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

Pannexin hemichannels: A novel promising therapy target for oxidative stress related diseases

Pannexins, which contain three subtypes: pannexin-1, -2, and -3, are vertebrate glycoproteins that form non-junctional plasma membrane intracellular hemichannels via oligomerization. Oxidative stress refers to an imbalance of the generation and elimination of reactive oxygen species (ROS). Studies have shown that elevated ROS levels are pivotal in the development of a variety of diseases. Recent studies indicate that the occurrence of these oxidative stress related diseases is associated with pannexin hemichannels. It is also reported that pannexins regulate the production of ROS which in turn may increase the opening of pannexin hemichannels. In this paper, we review recent researches about the important role of pannexin hemichannels in oxidative stress related diseases. Thus, pannexin hemichannels, novel therapeutic targets, hold promise in managing oxidative stress related diseases such as the tumor, inflammatory bowel diseases (IBD), pulmonary fibrosis, chronic obstructive pulmonary disease (COPD), cardiovascular disease, insulin resistance (IR), and neural degeneration diseases.

Advanced glycation end-products produced systemically and by macrophages: A common contributor to inflammation and degenerative diseases

Advanced glycation end products (AGEs) and their receptor have been implicated in the progressions of many intractable diseases, such as diabetes and atherosclerosis, and are also critical for pathologic changes in chronic degenerative diseases, such as Alzheimer's disease, Parkinson's disease, and alcoholic brain damage. Recently activated macrophages were found to be a source of AGEs, and the most abundant form of AGEs, AGE-albumin excreted by macrophages has been implicated in these diseases and to act through common pathways. AGEs inhibition has been shown to prevent the pathogenesis of AGEs-related diseases in human, and therapeutic advances have resulted in several agents that prevent their adverse effects. Recently, anti-inflammatory molecules that inhibit AGEs have been shown to be good candidates for ameliorating diabetic complications as well as degenerative diseases. This review was undertaken to present, discuss, and clarify current understanding regarding AGEs formation in association with macrophages, different diseases, therapeutic and diagnostic strategy and links with RAGE inhibition.

Paeoniflorin Attenuated Oxidative Stress in Rat COPD Model Induced by Cigarette Smoke

Paeoniflorin (PF), a monoterpene glucoside, might have an effect on the oxidative stress. However, the mechanism is still unknown. In this study, we made the COPD model in Sprague-Dawley (SD) rats by exposing them to the smoke of 20 cigarettes for 1 hour/day and 6 days/week, for 12 weeks, 24 weeks, or 36 weeks. Our findings suggested that smoke inhalation can trigger the oxidative stress from the very beginning. A 24-week treatment of PF especially in the dosage of 40 mg/kg·d can attenuate oxygen stress by partially quenching reactive oxygen species (ROS) and upregulating antioxidant enzymes via an Nrf2-dependent mechanism.

Protein oxidation and degradation caused by particulate matter

Particulate matter (PM) modulates the expression of autophagy; however, the role of selective autophagy by PM remains unclear. The objective of this study was to determine the underlying mechanisms in protein oxidation and degradation caused by PM. Human epithelial A549 cells were exposed to diesel exhaust particles (DEPs), urban dust (UD), and carbon black (CB; control particles). Cell survival and proliferation were significantly reduced by DEPs and UD in A549 cells. First, benzo(a)pyrene diolepoxide (BPDE) protein adduct was caused by DEPs at 150 μg/ml. Methionine oxidation (MetO) of human albumin proteins was induced by DEPs, UD, and CB; however, the protein repair mechanism that converts MetO back to methionine by methionine sulfoxide reductases A (MSRA) and B3 (MSRB3) was activated by DEPs and inhibited by UD, suggesting that oxidized protein was accumulating in cells. As to the degradation of oxidized proteins, proteasome and autophagy activation was induced by CB with ubiquitin accumulation, whereas proteasome and autophagy activation was induced by DEPs without ubiquitin accumulation. The results suggest that CB-induced protein degradation may be via an ubiquitin-dependent autophagy pathway, whereas DEP-induced protein degradation may be via an ubiquitin-independent autophagy pathway. A distinct proteotoxic effect may depend on the physicochemistry of PM.

Phenotypic assessment of pulmonary hypertension using high-resolution echocardiography is feasible in neonatal mice with experimental bronchopulmonary dysplasia and pulmonary hypertension: a step toward preventing chronic obstructive pulmonary disease

Bronchopulmonary dysplasia (BPD) and chronic obstructive pulmonary disease (COPD) are chronic lung diseases of human infants and adults, respectively, that are characterized by alveolar simplification. One-third of the infants with severe BPD develop pulmonary hypertension (PH). More importantly, PH increases morbidity and mortality in BPD patients. Additionally, COPD is a common respiratory morbidity in former BPD patients. The lack of an appropriate small animal model wherein echocardiography (Echo) can demonstrate PH is one of the major barriers to understand the molecular mechanisms of the disease and, thereby, develop rational therapies to prevent and/or treat PH in BPD patients. Thus, the goal of this study was to establish a model of experimental BPD and PH and investigate the feasibility of Echo to diagnose PH in neonatal mice. Since hyperoxia-induced oxidative stress and inflammation contributes to the development of BPD with PH, we tested the hypothesis that exposure of newborn C57BL/6J mice to 70% O2 (hyperoxia) for 14 days leads to lung oxidative stress, inflammation, alveolar and pulmonary vascular simplification, pulmonary vascular remodeling, and Echo evidence of PH. Hyperoxia exposure caused lung oxidative stress and inflammation as evident by increased malondialdehyde adducts and inducible nitric oxide synthase, respectively. Additionally, hyperoxia exposure caused growth restriction, alveolar and pulmonary vascular simplification, and pulmonary vascular remodeling. At 14 days of age, Echo of these mice demonstrated that hyperoxia exposure decreased pulmonary acceleration time (PAT) and PAT/ejection time ratio and increased right ventricular free wall thickness, which are indicators of significant PH. Thus, we have demonstrated the feasibility of Echo to phenotype PH in neonatal mice with experimental BPD with PH, which can aid in discovery of therapies to prevent and/or treat BPD with PH and its sequelae such as COPD in humans.

Glyco-redox, a link between oxidative stress and changes of glycans: Lessons from research on glutathione, reactive oxygen and nitrogen species to glycobiology

Reduction-oxidation (redox) response is one of the most important biological phenomena. The concept introduced by Helmut Sies encouraged many researchers to examine oxidative stress under pathophysiological conditions. Our group has been interested in redox regulation under oxidative stress as well as glycobiology in relation to disease. Current studies by our group and other groups indicate that functional and structural changes of glycans are regulated by redox responses resulting from the generation of reactive oxygen species (ROS) or reactive nitrogen species (RNS) in various diseases including cancer, diabetes, neurodegenerative disease such as Parkinson disease, Alzheimer's disease and amyotrophic lateral sclerosis (ALS), and chronic obstructive pulmonary disease (COPD), even though very few investigators appear to be aware of these facts. Here we propose that the field "glyco-redox" will open the door to a more comprehensive understanding of the mechanism associated with diseases in relation to glycan changes under oxidative stress. A tight link between structural and functional changes of glycans and redox system under oxidative stress will lead to the recognition and interest of these aspects by many scientists. Helmut's contribution in this field facilitated our future perspectives in glycobiology.

