IL-17 is a signature
cytokine of Th17 cells implicated in the induction and progression of chronic inflammatory diseases. Several studies in C57BL/6 mice, immunized with soluble schistosome egg Ags (SEA) in complete
Freund's adjuvant (CFA), and subsequently infected with Schistosoma mansoni (S. mansoni) have shown that severe hepatic granulomatous
inflammation is correlated with high levels of
IL-17. Here, using a Schistosoma japonicum (S. japonicum) larvae
infection model in C57BL/6 mice, we analyzed the dynamic expression of
IL-17 in infected livers by RT-qPCR and ELISA. Our results showed that
IL-17 expression was elevated during the course of
infection. The temporal expression of
IL-17 and
cytokines/
chemokines involved in the induction and effector function of Th17 cells was paralleled with hepatic granulomatous
inflammation. Treatment of S. japonicum infected mice with IL-17-neutralizing mAb resulted in significant downmodulation of granulomatous
inflammation and hepatocyte
necrosis. The protection was associated with lower expression of proinflammatory
cytokines/
chemokines, such as
IL-6, IL-1β, CXCL1, and CXCL2 and a reduced number of infiltrating neutrophils. Anti-IL-17 mAb significantly ameliorated hepatic granulomatous
inflammation, partly through the downregulation of proinflammatory
cytokines/
chemokines and recruitment of neutrophils. Our data indicate a pathogenic role of Th17/IL-17 in hepatic immunopathology in S. japonicum infected mice.