Differential but direct abolishment of human regulatory T cell suppressive capacity by various TLR2 ligands

HH Oberg, TTH Ly, S Ussat, T Meyer… - The Journal of …, 2010 - journals.aai.org
HH Oberg, TTH Ly, S Ussat, T Meyer, D Kabelitz, D Wesch
The Journal of Immunology, 2010journals.aai.org
Abstract CD4+ CD25 high regulatory T cells (Tregs) control cellular immune responses and
maintain peripheral tolerance. We investigated whether TLR2 ligands are able to abrogate
Treg-induced suppression in humans based on different reports about effects of triacylated
lipopeptide Pam 3 CSK4 in mice. Pretreatment of human Tregs with a mixture of TLR2
ligands Pam 2 CSK4, FSL-1, and Pam 3 CSK4 reduced the Treg-mediated suppression of
CD4+ CD25− responder T cells in the majority of the analyzed donors. Differential effects of …
Abstract
CD4+ CD25 high regulatory T cells (Tregs) control cellular immune responses and maintain peripheral tolerance. We investigated whether TLR2 ligands are able to abrogate Treg-induced suppression in humans based on different reports about effects of triacylated lipopeptide Pam 3 CSK4 in mice. Pretreatment of human Tregs with a mixture of TLR2 ligands Pam 2 CSK4, FSL-1, and Pam 3 CSK4 reduced the Treg-mediated suppression of CD4+ CD25− responder T cells in the majority of the analyzed donors. Differential effects of individual TLR2 ligands are explained by usage of different TLR2 heterodimers in the recognition of Pam 2 CSK4, FSL-1, and Pam 3 CSK4. In contrast to the murine system, TLR2 ligand-mediated abrogation of human Treg function was not associated with a downregulation of FoxP3 transcription factor. Furthermore, our results excluded an effect of TLR2 ligands on granzyme A/B release by human Tregs as a potential mechanism to abolish Treg-mediated suppression. Our data suggest that a downregulation of p27 Kip1 and restoration of Akt phosphorylation in human Tregs pretreated with TLR2 ligands result in a reversal of suppression on responder T cells. Moreover, our data indicate that a mixture of TLR2 ligands can be used to modulate human Treg activity.
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