TY - JOUR
T1 - Gi-protein-dependent inhibition of IL-12 production is mediated by activation of the phosphatidylinositol 3-kinase-protein 3 kinase B/Akt pathway and JNK
AU - La Sala, Andrea
AU - Gadina, Massimo
AU - Kelsall, Brian L.
PY - 2005/9/1
Y1 - 2005/9/1
N2 - Ligands for certain Giprotein-coupled receptors (GiPCRs) potently inhibit the production of IL-12 by human monocytes. We addressed the intracellular signaling mechanisms by which this occurs using primary human cells. Stimulation with the GiPCR ligands C5a and 1-deoxy-1-[6-[(3-iodophenyl) methyl]amino]-9H-purine-9-y1]-N-methyl-β-D-ribofuranuronamide (IB-MECA) blocked the production of IL-12 p70 by human monocytes stimulated with LPS and IFN-γ. In addition, C5a reduced the expression of mRNA for IL-12 p35, p40, IL-23 p19, and IL-27 p28. This effect was due neither to a down-regulation of TLR4 or IFN-γ receptor on the cell surface nor to interference with IFN-γ signaling, because IFN-γ-induced up-regulation of HLA-DR and CD40 were unaffected. C5a or IB-MECA activated the PI3K/Akt signaling pathway and induced the phosphorylation of the MAPK p38, ERK, and JNK. Inhibition of the PI3K/Akt signaling pathway with wortmannin or an inhibitor of Akt activity, and inhibition of JNK but not ERK prevented IL-12 and IL-23 suppression by C5a. These data extend observations on IL-12 suppression by C5a to IL-23 and IL-27, and are the first to demonstrate the intracellular signaling events leading to IL-12 and IL-23 inhibition after GiPCR activation.
AB - Ligands for certain Giprotein-coupled receptors (GiPCRs) potently inhibit the production of IL-12 by human monocytes. We addressed the intracellular signaling mechanisms by which this occurs using primary human cells. Stimulation with the GiPCR ligands C5a and 1-deoxy-1-[6-[(3-iodophenyl) methyl]amino]-9H-purine-9-y1]-N-methyl-β-D-ribofuranuronamide (IB-MECA) blocked the production of IL-12 p70 by human monocytes stimulated with LPS and IFN-γ. In addition, C5a reduced the expression of mRNA for IL-12 p35, p40, IL-23 p19, and IL-27 p28. This effect was due neither to a down-regulation of TLR4 or IFN-γ receptor on the cell surface nor to interference with IFN-γ signaling, because IFN-γ-induced up-regulation of HLA-DR and CD40 were unaffected. C5a or IB-MECA activated the PI3K/Akt signaling pathway and induced the phosphorylation of the MAPK p38, ERK, and JNK. Inhibition of the PI3K/Akt signaling pathway with wortmannin or an inhibitor of Akt activity, and inhibition of JNK but not ERK prevented IL-12 and IL-23 suppression by C5a. These data extend observations on IL-12 suppression by C5a to IL-23 and IL-27, and are the first to demonstrate the intracellular signaling events leading to IL-12 and IL-23 inhibition after GiPCR activation.
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M3 - Article
C2 - 16116186
AN - SCOPUS:23844434887
VL - 175
SP - 2994
EP - 2999
JO - Journal of Immunology
JF - Journal of Immunology
SN - 0022-1767
IS - 5
ER -