REPRODUCTIVE ENDOCRINOLOGY AND INFERTILITY Male reproductive proteins and reproductive outcomes

An enormous diversity of antigenically distinct proteins is found in seminal plasma. These include proteases, protease inhibitors, signal transduction molecules, protein kinases and phosphatases, transporter proteins, structural molecules, and immune response proteins. Sperm, too, carry a plethora of surface proteins; these mediate species-specific binding to the zona pellucida surrounding the oocyte. Together, semen and sperm proteins are called male reproductive proteins (MRPs). Male reproductive proteins have roles critical to evolution and reproductive immunology. Yet their clinical and epidemiologic impact on human reproduction is largely unstudied. The purpose of this Clinical Opinion is to suggest that MRPs may have broad influences on successful reproduction, potentially with roles in the composition of vaginal microflora, the occurrence of preterm birth and preeclampsia, and complications from assisted reproduction. As such, the import of MRPs on human reproductive success is suggested as an area ripe for future clinical and epidemiologic research.