CD4+ CD8αα+ double-positive intraepithelial T lymphocytes (DP T cells), a newly characterized subset of intraepithelial T cell, has been reported to contribute to local immunosuppression. However, whether DP T cells are present in Helicobacter. pylori-induced gastritis, and their relationship with disease prognosis remain to be elucidated. In this study, We established chronic gastritis models through Helicobacter felis (H. felis) infection. Gastric infiltrating lymphocytes were isolated from H. felis-induced gastritis mice and analyzed by flow cytometry. Our results suggest that DP T cells frequency in H. felis-induced gastritis mice was higher than the uninfected mice. Gastric DP T cells derived from lamina propria cells, which distributed in the gastric epithelial layer. We found that DP T cells exhibited anti-inflammatory function. In vitro, DP T cells inhibited the maturation of dendritic cells and the proliferation of CD4+ T cell. The elimination of CD4+CD8αα+ T cells in vivo resulted in severe gastritis and a reduction of H. felis load. Additionally, vaccine with silk fibroin as delivery systems enhanced vaccine efficacy by reducing DP T cells. We demonstrated that DP T cells performed an immunosuppressive role in Helicobacter felis-induced gastritis. These findings revealed that DP T cells may affect the prognosis of the disease and the vaccine efficacy.
