Tobacco Smoking and Environmental Risk Factors for Chronic Obstructive Pulmonary Disease

Epidemiological evidence relating environmental smoke to COPD in lifelong non-smokers: a systematic review

Background: Some evidence suggests environmental tobacco smoke (ETS) might cause chronic obstructive pulmonary disease (COPD). We reviewed available epidemiological data in never smokers. Methods: We identified epidemiological studies providing estimates of relative risk (RR) with 95% confidence interval (CI) for various ETS exposure indices. Confounder-adjusted RRs for COPD were extracted, or derived using standard methods. Meta-analyses were conducted for each exposure index, with tests for heterogeneity and publication bias. For the main index (spouse ever smoked or nearest equivalent), analyses investigated variation in RR by location, publication period, study type, sex, diagnosis, study size, confounder adjustment, never smoker definition, and exposure index definition. Results: Twenty-eight relevant studies were identified; nine European or Middle Eastern, nine Asian, eight American and two from multiple countries. Five were prospective, seven case-control and 16 cross-sectional. The COPD definition involved death or hospitalisation in seven studies, GOLD stage 1+ criteria in twelve, and other definitions in nine. For the main index, random-effects meta-analysis of 33 heterogeneous (p<0.001) estimates gave a RR of 1.20 (95%CI 1.08-1.34). Higher estimates for females (1.59,1.16-2.19, n=11) than males (1.29,0.94-1.76, n=7) or sexes combined (1.10,0.99-1.22, n=15 where sex-specific not available), and lower estimates for studies of 150+ cases (1.08,0.97-1.20, n=13) partly explained the heterogeneity. Estimates were higher for Asian studies (1.34,1.08-1.67, n=10), case-control studies (1.55,1.04-2.32, n=8), and COPD mortality or hospitalisation (1.40,1.12-1.74, n=11). Some increase was seen for severer COPD (1.29,1.10-1.52, n=7). Dose-response evidence was heterogeneous. Evidence for childhood (0.88,0.72-1.07, n=2) and workplace (1.12,0.77-1.64, n=4) exposure was limited, but an increase was seen for overall adulthood exposure (1.20,1.03-1.39, n=17). We discuss study weaknesses that may bias estimation of the association of COPD with ETS. Conclusions: Although the evidence suggests ETS increases COPD, study weaknesses and absence of well-designed large studies precludes reliable inference of causality. More definitive evidence is required.

Tanshinone IIA sulfonate protects against cigarette smoke-induced COPD and down-regulation of CFTR in mice

Chronic obstructive pulmonary disease (COPD) is a chronic lung disease characterized by abnormal inflammation, persistent and progressive lung function decline. The anti-inflammatory actions of tanshinone IIA, which is the most important active component from Chinese herbal medicine Danshen, have been well studied. However, it remains unknown whether sodium tanshinone IIA sulfonate (STS) protects against the development of COPD. Here we found that STS inhalation (5 mg/kg, 30 min per session, twice a day) significantly attenuated lung function decline, airspace enlargement, mucus production, bronchial collagen deposition, inflammatory responses and oxidative stress caused by cigarette smoke (CS) and lipopolysaccharide (LPS) exposures in mice. Moreover, treatment with STS (10 μg/ml) reduced CS extract (CSE)-induced IL-6 and IL-8 secretion in human bronchial epithelial (16HBE) cells. The anti-inflammatory actions of STS were associated with inhibition of ERK1/2 and NF-κB activations. Interestingly, STS inhibited CS-induced reduction of cystic fibrosis transmembrane conductance regulator (CFTR) in mouse lungs and in 16HBE cells. Treatment with a specific CFTR inhibitor CFTR-Inh172 augmented CSE-induced ERK1/2 and NF-κB-dependent inflammatory responses, but abolished the inhibitory action of STS on IL-6 and IL-8 secretion in 16HBE cells. These results demonstrate that CS-induced COPD and down-regulation of CFTR are prevented by STS.

