Advancements in the characterization of tissue resident memory T cells in skin disease.

The newly discovered subset of memory T cells, tissue resident memory T (TRM) cells, reside in peripheral tissues for a long time, contributing to a rapid immune response and constituting the first line of defense when pathogens invade cells. Tissue resident memory T cells have unique transcriptome characteristics, and their presence in peripheral tissues is regulated by many factors. TRM cells residing in different tissues often express different surface markers. In addition to CD8+ and CD4+ T cells, which are the best-characterized T cells, Treg cells and various innate T cells can reside in nonlymphoid tissues. Many recent studies have shown that tissue resident memory T cells play indispensable roles in tumor immunity and allergic diseases. This paper reviews the differentiation, regulation, variety and function of TRM cells and the roles they play in skin diseases, including cutaneous melanoma and psoriasis.