title: Chloride channel ClC-2 is a key factor in the development of DSS-induced murine colitis.
abstract: BACKGROUND
  Previously, it was shown that the chloride channel ClC-2 modulates intestinal tight junction (TJ) barrier function. The aim of the present study was to investigate the role of ClC-2 in epithelial barrier function and recovery in the event of epithelial injury.
  
  
  METHODS
  The role of ClC-2 was investigated in TJ barrier function in dextran sodium sulfate (DSS)-induced colitis in ClC-2 knockout mice and ClC-2 knockdown intestinal Caco-2 cells. Barrier function was measured electrophysiologically and by transepithelial mannitol fluxes. Selected TJ and associated proteins were Western blotted, cytokines were measured using quantitative PCR, and human colonic biopsies were examined with immunohistochemistry.
  
  
  RESULTS
  ClC-2 mice had a higher disease activity index, higher histological scores, and increased paracellular permeability compared with wild-type mice when treated with DSS. DSS-treated ClC-2 mice had increased claudin-2 expression, greater loss of occludin in the membrane, increased association of occludin with caveolin-1, and significantly increased tumor necrosis factor-α and interleukin-1β messenger RNA. ClC-2 knockdown in human intestinal Caco-2 cells resulted in a greater loss of epithelial resistance in the event of epithelial injury. The restoration of colonic barrier function after DSS colitis was delayed in ClC-2 mice. In human colonic biopsies, the protein and messenger RNA expression of ClC-2 was found to be reduced in patients with ulcerative colitis.
  
  
  CONCLUSIONS
  ClC-2 plays a critical role in experimental colitis in that its absence increases disease activity, reduces barrier function and recovery, and perturbs TJs. Furthermore, ClC-2 expression is markedly reduced in the colon of human patients with ulcerative colitis.
authors.affiliation: *Department of Clinical Sciences, Center for Comparative Medicine and Translational Research, College of Veterinary Medicine, North Carolina State University, Raleigh, North Carolina; †Department of Internal Medicine, School of Medicine, University of New Mexico, Albuquerque, New Mexico; and ‡Division of Gastroenterology and Hepatology, Department of Medicine, Center for Gastrointestinal Biology and Disease, and §Department of Microbiology and Immunology, University of North Carolina School of Medicine, Chapel Hill, North Carolina.
authors.forename: Prashant
authors.initials: P
authors.lastname: Nighot
authors.forename: Karen
authors.initials: K
authors.lastname: Young
authors.forename: Meghali
authors.initials: M
authors.lastname: Nighot
authors.forename: Manmeet
authors.initials: M
authors.lastname: Rawat
authors.forename: Eui J
authors.initials: EJ
authors.lastname: Sung
authors.forename: Nitsan
authors.initials: N
authors.lastname: Maharshak
authors.forename: Scott E
authors.initials: SE
authors.lastname: Plevy
authors.forename: Thomas
authors.initials: T
authors.lastname: Ma
authors.forename: Anthony
authors.initials: A
authors.lastname: Blikslager
mesh_terms: D000818:Animals; D015153:Blotting, Western; D000090007:CLC-2 Chloride Channels; D018938:Caco-2 Cells; D018118:Chloride Channels / Q000502:physiology*; D003092:Colitis / Q000139:chemically induced / Q000378:metabolism / Q000473:pathology*; D016207:Cytokines / Q000378:metabolism; D016264:Dextran Sulfate / Q000633:toxicity*; D004195:Disease Models, Animal; D005260:Female; D006801:Humans; D007124:Immunoenzyme Techniques; D007413:Intestinal Mucosa / Q000293:injuries / Q000378:metabolism / Q000473:pathology*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D012333:RNA, Messenger / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction; D019108:Tight Junctions / Q000378:metabolism / Q000473:pathology*
chemical_list: D000090007:CLC-2 Chloride Channels; D018118:Chloride Channels; D016207:Cytokines; D012333:RNA, Messenger; D016264:Dextran Sulfate
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