Risk factors for lung disease progression in children with cystic fibrosis.

To identify potential risk factors for lung disease progression in children with cystic fibrosis (CF), we studied the longitudinal data of all children with CF (aged ≥5 years) registered in the Dutch CF Registry (2009-2014).Lung disease progression was expressed as a decline in lung function (forced expiratory volume in 1 s (FEV1) % pred) and pulmonary exacerbation rate. Potential risk factors at baseline included sex, age, best FEV1 % pred, best forced vital capacity % pred, genotype, body mass index z-score, pancreatic insufficiency, medication use (proton pump inhibitors (PPIs), prophylactic antibiotics and inhaled corticosteroids), CF-related diabetes, allergic bronchopulmonary aspergillosis and colonisation with Pseudomonas aeruginosaThe data of 545 children were analysed. PPI use was associated with both annual decline of FEV1 % pred (p=0.017) and future pulmonary exacerbation rate (p=0.006). Moreover, lower FEV1 % pred at baseline (p=0.007), prophylactic inhaled antibiotic use (p=0.006) and pulmonary exacerbations in the baseline year (p=0.002) were related to pulmonary exacerbations in subsequent years.In a cohort of Dutch children with CF followed for 5 years, we were able to identify several risk factors for future exacerbations. In particular, the association between PPI use and lung disease progression definitely requires further investigation.

Biomarkers in Exhaled Breath Condensate Are Not Predictive for Pulmonary Exacerbations in Children with Cystic Fibrosis: Results of a One-Year Observational Study.

BACKGROUND: Cystic Fibrosis (CF) is characterized by chronically inflamed airways, and inflammation even increases during pulmonary exacerbations. These adverse events have an important influence on the well-being, quality of life, and lung function of patients with CF. Prediction of exacerbations by inflammatory markers in exhaled breath condensate (EBC) combined with early treatment may prevent these pulmonary exacerbations and may improve the prognosis. AIM: To investigate the diagnostic accuracy of a set of inflammatory markers in EBC to predict pulmonary exacerbations in children with CF. METHODS: In this one-year prospective observational study, 49 children with CF were included. During study visits with an interval of 2 months, a symptom questionnaire was completed, EBC was collected, and lung function measurements were performed. The acidity of EBC was measured directly after collection. Inflammatory markers interleukin (IL)-6, IL-8, tumor necrosis factor α (TNF-α), and macrophage migration inhibitory factor (MIF) were measured using high sensitivity bead based flow immunoassays. Pulmonary exacerbations were recorded during the study and were defined in two ways. The predictive power of inflammatory markers and the other covariates was assessed using conditionally specified models and a receiver operating characteristic curve (SAS version 9.2). In addition, k-nearest neighbors (KNN) algorithm was applied (SAS version 9.2). RESULTS: Sixty-five percent of the children had one or more exacerbations during the study. The conditionally specified models showed an overall correct prediction rate of 55%. The area under the curve (AUC) was equal to 0.62. The results obtained with the KNN algorithm were very similar. CONCLUSION: Although there is some evidence indicating that the predictors outperform random guessing, the general diagnostic accuracy of EBC acidity and the EBC inflammatory markers IL-6, IL-8, TNF-α and MIF is low. At present it is not possible to predict pulmonary exacerbations in children with CF with the chosen biomarkers and the method of EBC analysis. The biochemical measurements of EBC markers should be improved and other techniques should be considered.

Structural lung changes, lung function, and non-invasive inflammatory markers in cystic fibrosis.

