title: Urine-based detection of intestinal tight junction loss.
abstract: BACKGROUND
  Tight junction breakdown, with loss of the important sealing protein claudin-3, is an early event in the development of intestinal damage. Therefore, noninvasive analysis of intestinal tight junction status could be helpful in early detection of intestinal injury.
  
  
  OBJECTIVE
  To investigate the usefulness of urinary claudin-3 as marker for intestinal tight junction loss.
  
  
  METHODS
  A rat hemorrhagic shock model and a human setting of known intestinal damage, that is, patients with relapsed inflammatory bowel disease (IBD), were used to investigate intestinal tight junction status by immunohistochemical staining and urinary claudin-3 levels by western blot.
  
  
  RESULTS
  In rats claudin-3 urine levels increased rapidly after histologically proven intestinal tight junction loss, with significantly elevated levels at 90 minutes after shock compared with sham-operated animals [mean+/-SEM: 611+/-101 intensity (INT), n=6 vs. 232+/-30 INT, n=6; P<0.05]. Moreover, in colonic biopsies of patients with IBD relapse claudin-3 staining was reduced compared with biopsies of patients with IBD without signs of disease. Concomitantly, significantly increased claudin-3 urine levels were found in these patients (502+/-67 INT, n=10) compared with patients with IBD in remission (219+/-17 INT, n=10, P<0.001) and healthy volunteers (225+/-38 INT, n=10, P<0.001).
  
  
  CONCLUSIONS
  Here we show for the first time in both an experimental and clinical setting a strong relation between intestinal tight junction loss and urinary claudin-3 levels. These findings suggest that measurement of urinary claudin-3 can be used as noninvasive marker for intestinal tight junction loss. This offers new opportunities for early diagnosis and follow-up of intestinal injury.
authors.affiliation: Department of Surgery, Maastricht University Medical Centre and Nutrition and Toxicology Research Institute Maastricht, The Netherlands.
authors.forename: Geertje
authors.initials: G
authors.lastname: Thuijls
authors.forename: Joep P M
authors.initials: JP
authors.lastname: Derikx
authors.forename: Jacco-Juri
authors.initials: JJ
authors.lastname: de Haan
authors.forename: Joep
authors.initials: J
authors.lastname: Grootjans
authors.forename: Adriaan
authors.initials: A
authors.lastname: de Bruïne
authors.forename: Ad A M
authors.initials: AA
authors.lastname: Masclee
authors.forename: Erik
authors.initials: E
authors.lastname: Heineman
authors.forename: Wim A
authors.initials: WA
authors.lastname: Buurman
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000818:Animals; D015415:Biomarkers / Q000652:urine; D015153:Blotting, Western; D002648:Child; D062465:Claudin-3; D004195:Disease Models, Animal; D005260:Female; D006801:Humans; D015212:Inflammatory Bowel Diseases / Q000503:physiopathology*; D007413:Intestinal Mucosa / Q000378:metabolism*; D008297:Male; D008565:Membrane Proteins / Q000652:urine*; D008875:Middle Aged; D051381:Rats; D017207:Rats, Sprague-Dawley; D012771:Shock, Hemorrhagic / Q000503:physiopathology; D019108:Tight Junctions / Q000378:metabolism*; D055815:Young Adult
chemical_list: D015415:Biomarkers; C568122:CLDN3 protein, human; D062465:Claudin-3; C568124:Cldn3 protein, rat; D008565:Membrane Proteins