title: Morphological and functional heterogeneity of the mouse intrahepatic biliary epithelium.
abstract: Rat and human biliary epithelium is morphologically and functionally heterogeneous. As no information exists on the heterogeneity of the murine intrahepatic biliary epithelium, and with increased usage of transgenic mouse models to study liver disease pathogenesis, we sought to evaluate the morphological, secretory, and proliferative phenotypes of small and large bile ducts and purified cholangiocytes in normal and cholestatic mouse models. For morphometry, normal and bile duct ligation (BDL) mouse livers (C57/BL6) were dissected into blocks of 2-4 microm(2), embedded in paraffin, sectioned, and stained with hematoxylin and eosin. Sizes of bile ducts and cholangiocytes were evaluated by using SigmaScan to measure the diameters of bile ducts and cholangiocytes. In small and large normal and BDL cholangiocytes, we evaluated the expression of cholangiocyte-specific markers, keratin-19 (KRT19), secretin receptor (SR), cystic fibrosis transmembrane conductance regulator (CFTR), and chloride bicarbonate anion exchanger 2 (Cl(-)/HCO(3)(-) AE2) by immunofluorescence and western blot; and intracellular cyclic adenosine 3',5'-monophosphate (cAMP) levels and chloride efflux in response to secretin (100 nM). To evaluate cholangiocyte proliferative responses after BDL, small and large cholangiocytes were isolated from BDL mice. The proliferation status was determined by analysis of the cell cycle by fluorescence-activated cell sorting, and bile duct mass was determined by the number of KRT19-positive bile ducts in liver sections. In situ morphometry established that the biliary epithelium of mice is morphologically heterogeneous, with smaller cholangiocytes lining smaller bile ducts and larger cholangiocytes lining larger ducts. Both small and large cholangiocytes express KRT19 and only large cholangiocytes from normal and BDL mice express SR, CFTR, and Cl(-)/HCO(3)(-) exchanger and respond to secretin with increased cAMP levels and chloride efflux. Following BDL, only large mouse cholangiocytes proliferate. We conclude that similar to rats, mouse intrahepatic biliary epithelium is morphologically and functionally heterogeneous. The mouse is therefore a suitable model for defining the heterogeneity of the biliary tree.
authors.affiliation: Scott and White Digestive Diseases Research Center, Temple, TX, USA. sglaser@tamu.edu
authors.forename: Shannon S
authors.initials: SS
authors.lastname: Glaser
authors.forename: Eugenio
authors.initials: E
authors.lastname: Gaudio
authors.forename: Arundhati
authors.initials: A
authors.lastname: Rao
authors.forename: Lisa M
authors.initials: LM
authors.lastname: Pierce
authors.forename: Paolo
authors.initials: P
authors.lastname: Onori
authors.forename: Antonio
authors.initials: A
authors.lastname: Franchitto
authors.forename: Heather L
authors.initials: HL
authors.lastname: Francis
authors.forename: David E
authors.initials: DE
authors.lastname: Dostal
authors.forename: Julie K
authors.initials: JK
authors.lastname: Venter
authors.forename: Sharon
authors.initials: S
authors.lastname: DeMorrow
authors.forename: Romina
authors.initials: R
authors.lastname: Mancinelli
authors.forename: Guido
authors.initials: G
authors.lastname: Carpino
authors.forename: Domenico
authors.initials: D
authors.lastname: Alvaro
authors.forename: Shelley E
authors.initials: SE
authors.lastname: Kopriva
authors.forename: Jennifer M
authors.initials: JM
authors.lastname: Savage
authors.forename: Gianfranco D
authors.initials: GD
authors.lastname: Alpini
mesh_terms: D000818:Animals; D000943:Antigens, Differentiation / Q000378:metabolism; D001653:Bile Ducts, Intrahepatic / Q000166:cytology / Q000502:physiology*; D002453:Cell Cycle / Q000502:physiology*; D049109:Cell Proliferation; D048429:Cell Size; D002780:Cholestasis, Intrahepatic / Q000473:pathology; D004848:Epithelium / Q000502:physiology; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL
chemical_list: D000943:Antigens, Differentiation