Metabolic Signatures of Oxidative Stress and Their Relationship with Erythrocyte Membrane Surface Roughness Among Workers of Manual Materials Handling (MMH)

Background:

Brickfield workers in India perform manual materials handling (MMH) and as a result, are at a high risk of developing oxidative stress. This results in an alteration of the various markers of metabolic oxidative stress at the cellular level. Since red blood cell (RBC) is the central point where oxygen, glucose-6-phosphate dehydrogenase (G-6-PD), and glutathione (GSH) are involved, the surface roughness and its alteration and modeling with respect to workers exposed to MMH may be considered as helpful determinants in predicting early damage to the cell and restoring better health to the exposed population, that is, the worker exposed to stress. Hence, nanometric analysis of the surface roughness of the RBC may serve as an early indicator of the stress-related damage in these individuals.

Aims:

The purpose of the study was to identify early red blood corpuscular surface damage profile in terms of linear modeling correlating various biochemical parameters. Linear modeling has been aimed to be developed in order to demonstrate how individual oxidative stress markers such as malondialdehyde (MDA), G-6-PD, and reduced GSH are related to the RBC surface roughness [root mean square (RMS)].

Materials and Methods:

Conventional analysis of these biochemical responses were evaluated in MMH laborers (age varying between 18 years and 21 years) and a comparable control group of the same age group (with sedentary lifestyles). Peak expiratory flow rate (PEFR) and RBC surface analysis by atomic-force microscopy (AFM) and correlated scanning probe microscopy (SPM-analytical software) with corresponding image analysis were performed immediately after completion of standardized exercise (MMH) at the brickfield.

Results:

A number of correlated significances and regressive linear models were developed among MDA, G-6-PD, GSH, and RBC surface roughness.

Conclusion:

It appears that these linear models might be instrumental in predicting early oxidative damages related to specific occupational hazards.

Neutrophilic Bronchial Inflammation Correlates with Clinical and Functional Findings in Patients with Noncystic Fibrosis Bronchiectasis

Background. Neutrophilic bronchial inflammation is a main feature of bronchiectasis, but not much is known about its relationship with other disease features. Aim. To compare airway inflammatory markers with clinical and functional findings in subjects with stable noncystic fibrosis bronchiectasis (NCFB). Methods. 152 NFCB patients (62.6 years; females: 57.2%) underwent clinical and functional cross-sectional evaluation, including microbiologic and inflammatory cell profile in sputum, and exhaled breath condensate malondialdehyde (EBC-MDA). NFCB severity was assessed using BSI and FACED criteria. Results. Sputum neutrophil percentages inversely correlated with FEV1 (P < 0.0001; rho = -0.428), weakly with Leicester Cough Questionnaire score (P = 0.068; rho = -0.58), and directly with duration of the disease (P = 0.004; rho = 0.3) and BSI severity score (P = 0.005; rho = 0.37), but not with FACED. Sputum neutrophilia was higher in colonized subjects, P. aeruginosa colonized subjects showing greater sputum neutrophilia and lower FEV1. Patients with ≥3 exacerbations in the last year showed a significantly greater EBC-MDA than the remaining patients. Conclusions. Sputum neutrophilic inflammation and biomarkers of oxidative stress in EBC can be considered good biomarkers of disease severity in NCFB patients, as confirmed by pulmonary function, disease duration, bacterial colonization, BSI score, and exacerbation rate.

The aryl hydrocarbon receptor suppresses cigarette-smoke-induced oxidative stress in association with dioxin response element (DRE)-independent regulation of sulfiredoxin 1

The aryl hydrocarbon receptor (AhR) is a ubiquitously expressed receptor/transcription factor that mediates toxicological responses of environmental contaminants such as 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). Emerging evidence indicates that the AhR suppresses apoptosis and proliferation independent of exogenous ligands, including suppression of apoptosis by cigarette smoke, a key risk factor for chronic obstructive pulmonary disease (COPD). As cigarette smoke is a potent inducer of oxidative stress, a feature that may contribute to the development of COPD, we hypothesized that the AhR prevents smoke-induced apoptosis by regulating oxidative stress. Utilizing primary lung fibroblasts derived from AhR(+/+) and AhR(-/-) mice as well as A549 human lung adenocarcinoma cells deficient in AhR expression (A549-AhR(ko)), we first show that AhR(-/-) fibroblasts and A549-AhR(ko) epithelial cells have a significant increase in cigarette smoke extract (CSE)-induced oxidative stress compared to wild type. CSE induced a significant increase in the mRNA expression of key antioxidant genes, including Nqo1 and Srxn1, predominantly in AhR(+/+) fibroblasts, with significantly less induction in AhR(-/-) cells. The induction of Srxn1, but not Nqo1, was independent of dioxin-response element (DRE) binding as AhR(DBD/DBD) lung fibroblasts, which express an AhR incapable of binding the DRE, increased Srxn1 to a degree similar to wild-type cells in response to CSE. There was no difference in Nrf2 expression or activation based on AhR expression. Lung fibroblasts derived from COPD subjects have significantly less AhR protein expression compared with both never-smokers (Normal) and smokers (At Risk). Consequently, COPD-derived fibroblasts were less robust in their induction of both Nqo1 and Srxn1 mRNA after exposure to CSE, which also failed to activate the AhR in the COPD fibroblasts. Taken together, these results support a new role for the AhR in regulating antioxidant defense in lung structural cells, such that low AhR expression may facilitate the development or progression of COPD.

Alcohol, Aldehydes, Adducts and Airways

Drinking alcohol and smoking cigarettes results in the formation of reactive aldehydes in the lung, which are capable of forming adducts with several proteins and DNA. Acetaldehyde and malondialdehyde are the major aldehydes generated in high levels in the lung of subjects with alcohol use disorder who smoke cigarettes. In addition to the above aldehydes, several other aldehydes like 4-hydroxynonenal, formaldehyde and acrolein are also detected in the lung due to exposure to toxic gases, vapors and chemicals. These aldehydes react with nucleophilic targets in cells such as DNA, lipids and proteins to form both stable and unstable adducts. This adduction may disturb cellular functions as well as damage proteins, nucleic acids and lipids. Among several adducts formed in the lung, malondialdehyde DNA (MDA-DNA) adduct and hybrid malondialdehyde-acetaldehyde (MAA) protein adducts have been shown to initiate several pathological conditions in the lung. MDA-DNA adducts are pre-mutagenic in mammalian cells and induce frame shift and base-pair substitution mutations, whereas MAA protein adducts have been shown to induce inflammation and inhibit wound healing. This review provides an insight into different reactive aldehyde adducts and their role in the pathogenesis of lung disease.

Targeting oxidant-dependent mechanisms for the treatment of COPD and its comorbidities

Chronic obstructive pulmonary disease (COPD) is an incurable global health burden and is characterised by progressive airflow limitation and loss of lung function. In addition to the pulmonary impact of the disease, COPD patients often develop comorbid diseases such as cardiovascular disease, skeletal muscle wasting, lung cancer and osteoporosis. One key feature of COPD, yet often underappreciated, is the contribution of oxidative stress in the onset and development of the disease. Patients experience an increased burden of oxidative stress due to the combined effects of excess reactive oxygen species (ROS) and nitrogen species (RNS) generation, antioxidant depletion and reduced antioxidant enzyme activity. Currently, there is a lack of effective treatments for COPD, and an even greater lack of research regarding interventions that treat both COPD and its comorbidities. Due to the involvement of oxidative stress in the pathogenesis of COPD and many of its comorbidities, a unique therapeutic opportunity arises where the treatment of a multitude of diseases may be possible with only one therapeutic target. In this review, oxidative stress and the roles of ROS/RNS in the context of COPD and comorbid cardiovascular disease, skeletal muscle wasting, lung cancer, and osteoporosis are discussed and the potential for therapeutic benefit of anti-oxidative treatment in these conditions is outlined. Because of the unique interplay between oxidative stress and these diseases, oxidative stress represents a novel target for the treatment of COPD and its comorbidities.

