An IL-2 mutein increases IL-10 and CTLA-4-dependent suppression of dendritic cells by regulatory T cells [10x scRNA-seq]

Interleukin-2 (IL-2) variants with increased CD25 dependence that selectively expand Foxp3+ regulatory T (TR) cells are under clinical investigation for treating autoimmune and inflammatory diseases. We previously described an Fc-fused CD25-biased IL-2 mutein (Fc.IL-2 mutein) that promotes TR expansion and prevents the onset of autoimmune diabetes in non-obese diabetic (NOD) mice; however, the effects of this treatment on TR function in vivo are unclear. Here we show that Fc.IL-2 mutein treatment induces an activated Foxp3+ TR population characterized by elevated proliferation, a unique transcriptional program associated with Stat5- and TCR-dependent gene modules, and high levels of the immunosuppressive molecules IL-10 and CTLA-4. Increased IL-10 receptor signaling limits the upregulation of surface MHC class II expression during conventional dendritic cell (cDC) maturation, while increased CTLA-4-dependent transendocytosis leads to the transfer of CD80 and CD86 costimulatory ligands from maturing cDCs to Tregs. In NOD mice, Fc.IL-2 mutein treatment resulted in TR-mediated regulation of cDCs in the inflamed pancreas and draining lymph nodes accompanied by an increase in anergic T cells. Thus, we demonstrate that IL-2 mutein-expanded TR cells have enhanced functional properties and potently act to restrict cDC function in the target tissue and at the site of autoimmune induction, offering promising prospects for targeted immunotherapy. Overall design: These data contain 10x Gene Expression and Feature Barcode (CITE-seq) data from mouse spleen sorted CD4+ T-cells samples from twelve samples. Each bam file corresponds to a single Pool of three mice. One mouse in each pool represented each treatment -- one IL-2 Mutein treated animal, one IL-2 WT treated animal, and a PBS control animal.