Adenoviral E1A primes alveolar epithelial cells to PM(10)-induced transcription of interleukin-8

NADPH Oxidase Isoforms in COPD Patients and Acute Cigarette Smoke-Exposed Mice: Induction of Oxidative Stress and Lung Inflammation

Cigarette smoke (CS) is a major risk factor for chronic obstructive pulmonary disease (COPD), which represents the third leading cause of death worldwide. CS induces reactive oxygen species (ROS) production, leading to pulmonary inflammation and remodeling. NADPH oxidases (NOXs) represent essential sources of ROS production in the cardiovascular system. Whether and how NOX isoforms are activated in COPD patients and in response to acute cigarette smoke (ACS) remains incompletely understood. In the present study, the expression of NOX isoforms was examined in the lungs of end-stage COPD patients. In addition, mice silenced of NOX1 or NOX4 expression using in vivo RNA interference (RNAi), and NOX2-deficient (NOX2^−/y) mice, were exposed to ACS for 1 h using a standard TE-10B smoking machine. In lung sections isolated from COPD patients undergoing lung transplantation, protein expression of NOX1, NOX2, NOX4, or NOX5 was markedly upregulated compared to non-smoking donor controls. Likewise, ACS upregulated protein expression of NOX1, NOX2, and NOX4, production of ROS, inflammatory cell infiltration, and mRNA expression of proinflammatory cytokines TNF-α and KC in the mouse lung. In vivo RNAi knockdown of NOX1 or NOX4 decreased ACS induced ROS production, inflammatory cell influx, and the expression of TNF-α and KC, which were accompanied by inhibition of the NF-κB-COX-2 axis. Although ACS induced ROS production was reduced in the lungs of NOX2^−/y mice, inflammatory cell influx and expression of NF-κB/COX-2 were increased. Taken together, our results demonstrate for the first time that NOX isoforms 1, 2, 4 and 5 all remain activated in end-stage COPD patients, while NOX1 and NOX4 mediate oxidative stress and inflammatory responses in response to acute cigarette smoke. Therefore, targeting different isoforms of NOX might be necessary to treat COPD at different stages of the disease, which represents novel mechanistic insights enabling improved management of the devastating disease.

Air pollution, a possible risk factor for multiple sclerosis

OBJECTIVE

Studies focusing attention on the effects of environmental pollution on the etiology of multiple sclerosis (MS) are on the increase. The aim of this study was to determine MS prevalence in a city home to an iron and steel factory which causes air pollution.

METHODS

The study was designed as a cross-sectional, population-based, descriptive epidemiologic study. Ereğli city, which has an iron and steel factory and proven air pollution, was screened. Additionally, Devrek city, which is a rural and clean city, located 40 km away from Ereğli was assigned and results were compared. A validated questionnaire was used for screening. McDonald 2010 criteria were used to diagnose cases.

RESULTS

32 261 people were screened in Ereğli, and 21 963 people were screened in Devrek. In total, 41 patients were diagnosed with clinical definite MS. Crude prevalence was found to be 96.1/100 000 in Ereğli and 45.5/100 000 in Devrek. The mean age of patients was 39.8, and the female/male ratio was 1.9.

CONCLUSION

The results of this study indicate a more than double MS prevalence rate in the area home to an iron and steel factory when compared to the rural city. This supports the hypothesis that air pollution may be a possible etiological factor in MS.

Toxicology of ambient particulate matter

It is becoming increasingly clear that inhalation exposure to particulate matter (PM) can lead to or exacerbate various diseases, which are not limited to the lung but extend to the cardiovascular system and possibly other organs and tissues. Epidemiological studies have provided strong evidence for associations with chronic obstructive pulmonary disease (COPD), asthma, bronchitis and cardiovascular disease, while the evidence for a link with lung cancer is less strong. Novel research has provided first hints that exposure to PM might lead to diabetes and central nervous system (CNS) pathology. In the current review, an overview is presented of the toxicological basis for adverse health effects that have been linked to PM inhalation. Oxidative stress and inflammation are discussed as central processes driving adverse effects; in addition, profibrotic and allergic processes are implicated in PM-related diseases. Effects of PM on key cell types considered as regulators of inflammatory, fibrotic and allergic mechanisms are described.

Investigating the spill-over hypothesis: analysis of the association between local inflammatory markers in sputum and systemic inflammatory mediators in plasma

Exposure to air pollutants represents a risk factor not only for respiratory diseases and lung cancer, but also for cardiometabolic diseases. It has been hypothesised that local inflammation in the lung and systemic subclinical inflammation are linked by impaired lung function and the spill-over of proinflammatory factors from the lung into the circulation which could act as intermediaries between environmental exposures and disease risk. We wanted to investigate whether local and systemic inflammatory markers are associated, which would support the spill-over hypothesis. Sputum and plasma samples were obtained from 257 women of the German SALIA cohort. We performed immunoassays to measure multiple biomarkers of airway inflammation in sputum as well as cytokines, chemokines and soluble adhesion molecules in plasma. Correlations were calculated and adjusted for potentially confounding variables. Even though several significant associations were detected between inflammatory mediators in sputum and plasma, correlation coefficients were rather low ranging from r≥-0.20 to r≤0.20. Comparatively stronger associations were observed between nitrite, eosinophil cationic protein, leukotrienes C/D/E4 and interleukin-8 in sputum. Notably, correlations were positive with all proinflammatory biomarkers and interleukin-1 receptor antagonist in plasma, whereas negative correlations were observed with the anti-inflammatory adipokine adiponectin. In conclusion, local inflammation in the lung and systemic subclinical inflammation appear mainly independently regulated in elderly women from the general population. Although we found multiple significant correlations between inflammatory biomarkers in sputum and plasma, our results do not provide clear support for the spill-over hypothesis.

