title: Analysis of signal transduction pathways regulating cytokine-mediated Fc receptor activation on human eosinophils.
abstract: Igs can be potent stimulants of eosinophil activation since interaction with IgA or IgG-coated particles can lead to eosinophil degranulation. We have investigated the comparative roles of mitogen-activated protein (MAP) kinases (MAPKs; ERK1/2 and p38) and phosphatidylinositol-3 kinase (PI3K) in the priming and regulation of Fc receptor functioning on human eosinophils utilizing a MAPK kinase (MEK) inhibitor (PD98059), a p38 inhibitor SB203580, and the widely used PI3K inhibitors wortmannin and LY294002. We demonstrate that priming of human eosinophils with Th2-derived cytokines, IL-4 and IL-5, differentially activate phosphotyrosine-associated PI3K and ERK and p38 MAP kinases. This activation can be inhibited by pre-incubation with wortmannin or LY294002, PD98059, and SB203580, respectively. Analysis of the effects of the inhibitors on rosette formation between human eosinophils and IgA- or IgG-coated beads revealed that activation of MEK was not required for IgA binding after priming with IL-4 or IL-5. However, inhibition of MEK did inhibit IL-5-primed binding of IgG-beads. The rosette formation of primed eosinophils with IgA-beads could be completely inhibited by wortmannin and LY294002 treatment, demonstrating a critical role for PI3K. Interestingly, inhibition of the p38 pathway also resulted in a complete blockade of IgA rosette formation. This work demonstrates regulatory control by inside-out signaling of Fc receptors by various cytokines on human eosinophils. Thus in vivo the local production of Th2-derived cytokines will regulate the effector functions of Fc receptors.
authors.affiliation: Department of Pulmonary Diseases, University Hospital Utrecht, The Netherlands.
authors.forename: M
authors.initials: M
authors.lastname: Bracke
authors.forename: P J
authors.initials: PJ
authors.lastname: Coffer
authors.forename: J W
authors.initials: JW
authors.lastname: Lammers
authors.forename: L
authors.initials: L
authors.lastname: Koenderman
mesh_terms: D000730:Androstadienes / Q000494:pharmacology; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000037:antagonists & inhibitors / Q000502:physiology; D002867:Chromones / Q000494:pharmacology; D004789:Enzyme Activation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004804:Eosinophils / Q000187:drug effects* / Q000276:immunology; D005419:Flavonoids / Q000494:pharmacology; D006801:Humans; D007093:Imidazoles / Q000494:pharmacology; D007070:Immunoglobulin A / Q000276:immunology*; D007074:Immunoglobulin G / Q000276:immunology*; D015847:Interleukin-4 / Q000494:pharmacology*; D015848:Interleukin-5 / Q000494:pharmacology*; D008863:Microspheres; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D009025:Morpholines / Q000494:pharmacology; D019869:Phosphatidylinositol 3-Kinases / Q000502:physiology; D000081082:Phosphoinositide-3 Kinase Inhibitors; D010766:Phosphorylation / Q000187:drug effects; D047428:Protein Kinase Inhibitors; D011494:Protein Kinases / Q000502:physiology*; D011499:Protein Processing, Post-Translational / Q000187:drug effects; D011725:Pyridines / Q000494:pharmacology; D011961:Receptors, Fc / Q000187:drug effects* / Q000276:immunology; D017452:Receptors, IgG / Q000187:drug effects* / Q000276:immunology; D012397:Rosette Formation; D015398:Signal Transduction / Q000502:physiology*; D018418:Th2 Cells / Q000378:metabolism; D000077191:Wortmannin
chemical_list: D000730:Androstadienes; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D002867:Chromones; D004791:Enzyme Inhibitors; D005419:Flavonoids; D007093:Imidazoles; D007070:Immunoglobulin A; D007074:Immunoglobulin G; D015847:Interleukin-4; D015848:Interleukin-5; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D009025:Morpholines; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D047428:Protein Kinase Inhibitors; D011494:Protein Kinases; D011725:Pyridines; D011961:Receptors, Fc; D017452:Receptors, IgG; D000077191:Wortmannin; C045281:IgA receptor; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one; C093642:SB 203580; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one