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 (Tregs). 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 (Teffs) and eTregs 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+ eTeffs 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 eTregs correlated with high TCR functional activity. eTregs specific for one epitope suppressed the proliferation and gut migration of CD4+ eTeffs specific for the same and the other gluten epitope, demonstrating bystander suppression. The suppression requires an antigen-specific activation of eTregs given that polyclonal Tregs failed to suppress CD4+ eTeffs. These findings highlight the potential of gluten-reactive eTregs as a therapeutic for celiac disease.