Notoginsenoside Fc, a novel renoprotective agent, ameliorates glomerular endothelial cells pyroptosis and mitochondrial dysfunction in diabetic nephropathy through regulating HMGCS2 pathway

Background: Diabetic nephropathy (DN) is the primary cause of end-stage renal disease (ESRD), and the therapeutic strategies for DN are limited. Notoginsenoside Fc (Fc), a novel saponin isolated from Panax Notoginseng (PNG), has been reported to alleviate vascular injury in diabetic rats. However, the protective effects of Fc on DN remain unclear. Purpose: To investigate the beneficial effects and mechanisms of Fc on DN. Methods: Db/db mice were treated with 2.5, 5 and 10 mg center dot kg(-1)center dot d(-1) of Fc for 8 weeks. High glucose (HG) induced mouse glomerular endothelial cells (GECs) were treated with 2.5, 5 and 10 mu M of Fc for 24 h. Results: Our data found that Fc ameliorated urinary microalbumin level, kidney dysfunction and histopathological damage in diabetic mice. Moreover, Fc alleviated the accumulation of oxidative stress, the collapse of mitochondrial membrane potential and the expression of mitochondrial fission proteins, such as Drp-1 and Fis1, while increased the expression of mitochondrial fusion protein Mfn2. Fc also decreased pyroptosis-related proteins levels, such as TXNIP, NLRP3, cleaved caspase-1, and GSDMD-NT, indicating that Fc ameliorated GECs pyroptosis. In addition, 3-hydroxy-3-methylglutaryl-CoA synthase 2 (HMGCS2) expression was increased in diabetic group, which was partially abrogated by Fc. Our data further proved that knockdown of HMGCS2 could restrain HG-induced GECs mitochondrial dysfunction and pyroptosis. These results indicated that the inhibitory effects of Fc on mitochondrial damage and pyroptosis were associated with the suppression of HMGCS2. Conclusion: Taken together, this study clearly demonstrated that Fc ameliorated GECs pyroptosis and mitochondrial dysfunction partly through regulating HMGCS2 pathway, which might provide a novel drug candidate for DN.