Respiratory effects of exposure to diesel traffic in persons with asthma

The study to estimate the floating population in Seoul, Korea

Traffic-related pollutants have been reported to increase the morbidity of respiratory diseases. In order to apply management policies related to motor vehicles, studies of the floating population living in cities are important. The rate of metro rail transit system use by passengers residing in Seoul is about 54% of total public transportation use. Through the rate of metro use, the people-flow ratios in each administrative area were calculated. By applying a people-flow ratio based on the official census count, the floating population in 25 regions was calculated. The reduced level of deaths among the floating population in 14 regions having the roadside monitoring station was calculated as assuming a 20% reduction of mobile emission based on the policy. The hourly floating population size was calculated by applying the hourly population ratio to the regional population size as specified in the official census count. The number of people moving from 5 a.m. to next day 1 a.m. could not be precisely calculated when the population size was applied, but no issue was observed that would trigger a sizable shift in the rate of population change. The three patterns of increase, decrease, and no change of population in work hours were analyzed. When the concentration of particulate matter less than 10 μm in aerodynamic diameter was reduced by 20%, the number of excess deaths varied according to the difference of the floating population. The effective establishment of directions to manage the pollutants in cities should be carried out by considering the floating population. Although the number of people using the metro system is only an estimate, this disadvantage was supplemented by calculating inflow and outflow ratio of metro users per time in the total floating population in each region. Especially, 54% of metro usage in public transport causes high reliability in application.

Mechanistic link between diesel exhaust particles and respiratory reflexes

Background

Diesel exhaust particles (DEPs) are a major component of particulate matter in Europe's largest cities, and epidemiologic evidence links exposure with respiratory symptoms and asthma exacerbations. Respiratory reflexes are responsible for symptoms and are regulated by vagal afferent nerves, which innervate the airway. It is not known how DEP exposure activates airway afferents to elicit symptoms, such as cough and bronchospasm.

Objective

We sought to identify the mechanisms involved in activation of airway sensory afferents by DEPs.

Methods

In this study we use in vitro and in vivo electrophysiologic techniques, including a unique model that assesses depolarization (a marker of sensory nerve activation) of human vagus.

Results

We demonstrate a direct interaction between DEP and airway C-fiber afferents. In anesthetized guinea pigs intratracheal administration of DEPs activated airway C-fibers. The organic extract (DEP-OE) and not the cleaned particles evoked depolarization of guinea pig and human vagus, and this was inhibited by a transient receptor potential ankyrin-1 antagonist and the antioxidant N-acetyl cysteine. Polycyclic aromatic hydrocarbons, major constituents of DEPs, were implicated in this process through activation of the aryl hydrocarbon receptor and subsequent mitochondrial reactive oxygen species production, which is known to activate transient receptor potential ankyrin-1 on nociceptive C-fibers.

Conclusions

This study provides the first mechanistic insights into how exposure to urban air pollution leads to activation of guinea pig and human sensory nerves, which are responsible for respiratory symptoms. Mechanistic information will enable the development of appropriate therapeutic interventions and mitigation strategies for those susceptible subjects who are most at risk.

Is Neighborhood Green Space Protective against Associations between Child Asthma, Neighborhood Traffic Volume and Perceived Lack of Area Safety? Multilevel Analysis of 4447 Australian Children

Heavy traffic is a source of air pollution and a safety concern with important public health implications. We investigated whether green space lowers child asthma risk by buffering the effects of heavy traffic and a lack of neighborhood safety. Multilevel models were used to analyze affirmative asthma cases in nationally representative cross-sectional data from 4447 children aged 6-7 years old in Australia. Case-finding was based upon a triangulation of affirmative responses to three questions on doctor-diagnosed asthma, asthma-related medications and illness with wheezing lasting for at least 1 week within the 12 months prior. Among children considered to be exposed to high traffic volumes and areas with 0 to 20% green space quantity, the odds ratio of affirmative asthma was 1.87 (95% CI 1.37 to 2.55). However, the association between heavy traffic and asthma was significantly lower for participants living in areas with over 40% green space coverage (odds ratio for interaction 0.32, 95% CI 0.12 to 0.84). No association between affirmative asthma and green space coverage was observed for participants not exposed to heavy traffic, nor for the area safety variable. Protecting existing and investing in new green space may help to promote child respiratory health through the buffering of traffic-related air pollution.

Addressing unmet needs in understanding asthma mechanisms: From the European Asthma Research and Innovation Partnership (EARIP) Work Package (WP)2 collaborators

Asthma is a heterogeneous, complex disease with clinical phenotypes that incorporate persistent symptoms and acute exacerbations. It affects many millions of Europeans throughout their education and working lives and puts a heavy cost on European productivity. There is a wide spectrum of disease severity and control. Therapeutic advances have been slow despite greater understanding of basic mechanisms and the lack of satisfactory preventative and disease modifying management for asthma constitutes a significant unmet clinical need. Preventing, treating and ultimately curing asthma requires co-ordinated research and innovation across Europe. The European Asthma Research and Innovation Partnership (EARIP) is an FP7-funded programme which has taken a co-ordinated and integrated approach to analysing the future of asthma research and development. This report aims to identify the mechanistic areas in which investment is required to bring about significant improvements in asthma outcomes.

Decreased blood pressure associated with in-vehicle exposure to carbon monoxide in Korean volunteers

Background

Carbon monoxide (CO) is one of the primary components of emissions from light-duty vehicles, and reportedly comprises 77% of all pollutants emitted in terms of concentration. Exposure to CO aggravates cardiovascular disease and causes other health disorders. The study was aimed to assess the negative effects by injecting different amounts of CO concentration directly to human volunteers boarding in the car.

Methods

Human volunteers were exposed to CO concentrations of 0, 33.2, and 72.4 ppm, respectively during the first test and 0, 30.3, and 48.8 ppm respectively during the second test while seated in the car. The volunteers were exposed to each concentration for approximately 45 min. After exposure, blood pressure measurement, blood collection (carboxyhemoglobin [COHb] analysis), medical interview, echocardiography test, and cognitive reaction test were performed.

Result

In patients who were exposed to a mean concentration of CO for 72.4 ± 1.4 ppm during the first exposure test and 48.8 ± 3.7 ppm during the second exposure test, the COHb level exceeded 2%. Moreover, the diastolic blood pressure was decreased while increasing in CO concentration after exposure. The medical interview findings showed that the degree of fatigue was increased and the degree of concentration was reduced when the exposed concentration of CO was increased.

Conclusion

Although the study had a limited sample size, we found that even a low concentration of CO flowing into a car could have a negative influence on human health, such as change of blood pressure and degree of fatigue.

Whole Blood Cytokine Response to Local Traffic-Related Particulate Matter in Peruvian Children With and Without Asthma

This study sought to investigate if acute phase immune responses of whole blood from Peruvian children with controlled and uncontrolled asthma differed from children without asthma, following exposure to traffic-related particulate matter (TRPM). TRPM, including particulate matter from diesel combustion, has been shown to stimulate acute airway inflammation in individuals with and without asthma. For this study, a whole blood assay (WBA) was used to test peripheral whole blood samples from 27 children with asthma, and 12 without asthma. Participant blood samples were stimulated, ex vivo, for 24-h with an aqueous extract of TRPM that was collected near study area highways in Lima, Peru. All participant blood samples were tested against the same TRPM extract, in addition to purified bacterial endotoxin and pyrogen-free water, which served as positive and negative WBA controls, respectively. The innate and adaptive cytokine responses were evaluated in cell-free supernatants of the whole blood incubations. Comparatively similar levels were recorded for nine out of the 10 cytokines measured [e.g., – Interleukin (IL)-1β, IL-6, IL-10], regardless of study participant asthma status. However, IL-8 levels in TRPM-stimulated blood from children with uncontrolled asthma were diminished, compared to subjects without asthma (633 pg/ml vs. 1,023 pg/ml, respectively; p < 0.01); IL-8 responses for subjects with controlled asthma were also reduced, but to a lesser degree (799 pg/ml vs. 1,023 pg/ml, respectively; p = 0.10). These relationships were present before, and after, adjusting for age, sex, obesity/overweight status, C-reactive protein levels, and residential proximity to the study area’s major roadway. For tests conducted with endotoxin, there were no discernible differences in cytokine response between groups, for all cytokines measured. The WBA testing conducted for this study highlighted the capacity of the TRPM extract to potently elicit the release of IL-8 from the human whole blood system. Although the small sample size of the study limits the capacity to draw definitive conclusions, the IL-8 responses suggest that that asthma control may be associated with the regulation of a key mediator in neutrophil chemotaxis, at a systemic level, following exposure to PM derived from traffic-related sources.

Human bronchial epithelium orchestrates dendritic cell activation in severe asthma

The innate immune response is impaired in asthma, with increased epithelial release of C-X-C motif chemokine ligand (CXCL)8, interleukin (IL)-33 and thymic stromal lymphopoietin (TSLP). We hypothesised that dendritic cells might modulate the hyperresponsive epithelium in severe asthma.

