ECFS standards of care on CFTR-related disorders: Identification and care of the disorders

This is the third paper in the series providing updated information and recommendations for people with cystic fibrosis transmembrane conductance regulator (CFTR)-related disorder (CFTR-RD). This paper covers the individual disorders, including the established conditions - congenital absence of the vas deferens (CAVD), diffuse bronchiectasis and chronic or acute recurrent pancreatitis - and also other conditions which might be considered a CFTR-RD, including allergic bronchopulmonary aspergillosis, chronic rhinosinusitis, primary sclerosing cholangitis and aquagenic wrinkling. The CFTR functional and genetic evidence in support of the condition being a CFTR-RD are discussed and guidance for reaching the diagnosis, including alternative conditions to consider and management recommendations, is provided. Gaps in our knowledge, particularly of the emerging conditions, and future areas of research, including the role of CFTR modulators, are highlighted.

ECFS standards of care on CFTR-related disorders: Towards a comprehensive program for affected individuals

After three publications defining an updated guidance on the diagnostic criteria for people with cystic fibrosis transmembrane conductance regulator (CFTR)-related disorders (pwCFTR-RDs), establishing its relationship to CFTR-dysfunction and describing the individual disorders, this fourth and last paper in the series addresses some critical challenges facing health care providers and pwCFTR-RD. Topics included are: 1) benefits and obstacles to collect data from pwCFTR-RD are discussed, together with the opportunity to integrate them into established CF-registries; 2) the potential of infants designated CRMS/CFSPID to develop a CFTR-RD and how to communicate this information; 3) a description of the challenges in genetic counseling, with particular regard to phenotypic variability, unknown long-term evolution, CFTR testing and pregnancy termination 4) a proposal for the assessment of potential barriers to the implementation and dissemination of the produced documents to health care professionals involved in the care of pwCFTR-RD and a process to monitor the implementation of the CFTR-RD recommendations; 5) clinical trials investigating the efficacy of CFTR modulators in CFTR-RD and how endpoints and outcomes might be adapted to the heterogeneity of these disorders.

Challenges faced by parents of screen-detected children with Cystic Fibrosis: The ICOS study

Background

Informal care is an essential component of overall care for patients, particularly those with chronic illnesses such as Cystic Fibrosis (CF). This study aims to assess the level of caregiving burden faced by parents/caregivers of children with CF (CwCF) recruited to the Irish Comparative Outcomes Study of CF (ICOS), a historical cohort study of CwCF. In July 2011, a new-born screening programme began in Ireland.

Methods

The study population includes the parents of screen-detected CwCF born between July 2011-2021. The Challenge of Living with CF-Short Form is a new, validated 15-item tool that evaluates the caregiving burden faced by parents from the child’s diagnosis until early adolescence. Comparisons based on the age of screen-detected CwCF were conducted. SPSS was used for analysis.

Results

69 parents of screen-detected CwCF responded. Fifty percent of parents of older children (aged 4-12+ years) and 35% of the parents of toddlers (0-3 years) faced moderate-high level difficulties in managing the extra expenses required for the care of their CwCF, despite all children receiving free clinical care, prescriptions and medications. A significantly greater proportion of the parents of older children than younger children experienced constant problems in managing daily oral medication routines (37% vs 13%; P = 0.039), nebulised medication routines (67.5% vs 21.4%; P = 0.003), and physiotherapy routines (57.8% vs 31.8%; P = 0.046)

Conclusions

Using the novel Challenge of living with Cystic Fibrosis-Short Form questionnaire, our findings suggest that the caregiving burden is higher for parents of older CwCF. Expenses incurred by parents of a child with a serious chronic medical condition go beyond medical care and treatment expenses.

Key messages

• The challenge of living with Cystic Fibrosis-Short Form is being used for the first time in a population setting.

• The caregiving burden was more pronounced in the parents of older CwCF.

