Anti-Bacterial Factors Secreted From Cumulus Cells of Ovulated COCs Enhance Sperm Capacitation During In Vitro Fertilization

Problem The aim of this study was to find immune-related genes expressed in cumulus cells of ovulated cumulus oocyte complexes (COCs) and to clear the functional roles during fertilization process. Method of study Ovulated COCs were collected from oviduct 16 hr after the hCG injections followed by eCG priming. The cumulus cells were used for RT-PCR or western blotting study. COCs were also used for in vitro fertilization study. Results Cramp, Trf, Lyz2, S100a8, and S100a9 were expressed in cumulus cells during ovulation process. The protein levels of CRAMP or transferrin were detected in ovulated COCs and then secreted into hyaluronan-rich matrix. The high dose of these factors reduced the proliferative activity of E. coli; however, the lower levels of them significantly increased the rate of fertilization in in vitro via the induction of sperm capacitation. Conclusion Cumulus-secreted anti-bacterial factors act on sperm to induce sperm capacitation.