Atopy Is Associated with Age at Asthma Onset in Elderly Patients

BACKGROUND

Asthma in the elderly population (60 years of age and older) is frequently underdiagnosed, as well as atopy. Atopy, although more prevalent in younger patients, can be a major cause of asthma in the elderly. Chronic obstructive pulmonary disease (COPD) and cardiovascular disease are common differential diagnoses, especially in elderly smokers.

OBJECTIVE

The objective of this study was to assess atopy and comorbidities in elderly patients with asthma.

METHODS

This was an observational and retrospective study involving elderly asthmatic patients followed up at a tertiary center. Patients were assessed for severity of asthma, frequency of atopy, and frequency of comorbidities concomitant with asthma. Then, they were classified according to their age at asthma onset and the groups compared with each other for atopy, spirometric parameters, and comorbidities.

RESULTS

This study included 243 elderly asthmatic patients, 71.8% of them presenting severe disease and 82.3% forced expiratory volume in 1 second (FEV₁) < 80%. Gastroesophageal reflux disease, obesity, and asthma-COPD overlap syndrome were observed, respectively, in 64%, 37%, and 13% of these patients. Atopy was observed in 63%, mainly in those with early onset disease, and its frequency decreased as the age of asthma onset increased (P < .05). Total serum IgE was higher for allergic patients and FEV₁ values were lower for patients with long-term asthma. Aspirin-exacerbated respiratory disease was more frequent in patients with nonallergic asthma.

CONCLUSIONS

Most elderly asthmatic patients followed up in our tertiary center were atopic and higher values of total serum IgE suggest atopy. Atopy was inversely correlated with age of asthma onset. The diagnosis of allergic asthma in the elderly population is essential to treat patients more properly, improving their quality of life and decreasing asthma morbidity and mortality.

Spirometry is not enough to diagnose COPD in epidemiological studies: a follow-up study

A hallmark of the diagnosis of chronic obstructive pulmonary disease (COPD) is the measurement of post-bronchodilator (post-BD) airflow obstruction (AO) by spirometry, but spirometry is not enough for the provision of a clinical diagnosis. In the majority of previous epidemiological studies, COPD diagnosis has been based on spirometry and a few clinical characteristics. The aim of our study was to identify outcomes in patients newly diagnosed with airflow obstruction (AO) based on a diagnostic work-up conducted as part of a population-based cross-sectional study in North-Western Russia. Spirometry was performed before (pre-BD) and after BD administration, and AO was defined using the FEV1/FVC <0.70 and FEV1/FVC Collapse

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MESH Headings

• Bronchodilator Agents/therapeutic use
• Cross-Sectional Studies
• Female
• Follow-Up Studies
• Forced Expiratory Volume/drug effects
• Humans
• Male
• Middle Aged
• Pulmonary Disease, Chronic Obstructive/diagnosis
• Pulmonary Disease, Chronic Obstructive/drug therapy
• Pulmonary Disease, Chronic Obstructive/epidemiology
• Russia/epidemiology
• Spirometry
• Vital Capacity/drug effects

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Affiliation(s)

Elena Andreeva Institute of Health and Society, Université Catholique de Louvain, IRSS, Clos Chapelle-aux-Champs, 30/10.15, 1200, Brussels, Belgium Department of Family Medicine, Northern State Medical University, pr. Troitsky, 51, 163000, Arkhangelsk, Russia
Marina Pokhaznikova Department of Family Medicine, North-Western State Medical University named after I.I. Mechnikov, Kirochnaya str., 41, 191015, St. Petersburg, Russia
Anatoly Lebedev Department of Family Medicine, North-Western State Medical University named after I.I. Mechnikov, Kirochnaya str., 41, 191015, St. Petersburg, Russia
Irina Moiseeva Department of Family Medicine, North-Western State Medical University named after I.I. Mechnikov, Kirochnaya str., 41, 191015, St. Petersburg, Russia
Olga Kuznetsova Department of Family Medicine, North-Western State Medical University named after I.I. Mechnikov, Kirochnaya str., 41, 191015, St. Petersburg, Russia
Jean-Marie Degryse Institute of Health and Society, Université Catholique de Louvain, IRSS, Clos Chapelle-aux-Champs, 30/10.15, 1200, Brussels, Belgium. Department of Public Health and Primary Health Care, K.U.Leuven, Kapucijnenvoer 33, B3000, Leuven, Belgium.

