Follicle‐stimulating hormone promotes renal tubulointerstitial fibrosis in aging women via the AKT/GSK‐3β/β‐catenin pathway

Estrogen withdrawal in aging women contributes to the progression of chronic kidney disease (CKD). However, the effect of high circulating follicle‐stimulating hormone (FSH) levels on renal dysfunction remains unknown. In this study, blood samples from 3,055 postmenopausal women were collected and tested, which showed that there was a strong negative correlation between eGFR and FSH levels (p < 0.001), independent of LH, testosterone, and estradiol. Functional FSHR was detected in renal tubular epithelial cells. In vivo, high circulating FSH levels promoted a phenotype of tubulointerstitial fibrosis, characterized by increases in 24‐hr urine protein/creatinine ratio, serum Cr, serum BUN, and ECM deposition. Similar results obtained from cultured HK‐2 cells showed that FSH increased the transcriptional and protein expression of profibrotic mediators (collagen IV, fibronectin, and PAI‐1). This promotion of fibrosis by FSH occurred through the activation of AKT/GSK‐3β/β‐catenin pathway, which could be attenuated by silencing FSHR by siRNA or by LY294002 or MK2206. In addition, FSH‐stimulated HK‐2 cells secreted IL‐8, which promoted macrophage migration to exacerbate tubulointerstitial fibrosis. These results revealed a previously unknown effect of FSH on kidney injury, which may offer a critical insight into the development of CKD in aging postmenopausal women.