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.

Genomically-guided therapies: A new era for cystic fibrosis

Since the cloning of the CFTR gene 30 years ago, research aiming at understanding how CFTR mutations translate to abnormal synthesis or function of the CFTR protein has opened the way to genomically-guided therapy to improve CFTR function. A CFTR potentiator to enhance CFTR channel function has been approved in 2012 for specific and quite rare mutations. Subsequently, combinations of a corrector to increase CFTR expression at the cell membrane, plus a potentiator, have been approved for patients homozygous for the p.Phe508del mutation. To obtain robust correction of CFTR, new combinations of drugs are being studied. A triple combination associating two correctors and one potentiator is very promising and if data of clinical trials are confirmed, it could be a robust and well tolerated CFTR modulator for patients bearing at least one p.Phe508del mutation. Many other strategies are also in development to make these genomically-guided treatments available to all patients with CF. © 2020 French Society of Pediatrics. Published by Elsevier Masson SAS. All rights reserved.

Building global development strategies for cf therapeutics during a transitional cftr modulator era

As CFTR modulator therapy transforms the landscape of cystic fibrosis (CF) care, its lack of uniform access across the globe combined with the shift towards a new standard of care creates unique challenges for the development of future CF therapies. The advancement of a full and promising CF therapeutics pipeline remains a necessary priority to ensure maximal clinical benefits for all people with CF. It is through collaboration across the global CF community that we can optimize the evaluation and approval process of new therapies. To this end, we must identify areas for which harmonization is lacking and for which efficiencies can be gained to promote ethical, feasible, and credible study designs amidst the changing CF care landscape. This article summarizes the counsel from core advisors across multiple international regions and clinical trial networks, developed during a one-day workshop in October 2019. The goal of the workshop was to identify, in consideration of the highly transitional era of CFTR modulator availability, the drug development areas for which global alignment is currently uncertain, and paths forward that will enable advancement of CF therapeutic development.

Guideline on the design and conduct of cystic fibrosis clinical trials: the European Cystic Fibrosis Society-Clinical Trials Network (ECFS-CTN)

We describe the rationale for disease specific research networks in general as well as the aims and function of the European Cystic Fibrosis Society-Clinical Trials Network (ECFS-CTN) specifically. The ECFS-CTN was founded in 2009 with the aim of improving the quality and quantity of clinical research in the area of cystic fibrosis (CF) in Europe. A network of 18 clinical trial sites in 8 European countries was established according to uniform state-of-the-art quality criteria. To support the ECFS-CTN in the acquisition, planning and conduct of clinical trials, the network is equipped with a coordinating centre, steering and executive committees, and committees for protocol review, standardization, training and networking as well as a data safety monitoring board. A strong partnership with European CF patient parent organizations aims to increase awareness of the need for efficient clinical research and the participation of patients in clinical trials.

Pseudomonas aeruginosa induces vascular endothelial growth factor synthesis in airway epithelium in vitro and in vivo

Pseudomonas aeruginosa (PA) airway infection and bronchial blood vessel proliferation are features of bronchiectasis. Because vascular endothelial growth factor (VEGF)-A regulates angiogenesis, we hypothesised that PA infection induces VEGF synthesis in epithelium and peribronchial angiogenesis. Because epidermal growth factor receptor (EGFR) activation regulates VEGF synthesis in cancer, we also evaluated the roles of EGFR. Airway epithelial cells were incubated for 24 h with PA supernatants and VEGF concentrations were measured in culture medium by ELISA. C57BL/6N mice were instilled intratracheally with sterile agarose beads or with agarose beads coated with the PA strain PAO1 (mean ± sem 6 × 10(5) ± 3 × 10(5) cfu · animal(-1)), with or without the EGFR inhibitor AG1478 (12.5 mg · kg(-1) · day(-1) intraperitoneally). Epithelial immunostaining for VEGF and phosphorylated EGFR, and peribronchial vascularity, were quantified using morphometric analysis. VEGF expression was further assessed by western blot in mouse lung homogenates. PA supernatants induced dose-dependent VEGF synthesis in cultured airway epithelial cells, effects which were prevented by EGFR antagonists. In mice, persistent PAO1 infection increased immunostaining for VEGF and phosphorylated EGFR in airway epithelium, and resulted in increased peribronchial vascularity within 7 days. These effects were reduced by EGFR inhibition. Persistent PA infection induced VEGF synthesis in airway epithelium and peribronchial angiogenesis, at least in part via EGFR-dependent mechanisms.

