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Aim: To examine the trajectory of forced expiratory volume in 1 s (FEV 1 ) using data from the European Cystic Fibrosis Society patient registry (ECFPR) collected from 2008 to 2016, i.e. the era before highly effective modulator therapy (HEMT). We evaluated risk factors for FEV 1 decline., Methods: The study population included patients with a confirmed diagnosis of cystic fibrosis recorded in the ECFPR (2008-2016). The evolution of FEV 1 % predicted (%FEV 1 ) with age, and the yearly change in %FEV 1 were evaluated. Risk factors considered were cystic fibrosis transmembrane conductance regulator ( -CFTR ) mutation class, gender, age at diagnosis, neonatal screening, meconium ileus, sweat chloride concentration at diagnosis and country's income level., Results: We used 199 604 FEV 1 recordings from 38 734 patients. The fastest decline was seen during puberty and in patients diagnosed before the age of 10 years. Males had a higher %FEV 1 , but a higher yearly %FEV 1 loss between the ages of 15 and 25 years. We showed stabilisation and even improvement in %FEV 1 over age in adults with a class III CFTR mutation, but a steady decline in patients homozygous for F508del or with both mutations of classes I/II. A faster decline in %FEV 1 was found in patients from low-income countries compared to a similar %FEV 1 evolution in patients from middle- and high-income countries., Conclusions: These longitudinal FEV 1 data reflect the reality of cystic fibrosis across Europe in the era pre-HEMT, and can serve as baseline for comparison with the post-HEMT era. The similar evolution in middle- and high-income countries underlines opportunities for low-income countries., Competing Interests: Conflict of interest: The authors declare no conflict of interest., (Copyright ©The authors 2023.)

Rationale: Given the vast number of cystic fibrosis transmembrane conductance regulator ( CFTR ) mutations, biomarkers predicting benefit from CFTR modulator therapies are needed for subjects with cystic fibrosis (CF)., Objectives: To study CFTR function in organoids of subjects with common and rare CFTR mutations and evaluate correlations between CFTR function and clinical data., Methods: Intestinal organoids were grown from rectal biopsies in a cohort of 97 subjects with CF. Residual CFTR function was measured by quantifying organoid swelling induced by forskolin and response to modulators by quantifying organoid swelling induced by CFTR correctors, potentiator and their combination. Organoid data were correlated with clinical data from the literature., Results: Across 28 genotypes, residual CFTR function correlated (r 2 =0.87) with sweat chloride values. When studying the same genotypes, CFTR function rescue by CFTR modulators in organoids correlated tightly with mean improvement in lung function (r 2 =0.90) and sweat chloride (r 2 =0.95) reported in clinical trials. We identified candidate genotypes for modulator therapy, such as E92K, Q237E, R334W and L159S. Based on organoid results, two subjects started modulator treatment: one homozygous for complex allele Q359K_T360K, and the second with mutation E60K. Both subjects had major clinical benefit., Conclusions: Measurements of residual CFTR function and rescue of function by CFTR modulators in intestinal organoids correlate closely with clinical data. Our results for reference genotypes concur with previous results. CFTR function measured in organoids can be used to guide precision medicine in patients with CF, positioning organoids as a potential in vitro model to bring treatment to patients carrying rare CFTR mutations., Competing Interests: Conflict of interest: A.S. Ramalho has nothing to disclose. Conflict of interest: E. Fürstová has nothing to disclose. Conflict of interest: A.M. Vonk has nothing to disclose. Conflict of interest: M. Ferrante reports grants and personal fees from Amgen, grants, personal fees and non-financial support from Biogen, Janssen, Pfizer and Takeda, personal fees and non-financial support from Boehringer Ingelheim, MSD, Falk and Ferring, personal fees from Sandoz, Lamepro, and Mylan, outside the submitted work. Conflict of interest: C. Verfaillie has nothing to disclose. Conflict of interest: L. Dupont has nothing to disclose. Conflict of interest: M. Boon is a member of the European Reference Network for Rare Respiratory Diseases (ERN-LUNG) – Project ID number 739546. Conflict of interest: M. Proesmans has nothing to disclose. Conflict of interest: J.M. Beekman reports personal fees from various industries (Vertex, Proteostasis, Teva, others) for costs related to conference presentations, outside the submitted work; and has a patent WO2013093812A3 with royalties paid by Hubrecht Organoid Technology. Conflict of interest: I. Sarouk has nothing to disclose. Conflict of interest: C. Vazquez Cordero has nothing to disclose. Conflict of interest: F. Vermeulen has nothing to disclose. Conflict of interest: K. De Boeck has provided consultancy for Boehringer, Protalix, Raptor, Novabiotics, Eloxx and Chiesi, has been member of steering committees/advisory boards and been PI in studies for Vertex, has provided consultancy and been PI in studies for Galapagos, and has received speaker fees from Teva, outside the submitted work., (Copyright ©ERS 2021.)