Anacardic acid, a histone acetyltransferase inhibitor, modulates LPS-induced IL-8 expression in a human alveolar epithelial cell line A549

OBJECTIVE AND DESIGN

The histone acetylation processes, which are believed to play a critical role in the regulation of many inflammatory genes, are reversible and regulated by histone acetyltransferases (HATs), which promote acetylation, and histone deacetylases (HDACs), which promote deacetylation. We studied the effects of lipopolysaccharide (LPS) on histone acetylation and its role in the regulation of interleukin (IL)-8 expression. 

MATERIAL

A human alveolar epithelial cell line A549 was used in vitro.

METHODS

Histone H4 acetylation at the IL-8 promoter region was assessed by a chromatin immunoprecipitation (ChIP) assay. The expression and production of IL-8 were evaluated by quantitative polymerase chain reaction and specific immunoassay. Effects of a HDAC inhibitor, trichostatin A (TSA), and a HAT inhibitor, anacardic acid, were assessed. 

RESULTS

Escherichia coli-derived LPS showed a dose- and time-dependent stimulatory effect on IL-8 protein production and mRNA expression in A549 cells in vitro. LPS showed a significant stimulatory effect on histone H4 acetylation at the IL-8 promoter region by ChIP assay. Pretreatment with TSA showed a dose-dependent stimulatory effect on IL-8 release from A549 cells as compared to LPS alone. Conversely, pretreatment with anacardic acid inhibited IL-8 production and expression in A549 cells. 

CONCLUSION

These data suggest that LPS-mediated proinflammatory responses in the lungs might be modulated via changing chromatin remodeling by HAT inhibition.

Role of NADPH oxidase/ROS in pro-inflammatory mediators-induced airway and pulmonary diseases

Reactive oxygen species (ROS) are products of normal cellular metabolism and are known to act as second messengers. Under physiological conditions, ROS participate in maintenance of cellular 'redox homeostasis' in order to protect cells against oxidative stress. In addition, regulation of redox state is important for cell activation, viability, proliferation, and organ function. However, overproduction of ROS, most frequently due to excessive stimulation of either reduced nicotinamide adenine dinucleotide phosphate (NADPH) by pro-inflammatory cytokines, such as tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) or the mitochondrial electron transport chain and xanthine oxidase, results in oxidative stress. Oxidative stress is a deleterious process that leads to airway and lung damage and consequently to several respiratory inflammatory diseases/injuries, including acute respiratory distress syndrome (ARDS), asthma, cystic fibrosis (CF), and chronic obstructive pulmonary disease (COPD). Many of the known inflammatory target proteins, such as matrix metalloproteinase-9 (MMP-9), intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), cyclooxygenase-2 (COX-2), and cytosolic phospholipase A(2) (cPLA(2)), are associated with NADPH oxidase activation and ROS overproduction in response to pro-inflammatory mediators. Thus, oxidative stress regulates both key inflammatory signal transduction pathways and target proteins involved in airway and lung inflammation. In this review, we discuss mechanisms of NADPH oxidase/ROS in the expression of inflammatory target proteins involved in airway and lung diseases. Knowledge of the mechanisms of ROS regulation could lead to the pharmacological manipulation of antioxidants in airway and lung inflammation and injury.

Nanoparticle-induced pulmonary toxicity

In recent decades, advances in nanotechnology engineering have given rise to the rapid development of many novel applications in the biomedical field. However, studies into the health and safety of these nanomaterials are still lacking. The main concerns are the adverse effects to health caused by acute or chronic exposure to nanoparticles (NPs), especially in the workplace environment. The lung is one of the main routes of entry for NPs into the body and, hence, a likely site for accumulation of NPs. Once NPs enter the interstitial air spaces and are quickly taken up by alveolar cells, they are likely to induce toxic effects. In this review, we highlight the different aspects of lung toxicity resulting from NP exposure, such as generation of oxidative stress, DNA damage and inflammation leading to fibrosis and pneumoconiosis, and the underlying mechanisms causing pulmonary toxicity.

[Atmospheric air pollution: a risk factor for COPD?]

Tobacco smoking is the leading cause of COPD worldwide but other risk factors have been recognized. Air pollution is one of them, but its exact role in the development of COPD is hard to demonstrate. Its physiological effects on lung function have only been studied since the nineties by long and tedious cohort studies. Difficulties arise from the heterogeneity of air pollution (gas and particles); thus, its respiratory effects have to be examined for every component separately, and in different populations. It is also necessary to analyse the effects of atmospheric pollution in the short and the long term, considering both its physiological, clinical and toxicological effects, from childhood to adulthood. These factors make it difficult to obtain statistically significant results. Nevertheless, most studies seem to point to a role of air pollution in the development of COPD via oxydative stress but further studies are needed to confirm the exact effect of each component of air pollution on the respiratory tract. These studies could lead to improved public health policies and results are awaited that would identify at-risk populations, decide appropriate preventive measures and propose documented thresholds in pollution exposure... thereby limiting the spread of COPD.

Roles of oxidative stress in signaling and inflammation induced by particulate matter

This review reports the role of oxidative stress in impairing the function of lung exposed to particulate matter (PM). PM constitutes a heterogeneous mixture of various types of particles, many of which are likely to be involved in oxidative stress induction and respiratory diseases. Probably, the ability of PM to cause oxidative stress underlies the association between increased exposure to PM and exacerbations of lung disease. Mostly because of their large surface area, ultrafine particles have been shown to cause oxidative stress and proinflammatory effects in different in vivo and in vitro studies. Particle components and surface area may act synergistically inducing lung inflammation. In this vein, reactive oxygen species elicited upon PM exposure have been shown to activate a number of redox-responsive signaling pathways and Ca(2+) influx in lung target cells that are involved in the expression of genes that modulate relevant responses to lung inflammation and disease.

Effects of particulate matter (PM(10), PM(2.5) and PM(1)) on the cardiovascular system

Several studies have demonstrated that exposure to particulate matter (PM) of different size fractions is associated with an increased risk of cardiovascular disease (CVD). In this review, we have taken into consideration the possible correlation between the "short term" and "long term" effects of PM exposure and the onset of CVDs as well as the possible molecular mechanisms by which PM elicits the development of these events. Particularly, it is here underlined that these adverse health effects depend not only on the level of PM concentration in the air but also on its particular internal composition. Furthermore, we have also synthesized the findings gleaned from those few studies indicating that PM produced by tobacco smoke can give rise to cardiovascular injury.

