Regulation of tissue-resident memory T cells by the Microbiota

Abstract

Resident memory T cells (Trms) predominantly reside within tissue and are critical for providing rapid protection against invasive viruses, fungi and bacteria. Given that tissues are heavily impacted and shaped by the microbiota, it stands to reason that Trms are also influenced by the microbiota that inhabits barrier sites. The influence of the microbiota is largely mediated by microbial production of metabolites which are crucial to the immune response to both viral infection and cancerous tumors. In addition to the effects of metabolites, antigens derived from the microbiota can activate T cell responses. While microbiota-specific T cells may assist in tissue repair, control of infection and anti-tumor immunity, the actual 'memory' potential of these cells remains unclear. Here, we hypothesize that memory responses to antigens from the microbiota must be 'licensed' by inflammatory signals activated by invasion of the host by microorganisms.

Immunization of preterm infants: current evidence and future strategies to individualized approaches

“…The processes of generating microbiota-specific Trm T cells have not been thoroughly elucidated in early life immunity yet [reviewed in 121]. Given the high vulnerability of the neonatal microbiome for disturbance by environmental factors (as discussed below), the proposed function of Trm T cells to “remember” benign interactions with the microbiome as a preventive measure against repetitive or sustained inflammation [ 121 ] might also be affected. In the context of preterm birth, the lack of IgA from breast milk and maternal IgG antibodies transferred through the placenta may also result in reduced shaping of Trm T cells after birth [ 122 ].…”

The Memory T Cell “Communication Web” in Context with Gastrointestinal Disorders—How Memory T Cells Affect Their Surroundings and How They Are Influenced by It

“…The large intestine harbours multiple variants of commensal bacteria, viruses, fungi, and other types of microorganisms that are summarized as the intestinal microbiota. Their presence is crucial for the host by not only providing a physical barrier against harmful trespassers but also by producing metabolites that are useful to both the intestinal epithelium and the immune system [ 82 ]. Disturbances in the microbiota composition and homeostasis are widely reported to contribute to gut-related disorders.…”

Regulation of T cell repertoires by commensal microbiota

“…In addition to the regulation of IL-7 bioavailability by tissue-resident ILCs and intestinal epithelial cells, microbial metabolites can directly influence the generation and maintenance of memory CD8 + T cells that are generated upon viral and microbial infection, thereby influencing T cell repertoires systemically or at local tissues such as the intestine ( Overacre-Delgoffe and Hand, 2022 ). Microbial production of SCFAs enhance virus-specific long-lived memory CD8 + T cells.…”

“…Microbial production of SCFAs enhance virus-specific long-lived memory CD8 + T cells. Therefore, memory T cell formation is defective in mice absent of commensal microbiota ( Overacre-Delgoffe and Hand, 2022 ). Conversely, high-fiber diets augment memory T cell differentiation.…”