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Role of Na‐H Exchanger‐2 in Experimental Colitis: Mechanism of Regulation of Expression
Author(s) -
Khan Islam,
Soleiman Amal Ali,
Thameem Farook
Publication year - 2017
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.31.1_supplement.629.5
Subject(s) - colitis , mucin , western blot , chemistry , sodium–hydrogen antiporter , inflammatory bowel disease , ileum , medicine , immunofluorescence , microbiology and biotechnology , endocrinology , biology , biochemistry , immunology , sodium , antibody , disease , organic chemistry , gene
Background The Na‐H exchanger (NHE) perform an electroneutral uptake of NaCl and water from the lumen of the gastrointestinal tract. There are multiple distinct NHE isoforms, some of which show an altered expression in the inflammatory bowel diseases (IBD). In this study, we examined a role of NHE‐2 in experimental colitis. Methods Colitis was induced in male Sprague‐Dawley rats by intra‐rectal administration of trinitrobenezenesulfonic acid (TNBS). On day 6 post‐TNBS, the animals were sacrificed, colon and ileal segments were taken out, cleaned with phosphate buffered saline and used in this study. Results There was a significant decrease in the level of NHE‐2 protein as measured by ECL western blot and confocal immunofluorescence micrometry. The levels of NHE‐2 mRNA and heteronuclear RNA measured by an end‐point RT‐PCR and the real time PCR were also decreased significantly in the inflamed colon. However there was no change in the level of NHE‐2 protein in response to in‐vitro TNF‐α treatment of an uninflamed rat colon. These changes were selective and localized to colon as actin, an internal control remained unchanged. The confocal fluorescence microscopy revealed co‐localization of NHE‐2 and NHE‐3 in the brush borders of the colonic epithelial cells. Inflamed colon showed a significant increase in the myeloperoxidase activity and colon hypertrophy, and a significant decrease in the body weight and goblet cells' mucin staining. These changes were not conspicuous in the non‐inflamed ileum. Conclusions These findings demonstrate suppression of NHE‐2 expression on the brush borders in the colonic epithelial cells which is regulated transcriptionally. However a role of TNF‐α in the regulation of NHE‐2 is discounted in the present model of colitis. This decrease in the NHE‐2 expression will lead to a loss of electrolyte and water uptake thus contributing to the symptoms associated with IBD. Support or Funding Information The Kuwait University, Research Grant No. [YM 12/15]. Prof Khan, Anatomy for his help in tissue block preparation for histochemistry and confocal microscopy. Research Core Facility, Health Sciences, the Kuwait University for using their facility to conduct confocal immunofluorescence experiments.