Project description:Background and aims: Signal transducer and activator of transcription 3 (Stat3) is the main mediator of interleukin-6 type cytokine signaling required for hepatocyte proliferation and hepatoprotection but its role in sclerosing cholangitis and other cholestatic liver diseases remains unresolved. Methods: We investigated the role of Stat3 in inflammation-induced cholestatic liver injury and used mice lacking the multidrug resistance gene 2 (mdr2-/-) as a model for SC. Results: We demonstrate that conditional inactivation of stat3 in hepatocytes and cholangiocytes (stat3 delta hc) of mdr2-/- mice strongly aggravated bile acid-induced liver injury and fibrosis. A similar phenotype was observed in mdr2-/- mice lacking IL-6 production. Biochemical and molecular characterization suggested that Stat3 exerts hepatoprotective functions in both, hepatocytes and cholangiocytes. Loss of Stat3 in cholangiocytes led to increased expression of TNFα which might reduce the barrier function of bile ducts. Loss of Stat3 in hepatocytes led to upregulation of bile acid biosynthesis genes and downregulation of hepatoprotective epidermal growth factor receptor and insulin-like growth factor 1 signaling pathways. Consistently, stat3deltahc mice were more sensitive to cholic acid-induced liver damage than control mice. Conclusions: Our data suggest that Stat3 prevents cholestasis and liver damage in sclerosing cholangitis via regulation of pivotal functions in hepatocytes and cholangiocytes. Affymetrix microarray analyses was performed to identify metabolic and molecular pathways in stat3Dhc mdr2-/- mice that lead to cholestasis and bile acid-induced liver injury. To avoid false positive results that are due to differential cellular composition, we defined the onset of fibrosis and expression of fibrogenic factors in stat3Dhc mdr2-/- mice.
Project description:Primary sclerosing cholangitis (PSC) is a chronic liver disease characterized by biliary strictures, cholestasis, and an increased risk of cholangiocarcinoma (CCA). Here, we have used label-free quantitative proteomics to analyze serum and bile samples from non-PSC controls and PSC patients, as well as from PSC patients divided into groups according to endoscopic retrograde cholangiography score (with a score of >4 indicating advanced disease) and presence or absence of biliary dysplasia/CCA. Further analyses subsequently identified multiple candidates of new noninvasive serum markers for the diagnosis of PSC, as well as new markers for the prediction of the risk of disease progression and biliary neoplasia for patients already diagnosed with PSC.
Project description:Primary sclerosing cholangitis (PSC) is a chronic liver disease characterized by biliary strictures, cholestasis, and an increased risk of cholangiocarcinoma (CCA). Here, we have used label-free quantitative proteomics to analyze serum and bile samples from non-PSC controls and PSC patients, as well as from PSC patients divided into groups according to endoscopic retrograde cholangiography score (with a score of >4 indicating advanced disease) and presence or absence of biliary dysplasia/CCA. Further analyses subsequently identified multiple candidates of new noninvasive serum markers for the diagnosis of PSC, as well as new markers for the prediction of the risk of disease progression and biliary neoplasia for patients already diagnosed with PSC.
Project description:Primary sclerosing cholangitis (PSC) is a rare liver disease characterized by chronic inflammation and irreparable damage to the bile ducts. Due to a limited understanding of the underlying pathogenesis of disease, there remains a paucity of treatment options. As such, we sequenced healthy and diseased livers to compare the activity, interactions, and localization of immune and non-immune cells. This revealed that outside PSC scar regions, hepatocytes are transitioning to bile duct cells, whereas within the scars, there is an accumulation of immune cells. Of these cells, macrophages that typically contribute to tissue repair were enriched in immunoregulatory genes and were less responsive to stimulation. These cells are likely involved in maintaining hepatic inflammation and could be targeted in novel therapeutic development.
Project description:Primary sclerosing cholangitis (PSC) is a rare liver disease characterized by chronic inflammation and irreparable damage to the bile ducts. Due to a limited understanding of the underlying pathogenesis of disease, there remains a paucity of treatment options. As such, we sequenced healthy and diseased livers to compare the activity, interactions, and localization of immune and non-immune cells. This revealed that outside PSC scar regions, hepatocytes are transitioning to bile duct cells, whereas within the scars, there is an accumulation of immune cells. Of these cells, macrophages that typically contribute to tissue repair were enriched in immunoregulatory genes and were less responsive to stimulation. These cells are likely involved in maintaining hepatic inflammation and could be targeted in novel therapeutic development.
Project description:Primary sclerosing cholangitis (PSC) is a rare liver disease characterized by chronic inflammation and irreparable damage to the bile ducts. Due to a limited understanding of the underlying pathogenesis of disease, there remains a paucity of treatment options. As such, we sequenced healthy and diseased livers to compare the activity, interactions, and localization of immune and non-immune cells. This revealed that outside PSC scar regions, hepatocytes are transitioning to bile duct cells, whereas within the scars, there is an accumulation of immune cells. Of these cells, macrophages that typically contribute to tissue repair were enriched in immunoregulatory genes and were less responsive to stimulation. These cells are likely involved in maintaining hepatic inflammation and could be targeted in novel therapeutic development.
Project description:Primary sclerosing cholangitis (PSC) is a rare liver disease characterized by chronic inflammation and irreparable damage to the bile ducts. Due to a limited understanding of the underlying pathogenesis of disease, there remains a paucity of treatment options. As such, we sequenced healthy and diseased livers to compare the activity, interactions, and localization of immune and non-immune cells. This revealed that outside PSC scar regions, hepatocytes are transitioning to bile duct cells, whereas within the scars, there is an accumulation of immune cells. Of these cells, macrophages that typically contribute to tissue repair were enriched in immunoregulatory genes and were less responsive to stimulation. These cells are likely involved in maintaining hepatic inflammation and could be targeted in novel therapeutic development.
Project description:Primary sclerosing cholangitis (PSC) is characterized by chronic inflammation and progressive fibrosis of the biliary tree. The bile acid receptor TGR5 is found on biliary epithelial cells (BECs), where it promotes secretion, proliferation and tight junction integrity. Thus, we speculated that changes in TGR5 expression in BECs may contribute to PSC pathogenesis.
Project description:Hepatocytes are highly polarized epithelia. Loss of hepatocyte polarity is associated with various liver diseases, including cholestasis. However, the molecular underpinnings of hepatocyte polarization remain poorly understood. Previously, we have shown that loss of β-catenin at adherens junctions (AJs) is compensated by β-catenin and dual loss of both catenins in dual knockouts (DKO) in mice liver leads to progressive intrahepatic cholestasis. However, the clinical relevance of this observation, and further phenotypic characterization of the phenotype, is important. Here, we identify simultaneous loss of β- and γ-catenin in a subset of liver samples from patients of progressive familial intrahepatic cholestasis and primary sclerosing cholangitis. Hepatocytes in DKO mice exhibited defect in apical-basolateral localization of polarity proteins, impaired bile canaliculi formation, and loss of microvilli. Loss of polarity in DKO livers manifested as epithelial-to-mesenchymal transition, increased hepatocyte proliferation, and suppression of hepatocyte differentiation, which was associated with up-regulation of TGFβ signaling and repression of Hnf4α expression and activity. In conclusion, concomitant loss of the two catenins in the liver may be playing a pathogenic role in subsets of cholangiopathies. Our findings also support a previously unknown role β- and γ-catenin in the maintenance of hepatocyte polarity. Improved understanding of the regulation of hepatocyte polarization processes by β and γ-catenin could potentially benefit development of new therapies for cholestasis.