Figure 2:

Activation, residence, and response of T cells at barrier sites. (A) Surface molecules and transcription factors invovled in recruitment and retention in either the intestinal or the skin milieu. (B) Recognition of microbiota-derived antigens and other signals that modulate T-cell activation derived from the barrier environment. Depicted are different T-cell-intrinsic and -extrinsic signals sourced by the microbiota, divided in core and accessory mediators of T-cell activation. Integration of all these signals leads to the final T-cell response. Highlighted in blue are receptors that can directly bind microbial components or metabolites. (C) Main transcription factors, surface receptors, and cytokines that influence the spectrum of responses from barrier T cells into tolerogenic, pathogenic, protective, or reparative programs. Placements are not necessarily exclusive, as marker and cytokine patterns can be shared depending on the kind of T cell and the type and time of response. *Expressed only in murine cells.