Abstract
OBJECTIVE: This study aimed to investigate whether interleukin-28A (IL-28A) plays a role in murine myocarditis induced by coxsackievirus B3 (CVB3), and to explore its possible mechanism involved. METHODS: Male BALB/c mice both infected and not infected by CVB3 were randomly divided into four groups (n=40), untreated or treated with different doses of IL-28A for 4 days, and then sacrificed on days 4 and 7 post-infection. The heart samples were collected for histopathologic examination. Cardiac viral load was determined by a plaque assay. Additionally, immunoblot analysis, TUNEL assay, and immunohistochemistry were performed to examine the expression of signal transducer, activator of transcription 1 and 2 (STAT1 and STAT2), CVB3-induced apoptosis and the expression of Bcl-2, BAX and Caspase-3. RESULTS: Compared to uninfected mice, the CVB3 infected mice exhibited higher mortality rate (p<0.001), apparent inflammation and myocardial lesion (p<0.01), and higher cardiac viral load (p<0.01). After CVB3 infection, IL-28A treated mice presented no death (p<0.001), reduced inflammation and myocardial lesion (p<0.01), and lower viral load (p<0.01) compared to untreated mice. Besides, treatment with IL-28A markedly increased the expressions of STAT1 and STAT2, and inhibited CVB3-induced apoptosis in myocardial cells with increased ratio of Bcl-2/BAX. CONCLUSION: The antiviral and myocyte protective effects of IL-28A in CVB3-induced myocarditis are regulated by STAT1 and STAT2.