Non-classic cystic fibrosis associated with D1152H CFTR mutation

BACKGROUND

Limited knowledge exists on phenotypes associated with the D1152H cystic fibrosis transmembrane conductance regulator (CFTR) mutation.

METHODS

Subjects with a D1152H allele in trans with another CFTR mutation were identified using the French Cystic Fibrosis Registry. Phenotypic characteristics were compared with those of pancreatic insufficient (PI) and pancreatic sufficient (PS) cystic fibrosis (CF) subjects in the Registry (CF cohort).

RESULTS

Forty-two subjects with D1152H alleles were identified. Features leading to diagnosis included chronic sinopulmonary disease (n = 25), congenital absence of the vas deferens (n = 11), systematic neonatal screening (n = 4), and genetic counseling (n = 2). Median age at diagnosis was 33 [interquartile range (IQR, 24-41)] years in D1152H subjects. Median sweat chloride concentrations were 43.5 (39-63) mmol/l in D1152H subjects and were markedly lower than in PI and PS CF subjects (p < 0.05). Bronchiectasis was present in 67% of D1152H subjects, but Pseudomonas aeruginosa colonization and pancreatic insufficiency were present in <30% of subjects. Estimated rates of decline in forced expiratory volume in 1 s (FEV(1)) were lower in D1152H subjects vs PI CF subjects (p < 0.05). None of the D1152H subjects identified since 1999 had died or required lung transplantation.

CONCLUSIONS

When present in trans with a CF-causing mutation, D1152H causes significant pulmonary disease, but all subjects had prolonged survival.

[The diagnosis of cystic fibrosis in adults: lessons from a family story]

INTRODUCTION

Cystic fibrosis is usually diagnosed during the first years of life. Diagnosis may be achieved in adults with milder forms of the disease at any age.

CASE REPORTS

We report the diagnosis of cystic fibrosis in three adults within the same family. A 39 yr old man, was diagnosed with congenital absence of the vas deferens; the diagnosis of cystic fibrosis was achieved based on a positive chloride sweat test and the identification of two mutations in the CFTR gene. His mother experienced repeated bronchial infections that began when she was 12 years old. The diagnosis of cystic fibrosis was considered at the age of 74 yr after her son was diagnosed with this disease. Sweat test showed normal chloride concentrations and cystic fibrosis was suspected based on elevated basal transepithelial nasal potential difference. Genetic testing for the 33 most frequent mutations in the CFTR gene showed only one mutation. A second rare mutation was identified by complete sequencing of the CFTR gene, confirming the diagnosis of cystic fibrosis. A third case of pauci-symptomatic cystic fibrosis was diagnosed in a brother of the index case.

CONCLUSION

These observations illustrate the challenge of diagnosing milder forms of cystic fibrosis in adult subjects. The recognition of this diagnosis may lead to improvement in patient's care and to genetic counselling.

Mucoviscidose : du bon usage des explorations fonctionnelles respiratoires

INTRODUCTION

Neonatal screening for cystic fibrosis (CF) leads to early dedicated specialist care for all patients.

BACKGROUND

Pulmonary function tests (PFT) are mandatory for routine monitoring of CF patients. The aim of this article is to review the current guidelines for PFTs in CF, particularly the type of test, the age and the clinical status of the patient.

VIEWPOINT

The regular use of spirometry is generally accepted. Many other tests are used but their clinical value in the routine follow-up of CF patients remains to be established.

CONCLUSION

Further efforts should be made to evaluate the value of PFTs in CF, particularly in very young children.

Severity of scleroderma lung disease is related to alveolar concentration of nitric oxide

