WO2025179281A1 - Treatment of cardiovascular disease with antxr1 antibodies - Google Patents

Abstract

Disclosed herein are antibodies and antigen binding fragments that bind to ANTXR1, and methods of using the same to treat cardiovascular disease. In some examples the disclosed antibodies and antigen binding fragments bind to the extracellular domain of ANTXR1. In further examples the antibodies or antigen binding fragments block the interaction between ANTXR1 and collagen, including type I or type VI collagens. In some aspects administration of a therapeutically effective amount of these antibodies can be used to prevent the maladaptive sequelae caused by a myocardial infarction, or other cardiovascular diseases.

Description

4239-108688-03 TREATMENT OF CARDIOVASCULAR DISEASE WITH ANTXR1 ANTIBODIES CROSS REFERENCE TO RELATED APPLICATIONS [0001] This application claims priority to U.S. Provisional Application No.63/557,175, filed February 23, 2024, which is incorporated by reference in its entirety. FIELD [0002] This relates to the field of cardiovascular disease, particularly to the use of antibodies and antigen binding fragments that specifically bind ANTXR1 to treat or inhibit cardiovascular disease. ACKNOWLEDGMENT OF GOVERNMENT SUPPORT [0003] This invention was made with government support under ZIA BC010484 awarded by the National Institutes of Health. The government has certain rights in the invention. INCORPORATION OF ELECTRONIC SEQUENCE LISTING [0004] The electronic sequence listing is submitted as an XML file named “4239_108688_30_Sequenc e_Listing.xml” (68,626 bytes), created on February 23, 2025, is herein incorporated by reference in its entirety. BACKGROUND [0005] Heart disease has remained the leading cause of mortality worldwide for the last 20 years, resulting in 9 million deaths per year. According to the American Heart Association more than 6 million Americans are living with heart failure. In the US, the direct and indirect healthcare expenditures for patients with this condition is approximately $26 billion annually. Up to one-half of myocardial infarction (MI) patients will develop heart failure within 5 years, and two-thirds will not make a complete recovery. When end-stage failure occurs, heart transplantation or implantation of a left ventricular assist device (LVAD) are the only available treatment options. Unfortunately, heart conditions can continue to worsen in patients with LVADs and many patients are ineligible for LDAVs due to other underlying medical conditions. Importantly, heart transplant is not realistic as a standard therapy because of the lack of donors worldwide and the surgical complexities. Therefore, there is an urgent unmet medical need for improved myocardial infarction therapies. 4239-108688-03 SUMMARY [0006] Provided herein is a method of treating, or reducing the risk of, cardiovascular disease in a subject. The method comprises administering to a subject with or at risk of cardiovascular disease a therapeutically effective amount of an antibody or antigen binding fragment thereof that specifically binds to the extracellular domain of Anthrax Toxin Receptor 1 (ANTXR1) on the cell surface, to treat or reduce the risk of the cardiovascular disease in the subject. In some aspects, the cardiovascular disease is ischemic heart disease, progressive heart failure, atherosclerosis, coronary artery disease, myocardial ischemia, myocardial infarction, or hypertension. [0007] In some aspects, the antibody or antigen binding fragment comprises a heavy chain variable region (VH) comprising a heavy chain complementarity determining region (HCDR)1, a HCDR2, and a HCDR3 set forth as SEQ ID NOs: 3, 4, and 5, respectively, and a light chain variable region (VL) comprising a light chain complementarity determining region (LCDR)1, a LCDR2, and a LCDR3 set forth as SEQ ID NOs: 6, 7, and 8, respectively. In some aspects, the antibody or antigen binding fragment comprises a VH comprising a HCDR1, a HCDR2, and a HCDR3 set forth as SEQ ID NOs: 13, 14, and 15, respectively, and a VL comprising a LCDR1, a LCDR2, and a LCDR3 set forth as SEQ ID NOs: 16, 17, and 18, respectively. In some aspects, the antibody or antigen binding fragment comprises a VH comprising a HCDR1, a HCDR2, and a HCDR3 set forth as SEQ ID NOs: 24, 25, and 26, respectively, and a VL comprising a LCDR1, a LCDR2, and a LCDR3 set forth as SEQ ID NOs: 27, 28, and 29, respectively. [0008] In some aspects, the antibody is administered to the subject, and the antibody comprises a comprises a recombinant constant domain comprising a modification that disrupts Fc receptor binding, such as a LALA-PG mutation according to the EU numbering system. [0009] In some aspects, treating the subject inhibits progression of cardiovascular disease in the subject, such as by slowing progressive heart failure in the subject. BRIEF DESCRIPTION OF THE FIGURES [0010] The foregoing and other features and advantages of this disclosure will become more apparent from the following detailed description of several aspects which proceeds with reference to the accompanying figures. 4239-108688-03 [0011] FIGs.1A-1H. Expression of ANTXR1 in heart post-injury. A, Immunofluorescence staining of ANTXR1 and TNNI3 (cardiac troponin) in human LV following MI. The ANTXR1 positive image was taken from a “focal hotspot” in the infarct zone. Inset: Non-binding IgG control captured at same magnification. Bar = 100 µm. B, Immunoblotting of remote or infarct region from LV of failing human heart post-MI. C, scRNAseq dotplots comparing ANTXR1 levels in CFs from HCM, DCM and non-failing (NF) hearts. THBS4 and POSTN, markers of activated fibroblasts, served as positive controls. D, Immunofluorescence staining of ANTXR1 and TNNI3 in LV specimens from NF, HCM or DCM patients. Bar = 100 µm. E-F, Immunoblots detecting ANTXR1 protein in human NF, HCM, and DCM LV specimens (E) and relative quantification (F). G, Immunoblotting for ANTXR1 in mouse sham controls and MI hearts at different time points post-LAD ligation. GAPDH served as a loading control in (B), (E) and (G). H, Immunofluorescence staining for ANTXR1 and TNNT2 in mouse heart 7 days post-MI. RV: Right ventricle, LV: left ventricle, LA: left atrium. Bar = 500 µm (top panel) or 50 µm (bottom panel). [0012] FIGs.2A-2I. Genetic and pharmacologic antagonism of ANTXR1 prevents heart failure. A, Echocardiography monitoring of left ventricular EF% and FS% 28 days post-MI in ANTXR1 WT and KO mice. n=5/group (baseline) or 6-8/group (day 28). B, Experimental design for MI model with T8Ab treatment. Vehicle (control) or T8Ab treatments (arrowheads) began one day post-MI. C, Representative echocardiography tracings at baseline and 42 days post-MI with and without T8Ab. D, EF% and FS% at baseline, and day 1 or 42 post-MI. n=18/group. E, Kaplan–Meier survival analysis post-MI in mice treated with vehicle or T8Ab. P values were from a log-rank (Mantel-Cox) test. n=17-18. F, Experimental design for ATII/PE model. Vehicle or T8Ab treatments (15 mg/kg 3x/week, arrowheads) began one day post-ATII. G, EF%, global longitudinal strain (GLS) and ratio of early diastolic mitral inflow velocity to early diastolic mitral annulus velocity (MV E/e') at day 28. n=15-19/group. H, Experimental design for HFD/L-NAME model of HFpEF. Vehicle or T8Ab treatments (15 mg/kg 3x/week, arrowheads) began one day post- ATII. I, Cardiac function assessment and endurance test results at 35 days post-HFD/L- NAME. Results represent mean ± SEM. An ordinary one-way ANOVA with Tukey’s post hoc test was used for multiple comparisons. n=15/group. *P<0.05, **P<0.01, ***P<0.001, ****P<0.0001. [0013] FIGs.3A-3N. T8Ab treatment following MI promotes a cardioprotective gene signature. A, UMAP display of cardiac cell subpopulations. The diminished blood EC population at MI-d7 is highlighted (blue circle). B, Trajectory analysis of the 6 cardiac 4239-108688-03 fibroblast subclusters. C, Violin plot showing Antxr1 and Postn expression in each annotated cell type. D, Violin plot showing the total Antxr1 mRNA expression in CFs from MI-day7/14 versus sham. E, Bar graph showing % increase of Antxr1-positive CF4-6 cells after MI- day7/14 versus sham. F, GO analysis comparing pathway activation in CF1-3 versus CF4-6 at MI-d7. G, Co-IF staining for ANTXR1, THBS4 and TNNT2 in LV at day 7 post-MI. Bar=200 µm. H-I, Heat maps showing gene expression changes in the MI-d7+T8Ab and MI- d7+vehicle groups compared to sham (H) and the MI-d14+T8Ab and MI-d14+vehicle groups compared to sham (I). J-K, Violin plots showing the average expression of all genes upregulated by T8Ab at MI-d7 (J) and downregulated by T8Ab at MI-d14 (K) in panel H and I, respectively. inc., increased; dec., decreased. L-M, Violin plots showing Postn (l) and Meox1 (m) expression. N, qRT-PCR validation of Meox1 mRNA expression. P values: one- way ANOVA (RT-PCR) or Wilcoxon test (Violin plots). *P<0.05, **P<0.01, ***P<0.001, ns: non-significant. [0014] FIGs.4A-4J. T8Ab treatment promotes a cardioprotective gene signature in hypertension. A, UMAPs display cardiac cell subpopulations for each treatment group. B, Trajectory analysis of the cardiac fibroblast subclusters. C, Violin plot showing the relative Antxr1 and Postn expression in each annotated cell type. D, Bar graph indicates % increase in Antxr1 positive CF4,6 cells versus all the cells after 28 days of ATII/PE. E, Co-IF staining for ANTXR1 and THBS4 in the LV 28 days post-ATII/PE. Bar = 200 µm. F, GO analysis comparing enriched pathways in CF1-3 versus CF4,6 post-ATII/PE exposure. G, Volcano plot showing gene expression changes in response to T8Ab treatment in the Sham control and ATII/PE treated groups. H, Co-IF staining for CHP and WGA in LV after 28 days of ATII/PE. Bar = 50 µm. I, Quantification of CHP staining. Data represent the mean ± SEM from independent biological samples each indicated with a different color/shape. J, Violin plot showing Cthcr1, Comp, and Acta2 expression. K, qRT-PCR validation of Cthcr1, Comp, and Acta2 mRNA expression. P values were assessed using an unpaired, two tailed t-test (D) one-way ANOVA (I, K) or Wilcoxon test (J). *P<0.05, ***P<0.001. [0015] FIGs.5A-5L. T8Ab blocks TGFβ signaling in primary CFs. A, Immunoblot of ANTXR1 in CF under low serum (LS) conditions. B, qRT-PCR analysis of Antxr1 mRNA expression in CF in response to LS/TGFβ treatment. C, Gel contraction assay showing the impact of T8Ab treatment on CF response to TGFβ1. T8Ab1: L2. D, Quantification of the gel contraction assay. E, Immunoblotting of ANTXR1 WT and KO CF following LS/TGFβ1 treatment. F, SMAD2/3 and YAP IF staining of ANTXR1 wildtype (top 3 rows) or KO (bottom row) CF 1 hour post-treatment with LS/TGFβ1. N.S. IgG: Non-specific IgG. Bar = 4239-108688-03 20 µm. G-H, Quantification of SMAD2/3 (G) and YAP (H) IF staining. I, Immunoblotting of TGFBRs in ANTXR1 WT and KO CF treated with LS/TGFβ1. J, Rescue of TGFβ signaling by restoring ANTXR1 expression in the KO CFs. K, Comparison of T8Ab1 (L2) activity on TGFβ signaling in ANTXR1 WT or KO mouse CF (mCF) by immunoblotting. L, The effect of T8Abs on TGFβ signaling in human primary CF (hCF). For immunoblots, H3 antibody served as a loading control. Data represent mean ± SEM from independent biological replicates. P values: one-way ANOVA. ***P<0.001, ****P<0.0001. [0016] FIGs.6A-6C. Model illustrating ANTXR1’s role in TGFβ1 driven cardiac fibrosis. A, ANTXR1 upregulation in activated CFs following cardiac insult enhances ECM remodeling via TGFβ pathway activation while T8Abs block ECM synthesis and uptake. While not shown here, during normal physiology, or in early stages of injury before TGFβ1 has been fully activated, ANTXR1 blockade may induce ECM synthesis. B, ANTXR1 regulates TGFβ1 signaling by interacting with TGFBR1 during cardiac stress. C, T8Ab treatment disrupts the ANTXR1-TGFBR1 complex, leading to downregulated YAP and SMAD2/3 signaling. [0017] FIG.7. Localization of ANTXR1 in human left ventricle post-myocardial infarction. Immunofluorescence staining was performed on border zone (region between scar and remote area) of a LV sample taken from the failing heart of a 55-year-old transplant patient ~2.5 months following myocardial infarction. Note that ANTXR1 was generally enriched near regions with high levels of denatured collagen, as detected with a collagen hybridizing peptide (CHP). Anti-TNNI3 (cardiac troponin) antibodies were used to label cardiomyocytes. Bar: 2 mm. [0018] FIG.8. Localization of ANTXR1 in mouse heart post-myocardial infarction. Immunofluorescence staining for ANTXR1 and TNNT2 was performed on hearts taken at various time points following myocardial infarction (MI). Sham controls (surgery without MI) and MI-hearts taken from ANTXR1 KO mice were both taken at d7 post-surgery and used to demonstrate specificity. Bar: 1 mm. [0019] FIGs.9A-9B. T8Ab prevents fibrosis following hypertension. A, Picrosirius red staining was used to monitor fibrosis after 28 days of exposure to ATII/PE or saline (sham). Treatments with vehicle or T8Ab were administered 3x per week as depicted in FIG. 2F. A representative example from each group is shown. Bar: 1 mm. B, Quantification of the Picrosirius staining. Data shown represent the mean ± standard deviation (SD). N=5/group (vehicle) or 9-10/group (ATII/PE). p-values were assessed using a one-way ANOVA. **** p < 0.0001. 4239-108688-03 [0020] FIG.10. T8Ab-FI preserves heart function following hypertension. Echocardiography was used to evaluate the ejection fraction (EF %), fractional shortening (FS %) and diastolic function (MV E/e՛) in mice after 28 days of exposure to ATII/PE or saline (sham). Heart weight/body weight (HW/BW) ratios were taken at study end. Treatments with vehicle or Fc-inactive T8Ab (T8Ab-FI) were administered 3x per week as depicted in FIG.2F. Data shown represent the mean ± SEM. P values were assessed using a one-way ANOVA with a Tukey’s post hoc test. *P < 0.05, ****P < 0.0001. [0021] FIGs.11A-11C. HFD/L-NAME treatment induces glucose intolerance and arterial stiffness. A, A glucose tolerance test was used to measure blood glucose levels following a bolus injection of glucose administered 35 days after placing mice on a regular diet + vehicle or a high fat diet (HFD) + L-NAME. n=9-10/group. P values represent nearest data point vs. regular diet at same time point. While P values are significant between mice on a regular diet and those on a HFD/L-NAME + vehicle diet at various time points, all P values between the HFD/L-NAME + vehicle and the HFD/L-NAME + T8Ab are non-significant (ns). B, Quantification of glucose intolerance in A was determined from the area under the curve. Note that T8Ab treatment did not impact glucose intolerance. C, Pulse wave velocity (PWV), was used to determine arterial stiffness and verify the hypertensive activity of L- NAME. Data shown represent the mean ± SEM. P values were assessed using a one-way ANOVA with a Tukey’s post hoc test. **P < 0.01, ***P < 0.001, ****P < 0.0001, ns: non- significant. [0022] FIGs.12A-12F. Single cell characterization of cell populations following myocardial infarction. A, A dot plot displays enriched markers for each major cell population. B, Proportions of each major cell cluster across the 5 scRNAseq groups. C, Violin plots showing the relative expression of Cilp, Postn, Thbs4 and Antxr1 in each of the 6 cardiac fibroblast subclusters. D, Perturbations in the CF1-3 and CF4-6 fractions as a % of the total CF population in the Sham, MI-d7 or MI-d14 groups. *P < 0.05, **P < 0.01. E, UMAP plot of subclustered cells from all groups in the MI study combined. The key for the color annotations is shown in B, and the six cardiac fibroblasts subclusters are numbered. F, UMAP plots showing the relative mRNA expression of Cilp, Postn, Thbs4 and Antxr1 in each of the cell populations. [0023] FIGs.13A-13B. Gene expression alterations in epicardial and smooth muscle cells in response to MI and T8Ab treatment. Volcano plots depicting differentially expressed genes in epicardial cells (A) or smooth muscle cells (B) in response to MI at d14 4239-108688-03 vs. sham (left panel) or T8Ab vs. vehicle treatment following MI (right panel). The highlighted genes represent those whose altered expression after MI was reversed by T8Ab treatment. [0024] FIGs.14A-14D. Alterations in gene expression in CFs in response to myocardial infarction. A-B, Volcano plots depicting genes altered in CFs at d7 (A) or d14 (B) post-MI. Selected genes known to be induced in response to MI are highlighted. C-D, Pathway alterations in CF at d7 (C) or d14 (D) post-MI. [0025] FIGs.15A-15B. ANTXR1 promotes collagen remodeling following myocardial infarction. A, Immunofluorescence staining with a collagen hybridizing peptide (CHP) was used to evaluate the levels of denatured collagen in the left ventricular wall of ANTXR1 wildtype (WT) and knockout (KO) at day 7 or 14 post-myocardial infarction (MI). All cardiac fibroblasts were labelled with wheat germ agglutinin (WGA). B, Quantification of staining shown in A. Data represent the mean ± SEM from independent hearts samples indicated by the use of different colors/shapes. P values were assessed using a one-way ANOVA. *P < 0.05, **P < 0.01, ****P < 0.0001. [0026] FIGs.16A-16B. Pathway alterations in CFs in response to myocardial infarction. A-B, Pathway analysis performed on CFs of the indicated groups at d7 (A) or d14 (B) post-MI. Note that T8Ab treatment largely reversed pathway activation by day 14 post- MI. [0027] FIGs.17A-17B. SMAD3 phosphorylation after MI is significantly reduced in ANTXR1 KO mice. A, Immunofluorescence staining of nuclear pSMAD3 levels in the infarct region of ANTXR1 wildtype (WT) and knockout (KO) mice 14 days post-MI. Troponin staining shows the cardiomyocytes outside of the infarcted area. Bar: 50 µm. B, Quantification of the mean fluorescence intensity (MFI) of the nuclear pSMAD3 staining. Note, the nuclear counterstaining with DAPI verified the nuclear location of pSMAD3. Data represent the mean ± SEM. P values were assessed using a one-way ANOVA. *P < 0.05. [0028] FIGs.18A-18E. T8Ab induced alterations in blood endothelial cells (ECs) and macrophages following MI. A, Percentage of blood ECs compared to total cells in the sham group versus the MI group following vehicle or T8Ab treatment at day 7 post surgery. *P < 0.05, **P < 0.01. ns, not significant. B-C, Heat map showing genes upregulated or downregulated in blood ECs at day 7 (B) or 14 (C) in vehicle or T8Ab treated mice versus sham controls. Note that T8Ab treatment largely reversed the gene expression alterations in response to MI at both the d7 and d14 time point. D, Graph showing the percentage of macrophages at day 7 and 14 MI. *P < 0.05, **P < 0.01. ns, non-significant. E, Pathway 4239-108688-03 alterations in macrophages at day 7 post MI in response to T8Ab treatment. [0029] FIGs.19A-19F. Single cell characterization of cardiac cell populations following ATII/PE. A, Dot plot displaying enriched markers for each major cell population. B, Proportions of each major cell cluster across the 4 scRNAseq groups. C, Violin plots showing the relative expression of Cilp, Postn, Thbs4 and Antxr1 in each of the indicated cardiac fibroblast subclusters. D, Perturbations in the CF1-3 and CF4&6 clusters as a % of the CF population caused by ATII/PE treatment compared to sham controls. ***p < 0.001. E, UMAP plot of subclustered cells from all groups in the ATII/PE study combined. The key for the color annotations is shown in B and numbers indicate the cardiac fibroblast subclusters. F, UMAP plots showing relative mRNA expression of Cilp, Postn, Thbs4 and Antxr1 in each of the cell populations. [0030] FIGs.20A-20B. Alterations in gene expression in CFs in response to hypertension. A, Pathway alterations in CF after 28 days of exposure to ATII/PE or saline (sham). B, Volcano plots depicting genes altered in CFs following exposure to ATII/PE or saline. Some genes known to be induced by ATII/PE are highlighted. [0031] FIG.21. Alterations in gene expression in all cardiac cell populations in response to hypertension. Volcano plots depicting genes altered in all cardiac cell clusters 28 days after exposure to ATII/PE or saline (sham) and treatment with vehicle or T8Ab. [0032] FIGs.22A-22B. CF transition into a myofibroblast-like state in response to TGFβ. A, RT-PCR analysis evaluating the expression of various known TGFβ responsive genes in CFs cultured in low serum (LS) and treated with TGFβ for 4h, 24h or 48. Control cells were cultured in complete media. B, Immunoblotting analysis verifying the induction of known TGFβ responsive genes, including pSMAD2, YAP and ACTA2, in CF treated with TGFβ. P-values were assessed using a one-way ANOVA. *P < 0.05, **P < 0.01, ***P < 0.001, ****P < 0.0001. ns, non-significant. [0033] FIG.23. MMP14 levels are reduced following ANTXR1 antagonism. Immunoblotting was assessing the level of MMP14 in ANTXR1 wildtype (WT) cardiac fibroblasts (CF) after T8Ab treatment, or ANTXR1 knockout (KO) CF following treatment with LS/TGFβ for 24 hours. Histone H3 served as a loading control. [0034] FIGs.24A-24D. | ANTXR1 and TGFBR1 are closely associated in CF. A, Immunoblotting of co-Immunoprecipitation (IP) experiments assessing the interaction between ANTXR1 and TGFBR1 in CF. Non-specific IgG was used as a non-binding control. B, Co-immunofluorescence staining assessing ANTXR1 and TGFBR1 in ANTXR1 wildtype (WT) and knockout (KO) cardiac fibroblasts (CF). Bar: 20 µm. C, Representative images of a 4239-108688-03 proximity ligation assay testing interactions between ANTXR1 and TGFBR1 on the surface of live ANTXR1 WT and KO CFs. Bar: 20 µm. D, Quantification of PLA assays. P-values were assessed using a one-way ANOVA. Data represent the mean ± SEM and are derived from independent biological replicates that are indicated by the use of different colors/shapes. ****P < 0.0001. ns, not significant. [0035] FIG.25. Overexpression of truncated ANTXR1 stabilizes TGFBR1 levels in cardiac fibroblasts . Immunoblots showing TGFBR1 and SMAD3 levels in ANTXR1 wildtype (WT), ANTXR1 knockout (KO), and ANTXR1 KO cardiac fibroblasts overexpressing ANTXR1 with a deletion of its cytosolic domain (ANTXR1-CyDel). H3 was used as a loading control. [0036] FIGs.26A-26B. T8Ab1 binds the surface of the ANTXR1 ECD. A, Antibody docking predicts K94 and R88 at the interface between T8Ab1 (L2) and the ECD of ANTXR1. B, Flow cytometry showing binding of T8Ab1 (L2) to CHO cells overexpressing full length wildtype (WT) ANTXR1 or mutant ANTXR1 containing single alanine mutations surrounding the predicted antibody binding site. The two mutations that block binding are highlighted in red. The m830 anti-ANTXR1 antibody was used as a positive control. [0037] FIGs.27A-27B. ANTXR1 neutralizing antibodies do not alter TGFβ signaling in macrophages. A, Immunoblotting showing endogenous ANTXR1 and TGFBR1 levels in bone marrow derived macrophages (BMDM) and cardiac fibroblasts (CF). The BMDM replicates were derived from 3 different donor mice, while the ANTXR1 wildtype cardiac fibroblasts (CF) replicates were from three independent biological samples. B, Immunoblotting showing the impact of non-specific IgG or T8Ab1 treatment on TGF-β1 signaling in BMDM as assessed by SMAD2 phosphorylation (p-SMAD3). H3 served as a loading control in A and B. [0038] FIG.28 shows Table 1, demographics of clinical samples. [0039] FIG.29 shows Table 2, echocardiographic parameters in ANTXR1 WT and KO mice. [0040] FIG.30 shows Table 3, echocardiographic parameters in T8Ab treated mice following MI. [0041] FIG.31 shows Table 4, echocardiographic and morphologic parameters in T8Ab treated hypertensive mice. [0042] FIG.32 shows Table 5, Echocardiographic and morphologic parameters in T8Ab- FI treated hypertensive mice. [0043] FIG.33 shows Table 6, Echocardiographic and morphologic parameters in 4239-108688-03 HFpEF. [0044] FIG.34 shows Table 7, T8Ab alterations in known cardioprotective and cardiotoxic genes. [0045] FIG.35 shows Table 8, primers used for qRT-PCR. [0046] FIG.36 shows Table 9, reagents used for proximity ligation assay. [0047] FIG.37. Col1a2-cre-ER2 mice express cre specifically in cardiac fibroblasts. [0048] FIG.38. ANTXR1 expression in fibroblasts promotes heart disease. ***P<0.001. [0049] FIG.39. T8Ab (L2) antibody improves outcomes in female mice following MI. **P<0.01. [0050] FIG.40. T8Ab (L2) antibody improve outcomes in hypertension model even when treatment is initiated after injury. *P<0.05, ****P<0.0001. SEQUENCES [0051] The nucleic and amino acid sequences listed herein are shown using standard letter abbreviations for nucleotide bases and amino acids. Only one strand of each nucleic acid sequence is shown, but the complementary strand is understood as included by any reference to the displayed strand. In the accompanying sequence listing: [0052] SEQ ID NO: 1 is the amino acid sequence of the VH of the L2 antibody. QVQLKESGPALVKPTQTLTLTCTFSGFSLSTSGGGVSWIRQPPGKALEWLAHIYSNDDKSYS TSLKTRLTISKDTSKNQVVLTMTNMDPVDTATYYCARGGYFLDYWGQGTLVTVSS [0053] SEQ ID NO: 2 is the amino acid sequence of