Detection of Transforming Growth Factor-β1 in Coxsackie B3 Virus-Induced Murine Myocarditis

Abstract

To clarify the role of TGF-β1 in myocardial healing process after virus-induced myocarditis, we have examined the time course of TGF-β1 expression and its localization in myocardial healing process after Coxsackie B3-induced murine myocarditis. TGF-β1 immunoreactivity increased in parallel with its mRNA level and reached a peak at 10 days after Coxsackie B3 virus inoculation. Immunohistochemically, TGF-β1 was localized at pre-necrotic area at an early phase (5 days); it increased and extended to the area around the necrotic foci when necrosis became manifest (10 days); it decreased when macrophages and fibroblasts migrated to the necrotic foci (15 days); and then it reached a normal level and localized a little in perivascular and calcified regions (30 days). To our knowledge, this is the first study which demonstrates that TGF-β1 mRNA increases in viral-induced myocarditis at acute inflammatory phase. This result suggests that TGF-β1 promotes the migration of macrophages and fibroblasts to necrotic foci and induces fibrosis.