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

Elevated levels of oxidative stress markers in exhaled breath condensate

INTRODUCTION

Lung cancer is the leading cause of cancer death and oxidative stress secondary to carcinogens such as cigarette smoke has been implicated in its pathogenesis. Therefore, lung cancer patients were hypothesized to have higher levels of oxidative stress markers in their exhaled breath compared with controls.

METHODS

Exhaled breath condensate (EBC) was collected from newly diagnosed subjects with non-small cell lung cancer (NSCLC) and control subjects in a cross-sectional observational study. The samples were then analyzed for hydrogen peroxide (H(2)O(2)), pH, 8-isoprostane, and antioxidant capacity.

RESULTS

A total of 71 subjects (21 NSCLC patients, 21 nonsmokers, 13 exsmokers, and 16 smokers) were recruited. NSCLC patients had significantly higher EBC H(2)O(2) concentration (NSCLC subjects versus smokers, 10.28 microM, 95% confidence interval [CI]: 4.74-22.30 and 2.29 microM, 95% CI: 1.23-4.25, respectively, p = 0.003) and lower antioxidant capacity (NSCLC versus smokers, 0.051 mM, 95% CI: 0.042-0.063 and 0.110 mM, 95% CI: 0.059-0.206, p = 0.023; NSCLC versus all controls as a group, 0.051 mM, 95% CI: 0.042-0.063 and 0.087 mM, 95% CI: 0.067-0.112, p = 0.001). They also had significantly lower pH (5.9, 3.3-7.3) compared with exsmokers (6.7, 5.8-7, p = 0.009).

CONCLUSION

The significant increase of H(2)O(2) and reduction in antioxidant capacity in the EBC of lung cancer patients further support the concept of the disequilibrium between levels of oxidants and antioxidants in lung cancer, which leads to increased oxidative stress. These findings suggest oxidative stress is implicated in the development of lung cancer and may be an early marker of the disease.

Oxidant--antioxidant imbalance in asthma: scientific evidence, epidemiological data and possible therapeutic options

Prevalence of asthma has increased considerably in recent decades throughout the world especially in developed countries. Airway inflammation is thought to be prime cause for repeated episodes of airway obstruction in asthmatics. Several studies have shown that reactive oxygen species (ROS) play a key role in initiation as well as amplification of inflammation in asthmatic airways. Excessive ROS production in asthma leads to alteration in key enzymatic as well as nonenzymatic antioxidants such as glutathione, vitamins C and E, beta-carotene, uric acid, thioredoxin, superoxide dismutases, catalase, and glutathione peroxidases leading to oxidant-antioxidant imbalance in airways. Oxidant-antioxidant imbalance leads to pathophysiological effects associated with asthma such as vascular permeability, mucus hypersecretion, smooth muscle contraction, and epithelial shedding. Epidemiological data also support the scientific evidence of oxidant-antioxidant imbalance in asthmatics. Therefore, the supplementation of antioxidants to boost the endogenous antioxidants or scavenge excessive ROS production could be utilized to dampen/prevent the inflammatory response in asthma by restoring oxidant-antioxidant balance. This review summarizes the scientific and epidemiological evidence linking asthma with oxidant-antioxidant imbalance and possible antioxidant strategies that can be used therapeutically for better management of asthma.

Iron behaving badly: inappropriate iron chelation as a major contributor to the aetiology of vascular and other progressive inflammatory and degenerative diseases

BACKGROUND

The production of peroxide and superoxide is an inevitable consequence of aerobic metabolism, and while these particular 'reactive oxygen species' (ROSs) can exhibit a number of biological effects, they are not of themselves excessively reactive and thus they are not especially damaging at physiological concentrations. However, their reactions with poorly liganded iron species can lead to the catalytic production of the very reactive and dangerous hydroxyl radical, which is exceptionally damaging, and a major cause of chronic inflammation.

REVIEW

We review the considerable and wide-ranging evidence for the involvement of this combination of (su)peroxide and poorly liganded iron in a large number of physiological and indeed pathological processes and inflammatory disorders, especially those involving the progressive degradation of cellular and organismal performance. These diseases share a great many similarities and thus might be considered to have a common cause (i.e. iron-catalysed free radical and especially hydroxyl radical generation).The studies reviewed include those focused on a series of cardiovascular, metabolic and neurological diseases, where iron can be found at the sites of plaques and lesions, as well as studies showing the significance of iron to aging and longevity. The effective chelation of iron by natural or synthetic ligands is thus of major physiological (and potentially therapeutic) importance. As systems properties, we need to recognise that physiological observables have multiple molecular causes, and studying them in isolation leads to inconsistent patterns of apparent causality when it is the simultaneous combination of multiple factors that is responsible.This explains, for instance, the decidedly mixed effects of antioxidants that have been observed, since in some circumstances (especially the presence of poorly liganded iron) molecules that are nominally antioxidants can actually act as pro-oxidants. The reduction of redox stress thus requires suitable levels of both antioxidants and effective iron chelators. Some polyphenolic antioxidants may serve both roles.Understanding the exact speciation and liganding of iron in all its states is thus crucial to separating its various pro- and anti-inflammatory activities. Redox stress, innate immunity and pro- (and some anti-)inflammatory cytokines are linked in particular via signalling pathways involving NF-kappaB and p38, with the oxidative roles of iron here seemingly involved upstream of the IkappaB kinase (IKK) reaction. In a number of cases it is possible to identify mechanisms by which ROSs and poorly liganded iron act synergistically and autocatalytically, leading to 'runaway' reactions that are hard to control unless one tackles multiple sites of action simultaneously. Some molecules such as statins and erythropoietin, not traditionally associated with anti-inflammatory activity, do indeed have 'pleiotropic' anti-inflammatory effects that may be of benefit here.

