Cystic Fibrosis Mouse Model Research Articles

640 The cystic fibrosis mouse model resource center

640 The cystic fibrosis mouse model resource center

The circadian system in cystic fibrosis mice is regulated by histone deacetylase 6.

Disordered sleep experienced by people with cystic fibrosis (CF) suggest a possible disruption in circadian regulation being associated with the loss of cystic fibrosis transmembrane conductance regulator (Cftr) function. To test this hypothesis, circadian regulation was assessed in an F508del/F508del CF mouse model. CF mice exhibited significant alterations in both timing of locomotor activity and in mean activity per hour in both light-dark (LD) and dark-dark (DD) photoperiods compared with wild-type (WT) controls. It was also noted that in DD periodicity increased in CF mice, whereas shortening in WT mice as is expected. CF mice also exhibited altered timing of circadian gene expression and a reduction of melatonin production at all time points. Mechanistically, the role of microtubules in regulating these outcomes was explored. Mice lacking expression of tubulin polymerization promoting protein (Tppp) effectively mimicked CF mouse phenotypes with each measured outcome. Depleting expression of the microtubule regulatory protein histone deacetylase 6 (Hdac6) from CF mice (CF/Hdac6) resulted in the reversal of each phenotype to WT profiles. These data demonstrate an innate disruption of circadian regulation in CF mice and identify a novel microtubule-related mechanism leading to this disruption that can be targeted for therapeutic intervention.

Epithelial cell-specific role of HMGB1 in murine lungs with muco-obstructive lung disease

Abstract Introduction Mucoobstructive lung diseases are characterized by defective mucociliary clearance, mucin hypersecretion, and mucoobstruction. High mobility group box 1 protein (HMGB1) plays a key role as an inflammatory mediator. However, the role of HMGB1 in mucoobstructive lung diseases remains unclear. Using Scnn1b-Tg+ mice, a mouse model of cystic fibrosis, we hypothesized that the airway epithelial cell-specific HMGB1 acts as an anti-inflammatory mediator in the Scnn1b-Tg+ lungs. Methods Airway epithelial cell-specific HMGB1-deficient (CCSP-iCre+/Hmgb1flox/flox) and control (CCSP-iCre− /Hmgb1flox/flox) mice were generated. The bronchoalveolar lavage fluid (BALF) and lung tissue were collected for endpoints analyses. Results Compared with wild-type (WT) mice, HMGB1 expression was significantly increased in BALF and airway epithelial cells of Scnn1b-Tg+ mice. Unlike HMGB1-sufficient Scnn1b-Tg+ mice, HMGB1-deficient Scnn1b-Tg+ mice exhibited enhanced lung inflammation evident from the elevated total protein and dsDNA contents in the BALF. HMGB1 deletion in airway epithelial cells in Scnn1b-Tg+ mice also exaggerated immune cell recruitment, which was accompanied by increased levels of chemokines and cytokines, including KC, G-CSF, MCP-1, MIP-2, MIP-1α, MIP-1β, and IP-10. Furthermore, HMGB1 deletion in airway epithelial cells in Scnn1b-Tg+ mice enhanced the type 2 inflammation manifested by increased levels of Th2 cytokines such as IL-4 and IL-5. Additionally, HMGB1-deficient Scnn1b-Tg+ mice showed increased airway mucus plugging and impaired bacterial clearance. Conclusion Epithelial cell-derived HMGB1 may play an anti-inflammatory role in murine lungs with mucoobstructive lung disease. Supported by NIEHS (RO1, ES030125)

Recruitment of monocytes primed to express heme oxygenase-1 ameliorates pathological lung inflammation in cystic fibrosis

