Tilianin Protects against Ischemia/Reperfusion‐Induced Myocardial Injury through the Inhibition of the Ca²⁺/Calmodulin‐Dependent Protein Kinase II‐Dependent Apoptotic and Inflammatory Signaling Pathways

Abstract

Tilianin is a naturally occurring phenolic compound with a cardioprotective effect against myocardial ischemia/reperfusion injury (MIRI). The aim of our study was to determine the potential targets and mechanism of action of tilianin against cardiac injury induced by MIRI. An <i>in silico</i> docking model was used in this study for binding mode analysis between tilianin and Ca²⁺/calmodulin-dependent protein kinase II (CaMKII). Oxygen-glucose deprivation/reperfusion- (OGD/R-) injured H9c2 cardiomyocytes and ischemia/reperfusion- (I/R-) injured isolated rat hearts were developed as <i>in vitro</i> and <i>ex vivo</i> models, respectively, which were both treated with tilianin in the absence or presence of a specific CaMKII inhibitor KN93 for target verification and mechanistic exploration. Results demonstrated the ability of tilianin to facilitater the recovery of OGD/R-induced cardiomyocyte injury and the maintenance of cardiac function in I/R-injured hearts. Tilianin interacted with CaMKII<i>δ</i> with an efficient binding performance, a favorable binding score, and restraining p-CaMKII and ox-CaMKII expression in cardiomyocytes injured by MIRI. Importantly, inhibition of CaMKII abolished tilianin-mediated recovery of OGD/R-induced cardiomyocyte injury and maintenance of cardiac function in I/R-injured hearts, accompanied by the disability to protect mitochondrial function. Furthermore, the protective effects of tilianin towards mitochondrion-associated proapoptotic and antiapoptotic protein counterbalance and c-Jun N-terminal kinase (JNK)/nuclear factor- (NF-) <i>κ</i>B-related inflammation suppression were both abolished after pharmacological inhibition of CaMKII. Our investigation indicated that the inhibition of CaMKII-mediated mitochondrial apoptosis and JNK/NF-<i>κ</i>B inflammation might be considered as a pivotal mechanism used by tilianin to exert its protective effects on MIRI cardiac damage.