Xinmaikang (XMK) tablets alleviate atherosclerosis by regulating the SREBP2-mediated NLRP3/ASC/Caspase-1 signaling pathway

Xinmaikang (XMK) tablets, a Chinese patent medicine, have been used for the prevention and treatment of atherosclerosis (AS) clinically. However, the underlying mechanism of XMK is far from completely illustrated. This study aimed to determine whether XMK alleviates AS in Apolipoprotein E-knockout (ApoE−/−) mice and to explore the potential mechanism of action in bone marrow-derived macrophages (BMDMs). XMK decoction was analyzed by an LC‒MS/MS assay. Molecular docking was conducted to determine the interaction of XMK molecular ligands and AS targets. In vivo, 10 ApoE−/− mice were selected as the control group. Fifty ApoE−/− mice were randomly divided into 5 groups: the model group, low-, medium-, and high-dose XMK groups and the simvastatin group. Mice in the control group were fed a chow diet, and the other 5 groups were fed a high-fat diet (HFD) for 12 weeks. After 12 weeks, the treatment groups were administered low-dose XMK (2.28·kg-1·d), medium-dose XMK (4.55·kg-1·d), high-dose XMK (9.1 kg−1 d) and simvastatin (91 mg−1 d) for another 12 weeks. Serum enzymology assays tested AST/ALT, Cr, LDH and CK-MB levels. The atherosclerotic plaques and lipid deposition were measured by Oil red O (ORO) staining and Hematoxylin and Eosin (H&E) staining. Then, we examined the body weight and serum lipids (TC, TG, LDL-C and HDL-C) of the mice. ELISA was performed to determine the levels of inflammatory factors (IL-6, TNF-ɑ, VCAM-1, CXCL8 and CCL2). SREBP2/NLRP3 signaling pathway-related genes (SREBP2, NLRP3, ASC, IL-1β and Caspase-1) were analyzed by RT‒qPCR and western blotting. In vitro, LPS-stimulated BMDMs were treated with different concentrations of XMK (1, 2.5, 5, 10, 20, and 40 μg/ml). Immunofluorescence staining (SREBP2, NLRP3), adenovirus infection and siRNA knockdown (SREBP2, NLRP3, Caspase-1 and ASC) were conducted as complements to the in vivo experiment. Molecular docking showed a stable interaction between the effective components of XMK and SREBP2 and NLRP3. Serum enzymology assays revealed the medication safety of XMK in cardiac, hepatic and renal function. Studies in vivo indicated that XMK improved serum lipids (TC, TG, LDL-C and HDL-C) and reduced plaque area. Body weight decreased, and the expression of inflammatory cytokines (IL-6, TNF-ɑ and VCAM-1) was inhibited. Then, XMK downregulated the mRNA and protein expression of SREBP2, NLRP3, ASC, IL-1β and Caspase-1. In vitro, the above findings were reinforced in BMDMs, and knocking down SREBP2 restrained the effect of XMK on the NLRP3/ASC/Caspase-1 signaling pathway. XMK restrains AS by improving inflammation through the SREBP2-mediated NLRP3/ASC/Caspase-1 signaling pathway.