Evidence of oxidative stress in asthma and COPD: potential inhibitory effect of theophylline

Phytochemical Elucidation and Effect of Maesa indica (Roxb.) Sweet on Alleviation of Potassium Dichromate-Induced Pulmonary Damage in Rats

Maesa indica (Roxb.) Sweet is one of the well-known traditionally-used Indian plants. This plant is rich in secondary metabolites like phenolic acids, flavonoids, alkaloids, glycosides, saponins, and carbohydrates. It contains numerous therapeutically active compounds like palmitic acid, chrysophanol, glyceryl palmitate, stigmasterol, β-sitosterol, dodecane, maesaquinone, quercetin 3-rhaminoside, rutin, chlorogenic acid, catechin, quercetin, nitrendipine, 2,3-dihydroxypropyl octadeca-9,12-dienoate, kiritiquinon, and β-thujone. The Maesa indica plant has been reported to have many biological properties including antidiabetic, anticancer, anti-angiogenic, anti-leishmanial, antioxidant, radical scavenging, antibacterial, antiviral, and anti-coronavirus effects. One purpose of the current study was to investigate the leaves' metabolome via Triple-Time-of-Flight-Liquid-Chromatography-Mass Spectrometry (T-TOF LC/MS/MS) to identify the chemical constituents of the Maesa indica ethanolic extract (ME). Another purpose of this study was to explore the protective effect of ME against potassium dichromate (PD)-induced pulmonary damage in rats. Rats were assigned randomly into four experimental groups. Two different doses of the plant extract, (25 and 50 mg/kg), were administered orally for seven consecutive days before PD instillation injection. Results of our study revealed that ME enhanced cellular redox status as it decreased lipid peroxidation marker, MDA and elevated reduced glutathione (GSH). In addition, ME upregulated the cytoprotective signaling pathway PI3K/AKT. Moreover, ME administration ameliorated histopathological anomalies induced by PD. Several identified metabolites, such as chlorogenic acid, quercetin, apigenin, kaempferol, luteolin, and rutin, had previously indicated lung-protective effects, possibly through an antioxidant effect and inhibition of oxidative stress and inflammatory mediators. In conclusion, our results indicated that ME possesses lung-protective effects, which may be the result of its antioxidant and anti-inflammatory properties.

Theophylline for the management of respiratory disorders in adults in the 21st century: A scoping review from the American College of Clinical Pharmacy Pulmonary Practice and Research Network

Theophylline is an oral methylxanthine bronchodilator recommended as alternate therapy for the treatment of asthma and chronic obstructive pulmonary disease (COPD). However, it is not generally recommended for the treatment of other respiratory disorders such as obstructive sleep apnea (OSA) or hypoxia. Most clinical practice guidelines rely on evidence published prior to the year 2000 to make these recommendations. This scoping review aimed to gather and characterize evidence describing theophylline for the management of respiratory disorders in adults between January 1, 2000 and December 31, 2020. Databases searched included Ovid MEDLINE, Embase, CINAHL Complete, Scopus, and International Pharmaceutical Abstracts. This review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) extension for scoping reviews. Studies were included if they were published in English, theophylline was used for any respiratory disorder, and the study outcomes were disease- or patient-oriented. After removal of duplicates, 841 studies were screened and 55 studies were included. Results aligned with current clinical guideline recommendations relegating theophylline as an alternative therapy for the treatment of respiratory disorders, in favor of inhaled corticosteroids and inhaled bronchodilators. This scoping review identified the need for future research including: theophylline versus other medications deemed alternative therapies for asthma and COPD, meta-analyses of low-dose theophylline, and studies evaluating evidence-based patient-oriented outcomes for OSA, hypoxia, ventilator-induced diaphragmatic dysfunction, and spinal cord injury-related pulmonary function.

Therapeutic Potential of Small Molecules Targeting Oxidative Stress in the Treatment of Chronic Obstructive Pulmonary Disease (COPD): A Comprehensive Review