the VL of the L2 antibody. DIELTQPPSVSVAPGQTARISCSGDNIGGIYVHWYQQKPGQAPVLVIYADSKRPSGIPERFS GSNSGNTATLTISGTQAEDEADYYCQSYDITSLVFGGGTKLTVL [0054] SEQ ID NOs: 3-8 are the amino acid sequences of the HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 of the L2 antibody, respectively. SEQ ID NO: 3 - TSGGGVS SEQ ID NO: 4 – HIYSNDDKSYSTSLKT SEQ ID NO: 5 – GGYFLDY SEQ ID NO: 6 – SGDNIGGIYVH SEQ ID NO: 7 - ADSKRPS SEQ ID NO: 8 - QSYDITSLV [0055] SEQ ID NO: 9 is the amino acid sequence of the heavy chain of the L2 antibody, 4239-108688-03 with LALA-PG substitutions. QVQLKESGPALVKPTQTLTLTCTFSGFSLSTSGGGVSWIRQPPGKALEWLAHIYSNDDKSYS TSLKTRLTISKDTSKNQVVLTMTNMDPVDTATYYCARGGYFLDYWGQGTLVTVSSASTKGPS VFPLAPSSKSTSGGTAALGCLVKDYFPEPVTVSWNSGALTSGVHTFPAVLQSSGLYSLSSVV TVPSSSLGTQTYICNVNHKPSNTKVDKKVEPKSCDKTHTCPPCPAPEAAGGPSVFLFPPKPK DTLMISRTPEVTCVVVDVSHEDPEVKFNWYVDGVEVHNAKTKPREEQYNSTYRVVSVLTVLH QDWLNGKEYKCKVSNKALGAPIEKTISKAKGQPREPQVYTLPPSRDELTKNQVSLTCLVKGF YPSDIAVEWESNGQPENNYKTTPPVLDSDGSFFLYSKLTVDKSRWQQGNVFSCSVMHEALHN HYTQKSLSLSPGK [0056] SEQ ID NO: 10 is the amino acid sequence of the light chain of the L2 antibody. DIELTQPPSVSVAPGQTARISCSGDNIGGIYVHWYQQKPGQAPVLVIYADSKRPSGIPERFS GSNSGNTATLTISGTQAEDEADYYCQSYDITSLVFGGGTKLTVLGQPKANPTVTLFPPSSEE LQANKATLVCLISDFYPGAVTVAWKADSSPVKAGVETTTPSKQSNNKYAASSYLSLTPEQWK SHRSYSCQVTHEGSTVEKTVAPTECS [0057] SEQ ID NO: 11 is the amino acid sequence of the VH of the m825 antibody. QVQLVQSGAEVKKPGTSVKVSCKVPGYTFSSYAISWVRQAPGQGLEWMGGIIPIFGTTNYAQ KFQGRVTITGDESTSTVYMELSSLRSEDTAVYYCARDTDYMFDYWGQGTLVTVSS [0058] SEQ ID NO: 12 is the amino acid sequence of the VL of the m825 antibody. SSELTQDPVVSVALGETVSITCQGDNLRDFYASWYQQKPGQAPLLVMYGKNRRPSGIPDRFS GSTSGNTLSLTITGAQAEDEADYYCSSRDNSKHVVFGGGTKVTVL [0059] SEQ ID NOs: 13-18 are the amino acid sequences of the HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 of the m825 antibody, respectively. SEQ ID NO: 13 – GYTFSSYA SEQ ID NO: 14 – IIPIFGTT SEQ ID NO: 15 – ARDTDYMFDY SEQ ID NO: 16 – NLRDFY SEQ ID NO: 17 – GKN SEQ ID NO: 18 – SSRDNSKHVV [0060] SEQ ID NO: 19 is the amino acid sequence of human ANTXR1. MATAERRALGIGFQWLSLATLVLICAGQGGRREDGGPACYGGFDLYFILDKSGSVLHHWNEI YYFVEQLAHKFISPQLRMSFIVFSTRGTTLMKLTEDREQIRQGLEELQKVLPGGDTYMHEGF ERASEQIYYENRQGYRTASVIIALTDGELHEDLFFYSEREANRSRDLGAIVYCVGVKDFNET QLARIADSKDHVFPVNDGFQALQGIIHSILKKSCIEILAAEPSTICAGESFQVVVRGNGFRH ARNVDRVLCSFKINDSVTLNEKPFSVEDTYLLCPAPILKEVGMKAALQVSMNDGLSFISSSV IITTTHCSDGSILAIALLILFLLLALALLWWFWPLCCTVIIKEVPPPPAEESEEEDDDGLPK KKWPTVDASYYGGRGVGGIKRMEVRWGEKGSTEEGAKLEKAKNARVKMPEQEYEFPEPRNLN NNMRRPSSPRKWYSPIKGKLDALWVLLRKGYDRVSVMRPQPGDTGRCINFTRVKNNQPAKYP LNNAYHTSSPPPAPIYTPPPPAPHCPPPPPSAPTPPIPSPPSTLPPPPQAPPPNRAPPPSRP PPRPSV 4239-108688-03 [0061] SEQ ID NO: 20 is the amino acid sequence of the heavy chain of the m825 antibody, with LALA-PG substitutions. QVQLVQSGAEVKKPGTSVKVSCKVPGYTFSSYAISWVRQAPGQGLEWMGGIIPIFGTTNYAQ KFQGRVTITGDESTSTVYMELSSLRSEDTAVYYCARDTDYMFDYWGQGTLVTVSSASTKGPS VFPLAPSSKSTSGGTAALGCLVKDYFPEPVTVSWNSGALTSGVHTFPAVLQSSGLYSLSSVV TVPSSSLGTQTYICNVNHKPSNTKVDKKVEPKSCDKTHTCPPCPAPEAAGGPSVFLFPPKPK DTLMISRTPEVTCVVVDVSHEDPEVKFNWYVDGVEVHNAKTKPREEQYNSTYRVVSVLTVLH QDWLNGKEYKCKVSNKALGAPIEKTISKAKGQPREPQVYTLPPSRDELTKNQVSLTCLVKGF YPSDIAVEWESNGQPENNYKTTPPVLDSDGSFFLYSKLTVDKSRWQQGNVFSCSVMHEALHN HYTQKSLSLSPGK [0062] SEQ ID NO: 21 is the amino acid sequence of the light chain of the m825 antibody. SSELTQDPVVSVALGETVSITCQGDNLRDFYASWYQQKPGQAPLLVMYGKNRRPSGIPDRFS GSTSGNTLSLTITGAQAEDEADYYCSSRDNSKHVVFGGGTKVTVLGQPKANPTVTLFPPSSE ELQANKATLVCLISDFYPGAVTVAWKADSSPVKAGVETTTPSKQSNNKYAASSYLSLTPEQW KSHRSYSCQVTHEGSTVEKTVAPTECS [0063] SEQ ID NO: 22 is the amino acid sequence of the VH of the m830 mAb. EVQLVESGGGVVQPGRSVRLSCAASGFTFSTYTMHWVRQAPGKGLEWVAIISNDGSNKYYAD PVRGRFTISRDNSKNTLYLQMNSLRAEDTAVYYCVRGSSWYRGNWFDPWGQGTLVTVSS [0064] SEQ ID NO: 23 is the amino acid sequence of the VL of the m830 mAb. DIQMTQSPSSLSASVGDRVTIACRASQTISRYLNWYQQKPGKAPKLLIYAASSLQSGVSSRF SGSGSGTEFTLTISSLQPEDFATYFCQQTYSPPITFGQGTRLEIKR [0065] SEQ ID NOs: 24-29 are the amino acid sequences of the HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 of the m830 antibody, respectively. SEQ ID NO: 24 – GFTFSTYT SEQ ID NO: 25 – ISNDGSNK SEQ ID NO: 26 – VRGSSWYRGNWFDP SEQ ID NO: 27 – QTISRY SEQ ID NO: 28 – AAS SEQ ID NO: 29 – QQTYSPPIT [0066] SEQ ID NO: 30 is the amino acid sequence of the heavy chain of the m825 antibody, with LALA-PG substitutions. EVQLVESGGGVVQPGRSVRLSCAASGFTFSTYTMHWVRQAPGKGLEWVAIISNDGSNKYYAD PVRGRFTISRDNSKNTLYLQMNSLRAEDTAVYYCVRGSSWYRGNWFDPWGQGTLVTVSSVSS ASTKGPSVFPLAPSSKSTSGGTAALGCLVKDYFPEPVTVSWNSGALTSGVHTFPAVLQSSGL YSLSSVVTVPSSSLGTQTYICNVNHKPSNTKVDKKVEPKSCDKTHTCPPCPAPEAAGGPSVF LFPPKPKDTLMISRTPEVTCVVVDVSHEDPEVKFNWYVDGVEVHNAKTKPREEQYNSTYRVV SVLTVLHQDWLNGKEYKCKVSNKALGAPIEKTISKAKGQPREPQVYTLPPSRDELTKNQVSL 4239-108688-03 TCLVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSDGSFFLYSKLTVDKSRWQQGNVFSCSV MHEALHNHYTQKSLSLSPGK [0067] SEQ ID NO: 31 is the amino acid sequence of the light chain of the m825 antibody. DIQMTQSPSSLSASVGDRVTIACRASQTISRYLNWYQQKPGKAPKLLIYAASSLQSGVSSRF SGSGSGTEFTLTISSLQPEDFATYFCQQTYSPPITFGQGTRLEIKRGQPKANPTVTLFPPSS EELQANKATLVCLISDFYPGAVTVAWKADSSPVKAGVETTTPSKQSNNKYAASSYLSLTPEQ WKSHRSYSCQVTHEGSTVEKTVAPTECS [0068] SEQ ID NOs: 32-53 are primer sequences. DETAILED DESCRIPTION I. Introduction [0069] Anthrax Toxin Receptor 1 (ANTXR1, also known as Tumor Endothelial Marker 8 or TEM8) is a highly conserved single-pass transmembrane receptor that was originally discovered based on its overexpression in tumor-associated vasculature, and was subsequently found to also be widely overexpressed in cancer-associated fibroblasts (CAFs) (see Szot, C. et al., J. Clin. Invest. (2018) 128:2927-43; Carson-Walter, E.B. et al., Cancer Res. (2001) 61:6649-55; Nanda, A. et al., Cancer Res. (2004) 64:817-20; St. Croix, B. et al., Science (2000) 289:1197-1202). Although ANTXR1 is expressed at low levels in normal adult tissues it is induced in vivo following ischemia insult (see Chaudhary, A. et al., Cancer Cell (2012) 21:212-26; Andersen, N.J. et al., PLoS One (2016) 11: e0146586). In cell culture, ANTXR1 is a stress induced molecule that increases in vascular cells and CAFs in response to serum and growth factor deprivation (see Chaudhary, A. et al., Cancer Cell (2012) 21:212-26). Using the mouse hindlimb ischemia model, ANTXR1 was found to be elevated up to 20-fold in muscle tissues following ischemia induced by femoral artery ligation (see Andersen, N.J. et al., PLoS One (2016) 11: e0146586). However, in the same studies ANTXR1 WT and KO mice demonstrated no difference in the extent of injury or ability to regenerate damaged muscle tissue, suggesting that targeting ANTXR1 would not be useful for treating ischemic tissue injury (see Andersen, N.J. et al., PLoS One (2016) 11: e0146586 figures 2A-2C). [0070] ANTXR1 also plays a role in the degradation and uptake of mature collagen I (Col1) and VI (see Nanda, A. et al., Cancer Res. (2004) 64:817-20; Cullen, M. et al., Cancer Res. (2009) 69:6021-26; and Hsu, et al., Nature Communications (2022) 13(1):7078. doi: 10.1038/s41467-022-34643-5)). For example, a gradual buildup in Col1, the most abundant 4239-108688-03 collagen, is found in both ANTXR1 KO mice (see Cullen, M. et al., Cancer Res. (2009) 69:6021-26) and in human GAPO patients with ANTXR1 homozygous null mutations (see Stranecky, V. et al., Am. J. Hum. Genet. (2013) 92:792-799). Recent studies have also revealed that injection of a collagen hydrogel derived from adult decellularized pig hearts can improve heart function in both small and large animal preclinical models (see Wassenaar, J.W. et al., J. Am. Coll. Cardiol. (2016) 67:1074-86; Diaz, M.D. et al., JACC Basic Transl. Sci. (2021) 6:350-61; Wang, X. et al., Adv. Healthc. Mater (2022) 11:e2102265; Seif- Naraghi, S.B. et al., Sci. Transl. Med. (2013) 5: 173ra125; Singelyn, J.M. et al., J. Am. Coll. Cardiol. (2012) 59:751-63). The Col1-enriched gel used for this therapy, called VentriGel, has also shown encouraging activity in phase I clinical studies (see Traverse, J.H. et al., JACC Basic Transl. Sci. (2019) 4:659-69). Unfortunately, this therapy requires direct injection of this “mature” collagen into the scar region of the heart via a catheter, which can be difficult to administer uniformly and requires an invasive puncture that can cause further damage. ANTXR1 neutralizing monoclonal antibodies (mAbs), which can be delivered through intravenous administration, can directly block the degradation and uptake of mature Col1. II. Abbreviations ATII Angiotensin II ANTXR1 Anthrax Toxin Receptor 1 CAF Cancer-associated fibroblasts CVD Cardiovascular disease CDR Complementary determining region Col1 Collagen I ColVI Collagen VI DAPI 4',6-diamidino-2-phenylindole e/e’ E/e’ ratio EF Ejection fraction FS Fractional Shortening KO Knockout LAD Left anterior descending artery LVAD Left ventricular assist device LVIDs End-systolic left ventricular (LV) internal diameters (ID) LVIDd End-diastolic left ventricular (LV) internal diameters (ID) 4239-108688-03 LVvd Left ventricular diastolic volume LVvs Left ventricular end-systolic volume mAbs Monoclonal antibodies MI Myocardial Infarction ns Non-significant PE Phenylephrine hydrochloride TEM8 Tumor Endothelial Marker 8 WT Wildtype III. Summary of Terms [0071] Unless otherwise noted, technical terms are used according to conventional usage. Definitions of many common terms in molecular biology may be found in Krebs et al. (eds.), Lewin’s genes XII, published by Jones & Bartlett Learning, 2017. As used herein, the singular forms “a,” “an,” and “the,” refer to both the singular as well as plural, unless the context clearly indicates otherwise. For example, the term “an antigen” includes singular or plural antigens and can be considered equivalent to the phrase “at least one antigen.” As used herein, the term “comprises” means “includes.” It is further to be understood that any and all base sizes or amino acid sizes, and all molecular weight or molecular mass values, given for nucleic acids or polypeptides are approximate, and are provided for descriptive purposes, unless otherwise indicated. Although many methods and materials similar or equivalent to those described herein can be used, particular suitable methods and materials are described herein. In case of conflict, the present specification, including explanations of terms, will control. In addition, the materials, methods, and examples are illustrative only and not intended to be limiting. To facilitate review of the various aspects, the following explanations of terms are provided: [0072] Administration: To provide or give to a subject an agent, for example, a composition that includes a monoclonal antibody that specifically binds ANTXR1, by any effective route. Exemplary routes of administration include, but are not limited to, oral, injection (such as subcutaneous, intramuscular, intradermal, intraperitoneal, and intravenous), sublingual, rectal, transdermal (for example, topical), intranasal, vaginal, pericardial, intracoronary, intramyocardial, and inhalation routes. Typically, the antibodies and antigen binding fragments are administered intravenously. [0073] Anthrax Toxin Receptor 1 (ANTXR1): Also known as Tumor Endothelial Marker 8 (TEM8), ANTXR1 is a highly conserved, integrin-like, single-pass transmembrane 4239-108688-03 receptor that was originally discovered based on its overexpression in tumor-associated vasculature and was subsequently found to also be widely overexpressed in cancer-associated fibroblasts (CAFs) (Szot et al., J. Clin. Invest. (2018) 128:2927-43; Carson-Walter et al., Cancer Res. (2001) 61: 6649-55; Nanda et al., Cancer Res. (2004) 64:817-20; St Croix et al., Science (2000) 289:1197-1202). Unlike vascular endothelial growth factor (VEGF), VEGF receptor (VEGFR), and many other key angiogenesis regulators, ANTXR1 is not required for developmental angiogenesis, wound healing, or normal physiological angiogenesis of the corpus luteum (St Croix et al., Science, 289(5482):1197-1202, 2000; Nanda et al., Cancer Res., 64(3):817-820, 2004). ANTXR1 is expressed at low levels in normal adult tissues and has been reported to be induced in vivo following ischemia insult (Chaudhary, et al., Cancer- Cell (2012) 21:212-26; Anderson, et al., PLoS One (2016) 11:e0146586). In cell culture ANTXR1 is a stress induced molecule that increases in vascular cells and CAFs in response to serum and growth factor deprivation (Chaudhary, et al., Cancer Cell (2012) 21:212-26, Hsu, et al., Nature Communications (2022) 13(1):7078. doi: 10.1038/s41467-022-34643-5). ANTXR1 also functions as a cell-surface receptor for Anthrax toxin, and shares 58% amino acid identify with CMG2 (also known as ANTXR2), which is a second receptor for Anthrax toxin protein (Scobie et al., Proc. Natl. Acad. Sci. U.S.A., 100(9):5170-5174, 2003). [0074] ANTXR1 protein sequence is known (see, for example, GENBANK® Accession No. NP_115584.1, incorporated by reference herein as present in the database on October 21, 2022). Additionally, exemplary nucleic acid sequences encoding ANTXR1 protein are known (see, for example, GENBANK® Accession No. NM_032208.2, incorporated by reference herein as present in the database on October 21, 2022; see also for example, GENBANK® Accession No. NM_032208.3 incorporated by reference herein as present in the database on October 21, 2022). In one example, ANTXR1 is a polypeptide having an amino acid sequence set forth as SEQ ID NO: 19. The ANTXR1 extracellular domain is the portion of ANTXR1 that extends into the extracellular space, approximately amino acids 28- 320 of SEQ ID NO: 19. [0075] Antibody and Antigen Binding Fragment: An immunoglobulin, antigen- binding fragment, or derivative thereof, that specifically binds and recognizes an analyte (antigen) such as ANTXR1. The term “antibody” is used herein in the broadest sense and encompasses various antibody structures, including but not limited to monoclonal antibodies, polyclonal antibodies, multispecific antibodies (e.g., bispecific antibodies), and antigen binding fragments, so long as they exhibit the desired antigen-binding activity. 4239-108688-03 [0076] Non-limiting examples of antibodies include, for example, intact immunoglobulins and variants and fragments thereof that retain binding affinity for the antigen. Examples of antigen binding fragments include but are not limited to Fv, Fab, Fab', Fab'-SH, F(ab')₂; diabodies; linear antibodies; single-chain antibody molecules (e.g. scFv); and multispecific antibodies formed from antibody fragments. Antibody fragments include antigen binding fragments either produced by the modification of whole antibodies or those synthesized de novo using recombinant DNA methodologies (see, e.g., Kontermann and Dübel (Eds.), Antibody Engineering, Vols.1-2, 2^nd ed., Springer-Verlag, 2010). [0077] Antibodies also include genetically engineered forms such as chimeric antibodies (such as humanized murine antibodies) and heteroconjugate antibodies (such as bispecific antibodies). [0078] An antibody may have one or more binding sites. If there is more than one binding site, the binding sites may be identical to one another or may be different. For instance, a naturally-occurring immunoglobulin has two identical binding sites, a single-chain antibody or Fab fragment has one binding site, while a bispecific or bifunctional antibody has two different binding sites. [0079] Typically, a naturally occurring immunoglobulin has heavy (H) chains and light (L) chains interconnected by disulfide bonds. Immunoglobulin genes include the kappa, lambda, alpha, gamma, delta, epsilon and mu constant region genes, as well as the myriad immunoglobulin variable domain genes. There are two types of light chain, lambda (λ) and kappa (κ). There are five main heavy chain classes (or isotypes) which determine the functional activity of an antibody molecule: IgM, IgD, IgG, IgA and IgE. [0080] Each heavy and light chain contains a constant region (or constant domain) and a variable region (or variable domain). In combination, the heavy and the light chain variable regions specifically bind the antigen. [0081] References to “VH” or “VH” refer to the variable region of an antibody heavy chain, including that of an antigen binding fragment, such as Fv, scFv, dsFv or Fab. References to “VL” or “VL” refer to the variable domain of an antibody light chain, including that of an Fv, scFv, dsFv or Fab. [0082] The VH and VL contain a “framework” region interrupted by three hypervariable regions, also called “complementarity-determining regions” or “CDRs” (see, e.g., Kabat et al., Sequences of Proteins of Immunological Interest, 5^th ed., NIH Publication No.91-3242, Public Health Service, National Institutes of Health, U.S. Department of Health and Human 4239-108688-03 Services, 1991). The sequences of the framework regions of different light or heavy chains are relatively conserved within a species. The framework region of an antibody, that is the combined framework regions of the constituent light and heavy chains, serves to position and align the CDRs in three-dimensional space. [0083] The CDRs are primarily responsible for binding to an epitope of an antigen. The amino acid sequence boundaries of a given CDR can be readily determined using any of a number of well-known schemes, including those described by Kabat et al. (Sequences of Proteins of Immunological Interest, 5^th ed., NIH Publication No.91-3242, Public Health Service, National Institutes of Health, U.S. Department of Health and Human Services, 1991; “Kabat” numbering scheme), Al-Lazikani et al., (“Standard conformations for the canonical structures of immunoglobulins,” J. Mol. Bio., 273(4):927-948, 1997; “Chothia” numbering scheme), and Lefranc et al. (“IMGT unique numbering for immunoglobulin and T cell receptor variable domains and Ig superfamily V-like domains,” Dev. Comp. Immunol., 27(1):55-77, 2003; “IMGT” numbering scheme). The CDRs of each chain are typically referred to as CDR1, CDR2, and CDR3 (from the N-terminus to C-terminus), and are also typically identified by the chain in which the particular CDR is located. Thus, a VH CDR3 is the CDR3 from the VH of the antibody in which it is found, whereas a VL CDR1 is the CDR1 from the VL of the antibody in which it is found. Light chain CDRs are sometimes referred to as LCDR1, LCDR2, and LCDR3. Heavy chain CDRs are sometimes referred to as HCDR1, HCDR2, and HCDR3. [0084] In some aspects, a disclosed antibody includes a heterologous constant domain. For example, the antibody includes a constant domain that is different from a native constant domain, such as a constant domain including one or more modifications, such as the “LS” mutations that increase antibody half-life, or the “LALA-PG” mutations that prevent binding to Fc-gamma receptors. [0085] A “monoclonal antibody” is an antibody obtained from a population of substantially homogeneous antibodies, that is, the individual antibodies comprising the population are identical and/or bind the same epitope, except for possible variant antibodies, for example, containing naturally occurring mutations or arising during production of a monoclonal antibody preparation, such variants generally being present in minor amounts. In contrast to polyclonal antibody preparations, which typically include different antibodies directed against different determinants (epitopes), each monoclonal antibody of a monoclonal antibody preparation is directed against a single determinant on an antigen. Thus, the modifier “monoclonal” indicates the character of the antibody as being obtained from a 4239-108688-03 substantially homogeneous population of antibodies, and is not to be construed as requiring production of the antibody by any particular method. For example, the monoclonal antibodies may be made by a variety of techniques, including but not limited to the hybridoma method, recombinant DNA methods, phage-display methods, and methods utilizing transgenic animals containing all or part of the human immunoglobulin loci, such methods and other exemplary methods for making monoclonal antibodies being described herein. In some examples monoclonal antibodies are isolated from a subject. Monoclonal antibodies can have conservative amino acid substitutions which have substantially no effect on antigen binding or other immunoglobulin functions. (See, for example, Greenfield (Ed.), Antibodies: A Laboratory Manual, 2^nd ed. New York: Cold Spring Harbor Laboratory Press, 2014.) [0086] A “humanized” antibody or antigen binding fragment includes a human framework region and one or more CDRs from a non-human (such as a mouse, rat, or synthetic) antibody or antigen binding fragment. The non-human antibody or antigen binding fragment providing the CDRs is termed a “donor,” and the human antibody or antigen binding fragment providing the framework is termed an “acceptor.” In one aspect, all the CDRs are from the donor immunoglobulin in a humanized immunoglobulin. Constant regions need not be present, but if they are, they can be substantially identical to human immunoglobulin constant regions, such as at least about 85-90%, such as about 95% or more identical. Hence, all parts of a humanized antibody or antigen binding fragment, except possibly the CDRs, are substantially identical to corresponding parts of natural human antibody sequences. [0087] A “chimeric antibody” is an antibody which includes sequences derived from two different antibodies, which typically are of different species. In some examples, a chimeric antibody includes one or more CDRs and/or framework regions from one human antibody and CDRs and/or framework regions from another human antibody. [0088] A “fully human antibody” or “human antibody” is an antibody which includes sequences from (or derived from) the human genome, and does not include sequence from another species. In some aspects, a human antibody includes CDRs, framework regions, and (if present) an Fc region from (or derived from) the human genome. Human antibodies can be identified and isolated using technologies for creating antibodies based on sequences derived from the human genome, for example by phage display or using transgenic animals (see, e.g., Barbas et al. Phage display: A Laboratory Manuel. 1^st Ed. New York: Cold 4239-108688-03 Spring Harbor Laboratory Press, 2004. Print.; Lonberg, Nat. Biotech., 23: 1117-1125, 2005; Lonenberg, Curr. Opin. Immunol., 20:450-459, 2008). [0089] A “bispecific antibody” is a recombinant molecule composed of two different antigen binding domains that consequently binds to two different antigenic epitopes. Bispecific antibodies include chemically or genetically linked molecules of two antigen- binding domains. The antigen binding domains can be linked using a linker. The antigen binding domains can be monoclonal antibodies, antigen-binding fragments (e.g., Fab, scFv), or combinations thereof. A bispecific antibody can include one or more constant domains, but does not necessarily include a constant domain. An example of a bispecific antibody is a bispecific single chain antibody including a scFv that specifically binds to ANTXR1 joined (via a peptide linker) to a scFv that specifically binds to an antigen other than ANTXR1. Another example is a bispecific antibody including a Fab that specifically binds to ANTXR1 joined to a scFv that specifically binds to an antigen other than ANTXR1. [0090] Cardiac Ejection Fraction (EF): the percentage of blood volume ejected in each cardiac cycle and is a representation of left ventricle (LV) systolic performance. It is calculated from the end-diastolic and end-systolic volumes of the left ventricle. The formula for calculating EF is: EF% = ((LV v,d-LV v,s)/LV v,d)*100. [0091] Cardiovascular disease (CVD): A group of diseases that includes, but is not limited to, atherosclerosis, coronary artery disease (CAD), angina pectoris (commonly known as "angina"), thrombosis, ischemic heart disease, coronary insufficiency, peripheral vascular disease, myocardial infarction, cerebrovascular disease (such as stroke), transient ischemic attack, arteriolosclerosis, small vessel disease, elevated cholesterol, intermittent claudication, hypertension, Heart Failure with preserved Ejection Fraction (HFpEF). [0092] Collagen: The collagen family includes at least 15 types of collagen, which are major components of the extracellular matrix. Type I collagen is the principal collagen found in skin and bone and consists of two type I α1 collagen subunits (COL1A1) and one type I α2 collagen (COL1A2) subunit. [0093] Conditions sufficient to form an immune complex: Conditions which allow an antibody or antigen binding fragment to bind to its cognate epitope to a detectably greater degree than, and/or to the substantial exclusion of, binding to substantially all other epitopes. Conditions sufficient to form an immune complex are dependent upon the format of the binding reaction and typically are those utilized in immunoassay protocols or those conditions encountered in vivo. See Greenfield (Ed.), Antibodies: A Laboratory Manual, 2^nd ed. New York: Cold Spring Harbor Laboratory Press, 2014, for a description of immunoassay 4239-108688-03 formats and conditions. The conditions employed in the methods are “physiological conditions” which include reference to conditions (e.g., temperature, osmolarity, pH) that are typical inside a living mammal or a mammalian cell. While it is recognized that some organs are subject to extreme conditions, the intra-organismal and intracellular environment normally lies around pH 7 (e.g., from pH 6.0 to pH 8.0, more typically pH 6.5 to 7.5), contains water as the predominant solvent, and exists at a temperature above 0°C and below 50°C. Osmolarity is within the range that is supportive of cell viability and proliferation. [0094] The formation of an immune complex can be detected through conventional methods, for instance immunohistochemistry (IHC), immunoprecipitation (IP), flow cytometry, immunofluorescence microscopy, ELISA, immunoblotting (for example, Western blot), magnetic resonance imaging (MRI), computed tomography (CT) scans, radiography, and affinity chromatography. [0095] Conservative variant: “Conservative” amino acid substitutions are those substitutions that do not substantially decrease the binding affinity of an antibody for an antigen (for example, the binding affinity of an antibody for ANTXR1). For example, a human antibody that specifically binds ANTXR1 can include at most about 1, at most about 2, at most about 5, at most about 10, or at most about 15 conservative substitutions and specifically bind the ANTXR1 polypeptide. The term conservative variation also includes the use of a substituted amino acid in place of an unsubstituted parent amino acid, provided that antibody retains binding affinity for ANTXR1. Non-conservative substitutions are those that reduce an activity or binding to ANTXR1. [0096] The following six groups are examples of amino acids that are considered to be conservative substitutions for one another: 1) Alanine (A), Serine (S), Threonine (T); 2) Aspartic acid (D), Glutamic acid (E); 3) Asparagine (N), Glutamine (Q); 4) Arginine (R), Lysine (K); 5) Isoleucine (I), Leucine (L), Methionine (M), Valine (V); and 6) Phenylalanine (F), Tyrosine (Y), Tryptophan (W). [0097] Contacting: Placement in direct physical association; includes both in solid and liquid form, which can take place either in vivo or in vitro. Contacting includes contact between one molecule and another molecule, for example the amino acid on the surface of one polypeptide, such as an antigen, that contacts another polypeptide, such as an antibody. 