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Classical interpretation of cystic fibrosis (CF) lung disease pathogenesis suggests that infection initiates disease progression, leading to an exuberant inflammatory response, excessive mucus, and ultimately bronchiectasis. Although symptomatic antibiotic treatment controls lung infections early in disease, lifelong bacterial residence typically ensues. Processes that control the establishment of persistent bacteria in the CF lung, and the contribution of noninfectious components to disease pathogenesis, are poorly understood.To evaluate whether continuous antibiotic therapy protects the CF lung from disease using a ferret model that rapidly acquires lethal bacterial lung infections in the absence of antibiotics.CFTR (cystic fibrosis transmembrane conductance regulator)-knockout ferrets were treated with three antibiotics from birth to several years of age and lung disease was followed by quantitative computed tomography, BAL, and histopathology. Lung disease was compared with CFTR-knockout ferrets treated symptomatically with antibiotics.Bronchiectasis was quantified from computed tomography images. BAL was evaluated for cellular differential and features of inflammatory cellular activation, bacteria, fungi, and quantitative proteomics. Semiquantitative histopathology was compared across experimental groups. We demonstrate that lifelong antibiotics can protect the CF ferret lung from infections for several years. Surprisingly, CF animals still developed hallmarks of structural bronchiectasis, neutrophil-mediated inflammation, and mucus accumulation, despite the lack of infection. Quantitative proteomics of BAL from CF and non-CF pairs demonstrated a mucoinflammatory signature in the CF lung dominated by Muc5B and neutrophil chemoattractants and products.These findings implicate mucoinflammatory processes in the CF lung as pathogenic in the absence of clinically apparent bacterial and fungal infections.

Cystic fibrosis (CF) is a multiorgan disease caused by mutations in the cystic fibrosis transmembrane conductance regulator ( CFTR ). In patients with CF, abnormalities initiate in several organs before birth. However, the long-term impact of these in utero pathologies on disease pathophysiology is unclear. To address this issue, we generated ferrets harboring a VX-770 (ivacaftor)–responsive CFTR G551D mutation. In utero VX-770 administration provided partial protection from developmental pathologies in the pancreas, intestine, and male reproductive tract. Homozygous CFTR G551D/G551D animals showed the greatest VX-770–mediated protection from these pathologies. Sustained postnatal VX-770 administration led to improved pancreatic exocrine function, glucose tolerance, growth and survival, and to reduced mucus accumulation and bacterial infections in the lung. VX-770 withdrawal at any age reestablished disease, with the most rapid onset of morbidity occurring when withdrawal was initiated during the first 2 weeks after birth. The results suggest that CFTR is important for establishing organ function early in life. Moreover, this ferret model provides proof of concept for in utero pharmacologic correction of genetic disease and offers opportunities for understanding CF pathogenesis and improving treatment.

Rationale: The most prevalent genetic cause of chronic obstructive pulmonary disease is alpha-1 antitrypsin (A1AT) deficiency, a disorder that has yet to be widely modeled in animals because of species-specific differences between rodents and humans. Objectives: To address these challenges, we engineered two A1AT ferret models using zygote gene editing to test the hypothesis that unopposed protease activity within the lung leads to emphysema and bronchitis. Methods: Guide RNAs targeting exon 2 (for knockout) and exon 5 (for Z-allele mutation, Pi*Z) of the ferret A1AT gene were injected into ferret zygotes with Cas9 mRNA. For PI*Z targeting, a short oligonucleotide carrying the mutation was included. Offspring were genotyped and plasma levels of A1AT determined by Western blot before entry into a longitudinal study. Adult A1AT ferrets underwent bronchoscopy and FlexiVent over time to characterize lung disease. Control animals were wild-type (WT) and age, sex, and size matched. Results: A1AT-deficient ferrets spontaneously develop hallmarks of emphysema as early as 3 months when compared with matched WT control ferrets. Over time, A1AT-KO ferrets reached an inspiratory capacity of 117% ± 5% (WT, 57.4 ml; A1AT, 67.5 ml) and compliance of 111% ± 4% (WT, 5.5 ml/cm H(2)O; A1AT, 6.1 ml/cm H(2)O; N = 8 pairs A1AT/WT, P