Lung structural and functional impairments in young children with cystic fibrosis diagnosed following newborn screening - A nationwide observational study.

BACKGROUND: Non-invasive and sensitive clinical endpoints are needed to monitor onset and progression of early lung disease in children with cystic fibrosis (CF). We compared lung clearance index (LCI), FEV1, functional and structural lung magnetic resonance imaging (MRI) outcomes in Swiss children with CF diagnosed following newborn screening. METHODS: Lung function (LCI, FEV1) and unsedated functional and structural lung MRI was performed in 79 clinically stable children with CF (3 - 8 years) and 75 age-matched healthy controls. Clinical information was collected throughout childhood. RESULTS: LCI, ventilation and perfusion defects, and structural MRI scores were significantly higher in children with CF compared with controls, but FEV1 was not different between groups. Lung MRI outcomes correlated significantly with LCI (morphology score (r = 0.56, p < 0.001); ventilation defects (r = 0.43, p = 0.001); perfusion defects (r = 0.64, p < 0.001), but not with FEV1. Lung MRI outcomes were more sensitive to detect impairments in children with CF (abnormal ventilation and perfusion outcomes in 47 %, morphology score in 30 %) compared with lung function (abnormal LCI in 21 % and FEV1 in 4.8 %). Pulmonary exacerbations, respiratory hospitalizations, and increase in patient-reported cough was associated with higher LCI and higher structural and functional MRI outcomes. CONCLUSIONS: The LCI and lung MRI outcomes non-invasively detect even mild early lung disease in young children with CF diagnosed following newborn screening. Pulmonary exacerbations and early respiratory symptoms were risk factors for structural and functional impairment in childhood.

Signal-correction errors in the EasyOne Pro LAB multiple-breath washout device significantly impact outcomes in children and adults.

Multiple-breath washout (MBW) is an established technique to assess functional residual capacity (FRC) and ventilation inhomogeneity in the lung. Indirect calculation of nitrogen concentration requires accurate measurement of gas concentrations. To investigate the accuracy of the CO2 concentration and molar mass (MM) values used for the indirect calculation of nitrogen concentration in a commercial MBW device [EasyOne Pro LAB (EOPL), ndd Medizintechnik AG, Switzerland] and its impact on outcomes. We used high-precision gas mixtures to evaluate CO2 and MM sensor output in vivo and in vitro. We developed updated algorithms to correct observed errors and assessed the impact on MBW outcomes and FRC measurement accuracy compared with body plethysmography. The respiratory exchange ratio (RER)-based adjustment of the measured CO2 signal used in the EOPL led to an overestimated CO2 signal (range -0.1% to 1.0%). In addition, an uncorrected dependence on humidity was identified. These combined effects resulted in an overestimation of expired nitrogen concentrations (range -0.7% to 2.6%), and consequently MBW outcomes. Corrected algorithms reduced the mean (SD) cumulative expired volume by 15.8% (9.7%), FRC by 6.6% (3.0%), and lung clearance index by 9.9% (7.6%). Differences in FRC between the EOPL and body plethysmography further increased. Inadequate signal correction causes RER- and humidity-dependent expired nitrogen concentration errors and overestimation of test outcomes. Updated algorithms reduce average signal error, however, RER values far from the population average still cause measurement errors. Despite improved signal accuracy, the updated algorithm increased the difference in FRC between the EOPL and body plethysmography.NEW & NOTEWORTHY We investigated the accuracy of the molar mass (MM) and CO2 sensors of a commercial multiple-breath washout device (ndd Medizintechnik AG, Switzerland). We identified humidity and respiratory exchange ratio-dependent errors that in most measurements resulted in an overestimation of expired nitrogen concentrations, and consequently, MBW results. Functional residual capacity and lung clearance index decreased by 6.6% and 9.9%, respectively. Despite improved signal accuracy, the difference in FRC between the EOPL and body plethysmography increased.

Simultaneous multiple breath washout and oxygen-enhanced magnetic resonance imaging in healthy adults.

