Ion trap liquid chromatography/tandem mass spectrometry analysis of leukotriene B4 in exhaled breath condensate

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.

Simultaneous Quantitation of Lipid Biomarkers for Inflammatory Bowel Disease Using LC-MS/MS

Eicosanoids are key mediators and regulators of inflammation and oxidative stress that are often used as biomarkers for severity and therapeutic responses in various diseases. We here report a highly sensitive LC-MS/MS method for the simultaneous quantification of at least 66 key eicosanoids in a widely used murine model of colitis. Chromatographic separation was achieved with Shim-Pack XR-ODSIII, 150 × 2.00 mm, 2.2 µm. The mobile phase was operated in gradient conditions and consisted of acetonitrile and 0.1% acetic acid in water with a total flow of 0.37 mL/min. This method is sensitive, with a limit of quantification ranging from 0.01 to 1 ng/mL for the various analytes, has a large dynamic range (200 ng/mL), and a total run time of 25 min. The inter- and intraday accuracy (85-115%), precision (≥85%), and recovery (40-90%) met the acceptance criteria per the US Food and Drug Administration guidelines. This method was successfully applied to evaluate eicosanoid metabolites in mice subjected to colitis versus untreated, healthy control mice. In summary, we developed a highly sensitive and fast LC-MS/MS method that can be used to identify biomarkers for inflammation and potentially help in prognosis of the disease in inflammatory bowel disease (IBD) patients, including the response to therapy.

Compensate for or Minimize Matrix Effects? Strategies for Overcoming Matrix Effects in Liquid Chromatography-Mass Spectrometry Technique: A Tutorial Review

In recent decades, mass spectrometry techniques, particularly when combined with separation methods such as high-performance liquid chromatography, have become increasingly important in pharmaceutical, bio-analytical, environmental, and food science applications because they afford high selectivity and sensitivity. However, mass spectrometry has limitations due to the matrix effects (ME), which can be particularly marked in complex mixes, when the analyte co-elutes together with other molecules, altering analysis results quantitatively. This may be detrimental during method validation, negatively affecting reproducibility, linearity, selectivity, accuracy, and sensitivity. Starting from literature and own experience, this review intends to provide a simple guideline for selecting the best operative conditions to overcome matrix effects in LC-MS techniques, to obtain the best result in the shortest time. The proposed methodology can be of benefit in different sectors, such as pharmaceutical, bio-analytical, environmental, and food sciences. Depending on the required sensitivity, analysts may minimize or compensate for ME. When sensitivity is crucial, analysis must try to minimize ME by adjusting MS parameters, chromatographic conditions, or optimizing clean-up. On the contrary, to compensate for ME analysts should have recourse to calibration approaches depending on the availability of blank matrix. When blank matrices are available, calibration can occur through isotope labeled internal standards and matrix matched calibration standards; conversely, when blank matrices are not available, calibration can be performed through isotope labeled internal standards, background subtraction, or surrogate matrices. In any case, an adjusting of MS parameters, chromatographic conditions, or a clean-up are necessary.

Lipidomic methodologies for biomarkers of chronic inflammation in nutritional research: ω-3 and ω-6 lipid mediators

The evolutionary history of hominins has been characterized by significant dietary changes, which include the introduction of meat eating, cooking, and the changes associated with plant and animal domestication. The Western pattern diet has been linked with the onset of chronic inflammation, and serious health problems including obesity, metabolic syndrome, and cardiovascular diseases. Diets enriched with ω-3 marine PUFAs have revealed additional improvements in health status associated to a reduction of proinflammatory ω-3 and ω-6 lipid mediators. Lipid mediators are produced from enzymatic and non-enzymatic oxidation of PUFAs. Interest in better understanding the occurrence of these metabolites has increased exponentially as a result of the growing evidence of their role on inflammatory processes, control of the immune system, cell signaling, onset of metabolic diseases, or even cancer. The scope of this review has been to highlight the recent findings on: a) the formation of lipid mediators and their role in different inflammatory and metabolic conditions, b) the direct use of lipid mediators as antiinflammatory drugs or the potential of new drugs as a new therapeutic option for the synthesis of antiinflammatory or resolving lipid mediators and c) the impact of nutritional interventions to modulate lipid mediators synthesis towards antiinflammatory conditions. In a second part, we have summarized methodological approaches (Lipidomics) for the accurate analysis of lipid mediators. Although several techniques have been used, most authors preferred the combination of SPE with LC-MS. Advantages and disadvantages of each method are herein addressed, as well as the main LC-MS difficulties and challenges for the establishment of new biomarkers and standardization of experimental designs, and finally to deepen the study of mechanisms involved on the inflammatory response.

LC-MS/MS assay for the simultaneous determination of tocopherols, polyunsaturated fatty acids and their metabolites in human plasma and serum

The role of vitamin E in both enzymatic and free radical-dependent metabolism of polyunsaturated fatty acids (PUFAs) has been well demonstrated. This study proposed a new LC-MS/MS method to quantify the main vitamin E forms, their metabolites and main PUFA species in human blood, since, at present, there are not procedures able to simultaneously determine these two classes of compounds. After the optimization of sample treatment and reverse-phase separation conditions, tandem mass spectrometry detection was evaluated experimenting both positive and negative electrospray ionisation modes. The procedure was also preliminarily adapted to assess five arachidonic acid-derived eicosanoids that could be under the influence of vitamin E function, such as LTB4 (leukotriene B4), 20-HETE (20-hydroxyeicosatetraenoic acid) and their ω-oxidation metabolites. After the validation study, the performance characteristics were confirmed analysing a certified reference material (SRM^® 1950 - frozen human plasma by NIST). Finally, an application of the method in the analysis of lipid abnormalities of chronic kidney disease patients was shown.

Quantification of eicosanoids and their metabolites in biological matrices: a review

The quantification of eicosanoids and their metabolites in biological samples remain an analytical challenge, even though a number of methodologies/techniques have been developed. The major difficulties encountered are related to the oxidation of eicosanoids and their low quantities in biological matrices. Among the known methodologies, liquid chromatography-mass spectrometry (LC-MS/MS) is the standard method for eicosanoid quantification in biological samples. Recently advances have improved the ability to identify and simultaneous quantitate eicosanoids in biological matrices. The present article reviews the quantitative analysis of eicosanoids in different biological matrices by LC and ultra performance liquid chromatography (UPLC)-MS/MS and discusses important aspects to be considered during the collection, sample preparation and the generation of calibration curves required for eicosanoid analysis.

Detection of Lipid Mediators of Inflammation in the Human Tear Film

PURPOSE

Lipid mediators of inflammation are a group of signaling molecules produced by various cells under physiological conditions and modulate the inflammatory process during various pathologic conditions. Although eicosanoids and F2-isoprostanes are recognized lipid mediators of inflammation, there is no consensus yet on the extraction and mass spectrometry (MS) method for their analysis in individual human tear samples. Thus, the aim of this study was to develop an optimal method for extraction of lipid mediators of inflammation in the tear film and evaluate MS techniques for their analysis.

METHODS

Basal tears were collected from each eye of 19 subjects using glass microcapillaries. Lipid extraction was performed using either varying concentrations of acidified methanol, a modified Folch method, or solid-phase extraction. Initially, an untargeted analysis of the extracts was performed using SCIEX TripleTOF 5600 mass spectrometer to identify any lipid mediators of inflammation (eicosanoids) and later a targeted analysis was performed using the SCIEX 6500 Qtrap to identify and quantify prostaglandins and isoprostanes. Mass spectra and chromatograms were analyzed using Peakview, XCMS, and Multiquant software.

RESULTS

Prostaglandins and isoprostanes were observed and quantified using the Qtrap mass spectrometer under multiple reaction monitoring (MRM) mode after solid-phase extraction. Extraction with acidified methanol along with the Folch method produced cleaner spectra during MS with the Triple time of flight (TOF) mass spectrometer. Lipid mediators of inflammation were not observed in any of the tear samples using the Triple TOF mass spectrometer.

CONCLUSIONS

Solid-phase extraction may be the method of choice for extraction of prostaglandins and isoprostanes in low volumes of tears. The SCIEX Qtrap 6500 in MRM mode may be suitable to identify and quantify similar lipid mediators of inflammation.

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."

Simultaneous LC-MS/MS analysis of eicosanoids and related metabolites in human serum, sputum and BALF

The differences among individual eicosanoids in eliciting different physiological and pathological responses are largely unknown because of the lack of valid and simple analytical methods for the quantification of individual eicosanoids and their metabolites in serum, sputum and bronchial alveolar lavage fluid (BALF). Therefore, a simple and sensitive LC-MS/MS method for the simultaneous quantification of 34 eicosanoids in human serum, sputum and BALF was developed and validated. This method is valid and sensitive with a limit of quantification ranging from 0.2 to 3 ng/mL for the various analytes, and has a large dynamic range (500 ng/mL) and a short run time (25 min). The intra- and inter-day accuracy and precision values met the acceptance criteria according to US Food and Drug Administration guidelines. Using this method, detailed eicosanoid profiles were quantified in serum, sputum and BALF from a pilot human study. In summary, a reliable and simple LC-MS/MS method to quantify major eicosanoids and their metabolites was developed and applied to quantify eicosanoids in human various fluids, demonstrating its suitability to assess eicosanoid biomarkers in human clinical trials.

Determining the presence of asthma-related molecules and salivary contamination in exhaled breath condensate

Background

Researchers investigating lung diseases, such as asthma, have questioned whether certain compounds previously reported in exhaled breath condensate (EBC) originate from saliva contamination. Moreover, despite its increasing use in ‘omics profiling studies, the constituents of EBC remain largely uncharacterized. The present study aims to define the usefulness of EBC in investigating lung disease by comparing EBC, saliva, and saliva-contaminated EBC using targeted and untargeted mass spectrometry and the potential of metabolite loss from adsorption to EBC sample collection tubes.

Methods

Liquid chromatography mass spectrometry (LC-MS) was used to analyze samples from 133 individuals from three different cohorts. Levels of amino acids and eicosanoids, two classes of molecules previously reported in EBC and saliva, were measured using targeted LC-MS. Cohort 1 was used to examine contamination of EBC by saliva. Samples from Cohort 1 consisted of clean EBC, saliva-contaminated EBC, and clean saliva from 13 healthy volunteers; samples were analyzed using untargeted LC-MS. Cohort 2 was used to compare eicosanoid levels from matched EBC and saliva collected from 107 asthmatic subjects. Samples were analyzed using both targeted and untargeted LC-MS. Cohort 3 samples consisted of clean-EBC collected from 13 subjects, including smokers and non-smokers, and were used to independently confirm findings; samples were analyzed using targeted LC-MS, untargeted LC-MS, and proteomics. In addition to human samples, an in-house developed nebulizing system was used to determine the potential for EBC samples to be contaminated by saliva.

Results

Out of the 400 metabolites detected in both EBC and saliva, 77 were specific to EBC; however, EBC samples were concentrated 20-fold to achieve this level of sensitivity. Amino acid concentrations ranged from 196 pg/mL – 4 μg/mL (clean EBC), 1.98 ng/mL – 6 μg/mL (saliva-contaminated EBC), and 13.84 ng/mL – 1256 mg/mL (saliva). Eicosanoid concentration ranges were an order of magnitude lower; 10 pg/mL – 76.5 ng/mL (clean EBC), 10 pg/mL – 898 ng/mL (saliva-contaminated EBC), and 2.54 ng/mL – 272.9 mg/mL (saliva). Although the sample size of the replication cohort (Cohort 3) did not allow for statistical comparisons, two proteins and 19 eicosanoids were detected in smoker vs. non-smoker clean-EBC.

Conclusions

We conclude that metabolites are present and detectable in EBC using LC-MS; however, a large starting volume of sample is required.

Electronic supplementary material

The online version of this article (doi:10.1186/s12931-017-0538-5) contains supplementary material, which is available to authorized users.

