A key pathogenic role for the STAT1/T-bet signaling pathway in T-cell-mediated liver inflammation.

TH1 cytokines have been suggested to contribute to the pathogenesis of T-cell-mediated liver injury and inflammation. However, the molecular signaling pathways involved in such injury are still poorly understood. In the present study, we investigated the role of the STAT1/T-bet signaling pathway in a murine model of T-cell-mediated liver inflammation induced by the application of concanavalin A (Con A) using newly created STAT1 transgenic mice as well as STAT1- and T-bet-deficient mice. Liver injury induced by Con A was associated with an increase of both pSTAT1 and T-bet levels in the liver. Furthermore, functional studies suggested a pathogenic role for STAT1 in Con A-induced liver injury, because transgenic mice overexpressing STAT1 under the control of the CD2 promoter/enhancer construct showed elevated interferon gamma (IFN-gamma) and IRF-1 levels as well as significantly augmented liver injury following administration of Con A. Consistently, we observed that both STAT1-deficient and T-bet-deficient mice were protected from such T-cell-dependent liver injury. In conclusion, these findings suggest a key pathogenic role for the STAT1/T-bet signaling pathway for T-cell activation in the Con A model of T-cell-mediated liver pathology.