Canine gut dendritic cells in the steady state and in inflammatory bowel disease

Abstract

Alongside the intestinal border, dendritic cells (DCs) sample large amounts of endogenous and potentially pathogenic antigens followed by initiation of protective immune responses or induction of tolerance. Breakdown of oral tolerance towards commensal bacteria is suggested to be crucial for the development of both human and canine inflammatory bowel disease (IBD). The aim of this study was to investigate canine intestinal DCs in the steady state and in dogs with IBD using multicolour immunofluorescence. In the healthy gut, DC-like cells expressed MHC II, CD1a8.2 and CD11c, and, in lower amounts, CD11b, within lamina propria, Peyer's patches (PPs) and mesenteric lymph nodes (MLNs), whereas those expressing CD80 and CD86 were only present in PPs and MLNs. Occasionally, DC-like cells were in contact with the intestinal lumen through transepithelial projections. In canine IBD, CD1a8.2+, CD11b+ and CD11c+ DC-like cells were decreased within the stomach, duodenum and colon, whereas the colonic mucosa revealed elevation of CD86+ DC-like cells. The complex network of DC-like cells in the gut indicates their important role in canine mucosal immunity, including active sampling of luminal antigens. Furthermore, their shift in diseased dogs suggests a pathogenetic significance for canine IBD.

Heterogeneity of macrophages in canine histiocytic ulcerative colitis

“…20,21 PAS þ cells similar to macrophages characteristic for HUC were absent in the colon of dogs without gastrointestinal disorders.…”

“…Owing to the retrospective character of the study detailed clinical data were not available. Full-thickness colonic samples obtained postmortem from nine dogs (cases [12][13][14][15][16][17][18][19][20], which had been used in previous studies, 20,21 served as age-matched controls. All control dogs were euthanised for reasons other than gastrointestinal disorders, in consensus with their owners, and submitted for necropsy.…”

Histamine Receptor Expression in the Gastrointestinal Tract of Dogs

“…H1R and H2R expression was described for certain T-cell subtypes, B cells, dendritic cells, macrophages as well as neutrophilic and eosinophilic granulocytes by different methods in several species (Jutel et al, 2001(Jutel et al, , 2009Gantner et al, 2002;Akdis and Simons, 2006). Although most of these cell types are regularly found in lamina propria mucosae and in lymphoid aggregates of the intestine of dogs (German et al, 2001;Kleinschmidt et al, 2008;Junginger et al, 2014), exact identification of these histamine receptor expressing immune cell types would require further investigations using double labelling techniques. Strong immunohistochemical labelling for H2R was seen on single elongated cells that were mainly located within the crypts of stomach, small intestine and colon.…”

“…Most of the animals (animal nos. 1-10, 12, 14, 16-18) had been used in previous studies (Junginger et al, 2012(Junginger et al, , 2014. This study was carried out according to the German animal welfare act and international guidelines for animal use and has been approved by the animal welfare officer of the university.…”

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“…A predictive approach of the fecal bacterial metagenome using PICRUSt also did not reveal differences between the period before and during prebiotic administration. A second trial using a higher dose of prebiotics (3.2 mL/kg Guard et al, 2015; Hand et al, 76 2013; Handl etal., 2013;Junginger et al, 2014;Kieler et al, 2016;Minamoto et al, 2014; 77 Minamoto et al,2015;Song et al, 2013;Suchodolski et al, 2015). These studies are supported 78 by meta'omic analytic techniques (Morgan and Huttenhower, 2014) and powerful freely-…”