Real life practice of sweat testing in Europe

Evidence based guidelines exist for sweat testing, which remains a key component of a diagnosis of cystic fibrosis (CF), especially following newborn bloodspot screening (NBS). There are emerging challenges with respect to maintaining a valid sweat test service, notably a smaller number of sweat tests ordered in regions with established NBS programmes where Pediatricians refer less children for sweat testing, younger patients and equipment becoming obsolete. The ECFS Diagnostic Network Working Group has undertaken a comprehensive survey to better define sweat test practice across Europe. The survey was completed by 136 European respondents representing a CF center or laboratory providing a sweat test service (65% from regions with NBS for CF). There was considerable variance in practice, often not consistent with guidelines. In particular collection of sweat from two sites was rarely reported in European centres in contrast to US guidelines. There was a range of different references quoted for cut-off for both a positive and intermediate test. Most responses suggest cost is becoming an increasing issue and is not sufficiently reimbursed. This work will inform best practice guidelines and resources to sustain and improve sweat testing in Europe.

Establishing a diagnosis of cystic fibrosis

Cystic fibrosis (CF) is a recessively inherited condition caused by mutation of the cystic fibrosis transmembrane conductance regulator (CFTR) gene. Characterization of the genetic defect has improved understanding of the condition and, in the majority of cases, diagnosis is straightforward. However, in a significant number, diagnosis remains a challenge. This paper will discuss the management of these issues and reflect on atypical presentations. In addition we will discuss situations in which genetic variations of the CFTR gene are not associated with a classical CF phenotype and the implications for practice in both paediatric and adult clinics.

Comparison of real time diagnostic chemistries to detect Pseudomonas aeruginosa in respiratory samples from cystic fibrosis patients

BACKGROUND

Early eradication therapy is key to keeping the airways Pseudomonas aeruginosa infection-free and rapid identification is essential.

METHODS

We used rapid DNA extraction and qPCR assays to detect bacterial, P. aeruginosa and strain-specific targets in samples using two qPCR chemistries. Using 459 respiratory samples from adult and children CF patients, we compared two qPCR methods to culture-based methods in terms of sensitivity and time to result.

RESULTS

For adult samples, there was 100% concordance between methods. There was no clear pattern in fluctuations in P. aeruginosa number during exacerbation. In child samples, qPCR methods identified additional P. aeruginosa positive samples. The time-to-result was reduced by over 24h and copy number and colony forming unit could differ dramatically in some samples.

CONCLUSION

If adopted, these methods could significantly improve early P. aeruginosa detection in diagnostic laboratories and therefore play a pivotal role in prolonging infection-free airways in CF patients.

Oxygen saturation profile in healthy preterm infants

AIM

To establish a reference range for oxygen saturation (SpO(2)) in well preterm infants to guide home oxygen therapy using a pulse oximeter and Pulse Oximetry Data Analysis Software (PODS).

METHODS

SpO(2) and heart-rate profiles of healthy preterm infants receiving mechanical ventilation for less than 6 h and supplemental oxygen for less than 48 h were monitored using a pulse oximeter. The stored data were downloaded from the monitor to a personal computer as individual files. Each infant's files of SpO(2) were subsequently displayed in graphic form, and a reference range was constructed using dedicated software, PODS.

RESULTS

43 infants were studied. The median value of all infants mean SpO(2) values was 95% (range 92-99%). The median duration of saturations less than 85% and between 85% and 90 % were 1% and 2% respectively. Using the study group median, 5th and 95th percentiles, a cumulative frequency curve of time against SpO(2) value was constructed (representing the reference range of SpO(2) profiles in healthy preterm infants).

CONCLUSION

The SpO(2) reference range can be used as an easy and practical guide to compare SpO(2) profiles of infants on home oxygen therapy and guide their oxygen therapy.

Physiological measurements confirming the diagnosis of cystic fibrosis: the sweat test and measurements of transepithelial potential difference

Post-natal screening allied with genetic mutation testing has altered our perception of cystic fibrosis (CF) as a clinical entity. Increasingly, infants identified through screening programmes have few or no symptoms or present with atypical forms of the disease. We review how the sweat test has evolved to be the gold standard for confirming the diagnosis of CF and examine its limitations. Other physiological measurements, including nasal potential difference and intestinal current measurement, which might aid in establishing the diagnosis, particularly in patients exhibiting a mild phenotype, are also considered.

Topical cystic fibrosis transmembrane conductance regulator gene replacement for cystic fibrosis-related lung disease

BACKGROUND

Cystic fibrosis is caused by a defective gene encoding a protein called the cystic fibrosis transmembrane conductance regulator (CFTR), and is characterised by chronic lung infection resulting in inflammation and progressive lung damage that results in a reduced life expectancy.