Lung function testing and lung imaging are commonly used techniques to monitor respiratory diseases, such as cystic fibrosis (CF). The nitrogen (N2) multiple-breath washout technique (MBW) has been shown to detect ventilation inhomogeneity in CF, but the underlying pathophysiological processes that are altered are often unclear. Dynamic oxygen-enhanced magnetic resonance imaging (OE-MRI) could potentially be performed simultaneously with MBW because both techniques require breathing of 100% oxygen (O2) and may allow for visualisation of alterations underlying impaired MBW outcomes. However, simultaneous MBW and OE-MRI has never been assessed, potentially as it requires a magnetic resonance (MR) compatible MBW equipment. In this pilot study, we assessed whether MBW and OE-MRI can be performed simultaneously using a commercial MBW device that has been modified to be MR-compatible. We performed simultaneous measurements in five healthy volunteers aged 25-35 years. We obtained O2 and N2 concentrations from both techniques, and generated O2 wash-in time constant and N2 washout maps from OE-MRI data. We obtained good quality simultaneous measurements in two healthy volunteers due to technical challenges related to the MBW equipment and poor tolerance. Oxygen and N2 concentrations from both techniques, as well as O2 wash-in time constant maps and N2 washout maps could be obtained, suggesting that simultaneous measurements may have the potential to allow for comparison and visualization of regional differences in ventilation underlying impaired MBW outcomes. Simultaneous MBW and OE-MRI measurements can be performed with a modified MBW device and may help to understand MBW outcomes, but the measurements are challenging and have poor feasibility.

Variability of clinically measured lung clearance index in children with cystic fibrosis.

RATIONALE: The lung clearance index (LCI) is increasingly being used in the clinical surveillance of patients with cystic fibrosis (CF). However, there are limited data on long-term variability and physiologically relevant changes in LCI during routine clinical surveillance. OBJECTIVES: To evaluate the long-term variability of LCI and propose a threshold for a physiologically relevant change. METHODS: In children aged 4-18 years with CF, LCI was measured every 3 months as part of routine clinical surveillance during 2011-2020 in two centers. The variability of LCI during periods of clinical stability was assessed using mixed-effects models and was used to identify thresholds for physiologically relevant changes. RESULTS: Repeated LCI measurements of acceptable quality (N = 858) were available in 100 patients with CF; for 74 patients, 399 visits at clinical stability were available. The variability of repeated LCI measurements over time expressed as the coefficient of variation (CV%) was 7.4%. The upper limit of normal (ULN) for relative changes in LCI between visits was 19%. CONCLUSION: We report the variability of LCI in children and adolescents with CF during routine clinical surveillance. According to our data, a change in LCI beyond 19% may be considered physiologically relevant. These findings will help guide clinical decisions according to LCI changes.

Monitoring disease progression in childhood bronchiectasis.

Bronchiectasis (not related to cystic fibrosis) is a chronic lung disease caused by a range of etiologies but characterized by abnormal airway dilatation, recurrent respiratory symptoms, impaired quality of life and reduced life expectancy. Patients typically experience episodes of chronic wet cough and recurrent pulmonary exacerbations requiring hospitalization. Early diagnosis and management of childhood bronchiectasis are essential to prevent respiratory decline, optimize quality of life, minimize pulmonary exacerbations, and potentially reverse bronchial disease. Disease monitoring potentially allows for (1) the early detection of acute exacerbations, facilitating timely intervention, (2) tracking the rate of disease progression for prognostic purposes, and (3) quantifying the response to therapies. This narrative review article will discuss methods for monitoring disease progression in children with bronchiectasis, including lung imaging, respiratory function, patient-reported outcomes, respiratory exacerbations, sputum biomarkers, and nutritional outcomes.

P2Y1 purinergic receptor identified as a diabetes target in a small-molecule screen to reverse circadian ß-cell failure.