Cystic fibrosis (CF) lung disease is characterized by chronic airway inflammation and recurrent infections, resulting in (ir)reversible structural lung changes and a progressive decline in lung function. The objective of this study was to investigate the relationship between non-invasive inflammatory markers (IM) in exhaled breath condensate (EBC), lung function indices and structural lung changes, visualized by high resolution computed tomography (HRCT) scans in CF. In 34 CF patients, lung function indices (forced expiratory volume in 1 s, forced vital capacity [FVC], residual volume, and total lung capacity [TLC]) and non-invasive IM (exhaled nitric oxide, and condensate acidity, nitrate, nitrite, 8-isoprostane, hydrogen peroxide, interferon-gamma) were assessed. HRCT scans were scored in a standardized and validated way, a composite score and component scores were calculated. In general, the correlations between non-invasive IM and structural lung changes, and between IM and lung function were low (correlation coefficients <0.40). Patients with positive sputum Pseudomonas cultures had higher EBC nitrite levels and higher parenchymal HRCT subscores than patients with Pseudomonas-negative cultures (p < 0.05). Multiple linear regression models demonstrated that FVC was significantly predicted by hydrogen peroxide in EBC, and the scores of bronchiectasis and mosaic perfusion (Pearson correlation coefficient R = 0.78, p < 0.001). TLC was significantly predicted by 8-isoprostane, nitrate, hydrogen peroxide in EBC, and the mucous plugging subscore (R = 0.92, p < 0.01). Static and dynamic lung function indices in this CF group were predicted by the combination of non-invasive IM in EBC and structural lung changes on HRCT imaging. Future longitudinal studies should reveal whether non-invasive monitoring of airway inflammation in CF adds to better follow-up of patients.

Metabolomics of volatile organic compounds in cystic fibrosis patients and controls.

In cystic fibrosis (CF), airway inflammation causes an increased production of reactive oxygen species, responsible for degradation of cell membranes. During this process, volatile organic compounds (VOCs) are formed. Measurement of VOCs in exhaled breath of CF patients may be useful for the assessment of airway inflammation. This study investigates whether "metabolomics' of VOCs could discriminate between CF and controls, and between CF patients with and without Pseudomonas colonization. One hundred five children (48 with CF, 57 controls) were included in this study. After exhaled breath collection, samples were transferred onto tubes containing active carbon to adsorb and stabilize VOCs. Samples were analyzed by gas chromatography-time of flight-mass spectrometry to assess VOC profiles. Analysis showed that 1099 VOCs had a prevalence of at least 7%. By using 22 VOCs, a 100% correct identification of CF patients and controls was possible. With 10 VOCs, 92% of the subjects were correctly classified. The reproducibility of VOC measurements with a 1-h interval was very good (match factor 0.90 +/- 0.038). We conclude that metabolomics of VOCs in exhaled breath was possible in a reproducible way. This new technique was able to discriminate not only between CF patients and controls but also between CF patients with or without Pseudomonas colonization.

Free radicals in exhaled breath condensate in cystic fibrosis and healthy subjects.

Many markers of airway inflammation and oxidative stress can be measured non-invasively in exhaled breath condensate (EBC). However, no attempt has been made to directly detect free radicals using electron paramagnetic resonance (EPR) spectroscopy. Condensate was collected in 14 children with cystic fibrosis (CF) and seven healthy subjects. Free radicals were trapped by 5,5-dimethyl-1-pyrroline-N-oxide. EPR spectra were recorded using a Bruker EMX spectrometer. Secondly, to study the source of oxygen centered radical formation, catalase or hydrogen peroxide was added to the condensate. Radicals were detected in 18 out of 21 condensate samples. Analysis of spectra indicated that both oxygen and carbon centered radicals were trapped. Within-subject reproducibility was good in all but one subject. Quantitatively, there was a trend towards higher maximal peak heights of both oxygen and carbon centered radicals in the children with CF. Catalase completely suppressed the signals in condensate. Addition of hydrogen peroxide resulted in increased radical signal intensity. Detection of free radicals in EBC of children with CF and healthy subjects is feasible using EPR spectroscopy.

Cytokines in exhaled breath condensate of children with asthma and cystic fibrosis.

