Oxidative stress in chronic obstructive pulmonary disease. Oxidative Stress Study Group

Cytogenetic damage in buccal epithelia and peripheral lymphocytes of young healthy individuals exposed to ozone

Ozone (O(3)) is an important component of air pollution and a potent oxidant of biomolecules. To address the hypothesis that elevated ambient O(3) can induce cytogenetic damage in healthy people, we collected buccal cells from two groups of students (N = 126) from University of California, Berkeley, in the spring and again in the fall. One group spent their summer in the Los Angeles (LA) area where summer O(3) concentrations are significantly higher than in the San Francisco Bay (SF) area, and another remained in SF. During the school year, all students were exposed to low O(3) levels in SF. The micronucleus assay in a total of 611,000 buccal cells demonstrated that, in the fall, micronuclei (MN) in normal cells for the LA group had increased 39% relative to levels in the spring (1.52 and 0.87 MN/1,000 cells, respectively, P = 0.001). Students who spent the summer in SF had a 12.7% increase (P = 0.48). A similar effect of season was seen in degenerated buccal cells for the LA group (3.23 versus 1.88 MN/1,000 cells, P = 0.003). LA but not SF subjects also had more degenerated cells in the fall sample (P = 0.003). These findings were paralleled by an increase in MN and nucleoplasmic bridges in lymphocytes and MN in buccal cells in a sub-group of 15 students who underwent a 4-h controlled exposure to 200 p.p.b. O(3). This cytogenetic evidence, along with recent studies linking O(3) exposure to elevated lung cancer risk and mortality, suggest potential public health implications from exposures to high oxidant environments.

Nitric oxide synthases are associated with bronchial dysplasia

Recent studies suggest that reactive oxygen (ROS) and nitrogen species (RNS) are highly associated with the pathogenesis of cigarette smoke related lung diseases but their role in the malignant conversion of bronchial epithelium is unclear. The immunohistochemical expression of inducible, endothelial and neuronal nitric oxide synthases (iNOS, eNOS and nNOS) and nitrotyrosine as a biomarker of oxidative/nitrosative stress was evaluated in 79 cases including 13 non-smokers, 20 smokers without chronic obstructive pulmonary disease (COPD), 22 with COPD and 24 with metaplasia-dysplasia-sequence of the bronchial epithelium. Normal lung of non-smokers was mainly negative for nitrotyrosine, while it was higher in the alveolar macrophages of cigarette smokers and COPD than in non-smokers (p=0.025, p<0.001), and in the alveolar epithelium of smokers and COPD than in non-smokers (p=0.049). There were no major differences in the nitrotyrosine immunoreactivity between the metaplastic/dysplastic lesions and bronchial epithelium of cigarette smokers. Inducible NOS and nNOS were mainly non-detectable or weak in the normal looking bronchial epithelium of smokers and COPD, whereas metaplasia and dysplasia showed positivity for iNOS (22/24) and nNOS (14/24) in the majority of cases. Strong immunoreactivity for iNOS and nNOS was also found more often in dysplastic than metaplastic (p=0.011 and p=0.049, respectively) specimens. Thus, smoking can cause protein nitration also in normal lung. Prominent iNOS and nNOS immunoreactivity in the metaplasia-dysplasia-lesions suggests a divergent role of NOSs in lung carcinogenesis.

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".

Oxidative stress in asthma and COPD: antioxidants as a therapeutic strategy

Asthma and chronic obstructive pulmonary disease (COPD) are inflammatory lung diseases that are characterized by systemic and chronic localized inflammation and oxidative stress. Sources of oxidative stress arise from the increased burden of inhaled oxidants, as well as elevated amounts of reactive oxygen species (ROS) released from inflammatory cells. Increased levels of ROS, either directly or via the formation of lipid peroxidation products, may play a role in enhancing the inflammatory response in both asthma and COPD. Moreover, in COPD it is now recognized as the main pathogenic factor for driving disease progression and increasing severity. ROS and lipid peroxidation products can influence the inflammatory response at many levels through its impact on signal transduction mechanisms, activation of redox-sensitive transcriptions factors, and chromatin regulation resulting in pro-inflammatory gene expression. It is this impact of ROS on chromatin regulation by reducing the activity of the transcriptional co-repressor, histone deacetylase-2 (HDAC-2), that leads to the poor efficacy of corticosteroids in COPD, severe asthma, and smoking asthmatics. Thus, the presence of oxidative stress has important consequences for the pathogenesis, severity, and treatment of asthma and COPD. However, for ROS to have such an impact, it must first overcome a variety of antioxidant defenses. It is likely, therefore, that a combination of antioxidants may be effective in the treatment of asthma and COPD. Various approaches to enhance the lung antioxidant screen and clinical trials of antioxidant compounds are discussed.

Antioxidant and anti-inflammatory efficacy of NAC in the treatment of COPD: discordant in vitro and in vivo dose-effects: a review

In order to develop efficient therapeutic regimes for chronic obstructive pulmonary disease (COPD), N-acetylcysteine (NAC) has been tested as a medication which can suppress various pathogenic processes in this disease. Besides its well-known and efficient mucolytic action, NAC meets these needs by virtue of its antioxidant and anti-inflammatory modes of action. NAC is a thiol compound which by providing sulfhydryl groups, can act both as a precursor of reduced glutathione and as a direct ROS scavenger, hence regulating the redox status in the cells. In this way it can interfere with several signaling pathways that play a role in regulating apoptosis, angiogenesis, cell growth and arrest and inflammatory response. Overall, the antioxidant effects of NAC are well documented in in vivo and in vitro studies. It successfully inhibits oxidative stress at both high and low concentrations, under acute (in vitro) and chronic administration (in vivo). With regard to its anti-inflammatory action, in contrast, the effects of NAC differ in vivo and in vitro and are highly dose-dependent. In the in vitro settings anti-inflammatory effects are seen at high but not at low concentrations. On the other hand, some long-term effectiveness is reported in several in vivo studies even at low dosages. Increasing the dose seems to improve NAC bioavailability and may also consolidate some of its effects. In this way, the effects that are observed in the clinical and in vivo studies do not always reflect the success of the in vitro experiments. Furthermore, the results obtained with healthy volunteers do not always provide incontrovertible proof of its usefulness in COPD especially when number of exacerbations and changes in lung function are chosen as the primary outcomes. Despite these considerations and in view of the present lack of effective therapies to inhibit disease progression in COPD, NAC and its derivatives, because of their multiple molecular modes of action, remain promising medication once doses and route of administration are optimized.

Oxygen therapy at low flow causes oxidative stress in chronic obstructive pulmonary disease: Prevention by N-acetyl cysteine

Exposure to high oxygen concentration produces toxicity by free radical release. We aimed to study: whether stable chronic obstructive pulmonary disease (COPD) patients present an unbalance in the blood redox status; the effect of oxygen administration on blood redox balance; the efficacy of N-acetyl-cysteine (NAC) treatment against the oxidative stress-induced by oxygen administration and whether it is dose-related. To this, 45 stable state III COPD patients were recruited and reduced glutathione (GSH) and oxidised glutathione (GSSG) in erythrocytes and thiol proteins (P-SH) and carbonyl proteins (PC) in both erythrocytes and plasma were evaluated. All COPD patients underwent 2 l/m oxygen for 18 h and NAC at 1200 or 1800 mg/day or placebo for 48 h starting with oxygen administration. Blood samples were collected at basal conditions, after 8 and 18 h of oxygen administration and 24 h after oxygen withdrawal.

RESULTS

COPD patients present an unstable redox equilibrium mainly due to plasma sulphydryl protein depletion. Oxygen administration oxidize erythrocyte GSH, decrease P-SH and increase PC levels in both plasma and erythrocytes. NAC administration counteract the oxidative stress and at the highest dose completely prevent protein oxidation. In conclusion, stable state III COPD patients present an unstable redox balance; long term low flow oxygen administration induces systemic oxidative stress, which is prevented by NAC treatment.

