title: Exchange protein directly activated by cyclic AMP (EPAC) activation reverses neutrophil dysfunction induced by β2-agonists, corticosteroids, and critical illness.
abstract: BACKGROUND
  Neutrophils play a role in the pathogenesis of asthma, chronic obstructive pulmonary disease, and pulmonary infection. Impaired neutrophil phagocytosis predicts hospital-acquired infection. Despite this, remarkably few neutrophil-specific treatments exist.
  
  
  OBJECTIVE
  We sought to identify novel pathways for the restoration of effective neutrophil phagocytosis and to activate such pathways effectively in neutrophils from patients with impaired neutrophil phagocytosis.
  
  
  METHODS
  Blood neutrophils were isolated from healthy volunteers and patients with impaired neutrophil function. In healthy neutrophils phagocytic impairment was induced experimentally by using β2-agonists. Inhibitors and activators of cyclic AMP (cAMP)-dependent pathways were used to assess the influence on neutrophil phagocytosis in vitro.
  
  
  RESULTS
  β2-Agonists and corticosteroids inhibited neutrophil phagocytosis. Impairment of neutrophil phagocytosis by β2-agonists was associated with significantly reduced RhoA activity. Inhibition of protein kinase A (PKA) restored phagocytosis and RhoA activity, suggesting that cAMP signals through PKA to drive phagocytic impairment. However, cAMP can signal through effectors other than PKA, such as exchange protein directly activated by cyclic AMP (EPAC). An EPAC-activating analog of cAMP (8CPT-2Me-cAMP) reversed neutrophil dysfunction induced by β2-agonists or corticosteroids but did not increase RhoA activity. 8CPT-2Me-cAMP reversed phagocytic impairment induced by Rho kinase inhibition but was ineffective in the presence of Rap-1 GTPase inhibitors. 8CPT-2Me-cAMP restored function to neutrophils from patients with known acquired impairment of neutrophil phagocytosis.
  
  
  CONCLUSIONS
  EPAC activation consistently reverses clinical and experimental impairment of neutrophil phagocytosis. EPAC signals through Rap-1 and bypasses RhoA. EPAC activation represents a novel potential means by which to reverse impaired neutrophil phagocytosis.
authors.affiliation: Institute of Cellular Medicine, Newcastle University, Newcastle upon Tyne, United Kingdom.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Scott
authors.affiliation: Institute of Cellular Medicine, Newcastle University, Newcastle upon Tyne, United Kingdom.
authors.forename: Graham J
authors.initials: GJ
authors.lastname: Harris
authors.affiliation: Institute of Cellular Medicine, Newcastle University, Newcastle upon Tyne, United Kingdom.
authors.forename: Emma M
authors.initials: EM
authors.lastname: Pinder
authors.affiliation: Institute of Cellular Medicine, Newcastle University, Newcastle upon Tyne, United Kingdom.
authors.forename: James G
authors.initials: JG
authors.lastname: Macfarlane
authors.affiliation: Institute of Cellular Medicine, Newcastle University, Newcastle upon Tyne, United Kingdom.
authors.forename: Thomas P
authors.initials: TP
authors.lastname: Hellyer
authors.affiliation: Institute of Cellular Medicine, Newcastle University, Newcastle upon Tyne, United Kingdom.
authors.forename: Anthony J
authors.initials: AJ
authors.lastname: Rostron
authors.affiliation: Division of Anaesthesia, University of Cambridge, Addenbrooke's Hospital, Cambridge, United Kingdom.
authors.forename: Andrew
authors.initials: A
authors.lastname: Conway Morris
authors.affiliation: Centre for Translational Inflammation Research, University of Birmingham, Queen Elizabeth Hospital, Birmingham, United Kingdom.
authors.forename: David R
authors.initials: DR
authors.lastname: Thickett
authors.affiliation: Warwick Medical School Clinical Trials Unit and Heart of England Foundation Trust, University of Warwick, Coventry, United Kingdom.
authors.forename: Gavin D
authors.initials: GD
authors.lastname: Perkins
authors.affiliation: Centre for Infection and Immunity, Health Sciences Building, Queen's University Belfast, Belfast, United Kingdom; Regional Intensive Care Unit, Royal Victoria Hospital, Belfast, United Kingdom.
authors.forename: Daniel F
authors.initials: DF
authors.lastname: McAuley
authors.affiliation: Institute of Cellular Medicine, Newcastle University, Newcastle upon Tyne, United Kingdom.
authors.forename: John D
authors.initials: JD
authors.lastname: Widdrington
authors.affiliation: Institute of Cellular Medicine, Newcastle University, Newcastle upon Tyne, United Kingdom.
authors.forename: Sarah
authors.initials: S
authors.lastname: Wiscombe
authors.affiliation: Department of Anaesthetics, Royal Victoria Infirmary, Newcastle upon Tyne, United Kingdom.
authors.forename: Simon V
authors.initials: SV
authors.lastname: Baudouin
authors.affiliation: Integrated Critical Care Unit, Sunderland Royal Hospital, Sunderland, United Kingdom.
authors.forename: Alistair I
authors.initials: AI
authors.lastname: Roy
authors.affiliation: Intensive Care Unit, Queen Elizabeth Hospital, Gateshead, United Kingdom.
authors.forename: Vanessa C
authors.initials: VC
authors.lastname: Linnett
authors.affiliation: Intensive Care Unit, Freeman Hospital, Newcastle upon Tyne, United Kingdom.
authors.forename: Stephen E
authors.initials: SE
authors.lastname: Wright
authors.affiliation: Institute of Cellular Medicine, Newcastle University, Newcastle upon Tyne, United Kingdom.
authors.forename: Marie-Hélène
authors.initials: MH
authors.lastname: Ruchaud-Sparagano
authors.affiliation: Institute of Cellular Medicine, Newcastle University, Newcastle upon Tyne, United Kingdom. Electronic address: j.simpson@ncl.ac.uk.
authors.forename: A John
authors.initials: AJ
authors.lastname: Simpson
mesh_terms: D000305:Adrenal Cortex Hormones / Q000494:pharmacology*; D058666:Adrenergic beta-2 Receptor Agonists / Q000494:pharmacology*; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016638:Critical Illness; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D003602:Cytotoxicity, Immunologic; D005260:Female; D020662:Guanine Nucleotide Exchange Factors; D006801:Humans; D008297:Male; D008875:Middle Aged; D008954:Models, Biological; D018375:Neutrophil Activation / Q000187:drug effects / Q000276:immunology; D009504:Neutrophils / Q000187:drug effects / Q000276:immunology* / Q000378:metabolism*; D010587:Phagocytosis / Q000187:drug effects / Q000276:immunology; D054460:rho-Associated Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D020742:rhoA GTP-Binding Protein / Q000378:metabolism
chemical_list: D000305:Adrenal Cortex Hormones; D058666:Adrenergic beta-2 Receptor Agonists; D020662:Guanine Nucleotide Exchange Factors; C116122:RAPGEF3 protein, human; D054460:rho-Associated Kinases; D017868:Cyclic AMP-Dependent Protein Kinases; D020742:rhoA GTP-Binding Protein
keywords: Neutrophil; cyclic AMP; exchange protein directly activated by cyclic AMP; hospital-acquired infection; β(2)-agonist