The alveolar concentration of exhaled nitric oxide (CA,(NO)) is increased in patients with systemic sclerosis (SSc), but whether this increase is related to the severity of interstitial lung disease (ILD) in SSc has not yet been investigated. In total, 58 SSc patients prospectively underwent pulmonary function tests (PFTs), echocardiogram and fibrosis scoring on pulmonary computed tomography (CT). Patients were divided into two groups according to the presence (or not) of ILD. Measurements of CA,(NO) were assessed in all SSc patients and compared with those obtained in 19 healthy volunteers. Relationships were sought between CA,(NO) PFTs and CT scan fibrosis scores. Overall, CA,(NO) was significantly increased in SSc patients (median (range) 6.2 (3.8-9.9) ppb) as compared with controls (2.0 (1.2-3.0) ppb). Among SSc patients, CA,(NO) was significantly higher in patients with ILD compared with patients without ILD (n = 33, 7.5 (5.2-11.9) ppb versus n = 25, 4.9 (3.1-7.0) ppb, respectively). CA,(NO) was inversely related to total lung capacity (r = -0.34) and the diffusing capacity of the lung for carbon monoxide (r = -0.37) and was directly related to CT scan fibrosis scores (r = 0.36). An increased alveolar concentration of exhaled nitric oxide could, at least in part, either reflect or contribute to the severity of lung disease and could be used to noninvasively assess the extent of interstitial lung disease in systemic sclerosis.

Reduced exhaled NO is related to impaired nasal potential difference in patients with cystic fibrosis

Nitric oxide (NO) plays a central role in many airway physiological functions, and its production appears to be related with progression of lung disease in patients with cystic fibrosis (CF). However, underlying mechanisms which specifically link NO and CF-related lung disease remain unclear. Following in vitro and animal studies suggesting a role for NO in ion transport in various epithelia, this work investigates the relationship between transepithelial baseline potential difference (BPD), an index of airway ion transport, and exhaled NO in the airways of adult patients with CF. Association with other phenotypic traits, lung function tests and CFTR genotype was also assessed. Using simple linear regression, F(E)NO and transepithelial BPD values were significantly inversely correlated (p<0.001, r=-0.53). Polynomial analysis evidenced an asymptotic relationship between F(E)NO and BPD values, yielding a plateau for absolute BPD values above 50 mV. This relation was not altered by adjustment for clinical and genetic characteristics of the patients. The relationship between exhaled NO and transepithelial BPD suggests that low NO concentrations likely worsens airway ion transport impairment resulting from CFTR defect. These results fit with experimental studies that suggest the inhibitory effect of NO on sodium absorption, which is the main determinant of airway basal transepithelial conductance.

Nasal airway ion transport is linked to the cystic fibrosis phenotype in adult patients

BACKGROUND

This study was conducted to determine whether the major nasal airway ion transport abnormalities in cystic fibrosis (that is, defective cAMP regulated chloride secretion and basal sodium hyperabsorption) are related to the clinical expression of cystic fibrosis and/or to the genotype.

METHODS

Nasal potential difference was measured in 79 adult patients with cystic fibrosis for whom clinical status, respiratory function, and CFTR genotype were determined.

RESULTS

In univariate and multivariate analysis, patients with pancreatic insufficiency were more likely to have low responses to low chloride (odds ratio (OR) 8.6 (95% CI 1.3 to 58.5), p = 0.03) and isoproterenol (OR 11.2 (95% CI 1.3 to 93.9), p = 0.03) solutions. Similarly, in univariate and multivariate analysis, patients with poor respiratory function (forced expiratory volume in 1 second <50% of predicted value) were more likely to have an enhanced response to amiloride solution (OR 3.7 (95% CI 1.3 to 11.0), p = 0.02). However, there was no significant relationship between nasal potential difference and the severity of the genotype.

CONCLUSIONS

Nasal epithelial ion transport in cystic fibrosis is linked to the clinical expression of the disease. The pancreatic status appears to be mostly related to the defect in epithelial chloride secretion whereas the respiratory status is mostly related to abnormal sodium transport and the regulatory function of the CFTR protein.

Recombinant Escherichia coli as a gene delivery vector into airway epithelial cells

To transfer genes into airway epithelial cells, we have generated auxotrophic dap Escherichia coli BM2710 mutant that expresses the invasin of Yersinia pseudotuberculosis and the listeriolysin of Listeria monocytogenes. E. coli BM2710 harboring a plasmid carrying the gfp gene was incubated with immortalized normal or cystic fibrosis (CF) airway epithelial cells or with primary bronchial epithelial cells grown as an explant-outgrowth cell culture model. Approximately 2% of immortalized cells expressed GFP. Few primary cells were transfected that were always poorly differentiated and located at the edge of the outgrowth. This was consistent with the expression of beta1-integrins only on these cells and with the required interaction for cell entry of E. coli expressing the invasin with beta1-integrins. The subsequent intracellular trafficking of E. coli BM2710 studied by confocal and electronic microscopy showed that the E. coli-containing phagosomes rapidly matured into phagolysosomes. This is the first demonstration that recombinant bacteria are able to transfer genes into primary airway epithelial cells, provided that they are able to invade the cells.