CONCLUSION

Overall we argue, by synthesising a widely dispersed literature, that the role of poorly liganded iron has been rather underappreciated in the past, and that in combination with peroxide and superoxide its activity underpins the behaviour of a great many physiological processes that degrade over time. Understanding these requires an integrative, systems-level approach that may lead to novel therapeutic targets.

Pivotal role of c-Fos in nitric oxide synthase 2 expression in airway epithelial cells

The regulation of nitric oxide synthase 2 (NOS2) in airway epithelial cells plays a key role in the innate host response to a wide variety of microbial agents and also participates in the generation of pathologic airway inflammation. Among the important signalling cascades that direct NOS2 gene expression are nuclear factor kappaB (NFkappaB) and interferon-gamma (IFNgamma)/signal transducer and activator of transcription 1 (STAT-1). Previous studies suggest activator protein-1 (AP-1), in particular c-Fos component of AP-1, influences NOS2 expression. We investigated the effect of c-Fos modulation using RNA interference siRNA on NOS2 gene expression. A549 cells stably transfected with a plasmid overexpressing a c-Fos siRNA construct (FOSi) resulted in a decrease of NOS2 protein inducibility by IFN gamma. In contrast, classical IFN gamma inducible signal transduction pathways interferon regulated factor-1 (IRF-1) and pSTAT-1 were activated at a similar magnitude in FOSi and control cells. DNA-protein binding assays showed that c-Fos binding was present in wild type cells, but reduced in FOSi clones. FOSi clones had activation of NFkappaB detectable by DNA-protein binding assays, which may have contributed to a decrease of NOS2 expression. Overall, these studies indicate that c-Fos is a requisite and specific component for inducible NOS2 expression.

Glutathione-S-transferases in lung and sputum specimens, effects of smoking and COPD severity

BACKGROUND

Oxidative stress plays a potential role in the pathogenesis and progression of chronic obstructive pulmonary disease (COPD). Glutathione S-transferases (GSTs) detoxify toxic compounds in tobacco smoke via glutathione-dependent mechanisms. Little is known about the regulation and expression of GSTs in COPD lung and their presence in airway secretions.

METHODS

GST alpha, pi and mu were investigated by immunohistochemistry in 72 lung tissue specimens and by Western analysis in total lung homogenates and induced sputum supernatants from non-smokers, smokers and patients with variable stages of COPD severity.

RESULTS

GST alpha was expressed mainly in the airway epithelium. The percentage of GST alpha positive epithelial cells was lower in the central airways of patients with very severe (Stage IV) COPD compared to mild/moderate COPD (p = 0.02). GST alpha by Western analysis was higher in the total lung homogenates in mild/moderate COPD compared to cases of very severe disease (p < 0.001). GST pi was present in airway and alveolar epithelium as well as in alveolar macrophages. GST mu was expressed mainly in the epithelium. Both GST alpha and pi were detectable in sputum supernatants especially in patients with COPD.

CONCLUSION

This study indicates the presence of GST alpha and pi especially in the epithelium and sputum supernatants in mild/moderate COPD and low expression of GST alpha in the epithelium in cases of very severe COPD. The presence of GSTs in the airway secretions points to their potential protective role both as intracellular and extracellular mediators in human lung.

Cigarette smoke extract induces thymic stromal lymphopoietin expression, leading to T(H)2-type immune responses and airway inflammation

BACKGROUND

Both active and passive smoking are considered to be risk factors for asthma development. However, the precise mechanisms involved remain elusive. Recently, thymic stromal lymphopoietin (TSLP) has been shown to play a key role in the development of T(H)2-type allergic inflammation in patients with asthma.

OBJECTIVE

The aim of this study was to investigate whether there was a causal relationship between cigarette smoke exposure and TSLP expression in the lung.

METHODS

We examined the effects of repeated intranasal exposure of cigarette smoke extract (CSE) on TSLP mRNA and protein expression in the mouse lung by means of real-time PCR, Western blotting, and immunohistochemistry. We also examined the effects of intranasal exposure of CSE plus ovalbumin (OVA) on T(H)2-type immune responses and lung pathology.

RESULTS

Repeated exposure of CSE induced TSLP mRNA and protein expression, which was inhibited by treatment with antioxidative N-acetylcysteine and by TNF-alpha receptor I deficiency. In addition, the intranasal exposure of CSE simultaneously with OVA induced OVA-specific T(H)2-type immune responses and airway inflammation, which were inhibited by the blockade of the TSLP activity.

CONCLUSION

CSE induced TSLP expression in the mouse lung in an oxidative stress-dependent and TNF-alpha receptor I-dependent manner, and when challenged simultaneously with an antigen, CSE promoted the development of airway inflammation in association with T(H)2-type immune responses.

Proteomic analysis in lung tissue of smokers and COPD patients

RATIONALE

Although cigarette smoking is the most important risk factor for COPD, COPD develops in only a minority of smokers, suggesting a significant genetic role. To solve the underlying pathophysiologic mechanism, it is critical to understand genes and their final product, ie, proteins. We investigated the exclusive proteins from the lung tissues obtained from COPD patients using proteomics.

METHODS

Nontumorous lung tissue specimens were obtained from patients who underwent surgery for lung cancer. We included 22 subjects: nonsmokers (n = 8), smokers without COPD (healthy smokers, n = 7), and smokers with COPD (n = 7). Proteins were separated from their spots with two-dimensional polyacrylamide gel electrophoresis and examined by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS). To validate the proteins from the above procedures, Western blotting and immunohistochemistry were conducted.

RESULTS

Twelve protein spots from COPD group significantly increased or decreased compared with the other two groups were chosen for MALDI-TOF-MS analysis. Eight proteins were up-regulated in the COPD group as compared with the nonsmokers. Meanwhile, five proteins from the COPD group were up-regulated and five were down-regulated when compared with healthy smokers. Of these, matrix metalloproteinase (MMP)-13 and thioredoxin-like 2 were significantly increased in the COPD patients by Western blot and immunohistochemistry. MMP-13 was mainly expressed in the alveolar macrophages and type II pneumocytes; however, thioredoxin-like 2 was primarily seen in the bronchial epithelium.

CONCLUSIONS

MMP-13 and thioredoxin-like 2 in lungs increased in patients with COPD. MMP-13 was mainly expressed in the alveolar macrophages and type II pneumocytes. In contrast, thioredoxin-like 2 was primarily seen in the bronchial epithelium.

Cigarette smoke worsens lung inflammation and impairs resolution of influenza infection in mice

BACKGROUND

Cigarette smoke has both pro-inflammatory and immunosuppressive effects. Both active and passive cigarette smoke exposure are linked to an increased incidence and severity of respiratory virus infections, but underlying mechanisms are not well defined. We hypothesized, based on prior gene expression profiling studies, that upregulation of pro-inflammatory mediators by short term smoke exposure would be protective against a subsequent influenza infection.

METHODS

BALB/c mice were subjected to whole body smoke exposure with 9 cigarettes/day for 4 days. Mice were then infected with influenza A (H3N1, Mem71 strain), and analyzed 3 and 10 days later (d3, d10). These time points are the peak and resolution (respectively) of influenza infection.

RESULTS

Inflammatory cell influx into the bronchoalveolar lavage (BALF), inflammatory mediators, proteases, histopathology, viral titres and T lymphocyte profiles were analyzed. Compared to smoke or influenza alone, mice exposed to smoke and then influenza had more macrophages, neutrophils and total lymphocytes in BALF at d3, more macrophages in BALF at d10, lower net gelatinase activity and increased activity of tissue inhibitor of metalloprotease-1 in BALF at d3, altered profiles of key cytokines and CD4+ and CD8+ T lymphocytes, worse lung pathology and more virus-specific, activated CD8+ T lymphocytes in BALF. Mice smoke exposed before influenza infection had close to 10-fold higher lung virus titres at d3 than influenza alone mice, although all mice had cleared virus by d10, regardless of smoke exposure. Smoke exposure caused temporary weight loss and when smoking ceased after viral infection, smoke and influenza mice regained significantly less weight than smoke alone mice.

CONCLUSION

Smoke induced inflammation does not protect against influenza infection.In most respects, smoke exposure worsened the host response to influenza. This animal model may be useful in studying how smoke worsens respiratory viral infections.

Lung function loss, smoking, vitamin C intake, and polymorphisms of the glutamate-cysteine ligase genes

RATIONALE

Smoking-induced oxidative stress contributes to chronic obstructive pulmonary disease, a lung disease characterized by low lung function and increasing mortality worldwide. The counterbalance for this effect may be provided by, for example, increased intake of the antioxidant vitamin C or endogenously acting antioxidant enzymes like glutamate-cysteine ligase (GCL), which is responsible for glutathione biosynthesis.

OBJECTIVES

To investigate associations of functional polymorphisms in GCL subunits (GCLM and GCLC) with lung function level and its longitudinal course, with vitamin C and smoking habits as potential interactive factors.

METHODS

Two independent general population samples (Doetinchem, n = 1,152, and Vlagtwedde-Vlaardingen, n = 1,390) with multiple lung function (FEV(1), VC) measurements were genotyped for three polymorphisms (C[-129]T, C[-588]T, and a trinucleotide GAG repeat [TNR]) in the subunits of GCL. Genetic effects on lung function level and decline were estimated using linear regression and linear mixed effect models adjusted for confounders. Findings were further investigated for interactions with vitamin C intake in the Doetinchem cohort.

MEASUREMENTS AND MAIN RESULTS

GCLC polymorphisms were significantly associated with lower lung function levels in interaction with pack-years smoked in both cohorts. TNR variants in GCLC were associated with accelerated FEV(1) decline in both cohorts in interaction with pack-years. All significant effects were specifically present in subjects within the lowest tertile of vitamin C intake.

CONCLUSIONS

GCLC is a novel susceptibility gene for low level of lung function in two independent populations. We provide suggestive evidence that this occurs due to an interaction between GCLC polymorphisms, smoking, and low vitamin C intake, which all contribute to the oxidative burden.

Does the oxidative stress in chronic obstructive pulmonary disease cause thioredoxin/peroxiredoxin oxidation?

The thioredoxin/peroxiredoxin system comprises a redox-regulated antioxidant family in human lung; its significance, regulation, or oxidation has not been evaluated in smoking-related lung diseases. Here, we present the expression of the thioredoxin/peroxiredoxin system in lung biopsies from normal lung (n = 14), smokers (n = 21), and patients with chronic obstructive pulmonary disease (COPD, n = 38), and assess the possible inactivation/oxidation of this system by nonreducing Western blotting, two-dimensional gel electrophoresis, and mass spectrometry. Our study shows that the thiol status of the Trx/Prx-system can be modulated in vitro, but it appears to have high resistance against the oxidative stress in COPD.

Oxidant-antioxidant imbalance as a potential contributor to the progression of human pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is the most common idiopathic interstitial pneumonia. IPF is a disease with poor prognosis and an aggressive nature, and poses major challenges to clinicians. Thus, a large part of research in the area has focused on the pathogenesis on IPF. Characteristic features in IPF include fibrotic lesions devoid of inflammatory cell infiltrates. There are experimental models of lung fibrosis (e.g., bleomycin-induced fibrosis), but they typically contain a prominent inflammatory pattern in the lung, which leads to relatively diffuse lung fibrosis. Nonetheless, experimental models have provided important information about the progression and pathways contributing to the lung fibrosis, including activation of transforming growth factor beta (TGF-beta). Both patient material and experimental models of lung fibrosis have displayed marked elevation of several markers of oxidant burden and signs for disturbed antioxidant/oxidant balance. Several studies also suggest that reactive oxygen species can cause activation of growth-regulatory cytokines, including TGF-beta. In addition, there are indications that endogenous and exogenous antioxidants/redox modulators can influence fibrogenesis, protect the lung against fibrosis, and prevent its progression. Factors that restore the antioxidant capacity and prevent sustained activation of growth-regulatory cytokines may have a therapeutic role in IPF.

Airway biomarkers of the oxidant burden in asthma and chronic obstructive pulmonary disease: current and future perspectives

The pathogenesis of asthma and chronic obstructive pulmonary disease (COPD) has been claimed to be attributable to increased systemic and local oxidative stress. Detection of the oxidant burden and evaluation of their progression and phenotypes by oxidant biomarkers have proved challenging and difficult. A large number of asthmatics are cigarette smokers and smoke itself contains oxidants complicating further the use of oxidant biomarkers. One of the most widely used oxidant markers in asthma is exhaled nitric oxide (NO), which plays an important role in the pathogenesis of asthma and disease monitoring. Another oxidant marker that has been widely investigated in COPD is 8-isoprostane, but it is probably not capable of differentiating asthma from COPD, or even sensitive in the early assessment of these diseases. None of the current biomarkers have been shown to be better than exhaled NO in asthma. There is a need to identify new biomarkers for obstructive airway diseases, especially their differential diagnosis. A comprehensive evaluation of oxidant markers and their combinations will be presented in this review. In brief, it seems that additional analyses utilizing powerful tools such as genomics, metabolomics, lipidomics, and proteomics will be required to improve the specificity and sensitivity of the next generation of biomarkers.

Catalase as a source of both X- and V-factor for Haemophilus influenzae

Haemophilus influenzae requires two growth factors, designated factor X (porphyrin) and factor V (NAD). Mammalian catalases contain both bound heme and NADPH. This study shows that catalase can supply both factors X and V to H. influenzae in vitro, thus representing a potential in vivo source of these essential growth factors.

Matrix metalloproteinases -8, -9 and -12 in smokers and patients with stage 0 COPD

COPD is underdiagnosed and its early assessment is problematic. It has been suggested that symptomatic smokers with normal FEV1/FVC (Stage 0 COPD, GOLD criteria) can develop COPD in the future. Potential early biomarkers in COPD include the matrix metalloproteinases (MMPs). It is not yet known, whether alterations in MMP expression are associated with smoking alone or with the risk of developing COPD. In this cross-sectional study MMP-8, MMP-9 and MMP-12 were determined from induced sputum and plasma by ELISA, immunocytochemistry, zymography, and/or Western blot in non-smokers (n=32), smokers with symptoms (Stage 0, GOLD criteria) (n=23) or without symptoms (n=23). Only MMP-8 differentiated Stage 0 COPD from non-symptomatic smokers (p = 0.02). MMP-9 levels were significantly elevated in the induced sputum of non-symptomatic smokers and Stage 0 COPD (p = 0.01, p < 0.001) compared to non-smokers, but did not differ between the two subgroups of smokers. MMP-12 was higher only at Stage 0 compared to non-smokers (p = 0.04). MMP-8, MMP-9 and MMP-12 immunoreactivity was localized in macrophages and neutrophils, especially in smokers. MMP-8 levels correlated significantly with the small airway flow parameters (MEF50, MEF25) (p = 0.005 and p = 0.0004) and markers of neutrophil activation (myeloperoxidase, lactoferrin). In conclusion MMP-8 may differentiate Stage 0 from healthy smokers.

Endothelial nitric oxide synthase gene variants contribute to oxidative stress in COPD

Nitric oxide (NO) plays critical role in endothelial dysfunction and oxidative stress in COPD, pointing to the significance of endothelial nitric oxide synthase gene (eNOS) variants. We investigated the association of -786T/C, -922A/G, 4B/4A, and 894G/T polymorphisms of eNOS with the disease and its impact on nitrite and malonaldehyde levels in 190 COPD patients and 134 healthy controls, all smokers. The -786C, -922G and 4A alleles were significantly over-represented in patients (p=0.02, p=0.02, and p=0.03, respectively). The haplotypes, -786C:4A, 4A:894G, -786C:894G, and -786C:4A:894G were significantly over-represented in patients (p<0.0001, p =0.02, p=0.02, and p <0.0001, respectively), whereas, haplotypes, -786T:4B, 4B:894G, -786T:894G, and -786T:4B:894G were significantly under-represented in the patients (p<0.0001). The patients had significantly increased levels of nitrite (p=0.003) and malonaldehyde (p<0.0001). Combination of genotypes containing -786C and 4A alleles were greater in patients (p 0.05), and these combinations associated with decreased FEV1 value and nitrite level (p=0.03 and p=0.04, respectively) and with increased malonaldehyde levels (p=0.02). The eNOS -786C, -922G, and 4A alleles, these alleles associated haplotypes and genotype combinations were over-represented in patients. The variants and their combinations of four polymorphisms of eNOS contribute to disturbed pulmonary function and oxidative stress in COPD.

Association between paraoxonase-1 Q192R polymorphism and lung function among Saskatchewan grain handlers

Introduction: Paraoxonase-1 (PON1) is a high-density, lipoprotein-associated, multifunctional antioxidant enzyme that is detected in nonciliated bronchiolar epithelial cells, although its role in the lung has not yet been clarified. We therefore investigated the association between the PON1 Q192R polymorphism and lung function. Patients & Methods: A total of 216 male Saskatchewan grain handlers provided demographic, occupational and respiratory-symptom information by means of questionnaires, and thereafter underwent PON1 Q192R genotyping and lung-function testing. Results: Mean lung-function values did not differ among the Q192R genotypes. However, current smokers with the Q/Q genotype had a higher mean percent predicted forced expiratory volume in the first second (FEV1), and absolute and percent predicted FEV1 per forced vital capacity (FVC) compared with current smokers with at least one 192R allele (100.9 ± 11.2% vs 92.0 ± 15.1%, p = 0.01; 78.0 ± 5.9% vs 74.1 ± 6.8%, p = 0.03; and 96.8 ± 7.1% vs 92.1 ± 8.3%, p = 0.03; respectively). The incidence of subjects with FEV1/FVC less than 70% was significantly higher in current smokers with at least one 192R allele than in nonsmokers with the Q/Q genotype (odds ratio: 5.0; 95% confidence interval: 1.5–17.4). The protective effect of the Q/Q genotype was not found in nonsmokers. The FVC was not influenced by either PON1 genotype or smoking status. Conclusion: The results obtained from grain handlers suggest that PON1 may play some role in the protection of the airways against the toxicity of cigarette smoke, and the 192R allele may be a novel genetic risk factor for airway injury.

Glutathione S-transferase omega in the lung and sputum supernatants of COPD patients

Background

The major contribution to oxidant related lung damage in COPD is from the oxidant/antioxidant imbalance and possibly impaired antioxidant defence. Glutathione (GSH) is one of the most important antioxidants in human lung and lung secretions, but the mechanisms participating in its homeostasis are partly unclear. Glutathione-S-transferase omega (GSTO) is a recently characterized cysteine containing enzyme with the capability to bind and release GSH in vitro. GSTO has not been investigated in human lung or lung diseases.

Methods

GSTO1-1 was investigated by immunohistochemistry and Western blot analysis in 72 lung tissue specimens and 40 sputum specimens from non-smokers, smokers and COPD, in bronchoalveolar lavage fluid and in plasma from healthy non-smokers and smokers. It was also examined in human monocytes and bronchial epithelial cells and their culture mediums in vitro.

Results

GSTO1-1 was mainly expressed in alveolar macrophages, but it was also found in airway and alveolar epithelium and in extracellular fluids including sputum supernatants, bronchoalveolar lavage fluid, plasma and cell culture mediums. The levels of GSTO1-1 were significantly lower in the sputum supernatants (p = 0.023) and lung homogenates (p = 0.003) of COPD patients than in non-smokers.

Conclusion

GSTO1-1 is abundant in the alveolar macrophages, but it is also present in extracellular fluids and in airway secretions, the levels being decreased in COPD. The clinical significance of GSTO1-1 and its role in regulating GSH homeostasis in airway secretions, however, needs further investigations.

Protection from acute and chronic lung diseases by curcumin

The aim of this review has been to describe the current state of the therapeutic potential of curcumin in acute and chronic lung injuries. Occupational and environmental exposures to mineral dusts, airborne pollutants, cigarette smoke, chemotherapy, and radiotherapy injure the lungs, resulting in acute and chronic inflammatory lung diseases. Despite major advances in treating lung diseases, until now disease-modifying efficacy has not been demonstrated for any of the existing drugs. Current medical therapy offers only marginal benefit; therefore, there is an essential need to develop new drugs that might be of effective benefit in clinical settings. Over the years, there has been increasing evidence that curcumin, a phytochemical present in turmeric (Curcuma longa), has a wide spectrum of therapeutic properties and a remarkable range of protective effects in various diseases. Several experimental animal models have tested curcumin on lung fibrosis and these studies demonstrate that curcumin attenuates lung injury and fibrosis caused by radiation, chemotherapeutic drugs, and toxicants. The growing amount of data from pharmacological and animal studies also supports the notion that curcumin plays a protective role in chronic obstructive pulmonary disease, acute lung injury, acute respiratory distress syndrome, and allergic asthma, its therapeutic action being on the prevention or modulation of inflammation and oxidative stress. These findings give substance to the possibility of testing curcumin in patients with lung diseases.

Increased hydrogen peroxide concentration in the exhaled breath condensate of stable COPD patients after nebulized N-acetylcysteine

BACKGROUND

The oxidative burden in the airways is a hallmark of chronic obstructive pulmonary disease (COPD).

AIMS

This prospective, cross-over, placebo (PL)-controlled study was designed to investigate the effect of N-acetyl-l-cysteine (NAC) on hydrogen peroxide (H(2)O(2)), nitrites and nitrates (NO(2)(-)+NO(3)(-)), and thiol (RSH) concentrations in exhaled breath condensate (EBC) in stable COPD patients (n=19, aged 52.6+/-15.6 years, 10 females, mean FEV(1) 95.2+/-23.8%, FEV(1)/FVC 69.1+/-11.4%).

METHODS

H(2)O(2), NO(2)(-)+NO(3)(-) and RSH concentrations in EBC were determined with homovanillic acid, NADPH-nitrite reductase assays and Ellman's reaction, respectively.

RESULTS

Thirty minutes after nebulization, H(2)O(2) concentration increased if levels after NAC (0.45+/-0.25microM) and PL (0.17+/-0.17microM) were compared in COPD patients (p=0.002). This increased H(2)O(2) level in EBC was no longer observed either after 90min: 0.16+/-0.09microM (PL 0.17+/-0.15microM) or 3h: 0.12+/-0.07microM (PL 0.21+/-0.23microM) (p=0.5 and 0.2, respectively). The levels of NO(2)(-) and NO(3)(-) did not differ between NAC and PL. There was no significant difference in RSH levels between nebulized NAC and PL. After nebulized NAC, however, exhaled RSH increased from 1.42+/-1.69microM (0min) to 2.49+/-2.00microM (30min), and 1.71+/-1.83microM (180min) (p=0.009 and 0.03, respectively, compared with 0min).

CONCLUSIONS

These data demonstrate that nebulized NAC transiently increases exhaled H(2)O(2) level, whereas it has no effect on other oxidative parameters.

Chronic bronchitis and chronic obstructive pulmonary disease. The Finnish Action Programme, interim report

The Finnish National Prevention and Treatment Programme for Chronic Bronchitis and COPD, launched in 1998, has, to date, been running for 6 years (2003). The goals of this action programme were to reduce the incidence of COPD and the number of moderate and severe cases of the disease, and to reduce both the number of days of hospitalisation and treatment costs. A prevalent implementation of over 250 information and training events started. Health centres and pharmacies appointed a person in charge of COPD patients. In order to improve the cooperation between primary and specialised care, two thirds of hospital districts created local COPD treatment chains. The early diagnosis of COPD by spirometric examination was activated during the programme. Number of health centres with available spirometric services increased to 95%. Before the start of the programme, approximately 5-9% of the adult population had COPD. During the whole programme, the proportion of male and female smokers decreased from 30% to 26% and from 20% to 19%, respectively. The total number of hospitalisation periods and days due to COPD decreased by 15% and 18%, respectively. Both the number of pensioners and daily sickness days due to COPD also decreased by 18%. Registered COPD induced deaths remained at their previous levels during the monitoring period, i.e. around 1000 deaths out of 5.2 millions annually. The measures recommended by the programme have been widely introduced but they need to be still more effective.

Analysis of bronchoalveolar lavage fluid proteome from systemic sclerosis patients with or without functional, clinical and radiological signs of lung fibrosis

Lung fibrosis is a major cause of mortality and morbidity in systemic sclerosis (SSc). However, its pathogenesis still needs to be elucidated. We examined whether the alteration of certain proteins in bronchoalveolar lavage fluid (BALF) might have a protective or a causative role in the lung fibrogenesis process. For this purpose we compared the BALF protein profile obtained from nine SSc patients with lung fibrosis (SSc_Fib+) with that obtained from six SSc patients without pulmonary fibrosis (SSc_Fib-) by two-dimensional gel electrophoresis (2-DE). Only spots and spot-trains that were consistently expressed in a different way in the two study groups were taken into consideration. In total, 47 spots and spot-trains, corresponding to 30 previously identified proteins in human BALF, showed no significant variation between SSc_Fib+ patients and SSc_Fib- patients, whereas 24 spots showed a reproducible significant variation in the two study groups. These latter spots corresponded to 11 proteins or protein fragments, including serum albumin fragments (13 spots), 5 previously recognized proteins (7 spots), and 4 proteins (3 spots) that had not been previously described in human BALF maps, namely calumenin, cytohesin-2, cystatin SN, and mitochondrial DNA topoisomerase 1 (mtDNA TOP1). Mass analysis did not determine one protein-spot. The two study groups revealed a significant difference in BALF protein composition. Whereas levels of glutathione S-transferase P (GSTP), Cu–Zn superoxide dismutase (SOD) and cystatin SN were downregulated in SSc_Fib+ patients compared with SSc_Fib- patients, we observed a significant upregulation of α1-acid glycoprotein, haptoglobin-α chain, calgranulin (Cal) B, cytohesin-2, calumenin, and mtDNA TOP1 in SSc_Fib+ patients. Some of these proteins (GSTP, Cu–Zn SOD, and cystatin SN) seem to be involved in mechanisms that protect lungs against injury or inflammation, whereas others (Cal B, cytohesin-2, and calumenin) seem to be involved in mechanisms that drive lung fibrogenesis. Even if the 2-DE analysis of BALF did not provide an exhaustive identification of all BALF proteins, especially those of low molecular mass, it allows the identification of proteins that might have a role in lung fibrogenesis. Further longitudinal studies on larger cohorts of patients will be necessary to assess their usefulness as predictive markers of disease.

The receptor for advanced glycation end products and its ligands: a new inflammatory pathway in lung disease?

The binding of the receptor for advanced glycation end products (RAGE) with its ligands begins a sustained period of cellular activation and inflammatory signal amplification in different tissues and diseases. This binding could represent an as yet uninvestigated pathway of inflammatory reaction in the lung, where the presence of the receptor has been largely documented and advanced glycation end products (AGEs) are produced by nonenzymatic glycation and oxidation of proteins and lipids, driven by smoke and pollutants exposure or inflammatory stress. We immunohistochemically assessed the expression of RAGE and of its major proinflammatory ligands, N-epsilon-carboxy-methyl-lysine, S100B and S-100A12 in normal lung and in non-neoplastic lung disorders including smoke-related airway disease, granulomatous inflammation, postobstructive damage and usual interstitial pneumonia. In normal lung low expression of the receptor was observed in bronchiolar epithelia, type II pneumocytes, macrophages and some endothelia. S100A12 and S100B were expressed, respectively, in granulocytes and in dendritic cells. Carboxy-methyl-lysine was present in bronchiolar epithelia and macrophages. In all pathological conditions associated with inflammation and lung damage overexpression of both the receptor and of AGEs was observed in bronchiolar epithelia, type II alveolar pneumocytes, alveolar macrophages and endothelia. RAGE overexpression was more evident in epithelia associated with inflammatory cell aggregates. Fibroblasts in usual interstitial pneumonia expressed both the receptor and AGEs. The number of S100A12 and S100B immunoreactive inflammatory cells was variable. S100A12 was also expressed in mononuclear inflammatory cells and in activated epithelia. The activation of the inflammatory pathway controlled by the RAGE is not specific of a single lung disease, however, it may be relevant as a nonspecific pathway of sustained inflammation in lung tissue, and on this basis therapeutic approaches based on receptor blockage can be envisaged.

Modulation of glutaredoxin in the lung and sputum of cigarette smokers and chronic obstructive pulmonary disease

BACKGROUND

One typical feature in chronic obstructive pulmonary disease (COPD) is the disturbance of the oxidant/antioxidant balance. Glutaredoxins (Grx) are thiol disulfide oxido-reductases with antioxidant capacity and catalytic functions closely associated with glutathione, the major small molecular weight antioxidant of human lung. However, the role of Grxs in smoking related diseases is unclear.

METHODS

Immunohistochemical and Western blot analyses were conducted with lung specimens (n = 45 and n = 32, respectively) and induced sputum (n = 50) of healthy non-smokers and smokers without COPD and at different stages of COPD.

RESULTS

Grx1 was expressed mainly in alveolar macrophages. The percentage of Grx1 positive macrophages was significantly lower in GOLD stage IV COPD than in healthy smokers (p = 0.021) and the level of Grx1 in total lung homogenate decreased both in stage I-II (p = 0.045) and stage IV COPD (p = 0.022). The percentage of Grx1 positive macrophages correlated with the lung function parameters (FEV1, r = 0.45, p = 0.008; FEV1%, r = 0.46, p = 0.007, FEV/FVC%, r = 0.55, p = 0.001). Grx1 could also be detected in sputum supernatants, the levels being increased in the supernatants from acute exacerbations of COPD compared to non-smokers (p = 0.013) and smokers (p = 0.051).

CONCLUSION

The present cross-sectional study showed that Grx1 was expressed mainly in alveolar macrophages, the levels being decreased in COPD patients. In addition, the results also demonstrated the presence of Grx1 in extracellular fluids including sputum supernatants. Overall, the present study suggests that Grx1 is a potential redox modulatory protein regulating the intracellular as well as extracellular homeostasis of glutathionylated proteins and GSH in human lung.

Migrating leukocytes are the source of peroxiredoxin V during inflammation in the airways

Background

We characterized changes in expression of the antioxidant protein Peroxiredoxin V (PRXV) during airway inflammation.

Methods

Studies in anesthetized rats and mice; PRXV expression determined by Western blot analyses and immunohistochemistry; PRXV m-RNA expression determined by Taq-Man RT-PCR.

Results

Bacterial lung inflammation did not change expression of PRXV in murine epithelia but produced massive influx of leukocytes highly expressing PRXV. Endotoxin and f-MLP induced leukocyte migration in rat trachea but did not change mRNA levels and PRXV protein expression in tracheal epithelial cells. In primary airway cell culture (cow), alveolar epithelial cells A549, or co-culture of A549 with murine macrophages RAW264.7, exposure to live bacteria increased expression of PRXV, which required serum. PRXV was secreted in vitro by epithelial and immune cells.

Conclusion

Inflammation increased expression of PRXV in airways by at least 2 mechanisms: cell population shift by massive influx of leukocytes expressing PRXV, and moderate post-transcriptional up-regulation of PRXV in epithelial cells.

Long term smoking with age builds up excessive oxidative stress in bronchoalveolar lavage fluid

BACKGROUND

Epithelial lining fluid plays a critical role in protecting the lung from oxidative stress, in which the oxidised status may change by ageing, smoking history, and pulmonary emphysema.

METHODS

Bronchoalveolar lavage (BAL) was performed on 109 young and older subjects with various smoking histories. The protein carbonyls, total and oxidised glutathione were examined in BAL fluid.

RESULTS

By Western blot analysis, the major carbonylated protein in the BAL fluid was sized at 68 kDa, corresponding to albumin. The amount of carbonylated albumin per mg total albumin in BAL fluid was four times higher in older current smokers and three times higher in older former smokers than in age matched non-smokers (p<0.0001, p=0.0003, respectively), but not in young smokers. Total glutathione in BAL fluid was significantly increased both in young (p=0.006) and older current smokers (p=0.0003) compared with age matched non-smokers. In contrast, the ratio of oxidised to total glutathione was significantly raised (72%) only in older current smokers compared with the other groups. There was no significant difference in these parameters between older smokers with and without mild emphysema.

CONCLUSIONS

Oxidised glutathione associated with excessive protein carbonylation accumulates in the lung of older smokers with long term smoking histories even in the absence of lung diseases, but they are not significantly enhanced in smokers with mild emphysema.

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.