Chronic obstructive pulmonary disease (COPD) is an increasing and major global health problem. COPD is also the third leading cause of death worldwide. Oxidative stress (OS) takes place when various reactive species and free radicals swamp the availability of antioxidants. Reactive nitrogen species, reactive oxygen species (ROS), and their counterpart antioxidants are important for host defense and physiological signaling pathways, and the development and progression of inflammation. During the disturbance of their normal steady states, imbalances between antioxidants and oxidants might induce pathological mechanisms that can further result in many non-respiratory and respiratory diseases including COPD. ROS might be either endogenously produced in response to various infectious pathogens including fungi, viruses, or bacteria, or exogenously generated from several inhaled particulate or gaseous agents including some occupational dust, cigarette smoke (CS), and air pollutants. Therefore, targeting systemic and local OS with therapeutic agents such as small molecules that can increase endogenous antioxidants or regulate the redox/antioxidants system can be an effective approach in treating COPD. Various thiol-based antioxidants including fudosteine, erdosteine, carbocysteine, and N-acetyl-L-cysteine have the capacity to increase thiol content in the lungs. Many synthetic molecules including inhibitors/blockers of protein carbonylation and lipid peroxidation, catalytic antioxidants including superoxide dismutase mimetics, and spin trapping agents can effectively modulate CS-induced OS and its resulting cellular alterations. Several clinical and pre-clinical studies have demonstrated that these antioxidants have the capacity to decrease OS and affect the expressions of several pro-inflammatory genes and genes that are involved with redox and glutathione biosynthesis. In this article, we have summarized the role of OS in COPD pathogenesis. Furthermore, we have particularly focused on the therapeutic potential of numerous chemicals, particularly antioxidants in the treatment of COPD.

Synthesis and in vitro evaluation of anti-inflammatory, antioxidant, and anti-fibrotic effects of new 8-aminopurine-2,6-dione-based phosphodiesterase inhibitors as promising anti-asthmatic agents

Phosphodiesterase (PDE) inhibitors are currently an extensively studied group of compounds that can bring many benefits in the treatment of various inflammatory and fibrotic diseases, including asthma. Herein, we describe a series of novel N'-phenyl- or N'-benzylbutanamide and N'-arylidenebutanehydrazide derivatives of 8-aminopurine-2,6-dione (27-43) and characterized them as prominent pan-PDE inhibitors. Most of the compounds exhibited antioxidant and anti-inflammatory activity in lipopolysaccharide (LPS)-induced murine macrophages RAW264.7. The most active compounds (32-35 and 38) were evaluated in human bronchial epithelial cells (HBECs) derived from asthmatics. To better map the bronchial microenvironment in asthma, HBECs after exposure to selected 8-aminopurine-2,6-dione derivatives were incubated in the presence of two proinflammatory and/or profibrotic factors: transforming growth factor type β (TGF-β) and interleukin 13 (IL-13). Compounds 32-35 and 38 significantly reduced both IL-13- and TGF-β-induced expression of proinflammatory and profibrotic mediators, respectively. Detailed analysis of their inhibition preferences for selected PDEs showed high affinity for isoenzymes important in the pathogenesis of asthma, including PDE1, PDE3, PDE4, PDE7, and PDE8. The presented data confirm that structural modifications within the 7 and 8 positions of the purine-2,6-dione core result in obtaining preferable pan-PDE inhibitors which in turn exert an excellent anti-inflammatory and anti-fibrotic effect in the bronchial epithelial cells derived from asthmatic patients. This dual-acting pan-PDE inhibitors constitute interesting and promising lead structures for further anti-asthmatic agent discovery.

Reactive Oxygen Species and Antioxidative Defense in Chronic Obstructive Pulmonary Disease

The respiratory system is continuously exposed to endogenous and exogenous oxidants. Chronic obstructive pulmonary disease (COPD) is characterized by chronic inflammation of the airways, leading to the destruction of lung parenchyma (emphysema) and declining pulmonary function. It is increasingly obvious that reactive oxygen species (ROS) and reactive nitrogen species (RNS) contribute to the progression and amplification of the inflammatory responses related to this disease. First, we described the association between cigarette smoking, the most representative exogenous oxidant, and COPD and then presented the multiple pathophysiological aspects of ROS and antioxidative defense systems in the development and progression of COPD. Second, the relationship between nitric oxide system (endothelial) dysfunction and oxidative stress has been discussed. Third, we have provided data on the use of these biomarkers in the pathogenetic mechanisms involved in COPD and its progression and presented an overview of oxidative stress biomarkers having clinical applications in respiratory medicine, including those in exhaled breath, as per recent observations. Finally, we explained the findings of recent clinical and experimental studies evaluating the efficacy of antioxidative interventions for COPD. Future breakthroughs in antioxidative therapy may provide a promising therapeutic strategy for the prevention and treatment of COPD.