Particulate matter air pollution exposure: role in the development and exacerbation of chronic obstructive pulmonary disease

Due to the rapid urbanization of the world population, a better understanding of the detrimental effects of exposure to urban air pollution on chronic lung disease is necessary. Strong epidemiological evidence suggests that exposure to particulate matter (PM) air pollution causes exacerbations of pre-existing lung conditions, such as, chronic obstructive pulmonary disease (COPD) resulting in increased morbidity and mortality. However, little is known whether a chronic, low-grade exposure to ambient PM can cause the development and progression of COPD. The deposition of PM in the respiratory tract depends predominantly on the size of the particles, with larger particles deposited in the upper and larger airways and smaller particles penetrating deep into the alveolar spaces. Ineffective clearance of this PM from the airways could cause particle retention in lung tissues, resulting in a chronic, low-grade inflammatory response that may be pathogenetically important in both the exacerbation, as well as, the progression of lung disease. This review focuses on the adverse effects of exposure to ambient PM air pollution on the exacerbation, progression, and development of COPD.

Environmental exposures and gene regulation in disease etiology

Health or disease is shaped for all individuals by interactions between their genes and environment. Exactly how the environment changes gene expression and how this can lead to disease are being explored in a fruitful new approach to environmental health research, representative studies of which are reviewed here. We searched Web of Science and references of relevant publications to understand the diversity of gene regulatory mechanisms affected by environmental exposures with disease implications. Pharmaceuticals, pesticides, air pollutants, industrial chemicals, heavy metals, hormones, nutrition, and behavior can change gene expression through a broad array of gene regulatory mechanisms. Furthermore, chemically induced changes in gene regulation are associated with serious and complex human diseases, including cancer, diabetes and obesity, infertility, respiratory diseases, allergies, and neurodegenerative disorders such as Parkinson and Alzheimer diseases. The reviewed studies indicate that genetic predisposition for disease is best predicted in the context of environmental exposures. And the genetic mechanisms investigated in these studies offer new avenues for risk assessment research. Finally, we are likely to witness dramatic improvements in human health, and reductions in medical costs, if environmental pollution is decreased.

Airways inflammation and treatment during acute exacerbations of COPD

INTRODUCTION

Inflammation is a core feature of acute chronic obstructive pulmonary disease (COPD) exacerbations. It is important to focus on inflammation since it gives insight into the pathological changes causing an exacerbation, thereby possibly providing directions for future therapies which modify inflammation.

OBJECTIVES

To provide a cell-by-cell overview of the inflammatory processes during COPD exacerbations. To evaluate cell activation, and cytokine production, cellular interactions, damaging effects of inflammatory mediators to tissue, and the relation to symptoms at the onset of COPD exacerbations. To speculate on future therapeutic options to modify inflammation during COPD exacerbations.

RESULTS

During COPD exacerbations, there is increased airway wall inflammation, with pathophysiological influx of eosinophils, neutrophils, and lymphocytes. Although links have been suggested between the increase in eosinophils and lymphocytes and a viral etiology of the exacerbation, and between the increase in neutrophils and a bacterial aetiology, these increases in both inflammatory cell types are not limited to the respective aetiologies and the underlying mechanisms remain elusive.

CONCLUSION

Further research is required to fully understand the inflammatory mechanisms in the onset and development of COPD exacerbations. This might make inflammatory pathway-specific intervention possible, resulting in a more effective treatment of COPD exacerbations with fewer side effects.

Pathogenesis of chronic obstructive pulmonary disease

The pathogenesis of chronic obstructive pulmonary disease (COPD) encompasses a number of injurious processes, including an abnormal inflammatory response in the lungs to inhaled particles and gases. Other processes, such as failure to resolve inflammation, abnormal cell repair, apoptosis, abnormal cellular maintenance programs, extracellular matrix destruction (protease/antiprotease imbalance), and oxidative stress (oxidant/antioxidant imbalance) also have a role. The inflammatory responses to the inhalation of active and passive tobacco smoke and urban and rural air pollution are modified by genetic and epigenetic factors. The subsequent chronic inflammatory responses lead to mucus hypersecretion, airway remodeling, and alveolar destruction. This article provides an update on the cellular and molecular mechanisms of these processes in the pathogenesis of COPD.

Environmental exposures and gene regulation in disease etiology

OBJECTIVE

Health or disease is shaped for all individuals by interactions between their genes and environment. Exactly how the environment changes gene expression and how this can lead to disease are being explored in a fruitful new approach to environmental health research, representative studies of which are reviewed here.

DATA SOURCES

We searched Web of Science and references of relevant publications to understand the diversity of gene regulatory mechanisms affected by environmental exposures with disease implications.

DATA SYNTHESIS

Pharmaceuticals, pesticides, air pollutants, industrial chemicals, heavy metals, hormones, nutrition, and behavior can change gene expression through a broad array of gene regulatory mechanisms. Mechanisms include regulation of gene translocation, histone modifications, DNA methylation, DNA repair, transcription, RNA stability, alternative RNA splicing, protein degradation, gene copy number, and transposon activation. Furthermore, chemically induced changes in gene regulation are associated with serious and complex human diseases, including cancer, diabetes and obesity, infertility, respiratory diseases, allergies, and neurodegenerative disorders such as Parkinson and Alzheimer diseases. One of the best-studied areas of gene regulation is epigenetics, especially DNA methylation. Our examples of environmentally induced changes in DNA methylation are presented in the context of early development, when methylation patterns are initially laid down. This approach highlights the potential role for altered DNA methylation in fetal origins of adult disease and inheritance of acquired genetic change.

CONCLUSIONS

The reviewed studies indicate that genetic predisposition for disease is best predicted in the context of environmental exposures. Second, the genetic mechanisms investigated in these studies offer new avenues for risk assessment research. Finally, we are likely to witness dramatic improvements in human health, and reductions in medical costs, if environmental pollution is decreased.

