Differential inhibition of inflammatory cytokine release from cultured alveolar macrophages from smokers and non-smokers by NO2

Associations between air pollutants and acute exacerbation of drug-resistant tuberculosis: evidence from a prospective cohort study

BACKGROUND

Short-term exposure to air pollution may trigger symptoms of drug-resistant tuberculosis (DR-TB) through stimulating lung tissue, damaging tracheobronchial mucosa, the key anti-mycobacterium T cell immune function, and production and release of inflammatory cytokines.

OBJECTIVE

To investigate the association between acute exacerbations of DR-TB and short-term residential exposure to air pollutants (PM10, PM2.5, SO2, NO2, CO and O3) based on a large prospective cohort in Anhui Province, China.

METHOD

Patients were derived from a prospective cohort study of DR-TB in Anhui Province. All DR-TB patients underwent drug-susceptibility testing and prefecture-level reference laboratories confirmed their microbiologies. The case-crossover design was performed to evaluate the association between the risk of acute exacerbations of DR-TB and short-term residential exposure to air pollution.

RESULTS

Short-term NO2 exposure was significantly related to an elevated risk of first-time outpatient visit due to acute exacerbations of DR-TB(relative risk:1.159, 95% confidence interval:1.011 ~ 1.329). Stratification analyses revealed that the relationship between the risk of acute exacerbations and NO2 exposure was stronger in the elderly (age ≥ 65) DR-TB patients, and in individuals with a history of TB treatment.

CONCLUSIONS

NO2 Exposure was significantly associated with an elevated risk of acute exacerbation of DR-TB in Anhui Province, China.

cAMP-PDE signaling in COPD: Review of cellular, molecular and clinical features

Chronic obstructive pulmonary disease (COPD) is the fourth leading cause of death among non-contagious diseases in the world. PDE inhibitors are among current medicines prescribed for COPD treatment of which, PDE-4 family is the predominant PDE isoform involved in hydrolyzing cyclic adenosine monophosphate (cAMP) that regulates the inflammatory responses in neutrophils, lymphocytes, macrophages and epithelial cells The aim of this study is to investigate the cellular and molecular mechanisms of cAMP-PDE signaling, as an important pathway in the treatment management of patients with COPD. In this review, a comprehensive literature review was performed about the effect of PDEs in COPD. Generally, PDEs are overexpressed in COPD patients, resulting in cAMP inactivation and decreased cAMP hydrolysis from AMP. At normal amounts, cAMP is one of the essential agents in regulating metabolism and suppressing inflammatory responses. Low amount of cAMP lead to activation of downstream inflammatory signaling pathways. PDE4 and PDE7 mRNA transcript levels were not altered in polymorphonuclear leukocytes and CD8 lymphocytes originating from the peripheral venous blood of stable COPD subjects compared to healthy controls. Therefore, cAMP-PDE signaling pathway is one of the most important signaling pathways involved in COPD. By examining the effects of different drugs in this signaling pathway critical steps can be taken in the treatment of this disease.

Cigarette smoke extract-induced downregulation of p300 is responsible for the impaired inflammatory cytokine response of macrophages

Patients with chronic obstructive pulmonary disease (COPD) are susceptible to infection owing to the impaired immune function of alveolar macrophages. This is presumed to be caused, at least partially, by cigarette smoke (CS), which is a major risk factor for COPD. Although CS has been reported to inhibit Toll-like receptor (TLR) function and phagocytosis in macrophages, the molecular mechanism of CS-mediated impairment of macrophage immune function has not been completely elucidated. We investigated the effects of CS extracts (CSE) on macrophage immune function and its molecular mechanism. We assessed lipopolysaccharide (LPS, TLR4 ligand)-, Pam3CSK4 (TLR2 ligand)-, or CpG-oligodeoxynucleotide (TLR9 ligand)-induced IL-6, TNF-α, and IL-1β production in macrophages. Upregulation of IL-6, TNF-α, and IL-1β mRNA and protein by TLR ligands was suppressed on treatment with CSE. However, LPS-induced MAP kinase activation, IκBα degradation, and nuclear translocation of NF-κB were not impeded by CSE. In contrast, CSE significantly suppressed NF-κB transcriptional activity in the nucleus. We found that p300, which acetylates RelA/p65 at lysine 310, and acetyl-p65 (K310) were downregulated upon CSE treatment. Knock-down of p300 suppressed LPS-induced acetylation of NF-κB p65 and production of inflammatory cytokine. To summarize, these results suggest that CSE impair cytokine response by decreasing the expression levels of p300.