The mammalian circadian clock drives daily oscillations in physiology and behavior through an autoregulatory transcription feedback loop present in central and peripheral cells. Ablation of the core clock within the endocrine pancreas of adult animals impairs the transcription and splicing of genes involved in hormone exocytosis and causes hypoinsulinemic diabetes. Here, we developed a genetically sensitized small-molecule screen to identify druggable proteins and mechanistic pathways involved in circadian ß-cell failure. Our approach was to generate ß-cells expressing a nanoluciferase reporter within the proinsulin polypeptide to screen 2640 pharmacologically active compounds and identify insulinotropic molecules that bypass the secretory defect in CRISPR-Cas9-targeted clock mutant ß-cells. We validated hit compounds in primary mouse islets and identified known modulators of ligand-gated ion channels and G-protein-coupled receptors, including the antihelmintic ivermectin. Single-cell electrophysiology in circadian mutant mouse and human cadaveric islets revealed ivermectin as a glucose-dependent secretagogue. Genetic, genomic, and pharmacological analyses established the P2Y1 receptor as a clock-controlled mediator of the insulinotropic activity of ivermectin. These findings identify the P2Y1 purinergic receptor as a diabetes target based upon a genetically sensitized phenotypic screen.

Circadian rhythms ­ 'inbuilt' 24-hour cycles ­ control many aspects of behaviour and physiology. In mammals, they operate in nearly all tissues, including those involved in glucose metabolism. Recent studies have shown that mice with faulty genes involved in circadian rhythms, the core clock genes, can develop diabetes. Diabetes arises when the body struggles to regulate blood sugar levels. In healthy individuals, the hormone insulin produced by beta cells in the pancreas regulates the amount of sugar in the blood. But when beta cells are faulty and do not generate sufficient insulin levels, or when insulin lacks the ability to stimulate cells to take up glucose, diabetes can develop. Marcheva, Weidemann, Taguchi et al. wanted to find out if diabetes caused by impaired clock genes could be treated by targeting pathways regulating the secretion of insulin. To do so, they tested over 2,500 potential drugs on genetically modified beta cells with faulty core clock genes. They further screened the drugs on mice with the same defect in their beta cells. Marcheva et al. identified one potential compound, the anti-parasite drug ivermectin, which was able to restore the secretion of insulin. When ivermectin was applied to both healthy mice and mice with faulty beta cells, the drug improved the control over glucose levels by activating a specific protein receptor that senses molecules important for storing and utilizing energy. The findings reveal new drug targets for treating forms of diabetes associated with deregulation of the pancreatic circadian clock. The drug screening strategy used in the study may also be applied to reveal mechanisms underlying other conditions associated with disrupted circadian clocks, including sleep loss and jetlag.

Association of lung clearance index with survival in individuals with cystic fibrosis.

BACKGROUND: The lung clearance index (LCI) assesses global ventilation inhomogeneity and is a sensitive biomarker of airway function in cystic fibrosis (CF) lung disease. We examined the association of LCI with the risk of death or lung transplantation (LTx) in individuals with CF. METHODS: We performed a retrospective analysis in a cohort of individuals with CF aged ≥5 years with LCI and forced expired volume in 1 s (FEV1) measurements performed between 1980 and 2006. The outcome was time until death or LTx. We used the earliest available LCI and FEV1 values in a Cox proportional hazards regression adjusted for demographic and clinical variables. For sensitivity analyses, we used the mean of the first three LCI and FEV1 measurements, stratified the cohort based on age, and investigated individuals with normal FEV1. RESULTS: In total, 237 individuals with CF with a mean (range) age of 13.9 (5.6-41.0) years were included. The time-to-event analysis accrued 3813 person-years and 94 (40%) individuals died or received LTx. Crude hazard ratios were 1.04 (95% CI 1.01-1.06) per 1.0 z-score increase in LCI and 1.25 (95% CI 1.11-1.41) per 1.0 z-score decrease in FEV1. After adjusting LCI and FEV1 mutually in addition to sex, age, body mass index and number of hospitalisations, hazard ratios were 1.04 (95% CI 1.01-1.07) for LCI and 1.12 (95% CI 0.95-1.33) for FEV1. Sensitivity analyses yielded similar results and using the mean LCI strengthened the associations. CONCLUSIONS: Increased ventilation inhomogeneity is associated with greater risk of death or LTx. Our data support LCI as novel surrogate of survival in individuals with CF.

Quality of life is poorly correlated to lung disease severity in school-aged children with cystic fibrosis.

