Tolerance induced by the lipopeptide Pam3Cys is due to ablation of IL-1R-associated kinase-1.

Stimulation of the human monocytic cell line Mono Mac 6 with the synthetic lipopeptide (S)-(2,3-bis(palmitoyloxy)-(2RS)-propyl)-N-palmitoyl-(R)-Cys-(S)-Ser(S)-Lys(4)-OH, trihydrochloride (Pam(3)Cys) at 10 microg/ml induces a rapid expression of the TNF gene in a TLR2-dependent fashion. Preculture of the cells with Pam(3)Cys at 1 microg/ml leads to a reduced response after subsequent stimulation with Pam(3)Cys at 10 microg/ml, indicating that the cells have become tolerant to Pam(3)Cys. The CD14 and TLR2 expression is not decreased on the surface of the tolerant cells, but rather up-regulated.

IFN-alpha induces the human IL-10 gene by recruiting both IFN regulatory factor 1 and Stat3.

The anti-inflammatory cytokine IL-10 can be induced by type I IFNs, but the molecular mechanisms involved have remained elusive. With in silico analysis of the human IL-10 promoter we identified a module consisting of an IFN regulatory factor 1 (IRF-1) site and a Stat3 site. We demonstrate that IFN-alpha will induce the binding of IRF-1 and Stat3 to the respective motifs.