RESUMO
AIM: To establish an animal model of experimental autoimmune myocarditis (EAM) in BALB/c mice and to investigate the expression and significance of Toll-like receptor 3 in mouse EAM. METHODS: BALB/c mice were immunized with cardiac myosin extracted from porcine ventricular myocardium covered by complete freund's adjuvant (CFA) on 0 d and 7 d, then divided into immunized with CFA only. Serum and myocardium samples were collected at 14 d and 21 d after the first immunization. HE staining was used to identify the areas of inflammation. The myosin IgG antibody was examined by indirect ELISA assay. The changes of TLR3 protein and mRNA expression in myocardial tissue were measured by immunohistochemistry and real time-PCR. RESULTS: Compared to control group, immunohistochemistry results showed that there was positive expression of TLR3 in the myocardium of mice with EAM and the mRNA of TLR3 were more than 20 times (P<0.05). The expression of interferon beta mRNA in EAM group was more than 14 times as many as basal expression, that of tumor necrosis factor alpha was more than 18 times (P<0.05). CONCLUSION: The expression of Toll-like receptor 3 in myocardium is up-regulated in experimental autoimmune myocarditis. The inflammatory response to cardiac myosin may associate with the TLR3 signal transduction pathway.