Cystic fibrosis and survival to 40 years: a study of cystic fibrosis transmembrane conductance regulator function

Lung fibrosis: Post-COVID-19 complications and evidences

BACKGROUND

COVID 19, a lethal viral outbreak that devastated lives and the economy across the globe witnessed non-compensable respiratory illnesses in patients. As been evaluated in reports, patients receiving long-term treatment are more prone to acquire Pulmonary Fibrosis (PF). Repetitive damage and repair of alveolar tissues increase oxidative stress, inflammation and elevated production of fibrotic proteins ultimately disrupting normal lung physiology skewing the balance towards the fibrotic milieu.

AIM

In the present work, we have discussed several important pathways which are involved in post-COVID PF. Further, we have also highlighted the rationale for the use of antifibrotic agents for post-COVID PF to decrease the burden and improve pulmonary functions in COVID-19 patients.

CONCLUSION

Based on the available literature and recent incidences, it is crucial to monitor COVID-19 patients over a period of time to rule out the possibility of residual effects. There is a need for concrete evidence to deeply understand the mechanisms responsible for PF in COVID-19 patients.

Analysis of CF patient survival confirms STAT3 as a CF-modifying gene with changing impact over time

INTRODUCTION AND AIM

The signal transducer and activator of transcription 3 (STAT3) has been identified as one of the cystic fibrosis (CF) modifying genes. In this study, we aimed to assess the association between STAT3 genotype and CF patient survival over several decades and to investigate the effect of STAT3 inhibition on epithelial CFTR expression.

METHODS

We analyzed the informative genetic marker STAT3Sat for its association with survival in 174 p.Phe508del-CFTR homozygous CF patients treated at the CF center in Hannover spanning birth cohorts from >3 decades (1959-1994). Furthermore, we treated two epithelial cell lines with STAT3 inhibitors and monitored changes of CFTR protein expression by western blot.

RESULTS

Only for p.Phe508del-CFTR homozygous patients born prior to 1975, survival was significantly influenced by STAT3sat genotype (P = 0.023). The expression levels of STAT3 and CFTR positively correlated in epithelial cell lines (P = 0.01).

CONCLUSIONS

Our results in different birth cohorts identified a time-dependent impact of STAT3 genotype on CF patients' survival and found that improved symptomatic treatment of later-born CF patients obviates STAT3's modifying influence. Consistent with our previous results, STAT3-specific inhibition resulted in increased CFTR expression in the epithelial cell line 16HBE14o-. Thus, care should be taken when CF-modifying genes are studied in cross-sectional cohorts as the impact of modifying genes might not be invariant in the light of changing therapeutic regimens.

Chloride Conductance, Nasal Potential Difference and Cystic Fibrosis Pathophysiology

PURPOSE

Cystic fibrosis (CF) is a multisystem genetic disease caused by dysfunction of the epithelial anionic channel Cystic Fibrosis Transmembrane conductance Regulator (CFTR). Decreased mucociliary clearance because of thickened mucus is part of the pulmonary disease pathophysiology. It is controversial if the thickened airway surface liquid (ASL) is caused by the deficient chloride secretion and excessive sodium (through ENaC) and water hyperabsorption from the periciliar fluid or by the lack of bicarbonate secretion with relative acidification of the ASL. Correlations between the magnitude of in vivo chloride conductance with phenotypic characteristics and CF genotype can help to elucidate these mechanisms and direct to new treatments.

METHODS

Nasal potential difference was measured in 28 CF patients (age from 0.3 to 28 year) and correlated with pulmonary function, pancreatic phenotype, pulmonary colonization and genotype severity.

RESULTS

The CFTR-chloride conductance was better in older patients (r = 0.40; P = 0.03), in patients with better pulmonary function (r = 0.48; P = 0.01), and was associated with genotype severity. Higher chloride diffusion in the presence of a favorable chemical gradient was associated with Pseudomonas aeruginosa negativity (P < 0.05). More negative NPDmax was associated with pancreatic insufficiency (P < 0.01) as well with genotype severity, but not with the pulmonary function.

CONCLUSIONS

The anion permeability through CFTR, mainly chloride, but bicarbonate as well, is the most critical factor in CF airway pathophysiology. Treatments primarily directed to correct CFTR function and/or airway acidity are clearly a priority.

