Preventive but not late amiloride therapy reduces morbidity and mortality of lung disease in βENaC-overexpressing mice

Rationale: Increased airway Na+ absorption mediated by epithelial Na1 channels (ENaC) is a characteristic abnormality in the pathogenesis of cystic fibrosis (CF) lung disease. However, inhalation therapy with the ENaC blocker amiloride did not have therapeutic benefits in patients with CF with established lung disease. Objectives: We hypothesized that preventive inhibition of increased Na+ absorption in a structurally normal lung may be required for effective therapy of CF lung disease in vivo, and that therapeutic effects of late amiloride intervention may be impeded by the chronic disease process. Methods: To test this hypothesis in vivo, we used the βENaC-overexpression mouse as a model of CF lung disease and determined therapeutic effects of preventive versus late amiloride therapy on survival, airway mucus plugging, chronic bronchitis, and airway remodeling. Measurements and Main Results: We show that early intervention, i.e., from the first day of life, with the intranasal administration of amiloride significantly reduced pulmonary mortality, airway mucus obstruction, epithelial necrosis, goblet cell metaplasia, and airway inflammation in βENaC-overexpressing mice. In contrast, consistent with previous human trials in patients with CF, amiloride administration did not have benefits if treatment was started after the development of CF-like lung disease in bENaC-overexpressing mice. Conclusions: We conclude that preventive inhibition of increased airway Na+ absorption provides an effective therapy for CF-like lung diseasein vivo. These results suggest thatamiloride therapymaybean effective preventive therapy for patients with CF if initiated early in life before the onset of lung disease

Hypoxic Epithelial Necrosis Triggers Neutrophilic Inflammation via IL-1 Receptor Signaling in Cystic Fibrosis Lung Disease

Rationale: In many organs, hypoxic cell death triggers sterile neutrophilic inflammation via IL-1R signaling. Although hypoxia is common in airways from patients with cystic fibrosis (CF), its role in neutrophilic inflammation remains unknown. We recently demonstrated that hypoxic epithelial necrosis caused by airway mucus obstruction precedes neutrophilic inflammation in Scnn1b-transgenic (Scnn1b-Tg) mice with CF-like lung disease