Figure 2
From: Microbiota in T-cell homeostasis and inflammatory diseases
Microbiota mediates T-cell differentiation in homeostatic or pathogenic conditions. In mice under germ-free (GF) conditions, Bacteroides fragilis restores the development of the Th1-associated immune response through a bacterial product, polysaccharide A (PSA)-dependent pathway, while in mice under specific pathogen-free (SPF) conditions, PSA derived from B. fragilis induces Treg cell accumulation. Segmented filamentous bacteria (SFB) induces a Th17 immune response through adenosine 5′-triphosphate (ATP) production or serum amyloid A (SAA) produced by innate cells. Clostridium sp. promotes Treg cells through short-chain fatty acid (SCFA) production. Antigen-presenting cells (APCs) activated by cognate bacterial antigens could facilitate the generation of tissue-specific T cells derived from systemic T cells in a specific tissue environment.
