Blockade of IL-33 ameliorates Con A-induced hepatic injury by reducing NKT cell activation and IFN-γ production in mice.

IL-33, a recently described member of the IL-1 family, has been identified as a cytokine endowed with pro-Th2 type functions. To date, there are only limited data on its role in physiological and pathological hepatic immune responses. In this study, we examined the role of IL-33 in immune-mediated liver injury by exploring the model of concanavalin A (Con A)-induced hepatitis. We observed that the level of IL-33 expression in the liver was dramatically increased at 12 h after Con A injection. Meanwhile, ST2L, the receptor of IL-33, was significantly up-regulated in lymphocytes including T and natural killer T (NKT) cells, especially in NKT cells. Moreover, administration of recombinant IL-33 exacerbated Con A-induced hepatitis, while pretreatment of IL-33-blocking antibody or psST2-Fc plasmids showed a protective effect probably by inhibiting the activation of late stage of T cells and NKT cells and also decreasing the production of the cytokine IFN-γ. Furthermore, depletion of NKT cells abolished the protective effect of IL-33-blocking antibody, and IL-33 failed to exacerbate Con A-induced hepatitis in IFN-γ(-/-) mice. These data suggested the critical roles of NKT cells and IFN-γ in the involvement of IL-33 in Con A-induced hepatitis. Blockade of IL-33 may represent a novel therapeutic strategy through IL-33/ST2L signal to prevent immune-mediated liver injury.