Overwhelming neutrophilic inflammation is a leading cause of lung damage in many pulmonary diseases, including cystic fibrosis (CF). The heme oxygenase-1 (HO-1)/carbon monoxide (CO) pathway mediates the resolution of inflammation and is defective in CF-affected macrophages (MΦs). Here, we provide evidence that systemic administration of PP-007, a CO releasing/O2 transfer agent, induces the expression of HO-1 in a myeloid differentiation factor 88 (MyD88) and phosphatidylinositol 3-kinase (PI3K)/protein kinase B (AKT)-dependent manner. It also rescues the reduced HO-1 levels in CF-affected cells induced in response to lipopolysaccharides (LPS) or Pseudomonas aeruginosa (PA). Treatment of CF and muco-obstructive lung disease mouse models with a single clinically relevant dose of PP-007 leads to effective resolution of lung neutrophilia and to decreased levels of proinflammatory cytokines in response to LPS. Using HO-1 conditional knockout mice, we show that the beneficial effect of PP-007 is due to the priming of circulating monocytes trafficking to the lungs in response to infection to express high levels of HO-1. Finally, we show that PP-007 does not compromise the clearance of PA in the setting of chronic airway infection. Overall, we reveal the mechanism of action of PP-007 responsible for the immunomodulatory function observed in clinical trials for a wide range of diseases and demonstrate the potential use of PP-007 in controlling neutrophilic pulmonary inflammation by promoting the expression of HO-1 in monocytes/macrophages.

Investigating the Implications of CFTR Exon Skipping Using a Cftr Exon 9 Deleted Mouse Model.

Introduction: Severity and disease progression in people with Cystic Fibrosis (CF) is typically dependent on their genotype. One potential therapeutic strategy for people with specific mutations is exon skipping with antisense oligonucleotides (AO). CFTR exon 9 is an in-frame exon and hence the exclusion of this exon would excise only 31 amino acids but not alter the reading frame of the remaining mRNA. Splice mutations 1209 + 1 G > C and 1209 + 2 T > G were documented to cause CFTR exon 9 skipping and these variants were reported to manifest as a milder CF disease, therefore exon 9 skipping could be beneficial for people with class I mutations that affect exon 9 such as p.Trp401X. While the impact of exon 9 skipping on gene expression and cellular pathways can be studied in cells in vitro, trace amount of full-length normal or mutated material could confound the evaluation. To overcome this limitation, the impact of CFTR exon 9 skipping on disease phenotype and severity is more effectively evaluated in a small animal model. It was hypothesised that antisense oligonucleotide-mediated skipping this particular exon could result in a “mild mouse CF phenotype”. Methods: Cftr exon 9 deleted mice were generated using homologous recombination. Survival of homozygous (Cftr Δ9/Δ9 ) and heterozygous (Cftr Δ9/+ ) mice was compared to that of other CF mouse models, and lung and intestinal organ histology examined for any pathologies. Primary airway epithelial cells (pAECs) were harvested from Cftr Δ9/Δ9 mice and cultured at the Air Liquid Interface for CFTR functional assessment using Ussing Chamber analysis. Results: A Cftr Δ9/Δ9 mouse model presented with intestinal obstructions, and at time of weaning (21 days). Cftr Δ9/Δ9 mice had a survival rate of 83% that dropped to 38% by day 50. Histological sections of the small intestine from Cftr Δ9/Δ9 mice showed more goblet cells and mucus accumulation than samples from the Cftr Δ9/+ littermates. Airway epithelial cell cultures established from Cftr Δ9/Δ9 mice were not responsive to forskolin stimulation. Summary: The effect of Cftr exon 9 deletion on Cftr function was assessed and it was determined that the encoded Cftr isoform did not result in a milder “mouse CF disease phenotype,” suggesting that Cftr exon 9 is not dispensable, although further investigation in human CF pAECs would be required to confirm this observation.

Bicarbonate transport of airway surface epithelia in luminally perfused mice bronchioles

HCO3− secretion in distal airways is critical for airway mucosal defense. HCO3−/H+ transport across the apical membrane of airway surface epithelial cells was studied by measuring intracellular pH in luminally microperfused freshly dissected mice bronchioles. Functional studies demonstrated that CFTR, ENaC, Cl−–HCO3− exchange, Na+-H+ exchange, and Na+–HCO3− cotransport are involved in apical HCO3−/H+ transport. RT-PCR of isolated bronchioles detected fragments from Cftr, α, β, γ subunits of ENaC, Ae2, Ae3, NBCe1, NBCe2, NBCn1, NDCBE, NBCn2, Nhe1, Nhe2, Nhe4, Nhe5, Slc26a4, Slc26a6, and Slc26a9. We assume that continuous decline of intracellular pH following alkaline load demonstrates time course of HCO3− secretion into the lumen which is perfused with a HCO3−-free solution. Forskolin-stimulated HCO3− secretion was substantially inhibited by luminal application of CFTRinh-172 (5 μM), H2DIDS (200 μM), and amiloride (1 μM). In bronchioles from a cystic fibrosis mouse model, basal and acetylcholine-stimulated HCO3− secretion was substantially impaired, but forskolin transiently accelerated HCO3− secretion of which the magnitude was comparable to wild-type bronchioles. In conclusion, we have characterized apical HCO3−/H+ transport in native bronchioles. We have demonstrated that cAMP-mediated and Ca2+-mediated pathways are involved in HCO3− secretion and that apical HCO3− secretion is largely mediated by CFTR and H2DIDS-sensitive Cl−–HCO3− exchanger, most likely Slc26a9. The impairment of HCO3− secretion in bronchioles from a cystic fibrosis mouse model may be related to the pathogenesis of early lung disease in cystic fibrosis.

