Clinical mechanism of the cystic fibrosis transmembrane conductance regulator potentiator ivacaftor in G551D-mediated cystic fibrosis

Neutrophil Membrane Cholesterol Content is a Key Factor in Cystic Fibrosis Lung Disease

Background

Identification of mechanisms promoting neutrophil trafficking to the lungs of patients with cystic fibrosis (CF) is a challenge for next generation therapeutics. Cholesterol, a structural component of neutrophil plasma membranes influences cell adhesion, a key step in transmigration. The effect of chronic inflammation on neutrophil membrane cholesterol content in patients with CF (PWCF) remains unclear. To address this we examined neutrophils of PWCF to evaluate the cause and consequence of altered membrane cholesterol and identified the effects of lung transplantation and ion channel potentiator therapy on the cellular mechanisms responsible for perturbed membrane cholesterol and increased cell adhesion.

Methodology

PWCF homozygous for the ΔF508 mutation or heterozygous for the G551D mutation were recruited (n = 48). Membrane protein expression was investigated by mass spectrometry. The effect of lung transplantation or ivacaftor therapy was assessed by ELISAs, and calcium fluorometric and μ-calpain assays.

Findings

Membranes of CF neutrophils contain less cholesterol, yet increased integrin CD11b expression, and respond to inflammatory induced endoplasmic reticulum (ER) stress by activating μ-calpain. In vivo and in vitro, increased μ-calpain activity resulted in proteolysis of the membrane cholesterol trafficking protein caveolin-1. The critical role of caveolin-1 for adequate membrane cholesterol content was confirmed in caveolin-1 knock-out mice. Lung transplant therapy or treatment of PWCF with ivacaftor, reduced levels of circulating inflammatory mediators and actuated increased caveolin-1 and membrane cholesterol, with concurrent normalized neutrophil adhesion.

Interpretation

Results demonstrate an auxiliary benefit of lung transplant and potentiator therapy, evident by a reduction in circulating inflammation and controlled neutrophil adhesion.

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This study explored neutrophil adhesion in cystic fibrosis.

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Altered membrane cholesterol lead to increased adhesion.

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Circulating inflammatory mediators caused increased calpain activity and reduced membrane cholesterol content.

In patients with cystic fibrosis (CF), chronic inflammation in the circulation, in part originating from the pulmonary compartment, leads to decreased membrane cholesterol in circulating neutrophils, resulting in increased cell adhesion. The mechanism of action involves proteolytic down-regulation of the cholesterol trafficking protein caveolin-1. The overall effect of lung transplant therapy, or CFTR potentiator treatment, was to significantly diminish the circulating inflammatory burden thereby permitting caveolin-1 expression, with concomitant decreased CF cell adhesion and significant clinical improvement.

Restoring Cystic Fibrosis Transmembrane Conductance Regulator Function Reduces Airway Bacteria and Inflammation in People with Cystic Fibrosis and Chronic Lung Infections

RATIONALE

Previous work indicates that ivacaftor improves cystic fibrosis transmembrane conductance regulator (CFTR) activity and lung function in people with cystic fibrosis and G551D-CFTR mutations but does not reduce density of bacteria or markers of inflammation in the airway. These findings raise the possibility that infection and inflammation may progress independently of CFTR activity once cystic fibrosis lung disease is established.

OBJECTIVES

To better understand the relationship between CFTR activity, airway microbiology and inflammation, and lung function in subjects with cystic fibrosis and chronic airway infections.

METHODS

We studied 12 subjects with G551D-CFTR mutations and chronic airway infections before and after ivacaftor. We measured lung function, sputum bacterial content, and inflammation, and obtained chest computed tomography scans.

MEASUREMENTS AND MAIN RESULTS

Ivacaftor produced rapid decreases in sputum Pseudomonas aeruginosa density that began within 48 hours and continued in the first year of treatment. However, no subject eradicated their infecting P. aeruginosa strain, and after the first year P. aeruginosa densities rebounded. Sputum total bacterial concentrations also decreased, but less than P. aeruginosa. Sputum inflammatory measures decreased significantly in the first week of treatment and continued to decline over 2 years. Computed tomography scans obtained before and 1 year after ivacaftor treatment revealed that ivacaftor decreased airway mucous plugging.

CONCLUSIONS

Ivacaftor caused marked reductions in sputum P. aeruginosa density and airway inflammation and produced modest improvements in radiographic lung disease in subjects with G551D-CFTR mutations. However, P. aeruginosa airway infection persisted. Thus, measures that control infection may be required to realize the full benefits of CFTR-targeting treatments.

Retrospective observational study of French patients with cystic fibrosis and a Gly551Asp-CFTR mutation after 1 and 2years of treatment with ivacaftor in a real-world setting

BACKGROUND

Ivacaftor has been shown to improve lung function and body weight in patients with CF and a gating mutation. Real-world evaluation is warranted to examine its safety and effectiveness over the long term.

METHODS

A retrospective observational multicentre study collected clinical data in the year before and the 2years after ivacaftor initiation in patients with CF and a Gly551Asp-CFTR mutation.

RESULTS

Fifty-seven patients were included. Mean absolute change in FEV₁% predicted improved from baseline to Year 1 (8.4%; p<0.001) and Year 2 (7.2%; p=0.006). Statistically significant benefits were observed with increased body mass index, fewer Pseudomonas aeruginosa and Staphylococcus aureus positive cultures, and decreased IV antibiotics and maintenance treatment prescriptions (including azithromycin, Dornase alpha and nutritional supplements). No significant adverse events were reported.

CONCLUSION

The clinical benefits of ivacaftor reported in previous clinical trials were confirmed in a real-world setting two years post-initiation, also reducing treatment burden.

CFTR-dependent chloride efflux in cystic fibrosis mononuclear cells is increased by ivacaftor therapy

AIM

The Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) potentiator ivacaftor (Kalydeco®) improves clinical outcome in G551D cystic fibrosis (CF) patients. Here, we have investigated whether ivacaftor has a clinical impact on non-G551D gating mutations and function of circulating leukocytes as well.

METHODS

Seven patients were treated with ivacaftor and evaluated at baseline, and at 1-3 and 6 months. Besides clinical and systemic inflammatory parameters, circulating mononuclear cells (MNC) were evaluated for CFTR-dependent chloride efflux by spectrofluorimetry, neutrophils for oxidative burst by cytofluorimetry and HVCN1 mRNA expression by real time PCR.

