Methodological improvements for measuring eicosanoids and cytokines in exhaled breath condensate

Inflammatory Biomarkers in Exhaled Breath Condensate: A Systematic Review

Inflammation is a comprehensive set of physiological processes that an organism undertakes in response to a wide variety of foreign stimuli, such as viruses, bacteria, and inorganic particles. A key role is played by cytokines, protein-based chemical mediators produced by a broad range of cells, including the immune cells recruited in the inflammation site. The aim of this systematic review is to compare baseline values of pro/anti-inflammatory biomarkers measured in Exhaled Breath Condensate (EBC) in healthy, non-smoking adults to provide a summary of the concentrations reported in the literature. We focused on: interleukin (IL)-1β, IL-4, IL-6, IL-8, IL-10, tumour necrosis factor-alpha (TNF-α), and C reactive protein (CRP). Eligible articles were identified in PubMed, Embase, and Cochrane CENTRAL. Due to the wide differences in methodologies employed in the included articles concerning EBC sampling, storage, and analyses, research protocols were assessed specifically to test their adherence to the ATS/ERS Task Force guidelines on EBC. The development of reference intervals for these biomarkers can result in their introduction and use in both research and clinical settings, not only for monitoring purposes but also, in the perspective of future longitudinal studies, as predictive parameters for the onset and development of chronic diseases with inflammatory aetiology.

Analytical Approaches for the Determination of Buprenorphine, Methadone and Their Metabolites in Biological Matrices

The abuse of buprenorphine and methadone has grown into a rising worldwide issue. After their consumption, buprenorphine, methadone and their metabolites can be found in the human organism. Due to the difficulty in the assessment of these compounds by routine drug screening, the importance of developing highly sensitive analytical approaches is undeniable. Liquid chromatography tandem mass spectrometry is the preferable technique for the determination of buprenorphine, methadone and their metabolites in biological matrices including urine, plasma, nails or oral fluids. This research aims to review a critical discussion of the latest trends for the monitoring of buprenorphine, methadone and their metabolites in various biological specimens.

Challenges in Quantifying 8-OHdG and 8-Isoprostane in Exhaled Breath Condensate

Exhaled breath condensate (EBC) has attracted substantial interest in the last few years, enabling the assessment of airway inflammation with a non-invasive method. Concentrations of 8-Hydroxydesoxyguanosine (8-OHdG) and 8-isoprostane in EBC have been suggested as candidate biomarkers for lung diseases associated with inflammation and oxidative stress. EBC is a diluted biological matrix and consequently, requires highly sensitive chemical analytic methods (picomolar range) for biomarker quantification. We developed a new liquid chromatography coupled to tandem mass spectrometry method to quantify 8-OHdG and 8-isoprostane in EBC simultaneously. We applied this novel biomarker method in EBC obtained from 10 healthy subjects, 7 asthmatic subjects, and 9 subjects with chronic obstructive pulmonary disease. Both biomarkers were below the limit of detection (LOD) despite the good sensitivity of the chemical analytical method (LOD = 0.5 pg/mL for 8-OHdG; 1 pg/mL for 8-isoprostane). This lack of detection might result from factors affecting EBC collections. These findings are in line with methodological concerns already raised regarding the reliability of EBC collection for quantification of 8-OHdG and 8-isoprostane. Precaution is therefore needed when comparing literature results without considering methodological issues relative to EBC collection and analysis. Loss of analyte during EBC collection procedures still needs to be resolved before using these oxidative stress biomarkers in EBC.

Molecular analysis of phenotypic interactions of asthma

INTRODUCTION

Asthma is a heterogeneous disease characterized by multiples respiratory symptoms; this is a polygenic entity that involves a complex interaction of environmental factors and inherent to the individual. To understand the development of asthma, some phenotypes have been proposed.

OBJECTIVE

This work's purpose was to explore different molecules related to asthma development and to define each phenotype's specific characteristics.

MATERIAL AND METHODS

96 adult patients diagnosed with asthma before any treatment were enrolled in the protocol. Spirometric parameters, circulating leukocytes, serum IgE, body mass index, exhaled nitric oxide (FENO), and leukotrienes (LTB4) in urine were determined in each patient. The presence of asthma phenotypes proposed by the Global Initiative for Asthma (GINA) were explored: A) Allergic asthma, B) Non-allergic asthma, C) Late-onset asthma, D) Asthma with persistent airflow limitation, and E) Asthma with overweight and obesity.

RESULTS

In the cohort analyzed, we found four of phenotypes proposed by GINA; however, these phenotypes overlapped, due to this, 4 groups were integrated with allergic, non-allergic and obese patients, which were the main phenotypes. The main overlap was that of patients not-obese allergic, and was characterized by earlier onset, elevated levels of IgE, LTB4 and inflammasome related cytokines. Non-allergic patients had a significant association between interleukin (IL)-18 and IL-18 binding protein (BP) with narrow ratio between these cytokines. Finally, LTB4 had remarkable capacity to discriminate between allergic and not allergic patients.

CONCLUSIONS

Asthmatic phenotypes exist as interrelated characteristics and not as discrete entities. High levels of leukotrienes and IgE are hallmarks in the allergic phenotype of asthma.

Breathomics: Review of Sample Collection and Analysis, Data Modeling and Clinical Applications

Metabolomics research is rapidly gaining momentum in disease diagnosis, on top of other Omics technologies. Breathomics, as a branch of metabolomics is developing in various frontiers, for early and noninvasive monitoring of disease. This review starts with a brief introduction to metabolomics and breathomics. A number of important technical issues in exhaled breath collection and factors affecting the sampling procedures are presented. We review the recent progress in metabolomics approaches and a summary of their applications on the respiratory and non-respiratory diseases investigated by breath analysis. Recent reports on breathomics studies retrieved from Scopus and Pubmed were reviewed in this work. We conclude that analyzing breath metabolites (both volatile and nonvolatile) is valuable in disease diagnoses, and therefore believe that breathomics will turn into a promising noninvasive discipline in biomarker discovery and early disease detection in personalized medicine. The problem of wide variations in the reported metabolite concentrations from breathomics studies should be tackled by developing more accurate analytical methods and sophisticated numerical analytical alogorithms.

Exhaled Breath Condensate: An Update

Exhaled breath condensate (EBC) is a promising source of biomarkers of lung disease. EBC research and utility has increased substantially over the past 2 decades. This review summarizes many of the factors regarding the composition of EBC, its collection, and analysis for the utility of both clinicians and researchers.

Non-volatile compounds in exhaled breath condensate: review of methodological aspects

In contrast to bronchial and nasal lavages, the analysis of exhaled breath condensate (EBC) is a promising, simple, non-invasive, repeatable, and diagnostic method for studying the composition of airway lining fluid with the potential to assess lung inflammation, exacerbations, and disease severity, and to monitor the effectiveness of treatment regimens. Recent investigations have revealed the potential applications of EBC analysis in systemic diseases. In this review, we highlight the analytical studies conducted on non-volatile compounds/biomarkers in EBC. In contrast to other related articles, this review is classified on the basis of analytical techniques and includes almost all the applied methods and their methodological limitations for quantification of non-volatile compounds in EBC samples, providing a guideline for further researches. The studies were identified by searching the SCOPUS database with the keywords "biomarkers," "non-volatile compounds," "determination method," and "EBC."

Biomarkers in adult asthma: a systematic review of 8-isoprostane in exhaled breath condensate

OBJECTIVES

We aimed to assess the evidence for the use of 8-isoprostane in exhaled breath condensate (EBC) as a biomarker in adult asthma.

DESIGN

A systematic review and meta-analysis of EBC 8-isoprostane.

METHODS

We searched a number of online databases (including PubMed, Embase and Scopus) in January 2016. We included studies of adult non-smokers with EBC collection and asthma diagnosis conducted according to recognised guidelines. We aimed to pool data using random effects meta-analysis and assess heterogeneity using I ².

RESULTS

We included twenty studies, the findings from which were inconsistent. Seven studies (n = 329) reported 8-isoprostane levels in asthma to be significantly higher than that of control groups, whilst six studies (n = 403) did not. Only four studies were appropriate for inclusion in a random effects meta-analysis of mean difference. This found a statistically significant between-groups difference of 22 pg ml^-1. Confidence in the result is limited by the small number of studies and by substantial statistical heterogeneity (I ² = 94).

CONCLUSION

The clinical value of EBC 8-isoprostane as a quantitative assessment of oxidative stress in asthma remains unclear due to variability in results and methodological heterogeneity. It is essential to develop a robust and standardised methodology if the use of EBC 8-isoprostane in asthma is to be properly evaluated.

Evaluating the role of leukotriene-modifying drugs in asthma management: Are their benefits 'losing in translation'?

Leukotrienes (LTs) initiate a cascade of reactions that cause bronchoconstriction and inflammation in asthma. LT-modifying drugs have been proved very effective to reduce inflammation and associated exacerbation however despite some illustrious clinical trials the usage of these drugs remains overlooked because the evidence to support their utility in asthma management has been mixed and varied between studies. Although, there are plenty of evidences which suggest that the leukotriene-modifying drugs provide consistent improvement even after just the first oral dose and reduce asthma exacerbations, the beneficial effect of these drugs has remained sparse and widely debated. And these beneficial effects are often overlooked because most of the clinical studies include a mixed population of asthmatics who do not respond to LT-modifiers equally. Therefore, in the present era of personalized medicine, it is important to properly stratify the patients and non-invasive measurements of biomarkers may warrant the possibility to characterize biological/pathological pathway to direct treatment to those who will benefit from it. Endotyping based on individual's leukotriene levels should probably ascertain a subgroup of patients that would clearly benefit from the treatment even though the trial fails to show overall significance. In this article, we have methodically evaluated contemporary literature describing the efficacy of LT-modifying drugs in the management of asthma and highlighted the importance of phenotyping the asthmatics for better treatment outcomes.

The analysis of volatile organic compounds in exhaled breath and biomarkers in exhaled breath condensate in children - clinical tools or scientific toys?

Current monitoring strategies for respiratory diseases are mainly based on clinical features, lung function and imaging. As airway inflammation is the hallmark of many respiratory diseases in childhood, noninvasive methods to assess the presence and severity of airway inflammation might be helpful in both diagnosing and monitoring paediatric respiratory diseases. At present, the measurement of fractional exhaled nitric oxide is the only noninvasive method available to assess eosinophilic airway inflammation in clinical practice. We aimed to evaluate whether the analysis of volatile organic compounds (VOCs) in exhaled breath (EB) and biomarkers in exhaled breath condensate (EBC) is helpful in diagnosing and monitoring respiratory diseases in children. An extensive literature search was conducted in Medline, Embase and PubMed on the analysis and applications of VOCs in EB and EBC in children. We retrieved 1165 papers, of which nine contained original data on VOCs in EB and 84 on biomarkers in EBC. These were included in this review. We give an overview of the clinical applications in childhood and summarize the methodological issues. Several VOCs in EB and biomarkers in EBC have the potential to distinguish patients from healthy controls and to monitor treatment responses. Lack of standardization of collection methods and analysis techniques hampers the introduction in clinical practice. The measurement of metabolomic profiles may have important advantages over detecting single markers. There is a lack of longitudinal studies and external validation to reveal whether EB and EBC analysis have added value in the diagnostic process and follow-up of children with respiratory diseases. In conclusion, the use of VOCs in EB and biomarkers in EBC as markers of inflammatory airway diseases in children is still a research tool and not validated for clinical use.

Patients with chronic obstructive pulmonary disease and chronically colonized with Haemophilus influenzae during stable disease phase have increased airway inflammation

Background

Some patients with chronic obstructive pulmonary disease (COPD) show increased airway inflammation and bacterial colonization during stable phase. The aim of this study was to follow COPD patients and investigate chronic colonization with pathogenic bacteria during stable disease phase, and relate these findings to clinical parameters, inflammatory pattern, lung function, and exacerbations.

Methods

Forty-three patients with COPD were included while in a stable state and followed up monthly until exacerbation or for a maximum of 6 months. The patients completed the Clinical COPD Questionnaire and Medical Research Council dyspnea scale questionnaires, and exhaled breath condensate was collected, followed by spirometry, impulse oscillometry, and sputum induction.

Results

Ten patients were chronically colonized (ie, colonized at all visits) with Haemophilus influenzae during stable phase. These patients had higher sputum levels of leukotriene B₄ (P<0.001), 8-isoprostane (P=0.002), myeloperoxidase activity (P=0.028), and interleukin-8 (P=0.02) during stable phase when compared with other patients. In addition, they had lower forced vital capacity (P=0.035) and reactance at 5 Hz (P=0.034), but there was no difference in forced expiratory volume in 1 second (FEV₁), FEV₁ % predicted, forced vital capacity % predicted, exhaled breath condensate biomarkers, C-reactive protein, or Clinical COPD Questionnaire and Medical Research Council dyspnea scale results. Three patients had intermittent colonization (colonized at only some visits) of H. influenzae during stable phase, and had lower levels of inflammatory biomarkers in sputum when compared with the chronically colonized patients. The difference in airway inflammation seen during stable phase in patients chronically colonized with H. influenzae was not observed during exacerbations.

Conclusion

Some COPD patients who were chronically colonized with H. influenzae during stable phase showed increased airway inflammation and reduced lung volumes when compared with non-chronically colonized patients.

Biomarkers of eosinophilic inflammation in asthma

Eosinophils are mediators of allergic inflammation and are implicated in the pathogenesis of numerous conditions including asthma, parasitic infections, neoplasms, hyper-eosinophilic syndromes, vasculitic disorders, and organ-specific conditions. Assessing eosinophilic inflammation is therefore important in establishing a diagnosis, in monitoring and assessing response to treatment, and in testing novel therapeutics. Clinical markers of atopy and eosinophilic inflammation include indirect tests such as lung function, exhaled breath condensate analysis, fractional exhaled nitric oxide, serum immunoglobulin E levels and serum periostin. Direct measures, which quantify but do not anatomically localise inflammation include blood eosinophil counts, serum or plasma eosinophil cationic protein and sputum eosinophil levels. Cytology from bronchoalveolar lavage and histology from endobronchial and transbronchial biopsies are better at localising inflammation but are more invasive. Novel approaches using radiolabelled eosinophils with single-photon emission computed tomography, offer the prospect of non-invasive methods to localise eosinophilic inflammation.

Cysteinyl leukotriene levels correlate with 8-isoprostane levels in exhaled breath condensates of atopic and healthy children

BACKGROUND

Cysteinyl leukotrienes are important mediators of airway inflammation, whereas 8-isoprostane is a biomarker of oxidative stress. This study evaluated the distributions of cysteinyl leukotriene and 8-isoprostane concentrations in exhaled breath condensates (EBCs) of children. The relationship between cysteinyl leukotriene and 8-isoprostane concentrations in the EBCs was also evaluated.

METHODS

The EBCs were collected from 34 children with allergic respiratory diseases and 24 healthy children. All recruited children underwent pulmonary function testing every season. The severity of allergic respiratory diseases and medication status were assessed every month in children with allergic respiratory diseases.

RESULTS

The EBC cysteinyl leukotriene and 8-isoprostane levels were higher in children with asthma and allergic rhinitis than in those with asthma only and healthy children. In asthmatic children, cysteinyl leukotriene and 8-isoprostane levels peaked in the summer. All children showed a clear association between EBC cysteinyl leukotriene and EBC 8-isoprostane levels.

CONCLUSION

The cysteinyl leukotriene and 8-isoprostane concentrations in the EBCs of children significantly varied by season. Oxidative stress correlated with airway inflammation in children.

Effect of allergen inhalation on airway oxidant stress, using exhaled breath condensate 8-isoprostane, in mild asthma

OBJECTIVE

Exhaled breath condensate (EBC) 8-isoprostane concentrations are increased in asthma, but it is not known if they acutely change following bronchoprovocation. The objective of this study was to evaluate EBC 8-isoprostane concentrations following allergen-induced bronchoprovocation in asthma.

METHODS

This comparison study included eight mild atopic asthmatics and six controls. Asthmatics were challenged with inhaled specific allergen, methacholine, and irrelevant allergen in random order. Controls were challenged with irrelevant allergen. EBCs collected at 0, 3, 6, 9, and 23 hours by the R-tube method were measured for 8-isoprostanes by ELISA technique. Repeated measures ANOVA technique was used for analysis.

RESULTS

EBC 8-isoprostane concentrations did not change following any inhalational challenge, as compared to baseline, in either asthmatics or controls.

CONCLUSIONS

EBC 8-isoprostane concentrations do not acutely change following bronchoprovocation in subjects with mild asthma.

The role of exhaled nitric oxide and exhaled breath condensates in evaluating airway inflammation in asthma

BACKGROUND

Airway inflammation is central to the development and progression of asthma. Monitoring airway inflammation can be invasive and technically difficult, making its use limited in clinical practice. Several advances have been made in non-invasive techniques to monitor and measure inflammation from the airways.

OBJECTIVE

To examine the suitability of exhaled nitric oxide and exhaled breath condensates as diagnostic tools in asthma.

METHOD

The current literature regarding the use of exhaled nitric oxide and exhaled breath condensate to assess and manage asthma was reviewed.

CONCLUSION

Exhaled nitric oxide is a clinically useful marker of eosinophilic airway inflammation in asthma. Although showing promise, significant validation and investigation are required before exhaled breath condensate could be utilized in clinical practice.

Induced sputum, exhaled NO, and breath condensate in occupational medicine

OBJECTIVE

Studies of fractional exhaled NO (FeNO) or induced sputum are now well standardized and the exponential increase in publications about exhaled breath condensate reflects growing interest in a noninvasive diagnosis of pulmonary diseases in occupational medicine.

METHODS

This review describes current techniques (FeNO, induced sputum, and exhaled breath condensate) for the study of inflammation and oxidative stress biomarkers.

RESULTS

These biomarkers are FeNO, cytokines, H2O2, 8-isoprostane, malondialdehyde, and nitrogen oxides. These techniques also include the study of markers of the toxic burden in the lungs (heavy metals and mineral compounds) that are important in occupational health exposure assessment.

CONCLUSIONS

In occupational medicine, the study of both volatile and nonvolatile respiratory biomarkers can be useful in medical surveillance of exposed workers, the early identification of respiratory diseases, or the monitoring of their development.

Inflammatory markers in blood and exhaled air after short-term exposure to cooking fumes

Objectives:

Cooking fumes contain aldehydes, alkanoic acids, polycyclic aromatic hydrocarbons, and heterocyclic compounds. The inhalation of cooking fumes entails a risk of deleterious health effects. The aim of this study was to see if the inhalation of cooking fumes alters the expression of inflammatory reactions in the bronchial mucosa and its subsequent systemic inflammatory response in blood biomarkers.

Methods:

Twenty-four healthy volunteers stayed in a model kitchen on two different occasions for 2 or 4h. On the first occasion, there was only exposure to normal air, and on the second, there was exposure to controlled levels of cooking fumes. On each occasion, samples of blood, exhaled air, and exhaled breath condensate (EBC) were taken three times in 24h and inflammatory markers were measured from all samples.

Results:

There was an increase in the concentration of the d-dimer in blood from 0.27 to 0.28mg ml^–1 on the morning after exposure to cooking fumes compared with the levels the morning before (P-value = 0.004). There was also a trend of an increase in interleukin (IL)-6 in blood, ethane in exhaled air, and IL-1β in EBC after exposure to cooking fumes. In a sub-analysis of 12 subjects, there was also an increase in the levels of ethane—from 2.83 parts per billion (ppb) on the morning before exposure to cooking fumes to 3.53 ppb on the morning after exposure (P = 0.013)—and IL-1β—from 1.04 on the morning before exposure to cooking fumes to 1.39 pg ml^–1 immediately after (P = 0.024).

Conclusion:

In our experimental setting, we were able to unveil only small changes in the levels of inflammatory markers in exhaled air and in blood after short-term exposure to moderate concentrations of cooking fumes.

The effect of academic exam stress on mucosal and cellular airway immune markers among healthy and allergic individuals

Research suggests that psychological stress can exacerbate allergies, but relatively little is known about the effect of stress on mucosal immune processes central to allergic pathophysiology. In this study, we quantified vascular endothelial growth factor (VEGF), interferon gamma (IFN-γ), and interleukin-4 concentrations in saliva (S) and exhaled breath condensate (EBC) during final exams and at midsemester among 23 healthy and 21 allergic rhinitis individuals. IFN-γs decreased during exams for both groups while VEGF(EBC) increased (and increases in VEGFs were a trend). Elevated negative affect ratings predicted higher VEGF(EBC) in allergic individuals. IFN-γ(EBC) increased in healthy individuals early during exams and then decreased, while allergic individuals showed a decrease in IFN-γ(EBC) throughout final exams. These findings suggest that psychological stress can suppress cellular immune function among allergic individuals while increasing VEGF.

Exhaled breath condensate: an overview

Exhaled breath condensate (EBC) is a promising source of biomarkers of lung disease. EBC may be thought of either as a body fluid or as a condensate of exhaled gas. There are 3 principal contributors to EBC: variable-sized particles or droplets that are aerosolized from the airway lining fluid, distilled water that condenses from gas phase out of the nearly water-saturated exhalate, and water-soluble volatiles that are exhaled and absorbed into the condensing breath. The nonvolatile constituents and the water-soluble volatile constituents are of particular interest. Several key issues are discussed in this article.

Methodological aspects of exhaled breath condensate collection and analysis

The collection and analysis of exhaled breath condensate (EBC) may be useful for the management of patients with chronic respiratory disease at all ages. It is a promising technique due to its apparent simplicity and non-invasiveness. EBC does not disturb an ongoing respiratory inflammation. However, the methodology remains controversial, as it is not yet standardized. The current diversity of the methods used to collect and preserve EBC, the analytical pitfalls and the high degree of within-subject variability are the main issues that hamper further development into a clinical useful technique. In order to facilitate the process of standardization, a simplified schematic approach is proposed. An update of available data identified open issues on EBC methodology. These issues were then classified into three separate conditions related to their influence before, during or after the condensation process: (1) pre-condenser conditions related to subject and/or environment; (2) condenser conditions related to condenser equipment; and (3) post-condenser conditions related to preservation and/or analysis. This simplified methodological approach highlights the potential influence of the many techniques used before, during and after condensation of exhaled breath. It may also serve as a methodological checklist for a more systematical approach of EBC research and development.

Inflammatory mediators in exhaled breath condensate of healthy donors and exacerbated COPD patients

Samples of exhaled breath condensate (EBC) provide a convenient and non-invasive method to study inflammation in lung diseases. The aim of the present study was to evaluate and compare the inflammatory protein mediator levels in EBC from healthy donors (HD) and from patients with exacerbation of chronic obstructive pulmonary disease (COPD) using an EBC collection device with and without a coating of albumin as a carrier. We studied 13 HD and 26 patients with exacerbation of COPD. The concentrations of myeloperoxidase (MPO), IFNγ and secretory leukocyte protease inhibitor (SLPI) in EBC were measured by immunoassays. The EBC samples from HD and COPD patients showed higher concentrations of MPO when samples were recovered with an albumin-coated device. Furthermore, levels of MPO in COPD patients were significantly higher than in HD. An inverse correlation was observed between MPO and spirometric parameters (FVC and FEV1). Almost all samples collected with the albumin-coated device showed higher amounts of IFNγ and SLPI than those collected with the uncoated device. The levels of SLPI in COPD patients were significantly higher than in HD. A direct correlation was observed between FVC% predicted and SLPI. We concluded that coating the collection device with albumin increased the sensitivity of the technique, at least for measurements of MPO, SLPI and IFNγ. Furthermore, the higher levels of MPO and SLPI and lower levels of IFNγ in EBC from COPD patients could reflect the immunological status and the response of lung parenchyma to treatment during the exacerbation of the illness.

Exhaled breath marker in asthma patients with gastroesophageal reflux disease

Prevention of acid is important in gastroesophageal reflex disease (GERD)-related asthma therapy. Proton pump inhibitors (PPI) and H₂-receptor blockers have been reported as useful therapies for improving asthma symptoms. GERD prevalence is high in asthma; however, methods for validating GERD existence based on questionnaire, endoscopic examination and 24h-pH monitoring do not directly determine GERD influence on the airway. Exhaled breath condensate analysis is a novel and non-invasive tool for assessing information directly from the airway. Breath collected by cooling can be applied to pH, 8-isoprostane and cytokine analysis in patients with GERD-related asthma, and the pH and 8-isoprostane levels have been shown to reflect the effects of PPI therapy in these patients. Although the analysis of cooled breath has not yet been established in a clinical setting, this method is expected to provide a novel tool for monitoring airway acidification associated with GERD.

Exercise increases exhaled breath condensate cysteinyl leukotriene concentration in asthmatic patients

BACKGROUND

Although the importance of cysteinyl leukotrienes (Cys-LTs) in exercise-induced bronchoconstriction (EIB) is supported by various sources of evidence, how the concentration of these mediators change during the development of EIB has not been investigated.

OBJECTIVES

Our goal was to determine the effect of exercise on the concentration of airway Cys-LT in asthmatic patients by measuring Cys-LT in exhaled breath condensate (EBC).

METHODS

Seventeen atopic asthmatic patients with a previous history of EIB and six healthy volunteers were studied. Before and two times within 10 minutes after exercise challenge, FEV₁ was measured and EBC was collected for Cys-LT measurement. Exhaled nitric oxide level, a marker of airway inflammation, was also determined at baseline.

RESULTS

Baseline Cys-LT level was higher in the asthmatic group versus healthy subjects (168 pg/mL /112-223/ vs. 77 pg/mL /36-119/, p = .03). EBC Cys-LT concentration increased in all asthmatic patients post-exercise (n = 17, p = .03), with the increase significantly greater in patients developing exercise-induced bronchospasm (n = 7, p = .03), whereas no change was observed in healthy controls (p = .59). The exercise-induced fall in FEV(1) in asthmatics was related to the increase in EBC Cys-LT concentration (r = -0.40, p = .03).

CONCLUSIONS

Our study shows that Cys-LT concentration of EBC is elevated minutes after physical exercise in asthmatic patients and strongly supports the concept that the release of this mediator is involved in the development of EIB.

Exhaled breath condensates in asthma: diagnostic and therapeutic implications

Exhaled breath condensate (EBC) collection and analysis offers a unique non-invasive method to sample the airway lining fluid. It enables classification and quantification of airway inflammation associated with various pulmonary diseases such as asthma. Over the last decade, innumerable efforts have been made to identify biomarkers in EBC for diagnosis and management of asthma. The aim of this review is to consolidate information available to date, summarize findings from studies and identify potential biomarkers which need further refinement through translational research prior to application in clinical practice.

A new approach to study exhaled proteins as potential biomarkers for asthma

BACKGROUND

Asthma is a complex clinical disease characterized by airway inflammation. Recently, various studies reported on the analysis of exhaled breath condensate (EBC) in the search for potential biomarkers for asthma. However, in a complex disease such as asthma, one biomarker might not be enough for early diagnosis or follow-up.

OBJECTIVE

The use of proteome analysis may reveal disease-specific proteolytic peptide or protein patterns, and may lead to the identification of novel proteins for the detection of asthma.

METHODS

Liquid chromatography and mass spectrometry were used to separate and detect proteins (proteolytic peptides) present in EBC samples from 30 healthy children and 40 children with asthma in the age group of 6-12 years.

RESULTS

Support vector machine analysis resulted in differentiating profiles based on asthma status. These proteolytic peptide patterns were not correlated to some well known (spirometry, exhaled nitric oxide) and more recently described exhaled markers (EBC pH, LTB₄). The more abundant proteins in EBC were identified as cytokeratins, albumin, actin, haemoglobin, lysozyme, dermcidin, and calgranulin B.

CONCLUSION

Although the exact role in the disease development or physiological state of the airways of the proteins described in the presented pattern is not clear at this moment, this is an important step in the search for exhaled biomarkers for asthma. This study shows that EBC contains proteins that are of interest for future non-invasive asthma diagnosis or follow-up.

Efficacy of two breath condensers

BACKGROUND

Examination of Exhaled Breath Condensate has been suggested to give information about inflammatory airway diseases.

OBJECTIVES

The aim was to compare efficacy and variability in gain of two commercially available exhaled breath condensers, ECoScreen and RTube in an in vitro set up.

METHODS

Test fluids containing myeloperoxidase (MPO) or human neutrophil lipocalin (HNL) in addition to saline and bovine serum albumin were nebulized and aerosols were transferred by a servo ventilator to either of the two condensers. Analyses of MPO, HNL, or chlorine were done by means of ELISA, RIA, or a modified adsorbed organic halogen technique (AOX), respectively.

RESULTS

Recoveries of HNL were higher when using ECoScreen than RTube (P<0.05). In contrast, there were no significant differences between the two condensers in recoveries of MPO or chlorine. The spread of data was wide regarding all tested compounds.

CONCLUSION

Variability in gain was large and ECoScreen was more efficacious then RTube in condensing the tested solutes of HNL, but not those of MPO or chlorine.

Targeted eicosanoids lipidomics of exhaled breath condensate in healthy subjects

BACKGROUND

Exhaled breath condensate collection is a non-invasive method of sampling the respiratory tract that can be repeated several times in a wide range of clinical settings. Quantitation of non-volatile compounds in the condensate requires highly sensitive analytical methods, e.g. mass spectrometry.

OBJECTIVE

To validate cross-platform measurements of eicosanoids using high performance liquid chromatography or gas chromatography coupled with mass spectrometry in exhaled breath condensate sampled from 58 healthy individuals.

METHODS

Twenty different eicosanoid compounds, representing major arachidonic acid lipoxygenation and cyclooxygenation pathways were measured using a stable isotope dilution method. We applied a free palmitic acid concentration as a surrogate marker for the condensate dilution factor.

RESULTS

Eicosanoids concentrations in the condensates were consistent with their content in other biological fluids. Prostaglandin E(2) was the most abundant mediator, represented by its stable metabolite tetranor-PGEM. Prostaglandin D(2) products were at low concentration, while hydroxyacids derived from lipoxygenation were abundant. 5-HETE was elevated in current tobacco smokers. Leukotriene B(4) has the highest concentration of all 5-LO products. 15-LO analogues of cysteinyl leukotrienes-eoxins were detectable and metabolized to eoxin E(4). Two main vascular prostanoids: prostacyclin and thromboxane B(2) were present as metabolites. A marker for non-enzymatic lipid peroxidation, 8-iso-PGF(2alpha) isoprostane was increased in smokers.

CONCLUSION

Presented targeted lipidomics analysis of exhaled breath condensate in healthy subjects justifies its application to investigation of inflammatory lung diseases. Measurements of non-volatile mediators of inflammation in the condensates might characterize disease-specific pathological mechanisms and responses to treatment.

Levels of cysteinyl-leukotrienes in exhaled breath condensate are not due to saliva contamination

BACKGROUND AND AIMS

Saliva contamination has been suggested to be a major contributor to levels of cysteinyl leukotrienes in exhaled breath condensate (EBC). The aim of this study was to compare the levels of cysteinyl-leukotrienes (CysLT) and alpha-amylase activity in EBC to induced sputum and saliva collected from the same subjects (asthmatics and control). We thereby aimed to find out whether saliva contamination could be a plausible explanation to the levels found in EBC or not.

METHODS

EBC, saliva and induced sputum were collected from 11 asthmatic and 19 healthy adults. These samples were analyzed for CysLT concentration and alpha-amylase activity.

RESULTS

No significant correlation was found between CysLT concentration and alpha-amylase activity in EBC, saliva or sputum. In addition, we show that the saliva contamination (measured as alpha-amylase activity) was negligible, as the relative amount of saliva CysLT was only 0.6% of that found in EBC. The amount of CysLT correlated between all three compartments (EBC, saliva and sputum), but no similar correlation was seen for the alpha-amylase activity in EBC compared to saliva and sputum. The levels of CysLT were higher in asthmatic patients compared to healthy controls in EBC, saliva and sputum.

CONCLUSION

We conclude that the amount of CysLT in EBC cannot be explained by saliva contamination. Please cite this paper as: Tufvesson E, van Weele LJ, Ekedahl H and Bjermer L. Levels of cysteinyl-leukotrienes in exhaled breath condensate are not due to saliva contamination.

Increased cysteinyl-leukotrienes and 8-isoprostane in exhaled breath condensate from systemic sclerosis patients

OBJECTIVES

SSc is a systemic CTD characterized by fibrosis in skin and internal organs. Interstitial lung disease is a frequent complication with fibrosis in the lung parenchyma. The fibrotic process is believed to be influenced by leukotrienes (LTs) and also by oxidative stress. The aim of this study was to investigate the amount of LTs and 8-isoprostane, a marker of oxidative stress, in exhaled breath condensate (EBC) from SSc patients.

METHODS

Twenty-two SSc patients with median disease duration of 2.1 years were investigated. Fifteen patients had lcSSc, four patients had dcSSc and three patients only fulfilled criteria for limited SSc. Sixteen healthy controls were enrolled. Cysteinyl-LTs (CysLTs), LTB4 and 8-isoprostane were measured in EBC with EIA and related to the radiologic extent of pulmonary fibrosis.

RESULTS

Compared with controls, SSc patients displayed higher median (interquartile range) CysLT [6.1 (5.3-6.8) vs 4.9 (3.7-6.3) pg/ml; P=0.040], 8-isoprostane [0.23 (0.20-0.46) vs 0.19 (0.12-0.20) pg/ml; P=0.0020], but similar levels of LTB4 [0.70 (0.50-0.83) vs 0.60 (0.42-0.70) pg/ml]. CysLT correlated to LTB4, while 8-isoprostane did not correlate to any of the LTs. None of the biomarkers measured in EBC correlated to radiologic findings.

CONCLUSION

Increased levels of CysLT and 8-isoprostane in EBC from patients with SSc reflect the inflammatory pattern involving LTs as well as oxidative stress. These findings may indicate a possible non-invasive assessment of pulmonary involvement in SSc with a potential value for assessment of disease progress and therapy evaluation.

Biomarkers in asthma and allergic rhinitis

A biological marker (biomarker) is a physical sign or laboratory measurement that can serve as an indicator of biological or pathophysiological processes or as a response to a therapeutic intervention. An applicable biomarker possesses the characteristics of clinical relevance (sensitivity and specificity for the disease) and is responsive to treatment effects, in combination with simplicity, reliability and repeatability of the sampling technique. Presently, there are several biomarkers for asthma and allergic rhinitis that can be obtained by non-invasive or semi-invasive airway sampling methods meeting at least some of these criteria. In clinical practice, such biomarkers can provide complementary information to conventional disease markers, including clinical signs, spirometry and PC(20)methacholine or histamine. Consequently, biomarkers can aid to establish the diagnosis, in staging and monitoring of the disease activity/progression or in predicting or monitoring of a treatment response. Especially in (young) children, reliable, non-invasive biomarkers would be valuable. Apart from diagnostic purposes, biomarkers can also be used as (surrogate) markers to predict a (novel) drug's efficacy in target populations. Therefore, biomarkers are increasingly applied in early drug development. When implementing biomarkers in clinical practice or trials of asthma and allergic rhinitis, it is important to consider the heterogeneous nature of the inflammatory response which should direct the selection of adequate biomarkers. Some biomarker sampling techniques await further development and/or validation, and should therefore be applied as a "back up" of established biomarkers or methods. In addition, some biomarkers or sampling techniques are less suitable for (very young) children. Hence, on a case by case basis, a decision needs to be made what biomarker is adequate for the target population or purpose pursued. Future development of more sophisticated sampling methods and quantification techniques, such as--omics and biomedical imaging, will enable detection of adequate biomarkers for both clinical and research applications.

Increased cytokines, chemokines and soluble adhesion molecules in exhaled breath condensate of asthmatic children

BACKGROUND

Airway inflammation in asthma is characterized by the production of cytokines, chemokines and soluble adhesion molecules. The assessment of these inflammatory biomarkers in exhaled breath condensate (EBC) is hampered by low detection rates. However, the use of a glass condenser system combined with a sensitive analytical technique may increase the possibility to assess these biomarkers in EBC in a reliable way.

OBJECTIVE

(1) To assess the detection rates of cytokines (IL-1alpha, -1beta, -2, -4, -5, -6, -10, -12p70, -13, -18, IFN-gamma, TNF-alpha), chemokines [MIP1alpha (CCL3), MIF, eotaxin (CCL11), RANTES (CCL5), IP10 (CXCL10), IL8 (CXCL8), MCP1] and soluble adhesion molecules [soluble intercellular adhesion molecule (sICAM), soluble vascular adhesion molecule (sVCAM)] in EBC of children with asthma and healthy control children; (2) To study the differences in the biomarker concentration between children with asthma and controls.

METHODS

Sixty children were included: 31 asthmatics (71% atopic) and 29 controls. Exhaled breath condensate was collected using a glass condenser system. The inflammatory markers (IM) were analysed using multiplex immunoassay technology.

RESULTS

Detection percentages of cytokines, chemokines and adhesion molecules ranged from 94% to 100%, except for eotaxin (CCL11) and RANTES (CCL5) (detection rates of 10% and 45% in healthy controls, respectively). The intra-subject variability of biomarkers in EBC in the group as a whole ranged from 5.2% to 35.0%. In asthmatics, the levels of cytokines (IL-2, -4, -5, -6, -13, IFN-gamma), chemokines (MIP1alpha [CCL3], MIF, RANTES [CCL5], IP10 [CXCL10], IL8 [CXCL8], MCP1) and adhesion molecules (sICAM, sVCAM) were significantly increased in comparison with controls (P<0.05).

CONCLUSION

If collected with a glass condenser and analysed by multiplex immunoassay technology, cytokines, chemokines and soluble adhesion molecules can be reliably demonstrated in EBC of children. Most of these IM were elevated in EBC of asthmatics compared with controls.

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.

Comparative analysis of selected exhaled breath biomarkers obtained with two different temperature-controlled devices

Background

The collection of exhaled breath condensate (EBC) is a suitable and non-invasive method for evaluation of airway inflammation. Several studies indicate that the composition of the condensate and the recovery of biomarkers are affected by physical characteristics of the condensing device and collecting circumstances. Additionally, there is an apparent influence of the condensing temperature, and often the level of detection of the assay is a limiting factor. The ECoScreen2 device is a new, partly single-use disposable system designed for studying different lung compartments.

Methods

EBC samples were collected from 16 healthy non-smokers by using the two commercially available devices ECoScreen2 and ECoScreen at a controlled temperature of -20°C. EBC volume, pH, NOx, LTB₄, PGE₂, 8-isoprostane and cys-LTs were determined.

Results

EBC collected with ECoScreen2 was less acidic compared to ECoScreen. ECoScreen2 was superior concerning condensate volume and detection of biomarkers, as more samples were above the detection limit (LTB₄ and PGE₂) or showed higher concentrations (8-isoprostane). However, NOx was detected only in EBC sampled by ECoScreen.

Conclusion

ECoScreen2 in combination with mediator specific enzyme immunoassays may be suitable for measurement of different biomarkers. Using this equipment, patterns of markers can be assessed that are likely to reflect the complex pathophysiological processes in inflammatory respiratory disease.

Exhaled cysteinyl-leukotrienes and 8-isoprostane in patients with asthma and their relation to clinical severity

BACKGROUND

Collection of exhaled breath condensate (EBC) is a safe, non-invasive method to collect droplets of the airway surface liquid and measure mediators of airway inflammation and oxidative stress, such as cysteinyl-leukotrienes (cys-LTs) and 8-isoprostane.

OBJECTIVE

The aim of our study was to investigate baseline values of inflammatory lipid mediators in EBC and their relation to asthma severity.

METHODS

Nineteen healthy subjects, 16 mild, 12 moderate and 15 severe asthmatics were studied. All subjects attended a clinic visit for spirometry and EBC collection. The concentrations of exhaled cys-LTs and 8-isoprostane were measured by means of specific enzyme immunoassays.

RESULTS

8-isoprostane levels were significantly increased in mild (49.1+/-5.2 pg/mL, p<0.001), moderate (49.7+/-5.2 pg/mL, p<0.001) and severe asthmatics (77.7+/-7.3 pg/mL, p<0.001), compared to healthy controls (16.4+/-1.6 pg/mL). Moreover, 8-isoprostane levels were significantly higher in severe compared to mild and moderate asthmatics (p<0.01). Cys-LT levels were significantly higher in moderate (34.6+/-4.4 pg/mL, p<0.05) and severe asthmatics (47.9+/-6.0 pg/mL, p<0.001), while no significant difference was found between healthy controls and mild asthmatics. 8-isoprostane levels in EBC of asthmatics strongly correlated with cys-LT levels (r=0.61, p<0.0001).

CONCLUSIONS

8-isoprostane and cys-LT are detectable in EBC of healthy subjects and their levels progressively increase in asthmatic patients according to disease severity. The correlation found between these two lipid mediators indicating a link between oxidative stress and airway inflammation.

Diagnosis and management of work-related asthma: American College Of Chest Physicians Consensus Statement

BACKGROUND

A previous American College of Chest Physicians Consensus Statement on asthma in the workplace was published in 1995. The current Consensus Statement updates the previous one based on additional research that has been published since then, including findings relevant to preventive measures and work-exacerbated asthma (WEA).

METHODS

A panel of experts, including allergists, pulmonologists, and occupational medicine physicians, was convened to develop this Consensus Document on the diagnosis and management of work-related asthma (WRA), based in part on a systematic review, that was performed by the University of Alberta/Capital Health Evidence-Based Practice and was supplemented by additional published studies to 2007.

RESULTS

The Consensus Document defined WRA to include occupational asthma (ie, asthma induced by sensitizer or irritant work exposures) and WEA (ie, preexisting or concurrent asthma worsened by work factors). The Consensus Document focuses on the diagnosis and management of WRA (including diagnostic tests, and work and compensation issues), as well as preventive measures. WRA should be considered in all individuals with new-onset or worsening asthma, and a careful occupational history should be obtained. Diagnostic tests such as serial peak flow recordings, methacholine challenge tests, immunologic tests, and specific inhalation challenge tests (if available), can increase diagnostic certainty. Since the prognosis is better with early diagnosis and appropriate intervention, effective preventive measures for other workers with exposure should be addressed.

CONCLUSIONS

The substantial prevalence of WRA supports consideration of the diagnosis in all who present with new-onset or worsening asthma, followed by appropriate investigations and intervention including consideration of other exposed workers.

Prostacyclin analogs stimulate VEGF production from human lung fibroblasts in culture

Prostacyclin is a short-lived metabolite of arachidonic acid that is produced by several cells in the lung and prominently by endothelial cells. It increases intracellular cAMP levels activating downstream signaling thus regulating vascular mesenchymal cell functions. The alveolar wall contains a rich capillary network as well as a population of mesenchymal cells, i.e., fibroblasts. The current study evaluated the hypothesis that prostacyclin may mediate signaling between endothelial and mesenchymal cells in the alveolar wall by assessing the ability of prostacyclin analogs to modulate fibroblast release of VEGF. To accomplish this study, human lung fibroblasts were cultured in routine culture on plastic support and in three-dimensional collagen gels with or without three prostacyclin analogs, carbaprostacyclin, iloprost, and beraprost, and the production of VEGF was evaluated by ELISA and quantitative real-time PCR. Iloprost and beraprost significantly stimulated VEGF mRNA levels and protein release in a concentration-dependent manner. These effects were blocked by the adenylate cyclase inhibitor SQ-22536 and by the protein kinase A (PKA) inhibitor KT-5720 and were reproduced by a direct PKA activator but not by an activator of exchange protein directly activated by cAMP (Epac), indicating that cAMP-activated PKA signaling mediated the effect. Since VEGF serves to maintain the pulmonary microvasculature, the current study suggests that prostacyclin is part of a bidirectional signaling network between the mesenchymal and vascular cells of the alveolar wall. Prostacyclin analogs, therefore, have the potential to modulate the maintenance of the pulmonary microcirculation by driving the production of VEGF from lung fibroblasts.

Exhaled breath condensate: an overview

Exhaled breath condensate (EBC) is a promising source of biomarkers of lung disease. EBC is not a biomarker, but rather a matrix in which biomarkers may be identified, in that way equivalent to blood, sweat, tears, urine, and saliva. EBC may be thought of either as a body fluid or as a condensate of exhaled gas. The field of EBC research has advanced gradually, with the debates surrounding an emerging field helping to pose questions and gradually leading to answers. Conscientious assay technique will likely find in EBC any substance of substantially high enough concentration in the airway lining fluid.

Influence of condensing equipment and temperature on exhaled breath condensate pH, total protein and leukotriene concentrations

BACKGROUND

Exhaled breath condensate analysis is an attractive but still not fully standardised method for investigating airway pathology. Adherence of biomarkers to various condensing surfaces and changes in condensing temperature has been considered to be responsible for the variability of the results. Our aims were to compare the efficacy of different types of condensers and to test the influence of condensing temperature on condensate composition.

METHODS

Breath condensates from 12 healthy persons were collected in two settings: (1) by using three condensers of different type (EcoScreen, R-Tube, Anacon) and (2) by using R-Tube condenser either cooled to -20 or -70 degrees C. Condensate pH at standardised CO(2) level was determined; protein content was measured by the Bradford method and leukotrienes by EIA.

RESULTS

Breath condensates collected using EcoScreen were more alkaline (6.45+/-0.20 vs. 6.19+/-0.23, p<0.05 and 6.10+/-0.26, p<0.001) and contained more protein (3.89+/-2.03 vs. 2.65+/-1.98, n.s. and 1.88+/-1.99 microg/ml, p<0.004) as compared to the other devices. Only parameters obtained with R-Tube and Anacon correlated. Condensing temperature affected condensate pH (5.99+/-0.20 at -20 degrees C and 5.82+/-0.07 at -70 degrees C, p<0.05) but not protein content. Leukotriene B(4) was not found in any sample and cysteinyl-leukotriene was not found in condensates collected with R-Tube or Anacon.

CONCLUSION

Condenser type influences sample pH, total protein content and cysteinyl-leukotriene concentration. Condensing temperature influences condensate pH but not total protein content. These results suggest that adherence of the biomarkers to condenser surface and condensing temperature may play a role but does not fully explain the variability of EBC biomarker levels.

Methods used in clinical development of novel anti-asthma therapies

In recent years, it has become increasingly important to get as much as possible information on clinical efficacy already in the early phases of drug development. For proof of concept (POC) studies testing novel anti-inflammatory drugs in asthma, there are several validated exacerbation models, inducing various aspects of the airway inflammation and airway responsiveness. The choice of the appropriate asthma model depends on the drug's targets within the inflammatory process. For adequate assessment of the drug's anti-inflammatory potential, it is crucial to choose adequate (surrogate) biomarkers. Ideally, these should include measures of airway response, central and peripheral airway inflammation and airway hyperresponsiveness. Overall, there are validated non-invasive sampling techniques for the measurement of inflammatory markers in asthma that can be applied as outcome parameters in early clinical trials. If adequately implemented, these measurements can provide early indication of proof of pharmacological and potential therapeutic efficacy-even in first administration to humans.

The allergic cascade: review of the most important molecules in the asthmatic lung

Asthma is the most common chronic inflammatory disorder of the airways among children. It is a complex clinical disease characterized by airway obstruction, airway inflammation and airway hyperresponsiveness to a variety of stimuli. The development of allergic asthma exists of three phases, namely the induction phase, the early-phase asthmatic reaction (EAR) and the late-phase asthmatic reaction (LAR). Each phase is characterized by the production and interplay of various cell-derived mediators. In the induction phase, T helper cytokines are important in the development of asthma. Most important mediators in the EAR are preformed mediators, newly synthesized lipid mediators and cytokines that are produced by mast cells. During the LAR, inflammatory molecules are produced by various cell types, such as eosinophils, neutrophils, T cells, macrophages, dendritic cells, and structural cells. Chronical inflammation leads to structural changes of the airway architecture. In this review, the most important mediators involved in the induction phase, the early-phase and late-phase asthmatic reaction are discussed.

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.

Chlorine in breath condensate--a measure of airway affection in pollinosis?

BACKGROUND

Infiltration of inflammatory cells in bronchial mucosa and glandular hypersecretion are hallmarks of asthma. It has been postulated that exhaled breath condensate (EBC) mirrors events in epithelial lining fluid of airways, such as presence of local inflammation as well as glandular hypersecretion. It is also well known that eosinophil cationic protein (ECP) and cysteinyl-leukotrienes (cys-LT) are released by circulating inflammatory cells when triggered by antigen stimulation in asthma patients.

OBJECTIVES

The aim of this study was to evaluate whether chlorine and/or cys-LT in EBC would reflect changes of exposure of airborne pollen in patients with asthma.

METHODS

EBC and serum were collected from 23 patients with allergic asthma during a pollen season and repeated 5 months later during a period with no aeroallergens. Chlorine was measured by means of a sensitive coulometric technique and cys-LT by an EIA technique. Serum ECP was measured and lung function tests were performed and symptoms noted during both occasions.

RESULTS

Significantly higher concentrations of chlorine in EBC (p = 0.007) and ECP in serum (p = 0.003) were found during the pollen season compared to post-season. Chlorine levels tended to be higher in patients who reported of chest symptoms compared to those who denied symptoms during the pollen season (p = 0.06). Areas under the receiver-operated characteristic curves (AUC(ROC)) were compared and similar discriminative power to identify exacerbations of asthma was recorded by chlorine in EBC (range 0.67-0.78) and ECP in serum (range 0.64-0.78).

CONCLUSION

It is concluded that chlorine in EBC and ECP in serum decreased significantly post-season, and this is suggested to mirror the decrement in airborne antigen. It is furthermore proposed that chlorine in EBC and ECP in serum tend to have a similar capacity to identify seasonal variations in airborne pollen in patients with asthma.