title: Implication of cytosolic phospholipase A2 (cPLA2) in the regulation of human synoviocyte NADPH oxidase (Nox2) activity.
abstract: NADPH oxidase Nox2 is involved in the production of superoxide by rheumatoid synovial cells, constitutively and after pro-inflammatory cytokine treatment. The aims of the study were to evaluate the capacity of these cells to produce the superoxide anion in response to arachidonic acid (AA), and to study the involvement of cytosolic phospholipase A(2) (cPLA(2)) in the cytokine regulation of Nox2. Superoxide production was quantified in synovial cells obtained from six patients with rheumatoid arthritis (RA) and six with osteoarthritis (OA), stimulated with (i) AA, and (ii) PLA(2) inhibitors prior to IL-1beta or TNF-alpha treatment. Total cellular AA concentrations and PLA(2) activity were measured; effects of cytokines and NADPH oxidase inhibitors on the AA-activatable proton channel opening were also studied. Our results demonstrated that AA enhanced superoxide production in RA and OA cells; this production was significantly inhibited by iodonium diphenyl and apocynin. cPLA(2) inhibitors inhibited both IL-1beta and TNF-alpha-induced superoxide production in RA and OA cells. Basal PLA(2) activity was significantly more important in RA cells than in OA cells; PLA(2) activity was increased in IL-1beta and TNF-alpha pre-treated RA cells, and cPLA(2) inhibitors inhibited this activity. Opening of the AA-activatable proton channel was amplified when RA cells were pre-treated with both IL-1beta and TNF-alpha, and iodonium diphenyl and apocynin inhibited these cytokine effects. We concluded that AA is an important cofactor for synovial NADPH oxidase activity. Despite their direct effects on p47-phox phosphorylation, cytokines can also regulate the Nox2 activity though the AA-activatable associated H(+) channel.
authors.affiliation: Laboratoire de Biochimie A, Hôpital Cochin, Assistance Publique - Hôpitaux de Paris (AP-HP), 27 rue du Faubourg Saint-Jacques, 75679 Paris cedex 14, France. camille.gobeaux@cch.aphp.fr
authors.forename: Camille
authors.initials: C
authors.lastname: Chenevier-Gobeaux
authors.forename: Catherine
authors.initials: C
authors.lastname: Simonneau
authors.forename: Patrice
authors.initials: P
authors.lastname: Therond
authors.forename: Dominique
authors.initials: D
authors.lastname: Bonnefont-Rousselot
authors.forename: Serge
authors.initials: S
authors.lastname: Poiraudeau
authors.forename: Ohvanesse G
authors.initials: OG
authors.lastname: Ekindjian
authors.forename: Didier
authors.initials: D
authors.lastname: Borderie
mesh_terms: D000098:Acetophenones / Q000494:pharmacology; D000890:Anti-Infective Agents / Q000494:pharmacology; D016718:Arachidonic Acid / Q000494:pharmacology; D001172:Arthritis, Rheumatoid / Q000201:enzymology* / Q000473:pathology; D001713:Biphenyl Compounds / Q000494:pharmacology; D002478:Cells, Cultured; D003600:Cytosol / Q000201:enzymology* / Q000473:pathology; D004790:Enzyme Induction / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006801:Humans; D053583:Interleukin-1beta / Q000494:pharmacology; D007473:Ion Channels / Q000037:antagonists & inhibitors / Q000378:metabolism; D008562:Membrane Glycoproteins / Q000037:antagonists & inhibitors / Q000096:biosynthesis*; D000074662:NADPH Oxidase 2; D019255:NADPH Oxidases / Q000037:antagonists & inhibitors / Q000096:biosynthesis* / Q000378:metabolism; D009861:Onium Compounds / Q000494:pharmacology; D010003:Osteoarthritis / Q000201:enzymology* / Q000473:pathology; D010741:Phospholipases A / Q000037:antagonists & inhibitors / Q000378:metabolism*; D054467:Phospholipases A2; D013481:Superoxides / Q000378:metabolism; D013583:Synovial Membrane / Q000201:enzymology* / Q000473:pathology; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology
chemical_list: D000098:Acetophenones; D000890:Anti-Infective Agents; D001713:Biphenyl Compounds; D004791:Enzyme Inhibitors; D053583:Interleukin-1beta; D007473:Ion Channels; D008562:Membrane Glycoproteins; D009861:Onium Compounds; D014409:Tumor Necrosis Factor-alpha; C031291:diphenyliodonium; D013481:Superoxides; D016718:Arachidonic Acid; C056165:acetovanillone; C056558:CYBB protein, human; D000074662:NADPH Oxidase 2; D019255:NADPH Oxidases; C060505:neutrophil cytosolic factor 1; D010741:Phospholipases A; D054467:Phospholipases A2