INTESTINAL EPITHELIAL CELL-SPECIFIC CFTR KNOCKOUT MICE EXHIBIT FECAL MICROBIAL DYSBIOSIS

Abstract BACKGROUND Chronic intestinal inflammation is a poorly understood manifestation of Cystic Fibrosis (CF) disease. Fecal microbial dysbiosis has the potential of inducing intestinal inflammation and has been reported in people with CF as well as CF mouse models. CF mice consuming an osmotic polyethylene glycol (PEG) laxative in drinking water to prevent intestinal obstruction have low levels of intestinal inflammation and low intestinal bacterial loads. In contrast, CF mice consuming a nutritionally complete liquid diet to prevent intestinal impaction exhibit intestinal inflammation and high intestinal bacterial loads (R. C. De Lisle, et al., Am J Physiol 293, G577-G584, 2007) To investigate the development of dysbiosis in a CFTR-deficient intestine, we transitioned adult intestinal epithelial cell-specific knockout and wild-type (WT) mice from life-long consumption of PEG laxative to a nutritionally-complete liquid diet for a two week period before collection of fecal samples. METHODS Fecal samples collected from B6.Cg-Tg(Vil1-cre)-Cftrf10/f10 intestinal-specific Cftr knockout mice (iCftr KO) and their WT sex-matched littermates were DNA extracted and prepared for 16S rRNA sequencing and evaluation of the microbiome. Microbial community composition, richness and diversity indices, and relative abundance of bacterial species of interest were evaluated. RESULTS 16S rRNA sequencing and metagenomic analysis revealed significant differences in microbial composition with intestinal-specific loss of CFTR as compared to WT, as well as a significant decrease in Shannon diversity and Chao-1 richness indices. A significant deficit of taxa was seen in the intestinal-specific CF mice, as compared to WT, which corresponded with a significant increase in bacterial species that potentially serve as provocateurs of intestinal inflammation including Helicobacter typhlonius, Clostridium perfringens, Ruminococcus gnavus, and Tyzerella spp. CONCLUSIONS As compared to WT, the transition from PEG laxative to a nutritionally-complete liquid diet resulted in overt differences in the fecal microbiota composition in iCftr KO mice which included enrichment of potential bacterial pathobionts capable of stimulating intestinal inflammation. These studies suggest that the CFTR-deficient intestinal epithelium provides an environment selective for potential bacterial pathobionts. The paradigm of the study may prove useful for investigating the development of dysbiosis and corresponding changes in intestinal mucosal immunity.

INTESTINAL EPITHELIAL CELL-SPECIFIC CFTR KNOCKOUT MICE EXHIBIT FECAL MICROBIAL DYSBIOSIS

Chronic intestinal inflammation is a poorly understood manifestation of Cystic Fibrosis (CF) disease. Fecal microbial dysbiosis has the potential of inducing intestinal inflammation and has been reported in people with CF as well as CF mouse models. CF mice consuming an osmotic polyethylene glycol (PEG) laxative in drinking water to prevent intestinal obstruction have low levels of intestinal inflammation and low intestinal bacterial loads. In contrast, CF mice consuming a nutritionally complete liquid diet to prevent intestinal impaction exhibit intestinal inflammation and high intestinal bacterial loads (R.

Might Routine Vitamin A Monitoring in Cystic Fibrosis Patients Reduce Virus-Mediated Lung Pathology?