4239-108688-03 Contacting can also include contacting a cell for example by placing an antibody in direct physical association with a cell. [0098] Control: A reference standard. In some aspects, the control is a negative control, such as tissue sample obtained from a subject that does not have myocardial ischemia or a tissue sample from a tissue that is not ischemic. In other aspects, the control is a positive control, such as a tissue sample obtained from a patient diagnosed with myocardial ischemia, or a tissue sample from ischemic tissue. In still other aspects, the control is a historical control or standard reference value or range of values (such as a previously tested control sample, such as a group of patients with myocardial ischemia with known prognosis or outcome, or group of samples that represent baseline or normal values). [0099] A difference between a test sample and a control can be an increase or conversely a decrease. The difference can be a qualitative difference or a quantitative difference, for example a statistically significant difference. In some examples, a difference is an increase or decrease, relative to a control, of at least about 5%, such as at least about 10%, at least about 20%, at least about 30%, at least about 40%, at least about 50%, at least about 60%, at least about 70%, at least about 80%, at least about 90%, at least about 100%, at least about 150%, at least about 200%, at least about 250%, at least about 300%, at least about 350%, at least about 400%, or at least about 500%. [0100] Decrease or Reduce: To reduce the quality, amount, or strength of something; for example a reduction in cardiac disease in a patient. In one example, a therapy reduces myocardial ischemia or, or one or more symptoms associated with myocardial ischemia such as chest discomfort or nausea, for example as compared to the response in the absence of therapy. [0101] E/e’ Ratio (e/e’): The ratio of early diastolic mitral inflow velocity to early diastolic mitral annulus velocity. Used for the evaluation of LV filling pressure, and it has been used as a marker to diagnose diastolic heart failure. [0102] Epitope: An antigenic determinant. These are particular chemical groups or peptide sequences on a molecule that are antigenic, i.e. that elicit a specific immune response. An antibody specifically binds a particular antigenic epitope on a polypeptide. In some examples a disclosed antibody specifically binds to an epitope on ANTXR1. [0103] Expressed: Translation of a nucleic acid into a protein. Proteins may be expressed and remain intracellular, become a component of the cell surface membrane, or be secreted into the extracellular matrix or medium. [0104] Expression: Transcription or translation of a nucleic acid sequence. For 4239-108688-03 example, an encoding nucleic acid sequence (such as a gene) can be expressed when its DNA is transcribed into RNA or an RNA fragment, which in some examples is processed to become mRNA. An encoding nucleic acid sequence (such as a gene) may also be expressed when its mRNA is translated into an amino acid sequence, such as a protein or a protein fragment. In a particular example, a heterologous gene is expressed when it is transcribed into an RNA. In another example, a heterologous gene is expressed when its RNA is translated into an amino acid sequence. Regulation of expression can include controls on transcription, translation, RNA transport and processing, degradation of intermediary molecules such as mRNA, or through activation, inactivation, compartmentalization or degradation of specific protein molecules after they are produced. [0105] Expression Control Sequences: Nucleic acid sequences that regulate the expression of a heterologous nucleic acid sequence to which it is operatively linked. Expression control sequences are operatively linked to a nucleic acid sequence when the expression control sequences control and regulate the transcription and, as appropriate, translation of the nucleic acid sequence. Thus, expression control sequences can include appropriate promoters, enhancers, transcriptional terminators, a start codon (ATG) in front of a protein-encoding gene, splice signals for introns, maintenance of the correct reading frame of that gene to permit proper translation of mRNA, and stop codons. The term “control sequences” is intended to include, at a minimum, components whose presence can influence expression, and can also include additional components whose presence is advantageous, for example, leader sequences and fusion partner sequences. Expression control sequences can include a promoter. [0106] Expression vector: A vector comprising a recombinant polynucleotide comprising expression control sequences operatively linked to a nucleotide sequence to be expressed. An expression vector comprises sufficient cis- acting elements for expression; other elements for expression can be supplied by the host cell or in an in vitro expression system. Nonlimiting examples of expression vectors include cosmids, plasmids (e.g., naked or contained in liposomes) and viruses (e.g., lentiviruses, retroviruses, adenoviruses, and adeno-associated viruses) that incorporate the recombinant polynucleotide. [0107] Fc region: The constant region of an antibody excluding the first heavy chain constant domain. Fc region generally refers to the last two heavy chain constant domains of IgA, IgD, and IgG, and the last three heavy chain constant domains of IgE and IgM. An Fc region may also include part or all of the flexible hinge N-terminal to these domains. For IgA and IgM, an Fc region may or may not include the tailpiece, and may or may not be bound by 4239-108688-03 the J chain. For IgG, the Fc region is typically understood to include immunoglobulin domains Cγ2 and Cγ3 and optionally the lower part of the hinge between Cγ1 and Cγ2. Although the boundaries of the Fc region may vary, the human IgG heavy chain Fc region is usually defined to include residues following C226 or P230 to the Fc carboxyl-terminus, wherein the numbering is according to Kabat. For IgA, the Fc region includes immunoglobulin domains Cα2 and Cα3 and optionally the lower part of the hinge between Cα1 and Cα2. [0108] Fibrosis: The formation or development of excess fibrous connective tissue in an organ or tissue as a reparative or reactive process, as opposed to a formation of fibrous tissue as a normal constituent of an organ or tissue. [0109] Fractional Shortening (FS): the percentage change in left ventricle (LV) cavity dimensions in each cardiac cycle. It is calculated from the left ventricular internal dimension end-diastolic and left ventricular internal dimension end-systolic of the left ventricle. The formula for calculating FS is: FS% = ((LVID,d-LVID,s)/LVID,d)*100. [0110] IgA: A polypeptide belonging to the class of antibodies that are substantially encoded by a recognized immunoglobulin alpha gene. In humans, this class or isotype includes IgA₁ and IgA₂. IgA antibodies can exist as monomers, polymers (referred to as pIgA) of predominantly dimeric form, and secretory IgA. The constant chain of wild-type IgA contains an 18-amino-acid extension at its C-terminus called the tail piece (tp). Polymeric IgA is secreted by plasma cells with a 15-kDa peptide called the J chain linking two monomers of IgA through the conserved cysteine residue in the tail piece. [0111] IgG: A polypeptide belonging to the class or isotype of antibodies that are substantially encoded by a recognized immunoglobulin gamma gene. In humans, this class includes IgG1, IgG2, IgG3, and IgG4. In mice, this class includes IgG1, IgG2a, IgG2b, and IgG3. [0112] Immune complex: The binding of antibody or antigen binding fragment (such as a scFv) to a soluble antigen forms an immune complex. The formation of an immune complex can be detected, for instance, via immunohistochemistry, immunoprecipitation, flow cytometry, immunofluorescence microscopy, ELISA, immunoblotting (for example, Western blot), magnetic resonance imaging, CT scans, X-ray and affinity chromatography. [0113] Inhibiting or Treating a Disease: A therapeutic intervention (for example, administration of a therapeutically effective amount of an antibody that specifically binds ANTXR1 or a conjugate thereof) that reduces a sign or symptom of a disease or pathological condition related to a disease (such as myocardial ischemia or myocardial infarction). Treatment can also induce remission or cure of a condition. In particular examples, treatment 4239-108688-03 includes preventing the progression of a disease, for example inhibiting cardiac fibrosis caused as a result of a myocardial infarction. Prevention does not require the disease be eliminated or halted, it is sufficient, for example, to slow the progression of the disease. [0114] Reducing a sign or symptom of a disease or pathological condition related to a disease, refers to any observable beneficial effect of the treatment. Reducing a sign or symptom associated with myocardial ischemia (such as cardiac fibrosis) can be evidenced, for example, by a delayed onset of clinical symptoms of the disease in a susceptible subject (such delayed tissue scarring) a reduction in severity of some or all clinical symptoms of the disease (such as reduced chest discomfort), a slower progression of the disease (for example by prolonging the life of a subject with myocardial ischemia), a reduction in the number of relapses of the disease, or by an improvement in the overall health or well-being of the subject. A “prophylactic” treatment is a treatment administered to a subject who does not exhibit signs of a disease or exhibits only early signs for the purpose of decreasing the risk of developing pathology. [0115] Ischemia/Reperfusion Injury: In addition to the immediate injury that occurs during deprivation of blood flow, ischemic/reperfusion injury involves tissue injury that occurs after blood flow is restored. Current understanding is that much of this injury is caused by chemical products and free radicals released into the ischemic tissues. [0116] When a tissue is subjected to ischemia, a sequence of chemical events is initiated that may ultimately lead to cellular dysfunction and necrosis. If ischemia is ended by the restoration of blood flow, a second series of injurious events ensue, producing additional injury. Thus, whenever there is a transient decrease or interruption of blood flow in a subject, the resultant injury involves two components—the direct injury occurring during the ischemic interval and the indirect or reperfusion injury that follows. When there is a long duration of ischemia, the direct ischemic damage, resulting from hypoxia, is predominant. For relatively short duration ischemia, the indirect or reperfusion mediated damage becomes increasingly important. In some instances, the injury produced by reperfusion can be more severe than the injury induced by ischemia per se. This pattern of relative contribution of injury from direct and indirect mechanisms has been shown to occur in all organs. [0117] Isolated: A biological component (such as a nucleic acid, peptide, protein or protein complex, for example an antibody) that has been substantially separated, produced apart from, or purified away from other biological components in the cell of the organism in which the component naturally occurs, that is, other chromosomal and extra-chromosomal DNA and RNA, and proteins. Thus, isolated nucleic acids, peptides and proteins include 4239-108688-03 nucleic acids and proteins purified by standard purification methods. The term also embraces nucleic acids, peptides and proteins prepared by recombinant expression in a host cell, as well as, chemically synthesized nucleic acids. An isolated nucleic acid, peptide or protein, for example an antibody, can be at least 50%, at least 60%, at least 70%, at least 80%, at least 90%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% pure. [0118] LALA-PG: Mutations in the constant region of an IgG antibody at L234A, L235A, and P329A, with numbering according to EU convention. In some examples making the LALA-PG substitutions disrupts Fc receptor binding. In some examples the IgG antibody is murine IgG2a. In other examples the IgG antibody is human IgG1. See Lo et al., J. Bio. Chem. (2017) 292:3900-08; Saunders Front. Immuno. (2019) 10:1296. [0119] Myocardial Infarction (MI): An event that occurs when blood stops flowing properly to part of the heart and the heart muscle is injured due to inadequate oxygen delivery. The most common triggering event is the disruption of an atherosclerotic plaque in an epicardial coronary artery, which leads to a clotting cascade, sometimes resulting in total occlusion of the artery. If impaired blood flow to the heart lasts long enough, it triggers a process called the ischemic cascade; the heart cells in the territory of the occluded coronary artery die, chiefly through necrosis. [0120] Myocardial Ischemia: A decrease in the blood supply to the heart, for example, caused by constriction or obstruction of one or more blood vessels due to atherosclerosis.. Myocardial ischemia can lead to direct ischemic injury of heart tissue due to cell death caused by reduced oxygen supply. Myocardial ischemia sometimes results from vasoconstriction or thrombosis or embolism. Myocardial ischemia can occur acutely, as during surgery, or from trauma to tissue incurred in accidents, injuries and war settings, for instance. It can also occur sub-acutely, as found in atherosclerotic peripheral vascular disease, where progressive narrowing of blood vessels leads to inadequate blood flow to the heart (and other tissues and organs. Myocardial ischemia can be caused by a myocardial infarction. [0121] Nucleic acid (molecule or sequence): A deoxyribonucleotide or ribonucleotide polymer or combination thereof including without limitation, cDNA, mRNA, genomic DNA, and synthetic (such as chemically synthesized) DNA or RNA. The nucleic acid can be double stranded (ds) or single stranded (ss). Where single stranded, the nucleic acid can be the sense strand or the antisense strand. Nucleic acids can include natural nucleotides (such as A, T/U, C, and G), and can include analogs of natural nucleotides, such as labeled nucleotides. 4239-108688-03 [0122] “cDNA” refers to a DNA that is complementary or identical to an mRNA, in either single stranded or double stranded form. [0123] “Encoding” refers to the inherent property of specific sequences of nucleotides in a polynucleotide, such as a gene, a cDNA, or an mRNA, to serve as templates for synthesis of other polymers and macromolecules in biological processes having either a defined sequence of nucleotides (i.e., rRNA, tRNA and mRNA) or a defined sequence of amino acids and the biological properties resulting therefrom. Thus, a gene encodes a protein if transcription and translation of mRNA produced by that gene produces the protein in a cell or other biological system. Both the coding strand, the nucleotide sequence of which is identical to the mRNA sequence and is usually provided in sequence listings, and non-coding strand, used as the template for transcription, of a gene or cDNA can be referred to as encoding the protein or other product of that gene or cDNA. Unless otherwise specified, a “nucleotide sequence encoding an amino acid sequence” includes all nucleotide sequences that are degenerate versions of each other and that encode the same amino acid sequence. Nucleotide sequences that encode proteins and RNA may include introns. [0124] Operably linked: A first nucleic acid sequence is operably linked with a second nucleic acid sequence when the first nucleic acid sequence is placed in a functional relationship with the second nucleic acid sequence. For instance, a promoter, such as the CMV promoter, is operably linked to a coding sequence if the promoter affects the transcription or expression of the coding sequence. Generally, operably linked DNA sequences are contiguous and, where necessary to join two protein-coding regions, in the same reading frame. [0125] Pharmaceutically acceptable carriers: The pharmaceutically acceptable carriers of use are conventional. Remington: The Science and Practice of Pharmacy, 22^nd ed., London, UK: Pharmaceutical Press, 2013, describes compositions and formulations suitable for pharmaceutical delivery of the disclosed agents. [0126] In general, the nature of the carrier will depend on the particular mode of administration being employed. For instance, parenteral formulations usually include injectable fluids that include pharmaceutically and physiologically acceptable fluids such as water, physiological saline, balanced salt solutions, aqueous dextrose, glycerol or the like as a vehicle. For solid compositions (e.g., powder, pill, tablet, or capsule forms), conventional non-toxic solid carriers can include, for example, pharmaceutical grades of mannitol, lactose, starch, or magnesium stearate. In addition to biologically neutral carriers, pharmaceutical compositions to be administered can contain minor amounts of non-toxic auxiliary 4239-108688-03 substances, such as wetting or emulsifying agents, added preservatives (such as non-natural preservatives), and pH buffering agents and the like, for example sodium acetate or sorbitan monolaurate. In particular examples, the pharmaceutically acceptable carrier is sterile and suitable for parenteral administration to a subject for example, by injection. In some aspects, the active agent and pharmaceutically acceptable carrier are provided in a unit dosage form such as a pill or in a selected quantity in a vial. Unit dosage forms can include one dosage or multiple dosages (for example, in a vial from which metered dosages of the agents can selectively be dispensed). [0127] Polypeptide: A polymer in which the monomers are amino acid residues that are joined together through amide bonds. When the amino acids are alpha-amino acids, either the L-optical isomer or the D-optical isomer can be used, the L-isomers being preferred. The terms "polypeptide" or “protein” as used herein are intended to encompass any amino acid sequence and include modified sequences such as glycoproteins. A polypeptide includes both naturally occurring proteins, as well as those that are recombinantly or synthetically produced. A polypeptide has an amino terminal (N-terminal) end and a carboxy-terminal end. In some aspects, the polypeptide is a disclosed antibody or a fragment thereof. [0128] Purified: The term purified does not require absolute purity; rather, it is intended as a relative term. Thus, for example, a purified peptide preparation is one in which the peptide or protein (such as an antibody) is more enriched than the peptide or protein is in its natural environment within a cell. In one aspect, a preparation is purified such that the protein or peptide represents at least 50% of the total peptide or protein content of the preparation, such as at least 80%, at least 90%, at least 95% or greater of the total peptide or protein content. [0129] Sequence identity: The identity between two or more nucleic acid sequences, or two or more amino acid sequences, is expressed in terms of the identity between the sequences. Sequence identity can be measured in terms of percentage identity; the higher the percentage, the more identical the sequences. Homologs and variants of a VL or a VH of an antibody that specifically binds a target antigen are typically characterized by possession of at least about 75% sequence identity, for example at least about 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% sequence identity counted over the full-length alignment with the amino acid sequence of interest. [0130] Any suitable method may be used to align sequences for comparison. Non- limiting examples of programs and alignment algorithms are described in: Smith and Waterman, Adv. Appl. Math.2(4):482-489, 1981; Needleman and Wunsch, J. Mol. Biol. 4239-108688-03 48(3):443-453, 1970; Pearson and Lipman, Proc. Natl. Acad. Sci. U.S.A.85(8):2444-2448, 1988; Higgins and Sharp, Gene, 73(1):237-244, 1988; Higgins and Sharp, Bioinformatics, 5(2):151-3, 1989; Corpet, Nucleic Acids Res.16(22):10881-10890, 1988; Huang et al. Bioinformatics, 8(2):155-165, 1992; and Pearson, Methods Mol. Biol.24:307-331, 1994. Altschul et al., J. Mol. Biol.215(3):403-410, 1990, presents a detailed consideration of sequence alignment methods and homology calculations. The NCBI Basic Local Alignment Search Tool (BLAST) (Altschul et al., J. Mol. Biol.215(3):403-410, 1990) is available from several sources, including the National Center for Biological Information and on the Internet, for use in connection with the sequence analysis programs blastp, blastn, blastx, tblastn, and tblastx. Blastn is used to compare nucleic acid sequences, while blastp is used to compare amino acid sequences. Additional information can be found at the NCBI web site. [0131] Generally, once two sequences are aligned, the number of matches is determined by counting the number of positions where an identical nucleotide or amino acid residue is present in both sequences. The percent sequence identity between the two sequences is determined by dividing the number of matches either by the length of the sequence set forth in the identified sequence, or by an articulated length (such as 100 consecutive nucleotides or amino acid residues from a sequence set forth in an identified sequence), followed by multiplying the resulting value by 100. [0132] Specifically bind: When referring to an antibody or antigen binding fragment, refers to a binding reaction which determines the presence of a target protein in the presence of a heterogeneous population of proteins and other biologics. Thus, under designated conditions, an antibody binds preferentially to a particular target protein, peptide or polysaccharide (such as an antigen present on the surface of a cell, for example ANTXR1 extracellular domain) and does not bind in a significant amount to other proteins present in the sample or subject. Specific binding can be determined by standard methods. See Harlow & Lane, Antibodies, A Laboratory Manual, 2^nd ed., Cold Spring Harbor Publications, New York (2013), for a description of immunoassay formats and conditions that can be used to determine specific immunoreactivity. [0133] With reference to an antibody-antigen complex, specific binding of the antigen and antibody has a K_D of less than about 10^-7 Molar, such as less than about 10^-8 Molar, 10^-9, or even less than about 10^-10 Molar. KD refers to the dissociation constant for a given interaction, such as