Creating a novel mouse model to investigate the role of peripheral regulatory T cells in oral tolerance to gluten in Celiac disease

Celiac disease (CeD) is a multifaceted intestinal disorder with autoimmune characteristics, triggered by T cell recognition of gluten peptides presented in the context of HLA-DQ8, leading to inflammation. While the role of regulatory T cells (Tregs) in immune modulation is well-established, the specific contributions of thymic Tregs (tTregs) versus peripheral Tregs (pTregs) in mucosal tolerance remain uncertain. This study aims to elucidate the role of pTregs in gluten-induced inflammation using a novel mouse model. HLA-DQ8/Ab knockout (Ab ko) mice were bred with CNS-deficient (CNS -/-) mice, which lack the capacity to generate pTregs. Both HLA-DQ8/Ab ko and HLA-DQ8/Ab ko/CNS -/- mice were immunized with PT-Gliadin, and CD4+ T cells were sorted and transferred into HLA-DQ8/Ab ko/TCRαKO recipient mice. These recipients were fed a gluten-free or gluten-enriched diet for 12 weeks before euthanasia. Inflammation and immune cell profiles in small intestinal tissues and intraepithelial lymphocytes (IELs) were assessed. CNS -/- mice on a gluten-enriched diet exhibited significant weight loss and increased fecal lipocalin levels, indicative of inflammation. Analysis revealed a reduction in CD4+ T cells and Tregs and an increase in CD8+ T cells in intestinal tissues and IELs. However, activation markers of lymphocytes did not significantly differ between the groups. This adoptive transfer model provides a robust platform for investigating the role of pTregs in gluten tolerance and Celiac disease inflammation. It highlights the impact of pTreg deficiency on intestinal immune homeostasis and offers a valuable tool for future therapeutic studies.