title: Mucosal injury and inflammatory cells in response to brief ischaemia and reperfusion in the equine large colon.
abstract: BACKGROUND
  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.
  
  
  OBJECTIVE
  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/mm(2) mucosa vs. 1hI + 2hR: 1149.9 ± 220.6 cells/mm(2) 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.
  
  
  CONCLUSIONS
  Equine colonic mucosa subjected to a brief period of ischaemia can repair during reperfusion, despite increased mucosal inflammation.
authors.affiliation: Transplant Center, Department of Surgery, College of Medicine, Shands at University of Florida, Gainesville, FL, USA. agrosche@vetmed.ufl.edu
authors.forename: A
authors.initials: A
authors.lastname: Grosche
authors.forename: A J
authors.initials: AJ
authors.lastname: Morton
authors.forename: A S
authors.initials: AS
authors.lastname: Graham
authors.forename: J F
authors.initials: JF
authors.lastname: Valentine
authors.forename: J R
authors.initials: JR
authors.lastname: Abbott
authors.forename: M M R
authors.initials: MM
authors.lastname: Polyak
authors.forename: D E
authors.initials: DE
authors.lastname: Freeman
mesh_terms: D000818:Animals; D003106:Colon / Q000473:pathology*; D003108:Colonic Diseases / Q000473:pathology / Q000662:veterinary*; D051545:Cyclooxygenase 1 / Q000235:genetics / Q000378:metabolism; D051546:Cyclooxygenase 2 / Q000235:genetics / Q000378:metabolism; D004804:Eosinophils / Q000502:physiology; D015971:Gene Expression Regulation, Enzymologic; D006734:Horse Diseases / Q000473:pathology*; D006736:Horses; D007249:Inflammation / Q000662:veterinary*; D007413:Intestinal Mucosa / Q000166:cytology / Q000201:enzymology / Q000293:injuries* / Q000473:pathology; D008264:Macrophages / Q000502:physiology; D008407:Mast Cells / Q000502:physiology; D009504:Neutrophils / Q000502:physiology; D015427:Reperfusion Injury / Q000473:pathology / Q000662:veterinary*
chemical_list: D051545:Cyclooxygenase 1; D051546:Cyclooxygenase 2