a polypeptide ligand interaction or an antibody antigen interaction. For example, for the bimolecular interaction of an antibody or antigen binding fragment and an 4239-108688-03 antigen it is the concentration of the individual components of the bimolecular interaction divided by the concentration of the complex. [0134] The antibodies disclosed herein specifically bind only to a defined target (or multiple targets, in the case of a bispecific antibody). Thus, an antibody that specifically binds to ANTXR1 is an antibody that binds substantially to ANTXR1, including cells or tissue expressing ANTXR1, substrate to which the ANTXR1 is attached, or ANTXR1 in a biological specimen. It is, of course, recognized that a certain degree of non-specific interaction may occur between an antibody or conjugate including an antibody (such as an antibody that specifically binds ANTXR1 or conjugate including such antibody) and a non- target (such as a cell that does not express ANTXR1). Typically, specific binding results in a much stronger association between the antibody and protein or cells bearing the antigen than between the antibody and protein or cells lacking the antigen. Specific binding typically results in greater than 2-fold, such as greater than 5-fold, greater than 10-fold, or greater than 100-fold increase in amount of bound antibody (per unit time) to a protein including the epitope or cell or tissue expressing the target epitope as compared to a protein or cell or tissue lacking this epitope. Specific binding to a protein under such conditions requires an antibody that is selected for its specificity for a particular protein. A variety of immunoassay formats are appropriate for selecting antibodies or other ligands specifically immunoreactive with a particular protein. For example, solid-phase ELISA immunoassays are routinely used to select monoclonal antibodies specifically immunoreactive with a protein. [0135] Subject: Any mammal, such as humans, non-human primates, pigs, sheep, cows, rodents, and the like. In two non-limiting examples, a subject is a human subject or a murine subject. Thus, the term “subject” includes both human and veterinary subjects. [0136] Therapeutically effective amount: The amount of an agent (such as a ANTXR1 specific antibody) that alone, or together with one or more additional agents, induces the desired response, such as, for example treatment of myocardial ischemia or myocardial infarction in a subject. When administered to a subject, a dosage will generally be used that will achieve target tissue concentrations that has been shown to achieve a desired in vitro effect. Ideally, a therapeutically effective amount provides a therapeutic effect without causing a substantial cytotoxic effect in the subject. [0137] A therapeutically effective amount of a ANTXR1-specific antibody or antigen binding fragment as described herein that is administered to a human or veterinary subject will vary depending upon a number of factors associated with that subject, for example the overall health of the subject. A therapeutically effective amount can be determined by 4239-108688-03 varying the dosage and measuring the resulting therapeutic response, such as improved cardiac blood flow or cardiac ejection. Therapeutically effective amounts also can be determined through various in vitro, in vivo or in situ immunoassays. The disclosed agents can be administered in a single dose, or in several doses, as needed to obtain the desired response. However, the therapeutically effective amount of can be dependent on the source applied, the subject being treated, the severity and type of the condition being treated, and the manner of administration. [0138] Vector: A nucleic acid molecule as introduced into a host cell, thereby producing a transformed host cell. A vector may include nucleic acid sequences that permit it to replicate in a host cell, such as an origin of replication. A vector may also include one or more selectable marker genes and other genetic elements. IV. Methods of Treating, Reducing the Risk of, and Preventing Cardiovascular Disease [0139] Methods are provided for treating, reducing the risk of, or preventing, cardiovascular disease, such as progressive heart failure caused by myocardial infarction, high blood pressure and other forms of heart disease in a subject. The disclosed methods comprise administering to the subject a therapeutically effective amount of an antibody or antigen binding fragment thereof that specifically binds to the ANTXR1 extracellular domain on the cell surface as described herein (for example, administration of L2 mAb, m825 mAb, or m830 mAb). [0140] In some aspects, the method inhibits the progression of cardiovascular disease. In further aspects, the method inhibits cardiac fibrosis or development of cardiac fibrosis in the patient following myocardial infarction. In additional aspects, the antibody or antigen binding fragment is administered following myocardial infarction, such as within one day, one week, or one month, of myocardial infarction. [0141] In some aspects, formation of an immune complex between ANTXR1 and the antibody or antigen binding fragment treats the myocardial ischemia by reducing or preventing infiltration of immune cells into affected myocardium, activation of myofibroblasts, or maladaptive chronic regeneration and inflammation. [0142] In some aspects, the ANTXR1-specific antibody or antigen binding fragment inhibits a biological function or property of ANTXR1 protein in vivo, including, but not limited to, blocking the interaction between ANTXR1 and collagen. In some aspects the collagen is type I collagen. In other aspects the collagen is type VI collagen. In several 4239-108688-03 aspects administering antibodies or antigen binding fragments that block the interaction between ANTXR1 and collagen prevents or treats myocardial ischemia by reducing direct ischemic injury, ischemia, or reperfusion injury. [0143] In these applications, a therapeutically effective amount of an antibody or antigen binding fragment that specifically binds ANTXR1 or composition is administered to a subject in an amount and under conditions sufficient to form an immune complex with ANTXR1, thereby inhibiting the progression of cardiovascular disease, the progression of cardiac fibrosis, or inhibiting a sign or symptom of cardiovascular disease, myocardial infarction, and/or myocardial ischemia. [0144] In one example, a desired response is to treat or slow progressive heart failure in a subject, for example to increase blood flow to cardiac tissues in the subject, or to inhibit the progression of or reduce cardiac fibrosis in the subject. [0145] In one example, a desired response is to treat myocardial ischemia in a subject, for example to increase blood flow to cardiac tissues in the subject, or to inhibit the progression of or reduce cardiac fibrosis in the subject. [0146] In some aspects, administration of the therapeutically effective amount of the ANTXR1-specific antibody or antigen binding fragment decreases a sign or symptom of cardiovascular disease, myocardial infarction, and/or myocardial ischemia in the subject, for example, by at least 5%, at least 10%, at least 15%, at least 20%, at least 25%, at least 30%, at least 50%, at least 75%, at least 90%, or at least 95% as compared to a response in the absence of or prior to administration of the ANTXR1-specific antibody or antigen binding fragment. [0147] In some aspects, administration of the therapeutically effective amount of the ANTXR1-specific antibody or antigen binding fragment increases cardiac ejection fraction in the subject with reduced cardiac ejection fraction due to cardiovascular disease, for example, by at least 5%, at least 10%, at least 15%, at least 20%, at least 25%, at least 30%, at least 50%, at least 75%, at least 90%, or at least 95% as compared to a response in the absence of or prior to administration of the ANTXR1-specific antibody or antigen binding fragment. [0148] In some aspects, administration of the therapeutically effective amount of the ANTXR1-specific antibody or antigen binding fragment reduces progressive decrease in cardiac ejection fraction following myocardial infarction in the subject, for example, by at least 5%, at least 10%, at least 15%, at least 20%, at least 25%, at least 30%, at least 50%, at least 75%, at least 90%, or at least 95% as compared to a response in the absence of or prior to administration of the ANTXR1-specific antibody or antigen binding fragment. 4239-108688-03 [0149] In some aspects, administration of the therapeutically effective amount of the ANTXR1-specific antibody or antigen binding fragment reduces cardiac fibrosis in the subject, for example, by at least 5%, at least 10%, at least 15%, at least 20%, at least 25%, at least 30%, at least 50%, at least 75%, at least 90%, or at least 95% as compared to a response in the absence of or prior to administration of the ANTXR1-specific antibody or antigen binding fragment. [0150] In some aspects, administration of the therapeutically effective amount of the ANTXR1-specific antibody or antigen binding fragment increases blood flow to cardiac tissues in the subject, for example, by at least 5%, at least 10%, at least 15%, at least 20%, at least 25%, at least 30%, at least 50%, at least 75%, at least 90%, or at least 95% as compared to a response in the absence of or prior to administration of the ANTXR1-specific antibody or antigen binding fragment. [0151] In some aspects, administration of the therapeutically effective amount of the ANTXR1-specific antibody or antigen binding fragment inhibits the progression of cardiovascular disease in the subject, for example, by at least 5%, at least 10%, at least 15%, at least 20%, at least 25%, at least 30%, at least 50%, at least 75%, at least 90%, or at least 95% as compared to a response in the absence of or prior to administration of the ANTXR1- specific antibody or antigen binding fragment. [0152] In some aspects, administration of the therapeutically effective amount of the ANTXR1-specific antibody or antigen binding fragment inhibits the progression of cardiac fibrosis in the subject, for example, by at least 5%, at least 10%, at least 15%, at least 20%, at least 25%, at least 30%, at least 50%, at least 75%, at least 90%, or at least 95% as compared to a response in the absence of or prior to administration of the ANTXR1-specific antibody or antigen binding fragment. [0153] In some aspects, administration of the therapeutically effective amount of the ANTXR1-specific antibody or antigen binding fragment reduces Heart Failure with preserved Ejection Fraction (HFpEF) in the subject, for example, by at least 5%, at least 10%, at least 15%, at least 20%, at least 25%, at least 30%, at least 50%, at least 75%, at least 90%, or at least 95% as compared to a response in the absence of or prior to administration of the ANTXR1-specific antibody or antigen binding fragment. In a non-limiting example, the effect of treatment on Heart Failure with preserved Ejection Fraction (HFpEF) can be assessed in an animal model, such as described in Schiattarella et al., Nature, 568:351-356, 2019. [0154] Subjects that can benefit from the disclosed methods include human and 4239-108688-03 veterinary subjects. Examples of suitable subjects include those diagnosed with or suspecting of having cardiovascular disease (for example a subject that recently has a myocardial infarction, or a subject with coronary heart disease, or deep vein thrombosis). Subjects can be screened prior to initiating the disclosed therapies, for example to determine whether the subject has cardiovascular disease, has had a myocardial infarction, or is at risk of a myocardial infarction. In some examples a subject is selected because they exhibit signs or symptoms of myocardial ischemia, cardiovascular disease, or myocardial infarction. [0155] The therapeutically effective amount will depend upon the severity of the disease and the general state of the patient’s health. A therapeutically effective amount is that which provides either subjective relief of a symptom(s) or an objectively identifiable improvement as noted by the clinician or other qualified observer. In one example, a therapeutically effective amount is the amount necessary to reduce progressive decrease in cardiac ejection fraction following myocardial infarction in the subject. In another example a therapeutically effective amount is the amount necessary to inhibit the progression of cardiovascular disease in the subject, or the amount effective at reducing a sign or symptom of cardiovascular disease. The therapeutically effective amount of the agents administered can vary depending upon the desired effects and the subject to be treated. In some examples, therapeutic amounts are amounts which slow the progression of cardiovascular disease, such as that slow the progression of cardiac fibrosis caused by myocardial infarction. [0156] Any suitable mode of administration can be used, including local and systemic administration. For example, topical, oral, intravascular such as intravenous, intramuscular, intraperitoneal, intranasal, intradermal, intrathecal and subcutaneous administration can be used. [0157] In one example, the mode of administration is pericardial administration, for example, pericardial administration of a controlled release formulation including the ANTXR1-specific antibody or antigen binding fragment. For example, the controlled release formulation can be a solid, semi-solid, or encapsulated liquid, which can be physically placed into the pericardial space. In some examples, the ANTXR1-specific antibody or antigen binding fragment is physically placed in the pericardial space by an instrument, such as a catheter or needle that is advanced transthoracically or intravascularly, or transmyocardially into the pericardial space. [0158] The particular mode of administration and the dosage regimen will be selected by the attending clinician, taking into account the particulars of the case (for example the subject, the disease, the disease state involved, and whether the treatment is prophylactic). In 4239-108688-03 cases in which more than one agent or composition is being administered, one or more routes of administration may be used; for example, an anticoagulant may be administered orally and an antibody or antigen binding fragment or composition may be administered intravenously. Methods of administration include injection for which the antibodies, antigen binding fragments, or compositions are provided in a nontoxic pharmaceutically acceptable carrier such as water, saline, Ringer's solution, dextrose solution, 5% human serum albumin, fixed oils, ethyl oleate, or liposomes. In some examples, sustained intra-cardiac (or near-cardiac) release of the pharmaceutical preparation that includes a therapeutically effective amount of the antibody or antigen binding fragment may be beneficial. [0159] Doses of the antibody or antigen binding fragment vary, but generally range between about 0.5 mg/kg to about 50 mg/kg, such as a range of about 10 mg/kg to about 30 mg/kg, about 10 mg/kg to about 20 mg/kg, or about 10 mg/kg to about 15 mg/kg. In some aspects, the antibody or antigen binding fragment is administered at a dose of about 1 mg/kg, about 5 mg/kg, about 10 mg/kg, about 20 mg/kg, about 30 mg/kg, about 40 mg/kg, or about 50 mg/kg. In some aspects, the dose of the antibody or antigen binding fragment can be from about 0.5 mg/kg to about 5 mg/kg, such as a dose of about 1 mg/kg, about 2 mg/kg, about 3 mg/kg, about 4 mg/kg or about 5 mg/kg. The antibody or antigen binding fragment is administered according to a dosing schedule determined by a medical practitioner. In some examples, the antibody or antigen binding fragment is administered weekly, every two weeks, every three weeks or every four weeks. [0160] In some aspects, long-term administration is utilized, for example by using a continuous release pump. In further aspects, prolonged administration is used, for example by administering a composition including the antibody or antigen binding fragment thereof that specifically binds to the ANTXR1 extracellular domain on the cell surface in a controlled release formulation. [0161] The compositions that include an antibody, antigen binding fragment, or composition can be formulated in unit dosage form suitable for individual administration of precise dosages. In addition, the compositions may be administered in a single dose or in a multiple dose schedule. A multiple dose schedule is one in which a primary course of treatment may be with more than one separate dose, for instance 1-10 doses, followed by other doses given at subsequent time intervals as needed to maintain or reinforce the action of the compositions. Treatment can involve daily or multi-daily doses of compound(s) over a period of a few days to months, or even years. Thus, the dosage regime will also, at least in part, be determined based on the particular needs of the subject to be treated and will be 4239-108688-03 dependent upon the judgment of the administering practitioner. In one example the antibody, antigen binding fragment, or composition is administered within 30 days of a myocardial infarction. In a further example treatment with the antibody or antigen binding fragment is initiated within 30 days of a myocardial infarction. In other examples, the therapeutically effective amount of an antibody or antigen binding fragment that binds to ANTXR1 is administered less than 30 days, less than 25 days, 20 days, less than 15 days, less than 10 days, less than 9 days, less than 8 days, less than 7 days, less than 6 days, less than 5 days, less than 4 days, less than 3 days, less than 2 days, or less than 1 day after the myocardial infarction occurs. [0162] In some aspects, a subject is administered DNA or RNA encoding a disclosed antibody to provide in vivo antibody production, for example using the cellular machinery of the subject. Any suitable method of nucleic acid administration may be used; non-limiting examples are provided in U.S. Patent No.5,643,578, U.S. Patent No.5,593,972 and U.S. Patent No.5,817,637. U.S. Patent No.5,880,103 describes several methods of delivery of nucleic acids encoding proteins to an organism. One approach to administration of nucleic acids is direct administration with plasmid DNA, such as with a mammalian expression plasmid. The nucleotide sequence encoding the disclosed antibody, or antigen binding fragments thereof, can be placed under the control of a promoter to increase expression. The methods include liposomal delivery of the nucleic acids. Such methods can be applied to the production of an antibody, or antigen binding fragments thereof. In some aspects, a disclosed antibody or antigen binding fragment is expressed in a subject using the pVRC8400 vector (described in Barouch et al., J. Virol., 79(14), 8828-8834, 2005). [0163] In several aspects, a subject can be administered an effective amount of an AAV viral vector that comprises one or more nucleic acid molecules encoding a disclosed antibody or antigen binding fragment. The AAV viral vector is designed for expression of the nucleic acid molecules encoding a disclosed antibody or antigen binding fragment, and administration of the effective amount of the AAV viral vector to the subject leads to expression of an effective amount of the antibody or antigen binding fragment in the subject. Non-limiting examples of AAV viral vectors that can be used to express a disclosed antibody or antigen binding fragment in a subject include those provided in Johnson et al., Nat. Med., 15(8):901-906, 2009 and Gardner et al., Nature, 519(7541):87-91, 2015. [0164] In one aspect, a nucleic acid encoding a disclosed antibody or antigen binding fragment thereof is introduced directly into tissue. For example, the nucleic acid can be loaded onto gold microspheres by standard methods and introduced into the skin by a device 4239-108688-03 such as Bio-Rad’s HELIOS^ Gene Gun. The nucleic acids can be “naked,” consisting of plasmids under control of a strong promoter. [0165] Typically, the DNA is injected into muscle, although it can also be injected directly into other sites. Dosages for injection are usually around 0.5 µg/kg to about 50 mg/kg, and typically are about 0.005 mg/kg to about 5 mg/kg (see, e.g., U.S. Patent No. 5,589,466). V. Therapeutic ANTXR1 Antibodies and Antigen Binding Fragments for Cardiovascular Disease, and Related Nucleic acids and Compositions A. ANTXR1-specific monoclonal antibodies and antigen binding fragments [0166] ANTXR1-specific monoclonal antibodies and antigen binding fragments for use in the disclosed methods are provided. The antibodies and antigen binding fragments specifically bind to the extracellular domain of ANTXR1 on the cell surface. In several aspects, the antibodies and antigen binding fragments can inhibit a biological function or property of ANTXR1 protein in vivo, including, but not limited to, blocking the interaction between ANTXR1 and collagen. In some aspects the collagen is type I collagen. In other aspects the collagen is type VI collagen. In several aspects administering antibodies or antigen binding fragments that block the interaction between ANTXR1 and collagen prevents or treats myocardial ischemia by reducing direct ischemic injury, ischemia, or reperfusion injury. [0167] In some examples, the ANTXR1 specific antibodies include a variable heavy (VH) and a variable light (VL) chain and specifically bind ANTXR1. In several examples, the antibody or antigen binding fragment thereof includes heavy and light chain variable regions including the HCDR1, HCDR2, and HCDR3, and LCDR1, LCDR2, and LCDR3, respectively, of one of the L2 or m825 antibodies. L2 originated from a human mAb phage display library. (Chaudhary, A. et al., Cancer Cell (2012) 21:212-226). m825 and m830 are additional fully human anti-ANTXR1 antibodies isolated from a human naïve yeast display scFv library. (See PMIDs: 29863500 and 36400786 and US Patent Publication No. US 9,765,142). In some examples the LALA-PG mutations may be introduced into the L2, m825 or m830 antibodies, or other mutations that have been shown to prevent binding to Fc gamma receptors. [0168] The discussion of monoclonal antibodies below refers to isolated monoclonal 4239-108688-03 antibodies that include heavy and light chain variable domains including at least one complementarity determining region (CDR), such as a CDR1, CDR2 and CDR3. Various CDR numbering schemes (such as Kabat, Chothia or IMGT numbering schemes) can be used to determine CDR positions. The CDR amino acid sequence of the L2 and m825 antibodies are shown in Table 1 below. Table 1. CDR sequences of L2 and m825 antibodies. L2 [ , including a HCDR1, HCDR2, and/or HCDR3 including amino acids set forth as SEQ ID NOs: 3, 4, and 5, respectively, and a VL including a LCDR1, LCDR2, and/or LCDR3 including amino acids set forth as SEQ ID NOs: 6, 7, and 8 respectively. In some examples, the antibody or antigen binding fragment includes a VH including a HCDR1, HCDR2, and/or HCDR3 including amino acids set forth as SEQ ID NOs: 3, 4, and 5, respectively, wherein the remaining residues of the VH are at least 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence set forth as SEQ ID NO: 1 (L2 VH), and a VL including a LCDR1, LCDR2, and/or LCDR3 including amino acids set forth as SEQ ID NOs: 6, 7, and 8 respectively, wherein the remaining residues of the VL are at least 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence set forth as SEQ ID NO: 2 (L2 VL). In some examples, the antibody or antigen binding fragment includes a VH comprising the amino acid 4239-108688-03 sequence set forth as SEQ ID NO: 1 and a VL comprising the amino acid sequence set forth as SEQ ID NO: 2. In further examples, the antibody includes the LALA-PG mutations (L234A, L235A and P329G, EU numbering, which block binding to Fcγ receptors. [0170] In some examples the antibody includes a heavy chain including the amino acid sequence set forth as SEQ ID NO: 9 (L2 with LALA-PG heavy chain). In other examples includes a light chain including the amino acid sequence set forth as SEQ ID NO: 10 (L2 light chain). In further examples the antibody includes a heavy chain including the amino acid sequence set forth as SEQ ID NO: 9 (L2 with LALA-PG heavy chain), and a light chain including the amino acid sequence set forth as SEQ ID NO: 10 (L2 light chain). [0171] In other examples the antibody or antigen binding fragment includes a VH including a HCDR1, HCDR2, and/or HCDR3 including amino acids set forth as SEQ ID NOs: 13, 14, and 15, respectively, and a VL including a LCDR1, LCDR2, and/or LCDR3 including amino acids set forth as SEQ ID NOs: 16, 17, and 18, respectively. In some examples, the antibody or antigen binding fragment includes a VH including a HCDR1, HCDR2, and/or HCDR3 including amino acids set forth as SEQ ID NOs: 13, 14, and 15, respectively, wherein the remaining residues of the VH are at least 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence set forth as SEQ ID NO: 11 (L2 VH), and a VL including a LCDR1, LCDR2, and/or LCDR3 including amino acids set forth as SEQ ID NOs: 16, 17, and 18 respectively, wherein the remaining residues of the VL are at least 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence set forth as SEQ ID NO: 12 (L2 VL). In some examples, the antibody or antigen binding fragment includes a VH comprising the amino acid sequence set forth as SEQ ID NO: 11 and a VL comprising the amino acid sequence set forth as SEQ ID NO: 12. In further examples, the antibody includes the LALA- PG mutations (L234A, L235A and P329G, EU numbering, which block binding to Fcγ receptors. [0172] In some examples the antibody includes a heavy chain including the amino acid sequence set forth as SEQ ID NO: 20 (m825 with LALA-PG heavy chain). In other examples includes a light chain including the amino acid sequence set forth as SEQ ID NO: 21 (m825 light chain). In further examples the antibody includes a heavy chain including the amino acid sequence set forth as SEQ ID NO: 20 (m825 with LALA-PG heavy chain), and a light chain including the amino acid sequence set forth as SEQ ID NO: 21 (m825 light chain). [0173] In further examples the antibody or antigen binding fragment includes a VH including a HCDR1, HCDR2, and/or HCDR3 including amino acids set forth as SEQ ID NOs: 24, 25, and 26, respectively, and a VL including a LCDR1, LCDR2, and/or LCDR3 4239-108688-03 including amino acids set forth as SEQ ID NOs: 27, 28, and 29, respectively. In some examples, the antibody or antigen binding fragment includes a VH including a HCDR1, HCDR2, and/or HCDR3 including amino acids set forth as SEQ ID NOs: 24, 25, and 26, respectively, wherein the remaining residues of the VH are at least 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence set forth as SEQ ID NO: 22 (m830 VH), and a VL including a LCDR1, LCDR2, and/or LCDR3 including amino acids set forth as SEQ ID NOs: 27, 28, and 29 respectively, wherein the remaining residues of the VL are at least 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence set forth as SEQ ID NO: 23 (m830 VL). In some examples, the antibody or antigen binding fragment includes a VH comprising the amino acid sequence set forth as SEQ ID NO: 22 and a VL comprising the amino acid sequence set forth as SEQ ID NO: 23. In further examples, the antibody includes the LALA- PG mutations (L234A, L235A and P329G, EU numbering, which block binding to Fcγ receptors. [0174] In some examples the antibody includes a heavy chain including the amino acid sequence set forth as SEQ ID NO: 30 (m830 with LALA-PG heavy chain). In other examples includes a light chain including the amino acid sequence set forth as SEQ ID NO: 31 (m830 light chain). In further examples the antibody includes a heavy chain including the amino acid sequence set forth as SEQ ID NO: 30 (m830 with LALA-PG heavy chain), and a light chain including the amino acid sequence set forth as SEQ ID NO: 31 (m830 light chain). 