RESULTS

Ivacaftor determined a significant decrease in sweat chloride concentrations at all time points during treatment. Body mass index (BMI), FEV1 , and FVC showed an increasing trend. While C-reactive protein decreased significantly at 2 months, the opposite behavior was noticed for circulating monocytes. CFTR activity in MNC was found to increase significantly at 3 and 6 months. Neutrophil oxidative burst peaked at 2 months and then decreased to baseline. HVCN1 mRNA expression was significantly higher than baseline at 1-3 months and decreased after 6 months of treatment. The chloride efflux in MNC correlated positively with both FEV1 and FVC. On the other hand, sweat chloride correlated positively with CRP and WBC, and negatively with both respiratory function tests. A cluster analysis confirmed that sweat chloride, FEV1 , FVC, BMI, and MNC chloride efflux behaved as a single entity over time.

DISCUSSION

In patients with non-G551D mutations, ivacaftor improved both chloride transport in sweat ducts and chloride efflux in MNC, that is, functions directly imputed to CFTR.

Adherence and barriers to hyperinsufflation in children with congenital muscular dystrophy

BACKGROUND

Congenital muscular dystrophy (CMD) is a rare, inherited neuromuscular disease characterized by progressive muscle weakness, thoracic insufficiency, and ultimately respiratory failure. Adherence to respiratory therapies in children with neuromuscular disorders is unknown. This study examined the multimodal assessment of adherence and barriers to 15 min, twice daily hyperinsufflation in children with CMD. Adherence was hypothesized to be greater than 50% and discomfort, embarrassment, and difficulty finding time were hypothesized to be barriers.

METHODS

Participants included 18 children with CMD. Personalized hyperinsufflation settings were determined based on pressure-volume measurements at each study visit. Adherence was measured by a daily phone diary (DPD) and by electronic data download from the hyperinsufflation device. The DPD was conducted twice over a 48-hr period to capture a weekend and weekday, with the goal being 60 min of hyperinsufflation over the 48 hr (100% adherence). The hyperinsufflation objective electronic data reflected daily use of hyperinsufflation for the same 48-hr period. Data from DPD and the corresponding hyperinsufflation device data were used for analyses.

RESULTS

Adherence to hyperinsufflation was 40% via DPD and 44% for electronic data, with strong convergence between methods (r = 0.75, P < 0.001). Surprisingly, 53% of participants reported no barriers despite low adherence. Social distractions and family obligations were identified as barriers. There were no differences in adherence between those who did and did not endorse barriers to hyperinsufflation (DPD: t(13) = 0.44, P = n.s.; hyperinsufflation device: t(13) = -0.23, P = n.s.).

CONCLUSION

Adherence to hyperinsufflation is a significant problem in children with CMD and families have difficulty identifying adherence barriers. An important next step is to encourage open dialog around adherence barriers and promote adherence behaviors via intervention. Pediatr Pulmonol. 2017; 52:939-945. © 2016 Wiley Periodicals, Inc.

Recovery of lung function following a pulmonary exacerbation in patients with cystic fibrosis and the G551D-CFTR mutation treated with ivacaftor

BACKGROUND

Pulmonary exacerbations (PEx) are associated with acute loss of lung function that is often not recovered after treatment. We investigated lung function recovery following PEx for ivacaftor- and placebo-treated subjects.

METHODS

Short- and long-term pulmonary function recovery data after PEx were summarized from a placebo-controlled trial in 161 cystic fibrosis patients≥12years old with the G551D-CFTR mutation (NCT00909532). Short-term recovery was measured 2 to 8weeks after treatment, and long-term recovery was determined at the end-of-study, both compared with baseline measured just prior to the PEx.

RESULTS

Fewer patients receiving ivacaftor experienced a PEx than patients receiving placebo (33.7% vs. 56.4%; P=0.004) and had a lower adjusted incidence rate of PEx (0.589 vs. 1.382; P<0.001). The proportion of PEx followed by full short-term recovery of percent predicted forced expiratory volume in 1s was similar (ivacaftor vs. placebo, 57.1% vs. 53.7), as was the proportion of patients having long-term recovery (46.4% vs. 47.7%).

CONCLUSIONS

Ivacaftor treatment reduces the frequency of PEx but does not improve on the rate of complete lung function recovery after PEx when compared with placebo.

The treatment of the pulmonary and extrapulmonary manifestations of cystic fibrosis

Cystic fibrosis (CF) is a complex multisystem disease with considerable between patient variability in its manifestations and severity. In the past several decades, the range of treatments and the evidence to support their use for the pulmonary and extrapulmonary manifestations of CF have increased dramatically, contributing to the improved median survival of patients. As therapy for CF has evolved, new challenges including treatment adherence, medication intolerance and allergy, medical complications and coping with the burden of disease in the context of having a family and managing employment have arisen. While the majority of current therapy focuses primarily on improving symptoms, new therapies (CFTR modulators) target the underlying genetic defect.

New treatments targeting the basic defects in cystic fibrosis

Cystic fibrosis (CF) is a monogenic autosomal recessive disorder affecting around 75,000 individuals worldwide. It is a multi-system disease but the main morbidity and mortality is caused by chronic lung disease. Due to newborn screening, a multidisciplinary approach to care and intensive symptomatic treatment, the prognosis has dramatically improved over the last decades and there are currently more adults than children in many countries. However, CF is still a very severe disease with a current median age of life expectancy in the fourth decade of life. The disease is caused by mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene which encodes the CFTR protein, a protein kinase A-activated ATP-gated anion channel that regulates the transport of electrolytes such as chloride and bicarbonate. More than 2000 mutations have been reported, although not all of these have functional consequences. An enormous research effort and progress has been made in understanding the consequences of these mutations on the CFTR protein structure and function, and this has led to the approval of two new drug therapies that are able to bind to defective CFTR proteins and partially restore their function. They are mutation-specific therapies and available at present for specific mutations only. They are the first personalized medicine for CF with a possible disease-modifying effect. A pipeline of other compounds is under development with different mechanisms of action. It is foreseeable that new combinations of compounds will further improve the correction of CFTR function. Other strategies including premature stop codon read-through drugs, antisense oligonucleotides that correct the basic defect at the mRNA level or gene editing to restore the defective gene as well as gene therapy approaches are all in the pipeline. All these strategies are needed to develop disease-modifying therapies for all patients with CF.

Common clinical features of CF (respiratory disease and exocrine pancreatic insufficiency)

First described as a disease of the pancreas, cystic fibrosis is a genetically inherited progressive disease affecting multiple organ systems. Pulmonary and pancreatic involvement is common in individuals with cystic fibrosis, and the former is attributable to most of the mortality that occurs with the condition. This chapter provides an overview of a clinical approach to the pulmonary and pancreatic manifestations of cystic fibrosis.

Cystic fibrosis: current therapeutic targets and future approaches

Objectives

Study of currently approved drugs and exploration of future clinical development pipeline therapeutics for cystic fibrosis, and possible limitations in their use.

Methods

Extensive literature search using individual and a combination of key words related to cystic fibrosis therapeutics.

