Cells of the innate and adaptive immunity and their interactions in inflammatory bowel disease

Inflammatory bowel disease (IBD) is a group of chronic inflammatory conditions of the gastrointestinal tract that includes two major phenotypes, Crohn's disease and ulcerative colitis that are characterized by different clinical features and different course of the immune response. The exact aetiology of IBD still remains unknown, although it is thought that the diseases result from an excessive immune response directed against microbial or environmentally derived antigens which can be triggered by the disruption of the intestinal epithelial barrier integrity. In this review we present immune mechanisms and interactions between cells of the immune system and tissue environment that contribute to the development and progression of IBD in humans. Since dysregulation of the intestinal immune response is a hallmark of chronic inflammatory conditions, we characterize cells of the innate and adaptive immunity involved in the pathogenesis of IBD and their cross-talks. We describe various subclasses of recently discovered innate lymphoid cells, as well as dendritic cells, macrophages and T cells, including Th17, Th22 and T regulatory cells, present in the intestinal lamina propria and cytokine-mediated regulation of the immune response in IBD, highlighting the role of IL-22 and IL-17A/IL-23 axis. Insights into novel therapeutic modalities targeting certain elements of the immune pathways important for the pathogenesis of IBD have been also shortly presented.

Expression of death receptor 3 on peripheral blood mononuclear cells differes in adult IBD patients and children with newly diagnosed IBD

BACKGROUND

Interaction between TL1A and death receptor 3 (DR3) is associated with the pathogenesis of inflammatory bowel disease (IBD), although their role in the development of this disease remains not fully explained. Some studies showed elevated expression of TL1A and DR3 in inflamed intestinal tissue but currently there are no reports concerning expression of DR3 on peripheral blood mononuclear cells (PBMCs) of IBD patients which was the subject of our study.

METHODS

We performed flow cytometry analysis of DR3 expression on CD4(+), CD8(+), CD11c(+), CD14(+) or CD20(+) PBMCs of adults and children with IBD and healthy volunteers with respect to C-reactive protein (CRP) levels in blood. Blood samples were collected from pediatric patients before the beginning of therapy, whereas adults patients were undergoing anti-inflammatory IBD treatment and had much lower CRP levels.

RESULTS

With regard to appropriate healthy volunteers, children with IBD had elevated percentage of DR3-expressing CD4(+), CD8(+), CD11c(+) and CD20(+) PBMCs which, with the exception of DR3(+) CD11c(+) cells in children with ulcerative colitis, was correlated with CRP level in blood. Adult patients had increased frequency of DR3(+) CD8(+) and CD20(+) PBMCs and their CRP levels correlated only with DR3(+) CD8(+) cells.

CONCLUSIONS

In comparison to healthy volunteers, untreated children with IBD have higher percentage of DR3(+) PBMCs than adults with IBD undergoing anti-inflammatory treatment. In most of the investigated PBMCs populations, the frequency of DR3(+) cells is correlated with the level of CRP. We suggest anti-inflammatory treatment may lead to reduction in the frequency of DR3(+) PBMCs. © 2016 International Clinical Cytometry Society.