Genetically increased antioxidative protection and decreased chronic obstructive pulmonary disease

RATIONALE

Increased oxidative stress is involved in chronic obstructive pulmonary disease (COPD); however, plasma and bronchial lining fluid contains the antioxidant extracellular superoxide dismutase. Approximately 2% of white individuals carry the R213G polymorphism in the gene encoding extracellular superoxide dismutase, which increases plasma extracellular superoxide dismutase 10-fold and presumably also renders bronchial lining fluid high in extracellular superoxide dismutase.

OBJECTIVE

We tested the hypothesis that R213G reduces the risk of COPD.

METHODS

We studied cross-sectionally and prospectively (during 24 yr) 9,258 individuals from the Danish general population genotyped for R213G.

MEASUREMENTS

We determined plasma extracellular superoxide dismutase concentration, pulmonary function and COPD diagnosed by means of spirometry or through national hospitalization and death registers.

MAIN RESULTS

In the general population, 97.5% were noncarriers, 2.4% were heterozygotes, and 0.02% were homozygotes. Among R213G noncarriers, extracellular superoxide dismutase plasma concentration was 148+/-52 and 142+/-43 ng/ml (mean+/-SD) in individuals with and without COPD (Student's t test, p=0.02). Among heterozygotes, corresponding concentrations were 1,665+/-498 ng/ml and 1,256+/-379 (p<0.001). The adjusted odds ratio for spirometrically diagnosed COPD in heterozygotes versus noncarriers was 0.5 (95% confidence interval: 0.3-0.9). After stratification, the equivalent adjusted odds ratio was 1.5 (0.3-6.6) among nonsmokers and 0.4 (0.2-0.8) among smokers (p value for interaction=0.10). The adjusted hazard ratio for COPD hospitalization or death during follow-up in heterozygotes versus noncarriers was 0.3 (0.1-0.8).

CONCLUSIONS

Extracellular superoxide dismutase R213G heterozygosity protects against development of COPD in the Danish general population. This was observed in smokers, but not in nonsmokers.

Fruit and vegetable intakes and asthma in the E3N study

BACKGROUND

A study was undertaken to investigate whether dietary intake predicted the prevalence of adult asthma among French women participating in the E3N study.

METHODS

Of 68 535 women who completed a food frequency questionnaire in 1993 which included 238 food items, 2145 (3.1%) reported having asthma. The distribution of food intake was divided into quartiles (Q(1)-Q(4)) and the prevalence of asthma was compared between the different quartiles (lowest as reference) using logistic regression models on cross sectional data.

RESULTS

After adjusting for age, body mass index, menopausal status, smoking status, total caloric intake, physical activity, and use of dietary supplements, women who had a greater intake of tomatoes (OR(Q1-Q4) 0.85 95% CI 0.75 to 0.96, test for trend p = 0.02), carrots (OR(Q1-Q4) 0.81 95% CI 0.72 to 0.92, test for trend p = 0.0003), and leafy vegetables (OR(Q1-Q4) 0.82 95% CI 0.73 to 0.93, test for trend p = 0.0009) had a lower prevalence of asthma. Apples were marginally related to the prevalence of asthma. No other fruits or vegetables were significantly associated with asthma prevalence.

CONCLUSIONS

These results suggest that the intake of some vegetables may decrease the prevalence of adult asthma.

Transcription factor Nrf2 plays a pivotal role in protection against elastase-induced pulmonary inflammation and emphysema

Emphysema is one of the major pathological abnormalities associated with chronic obstructive pulmonary disease. The protease/antiprotease imbalance and inflammation resulting from oxidative stress have been attributed to the pathogenesis of emphysema. Nrf2 is believed to protect against oxidative tissue damage through the transcriptional activation of a battery of antioxidant enzymes. In this study, we investigated the protective role of Nrf2 in the development of emphysema using elastase-induced emphysema as our model system. We found that elastase-provoked emphysema was markedly exacerbated in Nrf2-knockout (KO) mice compared with wild-type mice. The severity of emphysema in Nrf2-KO mice correlated intimately with the degree of lung inflammation in the initial stage of elastase treatment. The highly inducible expression of antioxidant and antiprotease genes observed in wild-type alveolar macrophages was significantly attenuated in the lungs of Nrf2-KO mice. Interestingly, transplantation of wild-type bone marrow cells into Nrf2-KO mice retarded the development of initial lung inflammation and subsequent emphysema, and this improvement correlated well with the appearance of macrophages expressing Nrf2-regulated antiprotease and antioxidant genes. Thus, Nrf2 appears to exert its protective effects through the transcriptional activation of antiprotease and antioxidant genes in alveolar macrophages.

Changing the burden of COPD mortality

COPD is a major cause of mortality and morbidity worldwide with an estimated 2.75 million deaths in 2000 (fourth leading cause of death). In addition to the considerable morbidity and mortality associated with COPD, this disease incurs significant healthcare and societal costs. Current COPD guidelines acknowledge that the following can improve COPD mortality: smoking cessation; long-term oxygen therapy; and lung volume reduction surgery in small subsets of COPD patients. To date, no randomized controlled trials have demonstrated an effect of pharmacological treatment on mortality, although several observational studies suggest that both long-acting bronchodilators and inhaled corticosteroids may provide a survival benefit. The possibility that these treatments reduce mortality is being investigated in ongoing large-scale clinical trials.

The role for N-acetylcysteine in the management of COPD

Oxidative stress has been implicated in the pathogenesis and progression of COPD. Both reactive oxidant species from inhaled cigarette smoke and those endogenously formed by inflammatory cells constitute an increased intrapulmonary oxidant burden. Structural changes to essential components of the lung are caused by oxidative stress, contributing to irreversible damage of both parenchyma and airway walls. The antioxidant N-acetylcysteine (NAC), a glutathione precursor, has been applied in these patients to reduce symptoms, exacerbations, and the accelerated lung function decline. This article reviews the available experimental and clinical data on the antioxidative effects of NAC in COPD, with emphasis on the role of exhaled biomarkers.

Use of exhaled breath condensate in the study of airway inflammation after hypertonic saline solution challenge

STUDY OBJECTIVES

Hypertonic saline solution inhalation is suspected to produce airway inflammation.

DESIGN

The aim of this study was to verify this hypothesis by measuring inflammatory markers in exhaled breath condensate (EBC) collected before and after sputum induction with hypertonic and isotonic saline solution.

PATIENTS AND METHODS

We enrolled 10 patients with asthma, 10 patients with COPD, and 7 healthy subjects with no history of lung disease. Levels of interleukin (IL)-6 and tumor necrosis factor (TNF)-alpha were measured in EBC by a specific enzyme immunoassay kit. Exhaled pH was measured after deaeration/decarbonation by bubbling with argon (350 mL/min) for 10 min by means of a pH meter.

MEASUREMENTS AND RESULTS

Exhaled IL-6 and TNF-alpha concentrations were greater and pH was decreased compared to baseline after hypertonic saline solution inhalation in each group of subjects studied. No changes were observed following isotonic saline solution inhalation. Concentrations of IL-6, TNF-alpha, and pH in EBC correlated.

CONCLUSIONS

These findings suggest that hypertonic saline solution inhalation could cause a low-grade inflammation in airways, and levels of inflammatory markers such as IL-6, TNF-alpha, and pH in EBC may be a useful noninvasive way to assess and monitor airway inflammation.

