Decreased Frequency of Intestinal CD39+ γδ+ T Cells With Tissue-Resident Memory Phenotype in Inflammatory Bowel Disease.

Jana Libera,Melanie Wittner,Jocelyn De Heer,Samuel Huber,Johanna M Eberhard,Robin Woost,Marcus Kantowski,Dominik Reher,Friedrich Haag,Julian Schulze Zur Wiesch

doi:10.3389/fimmu.2020.567472

Abstract

The ectoenzymes CD39 and CD73 play a major role in controlling tissue inflammation by regulating the balance between adenosine triphosphate (ATP) and adenosine. Still, little is known about the role of these two enzymes and ATP and its metabolites in the pathophysiology of inflammatory bowel disease (IBD). We isolated mononuclear cells from peripheral blood and lamina propria of the large intestine of patients diagnosed with IBD and of healthy volunteers. We then comprehensively analyzed the CD39 and CD73 expression patterns together with markers of activation (HLA-DR, CD38), differentiation (CCR7, CD45RA) and tissue-residency (CD69, CD103, CD49a) on CD4+, CD8+, γδ+ T cells and mucosa-associated invariant T cells using flow cytometry. CD39 expression levels of γδ+ and CD8+ T cells in lamina propria lymphocytes (LPL) were much higher compared to peripheral blood mononuclear cells. Moreover, the frequency of CD39+ CD4+ and CD8+, but not γδ+ LPL positively correlated with T-cell activation. The frequency of CD39+ cells among tissue-resident memory LPL (Trm) was higher compared to non-Trm for all subsets, confirming that CD39 is a marker for the tissue-resident memory phenotype. γδ+ Trm also showed a distinct cytokine profile upon stimulation – the frequency of IFN-γ+ and IL-17A+ cells was significantly lower in γδ+ Trm compared to non-Trm. Interestingly, we observed a decreased frequency of CD39+ γδ+ T cells in IBD patients compared to healthy controls (p = 0.0049). Prospective studies need to elucidate the exact role of this novel CD39+ γδ+ T-cell population with tissue-resident memory phenotype and its possible contribution to the pathogenesis of IBD and other inflammatory disorders.

Highlights

Inflammatory bowel disease (IBD) is the umbrella term for Crohn’s disease (CD), ulcerative colitis (UC) and indeterminate colitis (IC)
Flow cytometry panels were designed to differentiate between CD4+, CD8+, mucosa-associated invariant T cells (MAIT), and γδ+ T cells which were further separated into Vδ2− and Vδ2+ subsets for some analysis
While CD4+ T cells were more frequent in peripheral blood mononuclear cells (PBMC) compared to lamina propria lymphocytes (LPL), the proportion of CD8+ and γδ+ T cells was higher in LPL than in PBMC (Figure 1A)

Summary

Introduction

Inflammatory bowel disease (IBD) is the umbrella term for Crohn’s disease (CD), ulcerative colitis (UC) and indeterminate colitis (IC) These diseases share aetiological and pathophysiological features and are characterized by a combination of genetic and environmental factors causing immune dysregulation [1, 2], and altered composition of the gut microbiota [3, 4]. In 2018, Raczkowski et al demonstrated that CD39+ and CD73+ cells in human mucosal tissue protect the epithelium from the proinflammatory effects of commensal bacteria-derived ATP in the intestinal lumen [13]. These findings strongly suggest that CD39 contributes to the regulation of the inflammatory microenvironment, and that changes in CD39 expression or function might promote the onset and perpetuation of IBD. There are only few human studies that comprehensively assessed the CD39 and CD73 expression patterns of different T-cell subsets in peripheral blood and mucosal tissue of healthy individuals versus IBD patients [19, 20]

Methods

Results

Conclusion