Oral antioxidants improve leg blood flow during exercise in patients with chronic obstructive pulmonary disease

The consequence of elevated oxidative stress on exercising skeletal muscle blood flow as well as the transport and utilization of O2 in patients with chronic obstructive pulmonary disease (COPD) is not well understood. The present study examined the impact of an oral antioxidant cocktail (AOC) on leg blood flow (LBF) and O2 consumption during dynamic exercise in 16 patients with COPD and 16 healthy subjects. Subjects performed submaximal (3, 6, and 9 W) single-leg knee extensor exercise while LBF (Doppler ultrasound), mean arterial blood pressure, leg vascular conductance, arterial O2 saturation, leg arterial-venous O2 difference, and leg O2 consumption (direct Fick) were evaluated under control conditions and after AOC administration. AOC administration increased LBF (3 W: 1,604 ± 100 vs. 1,798 ± 128 ml/min, 6 W: 1,832 ± 109 vs. 1,992 ± 120 ml/min, and 9W: 2,035 ± 114 vs. 2,187 ± 136 ml/min, P < 0.05, control vs. AOC, respectively), leg vascular conductance, and leg O2 consumption (3 W: 173 ± 12 vs. 210 ± 15 ml O2/min, 6 W: 217 ± 14 vs. 237 ± 15 ml O2/min, and 9 W: 244 ± 16 vs 260 ± 18 ml O2/min, P < 0.05, control vs. AOC, respectively) during exercise in COPD, whereas no effect was observed in healthy subjects. In addition, the AOC afforded a small, but significant, improvement in arterial O2 saturation only in patients with COPD. Thus, these data demonstrate a novel beneficial role of AOC administration on exercising LBF, O2 consumption, and arterial O2 saturation in patients with COPD, implicating oxidative stress as a potential therapeutic target for impaired exercise capacity in this population.

Association of Lung Inflammatory Cells with Small Airways Function and Exhaled Breath Markers in Smokers - Is There a Specific Role for Mast Cells?

Background

Smoking is associated with a mixed inflammatory infiltrate in the airways. We evaluated whether airway inflammation in smokers is related to lung function parameters and inflammatory markers in exhaled breath.

Methods

Thirty-seven smokers undergoing lung resection for primary lung cancer were assessed pre-operatively by lung function testing including single-breath-nitrogen washout test (sb-N2-test), measurement of fractional exhaled nitric oxide (FeNO) and pH/8-isoprostane in exhaled breath condensate (EBC). Lung tissue sections containing cancer-free large (LA) and small airways (SA) were stained for inflammatory cells. Mucosal (MC_T) respectively connective tissue mast cells (MC_TC) and interleukin-17A (IL-17A) expression by mast cells was analysed using a double-staining protocol.

Results

The median number of neutrophils, macrophages and mast cells infiltrating the lamina propria and adventitia of SA was higher than in LA. Both MCTC and MC_T were higher in the lamina propria of SA compared to LA (MC_TC: 49 vs. 27.4 cells/mm²; MC_T: 162.5 vs. 35.4 cells/mm²; P<0.005 for both instances). IL-17A expression was predominantly detected in MC_TC of LA. Significant correlations were found for the slope of phase III % pred. of the sb-N2-test (r_s= -0.39), for the FEV₁% pred. (r_s= 0.37) and for FEV₁/FVC ratio (r_s=0.38) with MC_T in SA (P<0.05 for all instances). 8-isoprostane concentration correlated with the mast cells in the SA (r_s=0.44), there was no correlation for pH or FeNO with cellular distribution in SA.

Conclusions

Neutrophils, macrophages and mast cells are more prominent in the SA indicating that these cells are involved in the development of small airway dysfunction in smokers. Among these cell types, the best correlation was found for mast cells with lung function parameters and inflammatory markers in exhaled breath. Furthermore, the observed predominant expression of IL-17A in mast cells warrants further investigation to elucidate their role in smoking-induced lung injury, despite the lack of correlation with lung function and exhaled breath parameters.

Protective effect of Lepidium sativum seed extract against hydrogen peroxide-induced cytotoxicity and oxidative stress in human liver cells (HepG2)

CONTEXT

Garden cress [Lepidium sativum (Brassicaceae)] has been widely used to treat a number of ailments in traditional medicine. The pharmacological and preventive potential of Lepidium sativum, such as anti-inflammatory, antipyretic, antihypertensive, anti-ashthamatic, anticancer, and anti-oxidant, are well known.

OBJECTIVE

The present investigation was designed to study the protective effects of chloroform extract of Lepidium sativum seed (LSE) against oxidative stress and cytotoxicity induced by hydrogen peroxide (H2O2) in human liver cells (HepG2).

MATERIALS AND METHODS

Cytotoxicity of LSE and H2O2 was identified by (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT), neutral red uptake (NRU) assays, and morphological changes in HepG2. The cells were pre-exposed to biologically safe concentrations (5-25 μg/ml) of LSE for 24 h, and then cytotoxic (0.25 mM) concentration of H2O2 was added. After 24 h of the exposures, cell viability by MTT, NRU assays, and morphological changes in HepG2 were evaluated. Further, protective effects of LSE on reactive oxygen species (ROS) generation, mitochondrial membrane potential (MMP), lipid peroxidation (LPO), and reduced glutathione (GSH) levels induced by H2O2 were studied.

RESULTS

Pre-exposure of LSE significantly attenuated the loss of cell viability up to 48% at 25 µg/ml concentration against H2O2 (LD50 value = 2.5 mM). Results also showed that LSE at 25 µg/ml concentration significantly inhibited the induction of ROS generation (45%) and LPO (56%), and increases the MMP (55%) and GSH levels (46%).

DISCUSSION AND CONCLUSION

The study suggests the cytoprotective effects of LSE against H2O2-induced toxicity in HepG2. The results also demonstrate the anti-oxidative nature of LSE.

Inhibition of adenylyl cyclase type 5 increases longevity and healthful aging through oxidative stress protection

Mice with disruption of adenylyl cyclase type 5 (AC5 knockout, KO) live a third longer than littermates. The mechanism, in part, involves the MEK/ERK pathway, which in turn is related to protection against oxidative stress. The AC5 KO model also protects against diabetes, obesity, and the cardiomyopathy induced by aging, diabetes, and cardiac stress and also demonstrates improved exercise capacity. All of these salutary features are also mediated, in part, by oxidative stress protection. For example, chronic beta adrenergic receptor stimulation induced cardiomyopathy was rescued by AC5 KO. Conversely, in AC5 transgenic (Tg) mice, where AC5 is overexpressed in the heart, the cardiomyopathy was exacerbated and was rescued by enhancing oxidative stress resistance. Thus, the AC5 KO model, which resists oxidative stress, is uniquely designed for clinical translation, since it not only increases longevity and exercise, but also protects against diabetes, obesity, and cardiomyopathy. Importantly, inhibition of AC5's action to prolong longevity and enhance healthful aging, as well as its mechanism through resistance to oxidative stress, is unique among all of the nine AC isoforms.

Genetic mutations potentially cause two novel NCF1 splice variants up-regulated in the mammary gland, blood and neutrophil of cows infected by Escherichia coli

Neutrophil cytosolic factor 1 (NCF1) plays a crucial role in host defense against microbial pathogens. In this study, we investigated the potential alternative splicing patterns, expression and splice-relevant single nucleotide polymorphisms (SNPs) of the bovine NCF1 gene to increase insights into its potential role against bovine mastitis caused by Escherichia coli infection. Using RT-PCR and clone sequencing methods, we found two novel splice variants designed as NCF1-TV1 (retained intron 6) and NCF1-TV2 (retained part of intron 8), respectively, encoding two putative truncated proteins (239AA and 283AA). Two splice variants were drastically up-regulated in the mastitis-infected cows' mammary tissues, blood and neutrophils compared with these of healthy cows using real-time RT-PCR. Genomic sequencing analysis identified four novel SNPs g.10112 G>A, g.10766 T>C, SNPs g.12085 G>A and g.12430 T>C at the ends of intron 6 and intron 8 of NCF1. ESE motif predicted that the SNP (g.10766 T>C) might affect the binding with splicing-related factors and subsequently caused the production of aberrant splice variant NCF1-TV1, which is one of the potential reasons that the functional SNP was associated with increased milk somatic cell score in cow. Our results would help in better understanding the NCF1 gene function in the process against pathogen infection, and the effect of splicing-related SNP on the production of aberrant splice variant and careful functional characterization in dairy cattle.

