Tolerance Induction in Diabetogenic BDC-2.5 T cells

CD4 T cells play a critical role in promoting the development of autoimmunity in Type 1 Diabetes (T1D). The diabetogenic CD4 T cell clone BDC-2.5, originally isolated from a non-obese diabetic (NOD) mouse, has been widely used to study the contribution of autoreactive CD4 T cells and relevant antigens to autoimmune diabetes. Recent work from our lab has shown that the antigen for BDC-2.5 T cells is a hybrid insulin peptide (2.5HIP) consisting of an insulin C-peptide fragment fused to a peptide from chromogranin A (ChgA), and that endogenous 2.5HIP-reactive T cells are major contributors to autoimmune pathology in NOD mice. The objective of this study was to determine if poly(lactide-co-glycolide) (PLG) nanoparticles (NPs) loaded with the 2.5HIP antigen (2.5HIP-PLG) can tolerize BDC-2.5 T cells. Infusion of 2.5HIP-PLG NPs was found to prevent diabetes in an adoptive transfer model by impairing the ability of BDC-2.5 T cells to produce pro-inflammatory cytokines through induction of anergy, leading to an increase in the ratio of Foxp3+ regulatory T cells to IFN-γ+ effector T cells. This work is the first to use a hybrid insulin peptide, or any neoepitope, to re-educate diabetogenic T cells and may have significant implications for the development of an antigen-specific therapy for T1D patients. Sequencing of FACS-sorted BDC-2.5 TCR-transgenic, CD4-positive, Foxp3-negative (GFP-negative) effector T cells (Teffs) was performed in order to determine the mechanisms of tolerance induction. Activated BDC-2.5 T cells were adoptively transferred into NOD.scid mice and Teffs were sorted from spleen/lymph nodes of 2.5HIP-PLG treated or untreated mice (pooled from 4 mice per group) 6 days after T cell transfer. RNA-Seq data are from 1 experiment without replicates. An up-regulation of anergy related genes in tolerized Teffs was found.