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Fung, Vivian

University of British Columbia

In type 1 diabetes (T1D), autoreactive T cells mediate the destruction of insulin-producing islet beta cells, leading to an inability to regulate blood glucose. If the patient cannot control their disease, the prolonged insulin deficiency will cause chronic hyperglycaemia, which may result in blindness and organ failure. Autoreactive T cells initiate pathogenesis upon recognition of islet-derived peptides presented by major histocompatibility complexes (MHC). In healthy individuals, these autoimmune reactions are normally suppressed by regulatory T cells (Tregs), but people with T1D are thought to have dysfunctional Tregs. Potential therapeutic strategies for T1D designed to minimize autoimmunity include pharmacological T cell inhibition and/or infusion of polyclonal Tregs. However, these strategies are non-specific and may have limited effects on beta-cell-directed autoimmunity. Research using the non-obese diabetic (NOD) mouse model has shown cell therapy with Tregs bearing a transgenic T cell receptor (TCR) specific towards an islet-derived antigen could be superior to prevent and/or reverse T1D. However, limitations of TCR-engineered Tregs include mispairing with the chains of the endogenous TCR and potential cross-reactivity with other peptides. I sought to overcome these limitations by engineering Tregs utilizing chimeric antigen receptor (CAR) technology. Advantages of CARs include high-affinity antibody-based interactions and self-contained co-stimulation. I studied two CARs in the NOD mouse model: the 1B2 CAR (specific towards insulin B₁₀-₂₃ complexed to MHC Class II I-Ag⁷) and the FS1 CAR (specific towards p63:I-Ag⁷). I validated CAR specificity by testing their binding capacity to peptide:I-Ag⁷ tetramers. Proliferation and suppression assays were conducted to compare the function of CAR Tregs versus polyclonal Tregs. I found when IB2 or FS1 CAR Tregs were cultured with splenocytes pulsed with relevant peptide, they proliferated and upregulated activation markers. FS1 CAR Tregs mediated enhanced suppression of T cell proliferation, and both 1B2 and FS1 CAR Tregs suppressed cytokine production more efficiently than polyclonal Tregs. Together, these proof-of-concept data show that T1D-peptide-MHC II-specific CARs can be used to re-direct the specificity of Tregs. These data set the stage for future testing in in vivo models of T1D and the development of similar therapeutic strategies for use in people with T1D.

Text

2023-02-28

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/79286

Experimental Medicine

University of British Columbia

UBCV

http://creativecommons.org/licenses/by-nc-nd/4.0/