1. Additional Description of Antibodies and Antigen Binding Fragments [0175] The antibody or antigen binding fragment can be a human antibody or fragment thereof. Chimeric antibodies are also provided. The antibody or antigen binding fragment can include any suitable framework region, such as (but not limited to) a human framework region. Alternatively, a heterologous framework region, such as, but not limited to a mouse or monkey framework region, can be included in the heavy or light chain of the antibodies. [0176] The antibody can be of any isotype. The antibody can be, for example, an IgM or an IgG antibody, such as IgG_1, IgG₂, IgG₃, or IgG₄. The class of an antibody that specifically binds ANTXR1 can be switched with another. In one aspect, a nucleic acid molecule encoding VL or VH is isolated such that it does not include any nucleic acid sequences encoding the constant region of the light or heavy chain, respectively. A nucleic acid molecule encoding VL or VH is then operatively linked to a nucleic acid sequence encoding a CL or CH from a different class of immunoglobulin molecule. This can be achieved, for example, using a vector or nucleic acid molecule that comprises a C_L or C_H chain. For 4239-108688-03 example, an antibody that specifically binds ANTXR1, that was originally IgG may be class switched to an IgM. Class switching can be used to convert one IgG subclass to another, such as from IgG1 to IgG2, IgG3, or IgG4. [0177] In some examples, the disclosed antibodies are oligomers of antibodies, such as dimers, trimers, tetramers, pentamers, hexamers, septamers, octomers and so on. [0178] The antibody or antigen binding fragment can be derivatized or linked to another molecule (such as another peptide or protein). In general, the antibody or antigen binding fragment is derivatized such that the binding to ANTXR1 is not affected adversely by the derivatization or labeling. For example, the antibody or antigen binding fragment can be functionally linked (by chemical coupling, genetic fusion, noncovalent association or otherwise) to one or more other molecular entities, such as another antibody (for example, a bi-specific antibody or a diabody), a detectable marker, an effector molecule, or a protein or peptide that can mediate association of the antibody or antibody portion with another molecule (such as a streptavidin core region or a polyhistidine tag). [0179] Also included are antibodies that bind to the same epitope on ANTXR1 to which the ANTXR1 specific antibodies provided herein bind. Antibodies that bind to such an epitope can be identified based on their ability to cross-compete (for example, to competitively inhibit the binding of, in a statistically significant manner) with the ANTXR1 specific antibodies provided herein in ANTXR1 binding assays (such as those described in the Examples). An antibody “competes” for binding when the competing antibody inhibits ANTXR1 binding of an antibody of the invention by more than 50%, in the presence of competing antibody concentrations higher than 106 x KD of the competing antibody. In a certain example, the antibody that binds to the same epitope on ANTXR1 as the antibodies of the present invention is a human monoclonal antibody. Such human monoclonal antibodies can be prepared and isolated as described herein. a. Binding affinity [0180] In several aspects, the antibody or antigen binding fragment specifically binds ANTXR1 with an affinity (e.g., measured by KD) of no more than 1.0 x 10^-8 M, no more than 5.0 x 10^-8 M, no more than 1.0 x 10^-9 M, no more than 5.0 x 10^-9 M, no more than 1.0 x 10^-10 M, no more than 5.0 x 10^-10 M, or no more than 1.0 x 10^-11 M. KD can be measured, for example, by a radiolabeled antigen binding assay (RIA) performed with the Fab version of an antibody of interest and its antigen. In one assay, KD can be measured using surface plasmon resonance assays using a BIACORE®-2000 or a BIACORE®-3000 (BIAcore, Inc., 4239-108688-03 Piscataway, N.J.) at 25° C with immobilized antigen CM5 chips at ~10 response units (RU). Briefly, carboxymethylated dextran biosensor chips (CM5, BIACORE®, Inc.) are activated with N-ethyl-N′-(3-dimethylaminopropyl)-carbodiimide hydrochloride (EDC) and N- hydroxysuccinimide (NHS) according to the supplier's instructions. Antigen is diluted with 10 mM sodium acetate, pH 4.8, to 5 μg/ml (~0.2 μM) before injection at a flow rate of 5 l/minute to achieve approximately 10 response units (RU) of coupled protein. Following the injection of antigen, 1 M ethanolamine is injected to block unreacted groups. For kinetics measurements, two-fold serial dilutions of Fab (0.78 nM to 500 nM) are injected in PBS with 0.05% polysorbate 20 (TWEEN-20™) surfactant (PBST) at 25° C at a flow rate of approximately 25 l/min. Association rates (k_on) and dissociation rates (k_off) are calculated using a simple one-to-one Langmuir binding model (BIACORE® Evaluation Software version 3.2) by simultaneously fitting the association and dissociation sensorgrams. The equilibrium dissociation constant (KD) is calculated as the ratio koff/kon. See, e.g., Chen et al., J. Mol. Biol.293:865-881 (1999). If the on-rate exceeds 10⁶ M⁻¹ s⁻¹ by the surface plasmon resonance assay above, then the on-rate can be determined by using a fluorescent quenching technique that measures the increase or decrease in fluorescence emission intensity (excitation=295 nm; emission=340 nm, 16 nm band-pass) at 25° C. of a 20 nM anti-antigen antibody (Fab form) in PBS, pH 7.2, in the presence of increasing concentrations of antigen as measured in a spectrometer, such as a stop-flow equipped spectrophometer (Aviv Instruments) or a 8000-series SLM-AMINCO™ spectrophotometer (ThermoSpectronic) with a stirred cuvette. b. Antigen Binding Fragments [0181] Antigen binding fragments are encompassed by the present disclosure, such as Fab, F(ab')₂, and Fv which include a heavy chain and light chain variable region and specifically bind ANTXR1 protein. These antibody fragments retain the ability to selectively bind with the antigen and are “antigen-binding” fragments. These fragments include: (1) Fab, the fragment which contains a monovalent antigen-binding fragment of an antibody molecule, can be produced by digestion of whole antibody with the enzyme papain to yield an intact light chain and a portion of one heavy chain; (2) Fab', the fragment of an antibody molecule can be obtained by treating whole antibody with pepsin, followed by reduction, to yield an intact light chain and a portion of the heavy chain; two Fab' fragments are obtained per antibody molecule; (3) (Fab')₂, the fragment of the antibody that can be obtained by treating whole 4239-108688-03 antibody with the enzyme pepsin without subsequent reduction; F(ab')₂ is a dimer of two Fab' fragments held together by two disulfide bonds; (4) Fv, a genetically engineered fragment containing the variable region of the light chain and the variable region of the heavy chain expressed as two chains; and (5) Single chain antibody (such as scFv), defined as a genetically engineered molecule containing the variable region of the light chain, the variable region of the heavy chain, linked by a suitable polypeptide linker as a genetically fused single chain molecule. A scFv is a fusion protein in which a light chain variable region of an immunoglobulin and a heavy chain variable region of an immunoglobulin are bound by a linker (see, e.g., Ahmad et al., Clin. Dev. Immunol., 2012, doi:10.1155/2012/980250; Marbry, IDrugs, 13:543-549, 2010). The intramolecular orientation of the VH-domain and the VL-domain in a scFv, is not decisive for the provided antibodies (e.g., for the provided multispecific antibodies). Thus, scFvs with both possible arrangements (VH-domain-linker domain-VL-domain; VL-domain- linker domain-VH-domain) may be used. (6) A dimer of a single chain antibody (scFV2), defined as a dimer of a scFV. This has also been termed a “miniantibody.” [0182] Additional antigen binding fragments include single-domain antibodies and nanobodies. [0183] The ANTXR1-antibody and antigen binding fragment can be obtained from any suitable source, including engineered (synthetic) antibodies, mice, human, camels, sharks, etc. [0184] For methods of making see for example, Harlow and Lane, Antibodies: A Laboratory Manual, 2^nd, Cold Spring Harbor Laboratory, New York, 2013. [0185] Any suitable method of producing the above-discussed antigen binding fragments may be used. Non-limiting examples are provided in Harlow and Lane, Antibodies: A Laboratory Manual, 2^nd, Cold Spring Harbor Laboratory, New York, 2013. [0186] Antigen binding fragments can be prepared by proteolytic hydrolysis of the antibody or by expression in a host cell (such as an E. coli cell) of DNA encoding the fragment. Antigen binding fragments can also be obtained by pepsin or papain digestion of whole antibodies by conventional methods. For example, antigen binding fragments can be produced by enzymatic cleavage of antibodies with pepsin to provide a 5S fragment denoted F(ab')₂. This fragment can be further cleaved using a thiol reducing agent, and optionally a blocking group for the sulfhydryl groups resulting from cleavage of disulfide linkages, to produce 3.5S Fab' monovalent fragments. 4239-108688-03 [0187] Other methods of cleaving antibodies, such as separation of heavy chains to form monovalent light-heavy chain fragments, further cleavage of fragments, or other enzymatic, chemical, or genetic techniques may also be used, so long as the fragments bind to the antigen that is recognized by the intact antibody. c. Variants [0188] In certain examples, amino acid sequence variants of the antibodies provided herein are contemplated. For example, it may be desirable to improve the binding affinity and/or other biological properties of the antibody. Amino acid sequence variants of an antibody may be prepared by introducing appropriate modifications into the nucleotide sequence encoding the antibody, or by peptide synthesis. Such modifications include, for example, deletions from, and/or insertions into and/or substitutions of residues within the amino acid sequences of the antibody. Any combination of deletion, insertion, and substitution can be made to arrive at the final construct, provided that the final construct possesses the desired characteristics, e.g., antigen-binding. [0189] In certain examples, antibody variants having one or more amino acid substitutions are provided. Sites of interest for substitutional mutagenesis include the CDRs and the framework regions. Amino acid substitutions may be introduced into an antibody of interest and the products screened for a desired activity, e.g., retained/improved antigen binding, decreased immunogenicity, or improved ADCC or CDC. [0190] The variants typically retain amino acid residues necessary for correct folding and stabilizing between the VH and the VL regions, and will retain the charge characteristics of the residues in order to preserve the low pI and low toxicity of the molecules. Amino acid substitutions can be made in the VH and the VL regions to increase yield. [0191] In some examples, the heavy chain of the antibody includes up to 10 (such as up to 1, up to 2, up to 3, up to 4, up to 5, up to 6, up to 7, up to 8, or up to 9) amino acid substitutions (such as conservative amino acid substitutions) compared to the amino acid sequence set forth as one of SEQ ID NOs : 1, 9, 11, 20, 22, or 30. In some examples, the light chain of the antibody includes up to 10 (such as up to 1, up to 2, up to 3, up to 4, up to 5, up to 6, up to 7, up to 8, or up to 9) amino acid substitutions (such as conservative amino acid substitutions) compared to the amino acid sequence set forth as one of SEQ ID NOs: 2, 10, 12, 21, 23, or 31. [0192] In some examples, the antibody or antigen binding fragment can include up to 10 (such as up to 1, up to 2, up to 3, up to 4, up to 5, up to 6, up to 7, up to 8, or up to 9) amino 4239-108688-03 acid substitutions (such as conservative amino acid substitutions) in the framework regions of the heavy chain of the antibody, or the light chain of the antibody, or the heavy and light chains of the antibody, compared to a known framework region, or compared to the framework regions of the L2, m825, or m830 antibodies as disclosed herein, and maintain the specific binding activity for ANTXR1 protein. [0193] In certain examples, substitutions, insertions, or deletions may occur within one or more CDRs so long as such alterations do not substantially reduce the ability of the antibody to bind antigen. For example, conservative alterations (e.g., conservative substitutions as provided herein) that do not substantially reduce binding affinity may be made in CDRs. In certain examples of the variant VH and VL sequences provided above, each CDR either is unaltered, or contains no more than one, two or three amino acid substitutions. [0194] To increase binding affinity of the antibody, the VL and VH segments can be randomly mutated, such as within H-CDR3 region or the L-CDR3 region, in a process analogous to the in vivo somatic mutation process responsible for affinity maturation of antibodies during a natural immune response. Thus in vitro affinity maturation can be accomplished by amplifying VH and VL regions using PCR primers complementary to the H-CDR3 or L-CDR3, respectively. In this process, the primers have been "spiked" with a random mixture of the four nucleotide bases at certain positions such that the resultant PCR products encode VH and VL segments into which random mutations have been introduced into the VH and/or VL CDR3 regions. These randomly mutated VH and VL segments can be tested to determine the binding affinity for ANTXR1 protein. In particular examples, the VH amino acid sequence is one of SEQ ID NOs: 1, 11, or 22. In other examples, the VL amino acid sequence is SEQ ID NOs: 2, 12, or 23. Methods of in vitro affinity maturation include Chowdhury, Methods Mol. Biol.207:179-196 (2008) and Hoogenboom et al. in Methods in Molecular Biology 178:1-37 O'Brien et al., ed., Human Press, Totowa, N.J., (2001). [0195] A useful method for identification of residues or regions of an antibody that may be targeted for mutagenesis is called “alanine scanning mutagenesis” as described by Cunningham and Wells (1989) Science, 244:1081-1085. In this method, a residue or group of target residues (e.g., charged residues such as arg, asp, his, lys, and glu) are identified and replaced by a neutral or negatively charged amino acid (e.g., alanine or polyalanine) to determine whether the interaction of the antibody with antigen is affected. Further substitutions may be introduced at the amino acid locations demonstrating functional sensitivity to the initial substitutions. Alternatively, or additionally, a crystal structure of an antigen-antibody complex is used to identify contact points between the antibody and 4239-108688-03 antigen. Such contact residues and neighboring residues may be targeted or eliminated as candidates for substitution. Variants may be screened to determine whether they contain the desired properties. [0196] In certain examples, an antibody or antigen binding fragment is altered to increase or decrease the extent to which the antibody or antigen binding fragment is glycosylated. Addition or deletion of glycosylation sites may be conveniently accomplished by altering the amino acid sequence such that one or more glycosylation sites is created or removed. [0197] Where the antibody comprises an Fc region, the carbohydrate attached thereto may be altered. Native antibodies produced by mammalian cells typically comprise a branched, biantennary oligosaccharide that is generally attached by an N-linkage to Asn297 of the CH2 domain of the Fc region. See, e.g., Wright et al. TIBTECH 15:26-32 (1997). The oligosaccharide may include various carbohydrates, e.g., mannose, N-acetyl glucosamine (GlcNAc), galactose, and sialic acid, as well as a fucose attached to a GlcNAc in the “stem” of the biantennary oligosaccharide structure. In some examples, modifications of the oligosaccharide in an antibody may be made in order to create antibody variants with certain improved properties. [0198] In one example, antibody variants are provided having a carbohydrate structure that lacks fucose attached (directly or indirectly) to an Fc region. For example, the amount of fucose in such antibody may be from 1% to 80%, from 1% to 65%, from 5% to 65% or from 20% to 40%. The amount of fucose is determined by calculating the average amount of fucose within the sugar chain at Asn297, relative to the sum of all glycostructures attached to Asn 297 (e.g. complex, hybrid and high mannose structures) as measured by MALDI-TOF mass spectrometry, as described in WO 2008/077546, for example. Asn297 refers to the asparagine residue located at about position 297 in the Fc region; however, Asn297 may also be located about ±3 amino acids upstream or downstream of position 297, i.e., between positions 294 and 300, due to minor sequence variations in antibodies. Such fucosylation variants may have improved ADCC function. See, e.g., US Patent Publication Nos. US 2003/0157108 (Presta, L.); US 2004/0093621 (Kyowa Hakko Kogyo Co., Ltd). Examples of publications related to “defucosylated” or “fucose-deficient” antibody variants include: US 2003/0157108; WO 2000/61739; WO 2001/29246; US 2003/0115614; US 2002/0164328; US 2004/0093621; US 2004/0132140; US 2004/0110704; US 2004/0110282; US 2004/0109865; WO 2003/085119; WO 2003/084570; WO 2005/035586; WO 2005/035778; WO2005/053742; WO2002/031140; Okazaki et al. J. Mol. Biol.336:1239-1249 (2004); Yamane-Ohnuki et al. Biotech. Bioeng.87: 614 (2004). Examples of cell lines capable of 4239-108688-03 producing defucosylated antibodies include Lec 13 CHO cells deficient in protein fucosylation (Ripka et al. Arch. Biochem. Biophys.249:533-545 (1986); US Pat Appl No US 2003/0157108 A1, Presta, L; and WO 2004/056312 A1, Adams et al., especially at Example 11), and knockout cell lines, such as alpha-1,6-fucosyltransferase gene, FUT8, knockout CHO cells (see, e.g., Yamane-Ohnuki et al. Biotech. Bioeng.87: 614 (2004); Kanda, Y. et al., Biotechnol. Bioeng., 94(4):680-688 (2006); and WO2003/085107). [0199] Antibodies variants are further provided with bisected oligosaccharides, e.g., in which a biantennary oligosaccharide attached to the Fc region of the antibody is bisected by GlcNAc. Such antibody variants may have reduced fucosylation and/or improved ADCC function. Examples of such antibody variants are described, e.g., in WO 2003/011878 (Jean- Mairet et al.); U.S. Pat. No.6,602,684 (Umana et al.); and US 2005/0123546 (Umana et al.). Antibody variants with at least one galactose residue in the oligosaccharide attached to the Fc region are also provided. Such antibody variants may have improved CDC function. Such antibody variants are described, e.g., in WO 1997/30087 (Patel et al.); WO 1998/58964 (Raju, S.); and WO 1999/22764 (Raju, S.). [0200] In several examples, the constant region of the antibody includes one or more amino acid substitutions to optimize in vivo half-life of the antibody. The serum half-life of IgG Abs is regulated by the neonatal Fc receptor (FcRn). Thus, in several examples, the antibody includes an amino acid substitution that increases binding to the FcRn. Such substitutions include those at IgG constant regions T250Q and M428L (see, e.g., Hinton et al., J Immunol., 176:346-356, 2006); M428L and N434S (the “LS” mutation, see, e.g., Zalevsky, et al., Nature Biotechnology, 28:157-159, 2010); N434A (see, e.g., Petkova et al., Int. Immunol., 18:1759-1769, 2006); T307A, E380A, and N434A (see, e.g., Petkova et al., Int. Immunol., 18:1759-1769, 2006); and M252Y, S254T, and T256E (see, e.g., Dall’Acqua et al., J. Biol. Chem., 281:23514-23524, 2006). [0201] In some examples, the constant region of the antibody includes one of more amino acid substitutions to optimize Antibody-dependent cell-mediated cytotoxicity (ADCC). ADCC is mediated primarily through a set of closely related Fcγ receptors. Some substitutions can increase binding to FcγRIIIa such as substitutions at IgG constant regions S239D and I332E (see, e.g., Lazar et al., Proc. Natl., Acad. Sci. U.S.A., 103:4005-4010, 2006); and S239D, A330L, and I332E (see, e.g., Lazar et al., Proc. Natl., Acad. Sci. U.S.A., 103:4005-4010, 2006). [0202] In further examples, the LALA-PG mutations (L234A, L235A and P329G) are introduced, which block binding to Fcγ receptors. 4239-108688-03 [0203] In certain examples, an antibody provided herein may be further modified to contain additional nonproteinaceous moieties that are readily available. The moieties suitable for derivatization of the antibody include but are not limited to water soluble polymers. Non- limiting examples of water soluble polymers include, but are not limited to, polyethylene glycol (PEG), copolymers of ethylene glycol/propylene glycol, carboxymethylcellulose, dextran, polyvinyl alcohol, polyvinyl pyrrolidone, poly-1,3-dioxolane, poly-1,3,6-trioxane, ethylene/maleic anhydride copolymer, polyaminoacids (either homopolymers or random copolymers), and dextran or poly(n-vinyl pyrrolidone)polyethylene glycol, propropylene glycol homopolymers, prolypropylene oxide/ethylene oxide co-polymers, polyoxyethylated polyols (e.g., glycerol), polyvinyl alcohol, and mixtures thereof. Polyethylene glycol propionaldehyde may have advantages in manufacturing due to its stability in water. The polymer may be of any molecular weight, and may be branched or unbranched. The number of polymers attached to the antibody may vary, and if more than one polymer are attached, they can be the same or different molecules. In general, the number and/or type of polymers used for derivatization can be determined based on considerations including, but not limited to, the particular properties or functions of the antibody to be improved, whether the antibody derivative will be used in a therapy under defined conditions, etc. B. Polynucleotides and Expression [0204] Nucleic acid molecules (for example, cDNA or RNA molecules) encoding the amino acid sequences of antibodies and antigen binding fragments that specifically bind to ANTXR1 are provided. Nucleic acids encoding these molecules can readily be produced using the amino acid sequences provided herein (such as the CDR sequences and VH and VL sequences), sequences available in the art (such as framework or constant region sequences), and the genetic code. In several aspects, a nucleic acid molecules can encode the VH, the VL, or both the VH and VL (for example in a bicistronic expression vector) of a disclosed antibody or antigen binding fragment. In several aspects, the nucleic acid molecules can be expressed in a host cell (such as a mammalian cell) to produce a disclosed antibody or antigen binding fragment. [0205] The genetic code can be used to construct a variety of functionally equivalent nucleic acid sequences, such as nucleic acids which differ in sequence but which encode the same antibody sequence, or encode a conjugate or fusion protein including the VH and/or VL nucleic acid sequence. 