title: Interleukin-18 primes the oxidative burst of neutrophils in response to formyl-peptides: role of cytochrome b558 translocation and N-formyl peptide receptor endocytosis.
abstract: Using flow cytometry, we observed that interleukin-18 (IL-18) primed human neutrophils (PMNs) in whole blood to produce superoxide anion (O2 degrees-) in response to N-formyl peptide (fMLP) stimulation, whereas IL-18 alone had no significant effect. In contrast to tumor necrosis factor alpha (TNF-alpha), which is a cytokine known to strongly prime O2 degrees- production, IL-18 did not induce either p47phox phosphorylation or its translocation from the cytosol to the plasma membrane. However, IL-18 increased PMN degranulation, as shown by increased levels of cytochrome b558 and CD11b expression at the PMN surface. Moreover, addition of IL-18 to whole blood for 45 min reduced the ability of PMNs to bind to fMLP, suggesting endocytosis of fMLP receptors, as visualized by confocal microscopy. 2,3-Butanedione 2-monoxime, which inhibits endosomal recycling of plasma membrane components back to the cell surface, concomitantly accentuated the diminution of fMLP binding at the PMN surface and increased IL-18 priming of O2 degrees- production by PMNs in response to fMLP. This suggests that fMLP receptor endocytosis could account, at least in part, for the priming of O2 degrees- production. In addition, genistein, a tyrosine kinase inhibitor, and SB203580, a p38 mitogen-activated protein kinase (p38MAPK) inhibitor, completely reversed the decreased level of fMLP binding and increased the level of CD11b expression after IL-18 treatment. Flow cytometric analysis of intact PMNs in whole blood showed that IL-18 increased p38MAPK phosphorylation and tyrosine phosphorylation. In particular, IL-18 induced phosphorylation of focal adhesion kinase (p125FAK), which has been implicated in cytoskeleton reorganization. Taken together, our findings suggest several mechanisms that are likely to regulate cytokine-induced priming of the oxidative burst in PMNs in their blood environment.
authors.affiliation: Unité INSERM U479, Faculté de Médecine Xavier Bichat, 16 rue Henri Huchard, 75877 Paris Cedex 18, France.
authors.forename: Carole
authors.initials: C
authors.lastname: Elbim
authors.forename: Cécile
authors.initials: C
authors.lastname: Guichard
authors.forename: Pham M C
authors.initials: PM
authors.lastname: Dang
authors.forename: Michèle
authors.initials: M
authors.lastname: Fay
authors.forename: Eric
authors.initials: E
authors.lastname: Pedruzzi
authors.forename: Hélène
authors.initials: H
authors.lastname: Demur
authors.forename: Cécile
authors.initials: C
authors.lastname: Pouzet
authors.forename: Jamel
authors.initials: J
authors.lastname: El Benna
authors.forename: Marie-Anne
authors.initials: MA
authors.lastname: Gougerot-Pocidalo
mesh_terms: D015550:Cell Degranulation / Q000187:drug effects; D002478:Cells, Cultured; D003573:Cytochrome b Group / Q000378:metabolism; D004705:Endocytosis / Q000187:drug effects; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; D006801:Humans; D020382:Interleukin-18 / Q000494:pharmacology*; D009240:N-Formylmethionine Leucyl-Phenylalanine / Q000494:pharmacology; D019255:NADPH Oxidases / Q000378:metabolism; D009504:Neutrophils / Q000187:drug effects / Q000378:metabolism*; D010766:Phosphorylation / Q000187:drug effects; D021381:Protein Transport; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D044042:Receptors, Formyl Peptide / Q000502:physiology*; D016897:Respiratory Burst / Q000187:drug effects*; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism
chemical_list: D003573:Cytochrome b Group; D020382:Interleukin-18; D044042:Receptors, Formyl Peptide; D009240:N-Formylmethionine Leucyl-Phenylalanine; C036888:cytochrome b558; D019255:NADPH Oxidases; D011505:Protein-Tyrosine Kinases; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; C496050:PTK2 protein, human; D048051:p38 Mitogen-Activated Protein Kinases