Determination of urinary levels of leukotriene B(4) using ad highly specific and sensitive methodology based on automatic MEPS combined with UHPLC-PDA analysis

Leukotriene B4 (LTB4) is a potent mediator of inflammation and plays a key function in the pathophysiology of chronic asthma. Detectable urinary levels of LTB4, arises from the activation of leukotriene pathways. In this study an ultra-fast, selective and sensitive analytical method based on semi-automatic microextraction by packed sorbents (MEPS) technique, using a new digitally controlled syringe (eVol®) combined with ultra-high pressure liquid chromatography (UHPLC), is proposed for the measurement of urinary LTB4 (U-LTB4) levels in a group of asthmatic patients (APs) and healthy controls (CTRL). Important parameters affecting MEPS performance, namely sorbent type, number of extraction cycles (extract-discard) and elution volume, were evaluated. The optimal experimental conditions among those investigated for the quantification of U-LTB4 in urine samples were as follows: porous graphitic carbon sorbent (PGC), 10 extractions cycle (10×250 μL of sample) and LTB4 elution with 100 μL of acetonitrile. The UHPLC optimum conditions resulted in a mobile phase consisting of 95% (v/v) of acid aqueous solution (v/v), and acetonitrile 5% (v/v); flow rate of 500 µL/min, and a column temperature of 37±0.1 °C. Under optimized conditions the proposed method exhibit good selectivity and sensitivity LOD (0.37 ng/mL) and LOQ (1.22 ng/mL). The recovery ranging from 86.4 to 101.1% for LTB4, with relative standard deviations (% RSD) no larger than 5%. In addition, the method also afforded good results in terms of linearity (r(2)>0.995) within the established concentration range, with a residual deviation for each calibration point below 6%, and intra- and inter-day repeatability in urine samples with RSD values lower than 4 and 5%, respectively. The application of the method to urine samples revealed a tendency towards the increased urinary LTB4 levels in APs (5.42±0.17 ng/mL) when compared to those of CTRL group (from ND to 1.9 ng/mL). Urinary measurement of LTB4 may be an interesting and non-invasive option to assess control of asthma.

Liquid chromatography-mass spectrometry measurement of leukotrienes in asthma and other respiratory diseases

Leukotrienes (LTs), including cysteinyl-LTs (LTC4, LTD4 and LTE4) and LTB4, are potent inflammatory lipid mediators which have been involved in the pathophysiology of respiratory diseases. LC-MS/MS techniques for measuring LT concentrations in sputum supernatants, serum, urine and exhaled breath condensate (EBC) have been developed. In asthmatic adults, reported LTB4 and LTE4 concentrations in sputum range from 79 to 7,220 pg/ml and from 11.9 to 891 pg/ml, respectively. Data on sputum LT concentrations in healthy subjects are not available. In EBC, reported LTE4 concentrations range from 38 to 126 pg/ml (95% CI) in adult asthma patients and from 34 to 48 pg/ml in healthy subjects. LTB4 concentrations in EBC range from 175 to 315 pg/ml (interquartile range) in asthmatic children, and from 25 to 245 pg/ml in healthy children. Enabling an accurate quantitative assessment of LTs in biological fluids, LC-MS/MS techniques provide a valuable tool for exploring the pathophysiological role of LTs in respiratory disease and might be useful for assessing the effects of therapeutic intervention. This review presents the analytical aspects of the LC-MS/MS techniques for measuring LT concentrations in biological fluids and discusses their potential utility for the assessment of airway inflammation and monitoring of pharmacological treatment in patients with asthma phenotypes and other respiratory diseases.

Liquid chromatography-tandem mass spectrometry for the analysis of eicosanoids and related lipids in human biological matrices: a review

Today, there is an increasing number of liquid chromatography tandem-mass spectrometric (LC-MS/MS) methods for the analysis of eicosanoids and related lipids in biological matrices. An overview of currently applied LC-MS/MS methods is given with attention to sample preparation strategies, chromatographic separation including ultra high performance liquid chromatography (UHPLC) and chiral separation, as well as to mass spectrometric detection using multiple reacting monitoring (MRM). Further, the application in recent clinical research is reviewed with focus on preanalytical aspects prior to LC-MS/MS analysis as well as applications in major diseases of Western civilization including respiratory diseases, diabetes, cancer, liver diseases, atherosclerosis, and neurovascular diseases.

Using high-performance liquid chromatography with UV detector to quantify exhaled leukotriene B4 level in nonatopic adults

This study aimed to evaluate the feasibility of the chemical method to analyze exhaled breath condensate (EBC) leukotriene B4 (LTB4) level in humans. High-performance liquid chromatography with a UV detector was applied to quantify the inflammatory biomarker. The LTB4 concentration in the concentrated pooled EBC samples was 1.19 ng/μL, and the average LTB4 concentration of each EBC sample was 15.38 ng/μL. This analytical technique was feasible to evaluate the levels of inflammatory mediators such as LTB4 in human EBCs without any complicated sample pretreatment processes.

Application of metabolomics approaches to the study of respiratory diseases

Metabolomics is the global unbiased analysis of all the small-molecule metabolites within a biological system, under a given set of conditions. These methods offer the potential for a holistic approach to clinical medicine, as well as improving disease diagnosis and understanding of pathological mechanisms. Respiratory diseases including asthma and chronic obstructive pulmonary disorder are increasing globally, with the latter predicted to become the third leading cause of global mortality by 2020. The root causes for disease onset remain poorly understood and no cures are available. This review presents an overview of metabolomics followed by in-depth discussion of its application to the study of respiratory diseases, including the design of metabolomics experiments, choice of clinical material collected and potentially confounding experimental factors. Particular challenges in the field are presented and placed within the context of the future of the applications of metabolomics approaches to the study of respiratory diseases.

Bronchial and alveolar nitric oxide in exercise-induced bronchoconstriction in asthmatic children

BACKGROUND

Epidemiological studies have shown an association between the severity of exercise-induced bronchoconstriction (EIB) and fractional exhaled nitric oxide at the flow of 50 mL/s (FeNO(50)). However, no study has assessed the correlation between alveolar production (C(alv)) and bronchial flux (J(NO)) of nitric oxide (NO) and EIB in asthmatic children.

OBJECTIVE

To identify the relationship between severity of EIB and bronchial or alveolar nitric oxide.

METHODS

Our group included 36 allergic children with intermittent asthma. The EIB was determined by a standard exercise challenge and the severity was expressed as the maximum change in percentage from the baseline value of lung function (ΔFEV(1)%, ΔFEF(25-75)%) after exercising. A chemiluminescence analyser at multiple flows was used to calculate FeNO(50), J(NO) and C(alv,) which reflect large airways, J(NO) and alveolar concentration of NO respectively.

RESULTS

Sixteen (44.4%) children presented a ∆FEV(1) ≥ 10%, eight (22.2%) had ∆FEV(1) ≥ 15% and nine (25%) children had a ∆FEF(25-75) ≥ 26%. A significant correlation was observed between severity of EIB and FeNO(50) , J(NO) and C(alv.) EIB was significantly more severe in children sensitive to indoor allergens compared with outdoor allergens only (P = 0.014); those children showed also higher levels of C(alv) (P = 0.003) and of J(NO) (P = 0.044).

CONCLUSIONS AND CLINICAL RELEVANCE

Our results suggest that inflammation is present in the central and peripheral airways and that it is associated with the severity of EIB. Clinicaltrials.gov NCT00952835.

Exhaled breath condensate pH in patients with cystic fibrosis

OBJECTIVE AND DESIGN

Exhaled breath condensate (EBC) pH has been proposed as a useful, non-invasive marker of airway inflammation in pulmonary diseases. In this study we tested whether cystic fibrosis (CF) is associated with acidification of EBC, when pH is assessed by the CO(2) gas standardization method.

METHODS

EBC was collected using two different devices (EcoScreen and R-Tube) in 46 stable CF patients during routine clinical visits and in 28 healthy controls.

RESULTS

Mean EBC pH in CF patients and in healthy controls was similar (EcoScreen: CF patients: 6.38 ± 0.03 versus controls: 6.39 ± 0.03, p = 0.699; R-tube: CF patients: 5.94 ± 0.04 versus controls: 6.02 ± 0.03, p = 0.159). Inflammatory cell counts in spontaneously expectorated sputum obtained in a subset of patients (n = 20) showed no correlation with pH values. EBC samples collected with the R-tube were more acidic than those collected with the EcoScreen device (p < 0.001).

CONCLUSIONS

Our data suggest that EBC pH does not discriminate between healthy controls and those with CF disease indicating that the clinical applicability of EBC pH measurements for assessing airway inflammation in CF is limited.

Fractionated breath condensate sampling: H(2)O(2) concentrations of the alveolar fraction may be related to asthma control in children

Background

Asthma is a chronic inflammatory disease of the airways but recent studies have shown that alveoli are also subject to pathophysiological changes. This study was undertaken to compare hydrogen peroxide (H₂O₂) concentrations in different parts of the lung using a new technique of fractioned breath condensate sampling.

Methods

In 52 children (9-17 years, 32 asthmatic patients, 20 controls) measurements of exhaled nitric oxide (FE_NO), lung function, H₂O₂ in exhaled breath condensate (EBC) and the asthma control test (ACT) were performed. Exhaled breath condensate was collected in two different fractions, representing mainly either the airways or the alveoli. H₂O₂ was analysed in the airway and alveolar fractions and compared to clinical parameters.

Results

The exhaled H₂O₂ concentration was significantly higher in the airway fraction than in the alveolar fraction comparing each single pair (p = 0.003, 0.032 and 0.040 for the whole study group, the asthmatic group and the control group, respectively). Asthma control, measured by the asthma control test (ACT), correlated significantly with the H₂O₂ concentrations in the alveolar fraction (r = 0.606, p = 0.004) but not with those in the airway fraction in the group of children above 12 years. FE_NO values and lung function parameters did not correlate to the H₂O₂ concentrations of each fraction.

Conclusion

The new technique of fractionated H₂O₂ measurement may differentiate H₂O₂ concentrations in different parts of the lung in asthmatic and control children. H₂O₂ concentrations of the alveolar fraction may be related to the asthma control test in children.

Exhaled breath condensate (EBC) biomarkers in pulmonary fibrosis

The diffuse parenchymal lung diseases (DPLDs) are a group of clinicopathological entities which have recently undergone reclassification. The commonest type of idiopathic DPLD is interstitial pulmonary fibrosis (PF), which is histologically characterized by usual interstitial pneumonia (UIP), with inflammatory changes in the alveoli and subsequent collagen deposition. A similar type of inflammatory change can also be seen with connective tissue disorders. Many mediators are involved, but it is difficult to study these in a non-invasive manner in patients. The aim of the study detailed in this paper was to investigate inflammatory and oxidative stress biomarkers in PF and correlate these with lung function. 20 PF patients and 20 controls participated in the study. Exhaled breath condensate (EBC) was collected over 10 min using a refrigerated condenser, after fractional exhaled nitric oxide (FeNO) and carbon monoxide (eCO) measurement. EBC total nitrogen oxides (NOx), hydrogen peroxide (H(2)O(2)), 8-isoprostane (8-iso), 3-nitrotyrosine (3-NT), pH and total protein were measured. EBC biomarkers were significantly raised in PF compared with controls: EBC 3-NT (2.5 (0.7-8.9) versus 0.3 (0.1-1.1) ng ml(-1), p = 0.02); pH (7.6 ± 0.3 versus 7.4 ± 0.2, p = 0.004); 8-isoprostane (0.2 (0.1-0.4) versus 0.08 (0.04-0.2) ng ml(-1), p = 0.04) and total protein (24.7 ± 21.1 versus 10.7 ± 7.0 µg ml(-1), p = 0.008). FeNO and eCO were also increased (8.6 (7.1-10.4) versus 6.6 (5.6-7.8) ppb, p = 0.04, and 4.5 ± 1.7 versus 2.7 ± 0.7 ppm, p = 0.001, respectively), but no significant differences were found for NOx or H(2)O(2). In conclusion, inflammatory and oxidative stress biomarkers are raised in patients with PF compared with controls. EBC may be useful for detecting and monitoring lung inflammation in PF.

New perspectives in pharmacological treatment of mild persistent asthma

Until the relationship between symptoms, lung function tests, airway inflammation, airway hyper-responsiveness (AHR), exacerbations and remodelling is clarified, regular treatment seems to enable a greater disease control than on-demand therapy in most patients with mild persistent asthma. Current guideline classification based on disease severity remains a cornerstone in asthma management. However, the heterogeneity of asthma, the growing emphasis on subphenotypes, including molecular phenotypes identified by -omics technologies, and their possible implications in terms of different asthma severity, progression and therapeutic response, are changing current asthma treatment mainly based on disease severity classification to a pharmacological strategy more focused on the individual patient.

Smart sensor systems for human health breath monitoring applications

Breath analysis techniques offer a potential revolution in health care diagnostics, especially if these techniques can be brought into standard use in the clinic and at home. The advent of microsensors combined with smart sensor system technology enables a new generation of sensor systems with significantly enhanced capabilities and minimal size, weight and power consumption. This paper discusses the microsensor/smart sensor system approach and provides a summary of efforts to migrate this technology into human health breath monitoring applications. First, the basic capability of this approach to measure exhaled breath associated with exercise physiology is demonstrated. Building from this foundation, the development of a system for a portable asthma home health care system is described. A solid-state nitric oxide (NO) sensor for asthma monitoring has been identified, and efforts are underway to miniaturize this NO sensor technology and integrate it into a smart sensor system. It is concluded that base platform microsensor technology combined with smart sensor systems can address the needs of a range of breath monitoring applications and enable new capabilities for healthcare.

Demonstration that methadone is being present in the exhaled breath aerosol fraction

Methadone has previously been found present in exhaled breath of methadone treated patients. This study aimed at studying if methadone is present in the aerosol fraction of exhaled breath and used different filter sampling techniques for that. Patients receiving methadone maintenance treatment were recruited for the study. Methadone was extracted from filters collecting methadone from exhaled breath using 2-propanol, methanol and ethyl acetate and measured using liquid-chromatography-tandem mass-spectrometry. The limit of quantification was 5 pg/sample and the intra-day imprecision and accuracy within 15%. The recovery of extracting methadone from filters was >90%. Two types of micro-particle filters were used in this study and were compared with the C18 silica filter (Empore) used before. The Glass fiber filter collected methadone from exhaled breath of methadone patients. The amount collected significantly exceeded the amount using the C18 Empore filter (3.6-14-fold), but the variability of amount trapped was large. The second filter type was a polymer filter. Also this filter was able to trap methadone from exhaled breath of methadone patients. The amount and variability was similar to the C18 Empore filter but smaller than the Glass fiber filter. The mean rate of methadone excretion measured with the best polymer filter was 92 pg/min with a range between 20 and 287 (n=5). The polymer filter has the practical advantage of having a low flow resistance making it possible to sample without pumping assistance. The polymer filter was found to collect >90% of the exhaled methadone. The conclusion of this study was that methadone in exhaled breath is carried in the aerosol fraction known to be formed in the lung as a result of normal breathing.

Pharmacotherapy of patients with mild persistent asthma: strategies and unresolved issues

In studies comparing regular versus on-demand treatment for patients with mild persistent asthma, on-demand treatment seems to have a similar efficacy on clinical and functional outcomes, but it does not suppress chronic airway inflammation or airway hyper-responsiveness (AHR) associated with asthma. Data on the efficacy of a continuous treatment with inhaled corticosteroids (ICS) in preventing the progression of asthma are conflicting. There is the possibility that patients without a regular treatment with ICS may develop a more severe asthma associated with airway structural changes (remodeling) and a progressive loss of lung function. However, the possible clinical and functional consequences of persistent, not controlled, airway inflammation in patients with asthma have to be established. Assessment of asthma control should include inflammatory outcomes, such as fraction of exhaled nitric oxide and sputum eosinophil counts. Until the relationships between symptoms, lung function tests, AHR, airway inflammation, exacerbations, and airway remodeling are clarified, regular treatment seems to be generally more appropriate than on-demand treatment to warrant a greater control of asthma. Select subgroups of patients with mild asthma who are well controlled by regular treatment might adopt the on-demand treatment plan as an intermediate step toward the suspension of controller medication. The increasing evidence for heterogeneity of asthma, the growing emphasis on asthma subphenotypes, including molecular phenotypes identified by omics technologies, and their possible implications for different asthma severity and progression and therapeutic response, are changing the paradigm of treating patients with asthma only based on classification of their disease severity to a pharmacological strategy more focused on the individual asthmatic patient. Pharmacological treatment of asthma is going toward a personalized approach.

Hydrogen peroxide in exhaled breath condensate in patients with asthma: a promising biomarker?

BACKGROUND

The measurement of hydrogen peroxide (H(2)O(2)) in exhaled breath condensate (EBC) has been proposed as a noninvasive way of monitoring airway inflammation. However, results from individual studies on EBC H(2)O(2) evaluation of asthma are conflicting. The purpose of this study was to explore whether EBC H(2)O(2) is elevated in people with asthma and whether it reflects disease severity and disease control or responds to corticosteroid treatment.

METHODS

Studies were identified by searching PubMed, Embase, Cochrane Database, Cumulative Index to Nursing and Allied Health Literature (CINAHL), and www.controlled-trials.com for relevant reports published before September 2010. Observational studies comparing levels of EBC H(2)O(2) between patients with asthma who were nonsmokers and healthy subjects were included. Data were independently extracted by two investigators and analyzed using Stata 10.0 software.

RESULTS

Eight studies (involving 728 participants) were included. EBC H(2)O(2) concentrations were significantly higher in patients with asthma who were nonsmokers compared with healthy subjects, and higher values of EBC H(2)O(2) were observed at each level of asthma, classified either by severity or control level, and the values were negatively correlated with FEV(1). In addition, EBC H(2)O(2) concentrations were lower in patients with asthma treated with corticosteroids than in patients with asthma not treated with corticosteroids.

CONCLUSIONS

H(2)O(2) might be a promising biomarker for guiding asthma treatment. However, further investigation is needed to establish its role.

Leukotriene modifiers for asthma treatment

Leukotrienes (LTs), including cysteinyl LTs (CysLTs) and LTB(4) , are potent lipid mediators that have a role in the pathophysiology of asthma. At least two receptor subtypes for CysLTs, CysLT(1) and CysLT(2) , have been identified. The activation of the CysLT(1) receptor is responsible for most of the pathophysiological effects of CysLTs in asthma, including increased airway smooth muscle activity, microvascular permeability, and airway mucus secretion. LTB(4) might have a role in severe asthma, asthma exacerbations, and the development of airway hyperresponsiveness. CysLT(1) receptor antagonists can be given orally as monotherapy in patients with mild persistent asthma, but these drugs are generally less effective than inhaled glucocorticoids. Combination of CysLT(1) receptor antagonists and inhaled glucocorticoids in patients with more severe asthma may improve asthma control and enable the dose of inhaled glucocorticoids to be reduced while maintaining similar efficacy. The identification of subgroups of asthmatic patients who respond to CysLT(1) receptor antagonists is relevant for asthma management as the response to these drugs is variable. CysLT(1) receptor antagonists have a potential anti-remodelling effect that might be important for preventing or reversing airway structural changes in patients with asthma. This review discusses the role of LTs in asthma and the role of LT modifiers in asthma treatment.

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.

Role of Leukotrienes and Leukotriene Modifiers in Asthma

Leukotrienes (LTs), including cysteinyl LTs (CysLTs) and LTB₄, are potent lipid mediators that are pivotal in the pathophysiology of asthma phenotypes. At least two receptor subtypes for CysLTs - CysLT1 and CysLT₂ - have been identified. Most of the pathophysiological effects of CysLTs in asthma, including increased airway smooth muscle activity, microvascular permeability and airway mucus secretion, are mediated by the activation of the CysLT1 receptor. LTB₄ may have a role in the development of airway hyperresponsiveness, severe asthma and asthma exacerbations. Although generally less effective than inhaled glucocorticoids, CysLT₁ receptor antagonists can be given orally as monotherapy in patients with persistent mild asthma. In patients with more severe asthma, CysLT₁ receptor antagonists can be combined with inhaled glucocorticoids. This therapeutic strategy improves asthma control and enables the dose of inhaled glucocorticoids to be reduced, while maintaining similar efficacy. The identification of subgroups of patients with asthma who respond to CysLT₁ receptor antagonists is relevant for asthma management, as the response to these drugs is variable. The potential anti-remodeling effect of CysLT₁ receptor antagonists might be important for preventing or reversing airway structural changes in patients with asthma. This review discusses the role of LTs in asthma and the therapeutic implications of the pharmacological modulation of the LT pathway for asthma.

HPLC/MS/MS-based approaches for detection and quantification of eicosanoids

Eicosanoids are oxygenated, endogenous, unsaturated fatty acids derived from arachidonic acid. Detection and quantification of these compounds are of great interest because they play important roles in a number of significant diseases, including asthma, chronic obstructive pulmonary disease (COPD), cardiovascular disease, and cancer. Because the endogenous levels of eicosanoids are quite low, sensitive and specific analytical methods are required to reliably quantify these compounds. High-performance liquid chromatography mass spectrometry (HPLC/MS) has emerged as one of the main techniques used in eicosanoid profiling. Herein, we describe the main LC/MS techniques and principles as well as their application in eicosanoid analysis. In addition, a protocol is given for extracting eicosanoids from biological samples, using bronchoalveolar lavage fluid (BALF) as an example. The method and instrument optimization procedures are presented, followed by the analysis of eicosanoid standards using reverse phase HPLC interfaced with an ion trap mass spectrometer (LC/MS/MS). This protocol is intended to provide a broad description of the field for readers looking for an introduction to the methodologies involved in eicosanoid quantification.

Analysis of exhaled breath condensate in respiratory medicine: methodological aspects and potential clinical applications

Analysis of exhaled breath condensate (EBC) is a noninvasive method for studying the composition of airway lining fluid and has the potential for assessing lung inflammation. EBC is mainly formed by water vapor, but also contains aerosol particles in which several biomolecules including leukotrienes, 8-isoprostane, prostaglandins, hydrogen peroxide, nitric oxide-derived products, and hydrogen ions, have been detected in healthy subjects. Inflammatory mediators in EBC are detected in healthy subjects and some of them are elevated in patients with different lung diseases. Analysis of EBC is completely noninvasive, is particularly suitable for longitudinal studies, and is potentially useful for assessing the response to pharmacological therapy. Identification of selective profiles of biomarkers of lung diseases might also have a diagnostic value. However, EBC analysis currently has important limitations. The lack of standardized procedures for EBC analysis and validation of some analytical techniques makes it difficult comparison of results from different laboratories. Analysis of EBC is currently more useful for relative measures than for quantitative assessment of inflammatory mediators. Reference analytical techniques are required to provide definitive evidence for the presence of some inflammatory mediators in EBC and for their accurate quantitative assessment in this biological fluid. Several methodological issues need to be addressed before EBC analysis can be considered for clinical applications. However, further research in this area is warranted due to the relative lack of noninvasive methods for assessing lung inflammation.

Exhaled breath condensate in patients with asthma: implications for application in clinical practice

Exhaled breath condensate (EBC) analysis, a rather appealing and promising method, can be used to evaluate conveniently and non-invasively a wide range of molecules from the respiratory tract, and to understand better the pathways propagating airway inflammation. A large number of mediators of inflammation, including adenosine, ammonia, hydrogen peroxide, isoprostanes, leukotrienes, prostanoids, nitrogen oxides, peptides and cytokines, have been studied in EBC. Concentrations of such mediators have been shown to be related to the underlying asthma and its severity and to be modulated by therapeutic interventions. Despite the encouraging positive results to date, the introduction of EBC in everyday clinical practice requires the resolution of some methodological pitfalls, the standardization of EBC collection and finally the identification of a reliable biomarker that is reproducible has normal values and provides information regarding the underlying inflammatory process and the response to treatment. So far, none of the parameters studied in EBC fulfils the aforementioned requirements with one possible exception: pH. EBC pH is reproducible, has normal values, reflects a significant part of asthma pathophysiology and is measurable on-site with standardized methodology although some methodological aspects of measurement of pH in EBC (e.g. the effect of ambient CO(2), sample de-aeration, time for pH measurement) require further research. However, EBC pH has not been evaluated prospectively as a guide for treatment, in a manner similar to exhaled NO and sputum eosinophils. EBC represents a simple and totally non-invasive procedure that may contribute towards our understanding of asthma pathophysiology. Besides the evaluation of new biomarkers, the standardization of the already existing procedures is warranted for the introduction of EBC in clinical practice.

Exhaled breath condensate in children: present knowledge and future prospects

Exhaled breath condensate (EBC) is a safe and easy technique that enables several biomarkers of lung disease to be detected. Condensate collection requires only minimal cooperation and can easily be done by children as young as 4 years old. Some condensers have been adapted for use by younger children but EBC collection with these devices still poses significant drawbacks. EBC has been applied in the study of various respiratory diseases in children (mostly asthma and cystic fibrosis, but also other diseases such as primary ciliary dyskinesia). Several biomarkers of airway inflammation and oxidative stress have been detected in the EBC of these patients, demonstrating the role of different inflammatory pathways in the pathophysiology of respiratory diseases. Lately EBC has also been analyzed using new techniques, such as metabolomic analysis, an approach that enables the simultaneous assessment of several biocompounds with the potential identification of metabolite profiles characteristic of a given disease. Studies published so far support the promising role of EBC in investigating the pathophysiology of lung diseases. The noninvasiveness of this technique makes it particularly suitable for application in children.

Biomarkers in exhaled breath condensate: a review of collection, processing and analysis

Exhaled breath condensate (EBC) is a potential rich source for countless biomarkers that can provide valuable information about respiratory as well as systemic diseases. EBC has been studied in a variety of diseases including allergic rhinitis, asthma, chronic obstructive lung disease, cystic fibrosis, lung cancer, and obstructive sleep apnea syndrome. Although numerous biomarkers have been discovered and studied in EBC, the methods of collection and biomarker detection have not been fully standardized. While leaving standardization methods up to individual labs for the present time is optimal for the continued discovery of new biomarkers in EBC, this decreases the reproducibility and generalizability of the findings. In this review we will discuss specific biomarkers studied in specific diseases as well as some of the related technical issues including collection, processing and analysis.

Non-invasive biomarkers and pulmonary function in smokers

Limited information exists regarding measurement, reproducibility and interrelationships of non-invasive biomarkers in smokers. We compared exhaled breath condensate (EBC) leukotriene B₄ (LTB₄) and 8-isoprostane, exhaled nitric oxide, induced sputum, spirometry, plethysmography, impulse oscillometry and methacholine reactivity in 18 smokers and 10 non-smokers. We assessed the relationships between these measurements and within-subject reproducibility of EBC biomarkers in smokers. Compared to non-smokers, smokers had significantly lower MMEF % predicted (mean 64.1 vs 77.7, p = 0.003), FEV₁/FVC (mean 76.2 vs 79.8 p = 0.05), specific conductance (geometric mean 1.2 vs 1.6, p = 0.02), higher resonant frequency (mean 15.5 vs 9.9, p = 0.01) and higher EBC 8-isoprostane (geometric mean 49.9 vs 8.9 pg/ml p = 0.001). Median EBC pH values were similar, but a subgroup of smokers had airway acidification (pH < 7.2) not observed in non-smokers. Smokers had predominant sputum neutrophilia (mean 68.5%). Repeated EBC measurements showed no significant differences between group means, but Bland Altman analysis showed large individual variability. EBC 8-isoprostane correlated with EBC LTB₄ (r = 0.78, p = 0.0001). Sputum supernatant IL-8 correlated with total neutrophil count per gram of sputum (r = 0.52, p = 0.04) and with EBC pH (r = −0.59, p = 0.02). In conclusion, smokers had evidence of small airway dysfunction, increased airway resistance, reduced lung compliance, airway neutrophilia and oxidative stress.

Variability of exhaled breath condensate leukotriene B4 and 8-isoprostane in COPD patients

The reproducibility of exhaled breath condensate (EBC) mediators is not well documented in chronic obstructive pulmonary disease (COPD). This study assessed within assay (WA), within (WD) and between day (BD) reproducibility of EBC leukotriene B₄ (LTB₄) and 8-isoprostane. Three EBC samples were collected from 24 COPD patients separated by 1 h and 1 wk, to assess WD and BD reproducibility. WA reproducibility was assessed by sample analysis by enzyme immunoassay in triplicate. WA coefficient of variation for LTB₄ and 8-isoprostane (18.2% and 29.2%, respectively) was lower than corresponding values for WD (47.7% and 65.3%, respectively) and BD (75.7% and 79.1%, respectively). Repeatability coefficient for 8-isoprostane and LTB₄ assays were 18.6 pg/ml and 13.2 pg/ml, respectively. Group mean differences for WD and BD were small and statistically nonsignificant. Using the Bland Altman method, there were wide limits of agreement for WD (−51.6 to 47.2 for 8-isoprostane and −31.8 to 31.4 for LTB₄) and BD reproducibility (−61.4 to 75.7 for 8-isoprostane and −29.3 to 38.6 for LTB₄). This is the first study to fully report the variability of EBC 8-isoprostane and LTB₄ in COPD. WA variability and group mean changes were small. However, we observed considerable WD and BD variability for these biomarkers.

Exhaled breath condensate: a new method for lung disease diagnosis

Analysis of exhaled breath composition in lung disease patients can indirectly point to biochemical changes that occur in the fluid lining airway surfaces. The parameters of redox and acid-base changes, and of inflammatory changes relevant in the pathogenesis of most pulmonary diseases are currently most widely determined in exhaled breath condensate. The collection of exhaled breath condensate is a safe, non-invasive, easy and simple diagnostic procedure that is suitable for longitudinal studies and applicable in patients of all age groups, irrespective of the disease severity. In spite of many scientific studies involving lung disease patients, methodology for exhaled breath condensate collection and analysis has not yet been realized for daily utilization. Additional studies of the exact origin of condensate constituents and standardization of the overall analytical process, including collection, storage, analysis and result interpretation, are needed. Irrespective of these limitations, further investigation of this sample type is fully justified by the fact that classical specimens used in the management of pulmonary disease are either obtained by invasive procedures (e.g., induced sputum, biopsy, bronchoalveolar lavage) or cannot provide appropriate information (e.g., urine, serum). Analysis of exhaled breath condensate in the future might contribute significantly to our understanding of the physiological and pathophysiological processes in lungs, to early detection, diagnosis and follow up of disease progression, and to evaluation of therapeutic response.

Method optimization and validation for the simultaneous determination of arachidonic acid metabolites in exhaled breath condensate by liquid chromatography-electrospray ionization tandem mass spectrometry

Background

Determinations of inflammatory markers in exhaled breath condensate were used to assess airway inflammation. The most applied method for this kind of determination is enzyme immunoassay. For research purposes to find new or to relate concrete biomarkers to different pulmonary diseases, a simultaneous determination of different inflammatory markers would be advantageous.

Methods

We developed an analytical method with on-line clean up and enrichment steps to determine 12 different inflammatory markers in exhaled breath condensate. A specific detection method ensures the unequivocally determination of each analyte at the same run. The method was optimized and validated to achieve a low limit of quantification up to 10 pg/mL each analyte. The precision of the method ranged between 4 and 16%.

Conclusion

The presented method should serve as an easy and fast tool to assess the utility of inflammatory markers in exhaled breath condensate to different pulmonary diseases and for several related disciplines in medicine.

Liquid chromatography/mass spectrometry analysis of exhaled leukotriene B4 in asthmatic children

Background

The role of leukotriene (LT) B₄, a potent inflammatory mediator, in atopic asthmatic and atopic nonasthmatic children is largely unknown. The lack of a gold standard technique for measuring LTB₄ in exhaled breath condensate (EBC) has hampered its quantitative assessment in this biological fluid. We sought to measure LTB₄ in EBC in atopic asthmatic children and atopic nonasthmatic children. Exhaled nitric oxide (NO) was measured as an independent marker of airway inflammation.

Methods

Fifteen healthy children, 20 atopic nonasthmatic children, 25 steroid-naïve atopic asthmatic children, and 22 atopic asthmatic children receiving inhaled corticosteroids were studied. The study design was of cross-sectional type. Exhaled LTB₄ concentrations were measured using liquid chromatography/mass spectrometry-mass spectrometry (LC/MS/MS) with a triple quadrupole mass spectrometer. Exhaled NO was measured by chemiluminescence with a single breath on-line method. LTB₄ values were expressed as the total amount (in pg) of eicosanoid expired in the 15-minute breath test. Kruskal-Wallis test was used to compare groups.

Results

Compared with healthy children [87.5 (82.5–102.5) pg, median and interquartile range], exhaled LTB₄ was increased in steroid-naïve atopic asthmatic [255.1 (175.0–314.7) pg, p < 0.001], but not in atopic nonasthmatic children [96.5 (87.3–102.5) pg, p = 0.59)]. Asthmatic children who were receiving inhaled corticosteroids had lower concentrations of exhaled LTB₄ than steroid-naïve asthmatics [125.0 (25.0–245.0) pg vs 255.1 (175.0–314.7) pg, p < 0.01, respectively]. Exhaled NO was higher in atopic nonasthmatic children [16.2 (13.5–22.4) ppb, p < 0.05] and, to a greater extent, in atopic steroid-naïve asthmatic children [37.0 (31.7–57.6) ppb, p < 0.001] than in healthy children [8.3 (6.1–9.9) ppb]. Compared with steroid-naïve asthmatic children, exhaled NO levels were reduced in asthmatic children who were receiving inhaled corticosteroids [15.9 (11.5–31.7) ppb, p < 0.01].

Conclusion

In contrast to exhaled NO concentrations, exhaled LTB₄ values are selectively elevated in steroid-naïve atopic asthmatic children, but not in atopic nonasthmatic children. Although placebo control studies are warranted, inhaled corticosteroids seem to reduce exhaled LTB₄ in asthmatic children. LC/MS/MS analysis of exhaled LTB₄ might provide a non-invasive, sensitive, and quantitative method for airway inflammation assessment in asthmatic children.

A validated liquid chromatography–mass spectrometry method for the determination of leukotrienes B4 and B5 produced by stimulated human polymorphonuclear leukocytes

A validated high-performance liquid chromatography (HPLC)-mass spectrometry method has been developed for the simultaneous assay of leukotrienes (LTs) B4 and B5, derived from omega-6 arachidonic acid and omega-3 polyunsaturated fatty acids (PUFA), respectively, produced by human polymorphonuclear leukocytes (PMNLs) stimulated with calcium ionophore A23187. The HPLC separation of PMNL ether extracts was performed on a reversed-phase column using a gradient elution program of 15 mM ammonium acetate and MeOH. Detection was performed by electrospray ionization-single quadripole mass spectrometry using single ion reaction monitoring in the negative mode at m/z 333.3 [M-H](-) and m/z 335.2 for prostaglandin B2/LTB5 and LTB4, respectively. The calibration curves for LTB4 and LTB5 were linear over the ranges 165-990 and 0.825-13.2 ng/ml, respectively. The lower limit of quantification for LTB5 was 0.66 ng/ml. The mean absolute recoveries for LTB4 and LTB5 were 81+/-4.8% and 82+/-5.9%, respectively. The method is precise with mean interday CVs for LTB4 and LTB5 within 7.1-10.7, and 3.8-9.4%, respectively, and accurate (range of interday deviations for LTB4 and LTB5 were -7.8 to 1, and -5 to 9% , respectively). The method has been validated and is being applied to the simultaneous quantification of the leukotrienes B4 and B5 in stimulated PMNLs in a clinical protocol studying the influence of a diet enriched in omega-3 PUFA on various surrogate markers of inflammation in young cystic fibrosis patients.

Exhaled breath condensate analysis in patients with COPD

Exhaled breath condensate (EBC) is a non-invasive method for studying the composition of airway lining fluid. EBC is mainly formed by water vapor but also contains aerosol particles in which several biomolecules including hydrogen peroxide, leukotrienes, prostaglandins, isoprostanes, nitric oxide-derived products, and hydrogen ions have been measured in healthy subjects. Some inflammatory mediators are elevated in patients with chronic obstructive pulmonary disease (COPD). Analysis of EBC has several advantages over other methods for assessing lung inflammation: it is completely non-invasive; this technique is particularly suitable for longitudinal studies; this method is potentially useful for assessing the efficacy of pharmacological therapy. Identification of selective profiles of inflammatory markers in EBC might also be of diagnostic value in patients with COPD. EBC analysis is currently more reliable for relative measures than for determining absolute levels of inflammatory mediators. The lack of standardization of the EBC analysis is currently the primary limitation of this technique making it difficult comparisons of data obtained in different laboratories. Reference analytical techniques are required to provide definitive evidence for the presence of several biomolecules in EBC and an accurate assessment of their concentrations in this biological fluid. Moreover, several methodological issues need to be addressed before this technique can be considered in the clinical management of patients with COPD. Despite important current limitations, further research in this area is warranted due to the lack of non-invasive methods for assessing lung inflammation which has a central role in the pathophysiology of COPD.