Key findings

Cystic fibrosis is an autosomal recessive disorder due to mutations in CFTR gene leading to abnormality of chloride channels in mucus and sweat producing cells. Respiratory system and GIT are primarily involved but eventually multiple organs are affected leading to life threatening complications. Management requires drug therapy, extensive physiotherapy and nutritional support. Previously, the focus was on symptomatic improvement and complication prevention but recently the protein rectifiers are being studied which are claimed to correct underlying structural and functional abnormalities. Some improvement is observed by the corrector drugs. Other promising approaches are gene therapy, targeting of cellular interactomes, and newer drugs for symptomatic improvement.

Conclusions

The treatment has a long way to go as most of the existing therapeutics is for older children. Other limiting factors include mutation class, genetic profile, drug interactions, adverse effects, and cost. Novel approaches like gene transfer/gene editing, disease modeling and search for alternative targets are warranted.

Targeted therapy for chronic respiratory disease: a new paradigm

Targeted therapy has emerged as a highly effective treatment approach for chronic respiratory diseases. Many of these conditions have dismal outcomes; however, targeted therapy shows great results for the subgroup who respond. This represents a new way to approach these conditions and offers great promise as a future treatment direction. In severe eosinophilic asthma, therapy that targets the interleukin-5 pathway with monoclonal antibodies leads to a 50% reduction in asthma exacerbations in previously refractory disease. In cystic fibrosis, lung function improves with therapy that targets specific molecular abnormalities in the cystic fibrosis transmembrane conductance regulator to increase the probability that this chloride channel is open. In lung cancer, specifically adenocarcinoma with epidermal growth factor receptor (EGFR) mutation and overexpression of EGFR tyrosine kinase, therapy that inhibits EGFR tyrosine kinase gives better outcomes than conventional chemotherapy.

Impact of CFTR Modulation on Intestinal pH, Motility, and Clinical Outcomes in Patients With Cystic Fibrosis and the G551D Mutation

Objectives:

A defect in bicarbonate secretion contributes to the pathophysiology of gastrointestinal complications in patients with cystic fibrosis (CF). We measured gastrointestinal pH, clinical outcomes, and intestinal transit profiles in patients with the G551D mutation before and after treatment with ivacaftor, a CF transmembrane regulator channel (CFTR) potentiator.

Methods:

Observational studies of ivacaftor effectiveness were conducted in the United States and Canada. A subset of subjects ingested a wireless motility capsule (n=10) that measures in vivo pH, both before therapy with ivacaftor and 1 month after treatment; values obtained were compared for mean pH and area under the pH curve, and regional intestinal motility. We also queried subjects about abdominal pain and recorded body weight before and after treatment.

Results:

One month after administering ivacaftor, a significant increase in mean pH was observed after gastric emptying (P<0.05). Area under the pH curve analyses indicate increased bicarbonate mass (P<0.05 for select 5 min intervals and all segments >30 min); mean weight gain was 1.1 kg (P=0.08). No difference in abdominal pain or regional transit times was seen.

Conclusions:

CFTR modulation improves the proximal small intestinal pH profile in patients with the G551D CFTR mutation and we observed clinically relevant, contemporaneous weight gain, although it did not reach statistical significance. These data provide in vivo evidence that CFTR is an important regulator of bicarbonate secretion, which may be a translational link between CFTR function and clinical improvement.

The Enigmatic Gut in Cystic Fibrosis: Linking Inflammation, Dysbiosis, and the Increased Risk of Malignancy

PURPOSE OF REVIEW

Intestinal inflammation, dysbiosis, and increased gastrointestinal malignancy risks are well-described in patients with cystic fibrosis (CF). However, there is limited understanding of their pathophysiology. This review aims to discuss these issues and assess potential links between them.

RECENT FINDINGS

Evidence of links between intestinal inflammation and dysbiosis (an imbalance in intestinal microbial populations) exist. Recent studies have demonstrated reduction in intestinal inflammation with probiotic administration. Both bacterial dysbiosis and gut inflammation contribute to the suboptimal nutritional status seen in children with CF. Short-chain fatty acids may be reduced in the gut lumen as a result of bacterial imbalances and may promote inflammation. Inflammation and bacterial dysbiosis in CF may also contribute to emerging adult complications such as gastrointestinal malignancy. An increase in carcinogenic microbes and reduction in microbes protective against cancer have been found in CF, linking bacterial dysbiosis and cancer. Murine studies suggest the CF gene, cystic fibrosis transmembrane conductance regulator (CFTR) gene, itself may be a tumour suppressor gene. The pathophysiology of interactions among intestinal inflammation, dysbiosis, and malignancy in CF is not clearly understood and requires further research.

Growth in Prepubertal Children With Cystic Fibrosis Treated With Ivacaftor

BACKGROUND AND OBJECTIVES

Cystic fibrosis (CF) is known for its impact on the lung and pancreas of individuals; however, impaired growth is also a common complication. We hypothesized that targeting the biological defect in the CF transmembrane conductance regulator (CFTR) protein may affect growth outcomes.

METHODS

In this post hoc analysis, we assessed linear growth and weight in 83 children (aged 6-11 years) enrolled in 2 clinical trials, the longitudinal-observation GOAL study and the placebo-controlled ENVISION study, to evaluate the effects of ivacaftor, a CFTR potentiator. We calculated height and weight z scores and height and weight growth velocities (GVs).

RESULTS

In ivacaftor-treated children in GOAL, height and weight z scores increased significantly from baseline to 6 months (increases of 0.1 [P < .05] and 0.26 [P < .0001], respectively); height GV increased significantly from 3 to 6 months (2.10-cm/year increase; P < .01). In ivacaftor-treated children in ENVISION, height and weight z scores increased significantly from baseline to 48 weeks (increases of 0.17 [P < .001] and 0.35 [P < .001], respectively). Height and weight GVs from baseline to 48 weeks were also significantly higher with ivacaftor than with placebo (differences of 1.08 cm/year [P < .05] and 3.11 kg/year [P < .001], respectively).

CONCLUSIONS

Ivacaftor treatment in prepubescent children may help to address short stature and altered GV in children with CF; results from these analyses support the existence of an intrinsic defect in the growth of children with CF that may be ameliorated by CFTR modulation.

