title: Role of TGF-β signaling in differentiation of mesothelial cells to vitamin A-poor hepatic stellate cells in liver fibrosis.
abstract: Mesothelial cells (MCs) form a single layer of the mesothelium and cover the liver surface. A previous study demonstrated that, upon liver injury, MCs migrate inward from the liver surface and give rise to hepatic stellate cells (HSCs) in biliary fibrosis induced by bile duct ligation (BDL) or myofibroblasts in CCl4-induced fibrosis. The present study analyzed the role of transforming growth factor-β (TGF-β) signaling in mesothelial-mesenchymal transition (MMT) and the fate of MCs during liver fibrosis and its regression. Deletion of TGF-β type II receptor (Tgfbr2) gene in cultured MCs suppressed TGF-β-mediated myofibroblastic conversion. Conditional deletion of Tgfbr2 gene in MCs reduced the differentiation of MCs to HSCs and myofibroblasts in the BDL and CCl4 models, respectively, indicating that the direct TGF-β signaling in MCs is responsible to MMT. After BDL and CCl4 treatment, MC-derived HSCs and myofibroblasts were distributed near the liver surface and the thickness of collagen was increased in Glisson's capsule beneath the liver surface. Fluorescence-activated cell sorting analysis revealed that MC-derived HSCs and myofibroblasts store little vitamin A lipids and have fibrogenic phenotype in the fibrotic livers. MCs contributed to 1.4 and 2.0% of activated HSCs in the BDL and CCl4 models, respectively. During regression of CCl4-induced fibrosis, 20% of MC-derived myofibroblasts survived in the liver and deactivated to vitamin A-poor HSCs. Our data indicate that MCs participate in capsular fibrosis by supplying vitamin A-poor HSCs during a process of liver fibrosis and regression.
authors.affiliation: Southern California Research Center for ALPD and Cirrhosis, Department of Pathology, Keck School of Medicine, University of Southern California, Los Angeles, California; and.
authors.forename: Yuchang
authors.initials: Y
authors.lastname: Li
authors.affiliation: Southern California Research Center for ALPD and Cirrhosis, Department of Pathology, Keck School of Medicine, University of Southern California, Los Angeles, California; and.
authors.forename: Ingrid
authors.initials: I
authors.lastname: Lua
authors.affiliation: Department of Pathology, Harbor-UCLA Medical Center, Torrance, California.
authors.forename: Samuel W
authors.initials: SW
authors.lastname: French
authors.affiliation: Southern California Research Center for ALPD and Cirrhosis, Department of Pathology, Keck School of Medicine, University of Southern California, Los Angeles, California; and asahina@usc.edu.
authors.forename: Kinji
authors.initials: K
authors.lastname: Asahina
mesh_terms: D000818:Animals; D001652:Bile Ducts / Q000473:pathology / Q000503:physiopathology; D002252:Carbon Tetrachloride Poisoning / Q000473:pathology; D002454:Cell Differentiation; D002478:Cells, Cultured; D058750:Epithelial-Mesenchymal Transition; D004848:Epithelium / Q000473:pathology*; D005347:Fibroblasts / Q000473:pathology; D055166:Hepatic Stellate Cells / Q000473:pathology*; D008026:Ligation; D008099:Liver / Q000473:pathology; D008103:Liver Cirrhosis / Q000473:pathology*; D051379:Mice; D018345:Mice, Knockout; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism; D000077294:Receptor, Transforming Growth Factor-beta Type II; D018125:Receptors, Transforming Growth Factor beta / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D016212:Transforming Growth Factor beta; D014802:Vitamin A Deficiency / Q000473:pathology*
chemical_list: D018125:Receptors, Transforming Growth Factor beta; D016212:Transforming Growth Factor beta; D017346:Protein Serine-Threonine Kinases; D000077294:Receptor, Transforming Growth Factor-beta Type II
keywords: Glisson's capsule; capsular fibrosis; fibrosis regression; myofibroblasts; vitamin A