OBJECTIVES

To determine whether topical CFTR gene replacement therapy to the lungs in people with cystic fibrosis is associated with improvements in clinical outcomes, and to assess any adverse effects.

SEARCH STRATEGY

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group Trials Register comprising references identified from comprehensive electronic database searches, handsearching relevant journals and abstract books of conference proceedings. Date of most recent search: February 2007

SELECTION CRITERIA

Randomised controlled trials comparing topical CFTR gene delivery to the lung, using either viral or non-viral delivery systems, with placebo or an alternative delivery system in people with confirmed cystic fibrosis.

DATA COLLECTION AND ANALYSIS

The authors independently extracted data and assessed study quality. Authors of included studies were contacted and asked for any available additional data. Meta-analysis was limited due to differing study designs.

MAIN RESULTS

Three randomised controlled trials met the inclusion criteria for this review, involving a total of 155 participants. Thirteen studies were excluded. The included studies differed in terms of CFTR gene replacement agent and study design, which limited the meta-analysis. Although the first Moss study reported a significant improvement in respiratory function (FEV(1)) 30 days after participants had received their first dose of gene therapy agent, this finding was not confirmed in their larger second study or in our meta-analysis.In participants who received the CFTR gene transfer agents in the Alton study, "influenza-like" symptoms were found (relative risk 7.00 (95% confidence interval (CI) 1.10 to 44.61)). There were no other significant increases in adverse events in any of the studies. Alton measured ion transport in the lower airways and demonstrated significant changes toward normal values in the participants who received gene transfer agents (P < 0.0001), weighted mean difference 6.86 (95% CI of 3.77 to 9.95). In these participants there was also evidence of increased salt transport in cells obtained by brushing the lower airway. These outcomes, whilst important, are not of direct clinical relevance.

AUTHORS' CONCLUSIONS

There is currently no evidence to support the use of CFTR gene transfer reagents as a treatment for lung disease in people with cystic fibrosis. Future studies need to investigate clinically important outcome measures.

Sodium channel blockers for cystic fibrosis

BACKGROUND

People with cystic fibrosis (CF) have increased transport of the salt, sodium across their airway lining. Over-absorption of sodium results in the dehydration of the liquid that lines the airway surface and is a primary defect in people with CF.

OBJECTIVES

To determine whether the topical administration of drugs that block sodium transport improves the respiratory condition of people with CF.

SEARCH STRATEGY

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group Trials Register comprising references identified from comprehensive electronic database searches, handsearching relevant journals and abstract books of conference proceedings. We contacted principal investigators known to work in the field, previous authors and pharmaceutical companies who manufacture ion transport agents for unpublished or follow-up data. Most recent search of the Group's register: March 2006

SELECTION CRITERIA

Published or unpublished randomised controlled trials (RCTs) or quasi-randomised controlled trials of sodium channel blockers compared to placebo or another sodium channel blocker or the same sodium channel blocker at a different dosing regimen.

DATA COLLECTION AND ANALYSIS

Two authors independently extracted data. Meta-analysis was limited due to differing study designs.

MAIN RESULTS

Four RCTs, with a total of 205 participants, examining the topical administration of the short-acting sodium channel blocker, amiloride, compared to placebo were identified as eligible for inclusion in the review. For three studies, interventions for six months were completed and it was possible to calculate relative change in respiratory function (FVC). There was a significant difference found in relative change in FVC in favour of placebo (GIV analysis of weighted mean difference for FVC; 1.51% (95% confidence interval -2.77 to -0.25). There were no significant differences identified in other clinically relevant outcomes.

AUTHORS' CONCLUSIONS

We found no evidence that the topical administration of a short-acting sodium channel blocker improves respiratory condition in people with cystic fibrosis and some limited evidence of deterioration in lung function.

Nasal potential difference increases with gestation in moderately preterm neonates on the first postnatal day

At birth the mammalian airway switches from liquid secretion to absorption, an important mechanism in lung liquid clearance. Airway ion transport was examined on the first postnatal day in 38 moderately preterm infants (29-36 weeks gestation). The absorptive airway ion transport capacity was well developed regardless of respiratory condition and there was little capacity for Cl- secretion.

