title: Regulation of human eosinophil NADPH oxidase activity: a central role for PKCdelta.
abstract: Eosinophils play a primary role in the pathophysiology of asthma. In the lung, the activation state of the infiltrating eosinophils determines the extent of tissue damage. Interleukin-5 (IL-5) and leukotriene B4 (LTB4) are important signaling molecules involved in eosinophil recruitment and activation. However, the physiological processes that regulate these activation events are largely unknown. In this study we have examined the mechanisms of human eosinophil NADPH oxidase regulation by IL-5, LTB4, and phorbol ester (PMA). These stimuli activate a Zn2+-sensitive plasma membrane proton channel, and treatment of eosinophils with Zn2+ blocks superoxide production. We have demonstrated that eosinophil intracellular pH is not altered by IL-5 activation of NADPH oxidase. Additionally, PKCdelta inhibitors block PMA, IL-5 and LTB4 mediated superoxide formation. Interestingly, the PKCdelta-selective inhibitor, rottlerin, does not block proton channel activation by PMA indicating that the oxidase and the proton conductance are regulated at distinct phosphorylation sites. IL-5 and LTB4, but not PMA, stimulated superoxide production is also blocked by inhibitors of PI 3-kinase indicating that activation of this enzyme is an upstream event common to both receptor signaling pathways. Our results indicate that the G-protein-coupled LTB4 receptor and the IL-5 cytokine receptor converge on a common signaling pathway involving PI 3-kinase and PKCdelta to regulate NADPH oxidase activity in human eosinophils.
authors.affiliation: Allergic Diseases Research Laboratory, Department of Immunology, Mayo Clinic and Foundation, Rochester, Minnesota 55905, USA. bankers.jennifer@mayo.edu
authors.forename: J L
authors.initials: JL
authors.lastname: Bankers-Fulbright
authors.forename: H
authors.initials: H
authors.lastname: Kita
authors.forename: G J
authors.initials: GJ
authors.lastname: Gleich
authors.forename: S M
authors.initials: SM
authors.lastname: O'Grady
mesh_terms: D000098:Acetophenones / Q000494:pharmacology; D001578:Benzopyrans / Q000494:pharmacology; D002478:Cells, Cultured; D002712:Chlorides / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004553:Electric Conductivity; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004804:Eosinophils / Q000187:drug effects / Q000201:enzymology* / Q000276:immunology; D006801:Humans; D006863:Hydrogen-Ion Concentration; D015848:Interleukin-5 / Q000494:pharmacology; D007527:Isoenzymes / Q000037:antagonists & inhibitors / Q000502:physiology*; D007700:Kinetics; D007975:Leukotriene B4 / Q000494:pharmacology; D019255:NADPH Oxidases / Q000378:metabolism*; D018408:Patch-Clamp Techniques; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000502:physiology*; D051745:Protein Kinase C-delta; D017494:Proton Pumps / Q000502:physiology; D013481:Superoxides / Q000378:metabolism; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D017967:Zinc Compounds / Q000494:pharmacology
chemical_list: D000098:Acetophenones; D001578:Benzopyrans; D002712:Chlorides; D004791:Enzyme Inhibitors; D015848:Interleukin-5; D007527:Isoenzymes; D017494:Proton Pumps; D017967:Zinc Compounds; D013481:Superoxides; D007975:Leukotriene B4; C016837:zinc chloride; C085746:rottlerin; D019255:NADPH Oxidases; C497258:PRKCD protein, human; D011493:Protein Kinase C; D051745:Protein Kinase C-delta; D013755:Tetradecanoylphorbol Acetate