Effects of Pseudomonas aeruginosa on CFTR chloride secretion and the host immune response

In the healthy lung the opportunistic pathogen, Pseudomonas aeruginosa, is rapidly eliminated by mucociliary clearance, a process that is dependent on the activity of the CFTR anion channel that, in concert with a number of other transport proteins, regulates the volume and composition of the periciliary surface liquid. This fluid layer is essential to enable cilia to clear pathogens from the lungs. However, in cystic fibrosis (CF), mutations in the CFTR gene reduce Cl^- and [Formula: see text] secretion, thereby decreasing periciliary surface liquid volume and mucociliary clearance of bacteria. In CF this leads to persistent infection with the opportunistic pathogen, P. aeruginosa, which is the cause of reduced lung function and death in ~95% of CF patients. Others and we have conducted studies to elucidate the effects of P. aeruginosa on wild-type and Phe508del-CFTR Cl^- secretion as well as on the host immune response. These studies have demonstrated that Cif (CFTR inhibitory factor), a virulence factor secreted by P. aeruginosa, is associated with reduced lung function in CF and induces the ubiquitination and degradation of wt-CFTR as well as TAP1, which plays a key role in viral and bacterial antigen presentation. Cif also enhances the degradation of Phe508del-CFTR that has been rescued by ORKAMBI, a drug approved for CF patients homozygous for the Phe508del-CFTR mutation, thereby reducing drug efficacy. This review is based on the Hans Ussing Distinguished Lecture at the 2016 Experimental Biology Meeting given by the author.

Therapeutic benefit observed with the CFTR potentiator, ivacaftor, in a CF patient homozygous for the W1282X CFTR nonsense mutation

Premature termination codons (PTCs) in cystic fibrosis transmembrane conductance regulator (CFTR) gene result in nonfunctional CFTR protein and are the proximate cause of ~11% of CF causing alleles. Aminoglycosides and other novel agents are known to induce translational readthrough of PTCs, a potential therapeutic approach. Among PTCs, W1282X CFTR is unique, as it is a C-terminal CFTR mutation that can exhibit partial activity, even in the truncated state. The potentiator ivacaftor (VX-770) is approved for treating CF patients with G551D and other gating mutations. Based on previous studies demonstrating the beneficial effect of ivacaftor for PTC mutations following readthrough in vitro, we hypothesized that ivacaftor may enhance CFTR activity in CF patients expressing W1282X CFTR, and could be further enhanced by readthrough. Ivacaftor significantly increased CFTR activity in W1282X-expressing cells compared to R1162X CFTR cells, and was further enhanced by readthrough with the aminoglycoside G418. Primary nasal epithelial cells from a W1282X homozygous patient showed improved CFTR function in the presence of ivacaftor. Upon ivacaftor administration to the same patient, there was significant improvement in pulmonary exacerbation frequency, BMI, and insulin requirement, whereas FEV1 remained stable over 3years. These studies suggest that ivacaftor may have moderate clinical benefit in patients with preserved expression of the W1282X CFTR mutation by stimulating residual activity of the truncated protein, suggesting the need for further studies including the addition of efficacious readthrough agents.

The effects of ivacaftor on CF fatty acid metabolism: An analysis from the GOAL study

BACKGROUND

Ivacaftor has produced significant improvement in certain individuals with cystic fibrosis (CF), though the full metabolic effects of treatment remain unknown. Abnormalities in fatty acid metabolism have previously been shown to be a characteristic of CFTR dysfunction. We hypothesized that as a reflection of this clinical improvement, ivacaftor would improve plasma fatty acid levels and decrease urine prostaglandin E metabolite levels.

METHODS

This study analyzed plasma fatty acid levels and urine prostaglandin E metabolites (PGE-M) in 40 subjects with CF participating in the G551D observational (GOAL) study who demonstrated response to the medication by a significant decrease in sweat Cl levels. Paired samples were analyzed before and after 6months of ivacaftor treatment.

RESULTS

Linoleic acid and docosahexaenoic acid levels, which are typically low in individuals with CF, did not significantly increase with ivacaftor treatment. However, arachidonic acid levels did decrease with ivacaftor treatment and there was a significant decrease in the arachidonic acid metabolite PGE-M as measured in the urine [median: before treatment 17.03ng/mg Cr; after treatment 9.06ng/mg Cr; p<0.001]. Furthermore, there were fatty acid age differences observed, including pediatric participants having significantly greater linoleic acid levels at baseline.

CONCLUSION

Ivacaftor reduces inflammatory PGE without fully correcting the plasma fatty acid abnormalities of CF. Age-related differences in fatty acid levels were observed, that may be a result of other clinical factors, such as diet, clinical care, or drug response.

Ivacaftor and symptoms of extra-oesophageal reflux in patients with cystic fibrosis and G551D mutation

BACKGROUND

Extra-oesophageal reflux (EOR) may lead to microaspiration in patients with cystic fibrosis (CF), a probable cause of deteriorating lung function. Successful clinical trials of ivacaftor highlight opportunities to understand EOR in a real world study.

METHODS

Data from 12 patients with CF and the G551D mutation prescribed ivacaftor (150mg bd) was collected at baseline, 6, 26 and 52weeks. The changes in symptoms of EOR were assessed by questionnaire (reflux symptom index (RSI) and Hull airway reflux questionnaire (HARQ)).

RESULTS

Six patients presented EOR at baseline (RSI >13; median 13; range 2-29) and 5 presented airway reflux (HARQ >13; median 12; range 3 to 33). Treatment with ivacaftor was associated with a significant reduction of EOR symptoms (P<0∙04 versus baseline) denoted by the reflux symptom index and Hull airway reflux questionnaire.

CONCLUSION

Ivacaftor treatment was beneficial for patients with symptoms of EOR, thought to be a precursor to microaspiration.

Hypoxia and sterile inflammation in cystic fibrosis airways: mechanisms and potential therapies

Cystic fibrosis is one of the most common autosomal recessive genetic diseases in Caucasian populations. Diagnosisvianewborn screening and targeted nutritional and antibiotic therapy have improved outcomes, however respiratory failure remains the key cause of morbidity and mortality. Progressive respiratory disease in cystic fibrosis is characterised by chronic neutrophilic airway inflammation associated with structural airway damage leading to bronchiectasis and decreased lung function. Mucus obstruction is a characteristic early abnormality in the cystic fibrosis airway, associated with neutrophilic inflammation often in the absence of detectable infection. Recent studies have suggested a link between hypoxic cell death and sterile neutrophilic inflammation in cystic fibrosis and other diseasesviathe IL-1 signalling pathway. In this review, we consider recent evidence regarding the cellular responses to respiratory hypoxia as a potential driver of sterile neutrophilic inflammation in the lung, current knowledge on hypoxia as a pathogenic mechanism in cystic fibrosis and the potential for current and future therapies to alleviate hypoxia-driven sterile inflammation.

Change in Pseudomonas aeruginosa prevalence in cystic fibrosis adults over time

Background

Little is known about risk factors for chronic and mucoid Pseudomonas aeruginosa (Pa) infection in cystic fibrosis (CF) adults, and whether the prevalence is changing.

Methods

We employed a retrospective cohort to analyze data from a single adult CF center (2002 to 2012). Regression models were used to assess independent predictors and change in prevalence of chronic and mucoid Pa infection over time.