Insights into the variability of nasal potential difference, a biomarker of CFTR activity

BACKGROUND

Nasal potential difference (NPD) is used to evaluate CFTR function in vivo. We aimed to evaluate the intrasubject and intersubject variability of NPD measurements.

METHODS

We reviewed NPD tracings of 116 patients with CF enrolled in the placebo arm of a multicenter study. Patients carried at least one nonsense mutation and underwent repeated NPD tests every 16 weeks. NPD parameters included basal potential difference (basal PD), inhibition of sodium absorption by amiloride (Δ Amiloride), chloride (Cl^-) transport in response to a Cl^--free solution (Δ Low Cl^-), isoproterenol (Δ Isoproterenol), the sum of Δ Low Cl^- and Δ Isoproterenol (Δ Low Cl^--Isoproterenol) and ATP (Δ ATP).

RESULTS

Basal PD and Δ Amiloride displayed the highest variabilities, mainly stemming from intercenter and intrasubject effect. Δ Low Cl^-, Δ Isoproterenol and Δ Low Cl^--Isoproterenol demonstrated a large intrasubject variability but a smaller intersubject variability. The intrasubject measurement variability for Δ Low Cl^--Isoproterenol, was within ± 7.2 mV with 95% probability. It was greater in patients reporting ongoing pulmonary exacerbations.

CONCLUSIONS

The large intercenter variability of basal PD and Δ Amiloride highlights the operator-dependent aspect of these measurements. A difference greater than 7.2 mV in Δ Low Cl^--Isoproterenol in a given patient on CFTR modulator can be attributed, with 95% probability, to a treatment effect rather than to the variability inherent in the measurement.

Assessment of pulmonary structure-function relationships in young children and adolescents with cystic fibrosis by multivolume proton-MRI and CT

BACKGROUND

Lung disease is the most frequent cause of morbidity and mortality in patients with cystic fibrosis (CF), and there is a shortage of sensitive biomarkers able to regionally monitor disease progression and to assess early responses to therapy.

PURPOSE

To determine the feasibility of noncontrast-enhanced multivolume MRI, which assesses intensity changes between expiratory and inspiratory breath-hold images, to detect and quantify regional ventilation abnormalities in CF lung disease, with a focus on the structure-function relationship.

STUDY TYPE

Retrospective.

POPULATION

Twenty-nine subjects, including healthy young children (n = 9, 7-37 months), healthy adolescents (n = 4, 14-22 years), young children with CF lung disease (n = 10, 7-47 months), and adolescents with CF lung disease (n = 6, 8-18 years) were studied.

FIELD STRENGTH/SEQUENCE

3D spoiled gradient-recalled sequence at 1.5T.

ASSESSMENT

Subjects were scanned during breath-hold at functional residual capacity (FRC) and total lung capacity (TLC) through noncontrast-enhanced MRI and CT. Expiratory-inspiratory differences in MR signal-intensity (Δ1 H-MRI) and CT-density (ΔHU) were computed to estimate regional ventilation. MR and CT images were also evaluated using a CF-specific scoring system.

STATISTICAL TESTS

Quadratic regression, Spearman's correlation, one-way analysis of variance (ANOVA).

RESULTS

Δ1 H-MRI maps were sensitive to ventilation heterogeneity related to gravity dependence in healthy lung and to ventilation impairment in CF lung disease. A high correlation was found between MRI and CT ventilation maps (R2  = 0.79, P < 0.001). Globally, Δ1 H-MRI and ΔHU decrease with increasing morphological score (respectively, R2  = 0.56, P < 0.001 and R2  = 0.31, P < 0.001). Locally, Δ1 H-MRI was higher in healthy regions (median 15%) compared to regions with bronchiectasis, air trapping, consolidation, and to segments fed by airways with bronchial wall thickening (P < 0.001).

DATA CONCLUSION

Multivolume noncontrast-enhanced MRI, as a nonionizing imaging modality that can be used on nearly any MRI scanner without specialized equipment or gaseous tracers, may be particularly valuable in CF care, providing a new imaging biomarker to detect early alterations in regional lung structure-function.

LEVEL OF EVIDENCE

3 Technical Efficacy: Stage 3 J. MAGN. RESON. IMAGING 2018;48:531-542.

Ultrashort Echo-Time Magnetic Resonance Imaging Is a Sensitive Method for the Evaluation of Early Cystic Fibrosis Lung Disease

RATIONALE

Recent advancements that have been made in magnetic resonance imaging (MRI) improve our ability to assess pulmonary structure and function in patients with cystic fibrosis (CF). A nonionizing imaging modality that can be used as a serial monitoring tool throughout life can positively affect patient care and outcomes.

