Tanshinone IIA Sodium sulfonate regulates antioxidant system, inflammation, and endothelial dysfunction in atherosclerosis by downregulation of CLIC1

Background: Tanshinone IIA Sodium sulfonate (STS) is clinically used for treating cardiovascular diseases in Traditional Chinese Medicine due to its antioxidation and anti-inflammation activities. Intracellular chloride channel 1 (CLIC1) participates in the regulation of oxidative stress and inflammation. This study investigates whether CLIC1 mediates the cardioprotective effects of STS. Methods: STS were used to treat atherosclerosis (AS) induced by feeding Apolipoprotein E-deficient (ApoE(-/-)) mice with a high-fat, cholesterol-rich diet. In addition, normal and CLIC1(-/-)human umbilical vein endothelial cells were treated with STS after exposure to H2O2 for 12 h. The oxidative status was determined by analyzing reactive oxygen species(ROS) and malondialdehyde (MDA) levels. ELISA, qRT-PCR and Western blot were used to determine the levels of TNF-alpha, IL-6, ICAM-1 and VCAM-1. CLIC1 cellular localization was examined by immunofluorescence. Chloride ion concentration was detected with chloride ion quenchers (MQAE). Results: STS treatment decreased atherosclerotic lesion area by 3.5 times (P = 0.001) in vivo. Meanwhile, STS reduced MDA production (13.6%, P = 0.008), increased SOD activity (113.6%, P = 0.008), decreased TNF-a (38.6%, P = 0.008) and IL-6 (43.0%, P = 0.03) levels, and downregulated the expression of CLIC1, ICAM-1, and VCAM-1 in the atherosclerotic mice. The dose-dependent anti-oxidative and anti-inflammatory effects of STS were further confirmed in vitro. Furthermore, CLIC1 depletion abolished the STS-mediated decrease of ROS and MDA production in HUVEC cells. Additionally, STS inhibited both CLIC1 membrane translocation and chloride ion concentration. Conclusion: The anti-oxidant, and anti-inflammation properties of STS in preventing AS is mediated by its inhibition of CLIC1 expression and membrane translocation.