Nasal potential difference (NPD) quantifies abnormal ion transport in cystic fibrosis. It has gained acceptance as an outcome measure for the investigation of new therapies. To quantify the effect of solution temperature on NPD, we first examined the effect of switching from room temperature (20-25°C) to warmed (32-37°C) solutions and vice versa during each perfusion step. Secondly, standard protocols were repeated at both temperatures in the same subjects. Changing solution temperature did not alter NPD during perfusion with Ringer's solution (<1 mV) (p>0.1). During perfusion with zero chloride solution, changing from room temperature to warmed solutions tended to decrease absolute NPD (i.e. it became less negative) by 0.9 mV (p>0.1); changing from warmed to room temperature increased NPD by 2.1 mV (p<0.05). During isoprenaline perfusion, changing from room temperature to warmed solutions increased NPD by 1.5 mV (p<0.01) and from warmed to room temperature decreased NPD by 1.4 mV (p<0.05). For full protocols at room temperature or warmed in the same subjects, mean values were similar (n = 24). During warmed perfusion, group results for total chloride response had a larger standard deviation. As this increased variability will probably decrease the power of trials, this study suggests that solutions at room temperature should be recommended for the measurement of NPD.

In patients with cystic fibrosis, cystic fibrosis transmembrane conductance regulator (CFTR) biomarkers, such as sweat chloride concentration and/or nasal potential difference, are used as end-points of efficacy in phase-III clinical trials with the disease modifying drugs ivacaftor (VX-770), VX809 and ataluren. The aim of this project was to review the literature on reliability, validity and responsiveness of nasal potential difference, sweat chloride and intestinal current measurement in patients with cystic fibrosis. Data on clinimetric properties were collected for each biomarker and reviewed by an international team of experts. Data on reliability, validity and responsiveness were tabulated. In addition, narrative answers to four key questions were discussed and agreed by the team of experts. The data collected demonstrated the reliability, validity and responsiveness of nasal potential difference. Fewer data were found on reliability of sweat chloride concentration; however, validity and responsiveness were demonstrated. Validity was demonstrated for intestinal current measurement, but further information is required on reliability and responsiveness. For all three end-points, normal values were collected and further research requirements were proposed. This body of work adds useful information to support the promotion of CFTR biomarkers to surrogate end-points and to guide further research in the area.

