Increased nitrotyrosine in exhaled breath condensate in cystic fibrosis

Human Breath Odors and Their Use in Diagnosis

Humans emit a complex array of volatile and nonvolatile molecules that are influenced by an individual's genetics, health, diet, and stress. Olfaction is the most ancient of our distal senses and may be used to evaluate food and environmental toxins as well as recognize kin and potential predators. Many body odors evolved to be olfactory messengers, which convey information between individuals. Consequently, those practicing the healing arts have used olfaction to aid in their diagnosis of disease since the dawn of medical practice. Studies using modern instrumental analyses have focused upon analysis of breath volatiles for biomarkers of internal diseases. In these studies, a subject's oral health status appears to seldom be considered. However, saliva and properly collected alveolar air samples must pass over or come in contact with the posterior dorsal surface of the tongue, a site of bacterial plaque development and source of halitosis-related volatiles. Because of our basic research into the nature of human body odors, our lab has received referrals of people with idiopathic malodor production, from either the oral cavity or body. We developed a protocol to help differentiate individuals with chronic halitosis from those with the genetic, odor-producing metabolic disorder trimethylaminuria (TMAU). In our referred population, TMAU is the largest cause of undiagnosed body odor. Many TMAU-positive individuals present with oral symptoms of dysguesia and halitosis as well as body odor. We present data regarding the presentation of our referred subjects as well as the analytical results from a small number of these subjects regarding their oral levels of halitosis-related malodorants and trimethylamine.

Antioxidants in cystic fibrosis. Conclusions from the CF antioxidant workshop, Bethesda, Maryland, November 11-12, 2003

Although great strides are being made in the care of individuals with cystic fibrosis (CF), this condition remains the most common fatal hereditary disease in North America. Numerous links exist between progression of CF lung disease and oxidative stress. The defect in CF is the loss of function of the transmembrane conductance regulator (CFTR) protein; recent evidence that CFTR expression and function are modulated by oxidative stress suggests that the loss may result in a poor adaptive response to oxidants. Pancreatic insufficiency in CF also increases susceptibility to deficiencies in lipophilic antioxidants. Finally the airway infection and inflammatory processes in the CF lung are potential sources of oxidants that can affect normal airway physiology and contribute to the mechanisms causing characteristic changes associated with bronchiectasis and loss of lung function. These multiple abnormalities in the oxidant/antioxidant balance raise several possibilities for therapeutic interventions that must be carefully assessed.

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.

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

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

Variability of nitric oxide metabolites in exhaled breath condensate

The collection of exhaled breath condensate (EBC) is simple and non-invasive, however, there are few data on the methodological aspects affecting concentrations of compounds in EBC. The aim of this study was to investigate methodological issues for measuring nitric oxide metabolites (NO(x)) in EBC. Twenty-five healthy adults (12 females, age range 23-55 years) and 22 children (11 females, age range 7-6 years) were recruited for studies investigating inter- and intra-day repeatability, repeatability with controlled expiratory flows and temperature, flow dependence, and analytical variability of EBC NO(x). Both intra- and inter-day repeatability was poor with a coefficient of repeatability of 103.4% of the mean difference between intra-day (15 min) measures and 118.6% of inter-day (24 h) differences. Repeatability was not improved when expiratory flow and temperature of the collection device were controlled. However, some of the variability (approximately 50%) may be accounted for by variability in the analytical technique (analytical variability) and this may result from difficulties in controlling for contamination. NO(x) levels were not affected by different expiratory flows in either adults or children but there was still significant variation within individuals. Levels of NO(x) in EBC seem to be highly variable and this needs to be considered if EBC NO(x) is to be used in clinical studies.

Decreased systemic bioavailability of L-arginine in patients with cystic fibrosis

Background

L-arginine is the common substrate for nitric oxide synthases and arginases. Increased arginase levels in the blood of patients with cystic fibrosis may result in L-arginine deficiency and thereby contribute to low airway nitric oxide formation and impaired pulmonary function.

Methods

Plasma amino acid and arginase levels were studied in ten patients with cystic fibrosis before and after 14 days of antibiotic treatment for pulmonary exacerbation. Patients were compared to ten healthy non-smoking controls.

