title: Macrophage recruitment by fibrocystin-defective biliary epithelial cells promotes portal fibrosis in congenital hepatic fibrosis.
abstract: Congenital hepatic fibrosis (CHF) is a disease of the biliary epithelium characterized by bile duct changes resembling ductal plate malformations and by progressive peribiliary fibrosis, in the absence of overt necroinflammation. Progressive liver fibrosis leads to portal hypertension and liver failure; however, the mechanisms leading to fibrosis in CHF remain elusive. CHF is caused by mutations in PKHD1, a gene encoding for fibrocystin, a ciliary protein expressed in cholangiocytes. Using a fibrocystin-defective (Pkhd1(del4/del4)) mouse, which is orthologous of CHF, we show that Pkhd1(del4/del4) cholangiocytes are characterized by a β-catenin-dependent secretion of a range of chemokines, including chemokine (C-X-C motif) ligands 1, 10, and 12, which stimulate bone marrow-derived macrophage recruitment. We also show that Pkhd1(del4/del4) cholangiocytes, in turn, respond to proinflammatory cytokines released by macrophages by up-regulating αvβ6 integrin, an activator of latent local transforming growth factor-β1. While the macrophage infiltrate is initially dominated by the M1 phenotype, the profibrogenic M2 phenotype increases with disease progression, along with the number of portal myofibroblasts. Consistent with these findings, clodronate-induced macrophage depletion results in a significant reduction of portal fibrosis and portal hypertension as well as of liver cysts.
  
  
  CONCLUSIONS
  Fibrosis can be initiated by an epithelial cell dysfunction, leading to low-grade inflammation, macrophage recruitment, and collagen deposition; these findings establish a new paradigm for biliary fibrosis and represent a model to understand the relationship between cell dysfunction, parainflammation, liver fibrosis, and macrophage polarization over time.
authors.affiliation: Department of Surgery and Translational Medicine, University of Milan-Bicocca, Milan, Italy.
authors.forename: Luigi
authors.initials: L
authors.lastname: Locatelli
authors.affiliation: Department of Surgery and Translational Medicine, University of Milan-Bicocca, Milan, Italy.|Department of Molecular Medicine, University of Padua School of Medicine, Padua, Italy.
authors.forename: Massimiliano
authors.initials: M
authors.lastname: Cadamuro
authors.affiliation: Section of Digestive Diseases, Yale University, New Haven, CT.
authors.forename: Carlo
authors.initials: C
authors.lastname: Spirlì
authors.affiliation: Section of Digestive Diseases, Yale University, New Haven, CT.
authors.forename: Romina
authors.initials: R
authors.lastname: Fiorotto
authors.affiliation: Center for Liver Research (CeLiveR), Papa Giovanni XXIII Hospital, Bergamo, Italy.
authors.forename: Silvia
authors.initials: S
authors.lastname: Lecchi
authors.affiliation: Department of Surgery and Translational Medicine, University of Milan-Bicocca, Milan, Italy.
authors.forename: Carola Maria
authors.initials: CM
authors.lastname: Morell
authors.affiliation: Division of Gastroenterology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA.
authors.forename: Yury
authors.initials: Y
authors.lastname: Popov
authors.affiliation: Department of Surgery and Translational Medicine, University of Milan-Bicocca, Milan, Italy.
authors.forename: Roberto
authors.initials: R
authors.lastname: Scirpo
authors.affiliation: Department of Molecular Medicine, University of Padua School of Medicine, Padua, Italy.
authors.forename: Maria
authors.initials: M
authors.lastname: De Matteis
authors.affiliation: Section of Digestive Diseases, Yale University, New Haven, CT.
authors.forename: Mariangela
authors.initials: M
authors.lastname: Amenduni
authors.affiliation: Liver Unit, Bambino Gesù Pediatric Hospital, IRCSS, Rome, Italy.
authors.forename: Andrea
authors.initials: A
authors.lastname: Pietrobattista
authors.affiliation: Liver Unit, Bambino Gesù Pediatric Hospital, IRCSS, Rome, Italy.
authors.forename: Giuliano
authors.initials: G
authors.lastname: Torre
authors.affiliation: Division of Gastroenterology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA.|Institute of Translational Immunology, Johannes Gutenberg University, Mainz, Germany.
authors.forename: Detlef
authors.initials: D
authors.lastname: Schuppan
authors.affiliation: Department of Molecular Medicine, University of Padua School of Medicine, Padua, Italy.|Section of Digestive Diseases, Yale University, New Haven, CT.
authors.forename: Luca
authors.initials: L
authors.lastname: Fabris
authors.affiliation: Department of Surgery and Translational Medicine, University of Milan-Bicocca, Milan, Italy.|Section of Digestive Diseases, Yale University, New Haven, CT.
authors.forename: Mario
authors.initials: M
authors.lastname: Strazzabosco
mesh_terms: D000818:Animals; D000951:Antigens, Neoplasm / Q000378:metabolism; D018925:Chemokines / Q000378:metabolism*; D004002:Clodronic Acid; D003094:Collagen / Q000378:metabolism; D004195:Disease Models, Animal; D004847:Epithelial Cells / Q000378:metabolism*; D030342:Genetic Diseases, Inborn / Q000276:immunology* / Q000378:metabolism; D016023:Integrins / Q000378:metabolism; D008103:Liver Cirrhosis / Q000276:immunology* / Q000378:metabolism; D008264:Macrophages / Q000502:physiology*; D051379:Mice; D058628:Myofibroblasts / Q000502:physiology; D011956:Receptors, Cell Surface / Q000172:deficiency*; D000071250:Snail Family Transcription Factors; D014157:Transcription Factors / Q000378:metabolism; D053773:Transforming Growth Factor beta1 / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
chemical_list: D000951:Antigens, Neoplasm; D018925:Chemokines; D016023:Integrins; C484365:Pkhd1 protein, mouse; D011956:Receptors, Cell Surface; D000071250:Snail Family Transcription Factors; C508961:Tgfb1 protein, mouse; D014157:Transcription Factors; D053773:Transforming Growth Factor beta1; D014409:Tumor Necrosis Factor-alpha; C073878:integrin alphavbeta6; D004002:Clodronic Acid; D003094:Collagen