Hu M, Zhang Y, Li X, et al. - Since low-grade chronic inflammation is frequently seen in polycystic ovary syndrome (PCOS) patients with elevated levels of inflammatory cytokines in the endometrium, researchers sought to analyze the mechanisms underlying cytokine synthesis and increased endometrial inflammation in patients with PCOS. Endometrial biopsy samples were obtained either during the proliferative phase of the menstrual cycle or with hyperplasia from non-PCOS (n = 17) and PCOS (n = 22) patients. The distribution of protein expression and localization correlated with significantly increased androgen receptor TLR2 and TLR4-mediated activation of IRF-7 and NFkB signaling, cytokine production and endometrial inflammation were demonstrated in PCOS patients vs non-PCOS patients with and without endometrial hyperplasia. Cytokine synthesis and increased endometrial inflammation in PCOS patients is coupled with androgen-induced TLR4/IRF-7/NFkB signaling inhibited by metformin therapy.