Suxiao jiuxin pill protects endothelial cells from oxidative stress-induced apoptosis via Nrf2/HO-1 pathway

Abstract Background Reactive oxygen species (ROS) are implicated in the pathogenesis of cardiovascular diseases (CVDs). Suxiao Jiuxin Pill (SX), a traditional Chinese medicine, has emerged as a promising herbal remedy with demonstrated efficacy in ameliorating cardiovascular pathology and improving clinical outcomes. Although SX exhibits significant antioxidant activities, the underlying mechanism remains unclear. Methods We utilized a mouse endothelial cell line, C166, to investigate the role of SX in regulation of oxidative stress. Hydrogen peroxide (H2O2) was employed to induce cell apoptosis. Cells were sequentially treated with SX, specific inhibitors, and H2O2. RT-qPCR and Western blot analyses were performed to evaluate changes at the mRNA and protein levels, respectively. Results SX demonstrated protective effects against H2O2-induced apoptosis in endothelial cells (ECs). Both the mRNA and protein levels of heme oxygenase-1 (HO-1) increased in response to SX treatment. Importantly, the protective role of SX in ECs was abolished by the HO-1 inhibitor Zinc protoporphyrin IX (ZnPP). Treatment with actinomycin D and cycloheximide revealed that SX upregulated HO-1 expression via de novo synthesis, and Nrf2 was verified as the main mediator. Furthermore, degradation of Nrf2 by its specific inhibitor, brusatol, reversed the protective effects of SX on ECs under oxidative stress. Conclusion SX plays a crucial role in protecting ECs from oxidative stress-induced apoptosis through activation of the Nrf2/HO-1 pathway. The protective effect of SX is dependent on HO-1 function, and inhibition of either Nrf2 or HO-1 effectively blocks the protective effect of SX.