The intake of maqui (Aristotelia chilensis) berry extract normalizes H2O2 and IL-6 concentrations in exhaled breath condensate from healthy smokers - an explorative study

BACKGROUND

Respiratory diseases are associated with pulmonary oxidative stress and inflammatory processes. Though studies in animal models suggest that dietary polyphenols improve lung injury, no intervention studies were carried out in humans. The aim of this study was to determine whether the intake of an anthocyanin-rich maqui extract improved H2O2 and IL-6 concentrations in exhaled breath condensates (EBCs) from asymptomatic smokers.

FINDINGS

15 asymptomatic smokers with mild cigarette smoking (3 pack-year [2.4 - 7.7]) (mean [CI95%]) were recruited in this exploratory longitudinal study. They ingested 2 g of maqui extract (polyphenol content = 5.18 ± 2.00 g GAE/100 g; FRAP value = 27.1 ± 2.0 mmol Fe(++)/100 g), twice daily for two weeks. EBCs were collected before and after treatment and the changes in H2O2 and IL-6 concentrations were determined by fluorimetry and Elisa, respectively. The EBC contents of H2O2 and IL-6 H2O2 before and after treatment in smokers were also compared with those determined in single EBC samples from 8 healthy non-smokers subjects. At baseline, the H2O2 concentrations were higher and those of IL-6 lower in the smokers than in the non-smokers. Maqui extract significantly decreased H2O2 (p < 0.0002) and increased IL-6 (p < 0.004) in the EBC from smokers. The EBC concentrations of H2O2 and IL-6 after maqui administration did not differ between smokers and non-smokers.

CONCLUSIONS

Maqui extract normalizes IL-6 and H2O2 concentrations in EBC from humans with mild smoking habits. If confirmed, these results suggest that dietary polyphenols might be considered as an interesting alternative for the dietary management of respiratory disorders.

[Tumor necrosis factor as an early marker of inflammation in healthy smokers]

BACKGROUND AND OBJECTIVES

Smoking creates an inflammation that leads to lose of lung function. Tumor necrosis factor alpha (TNF-α) is a cytokine that plays an important role in the pathogenesis of chronic obstructive pulmonary disease. There is a need to develop methods for an early detection of an impaired lung function in smokers. We aimed to show that smokers have higher levels of TNF-α in serum and exhaled breath condensate (EBC). We also analysed the influence of sex, age and weight on TNF-α, and determined the association between smoking, pulmonary function and TNF-α.

PATIENTS AND METHODS

Prospective study of smokers and non-smokers without any known disease. Respiratory function tests, EBC and blood samples were performed before smoking cessation.

STATISTICAL ANALYSIS

SPSS 11.0.

RESULTS

Fifty-one patients (60.8% smokers), 56.9% females, mean age 39.88 years old. Smokers initiated at an age of 15.77 years; the mean of cigarettes/day was 21.68. Significant differences in TNF-α serum levels between smokers and non-smokers were observed (P<.043). Differences did not reach significance for EBC. For tobacco consumption data, only age at smoking initiation and serum TNF-α levels had a correlation. A significant relation between TNF-α serum levels and forced expiratory volume in one second and forced vital capacity was found.

CONCLUSIONS

Smokers show higher TNF-α levels in serum. Number of years of smoking has an influence on TNF-α levels. There is a modest correlation between pulmonary function and plasma TNF-α levels, but not for EBC.

