The Role of Natural Killer Cells and Immune Factors in Implantation Failure in Women With Polycystic Ovary Syndrome

Polycystic ovary syndrome (PCOS) is a common endocrine-metabolic disorder linked to infertility and adverse reproductive outcomes. Emerging evidence highlights immune dysregulation, particularly involving natural killer (NK) cells, as a key driver of PCOS-associated implantation failure. Successful embryo implantation requires precise dialogue between the embryo and maternal endometrium, mediated by immune cells. Uterine NK (uNK) cells, the dominant immune population at the maternal-fetal interface in early pregnancy, display low cytotoxicity and high immunoregulatory and angiogenic activity. These features support trophoblast invasion, spiral artery remodeling, and maternal-fetal tolerance. In PCOS, chronic low-grade inflammation, hyperandrogenism, and insulin resistance alter immune cell phenotypes, cytokine production, and NK cell function. Such disruptions compromise the immunological balance essential for endometrial receptivity, potentially triggering recurrent implantation failure and early pregnancy loss. This review analyzes the role of NK cells and immune factors in PCOS-related implantation failure. Clarifying the crosstalk between endocrine, metabolic, and immune pathways provides deeper insights into reproductive dysfunction in PCOS, offering potential therapeutic targets to enhance implantation rates and pregnancy outcomes.

Hali tarjima qilinmagan