Journal Article

Inhibition of Protease–Epithelial Sodium Channel Signaling Improves Mucociliary Function in Cystic Fibrosis Airways

Elborn, J. Stuart, Martin, S. Lorraine, Stutts, M. Jackson, Walker, Brian, Ferguson, Timothy, Reihill, James, Hamilton, Robert, Harvey, Brian, Hendrick, Siobhan, Saint-Criq, Vinciane, Molecular Medicine Department, Royal College of Surgeons in Ireland ; Beaumont Hospital [Dublin, Ireland]

2016

Overview

Abstract Rationale 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. Objectives To determine whether a novel compound (QUB-TL1) designed to inhibit protease/ENaC signaling in CF airways restores ASL volume and mucociliary function. Methods 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. Measurements and Main Results 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. Conclusions 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.

• Publisher: American Thoracic Society,HAL CCSD,Oxford University Press
• Subject: Arginine - analogs & derivatives / Arginine - pharmacology / Cells, Cultured / Cystic fibrosis / Cystic Fibrosis - drug therapy / Humans / Hydration / Life Sciences / Mucociliary Clearance - drug effects / Mucociliary Clearance - physiology / Organophosphonates - pharmacology / Respiratory Mucosa - cytology / Respiratory Mucosa - drug effects / Respiratory Mucosa - physiology / Serine Endopeptidases - drug effects / Sodium Channel Blockers - therapeutic use / Sodium Channels - drug effects / Sodium Channels - physiology