title: A neutrophil intrinsic impairment affecting Rab27a and degranulation in cystic fibrosis is corrected by CFTR potentiator therapy.
abstract: Studies have endeavored to reconcile whether dysfunction of neutrophils in people with cystic fibrosis (CF) is a result of the genetic defect or is secondary due to infection and inflammation. In this study, we illustrate that disrupted function of the CF transmembrane conductance regulator (CFTR), such as that which occurs in patients with ∆F508 and/or G551D mutations, correlates with impaired degranulation of antimicrobial proteins. We demonstrate that CF blood neutrophils release less secondary and tertiary granule components compared with control cells and that activation of the low-molecular-mass GTP-binding protein Rab27a, involved in the regulation of granule trafficking, is defective. The mechanism leading to impaired degranulation involves altered ion homeostasis caused by defective CFTR function with increased cytosolic levels of chloride and sodium, yet decreased magnesium measured in CF neutrophils. Decreased magnesium concentration in vivo and in vitro resulted in significantly decreased levels of GTP-bound Rab27a. Treatment of G551D patients with the ion channel potentiator ivacaftor resulted in normalized neutrophil cytosolic ion levels and activation of Rab27a, thereby leading to increased degranulation and bacterial killing. Our results confirm that intrinsic alterations of circulating neutrophils from patients with CF are corrected by ivacaftor, thus illustrating additional clinical benefits for CFTR modulator therapy.
authors.affiliation: Respiratory Research Division, Department of Medicine, Royal College of Surgeons in Ireland, Education and Research Centre, Beaumont Hospital, Dublin, Ireland; and.
authors.forename: Kerstin
authors.initials: K
authors.lastname: Pohl
authors.affiliation: Respiratory Research Division, Department of Medicine, Royal College of Surgeons in Ireland, Education and Research Centre, Beaumont Hospital, Dublin, Ireland; and.
authors.forename: Elaine
authors.initials: E
authors.lastname: Hayes
authors.affiliation: National Institute for Cellular Biotechnology, Dublin City University, Dublin, Ireland.
authors.forename: Joanne
authors.initials: J
authors.lastname: Keenan
authors.affiliation: National Institute for Cellular Biotechnology, Dublin City University, Dublin, Ireland.
authors.forename: Michael
authors.initials: M
authors.lastname: Henry
authors.affiliation: National Institute for Cellular Biotechnology, Dublin City University, Dublin, Ireland.
authors.forename: Paula
authors.initials: P
authors.lastname: Meleady
authors.affiliation: Respiratory Research Division, Department of Medicine, Royal College of Surgeons in Ireland, Education and Research Centre, Beaumont Hospital, Dublin, Ireland; and.
authors.forename: Kevin
authors.initials: K
authors.lastname: Molloy
authors.affiliation: Respiratory Research Division, Department of Medicine, Royal College of Surgeons in Ireland, Education and Research Centre, Beaumont Hospital, Dublin, Ireland; and.
authors.forename: Bakr
authors.initials: B
authors.lastname: Jundi
authors.affiliation: Respiratory Research Division, Department of Medicine, Royal College of Surgeons in Ireland, Education and Research Centre, Beaumont Hospital, Dublin, Ireland; and.
authors.forename: David A
authors.initials: DA
authors.lastname: Bergin
authors.affiliation: Respiratory Research Division, Department of Medicine, Royal College of Surgeons in Ireland, Education and Research Centre, Beaumont Hospital, Dublin, Ireland; and.
authors.forename: Cormac
authors.initials: C
authors.lastname: McCarthy
authors.affiliation: Respiratory Research Division, Department of Medicine, Royal College of Surgeons in Ireland, Education and Research Centre, Beaumont Hospital, Dublin, Ireland; and.
authors.forename: Oliver J
authors.initials: OJ
authors.lastname: McElvaney
authors.affiliation: Respiratory Research Division, Department of Medicine, Royal College of Surgeons in Ireland, Education and Research Centre, Beaumont Hospital, Dublin, Ireland; and.
authors.forename: Michelle M
authors.initials: MM
authors.lastname: White
authors.affiliation: National Institute for Cellular Biotechnology, Dublin City University, Dublin, Ireland.
authors.forename: Martin
authors.initials: M
authors.lastname: Clynes
authors.affiliation: Respiratory Research Division, Department of Medicine, Royal College of Surgeons in Ireland, Education and Research Centre, Beaumont Hospital, Dublin, Ireland; and.
authors.forename: Emer P
authors.initials: EP
authors.lastname: Reeves
authors.affiliation: Respiratory Research Division, Department of Medicine, Royal College of Surgeons in Ireland, Education and Research Centre, Beaumont Hospital, Dublin, Ireland; and.
authors.forename: Noel G
authors.initials: NG
authors.lastname: McElvaney
mesh_terms: D000328:Adult; D000627:Aminophenols / Q000627:therapeutic use; D015550:Cell Degranulation / Q000187:drug effects / Q000235:genetics; D002478:Cells, Cultured; D002712:Chlorides / Q000378:metabolism; D003550:Cystic Fibrosis / Q000188:drug therapy / Q000235:genetics / Q000378:metabolism*; D019005:Cystic Fibrosis Transmembrane Conductance Regulator / Q000235:genetics / Q000378:metabolism*; D015180:Electrophoresis, Gel, Two-Dimensional; D005260:Female; D006706:Homeostasis / Q000235:genetics; D006801:Humans; D015151:Immunoblotting; D008274:Magnesium / Q000378:metabolism; D008297:Male; D009154:Mutation; D009504:Neutrophils / Q000187:drug effects / Q000378:metabolism* / Q000502:physiology; D021381:Protein Transport / Q000187:drug effects; D020543:Proteome / Q000235:genetics / Q000378:metabolism; D040901:Proteomics / Q000379:methods; D015363:Quinolones / Q000627:therapeutic use; D012964:Sodium / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology; D055815:Young Adult; D020691:rab GTP-Binding Proteins / Q000378:metabolism*; D000075745:rab27 GTP-Binding Proteins
chemical_list: D000627:Aminophenols; C505032:CFTR protein, human; D002712:Chlorides; D020543:Proteome; D015363:Quinolones; D014409:Tumor Necrosis Factor-alpha; D000075745:rab27 GTP-Binding Proteins; D019005:Cystic Fibrosis Transmembrane Conductance Regulator; C545203:ivacaftor; D012964:Sodium; C066694:RAB27A protein, human; D020691:rab GTP-Binding Proteins; D008274:Magnesium