OBJECTIVES

To compare an ultrashort echo-time MRI method with computed tomography (CT) as a biomarker of lung structure abnormalities in young children with early CF lung disease.

METHODS

Eleven patients with CF (mean age, 31.8 ± 5.7 mo; median age, 33 mo; 7 male and 4 female) were imaged via CT and ultrashort echo-time MRI. Eleven healthy age-matched patients (mean age, 22.5 ± 10.2 mo; median age, 23 mo; 5 male and 6 female) were imaged via ultrashort echo-time MRI. CT scans of 13 additional patients obtained for clinical indications not affecting the heart or lungs and interpreted as normal provided a CT control group (mean age, 24.1 ± 11.7 mo; median age, 24 mo; 6 male and 7 female). Studies were scored by two experienced radiologists using a well-validated CF-specific scoring system for CF lung disease.

MEASUREMENTS AND MAIN RESULTS

Correlations between CT and ultrashort echo-time MRI scores of patients with CF were very strong, with P values ≤0.001 for bronchiectasis (r = 0.96) and overall score (r = 0.90), and moderately strong for bronchial wall thickening (r = 0.62, P = 0.043). MRI easily differentiated CF and control groups via a reader CF-specific scoring system.

CONCLUSIONS

Ultrashort echo-time MRI detected structural lung disease in very young patients with CF and provided imaging data that correlated well with CT. By quantifying early CF lung disease without using ionizing radiation, ultrashort echo-time MRI appears well suited for pediatric patients requiring longitudinal imaging for clinical care or research studies. Clinical Trial registered with www.clinicaltrials.gov (NCT01832519).

Prevalence of hearing and vestibular loss in cystic fibrosis patients exposed to aminoglycosides

AIM

Cystic Fibrosis (CF) patients frequently use aminoglycosides (AGS) to treat CF exacerbation due to colonization with Pseudomonas aeruginosa. Although AGS can cause vestibular and auditory sensory losses that can negatively impact quality of life, little is known about the prevalence of vestibular loss in this population. The aim of this study was to determine the prevalence of hearing loss and/or vestibular dysfunction in CF patients treated with AGS.

METHODS

The relationship between hearing status and vestibular status was also investigated. Hearing was determined to be normal or abnormal based on pure tone air and bone conduction thresholds. Vestibular outcome was divided into four categories; normal, non-lateralized vestibular dysfunction, unilateral loss, and bilateral loss based on results of post head shaking testing, positional and positioning testing, bithermal calorics, sinusoidal, and rotational step testing.

RESULTS

Of our cohort of 71 patients, 56 (79%) patients have vestibular system dysfunction while only 15 (21%) have normal vestibular system function. Overall, 16 patients (23%) have hearing loss. In considering the relationship between auditory and vestibular function, 12 (17%) demonstrated both normal hearing and normal vestibular function and 13 (18%) have both hearing loss and abnormal vestibular function. Of the 55 (78%) patients with normal hearing, 43 (61%) have vestibular dysfunction, while 3 (4%) of patients with normal vestibular function have hearing loss.

CONCLUSION

These results suggest that monitoring hearing alone is insufficient to detect ototoxicity in CF patients being treated with systemic AGS.

What can the CF registry tell us about rare CFTR-mutations? A Belgian study

Background

CFTR2 provides clinical and functional information of the most common CFTR-mutations. Rare mutations (RMs) occur in only a few patients with limited reported clinical data. Their role in CF-disease liability is hardly documented.

Methods

Belgian CF-Registry 2013 data were analyzed to identify CF with at least 1 RM (CF_+RM). Clinical data and sweat chloride of CF_+RM were compared to CF-controls, carrying 2 class 1 to 3 mutations (CF_classic). Disease severity was compared between both groups. To avoid bias in the comparison, transplanted patients were excluded from each group.

Results

Seventy-seven CF_+RM were identified (77/1183 = 6.5%). Sixty-four different RM were detected, of which 21 had not been previously reported. All RMs, corresponding to HGVS (Human Genome Variation Society) nomenclature, were listed in supplementary data.

