Beta-7 integrin controls enterocyte migration in the small intestine.

Aim: To hypothesize that beta-7 integrin affects cellular migration of both, lymphocytes and enterocytes.

Methods: The nucleoside analog BrdU was ip injected in beta-7-deficient mice (C57BL/6-Itgb(tmlcgn)/J) of male gender and age-matched male C57BL/J J mice (wild type) 4, 20, or 40 h before analysis. The total small intestine was isolated, dissected, and used for morphometrical studies. BrdU-positive epithelial cells were numbered in at least 15 hemi-crypts per duodenum, jejunum, and ileum of each animal. The outer most BrdU-positive cell (cell(max)) was determined per hemi-crypt, numerically documented, and statistically analysed.

Results: Integrins containing the beta-7-chain were exclusively expressed on leukocytes. In the small intestinal mucosa of beta-7 integrin-deficient mice the number of intraepithelial lymphocytes was drastically decreased. Moreover, the Peyer's patches of beta-7 integrin-deficient mice appeared hypoplastic. In beta-7 integrin-deficient mice the location of cell(max) was found in a higher position than it was the case for the controls. The difference was already detected at 4 h after BrdU application, but significantly increased with time (40 h after BrdU injection) in all small intestinal segments investigated, i.e., duodenum, jejunum, and ileum. Migration of small intestinal enterocytes was different between the experimental groups measured by cell(max) locations.

Conclusion: The E-cadherin beta-7 integrin pathway probably controls migration of enterocytes within the small intestinal surface lining epithelial layer.