Oxidative stress and airway inflammation after allergen challenge evaluated by exhaled breath condensate analysis

Protocols to Measure Oxidative Stress and DNA Damage in Asthma

Asthma is associated with oxidative stress and oxidative damage of biomolecules, including DNA. Here, we describe the protocols to quantify reactive oxygen species (ROS) and oxidative stress markers in a mouse model of allergic airway inflammation. We also provide detailed methods to measure DNA damage by long-run real-time PCR for DNA-damage quantification (LORD-Q) assay and gene-specific DNA damage analyses by long amplicon (LA)-qPCR. Additionally, we describe methods to quantify oxidized DNA base lesions in lung genomic DNA by mass spectrometry, and to measure enzymatic activity of 8-oxoguanine DNA glycosylase (OGG1). Using these methods, the levels of oxidative stress and DNA damage in allergic inflammation and asthma can be elucidated.

Role of Nrf2 in Disease: Novel Molecular Mechanisms and Therapeutic Approaches - Pulmonary Disease/Asthma

Nuclear factor erythroid 2-related factor 2 (Nrf2) is a major transcription factor involved in redox homeostasis and in the response induced by oxidative injury. Nrf2 is present in an inactive state in the cytoplasm of cells. Its activation by internal or external stimuli, such as infections or pollution, leads to the transcription of more than 500 elements through its binding to the antioxidant response element. The lungs are particularly susceptible to factors that generate oxidative stress such as infections, allergens and hyperoxia. Nrf2 has a crucial protective role against these ROS. Oxidative stress and subsequent activation of Nrf2 have been demonstrated in many human respiratory diseases affecting the airways, including asthma and chronic obstructive pulmonary disease (COPD), or the pulmonary parenchyma such as acute respiratory distress syndrome (ARDS) and pulmonary fibrosis. Several compounds, both naturally occurring and synthetic, have been identified as Nrf2 inducers and enhance the activation of Nrf2 and expression of Nrf2-dependent genes. These inducers have proven particularly effective at reducing the severity of the oxidative stress-driven lung injury in various animal models. In humans, these compounds offer promise as potential therapeutic strategies for the management of respiratory pathologies associated with oxidative stress but there is thus far little evidence of efficacy through human trials. The purpose of this review is to summarize the involvement of Nrf2 and its inducers in ARDS, COPD, asthma and lung fibrosis in both human and in experimental models.

Molecular mechanisms of oxidative stress in asthma

The lungs are exposed to reactive oxygen species oxygen (ROS) produced as a result of inhalation of oxygen, as well as smoke and other air pollutants. Cell metabolism and the NADPH oxidases (Nox) generate low levels of intracellular ROS that act as signal transduction mediators by inducing oxidative modifications of histones, enzymes and transcription factors. Redox signalling is also regulated by localised production and sensing of ROS in mitochondria, the endoplasmic reticulum (ER) and inside the nucleus. Intracellular ROS are maintained at low levels through the action of a battery of enzymatic and non-enzymatic antioxidants. Asthma is a heterogeneous airway inflammatory disease with different immune endotypes; these include atopic or non-atopic Th2 type immune response associated with eosinophilia, or a non-Th2 response associated with neutrophilia. Airway remodelling and hyperresponsiveness accompany the inflammatory response in asthma. Over-production of ROS resulting from infiltrating immune cells, particularly eosinophils and neutrophils, and a concomitant impairment of antioxidant responses lead to development of oxidative stress in asthma. Oxidative stress is augmented in severe asthma and during exacerbations, as well as by air pollution and obesity, and causes oxidative damage of tissues promoting airway inflammation and hyperresponsiveness. Furthermore, deregulated Nox activity, mitochondrial dysfunction, ER stress and/or oxidative DNA damage, resulting from exposure to irritants, inflammatory mediators or obesity, may lead to redox-dependent changes in cell signalling. ROS play a central role in airway epithelium-mediated sensing, development of innate and adaptive immune responses, and airway remodelling and hyperresponsiveness. Nonetheless, antioxidant compounds have proven clinically ineffective as therapeutic agents for asthma, partly due to issues with stability and in vivo metabolism of these compounds. The compartmentalised nature of ROS production and sensing, and the role of ROS in homeostatic responses and in the action of corticosteroids and β2-adrenergic receptor agonists, adds another layer of complexity to antioxidant therapy development. Nox inhibitors and mitochondrial-targeted antioxidants are in clinical development for a number of diseases but they have not yet been investigated in asthma. A better understanding of the complex role of ROS in the pathogenesis of asthma will highlight new opportunities for more targeted and effective redox therapies.

Eicosanoids seasonally impact pulmonary function in asthmatic patients with Japanese cedar pollinosis

BACKGROUND

Condition of asthma in patients with asthma and concomitant seasonal allergic rhinitis (SAR) deteriorates during the Japanese cedar pollen (JCP) season. However, the underlying mechanisms remain unclear.

METHODS

We analyzed seasonal variations in eicosanoid levels in the airways of patients with asthma and concomitant SAR sensitized to JCP (N = 29, BA-SAR-JCP group) and those not sensitized (N = 13, BA-AR-non-JCP group) during the JCP season. The association between changes in eicosanoid concentrations and pulmonary function was assessed. Exhaled breath condensate (EBC) was collected, and pulmonary function tests were performed during the JCP and non-JCP seasons. The cysteinyl leukotriene (CysLT), thromboxane B₂ (TXB₂), prostaglandin D₂-methoxime (PGD₂-MOX), and leukotriene B₄ (LTB₄) levels in the collected EBC were measured via enzyme-linked immunosorbent immunoassays.

RESULTS

The log CysLT levels significantly increased in the BA-SAR-JCP group during the JCP season compared with the non-JCP season (1.78 ± 0.55, 1.39 ± 0.63 pg/mL, mean ± standard deviation, respectively, p = 0.01) and those in the BA-AR-non-JCP group during the JCP season (1.39 ± 0.38 pg/mL, p = 0.04). Moreover, the log TXB₂ levels seemed to increase. However, the log LTB₄ and log PGD₂-MOX levels did not increase. The changes in the log CysLT levels during the two seasons were negatively correlated to forced expiratory volume in one second (FEV₁) in the BA-SAR-JCP group (r = -0.52, p < 0.01).

CONCLUSIONS

In the BA-SAR-JCP group, seasonal increases in eicosanoid levels in the airway likely promoted deterioration in pulmonary function despite optimal maintenance treatment.

Reference Ranges of 8-Isoprostane Concentrations in Exhaled Breath Condensate (EBC): A Systematic Review and Meta-Analysis

Isoprostanes are physiopathologic mediators of oxidative stress, resulting in lipid peroxidation. 8-isoprostane seems particularly useful for measuring oxidative stress damage. However, no reference range values are available for 8-isoprosante in exhaled breath condensate (EBC) of healthy adults, enabling its meaningful interpretation as a biomarker. We conducted this systematic review and meta-analysis according to the protocol following PROSPERO (CRD42020146623). After searching and analyzing the literature, we included 86 studies. After their qualitative synthesis and risk of bias assessment, 52 studies were included in meta-analysis. The latter focused on studies using immunological analytical methods and investigated how the concentrations of 8-isoprostane differ based on gender. We found that gender had no significant effect in 8-isoprostane concentration. Among other studied factors, such as individual characteristics and factors related to EBC collection, only the device used for EBC collection significantly affected measured 8-isoprostane concentrations. However, adjustment for the factors related to EBC collection, yielded uncertainty whether this effect is due to the device itself or to the other factors. Given this uncertainty, we estimated the reference range values of 8-isoprostane stratified by gender and EBC collection device. A better standardization of EBC collection seems necessary; as well more studies using chemical analytical methods to extend this investigation.

Oxidative stress and macrophages: driving forces behind exacerbations of asthma and chronic obstructive pulmonary disease?

Oxidative stress is a common feature of obstructive airway diseases like asthma and chronic obstructive pulmonary disease (COPD). Lung macrophages are key innate immune cells that can generate oxidants and are known to display aberrant polarization patterns and defective phagocytic responses in these diseases. Whether these characteristics are linked in one way or another and whether they contribute to the onset and severity of exacerbations in asthma and COPD remain poorly understood. Insight into oxidative stress, macrophages, and their interactions may be important in fully understanding acute worsening of lung disease. This review therefore highlights the current state of the art regarding the role of oxidative stress and macrophages in exacerbations of asthma and COPD. It shows that oxidative stress can attenuate macrophage function, which may result in impaired responses toward exacerbating triggers and may contribute to exaggerated inflammation in the airways.

Effect of Anti-IL17 Antibody Treatment Alone and in Combination With Rho-Kinase Inhibitor in a Murine Model of Asthma

Background: Interleukin-17 (IL-17) and Rho-kinase (ROCK) play an important role in regulating the expression of inflammatory mediators, immune cell recruitment, hyper-responsiveness, tissue remodeling, and oxidative stress. Modulation of IL-17 and ROCK proteins may represent a promising approach for the treatment of this disease.

Objective: To study the effects of an anti-IL17 neutralizing antibody and ROCK inhibitor treatments, separately and in combination, in a murine model of chronic allergy-induced lung inflammation.

Methods: Sixty-four BALBc mice, were divided into eight groups (n = 8): SAL (saline-instilled); OVA (exposed-ovalbumin); SAL-RHOi (saline and ROCK inhibitor), OVA-RHOi (exposed-ovalbumin and ROCK inhibitor); SAL-anti-IL17 (saline and anti-IL17); OVA-anti-IL17 (exposed-ovalbumin and anti-IL17); SAL-RHOi-anti-IL17 (saline, ROCK inhibitor and anti-IL17); and OVA-RHOi-anti-IL17 (exposed-ovalbumin, anti-IL17, and ROCK inhibitor). A 28-day protocol of albumin treatment was used for sensitization and induction of pulmonary inflammation. The anti-IL17A neutralizing antibody (7.5 μg per treatment) was administered by intraperitoneal injection and ROCK inhibitor (Y-27632) intranasally (10 mg/kg), 1 h prior to each ovalbumin challenge (days 22, 24, 26, and 28).

Results: Treatment with the anti-IL17 neutralizing antibody and ROCK inhibitor attenuated the percentage of maximal increase of respiratory system resistance and respiratory system elastance after challenge with methacholine and the inflammatory response markers evaluated (CD4⁺, CD8⁺, ROCK1, ROCK2, IL-4, IL-5, IL-6, IL-10 IL-13, IL-17, TNF-α, TGF-β, NF-κB, dendritic cells, iNOS, MMP-9, MMP-12, TIMP-1, FOXP3, isoprostane, biglycan, decorin, fibronectin, collagen fibers content and gene expression of IL-17, VAChT, and arginase) compared to the OVA group (p < 0.05). Treatment with anti-IL17 and the ROCK inhibitor together resulted in potentiation in decreasing the percentage of resistance increase after challenge with methacholine, decreased the number of IL-5 positive cells in the airway, and reduced, IL-5, TGF-β, FOXP3, ROCK1 and ROCK2 positive cells in the alveolar septa compared to the OVA-RHOi and OVA-anti-IL17 groups (p < 0.05).

Conclusion: Anti-IL17 treatment alone or in conjunction with the ROCK inhibitor, modulates airway responsiveness, inflammation, tissue remodeling, and oxidative stress in mice with chronic allergic lung inflammation.

miR-155 Modulates Cockroach Allergen- and Oxidative Stress-Induced Cyclooxygenase-2 in Asthma

Exposure to cockroach allergen is a strong risk factor for developing asthma. Asthma has been associated with allergen-induced airway epithelial damage and heightened oxidant stress. In this study, we investigated cockroach allergen-induced oxidative stress in airway epithelium and its underlying mechanisms. We found that cockroach extract (CRE) could induce reactive oxygen species (ROS) production, particularly mitochondrial-derived ROS, in human bronchial epithelial cells. We then used the RT² Profiler PCR array and identified that cyclooxygenase-2 (COX-2) was the most significantly upregulated gene related to CRE-induced oxidative stress. miR-155, predicted to target COX-2, was increased in CRE-treated human bronchial epithelial cells, and was showed to regulate COX-2 expression. Moreover, miR-155 can bind COX-2, induce COX-2 reporter activity, and maintain mRNA stability. Furthermore, CRE-treated miR-155^-/- mice showed reduced levels of ROS and COX-2 expression in lung tissues and PGE₂ in bronchoalveolar lavage fluid compared with wild-type mice. These miR-155^-/- mice also showed reduced lung inflammation and Th2/Th17 cytokines. In contrast, when miR-155^-/- mice were transfected with adeno-associated virus carrying miR-155, the phenotypic changes in CRE-treated miR-155^-/- mice were remarkably reversed, including ROS, COX-2 expression, lung inflammation, and Th2/Th17 cytokines. Importantly, plasma miR-155 levels were elevated in severe asthmatics when compared with nonasthmatics or mild-to-moderate asthmatics. These increased plasma miR-155 levels were also observed in asthmatics with cockroach allergy compared with those without cockroach allergy. Collectively, these findings suggest that COX-2 is a major gene related to cockroach allergen-induced oxidative stress and highlight a novel role of miR-155 in regulating the ROS-COX-2 axis in asthma.

The effect of allergen-induced bronchoconstriction on concentration of 5-oxo-ETE in exhaled breath condensate of house dust mite-allergic patients

BACKGROUND

Arachidonic acid metabolites regulate several aspects of airway function including inflammation, muscle contraction and mucous secretion.

OBJECTIVE

The aim of this study was to evaluate concentration of selected 5-lipoxygenase- and cyclooxygenase-derived eicosanoids in exhaled breath condensate (EBC) during allergen-induced bronchoconstriction.

METHODS

The study was performed on 24 allergic rhinitis/asthma patients sensitized to a house dust mite (HDM) Dermatophagoides pteronyssinus (Dp) and 13 healthy controls (HCs). Bronchial challenge with Dp extract was performed only in the allergic patients. EBC samples were collected before (T₀ ) and during Dp-induced bronchoconstriction (T_EAR ). Eicosanoid concentration was measured using HPLC-tandem mass spectrometry.

RESULTS

Significant bronchoconstriction after Dp challenge was demonstrated in 15 patients (Rs), while in 9 patients (NRs) no asthmatic response could be detected. At T₀ the most abundant eicosanoids in EBC of HDM-allergic patients were LTB₄ and 5-oxo-ETE, while in HCs EBC concentration of LTB₄ was significantly greater than that of 5-oxo-ETE. Allergen challenge resulted in significant increase in EBC concentration of 5-oxo-ETE, LTD₄ and 8-iso-PGE₂ only in Rs. At T_EAR , the relative change of 5-oxo-ETE concentration in EBC correlated with decrease of peripheral blood eosinophilia (R = -0.774; P = .0012). Moreover, the relative increase of 5-oxo-ETE in EBC at T_EAR significantly correlated with the severity of the subsequent late asthmatic response (R = 0.683, P = .007).

CONCLUSION

Our study demonstrates significant up-regulation of 5-oxo-ETE synthesis in HDM-allergic patients and indicates possible involvement of that mediator in the pathogenesis of allergic asthma.

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.

Montelukast suppresses epithelial to mesenchymal transition of bronchial epithelial cells induced by eosinophils

Epithelial to mesenchymal transition (EMT) is a mechanism by which eosinophils can induce airway remodeling. Montelukast, an antagonist of the cysteinyl leukotriene receptor, can suppress airway remodeling in asthma. The purpose of this study was to evaluate whether montelukast can ameliorate airway remodeling by blocking EMT induced by eosinophils. EMT induced was assessed using a co-culture system of human bronchial epithelial cells and human eosinophils or the eosinophilic leukemia cell lines, Eol-1. Montelukast inhibited co-culture associated morphological changes of BEAS-2b cells, decreased the expression of vimentin and collagen I, and increased the expression of E-cadherin. Montelukast mitigated the rise of TGF-β1 production and Smad3 phosphorylation. Co-culture of human eosinophils with BEAS-2B cells significantly enhanced the production of CysLTs compared with BEAS-2B cells or eosinophils alone. The increase of CysLTs was abolished by montelukast pre-treatment. Montelukast had similar effects when co-culture system of Eol-1 and BEAS-2B was used. This study showed that montelukast suppresses eosinophils-induced EMT of airway epithelial cells. This finding may explain the mechanism of montelukast-mediated amelioration of airway remodeling in bronchial asthma.

Airway oxidative stress in chronic cough

BACKGROUND

The mechanisms of chronic cough are unclear. Many reactive oxygen species affect airway sensory C-fibres which are capable to induce cough. Several chronic lung diseases are characterised by cough and oxidative stress. In asthma, an association between the cough severity and airway oxidative stress has been demonstrated. The present study was conducted to investigate whether airway oxidative stress is associated with chronic cough in subjects without chronic lung diseases.

METHODS

Exhaled breath condensate samples were obtained in 43 non-smoking patients with chronic cough and 15 healthy subjects. Exclusion criteria included a doctor's diagnosis of any lung disorders and any abnormality in lung x-ray. The concentration of 8-isoprostane was measured. In addition, the patients filled in Leicester Cough Questionnaire and underwent hypertonic saline cough provocation test, spirometry, ambulatory peak flow monitoring, nitric oxide measurement, and histamine airway challenge. In a subgroup of patients the measurements were repeated during 12 weeks' treatment with inhaled budesonide, 800 ug/day.

RESULTS

The 8-isoprostane concentrations were higher in the cough patients than in the healthy subjects (24.6 ± 1.2 pg/ml vs. 10.1 ± 1.7 pg/ml, p = 0.045). The 8-isoprostane concentration was associated with the Leicester Cough Questionnaire total score (p = 0.044) but not with the cough sensitivity to saline or other tests. Budesonide treatment did not affect the 8-isoprostane concentrations.

CONCLUSIONS

Chronic cough seems to be associated with airway oxidative stress in subjects with chronic cough but without chronic lung diseases. This finding may help to develop novel antitussive drugs.

TRIAL REGISTRATION

The study was registered in ClinicalTrials.gov database (KUH5801112), identifier NCT00859274.

Oxidant-induced corticosteroid unresponsiveness in human bronchial epithelial cells

BACKGROUND

We hypothesised that increased oxidative stress, as present in the airways of asthma and chronic obstructive pulmonary disease (COPD) patients, induces epithelial damage and reduces epithelial responsiveness to suppressive effects of corticosteroids on proinflammatory cytokine production and barrier function.

METHODS

We induced oxidative stress by H2O2 and/or cigarette smoke extract (CSE) in human bronchial epithelial 16HBE cells and primary bronchial epithelial cells (PBEC) derived by brushings from asthma patients, COPD patients, and smoking and non-smoking control individuals. We investigated effects of budesonide on barrier function (electrical resistance) and TNF-α-induced proinflammatory cytokine production (IL-8/CXCL8, granulocyte macrophage-colony stimulating factor (GM-CSF)).

RESULTS

We observed that H2O2 and CSE reduce epithelial resistance. Budesonide significantly counteracted this effect, likely by protection against epidermal growth factor receptor-dependent cell-cell contact disruption. Furthermore, budesonide suppressed proinflammatory cytokine production. H2O2 pretreatment reduced this effect of budesonide on cytokine production in both 16HBE cells and PBECs. Importantly, PBECs from asthma and COPD patients were less sensitive to budesonide with respect to cytokine production and barrier function than PBECs from control subjects.

CONCLUSIONS

Together, our data indicate that budesonide suppresses epithelial proinflammatory responses and barrier dysfunction and that oxidative stress reduces these effects in airway epithelium from asthma and COPD patients. Therefore, restoration of corticosteroid responsiveness in asthma and COPD may act to improve the airway epithelial barrier.

Flavonone treatment reverses airway inflammation and remodelling in an asthma murine model

BACKGROUND AND PURPOSE

Asthma is an inflammatory disease that involves airway hyperresponsiveness and remodelling. Flavonoids have been associated to anti-inflammatory and antioxidant activities and may represent a potential therapeutic treatment of asthma. Our aim was to evaluate the effects of the sakuranetin treatment in several aspects of experimental asthma model in mice.

EXPERIMENTAL APPROACH

Male BALB/c mice received ovalbumin (i.p.) on days 0 and 14, and were challenged with aerolized ovalbumin 1% on days 24, 26 and 28. Ovalbumin-sensitized animals received vehicle (saline and dimethyl sulfoxide, DMSO), sakuranetin (20 mg kg(-1) per mice) or dexamethasone (5 mg kg(-1) per mice) daily beginning from 24th to 29th day. Control group received saline inhalation and nasal drop vehicle. On day 29, we determined the airway hyperresponsiveness, inflammation and remodelling as well as specific IgE antibody. RANTES, IL-5, IL-4, Eotaxin, IL-10, TNF-α, IFN-γ and GMC-SF content in lung homogenate was performed by Bioplex assay, and 8-isoprostane and NF-kB activations were visualized in inflammatory cells by immunohistochemistry.

KEY RESULTS

We have demonstrated that sakuranetin treatment attenuated airway hyperresponsiveness, inflammation and remodelling; and these effects could be attributed to Th2 pro-inflammatory cytokines and oxidative stress reduction as well as control of NF-kB activation.

CONCLUSIONS AND IMPLICATIONS

These results highlighted the importance of counteracting oxidative stress by flavonoids in this asthma model and suggest sakuranetin as a potential candidate for studies of treatment of asthma.

Traffic-related air pollutants and exhaled markers of airway inflammation and oxidative stress in New York City adolescents

Exposures to ambient diesel exhaust particles have been associated with respiratory symptoms and asthma exacerbations in children; however, epidemiologic evidence linking short-term exposure to ambient diesel exhaust particles with airway inflammation is limited. We conducted a panel study with asthmatic and nonasthmatic adolescents to characterize associations between ambient diesel exhaust particle exposures and exhaled biological markers of airway inflammation and oxidative stress. Over four weeks, exhaled breath condensate was collected twice a week from 18 asthmatics and 18 nonasthmatics (ages 14-19 years) attending two New York City schools and analyzed for pH and 8-isoprostane as indicators of airway inflammation and oxidative stress, respectively. Air concentrations of black carbon, a diesel exhaust particle indicator, were measured outside schools. Air measurements of nitrogen dioxide, ozone, and fine particulate matter were obtained for the closest central monitoring sites. Relationships between ambient pollutants and exhaled biomarkers were characterized using mixed effects models. Among all subjects, increases in 1- to 5-day averages of black carbon were associated with decreases in exhaled breath condensate pH, indicating increased airway inflammation, and increases in 8-isoprostane, indicating increased oxidative stress. Increases in 1- to 5-day averages of nitrogen dioxide were associated with increases in 8-isoprostane. Ozone and fine particulate matter were inconsistently associated with exhaled biomarkers. Associations did not differ between asthmatics and nonasthmatics. The findings indicate that short-term exposure to traffic-related air pollutants may increase airway inflammation and/or oxidative stress in urban youth and provide mechanistic support for associations documented between traffic-related pollutant exposures and respiratory morbidity.

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.

Lung function and biomarkers of airway inflammation during and after hospitalization for acute exacerbations of childhood asthma associated with viral respiratory symptoms

BACKGROUND

There are limited data assessing relationships between biomarkers of inflammation and lung function after hospitalization for asthma exacerbations in children.

OBJECTIVE

To assess the associations in asthmatic children among changes in lung function, fraction of exhaled nitric oxide (FENO), and cysteinyl leukotrienes (CysLTs) in exhaled breath condensate (EBC) after hospitalization for acute asthma.

METHODS

Spirometry and FENO were measured and EBC collected for CysLT measurement from 40 children during and 1, 2, and 4 weeks after hospitalization for an asthma exacerbation and during a single-study visit for 40 healthy children.

RESULTS

Enrollment FENO and EBC CysLT concentrations were higher in the children with asthma than in healthy individuals (mean FENO, 31.6 vs 7 ppb; P < .0001; mean EBC CysLT, 7.9 vs 4.9 ppb; P = .03). Among children with asthma, improvement in lung function reached a plateau within 2 weeks after hospital discharge. The EBC CysLT concentrations were not associated with changes in lung function, use of albuterol, or use of inhaled corticosteroids (ICSs). Among asthmatic children enrollment FENO was not associated with changes in lung function during follow-up. However, among children who had an elevated enrollment FENO (≥25 ppb), patients who did not use ICSs after hospital discharge had lower end-of-study lung function than those who used ICSs. At 2 and 4 weeks after hospital discharge, FENO was higher among patients who reported albuterol use more than twice weekly and among patients who reported no ICS use.

CONCLUSION

FENO measured at hospital discharge among children hospitalized with acute asthma may be useful in identifying patients who will respond to ICS therapy.

Exhaled breath 8-isoprostane as a marker of asthma severity

INTRODUCTION

Oxidative stress is a non-specific feature of airway inflammation in asthmatics. 8-Isoprostane (8-IP), a prostaglandin-F(2α) isomer, is a relatively new marker of oxidative stress and may be measured in exhaled breath condensate (EBC) of patients with asthma. This research study aimed to evaluate the usefulness of EBC 8-IP as a marker of severity and control of severe adult asthma.

MATERIAL AND METHODS

Twenty-seven severe, never-smoking asthmatics were studied. According to positive or negative reversibility testing, this group was subdivided into reversible and irreversible asthma groups. All participants were observed for 8 weeks during which they completed daily diary observations including day and night symptoms, number of awakenings, peak expiratory flow (PEF) variability, daily rescue medication usage and oral steroids consumption. They attended the clinic 3 times and on these occasions spirometry assessments, EBC collection and asthma control tests (ACT) were done. Two control groups were included: 11 healthy never-smokers and 16 newly diagnosed and never-treated, non-smoking mild asthmatics.

RESULTS

There were no statistically significant differences between severe asthma and healthy control or never-treated asthma groups in concentrations of EBC 8-IP (median and interquartile range: 4.67; 2.50-27.92 vs. 6.93; 2.5-12.98 vs. 3.80; 2.50-10.73, respectively). No correlations were found between EBC 8-IP and asthma control parameters, such as ACT results, night and day symptoms, consumption of rescue medication, percentage of days free of oral steroids, PEF diurnal variation, lung function test results, forced expiratory volume in the 1 s reversibility, and markers of systemic inflammation.

CONCLUSIONS

Our study results suggest that EBC 8-IP measurements are not useful for asthma monitoring.

Asthmatic cough and airway oxidative stress

The mechanisms of cough in asthma are unclear. Asthma is associated with an oxidative stress. Many reactive oxygen species sensitize or activate sensory C-fibers which are capable to induce cough. It was hypothesized that oxidative stress in the airways might contribute to the cough severity in asthma. Exhaled breath condensate samples were collected in ten healthy and 26 asthmatic subjects. The concentration of 8-isoprostane was measured. In addition, the subjects filled in Leicester Cough Questionnaire and underwent cough provocation tests with dry air hyperpnoea and hypertonic saline, among other measurements. Among the asthmatic subjects, high 8-isoprostane was associated with severe cough response to hyperpnoea (p=0.001), low Leicester Cough Questionnaire values (indicating severe subjective cough, p=0.02), and usage of combination asthma drugs (p=0.03-0.04). However, the 8-isoprostane concentrations did not differ significantly between the healthy and the asthmatic subjects. Airway oxidative stress may be associated with experienced cough severity and measured cough sensitivity in asthma.

Effect of exposure to detergents and other chemicals on biomarkers of pulmonary response in exhaled breath from hospital cleaners: a pilot study

PURPOSE

The main aim of the study was to provide evidence whether professional cleaning was associated with biomarkers of lung damage in non-invasively collected biological fluids (exhaled air and exhaled breath condensate--EBC).

MATERIALS AND METHODS

This cross-sectional study involved 40 cleaners regularly exposed to cleaning detergents and 40 controls. The subjects completed a standard questionnaire from European Community Respiratory Health Survey (ECRHS II) and underwent a spirometry. Fractional exhaled nitric oxide (F(E)NO) was measured online, and pH, ammonium (NH(4) (+)), H(2)O(2) and 4-hydroxynonenal (4-HNE) were assayed in EBC.

RESULTS

Among the cleaners, the frequency of asthma and rhinitis was, respectively, 2.5 and 20%. The most frequently reported symptoms were sneezing (27.5%), nasal and/or pharyngeal pruritus (25%), ocular pruritus (22.5%) and cough (22.5%). There were no significant differences in comparison with the control group. Median F(E)NO levels were higher in African than in Caucasian cleaners (21.5 [16.5-30.0] ppb and 18.0 [13.5-20.5] ppb; p < 0.05). H(2)O(2)-EBC (0.26 [0.09-0.53] μM vs. 0.07 [0.04-0.15] μM; p < 0.01), NH(4) (+)-EBC (857 [493-1,305] μM vs. 541 [306-907] μM; p < 0.01) and pH-EBC (8.17 [8.09-8.24] vs. 8.06 [7.81-8.10]; p < 0.01) were higher in the cleaners than in the controls. Finally, the cleaners showed significant correlations between pH-EBC and NH(4) (+)-EBC (r = 0.33, p < 0.05) and a weak correlation between 4-HNE-EBC and H(2)O(2)-EBC (r = 0.37, p < 0.05).

CONCLUSION

The promising role of EBC analysis in biomonitoring of exposed workers was confirmed. It was also possible to identify the potential biomarkers of exposure to alkaline products (increased ammonium-EBC and pH-EBC levels) and potential biomarkers of oxidative stress (increased H(2)O(2)-EBC levels correlated with 4-HNE-EBC levels) in workers with no signs of airway diseases.

Comparison of metabolites in exhaled breath and bronchoalveolar lavage fluid samples in a mouse model of asthma

BACKGROUND

A multi-capillary column ion mobility spectrometer (MCC/IMS) was developed to provide a method for the noninvasive diagnosis of lung diseases. The possibility of measuring the exhaled breath of mice was evaluated previously. The aim of the present study was to reveal whether mice affected by airway inflammation can be identified via MCC/IMS.

METHODS

Ten mice were sensitized and challenged with ovalbumin to induce allergic airway inflammation. The breath and volatile compounds of bronchoalveolar lavage fluid (BALF) were measured by MCC/IMS. Furthermore, histamine, nitric oxide, and arachidonic acid were determined as inflammatory markers in vitro.

RESULTS

Six volatile molecules were found in the BALF headspace at a significantly higher concentration in mice with airway inflammation compared with healthy animals. The concentration of substances correlated with the numbers of infiltrating eosinophilic granulocytes. However, substances showing a significantly different concentration in the BALF headspace were not found to be different in exhaled breath. Histamine and nitric oxide were identified by MCC/IMS in vitro but not in the BALF headspace or exhaled breath.

CONCLUSION

Airway inflammation in mice is detectable by the analysis of the BALF headspace via MCC/IMS. Molecules detected in the BALF headspace of asthmatic mice at a higher concentration than in healthy animals may originate from oxidative stress induced by airway inflammation. As already described for humans, we found no correlation between the biomarker concentration in the BALF and the breath of mice. We suggest using the model described here to gain deeper insights into this discrepancy.

Delayed asthmatic response to bronchial challenge with allergen-mediators, eicosanoids, eosinophil and neutrophil constituents in the blood and urine

BACKGROUND

In patients with allergic bronchial asthma, different immunologic mechanisms may participate and lead to different types of asthmatic response to allergen challenge, such as immediate/early (IAR/EAR), late (LAR) or delayed asthmatic response (DYAR).

OBJECTIVES

In 55 of 397 asthmatics, DYAR has been recorded (p < 0.001) and confirmed by repeated bronchial challenge with the same allergen (p < 0.001). DYAR began between 26 and 32 h, reached a maximum between 32 and 48 h and resolved within 56 h after the challenge. DYAR was associated with various clinical symptoms and diagnostic parameters having diverged from those recorded during the IARs/EARs and LARs.

METHODS

In 25 of 55 patients, repeated DYAR has been supplemented with the recording of leukotriene B(4) (LTB(4)), LTC(4), LTE(4), prostaglandin D(2) (PGD(2)), PGE(2), PGF(2)(α), thromboxane B(2), lipoxin A(4), eosinophil cationic protein, eosinophil-derived neurotoxin/eosinophil protein X, eosinophilic peroxidase, myeloperoxidase, histamine and tryptase in peripheral blood, and of LTC(4), thromboxane B(2), eosinophil-derived neurotoxin and 9α,11β-PGF(2) in urine, before and up to 72 h after the bronchial allergen challenge, by means of enzyme-linked immunoassay (ELISA/EIA) or ImmunoCAP.

RESULTS

DYAR was accompanied by a significant increase in the plasma concentrations of LTB(4) (p < 0.05) and myeloperoxidase (p < 0.05) at 24, 36 and 48 h after the challenge, whereas the plasma/serum or urine concentrations of the other factors did not demonstrate any significant changes (p > 0.05).

CONCLUSIONS

These results would indicate an active and prominent involvement of neutrophils, in addition to the previously demonstrated role of the Th1 lymphocytes, in the clinical DYAR.