title: 1,25-(OH)₂-vitamin D₃ prevents activation of hepatic stellate cells in vitro and ameliorates inflammatory liver damage but not fibrosis in the Abcb4(-/-) model.
abstract: OBJECTIVE
  Vitamin D3-deficiency is common in patients with chronic liver-disease and may promote disease progression. Vitamin D3-administration has thus been proposed as a therapeutic approach. Vitamin D3 has immunomodulatory effects and may modulate autoimmune liver-disease such as primary sclerosing cholangitis. Although various mechanisms of action have been proposed, experimental evidence is limited. Here we test the hypothesis that active 1,25-(OH)2-vitamin D3 inhibits activation of hepatic stellate cells (HSC) in vitro and modulates liver-injury in vivo.
  
  
  METHODS
  Proliferation and activation of primary murine HSC were assessed by BrdU- and PicoGreen(®)-assays, immunoblotting, immunofluorescence-microscopy, quantitative-PCR, and zymography following calcitriol-treatment. Wild-type and ATP-binding cassette transporter b4(-/-) (Abcb4(-/-))-mice received calcitriol for 4 weeks. Liver-damage, inflammation, and fibrosis were assessed by serum liver-tests, Sirius-red staining, quantitative-PCR, immunoblotting, immunohistochemistry and hydroxyproline quantification.
  
  
  RESULTS
  In vitro, calcitriol inhibited activation and proliferation of murine HSC as shown by reduced α-smooth muscle actin and platelet-derived growth factor-receptor-β-protein-levels, BrdU and PicoGreen®-assays. Furthermore, mRNA-levels and activity of matrix metalloproteinase 13 were profoundly increased. In vivo, calcitriol ameliorated inflammatory liver-injury reflected by reduced levels of alanine aminotransferase in Abcb4(-/-)-mice. In accordance, their livers had lower mRNA-levels of F4/80, tumor necrosis factor-receptor 1 and a lower count of portal CD11b positive cells. In contrast, no effect on overall fibrosis was observed.
  
  
  CONCLUSIONS
  Calcitriol inhibits activation and proliferation of HSCs in vitro. In Abcb4(-/-)-mice, administration of calcitriol ameliorates inflammatory liver-damage but has no effect on biliary fibrosis after 4 weeks of treatment.
authors.affiliation: Department of Medicine II, Liver Center Munich, University of Munich, Marchioninistr. 15, D-81377 Munich, Germany. Electronic address: florian.reiter@med.uni-muenchen.de.
authors.forename: Florian P
authors.initials: FP
authors.lastname: Reiter
authors.affiliation: Department of Medicine II, Liver Center Munich, University of Munich, Marchioninistr. 15, D-81377 Munich, Germany.
authors.forename: Simon
authors.initials: S
authors.lastname: Hohenester
authors.affiliation: Department of Medicine II, Liver Center Munich, University of Munich, Marchioninistr. 15, D-81377 Munich, Germany.
authors.forename: Jutta M
authors.initials: JM
authors.lastname: Nagel
authors.affiliation: Department of Medicine II, Liver Center Munich, University of Munich, Marchioninistr. 15, D-81377 Munich, Germany.
authors.forename: Ralf
authors.initials: R
authors.lastname: Wimmer
authors.affiliation: Department of Medicine II, Liver Center Munich, University of Munich, Marchioninistr. 15, D-81377 Munich, Germany.
authors.forename: Renate
authors.initials: R
authors.lastname: Artmann
authors.affiliation: Department of Medicine II, Liver Center Munich, University of Munich, Marchioninistr. 15, D-81377 Munich, Germany.
authors.forename: Lena
authors.initials: L
authors.lastname: Wottke
authors.affiliation: Institute of Pathology, University of Munich, Thalkirchner Str. 36, D-80337 Munich, Germany.
authors.forename: Marie-Christine
authors.initials: MC
authors.lastname: Makeschin
authors.affiliation: Institute of Pathology, University of Munich, Thalkirchner Str. 36, D-80337 Munich, Germany.
authors.forename: Doris
authors.initials: D
authors.lastname: Mayr
authors.affiliation: Department of Medicine I, Krankenhaus Barmherzige Brüder, Romanstr. 93, D-80639 Munich, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Rust
authors.affiliation: Hans Popper Laboratory of Molecular Hepatology, Division of Gastroenterology and Hepatology, Department of Internal Medicine III, Medical University of Vienna, Währinger Gürtel 18-20, A-1090 Vienna, Austria.
authors.forename: Michael
authors.initials: M
authors.lastname: Trauner
authors.affiliation: Department of Medicine II, Liver Center Munich, University of Munich, Marchioninistr. 15, D-81377 Munich, Germany.
authors.forename: Gerald U
authors.initials: GU
authors.lastname: Denk
mesh_terms: D018435:ATP Binding Cassette Transporter, Subfamily B / Q000172:deficiency* / Q000235:genetics; D000818:Animals; D002117:Calcitriol / Q000494:pharmacology*; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D004195:Disease Models, Animal; D055166:Hepatic Stellate Cells / Q000187:drug effects* / Q000276:immunology / Q000473:pathology; D006520:Hepatitis, Animal / Q000188:drug therapy* / Q000276:immunology / Q000473:pathology; D007155:Immunologic Factors / Q000494:pharmacology; D008103:Liver Cirrhosis / Q000188:drug therapy* / Q000276:immunology / Q000473:pathology; D053509:Matrix Metalloproteinase 13 / Q000235:genetics / Q000378:metabolism; D051379:Mice; D018345:Mice, Knockout; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D000097202:ATP-Binding Cassette Sub-Family B Member 4
chemical_list: D018435:ATP Binding Cassette Transporter, Subfamily B; D002117:Calcitriol; D007155:Immunologic Factors; D053509:Matrix Metalloproteinase 13; D012333:RNA, Messenger; D000097202:ATP-Binding Cassette Sub-Family B Member 4; C507081:Mmp13 protein, mouse
keywords: Abcb4; Calcitriol; Cholestasis; Fibrosis; Primary sclerosing cholangitis; Vitamin D