doi: 10.1038/s41467-019-11814-5.
Repeated semen exposure decreases cervicovaginal SIVmac251 infection in rhesus macaques
Shaheed A Abdulhaqq 1, Melween Martinez 2, Guobin Kang 3, Idia V Rodriguez 2, Stephanie M Nichols 2, David Beaumont 4, Jocelin Joseph 1, Livio Azzoni 1, Xiangfan Yin 1, Megan Wise 1, David Weiner 1, Qin Liu 1, Andrea Foulkes 5, Jan Münch 6, Frank Kirchhoff 6, Christos Coutifaris 7, Georgia D Tomaras 4, Carlos Sariol 2, Preston A Marx 8, Qingsheng Li 3, Edmundo N Kraiselburd 2, Luis J Montaner 9
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- PMID:31434895
- PMCID: PMC6704120
- DOI: 10.1038/s41467-019-11814-5
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Repeated semen exposure decreases cervicovaginal SIVmac251 infection in rhesus macaques
Shaheed A Abdulhaqq et al. Nat Commun..
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Abstract
Semen is the vehicle for virion dissemination in the female reproductive tract (FRT) in male-to-female HIV transmission. Recent data suggests that higher frequency semen exposure is associated with activation of anti-HIV mechanisms in HIV negative sex workers. Here, we use a non-human primate (NHP) model to show that repeated vaginal exposure to semen significantly reduces subsequent infection by repeated low-dose vaginal SIVmac251 challenge. Repeated semen exposures result in lower CCR5 expression in circulating CD4+ T-cells, as well as higher expression of Mx1 (in correlation with IFNε expression) and FoxP3 in the cervicovaginal mucosa, and increased infiltration of CD4+ T-cells. Establishing in vivo evidence of competing effects of semen on transmission impacts our basic understanding of what factors may determine HIV infectivity in humans. Our results clearly indicate that repeated semen exposure can profoundly modulate the FRT microenvironment, paradoxically promoting host resistance against HIV acquisition.
Conflict of interest statement
The authors declare no competing interests.
Figures
Intravaginal semen conditioning lowers susceptibility to SIV in rhesus macaques.a 32 Rhesus macaques (Macaca mulatta) were conditioned with intravaginal application of semen and/or SIVsmB7, a replication-incompetent SIV particle for 20 weeks. These animals were then challenged with low-dose SIVmac251 (200–400 TCID50) for 16 weeks intravaginally.b Log viral load line graphs for all 32 animals in the study with grouping listed. Blue vertical dashed line indicates time-point for 50% infection for non-semen condition groups and red vertical dashed line indicates 50% infection for semen conditioned group.c Survival curve comparing SIVsmB7 conditioned vs. animals receiving CEMsup [Log-rankp = 0.7314].d Survival curve comparing semen and vehicle-conditioned animals [Log-rankp = 0,0332]. 1- and 3-month post-acquisition VL (e) and CD4 (f) were similar in semen and vehicle-treated animals. Source data are provided as a Source Data file
Semen conditioning lowers CCR5 expression on peripheral CD4+ T-cells.a Representative flow cytometry plots of CCR5 expression on peripheral CD4+ T cells in semen verses vehicle-conditioned macaques.b CCR5 expression on peripheral CD4+ T-cells was significantly lower amongst semen-conditioned animals (Man–Whitneyp = 0.0366) (top left). Reduced CCR5 surface expression was confined to central memory CD4+ T-cells (Mann–Whitneyp = 0.0298) (top right) as both naïve and effector memory CD4+ T-cells displayed no difference in CCR5 expression (bottom panels).c Principal Component Analysis (PCA) showed no segregation of animal groups based on vaginally secreted cytokines.d After the initiation of SIVmac251 low-dose challenge, semen-conditioned animals had an increase in RANTES. Error bars are represented as median with IQR. Source data are provided as a Source Data file
Semen increases CD4+ cell infiltration and Mx1 expression within the cervix.a To assess the impact of semen on cellular infiltrates of the female reproductive tract, 14 macaques were euthanized after undergoing the same 20-week treatment sequence as the 32 animals that underwent challenge. For clarity, these groups are designated with an “A” following the original group name. The ectocervix displayed 3 distinct changes in response to semen pretreatment (analyzed as vehiclen = 6; semenn = 6).b semen-conditioned animals had nearly twice as many CD4 as semen-naïve animals (447.9 vs 238 cells/mm2;p = 0.0087).c These animals also had significantly higher levels of Mx1 staining as compared to semen-naïve animals which either had little or no Mx1 staining (p = 0.0152).d Similar to Mx1, Ki-67 within the lamina propria was significantly higher in semen-conditioned animals with most staining occurring near the basal epithelium. The endocervix displayed three distinct differences between semen and vehicle-conditioned animals (analyzed as vehiclen = 6; semenn = 8).e HLA-DR staining was 3-fold higher in semen-conditioned animals (p = 0.0027).f Mx1 staining of the ectocervix mirrored staining found in the ectocervix with vehicle-conditioned animals having little to no staining in comparison (p = 0.0200).g Semen-conditioned animals had nearly 3× more FoxP3+ cells within their endocervices as compared to vehicle-conditioned animals (p = 0.0426; 16.4 vs 6.43).h Select significant ectocervical correlations are shown for CD68 vs Mx1 (lamina propria); Ki67 vs Mx1; and IFNε vs Mx1 (epithelium) are shown.i Select significant endocervical correlations are shown for FoxP3+ vs CD4+ cells; FoxP3+ cells vs IFNε; and Mx1 and IFNε. Brown (Hex Code#613026/sensitivity 40 or 60) IHC staining was pseudo-colored red (Hue: −28, Saturation: +75) for visual clarity. Quantified tissue regions are outlined. Mann–WhitneyU testing was used to compare groups.P-values below 0.05 were considered significant. Error bars are shown as median with IQR. Spearman’s rho was used to determine the correlation between staining parameters. * Indicates staining values were normalized to max. Following shipment from the study site, it was determined that one animal from Group 5 and one animal from Group 6 had endocervical tissues too degraded for interpretable staining. All figures shown with 0.1 mm scale bar included. Source data are provided in Source Data file
References
- Abdulhaqq S A, Zorrilla C, Kang G, Yin X, Tamayo V, Seaton K E, Joseph J, Garced S, Tomaras G D, Linn K A, Foulkes A S, Azzoni L, VerMilyea M, Coutifaris C, Kossenkov A V, Showe L, Kraiselburd E N, Li Q, Montaner L J. HIV-1-negative female sex workers sustain high cervical IFNɛ, low immune activation, and low expression of HIV-1-required host genes. Mucosal Immunology. 2015;9(4):1027–1038. doi: 10.1038/mi.2015.116. - DOI - PMC - PubMed
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