MicroRNA-21 and -146b are involved in the pathogenesis of murine viral myocarditis by regulating TH-17 differentiation.

Viral myocarditis (VMC) is a common cardiovascular disease, and microRNAs (miRNAs) have been postulated to be involved in its pathology. Using microarrays, we observed that miRNA-21 and -146b were upregulated in a murine model of VMC. We also found that miRNA-451 was downregulated. In vivo silencing of miRNA-21 and -146b resulted in less-severe VMC. Overexpression of miRNA-451 did not ameliorate the severity of VMC. Further work revealed that inhibition of miRNA-21 and -146b decreased the expression levels of Th17 and RORγt . Overexpression of miRNA-451 had no effect on IL-17 and RORγt expression. Inhibition of miRNA-21 and -146b might ameliorate myocardium inflammation by mediating downregulation of RORγt expression, indicating that these miRNAs are involved in the pathogenesis of murine VMC.