Suitability of the Upper Airway Models Obtained from MRI Studies in Simulating Drug Lung Deposition from Inhalers

PURPOSE

In this study, the suitability of the upper airway models, obtained by applying a magnetic resonance imaging method, in simulating in vivo aerosol deposition data is determined.

METHODS

Depositions of salbutamol sulfate from two nebulizers in two models, one with constriction at the oropharynx (the constricted cast) and another model without that constriction (the wide cast), were determined.

RESULTS

For the Sidestream and Ventstream nebulizer, 76 +/- 3% (mean +/- standard deviation) and 81 +/- 2% of the emitted dose deposited in the constricted cast, whereas 51 +/- 2% and 49 +/- 3% of the emitted dose deposited in the wide cast, respectively. These values were in good agreement with in vivo data. Mostly, increasing nebulizer charge volume (by normal saline) from 2.5 ml to 5 ml increased significantly the lung dose. However, the lung doses from the Sidestream and Ventstream nebulizer with 2.5 ml charge volume via the wide cast were (1.37 +/- 0.06 and 1.38 +/- 0.05 mg) significantly larger than those for the constricted cast with 5 ml charge volume (0.87 +/- 0.15 and 0.86 +/- 0.21 mg, respectively) (p = 0.005).

CONCLUSIONS

The upper airway models closely simulated the in vivo deposition data. Optimizing the upper airway posture during inhalation via the nebulizers would be more efficient in increasing drug lung delivery than diluting their contents.

Azithromycin for cystic fibrosis

During what is a relatively barren time for new therapies for cystic fibrosis (CF), azithromycin has received a lot of attention as a potential treatment for CF lung disease. Laboratory studies suggest that azithromycin may have indirect actions, including anti-inflammatory, in addition to the standard antibacterial properties. The unique pharmacokinetics of azithromycin sets it aside from other macrolide antibiotics, but may result in increased resistance patterns. Three well-designed randomised controlled trials have demonstrated a small but significant improvement in respiratory function (forced expiratory volume in one second) with azithromycin compared with placebo. These trial results are confirmed by a recent meta-analysis. Mild adverse events (wheeze, diarrhoea and nausea) were significantly increased in one trial. There is no clear consensus regarding the correct dose and length of treatment with azithromycin. The present review discusses the role of azithromycin in the management of cystic fibrosis and the need for close monitoring of patients started on this drug. In addition, clinics should liaise closely with their microbiology departments and monitor resistance patterns.

Elevated sweat sodium associated with pulmonary oedema in meningococcal sepsis

BACKGROUND

We observed a temporary positive sweat test with sodium and chloride levels greater than 60 mmol L(-1) following meningococcal septicaemia. Objective was to investigate whether this finding is reproducible and whether this disturbance in epithelial sodium transport is related to sepsis-induced pulmonary oedema.

MATERIALS AND METHODS

Twenty-four children with a diagnosis of meningococcal septicaemia and 10 controls with noninfectious critical illness admitted to the Royal Liverpool Children's Hospital were included. Sweat collection was by pilocarpine iontophoresis in the acute phase of the illness (days 1-5) and on follow up. Sodium and chloride concentrations were determined by flame photometry.

RESULTS

In patients with meningococcal septicaemia, sweat sodium and chloride concentrations were significantly higher in the acute compared with the recovery phase, with a mean (SD) of 31.0 (14.6) mmol L(-1) in the acute vs. 19.6 (10.2) mmol L(-1) on recovery for sodium and 21.0 (12.1) mmol L(-1) in the acute vs. 11.8 (4.9) mmol L(-1) on recovery for chloride (P < 0.01, t-test, for sodium and chloride). Sweat sodium and chloride were significantly higher in patients with meningococcal disease compared with controls and in the acute phase in patients with septicaemia-related pulmonary oedema [mean (SD) sodium: 41.0 (15.4) mmol L(-1) and chloride: 28.8 (14.3) mmol L(-1)] compared with septic patients without [mean (SD) sodium: 24.5 (10.1) mmol L(-1) and chloride: 15.3 (7.9) mmol L(-1)] (P < 0.01 for sodium and chloride).

CONCLUSIONS

This is the first study to provide in vivo evidence of reduced epithelial sodium transport in children with septicaemia and of its association with pulmonary oedema.

