Tissue-resident memory T cells in diseases and therapeutic strategies

Tissue-resident memory T (T_RM) cells are crucial components of the immune system that provide rapid, localized responses to recurrent pathogens at mucosal and epithelial barriers. Unlike circulating memory T cells, T_RM cells are located within peripheral tissues, and they play vital roles in antiviral, antibacterial, and antitumor immunity. Their unique retention and activation mechanisms, including interactions with local epithelial cells and the expression of adhesion molecules, enable their persistence and immediate functionality in diverse tissues. Recent advances have revealed their important roles in chronic inflammation, autoimmunity, and cancer, illuminating both their protective and their pathogenic potential. This review synthesizes current knowledge on T_RM cells' molecular signatures, maintenance pathways, and functional dynamics across different tissues. We also explore the interactions of T_RM cells with other immune cells, such as B cells, macrophages, and dendritic cells, highlighting the complex network that underpins the efficacy of T_RM cells in immune surveillance and response. Understanding the nuanced regulation of T_RM cells is essential for developing targeted therapeutic strategies, including vaccines and immunotherapies, to enhance their protective roles while mitigating adverse effects. Insights into T_RM cells' biology hold promise for innovative treatments for infectious diseases, cancer, and autoimmune conditions.