Qingre Sanjie Formula alleviates atherosclerosis by promoting LXR-α/ABCG5/G8-mediated reverse cholesterol transport and bile acid synthesis

Background: Atherosclerosis is the leading cause of cardiovascular disease-related morbidity and mortality. The traditional Chinese medicine Qingre Sanjie Formula (QRSJF), composed of Prunellae Spica, Sargassum, Fritillariae Thunbergii Bulbus, Leonuri Herba, and Forsythiae Fructus, has shown efficacy in treating cardiovascular diseases, although its mechanisms are unclear. Purpose: This study aimed to explore the protective effects of QRSJF against atherosclerosis and the mechanisms involved. Methods: The composition of QRSJF was analyzed using Ultra Performance Liquid Chromatography Quadrupole Time-of-Flight Mass Spectrometry. An 8-week high-fat diet (HFD)-induced atherosclerosis model was established in ApoE-/- mice. Following model induction, mice received 12 weeks of QRSJF treatment at high- and low doses (3.16 and 1.58 g drug/kg/day, respectively) via oral gavage, while simvastatin (2.6 mg/kg/day) as the positive control. Various techniques, including biochemical assays, vascular ultrasonography, histopathology, untargeted metabolomics, and molecular biology techniques were utilized to evaluate therapeutic effects. The underlying mechanism was investigated in vitro using free fatty acids -induced HepG2 cells. Results: Both low- and high-dose QRSJF effectively attenuated dyslipidemia and decreased serum inflammatory cytokine levels in HFD-fed ApoE-/- mice. In addition, QRSJF alleviated atherosclerotic plaque formation, reduced arterial narrowing, and enhanced plaque stability. Plasma and liver metabolomic analyses further identified that ABC (ATP binding cassette) subfamily transporters and bile acid metabolism as key pathways through which QRSJF ameliorates atherosclerosis. QRSJF also alleviated liver lipid accumulation and increased the expression of liver proteins, including scavenger receptor class B type 1, low-density lipoprotein receptor, ABC subfamily A member 1, cholesterol 7α-hydroxylase (CYP7A1), ABC transporter G5/G8 (ABCG5/G8), bile salt output pump, and liver X receptor alpha (LXR-α). In vitro, QRSJF activated LXR-α expression in HepG2 cells, thereby enhancing the expression of the downstream targets, CYP7A1 and ABCG5/8, and reducing free fatty acid-induced lipid accumulation. Notably, the beneficial effects of QRSJF were abrogated by the LXR-α inhibitor GSK2033. Conclusion: QRSJF improves dyslipidemia and reduces atherosclerotic plaque in ApoE-/- mice by activating the LXR-α/ABCG5/G8 pathway. This facilitates cholesterol transport to the liver and promotes bile acid synthesis and cholesterol excretion into the bile and intestine, thereby exerting anti-atherosclerotic effects.