Roflumilast ameliorates diabetic nephropathy in rats through down-regulation of JAK/STAT signaling pathway

Roflumilast is a potent selective inhibitor of the phosphodiesterase-4 enzyme which greatly manifest an anti-inflammatory activity in chronic obstructive pulmonary patients. Inflammation is a prominent factor in the prevalence of diabetic nephropathy, one of the most prevalent microvascular complications of Diabetes Mellitus. The present study was undertaken to assess the potential role of roflumilast in diabetic nephropathy. The model was developed by feeding a high-fat diet for four weeks and following streptozotocin (30 mg/kg) injection intraperitoneally. The rats with > 13.8 mmol/L blood glucose were treated with roflumilast (0.25, 0.5, 1 mg/kg) and standard metformin (100 mg/kg) orally once a day for eight weeks. Roflumilast (1 mg/kg) remarkably improved renal damage, indicated by an increase in 16% albumin, a decrease in 5% serum creatinine, 12% BUN, 19% HbA1c, and 34% blood glucose. It also significantly improves the oxidative stress levels, which was indicated by a decrease in 18% MDA level and an increase in GSH, SOD, and catalase by 6%, 4%, and 5%, respectively. In addition, Roflumilast (1 mg/kg) decreased the HOMA-IR index by 28% and increased the pancreatic β-cells functioning by 30%. Moreover, significant improvement in histopathological abnormalities were observed in roflumilast treatment groups. Roflumilast treatment was shown to down-regulate the gene expressions of TNF-α (2.1-fold), NF-kB (2.3-fold), MCP-1 (2.5-fold), fibronectin (2.7-fold), collagen IV (2.7-fold), STAT 1(1.06-fold), and STAT 3 (1.20-fold) and upregulated the expression of the Nrf2 (1.43-fold) gene. Roflumilast manifested a potential role in diabetic nephropathy as a renoprotective agent. Roflumilast effectively down-regulates the JAK/STAT pathway and restores renal functions.