Propolis alleviates concanavalin A-induced hepatitis by modulating cytokine secretion and inhibition of reactive oxygen species.

Viral hepatitis-induced oxidative stress accompanied by increased levels of transforming growth factor-β (TGF-β) and hepatic fibrosis are hallmarks of hepatitis C virus infection. The present study was designed to investigate the potential protective effect of propolis against liver injury induced by concanavalin A (Con A), a T-cell-dependent model that causes an immune-mediated hepatitis in a similar pattern to the one induced by viral infections. In the present study, rats were randomly divided into four groups. The first group (control) was administered the vehicle of Con A (i.v.) for 24 h. The second group received Con A (12 mg/kg body weight i.v.) for 24 h. The third group received propolis (300 mg/kg by oral gavage) 5 days before and concurrently with Con A for 24 h. The last group received propolis alone. Following a single injection of Con A, histopathological changes as well as significant reduction in albumin level were observed. In addition, serum levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), and total bilirubin were significantly increased. These increases correlated with an increase in lipid peroxidation and downregulation of reduced glutathione (GSH) as well as superoxide dismutase (SOD) and catalase activities in liver tissue. Furthermore, these changes were associated with an increase in serum levels of the inflammatory cytokines tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) as well as the profibrotic cytokine TGF-β. Moreover, TGF- β activation was accompanied with an increase in Smad phosphorylation. Interestingly, concomitant administration of propolis along with Con A significantly attenuated all these negative effects and improved liver function indicating that propolis has the ability to protect rats from Con A-induced hepatitis.