Vaccarin suppresses diabetic nephropathy through inhibiting the EGFR signaling pathway

Abstract

Background Diabetic nephropathy (DN) is recognized as one of the primary causes of chronic kidney disease and end-stage renal disease. Vaccarin is a major component in traditional Chinese medicine Vaccaria with favorable effects on cardiovascular and metabolic diseases, including type 2 diabetes mellitus (T2DM). Nonetheless, the potential role and mechanism of vaccarin in the etiologies of DN have yet to be completely elucidated. Methods A classical T2DM was experimentally induced in mice via a high-fat diet (HFD)/ streptozocin (STZ) regimen. The renal histological changes were assessed. Masson staining and immunohistochemistry (IHC) were employed to assess renal fibrosis. Quantitative real time-PCR (RT-PCR) was utilized to quantify the mRNA levels of renal fibrosis and inflammation markers. The levels of malondialdehyde (MDA) and reactive oxygen species (ROS), as well as the contents of glutathione peroxidase (GSH-Px) were measured. The protein expression of collagen Ⅰ, TGF-β1, α-SMA, E-cadherin, P-ERK, P-EGFR(Y845), P-EGFR(Y1173), T-ERK and T-EGFR was detected by western blot. Results Our study showed that vaccarin had a beneficial impact on DN mice by improving renal function and mitigating histological damage. This was achieved through its inhibition of renal fibrosis, the reduction of inflammation cytokine overproduction, and ROS levels. Moreover, vaccarin treatment effectively suppressed epithelial-to-mesenchymal transition (EMT), a crucial process in renal fibrosis, in high glucose (HG)-induced HK-2 cells. The underlying mechanism was explored through network pharmacology analysis and molecular docking, which identified epidermal growth factor receptor (EGFR) as a potential target for vaccarin. In support, vaccarin reduced the phosphorylation levels of both EGFR and its downstream mediator, extracellular signal-regulated kinase 1/2 (ERK1/2), in diabetic kidneys and HG-treated HK-2 cells. Notably, blocking either EGFR or ERK1/2 yielded similar renal benefits as observed with vaccarin treatment. Conclusion This study revealed that vaccarin held the strong ability to attenuate renal damage via inactivation of EGFR signaling in T2DM.