Macrophage migration inhibitory factor (MIF), also known asglycosylation-inhibiting factor (GIF),L-dopachrome isomerase, orphenylpyruvate tautomerase is aprotein that in humans is encoded by theMIFgene.[5][6] MIF is an important regulator ofinnate immunity.[7] The MIF protein superfamily also includes a second member with functionally related properties, theD-dopachrome tautomerase (D-DT).[8]CD74 is a surface receptor for MIF.[9]
Bacterialantigens stimulatewhite blood cells to release MIF into the blood stream.[10] The circulating MIF binds toCD74 on other immune cells to trigger an acute immune response. Hence, MIF is classified as aninflammatory cytokine. Furthermore,glucocorticoids also stimulate white blood cells to release MIF and hence MIF partially counteracts the inhibitory effects that glucocorticoids have on the immune system. Finallytrauma activates theanterior pituitary gland to release MIF.[11]
Macrophage migration inhibitory factor assembles into atrimer composed of three identical subunits. Each of these monomers contain two antiparallelalpha helices and a four-strandedbeta sheet. The monomers surround a central channel with 3-foldrotational symmetry.[12][13]
MIF contains two motifs with catalytic activity. The first is a 27 amino acid motif located at theN-terminus functions as aphenylpyruvate tautomerase that can catalyze the conversion of 2-carboxy-2,3-dihydroindole-5,6-quinone (dopachrome) into 5,6-dihydroxyindole-2-carboxylic acid (DHICA).[14][15] MIF also contains a Cys-Ala-Leu-Cys catalytic site between residues 57 and 60 that appears to function as adisulfidereductase.[16]
Cytokines play an important role in promoting wound healing and tissue repair. Cell injury results in MIF release which then interacts withCD74. MIF-CD74 signaling activates pro-survival and proliferative pathways that protects the host during injury.[9]
Parasite-Produced MIF Cytokine in Immune Evasion, Invasion, and Pathogenesis
Multiple protozoan parasites produce homologs MIF that have similar inflammatory functions to human MIF, and play a role in their pathogenesis, invasion and immune evasion.[40][41] A preclinical study showed that blocking parasite MIF improves outcome in severe protozoan infections.[42] Examples of protozoans with MIF homologs that have been reported:
^Kozak CA, Adamson MC, Buckler CE, Segovia L, Paralkar V, Wistow G (June 1995). "Genomic cloning of mouse MIF (macrophage inhibitory factor) and genetic mapping of the human and mouse expressed gene and nine mouse pseudogenes".Genomics.27 (3):405–411.doi:10.1006/geno.1995.1070.PMID7558020.
^Günther S, Fagone P, Jalce G, Atanasov AG, Guignabert C, Nicoletti F (February 2019). "Role of MIF and D-DT in immune-inflammatory, autoimmune, and chronic respiratory diseases: from pathogenic factors to therapeutic targets".Drug Discovery Today.24 (2):428–439.doi:10.1016/j.drudis.2018.11.003.PMID30439447.S2CID53562815.
^Al-Abed Y, VanPatten S (January 2011). "MIF as a disease target: ISO-1 as a proof-of-concept therapeutic".Future Medicinal Chemistry.3 (1):45–63.doi:10.4155/fmc.10.281.PMID21428825.
^Shan ZX, Lin QX, Deng CY, Tan HH, Kuang SJ, Xiao DZ, et al. (December 2009). "[Identification of the interactions between the truncated fragments of macrophage migration inhibitory factor and CD74 using a yeast two-hybrid system]".Nan Fang Yi Ke da Xue Xue Bao = Journal of Southern Medical University (in Chinese).29 (12):2383–6, 2390.PMID20034881.
^Wang F, Shen X, Guo X, Peng Y, Liu Y, Xu S, et al. (February 2010). "Spinal macrophage migration inhibitory factor contributes to the pathogenesis of inflammatory hyperalgesia in rats".Pain.148 (2):275–283.doi:10.1016/j.pain.2009.11.011.PMID20005040.S2CID38141283.
^Kleemann R, Hausser A, Geiger G, Mischke R, Burger-Kentischer A, Flieger O, et al. (November 2000). "Intracellular action of the cytokine MIF to modulate AP-1 activity and the cell cycle through Jab1".Nature.408 (6809):211–216.Bibcode:2000Natur.408..211K.doi:10.1038/35041591.PMID11089976.S2CID205010648.
^Stosic-Grujicic S, Stojanovic I, Maksimovic-Ivanic D, Momcilovic M, Popadic D, Harhaji L, et al. (June 2008). "Macrophage migration inhibitory factor (MIF) is necessary for progression of autoimmune diabetes mellitus".Journal of Cellular Physiology.215 (3):665–675.doi:10.1002/jcp.21346.PMID18064633.S2CID36047003.
^Lue H, Kleemann R, Calandra T, Roger T, Bernhagen J (April 2002). "Macrophage migration inhibitory factor (MIF): mechanisms of action and role in disease".Microbes and Infection.4 (4):449–460.doi:10.1016/S1286-4579(02)01560-5.PMID11932196.
^Bloom J, Sun S, Al-Abed Y (December 2016). "MIF, a controversial cytokine: a review of structural features, challenges, and opportunities for drug development".Expert Opinion on Therapeutic Targets.20 (12):1463–1475.doi:10.1080/14728222.2016.1251582.PMID27762152.S2CID36752674.