Inflammatory response of lung macrophages and epithelial cells to tobacco smoke: a literature review of ex vivo investigations

Chronic inflammation contributes to the initiation and progression of tumors and tobacco smoke-associated inflammation is associated with malignant and certain non-neoplastic lung diseases. Reported herein are the results of an interpretative synthesis review of the literature assessing the inflammatory response of lung macrophages (MPhi) and epithelial cells to tobacco smoke as measured ex vivo. Papers were retrieved using Boolean operations from PubMed and Scopus. Many writings reported the results of assays of human MPhi from fresh surgically excised human lung tissue, bronchoalveolar lavage, activated blood monocytes, long-term cell lines and MPhi from different laboratory animals. Some publications reported the findings of comparative studies of lung MPhi freshly isolated from the lungs of smokers and non-smokers. Other papers described the effect of tobacco smoke on lung epithelial cells. Most investigators quantified the response of the target cells to tobacco smoke by measuring the production of pro-inflammatory mediators; these included chemokines, cytokines, reactive oxygen species and enzymes. Investigators have reported conflicting observations of the response of human and animal MPhi and epithelial cells to tobacco smoke. The spectrum included papers describing robust production of various inflammatory mediators, significant reduction of a pro-inflammatory response to a known stimulant and overt cytotoxicity. This literature review documents that there exists no consensus, and no emerging trend line, of the reproducible effect(s) of cigarette smoke. This discrepancy reflects the absence of standardized protocols for collecting, processing and bioassaying the smoke, a highly complex aerosol, and identifies the need for establishing collaborative research schemes.

Signal transduction pathways linking the activation of alveolar macrophages with the recruitment of neutrophils to lungs in chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is a major and increasing global health problem. It is predicted by the World Health Organization to become the third most common cause of death and the fifth most common cause of disability in the world by 2020. COPD is a complex inflammatory disease involving several types of inflammatory cells and multiple inflammatory mediators. Although abnormal numbers of inflammatory cells such as macrophages, dendritic cells, neutrophils, and T lymphocytes have been documented in COPD, the relationship between these cell types and the sequence of their appearance and persistence is largely unknown. Alveolar macrophages have been identified as one of the major cell types that plays a key role in orchestrating the inflammatory events associated with the pathophysiology of COPD. One of the major functions of macrophages is the secretion of chemotactic factors and this function is markedly increased on exposure to cigarette smoke (CS). This enhanced release of chemoattractants results in increased lung neutrophil infiltration, which is thought to be a key event in the development of COPD. The molecular basis for this amplified inflammatory response is not very clear, but it could be due to an alteration in signal transduction pathways within the macrophage. Based on existing literature, an attempt has been made to create a comprehensive review of the signal transduction pathways that link the activation of macrophages with the increased recruitment of neutrophils into the airways. Some of the major stimuli that activate macrophages and cause them to secrete chemotactic factors have been identified as CS, wood smoke, ozone, bacterial endotoxin, and proinflammatory cytokines such as interleukin (IL)-1beta and tumor necrosis factor (TNF)-alpha. These stimuli seem to activate mainly redox-sensitive transcription factors such as nuclear factor (NF)-kappa B and activator protein (AP)-1, both of which play a major role in the synthesis and secretion of chemotactic factors such as IL-8 and leukotriene B(4) (LTB(4)). The pathways involved in the synthesis and secretion of other factors such as macrophage chemotactic protein-1 (MCP-1) and growth-related oncogene-alpha (Gro-alpha) have also been reviewed.

Outdoor Air Pollution: Nitrogen Dioxide, Sulfur Dioxide, and Carbon Monoxide Health Effects

Nitrogen dioxide (NO2), sulfur dioxide (SO2), and carbon monoxide are important ambient air pollutants. High-intensity, confined space exposure to NO2 has caused catastrophic injury to humans, including death. Ambient NO2 exposure may increase the risk of respiratory tract infections through the pollutant's interaction with the immune system. Sulfur dioxide (SO2) contributes to respiratory symptoms in both healthy patients and those with underlying pulmonary disease. Controlled human exposure studies have demonstrated that experimental SO2 exposure causes changes in airway physiology, including increased airways resistance. Both acute and chronic exposure to carbon monoxide are associated with increased risk for adverse cardiopulmonary events, including death. However, studies have not demonstrated a clear dose-dependent health risk response to increasing amounts of these pollutants except at high concentrations. In addition, a number of studies examining the effects of ambient level exposure to NO2, SO2, and CO have failed to find associations with adverse health outcomes.

Toll-like receptor 2 expression is decreased on alveolar macrophages in cigarette smokers and COPD patients

Backround

Cigarette smoke exposure including biologically active lipopolysaccharide (LPS) in the particulate phase of cigarette smoke induces activation of alveolar macrophages (AM) and alveolar epithelial cells leading to production of inflammatory mediators. This represents a crucial mechanism in the pathogenesis of chronic obstructive pulmonary disease (COPD). Respiratory pathogens are a major cause of exacerbations leading to recurrent cycles of injury and repair. The interaction between pathogen-associated molecular patterns and the host is mediated by pattern recognition receptors (PRR's). In the present study we characterized the expression of Toll-like receptor (TLR)- 2, TLR4 and CD14 on human AM compared to autologous monocytes obtained from patients with COPD, healthy smokers and non-smokers.

Methods

The study population consisted of 14 COPD patients without evidence for acute exacerbation, 10 healthy smokers and 17 healthy non-smokers stratified according to age. The expression of TLR2, TLR4 and CD14 surface molecules on human AM compared to autologous monocytes was assessed ex vivo using FACS analysis. In situ hybridization was performed on bronchoalveolar lavage (BAL) cells by application of the new developed HOPE-fixative.

Results

The expression of TLR2, TLR4 and CD14 on AM from COPD patients, smokers and non-smokers was reduced as compared to autologous monocytes. Comparing AM we detected a reduced expression of TLR2 in COPD patients and smokers. In addition TLR2 mRNA and protein expression was increased after LPS stimulation on non-smokers AM in contrast to smokers and COPD patients.

Conclusion

Our data suggest a smoke related change in the phenotype of AM's and the cellular response to microbial stimulation which may be associated with impairment of host defenses in the lower respiratory tract.

Cigarette smoke condensate induces MMP-12 gene expression in airway-like epithelia

Cigarette smoke (CS)-induced emphysema is attributable to matrix metalloproteinase-12 (MMP-12) in mice, however, a relationship between CS and MMP-12 is absent in human emphysema. Here, we show that cigarette smoke condensate (CSC) induces MMP-12 gene expression in airway-like epithelia through a hydrogen peroxide (H(2)O(2))-dependent pathway involving NADPH oxidase, AP-1, and TNF-alpha. Cigarette smoke condensate-induced H(2)O(2) production and MMP-12 gene expression were inhibited by apocynin, a specific inhibitor of NADPH oxidases, while 3-aminobenzamide, an inhibitor of AP-1, attenuated CSC-induced MMP-12 gene expression. Messenger RNAs encoding phagocytic NADPH oxidase components and a homologue of p67phox, p51 (NOXA1), were detected, while mRNA of dual oxidase (Duox)1 was unchanged by CSC. Enbrel, an inhibitor of TNF-alpha function, reduced CSC-induced H(2)O(2) production and MMP-12 expression. These findings provide novel evidence of a direct relationship between CS exposure and MMP-12 in human airway epithelia and suggest several targets for modulation of this potentially pathogenic pathway.

