Yiqihuoxue formula improves atherosclerosis by regulating macrophage polarization associated with enhanced STAT6/PPARγ pathway

Background Atherosclerosis (AS) is a major contributor to deaths from cardiovascular diseases. Yiqihuoxue Formula (YQHXF) reflects the traditional Chinese medicine principle of “Qi-invigorating and blood-activating.” This study investigates the anti-atherosclerotic effects and mechanism of YQHXF through the signal transducer and activator of transcription 6 (STAT6)/ peroxisome proliferator-activated receptor gamma (PPARγ) signaling pathway and macrophage polarization. Methods Ultra-high performance liquid chromatography-high resolution mass spectrometry (UHPLC-HRMS) was used to detect the components of YQHXF-containing serum (YQHXF-CS). Using oxidized low-density lipoprotein (ox-LDL), RAW264.7 macrophages were induced into foam cells in vitro and treated with YQHXF-CS. PPARγ knockdown was achieved using siRNA. Cell viability, lipid accumulation, macrophage polarization markers, and STAT6/PPARγ signaling were analyzed. In vivo , ApoE −/− mice fed a high-fat diet (HFD) received low, medium, or high-dose YQHXF or atorvastatin. Serum lipids, aortic plaque area, histopathology, macrophage polarization, and pathway proteins were assessed. Results The results showed that YQHXF-CS contained 2,317 components. In vitro , 5% YQHXF-CS enhanced cell viability, reduced lipid droplets, downregulated M1 markers (nitric oxide synthase 2 ( Nos2) , tumor necrosis factor (Tnf) , interleukin 1 beta (Il1b) ), upregulated M2 markers ( interleukin 4 (Il4) , arginase 1 (Arg1) , transforming growth factor- β (Tgfb) , CD163, CD206), and this was accompanied by enhanced STAT6/PPARγ pathway. Moreover, YQHXF-CS partially counterbalanced siRNA-PPARγ-induced foam cells formation, and this effect was associated with M2 macrophages polarization. In vivo , YQHXF reduced body weight and serum lipid accumulation, diminished aortic plaque area and pathological damage, increased M2 macrophages (CD206 + , IL-4, IL-10), and decreased M1 macrophages (CD86 + , TNF-α, IL-1β). Mechanistically, YQHXF partially restored aortic p-STAT6 and PPAR γ expression. Conclusions YQHXF ameliorates AS, as evidenced by reduced foam cell formation, alleviated vascular lesions, and promotion of anti-inflammatory M2 macrophage polarization; these effects were associated with enhanced STAT6/PPARγ signaling. This validates the theory of “Qi-invigorating and blood-activating” and highlights YQHXF's therapeutic potential.