High-dimensional profiling reveals Tc17 cell enrichment in active Crohn’s disease and identifies a potentially targetable signature

Abstract

The immune-pathology in Crohn’s disease is linked to dysregulated CD4+ T cell responses biased towards pathogenic TH17 cells. However, the role of CD8+ T cells able to produce IL-17 (Tc17 cells) remains unclear. Here we characterize the peripheral blood and intestinal tissue of Crohn’s disease patients (n = 61) with flow and mass cytometry and reveal a strong increase of Tc17 cells in active disease, mainly due to induction of conventional T cells. Mass cytometry shows that Tc17 cells express a distinct immune signature (CD6high, CD39, CD69, PD-1, CD27low) which was validated in an independent patient cohort. This signature stratifies patients into groups with distinct flare-free survival associated with differential CD6 expression. Targeting of CD6 in vitro reduces IL-17, IFN-γ and TNF production. These results identify a distinct Tc17 cell population in Crohn’s disease with proinflammatory features linked to disease activity. The Tc17 signature informs clinical outcomes and may guide personalized treatment decisions.

Phenotypic, molecular and functional characterisation of humanin vitro-generated IL-17A+ CD8+ T-cells

“…Additionally, we demonstrate a significant, 7-fold increase in IL-17F+ CD8+ T-cells when PBMC were stimulated in the presence of IL-1β and IL-23. Recent studies have detailed the use of in vitro polarising cultures to investigate pharmacological or cytokine directed modulation of Tc17 cell responses (13, 26) yet, as with earlier literature, their polarising protocols are not directly comparable. Li et al reported a 20-fold increase in Tc17 cell frequency of healthy and colorectal cancer patient naïve CD8+ T-cell cultures upon 7-day culture in IMDM media using anti-CD3/CD28 mAb stimulation with IL-2, IL-1β, IL-6, IL-23, TGFβ, anti-IL-4 and anti-IFNγ (26).…”

“…Li et al reported a 20-fold increase in Tc17 cell frequency of healthy and colorectal cancer patient naïve CD8+ T-cell cultures upon 7-day culture in IMDM media using anti-CD3/CD28 mAb stimulation with IL-2, IL-1β, IL-6, IL-23, TGFβ, anti-IL-4 and anti-IFNγ (26). Whilst Globig et al reported a maximum induction of ~0.6% IL-17A+ CD8+ T-cells within healthy donor PBMC cultured with T-cell activator in the presence of IL-1β, IL-6, IL-23 and TGFβ (13). Neither study performed extensive Tc17 cell immunophenotyping post-culture as we report here.…”

“…However, few studies have described factors driving human Tc17 cells. The small collection of studies thus far offers a consensus in that IL-1β, IL-6, IL-23 without or with TGFβ and anti-IFNγ can direct Tc17 cell responses (11,13,(22)(23)(24)(25)(26). In addition, evidence for involvement of cellular drivers comes from reports that activated monocytes from tumour sites rather than nontumour tissues more potently induced IL-17A+ CD8+ T-cells in vitro (27), and that pleural mesothelial cells from patients with tuberculosis infection significantly enhanced IL-17 production by patient blood-derived CD8+ T-cells, in a cell-cell contact-dependent manner (11).…”

“…This includes expression of the lineage-committing transcription factors retinoic acid-receptor (RAR)-related orphan receptor (ROR)γt and musculoaponeurotic fibrosarcoma (c-MAF), surface expression of the typical type-17 markers CD161, CCR6 and IL-23R, and concomitant expression of Th17 (IL-17A, IL-17F, IL-21, IL-22 and granulocyte macrophage colony-stimulating factor (GM-CSF)) and cytotoxic CD8+ Tc1 (interferon (IFN)γ and tumour necrosis factor (TNF)α) related cytokines. The presence of these Tc17 cells has been described at different tissue sites in a variety of human infectious, autoimmune and inflammatory diseases, including tuberculosis (11), multiple sclerosis (12), inflammatory bowel disease (13) and psoriasis (14–16). We have also previously identified an enrichment of Tc17 cells in the joints of PsA patients that correlated with disease activity measures (17, 18).…”

Downregulation ofLet-7miRNA promotes Tc17 differentiation and emphysema via de-repression of RORγt

“…Moreover, we found that genetic ablation of IL-17A can attenuate nCB- or cigarette smoke-induced alveolar destruction and airway inflammation (Shan et al, 2012; You et al, 2015). More recently, IL-17A and IL-17F secreting CD8 + T cell (Tc17) subpopulation has been shown to play a critical role in the pathogenesis of several autoimmune and inflammatory disorders (Globig et al, 2022; Huber et al, 2013; Srenathan et al, 2016).…”