Results

The odds ratio of mucoid Pa infection was significantly less in individuals with better baseline lung function (OR 0.84,95%CI:0.77–0.92) and those diagnosed after the age of 25 (OR 0.21, 95%CI:0.05–0.95). The prevalence of chronic Pa and mucoid Pa decreased during the time interval. After adjusting for confounders, the observed decrease in chronic and mucoid Pa between 2002 and 2012 was no longer significant.

Conclusions

The prevalence of chronic and mucoid Pa is decreasing. Larger studies are needed to confirm these regional trends and their significance.

Electronic supplementary material

The online version of this article (doi:10.1186/s12890-016-0333-y) contains supplementary material, which is available to authorized users.

Neutrophil plasticity enables the development of pathological microenvironments: implications for cystic fibrosis airway disease

INTRODUCTION

The pathological course of several chronic inflammatory diseases, including cystic fibrosis, chronic obstructive pulmonary disease, and rheumatoid arthritis, features an aberrant innate immune response dominated by neutrophils. In cystic fibrosis, neutrophil burden and activity of neutrophil elastase in the extracellular fluid have been identified as strong predictors of lung disease severity.

REVIEW

Although neutrophils are generally considered to be rigid, pre-programmed effector leukocytes, recent studies suggest extensive plasticity in how neutrophil functions unfold upon recruitment to peripheral tissues, and how they choose their ultimate fate. Indeed, upon migration to cystic fibrosis airways, neutrophils display dysregulated lifespan, metabolic activation, and altered effector and regulatory functions, consistent with profound adaptation and phenotypic reprogramming. Licensed by signals present in cystic fibrosis airway microenvironment to survive and develop these novel functions, neutrophils orchestrate, in partnership with the epithelium and with the resident microbiota, the evolution of a pathological microenvironment. This microenvironment is defined by altered proteolytic, redox, and metabolic balance and the presence of stable luminal structures in which neutrophils and microbes coexist.

CONCLUSIONS

The elucidation of molecular mechanisms driving neutrophil plasticity in vivo will open new treatment opportunities designed to modulate, rather than block, the crucial adaptive functions fulfilled by neutrophils. This review aims to outline emerging mechanisms of neutrophil plasticity and their participation in the building of pathological microenvironments in the context of cystic fibrosis and other diseases with similar features.

A Case Report of Pregnancy During Use of Targeted Therapeutics for Cystic Fibrosis

New therapeutics, such as ivacaftor, and the combination drug lumacaftor/ivacaftor that target the underlying genetic cause of cystic fibrosis are being hailed as game-changers in this era of personalized medicine. Although these drugs improve lung function, their effects on female fertility have not been studied. In this case report we describe one woman's experience with ivacaftor and her unanticipated pregnancy. Implications related to comprehensive sexual and reproductive health care for women with cystic fibrosis are presented.

Cystic fibrosis

Cystic fibrosis is a common life-limiting autosomal recessive genetic disorder, with highest prevalence in Europe, North America, and Australia. The disease is caused by mutation of a gene that encodes a chloride-conducting transmembrane channel called the cystic fibrosis transmembrane conductance regulator (CFTR), which regulates anion transport and mucociliary clearance in the airways. Functional failure of CFTR results in mucus retention and chronic infection and subsequently in local airway inflammation that is harmful to the lungs. CFTR dysfunction mainly affects epithelial cells, although there is evidence of a role in immune cells. Cystic fibrosis affects several body systems, and morbidity and mortality is mostly caused by bronchiectasis, small airways obstruction, and progressive respiratory impairment. Important comorbidities caused by epithelial cell dysfunction occur in the pancreas (malabsorption), liver (biliary cirrhosis), sweat glands (heat shock), and vas deferens (infertility). The development and delivery of drugs that improve the clearance of mucus from the lungs and treat the consequent infection, in combination with correction of pancreatic insufficiency and undernutrition by multidisciplinary teams, have resulted in remarkable improvements in quality of life and clinical outcomes in patients with cystic fibrosis, with median life expectancy now older than 40 years. Innovative and transformational therapies that target the basic defect in cystic fibrosis have recently been developed and are effective in improving lung function and reducing pulmonary exacerbations. Further small molecule and gene-based therapies are being developed to restore CFTR function; these therapies promise to be disease modifying and to improve the lives of people with cystic fibrosis.

Respiratory pathogens mediate the association between lung function and temperature in cystic fibrosis

INTRODUCTION

Mean annual ambient temperature is a replicated environmental modifier of cystic fibrosis (CF) lung disease with warmer temperatures being associated with lower lung function. The mechanism of this relationship is not completely understood. However, Pseudomonas aeruginosa, a pathogen that infects the lungs of CF individuals and decreases lung function, also has a higher prevalence in individuals living in warmer climates. We therefore investigated the extent to which respiratory pathogens mediated the association between temperature and lung function.

METHODS

Thirteen respiratory pathogens observed on CF respiratory cultures were assessed in multistep fashion using clustered linear and logistic regression to determine if any mediated the association between temperature and lung function. Analysis was performed in the CF Twin-Sibling Study (n=1730; primary population); key findings were then evaluated in the U.S. CF Foundation Data Registry (n=15,174; replication population).

RESULTS

In the primary population, three respiratory pathogens (P. aeruginosa, mucoid P. aeruginosa, and methicillin-resistant Staphylococcus aureus) mediated the association between temperature and lung function. P. aeruginosa accounted for 19% of the association (p=0.003), mucoid P. aeruginosa for 31% (p=0.001), and MRSA for 13% (p=0.023). The same three pathogens mediated association in the replication population (7%, p<0.001; 7%, p=0.002; and 4%, (p=0.002), respectively).

CONCLUSIONS

Three important respiratory pathogens in CF mediate the association between lower lung function and warmer temperatures. These findings have implications for understanding regional variations in clinical outcomes, and interpreting results of epidemiologic studies and clinical trials that encompass regions with different ambient temperatures.

Biomarkers for cystic fibrosis drug development

PURPOSE

To provide a review of the status of biomarkers in cystic fibrosis drug development, including regulatory definitions and considerations, a summary of biomarkers in current use with supportive data, current gaps, and future needs.

METHODS

Biomarkers are considered across several areas of CF drug development, including cystic fibrosis transmembrane conductance regulator modulation, infection, and inflammation.

RESULTS

Sweat chloride, nasal potential difference, and intestinal current measurements have been standardized and examined in the context of multicenter trials to quantify CFTR function. Detection and quantification of pathogenic bacteria in CF respiratory cultures (e.g.: Pseudomonas aeruginosa) are commonly used in early phase antimicrobial clinical trials, and to monitor safety of therapeutic interventions. Sputum (e.g.: neutrophil elastase, myeloperoxidase, calprotectin) and blood biomarkers (e.g.: C reactive protein, calprotectin, serum amyloid A) have had variable success in detecting response to inflammatory treatments.