Adenovirus infections and lung disease

Adenovirus, particularly its E1A protein, has been investigated in the pathogenesis of chronic obstructive pulmonary disease (COPD). High levels of E1A DNA were found in the lungs of COPD patients, where its expression increased with disease severity. In lung epithelial cells, E1A increased intercellular adhesion molecule-1 and interleukin-8 expression, as well as nuclear factor-kappaB activation, in response to inflammatory stimuli. In addition to regulating the mediators that promote emphysema, E1A upregulates transforming growth factor-beta1 expression in bronchiolar epithelial cells and transforms lung epithelial cells to express mesenchymal markers. These results support its additional role in the airway remodeling process reported in COPD.

The pharmacology of particulate matter air pollution-induced cardiovascular dysfunction

Since the London fog of 1952, in which more than 4000 people were killed in 4 days, the combined efforts of scientists from several disciplines, including those from the environmental health, clinical and biomedical disciplines, have raised serious concerns about the impact of air pollutants on human health. These environmental pollutants are rapidly being recognized as important and independent risk factors for several diseases such as asthma, chronic obstructive pulmonary disease, lung cancer, atherosclerosis, ischemic heart disease and stroke. Although the relative effects of particulate matter air pollution (aerodynamic diameter <10 microm, or PM(10)) are greater for respiratory than for cardiovascular deaths, the number of deaths attributable to PM(10) is much larger for cardiovascular than for respiratory reasons due to the higher prevalence of cardiovascular disease in the general population. This review summarizes current understanding of the mechanisms underlying the associations between PM(10) exposure and cardiovascular morbidity and mortality.

Pathogenesis of chronic obstructive pulmonary disease

The current paradigm for the pathogenesis of chronic obstructive pulmonary disease is that chronic airflow limitation results from an abnormal inflammatory response to inhaled particles and gases in the lung. Airspace inflammation appears to be different in susceptible smokers and involves a predominance of CD8+ T lymphocytes, neutrophils, and macrophages. Studies have characterized inflammation in the peripheral airspaces in different stages of disease severity. Two other processes have received considerable research attention. The first is a protease-antiprotease imbalance, which has been linked to the pathogenesis of emphysema. However, the hypothesis of an increased protease burden associated with functional inhibition of antiproteases has been difficult to prove and is now considered an oversimplification. The second process, oxidative stress, has a role in many of the pathogenic processes of chronic obstructive pulmonary disease and may be one mechanism that enhances the inflammatory response. In addition, it has been proposed that the development of emphysema may involve alveolar cell loss through apoptosis. This mechanism may involve the vascular endothelial growth factor pathway and oxidative stress.

Lipopolysaccharide accelerates caspase-independent but cathepsin B-dependent death of human lung epithelial cells

Caspase-independent cell death has drawn increasing attention. In the present study, we found that lipopolysaccharide (LPS) accelerated spontaneous death of human lung epithelial A549 cells in a serum- and cell density-dependent manner: while serum starvation has been demonstrated to induce apoptosis in the same cell line, LPS-induced cell death was only observed in the presence of serum; in addition, the cell death was not observed when the cells were seeded at 10- or 100-fold lower density. The apoptotic features were demonstrated by TUNEL assay, DNA laddering and Annexin V staining. However, treatment of cells with two commonly used pan-caspase inhibitors, zVAD.fmk or BOC-D.fmk, failed to block cell death. In contrast, two cathepsin B inhibitors, Ca074-Me or N-1845, reduced cell death significantly. A time-dependent activation of cathepsin B, but not caspase 3, was observed in both control and LPS-treated cells. Although LPS did not further activate cathepsin B or its release, it increased expression and translocation of apoptosis inducing factor from mitochondria to the nucleus, and increased release of cytochrome c from mitochondria. LPS-induced cell death was significantly attenuated by either N-acetyl-L-cysteine or pyrrolidine-dithiocarbamate, both free radical scavengers. Disruption of lipid raft formation with filipin or methyl-beta-cyclodextrin also reduced apoptosis significantly, suggesting that lipid raft-dependent signaling is essential. These data imply that confluent cells undergo spontaneous cell death mediated by cathepsin B; LPS may accelerate this caspase-independent cell death through release of mitochondrial contents and reactive oxygen species.

Effect of the adenovirus E1A gene on nitric oxide production in alveolar epithelial cells

This study determined the effect of the adenovirus E1A gene on nitric oxide (NO) production in alveolar epithelial (A549) cells. E1A-positive A549 cells (E1A transfectants), E1A-negative A549 cells (control transfectants) and untransfected A549 cells were placed in 96-well tissue culture plates. After stimulation with lipopolysaccharide (LPS) or cytokine mixture (CM), the biochemical reaction products of NO (nitrite and nitrate) in the culture medium were measured by chemiluminescence. The inducible (iNOS) and the endothelial (eNOS) isoforms of nitric oxide synthase (NOS) protein expression were examined by Western blotting. iNOS mRNA expression was examined by Northern blotting and RT-PCR. CM-induced NO production by E1A-positive A549 cells was significantly lower than that of E1A-negative cells (p < 0.0001). LPS stimulation failed to enhance NO production in both cell types. CM induced iNOS protein expression in E1A-negative A549 cells, but not in E1A-positive cells. eNOS protein expression was constitutive and was not affected by CM stimulation, LPS stimulation or E1A. CM induced iNOS mRNA expression in E1A-negative A549 cells, but not in E1A-positive cells. In conclusion, the adenovirus E1A gene suppressed NO production through transcriptional control of the iNOS gene in A549 cells. This inhibition of NO production may enable the virus to persist in human tissue, since NO is an antiviral effector of the innate immune system.

Curcumin induces glutathione biosynthesis and inhibits NF-kappaB activation and interleukin-8 release in alveolar epithelial cells: mechanism of free radical scavenging activity

Oxidants and tumor necrosis factor-alpha (TNF-alpha) activate transcription factors such as nuclear factor-kappaB (NF-kappaB), which is involved in the transcription of proinflammatory mediators, including interleukin-8 (IL-8). Curcumin (diferuloylmethane) is a naturally occurring flavonoid present in the spice turmeric, which has a long traditional use as a chemotherapeutic agent for many diseases. We hypothesize that curcumin may possess both antioxidant and antiinflammatory properties by increasing the glutathione levels and inhibiting oxidant- and cytokine-induced NF-kappaB activation and IL-8 release from cultured alveolar epithelial cells (A549). Treatment of A549 cells with hydrogen peroxide (H2O2; 100 microM) and TNF-alpha (10 ng/ml) significantly increased NF-kappaB and activator protein-1 (AP-1) activation, as well as IL-8 release. Curcumin inhibited both H2O2- and TNF-alpha-mediated activation of NF-kappaB and AP-1, and IL-8 release. Furthermore, an increased level of GSH and glutamylcysteine ligase catalytic subunit mRNA expression was observed in curcumin-treated cells as compared with untreated cells. Curcumin interacted directly with superoxide anion (O2*-) and hydroxyl radical (*OH) as shown by electron paramagnetic resonance, quenching the interaction of the radicals with the spin trap, Tempone-H. This suggests that curcumin has multiple properties: as an oxygen radical scavenger, antioxidant through modulation of glutathione levels, and antiinflammatory agent through inhibition of IL-8 release in lung cells.

Hypertensive rats are susceptible to TLR4-mediated signaling following exposure to combustion source particulate matter

Toll-like receptor 4 (TLR4) has been shown to play a role in cell signaling that results in neutrophilic inflammation in response to lipopolysaccharide and respiratory syncytial virus infection. TLR4 also interacts with CD14, which upon complex formation triggers TLR4-associated signaling pathways to produce a proinflammatory response. This mechanism results in the activation of NF-kappa B and subsequent inflammatory gene induction. In order to determine the effect of combustion source particle matter (PM), rich in zinc and nickel but with negligible endotoxin, on a possible activation of TLR4-mediated cell signaling and inflammation, we intratracheally (IT) instilled 3.3 mg/kg of PM into 12-w-old healthy male Wistar Kyoto (WKY) and susceptible spontaneously hypertensive (SH) rats. Inflammation, inflammatory-mediator gene expression, bronchoalveolar lavage fluid (BALF) protein and LDH, TLR4 and CD14 protein, and NF-kappa B activation in the lung were determined after 24 h. Dose-response data (0.0, 0.83, 3.33, and 8.3 mg/kg PM) for BALF LDH were obtained as a marker of lung cell injury in SH rats. BALF neutrophils, but not macrophages, were significantly increased in the PM-exposed WKY and SH rats. SH rats showed a greater PMN increase than WKY rats. Similarly, BALF protein and LDH levels were also increased following PM exposure but to a significantly greater extent in SH rats. Plasma fibrinogen was increased only in SH rats exposed to PM. The increased inflammation seen in PM-exposed SH rats was accompanied by a significant increase in TLR4 protein in the lung tissue, which was primarily localized in alveolar macrophages and epithelial cells. CD14 was also increased by PM exposure in both SH and WKY rats but was significantly greater in the SH rats. These increases were associated with greater translocation of NF-kappa B in the lungs of SH rather than WKY rats. This was accompanied by increased macrophage inhibitory protein (MIP)-2 mRNA expression at 24 h of exposure. These data suggest that the increased inflammation in the lungs of PM-exposed SH rats compared to WKY rats is accompanied by an increase in TLR4-mediated cell signaling. Thus, one of the mechanisms for greater susceptibility of SH rats to PM exposure may involve an increased activation of the TLR4 signaling pathway.

Dosimetry and toxicology of ultrafine particles

While epidemiological studies indicate an association between adverse health effects and ambient ultrafine particle concentrations in susceptible individuals, toxicological studies aim to identify mechanisms which are causal for the gradual transition from the physiological status towards patho-physiological disease. Impressive progress has been made in recent years when objectives changed from classical tests like lung function, etc. to endpoints comprising of particle induced oxidative stress, cell signaling and activation, release of mediators initiating inflammatory processes not only in the respiratory tract but also in the cardio-vascular system. Particularly, the large surface area of ultrafine particles provides a unique interface for catalytic reactions of surface-located agents with biological targets like proteins, cells, etc. However, toxicological studies are hampered by a number of imminent complications when simulating long-term exposure of humans in urban environments with inherited and/or acquired susceptibility (e.g., acute exposure studies at high concentrations either in human subjects or animal models). Yet, based on a conservative estimate results available begin to show an adverse health risk for susceptible individuals and support the epidemiological evidence.

Pathophysiology of airflow limitation in chronic obstructive pulmonary disease

The airflow limitation that defines chronic obstructive pulmonary disease (COPD) is the result of a prolonged time constant for lung emptying, caused by increased resistance of the small conducting airways and increased compliance of the lung as a result of emphysematous destruction. These lesions are associated with a chronic innate and adaptive inflammatory immune response of the host to a lifetime exposure to inhaled toxic gases and particles. Processes contributing to obstruction in the small conducting airways include disruption of the epithelial barrier, interference with mucociliary clearance apparatus that results in accumulation of inflammatory mucous exudates in the small airway lumen, infiltration of the airway walls by inflammatory cells, and deposition of connective tissue in the airway wall. This remodelling and repair thickens the airway walls, reduces lumen calibre, and restricts the normal increase in calibre produced by lung inflation. Emphysematous lung destruction is associated with an infiltration of the same type of inflammatory cells found in the airways. The centrilobular pattern of emphysematous destruction is most closely associated with cigarette smoking, and although it is initially focused on respiratory bronchioles, separate lesions coalesce to destroy large volumes of lung tissue. The panacinar pattern of emphysema is characterised by a more even involvement of the acinus and is associated with alpha1 antitrypsin deficiency. The technology needed to diagnose and quantitate the individual small airway and emphysema phenotypes present in people with COPD is being developed, and should prove helpful in the assessment of therapeutic interventions designed to modify the progress of either phenotype.

