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

J Immunol. 2004 Aug 15;173(4):2736-45. doi: 10.4049/jimmunol.173.4.2736.

Abstract

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. Analysis of the NF-kappaB binding in Pam(3)Cys-tolerant cells shows a failure to mobilize NF-kappaB-p50p65 heterodimers, while NF-kappaB-p50p50 homodimers remain unchanged. Pam(3)Cys-tolerant cells showed neither IkappaBalpha-Ser(32) phosphorylation nor IkappaBalpha degradation but MyD88 protein was unaltered. However, IRAK-1 protein was absent in Pam(3)Cys-induced tolerance, while IRAK-1 mRNA was still detectable at 30% compared with untreated cells. In contrast, in LPS-tolerized cells, p50p50 homodimers were induced, IRAK-1 protein level was only partially decreased, and p50p65 mobilization remained intact. It is concluded that in Mono Mac 6 monocytic cells, inhibition of IRAK-1 expression at the mRNA and protein levels is the main TLR-2-dependent mechanism responsible for Pam(3)Cys-induced tolerance, but not for TLR-4-dependent LPS-induced tolerance.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adaptor Proteins, Signal Transducing
  • Antigens, Differentiation / immunology
  • Antigens, Differentiation / metabolism
  • Blotting, Western
  • Cell Line
  • Fluorescent Antibody Technique
  • Humans
  • I-kappa B Proteins / immunology
  • I-kappa B Proteins / metabolism
  • Immune Tolerance*
  • Interleukin-1 Receptor-Associated Kinases
  • Lipopolysaccharide Receptors / immunology
  • Lipopolysaccharide Receptors / metabolism
  • Lipopolysaccharides / immunology
  • Lipopolysaccharides / pharmacology
  • Lipoproteins / immunology
  • Lipoproteins / pharmacology*
  • Membrane Glycoproteins / immunology
  • Membrane Glycoproteins / metabolism
  • Monocytes / drug effects*
  • Monocytes / immunology
  • Myeloid Differentiation Factor 88
  • NF-KappaB Inhibitor alpha
  • NF-kappa B / immunology
  • NF-kappa B / metabolism
  • Protein Kinases / drug effects*
  • Protein Kinases / immunology
  • Protein Kinases / metabolism
  • Receptors, Cell Surface / immunology
  • Receptors, Cell Surface / metabolism
  • Receptors, Immunologic / immunology
  • Receptors, Immunologic / metabolism
  • Reverse Transcriptase Polymerase Chain Reaction
  • Signal Transduction / immunology
  • Toll-Like Receptor 2
  • Toll-Like Receptor 4
  • Toll-Like Receptors
  • Transfection
  • Tumor Necrosis Factor-alpha / drug effects*
  • Tumor Necrosis Factor-alpha / immunology
  • Tumor Necrosis Factor-alpha / metabolism

Substances

  • Adaptor Proteins, Signal Transducing
  • Antigens, Differentiation
  • I-kappa B Proteins
  • Lipopolysaccharide Receptors
  • Lipopolysaccharides
  • Lipoproteins
  • MYD88 protein, human
  • Membrane Glycoproteins
  • Myeloid Differentiation Factor 88
  • NF-kappa B
  • NFKBIA protein, human
  • Receptors, Cell Surface
  • Receptors, Immunologic
  • TLR2 protein, human
  • TLR4 protein, human
  • Toll-Like Receptor 2
  • Toll-Like Receptor 4
  • Toll-Like Receptors
  • Tumor Necrosis Factor-alpha
  • NF-KappaB Inhibitor alpha
  • Protein Kinases
  • Interleukin-1 Receptor-Associated Kinases