Cl097, a Tlr7/8 Ligand, Inhibits TLR-4-Dependent Activation of Irak-M and BCL-3 Expression

Prolonged or repeated stimulation of Toll-like receptor (TLR) 4 leads to hyporesponsiveness of monocyte-derived macrophages, which seems to be a hallmark of immunosuppression related to sepsis and cancer. Two negative regulators of TLR-4 signaling are IL-1 receptor-associated kinase M and B-cell leukemia 3. Here, we demonstrate that the expression of both proteins is inhibited when the TLR-7/TLR-8 agonist CL097 is added to monocyte cultures despite costimulation with the TLR-4 agonist LPS or hyaluronic acid. Reduction of IL-1 receptor-associated kinase M and B-cell leukemia 3 was paralleled by a significant increased cytokine induction of TNF-alpha, IL-10, and IL-12 observed after intracellular and extracellular TLR stimulation. In ex vivo stimulated whole blood of patients who have prolonged sepsis or metastatic cancer, TLR-7/TLR-8 agonists retained their ability of increased stimulation of TNF-alpha. These data might add to the understanding of sepsis and cancer-associated immune suppression in men.