Calycosin-7-Glucoside Alleviates Atherosclerosis by Inhibiting Ox-LDL-Induced Foam Cell Formation and Inflammatory Response in THP-1-Derived Macrophages via ATF-1 Activation Through the p38/MAPK Pathway.

PURPOSE: Macrophages play a pivotal role in the progression of atherosclerosis (AS), and targeting macrophage-associated pathological processes has emerged as a promising therapeutic strategy for AS. Flavonoids have demonstrated potent antioxidant properties with potential anti-atherosclerotic effects. This study aimed to investigate the therapeutic effects of the flavonoid calycosin-7-glucoside (CG) on AS and elucidate its underlying molecular mechanisms. METHODS: Macrophages were differentiated from human monocytic THP-1 cells by treatment with phorbol-12-myristate-13-acetate (PMA). Foam cell formation was induced by exposing differentiated macrophages to oxidized low-density lipoprotein (ox-LDL). Protein and inflammatory cytokine expression levels were assessed using RT-qPCR, Western blot, and ELISA assays. Total cholesterol and free cholesterol levels were quantified using commercial kits, and lipid droplet accumulation was visualized using Nile red staining. RESULTS: Activation of activating transcription factor 1 (ATF-1) was found to mediate CG-induced suppression of inflammatory responses and foam cell formation in ox-LDL-exposed THP-1-derived macrophages. CG treatment enhanced p38 MAPK activity, which was responsible for ATF-1 activation and subsequent inhibition of inflammation and foam cell formation. Mechanistically, ATF-1 facilitated CG-induced anti-atherosclerotic effects by upregulating liver X receptor beta (LXR-β) and cystic fibrosis transmembrane conductance regulator (CFTR), which are critical for lipid metabolism and inflammation regulation, respectively. CONCLUSION: CG attenuates ox-LDL-induced foam cell formation and inflammatory responses in THP-1-derived macrophages by activating the p38 MAPK/ATF-1 signaling pathway, leading to the upregulation of LXR-β and CFTR. These findings highlight the potential of CG as a therapeutic agent for AS.