Toll-Like Receptor 8-Mediated Reversal of CD4 ⁺ Regulatory T Cell Function

TLDR

CD4+ regulatory T cells suppress immune responses, but their regulation remains poorly understood. The study aims to link Toll-like receptor 8 signaling to the reversal of Treg cell function using synthetic and natural ligands. TLR8 ligands activate TLR8‑MyD88‑IRAK4 signaling within Treg cells to reverse their suppressive activity. The reversal of Treg function was independent of dendritic cells, required functional TLR8‑MyD88‑IRAK4 signaling, and enhanced anti‑tumor immunity in tumor‑bearing mice, suggesting a role for TLR8 in controlling immune responses to cancer and other diseases.

Abstract

CD4+ regulatory T (Treg) cells have a profound ability to suppress host immune responses, yet little is understood about how these cells are regulated. We describe a mechanism linking Toll-like receptor (TLR) 8 signaling to the control of Treg cell function, in which synthetic and natural ligands for human TLR8 can reverse Treg cell function. This effect was independent of dendritic cells but required functional TLR8-MyD88-IRAK4 signaling in Treg cells. Adoptive transfer of TLR8 ligand-stimulated Treg cells into tumor-bearing mice enhanced anti-tumor immunity. These results suggest that TLR8 signaling could play a critical role in controlling immune responses to cancer and other diseases.