BACKGROUND: There is no data exclusively on the relationship between health-related quality-of-life (HRQOL) and lung disease severity in early school-aged children with cystic fibrosis (CF). Using data from the Australian Respiratory Early Surveillance Team for Cystic Fibrosis (AREST CF) we assessed the relationships between HRQOL, lung function and structure. METHODS: 125 children aged 6.5-10 years enrolled in the AREST CF program were included from CF clinics at Royal Children's Hospital (RCH), Melbourne (n = 66) and Perth Children's Hospital (PCH), Perth (n = 59), Australia. Demographics, HRQOL measured by Cystic Fibrosis Questionnaire-Revised (CFQ-R), spirometry, multiple-breath washout (MBW) and chest CT were collected across two years. Correlation between CFQ-R scores and lung structure/function parameters and agreement between parent-proxy and child-reported HRQOL were evaluated. RESULTS: No correlation was observed between most CFQ-R domain scores and FEV1 z-scores, excepting weak-positive correlation with parent CFQ-R Physical (rho = 0.21, CI 0.02-0.37), and Weight (rho = 0.21, CI 0.03-0.38) domain and child Body domain (rho = 0.26, CI 0.00-0.48). No correlation between most CFQ-R domain scores and LCI values was noted excepting weak-negative correlation with parent Respiratory (rho = -0.23, CI -0.41--0.05), Emotional (rho = -0.24, CI -0.43--0.04), and Physical (-0.21, CI -0.39--0.02) domains. Furthermore, structural lung disease on CT data demonstrated little to no association with CFQ-R parent and child domain scores. Additionally, no agreement between child self-report and parent-proxy CFQ-R scores was observed across the majority of domains and visits. CONCLUSION: HRQOL correlated poorly with lung function and structure in early school-aged children with CF, hence clinical trials should consider these outcomes independently when determining study end-points.

Correction of sensor crosstalk error in Exhalyzer D multiple-breath washout device significantly impacts outcomes in children with cystic fibrosis.

Nitrogen multiple-breath washout is an established technique to assess functional residual capacity and ventilation inhomogeneity in the lung. Accurate measurement of gas concentrations is essential for the appropriate calculation of clinical outcomes. We investigated the accuracy of oxygen and carbon dioxide gas sensor measurements used for the indirect calculation of nitrogen concentration in a commercial multiple-breath washout device (Exhalyzer D, Eco Medics AG, Duernten, Switzerland) and its impact on functional residual capacity and lung clearance index. High-precision calibration gas mixtures and mass spectrometry were used to evaluate sensor output. We assessed the impact of corrected signal processing on multiple-breath washout outcomes in a data set of healthy children and children with cystic fibrosis using custom analysis software. We found inadequate correction for the cross sensitivity of the oxygen and carbon dioxide sensors in the Exhalyzer D device. This results in an overestimation of expired nitrogen concentration and consequently, multiple-breath washout outcomes. Breath-by-breath correction of this error reduced the mean (SD) cumulative expired volume by 19.6% (5.0%), functional residual capacity by 8.9% (2.2%), and lung clearance index by 11.9% (4.0%). It also substantially reduced the level of the tissue nitrogen signal at the end of measurements. Inadequate correction for cross sensitivity in the oxygen and carbon dioxide gas sensors of the Exhalyzer D device leads to an overestimation of functional residual capacity and lung clearance index. Correction of this error is possible and could be applied by reanalyzing the measurements in an updated software version.NEW & NOTEWORTHY We investigated the sensor accuracy of a prominent nitrogen multiple-breath washout (N2MBW) device (Eco Medics AG, Duernten, Switzerland) as a possible cause of lack of comparability between outcomes of different MBW devices and methods. We identified an error in the nitrogen concentration calculation of this device, which results in a 10%-15% overestimation of primary outcomes, functional residual capacity, and lung clearance index. It also leads to a significant overestimation of nitrogen back-diffusion into the lungs.

Respiratory symptoms do not reflect functional impairment in early CF lung disease.

