title: Cytokine-Induced Glucocorticoid Resistance from Eosinophil Activation: Protein Phosphatase 5 Modulation of Glucocorticoid Receptor Phosphorylation and Signaling.
abstract: The mechanisms contributing to persistent eosinophil activation and poor eosinopenic response to glucocorticoids in severe asthma are poorly defined. We examined the effect of cytokines typically overexpressed in the asthmatic airways on glucocorticoid signaling in in vitro activated eosinophils. An annexin V assay used to measure eosinophil apoptosis showed that cytokine combinations of IL-2 plus IL-4 as well as TNF-α plus IFN-γ, or IL-3, GM-CSF, and IL-5 alone significantly diminished the proapoptotic response to dexamethasone. We found that IL-2 plus IL-4 resulted in impaired phosphorylation and function of the nuclear glucocorticoid receptor (GCR). Proteomic analysis of steroid sensitive and resistant eosinophils identified several differentially expressed proteins, namely protein phosphatase 5 (PP5), formyl peptide receptor 2, and annexin 1. Furthermore, increased phosphatase activity of PP5 correlated with impaired phosphorylation of the GCR. Importantly, suppression of PP5 expression with small interfering RNA restored proper phosphorylation and the proapoptotic function of the GCR. We also examined the effect of lipoxin A4 on PP5 activation by IL-2 plus IL-4. Similar to PP5 small interfering RNA inhibition, pretreatment of eosinophils with lipoxin A4 restored GCR phosphorylation and the proaptoptotic function of GCs. Taken together, our results showed 1) a critical role for PP5 in cytokine-induced resistance to GC-mediated eosinophil death, 2) supported the dependence of GCR phosphorylation on PP5 activity, and 3) revealed that PP5 is a target of the lipoxin A4-induced pathway countering cytokine-induced resistance to GCs in eosinophils.
authors.affiliation: Department of Biochemistry and Molecular Biology, The University of Texas Medical Branch, Galveston, TX 77555.|National Heart, Lung, and Blood Institute Proteomics Center Program in Airway Inflammation, The University of Texas Medical Branch, Galveston, TX 77555.
authors.forename: Konrad
authors.identifier: 0000-0002-2771-5132
authors.initials: K
authors.lastname: Pazdrak
authors.affiliation: Department of Biochemistry and Molecular Biology, The University of Texas Medical Branch, Galveston, TX 77555.
authors.forename: Christof
authors.initials: C
authors.lastname: Straub
authors.affiliation: Department of Biochemistry and Molecular Biology, The University of Texas Medical Branch, Galveston, TX 77555.|National Heart, Lung, and Blood Institute Proteomics Center Program in Airway Inflammation, The University of Texas Medical Branch, Galveston, TX 77555.
authors.forename: Rosario
authors.initials: R
authors.lastname: Maroto
authors.affiliation: Department of Biochemistry and Molecular Biology, The University of Texas Medical Branch, Galveston, TX 77555.|National Heart, Lung, and Blood Institute Proteomics Center Program in Airway Inflammation, The University of Texas Medical Branch, Galveston, TX 77555.
authors.forename: Susan
authors.identifier: 0000-0002-5648-6981
authors.initials: S
authors.lastname: Stafford
authors.affiliation: MedImmune LLC, Gaithersburg, MD 20878; and.
authors.forename: Wendy I
authors.initials: WI
authors.lastname: White
authors.affiliation: Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, The University of Texas Medical Branch, Galveston, TX 77555.|National Heart, Lung, and Blood Institute Proteomics Center Program in Airway Inflammation, The University of Texas Medical Branch, Galveston, TX 77555.
authors.forename: William J
authors.identifier: 0000-0001-7075-712X
authors.initials: WJ
authors.lastname: Calhoun
authors.affiliation: Department of Biochemistry and Molecular Biology, The University of Texas Medical Branch, Galveston, TX 77555; akurosky@utmb.edu.|National Heart, Lung, and Blood Institute Proteomics Center Program in Airway Inflammation, The University of Texas Medical Branch, Galveston, TX 77555.
authors.forename: Alexander
authors.identifier: 0000-0002-2889-2317
authors.initials: A
authors.lastname: Kurosky
mesh_terms: D017209:Apoptosis / Q000187:drug effects; D001249:Asthma / Q000150:complications / Q000276:immunology; D016207:Cytokines / Q000276:immunology*; D003907:Dexamethasone / Q000494:pharmacology; D004804:Eosinophils / Q000187:drug effects / Q000276:immunology* / Q000502:physiology; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000494:pharmacology; D006801:Humans; D006967:Hypersensitivity / Q000378:metabolism; D007376:Interleukin-2 / Q000494:pharmacology; D007377:Interleukin-3 / Q000494:pharmacology; D015847:Interleukin-4 / Q000494:pharmacology; D015848:Interleukin-5 / Q000494:pharmacology; D044045:Lipoxins / Q000494:pharmacology; D008661:Metabolism, Inborn Errors / Q000276:immunology* / Q000378:metabolism; D009687:Nuclear Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D010749:Phosphoprotein Phosphatases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation; D040901:Proteomics; D034741:RNA, Small Interfering / Q000494:pharmacology; D011965:Receptors, Glucocorticoid / Q000172:deficiency* / Q000276:immunology / Q000378:metabolism*; D015398:Signal Transduction; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology
chemical_list: D016207:Cytokines; C508598:IL4 protein, human; D007376:Interleukin-2; D007377:Interleukin-3; D015848:Interleukin-5; D044045:Lipoxins; D009687:Nuclear Proteins; D034741:RNA, Small Interfering; D011965:Receptors, Glucocorticoid; D014409:Tumor Necrosis Factor-alpha; C040527:lipoxin A4; D015847:Interleukin-4; D003907:Dexamethasone; D016178:Granulocyte-Macrophage Colony-Stimulating Factor; D010749:Phosphoprotein Phosphatases; C089641:protein phosphatase 5