Expression of apical junction complex proteins in duodenal mucosa of dogs with inflammatory bowel disease

Objective-To determine the expression of tight junction and adherens junction proteins in duodenal mucosa samples of dogs with inflammatory bowel disease (IBD). Animals-12 dogs with IBD and 6 healthy control Beagles. Procedures-Duodenal mucosa biopsy samples were endoscopically obtained from dogs with IBD and healthy control Beagles. The expression of claudin-1, -2, -3, -4, -5, -7, and -8; E-cadherin; and beta-catenin in the duodenal mucosa samples was determined by means of immunoblotting. The subcellular localization of E-cadherin in the duodenal mucosa samples was determined with immunofluorescence microscopy. Results-The expression of each claudin and beta-catenin was not significantly different between control dogs and dogs with IBD. However, expression of E-cadherin was significantly lower in duodenal mucosa samples of dogs with IBD than it was in samples obtained from healthy control dogs. Results of immunofluorescence microscopy indicated decreased intensity of E-cadherin labeling in the tips of villi in duodenal mucosa samples obtained from 6 dogs with IBD, compared with staining intensity for other dogs. Conclusions and Clinical Relevance-Results of this study indicated expression of claudin-1, -2, -3, -4, -5, -7, and -8 and beta-catenin was not significantly different between duodenal mucosa samples obtained from control dogs and those obtained from dogs with IBD. However, E-cadherin expression was significantly lower in the villus epithelium in duodenal mucosa samples obtained from dogs with IBD versus samples obtained from control dogs, which suggested that decreased expression of that protein has a role in the pathogenesis of IBD in dogs.