Women with polycystic ovary syndrome exhibit impaired endometrial receptivity with excessive ERα and histone lactylation.

Polycystic ovary syndrome (PCOS) is one of the most common reproductive disorders in women and severely impairs fertility. Extant clinical studies can only provide indirect and plausible evidence to support endometrial dysfunction as an ovary-independent contributor to PCOS infertility, considering heterogeneous confounders in their phenotypes, comorbidities, and severities. By strictly controlling embryonic factors and potential confounders, our retrospective cohort study reports an adverse implantation rate in women with PCOS, confirming abnormalities in the endometrium, which are accompanied by excessive ERα and histone lactylation. Next, we validate the cooccurrence of impaired uterine receptivity with elevated ERα and histone lactylation in the PCOS mouse model. Inhibiting histone lactylation could downregulate ERα and estrogen-responsive genes, restore uterine receptivity, and improve the implantation rate in PCOS mice. Here, we show that upregulated ERα and histone lactylation are key indicators of impaired endometrial receptivity in PCOS, providing a potential therapeutic strategy by inhibiting lactate production.