The role of cytokines in immune regulation of female reproductive physiology

Cytokines act as protein mediators of the immune system and exert pleiotropic effects on the source cells and/or on target cells. Cytokines are formed in a cascade, bind to specific receptors, and influence the activity, differentiation, proliferation, and survival of immune cells of both T helper 1 (Th1) type (which has proinflammatory properties) and Th2 type (with an anti-inflammatory function). The female reproductive system is regulated by the immune system via cytokines at various physiological stages: during the ovarian cycle, maternal recognition, embryo implantation, gestation, and birth, participating in homeostasis and protection from pathogens. These processes interact under the hormonal influence of the hypothalamic­pituitary­gonadal axis. This review is aimed at addressing the involvement of some cytokines in female reproductive physiology, highlighting the maternal recognition of the embryo and implantation as immunologically important steps for fetal survival. The scientific knowledge on the role of cytokines in female reproduction processes, such as the Th1/Th2 balance and immune tolerance should advance the research in various fields of assisted reproduction in humans and animals, such as artificial insemination, embryo transfer, and in vitro fertilization. The same is true for the development of contraceptive methods and understanding of pathological processes such as uterine infections and autoimmune diseases.