Study on Roxadustat Attenuates Renal Interstitial Fibrosis Through Inhibiting HIF-1α/Notch-1 Signaling Pathway in Rats of Unilateral Ureteral Obstruction

OBJECTIVE To study the mechanism of roxadustat(ROX) in improving renal interstitial fibrosis(RIF) in rats with unilateral ureteral obstruction(UUO). METHODS Forty-eight ♂ rats were randomly divided into sham operation group, UUO group, UUO+ROX(25, 50 mg·kg^–1) group, twelve rats in each group. The rat model of RIF was established by ligation of the left ureter. The rats were given intragastric administration for 21 d from the third day after modeling. The serum creatinine(Scr) and blood urea nitrogen(BUN) was measured. HE staining and Masson staining were used to observe the pathological changes of renal tissue and collagen deposition. The expression of TGF-β1 in renal tissue detected by immunohistochemistry. The human proximal tubular epithelial cells were cultured in vitro, divided into control group, TGF-β1 (5 ng·mL^–1) group, TGF-β1+DMSO group and TGF-β1+ROX(10, 20, 40 μmol·L^–1) group. The cells were pre-treated with DMSO or ROX for 2 h, and then subjected to TGF-β1(5 ng·mL^–1) for 48 h. The expression of collagen Ⅰ, collagen Ⅲ, E-Cadherin, Fibronectin, α-smooth muscle actin(α-SMA), Vimentin, hypoxia-inducible factor 1α(HIF-1α), Notch-1, Notch-1 intracellular domain(NICD) and Hes1 were assessed by Western blotting. RESULTS The results of animal experiments showed that, compared with UUO group, ROX significantly reduced the levels of BUN and Scr, obviously attenuated collagen deposition and expression of collagen Ⅰ and collagen Ⅲ, and reduced the degree of RIF. The expression of epithelial cell marker E-Cadherin in renal tissue increased significantly, while interstitial cell marker Fibronectin, α-SMA and Vimentin decreased significantly(P<0.05 or P<0.01). At the same time, the expressions of HIF-1α, Notch-1, NICD and Hes1 in renal tissue were significantly down regulated(P<0.05 or P<0.01). The results of cell experiments showed that, compared with the TGF-β1 group, different doses of ROX could significantly reduce the expression of HIF-1α, Notch-1, NICD and Hes1 induced by TGF-β1, the expression of E-Cadherin was significantly up-regulated and the expression of Fibronectin, α-SMA and Vimentin was significantly down-regulated(P<0.05 or P<0.01). CONCLUSION These results suggest that ROX can alleviate UUO-induced RIF in rats, which may be involved in blocking HIF-1α/Notch-1 signaling pathway and reverse tubular epithelial cell epithelial-mesenchymal transition.