Glycofection: facilitated gene transfer by cationic glycopolymers

Mammalian cells express several types of lectins involved in intracellular trafficking, including endocytosis, interorganelle routing and putatively nuclear import. In order to enhance the gene transfer efficiency, glycosylated cationic polymers have been used as nonviral vectors. We developed a simple method to convert reducing saccharides into glycosynthons. Glycosynthons are used to synthesize cationic glycopolymers, called Glycofectins. Glycofectins interact with a plasmid to give a glycoplex, a compacted form of a polymer/DNA complex. The high glycoplex efficiency depends on the sugar involved in the uptake and in the intracellular trafficking of glycoplexes. The present paper deals with glycoplexes, with gene transfer into cystic fibrosis airway epithelial and gland serous cells, and with some of the problems that have to be solved before clinical trials.

Intracellular rate-limiting steps of gene transfer using glycosylated polylysines in cystic fibrosis airway epithelial cells

To identify the intracellular barriers to efficient gene transfer, we studied the intracellular trafficking of biotinylated plasmid DNA complexed with either fluorescein-conjugated lactosylated or mannosylated polylysine by confocal microscopy. Both are known to be taken up by cystic fibrosis airway epithelial cells (SigmaCFTE29o- cells), but their gene transfer efficiencies differ markedly: lactosylated polylysine is the most efficient glycosylated polylysine while mannosylated polylysine is quite inefficient for gene transfer. Mannosylated complexes appeared to stay longer in endosomes labeled by anti-transferrin receptor antibody than lactosylated complexes (from 30 min to 3 h and from 10 min to 30 min, respectively). At 24 h, higher percentages of mannosylated than lactosylated complexes were localized inside lysosomes labeled by anti-LAMP-1 antibody (41.8 +/- 6.6% versus 19.8 +/- 5.2%, respectively, P < 0.05). Between 30 min and 8 h, complexes reached the nuclei labeled by anti-lamin A/C antibody and no difference was observed between the nuclear amounts of mannosylated and lactosylated complexes. However, as analyzed by a nuclease S1 transcription assay, initiation of transcription was prevented when plasmid DNA was complexed to mannosylated polylysine. Our results indicate that the major limiting steps for mannosylated versus lactosylated polylysine transfer of plasmid DNA are delayed exit from endosomes, high accumulation in lysosomes and limited transcription of the complexed plasmid DNA.

Targeting of cell receptors and gene transfer efficiency: a balancing act

Vectors conjugated with ligands recognized by cell surface receptors are of interest for cystic fibrosis gene therapy since these vectors would allow cell-specific targeting. However, an efficient and specific uptake may be abrogated by a subsequent intracellular trafficking leading to an inefficient gene transfer. This has been shown for polylysine substituted with mannose residues. While mannose-specific membrane lectins are predominantly expressed at the surface of airway cells and mannosylated complexes are the most efficiently incorporated glycosylated complexes in these cells, mannosylated complexes lead to a low gene transfer efficiency because of an inefficient exit from endosomal compartments, a high accumulation in lysosomes and an inefficient nuclear import. In contrast, the entry of low amounts of lactosylated complexes is balanced by more efficient intracellular trafficking, leading to an efficient gene transfer. This emphasizes that for a successful gene transfer, it is necessary to find the balance between efficient and specific uptake, and intracellular trafficking that overcomes the various cellular barriers and enables the plasmid to reach the nucleus.

Gene therapy of cystic fibrosis: the glycofection approach

Many cells express surface membrane lectins that selectively bind and carry glycoconjugates into intracellular endosomes; in addition, various intracellular membrane and soluble lectins act as shuttles between different compartments. On this basis, we developed glycosylated polycations, now called glycofectins (glycosylated polylysine and polyethyleneimine). Recently, we set up a simple way to transform oligosaccharides into glycosynthons suitable to substitute proteins or polymers. Glycofectins bind plasmid DNA leading to compact glycoplexes. Glycoplexes prepared with glycofectins were found to be much more active than naked plasmid to transfer genes to various types of cells including human airway epithelial and serous cells. The gene transfer efficiency was found to depend on the nature of the sugars borne by glycofectins. It appeared that the sugar-dependent efficiency was not only related to the uptake but also to the intracellular traffic of glycoplexes.