Aerobic capacity, oxidant stress, and chronic obstructive pulmonary disease--a new take on an old hypothesis

Chronic obstructive pulmonary disease (COPD) is a smoking-related disorder that is a leading cause of death worldwide. It is associated with an accelerated rate of age-related decline in lung function due to the occurrence of destructive pathological changes such as emphysema, small airway remodeling, and mucus hypersecretion. Smokers are exposed to trillions of radicals and thousands of reactive chemicals and particles with every cigarette, thus oxidant stress is believed to be a central factor in the pathogenesis of COPD. The molecular activities of radicals, reactive oxygen, and nitrogen species can, over time, lead to a number of the detrimental changes in the lung. For instance, smoke can directly damage the mitochondrion, an organelle that has long been linked to age-related diseases associated with oxidant stress. Mitochondria are involved in a number of important cellular processes and are the largest source of endogenous reactive oxygen species (ROS) in the cell; therefore, any impairment of mitochondrial function can lead to greater oxidant damage, cellular dysfunction, and eventually to disease. Only a subset of smokers (15-50%) develops COPD, suggesting that there are polygenetic and/or environmental susceptibility factors involved in this complex disease. Here, we propose that the aerobic capacity for an individual may determine whether one is susceptible to developing COPD. Aerobic capacity is a polygenetic trait closely associated with mitochondrial function, and we suggest antioxidant defenses. Thus, those smokers who have the greatest aerobic capacity will be most resistant to the effects of chronic cigarette smoke exposure and be less likely to develop COPD.

Vimang (Mangifera indica L. extract) induces permeability transition in isolated mitochondria, closely reproducing the effect of mangiferin, Vimang's main component

Mitochondrial permeability transition (MPT) is a Ca(2+)-dependent, cyclosporin A (CsA)-sensitive, non-selective inner membrane permeabilization process. It is often associated with apoptotic cell death, and is induced by a wide range of agents or conditions, usually involving reactive oxygen species (ROS). In this study, we demonstrated that Mangifera indica L. extract (Vimang), in the presence of 20 microM Ca(2+), induces MPT in isolated rat liver mitochondria, assessed as CsA-sensitive mitochondrial swelling, closely reproducing the same effect of mangiferin, the main component of the extract, as well as MPT-linked processes like oxidation of membrane protein thiols, mitochondrial membrane potential dissipation and Ca(2+) release from organelles. The flavonoid catechin, the second main component of Vimang, also induces MPT, although to a lesser extent; the minor, but still representative Vimang extract components, gallic and benzoic acids, show respectively, low and high MPT inducing abilities. Nevertheless, following exposure to H(2)O(2)/horseradish peroxidase, the visible spectra of these compounds does not present the same changes previously reported for mangiferin. It is concluded that Vimang-induced MPT closely reproduces mangiferin effects, and proposed that this xanthone is the main agent responsible for the extract's MPT inducing ability, by the action on mitochondrial membrane protein thiols of products arising as a consequence of the mangiferin's antioxidant activity. While this effect would oppose the beneficial effect of Vimang's antioxidant activity, it could nevertheless benefit cells exposed to over-production of ROS as occurring in cancer cells, in which triggering of MPT-mediated apoptosis may represent an important defense mechanism to their host.

Lung function and blood levels of copper, selenium, vitamin C and vitamin E in the general population

BACKGROUND

Increased dietary intake of antioxidants has been associated with higher lung function, but few studies have used biological markers of antioxidant intake.

OBJECTIVE

This study aimed to determine if antioxidant status, as measured by blood levels, influences lung function.

DESIGN

Using a random subsample of 479 participants, aged 18-65 y old, from a larger cross-sectional observational study, the association of forced expiratory volume in 1 s (FEV1) with plasma copper, vitamin C, vitamin E and serum selenium was assessed.

RESULTS

An s.d. increase in blood copper level was associated with a difference in FEV1 of -48 ml (95% confidence intervals: -95, -2 ml, P = 0.04), vitamin C +49 ml (+4, +94, P = 0.03), vitamin E -15 ml (-62, +32, P = 0.53) and selenium +52 ml (+7, +96, P = 0.02). The sizes of association were not appreciably altered in a mutually adjusted model.

CONCLUSIONS

Higher levels of serum vitamin C and selenium appear to be associated with higher FEV1. The association between higher serum copper and lower FEV1 requires further study in view of the ubiquitous exposure to this mineral.

Systemic inflammatory response to exhaustive exercise in patients with chronic obstructive pulmonary disease

Systemic inflammation may be present in patients with chronic obstructive pulmonary disease (COPD). Exercise is known to elicit an inflammatory response. We hypothesized that the systemic inflammatory response to exercise might be exaggerated in COPD patients compared to healthy subjects. Sixteen COPD patients and 11 healthy subjects performed a maximal incremental bicycle test. Before and at maximal exercise arterial blood samples were taken to determine circulating catecholamines, (subsets of) leukocytes, acute phase proteins, creatine kinase and myoglobin. At rest, increased levels of norepinephrine and systemic inflammation were present in COPD. The response of catecholamines to exercise was lower in COPD patients (P<0.01), which in part was due to the lower maximal exercise capacity of these patients (P<0.01). Exercise-induced leukocytosis showed similar responses in both groups, but occurred at higher levels in COPD. Although patients had increased levels of CRP at rest (P<0.001), exercise did not affect acute phase proteins. No systemic signs of muscle damage were found. The present study shows that COPD patients are exposed to systemic inflammation that is intensified by exhaustive exercise. The inflammatory response in COPD is not exaggerated compared to healthy subjects but occurs at a higher level and is observed at lower external workload.

Increased DNA damage in patients with chronic obstructive pulmonary disease who had once smoked or been exposed to biomass

OBJECTIVE

Chronic obstructive pulmonary disease (COPD) is a slowly progressive condition characterised by poorly reversible airflow limitation associated with an abnormal inflammatory response of the lung. The main causal factors of COPD are chronic oxidative stress as a result of long-term smoking, use of biomass fuels, and air pollution. In this study, basal levels of DNA strand breaks were investigated together with some additional oxidative markers implicating oxidative damage on the other biomolecules such as proteins and lipids in patients with COPD who were exposed to smoking and biomass.

MATERIAL AND METHODS

We detected DNA strand breaks in peripheral blood mononuclear leukocytes by using a Single Cell Gel Electrophoresis (also called Comet Assay), plasma protein carbonyl (PC) content by using Reznick and Parker's spectrophotometric method, and lipid peroxidation by measurement of malondialdehyde (MDA) as indexes of oxidative stress in 47 patients with smoking-related COPD and 25 patients with biomass-related COPD and 36 age-and-sex matched control participants.

RESULTS

The mean values of DNA strand breaks, MDA and protein carbonyl levels were significantly higher in smoking- and biomass-related COPD groups than in the control group (ANOVA P<0.001, <0.05 and <0.05, respectively). DNA damage levels were also higher in smoking-related COPD group than in biomass-related COPD group (P<0.05). There was a positive relationship between DNA damage and MDA levels in smoking-related COPD group (P<0.05).

CONCLUSION

Oxidative stress markers and DNA damage were strongly increased in both patient groups with smoking- and biomass-related COPD. However, DNA is more affected in smoking-related COPD patients than in biomass-related COPD. These data indicate that cigarette smoking is a more significant DNA damaging risk factor than biomass smoke.

Theophylline prevents NAD+ depletion via PARP-1 inhibition in human pulmonary epithelial cells

Oxidative DNA damage, as occurs during exacerbations in chronic obstructive pulmonary disease (COPD), highly activates the nuclear enzyme poly(ADP-ribose)polymerase-1 (PARP-1). This can lead to cellular depletion of its substrate NAD+, resulting in an energy crisis and ultimately in cell death. Inhibition of PARP-1 results in preservation of the intracellular NAD+ pool, and of NAD+-dependent cellular processes. In this study, PARP-1 activation by hydrogen peroxide decreased intracellular NAD+ levels in human pulmonary epithelial cells, which was found to be prevented in a dose-dependent manner by theophylline, a widely used compound in the treatment of COPD. This enzyme inhibition by theophylline was confirmed in an ELISA using purified human PARP-1 and was found to be competitive by nature. These findings provide new mechanistic insights into the therapeutic effect of theophylline in oxidative stress-induced lung pathologies.

Increased Oxidative Stress in Exudative Pleural Effusions

STUDY OBJECTIVES

Oxidative stress has been associated with various respiratory disorders. We tested the hypothesis that exudates would present higher levels of oxidative stress compared to transudates, expressing the increased local oxidative burst in the former.

DESIGN

Prospective, cross-sectional study.

PATIENTS OR PARTICIPANTS

One hundred six consecutive patients who had undergone thoracentesis were studied. Ninety patients with a final diagnosis of pleural effusion were further analyzed.

SETTING

The respiratory department and a clinical laboratory of a tertiary hospital.

INTERVENTIONS

Subjects underwent diagnostic thoracentesis, and standard biochemical parameters (ie, total protein, lactate dehydrogenase, and albumin levels) were measured in pleural fluid and serum. Oxidative stress levels were assessed with a commercially available method (d-ROMs test; Diacron; Grosseto, Italy) that uses conventional Carratelli units (UCarr). In 14 patients, duplicate measurements of oxidative stress and a second thoracentesis were performed on the following day for the assessment of the repeatability of measurements. Receiver operating characteristic (ROC) analysis was performed in order to determine the optimal cutoff level for the differentiation between exudates and transudates.

MEASUREMENTS AND RESULTS

Oxidative stress levels were higher in exudates compared to transudates (mean [+/- SD] stress level, 274 +/- 72 vs 126 +/- 34 UCarr, respectively; p < 0.0001). No significant differences were found among the levels of oxidative stress in exudative effusions of different etiologies. The area under the ROC curve was 0.992 (95% confidence interval, 0.945 to 0.997), and the method provided high sensitivity (96.8%), high specificity (96.3%), and high accuracy (96.7%) for the diagnosis of exudates at a cutoff level for oxidative stress of 186 UCarr. Consecutive measurements of oxidative stress in the same samples and on fluid from two different thoracenteses performed on 2 consecutive days presented excellent repeatability.

CONCLUSIONS

Oxidative stress levels are higher in exudative pleural effusions compared to transudative effusions, probably due to reactive oxygen species produced in the former.

N-acetylcysteine and deferoxamine reduce pulmonary oxidative stress and inflammation in rats after coal dust exposure

Coal dust inhalation induces oxidative damage and inflammatory infiltration on lung parenchyma. Thus, the aim of this study was to determine whether N-acetylcysteine (NAC) administered alone or in combination with deferoxamine (DFX), significantly reduced the inflammatory infiltration and oxidative damage in the lungs of rats exposed to coal dust. Forty-two male Wistar rats (200-250 g) were exposed to the coal dust (3mg/0.5 mL saline, 3 days/week, for 3 weeks) by intratracheal instillation. The animals were randomly divided into three groups: saline 0.9% (n=8), supplemented with NAC (20mg/kg of body weight/day, intraperitoneal injection (i.p.)) (n=8), and supplemented with NAC (20 mg/kg of body weight/day, i.p.) plus DFX (20 mg/kg of body weight/week) (n=8). Control animals received only saline solution (0.5 mL). Lactate dehydrogenase activity and total cell number were determined in the bronchoalveolar lavage fluid. We determined lipid peroxidation and oxidative protein damage parameters and catalase and superoxide dismutase activities in the lungs of animals. Intratracheal instillation of coal dust in the lungs of rats led to an inflammatory response and induced significant oxidative damage. The administration of NAC alone or in association with DFX reduced the inflammatory response and the oxidative stress parameters in rats exposed to coal dust.

Elevated Oxidative Stress and Reciprocal Reduction of Vascular Endothelial Growth Factor Levels With Severity of COPD

STUDY OBJECTIVES

The prevalent theory concerning the pathogenesis of COPD is that it is an imbalance between oxidants and antioxidants. However, it has been reported that a decrease in vascular endothelial growth factor (VEGF) might affect the pathogenesis of COPD. Therefore, this study was designed to examine the differences between oxidative stress and VEGF levels, and the severity of COPD.

DESIGN

Controlled cross-sectional analysis.

SETTING

University hospital.

PARTICIPANTS

Twelve healthy control subjects and 57 COPD patients were included in this study. These COPD patients were divided into four groups based on the Global Initiative for Chronic Obstructive Lung Disease classification (mild COPD, 14 patients; moderate COPD, 15 patients; severe COPD, 16 patients; very severe COPD, 12 patients).

MEASUREMENTS AND RESULTS

Inflammatory markers, degree of oxidative stress, and VEGF levels were examined in sputum samples from all subjects. Nitrogen oxide levels in induced sputum were significantly higher in COPD patients than in healthy control subjects, and they increased with increases in the severity of COPD. In contrast, peroxynitrite inhibitory activity decreased with increases in the severity of COPD. Therefore, the mean (SD) peroxynitrite stress (ie, the nitrogen oxide level/peroxynitrite inhibitory activity ratio) steeply increased with increases in the severity of COPD (mild COPD: 8.4; SD, 1.5; p = 0.02; moderate COPD: 10.8; SD, 1.4; p < 0.0001; severe COPD: 14.5; SD, 2.5; p < 0.0001; very severe COPD: 18.3; SD, 4.1; p < 0.0001) compared with that of healthy control subjects. VEGF levels in induced sputum reciprocally decreased with severity of COPD (mild COPD: 1,360 pg/mL; SD, 800 pg/mL; p = 0.97; moderate COPD: 1,180 pg/mL; SD, 760 pg/mL; p = 0.50; severe COPD: 650 pg/mL; SD, 450 pg/mL; p = 0.007; very severe COPD: 480 pg/mL, SD, 240 pg/mL; p = 0.002). In addition, peroxynitrite inhibitory activity in COPD patients exhibited an accelerated decline from the mean VEGF level in healthy control subjects.

CONCLUSIONS

Elevated oxidative stress levels and a reciprocal reduction of VEGF levels in induced sputum were prominent with increases in the severity of COPD. Thus, epithelial cell injury mediated by oxidative stress may induce the decrease in lung VEGF levels, resulting in the promotion of the development of COPD.

CEBPG transcription factor correlates with antioxidant and DNA repair genes in normal bronchial epithelial cells but not in individuals with bronchogenic carcinoma

Background

Cigarette smoking is the primary cause of bronchogenic carcinoma (BC), yet only 10–15% of heavy smokers develop BC and it is likely that this variation in risk is, in part, genetically determined. We previously reported a set of antioxidant genes for which transcript abundance was lower in normal bronchial epithelial cells (NBEC) of BC individuals compared to non-BC individuals. In unpublished studies of the same NBEC samples, transcript abundance values for several DNA repair genes were correlated with these antioxidant genes. From these data, we hypothesized that antioxidant and DNA repair genes are co-regulated by one or more transcription factors and that inter-individual variation in expression and/or function of one or more of these transcription factors is responsible for inter-individual variation in risk for BC.

Methods

The putative transcription factor recognition sites common to six of the antioxidant genes were identified through in silico DNA sequence analysis. The transcript abundance values of these transcription factors (n = 6) and an expanded group of antioxidant and DNA repair genes (n = 16) were measured simultaneously by quantitative PCR in NBEC of 24 non-BC and 25 BC individuals.

Results

CEBPG transcription factor was significantly (p < 0.01) correlated with eight of the antioxidant or DNA repair genes in non-BC individuals but not in BC individuals. In BC individuals the correlation with CEBPG was significantly (p < 0.01) lower than that of non-BC individuals for four of the genes (XRCC1, ERCC5, GSTP1, and SOD1) and the difference was nearly significant for GPX1. The only other transcription factor correlated with any of these five target genes in non-BC individuals was E2F1. E2F1 was correlated with GSTP1 among non-BC individuals, but in contrast to CEBPG, there was no significant difference in this correlation in non-BC individuals compared to BC individuals.

Conclusion

We conclude that CEBPG is the transcription factor primarily responsible for regulating transcription of key antioxidant and DNA repair genes in non-BC individuals. Further, we conclude that the heavy smokers selected for development of BC are those who have sub-optimal regulation of antioxidant and DNA repair genes by CEBPG.

Membrane Switch Hypothesis. 2. Domain Structure of Phagocytes in Horses with Recurrent Airway Obstruction

The mechanism of recurrent airway obstruction (RAO) in horses was investigated by measuring the membrane domain structure and oxy-redoxy activity in phagocytes isolated from bronchoalveolar lavage fluid (BAL) and from the blood of healthy and RAO horses by electron paramagnetic resonance (EPR). Differences in the activity of intracellular antioxidant enzymes CAT, GPx, and SOD measured in phagocytes of RAO horses in comparison to healthy horses showed that the phagocytes were affected by oxidative stress. In comparison with polymorphonuclear leukocytes (phagocytes) from the blood of healthy horses the reduction mechanisms in BAL were faster and coincided with the merging of disordered membrane domains, while in horses with RAO the reduction and membrane domain structure remained unchanged. We assume that the merging of lipid domains observed in phagocytes from BAL of healthy horses could promote cluster formation of membrane proteins or ligands, which could trigger the activation process in phagocytes of healthy horses and consequently the physiological response that probably did not happen in phagocytes of RAO horses.

Leukocyte oxidant and antioxidant status in asthmatic patients

BACKGROUND

Oxidative stress mediated by reactive oxygen species (ROS) is recognized to contribute significantly to the inflammatory process of bronchial asthma (BA). These species are released into the airway by activated inflammatory cells such as leukocytes. In this study, we aimed to determine whether the oxidant-antioxidant balance is changed in leukocytes of patients with BA.

METHODS

Thirty eight patients (21 male, 17 female) aged 22-68 years and controls of 32 subjects (18 male, 14 female) aged 20-63 years were included in the study. A total of 10 mL venous blood was drawn, leukocytes were separated and lipid peroxidation (LPO), glutathione peroxidase (GSH-Px), superoxide dismutase (SOD) and vitamin C levels were determined in both patients and controls.

RESULTS

Leukocyte LPO and SOD activity in the patient group were higher than that of controls (p <0.001 and p <0.05, respectively). However, leukocyte GSH-Px and vitamin C levels in the patient group were lower than that of controls (p <0.01 and p <0.001, respectively).

CONCLUSIONS

The results suggest that there are alterations in a wide array of oxidants and antioxidants with balance shifting toward increased oxidative stress in BA.

Exhaled breath condensate levels of 8-isoprostane, growth related oncogene alpha and monocyte chemoattractant protein-1 in patients with chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) patients have increased neutrophils and macrophages in their lungs, and inflammation of the airway is related to oxidative stress. This study assessed the levels of 8-isoprostane (an oxidative stress marker) and chemokines related to neutrophil and monocyte inflammation (growth-related oncogene alpha [GROalpha] and monocyte chemoattractant protein-1 [MCP-1]) in the airway of ex-smoking COPD patients by exhaled breath condensate (EBC) collection. Thirty-two (28 males) stable COPD patients (14 with FEV(1) 50% [Group 1], 18 with FEV(1) <50% predicted [Group 2]) and 18 non-smoking age and sex-matched controls were studied in this cross-sectional study. EBC was collected using the EcoScreen (Jaeger, Germany) during 10 min of tidal breathing with the nose clipped. Concentrations of 8-isoprostane, GROalpha and MCP-1 were measured by enzyme immunoassays. COPD patients had a higher concentration of 8-isoprostane than controls (COPD versus control, P<0.001; Group 1 versus Group 2, P=0.045). 8-isoprostane increased across the groups from normal, Group 1 to Group 2 (r=0.64, P<0.001). The median intraquartile range (IQR) levels in pg/ml for GROalpha were 45.3(44.5-46.5), 45.4(44.5-46.0), 46.0(45.6-47.3), whereas MCP-1 levels were 5.3(5.2-5.9), 6.2(5.4-6.9) and 5.7(5.5-6.4) in Group 1, Group 2 COPD and control subjects, respectively. GROalpha level was lower in COPD patients when compared to controls (P=0.01). MCP-1 level did not differ between COPD and the control group. 8-isoprostane level, but not GROalpha and MCP-1, in EBC was increased in COPD patients with poorer lung function. This suggests an increased oxidative stress in the airway in patients with more severe COPD.

Focus on antioxidant enzymes and antioxidant strategies in smoking related airway diseases

Cigarette smoke causes significant oxidant stress which is further enhanced by recruitment and activation of inflammatory cells to the lung. Polymorphisms in some detoxification enzymes are thought to increase the risk of developing chronic obstructive pulmonary disease (COPD), but the ultimate role of genetic variability in antioxidant and/or detoxification enzymes in COPD remains obscure. Some antioxidant enzymes are inducted, but the extent of induction is insufficient to protect the lung/alveolar epithelium against cigarette smoke. Exogenous antioxidants such as vitamins do not seem to protect against cigarette smoke related lung injury. Glutathione related synthetic drugs such as N-acetylcysteine have shown some benefits, but they may have pro-oxidant side effects. Synthetic compounds with superoxide dismutase and catalase activities have shown promising results in animal models against a variety of oxidant exposures including cigarette smoke in the lung. These results are in agreement with studies highlighting the importance of alveolar antioxidant protection mechanisms in oxidant stress and their inducibility. These new drugs need to be tested in cigarette smoking related lung injury/inflammation since inflammation/oxidant stress can continue after discontinuation of smoking.

Effects of erdosteine on smoking-induced lipid peroxidation in healthy smokers

AIM

Oxidative stress caused by smoking has been implicated in many pulmonary diseases. Smoking causes reductions in plasma nitrate plus nitrite (NOx) concentrations and increases in plasma malondialdehyde (MDA) concentrations, which indicate oxidative stress and lipid peroxidation, respectively. In this study, we investigated the acute effects of smoking a single cigarette on the plasma concentrations of NOx and thiobarbituric acid reactive substances (TBARS) including MDA, and whether administration of erdosteine, a mucolytic and antioxidant agent, affects these parameters.

METHODS

Thirty healthy smokers were included in the study. Subjects smoked a single cigarette in 10 minutes on the study day. For analysis of NOx, TBARS and cotinine, blood was drawn from each subject before and 5 and 30 minutes after smoking. The subjects were then randomly divided into two groups, one receiving placebo and the other erdosteine suspension 175mg/5mL twice daily for 1 month. After this treatment period, the same study protocol was carried out. Two subjects in the placebo and five subjects in the study group were excluded because of noncompliance.

RESULTS

Twenty-three (14 female, 9 male) subjects completed the study. Their mean age was 32 +/- 8 years and their smoking history was 14 +/- 9 pack-years. Baseline NOx, TBARS and cotinine concentrations were similar between the groups. NOx concentrations decreased significantly after smoke exposure. At the end of the treatment period there were no significant differences in NOx, TBARS or cotinine concentrations between the groups. The concentration of TBARS after smoking decreased significantly in the erdosteine-treated group (at 5 minutes: 2.8 +/- 0.5 micromol/L before treatment and 2.3 +/- 0.3 micromol/L after treatment, p < 0.05; at 30 minutes: 2.8 +/- 0.5 micromol/L before treatment and 1.8 +/- 0.7 micromol/L after treatment, p < 0.05). Smoking history was significantly correlated with cotinine concentrations.

CONCLUSION

Acute smoke exposure decreased plasma NOx concentrations in healthy smokers, and this was not changed with erdosteine treatment. However, significant decreases were noted in TBARS concentrations after smoke exposure in the group that received erdosteine, suggesting that short-term erdosteine administration might help prevent smoking-induced lipid peroxidation.

Mediators of chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is a major and increasing global health problem that is now a leading cause of death. COPD is associated with a chronic inflammatory response, predominantly in small airways and lung parenchyma, which is characterized by increased numbers of macrophages, neutrophils, and T lymphocytes. The inflammatory mediators involved in COPD have not been clearly defined, in contrast to asthma, but it is now apparent that many lipid mediators, inflammatory peptides, reactive oxygen and nitrogen species, chemokines, cytokines, and growth factors are involved in orchestrating the complex inflammatory process that results in small airway fibrosis and alveolar destruction. Many proteases are also involved in the inflammatory process and are responsible for the destruction of elastin fibers in the lung parenchyma, which is the hallmark of emphysema. The identification of inflammatory mediators and understanding their interactions is important for the development of anti-inflammatory treatments for this important disease.

Short-term effects of montelukast in stable patients with moderate to severe COPD

This study aims to investigate the possibility of additional value of leukotriene receptor antagonist (LTA) on dyspnea score, arterial blood gases (ABG), pulmonary function tests (PFTs), and quality of life (St. George QoL) in chronic obstructive pulmonary disease (COPD) patients. In this randomized, prospective, single-blind, and controlled study, 117 non-reversible COPD patients defined by global initiative for chronic obstructive lung disease (GOLD) criteria were randomized to receive ipratropium bromide, formoterol and montelukast (n:58, montelukast group) or ipratropium bromide and formoterol (n:59, control group) after a 2-week run-in period. There was no significant demographic difference between the two groups (P>0.05). Baseline ABG, PFT, visual analoque scores (VAS), and QoL scores were obtained and at first month and second month, PFT, VAS, and QoL scores were repeated and ABG was obtained at second month and the values were compared with baseline values. As the result of the comparison, there was significant increase in vital capacity, FVC, FEV1, VAS, and PaO2 parameters (P<0.05), and a significant decrease in the QoL scores (P<0.05) in the montelukast group. These parameters did not show any difference in the control group (P>0.05). Sputum samples that could be obtained in 24 of the COPD patients were evaluated and in the montelukast group, there was a decrease in neutrophilic activity after treatment (n:13) (P:0.059). These results suggest that LTA that is used additionally in routine treatment protocol can produce additive improvement on PFT, dyspnea score and especially QoL in patients with stable COPD and for these reasons, LTA may be taken into account when there is need for an additional anti-inflammatory treatment in COPD patients.

The interrelationship between markers of inflammation and oxidative stress in chronic obstructive pulmonary disease: modulation by inhaled steroids and antioxidant

BACKGROUND

Chronic obstructive pulmonary disease (COPD) is accompanied by both airway and systemic inflammation and by oxidative stress. This study aimed to characterise the relationship between oxidative stress and inflammatory components in induced sputum and blood.

MATERIAL & METHODS

We studied blood and sputum samples from stable COPD patients (mean FEV1 60.5+/-7.5% predicted) at baseline (no treatment) and after 10 weeks treatment with either inhaled steroid, fluticasone propionate (FP) (1000 microg/d) or 10 weeks treatment with N-acetylcysteine (600mg/d) (NAC). We assessed the inflammatory markers (IL-8, ECP, sICAM-1, NE) in sputum and serum and we compared them with blood markers of oxidative stress (SOD, GPx, TEAC, albumin, vitamin E and A).

RESULTS

At baseline blood sICAM-1 correlated with IL-8 levels (P<0.01, r = 0.62) and negatively with GPx (P<0.01, r = -0.63) and with TEAC (P<0.05, r = -0.53). TEAC correlated positively with GPx (P<0.01, r = 0.70). Correlation between sICAM and IL-8 disappeared after NAC treatment. The correlation between sICAM and GPx disappeared after FP treatment. The correlation between TEAC and GPx was maintained after both NAC and FP.

CONCLUSIONS

The relationship between markers of inflammation, adhesion and antioxidant capacity is significantly modulated by treatment with N-acetylcysteine or inhaled corticosteroids.

Increased Arterial Carboxyhemoglobin Concentrations in Chronic Obstructive Pulmonary Disease

RATIONALE

Exhaled carbon monoxide (CO) and arterial blood carboxyhemoglobin concentrations (Hb-CO) increase in inflammatory pulmonary diseases.

OBJECTIVES

To study whether arterial Hb-CO is useful to monitor disease activity in patients with chronic obstructive pulmonary disease (COPD) who had stopped smoking.

METHODS

We measured arterial Hb-CO, arteriovenous Hb-CO differences, and FEV1 in 58 patients with COPD and 61 ex-smoking control subjects.

RESULTS

Arterial Hb-CO concentrations in patients at stable conditions were higher than those in control subjects (p < 0.0001). Furthermore, the Hb-CO concentrations in patients at the exacerbations (p < 0.0001) were higher than those at the stable conditions. Arterial Hb-CO concentrations in patients at stage III were higher than those in patients at stage II, and the Hb-CO concentrations in patients at stage IV were higher than those in patients at stage III at the stable conditions and exacerbations. Arterial Hb-CO correlated with exhaled CO in patients with COPD at stage II and stage III at the exacerbations. Arterial Hb-CO inversely correlated with the arterial blood partial oxygen pressure and FEV1. Arteriovenous Hb-CO differences in patients at the exacerbations did not differ from those in patients at stable conditions and from those in control subjects. Moreover, arterial Hb-CO correlated with serum C-reactive protein values and serum lipid peroxide concentrations.

CONCLUSIONS

These findings suggest that increased arterial Hb-CO may relate to severity in patients with COPD because of lung and systemic inflammation and production of reactive oxygen species.

Markers of inflammation and oxidative stress in exacerbated chronic obstructive pulmonary disease patients

COPD is characterised by damage to small airways due to an inflammatory process as well as an imbalance between oxidants and antioxidants. Several cytokines and cell adhesion molecules enhancing a mainly neutrophilic inflammation have been associated with COPD. The aim of the study was to investigate whether inflammation or oxidative markers gave an indication of the course of COPD during an exacerbation. Fourteen patients with moderate to severe COPD admitted to the St. Antonius Hospital because of an exacerbation have been monitored during treatment with prednisolone 50 mg intravenously during 24 h at admission, reduced to 25 mg at day 3 and tapered off with oral prednisolone at day 7. On three separate occasions, day 1, 3 and 7, H2O2 in exhaled air, IL-8 and the soluble cell adhesion molecule sICAM and sE-selectin in serum were measured. We compared the patients at day 1 with healthy controls (in both non-smokers and smokers). Furthermore, we examined the changes from the study group in time during therapy. At admission all the markers were raised in comparison with the control groups. During treatment H2O2 concentrations in breath condensate declined significantly (P<0.001) as well as IL-8 and sICAM in serum (P=0.002, respectively, P<0.001). There was no significant change in sE-selectin (P=0.132). No significant improvement has been found in spirometry. These data suggest that the markers H2O2 in exhaled air, IL-8 and sICAM in serum are suitable markers in monitoring exacerbated COPD.

Altered antioxidant status in peripheral skeletal muscle of patients with COPD

Despite the growing field of interest in the role of pulmonary oxidative stress in chronic obstructive pulmonary disease (COPD), barely any data are available with respect to antioxidant capacity in the peripheral musculature of these patients. The main objective of this study was to assess in detail the antioxidant status in skeletal muscle of patients with COPD. Biopsies from the vastus lateralis of 21 patients with COPD and 12 healthy age-matched controls were analysed. Total antioxidant capacity, vitamin E, glutathione, and uric acid levels were determined and the enzyme activities of superoxide dismutase, glutathione reductase, glutathione peroxidase, and glutathione-S-transferase were measured. Malondialdehyde was measured as an index of lipid peroxidation. The total antioxidant capacity and the uric acid levels were markedly higher in COPD patients than in healthy controls (25%, P = 0.006 and 24%, P = 0.029, respectively). Glutathione-S-transferase activity was also increased (35%; P = 0.044) in patients compared to healthy subjects. Vitamin E level was lower in patients than in controls (P < 0.05). The malondialdehyde level was not different between the two groups. It can be concluded that the muscle total antioxidant capacity is increased in patients with COPD. Together with the reduced vitamin E levels, the increased glutathione-S-transferase activity and normal levels of lipid peroxidation products, these findings suggest that the antioxidant system may be exposed to and subsequently triggered by elevated levels of reactive oxygen species.

Effects of N-acetylcysteine on outcomes in chronic obstructive pulmonary disease (Bronchitis Randomized on NAC Cost-Utility Study, BRONCUS): a randomised placebo-controlled trial

BACKGROUND

Increased oxidative stress is important in the pathogenesis of chronic obstructive pulmonary disease (COPD). We postulated that treatment with the antioxidant N-acetylcysteine would reduce the rate of lung-function decline, reduce yearly exacerbation rate, and improve outcomes.

METHODS

In a randomised placebo-controlled study in 50 centres, 523 patients with COPD were randomly assigned to 600 mg daily N-acetylcysteine or placebo. Patients were followed for 3 years. Primary outcomes were yearly reduction in forced expiratory volume in 1 s (FEV1) and the number of exacerbations per year. Analysis was by intention to treat.

FINDINGS

The yearly rate of decline in FEV1 did not differ between patients assigned N-acetylcysteine and those assigned placebo (54 mL [SE 6] vs 47 mL [6]; difference in slope between groups 8 mL [9]; 95% CI -25 to 10). The number of exacerbations per year did not differ between groups (1.25 [SD 1.35] vs 1.29 [SD 1.46]; hazard ratio 0.99 [95% CI 0.89-1.10, p=0.85]). Subgroup analysis suggested that the exacerbation rate might be reduced with N acetylcysteine in patients not treated with inhaled corticosteroids and secondary analysis was suggestive of an effect on hyperinflation.

INTERPRETATION

N-acetylcysteine is ineffective at prevention of deterioration in lung function and prevention of exacerbations in patients with COPD.

Effect of treatments on the progression of COPD: report of a workshop held in Leuven, 11-12 March 2004

During the last decade several long term studies of interventions in patients with COPD have been published. This review analyses the potential of these interventions to alter the progression of the condition. The only treatment that has unequivocally been shown to reduce the rate of decline in FEV(1) is smoking cessation. Active psychological intervention in combination with pharmacotherapy is required. Other treatments may have an effect on the rate of decline in FEV(1) but this appears to be very small, at most. Several treatments affect the exacerbation rate and therefore might affect the progression of the disease. Further studies are warranted to examine this effect.

Toward functional proteomics of alveolar macrophages

Alveolar macrophages (AM) belong to a phenotype of macrophages with distinct biological functions and important pathophysiological roles in lung health and disease. The molecular details determining AM differentiation from blood monocytes and AM roles in lung homeostasis are largely unknown. With the use of different technological platforms, advances in the field of proteomics have made it possible to search for differences in protein expression between AM and their precursor monocytes. Proteome features of each cell type provide new clues into understanding mononuclear phagocyte biology. In-depth analyses using subproteomics and subcellular proteomics offer additional information by providing greater protein resolution and detection sensitivity. With the use of proteomic techniques, large-scale mapping of phosphorylation differences between the cell types have become possible. Furthermore, two-dimensional gel proteomics can detect germline protein variants and evaluate the impact of protein polymorphisms on an individual's susceptibility to disease. Finally, surface-enhanced laser desorption and ionization (SELDI) time-of-flight mass spectrometry offers an alternative method to recognizing differences in protein patterns between AM and monocytes or between AM under different pathological conditions. This review details the current status of this field and outlines future directions in functional proteomic analyses of AM and monocytes. Furthermore, this review presents viewpoints of integrating proteomics with translational topics in lung diseases to define the mechanisms of disease and to uncover new diagnostic and therapeutic targets.

Validation of a new method to measure hydrogen peroxide in exhaled breath condensate

Inflammatory processes in the lung can or will elicit oxidative stress. The degree of oxidative stress can be determined by measuring hydrogen peroxide (H(2)O(2)) concentration in exhaled breath condensate (EBC) but the methods to measure H(2)O(2) are all rather time consuming and only reliable and/or accurate in the hand of skilled technicians in a dedicated laboratory. We tested a new commercial device (Ecocheck), developed to offer a less time-consuming method to measure H(2)O(2). We validated this new method according the NCCLS EP10-A2 protocol. The validation shows that the imprecision in the low range is high (28.4%) and declines with higher concentrations of H(2)O(2) (up to 6.6%). The Ecocheck is "an easy to use" measuring device for routine measurements getting quick results without the need for skilled technicians to determine H(2)O(2) concentrations.

NO2-induced airway inflammation is associated with progressive airflow limitation and development of emphysema-like lesions in C57BL/6 mice

The major features of chronic obstructive pulmonary disease (COPD) comprise a not fully reversible airflow limitation associated with an abnormal inflammatory response, increased mucus production and development of emphysema-like lesions. Animal models that closely mimic these alterations represent an important issue for the investigation of pathophysiological mechanisms. Since most animal models in this area have focused on specific aspects of the disease, we aimed to investigate whether exposure of C57BL/6 mice to nitrogen dioxide (NO2) may cause a more complex phenotype covering several of the characteristics of the human disease. Therefore, mice were exposed to NO2 for 14h each day for up to 25 days. Initial dose response experiments revealed the induction of a significant inflammatory response at a dose of 20 ppm NO2. Mice developed progressive airway inflammation together with a focal inflammation of the lung parenchyma characterized by a predominant influx of neutrophils and macrophages. In addition, goblet cell hyperplasia was detected in the central airways and increased collagen deposition was found in the lung parenchyma. NO2-exposed mice developed emphysema-like lesions as indicated by a significantly increased mean linear intercept as compared to control mice. Finally, the assessment of lung functional parameters revealed the development of progressive airway obstruction over time. In conclusion, our data provide evidence that the inflammatory response to NO2 exposure is associated with increased mucus production, development of airspace enlargement and progressive airway obstruction. Thus, NO2-exposed mice may serve as a model to investigate pathophysiological mechanisms that contribute to the development of human COPD.

Effect of ozone exposure on intracellular glutathione redox state in cultured human airway epithelial cells

Intracellular oxidation and reduction (redox state) correspond closely to the surrounding environment. Most environmental factors affecting this balances such as oxidants, ultraviolet light, radioactive emissions, infections, and allergic reactions represent oxidative stress upon cells. We examined intracellular redox state after oxidative stress upon cultured human airway epithelial cells (Calu-3) by measuring reduced (GSH) or oxidized (GSSG) glutathione. We studied cytokine production, which is related to glutathione redox regulation, in response to ozone and also evaluated the effect of pretreatment with an ethyl ester of reduced glutathione (GSH-OEt) on cytokines. Ozone exposure (3.0 ppm, 3 min) time-dependently changed the redox state, while increasing production of interleukin(IL)-8 and IL-6, mRNA and protein. Treatment with GSH-OEt before ozone suppressed IL-8, but stimulated IL-6 production. Thus, oxidative stress affects intracellular glutathione redox state, in airway epithelial cells, activating signals to increase production of cytokine, modulation that may exacerbate respiratory symptoms.

[Oxidative stress in bronchopulmonary disease: contribution of N-acetylcysteine (NAC)]

Oxidative stress is a frequent mechanism involved in the pathogenesis of bronchopulmonary disease. The cause can be exogenous, in particular related to to atmospheric pollution and tobacco smoke, or endogenous, related to mobilization of inflammatory cells (macrophages and polymorphonuclear neutrophils). In this general review, we present work demonstrating this oxidative stress and activation of inflammatory cells. We discuss the effect of oxidative stress on the bronchial tree and the need to maintain an adequate balance between oxidants and anti-oxidants. This reviews focuses on experimental studies proving the anti-oxidant effect of NAC on glutathione synthesis and on different pharmacological models. We then discuss human trials, initially experimental then in different bronchopulmonary pathologies related to oxidative stress. Acetaminophen intoxication and pulmonary fibrosis are models for use of NAC. Recent work on COPD appears to show a decrease in exacerbations, improvement in symptoms and quality-of-life, and perhaps a reduction in the alteration of ventilatory function.

COPD, a multicomponent disease: implications for management

Chronic obstructive pulmonary disease (COPD) is a multicomponent disease. These components affect both the lungs and organs outside the lungs (the so-called systemic effects of COPD) and can be of either a structural (including airway remodelling, emphysema, skeletal muscle wasting) or functional nature (inflammation, apoptosis, senescence). Further, these components are interdependent in a closely linked 'vicious cycle'. Accordingly, optimal therapies should therefore aim to address more than one of these components to break such a cycle. This needs to be considered not only in the development of future treatments but also in the current clinical management of patients with COPD. In this paper, evidence that supports the concept that COPD is a multicomponent disease is presented. The effects of currently available therapeutic options, including long-acting anticholinergics and long-acting beta2-agonist/inhaled corticosteroid combination therapies, upon each of these components is reviewed. In addition, potential new avenues for drug development and improved patient care are highlighted. By developing a better understanding of how different therapies impact upon the 'vicious cycle' of COPD, treatment regimens can be optimised to provide the greatest benefits to patients.

Inhaled Corticosteroids in Chronic Obstructive Pulmonary Disease

Chronic obstructive pulmonary disease (COPD) is a serious illness that affects over 5% of the adult population. It is one of the few conditions for which the mortality and morbidity are still increasing. Experts expect COPD to become the third leading cause of death and the fifth leading cause of disability worldwide by the year 2020. Thus far, the only treatments that have been shown to make a difference to survival are smoking cessation and the use of oxygen supplements for those who are hypoxaemic at rest. The use of inhaled corticosteroids as monotherapy or in combination with a long-acting beta2-adrenoceptor agonist for COPD is controversial. Experimental data indicate that the inflammatory process in COPD may be resistant to the anti-inflammatory effects of corticosteroids. However, several large clinical studies have shown that inhaled corticosteroids in relatively high doses (e.g. budesonide 800 microg/day or fluticasone propionate 1 mg/day) reduce exacerbations by 20-30% and improve the health status of COPD patients by a similar amount compared with placebo. Withdrawal of inhaled corticosteroids may increase clinical exacerbation rates by 50% in COPD patients and by 2-fold in those with severe disease. Combined therapy with inhaled corticosteroids and long-acting beta2-adrenoceptor agonists may be superior to individual component therapy in reducing exacerbations. However, these medications must be used cautiously, as they have been associated with certain adverse effects. Inhaled corticosteroids, for instance, increase the risk for dysphonia and oral thrush by 2- to 3-fold. Skin bruising is also more common in users than in non-users of inhaled corticosteroids. On balance, for those with moderate-to-severe COPD and those who experience frequent exacerbations, judicious use of inhaled corticosteroids alone or in combination with long-acting beta2-adrenoceptor agonists appears reasonable.

Redox regulation of histone deacetylases and glucocorticoid-mediated inhibition of the inflammatory response

Gene expression, at least in part, is regulated by changes in histone acetylation status induced by activation of the proinflammatory redox-sensitive transcription factors activator protein-1 (AP-1) and nuclear factor-kappaB (NF-kappaB). Hyperacetylated histone is associated with open actively transcribed DNA and enhanced inflammatory gene expression. In contrast, hypoacetylated histone is linked to a closed repressed DNA state and a lack of gene expression. The degree of inflammatory gene expression is a result of a balance between histone acetylation and histone deacetylation. One of the major mechanisms of glucocorticoid function is to recruit histone deacetylase enzymes to the site of active gene expression, thus reducing inflammation. Oxidative stress can enhance inflammatory gene expression by further stimulating AP-1- and NF-kappaB-mediated gene expression and elevating histone acetylation. In addition, oxidants can reduce glucocorticoid function by attenuating histone deacetylase activity and expression. Thus, oxidant stress, acting through changes in chromatin structure, can enhance inflammation and induce a state of relative glucocorticoid insensitivity. This may account for the lack of glucocorticoid sensitivity in patients with chronic obstructive pulmonary disease. Antioxidants should reduce the inflammation and restore glucocorticoid sensitivity in these subjects.

The Role of Oxidative Stress in the Pathogenesis??of COPD

Chronic inflammation and oxidative stress are important features in the pathogenesis of COPD. The increased oxidative stress in patients with COPD is the result of an increased burden of inhaled oxidants, as well as increased amounts of reactive oxygen species (ROS) generated by various inflammatory, immune and epithelial cells of the airways. Oxidative stress has important implications on several events of lung physiology and for the pathogenesis of COPD. These include oxidative inactivation of antiproteases and surfactants, mucus hypersecretion, membrane lipid peroxidation, mitochondrial respiration, alveolar epithelial injury, remodeling of extracellular matrix, and apoptosis. An increased level of ROS produced in the airways is reflected by increased markers of oxidative stress in the airspaces, sputum, breath, lungs, and blood in patients with COPD. The biomarkers of oxidative stress such as H2O2, F2-isoprostanes, malondialdehyde and 4-hydroxy-2-nonenal have been successfully measured in breath condensate. ROS and aldehydes play a key role in enhancing the inflammation through the activation of mitogen-activated protein kinases and redox-sensitive transcription factors such as nuclear factor kappa B and activator protein-1. Oxidative stress also alters nuclear histone acetylation and deacetylation leading to increased gene expression of pro-inflammatory mediators in the lung. Oxidative stress may play a role in the poor clinical efficacy of corticosteroids in the treatment of COPD. Since a variety of oxidants, free radicals, and aldehydes are implicated in the pathogenesis of COPD it is likely that a combination of antioxidants may be effective in the treatment of COPD. Antioxidant compounds may also be of therapeutic value in monitoring oxidative biomarkers indicating disease progression. Various approaches to enhance the lung antioxidant screen and the clinical effectiveness of antioxidant compounds in the treatment of COPD are discussed.

Proteinases and oxidants as targets in the treatment of chronic obstructive pulmonary disease

There is now compelling evidence that proteinases and oxidative stress play pathogenetic roles in the following pathologies in chronic obstructive pulmonary disease: airspace enlargement; chronic inflammation in the airways, lung interstitium, and alveolar space; and mucus hypersecretion in the large airways. Proteinases and oxidants may also contribute to remodeling processes in the small airways. In addition, data are emerging that show interactions between classes of proteinases and between proteinases and oxidants, which amplify lung inflammation and injury in chronic obstructive pulmonary disease. This review discusses the biologic roles of proteinases and oxidants, their roles in the pathogenesis of chronic obstructive pulmonary disease, and their potential as targets for therapy.

Influence of naringin on ferric iron induced oxidative damage in vitro

BACKGROUND

Iron is essential for oxygen transport and a variety of cellular processes like respiration and DNA synthesis. It may become toxic when not handled carefully by cellular proteins and shielded from surrounding media. Naringin treatment may help to overcome the iron-induced toxic effects in vitro.

METHODS

HepG2 cells were treated with 0.5, 1, 2.5, and 5 mmol/l naringin 1 h before exposure to 0.1, 0.25, 0.5, and 1 mmol/l ferric iron. The effect of iron or naringin or their combination treatment was studied on cell survival, DNA double-strand break induction, DNA oxidation, lipid peroxidation, and various antioxidants.

RESULTS

The exposure of cells to iron caused a dose-dependent decline in their clonogenic potential, while naringin pretreatment resulted in a significant elevation in the cell survival. Exposure of cells to iron resulted in a time-dependent elevation in DNA strand breaks and a peak level of DNA strand breaks was observed at 24 h, while naringin pretreatment inhibited the DNA double-strand breaks accompanied by an early repair. Similarly, treatment of HepG2 cells with iron caused increased DNA oxidation that showed reduction when cells were pretreated with naringin. The iron overload caused a significant elevation in the lipid peroxidation accompanied by depletion in glutathione (GSH) concentration, while naringin inhibited lipid peroxidation and arrested the iron-induced depletion in the GSH concentration. Iron treatment also reduced various antioxidant enzymes like glutathione peroxidase (GSHPx), catalase, and superoxide dismutase (SOD). Pretreatment of HepG2 cells with naringin resulted in an elevation in all the antioxidant enzymes.

CONCLUSIONS

Enhanced antioxidant status by naringin could compensate the oxidative stress and may facilitate an early recovery from iron-induced genomic insult in vitro.