BACKGROUND: Lung disease can develop within the first year of life in infants with cystic fibrosis (CF). However, the frequency and severity of respiratory symptoms in infancy are not known. METHODS: We assessed respiratory symptoms in 50 infants with CF and 50 healthy matched controls from two prospective birth cohort studies. Respiratory symptoms and respiratory rate were documented by standardized weekly interviews throughout the first year. Infants performed multiple breath washout in the first weeks of life. RESULTS: We analyzed 4552 data points (2217 in CF). Respiratory symptoms (either mild or severe) were not more frequent in infants with CF (OR:1.1;95% CI:[0.76, 1.59]; p=0.6). Higher lung clearance index and higher respiratory rate in infants with CF were not associated with respiratory symptoms. CONCLUSIONS: We found no difference in respiratory symptoms between healthy and CF infants. These data indicate that early CF lung disease may not be captured by clinical presentation alone.

Shedding light into the black box of infant multiple-breath washout.

BACKGROUND: Multiple-breath inert gas washout (MBW) is a sensitive technique to assess lung volumes and ventilation inhomogeneity in infancy. Poor agreement amongst commercially available setups and a lack of transparency in the underlying algorithms for the computation of infant MBW outcomes currently limit the widespread application of MBW as a surveillance tool in early lung disease. METHODS: We determined all computational steps in signal processing and the calculation of MBW outcomes in the current infant WBreath/Exhalyzer D setup (Exhalyzer D device, Eco Medics AG; WBreath software version 3.28.0, ndd Medizintechnik AG; Switzerland). We developed a revised WBreath version based on current consensus guidelines and compared outcomes between the current (3.28.0) and revised (3.52.3) WBreath version. We analyzed 60 visits from 40 infants with cystic fibrosis (CF) and 20 healthy controls at 6 weeks and 1 year of age. RESULTS: Investigation into the algorithms in WBreath 3.28.0 revealed discrepancies from current consensus guidelines, which resulted in a potential overestimation of functional residual capacity (FRC) and underestimation of lung clearance index (LCI). We developed a revised WBreath version (3.52.3), which overall resulted in 6.7% lower FRC (mean (SD) -1.78 (0.99) mL/kg) and 14.1% higher LCI (1.11 (0.57) TO) than WBreath version 3.28.0. CONCLUSION: Comprehensive investigation into the signal processing and algorithms used for analysis of MBW measurements improves the transparency and robustness of infant MBW data. The revised software version calculates outcomes according to consensus guidelines. Future work is needed to validate and compare outcomes between infant MBW setups.

Longitudinal course of clinical lung clearance index in children with cystic fibrosis.

BACKGROUND: Although the lung clearance index (LCI) is a sensitive marker of small airway disease in individuals with cystic fibrosis (CF), less is known about longitudinal changes in LCI during routine clinical surveillance. Here, our objectives were to describe the longitudinal course of LCI in children with CF during routine clinical surveillance and assess influencing factors. METHODS: Children with CF aged 3-18 years performed LCI measurements every 3 months as part of routine clinical care between 2011 and 2018. We recorded clinical data at every visit. We used a multilevel mixed effect model to determine changes in LCI over time and identify clinical factors that influence LCI course. RESULTS: We collected LCI measurements from 1204 visits (3603 trials) in 78 participants, of which 907 visits had acceptable LCI data. The average unadjusted increase in LCI for the entire population was 0.29 (95% CI 0.20-0.38) LCI units·year-1. The increase in LCI was more pronounced in adolescence (0.41 (95% CI 0.27-0.54) LCI units·year-1). Colonisation with either Pseudomonas aeruginosa or Aspergillus fumigatus, pulmonary exacerbations, CF-related diabetes and bronchopulmonary aspergillosis were associated with a higher increase in LCI over time. Adjusting for clinical risk factors reduced the increase in LCI over time to 0.24 (95% CI 0.16-0.33) LCI units·year-1. CONCLUSIONS: LCI measured during routine clinical surveillance is associated with underlying disease progression in children with CF. An increased change in LCI over time should prompt further diagnostic intervention.

Multiple breath washout quality control in the clinical setting.

