T cell receptor precision editing of regulatory T cells for celiac disease

Celiac disease, a gluten-sensitive enteropathy, demonstrates a strong human leukocyte antigen (HLA) association, with more than 90% of patients carrying the HLA-DQ2.5 allotype. No therapy is available for the condition except for a lifelong gluten-free diet. To address this gap, we explored the therapeutic potential of regulatory T cells (T_regs). By orthotopic replacement of T cell receptors (TCRs) through homology-directed repair, we generated gluten-reactive HLA-DQ2.5-restricted CD4⁺ engineered (e) T effector cells (T_effs) and eT_regs and performed in vivo experiments in HLA-DQ2.5 transgenic mice. Of five validated TCRs, TCRs specific for two immunodominant and deamidated gluten epitopes (DQ2.5-glia-α1a and DQ2.5-glia-α2) were selected for further evaluation. CD4⁺ eT_effs exposed to deamidated gluten through oral gavage colocalized with dendritic and B cells in the Peyer's patches and gut-draining lymph nodes and specifically migrated to the intestine. The suppressive function of human eT_regs correlated with high TCR functional activity. eT_regs specific for one epitope suppressed the proliferation and gut migration of CD4⁺ eT_effs specific for the same and the other gluten epitope, demonstrating bystander suppression. The suppression requires an antigen-specific activation of eT_regs given that polyclonal T_regs failed to suppress CD4⁺ eT_effs. These findings highlight the potential of gluten-reactive eT_regs as a therapeutic for celiac disease.