CD4 ⁺ T-Cells With High Common γ Chain Expression and Disturbed Cytokine Production Are Enriched in Children With Type-1 Diabetes

The common gamma chain (γ _c) contributes to the formation of different cytokine receptors [e.g., IL-2 receptor (IL-2R), IL-7R, and IL-15R], which are important for generation of self-reactive T-cells in autoimmune diseases, like in type 1 diabetes (T1D). Whereas, the roles of membrane and soluble IL-2Rα and IL-7Rα variants in T1D disease pathogenesis are well-described, effects of γ _c expression and availability for dependent receptors remain elusive. We investigated expression of the γ _c and dependent receptors on T-cells and soluble γ _c concentrations in serum from patients with T1D ( n = 34) and healthy controls ( n = 27). Effector T-cell cytokines as well as IL-2, IL-7, and IL-15 induced STAT5 phosphorylation were analyzed to determine functional implications of differential γ _c expression of CD4 ⁺ T-cell subsets classified by t-distributed Stochastic Neighbor Embedding (t-SNE) analyses. We found increased γ _c and IL-7Rα expression of CD4 ⁺ T-cells from T1D patients as compared to controls. t-SNE analyses assigned differential expression to subsets of memory T-cells co-expressing γ _c and IL-7Rα. Whereas, γ _c expression was positively correlated with IL-2Rα in memory T-cells from healthy controls, no dependency was found for patients with T1D. Similarly, the effector T-cell cytokine, IL-21, correlated inversely with γ _c expression in healthy controls, but not in T1D patients. Finally, T1D patients with high γ _c expression had increased proportions of IL-2 sensitive pSTAT5 ⁺ effector T-cells. These results indicated aberrantly high γ _c expression of T-cells from T1D patients with implications on dependent cytokine receptor signaling and effector T-cell cytokine production.