A type IV Autotaxin inhibitor ameliorates acute liver injury and non-alcoholic steatohepatitis in mice

An important but rather underexplored pathway implicated in liver disease is the lysophosphatidic acid (LPA) signaling axis. LPA acts through G-protein coupled receptors inducing downstream signaling pathways related to cell proliferation, differentiation, and migration, and is predominantly produced by the extracellular phosphodiesterase, Autotaxin (ATX). ATX has gained significant attention lately with an impressive number of ATX inhibitors (type I-IV) reported. Here, we aim to evaluate the therapeutic potential of a (yet unexplored) type IV ATX inhibitor, Cpd17, in liver injury. In this study, we first confirmed the involvement of the ATX/LPA signaling axis in human and murine diseased livers. Thereafter, we evaluated the effects of Cpd17, in comparison with the classic type I ATX inhibitor PF8380, in vitro. While both inhibitors attenuated induced cell injury phenotypes as assessed using various assays and specific readout parameters in hepatocytes, macrophages, and hepatic stellate cells (HSCs), Cpd17 appeared more effective. This prompted us to characterize the mechanism of action of both inhibitors in situ and in vitro in macrophages and HSCs, demonstrating that Cpd17 was more potent in inhibiting relevant signaling pathways, namely RhoA-mediated cytoskeletal remodeling, and phosphorylation of MAPK/ERK and AKT/PKB. Finally, we investigated the therapeutic potential of Cpd17 in two liver disease mouse models, CCl4-induced acute liver injury and diet-induced non-alcoholic steatohepatitis. We demonstrate that Cpd17 has an excellent potential for reducing liver injury in both disease models in vivo. We conclude that ATX inhibition, by type IV inhibitor in particular, has an excellent potential for clinical application in liver diseases.