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Associations between occupational inhalation risks and FeNO levels in airway obstruction patients: results from the National Health and Nutrition Examination Survey, 2007-2012

Purpose

To investigate associations between occupational inhalation risks and fractional exhaled nitric oxide (FeNO) levels in patients with chronic obstructive pulmonary disease (COPD).

Patients and methods

Data of 16,486 subjects who had undergone spirometry with pre-bronchodilator and post-bronchodilator lung function assessment were retrieved from the National Health and Nutrition Examination Survey, 2007–2012 database. After excluding 2,638 subjects with missing spirometry values, data of 13,336 subjects were included for analysis. Factors associated with occupational inhalation, FeNO levels and COPD were analyzed using logistic regression analysis.

Results

COPD was associated with occupational exposures to mineral dusts, organic dusts, exhaust fumes, other fumes, and second-hand smoking (P<0.05). Long-term exposure to these occupational hazards carried significantly higher risk for subjects with COPD than for controls (crude odds ratios [ORs]: mineral dusts: 2.364, organic dusts: 2.427, exhaust fumes: 2.728, other fumes: 2.144). In subgroup analysis, COPD correlated positively with long-term exposures to organic dusts and exhaust fumes in subjects with FeNO ≤50 ppb (ORs 1.361 and 1.314, respectively); conversely, COPD correlated negatively with intermediate to long-term exposures to organic dusts and exhaust fumes in those with FeNO >50 ppb (ORs 0.058 and 0.210, respectively).

Conclusion

Occupational exposures to airborne pollutants carries higher risk of COPD than non-exposure and the risk is higher the longer the duration of exposure. Exposure–response relationships are inconsistent in subjects with suspected asthmatic airway inflammation (FeNO ≥50 ppb). More careful risk assessment is needed in occupational inhalation exposure, since COPD with asthmatic airway inflammation, or asthma-COPD overlapping syndrome, may have the distinguishing features of both COPD and asthma.

Cigarette smoke extract induced exosome release is mediated by depletion of exofacial thiols and can be inhibited by thiol-antioxidants

INTRODUCTION

Airway epithelial cells have been described to release extracellular vesicles (EVs) with pathological properties when exposed to cigarette smoke extract (CSE). As CSE causes oxidative stress, we investigated whether its oxidative components are responsible for inducing EV release and whether this could be prevented using the thiol antioxidants N-acetyl-l-cysteine (NAC) or glutathione (GSH).

METHODS

BEAS-2B cells were exposed for 24h to CSE, H₂O₂, acrolein, 5,5'-dithiobis-(2-nitrobenzoic acid) (DTNB), bacitracin, rutin or the anti-protein disulfide isomerase (PDI) antibody clone RL90; with or without NAC or GSH. EVs in media were measured using CD63⁺CD81⁺ bead-coupled flow cytometry or tunable resistive pulse sensing (TRPS). For characterization by Western Blotting, cryo-transmission electron microscopy and TRPS, EVs were isolated using ultracentrifugation. Glutathione disulfide and GSH in cells were assessed by a GSH reductase cycling assay, and exofacial thiols using Flow cytometry.

RESULTS

CSE augmented the release of the EV subtype exosomes, which could be prevented by scavenging thiol-reactive components using NAC or GSH. Among thiol-reactive CSE components, H₂O₂ had no effect on exosome release, whereas acrolein imitated the NAC-reversible exosome induction. The exosome induction by CSE and acrolein was paralleled by depletion of cell surface thiols. Membrane impermeable thiol blocking agents, but not specific inhibitors of the exofacially located thiol-dependent enzyme PDI, stimulated exosome release.

SUMMARY/CONCLUSION

Thiol-reactive compounds like acrolein account for CSE-induced exosome release by reacting with cell surface thiols. As acrolein is produced endogenously during inflammation, it may influence exosome release not only in smokers, but also in ex-smokers with chronic obstructive pulmonary disease. NAC and GSH prevent acrolein- and CSE-induced exosome release, which may contribute to the clinical benefits of NAC treatment.

