Low-dose IL-2 reduces IL-21+ T cell frequency and induces anti-inflammatory gene expression in type 1 diabetes

Low-dose interleukin-2 is showing promise in the treatment of several autoimmune inflammatory diseases. Here authors map the trajectory of cellular and transcriptional changes in type 1 diabetes patients receiving an interval dosing interleukin-2 regimen, which shows an anti-inflammatory gene expression signature shared by all immune cell types analysed, persisting for at least a month after ending treatment. Despite early clinical successes, the mechanisms of action of low-dose interleukin-2 (LD-IL-2) immunotherapy remain only partly understood. Here we examine the effects of interval administration of low-dose recombinant IL-2 (iLD-IL-2) in type 1 diabetes using high-resolution single-cell multiomics and flow cytometry on longitudinally-collected peripheral blood samples. Our results confirm that iLD-IL-2 selectively expands thymic-derived FOXP3(+)HELIOS(+) regulatory T cells and CD56(bright) NK cells, and show that the treatment reduces the frequency of IL-21-producing CD4(+) T cells and of two innate-like mucosal-associated invariant T and V gamma 9V delta 2 CD8(+) T cell subsets. The cellular changes induced by iLD-IL-2 associate with an anti-inflammatory gene expression signature, which remains detectable in all T and NK cell subsets analysed one month after treatment. These findings warrant investigations into the potential longer-term clinical benefits of iLD-IL-2 in immunotherapy.