Project description:Regulatory T cells (Tregs) use a distinct TCR repertoire and are more self-reactive compared with conventional T cells. However, the extent to which TCR affinity regulates the function of self-reactive Tregs is largely unknown. In this study, we used a two-TCR model to assess the role of TCR affinity in Treg function during autoimmunity. We observed that high- and low-affinity Tregs were recruited to the pancreas and contributed to protection from autoimmune diabetes. Interestingly, high-affinity cells preferentially upregulated the TCR-dependent Treg functional mediators IL-10, TIGIT, GITR, and CTLA4, whereas low-affinity cells displayed increased transcripts for Areg and Ebi3, suggesting distinct functional profiles. The results of this study suggest mechanistically distinct and potentially nonredundant roles for high- and low-affinity Tregs in controlling autoimmunity.
Project description:Regulatory T cells (Tregs) are promising cellular therapies to induce immune tolerance in organ transplantation and autoimmune disease. The success of chimeric antigen receptor (CAR) T-cell therapy for cancer has sparked interest in using CARs to generate antigen-specific Tregs. Here, we compared CAR with endogenous T cell receptor (TCR)/CD28 activation in human Tregs. Strikingly, CAR Tregs displayed increased cytotoxicity and diminished suppression of antigen-presenting cells and effector T (Teff) cells compared with TCR/CD28 activated Tregs. RNA sequencing revealed that CAR Tregs activate Teff cell gene programs. Indeed, CAR Tregs secreted high levels of inflammatory cytokines, with a subset of FOXP3+ CAR Tregs uniquely acquiring CD40L surface expression and producing IFNγ. Interestingly, decreasing CAR antigen affinity reduced Teff cell gene expression and inflammatory cytokine production by CAR Tregs. Our findings showcase the impact of engineered receptor activation on Treg biology and support tailoring CAR constructs to Tregs for maximal therapeutic efficacy.
Project description:Reprogramming autoreactive CD4⁺ effector T (Teff) cells into immunosuppressive regulatory T (Treg) cells represents a promising strategy for treating established autoimmune diseases. However, the stability and function of such reprogrammed Tregs under inflammatory conditions remain unclear. Here, we show that demethylation of core Treg identity genes in Teff cells yields lineage-stable Effector T cell Reprogrammed Tregs (ER-Tregs). A single adoptive transfer of ER-Tregs not only prevents autoimmune neuroinflammation in mice when given before disease onset but also arrests its progression when administered after onset. Compared to Foxp3‑overexpressing Teff cells, induced Tregs from naïve precursors, and endogenous Tregs, ER‑Tregs provide superior protection against autoimmune neuroinflammation. This enhanced efficacy stems from their inherited autoantigen specificity and selectively preserved effector‑cell transcriptional programs, which together bolster their fitness in inflammatory environments and enhance their suppressive capacity. Our results establish epigenetic reprogramming of autoreactive Teff cells as an effective approach to generate potent, stable Tregs for the treatment of refractory autoimmune conditions.
Project description:Recent findings suggest that undifferentiated, stem-like, antigen specific T cells serve as an important long-term reservoir for autoimmune CD8 T cell responses. However, it is still unclear whether CD4 T cells exhibit a similar differentiation trajectory culminating in terminal differentiation, acquisition of an exhausted phenotype, and loss of stemness and function. We analyzed islet infiltrating T cells by scRNAseq and flow cytometry and found that while CD4 T cells in autoimmune diabetes share many features of exhaustion with CD8 T cells, expression patterns of inhibitory receptors are distinct in autoimmune T cells compared to T cells in chronic LCMV infection.
Project description:CD8+ T cell-mediated recognition of peptide-major histocompatibility complex class I (pMHCI) molecules involves cooperative binding of the T cell receptor (TCR), which confers antigen specificity, and the CD8 coreceptor, which stabilizes the TCR/pMHCI complex. Earlier work has shown that the sensitivity of antigen recognition can be regulated in vitro by altering the strength of the pMHCI/CD8 interaction. Here, we characterized two CD8 variants with moderately enhanced affinities for pMHCI, aiming to boost antigen sensitivity without inducing non-specific activation. Expression of these CD8 variants in model systems preferentially enhanced pMHCI antigen recognition in the context of low-affinity TCRs. A similar effect was observed using primary CD4+ T cells transduced with cancer-targeting TCRs. The introduction of high-affinity CD8 variants also enhanced the functional sensitivity of primary CD8+ T cells expressing cancer-targeting TCRs, but comparable results were obtained using exogenous wild-type CD8. Specificity was retained in every case, with no evidence of reactivity in the absence of cognate antigen. Collectively, these findings highlight a generically applicable mechanism to enhance the sensitivity of low-affinity pMHCI antigen recognition, which could augment the therapeutic efficacy of clinically relevant TCRs.
Project description:Recent findings suggest that undifferentiated, stem-like, antigen specific T cells serve as an important long-term reservoir for autoimmune CD8 T cell responses. However, it is still unclear whether CD4 T cells exhibit a similar differentiation trajectory culminating in terminal differentiation, acquisition of an exhausted phenotype, and loss of stemness and function. We analyzed islet infiltrating T cells in 8- and 16-week old NOD mice by scRNAseq and flow cytometry and found that while CD4 T cells in autoimmune diabetes share many features of exhaustion with CD8 T cells, expression patterns of inhibitory receptors are distinct in autoimmune T cells compared to T cells in chronic LCMV infection.
Project description:Seropositivity for autoantibodies against islet autoantigens is associated with the development of autoimmune type 1 diabetes and B cell targeted therapies are effective in both mouse models and in patients who are affected by or at risk for autoimmune type 1 diabetes. The role of B cell receptor affinity in autoimmune type 1 diabetes is unclear. Here, we employed single cell RNA sequencing to define the relationship between B cell receptor affinity for insulin and B cell phenotype during disease development using immunoglobulin heavy chain (VH125) transgenic mouse model (VH125.NOD) in which insulin binding B cells lose self-tolerance, becoming activated during development of autoimmmun type 1 diabetes.
Project description:Fluorochrome-conjugated peptide-MHC (pMHC) multimers are commonly used in combination with flow cytometry for direct ex vivo visualization and characterization of Ag-specific T cells, but these reagents can fail to stain cells when TCR affinity and/or TCR cell-surface density are low. pMHC multimer staining of tumor-specific, autoimmune, or MHC class II-restricted T cells can be particularly challenging, as these T cells tend to express relatively low-affinity TCRs. In this study, we attempted to improve staining using anti-fluorochrome unconjugated primary Abs followed by secondary staining with anti-Ab fluorochrome-conjugated Abs to amplify fluorescence intensity. Unexpectedly, we found that the simple addition of an anti-fluorochrome unconjugated Ab during staining resulted in considerably improved fluorescence intensity with both pMHC tetramers and dextramers and with PE-, allophycocyanin-, or FITC-based reagents. Importantly, when combined with protein kinase inhibitor treatment, Ab stabilization allowed pMHC tetramer staining of T cells even when the cognate TCR-pMHC affinity was extremely low (KD >1 mM) and produced the best results that we have observed to date. We find that this inexpensive addition to pMHC multimer staining protocols also allows improved recovery of cells that have recently been exposed to Ag, improvements in the recovery of self-specific T cells from PBMCs or whole-blood samples, and the use of less reagent during staining. In summary, Ab stabilization of pMHC multimers during T cell staining extends the range of TCR affinities that can be detected, yields considerably enhanced staining intensities, and is compatible with using reduced amounts of these expensive reagents.