Inhibition of FoxO1 alleviates polycystic ovarian syndrome by reducing inflammation and the immune response

Abstract

The aim of this study was to explore the role of forkhead box transcription Factor O1 (FoxO1) in chronic inflammation in polycystic ovary syndrome (PCOS). A PCOS rat model was constructed as an in vivo model by letrozole induction, and granulosa cells (GCs) from PCOS rats were isolated and cultured as an in vitro cellular model. FoxO1 was knocked down by shRNA and siRNA in the PCOS rat model and GCs model, respectively. H&E staining was conducted to evaluate the effect of FoxO1 inhibition on ovarian pathology and dysfunction in PCOS rats. The levels of inflammatory cytokines in the ovaries and uterus of PCOS rats and in GCs were assessed by ELISA. Flow cytometry was used to evaluate the changes in the contents of neutrophils and macrophages in the peripheral blood and spleen of PCOS rats. CCK-8 assays and Annexin V-FITC/PI staining were performed to evaluate the proliferation and apoptosis of GCs. The expression of genes and proteins related to the TLR4/NF-κB/NLRP3 pathway in GCs was determined by RT-qPCR and Western blotting. The results indicated that FoxO1 was highly expressed in PCOS rat model. Inhibition of FoxO1 significantly mitigated the pathological changes and dysfunction in the ovaries of PCOS rats while also suppressing inflammation and fibrosis in the ovaries and uterus. Moreover, knocking down FoxO1 facilitated the restoration of the normal ratio of neutrophils and macrophages in the peripheral blood and spleen of PCOS rats and promoted M2 polarization of macrophages. Additionally, inhibition of FoxO1 promoted the proliferation of GCs and inhibited the inflammatory response in GCs. Furthermore, FoxO1 knockdown inhibited the activation of the NF-κB pathway and the formation of the NLRP3 inflammasome in GCs. In conclusion, inhibition of FoxO1 can alleviate PCOS by inhibiting the TLR4/NF-κB/NLRP3 pathway to reduce inflammation and the immune response.

Keywords: FoxO1; Granulosa cells; Inflammatory response; NF-κB pathway; Polycystic ovary syndrome.