Lung injury and lung cancer caused by cigarette smoke-induced oxidative stress: Molecular mechanisms and therapeutic opportunities involving the ceramide-generating machinery and epidermal growth factor receptor

Chronic obstructive pulmonary disease (COPD) and lung cancer are frequently caused by tobacco smoking. However, these diseases present opposite phenotypes involving redox signaling at the cellular level. While COPD is characterized by excessive airway epithelial cell death and lung injury, lung cancer is caused by uncontrolled epithelial cell proliferation. Notably, epidemiological studies have demonstrated that lung cancer incidence is significantly higher in patients who have preexisting emphysema/lung injury. However, the molecular link and common cell signaling events underlying lung injury diseases and lung cancer are poorly understood. This review focuses on studies of molecular mechanism(s) underlying smoking-related lung injury (COPD) and lung cancer. Specifically, the role of the ceramide-generating machinery during cigarette smoke-induced oxidative stress leading to both apoptosis and proliferation of lung epithelial cells is emphasized. Over recent years, it has been established that ceramide is a sphingolipid playing a major role in lung epithelia structure/function leading to lung injury in chronic pulmonary diseases. However, new and unexpected findings draw attention to its potential role in lung development, cell proliferation, and tumorigenesis. To address this dichotomy in detail, evidence is presented regarding several protein targets, including Src, p38 mitogen-activated protein kinase, and neutral sphingomyelinase 2, the major sphingomyelinase that controls ceramide generation during oxidative stress. Furthermore, their roles are presented not only in apoptosis and lung injury but also in enhancing cell proliferation, lung cancer development, and resistance to epidermal growth factor receptor-targeted therapy for treating lung cancer.

Senescence-associated secretory phenotype and its possible role in chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is a major disease of the lungs. It primarily occurs after a prolonged period of cigarette smoking. Chronic inflammation of airways and the alveolar space as well as lung tissue destruction are the hallmarks of COPD. Recently it has been shown that cellular senescence might play a role in the pathogenesis of COPD. Cellular senescence comprises signal transduction program, leading to irreversible cell cycle arrest. The growth arrest in senescence can be triggered by many different mechanisms, including DNA damage and its recognition by cellular sensors, leading to the activation of cell cycle checkpoint responses and activation of DNA repair machinery. Senescence can be induced by several genotoxic factors apart from telomere attrition. When senescence induction is based on DNA damage, senescent cells display a unique phenotype, which has been termed "senescence-associated secretory phenotype" (SASP). SASP may be an important driver of chronic inflammation and therefore may be part of a vicious cycle of inflammation, DNA damage, and senescence. This research perspective aims to showcase cellular senescence with relevance to COPD and the striking similarities between the mediators and secretory phenotype in COPD and SASP.

In vitro antioxidant activity of Retama monosperma (L.) Boiss

The relationship between the antioxidant activity and the phenolic contents (total polyphenol, flavonoid and condensed tannin) of Retama monosperma (Fabaceae), used commonly in the traditional medicine of Mediterranean regions, was investigated. The antioxidant activities of the various fractions (toluene, chloroform, ethyl acetate and butanol) of the hydromethanolic extract of the seeds, stems and flowers have been evaluated using in vitro 2,2-diphenyl-1-picrylhydrazyl radical (DPPH) radical scavenging activities and Phosphomolybdic acid assays and were compared to ascorbic acid. A significant high Pearson's correlations between flavonoid content and antioxidant activities (r = 0.91) with Phosphomolybdic acid assays and (r = - 0.79) with IC50 DPPH radical scavenging activities. However, there was no correlation between condensed tannin and antioxidant activities. The results obtained in the present study indicate that the ethyl acetate fraction of seeds is a potential source of natural antioxidant for R. monosperma.

Oxidative stress and lung function profiles of male smokers free from COPD compared to those with COPD: a case-control study

BACKGROUND

The mechanisms of smoking tobacco leading to chronic obstructive pulmonary disease (COPD) are beginning to be understood. However, conclusions about the role of blood or lung oxidative stress markers were disparate.

AIMS

To investigate the oxidative stress in blood or lung associated with tobacco smoke and to evaluate its effect on pulmonary function data and its relation with physical activity.

METHODS

It is a case-control study. Fifty-four male-smokers of more than five pack-years (PY) and aged 40-60 years were included (29 Non-COPD, 16 COPD). Physical activity score was determined. Blood sample levels of malondialdehyde (MDA), protein-cys-SH (PSH), and Glutathione (GSH) were measured. Fractional exhaled nitric oxide (FeNO) and plethysmographic measurements were performed. Correlation coefficients (r) evaluated the association between oxidative stress markers and independent variables (plethysmographic data and physical activity score).

RESULTS

Non-COPD (48 ± 6 years) and COPD (49 ± 5 years) groups had similar tobacco consumption patterns, that is, 27 ± 14 PY versus 30 ± 19 PY, respectively. Compared to the Non-COPD group, the COPD group had significantly lower levels of GSH and PSH, that is, mean ± SE were 40 ± 6 versus 25 ± 5 µg/mL and 54 ± 10 versus 26 ± 5 µg/g of hemoglobin, respectively. However, MDA level and FeNO values were similar. In the COPD group, none of the oxidative stress markers was significantly correlated with plethysmographic data or physical activity score. In the Non-COPD group, GSH was significantly correlated with physical activity score (r = 0.47) and PSH was significantly correlated with total lung capacity (TLC) (r = -0.50), residual volume (r = 0.41), and physical activity score (r = 0.62). FeNO was significantly correlated with TLC of the COPD group (r = -0.48).

CONCLUSION

Compared to the Non-COPD group, the COPD group had a marked decrease in blood antioxidant markers (GSH and PSH) but similar blood oxidant (MDA) or lung (FeNO) burden.

The detox strategy in smoking comprising nutraceutical formulas of non-hydrolyzed carnosine or carcinine used to protect human health