Serum cytokine levels related to exposure to volatile organic compounds and PM2.5 in dwellings and workplaces in French farmers - a mechanism to explain nonsmoking COPD

Although French farmers smoke less on average than individuals from the general population, they suffer more from COPD. Exposure to biological and chemical air pollutants in the farm may be the cause of these higher COPD rates. This study investigates the role of bio-contaminants, including the relationship of exposure to volatile organic compounds (VOCs) and fine particulate matter (of diameter of 2.5 µm [PM_2.5]) objectively measured in the farm settings (dwellings and workplaces) to serum cytokines involved in COPD, in a sample of 72 farmers from 50 farms in the Auvergne region, France. Mean concentrations of VOCs were highest inside the home, while levels of PM_2.5 were highest in workplaces (stables and granaries). After adjusting for confounders, high exposure to PM_2.5 was significantly associated with a decreased level of serum cytokines (among others, IL13: β: −0.94, CI: −1.5 to −0.2, P-value =0.004; IL8: β: −0.82, CI: −1.4 to −0.2, P-value =0.005) and high exposure to VOCs according to a VOC global score with a decreased IL13 level (β: −0.5, CI: −0.9 to −0.1, P-value =0.01). Moreover, respiratory symptoms and diseases, including COPD, were associated with a decreased level of serum cytokines significantly in the case of IL5. An alteration of immune response balance in terms of cytokine levels in relation to indoor chemical air pollution exposure may contribute to respiratory health impairment in farmers.

Repression of Toll-like receptor-4 by microRNA-149-3p is associated with smoking-related COPD

Background

Smoking is the leading cause of COPD. Exploring molecular markers and understanding the pathogenic mechanisms of smoking-related COPD are helpful for early clinical diagnosis and treatment of the disease. This study aims to identify specific circulating microRNAs (miRNAs) from the blood of COPD patients with a long history of smoking.

Methods

Blood samples from four different groups were collected, and miRNA microarray was performed. Differential expression of miRNAs was verified by quantitative polymerase chain reaction. In vitro, THP-1 cells were cultured and stimulated with cigarette smoke extract (CSE) or transfected with miR-149-3p inhibitor/mimics. Protein levels of Toll-like receptor 4 (TLR-4) and nuclear factor κB (NF-κB) were detected using Western blot and immunofluorescence. Interleukin (IL)-1β and tumor necrosis factor (TNF)-α levels were determined by an enzyme-linked immunosorbent assay.

Results

miRNA profiling revealed that the expression of 56 miRNAs was changed between the four groups. Expression of miR-149-3p in group C (non-smoker non-COPD) was higher than in group S (smoker non-COPD), S-COPD (smoker with stable COPD) and AE-COPD (smoker with acute exacerbation COPD). CSE stimulation down-regulated the expression of miR-149-3p and up-regulated the TLR-4 and NF-κB levels in THP-1 cells. Transfecting miR-149-3p inhibitors in THP-1 cells also increased the expression of its target genes. Furthermore, overexpression of miR-149-3p inhibited the TLR-4/NF-κB signaling pathways and reduced the secretion of IL-1β and TNF-α.

Conclusion

This study found that smoking can induce differential expression of circulating miR-NAs, such as down-regulation of miR-149-3p. Reducing miR-149-3p may increase the inflammatory response in COPD patients through the regulation of the TLR-4/NF-κB signaling pathway.

Occupational and Biomass Exposure in Chronic Obstructive Pulmonary Disease: Results of a Cross-Sectional Analysis of the On-Sint Study

BACKGROUND

Although tobacco smoke is the main risk factor for chronic obstructive pulmonary disease (COPD), other inhaled toxics have also been associated with the disease. The present study analyzes data from exposure to these substances in a cohort of patients with COPD and assesses their impact on the clinical presentation of the disease.

METHODS

This is a cross-sectional analysis of the Clinical presentation, diagnosis and course of chronic obstructive pulmonary disease (On-Sint) study. All patients were smokers or ex-smokers as per protocol. In addition, during the inclusion visit patients were enquired about their occupational and biomass exposure history. The clinical features of patients with and without an added risk factor to tobacco were compared and those significant were entered in a multivariate logistic regression analysis, expressed as odds ratio (OR).

