Oridonin Attenuates Diabetes-induced Renal Fibrosis via the Inhibition of TXNIP/NLRP3 and NF-κB Pathways by Activating PPARγ in Rats

Introduction Oridonin possesses remarkable anti-inflammatory, immunoregulatory properties. However, the renoprotective effects of oridonin and the underlying molecular mechanisms in diabetic nephropathy (DN). We hypothesized that oridonin could ameliorate diabetes-induced renal fibrosis. Methods Streptozocin (STZ)-induced diabetic rats were provided with a high-fat diet to establish a type 2 diabetes mellitus (T2DM) animal model, and then treated with Oridonin (10, 20 mg/kg/day) for two weeks. Kidney function and renal fibrosis were assessed. High glucose-induced human renal proximal tubule epithelial cells (HK-2) were also treated with oridonin. The expression of inflammatory factors and fibrotic markers were analyzed. Results Oridonin treatment preserved kidney function and markedly limited the renal fibrosis size in diabetic rats. The renal fibrotic markers were inhibited in the oridonin 10 mg/kg/day and 20 mg/kg/day groups compared to the T2DM group. The expression of thioredoxin-interacting proteins/ nod-like receptor protein-3 (TXNIP/NLRP3) and nuclear factor (NF)-kappa B pathway decreased, while that of peroxisome proliferator-activated receptor-gamma (PPAR gamma) increased in the oridonin treatment group compared to the non-treated group. In vitro, PPAR gamma intervention could significantly regulate the effect of oridonin on the high glucose-induced inflammatory changes in HK-2 cells. Conclusion Oridonin reduces renal fibrosis and preserves kidney function via the inhibition of TXNIP/NLRP3 and NF-kappa B pathways by activating PPAR gamma in rat T2DM model, which indicates potential effect of oridonin in the treatment of DN.