NAMPT activation protects against myocardial ischemia/reperfusion injury via FSP1-CoQ10 ferroptosis defense.

BACKGROUND: Myocardial ischemia/reperfusion injury (MIRI) is characterized by metabolic disturbance, oxidative stress, mitochondrial dysfunction and regulated cardiomyocyte death. Nicotinamide phosphoribosyltransferase (NAMPT), the rate-limiting enzyme of the NAD+ salvage pathway, plays an important role in redox metabolism. However, whether NAMPT-dependent redox remodeling protects against MIRI by regulating ferroptosis remains unclear. METHODS: Rat myocardial ischemia/reperfusion and H9C2 hypoxia/reoxygenation models were established to evaluate the effects of NAMPT activation on myocardial injury, redox homeostasis, ferroptosis and mitochondrial integrity. NAMPT activity was modulated by P7C3 and FK866. Cardiac deficiency of ferroptosis suppressor protein 1 (FSP1), FSP1 knockdown, FSP1 overexpression and coenzyme Q10 (CoQ10) supplementation were used to investigate the downstream mechanism. RESULTS: NAMPT activation improved cardiac function, reduced myocardial infarct size and attenuated myocardial injury after ischemia/reperfusion. In both in vivo and in vitro models, NAMPT activation restored NAD+/NADH and NADP+/NADPH balance, reduced reactive oxygen species accumulation, lipid peroxidation and iron overload, and preserved mitochondrial membrane potential and ultrastructural integrity. FSP1 deficiency or knockdown weakened the anti-ferroptotic and mitochondrial protective effects of NAMPT activation, whereas FSP1 overexpression or CoQ10 supplementation partially rescued ferroptotic and mitochondrial injury under NAMPT suppression. CONCLUSION: NAMPT activation attenuates MIRI by restoring redox homeostasis and sustaining FSP1/CoQ10-mediated ferroptosis defense, likely through NAD(P)H-dependent metabolic coupling. These findings identify the NAMPT-FSP1/CoQ10 axis as a potential metabolic target for myocardial protection against reperfusion injury.