A recent American registry analysis in cystic fibrosis (CF) children showed less lung function decline after starting inhaled corticosteroid (ICS) use. We therefore examined the influence of ICS treatment on lung function in Belgian CF patients. Data from patients ≥ 6 yrs of age were eligible, provided entries on lung function, height and ICS use were available in two consecutive years. Data after oral steroid use or transplant were excluded. 852 subjects contributed data with 2,976 data pairs analysed, 44.9% concerning years of ICS use. Yearly % predicted decline in forced expiratory volume in 1 s (FEV₁) was 1.07% lower during ICS use (p = 0.001). Subgroup analysis for age revealed that the lower FEV₁ decline rate during ICS use was only statistically significant in children 6-12 yrs of age (2.56%; p = 0.0003). Baseline FEV(1) was lower by 5.89% (p < 0.0001) in ICS users for all age groups combined, but there was no difference in baseline lung function in the children 6-12 yrs of age. In 6-12-yr-old children with CF, baseline lung function was similar in ICS users and nonusers, but annualised FEV₁ decline was 2.56% pred lower in ICS users. Our data therefore support recent American findings.

This European Respiratory Society task force has reviewed the evidence for paediatric medicines in respiratory disease occurring in adults and children. We describe off-licence use, research priorities and ongoing studies. Off-licence and off-label prescribing in children is widespread and potentially harmful. Research areas in asthma include novel formulations and regimens, and individualised prescribing. In cystic fibrosis, future studies will focus on screened infants and robust outcome measures are needed. Other areas include new enzyme and antibiotic formulations and the basic defect. Research into pneumonia should include evaluation of new antibacterials and regimens, rapid diagnostic tests and, in pleural infection, antibiotic penetration, fibrinolytics and surveillance. In uncommon conditions, such as primary ciliary dyskinesia, congenital pulmonary abnormalities or neuromuscular disorders, drugs indicated for other conditions (e.g. dornase alfa) are commonly used and trials are needed. In neuromuscular disorders, the beta-agonists may enhance muscle strength and are in need of evaluation. Studies of antibiotic prophylaxis, immunoglobulin and antifungal drugs are needed in immune deficiency. We hope that this summary of the evidence for respiratory medicines in children, highlighting gaps and research priorities, will be useful for the pharmaceutical industry, the paediatric committee of the European Medicines Agency, academic investigators and the lay public.

The source of acquisition of Pseudomonas aeruginosa in cystic fibrosis (CF) patients remains unknown. Patient-to-patient transmission has been well documented but the role of the environment as a source of initial infection is as yet unclear. In the present study, the origin of the first P. aeruginosa isolate in CF patients was investigated by comparing the P. aeruginosa genotype(s) from newly infected patients with genotypes of P. aeruginosa isolates from the home environment and from other patients from the same CF centre. A total of 50 newly infected patients were studied. P. aeruginosa could be cultured from 5.9% of the environmental samples, corresponding to 18 patients. For nine of these, the genotype of the environmental P. aeruginosa isolate was identical to the patient's isolate. In total, 72% of the environmental P. aeruginosa isolates were encountered in the bathroom. Patient-to-patient transmission within the CF centre could not be ruled out for three patients. In summary, a low prevalence of Pseudomonas aeruginosa was found in the home environment of the newly infected cystic fibrosis patients. The bathroom should be targeted in any preventive cleaning procedures. An environmental source of the new infection could not be ruled out in nine patients.

The current authors aimed to examine whether cystic fibrosis (CF) patients in Belgium shared Pseudomonas aeruginosa genotypes and to compare the genotypes of isolates from the same patients during two consecutive years. A Belgian databank of the P. aeruginosa genotypes of all colonised CF patients was created. Sputum samples from a total of 276 P. aeruginosa colonised patients during 2003, and from a subgroup of 95 patients in 2004, were analysed. Patients were asked about any social contact between each other by questionnaire. All P. aeruginosa isolates exhibiting different colonial morphology on McConkey agar were first genotyped using arbitrarily primed PCR, whereafter single representatives of each randomly amplified polymorphic DNA-type were further genotyped by fluorescent amplified fragment length polymorphism analysis. In the 213 patients from whom P. aeruginosa could be cultured (resulting in 910 isolates), a total of 163 genotypes were found. The majority (75%) of patients harboured only one genotype. In most of the limited number of clusters, previous contacts between patients could be suspected. In 80% of the patients studied during both years, P. aeruginosa genotype remained unchanged. In conclusion, most colonised cystic fibrosis patients harbour only one Pseudomonas aeruginosa genotype, despite showing different colonial morphotypes. The number of clusters is limited, and most patients seem to retain the same genotypic strain during both years.