4239-108688-03 [0206] Nucleic acid molecules encoding the antibodies, antigen binding fragments, and conjugates that specifically bind to ANTXR1 can be prepared by any suitable method including, for example, cloning of appropriate sequences or by direct chemical synthesis by standard methods. Chemical synthesis produces a single stranded oligonucleotide. This can be converted into double stranded DNA by hybridization with a complementary sequence or by polymerization with a DNA polymerase using the single strand as a template. [0207] Exemplary nucleic acids can be prepared by cloning techniques. Examples of appropriate cloning and sequencing techniques can be found, for example, in Green and Sambrook (Molecular Cloning: A Laboratory Manual, 4^th ed., New York: Cold Spring Harbor Laboratory Press, 2012) and Ausubel et al. (Eds.) (Current Protocols in Molecular Biology, New York: John Wiley and Sons, including supplements). [0208] Nucleic acids can also be prepared by amplification methods. Amplification methods include the polymerase chain reaction (PCR), the ligase chain reaction (LCR), the transcription-based amplification system (TAS), and the self-sustained sequence replication system (3SR). [0209] The nucleic acid molecules can be expressed in a recombinantly engineered cell such as bacteria, plant, yeast, insect and mammalian cells. The antibodies, antigen binding fragments, and conjugates can be expressed as individual proteins including the VH and/or VL (linked to an effector molecule or detectable marker as needed), or can be expressed as a fusion protein. Any suitable method of expressing and purifying antibodies and antigen binding fragments may be used; non-limiting examples are provided in Al-Rubeai (Ed.), Antibody Expression and Production, Dordrecht; New York: Springer, 2011). An immunoadhesin can also be expressed. Thus, in some examples, nucleic acids encoding a VH and VL, and immunoadhesin are provided. The nucleic acid sequences can optionally encode a leader sequence. [0210] To create a scFv the VH- and VL-encoding DNA fragments can be operatively linked to another fragment encoding a flexible linker, e.g., encoding the amino acid sequence (Gly₄-Ser)₃, such that the VH and VL sequences can be expressed as a contiguous single- chain protein, with the VL and VH domains joined by the flexible linker (see, e.g., Bird et al., Science, 242(4877):423-426, 1988; Huston et al., Proc. Natl. Acad. Sci. U.S.A., 85(16):5879- 5883, 1988; McCafferty et al., Nature, 348:552-554, 1990; Kontermann and Dübel (Eds.), Antibody Engineering, Vols.1-2, 2^nd ed., Springer-Verlag, 2010; Greenfield (Ed.), Antibodies: A Laboratory Manual, 2^nd ed. New York: Cold Spring Harbor Laboratory Press, 2014). Optionally, a cleavage site can be included in a linker, such as a furin cleavage site. 4239-108688-03 [0211] The single chain antibody may be monovalent, if only a single VH and VL are used, bivalent, if two VH and VL are used, or polyvalent, if more than two VH and VL are used. Bispecific or polyvalent antibodies may be generated that bind specifically to ANTXR1 and another antigen. The encoded VH and VL optionally can include a furin cleavage site between the VH and VL domains. [0212] One or more DNA sequences encoding the antibodies, antigen binding fragments, or conjugates can be expressed in vitro by DNA transfer into a suitable host cell. The cell may be prokaryotic or eukaryotic. Numerous expression systems available for expression of proteins including E. coli, other bacterial hosts, yeast, and various higher eukaryotic cells such as the COS, CHO, HeLa and myeloma cell lines, can be used to express the disclosed antibodies and antigen binding fragments. Methods of stable transfer, meaning that the foreign DNA is continuously maintained in the host may be used. Hybridomas expressing the antibodies of interest are also encompassed by this disclosure. [0213] The expression of nucleic acids encoding the antibodies and antigen binding fragments described herein can be achieved by operably linking the DNA or cDNA to a promoter (which is either constitutive or inducible), followed by incorporation into an expression cassette. The promoter can be any promoter of interest, including a cytomegalovirus promoter. Optionally, an enhancer, such as a cytomegalovirus enhancer, is included in the construct. The cassettes can be suitable for replication and integration in either prokaryotes or eukaryotes. Typical expression cassettes contain specific sequences useful for regulation of the expression of the DNA encoding the protein. For example, the expression cassettes can include appropriate promoters, enhancers, transcription and translation terminators, initiation sequences, a start codon (i.e., ATG) in front of a protein- encoding gene, splicing signals for introns, sequences for the maintenance of the correct reading frame of that gene to permit proper translation of mRNA, and stop codons. The vector can encode a selectable marker, such as a marker encoding drug resistance (for example, ampicillin or tetracycline resistance). [0214] To obtain high level expression of a cloned gene, it is desirable to construct expression cassettes which contain, for example, a strong promoter to direct transcription, a ribosome binding site for translational initiation (e.g., internal ribosomal binding sequences), and a transcription/translation terminator. For E. coli, this can include a promoter such as the T7, trp, lac, or lambda promoters, a ribosome binding site, and preferably a transcription termination signal. For eukaryotic cells, the control sequences can include a promoter and/or an enhancer derived from, for example, an immunoglobulin gene, HTLV, SV40 or 4239-108688-03 cytomegalovirus, and a polyadenylation sequence, and can further include splice donor and/or acceptor sequences (for example, CMV and/or HTLV splice acceptor and donor sequences). The cassettes can be transferred into the chosen host cell by any suitable method such as transformation or electroporation for E. coli and calcium phosphate treatment, electroporation or lipofection for mammalian cells. Cells transformed by the cassettes can be selected by resistance to antibiotics conferred by genes contained in the cassettes, such as the amp, gpt, neo and hyg genes. [0215] Modifications can be made to a nucleic acid encoding a polypeptide described herein without diminishing its biological activity. Some modifications can be made to facilitate the cloning, expression, or incorporation of the targeting molecule into a fusion protein. Such modifications include, for example, termination codons, sequences to create conveniently located restriction sites, and sequences to add a methionine at the amino terminus to provide an initiation site, or additional amino acids (such as poly His) to aid in purification steps. [0216] Once expressed, the antibodies, antigen binding fragments, and conjugates can be purified according to standard procedures in the art, including ammonium sulfate precipitation, affinity columns, column chromatography, and the like (see, generally, Simpson et al. (Eds.), Basic methods in Protein Purification and Analysis: A Laboratory Manual, New York: Cold Spring Harbor Laboratory Press, 2009). The antibodies, antigen binding fragment, and conjugates need not be 100% pure. Once purified, partially or to homogeneity as desired, if to be used prophylatically, the polypeptides should be substantially free of endotoxin. [0217] Methods for expression of antibodies, antigen binding fragments, and conjugates, and/or refolding to an appropriate active form, from mammalian cells, and bacteria such as E. coli have been described and are applicable to the antibodies disclosed herein. See, e.g., Greenfield (Ed.), Antibodies: A Laboratory Manual, 2^nd ed. New York: Cold Spring Harbor Laboratory Press, 2014, Simpson et al. (Eds.), Basic methods in Protein Purification and Analysis: A Laboratory Manual, New York: Cold Spring Harbor Laboratory Press, 2009, and Ward et al., Nature 341(6242):544-546, 1989. C. Pharmaceutical Compositions [0218] Compositions are provided that include one or more of the disclosed antibodies or antigen binding fragments that specifically bind ANTXR1 in a carrier (such as a pharmaceutically acceptable carrier). The compositions can be prepared in unit dosage forms 4239-108688-03 for administration to a subject. The compositions can be formulated for systemic (such as intravenous) or local (such as pericardial) administration. In one example, the antibody that specifically binds ANTXR1 or an antigen binding fragment thereof is formulated for parenteral administration, such as intravenous administration. Compositions including an antibody or antigen binding fragment as disclosed herein are of use, for example, for the treatment of cardiovascular disease or myocardial infarction. [0219] The compositions for administration can include a solution of the antibody or antigen binding fragment dissolved in a pharmaceutically acceptable carrier, such as an aqueous carrier. A variety of aqueous carriers can be used, for example, buffered saline and the like. These solutions are sterile and generally free of undesirable matter. These compositions may be sterilized by conventional, well known sterilization techniques. The compositions may contain pharmaceutically acceptable auxiliary substances as required to approximate physiological conditions such as pH adjusting and buffering agents, toxicity adjusting agents and the like, for example, sodium acetate, sodium chloride, potassium chloride, calcium chloride, sodium lactate and the like. The concentration of antibody or antigen binding fragment or conjugate in these formulations can vary widely, and will be selected primarily based on fluid volumes, viscosities, body weight and the like in accordance with the particular mode of administration selected and the subject’s needs. [0220] A typical composition for intravenous administration comprises about 0.01 to about 30 mg/kg of antibody or antigen binding fragment per subject per day. Any suitable method may be used for preparing administrable compositions; non-limiting examples are provided in such publications as Remington: The Science and Practice of Pharmacy, 22^nd ed., London, UK: Pharmaceutical Press, 2013. In some aspects, the composition can be a liquid formulation including one or more antibodies, antigen binding fragments (such as an antibody or antigen binding fragment that specifically binds to ANTXR1), in a concentration range from about 0.1 mg/ml to about 20 mg/ml, or from about 0.5 mg/ml to about 20 mg/ml, or from about 1 mg/ml to about 20 mg/ml, or from about 0.1 mg/ml to about 10 mg/ml, or from about 0.5 mg/ml to about 10 mg/ml, or from about 1 mg/ml to about 10 mg/ml. [0221] Antibodies or an antigen binding fragment thereof, or a nucleic acid encoding such molecules, can be provided in lyophilized form and rehydrated with sterile water before administration, although they are also provided in sterile solutions of known concentration. The antibody solution, or an antigen binding fragment or a nucleic acid encoding such antibodies or antigen binding fragments, can then be added to an infusion bag containing 0.9% sodium chloride, USP, and typically administered at a dosage of from 0.5 to 15 mg/kg 4239-108688-03 of body weight. Considerable experience is available in the art in the administration of antibody drugs, which have been marketed in the U.S. since the approval of Rituximab in 1997. Antibodies, antigen binding fragments, or a nucleic acid encoding such molecules, can be administered by slow infusion, rather than in an intravenous push or bolus. In one example, a higher loading dose is administered, with subsequent, maintenance doses being administered at a lower level. For example, an initial loading dose of 4 mg/kg may be infused over a period of some 90 minutes, followed by weekly maintenance doses for 4-8 weeks of 2 mg/kg infused over a 30-minute period if the previous dose was well tolerated. [0222] Controlled release parenteral formulations can be made as implants, oily injections, or as particulate systems. Particulate systems include microspheres, microparticles, microcapsules, nanocapsules, nanospheres, and nanoparticles. Microcapsules contain the therapeutic protein, such as a cytotoxin or a drug, as a central core. In microspheres the therapeutic is dispersed throughout the particle. Particles, microspheres, and microcapsules smaller than about 1 µm are generally referred to as nanoparticles, nanospheres, and nanocapsules, respectively. Capillaries have a diameter of approximately 5 µm so that only nanoparticles are administered intravenously. Microparticles are typically around 100 µm in diameter and are administered subcutaneously or intramuscularly. [0223] Polymers can be used for ion-controlled release of the antibody compositions disclosed herein. Any suitable polymer may be used, such as a degradable or nondegradable polymeric matrix designed for use in controlled drug delivery. Alternatively, hydroxyapatite has been used as a microcarrier for controlled release of proteins. In yet another aspect, liposomes are used for controlled release as well as drug targeting of the lipid-capsulated drug. EXAMPLES [0224] The following examples are provided to illustrate particular features of certain aspects of the disclosure, but the scope of the claims should not be limited to those features exemplified. Example 1 Material and Methods This example provides a description of the materials and methods used for the studies provided herein. 4239-108688-03 Experimental animal models [0225] All mice were bred and maintained in a pathogen free facility certified by the Association for Assessment and Accreditation of Laboratory Animal Care (AAALAC) International, and the study was carried out in accordance with protocols approved by the NCI Frederick Animal Care and Use Committee (ACUC). Animal care was provided in accordance with the procedures outlined in the “Guide for Care and Use of Laboratory Animals” (National Research Council; 2011; National Academies Press; Washington, D.C.). Unless indicated otherwise, mice were fed Charles Rivers Rat and Mouse 18% autoclavable diet (Cat # 5L79, LabDiet) ad libitum and maintained under conventional housing. Clinical samples [0226] Anonymized human MI tissue samples were obtained from the Cooperative Human Tissue Network (CHTN) or the Duke Human Heart Repository with approval from the NIH Office of Human Subject Research. All clinical protocols were approved by institution-specific investigational review boards, with appropriate patient informed consent. The demographics of the human heart samples can be found in Table 1 (FIG.28). Experimental design [0227] The objective of the study was to evaluate the role of ANTXR1 in various mouse models of heart disease, including MI, pressure overload model, an obesity driven HFpEF. Animals were kept in the NCI vivarium at an ambient temperature of 25 ± 2°C, 45–55% relative humidity with 12 h light:dark cycle. The mice had free access to standard rodent pellet diet and drinking water. All tests were conducted on 2-month-old male ΑΝΤXR1 KO or WT mice on the C57BL/6-NCr background (Cullen, M. et al. Host-derived tumor endothelial marker 8 promotes the growth of melanoma. Cancer Res 69, 6021-6026, 2009), unless indicated otherwise. ΑΝΤXR1 conditional KO mice are available from the Jackson Laboratory [Strain no.: 037486]. Myocardial infarction (MI) model [0228] MI was induced in C57BL/6-NCr ΑΝΤXR1 WT and KO mice as described previously (Curcio, A. et al. Competitive displacement of phosphoinositide 3-kinase from beta-adrenergic receptor kinase-1 improves postinfarction adverse myocardial remodeling. Am J Physiol Heart Circ Physiol 291, H1754-1760, 2006). Briefly, mice were anesthetized with Tribromoethanol/Avertin anesthesia (2,2,2-tribromoethanol, Millipore Sigma and tert- 4239-108688-03 amyl alcohol, Millipore Sigma) administered intraperitoneally at 0.2 mL/10 grams of body weight. The neck and chest area were shaved and sterilized. Endotracheal intubation was performed by direct visualization of the trachea through a ventral neck incision and mice were ventilated with a small animal respirator (tidal volume = 1.0 ml, rate = 110 breaths/min. R405 Mouse Ventilator, RWD). Left thoracotomy was performed under a surgical microscope entering the fourth intercostal space to expose the pericardium and MI was produced by ligating the left anterior descending coronary artery with an 8–0 nylon suture (Nylon Monofilament NL146800,65F0P, DemeTECH) at the site of the vessels' emergence past the tip of the left atrium. After closing and suturing the chest, the animal was gradually weaned from the respirator to avoid possible pneumothorax. After surgery the animal cages were placed on a heating pad (99-102°F) for at least 7 days post-surgery. Left ventricular function was assayed by echocardiography at day 0, 1, 28, 42, or, as indicated, after surgery as described below. T8Ab treatment or PBS control was administered by IP injections 3 times per week starting on day 1 post-surgery. Hypertension model [0229] Hypertension was induced as described previously (Rurik, J. G. et al. CAR T cells produced in vivo to treat cardiac injury. Science 375, 91-96, 2022; Aghajanian, H. et al. Targeting cardiac fibrosis with engineered T cells. Nature 573, 430-433, 2019) by implanting a 28-day osmotic minipump (Alzet, Cupertino, model 2004) with constant release of (1.5 μg/g/day) angiotensin II and (50μg/g/day) phenylephrine (Sigma-Aldrich). Minipumps of control sham-injured animals contained 0.9% sodium chloride.15 mg/kg of T8Ab or vehicle (PBS) control were injected IP 3 times per week starting at day 1 post minipump implantation. Left ventricular function was assayed by echocardiography four weeks after hypertension induction as described below. 28 days after minipump implantation, mice were euthanized, and the heart collected for analysis. Mouse model of Heart Failure with preserved Ejection Fraction (HFpEF) \ [0230] HFpEF was induced in mice as previously described (Schiattarella, G. G. et al. Nitrosative stress drives heart failure with preserved ejection fraction. Nature 568, 351-356, 2019). Briefly, mice had free access to standard rodent diet (cat no.2916, Teklad) or a HFD (D12492, Research Diet) and water. L-NAME (0.5 g/L, Sigma-Aldrich) was supplied in the drinking water for 5 weeks, after adjusting the pH to 7.4. 4239-108688-03 Echocardiography and doppler imaging [0231] A Fujifilm VisualSonics Vevo2100 Ultrasound System (VisualSonics Inc, Toronto, ON, Canada) equipped with a MS400 (18-38 MHZ) transducer was used for all transthoracic echocardiography image acquisition. Measurements were performed in mice initially anesthetized with 3% isoflurane (Covetrus^) and switched to 1-1.5% during acquisition of the echocardiogram. The short axis B-mode was used to obtain the parameters of systolic function and the apical four-chamber views were used to measure diastolic function. Long axis B-mode view was used for analyzing the peak longitudinal strain rate. All measurements were calculated using Vevo Lab 2100 software. Pulse wave velocity [0232] Pulse wave velocity (PWV) was measured by noninvasive methods. The ascending aorta and the abdominal aorta pulse wave were recorded, and the distance between the two locations was measured using the meter of the table support on which the mice were restrained. PWV was calculated as the ratio of ΔD (distance between ascending aorta and the abdominal aorta) and ΔT (the electrocardiography-based transit time between averaged waveforms at both locations) (PWV = ΔD/ΔT). Exercise exhaustion test [0233] Mice were acclimated to the treadmill for 3 days (20 min/day) and the exhaustion test was performed after 2 days of rest. Mice ran uphill (20°) on the treadmill (IITC Life Science, 800 Treadmill, Woodland Hills, CA) starting at a warm-up speed of 5 m/min for 4 min after which the speed was increased to 14 m/min. When the mice reached the fatigue endpoint (10 continuous seconds in the designated fatigue zone in direct contact with an electric-stimulus grid), the mice were immediately removed from the treadmill and the running time calculated. Glucose-tolerance test [0234] Glucose-tolerance tests (GTT) were performed as previously described (Fulgenzi, G. et al. Novel metabolic role for BDNF in pancreatic beta-cell insulin secretion. Nat Commun 11, 1950, 2020). Briefly, mice were fasted for 6 h starting at 6:00 am before administering 2 g/kg glucose by oral gavage. Blood from the tail vein was collected at 0, 15, 30, 60, and 120 min after glucose administration using microhematocrit tubes (22-274913, 4239-108688-03 Thermo Fisher Scientific), and glucose concentrations were measured using the Alphatrak®2 glucometer (Zoetis). The area under the curve (AUC) was calculated using Prism10 software. Single cell preparation from mouse hearts and sequencing [0235] Mice were anesthetized with 0.2 mL/10 g Avertin of body weight as described above and the heart was perfused with sterile ice-cold PBS using a miniplus peristaltic pump (~1ml/heart/min, GILSON) for 10 min to clear red blood cells (Schafer, S. et al. IL-11 is a crucial determinant of cardiovascular fibrosis. Nature 552, 110-115, 2017). Cardiac single cells were obtained using the Multi Tissue Dissociation Kit 2 (Cat# 130-110-203, Miltenyi Biotec) according to manufactures protocols. This kit removes most of the cardiomyocytes during the procedure and the cutoff of single cell viability from each sample was ~90% for the following experiments. [0236] Libraries preparation and sequencing were performed at the Sequencing Facility, Frederick National Laboratory for Cancer Research. Briefly, ~16.5K cells were collected for each sample, and Chromium Next GEM Single Cell 3ʹ Reagent Kits v3.1 and Chromium Next GEM Single Cell 5' reagent v2 dual index kits were used for the AngII/PE mouse model and the MI model, respectively. All libraries were sequenced on a NovaSeq 6000 run. For the AngII/PE model, the sequencing run was set at 28 cycles + 90 cycles non-symmetric run and all samples had sequencing yields of more than 514 million reads each. For the MI model, the sequencing run was set at 151 cycles + 151 cycles symmetric run and all samples have sequencing yields of more than 424 million reads each. Demultiplexing of samples for both models was done by allowing 1 mismatch in the barcodes. The sequencing quality for all libraries was of high quality in that over 95.0% of bases in the barcode regions have Q30 or above, at least 91% of bases in the read have Q30 or above and more than 95% of bases in the UMI have Q30 or above. Analysis of the scRNA-seq dataset [0237] The fastq files were aligned to the database of the mouse genome (refdata-gex- mm10-2020-A) using cellranger (v7.0.0, 10x Genomics) with the default parameters on the NIH HPC Biowulf cluster (http://hpc.nih.gov). The h5 files from the output folder were analyzed using the Seurat (v4.1.1) according to the manual. For each sample, the cutoff of the following parameters was set as: min.cells >= 10, min.features >= 250, nCount_RNA >= 500, nFeature_RNA <= 10,000, and percent.mt <=10. After the above filter, the potential cell doublets were filtered out using DoubletFinder (v2.0.3). For the analysis of differentially 4239-108688-03 expressed genes, the pseudo-bulk RNA-seq method with DESeq2 (v1.36.0) was adopted. The clusterProfiler (v4.4.4) was used for the GO enrichment analysis. The volcano plots and heatmap were plotted using ggplot2(v3.4.3) and ComplexHeatmap (v2.15.1), separately. For the RNA velocity analysis, velocyto (v0.17) and scvelo (v0.2.4) were used. Immortalization of mouse cardiac fibroblasts [0238] Cardiac fibroblasts were purified from a tsA58⁺/ANTXR1^flox/flox C57BL/6-NCr strain which was made by crossing together The Jackson Laboratory Strain no: 032619 (Immortomouse) and 037486 (B6N.Cg-Antxr1^tm1.1Bstc/J). Cardiac cells were dispersed