EV-Mediated Intracardiac Crosstalk Mitigates Doxorubicin-Induced Cardiotoxicity

BACKGROUND: Extracellular vesicles (EVs) are involved in exercise-induced cardiac protection. However, the effects and underlying mechanisms of tissue-specific molecular cargo packaged within these EVs, including PIWI (P-element induced wimpy testis)-interacting RNA (piRNA), remain poorly understood. In particular, the mechanistic contribution of exercised intracardiac EV-associated piRNAs to doxorubicin-induced cardiotoxicity (DCT) has not been defined. METHODS: Transgenic reporter mice and a cardiomyocyte-specific Rab27a (RAB27A, member RAS oncogene family) knockout strategy were used to investigate the contribution of cardiomyocyte-derived EVs to exercise-induced cardioprotection against DCT. To screen functionally relevant cardioprotective piRNA cargo, heart tissues from patients with dilated cardiomyopathy and experimental DCT models were analyzed, including cardiomyocyte-specific knockout mice, human embryonic stem cell-derived cardiomyocytes, and primary murine cardiomyocytes. RESULTS: We found that cardiomyocyte-derived EVs post-exercise were enriched for a cardiac-specific protective piRNA (piR-mmu-57256903), designated as an exercise-induced protective piRNA (EPPIR). EPPIR levels were significantly reduced in heart tissue from patients with dilated cardiomyopathy and DCT models. Functionally, EPPIR protects the heart against DCT by regulating KDM6B (lysine [K]-specific demethylase 6B)-H3K27me3 (trimethylated histone H3 at lysine 27)-Dtna epigenetic axis. In addition, EPPIR acts as a cardiomyocyte-specific suppressor of Tp53 (tumor protein p53). CONCLUSIONS: We identify a previously unrecognized role for cardiomyocyte-derived EV-associated piRNA EPPIR in mediating exercise-induced cardioprotection. EPPIR exerts its protective effects through coordinated regulation of the KDM6B-Dtna axis and cardiomyocyte-specific suppressor of Tp53, providing mechanistic insight and highlighting a potential therapeutic strategy for DCT.