For this purpose, we investigated epithelial–dendritic crosstalk in normal and diseased conditions, and because ultrafine particulate matter may affect asthmatic airways, we investigated its impact on this crosstalk. Air–liquid interface cultures of human bronchial epithelial cells (HBEC) of control subjects (cHBEC) or severe asthma patients (saHBEC) were co-cultured with monocyte-derived dendritic cells (moDC).

Increased release of CXCL8, TSLP and IL-33 from saHBEC contrasted with cHBEC producing CXCL10 and CCL2. Regarding moDC activation, saHBEC co-cultures induced only upregulation of CD86 expression, while cHBEC yielded full moDC maturation with HLA-DR, CD80, CD86 and CD40 upregulation. Particulate matter stimulation of HBEC had no effect on cHBEC but stimulated CXCL8 and IL-33 release in saHBEC. Particulate matter impaired epithelium signalling (TSLP, IL-33 and CXCL8) in saHBEC co-cultures despite C-C chemokine ligand 2 induction.

Crosstalk between HBEC and moDC can be establishedin vitro, driving a T1-type response with cHBEC and a T2-type response with saHBEC. Normal or asthmatic status of HBEC differentially shapes the epithelial–dendritic responses. We conclude that control moDC cannot rescue the hyperresponsive airway epithelium of severe asthmatics.

Environmental triggers and avoidance in the management of asthma

Identifying asthma triggers forms the basis of environmental secondary prevention. These triggers may be allergenic or nonallergenic. Allergenic triggers include indoor allergens, such as house dust mites (HDMs), molds, pets, cockroaches, and rodents, and outdoor allergens, such as pollens and molds. Clinical observations provide support for the role of HDM exposure as a trigger, although avoidance studies provide conflicting results. Molds and their metabolic products are now considered to be triggers of asthma attacks. Pets, dogs, and especially cats can undoubtedly trigger asthmatic symptoms in sensitized subjects. Avoidance is difficult and rarely adhered to by families. Cockroach allergens contribute to asthma morbidity, and avoidance strategies can lead to clinical benefit. Mouse allergens are mostly found in inner-city dwellings, but their implication in asthma morbidity is debated. In the outdoors, pollens can induce seasonal asthma in sensitized individuals. Avoidance relies on preventing pollens from getting into the house and on minimizing seasonal outdoor exposure. Outdoor molds may lead to severe asthma exacerbations. Nonallergenic triggers include viral infections, active and passive smoking, meteorological changes, occupational exposures, and other triggers that are less commonly involved. Viral infection is the main asthma trigger in children. Active smoking is associated with higher asthma morbidity, and smoking cessation interventions should be personalized. Passive smoking is also a risk factor for asthma exacerbation. The implementation of public smoking bans has led to a reduction in the hospitalization of asthmatic children. Air pollution levels have been linked with asthmatic symptoms, a decrease in lung function, and increased emergency room visits and hospitalizations. Since avoidance is not easy to achieve, clean air policies remain the most effective strategy. Indoor air is also affected by air pollutants, such as cigarette smoke and volatile organic compounds generated by building and cleaning materials. Occupational exposures include work-exacerbated asthma and work-related asthma.

The exposome in practice: Design of the EXPOsOMICS project

EXPOsOMICS is a European Union funded project that aims to develop a novel approach to the assessment of exposure to high priority environmental pollutants, by characterizing the external and the internal components of the exposome. It focuses on air and water contaminants during critical periods of life. To this end, the project centres on 1) exposure assessment at the personal and population levels within existing European short and long-term population studies, exploiting available tools and methods which have been developed for personal exposure monitoring (PEM); and 2) multiple "omic" technologies for the analysis of biological samples (internal markers of external exposures). The search for the relationships between external exposures and global profiles of molecular features in the same individuals constitutes a novel advancement towards the development of "next generation exposure assessment" for environmental chemicals and their mixtures. The linkage with disease risks opens the way to what are defined here as 'exposome-wide association studies' (EWAS).

Respiratory outcomes of ultrafine particulate matter (UFPM) as a surrogate measure of near-roadway exposures among bicyclists

BACKGROUND

Studies have shown a consistent association between exposure to traffic-related air pollution and adverse health effects. In particular, exposure can be high for cyclists who travel near roadways. The objective of the current study was to examine the relationship between short-term exposure of near-road traffic emissions and acute changes in lung function among individuals who frequently bike in the Sacramento and Davis areas in California. Ultrafine particulate matter (UFPM) was used as a surrogate for near-roadway exposure in this study since the main source of this pollutant is from motor vehicle exhaust.

METHODS

Thirty-two bicyclists were recruited and completed two rides on separate days during the study period of March-June, 2008. One ride was on a high traffic route paralleling a section of Interstate 80 (I-80)/Interstate Business 80 (I-80B), and a second one was on a low traffic route, such as bike paths away from major highways. The participant's lung function was measured before and after each ride, and UFPM exposure was measured during the rides using a condensation particle counter (CPC).

RESULTS

In the final linear mixed-effect model using median UFPM concentrations as the main exposure, we observed that lung function change (post-ride minus baseline measurements) shifted in the negative direction. Lung function changed by 216 mL for FVC and 168 mL for FEV₁, respectively, for an interquartile range (IQR: 12,225 to 36,833 number of particles/cm³) increase of UFPM concentration after adjusting for other covariates of age, sex, wind direction, and day of the week.

CONCLUSIONS

This study found significant associations between increased levels of UFPM concentrations as a proxy for near road traffic pollution, and decrements in lung function measurements. Our results are related to short-term exposures, and the long-term health effects of cycling near heavy traffic require further research. Our study suggests the need to reduce traffic pollution, particularly near roads. Cyclists should plan their route to reduce their exposure where possible and further research on built environment designs may help urban planners to reduce the potential health concerns of cyclists' exposure to traffic-related air pollution.

Comparison of air pollution exposures in active vs. passive travel modes in European cities: A quantitative review

BACKGROUND

Transport microenvironments tend to have higher air pollutant concentrations than other settings most people encounter in their daily lives. The choice of travel modes may affect significantly individuals' exposures; however such considerations are typically not accounted for in exposure assessment used in environmental health studies. In particular, with increasing interest in the promotion of active travel, health impact studies that attempt to estimate potential adverse consequences of potential increased pollutant inhalation during walking or cycling have emerged. Such studies require a quantification of relative exposures in travel modes.

METHODS

The literature on air pollution exposures in travel microenvironments in Europe was reviewed. Studies which measured various travel modes including at least walking or cycling in a simultaneous or quasi-simultaneous design were selected. Data from these studies were harmonized to allow for a quantitative synthesis of the estimates. Ranges of ratios and 95% confidence interval (CI) of air pollution exposure between modes and between background and transportation modes were estimated.

RESULTS

Ten studies measuring fine particulate matter (PM_2.5), black carbon (BC), ultrafine particles (UFP), and/or carbon monoxide (CO) in the walk, bicycle, car and/or bus modes were included in the analysis. Only three reported on CO and BC and results should be interpreted with caution. Pedestrians were shown to be the most consistently least exposed of all across studies, with the bus, bicycle and car modes on average 1.3 to 1.5 times higher for PM_2.5; 1.1 to 1.7 times higher for UFP; and 1.3 to 2.9 times higher for CO; however the 95% CI included 1 for the UFP walk to bus ratio. Only for BC were pedestrians more exposed than bus users on average (bus to walk ratio 0.8), but remained less exposed than those on bicycles or in cars. Car users tended to be the most exposed (from 2.9 times higher than pedestrians for BC down to similar exposures to cyclists for UFP on average). Bus exposures tended to be similar to that of cyclists (95% CI including 1 for PM_2.5, CO and BC), except for UFP where they were lower (ratio 0.7).

CONCLUSION

A quantitative method that synthesizes the literature on air pollution exposure in travel microenvironments for use in health impact assessments or potentially for epidemiology was conducted. Results relevant for the European context are presented, showing generally greatest exposures in car riders and lowest exposure in pedestrians.

Occupational lung diseases: from old and novel exposures to effective preventive strategies

Occupational exposure is an important, global cause of respiratory disease. Unlike many other non-communicable lung diseases, the proximal causes of many occupational lung diseases are well understood and they should be amenable to control with use of established and effective approaches. Therefore, the risks arising from exposure to silica and asbestos are well known, as are the means of their prevention. Although the incidence of occupational lung disease has decreased in many countries, in parts of the world undergoing rapid economic transition and population growth-often with large informal and unregulated workforces-occupational exposures continue to impose a heavy burden of disease. The incidence of interstitial and malignant lung diseases remains unacceptably high because control measures are not implemented or exposures arise in novel ways. With the advent of innovative technologies, new threats are continually introduced to the workplace (eg, indium compounds and vicinal diketones). In developed countries, work-related asthma is the commonest occupational lung disease of short latency. Although generic control measures to reduce the risk of developing or exacerbating asthma are well recognised, there is still uncertainty, for example, with regards to the management of workers who develop asthma but remain in the same job. In this Review, we provide recommendations for research, surveillance, and other action for reducing the burden of occupational lung diseases.

