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Sun, X. et al. Disease phenotype of a ferret CFTR-knockout model of cystic fibrosis. J Clin Invest 120, 3149-3160

Department of Anatomy and Cell Biology, Carver College of Medicine, University of Iowa, Iowa City, Iowa 52242, USA.
The Journal of clinical investigation (Impact Factor: 13.77). 09/2010; 120(9):3149-60. DOI: 10.1172/JCI43052
Source: PubMed

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.

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    • "The anatomical and physiological similarity between human and ferret lungs also enables ferrets to be used as a model to study lung carcinomas (reviewed in Baric et al., 2013). Recently, absence of the cystic fibrosis transmembrane conductance regulator (CFTR) was associated with spontaneous disease induction in the lung and pancreas in ferrets, showing similar pathology to that of cystic fibrosis in humans (Sun et al., 2010, reviewed in Keiser and Engelhardt, 2011). The broad utility of this model is highlighted by the use of ferrets to study pneumococcal transmission, reproductive biology and human fetal brain development (reviewed in Baric et al., 2013). "
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    ABSTRACT: The ferret is an excellent model for many human infectious diseases including influenza, SARS-CoV, henipavirus and pneumococcal infections. The ferret is also used to study cystic fibrosis and various cancers, as well as reproductive biology and physiology. However, the range of reagents available to measure the ferret immune response is very limited. To address this deficiency, high-throughput real time RT-PCR TaqMan assays were developed to measure the expression of fifteen immune mediators associated with the innate and adaptive immune responses (IFNα, IFNβ, IFNγ, IL1α, IL1β, IL2, IL4, IL6, IL8, IL10, IL12p40, IL17, Granzyme A, MCP1, TNFα), as well as four endogenous housekeeping genes (ATF4, HPRT, GAPDH, L32). These assays have been optimized to maximize reaction efficiency, reduce the amount of sample required (down to 1ng RNA per real time RT-PCR reaction) and to select the most appropriate housekeeping genes. Using these assays, the expression of each of the tested genes could be detected in ferret lymph node cells stimulated with mitogens or infected with influenza virus in vitro. These new tools will allow a more comprehensive analysis of the ferret immune responses following infection or in other disease states.
    Journal of virological methods 05/2014; 205. DOI:10.1016/j.jviromet.2014.04.014 · 1.88 Impact Factor
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    • "Other consequences of CFTR mutations in the intestine include an abnormal GI microbiota with altered diversity, location and density, and increased inflammation, which leads to ulcerations in 60% of CF patients as revealed by a new endoscopy technique relying on swallowed capsules (PillCam) (Werlin et al., 2010). Gene-targeted animal models (e.g., mice, pigs and ferrets) lacking CFTR or Cftr expression develop meconium ileus at birth, confirming the importance of CFTR in the GI tract (Rogers et al., 2008; Snouwaert et al., 1992; Sun et al., 2010). Cftr mutant mouse models, which include both Cftr point mutations (e.g., Cftr F508/F508 ) and complete Cftr knockouts (e.g., Cftr −/− ), have greatly contributed to our understanding of the GI manifestations of CF. "
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    ABSTRACT: Our current understanding of cystic fibrosis (CF) has revealed that the biophysical properties of mucus play a considerable role in the pathogenesis of the disease in view of the fact that most mucus-producing organs are affected in CF patients. In this review, we discuss the potential causal relationship between altered cystic fibrosis transmembrane conductance regulator (CFTR) function and the production of mucus with abnormal biophysical properties in the intestine and lungs, highlighting what has been learned from cell cultures and animal models that mimic CF pathogenesis. A similar cascade of events, including mucus obstruction, infection and inflammation, is common to all epithelia affected by impaired surface hydration. Hence, the main structural components of mucus, namely the polymeric, gel-forming mucins, are critical to the onset of the disease. Defective CFTR leads to epithelial surface dehydration, altered pH/electrolyte composition and mucin concentration. Further, it can influence mucin transition from the intracellular to extracellular environment, potentially resulting in aberrant mucus gel formation. While defective HCO3(-) production has long been identified as a feature of CF, it has only recently been considered as a key player in the transition phase of mucins. We conclude by examining the influence of mucins on the biophysical properties of CF sputum and discuss existing and novel therapies aimed at removing mucus from the lungs.
    The international journal of biochemistry & cell biology 03/2014; 52. DOI:10.1016/j.biocel.2014.03.011 · 4.24 Impact Factor
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    • "The apparent decrease of 60% is even more striking when one considers that it is probably an underestimate, and that the rates would have been reduced more if normalized per unit area of epithelium to correct for 2-to 3-fold hypertrophy of CF glands. It is not immediately obvious why pilocarpine-induced secretion should be compromised in CF submucosal glands if it occurs via CaCCs, yet it is a consistent observation in glands from CF piglet trachea (Joo et al. 2010) and nasal turbinate (Cho et al. 2011), and tracheal xenografts (Sun et al. 2010). Pig glands exposed to the inhibitor CFTR inh -172 (Thiagarajah et al. 2004) also have diminished responses to cholinergic agonists. "
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    ABSTRACT: cAMP-stimulated anion conductance is defective in cystic fibrosis. The regulatory domain of CFTR, the anion channel protein encoded by the CF gene, possesses an unusually high density of consensus sequences for phosphorylation by PKA (14 in a stretch of <200 amino acids). Thus it is not surprising that CFTR is viewed primarily as a cAMP-stimulated anion channel, and most studies have focused on this mode of activation. However there is growing evidence that CFTR also responds to Ca2+ mobilizing secretagogues and contributes substantially to cholinergic and purinergic responses in native tissues. G protein coupled receptors that signal through Gαq can stimulate CFTR channels by activating Ca2+-dependent adenylyl cyclase and tyrosine kinases, and also by inhibiting PP2A. Here we review evidence for these novel mechanisms of CFTR activation and discuss how they may help explain previous observations.
    The Journal of Physiology 08/2013; 591(21). DOI:10.1113/jphysiol.2013.261909 · 4.54 Impact Factor
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