title: Inhibition of Protease-Epithelial Sodium Channel Signaling Improves Mucociliary Function in Cystic Fibrosis Airways.
abstract: In cystic fibrosis (CF) a reduction in airway surface liquid (ASL) height compromises mucociliary clearance, favoring mucus plugging and chronic bacterial infection. Inhibitors of the epithelial sodium channel (ENaC) have therapeutic potential in CF airways to reduce hyperstimulated sodium and fluid absorption to levels that can restore airway hydration.
  
  
  
  To determine whether a novel compound (QUB-TL1) designed to inhibit protease/ENaC signaling in CF airways restores ASL volume and mucociliary function.
  
  
  
  Protease activity was measured using fluorogenic activity assays. Differentiated primary airway epithelial cell cultures (F508del homozygotes) were used to determined ENaC activity (Ussing chamber recordings), ASL height (confocal microscopy), and mucociliary function (by tracking the surface flow of apically applied microbeads). Cell toxicity was measured using a lactate dehydrogenase assay.
  
  
  
  QUB-TL1 inhibits extracellularly located channel activating proteases (CAPs), including prostasin, matriptase, and furin, the activities of which are observed at excessive levels at the apical surface of CF airway epithelial cells. QUB-TL1-mediated CAP inhibition results in diminished ENaC-mediated Na(+) absorption in CF airway epithelial cells caused by internalization of a prominent pool of cleaved (active) ENaCγ from the cell surface. Importantly, diminished ENaC activity correlates with improved airway hydration status and mucociliary clearance. We further demonstrate QUB-TL1-mediated furin inhibition, which is in contrast to other serine protease inhibitors (camostat mesylate and aprotinin), affords protection against neutrophil elastase-mediated ENaC activation and Pseudomonas aeruginosa exotoxin A-induced cell death.
  
  
  
  QUB-TL1 corrects aberrant CAP activities, providing a mechanism to delay or prevent the development of CF lung disease in a manner independent of CF transmembrane conductance regulator mutation.
authors.affiliation: 1 Biomolecular Sciences Research Group, School of Pharmacy, and.
authors.forename: James A
authors.initials: JA
authors.lastname: Reihill
authors.affiliation: 1 Biomolecular Sciences Research Group, School of Pharmacy, and.
authors.forename: Brian
authors.initials: B
authors.lastname: Walker
authors.affiliation: 1 Biomolecular Sciences Research Group, School of Pharmacy, and.
authors.forename: Robert A
authors.initials: RA
authors.lastname: Hamilton
authors.affiliation: 1 Biomolecular Sciences Research Group, School of Pharmacy, and.
authors.forename: Timothy E G
authors.initials: TE
authors.lastname: Ferguson
authors.affiliation: 2 School of Medicine, Dentistry & Biomedical Sciences, Queen's University, Belfast, Northern Ireland, United Kingdom.
authors.forename: J Stuart
authors.initials: JS
authors.lastname: Elborn
authors.affiliation: 3 Marsico Lung Institute and Cystic Fibrosis Center, University of North Carolina, Chapel Hill, North Carolina; and.
authors.forename: M Jackson
authors.initials: MJ
authors.lastname: Stutts
authors.affiliation: 4 Department of Molecular Medicine, Royal College of Surgeons in Ireland, RCSI-ERC Beaumont Hospital, Dublin, Ireland.
authors.forename: Brian J
authors.initials: BJ
authors.lastname: Harvey
authors.affiliation: 4 Department of Molecular Medicine, Royal College of Surgeons in Ireland, RCSI-ERC Beaumont Hospital, Dublin, Ireland.
authors.forename: Vinciane
authors.initials: V
authors.lastname: Saint-Criq
authors.affiliation: 4 Department of Molecular Medicine, Royal College of Surgeons in Ireland, RCSI-ERC Beaumont Hospital, Dublin, Ireland.
authors.forename: Siobhan M
authors.initials: SM
authors.lastname: Hendrick
authors.affiliation: 1 Biomolecular Sciences Research Group, School of Pharmacy, and.
authors.forename: S Lorraine
authors.identifier: 0000-0002-1923-0610
authors.initials: SL
authors.lastname: Martin
mesh_terms: D001120:Arginine / Q000031:analogs & derivatives* / Q000494:pharmacology; D002478:Cells, Cultured; D003550:Cystic Fibrosis / Q000188:drug therapy*; D006801:Humans; D009079:Mucociliary Clearance / Q000187:drug effects* / Q000502:physiology; D063065:Organophosphonates / Q000494:pharmacology*; D020545:Respiratory Mucosa / Q000166:cytology / Q000187:drug effects* / Q000502:physiology; D012697:Serine Endopeptidases / Q000187:drug effects*; D026941:Sodium Channel Blockers / Q000627:therapeutic use*; D015222:Sodium Channels / Q000187:drug effects* / Q000502:physiology
chemical_list: D063065:Organophosphonates; C000621181:QUB-TL1 compound; D026941:Sodium Channel Blockers; D015222:Sodium Channels; D001120:Arginine; D012697:Serine Endopeptidases; C112256:human airway trypsin-like protease
keywords: Pseudomonas aeruginosa exotoxin A; airway surface liquid; channel activating proteases; furin; prostasin