Apelin-13 Protects Against Myocardial Hypoxia/Reoxygenation (H/R) Injury by Inhibiting Ferroptosis Via Nrf2 Activation.

Ischemia-reperfusion (IR)-induced myocardial damage represents a major pathological event in coronary artery disease (CAD). Effective therapeutic strategies are urgently needed to improve clinical outcomes for CAD patients. Apelin-13, primarily produced by magnocellular neurons, exhibits diverse biological functions across various cell types and tissues. However, its role in myocardial IR injury remains unexplored. In this study, we utilized an in vitro model of myocardial IR injury using H9c2 cardiomyocytes to investigate the potential protective effects of Apelin-13. Our findings reveal that Apelin-13 protects against hypoxia/reoxygenation (H/R)-induced oxidative stress in H9c2 cells by reducing mitochondrial reactive oxygen species (ROS) and malondialdehyde (MDA) levels, while enhancing superoxide dismutase (SOD) activity. Additionally, Apelin-13 alleviates H/R-induced mitochondrial dysfunction, as evidenced by increased mitochondrial membrane potential (MMP) and adenosine triphosphate (ATP) production. Crucially, Apelin-13 mitigates H/R-induced cardiomyocyte injury, as shown by reduced levels of creatine kinase-myocardial band (CK-MB), cardiac troponin I (cTnI), and lactate dehydrogenase (LDH). Remarkably, Apelin-13 also counteracts ferroptosis during H/R by decreasing ferrous iron (Fe²⁺) concentrations, increasing glutathione (GSH) levels, and suppressing glutathione peroxidase 4 (GPX4) and ferritin heavy chain 1 (FTH1) expression. These protective actions were negated by the ferroptosis inducer Erastin. Further investigation revealed that Apelin-13 activates the transcription factor nuclear factor erythroid 2-related factor 2 (Nrf2) through enhanced nuclear translocation and upregulation of heme oxygenase-1 (HO-1). Conversely, Nrf2 knockdown nullified the protective effects of Apelin-13 against ferroptosis and cardiomyocyte injury, underscoring the critical involvement of Nrf2 in mediating these benefits. Collectively, our results highlight the promising therapeutic potential of Apelin-13 in managing CAD.