title: Aquaporin-1 and 8 expression in the gallbladder mucosa might not be associated with the development of gallbladder stones in humans.
abstract: BACKGROUND
  Cholecystolithiasis is a highly prevalent condition in the Western world. Gallbladder stone-related conditions represent the second most common gastrointestinal pathology. Cholesterol stones represent over 80% of gallstones. Cholesterol stones develop secondary to crystallization of bile cholesterol. Water resorption from gallbladder bile via aquaporin in the gallbladder mucosa might play a role in the development of cholesterol stones. This study investigated the expression of Aquaporin-1 (AQP1) and Aquaporin-8 (AQP8) in the human gallbladder mucosa and their possible association with the formation of gallbladder stones.
  
  
  METHODS
  The expression of AQP1 and AQP8 in the gallbladder mucosa was examined via immunohistochemical staining. The expression of both AQP1 and AQP8 in the gallbladder mucosa of stone carriers (study group) was compared to that of nonstone carriers (control group).
  
  
  RESULTS
  Eighty-four gallbladder specimens from 44 male (52·2%) and 40 female (47·6%) patients were analysed. The study group included 47 specimens from stone carriers, while 37 specimens from stone-free gallbladders were included in the control group. Immunostaining for both AQP1 and AQP8 was positive in 80 cases. AQP1 was expressed both over the apical and intercellular membrane, while AQP8 was expressed only over the apical membrane. A similar distribution was recorded in specimens from the cystic duct. Immunostaining with AQP1 was generally stronger in comparison with AQP8. No significant (P > 0·05) relationship was found between aquaporin expression and the presence or absence of gallbladder stones.
  
  
  CONCLUSIONS
  AQP1 and AQP8 are both expressed in the gallbladder and cystic duct mucosa. However, their role in the development of gallbladder stones is still to be proven.
authors.affiliation: Department of Surgery II, Helios Klinikum Wuppertal, Universität Witten Herdecke, Wuppertal, Germany.
authors.forename: Peter C
authors.initials: PC
authors.lastname: Ambe
authors.affiliation: Institute of Pathology and Molecular Pathology, Helios Klinikum Wuppertal, Universität Witten Herdecke, Wuppertal, Germany.
authors.forename: Daniel
authors.initials: D
authors.lastname: Gödde
authors.affiliation: Department of Surgery II, Helios Klinikum Wuppertal, Universität Witten Herdecke, Wuppertal, Germany.
authors.forename: Hubert
authors.initials: H
authors.lastname: Zirngibl
authors.affiliation: Institute of Pathology and Molecular Pathology, Helios Klinikum Wuppertal, Universität Witten Herdecke, Wuppertal, Germany.
authors.forename: Stephan
authors.initials: S
authors.lastname: Störkel
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D051398:Aquaporin 1 / Q000378:metabolism*; D020346:Aquaporins / Q000378:metabolism*; D016022:Case-Control Studies; D041761:Cholecystolithiasis / Q000378:metabolism* / Q000601:surgery; D005260:Female; D005704:Gallbladder / Q000378:metabolism*; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008875:Middle Aged; D009092:Mucous Membrane / Q000378:metabolism*; D012189:Retrospective Studies; D016037:Single-Blind Method; D055815:Young Adult
chemical_list: C496020:AQP1 protein, human; D020346:Aquaporins; C108330:aquaporin 8; D051398:Aquaporin 1
keywords: Aquaporin; cholecystolithiasis; cholesterol stones; gallbladder mucosa; gallstones; immunohistochemistry