TG101348, a selective JAK2 antagonist, ameliorates hepatic fibrogenesis in vivo.

Hepatic fibrosis, characterized by an excessive extracellular matrix (ECM) accumulation, leading to scar-tissue formation is a growing health problem worldwide. Hepatocellular damage due to liver injury triggers inflammation and transdifferentiation of quiescent hepatic stellate cells (HSCs) into proliferative, contractile, and ECM-producing myofibroblasts. Involvement of the Janus kinase (JAK)-2 pathway in the pathogenesis of fibrosis has been reported earlier. However, in this study, we have investigated the effect of selective JAK2 antagonist TG101348 in fibroblasts and inflammatory macrophages and in vivo in an acute carbon tetrachloride-induced liver injury mouse model. In vitro, TG101348 significantly inhibited TGF-ß-induced collagen I expression in murine 3T3 fibroblasts. In human HSCs (LX2 cells), TG101348 potently attenuated TGF-ß-induced contractility and the protein and gene expression of major fibrotic parameters (collagen I, vimentin, and α-smooth muscle actin). In LPS- and IFN-γ-stimulated inflammatory macrophages, TG101348 significantly reduced the NO release and strongly inhibited the expression of inflammatory markers (inducible nitric oxide synthase, C-C motif chemokine ligand 2, IL-1ß, IL-6, and C-C chemokine receptor type 2). In vivo in an acute liver injury mouse model, TG101348 significantly attenuated collagen accumulation and HSC activation. Interestingly, TG101348 drastically inhibited macrophage infiltration and intrahepatic inflammation. Pharmacological inhibition of the JAK2 signaling pathway in activated HSCs and inflammatory macrophages using TG101348 suggests a potential therapeutic approach for the treatment of liver fibrosis.-Akcora, B. O., Dathathri, E., Ortiz-Perez, A., Gabriël, A. V., Storm, G., Prakash, J., Bansal, R. TG101348, a selective JAK2 antagonist, ameliorates hepatic fibrogenesis in vivo.

Inhibition of canonical WNT signaling pathway by ß-catenin/CBP inhibitor ICG-001 ameliorates liver fibrosis in vivo through suppression of stromal CXCL12.

Quiescent hepatic stellate cells (HSCs), in response to liver injury, undergo characteristic morphological transformation into proliferative, contractile and ECM-producing myofibroblasts. In this study, we investigated the implication of canonical Wnt signaling pathway in HSCs and liver fibrogenesis. Canonical Wnt signaling pathway activation and inhibition using ß-catenin/CBP inhibitor ICG001 was examined in-vitro in TGFß-activated 3T3, LX2, primary human HSCs, and in-vivo in CCl4-induced acute liver injury mouse model. Fibroblasts-conditioned medium studies were performed to assess the Wnt-regulated paracrine factors involved in crosstalk between HSCs-macrophages and HSCs-endothelial cells. Canonical Wnt signaling pathway components were significantly up-regulated in-vitro and in-vivo. In-vitro, ICG-001 significantly inhibited fibrotic parameters, 3D-collagen contractility and wound healing. Conditioned medium induced fibroblasts-mediated macrophage and endothelial cells activation was significantly inhibited by ICG-001. In-vivo, ICG-001 significantly attenuated collagen accumulation and HSC activation. Interestingly, ICG-001 drastically inhibited macrophage infiltration, intrahepatic inflammation and angiogenesis. We further analyzed the paracrine factors involved in Wnt-mediated effects and found CXCL12 was significantly suppressed both in-vitro and in-vivo following Wnt inhibition. Wnt-regulated CXCL12 secretion from activated HSCs potentiated macrophage infiltration and activation, and angiogenesis. Pharmacological inhibition of canonical Wnt signaling pathway via suppression of stromal CXCL12 suggests a potential therapeutic approach targeting activated HSCs in liver fibrosis.