Reliability and Usefulness of Different Biomarkers of Oxidative Stress in Chronic Obstructive Pulmonary Disease

Introduction

Chronic obstructive pulmonary disease (COPD) is a progressive disease characterized by airflow limitation that is not fully reversible after inhaled bronchodilator use associated with an abnormal inflammatory condition. The biggest risk factor for COPD is cigarette smoking. The exposure to noxious chemicals contained within tobacco smoke is known to cause airway epithelial injury through oxidative stress, which in turn has the ability to elicit an inflammatory response. In fact, the disruption of the delicate balance between oxidant and antioxidant defenses leads to an oxidative burden that has long been held responsible to play a pivotal role in the pathogenesis of COPD. There are currently several biomarkers of oxidative stress in COPD that have been evaluated in a variety of biological samples. The aim of this review is to identify the best studied molecules by summarizing the key literature findings, thus shedding some light on the subject.

Methods

We searched for relevant case-control studies examining oxidative stress biomarkers in stable COPD, taking into account the analytical method of detection as an influence factor.

Results

Many oxidative stress biomarkers have been evaluated in several biological matrices, mostly in the blood. Some of them consistently differ between the cases and controls even when allowing different analytical methods of detection.

Conclusions

The present review provides an overview of the oxidative stress biomarkers that have been evaluated in patients with COPD, bringing focus on those molecules whose reliability has been confirmed by the use of different analytical methods.

Vitamin D, C-reactive protein, and oxidative stress markers in chronic obstructive pulmonary disease

Objective:

Chronic obstructive pulmonary disease (COPD) is a leading cause of morbidity and mortality worldwide. Systemic inflammation and oxidant/antioxidant imbalance has been seen to play a key role in pathogenesis of COPD. The present study investigated the levels of inflammatory and antioxidant/oxidative stress biomarker in COPD patients and healthy subjects.

Materials and Methods:

The present study enrolled seventy COPD patients and seventy healthy controls from Department of Respiratory Medicine at a tertiary care hospital. Vitamin D, C-reactive protein (CRP), superoxide dismutase (SOD), catalase, and malondialdehyde (MDA) levels were measured in both cases and control. GraphPad PRISM version 6.01 was used for analysis of data.

Results:

The levels of Vitamin D, SOD, Catalase, were found to be significantly lower among the COPD patients in comparison to healthy controls while levels of MDA and CRP were significantly higher (P = 0.0001).

Conclusion:

The results showed oxidant/antioxidant imbalance and Vitamin D deficiency in COPD patients. Higher levels of CRP and oxidative stress markers were observed in COPD patients in comparison to healthy controls. A biomarker based study testing the efficacy of novel antioxidant or other agents will be helpful that can modify the course of this disease.

Effects of Tiotropium Combined with Theophylline on Stable COPD Patients of Group B, D and its Impact on Small Airway Function: A Randomized Controlled Trial

INTRODUCTION

Tiotropium bromide has been widely used in clinical practice, while theophylline is another treatment option for chronic obstructive pulmonary disease (COPD). However, only a few relevant studies have investigated the long-term outcomes and efficacy of both in patients with COPD. We evaluated the effects of tiotropium and low-dose theophylline on stable COPD patients of groups B and D.

METHODS

Eligible participants (n = 170) were randomized and received either tiotropium 18 µg once daily with theophylline 100 mg twice daily (Group I) or tiotropium 18 µg once daily (Group II) for 6 months. COPD assessment test (CAT), modified Medical Research Council (mMRC) dyspnea scores and pulmonary function tests were measured before randomization and during the treatment.

RESULTS

After 6 months of treatment, the CAT scores in both groups decreased significantly (11.41 ± 3.56 and 11.08 ± 3.05, p < 0.0001). The changes of CAT (p = 0.028) and mMRC scores (p = 0.049) between the two groups differed after 1 month of treatment. In Group I, forced expiratory flow after 25% of the FVC% predicted (MEF₂₅% pred) was significantly improved after 3 months (4.84 ± 8.73%, p < 0.0001) and 6 months (6.21 ± 8.65%, p < 0.0001). There was a significant difference in small airway function tests (MEF₅₀% pred, MEF₂₅% pred, and MMEF% pred) between the two groups after 6 month of treatment (p = 0.003, p < 0.0001, and p = 0.021, respectively).

CONCLUSIONS

Tiotropium combined with low-dose theophylline significantly improved the symptoms and general health of patients with stable COPD of groups B and D after 6 months of follow-up. Additionally, this therapy also improved the indicators of small airway function.

TRIAL REGISTRATION

Chinese Clinical Trial Registry (Registry ID: ChiCTR1800019027).

Circulating malondialdehyde concentrations in patients with stable chronic obstructive pulmonary disease: a systematic review and meta-analysis

The aim of this meta-analysis was to review the available evidence regarding the blood concentrations of the oxidative stress marker malondialdehyde (MDA) in chronic obstructive pulmonary disease (COPD) patients in comparison to healthy individuals. 14 studies were included in the meta-analysis (from inception to October 2017) with a total of 817 COPD patients and 530 healthy controls. Pooled MDA concentrations were significantly higher in patients with COPD than controls (standardized mean differences = 2.39 μmol/l, 95% CI: 1.50-3.28 μmol/l; p < 0.001). Our meta-analysis showed that the blood concentrations of MDA are consistently higher in patients with COPD when compared with healthy controls, suggesting an important role of lipid peroxidation, and thus oxidative stress, in the pathogenesis of COPD.

Evaluation of Oxidative Stress and Antioxidant Status in Chronic Obstructive Pulmonary Disease

Chronic obstructive pulmonary disease (COPD) is a common respiratory condition involving the airways and characterized by airflow limitation. Gaseous and noxious particles play an important role in this process. Antioxidants are the substances that may protect cells from the damage caused by unstable molecules known as free radicals. The increased oxidative stress in patients with COPD is the result of an increased burden of inhaled oxidants, as well as increased amounts of reactive oxygen species (ROS) generated by various inflammatory, immune and epithelial cells of the airways. A total of 150 subjects with COPD and 100 healthy controls subjects were enrolled in this study from the period October 2015 to January 2016. The investigation included measurements of plasma superoxide dismutase activity (SOD), catalase activity (CAT), glutathione content (GSH) reduced form, (GPx) glutathione peroxidase, glutathione reductase (GR) and lipid peroxidation (LPO). Absorbance was measured by UV spectrophotometer. The estimated values of SOD, catalase, GPx, GSH and GR were found to be significantly (P = 0.0001) lower among the cases compared with controls. But, the levels of MDA were higher (P = 0.0001) in cases as compared to control group and there was significant difference in the oxidative stress parameters among the various stages of COPD. The post hoc analysis revealed that SOD was significantly (P < 0.01) lower among the mild, moderate and severe patients compared with very severe patients. The catalase was also observed to be significantly (P = 0.01) lower among mild, moderate and severe patients than very severe patients. The GPx was found to be significantly (P = 0.002) lower among the mild, moderate and severe patients compared with very severe patients. MDA was observed to be significantly higher in mild, moderate and severe patients compared with very severe (P = 0.001). GR was significantly (P = 0.003) lower among mild, moderate and severe patients than very severe patients. However, there was no significant difference in GSH among severity of COPD patients. This study suggests that oxidant and antioxidant imbalance plays an important role in various stages of severity of COPD. These results revealed the presence of an oxidative stress in subjects with COPD, and it is proportionate to the severity of disease.

Study of oxidative stress biomarkers in chronic obstructive pulmonary disease and their correlation with disease severity in north Indian population cohort

Background:

Oxidant-antioxidant imbalance forms a prime component in pathogenesis of chronic obstructive pulmonary disease (COPD). Studies of oxidative stress markers in South Asians were sparse.

Methods:

One hundred and eighty COPD patients and eighty healthy nonsmokers were enrolled in the study. Serum malondialdehyde (MDA) and iron levels were estimated for oxidative stress. Three antioxidant markers evaluated-catalase, superoxide dismutase (SOD), and serum copper. Patients on antioxidant therapy and with sepsis and chronic illness were excluded from the study.

Results:

The mean age of COPD patients was 59.29 ± 10.3 years. Serum levels of MDA and iron were significantly higher in COPD patients compared to controls (5.21 ± 1.9 vs. 0.71 ± 0.29 nmol MDA/ml, P = 0.0001 and 69.85 ± 85.49 vs. 79.32 ± 24.39 μg/dl, P = 0.0001, respectively). Mean level of all antioxidant enzymes catalase, SOD, and copper were significantly diminished in cases when compared to control population (P = 0.001). Levels of MDA and iron were found to be significantly elevated in higher Global Initiative for Chronic Obstructive Lung Disease (GOLD) classes (III, IV) when compared to lower GOLD Classes (I, II). The levels of serum antioxidants were significantly depleted in higher GOLD grades too. COPD patients who were male and smoked had significantly higher levels of oxidants and depleted antioxidant levels compared to female and nonsmoking compatriots. Serum MDA levels negatively correlated with forced expiratory volume 1 s and forced vital capacity (r = −0.19 and r = −0.21, P ≤ 0.01). The presence of a cough significantly correlated with higher levels of MDA and iron (P = 0.001). The levels of MDA negatively correlated with SOD and catalase levels.