BACKGROUND: Inflammatory mediators in exhaled breath condensate (EBC) indicate ongoing inflammation in the lungs and might differentiate between asthma and cystic fibrosis (CF). OBJECTIVES: To evaluate the presence, concentration, and short-term variability of TH1- and TH2-mediated cytokines (interferon-gamma [IFN-gamma], tumor necrosis factor alpha [TNF-alpha], interleukin 10 [IL-10], IL-5, IL-4, and IL-2) in EBC of children with asthma or CF and in controls and to analyze the discriminating ability of inflammatory markers in EBC between children with asthma or CF and controls. METHODS: Expired air was conducted through a double-jacketed glass tube cooled by circulating ice water. In 33 asthmatic children, 12 children with CF, and 35 control children, EBC was collected during tidal breathing. Cytokines were measured using flow cytometry. RESULTS: Interleukin 2, IL-4, IFN-gamma, and IL-10 were detected in 16%, 16%, 11%, and 9%, respectively, of all samples in asthma and CF. Interleukin 5 and TNF-alpha were not detected in children with CF. Cytokine concentrations did not differ significantly in children with asthma vs CF. In controls, IFN-gamma, TNF-alpha, and IL-10 were detected in 9%, 14%, and 3%, respectively; IL-2, IL-4, and IL-5 were not detected in controls. CONCLUSIONS: Cytokines such as IFN-gamma, TNF-alpha, IL-10, IL-5, IL-4, and IL-2 can be detected in EBC of children with asthma or CF. However, the concentrations found are close to the detection limits of the assay used. These findings emphasize the importance of developing more sensitive techniques for the analysis of EBC and of standardizing the EBC collection method.

Childhood asthma: exhaled markers of airway inflammation, asthma control score, and lung function tests.

Exhaled markers of airway inflammation become increasingly important in the management of childhood asthma. The aims of the present study are: 1) to compare exhaled markers of inflammation (nitric oxide, carbon monoxide, and acidity of breath condensate) with conventional asthma measures (lung function tests and asthma control score) in childhood asthma; and 2) to investigate the detectability of albumin, CRP, IL-6, IL-8, TNF-alpha, sICAM-1, and sTNF-R75 in the exhaled breath condensate (EBC) of asthmatic children. Thirty-two children with mild to moderate persistent asthma and healthy controls aged 6-12 years were studied. We measured exhaled NO and CO, and subsequently EBC was collected. Inflammatory mediators in EBC were measured using an enzyme-linked immunosorbent assay. Respiratory symptoms and asthma control were assessed using the asthma control questionnaire (ACQ) of Juniper et al. (Eur Respir J 1999;14:902-907). Exhaled NO showed a significant correlation with exhaled CO (r = 0.59, P < 0.05) and FEV1 (r = -0.59, P < 0.05), but not with ACQ score (r = 0.48, P = 0.06). Exhaled CO was correlated with prebronchodilator FEV1 (r = -0.45, P < 0.05), but not with asthma control (r = 0.18, P = 0.35). Acidity of EBC was significantly lower in asthmatic children than in healthy controls (P < 0.05), but did not correlate with any of the conventional asthma measures. We were not able to demonstrate the presence of CRP, IL-6, IL-8, TNF-alpha, sICAM-1, and sTNF-R75 in EBC. Albumin was found in two EBC samples of asthmatic children. We conclude that exhaled NO had a better correlation with lung function parameters and asthma control than exhaled CO and acidity of EBC, in mild to moderate persistent childhood asthma. However, exhaled NO, CO, and deaerated pH of EBC did not differ between asthmatic children and controls, possibly because of a too homogeneous and well-controlled study population. To further evaluate the clinical utility of exhaled markers in monitoring childhood asthma, more studies are required on a wider range of asthma severity, and preferably with repeated measurements of markers and of asthma control.

Exhaled breath condensate in children: pearls and pitfalls.

Exhaled breath condensate (EBC) is a rapidly growing field of research in respiratory medicine. Airway inflammation is a central feature of chronic lung diseases, like asthma, cystic fibrosis, bronchopulmonary dysplasia and primary ciliary dyskinesia. EBC may be a useful technique for non-invasive assessment of markers of airway inflammation. The non-invasive character of EBC "inflammometry" and the general lack of appropriate techniques makes it particularly interesting for paediatrics. We provide a detailed update on the methods currently used for EBC collection and measurement of mediators. We emphasize on paediatric data. The apparent simplicity of the EBC method must not be overstated, as numerous methodological pitfalls have yet to overcome. Comparison and interpretation of data on this rapidly growing field of research is mainly hampered by the lack of standardization and the lack of specific high-sensitivity immunochemical or colorimetric assays. The initiative of the European Respiratory Society to institute a task force on this topic is a first step towards a uniform technique of EBC. Meanwhile, when using this technique or when interpreting research data, one should be fully aware of the possible methodological pitfalls.