Diesel Exhaust Particles Enhance MUC4 Expression in NCI-H292 Cells and Nasal Epithelial Cells via the p38/CREB Pathway

BACKGROUND

Diesel exhaust particles (DEPs), the major contributors to air pollution, induce inflammatory responses in the nasal epithelium. Overproduction of airway mucins is an important pathogenic finding in inflammatory airway diseases.

OBJECTIVE

The aims of the present study were to determine the effect of DEPs on the expression of the mucin gene MUC4 and to investigate the underlying mechanism of DEP-induced MUC4 expression in NCI-H292 cells and primary nasal epithelial cells (PNECs).

METHODS

NCI-H292 cells were stimulated for 24 h with DEPs. Messenger RNA (mRNA) and protein expression of MUC4 was determined by real-time reverse transcription (RT) polymerase chain reaction (PCR) and Western blotting. NCI-H292 cells were exposed to 3 mitogen-activated protein kinase inhibitors (U0126, SB203580, and SP600125) and a CREB (cAMP response element-binding protein) inhibitor prior to stimulation with DEPs, and MUC4 expression was examined by RT-PCR and Western blotting. PNECs were pretreated with a p38 inhibitor and CREB inhibitor prior to stimulation with DEPs, and MUC4 expression was then determined by RT-PCR and/or Western blotting.

RESULTS

DEPs significantly increased the expression of MUC4 mRNA and protein. MUC4 mRNA and protein expression was inhibited by pretreatment with p38 and CREB inhibitors in NCI-H292 stimulated with DEPs. p38 and CREB inhibitors also blocked the expression of MUC4 mRNA and protein in DEP-stimulated PNECs.

CONCLUSIONS

We demonstrated that DEPs stimulated the expression of MUC4 via the p38/CREB pathway in NCI-H292 cells and PNECs. The results of the present study pave the way for further studies on the role of MUC4 in DEP-induced hypersecretion in airway epithelium.

A panel study of airborne particulate matter composition versus concentration: Potential for inflammatory response and impaired pulmonary function in children

BACKGROUND

The relationship between airborne particulate matter (PM) and pulmonary function in children has not been consistent among studies, potentially owing to differences in the inflammatory response to PM, based on PM types and sources. The objective of this study was to investigate the effect of airborne PM on pulmonary function in schoolchildren and its potential for an inflammatory response.

METHODS

Daily morning peak expiratory flow (PEF) was measured in 339 schoolchildren in February 2015. Interleukin (IL)-8 production was assessed in THP1 cells stimulated by airborne PM collected every day during the study period, and these IL-8 concentrations are described as the daily IL-8 levels. A linear mixed model was used to estimate the association between PEF values and the daily levels of suspended PM (SPM), PM diameters smaller than 2.5 μm (PM_2.5), and IL-8.

RESULTS

The daily IL-8 levels were significantly associated with those of SPM and PM_2.5. A 0.83 μg/mL increase in IL-8 levels was significantly associated with a -1.07 L/min (95% confidence interval, -2.05 to -0.08) decrease in PEF. A 12.0 μg/m³ increase in SPM and a 10.0 μg/m³ increase in PM_2.5 were associated with a -1.36 L/min (-2.93 to 0.22) and -1.72 L/min (-3.82 to 0.36) decreases in PEF, respectively. There were no significant relationships between PEF, SPM, and PM_2.5.

CONCLUSIONS

These findings suggest that the effects of airborne PM on pulmonary function in schoolchildren might depend more on the pro-inflammatory response than the mass concentration of the PM.

Effect of Short-Term Exposure to High Particulate Levels on Cough Reflex Sensitivity in Healthy Tourists: A Pilot Study

BACKGROUND

Previous studies have reported a relationship between particulate air pollution and respiratory symptoms or decline in lung function, but information about acute effects of short-term exposure to airborne particulate matter (PM) on cough and pulmonary function is scarce.

OBJECTIVE

To investigate the effect of short-term exposure to high concentrations of PM on the cough reflex threshold, urge-to-cough, pulmonary function, and cough-related quality of life in a group of healthy non-resident volunteers visiting Beijing, China.

METHODS

Seventeen healthy residents of Sendai, Japan, who planned to attend a meeting in Beijing, were recruited. We checked local air quality and measured cough reflex thresholds, urge-to-cough, pulmonary function, and Leicester Cough Questionnaire-acute (LCQ-acute) scores in the volunteers before, during, and after their trip to Beijing.

RESULTS

The PM_2.5 and PM₁₀ concentrations in Beijing were significantly higher than those in Japan on the measurement days. Cough reflex thresholds, expressed as nebulized citric acid concentrations required to induce ≥ 2 and ≥ 5 coughs, were significantly lower during the stay in Beijing than before or after the visit. Vital capacity, forced expiratory volume in one second (FEV₁), forced vital capacity (FVC), and FEV₁/FVC were significantly lower during the stay in Beijing than before the trip. Similarly, the urge-to-cough threshold was significantly lower during the stay in Beijing than after the trip, as was the total LCQ-acute score.

CONCLUSION

We tentatively concluded that short-term exposure to high PM concentrations may have adverse effects on cough reflex and urge-to-cough thresholds, pulmonary function, and cough-related quality of life.

Comparison of lung damage in mice exposed to black carbon particles and ozone-oxidized black carbon particles

Black carbon (BC) is a key component of atmospheric particles and has a significant effect on human health. Oxidation could change the characteristics of BC and increase its toxicity. The comparison of lung damage in mice exposed to BC and ozone-oxidized BC (oBC) particles is investigated in this study. Mice which were intratracheally instilled with particles have a higher expression of IL-1β, IL-6 and IL-33 in bronchoalveolar lavage fluid (BALF). Also, the IL-6, IL-33 mRNA expression in the lung tissue of mice instilled with oBC was higher than that of mice instilled with BC. The expression of CD3 in the lung tissue of mice intratracheally instilled with oBC was higher than the mice distilled with BC. The pathology results showed that the lung tissue of mice instilled with oBC particles have much more inflammatory cells infiltration than that of mice treated with BC. It is believed that the PI3K-AKT pathway might be involved in the oBC particles caused lung damage. Results indicated that oBC particles in the atmosphere may cause more damage to health.

Acute respiratory response to traffic-related air pollution during physical activity performance

BACKGROUND

Physical activity (PA) has beneficial, whereas exposure to traffic related air pollution (TRAP) has adverse, respiratory effects. Few studies, however, have examined if the acute effects of TRAP upon respiratory outcomes are modified depending on the level of PA.

OBJECTIVES

The aim of our study was to disentangle acute effects of TRAP and PA upon respiratory outcomes and assess the impact of participants TRAP pre-exposure.

METHODS

We conducted a real-world crossover study with repeated measures of 30 healthy adults. Participants completed four 2-h exposure scenarios that included either rest or intermittent exercise in high- and low-traffic environments. Measures of respiratory function were collected at three time points. Pre-exposure to TRAP was ascertained from land-use-modeled address-attributed values. Mixed-effects models were used to estimate the impact of TRAP and PA on respiratory measures as well as potential effect modifications.

RESULTS

We found that PA was associated with a statistically significant increases of FEV₁ (48.5mL, p=0.02), FEV₁/FVC (0.64%, p=0.005) and FEF_25-75% (97.8mL, p=0.02). An increase in exposure to one unit (1μg/m³) of PM_coarse was associated with a decrease in FEV₁ (-1.31mL, p=0.02) and FVC (-1.71mL, p=0.01), respectively. On the other hand, for an otherwise equivalent exposure an increase of PA by one unit (1%Heart rate max) was found to reduce the immediate negative effects of particulate matter (PM) upon PEF (PM_2.5, 0.02L/min, p=0.047; PM₁₀, 0.02L/min p=0.02; PM_coarse, 0.03L/min, p=0.02) and the several hours delayed negative effects of PM upon FVC (PM_coarse, 0.11mL, p=0.02). The negative impact of exposure to TRAP constituents on FEV₁/FVC and PEF was attenuated in those participants with higher TRAP pre-exposure levels.

CONCLUSIONS

Our results suggest that associations between various pollutant exposures and respiratory measures are modified by the level of PA during exposure and TRAP pre-exposure of participants.

Effects of Asian Dust Particles on the Early-Stage Antigen-Induced Immune Response of Asthma in NC/Nga Mice

Asian dust (AD) can aggravate airway inflammation in asthma, but the association between AD and the development of asthma remains unclear. This study aimed to investigate the effects of AD on the early stage of antigen sensitization using a mouse model of asthma, as well as the role of leukotrienes (LTs) in antigen-induced airway inflammation potentiated by AD particles. NC/Nga mice were co-sensitized by intranasal instillation of AD particles and/or Dermatophagoides farinae (Df) for five consecutive days. Df-sensitized mice were stimulated with an intranasal Df challenge at seven days. Mice were treated with the type 1 cysteinyl LT (CysLT₁) receptor antagonist orally 4 h before and 1 h after the allergen challenge. At 24 h post-challenge, the differential leukocyte count, inflammatory cytokines, and LTs in bronchoalveolar lavage fluid were assessed, and airway inflammation was evaluated histopathologically. AD augmented neutrophilic and eosinophilic airway inflammation with increased CysLTs and dihydroxy-LT in a mouse model of asthma. The CysLT₁ receptor antagonist was shown to attenuate both neutrophilic and eosinophilic airway inflammation augmented by AD. Therefore, exposure to AD may be associated with the development of asthma and LTs may play important roles in airway inflammation augmented by AD.

Ambient Air Pollution, Meteorological Factors and Outpatient Visits for Eczema in Shanghai, China: A Time-Series Analysis

Environmental irritants are important risk factors for skin diseases, but little is known about the influence of environmental factors on eczema incidence. In this time-series study, our objective was to examine the associations of environmental factors with outpatient visits for eczema. Daily outpatient visits between 2007 and 2011 (1826 days) were collected from Huashan Hospital in Shanghai, China. We used an overdispersed generalized additive model to investigate the short-term association between environmental factors and outpatient visits for eczema. Daily outpatient visits for eczema were significantly associated with air pollution and meteorological factors. For example, a 10 μg/m³ increase of 7-day (lag 06) average concentrations of PM₁₀ (particulate matter no greater than 10 microns), SO₂, NO₂ was associated with 0.81% (95% confidence intervals (CI) 0.39%, 1.22%), 2.22% (95% CI: 1.27%, 3.16%) and 2.31% (95% CI: 1.17%, 3.45%) increase in outpatient visits for eczema, respectively. A 10 °C elevation of temperature on lag 0 day were associated with 8.44% (95% CI: 4.66%, 12.22%) increase in eczema visits, whereas 10 unit decrease of 7-day average relative humidity were associated with 10.86% (95% CI: 8.83%, 12.89%) increase in eczema visits. This study provided clear evidence of ambient air pollution, high temperature and low relative humidity on increasing the incidence of eczema in Shanghai, China.

Asthma

Asthma is one of the most frequent chronic respiratory diseases worldwide, with an increase in its prevalence in the last decade. Ongoing studies continue to search for better diagnostic tools and advanced treatment options in an effort to decrease the morbidity and mortality associated with it. Unfortunately, many asthmatic patients still suffer from poorly controlled asthma, which may lead to life-threatening situations. This article reviews the basics of asthma and highlights the current guidelines in making accurate diagnosis and initiating therapeutic plan.

Asthma exacerbations and traffic: examining relationships using link-based traffic metrics and a comprehensive patient database

BACKGROUND

The Rochester Epidemiology Project (REP) is a unique community-based medical record data linkage system that provides individual patient address, diagnosis and visit information for all hospitalizations, as well as emergency department, urgent care and outpatient clinic visits for asthma. Proximity to traffic is known to be associated with asthma exacerbations and severity. Our null hypothesis was that there is no association between residential proximity to traffic and asthma exacerbations over eleven years of REP data.

METHODS

Spatial coordinates of the homes of 19,915 individuals diagnosed with asthma were extracted from the REP database. Three metrics of traffic exposure at residences were calculated from link-based traffic count data. We used exploratory statistics as well as logistic and Poisson regression to examine associations between three traffic metrics at the home address and asthma exacerbations.

RESULTS

Asthma exacerbations increased as traffic levels near the home increased. Proximity to traffic was a significant predictor of asthma exacerbations in logistic and Poisson regressions controlling for age, gender and block group poverty.

CONCLUSIONS

Over eleven years in a comprehensive county-wide data set of asthma patients, and after controlling for demographic effects, we found evidence that living in proximity to traffic increased the risk of asthma exacerbations.

Physical activity, black carbon exposure and airway inflammation in an urban adolescent cohort

OBJECTIVE

Regular physical activity can improve cardiopulmonary health; however, increased respiratory rates and tidal volumes during activity may increase the effective internal dose of air pollution exposure. Our objective was to investigate the impact of black carbon (BC) measured by personal sampler on the relationship between physical activity and fractional exhaled nitric oxide (FeNO), a marker of airway inflammation. We hypothesized that higher personal BC would attenuate the protective effect of physical activity on airway inflammation.

METHODS

We performed a cross-sectional study nested in a birth cohort of African American and Dominican children living in the Bronx and Northern Manhattan, New York City. Children were recruited based on age (target 9-14 year olds) and presence (n=70) or absence (n=59) of current asthma. Children wore wrist mounted accelerometers for 6 days and were classified as 'active' if they had ≥60min of moderate-to-vigorous activity (MVA) each day and 'non-active' if they had <60min of MVA on any given day, based on CDC guidelines. Personal BC measured using a MicroAeth, was assessed during two 24-h periods, at the beginning and end of physical activity assessment. High BC was defined as the upper tertile of BC measured with personal sampler. FeNO measurements were sampled at the beginning and end of the of physical activity assessment.

RESULTS

In multivariable linear regression models, 'active' children had 25% higher personal BC concentrations (p=0.02) and 20% lower FeNO (p=0.04) compared to 'non-active' children. Among children with high personal BC (n=33), there was no relationship between activity and FeNO (p=1.00). The significant protective relationship between activity and airway inflammation was largely driven by children with lower personal BC (n=96, p=0.04).

CONCLUSIONS

Children that live in an urban environment and are physically active on a daily basis have higher personal exposure to BC. High BC offsets the protective relationship between physical activity and airway inflammation.

Allergies in urban versus countryside settings in Poland as part of the Epidemiology of the Allergic Diseases in Poland (ECAP) study - challenge the early differential diagnosis

Introduction

The incidence of allergies depends on a number of factors, including adopting an urban “western” lifestyle, genetic predispositions, and different regions of residence.

Aim

To compare the prevalence of allergic conditions (seasonal allergic rhinitis (SAR) and perennial allergic rhinitis (PAR), bronchial asthma (BA), atopic dermatitis (AD)) in a group of countryside versus urban residents in Poland.

Material and methods

The prevalence of allergic conditions in urban versus countryside settings was assessed using the translated and approved questionnaire developed for international ECRHS II and ISAAC studies. Respondents were selected via random multistage sampling, with proportionate stratified sampling, and the Polish Resident Identification Number (PESEL) as the basis. A total of 18,617 respondents took part in the study. Subsequently, approximately 25% of the subjects underwent outpatient assessments: skin-prick, lung function, peak nasal inspiratory flow (PNIF) tests, as well as history-taking.

Results

Allergic rhinitis (AR) proved to be the most common condition in the entire study population. Children residing in the countryside were twice more likely to be diagnosed with BA (8.33% vs. 4%; p < 0.05). Conversely, in the adult subgroup, BA was more commonly observed in urban areas. Whereas reported symptom rates were much higher in AR and AD patients, symptomatic BA was proportionately lower with respect to the official diagnoses (underdiagnosed BA phenomenon). Atopic dermatitis was considerably more common in the metropolitan population. One factor that significantly correlated with allergic diseases was a positive family history.

Conclusions

Inhabitants of metropolitan areas are to a greater extent predisposed to allergic conditions. One factor significantly contributing to allergies is genetic predisposition. Given the scale of the problem, there is an urgent need to implement measures for early prevention and diagnosis of allergies to minimize distant health effects.

Scripted drives: A robust protocol for generating exposures to traffic-related air pollution

Commuting in automobiles can contribute substantially to total traffic-related air pollution (TRAP) exposure, yet measuring commuting exposures for studies of health outcomes remains challenging. To estimate real-world TRAP exposures, we developed and evaluated the robustness of a scripted drive protocol on the NJ Turnpike and local roads between April 2007 and October 2014. Study participants were driven in a car with closed windows and open vents during morning rush hours on 190 days. Real-time measurements of PM2.5, PNC, CO, and BC, and integrated samples of NO2, were made in the car cabin. Exposure measures included in-vehicle concentrations on the NJ Turnpike and local roads and the differences and ratios of these concentrations. Median in-cabin concentrations were 11 μg/m3 PM2.5, 40 000 particles/cm3, 0.3 ppm CO, 4 μg/m3 BC, and 20.6 ppb NO2. In-cabin concentrations on the NJ Turnpike were higher than in-cabin concentrations on local roads by a factor of 1.4 for PM2.5, 3.5 for PNC, 1.0 for CO, and 4 for BC. Median concentrations of NO2 for full rides were 2.4 times higher than ambient concentrations. Results were generally robust relative to season, traffic congestion, ventilation setting, and study year, except for PNC and PM2.5, which had secular and seasonal trends. Ratios of concentrations were more stable than differences or absolute concentrations. Scripted drives can be used for generating reasonably consistent in-cabin increments of exposure to traffic-related air pollution.

Particulate Oxidative Burden as a Predictor of Exhaled Nitric Oxide in Children with Asthma

BACKGROUND

Epidemiological studies have provided strong evidence that fine particulate matter (PM2.5; aerodynamic diameter ≤ 2.5 μm) can exacerbate asthmatic symptoms in children. Pro-oxidant components of PM2.5 are capable of directly generating reactive oxygen species. Oxidative burden is used to describe the capacity of PM2.5 to generate reactive oxygen species in the lung.

OBJECTIVE

In this study we investigated the association between airway inflammation in asthmatic children and oxidative burden of PM2.5 personal exposure.

METHODS

Daily PM2.5 personal exposure samples (n = 249) of 62 asthmatic school-aged children in Montreal were collected over 10 consecutive days. The oxidative burden of PM2.5 samples was determined in vitro as the depletion of low-molecular-weight antioxidants (ascorbate and glutathione) from a synthetic model of the fluid lining the respiratory tract. Airway inflammation was measured daily as fractional exhaled nitric oxide (FeNO).

RESULTS

A positive association was identified between FeNO and glutathione-related oxidative burden exposure in the previous 24 hr (6.0% increase per interquartile range change in glutathione). Glutathione-related oxidative burden was further found to be positively associated with FeNO over 1-day lag and 2-day lag periods. Results further demonstrate that corticosteroid use may reduce the FeNO response to elevated glutathione-related oxidative burden exposure (no use, 15.8%; irregular use, 3.8%), whereas mold (22.1%), dust (10.6%), or fur (13.1%) allergies may increase FeNO in children with versus children without these allergies (11.5%). No association was found between PM2.5 mass or ascorbate-related oxidative burden and FeNO levels.

CONCLUSIONS

Exposure to PM2.5 with elevated glutathione-related oxidative burden was associated with increased FeNO.

CITATION

Maikawa CL, Weichenthal S, Wheeler AJ, Dobbin NA, Smargiassi A, Evans G, Liu L, Goldberg MS, Godri Pollitt KJ. 2016. Particulate oxidative burden as a predictor of exhaled nitric oxide in children with asthma. Environ Health Perspect 124:1616-1622; http://dx.doi.org/10.1289/EHP175.

Physical Activity, Air Pollution, and the Risk of Asthma and Chronic Obstructive Pulmonary Disease

RATIONALE

Physical activity enhances uptake of air pollutants in the lung, possibly augmenting their harmful effects on chronic lung disease during exercise.

OBJECTIVES

To examine whether benefits of physical activity with respect to the risk of asthma and chronic obstructive pulmonary disease (COPD) are moderated by exposure to high air pollution levels in an urban setting.

METHODS

A total of 53,113 subjects (50-65 yr) from the Danish Diet, Cancer, and Health cohort reported physical activity at recruitment (1993-1997) and were followed until 2013 in the National Patient Register for incident hospitalizations for asthma and COPD. Levels of nitrogen dioxide (NO₂) were estimated at subject residences at the time of recruitment. We used Cox regression to associate physical activities and NO₂ (high/medium/low) with asthma and COPD, and then introduced an interaction term between each physical activity and NO₂.

MEASUREMENTS AND MAIN RESULTS

A total of 1,151 subjects were hospitalized for asthma and 3,225 for COPD during 16 years. We found inverse associations of participation in sports (hazard ratio [95% confidence interval]: 0.85 [0.75-0.96]) and cycling (0.85 [0.75-0.96]) with incident asthma, and of participation in sports (0.82 [0.77-0.89]), cycling (0.81 [0.76-0.87]), gardening (0.88 [0.81-0.94]), and walking (0.85 [0.75-0.95]) with incident COPD admissions. We found positive associations between NO₂ and incident asthma (1.23 [1.04-1.47]) and COPD (1.15 [1.03-1.27]) hospitalizations (comparing ≥21.0 μg/m³ to <14.3 μg/m³). We found no interaction between associations of any physical activity and NO₂ on incident asthma or COPD hospitalizations.

CONCLUSIONS

Increased exposure to air pollution during exercise does not outweigh beneficial effects of physical activity on the risk of asthma and COPD.

Effects of Short-Term Exposure to Particulate Air Pollutants on the Inflammatory Response and Respiratory Symptoms: A Panel Study in Schoolchildren from Rural Areas of Japan

The relationship between particulate air pollutants and respiratory symptoms in children has not been consistent among studies, potentially owing to differences in the inflammatory response to different particulate air pollutants. This study aimed to investigate the effect of particulate air pollutants on respiratory symptoms and the inflammatory response in schoolchildren. Three hundred-and-sixty children were included in the study. The children recorded daily respiratory symptom scores for October 2015. In addition, the daily amount of interleukin (IL)-6, IL-8, and tumor necrosis factor (TNF)-α production was assessed in THP1 cells stimulated with suspended particulate matter (SPM), which was collected every day during the study period. Generalized estimating equation logistic regression analyses were used to estimate the associations among respiratory symptoms and the daily levels of SPM, IL-6, IL-8, and TNF-α. Daily SPM levels were not associated with respiratory symptoms or the daily IL-6, IL-8, and TNF-α levels. Conversely, there was a significant association between respiratory symptoms and the daily IL-6, IL-8, and TNF-α levels. These results suggested that the effects of particulate air pollutants on respiratory symptoms in schoolchildren might depend more on the pro-inflammatory response to them than on their mass concentration.

Exercise-induced bronchoconstriction update-2016

The first practice parameter on exercise-induced bronchoconstriction (EIB) was published in 2010. This updated practice parameter was prepared 5 years later. In the ensuing years, there has been increased understanding of the pathogenesis of EIB and improved diagnosis of this disorder by using objective testing. At the time of this publication, observations included the following: dry powder mannitol for inhalation as a bronchial provocation test is FDA approved however not currently available in the United States; if baseline pulmonary function test results are normal to near normal (before and after bronchodilator) in a person with suspected EIB, then further testing should be performed by using standardized exercise challenge or eucapnic voluntary hyperpnea (EVH); and the efficacy of nonpharmaceutical interventions (omega-3 fatty acids) has been challenged. The workgroup preparing this practice parameter updated contemporary practice guidelines based on a current systematic literature review. The group obtained supplementary literature and consensus expert opinions when the published literature was insufficient. A search of the medical literature on PubMed was conducted, and search terms included pathogenesis, diagnosis, differential diagnosis, and therapy (both pharmaceutical and nonpharmaceutical) of exercise-induced bronchoconstriction or exercise-induced asthma (which is no longer a preferred term); asthma; and exercise and asthma. References assessed as relevant to the topic were evaluated to search for additional relevant references. Published clinical studies were appraised by category of evidence and used to document the strength of the recommendation. The parameter was then evaluated by Joint Task Force reviewers and then by reviewers assigned by the parent organizations, as well as the general membership. Based on this process, the parameter can be characterized as an evidence- and consensus-based document.

Association between size-segregated particles in ambient air and acute respiratory inflammation

The health effects of particulate matter (PM) in ambient air are well documented. However, whether PM size plays a critical role in these effects is unclear in the population studies. This study investigated the association between the ambient concentrations of PM with varies sizes (5.6-560nm) and a biomarker of acute respiratory inflammation, the fraction of exhaled nitric oxide (FENO), in a panel of 55 elderly people in Shanghai, China. Linear mixed-effect model was fitted to estimate the association between FENO and moving average concentrations of PM, adjusting for temperature, relative humidity, day of the week, and age. Results showed that among the measured particles size range, Aitken-mode (20-100nm) particles had the strongest positive association with increased FENO when using moving average concentration of PM up to 24h prior to visits. The estimates were robust to the adjustment for gender, condition of chronic disease and use of medication, and to the sensitive analysis using different times of visits. The authors concluded that the association between acute respiratory inflammation and PM concentration of fine particulates depended on particle size, and suggested Aitken-mode particles may be the most responsible for this adverse health association.

Proximity to a Major Road and Plasma Cytokines in School-Aged Children

Traffic-related air pollution (TRAP) may affect immune responses, including those in the T_H2 and T_H17 pathways. To examine whether TRAP is associated with plasma level of T_H17-, T_H1-, and T_H2-related cytokines in children with and without asthma, a cross-sectional study of 577 children (ages 6–14 years) with (n = 294) and without (n = 283) asthma in San Juan (Puerto Rico) was performed. Residential distance to a major road was estimated using geocoded home addresses for study participants. A panel of 14 cytokines, enriched for the T_H17 pathway, was measured in plasma. Asthma was defined as physician-diagnosed asthma and current wheeze. Multivariable linear regression was used to examine the association of residential distance to a major road (a marker of TRAP), asthma, and cytokine levels. Among all participating children, residential proximity to a major road was significantly associated with increased plasma level of IL-31, even after adjustment for relevant covariates and correction for multiple testing. The presence of asthma modified the estimated effect of the residential distance to a major road on plasma TNF-α (P for interaction = 0.00047). Although living farther from a major road was significantly associated with lower TNF-α level in control subjects, no such decrease was seen in children with asthma. In a direct comparison of cases and control subjects, children with asthma had significantly higher levels of IL-1β, IL-22, and IL-33 than control subjects. TRAP is associated with increased levels of proinflammatory cytokines among Puerto Rican children, who belong to an ethnic group with high risk for asthma.

How do you explain the risk of air pollution to your patients?

.@ERStalk Environ & Health committee workshop concludes: HCPs vital to raising awareness of air pollution to patients http://ow.ly/pfOe301FoIg.

Trace metal exposure is associated with increased exhaled nitric oxide in asthmatic children

BACKGROUND

Children with asthma experience increased susceptibility to airborne pollutants. Exposure to traffic and industrial activity have been positively associated with exacerbation of symptoms as well as emergency room visits and hospitalisations. The effect of trace metals contained in fine particulate matter (aerodynamic diameter 2.5 μm and lower, PM2.5) on acute health effects amongst asthmatic children has not been well investigated. The objective of this panel study in asthmatic children was to determine the association between personal daily exposure to ambient trace metals and airway inflammation, as measured by fractional exhaled nitric oxide (FeNO).

METHODS

Daily concentrations of trace metals contained on PM2.5 were determined from personal samples (n = 217) collected from 70 asthmatic school aged children in Montreal, Canada, over ten consecutive days. FeNO was measured daily using standard techniques.

RESULTS

A positive association was found between FeNO and children's exposure to an indicator of vehicular non-tailpipe emissions (8.9 % increase for an increase in the interquartile range (IQR) in barium, 95 % confidence interval (CI): 2.8, 15.4) as well as exposure to an indicator of industrial emissions (7.6 % increase per IQR increase in vanadium, 95 % CI: 0.1, 15.8). Elevated FeNO was also suggested for other metals on the day after the exposure: 10.3 % increase per IQR increase in aluminium (95 % CI: 4.2, 16.6) and 7.5 % increase per IQR increase in iron (95 % CI: 1.5, 13.9) at a 1-day lag period.

CONCLUSIONS

Exposures to ambient PM2.5 containing trace metals that are markers of traffic and industrial-derived emissions were associated in asthmatic children with an enhanced FeNO response.

Emergency Department Visits for Asthma Exacerbation due to Weather Conditions and Air Pollution in Chuncheon, Korea: A Case-Crossover Analysis

Purpose

This retrospective study was conducted to estimate the effects of climate factors and air pollution on asthma exacerbations using a case-crossover analysis.

Methods

Patients who visited the emergency department (ED) of 2 university hospitals in Chuncheon for asthma exacerbations from January 1, 2006, to December 31, 2011, were enrolled. Daily average data for meteorological factors (temperature, daily temperature range, relative humidity, wind speed, atmospheric pressure, presence of rain, solar irradiation, and presence of fog) and the daily average levels of gaseous air pollutants (SO₂, NO₂, O₃, CO, and PM₁₀) were obtained. A case-crossover analysis was performed using variables about the weather and air pollution at 1-week intervals between cases and controls before and after ED visits.

Results

There were 660 ED visits by 583 patients with asthma exacerbations. Low relative humidity (lag 1 and 2) and high wind speed (lag 1, 2, and 3) were associated with ED visits for asthma. Fog (lag 2) showed protective effects against asthma exacerbations in Chuncheon (risk increase: -29.4% [95% CI=-46.3% to -7.2%], P=0.013). These relationships were stronger in patients ≤19 years old than in those >60 years old. High levels of ambient CO (lag 1, 2, and 3) and NO₂ (lag 2 and 3) were associated with decreased ED visits for asthma. However, there were no significant relationships among levels of ambient CO or NO₂ and asthma exacerbations after adjusting for wind speed and relative humidity.

Conclusions

High wind speed and low humidity were associated with an increased risk of asthma ED visits. Fog was associated with a decreased risk of asthma ED visits after controlling for seasonal variations in weather and air pollution.

Environmental NO2 and CO Exposure: Ignored Factors Associated with Uremic Pruritus in Patients Undergoing Hemodialysis

Uremic pruritus (UP), also known as chronic kidney disease-associated pruritus, is a common and disabling symptom in patients undergoing maintenance hemodialysis (MHD). The pathogenesis of UP is multifactorial and poorly understood. Outdoor air pollution has well-known effects on the health of patients with allergic diseases through an inflammatory process. Air pollution-induced inflammation could occur in the skin and aggravate skin symptoms such as pruritus or impair epidermal barrier function. To assess the role of air pollutants, and other clinical variables on uremic pruritus (UP) in HD patients, we recruited 866 patients on maintenance HD. We analyzed the following variables for association with UP: average previous 12-month and 24-month background concentrations for nitrogen dioxide (NO2) and carbon monoxide (CO), and suspended particulate matter of <2.5 μm (PM2.5). In a multivariate logistic regression, hemodialysis duration, serum ferritin levels, low-density lipoprotein levels, and environmental NO2/CO levels were positively associated with UP, and serum albumin levels were negatively associated with UP. This cross-sectional study showed that air pollutants such as NO2 and CO might be associated with UP in patients with MHD.

Inhaled SiO2 nanoparticles blunt cold-exposure-induced WAT-browning and metabolism activation in white and brown adipose tissue

Concern has been growing over the potential hazard of nanoparticles to human health because of increasing ambient particulate air pollution. Much research has been performed on the toxicology of nanoparticles to organs. Meanwhile, particles floating in air, particularly in winter, are more serious. Thus, the purpose of this study was to evaluate the effect of nanoparticles and cold on human health. There is little research on the effects of nanoparticles on energy metabolism. The composition of particulate matter is complicated; however, silicon in particles accounts for a significant proportion. Adipose tissue is the main organ that produces heat and maintains the body temperature in a cold environment. White adipose tissue (WAT) stores energy in the form of triacylglycerol, whereas brown adipose tissue (BAT) dissipates energy in the form of heat to maintain the body temperature. This article presents the effect of air ultra-particles and cold on the WAT and BAT. In vivo, Sprague-Dawley rats were divided into four groups: exposed to the same deposited doses of silicon dioxide (SiO₂) nanoparticles (NPs) by intratracheal instillation or/and cold exposure at 4 °C, 4 h per day for four weeks. Cold exposure induced weight loss and WAT browning, as indicated by pathology, transmission electron microscopy (TEM), upregulated mRNA levels of BAT and WAT specific genes and molecular switches. Intratracheal instillation of nano-SiO₂ induced a slowdown in metabolism, weight gain and inhibited WAT browning, as indicated by the downregulated mRNA levels of BAT and WAT marker genes and molecular switches. This study provided direct evidence that SiO₂ NPs might inhibit the effect of cold-induced white/brown adipose tissue changes in plasticity and metabolism.

Diesel exhaust: current knowledge of adverse effects and underlying cellular mechanisms

Diesel engine emissions are among the most prevalent anthropogenic pollutants worldwide, and with the growing popularity of diesel-fueled engines in the private transportation sector, they are becoming increasingly widespread in densely populated urban regions. However, a large number of toxicological studies clearly show that diesel engine emissions profoundly affect human health. Thus the interest in the molecular and cellular mechanisms underlying these effects is large, especially concerning the nature of the components of diesel exhaust responsible for the effects and how they could be eliminated from the exhaust. This review describes the fundamental properties of diesel exhaust as well as the human respiratory tract and concludes that adverse health effects of diesel exhaust not only emerge from its chemical composition, but also from the interplay between its physical properties, the physiological and cellular properties, and function of the human respiratory tract. Furthermore, the primary molecular and cellular mechanisms triggered by diesel exhaust exposure, as well as the fundamentals of the methods for toxicological testing of diesel exhaust toxicity, are described. The key aspects of adverse effects induced by diesel exhaust exposure described herein will be important for regulators to support or ban certain technologies or to legitimate incentives for the development of promising new technologies such as catalytic diesel particle filters.

Effect of GST variants on lung function following diesel exhaust and allergen co-exposure in a controlled human crossover study

BACKGROUND

Isolated exposure to diesel exhaust (DE) or allergen can cause decrements in lung function that are impacted by the presence of genetic variants in the glutathione-S-transferase (GST) family but the effect of GST interactions with DE-allergen co-exposure on lung function is unknown. We aimed to assess the impact of DE and allergen co-exposure on lung function and the influence of GSTM1 or GSTT1 variation

METHODS

We used a blinded crossover study design with 17 atopic subjects exposed to filtered air (FA; the control for DE) or DE for 2h. One hour following each exposure to DE or FA, bronchoscopy was performed to deliver a diluent-controlled segmental allergen challenge (SAC). Methacholine challenge and forced expiratory volume in 1s (FEV1) was performed pre-exposure (baseline airway responsiveness) and 24h post-exposure (effect of co-exposure). Additionally, FEV1 was performed hourly after DE/FA exposure and protein carbonyl content was measured in plasma as an oxidative stress marker.

RESULTS

Changes in FEV1 from baseline were dependent on time following allergen exposure. DE, as opposed to FA, led to a significant change in FEV1 at 2h post-allergen exposure in GSTT1 variants only (24.5±19.6% reduction in GSTT1 null individuals vs. 9.2±7.3% reduction in GSTT1 present individuals). Moreover, plasma protein carbonyl level 4h after co-exposure was higher in the individuals who have the GSTT1 null genotype.

CONCLUSIONS

This suggests a gene-environment interaction that endangers susceptible populations co-exposed to DE and allergen.

COPD and exercise: does it make a difference?

KEY POINTS

Physiological changes are observed following a structured exercise training programme in patients with COPD, without changes in resting lung function.Exercise training is the cornerstone of a comprehensive pulmonary rehabilitation programme in patients with COPD.Most comorbidities in patients referred for pulmonary rehabilitation remain undiagnosed and untreated.After careful screening, it is safe for COPD patients with comorbidities to obtain significant and clinically relevant improvements in functional exercise capacity and health status after an exercise-based pulmonary rehabilitation programme.

EDUCATIONAL AIMS

To inform readers of the positive effects of exercise-based pulmonary rehabilitation in patients with COPD, even with comorbid conditions.To inform readers of the importance of physical activity in patients with COPD. Exercise training is widely regarded as the cornerstone of pulmonary rehabilitation in patients with chronic obstructive pulmonary disease (COPD). Indeed, exercise training has been identified as the best available means of improving muscle function and exercise tolerance in patients with COPD. So, exercise training truly makes a difference in the life of patients with COPD. In this review, an overview is provided on the history of exercise training (as standalone intervention or as part of a comprehensive pulmonary rehabilitation programme), exercise training in comorbid patients with COPD, and the impact of physical activity counselling in a clean air environment.

Time-dependency of mice lung recovery after a 4-week exposure to traffic or biomass air pollutants

The time-dependency of lung recovery after 3 intranasal instillations per week during four weeks of distilled water (C groups) or particles (15μg) from traffic (U groups) or biomass burning (B groups) was observed in BALB/c mice. Lung mechanics [static elastance (Est), viscoelastic component of elastance (ΔE), lung resistive (ΔP1) and viscoelastic/inhomogeneous (ΔP2) pressures] and histology were analyzed 1 (C1, U1, B1), 2 (C2, U2, B2), 7 (C7, U7, B7) or 14 days (C14, U14, B14) after the last instillation. Est, ΔE, ΔP1 and ΔP2 were higher in U1 and B1 than in C1, returning to control values at day 2, except for ΔP1 that normalized after 7 days. Alveolar collapse, bronchoconstriction index and alveolar lesion were larger in U1 and B1 than in C1, however collapse returned to baseline at 7 days, while the others normalized in 2 days. A 4-week exposure to U and B induced lung impairment that resolved 7 days after the last exposure.

Inhalation of diesel exhaust and allergen alters human bronchial epithelium DNA methylation

BACKGROUND

Allergic disease affects 30% to 40% of the world's population, and its development is determined by the interplay between environmental and inherited factors. Air pollution, primarily consisting of diesel exhaust emissions, has increased at a similar rate to allergic disease. Exposure to diesel exhaust may play a role in the development and progression of allergic disease, in particular allergic respiratory disease. One potential mechanism underlying the connection between air pollution and increased allergic disease incidence is DNA methylation, an epigenetic process with the capacity to integrate gene-environment interactions.

OBJECTIVE

We sought to investigate the effect of allergen and diesel exhaust exposure on bronchial epithelial DNA methylation.

METHODS

We performed a randomized crossover-controlled exposure study to allergen and diesel exhaust in humans, and measured single-site (CpG) resolution global DNA methylation in bronchial epithelial cells.

RESULTS

Exposure to allergen alone, diesel exhaust alone, or allergen and diesel exhaust together (coexposure) led to significant changes in 7 CpG sites at 48 hours. However, when the same lung was exposed to allergen and diesel exhaust but separated by approximately 4 weeks, significant changes in more than 500 sites were observed. Furthermore, sites of differential methylation differed depending on which exposure was experienced first. Functional analysis of differentially methylated CpG sites found genes involved in transcription factor activity, protein metabolism, cell adhesion, and vascular development, among others.

CONCLUSIONS

These findings suggest that specific exposures can prime the lung for changes in DNA methylation induced by a subsequent insult.

Mucosal production of uric acid by airway epithelial cells contributes to particulate matter-induced allergic sensitization

Exposure to particulate matter (PM), a major component of air pollution, contributes to increased morbidity and mortality worldwide. PM induces innate immune responses and contributes to allergic sensitization, although the mechanisms governing this process remain unclear. Lung mucosal uric acid has also been linked to allergic sensitization. The links among PM exposure, uric acid, and allergic sensitization remain unexplored. We therefore investigated the mechanisms behind PM-induced allergic sensitization in the context of lung mucosal uric acid. PM10 and house dust mite exposure selectively induced lung mucosal uric acid production and secretion in vivo, which did not occur with other challenges (lipopolysaccharide, virus, bacteria, or inflammatory/fibrotic stimuli). PM10-induced uric acid mediates allergic sensitization and augments antigen-specific T-cell proliferation, which is inhibited by uricase. We then demonstrate that human airway epithelial cells secrete uric acid basally and after stimulation through a previously unidentified mucosal secretion system. Our work discovers a previously unknown mechanism of air pollution-induced, uric acid-mediated, allergic sensitization that may be important in the pathogenesis of asthma.

Sirtuin 3 Protects against Urban Particulate Matter-Induced Autophagy in Human Bronchial Epithelial Cells

Urban particulate matter (urban PM) is a heterogeneous mixture of various types of particles originating from different sources. Exposure to high concentrations of urban PM leading to adverse health effects is evaluated by using in vitro cultures of human lung epithelial cells. However, the mechanism underlying the correlation between high concentrations of urban PM exposure and adverse health effects has not been fully elucidated; urban PM-induced oxidative stress is considered as an important mechanism of urban PM-mediated cytotoxicity. Sirtuin 3 (SIRT3), a primary mitrochondrial deacetylase, controls cellular reactive oxygen species (ROS) production, and expression of antioxidant enzymes. In this study, we examined the role of SIRT3 in the regulation of urban PM-induced oxidative stress in normal primary human bronchial epithelial cells (HBEpiCs). Cell viability showed a time- and concentration-dependent decrease when exposed to urban PM, which could indicate that the amount of lactate dehydrogenase released from the cell in response to urban PM is related to cell viability in HBEpiC. The effects of urban PM on morphological and biochemical markers of autophagy in HBEpiC were analyzed by electron microscopy and Western blotting. Overexpression of SIRT3 inhibited urban PM-induced ROS generation, while concomitantly increasing the expression of antioxidant enzymes, and decreasing NF-κB activation and release of inflammation factors. Up-regulation of SIRT3 significantly inhibited the expression of autophagy markers and autophagic vacuole formation. Our findings provide a valuable insight into the potential role of the SIRT3 enzyme in regulating urban PM-induced autophagy by mediating urban PM-induced oxidative stress, which may contribute to urban PM-induced impairment of airway epithelial cell function.

Controlled diesel exhaust and allergen coexposure modulates microRNA and gene expression in humans: Effects on inflammatory lung markers

BACKGROUND

Air pollution's association with asthma may be due to its augmentation of allergenic effects, but the role of microRNA (miRNA) and gene expression in this synergy is unknown.

OBJECTIVE

We sought to determine whether exposure to allergen, exposure to diesel exhaust (DE), or coexposures modulate miRNA, gene expression, or inflammatory pathways and whether these measurements are correlated.

METHODS

Fifteen participants with atopy completed this controlled study of 2 hours of filtered air or DE (300 μg PM_2.5/m³) exposure, followed by saline-controlled segmental bronchial allergen challenge. Gene and miRNA expression in bronchial brushings and lung inflammatory markers were measured 48 hours later, in study arms separated by approximately 4 weeks. Expression of miRNAs, messenger RNAs, and inflammatory markers and their interrelationships were determined using regression.

RESULTS

Robust linear models indicated that DE plus saline and DE plus allergen significantly modulated the highest number of miRNAs and messenger RNAs, respectively, relative to control (filtered air plus saline). In mixed models, allergen exposure modulated (q ≤ 0.2) miRNAs including miR-183-5p, miR-324-5p, and miR-132-3p and genes including NFKBIZ and CDKN1A, but DE did not significantly modify this allergenic effect. Repression of CDKN1A by allergen-induced miR-132-3p may contribute to shedding of bronchial epithelial cells.