BACKGROUND: Multiple breath washout (MBW) is increasingly used in the clinical assessment of patients with cystic fibrosis (CF). Guidelines for MBW quality control (QC) were developed primarily for retrospective assessment and central overreading. We assessed whether real-time QC of MBW data during the measurement improves test acceptability in the clinical setting. METHODS: We implemented standardized real-time QC and reporting of MBW data at the time of the measurement in the clinical pediatric lung function laboratory in Bern, Switzerland, in children with CF aged 4-18 years. We assessed MBW test acceptability before (31 tests; 89 trials) and after (32 tests; 96 trials) implementation of real-time QC and compared agreement between reviewers. Further, we assessed the implementation of real-time QC at a secondary center in Zurich, Switzerland. RESULTS: Before the implementation of real-time QC in Bern, only 58% of clinical MBW tests were deemed acceptable following retrospective QC by an experienced reviewer. After the implementation of real-time QC, MBW test acceptability improved to 75% in Bern. In Zurich, after the implementation of real-time QC, test acceptability improved from 38% to 70%. Further, the agreement between MBW operators and an experienced reviewer for test acceptability was 84% in Bern and 93% in Zurich. CONCLUSION: Real-time QC of MBW data at the time of measurement is feasible in the clinical setting and results in improved test acceptability.

The impact of segmentation on whole-lung functional MRI quantification: Repeatability and reproducibility from multiple human observers and an artificial neural network.

PURPOSE: To investigate the repeatability and reproducibility of lung segmentation and their impact on the quantitative outcomes from functional pulmonary MRI. Additionally, to validate an artificial neural network (ANN) to accelerate whole-lung quantification. METHOD: Ten healthy children and 25 children with cystic fibrosis underwent matrix pencil decomposition MRI (MP-MRI). Impaired relative fractional ventilation (RFV ) and relative perfusion (RQ ) from MP-MRI were compared using whole-lung segmentation performed by a physician at two time-points (At1 and At2 ), by an MRI technician (B), and by an ANN (C). Repeatability and reproducibility were assess with Dice similarity coefficient (DSC), paired t-test and Intraclass-correlation coefficient (ICC). RESULTS: The repeatability within an observer (At1 vs At2 ) resulted in a DSC of 0.94 ± 0.01 (mean ± SD) and an unsystematic difference of -0.01% for RFV (P = .92) and +0.1% for RQ (P = .21). The reproducibility between human observers (At1 vs B) resulted in a DSC of 0.88 ± 0.02, and a systematic absolute difference of -0.81% (P < .001) for RFV and -0.38% (P = .037) for RQ . The reproducibility between human and the ANN (At1 vs C) resulted in a DSC of 0.89 ± 0.03 and a systematic absolute difference of -0.36% for RFV (P = .017) and -0.35% for RQ (P = .002). The ICC was >0.98 for all variables and comparisons. CONCLUSIONS: Despite high overall agreement, there were systematic differences in lung segmentation between observers. This needs to be considered for longitudinal studies and could be overcome by using an ANN, which performs as good as human observers and fully automatizes MP-MRI post-processing.

Tn-Seq reveals hidden complexity in the utilization of host-derived glutathione in Francisella tularensis.

Host-derived glutathione (GSH) is an essential source of cysteine for the intracellular pathogen Francisella tularensis. In a comprehensive transposon insertion sequencing screen, we identified several F. tularensis genes that play central and previously unappreciated roles in the utilization of GSH during the growth of the bacterium in macrophages. We show that one of these, a gene we named dptA, encodes a proton-dependent oligopeptide transporter that enables growth of the organism on the dipeptide Cys-Gly, a key breakdown product of GSH generated by the enzyme γ-glutamyltranspeptidase (GGT). Although GGT was thought to be the principal enzyme involved in GSH breakdown in F. tularensis, our screen identified a second enzyme, referred to as ChaC, that is also involved in the utilization of exogenous GSH. However, unlike GGT and DptA, we show that the importance of ChaC in supporting intramacrophage growth extends beyond cysteine acquisition. Taken together, our findings provide a compendium of F. tularensis genes required for intracellular growth and identify new players in the metabolism of GSH that could be attractive targets for therapeutic intervention.

Effect of breastfeeding duration on lung function, respiratory symptoms and allergic diseases in school-age children.

