title: GM-CSF priming of human monocytes is dependent on ERK1/2 activation.
abstract: The ability to augment monocyte functions such as TNF-alpha-producing capacities confers a high immunostimulating potential to GM-CSF. In the present investigation, the mechanism of the GMCSF-mediated enhancement of monocyte cytokine production was analysed with regard to the involvement of intracellular signalling pathways. GM-CSF primes human monocytes dose- and time-dependently for enhanced LPS-stimulated TNF-alpha synthesis. Pre-incubation with 10 ng/ml GM-CSF for 6 h before LPS stimulation (10 ng/ml) caused a 3.4 +/- 1.9-fold increase in TNF-alpha release compared to unprimed controls. This was associated with increased phosphorylation of IkappaBalpha and elevated nuclear levels of the NF-kappaB components p50 and p65 and NF-kappaB binding to DNA. LPS-induced AP-1 binding to DNA was also enhanced in GM-CSF-pre-incubated cells. GMCSF treatment also caused a slight increase in TLR4 expression on monocytes while CD14 expression remained unchanged. GM-CSF-priming was unaffected by inhibitors of p38 MAPK (SB203580) and lipoxygenase (NDGA). In contrast, the broad-spectrum tyrosine kinase inhibitor genistein and the MEK-1 inhibitor (PD98059) abrogated GM-CSF priming of TNF-alpha release and activation of both NF-kappaB and AP-1. It is concluded that a tyrosine kinase of the GM-CSF-triggered ERK1/2 pathway augments the LPS-induced NF-kappaB and AP-1 activation.
authors.affiliation: Department of Trauma Surgery, University Hospital of Essen, Essen, Germany.
authors.forename: Sven
authors.initials: S
authors.lastname: Lendemans
authors.forename: Meenakshi
authors.initials: M
authors.lastname: Rani
authors.forename: Christian
authors.initials: C
authors.lastname: Selbach
authors.forename: Ernst
authors.initials: E
authors.lastname: Kreuzfelder
authors.forename: Fritz Ulrich
authors.initials: FU
authors.lastname: Schade
authors.forename: Sascha
authors.initials: S
authors.lastname: Flohé
mesh_terms: D015153:Blotting, Western; D002467:Cell Nucleus / Q000187:drug effects / Q000378:metabolism; D002470:Cell Survival / Q000187:drug effects; D003593:Cytoplasm / Q000187:drug effects / Q000378:metabolism; D024202:Electrophoretic Mobility Shift Assay; D004789:Enzyme Activation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005434:Flow Cytometry; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000494:pharmacology*; D006801:Humans; D020672:I-kappa B Proteins / Q000378:metabolism; D066298:In Vitro Techniques; D018950:Lipopolysaccharide Receptors / Q000096:biosynthesis; D008070:Lipopolysaccharides / Q000494:pharmacology; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism*; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D009000:Monocytes / Q000187:drug effects* / Q000378:metabolism; D016328:NF-kappa B / Q000378:metabolism; D010766:Phosphorylation; D013268:Stimulation, Chemical; D051195:Toll-Like Receptor 2 / Q000096:biosynthesis; D051197:Toll-Like Receptor 4 / Q000096:biosynthesis; D018808:Transcription Factor AP-1 / Q000235:genetics; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis / Q000378:metabolism; D019892:eIF-2 Kinase / Q000378:metabolism
chemical_list: D004791:Enzyme Inhibitors; D020672:I-kappa B Proteins; D018950:Lipopolysaccharide Receptors; D008070:Lipopolysaccharides; D016328:NF-kappa B; D051195:Toll-Like Receptor 2; D051197:Toll-Like Receptor 4; D018808:Transcription Factor AP-1; D014409:Tumor Necrosis Factor-alpha; D016178:Granulocyte-Macrophage Colony-Stimulating Factor; D019892:eIF-2 Kinase; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases