Exhaled breath condensate in children: pearls and pitfalls

Feasibility of a new method to collect exhaled breath condensate in pre-school children

Exhaled breath condensate (EBC) is a promising non-invasive method to assess respiratory inflammation in adults and children with lung disease. Especially in pre-school children, condensate collection is hampered by long sampling times because of open-ended collection systems. We aimed to assess the feasibility of condensate collection in pre-school children using a closed glass condenser with breath recirculation system, which also collects the residual non-condensed exhaled breath, and subsequently recirculates it back into the condenser. Condensate was collected before and after breath recirculation in 70 non-sedated pre-school children with and without recurrent wheeze. Cytokines (IL-4, IL-5, IL-6, IL-8, IL-10, IL-12p70, IL-13, TNF-α) were measured in 50 μl samples using ultrasensitive multiplexed liquid bead array. The success rate of condensate collection increased from 64% (without recirculation) to 83% (after breath recirculation), and mean condensate volume from 214 to 465 μl respectively. Detection of cytokines was successful in 95-100% of samples. Cytokine concentrations before and after breath recirculation were not different (p > 0.232). In asthmatic children, only TNF-α concentrations were significantly decreased, compared to non-asthmatics. In pre-school children, the collection of EBC is feasible using a new closed glass condenser with breath recirculation system. This new method may help to assess - non-invasively - cytokine profiles in asthmatic and non-asthmatic pre-school children.

Volatile organic compounds in exhaled breath as a diagnostic tool for asthma in children

BACKGROUND

The correct diagnosis of asthma in young children is often hard to achieve, resulting in undertreatment of asthmatic children and overtreatment in transient wheezers.

OBJECTIVES

To develop a new diagnostic tool that better discriminates between asthma and transient wheezing and that leads to a more accurate diagnosis and hence less undertreatment and overtreatment. A first stage in the development of such a tool is the ability to discriminate between asthmatic children and healthy controls. The integrative analysis of large numbers of volatile organic compounds (VOC) in exhaled breath has the potential to discriminate between various inflammatory conditions of the respiratory tract.

METHODS

Breath samples were obtained and analysed for VOC by gas chromatography-mass spectrometry from asthmatic children (n=63) and healthy controls (n=57). A total of 945 determined compounds were subjected to discriminant analysis to find those that could discriminate diseased from healthy children. A set of samples from both asthmatic and healthy children was selected to construct a model that was subsequently used to predict the asthma or the healthy status of a test group. In this way, the predictive value of the model could be tested.

MEASUREMENTS AND MAIN RESULTS

The discriminant analyses demonstrated that asthma and healthy groups are distinct from one another. A total of eight components discriminated between asthmatic and healthy children with a 92% correct classification, achieving a sensitivity of 89% and a specificity of 95%. Conclusion The results show that a limited number of VOC in exhaled air can well be used to distinguish children with asthma from healthy children.

Monitoring respiratory disease severity in cystic fibrosis

Measurements of disease severity provide a guide for the physician to tailor therapies, for the patient and family to gauge progress, and are required for clinical trials. For many respiratory diseases, including cystic fibrosis, sensitive, noninvasive measurements are few, and some of those that are available are applicable only to certain subgroups of patients or lack sufficient sensitivity. We discuss currently available measurements in 4 groups: physiology, infection, inflammation, and radiology. For each group we highlight strengths and weaknesses, ask how we could improve upon these, and provide details of alternative methods.

Airway monitoring by collection and mass spectrometric analysis of exhaled particles

We describe a new method for simultaneously collecting particles in exhaled air for subsequent chemical analysis and measuring their size distribution. After forced exhalation, particles were counted and collected in spots on silicon wafers with a cascade impactor. Several phospholipids were identified by time-of-flight secondary ion mass spectrometric analysis of the collected spots, suggesting that the particles originated from the lower airways. The amount of particles collected in ten exhalations was sufficient for characterizing the phospholipid composition. The feasibility of the technique in respiratory research is demonstrated by analysis of the phospholipid composition of exhaled particles from healthy controls, patients with asthma, and patients with cystic fibrosis. We believe this technology will be useful for monitoring patients with respiratory disease and has a high potential to detect new biomarkers in exhaled air.

Investigation of attention deficit and hyperactivity disorder in adult patients with atopic dermatitis

Background. Atopic dermatitis (AD) is a common chronic inflammatory disease that is associated with significant psychosocial morbidity and a decrease in health-related quality of life. Attention deficit hyperactivity disorder may be present in atopic dermatitis patients. Objective. The present study aims to investigate the co-presence of ADHD in adult patients with AD. Material and method. The study registered 60 adult patients with AD (48 females and 12 males) and 50 non-atopic control subjects (38 females and 12 males). The AD patient group and the control group were assessed using the Turgay adult Attention-Deficit/Hyperactivity Disorder (ADD/ADHD) DSM-IV-Based Diagnostic Screening and Rating Scale (Turkish Version), which was studied by a team of psychologists and psychiatrists in Turkey for validity, reliability and norms. The scale covers three dimensions of the disease, namely inattention, hyperactivity and impulsivity, and associated features of ADHD. The groups were compared and contrasted in terms of their similarities and differences in ADD/ADHD symptoms. Results. Three sub-dimensions of ADD/ADHD scale (Attention Deficit, Hyperactivity/ Impulsivity and Problem subdivisions) in AD patients were found statistically significantly elevated relative to controls (P<0.001, P<0.001, P<0.001, respectively). Conclusions. In conclusion we established the co-presence of ADHD in AD patients in the adult age group.

Oxidative stress and its determinants in the airways of children with asthma

BACKGROUND

There is ample evidence for the existence of a systemic oxidative stress in childhood asthma but relatively little information on the oxidant stress in the airways.

OBJECTIVE

To determine the extent of oxidant/antioxidant imbalance and describe its determinants in the airways of asthmatic children including asthma severity and the genotype of the antioxidant enzymes.

METHODS

One hundred and ten children with mild asthma, 30 children with moderate asthma and 191 healthy controls were included in the study. Exhaled breath condensate (EBC) was collected from all children with EcoScreen. Levels of malondialdehyde were measured as the indicator of oxidative stress, and of reduced glutathione as the indicator of antioxidant defense. Children were genotyped for the presence of null variants of glutathione S transferase (GST) T1 and GSTM1, and ile105val variant of GSTP1. Risk factors were analyzed with multivariate logistic regression.

RESULTS

EBC contained significantly higher levels of malondialdehyde and lower levels of reduced glutathione in asthmatic children compared with healthy controls (P < 0.001 for each), whereas there was no difference between mild and moderate asthmatics. Multivariate logistic regression identified asthma as the only independent factor contributing to oxidative stress. Genotypes of the antioxidant enzymes had no effect on the oxidative burden.

CONCLUSIONS

Asthma is associated with an extremely powerful oxidative stress not only in the systemic circulation but also in the airways.

Assessment of individual lung cancer risk by the proteomic analysis of exhaled breath condensate

BACKGROUND

Lung cancer is one of the leading causes of cancer-related deaths. Several diagnostic strategies are available but these are frequently ineffective, either because of their cost and organizational difficulty or because of the involvement of high radiations. As recent data from spiral computerized axial tomography have shown limited sensitivity and limited impact on cancer-related fatality, several options have been proposed in order to identify biological fluid-based biomarkers.

OBJECTIVE

Evaluating whether proteomic analysis of alveolar fluid obtained in the form of exhaled breath condensate (EBC) can be valuable for detecting and effectively diagnosing lung cancer.

METHODS

Careful review of recently published papers on proteomic EBC analysis, together with experience in the authors' laboratory, allows the discussion of benefits, pitfalls and possible future development of this approach.

RESULTS/CONCLUSIONS

The rapid advancements of proteomics are expected to validate EBC protein(s) as lung pathology biomarker(s). Accessibility of an early marker of lung cancer will be a great advantage for potentially early treatment by surgical procedures with limited tissue removal, possibly preceding metastasis development.

Biomarkers in exhaled breath condensate indicate presence and severity of cystic fibrosis in children

Chronic airway inflammation is present in cystic fibrosis (CF). Non-invasive inflammometry may be useful in disease management. The aim of the present cross-sectional study was to investigate: (i) the ability of fractional exhaled nitric oxide and inflammatory markers (IM) [exhaled breath condensate (EBC) acidity, nitrite, nitrate, hydrogen peroxide (H(2)O(2)), 8-isoprostane, Th1/Th2 cytokines] to indicate (exacerbations of) CF; and (ii) the ability of these non-invasive IM to indicate CF disease severity. In 98 children (48 CF/50 controls), exhaled nitric oxide was measured using the NIOX, and condensate was collected using a glass condenser. In CF interferon (IFN-gamma) and nitrite concentrations were significantly higher, whereas exhaled nitric oxide levels were significantly lower compared with controls (3.3 +/- 0.3 pg/ml, 2.2 +/- 0.2 microM, 10.0 +/- 1.2 p.p.b. vs. 2.6 +/- 0.2 pg/ml, 1.4 +/- 0.1 microM, 15.4 +/- 1.4 p.p.b. respectively). Using multivariate logistic regression models, the presence of CF was best indicated by 8-isoprostane, nitrite and IFN-gamma [sensitivity 78%, specificity 83%; area under receiver operating characteristic curve (AUC) 0.906, p < 0.001]. An exacerbation of CF was best indicated by 8-isoprostane and nitrite (sensitivity 40%, specificity 97%, AUC curve 0.838, p = 0.009). Most indicative biomarkers of CF severity were exhaled nitric oxide, and condensate acidity (sensitivity 96%, specificity 67%; AUC curve 0.751, p = 0.008). In this cross-sectional study, the combination of different exhaled IM could indicate (exacerbations of) CF, and severity of the disease in children. Longitudinal data are necessary to further confirm the role of these markers for the management of CF in children.

Comparison of the anti-inflammatory effects of extra-fine hydrofluoroalkane-beclomethasone vs fluticasone dry powder inhaler on exhaled inflammatory markers in childhood asthma

BACKGROUND

Extra-fine hydrofluoroalkane-beclomethasone differs from other inhaled corticosteroids by its fine aerosol characteristics. Therefore, extra-fine hydrofluoroalkane-beclomethasone may be particularly useful for treating peripheral airway inflammation in asthma.

OBJECTIVE

To analyze the anti-inflammatory effects of extra-fine hydrofluoroalkane-beclomethasone vs fluticasone dry powder inhaler (DPI) in asthmatic children by measuring bronchial and alveolar nitric oxide (NO) and inflammatory markers in exhaled breath condensate (EBC).

METHODS

In a 6-month crossover study, 33 children aged 6 to 12 years with moderate persistent asthma were randomly treated with extra-fine hydrofluoroalkane-beclomethasone (200 microg daily via an Autohaler) and fluticasone DPI (200 microg daily via a Diskus). The primary outcome variables were alveolar NO concentration and bronchial NO flux. The secondary outcome variables were levels of inflammatory markers in EBC, lung function indices, symptoms, exacerbations, and adverse effects. All the variables were recorded at baseline and after each treatment period.

RESULTS

Mean +/- SE alveolar NO concentration and bronchial NO flux were comparable after treatment with hydrofluoroalkane-beclomethasone vs fluticasone DPI (4.7 +/- 0.5 vs 4.3 +/- 0.5 ppb, P = .55, and 1,124.3 +/- 253.6 vs 1,029.1 +/- 195.5 pL/s, P = .70, respectively). In addition, levels of inflammatory markers in EBC, lung function indices, and symptoms did not differ between treatments. Patients used fewer beta2-agonists during the last 2 weeks of hydrofluoroalkane-beclomethasone treatment.

CONCLUSION

The anti-inflammatory effects of hydrofluoroalkane-beclomethasone are similar to those of fluticasone DPI in children with moderate persistent asthma.

New visions in respiratory allergy (asthma and allergic rhinitis): an iPAC summary and future trends

In many aspects, respiratory allergies, i.e., allergic asthma and rhinitis, represent the hallmarks of allergy. Epidemiologic data highlight their large prevalence of most parts of the world, socioeconomic analysis reveal their large impact on global health and the large number of scientific publications in this field regularly brings to light many new aspects of these diseases. However, the current understanding of respiratory allergies, in particular in children remains scarce. How can we efficiently prevent respiratory allergies in allergy-prone infants? How can we prevent the progression of the disease? What therapeutic strategies could efficiently address efficient immunomodulation? the international Pediatric Allergy and Asthma Consortium, addressed these issues by a thorough review of the literature providing a state-of-the-art current knowledge in respiratory allergy, and identified a series of needs to be addressed in future studies.

Adherence to allergy prevention recommendations in children with a family history of asthma

Allergen avoidance has been a major component of most programs for primary prevention of asthma and allergic diseases in childhood. As a part of the Childhood Asthma Prevention Study, families were provided with written and oral information on measures considered to be helpful in the primary prevention of allergic disease in high-risk infants. Dietary measures included advice to breastfeed for 6 months or longer, to delay the introduction of solid foods until after the infant turned 6 months of age, and to delay giving allergenic foods (egg and peanut butter) until after 12 months of age. In the active group of the randomized controlled trial aimed at reducing house dust mite (HDM) allergen levels, parents were advised to use an HDM-impermeable study mattress cover and an acaricide, to avoid sheep skins, and not to use a pillow before 12 months of age. Families received regular visits from the research nurses at 1, 3, 6, 9 and 12 months and phone calls every 6 wk. Only 43.4% of mothers were breastfeeding by 6 months and less than 20% by 12 months. The introduction of solid foods before 6 months was common, 26% by 3 months and 96% by 6 months. Adherence to infant-feeding recommendations was significantly greater in women over 30 yr of age, women who did not smoke during pregnancy, and women who had a tertiary education. Adherence to HDM reduction measures was greater than to those for infant feeding. The presence of symptoms in the form of an itchy rash by 4 wk did not significantly increase adherence. Complete adherence to infant-feeding recommendations in this intervention study of high-risk infants was low despite the provision of written information and reinforcement at home visits. In considering allergy prevention advice offered during clinical care, the likelihood of adherence is a factor which needs to be evaluated in assessing any potential benefits of allergy prevention regimens.

Exhaled breath malondialdehyde as a marker of effect of exposure to air pollution in children with asthma

BACKGROUND

Assessment of the adverse effects of oxidative stress related to air pollution is limited by the lack of biological markers of dose to the lungs.

OBJECTIVE

We evaluated the use of exhaled breath condensate (EBC) malondialdehyde as a biomarker of exposure to traffic-related pollution in children with asthma as part of a panel study in Mexico City.

METHODS

Standard spirometry and collection of EBC and nasal lavage were performed. Environmental monitoring sites were located within 5 km of the children's homes and schools. Data were analyzed by using generalized estimating equations.

RESULTS

A total of 480 samples of malondialdehyde were obtained from 107 patients with asthma, with a median level of 18.7 (interquartile range [IQR], 12.4-28.7) nmol. Ambient particulates less than 2.5 microg/m(3) and ozone levels on the day of sampling were significantly associated with higher malondialdehyde levels. A 14.2-microg/m(3) (IQR) increase in 8-hour moving average particulates less than 2.5 microg/m(3) in size was associated with a 1.12-nmol increase in malondialdehyde and a 15.9-ppb (IQR) increase in 8-hour moving average ozone with a 1.16-nmol increase in malondialdehyde. Malondialdehyde levels were inversely associated with forced vital capacity and FEV(1) and positively associated with IL-8 levels in nasal lavage.

CONCLUSION

Exhaled breath condensate malondialdehyde was related to both air pollution exposure and changes in lung function and inflammatory markers.

Proteomics as a method for early detection of cancer: a review of proteomics, exhaled breath condensate, and lung cancer screening

The study of expressed proteins in neoplasia is undergoing a revolution with the advent of proteomic analysis. Unlike genomic studies where individual changes may have no functional significance, protein expression is closely aligned with cellular activity. This perspective will review proteomics as a method of detecting markers of neoplasia with a particular emphasis on lung cancer and the potential to sample the lung by exhaled breath condensate (EBC). EBC collection is a simple, new, and noninvasive technique, which allows sampling of lower respiratory tract fluid. EBC enables the study of a wide variety of biological markers from low molecular weight mediators to macromolecules, such as proteins, in a range of pulmonary diseases. EBC may be applied to the detection of lung cancer where it could be a tool in early diagnosis. This perspective will explore the potential of applying proteomics to the EBC from lung cancer patients as an example of detecting potential biomarkers of disease and progression.

Longitudinal monitoring of pediatric cystic fibrosis lung disease using nitrite in exhaled breath condensate

Cystic fibrosis (CF) lung disease is characterized by airway inflammation and airway infection. Nitrites in exhaled breath condensate (EBC-NO(2)(-)) have been shown to be increased in children and adults with CF compared to healthy controls suggesting its use as a measure of airway inflammation. This longitudinal study aimed to evaluate if repeated measurements of EBC-NO(2)(-) are helpful in monitoring CF lung disease activity in children. Thirty-two children with mild CF lung disease (age 10.6 +/- 3.3 years) were recruited in two study centers. Follow-up visits occurred every 3 months over a period of 1 year with a total of five visits. Each visit included a clinical assessment incorporating a modified Shwachman-Kulczycki (SK) score, spirometry, an oropharyngeal swab, or sputum sample for bacterial analysis and an EBC sample analyzed for NO(2)(-) using a spectrophotometric assay. Furthermore at the first and the last visit a chest radiograph was done and scored (Chrispin-Norman (CN) score). There was no correlation of EBC-NO(2)(-) and parameters of spirometry, SK-score, or CN-score. Furthermore, increased EBC-NO(2)(-) levels did not predict subsequent pulmonary exacerbations. We conclude that repeated measurements of EBC-NO(2)(-) are not helpful in the longitudinal monitoring of mild CF lung disease in children.

Exhaled nitric oxide and biomarkers in exhaled breath condensate indicate the presence, severity and control of childhood asthma

BACKGROUND

Exhaled nitric oxide and inflammatory biomarkers in exhaled breath condensate may be useful to diagnose and monitor childhood asthma. Their ability to indicate an asthma diagnosis, and to assess asthma severity and control, is largely unknown.

OBJECTIVE

To study (1) the ability of exhaled nitric oxide and inflammatory markers in exhaled breath condensate (nitrite, nitrate, hydrogen peroxide, 8-isoprostane, IFN-gamma, TNF-alpha, IL-2, -4, -5, -10 and acidity) to discriminate between childhood asthma and controls. (2) The ability of these biomarkers to indicate asthma severity and control.

METHODS

One-hundred and fourteen children were included: 64 asthmatics (10.7+/-3.0 years, 67.2% atopic) and 50 controls (10.0+/-0.4 years). Condensate was collected using a glass condenser.

RESULTS

Exhaled nitric oxide, IFN-gamma and IL-4 in exhaled breath condensate differed significantly between asthma and controls. Multivariate backward logistic regression models demonstrated that IL-4 (odds ratio 7.9, 95% confidence interval 1.2-51.0) was the only significant indicator of an asthma diagnosis. Asthma control was best assessed by exhaled nitric oxide, 8-isoprostane, IFN-gamma and IL-4 (sensitivity 82%, specificity 80%, P<0.05), whereas exhaled nitric oxide, 8-isoprostane, nitrate and nitrite in condensate were the best indicators of asthma severity (sensitivity 89%, specificity 72%, P<0.05).

CONCLUSION

Different markers in condensate are of an additional value to exhaled nitric oxide, and are needed in non-invasive inflammometry. They could be useful to diagnose asthma and to indicate asthma control and severity in childhood.

Asthma control or severity: that is the question

In the first National Heart Lung and Blood Institute and Global Initiative for Asthma (GINA) guidelines, the level of symptoms and airflow limitation and its variability allowed asthma to be subdivided by severity into four subcategories (intermittent, mild persistent, moderate persistent, and severe persistent). It is important to recognize, however, that asthma severity involves both the severity of the underlying disease and its responsiveness to treatment. Thus, the first update of the GINA guidelines defined asthma severity depending on the clinical features already proposed as well as the current treatment of the patient. In addition, severity is not a fixed feature of asthma, but may change over months or years, whereas the classification by severity suggests a static feature. Moreover, using severity as an outcome measure has limited value in predicting what treatment will be required and what the response to that treatment might be. Because of these considerations, the classification of asthma severity is no longer recommended as the basis for treatment decisions, a periodic assessment of asthma control being more relevant and useful.

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.

Exhaled breath condensate pH measurement in children with asthma, allergic rhinitis and atopic dermatitis

Recent studies have shown that the pH of exhaled breath condensate (EBC) could be predictive of asthma exacerbation. Moreover, it has been documented that both allergic rhinitis and atopic dermatitis constitute risk factors for the occurrence of asthma in a progression of disease known as atopic march. The aim of our study was to establish if condensate pH could be used as a valuable mean of monitoring of asthma in atopic children. We studied 34 atopic children with acute asthma, 70 with stable asthma, 35 children with allergic rhinitis, and 17 with atopic dermatitis. Thirty healthy children were used as controls. All children underwent skin prick tests and lung function tests. Exhaled breath condensate samples were collected with a condensing device and de-aerated with argon. The pH of EBC was measured using a pH meter. Children with acute asthma were treated with inhaled steroids and bronchodilators. We found that the pH of condensate in patients with acute asthma was lower than that of patients with stable asthma, rhinitis, and controls (7.25 vs. 7.32, p < 0.05; 7.25 vs. 7.48, p < 0.02; 7.25 vs. 7.78, p < 0.0001, respectively). Patients with stable asthma, rhinitis, and eczema had also lower pH than that of controls (7.32, 7.48, and 7.44 vs. 7.78; p < 0.0001, p < 0.006, p < 0.04, respectively). Patients with acute asthma normalized their pH after treatment (7.82 vs. 7.25; p < 0.0001). Finally, patients with acute asthma showed a positive correlation between pH and lung functional parameters (forced expiratory volume in 1 s; r = 0.39, p = 0.04). Our study shows that EBC pH measurement may be a promising marker for assessing airway inflammation and monitoring response to anti-inflammatory treatment in asthmatic children. Furthermore, we report the first evidence of airways acidification in children with allergic rhinitis and atopic dermatitis. Therefore, EBC pH assessment may be useful in the evaluation of progression of the atopic march toward the development of asthma later in life. Further studies are recommended in order to confirm this indication.

Evaluation of methodological and biological influences on the collection and composition of exhaled breath condensate

The purpose of this inter-species comparison (calves and pigs) was to identify methodological and biological influences on the collection and composition of exhaled breath condensate (EBC). A total of 352 EBC samples were collected, whilst variables of ventilation were registered in parallel. Partial pressure of carbon dioxide (pCO2) and pH were analysed in non-degassed EBC samples. The concentration of total protein in EBC was measured colorimetrically. In both species, lung function was evaluated before and after EBC collection. Statistical analyses were performed to study the effect of EBC collection on lung function and to identify the influence of ventilatory variables on the collection and composition of EBC. Collection of EBC did not affect lung function. Despite the volume of EBC collected per unit time being primarily dependent on ventilation per unit time, species-specific conditions during the EBC collection process resulted in different dependences of EBC collection from other variables of ventilation (i.e. maximal airflow during expiration or expired tidal volume kg-1 body weight). The concentration of protein ml(-1) EBC increased with the expired volume per min and with peak expiratory flow. Although the pCO2 in fresh EBC was significantly negatively dependent on the duration of collection, comparable pHs (5.6 - 6.2) were measured in EBC of both calves and pigs. The obtained data may help one standardize EBC collection in different species.

Comparison of two methods for exhaled breath condensate collection

BACKGROUND

Exhaled breath condensate (EBC) is a noninvasive method to obtain samples from fluids lining the respiratory surfaces. Even though various methods and devices are now available, the relative efficiency of these methods for recovering airway mediators and characterizing EBC has not been established.

AIM

To compare the volume, pH, lipid mediator, and protein concentrations in EBCs collected by two commonly used commercially available devices, RTube and ECoScreen.

METHODS

Exhaled breath condensates were obtained consecutively using the RTube and ECoScreen methods from 30 healthy, nonallergic adults. Samples were immediately placed on dry ice after collection. pH was measured after argon deaeration. Cysteinyl leukotrienes (cys-LTs) were measured as a representative lipid mediator and eotaxin as the protein mediator by using enzyme-linked immunosorbent assay.

RESULTS

The mean volume of samples obtained with ECoScreen (1880 +/- 116 microl) was significantly higher than that obtained with RTube (1405 +/- 82 microl) (P < 0.001). Concentrations of both cys-LTs [205.4 pg/ml (65.5-472.3) with ECoScreen vs 21.6 (11.87-152.2) with RTube, P < 0.001] and eotaxin [17.0 pg/ml (11.4-22.4) with ECoScreen vs 11.7 (10.5-13.5) with RTube, P = 0.01] were significantly higher in samples collected with ECoScreen than with RTube. There was no significant difference between the pH measurements.

CONCLUSION

Compared with RTube, collection of exhaled breath by ECoScreen allows larger volumes to be collected and detects protein and lipid mediators with greater sensitivity. These differences in mediator recovery may be due to the differences in the collection temperature.

Free 3-nitrotyrosine in exhaled breath condensates of children fails as a marker for oxidative stress in stable cystic fibrosis and asthma

3-Nitrotyrosine (3-NT) is considered as a marker of oxidative stress, which occurs during inflammation. Since 3-NT levels in exhaled breath condensate (EBC) are very low, we applied a specific and sensitive gas chromatography-negative ion chemical ionization-mass spectrometry (GC-NICI-MS) method and high performance liquid chromatography (HPLC) with electrochemical detection for the analysis of free 3-NT in EBC. A total of 42 children (aged 5-17 years) were enrolled in this study, including children with asthma (n=12), cystic fibrosis (n=12), and healthy controls (n=18). Additionally, 14 healthy non-smoking adults (aged 18-59 years) were included. An EcoScreen system was used for the collection of EBC samples. Free 3-NT levels in EBC ranged from 0.54-6.8 nM. Median (interquartile range) concentrations (nM) were similar in all groups: 1.46 (0.97-2.49) in healthy adults, 2.51 (1.22-3.51) in healthy children, 1.46 (0.88-2.02) in children with asthma, and 1.97 (1.37-2.35) in CF children, respectively (p=0.24, Kruskall-Walis test). No difference was found between the children with airway disease and age-matched healthy controls. In healthy subjects, there was no effect of age on 3-NT concentrations. HPLC analyses provided similar concentration ranges for EBC 3-NT when compared with GC-NICI-MS. Our study has clearly demonstrated that free 3-NT in EBC fails as a marker for oxidative stress in children with stable CF and asthma.

Dissolution of materials in artificial skin surface film liquids

The dissolution of chemical constituents from jewelry, textiles, cosmetics, drugs, industrial chemicals, and particles in direct and prolonged contact with human skin is often assessed in vitro using artificial skin surface film liquids (SSFL). To provide meaningful results, the composition of artificial SSFL should accurately mimic human sweat and sebum, and the conditions of the in vitro test system should accurately reflect in vivo skin conditions. We summarized the reported composition of human SSFL and compared it to 45 different formulations of artificial sweat and 18 formulations of artificial sebum (studies published from 1940 to 2005). Conditions of in vitro dissolution test systems were reviewed and compared to in vivo skin conditions. The concentrations of individual constituents and pH of artificial sweat and concentrations of artificial sebum constituents are not always within ranges reported for human SSFL. Nearly all artificial SSFL lack many of the constituents in human SSFL. To develop a comprehensive model SSFL, we propose a standard SSFL, modified from the two best published sweat and sebum formulations. Little is known concerning the influence of test system conditions on dissolution, including SSFL temperature, container material composition, agitation, and physicochemical properties of the test article on dissolution. Thus, both a need and an opportunity exist for standardizing the composition of artificial SSFL and in vitro dissolution test methodologies. To standardize in vitro dissolution test systems, we recommend: maintaining artificial SSFL at a biologically relevant temperature appropriate to the human activity being modeled, carefully selecting test and sample storage containers to avoid bias in dissolution measurements, accounting for friction between a test article and skin in a biologically plausible manner, and physicochemical characterization of the test article or material to better understand mechanisms of dissolution and potential mechanisms of toxic action of dissolved material. More accurate modeling and better understanding of chemical dissolution from articles in contact with the skin will ultimately improve risk decision making, thereby protecting even the most susceptible persons from adverse health effects resulting from skin exposure.

Markers of airway inflammation in primary ciliary dyskinesia studied using exhaled breath condensate

Macroscopically, the airways in primary ciliary dyskinesia (PCD) are inflamed and infected, and the eventual result is bronchiectasis. The measurement of noninvasive markers of inflammation in PCD may allow determination of mechanisms of tissue damage, and even allow monitoring of therapy. The aim of this study was to measure in exhaled breath condensate (EBC) of children with PCD the concentrations of the neutrophil chemoattractants leukotriene (LT) B4 and interleukin (IL)-8 and the marker of oxidative stress 8-isoprostane (8-IP), and to try determining whether these markers can be used to assess mechanisms of airway inflammation in these patients. Concentrations of LTB4, IL-8, and 8-IP in the EBC of 23 PCD and 11 age-matched healthy children were measured using an enzyme immunoassay (EIA). The children also performed spirometry and underwent sputum induction, the latter for differential cell count. The concentrations of 8-IP in EBC of children with stable PCD were significantly increased compared to normal controls (median, 7.8 pg/ml vs. 3.1 pg/ml; P = 0.004). There was no difference in the median concentrations of EBC LTB4 between PCD subjects and healthy controls (28 pg/ml vs. 28 pg/ml; P = 0.5). IL-8 levels were below the detection limit of the assay, and were not analyzed further. There was no correlation between concentrations of either 8-IP or LTB(4) in EBC and forced expired volume in 1 sec in PCD children. Sputum induction was successful in 83% of the subjects; the median induced sputum neutrophil count was 69% (interquartile range, 59.3-73.6). No significant correlation was found between sputum neutrophils and either EBC 8-IP or LTB4 concentrations in PCD children. This study showed that oxidative stress, as reflected by increased exhaled 8-IP concentration, is increased in PCD children. The mechanism of airway neutrophilia is unclear, but is unlikely to be related to increased production of LTB4, at least in stable PCD patients.

Exhaled breath condensate pH and childhood asthma: unselected birth cohort study

RATIONALE

Exhaled breath condensate pH (EBC-pH) may be useful noninvasive marker for evaluation of patients with asthma.

OBJECTIVES

To investigate the relationship between EBC-pH and symptoms suggestive of childhood asthma in an epidemiologic setting and examine its relation to lung function, airway hyperresponsiveness (AHR), and airway inflammation.

METHODS

Within the context of a prospective population-based birth cohort, EBC was collected from 630 children at age 8 yr using the RTube (pH measured after deaeration with argon). Lung function was measured by spirometry (FEV1; n = 521) and plethysmography (sRaw; n = 567), and AHR by methacholine challenge (n = 498). Airway inflammation was assessed using exhaled nitric oxide (eNO; n = 305).

RESULTS

EBC-pH values ranged widely (4.40-8.29), and did not differ between 54 children with parentally reported asthma and 562 nonasthmatic subjects (median [interquartile range]: 7.75 [7.45-7.85] vs. 7.77 [7.59-7.87]; p = 0.35). There was a trend for lower EBC-pH among current wheezers (n = 98; 7.72 [7.50-7.83]) compared with nonwheezers (n = 532; 7.77 [7.60-7.87]; p = 0.07). Wheeze frequency, severity, and use of antiasthma medication were not associated with EBC-pH. There was no consistent association between EBC-pH and lung function, airway reactivity, and airway inflammation (FEV1, sRaw, PD20 methacholine, or eNO). There was no significant difference in EBC-pH between current wheezers receiving asthma medication who had positive methacholine challenge compared with children without any of these features.

CONCLUSIONS

In the epidemiologic setting, EBC-pH does not differ between children with and without parentally reported symptoms suggestive of asthma. We found no consistent association between EBC-pH and lung function, AHR, and airway inflammation in this sample from the general population.

Exhaled breath condensate levels of eotaxin and macrophage-derived chemokine in stable adult asthma patients

BACKGROUND

Asthma is associated with esoinophilic airway inflammation and overproduction of T-helper type 2 (Th2) lymphocyte-related cytokines.

OBJECTIVE

This study assessed the eosinophil chemoattractant eotaxin and Th2-specific macrophage-derived chemokine (MDC) in the adult asthmatic airway. Eotaxin and MDC levels were determined in exhaled breath condensate (EBC) obtained from adult patients with asthma.

METHODS

Fifty-four asthmatics (20 male, mean (SD) age 40 (12) years and percentage predicted forced expiratory volume in 1 s (FEV(1)) 81.7 (20.8)) and 20 age- and sex-matched controls were studied. EBC was collected using EcoScreen by 10 min of tidal breathing with a nose clip. Concentrations of eotaxin and MDC were measured by ELISA.

RESULTS

Asthma patients on inhaled corticosteroid (ICS) had a higher median interquartile range (IQR) level of eotaxin than the steroid-naïve asthmatics (18.5 (17.7-20.1) vs. 17.9 (17.0-18.6) pg/mL, P=0.02) and controls (18.5 (17.7-20.1) pg/mL vs 17.4 (16.3-18.0) pg/mL, P=0.001). Eotaxin level in EBC had a significant negative correlation with the FEV(1)/forced vital capacity ratio (r=-0.43, P=0.03) in steroid-naïve asthmatics. EBC MDC level was higher in subjects on ICS than the steroid naïve asthmatics (120 (118-125) vs. 117 (116-119) pg/mL, P=0.01) and the controls (120 (118-125) vs. 117 (116-120) pg/mL, P=0.02).

CONCLUSIONS

Eotaxin and MDC could be measured in EBC of adults with asthma. EBC eotaxin and MDC levels were higher in asthmatics on ICS than the steroid-naïve asthmatics or controls. Exhaled chemokines may be potential non-invasive markers for assessing airway inflammation in asthmatics.

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.

A critical appraisal of methods used in early clinical development of novel drugs for the treatment of asthma

Asthma is a heterogeneous disorder characterized by chronic airway inflammation, hyperresponsiveness and remodeling. Being the hallmark of asthma, airway inflammation has become the most important target for therapeutic agents. Consequently, during the past decade various semi-and non-invasive methods have been explored to sample the airway inflammation in asthma. In this review, we provide a practical overview of the current status of various sampling techniques including sputum induction, exhaled breath analysis, and bronchoprovocation tests (BPTs). We focus on their applicability for monitoring in clinical practice and in intervention trials in asthma.

Measuring exhaled breath condensates in infants

There is growing interest in investigating compounds of exhaled breath condensates (EBC) as potential noninvasive markers of airways disease processes. Some of these markers have the potential to provide information on the early stages of disease. In this paper, we present a method for collecting EBC during both oral and nasal breathing in infants. Fifty-four infants (mean age, 13.3 months; range, 1-30 months) undergoing infant lung-function testing were recruited for this study. Breath condensates were collected during sedated sleep, using a custom-made collection device. Collections were made for 10 min during normal tidal breathing. Nasal measurements were attempted in all children by placing a face-mask over the nose and mouth and keeping the mouth closed. In 14 infants, oral measurements were made by placing a face-mask over the mouth only and occluding the nose. Condensates were collected successfully in all but one child. The collected volume ranged from 50-550 microl (mean +/- SD, 281.8 +/- 145.8 microl). The volume of EBC collected was correlated to age, length, weight, and minute ventilation. Significantly more EBC was collected during oral compared to nasal breathing (354.3 vs. 277.5 microl, P=0.03). There were no significant changes in heart rate, respiratory rate, or oxygen saturation during collection. The collection of EBC in young children and infants is feasible and safe, and the method used here allows the successful collection of reasonable amounts of exhaled condensate.