Macrolide antibiotics for cystic fibrosis

BACKGROUND

Chronic severe infection with Pseudomonas aeruginosa, affects many people with cystic fibrosis (CF). There is evidence from the laboratory and from other disease processes that macrolide antibiotics, whilst not directly active against Pseudomonas aeruginosa, may have indirect actions against this organism.

OBJECTIVES

We aimed to test the hypotheses that, in people with CF, macrolide antibiotics:(1) improve clinical status compared to placebo or another antibiotic;(2) do not have unacceptable adverse effects. If benefit was demonstrated, we aimed to assess the optimal type, dose and duration of macrolide therapy.

SEARCH STRATEGY

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group trials register comprising references identified from comprehensive electronic database searches, handsearching relevant journals and abstract books of conference proceedings. We contacted principal investigators known to work in the field, previous authors and pharmaceutical companies who manufacture macrolide antibiotics for unpublished or follow-up data (December 2003). Most recent search of the Group's register: January 2004

SELECTION CRITERIA

Published or unpublished randomised controlled trials of macrolide antibiotics compared to placebo, another class of antibiotic or another macrolide antibiotic. Studies comparing regimens of the same macrolide antibiotic at different doses will also be included.

DATA COLLECTION AND ANALYSIS

Two reviewers independently extracted data and assessed study quality. Three groups were contacted for missing data and we hope to include these in future reviews.

MAIN RESULTS

Searches identified 14 studies, four were included in this review (296 participants). Two studies enrolled adults, one children (a significant number of whom were not colonised with Pseudomonas aeruginosa) and one both adults and children. All the clinical studies reported small but significant improvements in respiratory function with azithromycin versus placebo. Meta-analysis at the one-month and six-month time points demonstrates a significant benefit with respect to relative change in FEV1 (at six months, for n = 104, azithromycin and n = 114, placebo; WMD 5.82% (95% CI 2.45 to 9.20)). The largest study reported a significant increase in mild adverse events (nausea, diarrhoea and wheezing).

REVIEWERS' CONCLUSIONS

There is clear evidence from these studies of a small but significant improvement in respiratory function following treatment with azithromycin. The largest study employed a three times a week dose and, in this study, treatment with azithromycin was associated with a significant increase in mild adverse events. Further studies are needed to clarify the precise role of azithromycin in the treatment of CF lung disease.

Macrolide antibiotics for cystic fibrosis

BACKGROUND

The antibiotic treatment of chest infections which characterise cystic fibrosis (CF) has significantly improved prospects for people with CF. The nature of organisms causing these infections has restricted antibiotic choice. Pseudomonas aeruginosa, especially, is resistant to most oral antibiotics. There is evidence from the laboratory and from other disease processes that macrolide antibiotics, whilst not directly active against Pseudomonas aeruginosa, may have indirect actions against this organism.

OBJECTIVES

We aimed to test the hypotheses that macrolide antibiotics:(1) improve clinical status compared to placebo or another antibiotic;(2) have no unacceptable adverse effects. If benefit was demonstrated, we aimed to assess the optimal type, dose and duration of macrolide therapy.

SEARCH STRATEGY

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group trials register comprising references identified from comprehensive electronic database searches, handsearching relevant journals and abstract books of conference proceedings.We contacted principal investigators known to work in the field, previous authors and pharmaceutical companies who manufacture macrolide antibiotics for unpublished or follow-up data (December 2002). Date of the most recent search of the Group's register: March 2003.

SELECTION CRITERIA

Published or unpublished randomised controlled trials of macrolide antibiotics compared to placebo, another class of antibiotic or another macrolide antibiotic. Studies comparing regimens of the same macrolide antibiotic at different doses will also be included.

DATA COLLECTION AND ANALYSIS

Two reviewers independently extracted data and assessed study quality. Two groups were contacted for missing data, but these were unavailable for the review.

MAIN RESULTS

Searches identified eleven studies, two were included in this review (101 participants). One study enrolled adults and the other children (a significant number of whom were not colonised with Pseudomonas aeruginosa). Both studies report small but significant changes in respiratory function (% change in FEV1) in favour of azithromycin. Meta-analysis at the two-month time point demonstrated a significant benefit with respect to percentage change in FVC (weighted mean difference 5.42 (1.77 to 9.07)) from azithromycin, but no difference with respect to percentage change of FEV1. There were no significant adverse effects reported.

REVIEWER'S CONCLUSIONS

The role of macrolides in the management of CF lung disease remains unclear and there are many unanswered questions. Two small randomised controlled trials have suggested short-term improvement in respiratory function with azithromycin. Until the results of further studies are available the widespread use of azithromycin in CF cannot be advocated and should be restricted to well-designed randomised controlled trials.

Airway surface liquid recovered by lavage with perfluorocarbon liquid in cats

BACKGROUND

Airway surface liquid (ASL) is difficult to sample. Lavage with an immiscible perfluorocarbon (PFC) liquid to recover ASL was evaluated in cats.

MATERIALS AND METHODS

Six wild-type cats underwent bronchoscopic lavage with a PFC (perfluorohexane), with the bronchoscope wedged in the feline equivalent of the right lower lobe. Two cats (control animals) were lavaged with a saline vehicle only. Four procedures were performed on each animal at 2-3-week intervals. Ionic composition of ASL was determined by flame photometry.

RESULTS

Cats lavaged with PFC showed significantly more acute respiratory distress than those lavaged with saline (respiratory rate following procedure: PFC, 47 +/- 5 min-1 vs. saline, 27 +/- 2 min-1, P < 0.05; O2 saturation: PFC 80 +/- 1% vs. saline, 91 +/- 1%, P < 0.01). The PFC group also had clinical evidence of chronic respiratory compromise (mean respiratory rate before next anaesthetic; PFC, 37 +/- 2 min-1 vs. saline, 20 +/- 3 min-1, P < 0.01). The PFC-lavaged lungs demonstrated persistent radiographic changes and histological evidence of small airways obstruction with distal alveolar damage. Six PFC lavages yielded ASL samples (> 100 microL) which were sufficient for analysis. Mean (+/- SEM) ionic concentrations in these samples were Na+ 157.4 +/- 14.5 mmol L-1, Cl- 150.5 +/- 16.8 mmol L-1 and K+ 10.1 +/- 1.7 mmol L-1.

CONCLUSIONS

Perfluorocarbon lavage can be used to collect unmodified ASL from the distal lung. However, repeated lavage with perfluorohexane was associated with significant pathological changes in this study.

A modified technique for measurement of nasal transepithelial potential difference in infants

OBJECTIVE

To establish a method for measuring nasal transepithelial potential difference (PD) in infants.

STUDY DESIGN

A modified infant method (smaller catheter size, reduced flow rates, and shorter protocol time) was compared with an established adult nasal PD method in 10 adult volunteers (4 with cystic fibrosis [CF]). Nasal PD was measured in 13 infants with a possible diagnosis of CF.

RESULTS

Recordings were similar for the established and the modified methods in adult volunteers. An amiloride concentration of 10(-4) mol/L was necessary for full inhibition of amiloride-sensitive sodium ion (Na(+)) transport. Of the 13 infants, 2 had PD values suggestive of CF (mean baseline PD, -50.1 mV and -31.4 mV; maximum baseline PD, -61 mV and -49 mV; change in PD after perfusion with zero chloride solution with isoprenaline and amiloride [DeltazeroCl(-)/Iso], -1 mV and +3.5 mV), and 11 had normal values (mean +/- SEM baseline PD, -13.2 +/- 1.0 mV; maximum baseline PD, -21.4 +/- 2.0; DeltazeroCl(-)/Iso, -15.3 +/- 1.9 mV). These results correlated with subsequent sweat test data, mutation analysis, and clinical outcome.

CONCLUSION

Nasal PD measured with this modified method is comparable to that measured with an established adult method. The measurements were well tolerated in 13 infants and discriminated bioelectric profiles characteristic of normal and CF respiratory epithelium. This study supports the use of this modified nasal PD technique as a diagnostic test for CF in newborn infants.