Four separate categories of chronic Pseudomonas aeruginosa (Pa) infection in children with cystic fibrosis (CF) have been previously defined, based on airway cultures taken over the previous year. The aim of the present study was to evaluate this definition in the current authors' paediatric and adult CF clinic using clinical, immunological and lung function parameters. During follow-up, out of 193 patients, 55 (34%) CF patients had never been infected with Pa, 27 (17%) were free of Pa, 29 (18%) were intermittently infected and 51 (31%) were chronically infected. Disease severity markers, such as lung function, were significantly worse in the chronic group, especially in the paediatric population. Differences in adult patients were smaller and no longer significant. Pa antibodies differed strongly between the groups, and were very high (mean+/-sd 55.4+/-5.5) and highly statistically significant from all other groups in the chronic group. They were low and different from all other groups in the never group (1.8+/-0.6). Pa antibodies did not differ between the free of Pa and the intermittent group. In conclusion, the current authors confirmed an agreement between Pseudomonas aeruginosa status according to the new definition and clinical status, as well as with the level of Pseudomonas aeruginosa antibodies.

In Belgian cystic fibrosis (CF) clinics, sputum samples are evaluated on selective MAST medium routinely every 3 months. In this study, in 1993 and 1999, isolates were further examined by recA restriction fragment length polymorphism analysis and pulsed-field gel electrophoresis of genomic DNA restricted with SpeI. In 1993, 12 patients were colonised with Burkholderia cepacia complex (Bcc): B. cenocepacia (n=6), B. multivorans (n=3), B. stabilis (n=3). Four patients were colonised with the same B. cenocepacia strain; two with the same B. stabilis strain. After 5 yrs, three B. cenocepacia- and one B. multivorans-colonised patients had died. In 1999, Bcc was isolated in 12 patients: B. multivorans (n=9), B. stabilis (n=1) and B. cenocepacia (n=2). Three patients were colonised by the same B. multivorans strain. Compared to matched controls, the 5 yr outcome was poor; four B. cepacia patients died and none of the control patients died. Lung-function evolution was poor. In conclusion, the rate of colonisation in Belgian cystic fibrosis patients is stable and low. Burkholderia cenocepacia was most prevalent in 1993; Burkholderia multivorans in 1999. The cross-infection rate is low. Three patients had transient colonisation. The impact of Burkholderia cepacia complex on morbidity in the Belgian cystic fibrosis population is high and not limited to Burkholderia cenocepacia.

In this European study, the phenotype in 68 patients, homozygous or compound heterozygous for the G85E mutation, was investigated. Each index case was compared with two cystic fibrosis (CF) patients from the same clinic, matched for age and sex: one with pancreatic sufficiency (PS) and one with pancreatic insufficiency (PI). When comparing 31 G85E/F508del and F508del/F508del patients, there were no differences in median age at diagnosis, mean sweat chloride value, most recent weight for height, most recent forced expiratory volume in one second % predicted, prevalence of chronic Pseudomonas aeruginosa colonisation and typical CF complications. However, PI was less frequent in the G85E/F508del group. Comparison of 55 G85E patients (with second mutation known and not classified as mild) with PS controls (n=44) showed that the G85E patients had a significantly higher sweat chloride, more often failure to thrive at diagnosis, higher prevalence of PI, worse current weight for height, higher prevalence of chronic P. aeruginosa colonisation and liver cirrhosis. Pulse-chase experiments revealed that G85E cystic fibrosis transmembrane conductance regulator failed to mature on a M470 as well as on a V470 background. Therefore, G85E is a class II mutation. Although there is variability in its clinical presentation, G85E mutation results in a severe phenotype.

