Combination of leflunomide and benazepril reduces renal injury of diabetic nephropathy rats and inhibits high-glucose induced cell apoptosis through regulation of NF-κB, TGF-β and TRPC6

Objective: To investigate effects of combination use of leflunomide and benazepril on diabetic nephropathy (DN) both in vivo and in vitro. Methods: The streptozotocin (STZ) induced Sprague-Dawley rats were treated with leflunomide (15 mg/kg/d), benazepril (15 mg/kg/d) or both the two drugs. Fasting blood glucose (FBG) and renal function indexes including blood urea nitrogen (BUN), serum creatinine (Scr), and proteinuria and kidney/body weight ratio (KW/BW) were measured. HE staining was used for histological analysis. The rat glomerular mesangial cells (RMCs) were treated with high-glucose (150 mg/ml) and the leflunomide and benazepril with both concentrations of 50 μmol/l were used to treat the high-glucose induced cells. TUNEL assay was used for measurement of cell apoptosis. Western blotting was conducted to determine expression of nuclear factor Kappa B (NF-κB), transforming growth factor-β (TGF-β) and transient receptor potential canonical 6 (TRPC6). Results: The body weight was significantly lower and all indexes of FBG, BUN, Scr, proteinuria and KW/BW ratio, GFR, as well as inflammatory factors TNF-α and IL-6 were significantly increased in the DN group after STZ treatment for 4 weeks. The treatment with leflunomide, benazepril or the both dramatically reduced the above effects induced by STZ, and the alteration was the most significant in the combination group. Treatment of leflunomide and benazepril significantly reduced expression levels of NF-κB, TGF-β and TRPC6 in renal tissues of DN rats as well as in high-glucose induced RMCs. It was also observed leflunomide and benazepril reduced high-glucose induced cell apoptosis of RMCs. Conclusion: The combination use of leflunomide and benazepril could improve the renal function and reduce the renal injury of DN rats and could reduce the levels of NF-κb, TGF-β and TRPC6 in both DN rats and high-glucose induced RMCs.