Cystic fibrosis (CF) is an autosomal recessive gene disorder that affects tens of thousands of patients worldwide. Individuals with CF often succumb to progressive lung disease and respiratory failure following recurrent infections with bacteria. Viral infections can also damage the lungs and heighten the CF patient’s susceptibility to bacterial infections and long-term sequelae. Vitamin A is a key nutrient important for immune health and epithelial cell integrity, but there is currently no consensus as to whether vitamin A should be monitored in CF patients. Here we evaluate previous literature and present results from a CF mouse model, showing that oral vitamin A supplements significantly reduce lung lesions that would otherwise persist for 5-6 weeks post-virus exposure. Based on these results, we encourage continued research and suggest that programs for the routine monitoring and regulation of vitamin A levels may help reduce virus-induced lung pathology in CF patients.

386: Distinct lung characteristics in experimental mouse model of chronic cystic fibrosis–related diabetes

386: Distinct lung characteristics in experimental mouse model of chronic cystic fibrosis–related diabetes

661: W1282X cystic fibrosis mouse models for examining in vivo nonsense mutation correction

661: W1282X cystic fibrosis mouse models for examining in vivo nonsense mutation correction

Postnatal Ozone Exposure Disrupts Alveolar Development, Exaggerates Mucoinflammatory Responses, and Suppresses Bacterial Clearance in Developing Scnn1b-Tg+ Mice Lungs

Increased levels of ambient ozone, one of the six criteria air pollutants, result in respiratory tract injury and worsening of ongoing lung diseases. However, the effect of ozone exposure on the respiratory tract undergoing active lung development and simultaneously experiencing mucoinflammatory lung diseases, such as cystic fibrosis, remains unclear. To address these questions, we exposed Scnn1b transgenic (Scnn1b-Tg+) mice, a mouse model of cystic fibrosis-like lung disease, and littermate wild-type (WT) mice to ozone from postnatal days (PND) 3-20 and examined the lung phenotypes at PND21. As compared with filtered air (FA)-exposed WT mice, the ozone-exposed WT mice exhibited marked alveolar space enlargement, in addition to significant eosinophilic infiltration, type 2 inflammation, and mucous cell metaplasia. Ozone-exposed Scnn1b-Tg+ mice also exhibited significantly increased alveolar space enlargement, which was also accompanied by exaggerated granulocytic infiltration, type 2 inflammation, and a greater degree of mucus obstruction. The alveolar space enlargement in ozone-exposed WT, FA-exposed Scnn1b-Tg+, and ozone-exposed Scnn1b-Tg+ mice was accompanied by elevated levels of MMP12 protein in macrophages and Mmp12 mRNA in the lung homogenates. Finally, although bacterial burden was largely resolved by PND21 in FA-exposed Scnn1b-Tg+ mice, ozone-exposed Scnn1b-Tg+ mice exhibited compromised bacterial clearance, which was also associated with increased levels of IL-10, an immunosuppressive cytokine, and marked mucus obstruction. Taken together, our data show that ozone exposure results in alveolar space remodeling during active phases of lung development and markedly exaggerates the mucoinflammatory outcomes of pediatric-onset lung disease, including bacterial infections, granulocytic inflammation, mucus obstruction, and alveolar space enlargement.

CFTR regulates embryonic T lymphopoiesis via Wnt signaling in zebrafish

The number and function of T cells are abnormal as observed in cystic fibrosis (CF) patients and CF mouse models, and our previous work shows that the CFTR mutant leads to deficiency of primitive and definitive hematopoietic in zebrafish. However, the functions and underlying mechanisms of CFTR in T cell development during early embryogenesis have not been explored. Here, we report that the genetic ablation of CFTR in zebrafish resulted in abrogated embryonic T lymphopoiesis, which was ascribed to impaired thymic homing and expansion of hematopoietic stem cells (HSCs). Transcriptome analysis of isolated HSCs in zebrafish embryos at 48 hpf showed a significant alteration of key factors essential for T cell development and Wnt signaling, consistent with our previous work on CFTR regulating hematopoiesis. In brief, we uncovered the function of CFTR in embryonic T cell development and suggest that the immune deficiency of CF patients may originate from an early embryonic stage.

Impaired cholesterol metabolism in the mouse model of cystic fibrosis. A preliminary study.