Therapy for chronic obstructive pulmonary disease in the 21st century

Chronic obstructive pulmonary disease (COPD) is a common, smoking-related, severe respiratory condition characterised by progressive, irreversible airflow limitation. Current treatment of COPD is symptomatic, with no drugs capable of halting the relentless progression of airflow obstruction. Better understanding of the airway inflammation, oxidative stress and alveolar destruction that characterise COPD has delineated new disease targets, with consequent identification of novel compounds with therapeutic potential. These new drugs include aids to smoking cessation (e.g. bupropion) and improvements to existing therapies, for example long-acting rather than short-acting bronchodilators, as well as combination therapy. New antiproteases include acyl-enzyme and transition state inhibitors of neutrophil elastase (e.g. sivelestat and ONO-6818), matrix metalloprotease inhibitors (e.g. batimastat), cathepsin inhibitors and peptide protease inhibitors (e.g. DX-890 [EPI-HNE-4] and trappin-2). New antioxidants include superoxide dismutase mimetics (e.g. AEOL-10113) and spin trap compounds (e.g. N-tert-butyl-alpha-phenylnitrone). New anti-inflammatory interventions include phosphodiesterase-4 inhibitors (e.g. cilomilast), inhibitors of tumour necrosis factor-alpha (e.g. humanised monoclonal antibodies), adenosine A(2a) receptor agonists (e.g. CGS-21680), adhesion molecule inhibitors (e.g. bimosiamose [TBC1269]), inhibitors of nuclear factor-kappaB (e.g. the naturally occurring compounds hypoestoxide and (-)-epigallocatechin-3-gallate) and activators of histone deacetylase (e.g. theophylline). There are also selective inhibitors of specific extracellular mediators such as chemokines (e.g. CXCR2 and CCR2 antagonists) and leukotriene B(4) (e.g. SB201146), and of intracellular signal transduction molecules such as p38 mitogen activated protein kinase (e.g. RWJ67657) and phosphoinositide 3-kinase. Retinoids may be one of the few potential treatments capable of reversing alveolar destruction in COPD, and a number of compounds are in clinical trial (e.g. all-trans-retinoic acid). Talniflumate (MSI-1995), an inhibitor of human calcium-activated chloride channels, has been developed to treat mucous hypersecretion. In addition, the purinoceptor P2Y(2) receptor agonist diquafosol (INS365) is undergoing clinical trials to increase mucus clearance. The challenge to transferral of these new compounds from preclinical research to disease management is the design of effective clinical trials. The current scarcity of well characterised surrogate markers predicts that long-term studies in large numbers of patients will be needed to monitor changes in disease progression.

Contribution of IL-1 beta and TNF-alpha to the initiation of the peripheral lung response to atmospheric particulates (PM10)

Alveolar macrophages (AM) play a key role in clearing atmospheric particulates from the lung surface and stimulating epithelial cells to produce proinflammatory mediators. The present study examines the role of "acute response" cytokines TNF-alpha and IL-1 beta released by AM exposed to ambient particulate matter with a diameter of <10 microm (PM(10)) in amplifying the proinflammatory mediator expression by A549 cells and human bronchial epithelial cells (HBEC). The results showed that supernatants from human AM incubated 24 h with PM(10) (100 microg/ml) contained more TNF-alpha, IL-1 beta, granulocyte-macrophage colony stimulating factor, IL-6, and IL-8 than nonexposed AM supernatants. The 3-h treatment of A549 cells with PM(10)-exposed AM supernatants increased TNF-alpha, IL-1 beta, IL-8, regulated on activation normal T-cells expressed and secreted (RANTES), and leukemia inhibitory factor mRNA compared with the treatment with nonexposed AM supernatants and, compared with untreated A549 cells, additionally increased ICAM-1 and monocyte chemotactic protein-1 mRNA. Preincubating PM(10)-exposed AM supernatants with anti-IL-1 beta antibodies reduced all the above mediators as well as VEGF mRNA expression (P < 0.05), while anti-TNF-alpha antibodies were less effective (P > 0.05), and the combination of the two antibodies most effective. When HBEC were treated similarly, anti-TNF-alpha antibodies had the greatest effect. In A549 cells PM(10)-exposed AM supernatants increased NF-kappa B, activator protein (AP)-1 and specificity protein 1 binding, while anti-TNF-alpha and anti-IL-1 beta antibodies reduced NF-kappa B and AP-1 binding. We conclude that AM-derived TNF-alpha and IL-1 beta provide a major stimulus for the production of proinflammatory mediators by lung epithelial cells and that their relative importance may depend on the type of epithelial cell target.

Rhinovirus 16 3C protease induces interleukin-8 and granulocyte-macrophage colony-stimulating factor expression in human bronchial epithelial cells

Rhinovirus (RV), a member of the Picornaviridae family, accounts for many virus-induced asthma exacerbations. RV induces airway cell chemokine expression both in vivo and in vitro. Because of the known interactions of proteases with cellular functions, we hypothesized that RV 3C protease is sufficient for cytokine up-regulation. A cDNA encoding RV16 3C protease was constructed by PCR amplification and transfected into 16HBE14o- human bronchial epithelial cells. 3C protease induced expression of both IL-8 and GM-CSF, as well as transcription from both the IL-8 and GM-CSF promoters. 3C expression also induced activator protein 1 and NF-kappaB transcriptional activation. Finally, mutation of IL-8 promoter AP-1 and NF-kappaB promoter sequences significantly reduced 3C-induced responses. Together, these data suggest expression of RV16 3C protease is sufficient to induce chemokine expression in human bronchial epithelial cells, and does so in an AP-1- and NF-kappaB-dependent manner.

