Gatekeeping the Gut; Dynamics and interactions of tissue-resident memory T cells within the intestine

Abstract

The immune system can create memory of what it has seen. This feature is of critical importance, as it enables the immune system to respond to reinfection at a faster rate. The most prevalent type of memory cells remain in non-lymphoid tissue locally, through tissue-resident memory T (TRM) cells. Unlike circulatory T cells, TRM cells reside in tissues for a long period of time, which enables them to eAectively combat repetitive infections in many tissues. One of the tissues with a great number of TRM cells is the gut. The unique position of gut-homing TRM cells diAer from other TRM cells in their interactions with the gut microbiota and their excreted metabolites. In this paper, we review the development and dynamics of gut TRM cells. We evaluate the reliability of CD69 and CD103 as phenotypic markers for identifying TRM cells in the gut of both humans and mice, while also addressing key limitations associated with their use. Furthermore, we investigate the influence of the gut microbiota and antigenic stimuli on the recruitment and establishment of gut TRM cells, with implications for the development of a functionally mature mucosal immune system.