CONCLUSIONS

Biomarkers are used throughout the drug development process in CF, and many have been used in early phase clinical trials to provide proof of concept, detect drug bioactivity, and inform dosing for later-phase studies. Advances in the precision of current biomarkers, and the identification of new biomarkers with 'omics-based technologies, are needed to accelerate CF drug development.

Individualized medicine using intestinal responses to CFTR potentiators and correctors

Cystic fibrosis transmembrane conductance regulator (CFTR) modulators that target the mutant CFTR protein are being introduced for treatment of cystic fibrosis. Stratification of subjects based on their CFTR genotype has been proven essential to demonstrate clinical efficacy of these novel treatments. Despite this stratification, considerable heterogeneity between subjects receiving CFTR modulators is still observed which remains largely uncharacterized. The CFTR genotype, and additional genetic and environmental factors that impact either tissue-specific CFTR protein characteristics or the pharmacokinetic properties of treatments will likely determine the individual response to therapy. The development of intestinal biomarkers for CFTR modulators may help to better quantitate individual responses to treatment, with potential to optimize treatments for subjects with limited responses, and the selection of responsive subjects that currently do not receive treatments. Here, recent advances concerning the use of intestinal biomarkers for CFTR modulator treatments are reviewed, with a focus on biomarkers of CFTR function in ex vivo rectal biopsies and in vitro cultured primary intestinal organoids. Their potential value is considered in the context of the current unmet needs for better treatments for the majority of subjects with CF, and individual biomarkers that enable the prediction of long term therapeutic responses to CFTR modulators. Pediatr Pulmonol. 2016;51:S23-S34. © 2016 Wiley Periodicals, Inc.

CFTR Modulator Therapies in Pediatric Cystic Fibrosis: Focus on Ivacaftor

INTRODUCTION

Mutations in the cystic fibrosis transmembrane conductance regulator protein (CFTR) cause cystic fibrosis (CF), a disease with life threatening pulmonary and gastrointestinal manifestations. Recent breakthrough therapies restore function to select disease-causing CFTR mutations. Ivacaftor is a small molecule that increases the open channel probability of certain CFTR mutations, producing clear evidence of bioactivity and efficacy in pediatric CF patients. CFTR modulators represent a significant advancement in CF treatment. Extending these therapies to young CF patients is proposed to have the greatest long term impact, potentially preventing later disease.

AREAS COVERED

Here we summarize the research experience of CFTR modulators in pediatrics, focusing on ivacaftor and highlighting challenges in pediatric studies. As a result of these studies, ivacaftor has been approved in CF patients age 2 years and older who have one of ten CFTR mutations.

EXPERT OPINION

Conducting studies in young CF patients presents unique challenges, including small numbers of patients and difficulty selecting sensitive biomarkers and meaningful outcome measures. Adverse events may be more pronounced in children and deserve special attention. Ongoing efforts must focus on expanding and validating new biomarkers, innovative study design, and thorough monitoring of adverse events in children treated with CFTR modulators.

CFTR Modulators: Shedding Light on Precision Medicine for Cystic Fibrosis

Cystic fibrosis (CF) is the most common life-threatening monogenic disease afflicting Caucasian people. It affects the respiratory, gastrointestinal, glandular and reproductive systems. The major cause of morbidity and mortality in CF is the respiratory disorder caused by a vicious cycle of obstruction of the airways, inflammation and infection that leads to epithelial damage, tissue remodeling and end-stage lung disease. Over the past decades, life expectancy of CF patients has increased due to early diagnosis and improved treatments; however, these patients still present limited quality of life. Many attempts have been made to rescue CF transmembrane conductance regulator (CFTR) expression, function and stability, thereby overcoming the molecular basis of CF. Gene and protein variances caused by CFTR mutants lead to different CF phenotypes, which then require different treatments to quell the patients' debilitating symptoms. In order to seek better approaches to treat CF patients and maximize therapeutic effects, CFTR mutants have been stratified into six groups (although several of these mutations present pleiotropic defects). The research with CFTR modulators (read-through agents, correctors, potentiators, stabilizers and amplifiers) has achieved remarkable progress, and these drugs are translating into pharmaceuticals and personalized treatments for CF patients. This review summarizes the main molecular and clinical features of CF, emphasizes the latest clinical trials using CFTR modulators, sheds light on the molecular mechanisms underlying these new and emerging treatments, and discusses the major breakthroughs and challenges to treating all CF patients.

Healthcare resource utilization associated with ivacaftor use in patients with cystic fibrosis

OBJECTIVE

Ivacaftor was approved in 2012 to treat patients with cystic fibrosis (CF) with specific CFTR gene mutations. The objective of this analysis was to analyze the impact of ivacaftor on health resource utilization through analysis of claims data.

METHODS

Patients diagnosed with CF aged ≥6 years prescribed ivacaftor between January 1, 2012 and July 31, 2014 with ≥12 months of continuous insurance coverage prior to and following the prescription were identified. All-cause and CF-specific healthcare resource utilization during the pre- and post-prescription periods and ivacaftor adherence levels were studied.

RESULTS

The 79 identified patients had a mean age of 20.8 years, and 54% were female. The proportion of patients with inpatient admissions (all-cause and CF-related) was significantly higher in the pre index compared to post index period (p ≤ 0.05). Mean ivacaftor medication possession ratio was 0.8 (SD = 0.3), and 73% of patients had a medication possession ratio >0.80.

LIMITATIONS

Only a small number of patients met the inclusion criteria. Additionally, claims data may contain errors or inconsistencies and cannot be used to determine if medications were taken as prescribed.

CONCLUSIONS

Ivacaftor therapy was associated with significant reductions in hospitalizations along with high rates of adherence to treatment over 12 months.

Interleukin-17 Pathophysiology and Therapeutic Intervention in Cystic Fibrosis Lung Infection and Inflammation

Cystic fibrosis (CF) is characterized by an excessive neutrophilic inflammatory response within the airway as a result of defective cystic fibrosis transmembrane receptor (CFTR) expression and function. Interleukin-17A induces airway neutrophilia and mucin production associated with Pseudomonas aeruginosa colonization, which is associated with the pathophysiology of cystic fibrosis. The objectives of this study were to use the preclinical murine model of cystic fibrosis lung infection and inflammation to investigate the role of IL-17 in CF lung pathophysiology and explore therapeutic intervention with a focus on IL-17. Cftr-deficient mice (CF mice) and wild-type mice (WT mice) infected with P. aeruginosa had robust IL-17 production early in the infection associated with a persistent elevated inflammatory response. Intratracheal administration of IL-17 provoked a neutrophilic response in the airways of WT and CF animals which was similar to that observed with P. aeruginosa infection. The neutralization of IL-17 prior to infection significantly improved the outcomes in the CF mice, suggesting that IL-17 may be a therapeutic target. We demonstrate in this report that the pathophysiological contribution of IL-17 may be due to the induction of chemokines from the epithelium which is augmented by a deficiency of Cftr and ongoing inflammation. These studies demonstrate the in vivo contribution of IL-17 in cystic fibrosis lung disease and the therapeutic validity of attenuating IL-17 activity in cystic fibrosis.