Conclusion:

Oxidative markers (MDA and iron) are higher whereas antioxidants (catalase, copper, and SOD) are significantly reduced in patients of COPD. Serum MDA levels correlate with lung functions and disease severity.

Circulating biomarkers of oxidative stress in chronic obstructive pulmonary disease: a systematic review

Chronic obstructive pulmonary disease (COPD) is a progressive condition characterized by airflow limitation associated with an abnormal inflammatory response of the lungs to noxious particles and gases, caused primarily by cigarette smoking. Increased oxidative burden plays an important role in the pathogenesis of COPD. There is a delicate balance between the toxicity of oxidants and the protective function of the intracellular and extracellular antioxidant defense systems, which is critically important for the maintenance of normal pulmonary functions. Several biomarkers of oxidative stress are available and have been evaluated in COPD. In this review, we summarize the main literature findings about circulating oxidative stress biomarkers, grouped according to their method of detection, measured in COPD subjects.

The Ethanol Extract of Osmanthus fragrans Flowers Reduces Oxidative Stress and Allergic Airway Inflammation in an Animal Model

The Osmanthus fragrans flower, a popular herb in Eastern countries, contains several antioxidant compounds. Ben Cao Gang Mu, traditional Chinese medical literature, describes the usefulness of these flowers for phlegm and stasis reduction, arrest of dysentery with blood in the bowel, and stomachache and diarrhea treatment. However, modern evidence regarding the therapeutic efficacy of these flowers is limited. This study was aimed at assessing the antioxidative effects of the ethanol extract of O. fragrans flowers (OFE) in vivo and evaluating its antioxidant maintenance and therapeutic effect on an allergic airway inflammation in mice. After OFE's oral administration to mice, the values obtained in the oxygen radical absorbance capacity assay as well as the glutathione concentration in the lungs and spleens of mice increased while thiobarbituric acid reactive substances decreased significantly, indicating OFE's significant in vivo antioxidant activity. OFE was also therapeutically efficacious in a mouse model of ovalbumin-induced allergic airway inflammation. Orally administered OFE suppressed ovalbumin-specific IgE production and inflammatory cell infiltration in the lung. Moreover, the antioxidative state of the mice improved. Thus, our findings confirm the ability of the O. fragrans flowers to reduce phlegm and suggest that OFE may be useful as an antiallergic agent.

Acute effects of walking environment and GSTM1 variants in children with asthma

BACKGROUND

Exercise in air polluted by traffic emissions may aggravate airway inflammation in children with asthma, particularly those who produce decreased glutathione-S transferase (GST) as a result of GSTM1 gene deletion.

OBJECTIVES

This pilot crossover study investigated whether children with asthma experience more airway changes when exercising outdoors near roadways than when exercising indoors. It also examined differences in risk between children with and without GSTM1 deletion.

METHOD

Children between the ages of 5 and 12 years were assigned to groups and walked daily for 1 week in each exercise condition. Airway inflammation indicated by exhaled nitric oxide (eNO) and pulmonary functions measured as forced expiratory volume in 1 s (FEV1) and mid-expiratory flow rate were measured at baseline and at three intervals during the walking program. Independent variables of interest included walking condition (place), time of walking, genotype, and particulate matter (PM) exposure.

RESULTS

A linear mixed models approach was used to investigate the contributions of targeted variables to respiratory outcomes. Results indicated that walking location and ambient level of ultrafine particulates during walking influenced function of small airways. Absence of one or both alleles for the GSTM1 gene did not influence airway function acutely.

DISCUSSION

Mid-expiratory flow (FEF(25-75)) may be more informative than FEV1 in studies of acute lung function changes in children with asthma. Further study of the effects of varied environmental conditions on lower airway function of children is needed to optimize exercise experiences for urban children with asthma.

Exosomes communicate protective messages during oxidative stress; possible role of exosomal shuttle RNA

BACKGROUND

Exosomes are small extracellular nanovesicles of endocytic origin that mediate different signals between cells, by surface interactions and by shuttling functional RNA from one cell to another. Exosomes are released by many cells including mast cells, dendritic cells, macrophages, epithelial cells and tumour cells. Exosomes differ compared to their donor cells, not only in size, but also in their RNA, protein and lipid composition.

METHODOLOGY/PRINCIPAL FINDINGS

In this study, we show that exosomes, released by mouse mast cells exposed to oxidative stress, differ in their mRNA content. Also, we show that these exosomes can influence the response of other cells to oxidative stress by providing recipient cells with a resistance against oxidative stress, observed as an attenuated loss of cell viability. Furthermore, Affymetrix microarray analysis revealed that the exosomal mRNA content not only differs between exosomes and donor cells, but also between exosomes derived from cells grown under different conditions; oxidative stress and normal conditions. Finally, we also show that exposure to UV-light affects the biological functions associated with exosomes released under oxidative stress.

