Endothelin Receptor-A Inhibition Decreases Ductular Reaction, Liver Fibrosis, and Angiogenesis in a Model of Cholangitis
Travis Owen, Guido Carpino, Lixian Chen, Debjyoti Kundu, Payton G. Wills, Burcin Ekser, Paolo Onori, Eugenio Gaudio, Gianfranco Alpini, Heather Francis, Lindsey Kennedy
Abstract
Background & Aims Primary sclerosing cholangitis (PSC) leads to ductular reaction and fibrosis and is complicated by vascular dysfunction. Cholangiocyte and endothelial cell crosstalk modulates their proliferation in cholestatic models. Endothelin (ET)-1 and ET-2 bind to their receptor, ET-A, and cholangiocytes are a key source of ET-1 after bile duct ligation. We aimed to evaluate the therapeutic potential of ET-A inhibition in PSC and biliary-endothelial crosstalk mediated by this pathway. Methods Wild-type and multidrug resistance 2 knockout ( Mdr2 -/ - ) mice at 12 weeks of age were treated with vehicle or Ambrisentan (ET-A antagonist) for 1 week by daily intraperitoneal injections. Human control and PSC samples were used. Results Mdr2 -/- mice at 4, 8, and 12 weeks displayed angiogenesis that peaked at 12 weeks. Mdr2 -/- mice at 12 weeks had enhanced biliary ET-1/ET-2/ET-A expression and secretion, whereas human PSC had enhanced ET-1/ET-A expression and secretion. Ambrisentan reduced biliary damage, immune cell infiltration, and fibrosis in Mdr2 -/- mice. Mdr2 -/- mice had squamous cholangiocytes with blunted microvilli and dilated arterioles lacking cilia; however, Ambrisentan reversed these alterations. Ambrisentan decreased cholangiocyte expression of pro-angiogenic factors, specifically midkine, through the regulation of cFOS. In vitro , ET-1/ET-A caused cholangiocyte senescence, endothelial cell angiogenesis, and macrophage inflammation. In vitro , human PSC cholangiocyte supernatants increased endothelial cell migration, which was blocked with Ambrisentan treatment. Conclusions ET-A inhibition reduced biliary and liver damage in Mdr2 -/- mice. ET-A promotes biliary angiocrine signaling that may, in turn, enhance angiogenesis. Targeting ET-A may prove therapeutic for PSC, specifically patients displaying vascular dysfunction.