Serum granulosa cell-derived TNF-α promotes inflammation and apoptosis of renal tubular cells and PCOS-related kidney injury through NF-κ.B signaling

Polycystic ovary syndrome (PCOS) is a disorder with endocrinal and metabolic problems in reproductive aged women. Evidence shows that PCOS is in a high prone trend to develop kidney diseases. In this study, we investigated the mediators responsible for PCOS-related kidney injury. We found that tumor necrosis factor (TNF-alpha) levels were significantly increased in serum and primary cultured granulosa cells (GCs) from PCOS patients. Serum TNF-alpha levels were positively correlated with serum testosterone and luteinizing hormone (LH)/follicle-stimulating hormone (FSH) ratio, suggesting its positive role in the severity of PCOS. Serum TNF-alpha levels were also positively correlated with the levels of urinary KapU, LamU, a1-MU and ss 2-MU, the markers for renal tubular cellderived proteinuria. We established a PCOS mouse model by resection of the right kidney, followed by daily administration of dihydrotestosterone (DHT, 27.5 mu g, i.p.) from D7 for 90 days. We found that TNF-alpha levels were significantly increased in the ovary and serum of the mice, accompanied by increased renal tubular cell apoptosis, inflammation and fibrosis in kidneys. Furthermore, the receptor of TNF-alpha, tumor necrosis factor receptor 1 (TNFR1), was significantly upregulated in renal tubular cells. We treated human ovarian granulosa-like tumor cells (KGN) with DHT (1 mu g/ml) in vitro, the conditioned medium derived from the granulosa cell culture greatly accelerated apoptotic injury in human proximal tubular epithelial cells (HKC-8), which was blocked after knockdown of TNF-alpha in KGN cells. Furthermore, knockdown of TNFR1 in renal tubular epithelial cells greatly ameliorated cell injury induced by granulosa cell-derived conditioned medium. These results suggest that serum TNF-alpha plays a key role in mediating inflammation and apoptosis in renal tubular cells associated with PCOS-related kidney injury.