using the Multi Tissue Dissociation Kit 2 as above. Cardiac fibroblasts were then purified as previously described (Melzer, M., Beier, D., Young, P. P. & Saraswati, S. Isolation and Characterization of Adult Cardiac Fibroblasts and Myofibroblasts. J Vis Exp, 2020). Briefly, cells were first negatively selected sequentially, with anti-CD45 (Cat# 130-052-301, Miltenyi Biotec) and anti-CD31 microbeads (Cat# 130-097-418, Miltenyi Biotec) followed by a positive selection with an anti-fibroblast antibody (Clone: mEF-SK4, Cat# 130-120-802, Miltenyi Biotec). After purification, cells were plated on a 0.1% gelatin-precoated T75 flask (Cat# 07903, STEMCELL) with DEME/F-12 medium (Cat# 11330032, ThermoFisher) supplemented with 10% FBS (Cat# 97068-085, Avantor^® Seradigm), Sodium Pyruvate (Cat# 11360070, ThermoFisher), MEM Non-Essential Amino Acids Solution (Cat# 11140050, ThermoFisher), Penicillin/Streptomycin (Cat# 30-002-CI, CORNING) and IFN-γ (5 ng/ml, Cat# 315-05, PeproTech) and maintained at 32 °C with 5% CO₂ for immortalization. After 2 passages expansion, cells were cryopreserved. For experiments, all cell lines were used within 10 passages and cultured with the above medium but without IFN- γ at 37°C with 5% CO₂. Culture of human cardiac fibroblasts [0239] Primary human ventricular cardiac fibroblasts (NHCF-V, Cat# CC-2904, Lonza) were cultured on a 0.1% gelatin-precoated T75 flask with DEME/F-12 medium supplemented with 10% FBS, Sodium Pyruvate, MEM Non-Essential Amino Acids Solution, and Penicillin/Streptomycin at 37°C with 5% CO2. After 1 passage, cells were plated in a 6 cm dish (2.5x10⁴ cells/ml) with 6 ml of culture medium and cultured for 1 day. After 16 hours starvation in DMEM/F-12, 0.5% FBS, the active form of TGF-β (10 ng/ml, Cat# 100-21C, PeproTech) was added to each dish for stimulation with or without the T8Ab. After 1 hour 4239-108688-03 cells were collected for immunoblotting. Gel contraction assay [0240] The gel contraction assay was performed as previously described (Alexanian, M. et al. A transcriptional switch governs fibroblast activation in heart disease. Nature 595, 438- 443, 2021). Briefly, mouse cardiac fibroblasts were plated in T75 flasks (5 x 10⁵ cells/flask) with DEME/F-12 medium supplemented with 10% FBS, Sodium Pyruvate, MEM Non- Essential Amino Acids Solution, Penicillin/Streptomycin, and cultured at 37 °C, 5% CO₂. After one day the medium was changed to basic DMEM/F-12 medium containing 0.5% FBS (low serum medium) for 16 hours starvation. Cells were then trypsinized, collected in a low serum medium, centrifuged, and resuspended in fresh low serum medium, and kept on ice before adding ice-cold PureCol® EZ Gel (Neutralized Type I Collagen Solution, ~5 mg/ml, Cat# 5074, Advanced BioMatrix) to prepare a cell/gel mixture with 2.5x10⁵ cells/ml and 1 mg/ml collagen gel. TGF-β (10ng/ml) was added to the cells/gel mixture with or without the T8Ab (20 μg/ml) before plating 500ul mixture/well (1.25x10⁵ cells/well) of an untreated 24- well plate and allow the cells/gel mixture to solidify at 37 °C, 5% CO₂ for 2 hours. After supplementing the well with an additional 500 μl of the appropriate medium, the cells/gel mixture was gently detached from the bottom of each well and cultured for 48 hours before capturing a picture of each well with a reverse microscope (ZEISS SteREO Discovery.V20). The surface area of each cell/gel mixture was quantified using Fiji (v2.14.0) and the contraction ability was calculated by the following formula: 1 – (surface area of the cells/gel) / (total area of the well). RT-qPCR assay [0241] RNA was purified using the RNeasy Mini Kit (Cat# 74104, Qiagen). The cDNA was prepared from 1 μg of RNA using the RevertAid First Strand cDNA Synthesis Kit (Cat# K1621, ThermoFisher) and RT-qPCR was performed using the iTaq™ Universal SYBR® Green Supermix (Cat# 1725120, BioRad). All procedures were performed according to the specific kit manufacture’s protocol. Detailed information on all the primers is provided in Table 8 (FIG.35). Cell lysates, coimmunoprecipitation and immunoblotting analysis [0242] Plated cells were rinsed twice with ice-cold PBS before adding RIPA lysis buffer 4239-108688-03 (Cat# 20-188, Millipore) supplemented with protease/phosphatase inhibitor cocktail. Cells were then scraped, collected, and sonicated. Lysates were cleared by centrifugation at 14000 x rpm, 10 min, 4 °C before adding Laemmli Sample Buffer for immunoblotting. For immunoprecipitation, cells were rinsed twice with ice-cold PBS and lysed with lysis buffer (25 mM Tris, pH 7.5, 75 mM NaCl, 0.5% Triton X-100, 10% Glycerol, protease/phosphatase inhibitor cocktail-Cat# 78443, ThermoFisher). Plates were then scraped, and supernatants collected, incubated with rotation at 4°C for 40 min, cleared by centrifugation (14,000xrpm, 10min, 4 °C) and quantified by Pierce™ BCA Protein Assay Kits (Cat# 23225, ThermoFisher). For each co-IP 1 mg of protein lysate was incubated with 10ul of Dynabeads™ Protein G (Cat# 10003D, ThermoFisher) for 1 hour with rotation at 4°C to preclear non-specific binding proteins. Precleared lysates were then transferred to a new tube and 1 μg antibody was added and incubated overnight at 4°C before adding 10 μl of Dynabeads™ Protein G for an additional 2 hour incubation with rotation at 4°C. Beads were then washed 5 times with cell lysis buffer and eluted with Laemmli Sample Buffer (Cat# 1610747, BioRad). Sample buffer was boiled for 10 min before immunoblotting. Proximity ligation assay (PLA) [0243] Eight-well Cell Culture Slides (Cat# CCS-8, MatTek) were coated with Poly-D- Lysine (Cat# 5049, Advanced BioMatrix) before plating 3.5 x 10³ mouse cardiac fibroblasts in 500 μl DEME/F-12, 10% FBS, Sodium Pyruvate, and MEM Non-Essential Amino Acids Solution. Cells were cultured at 37°C, 5% CO2 for one day before changing the medium to low serum (0.5% FBS). After 16 hours of starvation, TGF-β (10ng/ml) was added for stimulation and after 1 hour the slides were transferred on ice and the PLA was performed according to the manufactures protocol⁶². Detailed information on the reagents used for PLA is provided in Table 9, FIG.36. Histology and immunofluorescence (IF) staining [0244] Mouse hearts were collected and fixed overnight in 10% formalin before dehydration and paraffin embedding.5 µm sections were then stained with Picro-sirius Red Stain Kit (Cat# ab150681, Abcam) according to the manufacture instructions to visualize collagens fibers in heart sections. For IF staining, hearts were dissected, rinsed, and carefully infused with OCT before embedding in OCT and cryopreserving.5 µm frozen sections were cut onto Superfrost Plus slides (Cat# 12-550-15, Fisher) and the sections were fixed with 1% 4239-108688-03 PFA for 20 minutes before blocking and permeabilizing for 1hour at room temperature with 1% blocking reagent (Cat# 11096176001, Roche) containing 0.1% Triton X-100. Samples were then incubated with c37 anti-rabbit ANTXR1 (AbCam cat no. ab241067) diluted 1/100 in 1% blocking buffer containing 0.1% Triton X-100 for 2 hours at room temperature followed by FITC-labeled anti-rabbit (Cat# 111-095- 144, Jackson ImmunoResearch) and 488-linked goat anti-FITC (Cat# A11055, ThermoFisher). IF of denatured collagen in the heart tissue was performed according to published protocols (Hwang, J. et al. In Situ Imaging of Tissue Remodeling with Collagen Hybridizing Peptides. ACS Nano 11, 9825-9835, 2017). Cardiac cells were stained with an anti-cardiac troponin T (BD Pharmingen™ Alexa Fluor® 647 Mouse) for 30 minutes at room temperature before being cover slipped with a Vectashield^ PLUS Antifade Mounting Medium with DAPI. Images were acquired on a Leica DMi8 microscope equipped with a Yokogawa CSU-W1 Spinning Disk Confocal and Andor Zyla 4.2 sCMOS camera controlled by Andor Fusion software, using a 40x NA1.4 oil lens (Leica). Deconvolution was performed with Fusion software. For ANTXR1 and TGFBR1 IF staining, mouse cardiac fibroblasts were cooled down on ice for 10 minutes after stimulation, as above, before adding anti-ANTXR1 antibody clone m830 (1mg/ml, 1/100 dilution) for a 1 hour incubation. After rinsing three times with ice-cold culture medium and two times with ice-cold PBS, cells were fixed with 1% PFA for 20 min (10 min on ice and 10 min at RT), blocked and permeabilized with a 1% blocking reagent (Cat# 11096176001, Roche) containing 0.1% Triton X-100 for 10 min at room temperature and incubated with anti-TGFBR1 antibody (1/100 dilution) diluted in 1% blocking buffer, 0.1% Triton X-100 for 1 hour. For YAP and SMAD2/3 IF staining, the 1% blocking buffer contained 0.2% Triton X-100. Fiji (v2.14.0) was used for quantitative analysis. ANTXR1 knockout and rescue in mouse cardiac fibroblasts [0245] Cardiac fibroblasts were established from the C57BL6-ANTXR1^flox/flox mice that also contained a temperature-sensitive SV40 TAg transgene (Immortomouse, The Jackson Laboratory) and then infected with a Cre Recombinase Adenovirus (Ad-Cre-IRES-GFP, Cat# 1710, Vector Biolabs) to knockout the Antxr1 gene. Two days post infection, GFP-positive cells were sorted by flow cytometry followed by validation of complete knock out by WB analysis. eGFP Adenovirus (Ad-GFP, Cat# 1060, Vector Biolabs) was used as a negative control. For rescue experiments, the full-length and the cytosolic domain-deleted (355-564 aa, ANTXR1-CytDel) human Antxr1 c-DNA were inserted into a pLenti vector (Cat# 17448, 4239-108688-03 Addgene). Second-generation lentivirus particles were prepared for each lentivurus and an empty pLenti-GFP vector, as a control before transfection of ANTXR1 knockout cardiac fibroblast. Two days after infection, cells were treated with 6 μg/ml puromycin to select for stable CF cell lines. Flow cytometry assay [0246] Cells were trypsinized, rinsed, and resuspended in 200 μl ice-cold PBS containing 0.5% BSA (PBSA). One μg of relevant antibody was added to 2 million cells for a 1 hour incubation on ice. After three washes with PBSA, the fluorescence-labeled secondary antibody was added for a 30-minutes incubation on ice before 3 additional washes with PBSA and analysis using a BD LSRFortessa apparatus. Data was analyzed using FlowJo software (v10.8.1). Bone marrow-derived macrophage assay [0247] Mouse bone marrow cells were isolated according to published protocols (Palmieri, E. M. et al. Nitric oxide orchestrates metabolic rewiring in M1 macrophages by targeting aconitase 2 and pyruvate dehydrogenase. Nat Commun 11, 698, 2020). Briefly, femurs of C57BL/6 mice were flushed with sterile ice-cold PBS and collected cells were washed with ice-cold PBS and treated with ACK lysing buffer (Cat# A1049201, Gibco) to lyse red blood cells. Purified cells were resuspended in DMEM/F-12 medium supplemented with 10% FBS, Sodium Pyruvate, MEM Non-Essential Amino Acids Solution, Penicillin/Streptomycin, and 10 ng/ml recombinant murine M-CSF (Cat# 315-02, PeproTech), plated in 6-well plates (6 million cells/well with 5 ml medium) and cultured for 6 days changing medium every 3 days. At day 6 cells were transferred to a 6 cm dish at a concentration of 1.5 million cells/dish in 5ml medium and stimulated with TGF-β with or without an ANTXR1 antibody as done for cardiac fibroblasts (see above). After 1 hour of TGF-β stimulation, cells were collected for WB analysis. Prediction of protein crystal structure and protein interaction [0248] The structure of the anti-ANTXR1 antibody T8Ab1: L2 used in these studies was modeled using the ABodyBuilder2 while the structure of the extracellular domain (ECD) of ANTXR1 (PDB ID: 3N2N) was downloaded from the PDB website. Docking between the ANTXR1 ECD and each antibody was performed on the HADDOCK2.4 server with default parameters. The predicted complex with the highest HADDOCK score of each conformation 4239-108688-03 was selected and the structural graphics were analyzed and visualized in PyMOL (v2.5.0). Quantification and statistical analysis [0249] An unpaired 2-tail Student’s t-test was used to calculate differences between two groups, except for Violin plots, where a Wilcoxon text was used. An ordinary one-way ANOVA was used calculate differences between three or more groups with Tukey’s post-hoc method to control for experiment-wise error. For Kaplan Meier survival analysis, a Log-rank (Mantel-Cox) test was used to compare arms. Differences between two groups were presented as the mean ± SEM or mean ± SD as noted in Figure Legends. Experimental sample numbers (n) are indicated in Figure Legends. All tests were two-sided and p values < 0.05 were considered statistically significant. All statistical analysis was performed with GraphPad Prism 10.2.0. Example 2 ANTXR1 promotes heart failure post-MI [0250] To evaluate ANTXR1 in ischemic heart disease, ANTXR1 protein was assessed in samples derived from the injured heart of post-MI heart transplant recipients. Co- immunofluorescence (IF) staining revealed low ANTXR1 throughout cardiomyocyte-rich [cardiac troponin1(TNNI3)-positive] non-infarct regions and high ANTXR1 in focal “hotspots” of the cardiomyocyte depleted (TNNI3 negative) scar regions (FIG.1A and FIG. 7). Importantly, in 2-month post-MI samples ANTXR1 focal staining was most prominent at sites of active collagen remodeling, based on co-localization with denatured collagen detected using a collagen hybridizing peptide (CHP) (FIG.7B). Immunoblotting confirmed the overexpression of ANTXR1 protein in the infarct region of the human heart, which was inversely proportional to the troponin level (FIG.1B). Evaluation of public scRNAseq datasets also revealed elevated ANTXR1 mRNA in CFs derived from HCM and DCM patients (FIG.1C). Furthermore, IF staining and immunoblotting revealed increased ANTXR1 protein in HCM and DCM compared to non-failing heart samples, with expression localized to interstitial stromal cells (FIGs.1D-1F and Table 1, FIG.28). These studies demonstrate a widespread induction of ANTXR1 in various human heart diseases. [0251] Next, ANTXR1 expression was analyzed using a mouse model wherein MI is evoked by permanent ligation of the left anterior descending (LAD) coronary artery. ANTXR1 protein expression in lysates from the infarct region of the left ventricle (LV) peaked 5 to 14 days post-MI but remained low or below detection in both the distal region of 4239-108688-03 the infarcted heart and LV from non-infarcted sham controls that also underwent surgery but without LAD ligation (FIG.1G). IF staining of the infarcted heart revealed localized ANTXR1 expression throughout the troponin negative scar region, reaching peak levels between day 7 to 14, then gradually decreasing by day 42 post-MI (FIG.1H and FIG.8). ANTXR1 was undetectable in sham controls and antibody specificity was verified by a loss of staining in MI hearts from ANTXR1 KO mice (FIG.8). [0252] Intrigued by ANTXR1’s localized upregulation in the injured scar region at sites of active collagen remodeling, ANTXR1’s functional role was evaluated by inducing MI in ANTXR1 WT or KO mice. Surprisingly, echocardiography revealed improved cardiac function, including enhanced contractile performance (ejection fraction [EF] and fractional shortening [FS]) in the ANTXR1 KO group 28 days following ischemic injury (FIG.2A and Table 2, FIG.29). Based on this unexpected finding, the ability of ANTXR1 blocking antibodies to improve heart function post-MI was tested. For this, a fully cross-species (human/mouse) reactive anti-ANTXR1 antibody called L2 (herein called T8Ab) was tested. T8Ab was previously developed for cancer therapy and displayed no evidence of toxicity following 6 weeks of treatment (20 mg/kg; 3x/week) (Chaudhary, A. et al. TEM8/ANTXR1 blockade inhibits pathological angiogenesis and potentiates tumoricidal responses against multiple cancer types. Cancer Cell 21, 212-226, 2012). T8Ab is a human/mouse reverse chimera that contains a fully human variable domain fused to a murine constant domain, which minimizes immunogenicity and enables long-term repeated dosing in immunocompetent mice. In this study, C57BL6 mice were treated intraperitoneally with 15 mg/kg of T8Ab 3x/week for 42 days, starting 24h after MI (FIG.2B). While heart function gradually declined from day 1 to 42 in the vehicle-treated MI group, T8Ab treatment strikingly improved heart function during the same period (FIGs.2C,2D and Table 3, FIG. 30). Moreover, 67% of mice survived in the T8Ab treated group compared with only 35% in the vehicle-treated group (FIG.2E). Example 3 ANTXR1 drives hypertensive HF [0253] While IF staining of ANTXR1 was undetectable in sham control hearts, following MI ANTXR1 was expressed not only in the ischemic LV scar region, but also in the non- ischemic left atrium (LA) (FIG.1H and FIG.8). Prominent fibrosis in the LA of the injured heart was previously attributed to pressure overload. These data, along with the hypertensive HCM/DCM results (FIGs.1C-1F), suggest that ANTXR1 levels mirror the fibrotic response 4239-108688-03 and may be induced in CF by both ischemia and hypertension. To determine the role of ANTXR1 in non-ischemic heart disease driven by pressure overload, an angiotensin II (ATII)/phenylephrine (PE)-induced heart hypertension mouse model was adopted (FIG.2F). In this study, starting one day after ATII/PE commencement, mice were treated with vehicle or T8Ab antibody 3x per week and evaluated after four weeks. Echocardiography revealed significantly improved LV systolic and diastolic function in the T8Ab group at day 28 accompanied by reduced fibrosis (FIG.2G, FIG.9 and Table 4, FIG.31), indicating that ANTXR1 antagonism could also prevent hypertension-induced HF. [0254] Improved heart function following T8Ab treatment could potentially result from variable domain (VD)-mediated function blocking activity, or through Fc mediated mechanisms – for example, the recruitment of Fc-gamma receptor (FcγR) positive cells, such as macrophages or other hematopoietic cells, to the injured site. To evaluate the impact of the Fc domain, three amino acid substitutions (L234A, L235A, and P329G) were introduced into the heavy chain of the T8Ab to create a stable and immunologically inert Fc inactive mutant, called T8Ab-FI, with a disrupted ability to bind FcγR. Importantly, T8Ab-FI treatment protected the heart from hypertensive injury (FIG.10 and Table 5, FIG.32), suggesting that antibody binding to ANTXR1 was more important than FcγR binding for its cardioprotective activity. Taken together with the improved cardiac function in ANTXR1 KO vs WT mice, the findings show that ANTXR1 functional blockade appears to be required for T8Ab cardioprotective activity, while Fc mediated interactions appear inconsequential. [0255] Next, the role of ANTXR1 was explored using an obesity triggered model of HFpEF (FIG.2H) (Schiattarella, G. G. et al. Nitrosative stress drives heart failure with preserved ejection fraction. Nature 568, 351-356, 2019). One day following high fat diet and N^[w]-nitro-l-arginine methyl ester (HFD/L-NAME) initiation, mice were treated with vehicle or T8Ab antibody 3x/week for 35 days. While EF% was not altered in this model, as expected, myocardial and diastolic function were improved by T8Ab treatment, based on an increase in LV global longitudinal strain (GLS) and a decrease in mitral valve (MV) E/e′ ratios (FIG.2I, FIG.11 and Table 6, FIG.33). Because patients with HFpEF typically experience shortness of breath, lack of energy, and exercise intolerance, mice exposed to HFD/L-NAME were also subjected to a running test. As shown in FIG.2I, T8Ab treatment resulted in significantly longer run times compared to the vehicle treated group. Taken together, the findings show that T8Ab improved cardiac function in multiple models of heart disease, including that driven by MI, pressure overload and obesity (HFpEF). 4239-108688-03 Example 4 T8Ab cardioprotection post-MI [0256] To gain insight into the mechanisms by which ANTXR1 regulates heart function, single-cell RNA sequencing (scRNA-seq) data on 117,481 cardiac cells derived from five experimental groups was collected using the 10X Genomics platform: Sham + vehicle control, MI-d7 + vehicle, MI-d7 + T8Ab, MI-d14 + vehicle and MI-d14 + T8Ab (FIG.2B). Unsupervised clustering of the scRNAseq data revealed various cardiac cell subpopulations including CFs, endothelial cells (ECs), smooth muscle cells (SMCs), macrophages and other hematopoietic cells, as well as a small population of cardiomyocytes (FIG.3A and FIGs. 12A,12B). The CF population was comprised of 6 subclusters (CF1-6), all of which expressed Antxr1 mRNA and could be further subdivided into resting (CF1-3) and activated (CF4-6) subpopulations, only the latter of which increased in relative proportion post-MI and expressed the activation markers Thbs4, Postn, and Cilp (FIGs.3B,3C, and FIGs.12C-12F). While Antxr1 mRNA was not found in hematopoietic cells, it was detectable in other mesenchymal cells including SMCs, epicardial cells and Schwann cells (FIG.3C). [0257] The largest population change following MI was the expansion of the CF4-6 clusters at both day 7 and 14 post MI (FIG.3B and FIG.12D). Marked expansion of the Antxr1 positive CF4-6 populations is consistent with the increase in total ANTXR1 protein observed in the infarcted heart (compare FIG.1G with FIGs.3D,3E). Gene Ontology (GO) analysis revealed an enrichment of TGFβ and ECM organization related pathways in CF4-6, while the inflammation and ERK1/2 related pathways were enriched in CF1-3 (FIG.3F), suggesting different roles of the individual CF populations in HF. To verify if ANTXR1 protein was expressed in the expanding CF4-6 population, ANTXR1 co-IF staining was performed along with THBS4, a marker turned on in the activated CF4-6 population (FIG. 3G). Interestingly, IF staining of the LV scar region 7d post-MI revealed a high level of ANTXR1 colocalization with THBS4 (FIG.3G). Because ANTXR1 protein was seldom detected in THBS4 negative CF, these studies suggest that Antxr1 mRNA, which was present in all CF populations, may be translated into protein selectively in the expanding THBS4 positive CF4-6 clusters, similar to the post-transcriptional regulation described for other pro- fibrotic proteins. While Antxr1 mRNA was also found in epicardial cells, Schwann cells and smooth muscle cells, changes in gene expression in response to T8Ab treatment in these cell types were either undetectable (Schwann cells) or near background (epicardial cells and smooth muscle cells) (FIG.13). Taken together, it is concluded that ANTXR1 is functioning at the protein level most prominently in the CF4-6 population that rapidly expands by 7 days 4239-108688-03 post MI, providing a potential marker for activated CF in the ischemic heart. [0258] Next, gene expression alterations in CFs in response to MI and T8Ab treatment were assessed. As expected, following MI injury an increase in expression of ECM molecules involved in scar formation, such as Col1a1, Col1a2 and Fn was observed (FIG.14). Remarkably, T8Ab treatment further increased ECM levels by day 7, suggesting that ANTXR1 antagonism could accelerate early scar formation (FIG.3H). Several matricellular products that regulate ECM and modulate signaling were also accentuated by T8Ab treatment at day 7. For example, Ccn5, Comp, Cthrc1, Pdgfa, Thbs4 and Timp3 were previously shown to promote the development of a cardioprotective fibrotic scar or matrix preserving program that prevented early cardiac rupture (FIG.3H and Table 7, FIG.34). Consistent with T8Ab induction of a matrix preserving program, ANTXR1 ablation was able to block collagen degradation in the MI model (FIG.15). Similarly, several genes downregulated in response to T8Ab treatment, such as Cytl1, Pdgfra, and Smoc2, were previously found to promote cardiotoxicity (Table 7, FIG.34). GO analysis further supported the increase in ECM production by T8Ab at day 7 (FIG.16A). By day 14 all major pathways that remained activated by MI, including TGFβ induction and collagen production, had reverted back to a baseline state following T8Ab treatment (FIG.16B). To verify that TGFβ signaling was dependent on ANTXR1 in vivo, we performed IF staining for nuclear phosphorylated SMAD3 and found decreased levels at day 14 in ANTXR1 KO mice (FIG.17). [0259] Several of the T8Ab induced cardioprotective genes known to facilitate rapid scar development, such as Col1a1, Col1a2, and Col3a1, have also been implicated in chronic maladaptive ECM remodeling that occurs following scar formation. Strikingly, many of the same genes that increased significantly in response to T8Ab treatment at day 7 were decreased by T8Ab treatment by day 14 (FIGs.3H,3I). When the set of 331 T8Ab- upregulated genes at day 7 were reanalyzed at day 14, they were found to decrease on average after treatment, while day 14 T8Ab-downregulated genes (294 total) increased at day 7 post-treatment (FIGs.3J,3K), highlighting the time-dependent opposite activity of the antibody on gene expression. An exemplary case is the Postn gene, which increased with T8Ab treatment on day 7 but significantly decreased by day 14 (FIG.3L). Postn encodes periostin, a secreted matricellular