Histidylated polylysine as a synthetic vector for gene transfer into immortalized cystic fibrosis airway surface and airway gland serous cells

BACKGROUND

We recently designed a cationic polymer called histidylated polylysine made of polylysine partially substituted with histidyl residues which become protonated at slightly acidic pH. This polymer is thought to induce the leakage of acidic vesicles containing plasmid/histidylated polylysine complexes.

METHODS

and results Here, we have analyzed the ability of histidylated polylysine to transfer reporter or CFTR genes into immortalized cystic fibrosis airway surface epithelial cells (sigmaCFTE29o- cells) and airway gland serous cells (CF-KM4 cells) which are both important targets for cystic fibrosis gene therapy. The luciferase reporter gene expression measured after gene transfer with histidylated polylysine into both cell lines was quite high and similar to that obtained with commercially available vectors. In addition, the level of expression was not dependent on the presence of a membrane disrupting agent such as chloroquine. Histidylated complexes were present in slightly acidic non-lysosomal cellular compartments as shown by a cytological approach using biotinylated plasmid, lysosome-specific antibodies and confocal microscopy. Histidylated complexes appeared to be of small size when prepared at low ionic strength and formed aggregates upon increasing the ionic strength. However, aggregate formation was prevented by the addition of 10% fetal bovine serum. Gene transfer efficiency varied with the size of the complexes and decreased when small particles were used.

CONCLUSIONS

These results suggest that histidylated polylysine may be an efficient non-viral vector for gene transfer into cystic fibrosis airway surface epithelial cells and airway gland serous cells.

[Diagnosis of cystic fibrosis in adults]

Cystic fibrosis is a genetic recessive disorder caused by mutations in the gene that encodes the CFTR protein. The diagnosis of cystic fibrosis is usually established in early childhood but it is now being made in an increasing number of adults. Many of them present with mild or atypical cystic fibrosis clinical features, mostly lung disease. In addition, some adults with congenital bilateral absence of vas deferens or idiopathic chronic pancreatitis may be assigned a diagnosis of cystic fibrosis. The diagnosis of cystic fibrosis in adults should be based on the presence of one or more characteristic clinical features, a history of cystic fibrosis in a sibling, plus evidence of defective CFTR function as documented by elevated sweat chloride concentrations or abnormal ion transport across the nasal epithelium, or identification of mutations on both CFTR genes.

Efficient gene transfer into human normal and cystic fibrosis tracheal gland serous cells with synthetic vectors

Submucosal gland serous cells are believed to play a major role in the physiopathology of cystic fibrosis (CF) and may represent an important target for CF gene therapy. We have studied the efficiency of reporter gene transfer into immortalized normal (MM-39) and CF (CF-KM4) human airway epithelial gland serous cells using various synthetic vectors: glycosylated polylysines (glycofectins), polyethylenimine (PEI) (25 and 800 kD), lipofectin, and lipofectAMINE. In both cell lines, a high luciferase activity was achieved with various glycofectins, with PEI 25 kD, and with lipofectAMINE. After three transfections applied daily using alpha-glycosylated polylysine, 20% of the cells were transfected. At 24 h after CF transmembrane conductance regulator (CFTR) gene transfer into CF-KM4 cells using alpha-glycosylated polylysine, the immunolocalization of CFTR was analyzed by laser scanning confocal microscopy and the transgenic CFTR was detected by an intense labeling of the plasma membrane. The presence of membrane lectins, i. e., cell surface receptors binding oligosaccharides, was also examined on MM-39 and CF-KM4 cells by assessing the binding and uptake of fluorescein-labeled neoglycoproteins and fluorescein-labeled glycoplexes (glycofectins complexed to plasmid DNA). Among all the neoglycoproteins and glycoplexes tested, those bearing alpha-mannosylated derivatives were most efficiently taken up by both normal and CF gland serous cells. However, alpha-mannosylated polylysine was quite inefficient for gene transfer, indicating that the efficiency of gene transfer is determined both by the uptake of the complexes and also by their intracellular trafficking. Moreover, our results show that an efficient in vitro gene transfer was achieved in human airway gland serous cells with the same synthetic vectors described to efficiently transfect human airway surface epithelial cells.