Abstract

Background and aims: Ischemic heart disease (IHD) presents a significant global health challenge, with myocardial ischemia-reperfusion injury (MIRI) being a major pathophysiological contributor and lacking effective interventions. While aerobic exercise training (AET) enhances cardiovascular health, its protective mechanism in MIRI remains elusive. This study aims to elucidate the protective effect of AET in MIRI and its underlying mechanism.

Methods: A mouse model of AET and MIRI was established to evaluate basic indices, cardiac ultrasound, and myocardial injury markers. Dot Blot, qRT-PCR, and Western blot were employed to assess m⁶A RNA methylation levels and related protein expression in myocardial tissue. In vitro, primary cardiomyocyte culture was utilized to mimic MIRI, evaluating cell viability, mitochondrial membrane potential, etc. Finally, myocardial tissues of MIRI mice were immunoprecipitated for m⁶A RNA methylation and sequenced to analyze related signaling pathways.

Key results: AET significantly improved cardiac function and mitigated myocardial injury and fibrosis. Moreover, AET protected myocardium from MIRI by reducing m⁶A RNA methylation levels and modulating METTL3 expression. In vitro experiments demonstrated that the decrease in m⁶A RNA methylation levels and METTL3 expression conferred resistance to hypoxia/reoxygenation-induced injury. Furthermore, sequencing results indicated elevated myocardial tissue m⁶A RNA methylation levels during MIRI, activation of the Nrf2-related signaling pathway, and AET-mediated regulation of the Nrf2/HO-1 signaling pathway, thereby attenuating MIRI through modulation of METTL3-related m⁶A methylation.

Conclusion and significance: AET attenuates MIRI by reducing the level of METTL3-related m⁶A RNA methylation in cardiomyocytes and activating the Nrf2/HO-1 antioxidant signaling pathway. This finding provides a novel insight and strategy for the prevention and treatment of IHD, holding significant clinical implications.