Roxadustat Regulates the NKA/Src/HIF-1/ROS Signaling Pathway to Improve Kidney Outcomes in Mice with Lupus

Background: Sustained release of ROS can aggravate podocyte injury in lupus nephritis. NKA（Na-K-APTase）is widely distributed in renal tissues and releases a large number of ROS after activation, which promotes the apoptosis of renal tubular epithelial cells/podocytes. Roxastat, as an inhibitor of HIF-1, can inhibit the release of ROS. We speculate that Roxastat may disrupt the positive feedback loop of ROS release by stabilizing HIF-1 protein and blocking the damage of tubular epithelial cells/podocytes, thereby protecting kidney tissue and delaying the progression of disease. Methods: Mice were divided into the following groups: 1. Control group; 2. 2. MRL/LPR model group (lupus group); 3. Roxastat intervention group（Roxa group）; Biochemical indexes: urine protein, Scr, BUN; The WB method was used to detect NKA, p-Src, HIF in mouse kidney tissue. Annexin V/PI flow cytometry was used to detect apoptotic cells. The ROS content in mouse kidney tissue was detected by flow cytometry with DCFH-DA probe method. MCP-1 and NGAL were detected by ELISA. Results: 1. Proteinuria in MRL/LPR group was significantly up-regulated compared with control group (499.36±77.67vs45.68±23.66mg/L, p < 0.001), and down-regulated in Roxa group (499.36±77.67vs277.44±45.67 mg/L, P < 0.001). p < 0.001); 2. Scr in MRL/LPR group was increased (314.18±23.67vs106.63±15.67umol/L, p < 0.05), but decreased in Roxa group (243.54±17.33vs314.18±23.67umol/L, p < 0.05); 3. MCP-1 in MRL/LPR group was significantly up-regulated (437.84±50.5vs119.90±28.9pg/ml, p < 0.001).,but decreased in Roxa group(321.38±13.5vs437.84±50.5pg/ml, p < 0.001). 4. Annexin V/PI showed up-regulated in MRL/LPR group (30.05%±2.05%vs0.21%±0.02%); decreased in Roxa group (16.23%±2.23%vs 30.5% ±2.05%). 5. The ROS release was detected by DCFH-DA : which was up-regulated in MRL/LPR group (39.88%±2.88%vs3.28%±0.28%); lower in Roxa group (26.54%±2.54%vs39.88%±2.88%). Conclusion: Roxastat may reduce the release of ROS by NKA/Src/HIF-1, thereby improving the injury of tubule/podocyte, reducing the excretion of proteinuria, and delaying the progression of lupus nephritis. Funding: Government Support – Non-U.S.