CONCLUSIONS/SIGNIFICANCE

These results argue that the exosomal shuttle of RNA is involved in cell-to-cell communication, by influencing the response of recipient cells to an external stress stimulus.

Effects of supportive treatment such as antioxidant or leukotriene receptor antagonist drugs on inflammatory and respiratory parameters in asthma patients

In this study, prospectively, we aimed to determine the effects of the different treatment alternatives on the oxidant system and inflammatory and clinic determinants during the stable period of 1 month following an asthmatic attack. Thirty-one patients (22 female, nine male) were randomly divided into three groups following the stabilization of an acute asthma attack. The control group that is an additional group to the three patient groups consisted of 10 healthy volunteers (five female, five male). The following protocols were used for 4 weeks: Group I: short-acting inhaler beta2 mimetic as required (treatment A)+800 mug inhaler budesonide (treatment B)+leukotriene receptor antagonist; Group II: treatment A and B; Group III: treatment A and B+vitamin E. The serum levels before and after treatment of eosinophilic cationic protein (ECP), leukotriene E4 (LTE(4)), and malondialdehyde (MDA) were determined. The values before and after treatment were statistically compared both with each other and control values. Pretreatment ECP, LTE(4), and MDA levels for the three groups were significantly higher compared with post-treatment levels (P<0.05 to P<0.001) and the control levels (P<0.01 to P<0.001). However, when post-treatment levels were compared with those of the control group, no significant differences were found (P>0.05). Lack of significant variation was observed when the pre- and post-treatment differences in the three groups were compared for each one of ECP, LTE(4), and MDA levels (P>0.05). Leukotriene receptor antagonist or antioxidant agents added to standard asthma treatment did not make a significant contribution on ECP, LTE(4), and MDA levels and respiratory parameters such as spirometric function tests. Etiologic factors and/or the possible changes in different pathogenetic ways of the inflammation process may have been responsible for nonsignificant intertreatment difference in the biomarker levels. The result confirms that suppressing the inflammation in asthma enables the entire inflammatory pathologic process to be controlled.

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

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

Non-invasive biomarkers of oxidative stress: reproducibility and methodological issues

Oxidative stress is the hallmark of various chronic inflammatory lung diseases. Increased concentrations of reactive oxygen species (ROS) in the lungs of such patients are reflected by elevated concentrations of oxidative stress markers in the breath, airways, lung tissue and blood. Traditionally, the measurement of these biomarkers has involved invasive procedures to procure the samples or to examine the affected compartments, to the patient's discomfort. As a consequence, there is a need for less or non-invasive approaches to measure oxidative stress. The collection of exhaled breath condensate (EBC) has recently emerged as a non-invasive sampling method for real-time analysis and evaluation of oxidative stress biomarkers in the lower respiratory tract airways. The biomarkers of oxidative stress such as H2O2, F2-isoprostanes, malondialdehyde, 4-hydroxy-2-nonenal, antioxidants, glutathione and nitrosative stress such as nitrate/nitrite and nitrosated species have been successfully measured in EBC. The reproducibility, sensitivity and specificity of the methodologies used in the measurements of EBC oxidative stress biomarkers are discussed. Oxidative stress biomarkers also have been measured for various antioxidants in disease prognosis. EBC is currently used as a research and diagnostic tool in free radical research, yielding information on redox disturbance and the degree and type of inflammation in the lung. It is expected that EBC can be exploited to detect specific levels of biomarkers and monitor disease severity in response to appropriate prescribed therapy/treatment.

Asthma and COPD: differences and similarities. With special reference to the usefulness of budesonide/formoterol in a single inhaler (Symbicort) in both diseases

Asthma and chronic obstructive pulmonary disease (COPD) both have a high prevalence worldwide and yet each condition remains underdiagnosed. Despite a number of common features, these inflammatory respiratory syndromes have distinct clinical outcomes. COPD represents a greater economic burden than asthma because it has a less favourable prognosis and is associated with greater morbidity and mortality. Therefore, it is important to distinguish between these two diseases at an early stage, so that appropriate therapy can be prescribed to prevent deterioration. However, effective treatments that may be used in both conditions can minimise the effects of misdiagnosis and maximise the impact of treatment without the associated complexity when both conditions occur together. The current review summarises the differences and similarities of asthma and COPD, in terms of risk factors, pathophysiology, symptoms and diagnosis, to provide greater understanding of the role of budesonide/formoterol in a single inhaler in both diseases.

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

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

Biomarkers in breath condensate: a promising new non-invasive technique in free radical research

Oxidative stress is associated with a range of inflammatory lung diseases including asthma, adult respiratory distress syndrome, idiopathic pulmonary fibrosis, pneumonia, lung transplantation, chronic obstructive pulmonary disease, cystic fibrosis, bronchiectasis and lung cancer. Increased concentrations of reactive oxygen species (ROS) in the airways of such patients are reflected by elevated concentrations of oxidative stress markers in the breath, airways, lung tissue and blood. Traditionally, the measurement of these biomarkers has involved invasive procedures to procure the samples, or examine the compartments. As a consequence, there is a need for less invasive approaches to measure oxidative stress. Analysis of breath hydrocarbons has partly fulfilled this need, however only gas phase volatile constituents can be assessed by this approach. The collection of exhaled breath condensate (EBC) is a simple, non-invasive approach, which comprehensively samples the lower respiratory tract. It is currently used as a research and diagnostic tool in the free radical field, yielding information on redox disturbance and the degree and type of inflammation in the lung. With further technical developments, such an approach may ultimately have a role in the clinic, in helping to diagnose specific lung diseases. EBC can be exploited to assess a spectrum of potential biomarkers, thus generating a "finger print" characteristic of the disease. By assessing the nature of oxidative stress in this manner, the most appropriate therapy can be selected and the response to treatment monitored.

4-Hydroxy-2-nonenal enhances fibronectin production by IMR-90 human lung fibroblasts partly via activation of epidermal growth factor receptor-linked extracellular signal-regulated kinase p44/42 pathway

To elucidate the underlying mechanisms in oxidative stress-related airway remodeling observed in chronic inflammatory pulmonary diseases such as asthma, we studied the effects of a thiol antioxidant, N-acetylcysteine (NAC), a selective epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor, AG-1478, and tyrphostin-1 as a negative control for AG-1478 on an aldehydic product of lipid peroxidation 4-hydroxy-2-nonenal (HNE)-induced secretion of fibronectin by IMR-90 human lung fibroblasts. We also studied signal transduction pathways involved in the secretion of fibronectin evident after exposure of IMR-90 cells to HNE. Twenty-five-micromole HNE treatments of IMR-90 cells activated extracellular signal-regulated kinase p44/42 (Erk1/2) with little activation of p38 mitogen-activated protein kinase (p38MAPK) and no activation of c-Jun NH(2)-terminal kinase. HNE-induced secretion of fibronectin was inhibited by U-0126, an inhibitor of the Erk1/2 pathway, while no significant inhibition by SB-203580, an inhibitor of p38MAPK pathway, was observed. NAC and AG-1478, but not tyrphostin-1, inhibited HNE-induced fibronectin secretion accompanied by a pallarel inhibition of Erk1/2 activation. These data suggest that pulmonary oxidative stress-related lipid peroxidation may play an important role in developing airway remodeling through activating lung fibroblasts to further produce extracellular matrices, such as fibronectin, partly via activation of an EGFR-linked Erk1/2 signal transduction pathway, and that the antioxidant NAC and the EGFR tyrosine kinase inhibitor AG-1478 can be potentially useful in pulmonary diseases involving airway remodeling.

Inhibition of airway inflammation and hyperreactivity by an antioxidant mimetic

A catalytic antioxidant, AEOL 10113, was used in a murine model of asthma to test the hypothesis that oxidants contribute to the pathogenesis of asthma. Balb/c mice were immunized and challenged with ovalbumin. AEOL 10113 was administered to the mice by intratracheal instillation during ovalbumin challenges. Enhanced pause as an indicator of airway reactivity and differential cell count of lavage cells as an indicator of airway inflammation were assessed. Lung expressions of the adhesion molecules VCAM-1 and ICAM-1 were measured. We found that treatment of ovalbumin-challenged mice with AEOL 10113 drastically reduced the severity of airway inflammation as evidenced by the reduced numbers of eosinophils, neutrophils, and lymphocytes found in bronchoalveolar lavage fluid. Inhibition of ovalbumin-induced airway inflammation is associated with inhibited expression of VCAM-1, which is a key adhesion molecule responsible for the recruitment of inflammatory cells into the lungs of ovalbumin-challenged mice. In addition, treatment with AEOL 10113 reduced the magnitude of ovalbumin-induced airway hyperreactivity to methacholine. These results suggest that oxidative stress is an important factor in the pathogenesis of asthma and that a synthetic catalytic antioxidant could be effective in the treatment of asthma.

