Effects of the MAPK pathway and the expression of CAR in a murine model of viral myocarditis

The pathogenesis of viral myocarditis (VMC) is not fully understood. This study aimed to examine the relationship between coxsackie-adenovirus receptor (CAR) and the p38 mitogen activated protein kinase (MAPK) pathway mechanisms in a mouse model. Three groups of mice were established: 5 mice in a control group injected with saline, 15 in the model group injected with coxsackie virus B3 (CVB) and 15 in the intervention group injected with CVB3 but treated with the p38 MAPK inhibitor SB203580. Mice were sacrificed at days 1, 5, 10, 15 and 30 and cardiac tissues were isolated to perform the tests. Quantitative PCR and western blot analysis showed CAR mRNA and protein expression levels were highest in the model group at all time-points (P<0.05). The expression levels of p38 MAPK protein by western blot analysis at days 1, 5 and 10 were obviously higher in the model group (P>0.05). H&E staining used to observe myocardial pathological changes showed the inflammatory infiltration was also higher in the model group at all the time-points (P<0.05). Our results show a direct relationship between CAR and p38 MAPK levels, and since the p38 MAPK inhibitor treatment resulted in reduced levels of CAR as well as lower inflammatory infiltration, it is possible that the signaling pathway may mediate CAR expression during the pathogenesis of VMC.