Clinical Research
Copyright ©2007 Baishideng Publishing Group Co., Limited. All rights reserved.
World J Gastroenterol. Mar 21, 2007; 13(11): 1687-1695
Published online Mar 21, 2007. doi: 10.3748/wjg.v13.i11.1687
Aquaporin-8 expression is reduced in ileum and induced in colon of patients with ulcerative colitis
Alexandra Zahn, Christoph Moehle, Thomas Langmann, Robert Ehehalt, Frank Autschbach, Wolfgang Stremmel, Gerd Schmitz
Alexandra Zahn, Robert Ehehalt, Wolfgang Stremmel, Department of Gastroenterology, University Hospital Heidelberg, Heidelberg 69120, Germany
Christoph Moehle, Thomas Langmann, Gerd Schmitz, Institute of Clinical Chemistry, University of Regensburg, Regensburg 93042, Germany
Frank Autschbach, Institute of Pathology, University of Heidelberg, Heidelberg 69120, Germany
Author contributions: All authors contributed equally to the work.
Supported by a grant from the Dietmar Hopp Foundation
Correspondence to: Alexandra Zahn, MD, Department of Gastroenterology, University Hospital of Heidelberg, Im Neuenheimer Feld 410, D-69120 Heidelberg, Germany. alexandra.zahn@med.uni-heidelberg.de
Telephone: +49-6221-5634403 Fax: +49-6221-564116
Received: February 4, 2007
Revised: February 23, 2006
Accepted: March 14, 2007
Published online: March 21, 2007
Abstract

AIM: To study susceptibility genes which may play a potential role in the pathogenesis and etiology of inflammatory bowel disease (IBD).

METHODS: To identify potential susceptibility genes we performed global gene expression profiling in patients with IBD and control specimens. For determination of an intrinsic gene expression profile in ulcerative colitis (UC) and Crohn's disease (CD) compared to normal subjects, mucosal biopsies of non-inflamed regions of the colon and the terminal ileum were subjected to DNA microarray analysis. Real-time RT-PCR and immunohistochemistry were used for verification of selected regulated candidate genes and a genetic analysis was performed.

RESULTS: We could show that aquaporin-8 (AQP8) mRNA and protein levels were significantly increased in the colon of UC patients compared to controls. Genetic analysis of the six exons and the promoter region of AQP8, however, revealed no mutations or polymorphisms in IBD patients.

CONCLUSION: Our results suggest that upregulation of AQP8 in the colon of UC patients represents a secondary phenomenon which may, due to altered water exchange of the distal intestinal mucosa, disturb the physiologic colonic mucus barrier and thus lead to chronic infla-mmation and ulceration.

Keywords: Aquaporin-8; Colonic mucus barrier; DNA microarrays; Expression profiling; Ulcerative colitis