RESULTS

The sample size was 1214 patients with COPD, of which 1012 (83.4%) had tobacco as the only risk factor and 202 (16.6%) had additional ones, mainly 174 (14.3%) with occupational gases and 32 (2.6%) with biomass exposure. The geographical distribution of this exposure showed a preference for the northern parts of the country and the East coast. The biomass exposure was rather low. Male gender (OR: 2.180), CAT score (OR: 1.036) and the use of long-term oxygen therapy (OR: 1.642) were associated with having an additional risk factor in the multivariate analysis.

CONCLUSIONS

Occupational exposures are more common than biomass in Spain. COPD caused by tobacco plus other inhalants has some differential features and a more impaired quality of life.

Evaluation of Individuals at Risk for COPD: Beyond the Scope of the Global Initiative for Chronic Obstructive Lung Disease

The Global initiative for chronic Obstructive Lung Disease (GOLD) Strategy is a valuable tool for clinicians in the diagnosis and management of patients with established chronic obstructive pulmonary disease (COPD). However, there are no recommendations for the evaluation of individuals, exposed to risk factors, who are most likely to develop COPD. Consequently, it is necessary to consider all of the factors that may play a role in the pathogenesis of COPD: genetic factors, gender, socioeconomic status, disadvantageous factors in childhood, lung diseases and exposure to risk factors such as smoking, biomass fuel smoke, occupational hazards and air pollution. Along with the clinical assessment, periodic spirometry should be performed to evaluate lung function and make possible early detection of individuals who will develop the disease through the rate of forced expiratory volume in 1 second (FEV₁) decline. The first spirometry, periodicity, and clinically significant decline in FEV₁ will encompass the cornerstones of clinical follow up. This approach allows the implementation of important interventions in order to help individuals to cease contact with risk factors and prevent progressive respiratory impairment with the consequent deterioration of quality of life and increased morbidity and mortality.

Macrophages, Inflammation, and Lung Cancer

Lung cancer is the leading cause of cancer mortality worldwide, and at only 18%, it has one of the lowest 5-year survival rates of all malignancies. With its highly complex mutational landscape, treatment strategies against lung cancer have proved largely ineffective. However with the recent success of immunotherapy trials in lung cancer, there is renewed enthusiasm in targeting the immune component of tumors. Macrophages make up the majority of the immune infiltrate in tumors and are a key cell type linking inflammation and cancer. Although the mechanisms through which inflammation promotes cancer are not fully understood, two connected hypotheses have emerged: an intrinsic pathway, driven by genetic alterations that lead to neoplasia and inflammation, and an extrinsic pathway, driven by inflammatory conditions that increase cancer risk. Here, we discuss the contribution of macrophages to these pathways and subsequently their roles in established tumors. We highlight studies investigating the association of macrophages with lung cancer prognosis and discuss emerging therapeutic strategies for targeting macrophages in the tumor microenvironment.

Inflammatory bowel disease and risk of mortality in COPD

Patients with chronic obstructive pulmonary disease (COPD) have higher incidence and prevalence of other chronic inflammatory diseases, including inflammatory bowel disease (IBD). We assessed whether IBD onset increases mortality risk in patients with COPD or asthma-associated COPD.Two population-based cohorts of COPD and asthma-COPD subjects were identified using the administrative health databases in Québec, Canada, 1990-2007. Death records were retrieved from the death certificate registry. Cox proportional hazards models were used to assess the impact of newly developed IBD on mortality risk.The COPD and asthma-COPD cohorts included 273 208 and 26 575 patients, respectively, of which 697 and 119 developed IBD. IBD increased the risk of all-cause mortality in both COPD (hazard ratio 1.23, 95% CI 1.09-1.4) and asthma-COPD (hazard ratio 1.65, 95% CI 1.23-2.22). In asthma-COPD patients, IBD increased the risk of mortality from respiratory conditions (hazard ratio 2.18, 95% CI 1.31-3.64); in COPD patients, IBD increased the risk of death from digestive conditions (hazard ratio 4.45, 95% CI 2.39-8.30).IBD is a risk factor for mortality in patients with pre-existing COPD or asthma-COPD. IBD increased mortality by respiratory and digestive conditions in patients with asthma-COPD and COPD, respectively.

The Role of Innate and Adaptive Immune Cells in the Immunopathogenesis of Chronic Obstructive Pulmonary Disease

Chronic obstructive pulmonary disease (COPD) is a chronic and progressive inflammatory disease of the airways and lungs that results in limitations of continuous airflow and is caused by exposure to noxious gasses and particles. A major cause of morbidity and mortality in adults, COPD is a complex disease pathologically mediated by many inflammatory pathways. Macrophages, neutrophils, dendritic cells, and CD8+ T-lymphocytes are the key inflammatory cells involved in COPD. Recently, the non-coding small RNA, micro-RNA, have also been intensively investigated and evidence suggest that it plays a role in the pathogenesis of COPD. Here, we discuss the accumulated evidence that has since revealed the role of each inflammatory cell and their involvement in the immunopathogenesis of COPD. Mechanisms of steroid resistance in COPD will also be briefly discussed.

Association between glutathione S-transferase P1 Ile (105) Val gene polymorphism and chronic obstructive pulmonary disease: A meta-analysis based on seventeen case-control studies

INTRODUCTION

Previous studies have shown that glutathione S-transferase P1 (GSTP1) was associated with chronic obstructive pulmonary disease (COPD). However, the association between GSTP1 Ile (105) Val gene polymorphism and COPD remains controversial. To drive a more precise estimation, we performed a meta-analysis based on published case-control studies.

METHODS

An electronic search of PubMed, EMBASE, Cochrane library, Web of Science and China Knowledge Resource Integrated (CNKI) Database for papers on GSTP1 Ile (105) Val gene polymorphism and COPD risk was performed. The pooled odds ratios (ORs) with 95% confidence intervals (CIs) were used to assess the strength of association in the homozygote model, heterozygote model, dominant model, recessive model and an additive mode. Statistical heterogeneity, test of publication bias and sensitivity analysis was performed. The software STATA (Version 13.0) was used data analysis.

RESULTS

Overall, seventeen studies with 1892 cases and 2012 controls were included in this meta-analysis. The GSTP1 Ile (105) Val polymorphism showed pooled odds ratios for the homozygote comparison (OR = 1.501, 95%CI [0.862, 2.614]), heterozygote comparison (OR = 0.924, 95%CI [0.733, 1.165]), dominant model (OR = 1.003, 95%CI [0.756, 1.331]), recessive model (OR = 1.510, 95%CI [0.934, 2.439]), and an additive model (OR = 1.072, 95%CI [0.822, 1.398]).

CONCLUSIONS

In conclusion, the current meta-analysis, based on the most updated information, showed no significant association between GSTP1 Ile (105) Val gene polymorphism and COPD risk in any genetic models. The results of subgroup analysis also showed no significant association between GSTP1 Ile (105) Val gene polymorphism and COPD risk in Asian population and Caucasian population. Further studies involving large populations and careful control with age, sex, ethnicity, and cigarette smoking are greatly needed.

Prevalence and risk factors for COPD in farmers: a cross-sectional controlled study

There are conflicting data regarding the magnitude and determinants of chronic obstructive pulmonary disease (COPD) risk in farmers.In a cross-sectional study of 917 nonfarming working controls and 3787 farmers aged 40-75 years, we assessed respiratory symptoms, tobacco exposure, job history (without direct exposure measurement) and lung function. COPD was defined by the Global Initiative for Chronic Obstructive Lung Disease (GOLD) criterion (post-bronchodilator forced expiratory volume in 1 s (FEV1)/forced vital capacity (FVC) <0.70) and by the Quanjer reference equation (post-bronchodilator FEV1/FVC <lower limit of normal (LLN)).The prevalence (95% CI) of COPD according to the GOLD criterion was 5.1% (4.4-5.8%) and 2.9% (1.8-4.0%) in farmers and controls, respectively (p=0.005), and 3.1% (2.5-3.6%) and 1.5% (0.7-2.3%), respectively, for the LLN criterion (p<0.01). For both COPD criteria after adjustment for age, sex and smoking status, COPD prevalence was similar in controls and crop farmers. Compared to controls, four job categories had a higher prevalence of COPD according to the GOLD criterion, namely, cattle breeders, swine breeders, poultry breeders and breeders of two or more livestock types. Among cattle breeders, only those from Franche-Comté had higher prevalence of COPD according to both GOLD and LLN criteria.The prevalence of COPD in farmers is higher than in nonfarming working controls, and depends on the farming activity, the region and the criterion used to define COPD.