BACKGROUND: A positive effect of breastfeeding on lung function has been demonstrated in cohorts of children with asthma or risk for asthma. We assessed the impact of breastfeeding on lung function and symptoms at the age of 6 years in an unselected, healthy birth cohort. METHODS: We prospectively studied healthy term infants from the Bern-Basel Infant Lung Development (BILD) cohort from birth up to 6 years. Any breastfeeding was assessed by weekly phone calls during the first year of life. Risk factors (eg, smoking exposure, parental history of allergic conditions, and education) were obtained using standardized questionnaires. The primary outcomes were lung function parameters measured at 6 years of age by spirometry forced expiratory volume in 1 second, body plethysmography (functional residual capacity [FRCpleth ], the total lung capacity [TLCpleth ], and the effective respiratory airway resistance [Reff ]) and fractional exhaled nitric oxide (FeNO). Secondary outcomes included ever wheeze (between birth and 6 years), wheeze in the past 12 months, asthma, presence of allergic conditions, atopic dermatitis, rhinitis, and positive skin prick test at the age of 6 years. RESULTS: In 377 children the mean breastfeeding duration was 36 weeks (SD 14.4). We found no association of breastfeeding duration with obstructive or restrictive lung function and FeNO. After adjustment for confounders, we found no associations of breastfeeding duration with respiratory symptoms or the presence of allergic conditions. CONCLUSION: This study found no evidence of an association between breastfeeding and comprehensive lung function in unselected healthy children with long-term breastfeeding. Our findings do not support the hypothesis that the duration of breastfeeding has a direct impact on lung function in a healthy population with low asthmatic risk.

Airway Mucus Hyperconcentration in Non-Cystic Fibrosis Bronchiectasis.

Rationale: Non-cystic fibrosis bronchiectasis is characterized by airway mucus accumulation and sputum production, but the role of mucus concentration in the pathogenesis of these abnormalities has not been characterized.Objectives: This study was designed to: 1) measure mucus concentration and biophysical properties of bronchiectasis mucus; 2) identify the secreted mucins contained in bronchiectasis mucus; 3) relate mucus properties to airway epithelial mucin RNA/protein expression; and 4) explore relationships between mucus hyperconcentration and disease severity.Methods: Sputum samples were collected from subjects with bronchiectasis, with and without chronic erythromycin administration, and healthy control subjects. Sputum percent solid concentrations, total and individual mucin concentrations, osmotic pressures, rheological properties, and inflammatory mediators were measured. Intracellular mucins were measured in endobronchial biopsies by immunohistochemistry and gene expression. MUC5B (mucin 5B) polymorphisms were identified by quantitative PCR. In a replication bronchiectasis cohort, spontaneously expectorated and hypertonic saline-induced sputa were collected, and mucus/mucin concentrations were measured.Measurements and Main Results: Bronchiectasis sputum exhibited increased percent solids, total and individual (MUC5B and MUC5AC) mucin concentrations, osmotic pressure, and elastic and viscous moduli compared with healthy sputum. Within subjects with bronchiectasis, sputum percent solids correlated inversely with FEV1 and positively with bronchiectasis extent, as measured by high-resolution computed tomography, and inflammatory mediators. No difference was detected in MUC5B rs35705950 SNP allele frequency between bronchiectasis and healthy individuals. Hypertonic saline inhalation acutely reduced non-cystic fibrosis bronchiectasis mucus concentration by 5%.Conclusions: Hyperconcentrated airway mucus is characteristic of subjects with bronchiectasis, likely contributes to disease pathophysiology, and may be a target for pharmacotherapy.

Endotracheal tube mucus as a source of airway mucus for rheological study.

Muco-obstructive lung diseases (MOLDs), like cystic fibrosis and chronic obstructive pulmonary disease, affect a spectrum of subjects globally. In MOLDs, the airway mucus becomes hyperconcentrated, increasing osmotic and viscoelastic moduli and impairing mucus clearance. MOLD research requires relevant sources of healthy airway mucus for experimental manipulation and analysis. Mucus collected from endotracheal tubes (ETT) may represent such a source with benefits, e.g., in vivo production, over canonical sample types such as sputum or human bronchial epithelial (HBE) mucus. Ionic and biochemical compositions of ETT mucus from healthy human subjects were characterized and a stock of pooled ETT samples generated. Pooled ETT mucus exhibited concentration-dependent rheologic properties that agreed across spatial scales with reported individual ETT samples and HBE mucus. We suggest that the practical benefits compared with other sample types make ETT mucus potentially useful for MOLD research.