Seven transplanted CF_+RM were excluded for further analysis. CF_+RM had higher age at diagnosis [median (IQR)] [3.7 y (0.3–18.3) vs. 0.3y (0.1–2,0) (p < 0.0001)], lower sweat chloride [96 mmol/L (64–107) vs. 104 mmol/L (97–115) (p < 0.0001)], higher FEV₁%pred [77%pred (58–96) vs. 68%pred (48–86) (p = 0.017)], were less frequently pancreatic insufficient [56% vs. 98% (p < 0.0001)], Pseudomonas aeruginosa colonized [24% vs. 44% (p = 0.0093)] and needed fewer IV antibiotics [36% vs. 51% (p = 0.041)] than CF_classic. However, a wide spectrum of disease severity was seen amongst CF_+RM.

Conclusions

CF-patients with a RM cover 6.5% of the Belgian CF-population. Rare mutations can be found in severely ill patients, but more often in late diagnosed, pancreatic sufficient patients.

Electronic supplementary material

The online version of this article (doi:10.1186/s13023-017-0694-1) contains supplementary material, which is available to authorized users.

Allergic bronchopulmonary aspergillosis is associated with pet ownership in cystic fibrosis

BACKGROUND

Late diagnosis of allergic bronchopulmonary aspergillosis (ABPA) is associated with significant lung function decline and morbidity in cystic fibrosis (CF). The association of ABPA and domestic pet ownership in patients with CF has not been elucidated yet. Our objective was to determine the association of ABPA with pet ownership in patients with CF.

METHODS

Clinical and microbiological data from certified local patient registry were analyzed for 109 patients with CF aged 1-64 years: 55 pet owner and 54 non-pet owners. The primary outcome of the retrospective observational study was the occurrence of ABPA in pet owners and non-pet owners with CF. The free statistical software R was utilized to investigate logistic regression models for association factors.

RESULTS

Of the 109 patients included in the study, 61 (56%) were female. The mean age of the total group was 25.4 ± 13.2 years. Adjusted analysis revealed that ABPA (OR 5.0227, 95% CI: 1.182-21.340, p = 0.029) was associated with pet ownership in patients with CF. Furthermore, ABPA in pet owners with CF was associated with an increased number of exacerbations (OR 6.446, 95% CI: 1.057-39.328, p = 0.043). Other outcomes did not significantly differ.

CONCLUSION

Owning a pet was associated with ABPA in patients with CF. Future prospective multicenter longitudinal studies are needed to investigate chronological causality between pet ownership, ABPA development, and pulmonary exacerbations and to determine whether these estimates are generalizable for ABPA susceptible patients beyond CF (asthma, bronchiectasis).

Country to country variation: what can be learnt from national cystic fibrosis registries

PURPOSE OF REVIEW

This review will address the evolving science involving international comparisons of populations of persons living with cystic fibrosis. Understanding the current clinical outcomes in cystic fibrosis is critical prior to assessing such comparisons. Countries that differ in clinical approaches provide natural experiments to assess those approaches.

RECENT FINDINGS

Recent studies have highlighted that the population of persons with cystic fibrosis is changing; estimates predict a continued growth of cystic fibrosis populations with substantial increases in persons with cystic fibrosis who are adults. Additional work highlighted differences in subpopulations (i.e. children); US cystic fibrosis children appear to have better lung function, but similar nutritional status, compared to UK cystic fibrosis children. These differences were associated with differences in intensity of care, with a higher proportion of US children receiving more cystic fibrosis-specific therapies. Additional research raises important questions regarding potential sampling bias in different patient registries and differing rates of unconfirmed cases of cystic fibrosis. These and other limitations are highlighted.

SUMMARY

Differences in both demographics and clinical outcomes in cystic fibrosis between nations can be informative, but, like many types of observational research, are at risk of unrecognized bias. Despite this limitation, these comparisons can lead to substantive improvements in care in cystic fibrosis.

Cystic fibrosis

Cystic fibrosis is an autosomal recessive, monogenetic disorder caused by mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene. The gene defect was first described 25 years ago and much progress has been made since then in our understanding of how CFTR mutations cause disease and how this can be addressed therapeutically. CFTR is a transmembrane protein that transports ions across the surface of epithelial cells. CFTR dysfunction affects many organs; however, lung disease is responsible for the vast majority of morbidity and mortality in patients with cystic fibrosis. Prenatal diagnostics, newborn screening and new treatment algorithms are changing the incidence and the prevalence of the disease. Until recently, the standard of care in cystic fibrosis treatment focused on preventing and treating complications of the disease; now, novel treatment strategies directly targeting the ion channel abnormality are becoming available and it will be important to evaluate how these treatments affect disease progression and the quality of life of patients. In this Primer, we summarize the current knowledge, and provide an outlook on how cystic fibrosis clinical care and research will be affected by new knowledge and therapeutic options in the near future. For an illustrated summary of this Primer, visit: http://go.nature.com/4VrefN.

