Mucosal injury and inflammatory cells in response to brief ischaemia and reperfusion in the equine large colon
Article first published online: 25 JUL 2011
© 2011 EVJ Ltd
Equine Veterinary Journal
Special Issue: Equine Colic. Guest Editors: T.S. Mair and C.J. Proudman. Publication of this supplement was supported by The Horse Trust
Volume 43, Issue Supplement s39, pages 16–25, August 2011
How to Cite
GROSCHE, A., MORTON, A. J., GRAHAM, A. S., VALENTINE, J. F., ABBOTT, J. R., POLYAK, M. M. R. and FREEMAN, D. E. (2011), Mucosal injury and inflammatory cells in response to brief ischaemia and reperfusion in the equine large colon. Equine Veterinary Journal, 43: 16–25. doi: 10.1111/j.2042-3306.2011.00415.x
- Issue published online: 25 JUL 2011
- Article first published online: 25 JUL 2011
- [Paper received for publication 14.01.11; Accepted 05.04.11]
- epithelial damage;
- mast cells;
Reason for performing study: Intestinal ischaemia and reperfusion (I/R) can activate inflammatory cells in the equine colon, although effects on different types of inflammatory cells have received little attention.
Objectives: To assess early mucosal injury, the reaction of mucosal neutrophils, eosinophils, mast cells and macrophages, and cyclooxygenase (COX)-1 and -2 expression in response to I/R in the equine large colon.
Methods: Large colon ischaemia was induced for 1 h (1hI) followed by 4 h of reperfusion in 6 horses, and mucosal biopsies were sampled before and after ischaemia, and after 1, 2 and 4 h of reperfusion. Semithin sections (500 nm) of epon-embedded biopsies were stained with toluidine blue for histomorphometric evaluation. The number and distribution of mucosal macrophages (CD163), neutrophils (calprotectin), eosinophils (LUNA) and mast cells (toluidine blue) were determined, and mucosal COX-1 and -2 expression was identified.
Results: Ischaemia caused epithelial cell and nuclear swelling (mean ± s.e. nuclear width; control: 2.7 ± 0.2 µm vs. 1hI: 4.2 ± 0.2 µm; P<0.01), subepithelial oedema (control: 0.2 ± 0.1 µm vs. 1hI: 3.2 ± 0.2 µm; P<0.01) and increased epithelial apoptosis (control: 14.3 ± 4.1 apoptotic cells/mm mucosa vs. 1hI: 60.4 ± 14.0 apoptotic cells/mm mucosa; P<0.01). COX-2 expression (P<0.01) was evident after ischaemia. Reperfusion caused paracellular fluid accumulation (control: 0.9 ± 0.1 µm vs. 1hI: 0.6 ± 0.6 µm vs. 1hI + 4hR: 1.6 ± 0.2 µm; P<0.05). Epithelial repair started at 1 h of reperfusion (P<0.001), followed by migration of neutrophils into the mucosa after 2 h (control: 72.3 ± 18.4 cells/mm2 mucosa vs. 1hI + 2hR: 1149.9 ± 220.6 cells/mm2 mucosa; P<0.01). Mucosal eosinophils, mast cells and macrophages did not increase in numbers but were activated.
Conclusions: Epithelial injury and COX-2 expression caused by short-term hypoxia were followed by intense inflammation associated with epithelial repair during reperfusion.
Potential relevance: Equine colonic mucosa subjected to a brief period of ischaemia can repair during reperfusion, despite increased mucosal inflammation.