The first two authors contributed equally to the study.
Article first published online: 6 MAY 2011
Copyright © 2011 Crohn's & Colitis Foundation of America, Inc.
Inflammatory Bowel Diseases
Volume 18, Issue 1, pages 101–111, January 2012
How to Cite
Xiao, F., Juric, M., Li, J., Riederer, B., Yeruva, S., Kumar Singh, A., Zheng, L., Glage, S., Kollias, G., Dudeja, P., Tian, D.-A., Xu, G., Zhu, J., Bachmann, O. and Seidler, U. (2012), Loss of downregulated in adenoma (DRA) impairs mucosal HCO3− secretion in murine ileocolonic inflammation. Inflamm Bowel Dis, 18: 101–111. doi: 10.1002/ibd.21744
Supported by the Deutsche Forschungsgemeinschaft grants SFB621-C9, and Se460/13-4 (to U.S.) SFB621-C10 (to O.B.), and the DFG Chinese-German exchange grant DFG 446 CHV 113/268/0-1 (to U.S. and J.Z.).
The first two authors share the first, and the last two share the corresponding authorship.
- Issue published online: 11 DEC 2011
- Article first published online: 6 MAY 2011
- Manuscript Accepted: 28 MAR 2011
- Manuscript Received: 17 MAR 2011
- inflammatory bowel disease;
- anion exchanger;
Ileocolonic luminal pH has been reported to be abnormally low in inflammatory bowel disease (IBD) patients, and one of the causative factors may be reduced epithelial HCO secretory rate (J). Disturbances in J may occur due to inflammation-induced changes in the crypt and villous architecture, or due to the effect of proinflammatory cytokines on epithelial ion transporters.
To discriminate between these possibilities, the tumor necrosis factor alpha (TNF-α) overexpressing (TNF+/ΔARE) mouse model was chosen, which displays high proinflammatory cytokine levels in both ileum and colon, but develops only mild colonic histopathology and diarrhea. HCO secretion, mRNA expression, immunohistochemistry, and fluid absorptive capacity were measured in ileal and mid-colonic mucosa of TNF+/ΔARE and wildtype (WT) (TNF+/+) mice in Ussing chambers, and in anesthetized mice in vivo.
The high basal J observed in WT ileal and mid-colonic mucosa were luminal Cl−-dependent and strongly decreased in TNF+/ΔARE mice. Downregulated in adenoma (DRA) mRNA and protein expression was strongly decreased in TNF+/ΔARE ileocolon, whereas cystic fibrosis transmembrane conductance regulator (CFTR), Na+/H+ exchanger 3 (NHE3), Na+/HCO cotransporter (NBC), and epithelial sodium channel (ENaC) expression was not significantly altered. This indicates that the severe defect in ileocolonic J was due to DRA downregulation. Fluid absorption was severely depressed in the ileum but only mildly affected in the mid-distal colon, preventing the development of overt diarrhea.
Even mild ileocolonic inflammation may result in a decrease of epithelial HCO secretion, which may contribute to alterations in surface pH, intestinal flora, and mucus barrier properties. (Inflamm Bowel Dis 2011;)