Single-cell analysis of follicular fluid reveals dysregulation of ovulatory immune function in PCOS patients undergoing ovarian stimulation

Polycystic ovary syndrome is the most common endocrine condition in women and anovulatory cause of female infertility. While a pro-inflammatory cytokines and leukocyte bias in systemic circulation is well-documented in PCOS, it is not known how this inflammation extends to or affects the ovary. Additionally, the relationship between ovulation and inflammation in PCOS is not well-defined. We hypothesize that the ovarian follicular immune environment in PCOS is uniquely dysregulated, and that resolving anovulation through ovulation induction is not sufficient to alleviate this dysregulation. Using single-cell RNA and surface protein analysis of peripheral blood and follicular fluid from patients undergoing in vitro fertilization, we discovered that both control and PCOS follicles were immunologically distinct from circulation. At a systemic level, we find that ovulation induction in PCOS does not alleviate systemic inflammation. In contrast, while healthy control ovaries experienced acute immune-directed ovulatory signaling, PCOS ovarian follicles were deficient in key pro-ovulatory cell to cell communication, and displayed instead a chronic low-grade inflammatory state with fibrotic features. Taken together, a picture emerges where acute ovulation demonstrates a well-ordered series of follicle-specific immune information flows, which are disrupted and replaced by low grade chronic inflammation in the PCOS follicle.