Immunological pathogenesis of inflammatory bowel disease: focus on tissue resident memory T cells

Tissue-resident memory T (T_RM) cells are a type of tissue-restricted memory T cells with terminal differentiation and a memory function. They exist in mucosal tissues for a long period. In the absence of disease, T_RM cells promote essential inflammation, which reinforces the intestinal barrier and prevents bacterial translocation. However, in inflammatory or autoimmune environments, T_RM cells are hyperactivated. This heightened activity causes the host to release excessive pro-inflammatory cytokines, resulting in local immune imbalances and damage to the barrier, ultimately leading to tissue lesions. Numbers of studies have shown that T_RM cells play a crucial role in the development and progression of inflammatory bowel disease (IBD), suggesting that targeted regulation of T_RM cells homeostasis may be an important strategy for treating IBD. Here, we compiled the existing understanding of the role of T_RM cells in IBD, with particular emphasis on the associated mechanisms and approaches for targeting T_RM cells in IBD treatment. This review will serve as a foundation for a better understanding of IBD development and enhancing the effectiveness of clinical treatments for IBD.