Toll-like receptors (TLRs) are widely expressed and play an essential role in the activation of innate immune cells. However, certain TLRs are also expressed on T cells, and TLR ligands can directly modulate T cell functions. Here, we discuss findings indicating that T cells directly respond to Heat Shock Protein (HSP) 60, a self molecule, or to the HSP60-derived peptide, p277, via a TLR2-dependent mechanism. HSP60 has been considered to be a "danger signal" for the immune system because of its ability to induce proinflammatory phenotypes in innate immune cells - in this case via TLR4activation; nevertheless, TLR2 engagement by HSP60 on T cells can lead to resolution of inflammation by up-regulating the suppression function of regulatory T cells and shifting the resulting cytokine secretion balance toward a Th2 phenotype. Moreover, T cell TLR4engagement by LPS leads to up-regulation of suppressor of cytokine signaling 3 expression and consequently down-regulates T cell chemotaxis. Thus, TLR2 and TLR4 activation can contribute to both induction and termination of effector immune responses by controlling the activities of both innate and adaptive immune cells. © 2013 Zanin-Zhorov and Cohen.
CITATION STYLE
Zanin-Zhorov, A., & Cohen, I. R. (2013). Signaling via TLR2 and TLR4 directly down-regulates T cell effector functions: The regulatory face of danger signals. Frontiers in Immunology. https://doi.org/10.3389/fimmu.2013.00211
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