Repeat administration of DNA/liposomes to the nasal epithelium of patients with cystic fibrosis

The major cause of mortality in patients with cystic fibrosis (CF) is lung disease. Expression of the cystic fibrosis transmembrane conductance regulator (CFTR) gene product in the airways is a potential treatment. Clinical studies in which the CFTR cDNA was delivered to the respiratory epithelia of CF patients have resulted in modest, transient gene expression. It seems likely that repeated administration of the gene transfer vector will be required for long-term gene expression. We have undertaken a double-blinded study in which multiple doses of a DNA/liposome formulation were delivered to the nasal epithelium of CF patients. Ten subjects received plasmid DNA expressing the CFTR cDNA complexed with DC-Chol/DOPE cationic liposomes, whilst two subjects received placebo. Each subject received three doses, administered 4 weeks apart. There was no evidence of inflammation, toxicity or an immune response towards the DNA/liposomes or the expressed CFTR. Nasal epithelial cells were collected 4 days after each dose for a series of efficacy assays including quantitation of vector-specific DNA and mRNA, immunohistochemistry of CFTR protein, bacterial adherence, and detection of halide efflux ex vivo. Airway ion transport was also assessed in vivo by repeated nasal potential difference (PD) measurements. On average, six of the treated subjects were positive for CFTR gene transfer after each dose. All subjects positive for CFTR function were also positive for plasmid DNA, plasmid-derived mRNA and CFTR protein. The efficacy measures suggest that unlike high doses of recombinant adenoviral vectors, DNA/liposomes can be successfully re-administered without apparent loss of efficacy.

A placebo-controlled study of liposome-mediated gene transfer to the nasal epithelium of patients with cystic fibrosis

Cystic fibrosis (CF) is a common, serious, inherited disease. The major cause of mortality in CF is lung disease, due to the failure of airway epithelial cells to express a functional product of the cystic fibrosis transmembrane conductance regulator (CFTR) gene. A potential treatment for CF lung disease is the expression of CFTR in the airways following gene transfer. We have undertaken a double-blinded, placebo-controlled, clinical study of the transfer of the CFTR cDNA to the nasal epithelium of 12 CF patients. Cationic liposomes complexed with plasmid containing the human CFTR cDNA were administered to eight patients, whilst four patients received placebo. Biopsies of the nasal epithelium taken 7 days after dosing were normal. No significant changes in clinical parameters were observed. Functional expression of CFTR assessed by in vivo nasal potential difference measurements showed transient correction of the CF chloride transport abnormality in two patients (15 days after dosing in one patient). Fluorescence microscopy demonstrated CFTR function ex vivo. In cells from nasal brushings. In total, evidence of functional CFTR gene transfer was obtained in six out of the eight treated patients. These results provide proof of concept for liposome-mediated CF gene transfer.

The role of hepatobiliary scintigraphy in cystic fibrosis

This was a prospective open study that examined the quantitative and qualitative analysis of hepatobiliary scintigraphy (DISIDA) in detecting liver involvement in cystic fibrosis (CF). Forty-four adult and pediatric patients (median age, 12.1 years; range, 1.1-36.3 years) were divided into three groups: group 1, no evidence of liver involvement (n = 8); group 2, biochemical evidence of liver involvement on two or more occasions (n = 26); and group 3, clinical evidence of liver disease (n = 10). In groups 1 and 2, the most common qualitative scintigraphic finding was focal intrahepatic retention of tracer (26/34 patients, 12 of whom had normal findings on ultrasonography). This finding corresponds to focal cholestasis and may warrant treatment with the choleretic agent ursodeoxycholic acid (UDCA). In the group 3 patients, the abnormal qualitative scintigraphic appearances (heterogeneous uptake of tracer and nodular liver outline) added little to the findings on ultrasonography; however, these patients had a prolonged mean hepatic clearance time compared with those in groups 1 and 2 (one-way ANOVA; P < .015). It is proposed that scintigraphy with DISIDA has a role in the detection of early liver involvement in cystic fibrosis.

Generation and characterization of a delta F508 cystic fibrosis mouse model

We have generated mice carrying the most common mutation in cystic fibrosis (CF), delta F508, within the cystic fibrosis (Cftr) gene. Mutant animals show pathological and electrophysiological changes consistent with a CF phenotype. delta F508-/- mice die from peritonitis and show deficiencies in cAMP-activated electrogenic Cl- transport. These mice produce delta F508 transcripts and show the temperature-dependent trafficking defect first described for the human delta F508 CFTR protein. A functional CFTR Cl- channel not demonstrated by null CF mice or present at 37 degrees C was detected following incubation of epithelial cells at 27 degrees C. Thus, these mice are an accurate delta F508 model and will be valuable for testing drugs aimed at overcoming the delta F508 trafficking defect.