Figure 2.

The role of NK cells in endometriosis-related infertility. NK cells play pivotal roles at various stages of infertility associated with endometriosis. Throughout follicular development, NK cells have the capacity to impede oocyte maturation through direct action and the secretion of cytokines. During the process of embryo transportation, NK cells derived from peritoneal fluid and blood may collaboratively exert embryotoxic effects. The implantation process witnesses a disturbed dynamic alteration in the quantity of NK cells, resulting in compromised NK cell maturation and heightened cytotoxicity, consequently leading to decreased uterine receptivity and subsequent implantation failure. Moreover, during early pregnancy, the elevated expression of CD200S on NK cells led to enhanced cytotoxicity, potentially mediating the immune rejection of the embryo. These factors collectively contribute to the infertility and miscarriage observed in patients with endometriosis. (WOI: window of implantation; EVT: extravillous trophoblasts). ↑: increased, ↓: decreased.