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Generation of Alpha-1 Antitrypsin Knockout and PIZZ Ferrets Using Crispr/Cas9. A Genetic Model of Emphysema
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Generation of Alpha-1 Antitrypsin Knockout and PIZZ Ferrets Using Crispr/Cas9. A Genetic Model of Emphysema

Nan He, Bradley H Rosen, Jaimie S Gray, Idil A Evans, Marina Zieger, Ziying Yan, Florie Borel, Bo Liang, Xingshen Sun, Shashanna R Moll, …
Annals of the American Thoracic Society, Vol.15(Suppl 4), pp.S292-S293
12/2018
DOI: 10.1513/AnnalsATS.201806-429MG
PMCID: PMC6321996
PMID: 30758999
url
https://doi.org/10.1513/AnnalsATS.201806-429MGView
Published (Version of record) Open Access

Abstract

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  < 0.05). Progression of these disease parameters and pressure–volume loop disturbances increased with age (oldest are ∼2 yr). The bronchoalveolar lavage (BAL) proteome of KO animals confirmed absence of A1AT protein along with elevated soluble Muc5AC (Log 2 fold change, 6.74; P  < 0.001). Active neutrophil elastase was elevated in A1AT-KO versus WT BAL (292 ± 82 vs. 179 ± 17 ng/ml) but did not reach significance; in one experiment, active NE was sixfold higher in the upper lobe of the A1AT than the lower (1,240 vs. 209 ng/ml). Quantitative alveolar morphometry in one A1AT was 121% of its matched WT control. The PI*ZZ animals are entering studies at several months of age. Conclusions: Our findings suggest that A1AT-deficient ferrets spontaneously develop anatomic and physiologic aspects of progressive lung disease consistent with emphysema and chronic bronchitis.
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