Theophylline inhibits NF-kappaB activation in human peripheral blood mononuclear cells

BACKGROUND

Theophylline not only dilates the bronchi, but also modulates the production of proinflammatory cytokines and inhibits inflammation. Theophylline exerts an antiinflammatory effect on allergic inflammation through inhibition of NF-kappaB activation in mast cells. However, the action of theophylline on monocytes/macrophages and T cells is unknown.

METHODS

We examined whether or not theophylline inhibits tumor necrosis factor (TNF)-alpha-induced activation of the nuclear transcription factor NF-kappaB, a factor that is essential for the expression of proinflammatory cytokines, in human monocytic U-937 cells, a T cell line (Jurkat) and peripheral blood mononuclear cells (PBMC). The inhibitory effect of theophylline on TNF-alpha-induced NF-kappaB activation was evaluated by Western blotting, flow cytometry and chloramphenicol acetyltransferase (CAT) assaying. Expression of the IkappaBalpha protein was evaluated by Western blotting.

RESULTS

Western blotting demonstrated that theophylline inhibits NF-kappaB activation in U-937 and Jurkat cells and PBMC. Flow cytometry demonstrated that theophylline inhibits NF-kappaB activation in U-937 and Jurkat cells in a dose-related manner. CAT assaying indicated that NF-kappaB-dependent reporter gene expression is inhibited in U-937 cells pretreated with theophylline. Western blotting of cytoplasmic extracts of U-937 cells revealed that this inhibition was linked to theophylline-induced preservation of expression of the IkappaBalpha protein.

CONCLUSIONS

These findings are consistent with the idea that theophylline suppresses the production of proinflammatory cytokines via inhibition of NF-kappaB activation through preservation of the IkappaBalpha protein in monocytes/macrophages and T cells.

Oxidative stress and lung inflammation in airways disease

Oxidative stress results from an oxidant/antioxidant imbalance in favour of oxidants. A large number of studies have demonstrated that increased oxidative burden occurs in airways diseases, shown by increased marks of oxidative stress in the airspaces and systemically in these patients. There is now substantial evidence that oxidative stress plays an important role in the injurious and inflammatory responses in airways diseases such as asthma and chronic obstructive pulmonary disease (COPD). In addition to these proinflammatory mechanisms resulting from oxidative stress, protective mechanisms such as the upregulation of protective antioxidant genes also occur. At present, effective antioxidant therapy that has good bioavailability and potency is not available. Such drugs are being developed and should in the future allow the hypothesis that oxidative stress is a fundamental factor in the inflammation, which occurs in these airways diseases to be tested.

PAF acetylhydrolase gene polymorphisms and asthma severity

This review describes the current understanding of the contributions of genetic alterations in platelet-activating factor (PAF) acetylhydrolase to the pathogenesis of asthma. A variety of in vitro and in vivo studies, performed by multiple laboratories, suggest that the lipid substrates of this enzyme, PAF and oxidised derivatives of phosphatidylcholines, play important roles as causative factors in many diseases including asthma. PAF acetylhydrolase inactivates PAF and oxidatively-fragmented lipids thus providing a mechanism to prevent their pro-inflammatory effects. Since it is a most unusual protein, the biochemical, structural and functional characteristics of PAF acetylhydrolase continue to be unravelled. First, the ability of this enzyme to inactivate pro-inflammatory lipid mediators is modulated by its association with lipoproteins and by its susceptibility to oxidative inactivation. Second, mediators of inflammation, such as the substrates for PAF acetylhydrolase, alter expression of the protein at the transcriptional level. Third, naturally-occurring variants of PAF acetylhydrolase have catalytic properties different from those exhibited by the most common form of this protein. Thus, a variety of factors, including genetics, contribute to determine the biological level of lipid substrates known to act as mediators of asthma and other diseases. Here, I summarise key studies that implicate PAF and related molecules as important mediators in the pathogenesis of asthma. Next, I describe clinical findings that are consistent with a role of PAF acetylhydrolase as a modulator of asthma. Third, I focus on the biochemical effects associated with naturally-occurring mutations and polymorphisms in the PAF acetylhydrolase gene and the incidence of these genetic variations in populations of asthmatic subjects. Finally, I present my views on the future of this emerging field and the potential utility of performing additional studies aimed at further characterising the contribution of PAF acetylhydrolase to the pathogenesis of a complex syndrome generally recognised as a multifactorial and heterogeneous disease.