Published online Feb 14, 2015. doi: 10.3748/wjg.v21.i6.1759
Peer-review started: May 22, 2014
First decision: June 10, 2014
Revised: July 8, 2014
Accepted: July 24, 2014
Article in press: July 25, 2014
Published online: February 14, 2015
Processing time: 265 Days and 17.4 Hours
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-Itgbtmlcgn/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 (cellmax) 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 cellmax 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 cellmax locations.
CONCLUSION: The E-cadherin beta-7 integrin pathway probably controls migration of enterocytes within the small intestinal surface lining epithelial layer.
Core tip: Integrins are involved in migration of epithelial and non-epithelial cells. beta-7-chain integrins are exclusively expressed on leukocytes and important for homing of lymphocytes into the intestinal mucosa. In beta-7 integrin-deficient mice, the number of intraepithelial lymphocytes is drastically decreased and accompanied by a significant increase in enterocyte migration along the crypt-villus axis. This phenomenon is probably mediated by the E-cadherin beta-7 integrin pathway.