Aerobic exercise stabilizes atherosclerotic plaques by suppressing miR-15a-5p-mediated repression of Semaphorin-3A in vascular smooth muscle cells

AIMS: Aerobic exercise reduces cardiovascular events in atherosclerosis, but the causal roles of microRNAs (miRNAs) in mediating exercise-induced vascular smooth muscle cell (VSMC) phenotypic switching and plaque stabilization remains unclear. This study investigated whether aerobic exercise stabilizes atherosclerotic plaques by reprogramming VSMC miRNA expression, focusing on the miR-15a-5p/Semaphorin-3A (Sema3A) axis. MATERIALS AND METHODS: mice were assigned to sedentary or 12-week moderate-intensity treadmill exercise. Aortic miRNA profiles were analyzed by small RNA sequencing and integrated with exercise-responsive circulating miRNAs. Plaque burden and vulnerability were evaluated by histology and immunohistochemistry. Molecular mechanisms were validated in vitro and in vivo using luciferase reporter assays, qPCR, Western blotting, and VSMC-specific AAV9-mediated miR-15a-5p overexpression. miR-15a-5p and Sema3A expression were examined in human carotid atherosclerotic plaques. KEY FINDINGS: Exercise reduced plaque vulnerability, increased collagen content, reduced lipid content, and attenuated macrophage infiltration. Integrative miRNA profiling revealed that miR-15a-5p was markedly upregulated in atherosclerotic aortas but significantly suppressed by exercise locally and in circulation. In human carotid plaques, miR-15a-5p levels positively correlated with the plaque vulnerability index. Mechanistically, miR-15a-5p directly targeted the 3'-UTR of Sema3A, repressing its expression. VSMC-specific miR-15a-5p overexpression in vivo downregulated contractile markers, accelerated phenotypic switching, and destabilized plaques, such traits resembled those in cells from sedentary mice. SIGNIFICANCE: Aerobic exercise stabilizes plaques by downregulating miR-15a-5p, relieving Sema3A repression and preserving the contractile VSMC phenotype. The miR-15a-5p/Sema3A signaling axis mediates exercise-induced atheroprotection. Notably, elevated miR-15a-5p levels in human carotid plaques correlate positively with plaque vulnerability, supporting its potential as an atherosclerotic therapeutic target.