Methodological improvements for measuring eicosanoids and cytokines in exhaled breath condensate

BACKGROUND

Exhaled breath condensate (EBC) is simple to collect and as such a non-invasive method that has attracted substantial interest in the last few years. However, several methodological concerns have been raised and it has been difficult to reproduce results between different centres. Because of low concentrations of inflammatory markers, potential loss in the sampling system may have great influence. The aim of the present study was to se if evaporation and plastic coating could facilitate detection.

METHODOLOGY

Through methodological improvements, we have now made it possible to measure EBC concentrations of eicosanoids and cytokines in our system. Due to absorbance of both fatty acid derivates and proteins to several plastics, the first step is coating of all surfaces with bovine serum albumin and Tween 20. Since several assays are sensitive to these factors, the methodology has to be standardised to avoid false results. Secondly, larger amounts of EBC have to be vacuum-dried, and thereafter resolved in the respective assay buffers. The EBCs have to be concentrated 5-10 times, depending on samples and assay sensitivity.

RESULTS

Due to these improvements we can measure, for example, cysteinyl-leukotrienes, leukotriene B4, prostaglandin E and 8-isoprostane. High sensitivity assays have also made it possible to measure cytokines, for example, interleukin (IL)-1beta, IL-8 and IL-13.

SUMMARY

We are aware of different results from other labs. However, it seems essential to coat and to concentrate the samples in order to achieve reliable and measurable results.

Utility of exhaled breath condensates in chronic obstructive pulmonary disease: a critical review

PURPOSE OF REVIEW

Evaluation of the utility of exhaled breath condensates in chronic obstructive pulmonary disease.

RECENT FINDINGS

Exhaled breath condensates have recently been introduced as a simple, noninvasive method of sampling respiratory fluid in inflammatory lung disorders, including chronic obstructive pulmonary disease. Increases in condensate concentrations of at least 12 markers of inflammation have been reported in these disorders. Furthermore, condensate pH appears to be decreased in both chronic obstructive lung disease and bronchial asthma. This has been referred to as acidopnea and could reflect airway acidification by inflammatory cells. Although safer and more convenient than bronchoalveolar lavage, interpretation of condensate data is complicated by uncertainty regarding the source of condensate solutes and by variable dilution of respiratory droplets from condensed water vapor, which represents more than 99.9% of condensate volumes. This dilution can be estimated from the dilution of plasma constituents such as urea or electrolytes. Because the principal buffer in condensate is NH4, much of which is derived from bacterial degradation of urea in the mouth, condensate pH measurements may not provide accurate estimates of airway pH. Nevertheless, acidification of condensate may be indicative of gastroesophageal reflux, which frequently occurs in obstructive lung diseases and may contribute to cough and bronchospasm.

SUMMARY

It is too early to tell how useful condensate studies will be to pulmonary investigators and clinicians. Realization of the enormous potential of this approach will require a thorough understanding of the manner in which these solutions are generated and how they should be analyzed.

Epithelial lining fluid solute concentrations in chronic obstructive lung disease patients and normal subjects

The exhaled breath condensate (EBC) method represents a new, noninvasive way to detect inflammatory and metabolic markers in the fluid that covers the airways [epithelial lining fluid (ELF)]. However, respiratory droplets represent only a very small and variable fraction of the EBC, most (approximately 99.99%) of which is water vapor. Our objective was to show that ELF concentrations could be calculated from EBC values by using any of three dilutional indicators (urea, total cations, and conductivity) in nine normal and nine chronic obstructive lung disease (COPD) subjects. EBC concentrations of Na(+), K(+), Ca(2+), Mg(2+), total cations, urea, and conductivity varied over a 10-fold range among individuals, but concentrations of these constituents (except Ca(2+)) remained well correlated (r(2) = 0.44-0.83, P < 0.001). Dilution (D) of respiratory droplets in water vapor was calculated by dividing plasma concentrations of the dilutional indicators by EBC concentrations. Estimates of D were not significantly different among these indicators, and urea D averaged 10,800 +/- 2,100 (SE) in normal and 12,600 +/- 3,300 in COPD subjects. Although calculated Na(+) concentrations in the ELF were less than one-half those in plasma, and concentrations of K(+), Ca(2+), and Mg(2+) exceeded those in plasma, total cation concentrations in ELF were not significantly different from those in plasma, indicating that ELF is isotonic in both normal and COPD subjects. EBC amylase concentrations (measured with an ultrasensitive procedure) indicated that saliva represented <10% of the respiratory (ELF) droplets in all but three samples. Dilutional and salivary markers are essential for interpretation of EBC studies.

Optimization and validation of an ion chromatographic method for the simultaneous determination of sodium, ammonium and potassium in exhaled breath condensate

An ion chromatographic method with conductivity detection for the simultaneous quantification of sodium, ammonium and potassium in exhaled breath condensate (EBC) was developed and validated. A factorial design was used to optimize the chromatographic conditions, which resulted in baseline separations of the cations within 6 min. The method requires no pre-treatment of EBC samples. The optimized method was used for the intra-individual screening of cations in EBC of 10 healthy volunteers. The LOQs were low (0.3, 0.1 and 0.2 microM for sodium, ammonium and potassium, respectively), compared with levels detected in healthy volunteers. The responses were linear with good precision, and samples could be stored for at least 10 weeks at refrigerating conditions.

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.