protein that is essential for rapid scar formation but also drives late-stage maladaptive cardiac fibrosis. At day 14 T8Ab also prevented the MI-induced downregulation of several cardioprotective genes, including Klf15, Npr1 and Pgf (FIG.3I and Table 7, FIG.34). Together, these results indicate that ANTXR1 participates in pathological ECM homeostasis, and that ANTXR1 blockade creates a more favorable gene expression 4239-108688-03 signature that serves to minimize late-stage collagen production. [0260] MEOX1, a transcription factor activated through TGFβ signaling, has recently emerged as a pivotal mediator of fibroblast activation linked to cardiac dysfunction (Alexanian, M. et al. A transcriptional switch governs fibroblast activation in heart disease. Nature 595, 438-443, 2021). While systemic administration of BET bromodomain inhibitors demonstrated efficacy in reversing HF in mouse models by blocking MEOX1 activation and reversing the activated CF state, their broad off-target effects in normal tissues pose challenges for their clinical application in cardiovascular diseases (Alexanian, M. et al. A transcriptional switch governs fibroblast activation in heart disease. Nature 595, 438-443, 2021). T8Ab treatment selectively blocked Meox1 expression in CF at day 14, a result that was verified using RT-PCR (FIGs.3M,3N). These studies highlight the potential of T8Ab to reverse MEOX1-driven heart damage without compromising normal tissue function. [0261] Another striking alteration caused by MI was a transient reduction in the size of the blood EC cluster by day 7, which recovered by day 14, while the nearby lymphatic EC (LEC) cluster remained unchanged (FIG.3A). T8Ab treatment completely prevented the loss of blood ECs at day 7 (FIG.18A). EC loss may be the result of injury-induced endothelial-to- mesenchymal transition (EndMT), which has previously been shown to result in more collagen producing myofibroblasts at the expense of impaired angiogenesis. Consistent with EndMT, the blood EC cluster in the infarcted heart showed reduced expression of endothelial genes (e.g. Kdr, Flt, Fabp4), and increased expression of mesenchymal genes (e.g. Fn, Vim) (FIGs.18B,18C). At both day 7 and 14 post-MI T8Ab treatment largely prevented gene expression alterations in blood ECs and preserved the expression of cardioprotective genes such as Egln1, Timp3, Timp4, Epas1, Flt1 and Bmp6 (Table 7). Moreover, the T8Ab treatment also enriched angiogenesis related pathways in CFs at day 7 (FIG.16A). Although Antxr1 mRNA levels were negligible in cardiac macrophages (FIG.3c), T8Ab treatment also increased macrophage cell numbers at day 7 but not day 14, suggesting an indirect modulation of this cell population (FIG.18D). At day 7, T8Ab treatment altered the activity of several pathways in macrophages, including the induction of pro-angiogenic signaling (FIG.18E). Example 5 T8Ab cardioprotection post-hypertension [0262] To explore the impact of ANTXR1 on heart function in a preclinical model of hypertension, next scRNA-seq was performed on hearts following 4 weeks of exposure to 4239-108688-03 ATII/PE along with T8Ab or vehicle treatment (FIG.2F). In total, 106,443 processed cells were analyzed and, like the MI model, each of the major cardiac cell types was identified following unsupervised clustering (FIG.4A and FIGs.19A,19B). However, the small CF5 cluster, which enriched after MI and was characterized by high expression of cell cycle genes, was absent following 4 weeks of ATII/PE treatment, probably due to the lower number of cycling cells. Similar to the MI model, trajectory analysis revealed that the CF4,6 subclusters, which amplified following ATII/PE treatment, likely originated from the CF1-3 population (FIG.4B). While Antxr1 mRNA was again detected in epicardial cells, Schwan cells, smooth muscle cells and all fibroblast subclusters, only the activated CF4,6 populations expanded following ATII/PE, leading to an overall increase in Antxr1 positive CFs (FIGs. 4C,4D, and FIGs.19C-19F). Consistent with the MI model, by co-IF, ANTXR1 colocalized with THBS4 in the expanding population of CF following ATII/PE treatment (FIG.4E). In response to ATII/PE treatment, the newly generated CF4,6 cells displayed gene expression signatures indicative of TFG-β signaling and collagen biosynthesis, which were absent from the CF1-3 populations (FIG.4F). ATII/PE treatment induced robust ECM expression and activated the TGFβ pathway in CF similar to the MI model (FIG.20). [0263] T8Ab treatment upregulated the expression of 630 genes and reduced the expression of 511 genes in CF following pressure overload, but not in the sham (FIG.4G). Several of the upregulated genes were shared with the MI model and included cardioprotective fibrotic regulators such as Ccn2, Ccn4, Ccn5, Comp, Cthrc1 and Pdgfa (FIG.4G, bottom panel and Table 7, FIG.34). To determine if the T8Ab was also able to block collagen degradation similar to the MI model, CHP IF staining was performed. Collagen degradation was elevated ~15-fold by ATII/PE but reduced to near baseline levels following T8Ab treatment (FIGs.4H,4I). Some genes involved in proliferation, myofibroblast formation and/or fibrosis were also reduced by T8Ab treatment such as Ccnd1, Acta2 (αSMA), Fap, Ccn3 and Adamts8 (FIG.4G, bottom panel and Table 7, FIG.34). Upregulation or downregulation of mRNA expression in the scRNAseq dataset was also verified by RT-qPCR (FIGs.4J,4K). In sharp contrast to ANTXR1 antibody treatment following injury, treatment of sham controls with T8Ab had little to no impact on cell proportions (FIG.19B) and gene expression in CFs (FIG.4G) or all cardiac cells (FIG.21), highlighting the enhanced functional activity of ANTXR1 during pathological conditions. 4239-108688-03 Example 6 ANTXR1 facilitates TGFβ signaling [0264] To further explore the role of ANTXR1 in cardiac fibrosis, immortalized ANTXR1-WT (wildtype) primary cardiac fibroblasts (CF) from ANTXR1 conditional KO mice were established and treated with adeno-cre to create an ANTXR1-KO subline for comparison. ANTXR1 protein was gradually induced in ANTXR1-WT CFs in response to low serum (LS, 0.5%) versus 10% serum (FIG.5A). Next, the role of ANTXR1 in TGFβ signaling was investigated as this pathway is involved with myofibroblast formation and cardiac fibrosis, was the most prominent pathway activated in CF following both hypertension and MI, and was blocked by ANTXR1 antagonism (FIGs.3F, 4F and FIGs. 16B, 17 and 20A). CFs cultured in low serum overnight were treated with TGFβ for 4h, 24h or 48 hours which, as expected, resulted in a significant mRNA induction of myofibroblast- related markers (Acta2, Col1a1, Cthrc1 and Postn) and Antxr1 (FIG.5B and FIG.22A). Upregulation of Acta2 protein, the original myofibroblast marker, and activation of SMAD and YAP signaling by TGFβ were also verified by immunoblotting (FIG.22B). These data confirmed the reprogramming of the established primary CF into a myofibroblast-like state by TGFβ. [0265] Next, the role of ANTXR1 on TGFβ functional activity was evaluated using a collagen gel contraction assay – a mechanosensing assay that measures the ability of CF to remodel their surrounding collagen I matrices in response to TGFβ. Consistent with prior studies, treatment with TGFβ induced robust gel contraction (FIGs.5C,5D). Importantly, T8Abs largely blocked TGFβ induced collagen gel contraction in WT CFs while CF- ANTXR1-KO cells were unresponsive to TGFβ, indicating ANTXR1 participates in the TGFβ pathway in CFs. Because MMP14 is involved with TGFβ induced collagen degradation, MMP14 levels were also assessed and it was found that MMP15 levels decreased upon ANTXR1 blockade (FIG.23). To further explore the role of ANTXR1 on TGFβ activity, next immunoblotting was used to evaluate downstream signaling activity in CFs. T8Ab treatment inhibited total and phosphorylated levels of SMAD2, SMAD3 and YAP (FIG.5E), key components of an activated TGFβ pathway under mechanical stress. ANTXR1 genetic disruption also blocked SMAD2/3 and YAP, but in a more accelerated manner. Inhibition or deletion of YAP specifically in cardiac fibroblast has been shown to reduce fibrosis and improve cardiac function, following MI and hypertension. TGFβ downstream signaling was further validated by IF staining where both T8Ab treatment and loss of ANTXR1 significantly abolished the nuclear localization of active SMAD2/3 and YAP 4239-108688-03 (FIGs.5F-5H). Taken together, these studies indicate that ANTXR1 promotes TGFβ- SMAD2/3-YAP profibrotic signaling in CFs. [0266] Intrigued by the dependency of TGFβ signaling on ANTXR1, a potential relationship between the canonical TGFβ receptors (TGFBR1 and TGFBR2) and ANTXR1 in CFs was next explored. Strikingly, TGFBR1 levels were markedly reduced in ANTXR1- KO versus ANTXR1-WT CFs and decreased with time in T8Ab treated ANTXR1-WT cells (FIG.5I). In sharp contrast to TGFBR1, total TGFBR2 levels were essentially unaffected by ANTXR1 expression. TGFBR1 levels and downstream SMAD and YAP alterations could be rescued in CF-ANTXR1-KO cells by transfection with an ANTXR1 expression vector, but not an empty vector control (FIG.5J). These data suggested a potential interaction between TGFBR1 and ANTXR1. Upon co-immunoprecipitation, TGFBR1 was detected in ANTXR1 immunoprecipitates and ANTXR1 was found in TGFBR1 immunoprecipitates (FIG.24A), indicating that ANTXR1 may stabilize TGFBR1 on the cell surface. To assess cell surface co-localization, co-IF staining was performed, which revealed a substantial overlap of ANTXR1 and TGFBR1 in ANTXR1 WT CFs (FIG.24B). Importantly, TGFBR1 was not detected on the surface of ANTXR1 KO CFs consistent with its downregulation in cellular lysates (compare FIG.5J with FIG.24B). A proximity ligation assay (PLA) also verified the co-localization of ANTXR1 and TGFBR1 in CFs (FIGs.24C,24D). CF-ANTXR1-KO cells overexpressing a truncated ANTXR1 lacking its cytosolic domain retained its ability to stabilize TGFBR1 expression and signaling, indicating the extracellular and/or transmembrane domains of ANTXR1 are sufficient for the interaction (FIG.25). Together, these results suggest that ANTXR1 regulates fibrosis at least in part through its interaction with TGFBR1 on the cell surface of CFs. [0267] Like TGFBR1, ANTXR1 is highly conserved, with the mature mouse and human ANTXR1 proteins sharing ~98% amino acid identity overall. To evaluate the role of ANTXR1 in TGFβ signaling in human primary cardiac fibroblasts (hCF), we tested T8Ab (L2; T8Ab1), which we determined could also block TGFβ signaling in mouse CFs (FIG. 5K). Antibody docking prediction followed by alanine scanning mutagenesis revealed that T8Ab1 bound a region on the surface of the ANTXR1 ECD (FIG.26). Treatment with T8Ab1 decreased TGFβ signaling in hCF, resulting in decreased levels of TGFBR1, SMAD2/3, and YAP (FIG.5L). [0268] While accumulating data indicate a maladaptive role of TGFβ signaling in CFs, TGFβ/SMAD3 signaling in macrophages is thought to be cardioprotective. Antxr1 mRNA and protein in macrophages were undetectable (FIGs.3C, 4C, and FIG.27A), suggesting that 4239-108688-03 TGFβ signaling in this cell type may not depend on ANTXR1. As expected, T8Ab selectively antagonized TGFβ signaling in CF but not macrophages (FIG.5K and FIG.27B), highlighting the specificity of ANTXR1 targeting. Thus, ANTXR1 promotion of TGFβ signaling in CFs can be antagonized through antibody blockade (FIG.6) providing a potential avenue for selectively blocking maladaptive collagen synthesis while maintaining TGFβ dependent cardioprotective activities. Example 7 Conditional knock-out of the ANTXR1 in cardiac fibroblasts [0269] This example describes production of a conditional knock-out of the ANTXR1 gene in cardiac fibroblasts of mice. [0270] To conditionally knockout the ANTXR1 gene specifically in cardiac fibroblasts, a mouse strain was identified that could express cre specifically in fibroblasts. For that, the col1a2-cre-ER2 strain, available at The Jackson Laboratory, was used. To evaluate cre function, the cre-driver strain was crossed to the mTmG reporter mouse (also from The Jackson Laboratory). Mice containing both transgenes were then fed a normal control diet or a tamoxifen-containing diet, and then treated with ATII/PE using a 28-day slow-release Alzet osmotic pump. 28 days later, hearts were removed and assessed by immunofluorescence staining (FIG.37). In mice with the mTmG transgene, cells only switch to eGFP expression if cre is expressed. As shown in FIG.37, cre (eGFP) was only detected in mice fed tamoxifen (TAM). The cre-positive cells also showed co-localized staining with PDGFRA, a marker of cardiac fibroblasts. [0271] The preclinical mouse studies described herein show improved heart disease outcomes using ANTXR1 global knockout versus wildtype mice and following treatment of wildtype mice with ANTXR1 neutralizing antibodies. However, these studies do not provide information on the ANTXR1 positive cell types that promote heart disease. Because the scRNAseq analysis implicated cardiac fibroblasts as the likely ANTXR1 positive cell type, to directly assess the functional role of these cells in vivo, conditional ANTXR1 KO mice were created using the tamoxifen-inducible col1a2-cre-ER2 driver. Mice containing col1a2-cre and a ANTXR1 wildtype (+) or a floxed (fl) allele were fed a tamoxifen diet. The mice were then treated with ATII/PE by implanting slow-release Alzet osmotic pumps. After 28 days, heart function was analyzed by echocardiography and several measures, including percent ejection fraction (EF), were collected. As shown in FIG.38, heart function improved in mice containing a the floxed allele, indicating that high ANTXR1 expression in cardiac fibroblasts 4239-108688-03 was detrimental for heart function. Example 8 ANTXR1 antibody improve outcomes in female mice following MI [0272] This example shows that the cardioprotective effect of ANTXR1 antibody treatment is exhibited in female mice. [0273] Because heart disease is typically worse in males than females (at least prior to menopause), the preclinical mouse MI studies described above employed male mice. However, to determine if ANTXR1 antibodies can also protect females from heart disease, in this study female mice were subjected to the LAD-ligation model of MI as described above. Starting 1 day following MI, mice were treated with T8Ab (L2 anti-ANTXR1 antibody) at a dose of 15 mg/kg. As shown in FIG.39, the percent Ejection Fraction (EF), a key measure of heart function, decreased following MI. By 14- and 28-days post MI, heart function had improved significantly in the antibody treated group. Example 9 ANTXR1 antibody improves outcomes in hypertension model when treatment is initiated after injury [0274] This example shows that the cardioprotective effect of ANTXR1 antibody treatment is observed even when treatment is initiated after injury. [0275] In the preclinical mouse hypertension studies described above, ANTXR1 antibody treatment began one day following ATII/PE treatment, before heart damage had occurred. Evidence in this example shows that the ANTXR1 antibody treatment also improves outcomes in mice with pre-established heart damage. Mice were treated with ATII/PE for one-week, at which time heart function had decreased as assessed by echocardiography – for example, average EF% decreased from about 80% at baseline to about 40%. At that time, mice were randomized into two groups and administered vehicle or T8Ab (L2 anti-ANTXR1 antibody) at a dose of 15 mg/kg. As shown in FIG.40, by day 28 of ATII/PE, heart function in the T8Ab treated group had significantly increased compared to the vehicle treated control group. Example 7 Discussion [0276] In the current study, ANTXR1 was found to be elevated in activated cardiac 4239-108688-03 fibroblasts after cardiac injury. The findings reveal a deleterious role for ANTXR1 in heart disease triggered by ischemia, hypertension, and obesity. ANTXR1 antagonism accelerated beneficial scar formation, augmented the production of cardioprotective matricellular proteins, and suppressed late-stage chronic maladaptive collagen turnover. [0277] In the case of hypertension, the heart initially responds through physiologic hypertrophy (i.e. increased muscle mass), which helps compensate for elevated blood pressure. While physiological hypertrophy is initially reversible, prolonged stress, particularly in the presence of escalating blood pressure, triggers an excess of interstitial fibrosis, thereby introducing further rigidity to the LV wall. Although this newly formed ECM may help protect the cardiac wall from rupture, excessive CF expansion and ECM remodeling lead to reduced contractile function and further cardiomyocyte loss. By preventing excessive collagen turnover, which is a potential precursor to impaired cardiac function, ANTXR1 antibodies hold the potential to arrest chronic damage and preserve the viability of cardiomyocytes. [0278] While a connection between ANTXR1 and the TGFβ pathways has not yet been described, here we found ANTXR1 to play a pivotal role in promoting canonical TGFβ- SMAD signaling, a pathway well-known for inducing collagen transcription and maladaptive fibrosis in CF. At day 7 post-MI, ANTXR1 blockade stimulated the expression of genes associated with ECM production, including collagen and matricellular proteins through an unclear fibroblast-specific mechanism. T8Ab also blocked collagen degradation and induced a matrix preserving program involving overexpression of Timp1 and Timp3. By day 14, ANTXR1 antibodies blocked the production of TGFβ inducible matrix-forming genes, such as Col1a1 and Col1a2. These findings underscore the ability of T8Ab to halt ANTXR1- dependent TGFβ signaling that drives late-stage maladaptive collagen remodeling, thereby impeding the progression of fibrosis. [0279] In summary, following cardiac stress, ANTXR1 protein is induced to high levels within a newly formed population of activated CF where it promotes maladaptive collagen remodeling by amplifying TGFβ signaling. ANTXR1 neutralizing antibodies successfully accelerated scar formation, impeded late-stage collagen turnover post-MI, and prevented maladaptive TGFβ driven collagen remodeling. While previous attempts to improve heart function through the blockade of TGFβ signaling have shown limited clinical success, ANTXR1 antagonists have the potential to selectively block collagen turnover in CFs without compromising the cardioprotective activities of TGFβ, positioning them as a promising safe and effective therapeutic modality for the treatment of all forms of heart disease. 4239-108688-03 It will be apparent that the precise details of the methods and compositions described may be varied or modified without departing from the spirit of the described aspects of the disclosure. We claim all such modifications and variations that fall within the scope and spirit of the claims below.

Claims

4239-108688-03 Claims: 1. A method of treating or reducing the risk of cardiovascular disease in a subject, comprising: administering to a subject with or at risk of cardiovascular disease a therapeutically effective amount of an antibody or antigen binding fragment thereof that specifically binds to the extracellular domain of Anthrax Toxin Receptor 1 (ANTXR1) on the cell surface, to treat or reduce the risk of the cardiovascular disease in the subject. 2. The method of claim 1, wherein the cardiovascular disease is ischemic heart disease, progressive heart failure, heart disease caused by atherosclerosis, coronary artery disease, myocardial ischemia, myocardial infarction, hypertensive heart disease, cardiomyopathy, and/or Heart Failure with preserved Ejection Fraction (HFpEF). 3. The method of claim 1 or claim 2, further comprising selecting the subject with or at risk of the cardiovascular disease for treatment. 4. The method of any one of claims 1-3, wherein the antibody or antigen binding fragment thereof specifically binds to the extracellular domain of ANTXR1 on the cell surface. 5. The method of any one of claims 1-4, wherein the antibody or antigen binding fragment comprises: a heavy chain variable region (VH) comprising a heavy chain complementarity determining region (HCDR)1, a HCDR2, and a HCDR3 set forth as SEQ ID NOs: 3, 4, and 5, respectively, and a light chain variable region (VL) comprising a light chain complementarity determining region (LCDR)1, a LCDR2, and a LCDR3 set forth as SEQ ID NOs: 6, 7, and 8, respectively [L2 CDRs]; a VH comprising a HCDR1, a HCDR2, and a HCDR3 set forth as SEQ ID NOs: 13, 14, and 15, respectively, and a VL comprising a LCDR1, a LCDR2, and a LCDR3 set forth as SEQ ID NOs: 16, 17(GKN), and 18 [m825 CDRs], respectively; or a VH comprising a HCDR1, a HCDR2, and a HCDR3 set forth as SEQ ID NOs: 24, 25, and 26, respectively, and a VL comprising a LCDR1, a LCDR2, and a LCDR3 set forth as SEQ ID NOs: 27, 28(AAS), and 29 [m830 CDRs], respectively. 4239-108688-03 6. The method of claim 5, wherein the antibody or antigen binding fragment comprises: the VH and VL comprising the HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 set forth as SEQ ID NOs: 3, 4, 5, 6, 7, and 8, respectively, and wherein the remaining residues of the VH and VL comprise amino acid sequences at least 90% identical to SEQ ID NOs: 1 and 2, respectively [L2]; the VH and VL comprising the HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 set forth as SEQ ID NOs: 13, 14, 15, 16, 17(GKN), and 18, respectively, and wherein the remaining residues of the VH and VL comprise amino acid sequences at least 90% identical to SEQ ID NOs: 11 and 12, respectively [m825]; or the VH and VL comprising the HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 set forth as SEQ ID NOs: 24, 25, 26, 27, 28(AAS), 29, respectively, and wherein the remaining residues of the VH and VL comprise amino acid sequences at least 90% identical to SEQ ID NOs: 22 and 23, respectively [m830]. 7. The method of claim 5 or claim 6, wherein the VH and the VL comprise SEQ ID NOs: 1 and 2, respectively, SEQ ID NOs: 11 and 12, respectively, or SEQ ID NOs: 22 and 23, respectively. 8. The method of any one of the prior claims, comprising administering the antibody to the subject. 9. The method of claim 8, wherein the antibody comprises a human constant domain. 10. The method of claim 9, wherein the antibody is a human antibody. 11. The method of claim 9 or claim 10, wherein the antibody is an IgG. 12. The method of any one of claims 9-11, wherein the antibody comprises a recombinant constant domain comprising a modification that increases the half-life of the antibody. 13. The method of claim 12, wherein the antibody comprises a recombinant 4239-108688-03 constant domain comprising a modification that disrupts Fc receptor binding. 14. The method of claims 12 or 13, wherein the recombinant constant domain comprises a LALA-PG mutation according to the EU numbering system. 15. The method of any one of claims 1-4, wherein the antibody comprises a heavy chain and a light chain set forth as SEQ ID NOs: 9 and 10, respectively, SEQ ID NOs: 20 and 21, respectively, or SEQ ID NOs: 30 and 31, respectively. 16. The method of any one of claims 1-7, comprising administering the antigen binding fragment to the subject. 17. The method of claim 16, wherein the antigen binding fragment is a Fv, Fab, Fab', F(ab')2, scFV or scFV2. 18. The method of any one of the prior claims, wherein administering the antibody or antigen binding fragment prevents or treats myocardial ischemia by reducing direct ischemic injury, ischemia, or reperfusion injury. 19. The method of any of the prior claims wherein the subject is a human. 20. The method of any of the prior claims wherein the antibody or antigen binding fragment blocks an interaction between ANTXR1 and collagen. 21. The method of claim 20 wherein the collagen is type I or type VI collagen. 22. The method of any one of the prior claims, wherein the myocardial ischemia is due to a myocardial infarction in the subject. 23. The method of any one of the prior claims, wherein treating the subject inhibits progression of cardiovascular disease in the subject. 24. The method of any one of the prior claims, wherein preventing or treating the myocardial ischemia reduces progressive decrease in cardiac ejection fraction following 4239-108688-03 myocardial infarction. 25. The method of any one of the prior claims, wherein treating the subject inhibits cardiac fibrosis due to myocardial infarction in the subject. 26. The method of claim 25 wherein treatment with the antibody or antigen binding fragment is initiated within 30 days of the myocardial infarction. 27. The method of any of the prior claims, wherein the amount of an antibody or antigen binding fragment is between about 0.5 mg/kg and about 50 mg/kg. 28. The method of any of the prior claims, wherein the antibody or antigen binding fragment is administered to the subject intravenously. 29. The method of any of the prior claims, wherein the antibody or antigen binding fragment is administered to the subject pericardially.