Dexmedetomidine exerts cardioprotective effect through miR-146a-3p targeting IRAK1 and TRAF6 via inhibition of the NF-κB pathway

Background: Myocardial ischemia/reperfusion (I/R) injury is a common cause of mortality. Cardiac miR-146a is emerging as a potent regulator of myocardial function. Dexmedetomidine preconditioning provides cardioprotective effects, of which mechanisms related to miR-146a-3p are unclear. Methods: A myocardial I/R model in rats and a cellular anoxia/reoxygenation (A/R) model in H9C2 cells were established and preconditioned with dexmedetomidine or not. H9C2 cells were transfected with mimics, inhibitor, or negative controls of miR-146a-3p, and siRNAs of IRAK1 or TRAF6. Relative expressions of miR-146a3p were determined by quantitative real-time polymerase chain reaction. The apoptosis rates and reactive oxygen species (ROS) levels in H9C2 cells were examined by flow cytometry. Protein expressions of IRAK1, TRAF6, cleaved Caspase-3, BAX, BCL-2, NF-kappa B p65, phosphorylated NF-kappa B p65 (p-NF-kappa B p65), I kappa B alpha, and phosphorylated I kappa B alpha (p-I kappa B alpha) in H9C2 cells were detected by Western blot. Results: Dexmedetomidine decreased myocardial infarction size and apoptosis rates of H9C2 cells. Dexmedetomidine upregulated expression of miR-146a-3p. Dexmedetomidine significantly decreased protein expressions of IRAK1, TRAF6, cleaved Caspase-3, BAX, and NF-kappa B p65, but increased expressions of BCL-2 in H9C2 cells. miR-146a-3p overexpression strengthened the anti-apoptotic effect induced by dexmedetomidine in H9C2 cells via decreasing protein levels of IRAK1, TRAF6, cleaved Caspase-3, BAX, NF-kappa B p65, p-NF-kappa B p65, and p-I kappa B alpha and increasing protein level of BCL-2. Downregulation of miR-146a-3p reversed the changes in these proteins in H9C2 cells. Expressions of NF-kappa B p65 and p-NF-kappa B p65 were further decreased following knockdown of IRAK1 or TRAF6. ROS emission was significantly increased after A/R, while significantly decreased following dexmedetomidine preconditioning in H9C2 cells transfected with siIRAK1 or siTRAF6. Conclusion: miR-146a-3p targeting IRAK1 and TRAF6 through inhibition of NF-kappa B signaling pathway and ROS emission is involved in cardioprotection induced by dexmedetomidine pretreatment.