Salvianolic acid B increases the stability of atherosclerotic vulnerable plaques by inhibiting macrophage apoptosis via the Piezo1/JNK pathway

BACKGROUND: Atherosclerosis is the leading cause of cardiovascular morbidity and mortality, and plaque vulnerability is a critical determinant of acute cardiovascular events. Previous studies have reported that Salvianolic acid B (Sal-B), a main active constituent of Salvia miltiorrhiza, inhibits AS by targeting Piezo1 and have clarified its anti-inflammatory and antioxidant effects in endothelial cells. However, the specific signaling pathway downstream of Piezo1 that regulates apoptosis in macrophages remains unclear, and the molecular mechanism by which Sal-B affects macrophage apoptosis through directly regulating Piezo1 still needs to be further explored. OBJECTIVE: This study aimed to investigate the protective effects of Sal-B on atherosclerosis and to elucidate the underlying molecular mechanisms, with particular emphasis on macrophage apoptosis and the Piezo1-JNK signaling pathway. METHODS: mice fed a high-fat diet, followed by oral administration of Sal-B at different doses. Plaque morphology, fibrous cap thickness, and lipid profiles were assessed using Oil Red O, hematoxylin and eosin (H&E), and Masson's staining. Macrophage apoptosis and related protein expression were evaluated by TUNEL staining, flow cytometry, Western blotting, and immunohistochemistry in both in vivo and in vitro experiments. RESULTS: Sal-B significantly reduced plaque area, increased fibrous cap thickness, and improved serum lipid profiles. It markedly downregulated the expression of pro-apoptotic Bax and cleaved caspase-3 while upregulating the anti-apoptotic protein Bcl-2, thereby inhibiting macrophage apoptosis. Consistently, Sal-B suppressed the expression of Piezo1, JNK, and phosphorylated JNK (p-JNK) in vivo and in vitro. Overexpression of Piezo1 enhanced JNK/p-JNK activation, increased Bax and cleaved caspase-3 levels, decreased Bcl-2 expression, and aggravated macrophage apoptosis, indicating that excessive Piezo1 activity may counteract the anti-apoptotic effects of Sal-B. CONCLUSION: Sal-B stabilizes atherosclerotic plaques by suppressing Piezo1 activation and downstream JNK/p-JNK signaling, thereby reducing macrophage apoptosis, limiting necrotic core expansion, and ultimately attenuating the progression of atherosclerosis. This finding offers novel mechanistic insights into the anti-atherosclerotic effects of Sal-B and identifies the macrophage apoptosis-related Piezo1 channel as a potential therapeutic target for atherosclerotic lesions.