Primary Human Alveolar Type II Epithelial Cell Chemokine Release

An early response to cigarette smoke is an influx of leukocytes into the lung. Alveolar epithelial type II (ATII) cells may contribute by releasing chemokines in response to cigarette smoke and neutrophil elastase (NE). Human ATII cells were purified from normal regions of lungs resected for carcinoma (n = 14). In vitro, these cells exhibited ATII cell characteristics: lamellar bodies, apical microvilli, tight junctions, and expressed surfactant apoprotein C. Basal ATII cell release of five chemokines ranked as follows: monocyte chemotactic protein (MCP)-1 > interleukin (IL)-8 > growth-related oncogene (GRO)-alpha > macrophage inflammatory protein (MIP)-1alpha > regulated on activation, normal T cell expressed and secreted (RANTES). MIP-1alpha and RANTES were often not detectable. After stimulation with a mixture of lipopolysaccharide/endotoxin (LPS), tumor necrosis factor-alpha, IL-1beta, and IFN-gamma, MCP-1 and IL-8 secretion rose 4-6-fold, whereas GRO-alpha rose 25-fold. NE stimulated IL-8 mRNA expression, and 10nM NE stimulated IL-8 secretion; however, 100 nM NE caused a decrease in extracellular IL-8, MCP-1, and GRO-alpha, attributed to proteolysis. Cigarette smoke extract (CSE) inhibited IL-8 mRNA expression and release of all chemokines. Glutathione protected against the effects of CSE, suggesting oxidative mechanisms. GRO-alpha, important in growth and repair, was sensitive to both stimulation, by LPS:cytokines, and inhibition, by CSE. Thus, contrary to the original hypothesis, high concentrations of NE and CSE resulted in reduced extracellular chemokine levels. We hypothesize that reduced ATII cell-derived chemokine levels compromise alveolar repair, contributing to cigarette smoke-induced alveolar damage and emphysema.

Markers of Inflammation in Exhaled Breath Condensate of Young Healthy Smokers

INTRODUCTION

Although a strong correlation exists between long-term cigarette smoking, pulmonary inflammation, and COPD, efforts to identify populations at risk of acquiring COPD have so far been unsuccessful. To this end, noninvasive detection and monitoring of biomarkers of pulmonary inflammation in young healthy smokers may assist in this task.

STUDY OBJECTIVES

The purpose of this study was to determine the concentrations of total protein, nitrites, interleukin (IL)-1beta, and tumor necrosis factor (TNF)-alpha, and neutrophil chemotactic activity in exhaled breath condensate (EBC) collected from healthy college student smokers and nonsmokers.

DESIGN

EBC was collected from 20 volunteers (9 nonsmokers and 11 smokers) during tidal breathing for 20 min. EBC was also collected from smokers 30 min after smoking one filtered cigarette. The concentrations of total protein, nitrite, IL-1beta, and TNF-alpha in EBC was determined by enzyme-linked immunosorbent assay. Neutrophil chemotactic activity in EBC was determined in vitro using the blind-well technique.

RESULTS

The concentrations of total protein and nitrite, and neutrophil chemotactic activity were significantly higher in EBC of smokers in comparison to nonsmokers (p < 0.05). The concentrations of total protein and nitrite in the condensate of smokers did not change significantly after smoking one cigarette. The concentrations of IL-1beta and TNF-alpha in EBC were similar in nonsmokers and smokers.

CONCLUSIONS

Concentrations of certain inflammatory mediators and neutrophil chemotactic activity are increased in EBC of young healthy smokers. Collection and analysis of EBC may assist in early detection of cigarette smoke-induced pulmonary inflammation and identifying populations at risk for acquiring COPD.

Tumor necrosis factor-alpha is central to acute cigarette smoke-induced inflammation and connective tissue breakdown

The role of tumor necrosis factor-alpha (TNF-alpha) as a mediator of cigarette smoke-induced disease is controversial. We exposed mice with knocked-out p55/p75 TNF-alpha receptors (TNF-alpha-RKO mice) to cigarette smoke and compared them with control mice. Two hours after smoke exposure, increases in gene expression of TNF-alpha, neutrophil chemoattractant, macrophage inflammatory protein-2, and macrophage chemoattractant, protein-1 were seen in control mice. By 6 hours, TNF-alpha, macrophage inflammatory protein-2, and macrophage chemoattractant protein-1 gene expression levels had returned to control values in control mice and stayed at control values through 24 hours. In TNF-alpha-RKO mice, no changes in gene expression of these mediators were seen at any time. At 24 hours, control mice demonstrated increases in lavage neutrophils, macrophages, desmosine (a measure of elastin breakdown), and hydroxyproline (a measure of collagen breakdown), whereas TNF-alpha-RKO mice did not. In separate experiments, pure strain 129 mice, which produce low levels of TNF-alpha, showed no inflammatory response to smoke at 24 hours or 7 days. We conclude that TNF-alpha is central to acute smoke-induced inflammation and resulting connective tissue breakdown, the precursor of emphysema. The findings support the idea that TNF-alpha promoter polymorphisms may be of importance in determining who develops smoke-induced chronic obstructive pulmonary disease.

