Phenotypic Characterization of Canine Intestinal Intraepithelial Lymphocytes in Dogs with Inflammatory Bowel Disease

Abstract

BackgroundMany dogs suffering from inflammatory bowel disease (IBD) are presented to veterinary clinics. These patients are diagnosed based on a history of chronic gastrointestinal signs and biopsy‐confirmed histopathologic intestinal inflammation. Intestinal intraepithelial lymphocytes (IEL) are part of the first line of defense in the gastrointestinal immune system. Alterations in IEL subsets may play a role in the pathogenesis of IBD.HypothesisThe aim of this study was to characterize the phenotypes of IEL in dogs with IBD compared with healthy control dogs.AnimalsIntestinal intraepithelial lymphocytes subpopulations of control dogs (n = 5) obtained from endoscopic biopsies (EB) were compared to those obtained from full thickness biopsies (FTB) on the same day. In addition, the phenotypes of IEL from FTB of control dogs (n = 10) were compared with EB of IBD dogs (n = 10). Each participant was scored clinically using the canine inflammatory bowel disease activity index (CIBDAI), and all samples were graded histopathologically. Three‐color flow cytometry of isolated IEL was performed using monoclonal antibodies against T‐ and B‐lymphocyte subpopulations.ResultsNo significant differences in the composition of IEL subpopulations were found in control dogs based on method of biopsy. The IBD dogs had significantly higher CIBDAI and histopathologic scores compared with control dogs and their IEL contained a significantly higher frequency TCRγδ T‐cells.Conclusions and Clinical ImportanceEndoscopic biopsies provide suitable samples for 3‐color flow cytometry when studying canine intestinal IEL and IBD patients show significant changes of major T‐cell subsets compared to healthy control dogs.

Identification of histamine receptors in the canine gastrointestinal tract

“…18 These findings are similar to previous reports of mild histopathology changes in asymptomatic healthy, control dogs. 23,24 Histology of the canine GI tract is affected by many factors, including age, intestinal parasites, diet, intestinal flora, medications, and environmental allergens. 18,24 All dogs received monthly topical parasiticide 2 and deworming every 3 months; 3 therefore intestinal parasitism is an unlikely explanation for the mild GI inflammation noted.…”

“…23,24 Histology of the canine GI tract is affected by many factors, including age, intestinal parasites, diet, intestinal flora, medications, and environmental allergens. 18,24 All dogs received monthly topical parasiticide 2 and deworming every 3 months; 3 therefore intestinal parasitism is an unlikely explanation for the mild GI inflammation noted. The authors agree with the observation by Junginger et al, that mild histopathological abnormalities may simply represent background variation in the GI tract of normal dogs.…”

“…3 The H3 receptor has also been found in other nonneurological tissues, including the respiratory epithelium, gastric and intestinal mucosa, skin, vascular endothelium, thymus, heart, and kidney of the rat. 5,24 The H3 receptor is involved primarily in negative feedback-mediated inhibition of the synthesis and release of not only histamine but also other neurotransmitters such as dopamine, serotonin, glutamate, acetylcholine, and norepinephrine. 1,2 Neurogenic inflammation may also be controlled in part through the interaction of histamine on mast cell H3 receptors through a neuron-mast cell feedback loop.…”

Inflammatory Bowel Disease and Current Treatment Options in Dogs

“…Inflammatory Bowel Disease (IBD) represents a group of chronic, inflammatory disorders in the gastrointestinal system in animals as well as humans (Haas et al, 2014). It is a progressive disease with poorly characterized etiology (Jackson and Jewell, 2015).…”

“…It is a progressive disease with poorly characterized etiology (Jackson and Jewell, 2015). IBD is especially important for dogs, because large number of dogs suffer from chronic or recurrent gastrointestinal problems (Cerquetella et al, 2010;Haas et al, 2014).…”