Screening for F508del as a first step in the molecular diagnosis of cystic fibrosis

OBJECTIVE:

To determine the relevance of screening for the F508del mutation of the cystic fibrosis transmembrane conductance regulator gene as a first step in the genetic diagnosis of cystic fibrosis (CF) by associating the genotype with various clinical variables.

METHODS:

We evaluated 180 CF patients regarding the F508del mutation. The clinical data were obtained from the medical records of the patients and from interviews with their parents or legal guardians.

RESULTS:

Of the 180 patients studied, 65 (36.1%) did not carry the F508del mutation (group 0 [G0]), 67 (37.2%) were F508del heterozygous (G1), and 48 (26.7%) were F508del homozygous (G2). All three groups showed associations with the clinical variables. Homozygosis was associated with younger patients, younger age at CF diagnosis, and younger age at the first isolation of Pseudomonas aeruginosa (PA), as well as with higher prevalence of pancreatic insufficiency (PI) and non-mucoid PA (NMPA) colonization. In comparison with G1+G2 patients, G0 patients were older; first experienced clinical symptoms, digestive disease, and pulmonary disease at an older age; were older at CF diagnosis and at first PA isolation; and had a lower prevalence of PI and meconium ileus, as well as of colonization by NMPA, mucoid PA, and Burkholderia cepacia. In G1 patients, values were intermediate for age at CF diagnosis; age at first PA isolation, first pulmonary symptoms, and first clinical manifestations; MPA colonization; and OR for PI.

CONCLUSIONS:

The identification of F508del in 63.9% of the patients studied showed that this can be a useful tool as a first step in the genetic diagnosis of CF. The F508del genotype was associated with clinical severity of the disease, especially with the variables related to CF onset.

Rate of improvement of CF life expectancy exceeds that of general population--observational death registration study

BACKGROUND

It is unclear why cystic fibrosis (CF) survival has improved. We wished to quantify increases in CF median age of death in the context of general population survival improvement.

METHOD

Death registration data analysis (US, England & Wales (E&W)-1972-2009).

RESULTS

CF median age of death is higher in US than E&W and greater for males, opposite to that of death from all causes. CF median age of death has increased by 0.543 life years per year (E&W, US combined (95% confidence interval 0.506, 0.582)). The difference in median age at death between those dying from all causes and CF decreased in both territories. CF median age of death for males is greater than for females in both territories. This gap has not narrowed.

CONCLUSION

The median age of death of people with CF is improving more rapidly than that of the general population in US and E&W.

Increased apical Na+ permeability in cystic fibrosis is supported by a quantitative model of epithelial ion transport

Cystic fibrosis (CF) is caused by mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene, which encodes an anion channel. In the human lung CFTR loss causes abnormal ion transport across airway epithelial cells. As a result CF individuals produce thick mucus, suffer persistent bacterial infections and have a much reduced life expectancy. Trans-epithelial potential difference (V_t) measurements are routinely carried out on nasal epithelia of CF patients in the clinic. CF epithelia exhibit a hyperpolarised basal V_t and a larger V_t change in response to amiloride (a blocker of the epithelial Na⁺ channel, ENaC). Are these altered bioelectric properties solely a result of electrical coupling between the ENaC and CFTR currents, or are they due to an increased ENaC permeability associated with CFTR loss? To examine these issues we have developed a quantitative mathematical model of human nasal epithelial ion transport. We find that while the loss of CFTR permeability hyperpolarises V_t and also increases amiloride-sensitive V_t, these effects are too small to account for the magnitude of change observed in CF epithelia. Instead, a parallel increase in ENaC permeability is required to adequately fit observed experimental data. Our study provides quantitative predictions for the complex relationships between ionic permeabilities and nasal V_t, giving insights into the physiology of CF disease that have important implications for CF therapy.

