Surface protein and functional analyses identify CD4+CD39+ TCR αβ+ and activated TCR Vδ1+ cells with distinct pro-inflammatory functions in Crohn's disease lesions.

Crohn's disease (CD) is a chronic immune-mediated disorder of the gastrointestinal tract. Extensive screening studies have revealed the accumulation of immune cell subsets with unique plasticity and immunoregulatory properties in patients with CD. We performed phenotypic and functional studies on inflamed and non-inflamed bioptic tissue to investigate the presence of distinct T cells in the intestinal mucosa of CD patients. We analysed hundreds of surface molecules expressed on cells isolated from the intestinal tissue of CD patients using anti-CD45 mAbs-based barcoding. A gene ontology enrichment analysis showed that proteins that regulate the activation of T cells were the most enriched group. We, therefore, designed T-cell focused multicolour flow-cytometry panels and performed clustering analysis which revealed an accumulation of activated T_EM CD4⁺CD39⁺ T cells producing IL-17 and IL-21 and increased frequency of terminally differentiated TCR Vδ1⁺ cells producing TNF-α and IFN-γ in inflamed tissue of CD patients. The different functional capacities of CD4⁺ and TCR Vδ1⁺ cells in CD lesions indicate their non-overlapping contribution to inflammation. The abnormally high number of terminally differentiated TCR Vδ1⁺ cells suggests that they are continuously activated in inflamed tissue, making them a potential target for novel therapies. This study provides two main findings: the first is the increased presence of CD4-CD39 double-positive T cells, which are uniquely present in inflamed tissue and not in not inflamed tissue or in blood. The second main finding is a proportional increase of terminally differentiated TCR Vδ1 ⁺  cells in inflamed mucosa, a mirror of continuous activation. Our data also indicate that these two cell populations participate in local inflammation in a non-redundant manner, as they secrete IL-17 and IL-21 or TNF-α and IFN-γ, respectively. Graphical Abstract [ABSTRACT FROM AUTHOR]