This study aims to investigate cholesterol metabolism in a mouse model with cystic fibrosis (CF) by the comparison of affected homozygous versus wild type (WT) mice. In particular, we evaluated the effects of a diet enriched with cholesterol in both mice groups in comparison with the normal diet. To this purpose, beyond serum and liver cholesterol, we analyzed serum phytosterols as indirect markers of intestinal absorption of cholesterol, liver lathosterol as indirect marker of de novo cholesterol synthesis, liver cholestanol (a catabolite of bile salts synthesis) and the liver mRNA levels of LDL receptor (LDLR), 3-hydroxy-3-methylglutaryl-CoA reductase (HMG-CoAR), acyl CoA:cholesterol acyl transferase 2 (ACAT2), cytochrome P450 7A1 (CYP7A1) and tumor necrosis factor alpha (TNFα). CF mice showed lower intestinal absorption and higher liver synthesis of cholesterol than WT mice. In WT mice, the cholesterol supplementation inhibits the synthesis of liver cholesterol and enhances its catabolism, while in CF mice we did not observe a reduction of LDLR and HMG-CoAR expression (probably due to an altered feed-back), causing an increase of intracellular cholesterol. In addition, we observed a further increase (5-fold) in TNFα mRNA levels. This preliminary study suggests that in CF mice there is a vicious circle in which the altered synthesis/secretion of bile salts may reduce the digestion/absorption of cholesterol. As a result, the liver increases the biosynthesis of cholesterol that accumulates in the cells, triggering inflammation and further compromising the metabolism of bile salts.

WS07.4 Development of a humanised cystic fibrosis mouse model

WS07.4 Development of a humanised cystic fibrosis mouse model

1635. Oral Delivery of Amikacin-Lipid NanoCrystal Formulations Safely and Effectively Treat Macrolide Resistant Mycobacteria Infections in a Mouse Model of Cystic Fibrosis

BackgroundIn the cystic fibrosis lung, infections by intracellular pathogens, such as Mycobacteria, are problematic to treat due to a thick buildup of mucous as well as the difficulty of many anti-microbial agents, such as amikacin, to penetrate across the plasma membranes of infected cells. Lipid NanoCrystals (LNCs), mediate oral bioavailability for injectable drugs, reduce toxicity, and significantly enhance targeting to mycobacterial infected cells followed by intracellular drug delivery.MethodsThe oral efficacy of Amikacin-LNC (AmK-LNC) was evaluated in the cystic fibrosis (B6CFTRtm1UNC/CFTRtm1UNC) chronic mouse model against each of the three NTM strains having high resistance to macrolide antibiotics (M. avium subsp intracellulare 25292, M. abscesus ssp abscessus 1513, and M. abscessus ssp bolletii 1948). Mice were infected with a pulmonary aerosol of 1x108 CFUs of the macrolide resistant strain and treated daily starting on day 28 for a total of 8 weeks with saline control, oral LP-4 CAmK Lyophilized 50 mg/kg BID, oral LP-4 CAMK Lyophilized 100 mg/kg BID, IP Amikacin (AMI) 150 mg/kg QD, or oral Clarithromycin 250 mg/kg QD. Bacterial burden was measured on day 1, 27, 42, 56 and 84 after infection by plating serial dilutions of organ homogenates on nutrient 7H11 and charcoal agar and counting CFUs after 25-30 days incubation at 32°C. Results represent the average of six experiments (n=5 mice per experiment) bacterial load was expressed as the average Log10 CFU (± SEM) cells (± SEM). ANOVA, saline control compared to drug-treated groups, * denotes the compound that resulted in the highest bacterial reduction, *p< 0.05.ResultsOral administration of AmK-LNCs safely and effectively treated all three macrolide resistant Mycobacteria infections. Colony counts showed that oral administration of AmK-LNC resulted in CFU lung, spleen and liver counts lower than treatment with IP amikacin or clarithromycin.Lung pathology showed that lesions were more numerous and larger in infected mice treated with clarithromycin or amikacin compared to the smaller lesions after treatment with oral AmK-LNC.Bacterial Counts in the Lungs (A), Spleens (B) and Livers (C) Lung Pathology ConclusionConclusionsOral administration of amikacin-LNCs safely and effectively treats macrolide resistant mycobacterial infections in a mouse model of Cystic Fibrosis.DisclosuresRuying Lu, n/a, Matinas BioPharma Inc. (Employee)Matinas BioPharma Inc. (Employee, Shareholder) Raphael J. Mannino, n/a, Matinas BioPharma Inc. (Employee, Shareholder)