The increased oxidative stress in patients with smoking-associated disease, such as chronic obstructive pulmonary disease, is the result of an increased burden of inhaled oxidants as well as increased amounts of reactive oxygen species generated by various inflammatory, immune and epithelial cells of the airways. Nicotine sustains tobacco addiction, a major cause of disability and premature death. In addition to the neurochemical effects of nicotine, behavioural factors also affect the severity of nicotine withdrawal symptoms. For some people, the feel, smell and sight of a cigarette and the ritual of obtaining, handling, lighting and smoking a cigarette are all associated with the pleasurable effects of smoking. For individuals who are motivated to quit smoking, a combination of pharmacotherapy and behavioural therapy has been shown to be most effective in controlling the symptoms of nicotine withdrawal. In the previous studies, we proposed the viability and versatility of the imidazole-containing dipeptide-based compounds in the nutritional compositions as the telomere protection targeted therapeutic system for smokers in combination with in vitro cellular culture techniques being an investigative tool to study telomere attrition in cells induced by cigarette smoke (CS) and smoke constituents. Our working therapeutic concept is that imidazole-containing dipeptide-based compounds (non-hydrolyzed carnosine and carcinine) can modulate the telomerase activity in the normal cells and can provide the redox regulation of the cellular function under the terms of environmental and oxidative stress and in this way protect the length and the structure of telomeres from attrition. The detoxifying system of non-hydrolyzed carnosine or carcinine can be applied in the therapeutic nutrition formulations or installed in the cigarette filter. Patented specific oral formulations of non-hydrolyzed carnosine and carcinine provide a powerful manipulation tool for targeted therapeutic inhibition of cumulative oxidative stress and inflammation and protection from telomere attrition associated with smoking. It is demonstrated in this work that both non-hydrolyzed carnosine and carcinine are characterized by greater bioavailability than pure l-carnosine subjected to enzymatic hydrolysis with carnosinase, and perform the detoxification of the α,β-unsaturated carbonyl compounds present in tobacco smoke. We argue that while an array of factors has shaped the history of the 'safer' cigarette, it is the current understanding of the industry's past deceptions and continuing avoidance of the moral implications of the sale of products that cause the enormous suffering and death of millions that makes reconsideration of 'safer' cigarettes challenging. In contrast to this, the data presented in the article show that recommended oral forms of non-hydrolyzed carnosine and carcinine protect against CS-induced disease and inflammation, and synergistic agents with the actions of imidazole-containing dipeptide compounds in developed formulations may have therapeutic utility in inflammatory lung diseases where CS plays a role.

Andrographolide antagonizes cigarette smoke extract-induced inflammatory response and oxidative stress in human alveolar epithelial A549 cells through induction of microRNA-218

Andrographolide is a major bioactive labdane diterpenoid isolated from Andrographis paniculata and has protective effects against cigarette smoke (CS)-induced lung injury. This study was done to determine whether such protective effects were mediated through modulation of microRNA (miR)-218 expression. Therefore, we exposed human alveolar epithelial A549 cells to cigarette smoke extract (CSE) with or without andrographolide pretreatment and measured the level of glutathione, nuclear factor-kappaB (NF-κB) activation, proinflammatory cytokine production, and miR-218 expression. We found that andrographolide pretreatment significantly restored the glutathione level in CSE-exposed A549 cells, coupled with reduced inhibitor κB (IκB)-α phosphorylation and p65 nuclear translocation and interleukin (IL)-8 and IL-6 secretion. The miR-218 expression was significantly upregulated by andrographolide pretreatment. To determine the biological role of miR-218, we overexpressed and downregulated its expression using miR-218 mimic and anti-miR-218 inhibitor, respectively. We observed that miR-218 overexpression led to a marked reduction in IκB-α phosphorylation, p65 nuclear accumulation, and NF-κB-dependent transcriptional activity in CSE-treated A549 cells. In contrast, miR-218 silencing enhanced IκB-α phosphorylation and p65 nuclear accumulation in cells with andrographolide pretreatment and reversed andrographolide-mediated reduction of IL-6 and IL-8 production. In addition, depletion of miR-218 significantly reversed the upregulation of glutathione levels in A549 cells by andrographolide. Taken together, our results demonstrate that andrographolide mitigates CSE-induced inflammatory response in A549 cells, largely through inhibition of NF-κB activation via upregulation of miR-218, and thus has preventive benefits in CS-induced inflammatory lung diseases.

Aberrant neutrophil functions in stable chronic obstructive pulmonary disease: the neutrophil as an immunotherapeutic target

Chronic obstructive pulmonary disease (COPD) is a common, progressive and debilitating chronic inflammatory condition affecting the lungs, with significant systemic manifestations and co-morbidities. Smoking cigarettes is the main risk factor, but only a fifth of smokers have clinically significant airflow obstruction and the inflammation persists after smoking cessation. This suggests that smoking (and exposure to other inhaled toxins) may be necessary but not sufficient to cause COPD. Neutrophils are believed central to COPD and their accumulation and degranulation are associated with tissue damage, increased inflammation and disordered tissue repair. It was assumed that neutrophil activity and function were appropriate in COPD, responding to the presence of high levels of inflammation in the lung. However more recent studies of neutrophil function (including migration, reactive oxygen species generation, degranulation, phagocytosis and extracellular trap (NET) production) suggest that there is a general impairment in COPD neutrophil responses that predispose towards increased inflammation and reduced bacterial clearance. This may be amenable to correction and manipulating neutrophil intracellular pathways (such as phosphoinositide-3-kinase signalling) appears to restore some key COPD neutrophil responses. Targeting neutrophil intra-cellular signalling may provide a means to normalise neutrophil behaviour in COPD. This could lead to improvements in disease outcomes by reducing extraneous inflammatory burden. However further studies are needed to determine if these findings are relevant in vivo and whether this would impact positively upon health and disease.

Local and systemic neutrophilic inflammation in patients with lung cancer and chronic obstructive pulmonary disease

Background

Recent investigations suggest that neutrophils play an important role in the immune response to lung cancer as well as chronic obstructive pulmonary disease (COPD). The aim of this study was to evaluate the amount of neutrophils and markers of their activity in lung cancer and COPD and in coexistence of these two diseases.

Methods

In total, 267 persons were included in the study: 139 patients with lung cancer, 55 patients with lung cancer and COPD, 40 patients with COPD, and 33 healthy subjects. Peripheral blood and BAL fluid samples were obtained for cell count analysis and determination of NE, MPO levels and ROS production. NE and MPO levels in the serum and BAL fluid were determined by ELISA. ROS production was analyzed by flow cytometer.

Results

The percentage, cell count of neutrophils and neutrophil to lymphocyte ratio in the peripheral blood were significantly higher in lung cancer patients with or without COPD compared to COPD patients or healthy individuals (P < 0.05). The percentage and cell count of neutrophils in BAL fluid were significantly lower in patients with lung cancer with or without COPD than in patients with COPD (P < 0.05). However, BAL fluid and serum levels of both NE and MPO were significantly higher in patients with lung cancer than COPD patients or healthy individuals (P < 0.05). Neutrophils produced higher amounts of ROS in patients with lung cancer with or without COPD compared with COPD patients or healthy individuals (P < 0.05).

Conclusions

The results from this study demonstrate higher degree of local and systemic neutrophilic inflammation in patients with lung cancer (with or without COPD) than in patients with COPD.

Oxidative stress and chromatin remodeling in chronic obstructive pulmonary disease and smoking-related diseases

SIGNIFICANCE

Chronic obstructive pulmonary disease (COPD) is predominantly a tobacco smoke-triggered disease with features of chronic low-grade systemic inflammation and aging (inflammaging) of the lung associated with steroid resistance induced by cigarette smoke (CS)-mediated oxidative stress. Oxidative stress induces various kinase signaling pathways leading to chromatin modifications (histone acetylation/deacetylation and histone methylation/demethylation) in inflammation, senescence, and steroid resistance.

RECENT ADVANCES

Histone mono-, di-, or tri-methylation at lysine residues result in either gene activation (H3K4, H3K36, and H3K79) or repression (H3K9, H3K27, and H3K20). Cross-talk occurs between various epigenetic marks on histones and DNA methylation. Both CS and oxidants alter histone acetylation/deacetylation and methylation/demethylation leading to enhanced proinflammatory gene expression. Chromatin modifications occur in lungs of patients with COPD. Histone deacetylase 2 (HDAC2) reduction (levels and activity) is associated with steroid resistance in response to oxidative stress.

CRITICAL ISSUES

Histone modifications are associated with DNA damage/repair and epigenomic instability as well as premature lung aging, which have implications in the pathogenesis of COPD. HDAC2/SIRTUIN1 (SIRT1)-dependent chromatin modifications are associated with DNA damage-induced inflammation and senescence in response to CS-mediated oxidative stress.