Cystic Fibrosis: Microbiology and Host Response

The earliest descriptions of lung disease in people with cystic fibrosis (CF) showed the involvement of 3 interacting pathophysiologic elements in CF airways: mucus obstruction, inflammation, and infection. Over the past 7 decades, our understanding of CF respiratory microbiology and inflammation has evolved with the introduction of new treatments, increased longevity, and increasingly sophisticated laboratory techniques. This article reviews the current understanding of infection and inflammation and their roles in CF lung disease. It also discusses how this constantly evolving information is used to inform current therapeutic strategies, measures and predictors of disease severity, and research priorities.

New Therapeutic Approaches to Modulate and Correct Cystic Fibrosis Transmembrane Conductance Regulator

Cystic fibrosis transmembrane conductance regulator (CFTR) modulators are clinically available personalized medicines approved for some individuals with cystic fibrosis (CF) to target the underlying defect of disease. This review summarizes strategies used to develop CFTR modulators as therapies that improve function and availability of CFTR protein. Lessons learned from dissemination of ivacaftor across the CF population responsive to this therapy and future approaches to predict and monitor treatment response of CFTR modulators are discussed. The goal remains to expand patient-centered and personalized therapy to all patients with CF, ultimately improving life expectancy and quality of life for this disease.

Hyperpolarized 129Xe for investigation of mild cystic fibrosis lung disease in pediatric patients

BACKGROUND

Cystic fibrosis (CF) is a genetic disease which carries high morbidity and mortality from lung-function decline. Monitoring disease progression and treatment response in young patients is desirable, but serial imaging via CT is often considered prohibitive, and detailed functional information cannot be obtained using conventional imaging techniques. Hyperpolarized ¹²⁹Xe magnetic resonance imaging (MRI) can depict and quantify regional ventilation, but has not been investigated in pediatrics. We hypothesized that ¹²⁹Xe MRI is feasible and would demonstrate ventilation defects in mild CF lung disease with greater sensitivity than FEV₁.

METHODS

11 healthy controls (age 6-16years) and 11 patients with mild CF (age 8-16years, Forced Expiratory Volume (FEV₁) percent predicted >70%) were recruited for this study. Nine CF patients had an FEV₁>85%. Each subject was imaged via hyperpolarized ¹²⁹Xe MRI, and the ventilation defect percentage (VDP) was measured. FEV₁ and VDP were compared between the groups.

RESULTS

FEV₁ for controls was 100.3%±8.5% (mean±sd) and for CF patients was 97.9%±16.0% (p=0.67). VDP was 6.4%±2.8% for controls and 18.3%±8.6% for CF (p<0.001). When considering the 9 CF patients with normal FEV₁ (>85%), the mean FEV₁ was 103.1%±12.3% (p=0.57 compared to controls) and VDP was 15.4%±6.3% (p=0.002).

CONCLUSIONS

Hyperpolarized ¹²⁹Xe MRI demonstrated ventilation defects in CF patients with normal FEV₁ and more effectively discriminated CF from controls than FEV₁. Thus ¹²⁹Xe may be a useful outcome measure to detect mild CF lung disease, to investigate regional lung function in pediatric lung diseases, and to follow disease progression.

Lumacaftor/ivacaftor combination for cystic fibrosis patients homozygous for Phe508del-CFTR

Cystic fibrosis (CF) is a life-shortening inherited disease caused by the loss or dysfunction of the CF transmembrane conductance regulator (CFTR) channel activity resulting from mutations in the CFTR gene. Phe508del is the most prevalent mutation, with approximately 90% of all CF patients carrying it on at least one allele. Over the past two or three decades, significant progress has been made in understanding the pathogenesis of CF, and in the development of effective CF therapies. The approval of Orkambi® (lumacaftor/ivacaftor) marks another milestone in CF therapeutics development, which, with the advent of personalized medicine, could potentially revolutionize CF care and management. This article reviews the rationale, progress and future direction in the development of lumacaftor/ivacaftor combination to treat CF patients homozygous for the Phe508del-CFTR mutation.

Antiinflammatory effects of bromodomain and extraterminal domain inhibition in cystic fibrosis lung inflammation

Significant morbidity in cystic fibrosis (CF) results from chronic lung inflammation, most commonly due to Pseudomonas aeruginosa infection. Recent data suggest that IL-17 contributes to pathological inflammation in the setting of abnormal mucosal immunity, and type 17 immunity-driven inflammatory responses may represent a target to block aberrant inflammation in CF. Indeed, transcriptomic analysis of the airway epithelium from CF patients undergoing clinical bronchoscopy revealed upregulation of IL-17 downstream signature genes, implicating a substantial contribution of IL-17-mediated immunity in CF lungs. Bromodomain and extraterminal domain (BET) chromatin modulators can regulate T cell responses, specifically Th17-mediated inflammation, by mechanisms that include bromodomain-dependent inhibition of acetylated histones at the IL17 locus. Here, we show that, in vitro, BET inhibition potently suppressed Th17 cell responses in explanted CF tissue and inhibited IL-17-driven chemokine production in human bronchial epithelial cells. In an acute P. aeruginosa lung infection murine model, BET inhibition decreased inflammation, without exacerbating infection, suggesting that BET inhibition may be a potential therapeutic target in patients with CF.

In vivo imaging of airway cilia and mucus clearance with micro-optical coherence tomography

We have designed and fabricated a 4 mm diameter rigid endoscopic probe to obtain high resolution micro-optical coherence tomography (µOCT) images from the tracheal epithelium of living swine. Our common-path fiber-optic probe used gradient-index focusing optics, a selectively coated prism reflector to implement a circular-obscuration apodization for depth-of-focus enhancement, and a common-path reference arm and an ultra-broadbrand supercontinuum laser to achieve high axial resolution. Benchtop characterization demonstrated lateral and axial resolutions of 3.4 μm and 1.7 μm, respectively (in tissue). Mechanical standoff rails flanking the imaging window allowed the epithelial surface to be maintained in focus without disrupting mucus flow. During in vivo imaging, relative motion was mitigated by inflating an airway balloon to hold the standoff rails on the epithelium. Software implemented image stabilization was also implemented during post-processing. The resulting image sequences yielded co-registered quantitative outputs of airway surface liquid and periciliary liquid layer thicknesses, ciliary beat frequency, and mucociliary transport rate, metrics that directly indicate airway epithelial function that have dominated in vitro research in diseases such as cystic fibrosis, but have not been available in vivo.

