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IFN-γ is a signature Th1 cell associated cytokine critical for the inflammatory response in autoimmunity with both pro-inflammatory and potentially protective functions. IL-17A is the hallmark of T helper 17 (Th17) cell subsets, produced by γδT, CD8+ T, NK and NKT cells. We have taken advantage of our colony of IL-2Rα−/− mice that spontaneously develop both autoimmune cholangitis and inflammatory bowel disease. In this model CD8+ T cells mediate biliary ductular damage, whereas CD4+ T cells mediate induction of colon-specific autoimmunity. Importantly, IL-2Rα−/− mice have high levels of interferon γ (IFN-γ), and interleukin-17A (IL-17A). We produced unique double deletions of mice that were either IL-17A−/−IL-2Rα−/− or IFN-γ−/−IL-2Rα−/− to specifically address the precise role of these two cytokines in the natural history of autoimmune cholangitis and colitis. Of note, deletion of IL-17A in IL-2Rα−/− mice led to more severe liver inflammation, but ameliorated colitis. In contrast, there were no significant changes in the immunopathology of double knock-out IFN-γ−/− IL-2Rα−/− mice, compared to single knock-out IL-2Rα−/− mice with respect to cholangitis or colitis. Furthermore, there was a significant increase in pathogenetic CD8+ T cells in the liver of IL-17A−/−IL-2Rα−/− mice. Our data suggest that while IL-17A plays a protective role in autoimmune cholangitis, it has a pro-inflammatory role in inflammatory bowel disease. These data take on particular significance in the potential use of anti-IL-17A therapy in humans with primary biliary cirrhosis. [ABSTRACT FROM AUTHOR]

Abstract: There have been major advances in defining the immunological events associated with fibrosis in various chronic liver diseases. We have taken advantage of this data to focus on the mechanisms of action of a unique multi-kinase inhibitor, coined sorafenib, on CCl4-induced murine liver fibrosis, including the effects of this agent in models of both acute and chronic CCl4-mediated pathology. Importantly, sorafenib significantly attenuated chronic liver injury and fibrosis, including reduction in liver inflammation and histopathology as well as decreased expression of liver fibrosis-related genes, including α-smooth muscle actin, collagen, matrix metalloproteinases and the tissue inhibitor of metalloproteinase-1. Furthermore, sorafenib treatment resulted in translocation of cytoplasmic STAT3 to the nucleus in its active form. Based on this observation, we used hepatocyte-specific STAT3 knockout (STAT3Hep−/−) mice to demonstrate that hepatic STAT3 was critical for sorafenib-mediated protection against liver fibrosis, and that the upregulation of STAT3 phosphorylation was dependent on Kupffer cell-derived IL-6. In conclusion, these data reflect the clinical potential of the multi-kinase inhibitor sorafenib for the prevention of fibrosis as well as the treatment of established liver fibrosis and illustrate the immunological mechanisms that underlie the protective effects of sorafenib. [Copyright &y& Elsevier]