Protective effects of losartan in mice with chronic viral myocarditis induced by coxsackievirus B3.

Abstract Aim To investigate whether losartan has protective effects in mice with chronic viral myocarditis induced by coxsackievirus B3 (CVB3). Main methods Thirty two male Balb/c mice were intraperitoneally injected with CVB3 (10 × TCID 50 ) to induce chronic viral myocarditis (CVM). Losartan at 12.5 mg/kg (n = 16) or normal saline (n = 16) were orally administered daily for 28 days to these mice. Uninfected mice (n = 6) were used as controls. On day 29, all mice underwent anesthesia and echocardiography prior to sacrifice. Serum IL-17, IL-4, IFN-γ and TNF-α levels were measured by enzyme-linked immunosorbent assay, and cardiac tissues were histologically examined after hematoxylin & eosin staining. In addition, the effect of losartan on the virus titers in primary cultured neonatal rat cardiomyocytes infected with CVB3 was measured on Hep-2 cells at 72 h post infection. Key findings Mice infected with CBV3 had significantly increased mortality, heart/body weight ratios, necrosis and inflammatory scores and decreased cardiac ejection fractions, compared with the controls (all P  Significance Losartan protects mice against CVB3-induced CVM, most likely through upregulating Th2 responses, and down-regulating Th1 and Th17 responses.