Ageing in cystic fibrosis and long-term survival

The demographics of cystic fibrosis continue to change with adults outnumbering children in most developed countries. Median predicted survival is now over 40 years and 7.6% are aged >40 years. Patients surviving beyond 40 cover the full spectrum of disease from homozygous F508del to single organ disease. Differences in the characteristics of older patients are recognised, but generally patients diagnosed in adulthood are still at risk of accelerated lung function decline. Improved survival brings new challenges, including a rising rate of CF co-morbidities such as diabetes, in addition to other medical problems such as renal impairment and ototoxicity.

[Mucoviscidosis: CFTR mutation-specific therapy: a ray of sunshine in a cloudy sky]

There is a need to find a cure for pulmonary disease in cystic fibrosis (CF), though full benefit of this approach will be restricted to those patients with well-preserved lungs. The most promising route is currently that of a pharmacological mutation-specific approach aiming at correcting the mechanism by which mutations lead to impairment of chloride conductance across respiratory epithelial cells. In the past 14years, 7 candidate drugs (CPX, 4PBA, gentamicin, PTC124, VX-770 or Ivacaftor, VX-809 or Lumacaftor, and Miglustat) have been investigated in CF patients. A postulate of 14 out of the 15 published studies has been that an effective agent had to improve total chloride secretion as assessed in vivo by nasal potential difference measurements. The present review casts a critical look at these studies. Apparent inconsistencies are discussed as well as possible limitations of nasal potential difference measurements as outcome parameters in these trials. Primarily targeting a mutation carried by less than 2% of French CF patients, the 2 Ivacaftor studies could well be a milestone on the long road toward a cure for CF. However, further data on safety and long-term efficacy are obviously needed and the current price of this medication in the US would make it unaffordable for European patients.

Matrine modulates HSC70 levels and rescues ΔF508-CFTR

Cystic fibrosis transmembrane conductance regulator (CFTR) is a cAMP-dependent Cl(-) channel located in the plasma membrane, and its malfunction results in cystic fibrosis (CF), the most common lethal genetic disease in Caucasians. Most CF patients carry the deletion of Phe508 (ΔF508 mutation); this mutation prevents the delivery of the CFTR to its correct cellular location, the apical (lumen-facing) membrane of epithelial cells. Molecular chaperones play a central role in determining the fate of ΔF508-CFTR. In this report, we show that the Matrine, a quinolizidine alkaloid, downregulates the expression of the molecular chaperone HSC70 and increases the protein levels of ΔF508-CFTR in human alveolar basal epithelial cells (A549 cell line), stably transfected with a ΔF508-CFTR-expressing construct. Moreover, Matrine induced ΔF508-CFTR release from endoplasmic reticulum to cell cytosol and its localization on the cell membrane. Interestingly, downregulation of HSC70 resulted in increased levels of ΔF508-CFTR complexes with the co-chaperone BAG3 that in addition appeared to co-localize with the mutated protein on the cell surface. These results shed new light on ΔF508-CFTR interactions with proteins of the chaperones/co-chaperones system and could be useful in strategies for future medical treatments for CF.

Gene therapy for the treatment of cystic fibrosis

Gene therapy is being developed as a novel treatment for cystic fibrosis (CF), a condition that has hitherto been widely-researched yet for which no treatment exists that halts the progression of lung disease. Gene therapy involves the transfer of correct copies of cystic fibrosis transmembrane conductance regulator (CFTR) DNA to the epithelial cells in the airways. The cloning of the CFTR gene in 1989 led to proof-of-principle studies of CFTR gene transfer in vitro and in animal models. The earliest clinical trials in CF patients were conducted in 1993 and used viral and non-viral gene transfer agents in both the nasal and bronchial airway epithelium. To date, studies have focused largely on molecular or bioelectric (chloride secretion) outcome measures, many demonstrating evidence of CFTR expression, but few have attempted to achieve clinical efficacy. As CF is a lifelong disease, turnover of the airway epithelium necessitates repeat administration. To date, this has been difficult to achieve with viral gene transfer agents due to host recognition leading to loss of expression. The UK Cystic Fibrosis Gene Therapy Consortium (Imperial College London, University of Edinburgh and University of Oxford) is currently working on a large and ambitious program to establish the clinical benefits of CF gene therapy. Wave 1, which has reached the clinic, uses a non-viral vector. A single-dose safety trial is nearing completion and a multi-dose clinical trial is shortly due to start; this will be powered for clinically-relevant changes. Wave 2, more futuristically, will look at the potential of lentiviruses, which have long-lasting expression. This review will summarize the current status of translational research in CF gene therapy.