The impulse oscillation system (IOS) has been developed recently to measure respiratory system resistance (Rrs) and reactance (Xrs) at different frequencies up to > or = 25 Hz. IOS has, however, not been validated against established techniques. This study compared IOS with the classical pseudorandom noise forced oscillation technique (FOT) and body plethysmographic airway resistance (Raw) in 49 subjects with a variety of lung disorders and a wide range of Raw (0.10-1.28 kPa x L(-1) x s). Rrs,IOS was slightly greater than Rrs,FOT, especially at lower frequencies, with a mean +/- SD difference at 5-6 Hz of 0.14 +/- 0.09 kPa x L(-1) x s. Comparisons with the wave-tube technique applied on two analogues indicated an overestimation by IOS. Xrs,IOS and Xrs,FOT were very similar, with a slightly higher resonant frequency with IOS than with FOT (mean difference +/- SD 1.35 +/- 3.40 Hz). Raw was only moderately correlated with Rrn,FOT and Rrs-IOS; although the mean differences were small (0.04 +/- 0.14 kPa x L(-1)s for Rrs6,FOT and -0.10 +/- 0.14 kPa x L(-1) x s for Rrs5,IOS), IOS and FOT markedly underestimated high resistance values. In conclusion, the impulse oscillation system yields respiratory system resistance and reactance values similar, but not identical to those provided by the forced oscillation technique.

A culture from the lower airway secretions is the optimal sample to guide antibiotic therapy in cystic fibrosis (CF) lung disease. The authors therefore examined whether sputum induction is an efficient, safe and acceptable procedure in CF children without spontaneous expectorations. Nineteen patients were studied. Their mean age (range) was 8.6 yrs (4.3-15.2 yrs). Their mean forced expiratory volume in one second (FEV1) was 88% predicted (46-122%). NaCl solutions from 0.9-6% were inhaled, after baseline lung function tests before and after salbutamol. All patients did produce secretions. Alveolar macrophages were present in 16/19 induced samples. The procedure induced minor but significant bronchoconstriction: the mean change (range) in postsalbutamol FEV1 (% pred) was -7 (-24-16). Percutaneous oxygen saturation remained above 90% in all children. The test had to be discontinued in one child because of cough and wheeze. Acceptability of the procedure evaluated using a visual analogue scale from -7-7 showed a mean value (range) at the final concentration of -1.23 (-6.16-5.88). It is concluded that sputum induction is possible, safe and acceptable in cystic fibrosis children who do not expectorate spontaneously.

Few data are available on the bronchodilator response in preschool children. This study was set up to study baseline lung function and bronchodilator responses in healthy and asthmatic children younger than 7 yrs old. In 281 preschool children attending kindergarten (age range 2.7-6.6 yrs old) respiratory system resistance (Rrs) and reactance (Xrs) by impulse oscillation system at 5, 10, 15, 20, 25 and 35 Hz as well as resonance frequency (f0) were measured before and 20 min after 200 microg inhaled salbutamol by a metered-dose inhaler connected to a spacer device. Thirty-four of them were diagnosed as asthmatics based on a validated standardized questionnaire. The mean Rrs (+/-SD) at 5 Hz (Rrs,5) was 1.03 (+/-0.24) kPa x L(-1) x s for healthy children and 1.09 (+/-0.26) kPa x L(-1) x s for stable asthmatics. The mean change in Rrs,5 after salbutamol was -0.13 (+/-0.20) kPa x L(-1) x s for the healthy children and -0.09 (+/-0.25) kPa x L(-1) x s for the asthmatic group. The scatter for the measurements was striking. Neither baseline values of impulse oscillation nor its changes after bronchodilator administration was significantly different between healthy and stable asthmatic children. A change in respiratory system resistance at 5 Hz of 40% is to be considered the cut-off for a " positive" bronchodilator response.