Considerations for the Conduct of Clinical Trials with Antiinflammatory Agents in Cystic Fibrosis. A Cystic Fibrosis Foundation Workshop Report

Inflammation leads to lung destruction and loss of pulmonary function in patients with cystic fibrosis (CF). Drugs that modulate the cystic fibrosis transmembrane conductance regulator (CFTR) have recently been approved. Although the impact of CFTR modulators on sweat chloride and lung function are exciting, they have not yet demonstrated an effect on inflammation. Therefore, CF antiinflammatory drug development must continue. Unfortunately, the lack of clarity with this process has left investigators and industry sponsors frustrated. The Cystic Fibrosis Foundation established a working group in early 2014 to address this issue. There are many inflammatory processes disrupted in CF, and, therefore, there are many potential targets amenable to antiinflammatory therapy. Regardless of a drug's specific mechanism of action, it must ultimately affect the neutrophil or its products to impact CF. The working group concluded that before bringing new antiinflammatory drugs to clinical trial, preclinical safety studies must be conducted in disease-relevant models to assuage safety concerns. Furthermore, although studies of antiinflammatory therapies must first establish safety in adults, subsequent studies must involve children, as they are most likely to reap the most benefit. The working group also recommended that pharmacokinetic-pharmacodynamic studies and early-phase safety studies be performed before proceeding to larger studies of longer duration. In addition, innovative study designs may improve the likelihood of adequately assessing treatment response and mitigating risk before conducting multiyear studies. Learning from past experiences and incorporating this knowledge into new drug development programs will be instrumental in bringing new antiinflammatory therapies to patients.

Ibuprofen regulation of microtubule dynamics in cystic fibrosis epithelial cells

High-dose ibuprofen, an effective anti-inflammatory therapy for the treatment of cystic fibrosis (CF), has been shown to preserve lung function in a pediatric population. Despite its efficacy, few patients receive ibuprofen treatment due to potential renal and gastrointestinal toxicity. The mechanism of ibuprofen efficacy is also unclear. We have previously demonstrated that CF microtubules are slower to reform after depolymerization compared with respective wild-type controls. Slower microtubule dynamics in CF cells are responsible for impaired intracellular transport and are related to inflammatory signaling. Here, it is identified that high-dose ibuprofen treatment in both CF cell models and primary CF nasal epithelial cells restores microtubule reformation rates to wild-type levels, as well as induce extension of microtubules to the cell periphery. Ibuprofen treatment also restores microtubule-dependent intracellular transport monitored by measuring intracellular cholesterol transport. These effects are specific to ibuprofen as other cyclooxygenase inhibitors have no effect on these measures. Effects of ibuprofen are mimicked by stimulation of AMPK and blocked by the AMPK inhibitor compound C. We conclude that high-dose ibuprofen treatment enhances microtubule formation in CF cells likely through an AMPK-related pathway. These findings define a potential mechanism to explain the efficacy of ibuprofen therapy in CF.

Connectivity mapping (ssCMap) to predict A20-inducing drugs and their antiinflammatory action in cystic fibrosis

Cystic fibrosis (CF) lung disease is characterized by chronic and exaggerated inflammation in the airways. Despite recent developments to therapeutically overcome the underlying functional defect in the cystic fibrosis transmembrane conductance regulator, there is still an unmet need to also normalize the inflammatory response. The prolonged and heightened inflammatory response in CF is, in part, mediated by a lack of intrinsic down-regulation of the proinflammatory NF-κB pathway. We have previously identified reduced expression of the NF-κB down-regulator A20 in CF as a key target to normalize the inflammatory response. Here, we have used publicly available gene array expression data together with a statistically significant connections' map (sscMap) to successfully predict drugs already licensed for the use in humans to induce A20 mRNA and protein expression and thereby reduce inflammation. The effect of the predicted drugs on A20 and NF-κB(p65) expression (mRNA) as well as proinflammatory cytokine release (IL-8) in the presence and absence of bacterial LPS was shown in bronchial epithelial cells lines (16HBE14o-, CFBE41o-) and in primary nasal epithelial cells from patients with CF (Phe508del homozygous) and non-CF controls. Additionally, the specificity of the drug action on A20 was confirmed using cell lines with tnfαip3 (A20) knockdown (siRNA). We also show that the A20-inducing effect of ikarugamycin and quercetin is lower in CF-derived airway epithelial cells than in non-CF cells.

Animal Models of Cystic Fibrosis Pathology: Phenotypic Parallels and Divergences

Cystic fibrosis (CF) is caused by mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene. The resultant characteristic ion transport defect results in decreased mucociliary clearance, bacterial colonisation, and chronic neutrophil-dominated inflammation. Much knowledge surrounding the pathophysiology of the disease has been gained through the generation of animal models, despite inherent limitations in each. The failure of certain mouse models to recapitulate the phenotypic manifestations of human disease has initiated the generation of larger animals in which to study CF, including the pig and the ferret. This review will summarise the basic phenotypes of three animal models and describe the contributions of such animal studies to our current understanding of CF.

Ivacaftor in cystic fibrosis adults: Czech experience with six years of follow-up

AIMS

Ivacaftor is a revolutionary treatment option for cystic fibrosis (CF) patients with G551D and other gating mutations. The aim of this study was to evaluate the clinical status of patients on ivacaftor who were followed for up to 6 years together with an evaluation of ivacaftor therapy in one patient with an initial FEV1 less than 40% of predicted value.

METHODS

Data on development of clinical status and sinopulmonary-related therapies were obtained from patient health records during ivacaftor treatment lasting for up to six years and were compared with an equivalent period before ivacaftor administration.

RESULTS

Five CF adults with a median age 28.6 years (range 21.4-35.6 years) with median FEV1 45% pred. (range 16-85% pred.) were included in the study. Four subjects were also participants in the STRIVE and PERSIST studies. Altogether, twenty-four patient-years of ivacaftor treatment were analyzed. The median FEV1 decline per year decreased from -4.5 to -0.9% pred. (P = 0.043). Reduction in number of days on antibiotic treatment and hospital stays was 21% (P < 0.001) and 75% (P = 0.003), respectively. Improvement and stabilization of lung function was observed for up to six years of treatment. In a patient with severe airway obstruction, an increase in the FEV1 value (30.4% from baseline) was documented during the first twelve months of treatment.

CONCLUSION

Ivacaftor therapy resulted in improved and stabilized lung function in up to six years of treatment with a reduction in number of days on antibiotic treatment and hospital stays. Its efficiency was also displayed in a patient with severe airway obstruction.