Nanoparticulate carbon black in cigarette smoke induces DNA cleavage and Th17-mediated emphysema

Chronic inhalation of cigarette smoke is the major cause of sterile inflammation and pulmonary emphysema. The effect of carbon black (CB), a universal constituent of smoke derived from the incomplete combustion of organic material, in smokers and non-smokers is less known. In this study, we show that insoluble nanoparticulate carbon black (nCB) accumulates in human myeloid dendritic cells (mDCs) from emphysematous lung and in CD11c⁺ lung antigen presenting cells (APC) of mice exposed to smoke. Likewise, nCB intranasal administration induced emphysema in mouse lungs. Delivered by smoking or intranasally, nCB persisted indefinitely in mouse lung, activated lung APCs, and promoted T helper 17 cell differentiation through double-stranded DNA break (DSB) and ASC-mediated inflammasome assembly in phagocytes. Increasing the polarity or size of CB mitigated many adverse effects. Thus, nCB causes sterile inflammation, DSB, and emphysema and explains adverse health outcomes seen in smokers while implicating the dangers of nCB exposure in non-smokers.

DOI:http://dx.doi.org/10.7554/eLife.09623.001

Smoking for many years damages the lungs and leads to a disease called emphysema that makes it difficult to breathe and is often deadly. There are thousands of chemicals in cigarette smoke and many of them have been linked to the development of lung cancer, although it has been difficult to pinpoint those that are responsible for smoking-related emphysema. Moreover, cigarette smoke also contains large numbers of small particles and relatively little is known about the role played by these particles in smoking-related disease.

One of the hallmarks of long-term smoking is a blackening of the lung tissue that persists even if someone stops smoking. Previously, little was known about the composition of the substance that causes this blackening, or its significance in the development of emphysema. Now, by studying lung tissue taken from smokers with emphysema, You et al. have shown that this black substance is made of nano-sized particles of a material called carbon black (which is also known as elemental carbon). These nanoparticles are produced by the incomplete combustion of the cigarettes. You et al. also confirmed that nanoparticles of carbon black can cause emphysema in mice.

Closer examination of the lung damage caused by the nanoparticles revealed that they trigger breakages in DNA, which leads to inflammation of the lung. And because the nanoparticles cannot be cleared, they are released into the lung when cells die, which perpetuates lung inflammation and damage.

You et al. then went on to show that nanoparticles of carbon black can be modified in a way that allows them to be cleared from the lungs. Such modifications could potentially protect people who are exposed to carbon black nanoparticles in the environment or in workplaces where carbon black is used, such as factories that produce automobile tires and other rubber products.

DOI:http://dx.doi.org/10.7554/eLife.09623.002

Mitochondrial Redox Dysfunction and Environmental Exposures

SIGNIFICANCE

Mitochondria are structurally and biochemically diverse, even within a single type of cell. Protein complexes localized to the inner mitochondrial membrane synthesize ATP by coupling electron transport and oxidative phosphorylation. The organelles produce reactive oxygen species (ROS) from mitochondrial oxygen and ROS can, in turn, alter the function and expression of proteins used for aerobic respiration by post-translational and transcriptional regulation.

RECENT ADVANCES

New interest is emerging not only into the roles of mitochondria in disease development and progression but also as a target for environmental toxicants.

CRITICAL ISSUES

Dysregulation of respiration has been linked to cell death and is a major contributor to acute neuronal trauma, peripheral diseases, as well as chronic neurodegenerative diseases, such as Parkinson's disease and Alzheimer's disease.

FUTURE DIRECTIONS

Here, we discuss the mechanisms underlying the sensitivity of the mitochondrial respiratory complexes to redox modulation, as well as examine the effects of environmental contaminants that have well-characterized mitochondrial toxicity. The contaminants discussed in this review are some of the most prevalent and potent environmental contaminants that have been linked to neurological dysfunction, altered cellular respiration, and oxidation.

BTEX in indoor air of waterpipe cafés: Levels and factors influencing their concentrations

BTEX (benzene, toluene, ethylbenzene and xylene) concentrations, factors affecting their levels, and the exposure risks related to these compounds were studied in waterpipe (Ghalyun/Hookah) cafés of Ardabil city in Islamic Republic of Iran. 81 waterpipe cafés from different districts of Ardabil city were selected and their ambient air was monitored for BTEX compounds. Air samples were taken from standing breathing zone of employees, ~150 cm above the ground level, and were analyzed using GC-FID. In each case, the types of smoked tobacco (regular, fruit flavored), types of ventilation systems (natural/artificial), and the floor level at which the café was located were investigated. A high mean concentration of 4.96±2.63 mg/m(3) corresponding to long term exposure to benzene-related cancer risk of 4314×10(-6) was estimated. The levels of the remaining compounds were lower than the national guideline limits, but their hazard quotients (HQ) for long term exposure to ethylbenzene (1.15) and xylene (17.32) exceeded the HQ unit value. Total hazard indices (HI) of 63.23 were obtained for non-cancer risks. Type of the smoked tobacco was the most important factor influencing BTEX concentrations in the cafés. BTEX concentrations in indoor ambient air of Ardabil waterpipe cafés were noticeably high, and therefore may pose important risks for human health on both short and long term exposures.

Obesity as a susceptibility factor to indoor particulate matter health effects in COPD

Our goal was to investigate whether obesity increases susceptibility to the adverse effects of indoor particulate matter on respiratory morbidity among individuals with chronic obstructive pulmonary disease (COPD). Participants with COPD were studied at baseline, 3 and 6 months. Obesity was defined as a body mass index ≥30 kg·m(-2). At each time point, indoor air was sampled for 5-7 days and particulate matter (PM) with an aerodynamic size ≤2.5 μm (PM2.5) and 2.5-10 μm (PM2.5-10) was measured. Respiratory symptoms, health status, rescue medication use, exacerbations, blood biomarkers and exhaled nitric oxide were assessed simultaneously. Of the 84 participants enrolled, 56% were obese and all were former smokers with moderate-to-severe COPD. Obese participants tended to have less severe disease as assessed by Global Initiative for Chronic Obstructive Pulmonary Disease stage and fewer pack-years of smoking. There was evidence that obesity modified the effects of indoor PM on COPD respiratory outcomes. Increases in PM2.5 and PM2.5-10 were associated with greater increases in nocturnal symptoms, dyspnoea and rescue medication use among obese versus non-obese participants. The impact of indoor PM on exacerbations, respiratory status and wheeze also tended to be greater among obese versus non-obese participants, as were differences in airway and systemic inflammatory responses to indoor PM. We found evidence that obesity was associated with exaggerated responses to indoor fine and coarse PM exposure among individuals with COPD.

Cyclic nucleotide-based therapeutics for chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) defines a group of chronic inflammatory disorders of the airways that are characterised by a progressive and largely irreversible decline in expiratory airflow. Drugs used to treat COPD through actions mediated by cyclic AMP (cAMP) are restricted to long-acting and short-acting β2-adrenoceptor agonists and, in a subset of patients with chronic bronchitis, a phosphodiesterase 4 inhibitor, roflumilast. These agents relax airway smooth muscle and suppress inflammation. At the molecular level, these effects in the airways are mediated by two cAMP effectors, cAMP-dependent protein kinase and exchange proteins activated by cAMP. The pharmacology of newer agents, acting through these systems, is discussed here with an emphasis on their potential to interact and increase therapeutic effectiveness.