Alleviation of depression-like behavior in a cystic fibrosis mouse model by Hdac6 depletion

Cystic fibrosis (CF) patients experience heightened levels of anxiety and depression. Stress from dealing with chronic disease and rigorous treatment regimens certainly are primary contributors to these outcomes. We previously have demonstrated that microtubule alterations in CF are linked to a number of CF phenotypes including growth regulation and inflammatory responses to airway bacterial challenge. Deletion of histone deactelyase 6 (HDAC6), a cytosolic deacetylase that regulates tubulin acetylation, in CF mice restores growth and inflammatory phenotypes to wild type (WT) profiles. In this study, the hypothesis that Hdac6 depletion in CF mice would impact behaviors since Hda6 inhibition has been previously reported to have anti-depressive properties. Data demonstrate that CF mice exhibit reduced activity and reduced open arm time in an elevated plus maze test which can be consistent with anxiety-like behavior. CF mice also exhibit depression-like behaviors compared to WT mice in an age dependent manner. By eight weeks of age, CF mice exhibit significantly more immobile time in the tail-suspension test, however, Hdac6 depletion reverses the depressive phenotype. These data demonstrate that loss of CFTR function may predispose patients to experience depression and that this behavior is Hdac6 dependent.

CFTR dysregulation drives active selection of the gut microbiome.

Patients with cystic fibrosis (CF) have altered fecal microbiomes compared to those of healthy controls. The magnitude of this dysbiosis correlates with measures of CF gastrointestinal (GI) disease, including GI inflammation and nutrient malabsorption. However, whether this dysbiosis is caused by mutations in the CFTR gene, the underlying defect in CF, or whether CF-associated dysbiosis augments GI disease was not clear. To test the relationships between CFTR dysfunction, microbes, and intestinal health, we established a germ-free (GF) CF mouse model and demonstrated that CFTR gene mutations are sufficient to alter the GI microbiome. Furthermore, flow cytometric analysis demonstrated that colonized CF mice have increased mesenteric lymph node and spleen TH17+ cells compared with non-CF mice, suggesting that CFTR defects alter adaptive immune responses. Our findings demonstrate that CFTR mutations modulate both the host adaptive immune response and the intestinal microbiome.

Real-time in vivo imaging of regional lung function in a mouse model of cystic fibrosis on a laboratory X-ray source

Most measures of lung health independently characterise either global lung function or regional lung structure. The ability to measure airflow and lung function regionally would provide a more specific and physiologically focused means by which to assess and track lung disease in both pre-clinical and clinical settings. One approach for achieving regional lung function measurement is via phase contrast X-ray imaging (PCXI), which has been shown to provide highly sensitive, high-resolution images of the lungs and airways in small animals. The detailed images provided by PCXI allow the application of four-dimensional X-ray velocimetry (4DxV) to track lung tissue motion and provide quantitative information on regional lung function. However, until recently synchrotron facilities were required to produce the highly coherent, high-flux X-rays that are required to achieve lung PCXI at a high enough frame rate to capture lung motion. This paper presents the first translation of 4DxV technology from a synchrotron facility into a laboratory setting by using a liquid-metal jet microfocus X-ray source. This source can provide the coherence required for PCXI and enough X-ray flux to image the dynamics of lung tissue motion during the respiratory cycle, which enables production of images compatible with 4DxV analysis. We demonstrate the measurements that can be captured in vivo in live mice using this technique, including regional airflow and tissue expansion. These measurements can inform physiological and biomedical research studies in small animals and assist in the development of new respiratory treatments.

Optical Nanosensors for in vivo Physiological Chloride Detection for Monitoring Cystic Fibrosis Treatment.

Personalized approaches for continuous monitoring of chloride levels are potentially valuable for evaluating the efficacy of new treatments of genetic disorders such as cystic fibrosis. In this report, we validated optode-based nanosensors for real-time chloride monitoring in the interstitial fluid of living animals. These nanosensors take advantage of a ratiometric sensing scheme which demonstrates reversible and selective chloride detection in the physiological range. We further investigate how skin pigmentation affects the sensor performance during in vivo fluorescence imaging. We successfully monitored endogenous chloride changes using nanosensors during pharmacological treatment in a cystic fibrosis mouse model. We believe this platform is a valuable tool for chloride detection which could assess the efficacy of new treatments for cystic fibrosis.