Results

Systemic arginase levels measured by ELISA were significantly increased in cystic fibrosis with exacerbation compared to controls (17.3 ± 12.0 vs. 4.3 ± 3.4 ng/ml, p < 0.02). Arginase levels normalized with antibiotic treatment. Plasma L-arginine was significantly reduced before (p < 0.05) but not after treatment. In contrast, L-ornithine, proline, and glutamic acid, all downstream products of arginase activity, were normal before, but significantly increased after antibiotic therapy. Bioavailability of L-arginine was significantly reduced in cystic fibrosis before and after exacerbation (p < 0.05, respectively).

Conclusion

These observations provide further evidence for a disturbed balance between the L-arginine metabolic pathways in cystic fibrosis.

Vitamins and respiratory disease: antioxidant micronutrients in pulmonary health and disease

The lungs are continually exposed to relatively-high O(2) tensions, and as such, in comparison with other organs, they represent a unique tissue for the damaging effects of oxidant attack. At particular times during a lifetime this every day challenge may increase exponentially. The first oxidative insult occurs at birth, when cells are exposed to a sudden 5-fold increase in O(2) concentration. Thereafter, the human lung, from infancy through to old age, can be subjected to deleterious oxidative events as a consequence of inhaling environmental pollutants or irritants, succumbing to several pulmonary diseases (including infant and adult respiratory distress syndromes, asthma, chronic obstructive pulmonary disease, cystic fibrosis and cancer) and receiving treatment for these diseases. The present paper will review the concept that consumption of a healthy diet and the consequent ability to establish and then maintain adequate micronutrient antioxidant concentrations in the lung throughout life, and following various oxidative insults, could prevent or reduce the incidence of oxidant-mediated respiratory diseases. Furthermore, the rationale, practicalities and complexities of boosting the antioxidant pool of the respiratory-tract lining fluid in diseases in which oxidative stress is actively involved, by direct application to the lung v. dietary modification, in order to achieve a therapeutic effect will be discussed.

Activation of TLR-9 induces IL-8 secretion through peroxynitrite signaling in human neutrophils

Bacterial DNA containing unmethylated CpG motifs is emerging as an important regulator of functions of human neutrophil granulocytes (polymorphonuclear leukocytes (PMN)). These motifs are recognized by TLR-9. Recent studies indicate that peroxynitrite (ONOO-) may function as an intracellular signal for the production of IL-8, one of the key regulators of leukocyte trafficking in inflammation. In this study we investigated whether bacterial DNA (CpG-DNA) could induce ONOO- signaling in human PMN. Human whole blood, isolated PMN (purity, >95%), and high purity (>99%) PMN respond to CpG-DNA, but not to calf thymus DNA, with secretion of IL-8 and, to a lesser extent, IL-6 and TNF. Methylation of cytosines in CpG-DNA resulted in a complete loss of activity. The endosomal acidification inhibitors, bafilomycin A and chloroquine, inhibited CpG-DNA-induced cytokine release from PMN. CpG-DNA-induced IL-8 mRNA expression and release was also blocked by the NO synthase inhibitor Nomega-nitro-L-arginine methyl ester. CpG-DNA evoked concomitant increases in intracellular superoxide and NO levels, leading to enhanced ONOO- formation and, consequently, nuclear accumulation of c-Fos and NF-kappaB. Pharmacological inhibition of NF-kappaB activation attenuated approximately 75% of CpG-DNA-evoked IL-8 release. These results identify ONOO- -dependent activation of NF-kappaB and c-Fos as an important mechanism that mediates PMN responses, including IL-8 gene expression and release, to bacterial DNA and unmethylated CpG motifs in particular. Enhanced ONOO- formation represents a mechanism by which bacterial DNA may contribute to prolongation and amplification of the inflammatory response.

Reactive nitrogen species in the respiratory tract

Endogenous Nitric Oxide (NO) plays a key role in the physiological regulation of airway functions. In response to various stimuli activated inflammatory cells (e.g., eosinophils and neutrophils) generate oxidants ("oxidative stress") which in conjunction with exaggerated enzymatic release of NO and augmented NO metabolites produce the formation of strong oxidizing reactive nitrogen species, such as peroxynitrite, in various airway diseases including asthma, chronic obstructive pulmonary diseases (COPD), cystic fibrosis and acute respiratory distress syndrome (ARDS). Reactive nitrogen species provoke amplification of inflammatory processes in the airways and lung parenchyma causing DNA damage, inhibition of mitochondrial respiration, protein dysfunction and cell damage ("nitrosative stress"). These effects alter respiratory homeostasis (such as bronchomotor tone and pulmonary surfactant activity) and the long-term persistence of "nitrosative stress" may contribute to the progressive deterioration of pulmonary functions leading to respiratory failure. Recent studies showing that protein nitration can be dynamic and reversible ("denitration mechanisms") open new horizons in the treatment of chronic respiratory diseases affected by the deleterious actions of "nitrosative stress".

3-Nitrotyrosine, a marker of nitrosative stress, is increased in breath condensate of allergic asthmatic children

BACKGROUND

Asthmatic patients have high exhaled nitric oxide (NO) levels. NO-mediated inflammatory actions are mainly due to NO conversion into reactive nitrogen species, which can lead to nitrotyrosine formation. The aim of this study was to assess 3-nitrotyrosine (3-NT) levels in exhaled breath condensate (EBC) of asthmatic and healthy children and to investigate whether there is any relationship with exhaled NO (FE(NO)) and lung function.

METHODS

The study included 20 asthmatic children (10 steroid-naive with intermittent asthma, 10 steroid-treated with unstable persistent asthma) and 18 healthy controls. They underwent FE(NO) measurement, EBC collection and spirometry. 3-NT was measured by a new liquid chromatography-tandem mass spectrometry (LC-MS/MS) method in isotopic dilution.

RESULTS

The median EBC concentration of 3-NT (expressed as nitrotyrosine/tyrosine ratio x 100) in asthmatic children was fivefold higher than in healthy subjects [0.23% (0.12-0.32) vs 0.04% (0.02-0.06), P < 0.001] with no difference between steroid-naive and unstable steroid-treated asthmatic patients. FE(NO) levels were higher in asthmatic [44.6 ppb (36.0-66.0)] than in healthy children [7.5 ppb (6.0-8.8), P < 0.001]. No correlation was found among 3-NT, FE(NO) and lung function parameters.

CONCLUSION

Nitrotyrosine is high in EBC of asthmatic children and could be considered as a noninvasive marker of nitrosative events in the airways.

Flunisolide decreases exhaled nitric oxide and nitrotyrosine levels in asthmatic children

BACKGROUND

Exhaled nitric oxide (FeNO) has been reported to be elevated in the oxidative stress involved in asthmatic patients, and the reaction of nitric oxide (NO) with superoxide anions results in the formation of nitrotyrosine. The purpose of this study was to investigate the effect of inhaled steroid treatment on nitrotyrosine levels collected by exhaled breath condensate (EBC) and on FeNO.

METHODS

This was a single-blind placebo-controlled study. The lung function, FeNO, and nitrotyrosine levels were evaluated in 10 asthmatic children.

RESULTS

The nitrotyrosine levels were stable during the placebo period (T0 = 1.16 ng/ml versus T1 = 1.05 ng/ml; NS.), whereas they decreased after the treatment with flunisolide (T2 = 1.14 ng/ml versus T3 = 0.88 ng/ml; P < .001). No significant reduction in FeNO levels was observed after placebo treatment (T0 = 38.4 ppb versus T1 = 34.7 ppb, NS.). In contrast, FeNO values decreased significantly being at T3 = 14.9 ppb (T1 versus T3; P = .024).

CONCLUSIONS

This study shows that corticosteroid treatment reduces nitrotyrosine levels in EBC of asthmatic subjects.

Selective quantification of free 3-nitrotyrosine in exhaled breath condensate in asthma using gas chromatography/tandem mass spectrometry

Reactive nitrogen species can cause oxidative modifications of certain amino acid residues in proteins, notably the modification of tyrosine to 3-nitrotyrosine (3-NT), which is a potentially useful marker of oxidative stress. Since lung diseases are associated with airway inflammation and oxidative stress, quantification of 3-NT in exhaled breath condensate (EBC) may provide a non-invasive means for monitoring ongoing inflammatory processes. 3-NT-like immunoreactivity has previously been detected in EBC, but no definitive evidence for the presence of 3-NT in EBC is available. Here, a method based on gas chromatography/negative ion chemical ionization/tandem mass spectrometry was established for the quantification of free 3-NT in EBC. The detection limit was 0.56 pM (corresponding to 3.0 amol microl(-1) sample injected) and the method was found to give linear results (r2 > 0.999) in the concentration range of 0-5.0 nM. The coefficient of variation (CV) for within-day and between-day precision were 11 and 12%, respectively. No artifactual nitration was observed during sample processing. The method was applied to study subjects with asthma (n = 8), and healthy subjects (n = 10), but only a slight non-significant increase in 3-NT levels was found in the former group (median [interquartile ranges]; 99 [50-547] amol s(-1) vs. 75 [35-147] amol s(-1)). No correlation with exhaled nitric oxide (NO), pulmonary function or EBC levels of total protein was observed. The 3-NT levels were much lower compared to previously reported levels, based on immunochemical measurements. The method does not allow the simultaneous quantification of tyrosine in samples.

Circulating markers to assess nutritional therapy in cystic fibrosis

Cystic fibrosis (CF) is the most commonly occurring lethal autosomal recessive disorder. The gene defect causes defective sodium and chloride transport across epithelial cells of the respiratory, hepatobiliary, gastrointestinal and reproductive tracts, resulting in thick mucus secretions. In the respiratory tract, mucus traps bacteria, causing repeated lung infections, progressive bronchiectasis and eventual death due to respiratory failure. In the gastrointestinal tract, mucus prevents pancreatic enzymes reaching the gut, leading to nutrient malabsorption. Careful nutritional management has a dramatic effect on growth and survival rates in CF. Appropriate nutritional support includes pancreatic enzyme replacement therapy, a high-fat/high-energy diet and essential nutrient supplementation, specifically fat-soluble vitamins and essential fatty acids (EFA). Long-term studies are required to examine the effects of nutritional interventions on key clinical outcomes in CF, such as the rate of decline of lung function. The use of circulating markers to assess the influence of nutritional therapy allows short-term intervention studies to predict the potential for clinical improvements. This article provides an overview of the biomarkers useful in the prediction of the efficacy of nutritional therapy on improvements in quality and quantity of life in CF.

Nitric oxide and pulmonary arterial pressures in pulmonary hypertension

Decreased production of vasodilator substances such as nitric oxide (NO) has been proposed as important in development of pulmonary arterial hypertension (PAH). We hypothesize that NO measured over time serves as a non invasive marker of severity of PAH and response to therapy. We prospectively and serially measured exhaled NO and carbon monoxide (CO), a vasodilator and anti-inflammatory product of heme oxygenases, in 17 PAH patients in conjunction with hemodynamic parameters over 2 years. Although pulmonary artery pressures and NO were similar in all patients at entry to the study, NO increased in the 12 individuals who survived to complete the study, and correlated with change in pulmonary artery pressures. In contrast, CO did not change or correlate with hemodynamic parameters. Investigation of NO-oxidant reaction products in PAH in comparison to controls suggests that NO synthesis is impaired in the lung and that reactive oxygen species may be involved in the pathophysiology of pulmonary hypertension. Endogenous NO is inversely related to pulmonary artery pressure in PAH, with successful therapy of PAH associated with increase in NO.

Breath condensate pH in children with cystic fibrosis and asthma: a new noninvasive marker of airway inflammation?

STUDY OBJECTIVES

The noninvasive assessment and monitoring of airway inflammation could be important in respiratory disease. The pH of exhaled breath condensate (EBC) is a promising marker. Although pH has been measured in the EBC of adults with inflammatory airway diseases, no study has measured this in children.

DESIGN

This study aimed to assess whether there is a change in pH in the EBC of children with cystic fibrosis (CF) and asthma, and to try to determine whether pH could be used as a marker of airway inflammation. Furthermore, the relationships among EBC pH, severity of disease, and oxidative stress were studied.

PATIENTS AND METHODS

We studied 20 children with CF (mean [+/- SEM] age, 7 +/- 3 years), 20 children with asthma (mean age, 7 +/- 2 years), and 15 age-matched healthy children (mean age, 7 +/- 2 years). The pH of EBC was measured using a pH meter.

MEASUREMENTS AND RESULTS

Lower pH values were observed in the EBC of children with CF and asthma compared to control subjects (mean pH, 7.23 +/- 0.03 and 7.42 +/- 0.01 vs 7.85 +/- 0.02, respectively). Furthermore, relationships among EBC pH, severity of asthma, and the presence of an infective exacerbation of CF was found. There was a negative correlation between exhaled pH and exhaled leukotriene B(4) concentrations (r = -0.5; p < 0.005).

CONCLUSION

We conclude that the measurement of EBC pH may be useful in the evaluation of airway inflammation in children with asthma and CF.

Exhaled nitric oxide in children with asthma receiving Xolair (omalizumab), a monoclonal anti-immunoglobulin E antibody

OBJECTIVE

To evaluate the effect of a humanized monoclonal antibody to immunoglobulin E, omalizumab (Xolair, Novartis Pharmaceuticals, East Hanover, NJ; Genentech Inc, South San Francisco, CA), on airway inflammation in asthma, as indicated by the fractional concentration of exhaled nitric oxide (FE(NO)), a noninvasive marker of airway inflammation. Xolair was approved recently by the US Food and Drug Administration for moderate-to-severe allergic asthma in adolescents and adults.

STUDY DESIGN

As an addendum at 2 sites to a randomized, multicenter double-blind, placebo-controlled trial, FE(NO) was assessed in children with allergic asthma over 1 year. There were 3 consecutive study periods: 1) stable dosing of inhaled beclomethasone dipropionate (BDP) when the dose was optimized (period of 16 weeks); 2) inhaled steroid-reduction phase (period of 12 weeks), during which BDP was tapered if subjects remained stable; and 3) open-label extension phase, during which subjects receiving placebo were switched to active omalizumab (period of 24 weeks). The primary outcome was area under the FE(NO) versus time curve (AUC) for adjusted FE(NO), defined as the ratio of FE(NO) at each time point compared with the value at baseline.

RESULTS

Twenty-nine subjects participated and were randomized to omalizumab (n = 18) and placebo (n = 11) treatment groups in a 2:1 ratio dictated by the main study. There was a significant difference for age, resulting in a difference in absolute forced expiratory volume in 1 second but no difference in asthma severity based on the forced expiratory volume in 1 second percentage predicted. Baseline BDP dose was comparable between groups, as were baseline values of mean FE(NO) (active: 38.6 +/- 25.6 ppb; placebo: 52.7 +/- 52.9 ppb). The degree of BDP dose reduction during the steroid-reduction and open-label phases was equivalent between the omalizumab and placebo-treated groups; subjects in the omalizumab- and placebo-treated groups had reduced their BDP dose by an average of 51% and 60%, respectively, at the end of the steroid-reduction phase and by 68% and 94%, respectively, by the end of the open-label period. In the active and placebo groups, 44% and 27% and 75% and 73% of subjects had stopped use of inhaled corticosteroids at the end of the steroid-reduction and open-label phases, respectively. There was no significant difference between the active and placebo groups during the steroid-stable phase for AUC of adjusted nitric oxide (1.31 +/- 1.511 vs 1.45 +/- 0.736). However, during the steroid-reduction phase, the variability of adjusted FE(NO) in the placebo-treated group was greater than that of the omalizumab-treated group at most visits, with a significant difference between groups for AUC of adjusted nitric oxide (0.88 +/- 0.69 vs 1.65 +/- 1.06). FE(NO) fell from 82.1 +/- 55.6 ppm at the end of the steroid-reduction phase to 33.3 +/- 21.6 ppb at the end of the open-label period in the placebo group who were placed on active omalizumab. This decrease occurred while the mean dose of BDP remained very low. Analysis of FE(NO) over 52 weeks of omalizumab treatment in the active group demonstrated that there was a significant reduction from baseline to the end of the open-label period (41.9 +/- 29.0 to 18.0 +/- 21.8 ppb) despite a high degree of steroid reduction.

CONCLUSION

In this preliminary study based on FE(NO), a noninvasive marker of airway inflammation, treatment with omalizumab may inhibit airway inflammation during steroid reduction in children with allergic asthma. The degree of inhibition of FE(NO) was similar to that seen for inhaled corticosteroids alone, suggesting an antiinflammatory action for this novel therapeutic agent in asthma. This is in keeping with recent evidence that omalizumab inhibits eosinophilic inflammation in induced sputum and endobronchial tissue.

Noninvasive biomarkers of airway inflammation in cystic fibrosis

PURPOSE OF REVIEW

Airway inflammation plays a central role in the lung disease of cystic fibrosis (CF). Biomarkers of inflammation may be useful for monitoring disease progression and evaluating response to therapy. Much of our knowledge of the chronic inflammatory process in the CF airway derives from studies of bronchoscopy and bronchoalveolar lavage. A number of noninvasive approaches have been recently developed to more readily assess airway inflammation including sputum induction, collection of exhaled air, analysis of systemic markers of inflammation, and computed tomography imaging.

RECENT FINDINGS

While measurements of biomarkers of inflammation continue to advance our understanding of the underlying disease process, there is as yet no established role for these markers in clinical practice. This review summarizes the current state of knowledge of various inflammatory markers relevant to CF lung disease, with an eye towards application as surrogate outcome measures in CF clinical trials.

SUMMARY

It is hoped that biomarkers obtained by noninvasive means will be useful in determining specific pathways of injury (ie, oxidative or proteolytic) in individual persons with CF and in assessing response to antiinflammatory treatments.

Elemental and ion composition of exhaled AIR condensate in cystic fibrosis

BACKGROUND

In cystic fibrosis (CF) the exact ion composition of the airway surface fluid is still debated and it is not clear if it differs from healthy subjects. The air that we exhale contains small droplets, which are generated by shear forces from the airway surface fluid and very likely mirror its ion composition. We hypothesized that differences between CF-patients and healthy controls would be reflected by differences in their exhaled air.

METHODS

In nasally collected exhaled breath condensate from 20 children and young adults with cystic fibrosis and 20 healthy subjects, the elements and anions were determined by optical emission spectroscopy and ion-exchange chromatography.

RESULTS

The concentrations of the major components Na and Cl- did not differ, Zn was higher and NO3- was lower in CF-patients. During a given time period, CF-patients produced a slightly larger volume of breath condensate and they exhaled more Na, K and Zn. Fluoride was detected in half of all samples, whereas copper, iron, magnesium, phosphorus and sulfur were present only sporadically, with no differences.

CONCLUSIONS

These data detail the composition of exhaled breath condensate and suggest a similar Na and Cl- concentration in CF-airway surface fluid as in healthy subjects.

Exhaled nitric oxide increases following admission for intravenous antibiotics in children with cystic fibrosis

BACKGROUND

Lack of standardisation for the measurement of exhaled nitric oxide (NO) (FENO) has resulted in conflicting data in cystic fibrosis (CF). The aim of this study was to assess whether FENO is a useful non-invasive marker of lung disease in CF by assessing the effect of intravenous (IV) antibiotics on FENO.

METHODS

FENO was measured on line, according to recently published ERS/ATS guidelines, using a chemiluminescence analyser together with pulmonary function in 14 CF children prior to and following a course of IV antibiotics.

RESULTS

There was a significant improvement in mean (S.E.M.) % FEV1 from 60.0 (6.3) to 68.0 (5.4) (P < 0.05) and mean (S.E.M.) % FVC from 66.3 (5.5) to 75.1 (4.9) (P < 0.01). FENO increased significantly from median (range) 5.8 (2.0-14.3) to 9.2 ppb (0.8-25.1) (P < 0.05). There was no correlation between FE(NO) and lung function. Subgroup analysis on those with chronic Pseudomonas aeruginosa infection (n = 6) demonstrated no significant change in FENO.

CONCLUSIONS

Using a flow of 50 ml/s, FENO increases following admission for IV antibiotic treatment in children with CF but does not correlate with lung function. It is not a useful marker of lung diseases in CF, which has implications for clinical practice.

Nitric oxide metabolites are not reduced in exhaled breath condensate of patients with primary ciliary dyskinesia

STUDY OBJECTIVES

To investigate whether nitric oxide (NO) metabolites would be reduced in children affected by primary ciliary dyskinesia (PCD).

DESIGN

Single-center observational study.

PATIENTS

Fifteen children with PCD (seven boys; mean [+/- SEM] age, 10.3 +/- 0.7 years; mean FEV(1), 73 +/- 2.1% predicted) were recruited along with 14 healthy age-matched subjects (seven boys; mean age, 11.5 +/- 0.4 years; mean FEV(1), 103 +/- 5% predicted).

INTERVENTIONS

We assessed the levels of nitrite (NO(2)(-)), NO(2)(-)/NO(3)(-) (NO(2)(-)/NO(3)(-)), and S-nitrosothiol in exhaled breath condensate, exhaled NO, and nasal NO from children with PCD compared to those in healthy children.

MEASUREMENTS AND RESULTS

The mean exhaled and nasal NO levels were markedly decreased in children with PCD compared to those without PCD (3.2 +/- 0.2 vs 8.5 +/- 0.9 parts per billion [ppb], respectively [p < 0.0001]; 59.6 +/- 12.2 vs 505.5 +/- 66.8 ppb, respectively [p < 0.001]). Despite the lower levels of exhaled NO in children with PCD, no differences were found in the mean levels of NO(2)(-) (2.9 +/- 0.4 vs 3.5 +/- 0.3 microM, respectively), NO(2)(-)/NO(3)(-) (35.2 +/- 5.0 vs 34.3 +/- 4.5 microM, respectively), or S-nitrosothiol (1.0 +/- 0.2 vs 0.6 +/- 0.1 microM, respectively) between children with PCD and healthy subjects.

CONCLUSION

These findings suggest that NO synthase activity may not be decreased as much as might be expected on the basis of low exhaled and nasal NO levels.

Superoxide dismutases in the lung and human lung diseases

The lungs are directly exposed to higher oxygen concentrations than most other tissues. Increased oxidative stress is a significant part of the pathogenesis of obstructive lung diseases such as asthma and chronic obstructive pulmonary disease, parenchymal lung diseases (e.g., idiopathic pulmonary fibrosis and lung granulomatous diseases), and lung malignancies. Lung tissue is protected against these oxidants by a variety of antioxidant mechanisms among which the superoxide dismutases (SODs) are the only ones converting superoxide radicals to hydrogen peroxide. There are three SODs: cytosolic copper-zinc, mitochondrial manganese, and extracellular SODs. These enzymes have specific distributions and functions. Their importance in protecting lung tissue has been confirmed in transgenic and knockout animal studies. Relatively few studies have been conducted on these enzymes in the normal human lung or in human lung diseases. Most human studies suggest that there is induction of manganese SOD and, possibly, extracellular SOD during inflammatory, but not fibrotic, phases of parenchymal lung diseases and that both copper-zinc SOD and manganese SOD may be downregulated in asthmatic airways. Many previous antioxidant therapies have been disappointing, but newly characterized SOD mimetics are being shown to protect against oxidant-related lung disorders in animal models.

Increased leukotriene B4 and interleukin-6 in exhaled breath condensate in cystic fibrosis

Chronic neutrophilic airway inflammation is an important feature of cystic fibrosis (CF). Noninvasive inflammatory markers may be useful in monitoring CF. Leukotriene B4 (LTB4) and interleukin (IL)-6 are inflammatory mediators that are increased in chronic neutrophilic inflammation. The aim of this study was to assess whether LTB4 and IL-6 were increased in exhaled breath condensate of CF patients and whether they could be used to monitor inflammation. Twenty patients with CF (13 males, age of 28 +/- 9 years) were recruited together with 15 age-matched healthy subjects (8 males, age 35 +/- 7 years). LTB4 and IL-6 levels were markedly elevated in patients with acute exacerbations (28.8 +/- 4.3 and 8.7 +/- 0.4 pg/ml) compared with control subjects (6.8 +/- 0.7 and 2.6 +/- 0.1 pg/ml, p < 0.0001). We also observed a decrease of exhaled LTB4 and IL-6 concentrations after antibiotic treatment in six patients who were followed until clinically stable (31.1 +/- 4.4 and 9.5 +/- 0.4 pg/ml vs. 18.8 +/- 0.8 and 6.4 +/- 0.2 pg/ml, respectively) and an increase in 15 CF patients infected with Pseudomonas aeruginosa (34.3 +/- 5.0 and 9.3 +/- 0.3 pg/m) compared with those infected with other bacteria (18.3 +/- 0.7 and 6.9 +/- 0.5 pg/ml). These findings suggest that LTB4 and IL-6 levels are increased in exhaled breath condensate of patients with CF during exacerbation and could be used to monitor airway inflammation in these patients.

Nitric oxide, nitrotyrosine, and nitric oxide modulators in asthma and chronic obstructive pulmonary disease

Nitric oxide (NO), a simple free-radical gas, elicits a diverse range of physiologic and pathophysiologic effects, and plays an important role in pulmonary diseases. Nitrosative stress and nitration of proteins in airway epithelium may be responsible for steroid resistance in asthma and their ineffectiveness in chronic obstructive pulmonary disease (COPD), supporting the potential role of future therapeutic strategies aimed at regulating NO synthesis in asthma and COPD. In this article, we review the potential role of NO modulators (NO synthase inhibitors and NO donors), which, if given on a regular basis, may have clinical benefit in asthma and COPD.

Nitric oxide in respiratory diseases

The formation and modulation of nitric oxide (NO) in the lungs is reviewed. Its beneficial and deleterious roles in airways diseases, including asthma, chronic obstructive pulmonary disease, and cystic fibrosis, and in animal models is discussed. The pharmacological effects of agents that modulate NO production or act as NO donors are described. The clinical pharmacology of these agents is described and the therapeutic potential for their use in airways disease is considered.

Oxidative stress in airways: is there a role for extracellular superoxide dismutase?

Airways are exposed to high levels of environmental oxidants, yet they also have enriched extracellular antioxidants. Airways disease such as asthma, cystic fibrosis, and chronic obstructive pulmonary disease have evidence of increased oxidative stress, suggesting that reactive oxygen and nitrogen species may overwhelm antioxidant defenses in airway diseases. Extracellular superoxide dismutase is abundant in pulmonary tissues and protects the lung from increased oxidative stress; however, its role in asthma and other airway diseases has not been fully elucidated. Proteolytic processing of extracellular superoxide dismutase decreases its affinity for the extracellular matrix and may be a mechanism to regulate its distribution during conditions of inflammation or oxidative stress.

Exhaled breath condensate: an evolving tool for noninvasive evaluation of lung disease

Exhaled breath condensate (EBC) contains aerosolized airway lining fluid and volatile compounds that provide noninvasive indications of ongoing biochemical and inflammatory activities in the lung. Rapid increase in interest in EBC has resulted from the recognition that in lung disease this easily sampled fluid has measurable characteristics that differ prominently from health. These assays have provided evidence of airway and lung redox deviation, acid-base status, and degree and type of inflammation in acute and chronic asthma, chronic obstructive pulmonary disease, adult respiratory distress syndrome, occupational diseases, and cystic fibrosis. Characterized by uncertain and variable degrees of dilution, EBC does not provide precise assessment of individual solute concentrations within native airway lining fluid. However, it can provide useful information when concentrations differ substantially between health and disease or are based on ratios of solutes found in the sample. Because they can be used to measure the targets of modern therapy, EBC assays are likely to become integral components of future clinical studies, and after further technical work is accomplished, they might be used to diagnose and monitor therapy in individual patients.

Analysis of exhaled breath condensate for monitoring airway inflammation

Several inflammatory mediators have been identified in the exhaled breath condensate (EBC) that is formed by breathing through a cooling system. Analysis of EBC is a noninvasive method that allows repeat measurements of lung inflammation and is potentially useful for monitoring drug therapy. Characterization of the profiles of exhaled markers could help to discriminate between different inflammatory lung diseases; thus, EBC might be a novel, noninvasive approach to monitoring lung diseases. However, several methodological issues, such as standardization of sample collection and validation of analytical techniques, need to be addressed before this method can be applied clinically. Controlled studies are needed to establish the utility of EBC markers for guiding pharmacological treatment in inflammatory lung diseases.

Indirect monitoring of lung inflammation

The assessment of airway inflammation by non-invasive methods could provide a signal to start anti-inflammatory treatment before the onset of symptoms and the impairment of lung function. It could also be useful in the follow-up of patients with lung disease, and for guiding drug treatment. Measuring inflammatory markers in exhaled breath condensate is potentially the easiest way to quantify lung inflammation. The clinical applicability of this method could facilitate the practice of respiratory medicine.

Biomarkers of some pulmonary diseases in exhaled breath

Analysis of various biomarkers in exhaled breath allows completely non-invasive monitoring of inflammation and oxidative stress in the respiratory tract in inflammatory lung diseases, including asthma, chronic obstructive pulmonary disease (COPD), cystic fibrosis (CF), bronchiectasis and interstitial lung diseases. The technique is simple to perform, may be repeated frequently, and can be applied to children, including neonates, and patients with severe disease in whom more invasive procedures are not possible. Several volatile chemicals can be measured in the breath (nitric oxide, carbon monoxide, ammonia), and many non-volatile molecules (mediators, oxidation and nitration products, proteins) may be measured in exhaled breath condensate. Exhaled breath analysis may be used to quantify inflammation and oxidative stress in the respiratory tract, in differential diagnosis of airway disease and in the monitoring of therapy. Most progress has been made with exhaled nitric oxide (NO), which is increased in atopic asthma, is correlated with other inflammatory indices and is reduced by treatment with corticosteroids and antileukotrienes, but not (beta 2-agonists. In contrast, exhaled NO is normal in COPD, reduced in CF and diagnostically low in primary ciliary dyskinesia. Exhaled carbon monoxide (CO) is increased in asthma, COPD and CF. Increased concentrations of 8-isoprostane, hydrogen peroxide, nitrite and 3-nitrotyrosine are found in exhaled breath condensate in inflammatory lung diseases. Furthermore, increased levels of lipid mediators are found in these diseases, with a differential pattern depending on the nature of the disease process. In the future it is likely that smaller and more sensitive analyzers will extend the discriminatory value of exhaled breath analysis and that these techniques may be available to diagnose and monitor respiratory diseases in the general practice and home setting.