Pharmacological inhibition of STAT3 pathway ameliorates acute liver injury in vivo via inactivation of inflammatory macrophages and hepatic stellate cells

Liver diseases represent a major health problem worldwide, in particular, acute liver injury is associated with high mortality and morbidity. Inflammatory macrophages and hepatic stellate cells (HSCs) are known to be involved in the pathogenesis of acute liver injury. In this study, we have investigated the implication of STAT3 inhibition in acute liver injury/early fibrogenesis. In fibrotic human livers, we found STAT3 mRNA expression was significantly upregulated and correlated with collagen I expression. In vitro, STAT3 signaling pathway was found to be activated in TGFβ-activated HSCs and inflammatory macrophages. STAT3 inhibitor, WP1066 significantly inhibited TGFβ-induced collagen I, vimentin and α-SMA expression, and contractility in human HSCs. In LPS- and IFNγ-induced pro-inflammatory macrophages, WP1066 strongly attenuated nitric-oxide release and expression of major inflammatory markers such as TNF-α, iNOS, CCL2, IL-1β, IL-6, and CCR2. In vivo in CCl4-induced acute liver injury mouse model, WP1066 significantly reduced collagen expression, HSCs activation, and intrahepatic inflammation. Finally, in LPS-induced human hepatic 3D spheroid model, WP1066 inhibited LPS-induced fibrotic and inflammatory parameters. In conclusion, our results demonstrate that the therapeutic inhibition of STAT3 pathway using WP1066 targeting HSCs and inflammatory macrophages suggests a potential pharmacological approach for the treatment of acute liver injury.

Inhibition of canonical WNT signaling pathway by β-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 β-catenin/CBP inhibitor ICG001 was examined in-vitro in TGFβ-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.

Tyrosine kinase inhibitor BIBF1120 ameliorates inflammation, angiogenesis and fibrosis in CCl4-induced liver fibrogenesis mouse model

Hepatic fibrosis, a progressive chronic disease mainly caused by hepatitis viral infections, alcohol abuse or metabolic syndrome leading to liver dysfunction and is the growing cause of mortality worldwide. Tyrosine kinase inhibitor BIBF1120 (Nintedanib) has been evaluated in clinical trials for idiopathic pulmonary fibrosis and advanced Hepatocellular carcinoma, but has not been explored for liver fibrosis yet. In this study, we aimed to investigate the therapeutic effects and mechanism of BIBF1120 in liver fibrogenesis. The effects of BIBF1120 were evaluated in TGFβ-activated mouse 3T3 fibroblasts, LX2 cells, primary human hepatic stellate cells (HSCs) and CCl₄-induced liver fibrogenesis mouse model. Fibroblasts-conditioned medium studies were performed to assess the paracrine effects on macrophages and endothelial cells. In-vitro in TGFβ-activated fibroblasts, BIBF1120 significantly inhibited expression of major fibrotic parameters, wound-healing and contractility. In vivo in CCl₄-induced acute liver injury model, post-disease BIBF1120 administration significantly attenuated collagen accumulation and HSC activation. Interestingly, BIBF1120 drastically inhibited intrahepatic inflammation and angiogenesis. To further elucidate the mechanism of action, 3T3-conditioned medium studies demonstrated increased 3T3-mediated macrophage chemotaxis and endothelial cells tube formation and activation, which was significantly decreased by BIBF1120. These results suggests that BIBF1120 can be a potential therapeutic approach for the treatment of liver fibrosis.