Interleukin-22 improves ovulation in polycystic ovary syndrome via STAT3 signaling

Polycystic ovary syndrome (PCOS) is a common reproductive endocrine disease, which leads to serious impairment of reproductive health in women of child-bearing age. Anovulation or oligo-ovulation is a common clinical manifestation of PCOS patients. A disturbance of the ovarian immune microenvironment contributes to the disorders of follicle development and ovulation; however, the underlying mechanism remains unclear. Here we demonstrated the protective effect of immune factor interleukin-22 (IL-22) on PCOS follicle development and ovulation. Follicular IL-22 levels were significantly lower in PCOS patients than in the control group and were positively correlated with oocyte fertilization rate and high-quality embryo rate. Additionally, IL-22 evidently improved follicle development in vitro and promoted ovulation-related gene expression, which was disrupted by the depletion of interleukin-22 receptor 1 (IL-22R1) or inhibition of STAT3 in granulosa cells. This indicates that IL-22 acts through IL-22R1 and the STAT3 signaling pathway to promote follicle development and ovulation in PCOS. In summary, this study has elucidated the vital role of the ovarian immune microenvironment in follicle development and ovulation. Application of IL-22 may provide new insights into the treatment of PCOS patients.