Macrophages and the pathogenesis of COPD

Macrophages are long-lived effector cells within the lung. They are reactive, responding to endogenous and exogenous stimuli, as well as proactive, producing mediators that modulate the behavior of surrounding cells. In addition, they play a critical role in the clearance of apoptotic neutrophils. Their role in COPD probably reflects a number of functional properties. However, if the link between increased proteinase burden and tissue destruction and injury in patients with COPD is correct, then macrophages must be very significant. Even though other cells, including epithelial cells and fibroblasts, have been shown to express higher matrix metalloproteinase (MMP) levels in lung tissue from subjects with COPD and emphysema, the numbers of resident cells do not appear to increase by the same factor as that of sequestered macrophages. The combination of a 5- to 10-fold increase in macrophage numbers, the up-regulation of MMPs, and their co-release with other classes of stored proteinases must be highly significant in terms of an increase in proteinase potential in the small airways and respiratory units. This may account for increased tissue destruction and inflammatory mediator activation leading to the pathology that occurs during COPD. Since only about 15% of smokers develop clinically significant disease, it seems likely, in smokers without COPD, that these processes either are strictly controlled or that lung repair mechanisms are more effective.

Acute effects of smoke exposure on the cellular and cytokine profile in isolated perfused lungs

The aim of this study was to assess the acute effects of cigarette smoke exposure on cellular and cytokine profile in BAL fluids in an isolated perfused rabbit assay. The experimental animals were categorized into four groups: (1) unexposed controls and (2) cigarette smoke-exposed animals perfused with autologous whole blood; (3) unexposed controls and cigarette smoke-exposed; (4) cigarette smoke-exposed animals perfused with Krebs' Ringer solution containing 5% bovine serum albumin and glucose. Cigarette smoke induced an increase in total cell numbers (mainly alveolar macrophages in BAL fluids) and an increase in the permeability index of BAL. Levels of interleukin 8 were also significantly decreased in BAL fluids due to acute effects of cigarette smoke exposure. The most likely explanation for cigarette smoke-induced increase of inflammatory cells in BAL in lungs is because of the release of pre-existing cells from reservoirs within the lungs. The acute effects of cigarette smoke-induced increase of pulmonary epithelial permeability may also play an important role in the cellular recruitment into airspaces from the lung reservoirs.

Effect of nitrogen dioxide on respiratory viral infection in airway epithelial cells

Nitrogen dioxide (NO(2)) is a common air pollutant outdoors and indoors in homes with unvented combustion sources. It is also a constituent of tobacco smoke. Epidemiological studies suggest that children exposed to NO(2), or living with smoking parents, have an increased incidence of respiratory viral infections. The most common virus causing severe respiratory symptoms in infants and young children is respiratory syncytial virus (RSV). In the present study we investigated whether NO(2) exposure affects RSV infection in airway epithelial cells, the host cells for viral replication and virus-induced cytokine production. Cultures of the bronchial epithelial cell line BEAS-2B exposed to 0.5, 1.0, and 1.5 ppm NO(2) for 60 min were infected with RSV. Viral replication, as well as RSV-induced interleukin (IL)-6 and IL-8, was assessed at various times postinfection. The NO(2) doses used were not toxic to the BEAS-2B cells as measured by release of lactic dehydrogenase (LDH). The internalization of RSV was increased by exposure to 0.5 ppm NO(2) and decreased by exposure to 1.5 ppm NO(2). On the other hand, the release of infectious virus 48 h postexposure was not affected by the two lower doses of NO(2), but was significantly reduced in cells exposed to 1.5 ppm NO(2). Virus-induced cytokine production was also significantly reduced in cells exposed to 1.5 ppm NO(2), and not affected by 0.5 and 1.0 ppm. It is likely that the decrease in cytokine production is related to the decrease in viral burden. These data suggest that possible increases in viral clinical symptoms associated with NO(2) may not be caused by increased susceptibility of the epithelial cells to infection but may result from effects of NO(2) on host defenses that prevent the spread of virus.