Enhancing Treg cell therapy using a tethered autocrine orthogonal IL-2 system 2807

Abstract Description Regulatory T cell (Treg) therapy aims to restore immune tolerance, but only a small fraction of infused Tregs persist long term in patients. Concomitant low-dose IL-2 improved Treg survival, but also activated cytotoxic T cells, limiting its utility. In this study, we explored cell engineering strategies to enable selective delivery of IL-2 to therapeutic Tregs in a mouse model of type 1 diabetes. We first tested an orthogonal IL-2-IL-2R system, in which mutated IL-2 (ortho-2) were selected to preferentially engage a mutated IL-2 receptor (ortho-2R). We found that a highly selective ortho-2,3A10, failed to improve diabetes prevention by ortho-2R+ Tregs due to its low affinity, whereas another ortho-2,1G12, with higher affinity for ortho-2R did not achieve selective IL-2 signaling in engineered Tregs due to its cross-reactivity on wild-type IL-2R. To facilitate Treg-selective signaling, we physically linked ortho-2 to the ortho-2R via a peptide linker and expressed the construct in Tregs. We found tethered 3A10 was superior to tethered 1G12 in inducing selective IL-2 signaling and supporting Treg persistence in vivo, so that 2,000 engineered Tregs completely prevented diabetes. To ensure expression of tethered 3A10 in Tregs, we inserted the construct into the Foxp3 locus, preventing its activation of autoreactive T cells. These results demonstrate a strategy to selectively enhance the survival and function of therapeutic Tregs using a tethered autocrine orthogonal IL-2 system. Funding Sources Breakthrough T1D 5-COE-2019-860-S-B Topic Categories Therapeutic Approaches to Autoimmunity (THER)