FUTURE DIRECTIONS

Understanding CS/oxidative stress-mediated chromatin modifications and the cross-talk between histone acetylation and methylation will demonstrate the involvement of epigenetic regulation of chromatin remodeling in inflammaging. This will lead to identification of novel epigenetic-based therapies against COPD and other smoking-related lung diseases. Pharmacological activation of HDAC2/SIRT1 or reversal of their oxidative post-translational modifications may offer therapies for treatment of COPD and CS-related diseases based on epigenetic histone modifications.

Src mediates cigarette smoke-induced resistance to tyrosine kinase inhibitors in NSCLC cells

The EGF receptor (EGFR) is a proto-oncogene commonly dysregulated in several cancers including non-small cell lung carcinoma (NSCLC) and, thus, is targeted for treatment using tyrosine kinase inhibitors (TKI) such as erlotinib. However, despite the efficacy observed in patients with NSCLC harboring oncogenic variants of the EGFR, general ineffectiveness of TKIs in patients with NSCLC who are current and former smokers necessitates identification of novel mechanisms to overcome this phenomenon. Previously, we showed that NSCLC cells harboring either wild-type (WT) EGFR or oncogenic mutant (MT) L858R EGFR become resistant to the effects of TKIs when exposed to cigarette smoke, evidenced by their autophosphorylation and prolonged downstream signaling. Here, we present Src as a target mediating cigarette smoke-induced resistance to TKIs in both WT EGFR- and L858R MT EGFR-expressing NSCLC cells. First, we show that cigarette smoke exposure of A549 cells leads to time-dependent activation of Src, which then abnormally binds to the WT EGFR causing TKI resistance, contrasting previous observations of constitutive binding between inactive Src and TKI-sensitive L858R MT EGFR. Next, we show that Src inhibition restores TKI sensitivity in cigarette smoke-exposed NSCLC cells, preventing EGFR autophosphorylation in the presence of erlotinib. Furthermore, we show that overexpression of a dominant-negative Src (Y527F/K295R) restores TKI sensitivity to A549 exposed to cigarette smoke. Importantly, the TKI resistance that emerges even in cigarette smoke-exposed L858R EGFR-expressing NSCLC cells could be eliminated with Src inhibition. Together, these findings offer new rationale for using Src inhibitors for treating TKI-resistant NSCLC commonly observed in smokers.

Molecular mechanisms of reactive oxygen species-related pulmonary inflammation and asthma

Asthma is a highly relevant disorder that can be induced by many environmental factors such as allergens and pollutants. One of the most critical pathological symptoms of asthma is airway inflammation. In order to identify a cause of respiratory inflammation, we thoroughly examine the unique role of reactive oxygen species (ROS). Evidence supports that the inhalation of aggravating compounds such as allergens can promote the increased generation of ROS. Accordingly, ROS have a proven role in the cellular signaling cascades of many respiratory diseases that cause respiratory inflammation, including asthma. Although there is no known cure for asthma, current treatments effectively lessen the inflammation symptom. Based on the investigations of asthma pathogenesis and the mechanism of ROS formation, we have identified several novel anti-inflammatory therapeutic treatments, shedding light on a fundamental understanding for the cure of this disorder. In this review, we will outline the pathogenesis of asthma and its relationship to ROS, oxidative stress, and pulmonary inflammation.

Moderate hypothermia attenuates oxidative stress injuries in alveolar epithelial A549 cells

Reactive oxygen species (ROS) are generally involved in lung inflammation and acute lung injury. We investigated the effects of hypothermia on ROS-induced cell damage in human alveolar type II cells. A549 cells were exposed to H2O2 and cultured at different temperatures, namely, normthermia (37°C), mild hypothermia (34°C), or moderate hypothermia (32°C). Cell damage was measured using various assays. The biochemical studies demonstrated a significant increase in apoptosis and intracellular ROS at 32°C in uninjured A549 cells. After exposure to H2O2, a marked decrease in cell viability (<50%) was demonstrated, and this was significantly ameliorated upon culture at 32°C. Significantly intracellular damage was found to affect the 24-hour H2O2-exposed cells in 37°C (P < .05), including an increase in apoptosis and necrosis, intracellular ROS, caspase-3 activity, HMGB1 protein expression, and some alterations to the cell cycle. On hypothermic treatment, the 24-hour H2O2-induced caspase-3 activation was significantly suppressed in cells cultured at both 32°C and 34°C (P < .05 versus 37°C). The cell cycle changes in 24-hour H2O2-exposed cells were significantly diminished when the cells were cultured in 32°C (P < .05 versus 37°C). However, these intracellular alterations were not seen in 6-hour H2O2-exposed cells. We concluded that moderate hypothermia (32°C) of alveolar epithelial A549 cells seems to provide protection against H2O2-induced 24-hour oxidative stress by attenuating cell death and intracellular damage. However, moderate hypothermia might cause minor damage to uninjured cells, so the use of hypothermic treatment needs to be judiciously applied.

Systemic inflammatory biomarkers and co-morbidities of chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) can no longer be considered as a disease affecting only the lungs. Increasing evidence supports the presence of a systemic inflammatory component which is thought to provide the link between COPD and the co-morbidities commonly associated with this disease. These include cardiovascular disorders, skeletal muscle dysfunction, diabetes, and osteoporosis. The majority of current therapies for COPD have been developed to improve airway obstruction or to target airway inflammation, leaving an unmet medical need with respect to the systemic inflammatory component of COPD and its extra-pulmonary manifestations. This review describes systemic biomarkers in COPD and their relationship with both the local lung and systemic manifestations of the disease. A summary is provided of the most promising biomarkers that have been investigated in COPD and its co-morbidities. Such biomarkers may be used to assess and manage the systemic effects of COPD, and may guide future development of novel therapeutic interventions to provide a more holistic approach to treating this multi-faceted disease.

Oxidative status in the lungs associated with tobacco smoke exposure

BACKGROUND

Oxidative stress has a critical role in inflammatory responce against tobacco smoke (TS). Testing exhaled breath condensate (EBC) samples is one of the methods used for assessment of airway inflammation caused by TS. We aimed to investigate oxidative stress in the lungs associated with TS and to evaluate the effect of this stress with pulmonary function tests (PFTs).

METHODS

We included 69 subjects as three groups into the study (Group I; 26 smokers, Group II; 21 passive smokers, Group III; 22 non-smokers without TS exposure). Levels of malondialdehyde (MDA), 8-hydroxydeoxyguanosine (8-OHdG), nitrite/nitrate [index of nitric oxide (NO) production], vitamin C, superoxide dismutase (SOD), and glutathione peroxidase (GSH-Px) were measured in EBC samples collected using a condenser and PFTs were performed.

RESULTS

The levels of MDA, 8-OHdG, SOD and GSH-Px were higher in smokers. NO levels gradually increased from Group I to Group III. MDA levels were lower in Group III than Group II. The levels of vitamin C were similar in all groups. We determined negative correlation between 8-OHdG levels and forced expiratory volume in one second (FEV₁), and maximum mean expiratory flow (MMEF), and a positive correlation between SOD levels and FEV₁.

CONCLUSIONS

TS exposure affected the balance between oxidative stress and antioxidant capacity of lungs. Preventing environmental TS exposure might decrease oxidative damage. Increased levels of 8-OHdG and SOD levels could be assessed as an early sign of airway damage.

Subacute effect of cigarette smoke exposure in rats: protection by pot marigold (Calendula officinalis L.) extract

This study was carried out to determine the preventive effect of Calendula officinalis L. (pot marigold) on rats exposed to cigarette smoke (CS). Rats were divided into three groups as control, CS and CS + pot marigold (PM). The rats in the CS and CS + PM groups were subjected to CS for 1 h twice a day for 23 days. PM (100 mg/kg body weight) was given to rats in the CS + PM group by gavage, 1 h before each administration period. While malondialdehyde, protein carbonyl contents and reduced glutathione level of the CS group increased, their levels diminished by PM administration. In addition, glutathione peroxidase (GPx), superoxide dismutase activities and β-carotene, vitamins A and C levels decreased in the CS group compared to control, however activities of these enzymes and concentration of vitamins were elevated by PM supplementation. This investigation showed that administration of PM supplied relative protection against subacute CS-induced cell injury.

Insulin resistance and oxidative stress influence colony-forming unit-endothelial cells capacity in obese patients

The aim of this study was to investigate the relationship between a sub-population of endothelial progenitor cells (EPC), namely colony-forming unit-endothelial cells (CFU-EC), their colony-forming capacity and variable clinical parameters, including insulin resistance and oxidative stress, in obese individuals. Thirty-eight obese adults (aged 42.5 ± 12.7), with BMI 32.3 ± 4.0 and 13 normal-weight controls (aged 48.2 ± 12.9; BMI 23.2 ± 2.3) were studied. CFU-EC colony-forming capacity was impaired in the group of obese individuals compared to the normal-weight controls (P = 0.001). The inverse correlation between homeostasis model assessment-insulin resistance (HOMA(IR)) index and CFU-EC number (r = -0.558, P < 0.0001) as well as positive total antioxidant status of plasma (TAS)/CFU-EC relation were noticed during the study. Additionally, correlations between the concentration of triglycerides (TG), high-density lipoproteins (HDLs), and body composition parameters in the obese participants were established. Our results demonstrate that insulin resistance and oxidative stress have a significant impact on the CFU-EC colony formation in obesity. Moreover, in multivariate regression analysis, in both studied groups, the HOMA(IR) index and HDL concentration were independent predictors of the number of CFU-EC. Endothelium dysfunction, which can be present in obesity, may in part be caused by EPC function impairment in this condition.

Interleukin-6 and airflow limitation in chemical warfare patients with chronic obstructive pulmonary disease

OBJECTIVES

Chronic obstructive pulmonary disease (COPD) is one of the main late complications of sulfur mustard poisoning. The aim of this study was to evaluate serum levels of interleukin (IL)-6 in war veterans with pulmonary complications of sulfur mustard poisoning and their correlation with severity of airways disease.

METHODS

Fifty consecutive patients with sulfur mustard poisoning and stable COPD, and of mean age 46.3 ± 9.18 years were enrolled in this study. Thirty healthy men were selected as controls and matched to cases by age and body mass index. Spirometry, arterial blood gas, six- minute walk test, BODE (body mass index, obstruction, dyspnea, and exercise capacity), and St George's Respiratory Questionnaire about quality of life were evaluated. Serum IL-6 was measured in both patient and control groups.

RESULTS

Fifty-four percent of patients had moderate COPD. Mean serum IL-6 levels were 15.01 ± standard deviation (SD) 0.61 pg/dL and 4.59 ± 3.40 pg/dL in the case and control groups, respectively (P = 0.03). There was a significant correlation between IL-6 levels and Global Initiative for Chronic Obstructive Lung Disease stage (r = 0.25, P = 0.04) and between IL-6 and BODE index (r = 0.38, P = 0.01). There was also a significant negative correlation between serum IL-6 and forced expiratory volume in one second (FEV(1), r = -0.36, P = 0.016).

CONCLUSION

Our findings suggest that serum IL-6 is increased in patients with sulfur mustard poisoning and COPD, and may have a direct association with airflow limitation.

Gene expression profiling of peripheral blood leukocytes identifies potential novel biomarkers of chronic obstructive pulmonary disease in current and former smokers

BACKGROUND

Chronic obstructive pulmonary disease (COPD) is an inflammatory lung disease with associated systemic effects.

OBJECTIVE

To use gene expression microarrays in peripheral blood leukocytes of current and former cigarette smokers to identify differences associated with COPD.

MATERIALS AND METHODS

Random forest modelling and a split-sample case-control approach were used to identify candidate predictors.

RESULTS

We identified 1013 genes and one smoking exposure variable that differentiated current and former smokers with or without COPD. This predictor set was reduced to a nine-gene classifier (IL6R, CCR2, PPP2CB, RASSF2, WTAP, DNTTIP2, GDAP1, LIPE and RPL14).

CONCLUSION

These gene expression profiles represent potential biomarkers for COPD and may help increase mechanistic understanding of the disease.

Malondialdehyde and superoxide dismutase correlate with FEV(1) in patients with COPD associated with wood smoke exposure and tobacco smoking

Tobacco smoking is the primary risk factor for chronic obstructive pulmonary disease (COPD). However, recent epidemiological studies have established domestic exposure to wood smoke and other biomass fuels as additional important risk factors, characteristic in developing countries. Oxidative stress is one of the mechanisms concerned with pathogenesis of COPD. However, the molecular mechanisms involved in the onset and progress of COPD associated with biomass and specifically that derived from wood smoke exposure remain unknown. We analyzed the relationship between forced expiratory volume in first second (FEV(1)) with plasma malondialdehyde (MDA) concentration and activities of superoxide dismutase (SOD), glutathione peroxidase (GPx), glutathione reductase (GR), and glutathione-S-transferase (GST) in COPD patients associated with wood smoke (WSG; n = 30), tobacco smoking (TSG; n = 30), and healthy control subjects (HCG; n = 30). Differences between FEV(1) from WSG and TSG (58 +/- 22% and 51 +/- 24%, respectively) with HCG (100 +/- 6%) were observed (P < 0.01). Plasma MDA concentration was higher in both WSG and TSG (1.87 +/- 0.81 and 1.68 +/- 0.82 nmol/mL, respectively) compared with HCG (0.42 +/- 0.17 nmol/mL; P < 0.01). SOD activity showed a significant increase in both WSG and TSG (0.36 +/- 0.12 and 0.37 +/- 0.13 U/mL) compared with HCG (0.19 +/- 0.04 U/mL; P < 0.01). No differences were shown regarding GPx, GR, and GST activities between COPD and control groups. Inverse correlations were founded between MDA and SOD with FEV(1) in both COPD patients and control subjects (P < 0.001). These results indicate a role for oxidative stress in COPD associated with wood smoke similar to that observed with tobacco smoking in subjects who ceased at least 10 years previous to this study.

The influence of dexamethasone and the role of some antioxidant vitamins in the pathogenesis of experimental bronchial asthma

BACKGROUND

Bronchial asthma is a disease characterized by paroxysmal and reversible obstruction of the airways. The imbalance between the oxidant and antioxidant system that is called oxidative stress is critical in asthma pathogenesis. It is likely, therefore, that antioxidants may be effective in the treatment of asthma. Systemic treatment with glucocorticoids has been reported to inhibit smooth muscle hypercontraction which may account partially for their beneficial effects in the treatment of asthma.

OBJECTIVE

The present study was conducted in order to study the effect of dexamethasone and some antioxidant vitamins on interleukin-4 (IL-4), immunoglobulin E (IgE) and heat shock protein 70 (Hsp70) in bronchial asthma in rats, and to recognize their possible beneficial role.

METHOD

The study was conducted on 60 adult male albino rats randomly divided into 4 groups (15 for each group): including normal control group (group A); asthma model group where rats were sensitized by ovalbumin and challenged with antigen aerosol producing bronchial asthma (group B); asthma model group treated with antioxidant vitamins (vitamin E and vitamin C) (group C); asthma model group treated with dexamethasone (group D). Blood and lung samples were collected from all groups.

RESULTS AND CONCLUSION

Our results revealed a significant decrease of serum reduced glutathione (GSH) levels among groups B, C and D as compared to group A, while there was a significant increase in group C and D as compared to group B. Antioxidant and dexamethasone treatment resulted in a significant decrease of serum IL-4, malondialdehyde (MDA), and serum IgE levels in group C and D as compared to group B. Antioxidant treatment resulted in a significant decrease of serum Hsp70 level as compared to group B, while dexamethasone treatment resulted in a significant increase of serum Hsp70 level as compared to group B. This study suggests that it is likely that a combination of antioxidant vitamins may be effective in the treatment of asthma, considering their reported effects on lowering MDA, IL-4, and IgE levels, and the similar beneficial effects of dexamethasone in addition to increasing the expression of Hsp70 in the studied model of bronchial asthma.

Airway inflammation in cadmium-exposed rats is associated with pulmonary oxidative stress and emphysema

The aim of this study was to test the hypothesis that pulmonary inflammation and emphysema induced by cadmium (Cd) inhalation are associated with pulmonary oxidative stress. Two groups of Sprague Dawley rats were used: one vehicle-exposed group undergoing inhalation of NaCl (0.9%, n = 24) and one Cd-exposed group undergoing inhalation of CdCl(2) (0.1%, n = 24). The animals in the vehicle-and Cd-exposed groups were divided into 4 subgroups (n = 6 per group), which underwent either a single exposure (D2) of 1H or repeated exposures 3 times/week for 1H for a period of 3 weeks (3W), 5 weeks (5W) or 5 weeks followed by 2 weeks without exposure (5W + 2). At sacrifice, the left lung was fixed for histomorphometric analysis (median inter-wall distance, MIWD), whilst bronchoalveolar lavage fluid (BALF) was collected from the right lung. Cytological analysis of BALF was performed and BALF was analysed for oxidant markers 8-iso-PGF(2a), uric acid (UA), reduced (AA) and oxidised ascorbic acid (DHA) and reduced (GSH) and oxidised glutathione (GSSG). Cd-exposure induced a significant increase of BALF macrophages and neutrophils. 8-iso-PGF(2a), UA, GSH and GSSG were significantly increased at D2. At 5W and 5W + 2, AA and GSH were significantly lower in Cd-exposed rats, indicating antioxidant depletion. MIWD significantly increased in all repeatedly Cd-exposed groups, suggesting development of pulmonary emphysema. 8-iso-PGF(2a) and UA were positively correlated with macrophage and neutrophil counts. GSH, GSSG and 8-iso-PGF(2a) were negatively correlated with MIWD, indicating that Cd-induced emphysema could be associated with pulmonary oxidative stress.

Lipid-soluble components in cigarette smoke induce mitochondrial production of reactive oxygen species in lung epithelial cells

Reactive oxygen species (ROS) present in cigarette smoke (CS) are thought to contribute to the development of COPD. Although CS-ROS can hardly enter airway epithelial cells, and certainly not the circulation, systemic levels of ROS have been found to be elevated in COPD patients. We hypothesize that lipophilic components present in CS can enter airway epithelial cells and increase intracellular ROS production by disturbing mitochondrial function. Different airway epithelial cells were exposed to CS extract (CSE), hexane-treated CSE (CSE without lipophilic components), gaseous-phase CS, and water-filtered CS (gaseous-phase CS without ROS). Mitochondrial membrane potential (Deltapsi(m)) and ATP levels were assessed using the bronchial epithelial cell line Beas-2b. ROS generation measured directly by DCF fluorescence and indirectly by measuring free thiol groups (-SH) upon exposure to CS was assessed using lung alveolar epithelial cells devoid of functional mitochondria (A549-rho0), with normal A549 cells serving as controls. In Beas-2b cells, CSE (4 h) caused a dose-dependent decrease in Deltapsi(m) and ATP levels, whereas hexane-treated CSE did not. DCF fluorescence in A549 cells increased in response to CSE, whereas this was not the case in A549-rho0 cells. Exposure of A549 cells to CS resulted in a rapid decrease in free -SH, whereas exposure to ROS-depleted CS only resulted in a delayed decrease. This delayed decrease was less pronounced in A549-rho0 cells. Lipophilic components in CS disturb mitochondrial function, which contributes to increased intracellular generation of ROS. Our results are of importance in understanding the systemic effects of smoking observed in patients with COPD.

Antioxidant therapeutic advances in COPD

Chronic obstructive pulmonary disease (COPD) is associated with a high incidence of morbidity and mortality. Cigarette smoke-induced oxidative stress is intimately associated with the progression and exacerbation of COPD and therefore targeting oxidative stress with antioxidants or boosting the endogenous levels of antioxidants is likely to have beneficial outcome in the treatment of COPD. Among the various antioxidants tried so far, thiol antioxidants and mucolytic agents, such as glutathione, N-acetyl-L-cysteine, N-acystelyn, erdosteine, fudosteine and carbocysteine; Nrf2 activators; and dietary polyphenols (curcumin, resveratrol, and green tea catechins/quercetin) have been reported to increase intracellular thiol status along with induction of GSH biosynthesis. Such an elevation in the thiol status in turn leads to detoxification of free radicals and oxidants as well as inhibition of ongoing inflammatory responses. In addition, specific spin traps, such as alpha-phenyl-N-tert-butyl nitrone, a catalytic antioxidant (ECSOD mimetic), porphyrins (AEOL 10150 and AEOL 10113), and a SOD mimetic M40419 have also been reported to inhibit cigarette smoke-induced inflammatory responses in vivo in the lung. Since a variety of oxidants, free radicals and aldehydes are implicated in the pathogenesis of COPD, it is possible that therapeutic administration of multiple antioxidants and mucolytics will be effective in management of COPD. However, a successful outcome will critically depend upon the choice of antioxidant therapy for a particular clinical phenotype of COPD, whose pathophysiology should be first properly understood. This article will review the various approaches adopted to enhance lung antioxidant levels, antioxidant therapeutic advances and recent past clinical trials of antioxidant compounds in COPD.

Oxidative damage to nucleic acids in severe emphysema

BACKGROUND

Oxidative stress is a key element in the pathogenesis of emphysema, but oxidation of nucleic acids has been largely overlooked. The aim of this study was to investigate oxidative damage to nucleic acids in severe emphysematous lungs.

METHODS

Thirteen human severe emphysematous lungs, including five with alpha(1)-antitrypsin deficiency (AATD), were obtained from patients receiving lung transplantation. Control lung tissue was obtained from non-COPD lungs (n = 8) and donor lungs (n = 8). DNA and RNA oxidation were investigated by immunochemistry. Morphometry (mean linear intercept [Lm] and CT scan) and immunostaining for CD68 and neutrophil elastase also were performed.

RESULTS

Nucleic acid oxidation was increased in alveolar wall cells in emphysematous lungs compared to non-COPD and donor lungs (p < 0.01). In emphysematous lungs, oxidative damage to nucleic acids in alveolar wall cells was increased in the more severe emphysematous areas assessed by histology (Lm, > 0.5 mm; p < 0.05) and CT scan (< -950 Hounsfield units; p < 0.05). Compared to classic emphysema, AATD lungs exhibited higher levels of nucleic acid oxidation in macrophages (p < 0.05) and airway epithelial cells (p < 0.01). Pretreatments with DNase and RNase demonstrated that RNA oxidation was more prevalent than DNA oxidation in alveolar wall cells.

CONCLUSIONS

We demonstrated for the first time that nucleic acids, especially RNA, are oxidized in human emphysematous lungs. The correlation between the levels of oxidative damage to nucleic acids in alveolar wall cells and the severity of emphysema suggest a potential role in the pathogenesis of emphysema.