Empagliflozin attenuates cardiac microvascular ischemia/reperfusion through activating the AMPK1/ULK1/FUNDC1/mitophagy pathway

Mitophagy preserves microvascular structure and function during myocardial ischemia/reperfusion (I/R) injury. Empagliflozin, an anti-diabetes drug, may also protect mitochondria. We explored whether empagliflozin could reduce cardiac microvascular I/R injury by enhancing mitophagy. In mice, I/R injury induced luminal stenosis, microvessel wall damage, erythrocyte accumulation and perfusion defects in the myocardial microcirculation. Additionally, I/R triggered endothelial hyperpermeability and myocardial neutrophil infiltration, which upregulated adhesive factors and endothelin-1 but downregulated vascular endothelial cadherin and endothelial nitric oxide synthase in heart tissue. In vitro, I/R impaired the endothelial barrier function and integrity of cardiac microvascular endothelial cells (CMECs), while empagliflozin preserved CMEC homeostasis and thus maintained cardiac microvascular structure and function. I/R activated mitochondrial fission, oxidative stress and apoptotic signaling in CMECs, whereas empagliflozin normalized mitochondrial fission and fusion, neutralized supra physiologic reactive oxygen species concentrations and suppressed mitochondrial apoptosis. Empagliflozin exerted these protective effects by activating FUNDC1-dependent mitophagy through the AMPK alpha 1/ULK1 pathway. Both in vitro and in vivo, genetic ablation of AMPK alpha 1 or FUNDC1 abolished the beneficial effects of empagliflozin on the myocardial microvasculature and CMECs. Taken together, the preservation of mitochondrial function through an activation of the AMPK alpha 1/ULK1/FUNDC1/mitophagy pathway is the working mechanism of empagliflozin in attenuating cardiac microvascular I/R injury.