The role of oxidative stress in chronic obstructive pulmonary disease

Tobacco smoke is the number one risk factor for chronic obstructive pulmonary disease (COPD) and contains a high concentration of oxidants. The lung has a high concentration of antioxidants and antioxidant enzymes; however, COPD patients show evidence of increased oxidative stress suggesting that endogenous antioxidants may be insufficient to prevent oxidative damage from cigarette smoke. The consequences of increased oxidative stress in the lung include increased transcription of inflammatory genes, increased protease activity, and increased mucus secretion. Oxidative stress is often associated with impaired skeletal muscle function and may be one of the causes of glucocorticoid resistance. While current pharmacologic approaches to the treatment of chronic obstructive pulmonary disease do not commonly include antioxidants, preclinical studies involving animal models suggest that antioxidant superoxide dismutase mimetics offer a potential new therapeutic approach to the prevention and treatment of chronic obstructive pulmonary disease.

Innate immune responses to LPS in mouse lung are suppressed and reversed by neutralization of GM-CSF via repression of TLR-4

The innate immune inflammatory response to lipopolysaccharide (LPS, an endotoxin) is essential for lung host defense against infection by gram-negative bacteria but is also implicated in the pathogenesis of some lung diseases. Studies on genetically altered mice implicate granulocyte-macrophage colony-stimulating factor (GM-CSF) in lung responses to LPS; however, the physiological effects of GM-CSF neutralization are poorly characterized. We performed detailed kinetic and dose-response analyses of the lung inflammation response to LPS in the presence of the specific GM-CSF-neutralizing antibody 22E9. LPS instilled into the lungs of BALB/c mice induced a dose-dependent inflammation comprised of intense neutrophilia, macrophage infiltration and proliferation, TNF-alpha and matrix metalloproteinase release, and macrophage inflammatory protein-2 induction. The neutralization of anti-GM-CSF in a dose-dependent fashion suppressed these inflammatory indexes by 85% when given before or after LPS or after repeat LPS challenges. Here we report for the first time that the physiological expression of Toll-like receptor-4 in lung is reduced by anti-GM-CSF. We observed that lower Toll-like receptor-4 expression correlated with a similar decline in peak TNF- levels in response to endotoxin. Consequently, sustained expression of key inflammatory mediators over 24 h was reduced. These data expand the understanding of the contribution of GM-CSF to innate immune responses in lung and suggest that blocking GM-CSF might benefit some lung diseases where LPS has been implicated in etiology.

New concepts in chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is a leading cause of death and disability but has only recently been explored from a cellular and molecular perspective. In COPD, chronic inflammation leads to fixed narrowing of small airways and alveolar wall destruction (emphysema). This is characterized by increased numbers of alveolar macrophages, neutrophils, and cytotoxic T lymphocytes, and the release of multiple inflammatory mediators (lipids, chemokines, cytokines, growth factors). There is also a high level of oxidative stress, which may amplify this inflammation. There is increased elastolysis and probable involvement of matrix metalloproteinases. The inflammation and proteolysis in COPD is an amplification of the normal inflammatory response to cigarette smoke. Unlike asthma, this inflammation appears to be resistant to corticosteroids, prompting a search for novel anti-inflammatory therapies that may prevent the relentless progression of the disease.

Oxidative stress and calcium signaling in the adverse effects of environmental particles (PM10)

This review focuses on the potential role that oxidative stress plays in the adverse effects of PM(10). The central hypothesis is that the ability of PM(10) to cause oxidative stress underlies the association between increased exposure to PM(10) and both exacerbations of lung disease and lung cancer. Pulmonary inflammation may also underlie the cardiovascular effects seen following increased PM(10), although the mechanisms of the cardiovascular effects of PM(10) are not well understood. PM(10) is a complex mix of various particle types and several of the components of PM(10) are likely to be involved in the induction of oxidative stress. The most likely of these are transition metals, ultrafine particle surfaces, and organic compounds. In support of this hypothesis, oxidative stress arising from PM(10) has been shown to activate a number of redox-responsive signaling pathways in lung target cells. These pathways are involved in expression of genes that play a role in responses relevant to inflammation and pathological change, including MAPKs, NF-kappaB, AP-1, and histone acetylation. Oxidative stress from particles is also likely to play an important role in the carcinogenic effects associated with PM(10) and hydroxyl radicals from PM(10) cause DNA damage in vitro.

Histone acetylation regulates epithelial IL-8 release mediated by oxidative stress from environmental particles

Increases in the levels of environmental particulate matter with a diameter of <10 microm diameter (PM(10)) in the air are associated with a variety of adverse health effects, particularly chronic lung and cardiovascular diseases. The expression of many inflammatory genes involves the remodeling of the chromatin structure provided by histone proteins. Histone acetylation causes the unwinding of chromatin structure, therefore allowing transcription factor access to promoter sites. Acetylation is reversible and is regulated by histone acetyltransferases (HATs), which promote acetylation, and deacetylases, which promote deacetylation. PM(10) and H(2)O(2) increased IL-8 protein release from A549 cells after 24-h treatment, and this was enhanced by histone deacetylase inhibition by trichostatin A (cotreatment). PM(10) and H(2)O(2) treatment also increased HAT activity as well as the level of acetylated histone 4 (H4). PM(10) enhanced H4 acetylation that was mediated by oxidative stress as shown by thiol antioxidant inhibition. Acetylation of H4 mediated by PM(10) was associated with the promoter region of the IL-8 gene. These data suggest that remodeling of chromatin by histone acetylation plays a role in PM(10)-mediated responses in the lungs.

Adenoviral E1A modulates inflammatory mediator expression by lung epithelial cells exposed to PM10

We examined the hypothesis that ambient particulate matter with a diameter of <10 microm (PM(10))-induced lung inflammation is amplified by latent adenovirus infection. Inflammatory mediator expression in response to PM(10) exposure was compared between adenovirus E1A-transfected A549 alveolar epithelial cells and cells transfected with control plasmid. Messenger RNA was measured by the RNase protection assay and protein by ELISA or immunocytochemistry. Intercellular adhesion molecule-1 and IL-8 mRNA and protein were increased in E1A-positive cells exposed to 500 microg/ml PM(10). Monocyte chemoattractant protein-1 mRNA and protein were unchanged in E1A-positive cells but increased in E1A-negative cells after 100 and 500 microg/ml PM(10) exposure. Electrophoretic mobility shift assays showed increased NF-kappaB and decreased specificity protein 1 nuclear binding in E1A-positive cells exposed to PM(10). These results indicate that E1A modulates cytokine and adhesion molecule expression in epithelial cells in a manner that could amplify PM(10)-induced lung inflammation. We suggest that this amplified inflammatory response may contribute to the pathogenesis of exacerbations of chronic obstructive pulmonary disease associated with exposure to particulate matter air pollution.

The antioxidant cocktail effective microorganism X (EM-X) inhibits oxidant-induced interleukin-8 release and the peroxidation of phospholipids in vitro

The antioxidant beverage EM-X is derived from the ferment of unpolished rice, papaya, and sea-weeds with effective microorganisms. Oxidative stress enhances the expression of proinflammatory genes, causing the release of the chemokine interleukin-8 (IL-8), which mediates a multitude of inflammatory events. Human alveolar epithelial cells (A549) were treated with H(2)O(2) (100 microM) or TNF-alpha (10ng/ml) alone or with the addition of EM-X (100 microl/ml), incubated for 20h, and the release of IL-8, measured using ELISA. EM-X inhibited the release of IL-8 at the transcriptional level in A549 cells. EM-X also decreased the iron/ascorbate dependent peroxidation of ox-brain phospholipids in a concentration dependent manner. A TEAC value of 0.10+/-0.05mM was obtained for EM-X, indicating antioxidant potential. We suggest that the anti-inflammatory and antioxidant properties of EM-X are dependent on the flavonoid contents of the beverage.

Oxidative stress, transcription factors and chromatin remodelling in lung inflammation

Oxidative stress has been implicated in the pathogenesis of several inflammatory lung disorders. Oxidants and inflammatory mediators such as tumour necrosis factor-alpha (TNF-alpha) activate transcription factors such as nuclear factor-kappaB (NF-kappaB) and activator protein-1 (AP-1) leading to the expression of pro-inflammatory genes. The expression of many genes, including those encoding pro-inflammatory mediators involves the remodelling of the chromatin structure provided by histone proteins. Histone acetylation causes the unwinding of chromatin structure therefore allowing transcription factor access to promoter sites. Nuclear histone acetylation is a reversible process, and is regulated by a group of acetyltransferases (HATs) which promote acetylation, and deacetylases (HDACs) which promote deacetylation. In addition, several co-activators, transcription factors and nuclear proteins also have histone acetyltransferase activity. Both TNF-alpha and the oxidant, hydrogen peroxide (H2O2) alter histone acetylation/deacetylation, and the activation of NF-kappaB and AP-1, leading to the release of the pro-inflammatory cytokine interleukin-8 (IL-8) in human alveolar epithelial cells (A549). Pharmacological inhibition of HDAC leads to the increased HAT activity, AP-1 and NF-kappaB activation, and IL-8 release by H2O2 or TNF-alpha treatments. This suggests that the remodelling of chromatin by histone acetylation plays a role in the oxidant-mediated pro-inflammatory responses in the lungs.

Inhibition of LPS-induced activation of alveolar macrophages by high concentrations of LPS-binding protein

Lipopolysaccharide (LPS)-binding protein regulates the effects of LPS on immunocompetent cells. By catalyzing the binding of LPS to membrane CD14, LPS-binding protein (LBP) potentiates both the inflammatory response and internalization of LPS. LBP-mediated transport of LPS into high density lipoprotein particles participates in LPS clearance. Elevated serum levels of LBP have been shown to elicit protective effects in vivo. Because the expression of LBP is upregulated in lung epithelial cells upon proinflammatory stimulation, we here investigated whether LBP modulates inflammatory responses by lung specific cells. The moderate elevation of LBP concentrations enhanced both LPS-induced signaling and LPS uptake by rat alveolar macrophages, whereas strongly elevated LBP levels inhibited both. In contrast, the lung epithelial cell line A549 responded to high concentrations of LBP by an enhanced LPS uptake which did not result in cellular activation, suggesting an anti-inflammatory function of these cells by clearing LPS.

Latent adenovirus infection in COPD

We have concentrated on the adenovirus as the source of the heightened inflammatory response of the lungs of patients with COPD. We have concentrated in particular on the responses to agents such as lipopolysaccharides and environmental particulates that contaminate the air we breathe, and we have accumulated evidence that the E1A gene of this virus could be the key player in this process. As other intracellular pathogens such as Chlamydia pneumoniae have recently been implicated in the pathogenesis of COPD, our studies on the adenovirus E1A could serve as the model for investigating the interaction between host and extrinsic factors in the chronic progression of this debilitating lung disease.

PM(10)-exposed macrophages stimulate a proinflammatory response in lung epithelial cells via TNF-alpha

There is now considerable evidence for an association between the levels of particulate air pollution [particulate matter <10 microm in aerodynamic diameter (PM(10))] and various adverse health endpoints. The release of proinflammatory mediators from PM(10)-exposed macrophages may be important in stimulating cytokine release from lung epithelial cells, thus amplifying the inflammatory response. A549 cells were treated with conditioned media from monocyte-derived macrophages stimulated with PM(10), titanium dioxide (TiO(2)), or ultrafine TiO(2). We demonstrate that only conditioned media from PM(10)-stimulated macrophages significantly increased nuclear factor-kappaB and activator protein-1 DNA binding, enhanced interleukin-8 (IL-8) mRNA levels as assessed by RT-PCR, and augmented IL-8 protein levels, over untreated controls. Furthermore, PM(10)-conditioned media also caused transactivation of IL-8 as determined by an IL-8-chloramphenicol acetyl transferase reporter. Analysis of these conditioned media revealed marked increases in tumor necrosis factor-alpha (TNF-alpha) and protein levels and enhanced chemotactic activity for neutrophils. Preincubation of conditioned media with TNF-alpha-neutralizing antibodies significantly reduced IL-8 production. These data suggest that PM(10)-activated macrophages may amplify the inflammatory response by enhancing IL-8 release from lung epithelial cells, in part, via elaboration of TNF-alpha.