Chun-Hui He

Purpose To investigate the protective effect and mechanism of enhanced expression of endogenous macrophage migration inhibitory factor (MIF) on cardiac ischemia–reperfusion (I/R) injury. Methods A recombinant double-stranded adeno-associated virus serotype 9 with MIF or green fluorescent protein (GFP) genes (dsAAV9-MIF/GFP) was transduced into mice and neonatal rat ventricular myocytes (NRVMs). The models of cardiac 60 min ischemia and 24 h reperfusion and 12 h hypoxia/12 h reoxygenation (H/R) were established in mice and NRVMs, respectively. Infarct size, cardiac remodeling, and related signaling pathways were assessed. Results The dsAAV9 vector demonstrated strong transduction efficacy and cardiac affinity. Cardiac overexpression of MIF led to a 35.3% reduction in infarct size and improved cardiac function following I/R injury. In the dsAAV9-MIF group, the AMP-activated protein kinase (AMPK) signaling pathway was activated, and autophagy was enhanced during the ischemic period. During reperfusion, the extracellular signal-regulated kinases 1 and 2 (ERK1/2) signaling pathway was upregulated, leading to reduced cardiac apoptosis. In vitro, transfection with MIF in NRVMs also upregulated AMPK and ERK1/2 signaling during hypoxia and reoxygenation, respectively. Furthermore, MIF overexpression significantly improved autophagy and mitochondrial function, evidenced by an increased LC3-II/I ratio and enhanced mitochondrial membrane potential (ΔΨm), with these effects reversed by the AMPK inhibitor compound C. Additionally, MIF overexpression led to a 60% reduction in the apoptosis rate of cardiomyocytes subjected to H/R and decreased the Bax/Bcl-2 ratio, partially through the ERK1/2 signaling pathway. Conclusion Enhanced endogenous MIF expression via the dsAAV9 vector provides significant cardioprotection against I/R injury by activating the AMPK and ERK1/2 signaling pathways. Our findings suggest that targeting MIF may represent a viable therapeutic strategy for severe and prolonged I/R injury.