CONCLUSIONS

Expression of specific miRNAs and genes associated with bronchial immune responses were significantly modulated by DE or allergen. However, DE did not augment the effect of allergen at 48 hours, suggesting that adjuvancy may be transient or require higher or prolonged exposure. In silico analysis suggested a possible mechanism contributing to epithelial wall damage following allergen exposure.

Acute effects on pulmonary function in young healthy adults exposed to traffic-related air pollution in semi-closed transport hub in Beijing

OBJECTIVES

Transport hub is an important part of urban comprehensive transportation system. Traffic-related air pollution can reach high level because of difficulty of diffusion and increase of emission in transport hub. However, whether exposure in this semi-closed traffic micro-environment causes acute changes in pulmonary function of commuters still needs to be explored.

METHODS

Forty young healthy adults participated in this randomized, crossover study. Each participant underwent 2 h exposure in a designated transport hub and, on a separate occasion, in an appointed park. Personal exposures to fine particulate matter (PM_2.5), black carbon (BC) and carbon monoxide (CO) were measured. Forced expiratory volume in 1 s (FEV₁) and peak expiratory flow (PEF) were assessed pre-, during and post-exposure. Mixed linear models were used to analyze the pulmonary effects of traffic-related air pollutants.

RESULTS

Participants had significantly higher exposures to PM_2.5, BC and CO in the transport hub than in the park. Exposure in transport hub induced significant reductions in FEV₁ and PEF compared with the park during exposure 1 and 2 h. The reductions were significant associated with traffic-related air pollutants. For instance, per 10 μg/m³ increment in PM_2.5 was associated with -0.15 % (95 % CI -0.28, -0.02 %) reduction in FEV₁ during exposure 2 h. However, effects became attenuate after 2 h exposure.

CONCLUSIONS

Short-term exposure in transport hub had acute reduction effects on pulmonary function. More attention should be paid to the health effects of exposure in the semi-closed traffic micro-environment.

Effect of Asian dust on pulmonary function in adult asthma patients in western Japan: A panel study

BACKGROUND

Asian dust (AD) has become a major health concern. The concentration of AD is typically expressed in particulate matter less than 10 μm (PM10) and 2.5 μm (PM2.5). However, PM10 and PM2.5 consist of various substances besides AD. Light detection and ranging (LIDAR) systems can selectively measure the quantity of AD particles to distinguish non-spherical airborne particles from spherical airborne particles. The objective of this study was to investigate the relationship between pulmonary function in adult asthma patients and AD using LIDAR data.

METHODS

Subjects were 231 adult asthma patients who had their morning peak expiratory flow (PEF) measured from March to May 2012. A linear mixed model was used to estimate the association of PEF with sand dust particles detected by LIDAR.

RESULTS

Increases in the interquartile range of AD particles (0.018 km(-1)) led to changes in PEF of -0.42 L/min (95% confidence interval [CI], -0.85 to 0.01). An increase of 11.8 μg/m(3) in suspended particulate matter and 6.9 μg/m(3) in PM2.5 led to decreases of -0.17 L/min (-0.53 to 0.21) and 0.03 L/min (-0.35 to 0.42), respectively. A heavy AD day was defined as a day with a level of AD particles >0.032 km(-1), which was the average plus one standard deviation during the study period, and six heavy AD days were identified. Change in PEF after a heavy AD day was -0.97 L/min (-1.90 to -0.04).

CONCLUSIONS

Heavy exposure to AD particles was significantly associated with decreased pulmonary function in adult asthma patients.

Pathogenesis and prevention strategies of severe asthma exacerbations in children

PURPOSE OF REVIEW

Exacerbations of asthma in children are most frequently precipitated by respiratory infections with a seasonal pattern. However, management takes little account of the underlying infective or other precipitant abnormality.

RECENT FINDINGS

Interactions between environmental triggers, the airway microbiome and innate immune responses are key determinants of exacerbations. Elevated innate cytokines interleukin (IL)-33 and IL-25, and abnormal molecular responses in the interferon pathway are associated with rhinoviral infections. Exacerbations caused by fungal allergens also induce IL-33, highlighting this as an attractive therapeutic target. An equal contribution of bacterial and viral infection during exacerbations, particularly in preschool children, has become increasingly apparent, but some organisms may be protective. Investigation of mechanisms underlying infection-related exacerbations especially in preschool children is needed.Progressive loss of lung function from exacerbations is most pronounced in children aged 6-11 years, and low FEV1 is now recognized as a key predictor for the development of chronic obstructive pulmonary disease and premature death. Although prevention of exacerbations is critical, suboptimal patient education, prescription and adherence to maintenance therapy, and a lack of predictive biomarkers, remain key unaddressed issues in children.

SUMMARY

Precipitants and predictors of exacerbations, together with the child's age and clinical phenotype, need to be used to achieve individualized management in preference to the current uniform approach for all.

H3K9 acetylation change patterns in rats after exposure to traffic-related air pollution

Traffic-related air pollution (TRAP) has been acknowledged as a potential risk factor for numerous respiratory disorders including lung cancer; however, the exact mechanisms involved are still unclear. Here we investigated the effects of TRAP exposure on the H3K9 acetylation in rats. The exposure was performed in both spring and autumn with identical study procedures. In each season, 48 healthy Wistar rats were exposed to different levels of TRAP for 4 h, 7 d, 14 d, and 28 d, respectively. H3K9 acetylation levels in both the peripheral blood mononuclear cells (PBMCs) and lung tissues were quantified. Multiple linear regression was applied to assess the influence of air pollutants on H3K9 acetylation levels. The levels of PM2.5, PM10, and NO2 in the tunnel and crossroad groups were significantly higher than in the control group. The H3K9 acetylation levels were not significantly different between spring and autumn. When spring and autumn data were analyzed together, no significant association between the TRAP and H3K9 acetylation was found in 4h exposure window. However, in the 7 d exposure window, PM2.5 and PM10 exposures were associated with changes in H3K9 acetylation ranging from 0.276 (0.053, 0.498) to 0.475 (0.103, 0.848) per 1 μg/m(3) increase in the pollutant concentration. In addition, prolonged exposure of the rats in the tunnel showed that both PM2.5 and PM10 concentrations were positively associated with H3k9 acetylation in both PBMCs and lung tissues. The findings showed that 7-d and prolonged TRAP exposure could effectively increase the H3K9 acetylation level in both PBMCs and lung tissues of rats.

Long-term exposure to diesel engine exhaust affects cytokine expression among occupational population

Diesel engine exhaust (DEE) is a predominant contributor to urban air pollution. The International Agency for Research on Cancer classified DEE as a group I carcinogen. Inflammatory response is considered to be associated with various health outcomes including carcinogenesis. However, human data linking inflammation with long-term DEE exposure are still lacking. In this study, a total of 137 diesel engine testing workers with an average exposure of 8.2 years and 108 unexposed controls were enrolled. Peripheral blood samples were collected from all subjects, and the association of DEE exposure with inflammatory biomarkers was analyzed. Overall, DEE exposed workers had a significant increase in the C-reactive protein (CRP) and a significant decrease in cytokines including interleukin (IL)-1β, IL-6, IL-8, and macrophage inflammatory protein (MIP)-1β compared to controls after adjusting for age, BMI, smoking status, and alcohol use, and findings were highly consistent when stratified by smoking status. In addition, exposure time dependent patterns for IL-6 and CRP were also found (Ptrend = 0.006 and 0.026, respectively); however, the levels of IL-1β and MIP-1β were significantly lower in subjects with a DEE working time of less than 10 years compared with the controls and then recovered to control levels in workers exposed for >10 years. There were no significant differences in blood cell counts and major lymphocyte subsets between exposed workers and the controls. Our results provide epidemiological evidence for the relationship between DEE exposure and immunotoxicity considering the important roles of cytokines in immunological processes.

Health effects of smoke from planned burns: a study protocol

Background

Large populations are exposed to smoke from bushfires and planned burns. Studies investigating the association between bushfire smoke and health have typically used hospital or ambulance data and been done retrospectively on large populations. The present study is designed to prospectively assess the association between individual level health outcomes and exposure to smoke from planned burns.

Methods/design

A prospective cohort study will be conducted during a planned burn season in three locations in Victoria (Australia) involving 50 adult participants who undergo three rounds of cardiorespiratory medical tests, including measurements for lung inflammation, endothelial function, heart rate variability and markers of inflammation. In addition daily symptoms and twice daily lung function are recorded. Outdoor particulate air pollution is continuously measured during the study period in these locations. The data will be analysed using mixed effect models adjusting for confounders.

Discussion

Planned burns depend on weather conditions and dryness of ‘fuels’ (i.e. forest). It is potentially possible that no favourable conditions occur during the study period. To reduce the risk of this occurring, three separate locations have been identified as having a high likelihood of planned burn smoke exposure during the study period, with the full study being rolled out in two of these three locations. A limitation of this study is exposure misclassification as outdoor measurements will be conducted as a measure for personal exposures. However this misclassification will be reduced as participants are only eligible if they live in close proximity to the monitors.