Disease phenotype of a ferret CFTR-knockout model of cystic fibrosis

TLDR

Cystic fibrosis is a recessive disorder affecting multiple organs and caused by CFTR mutations, but animal models have been difficult due to species‑ and strain‑specific differences. The study reports the phenotype of a CFTR‑knockout ferret model and generates gut‑corrected transgenic kits to mitigate severe intestinal disease. The authors generated CFTR‑knockout ferrets and engineered four gut‑corrected transgenic lines expressing ferret CFTR only in the intestine. Neonatal CFTR‑knockout ferrets recapitulated key human CF phenotypes—including defective airway chloride transport, variable meconium ileus, pancreatic, liver, and vas deferens disease, and early lung infection—while severe gastrointestinal malabsorption caused death in those without MI; ursodeoxycholic acid and a proton‑pump inhibitor improved liver function, weight gain, and survival, and one gut‑corrected clone passed feces normally without lung or liver CFTR expression, demonstrating the model’s utility for dissecting CF pathogenesis and developing treatments.

Abstract

Cystic fibrosis (CF) is a recessive disease that affects multiple organs. It is caused by mutations in CFTR. Animal modeling of this disease has been challenging, with species- and strain-specific differences in organ biology and CFTR function influencing the emergence of disease pathology. Here, we report the phenotype of a CFTR-knockout ferret model of CF. Neonatal CFTR-knockout ferrets demonstrated many of the characteristics of human CF disease, including defective airway chloride transport and submucosal gland fluid secretion; variably penetrant meconium ileus (MI); pancreatic, liver, and vas deferens disease; and a predisposition to lung infection in the early postnatal period. Severe malabsorption by the gastrointestinal (GI) tract was the primary cause of death in CFTR-knockout kits that escaped MI. Elevated liver function tests in CFTR-knockout kits were corrected by oral administration of ursodeoxycholic acid, and the addition of an oral proton-pump inhibitor improved weight gain and survival. To overcome the limitations imposed by the severe intestinal phenotype, we cloned 4 gut-corrected transgenic CFTR-knockout kits that expressed ferret CFTR specifically in the intestine. One clone passed feces normally and demonstrated no detectable ferret CFTR expression in the lung or liver. The animals described in this study are likely to be useful tools for dissecting CF disease pathogenesis and developing treatments.