Cardiac extracellular vesicles aggravate cardiomyocyte ferroptosis in myocardial ischemia-reperfusion injury via miR-155-5p-Nfe2l2 signaling

Ischemia-reperfusion (IR) injury represents a major cause of cell death post myocardial infarction. Ferroptosis is a newly discovered form of regulated cell death (RCD) dependent on iron and reactive oxygen species (ROS). We recently confirmed that cardiac IR triggers the increased release of extracellular vesicles (EVs) which aggravates cardiac dysfunction. Whether and how these EVs contribute to cardiac ferroptosis during myocardial IR injury remain elusive. Murine myocardial IR models were established by ligation of the left anterior descending coronary artery for 45 minutes and then reperfusion. Then EVs from the heart subjected to IR (IR-EVs) were isolated. Adoptive transfer of IR-EVs and EVs inhibition experiments confirmed that IR-EVs act as a vital factor that contributes to the cardiomyocyte ferroptosis during cardiac IR, with increased Ptgs2 expression and malondialdehyde (MDA) production, as well as decreased NADPH level. Moreover, miR-155-5p enriched in IR-EVs can be delivered into cardiomyocytes and promoted the ferroptosis of cardiomyocytes in the peroxidation injury. Nfe2l2 was further confirmed as the target gene of miR-155-5p by luciferase reporter assay. Consistently, molecules targeting Nfe2l2 modulated the H ₂ O ₂ or oxygen glucose deprivation/reoxygenation (OGD/R) induced ferroptosis, involving the downstream antioxidant response elements (AREs) of the Nfe2l2 pathway including Nqo1, HO1, Fth1, and Slc7a11. In conclusion, the present results provide a novel EV-based ferroptosis regulation mechanism in cardiac IR injury. Strategies targeting the IR-EVs-miR-155-5p-Nfe2l2 axis may be of therapeutic potential to prevent cardiac ferroptosis and dysfunction after myocardial IR.