Indoor particulate matter exposure is associated with increased black carbon content in airway macrophages of former smokers with COPD

Biomarkers of the relationship of particulate matter exposure with the progression of chronic respiratory diseases

A high level of particulate matter (PM) in air is correlated with the onset and development of chronic respiratory diseases. We conducted a systematic literature review, searching the MEDLINE, EMBASE, and Cochrane databases for studies of biomarkers of the effect of PM exposure on chronic respiratory diseases and the progression thereof. Thirty-eight articles on biomarkers of the progression of chronic respiratory diseases after exposure to PM were identified, four of which were eligible for review. Serum, sputum, urine, and exhaled breath condensate biomarkers of the effect of PM exposure on chronic obstructive pulmonary disease (COPD) and asthma had a variety of underlying mechanisms. We summarized the functions of biomarkers linked to COPD and asthma and their biological plausibility. We identified few biomarkers of PM exposure-related progression of chronic respiratory diseases. The included studies were restricted to those on biomarkers of the relationship of PM exposure with the progression of chronic respiratory diseases. The predictive power of biomarkers of the effect of PM exposure on chronic respiratory diseases varies according to the functions of the biomarkers.

Activation of epithelial and inflammatory pathways in adolescent elite athletes exposed to intense exercise and air pollution

RATIONALE

Participation in high-intensity exercise in early life might act as stressor to the airway barrier.

OBJECTIVES

To investigate the effect of intense exercise and associated exposure to air pollution on the airway barrier in adolescent elite athletes compared with healthy controls and to study exercise-induced bronchoconstriction (EIB) in this population.

METHODS

Early-career elite athletes attending 'Flemish-Elite-Sports-Schools' (12-18 years) of 4 different sport disciplines (n=90) and control subjects (n=25) were recruited. Presence of EIB was tested by the eucapnic voluntary hyperventilation (EVH) test. Markers at mRNA and protein level; RNA-sequencing; carbon load in airway macrophages were studied on induced sputum samples.

RESULTS

444 genes were differentially expressed in sputum from athletes compared with controls, which were related to inflammation and epithelial cell damage and sputum samples of athletes contained significantly more carbon loaded airway macrophages compared with controls (24%, 95% CI 20% to 36%, p<0.0004). Athletes had significantly higher substance P (13.3 pg/mL, 95% CI 2.0 to 19.2) and calprotectin (1237 ng/mL, 95% CI 531 to 2490) levels as well as IL-6, IL-8 and TNF-α mRNA levels compared with controls (p<0.05). The incidence of EIB in athletes was 9%. The maximal fall in forced expiratory volume in 1 s (%) after EVH test in athletes was significantly associated with prior PM10 and PM2.5 exposure.

CONCLUSION

Early-career elite athletes showed increased markers of air pollution exposure, epithelial damage and airway inflammation compared with controls. Acute exposure to increased air pollution PM10 levels was linked to increased airway hyper-reactivity.

TRIAL REGISTRATION NUMBER

NCT03587675.

Black carbon content in airway macrophages is associated with increased severe exacerbations and worse COPD morbidity in SPIROMICS

BACKGROUND

Airway macrophages (AM), crucial for the immune response in chronic obstructive pulmonary disease (COPD), are exposed to environmental particulate matter (PM), which they retain in their cytoplasm as black carbon (BC). However, whether AM BC accurately reflects environmental PM2.5 exposure, and can serve as a biomarker of COPD outcomes, is unknown.

METHODS

We analyzed induced sputum from participants at 7 of 12 sites SPIROMICS sites for AM BC content, which we related to exposures and to lung function and respiratory outcomes. Models were adjusted for batch (first vs. second), age, race (white vs. non-white), income (<$35,000, $35,000~$74,999, ≥$75,000, decline to answer), BMI, and use of long-acting beta-agonist/long-acting muscarinic antagonists, with sensitivity analysis performed with inclusion of urinary cotinine and lung function as covariates.

RESULTS

Of 324 participants, 143 were current smokers and 201 had spirometric-confirmed COPD. Modeled indoor fine (< 2.5 μm in aerodynamic diameter) particulate matter (PM2.5) and urinary cotinine were associated with higher AM BC. Other assessed indoor and ambient pollutant exposures were not associated with higher AM BC. Higher AM BC was associated with worse lung function and odds of severe exacerbation, as well as worse functional status, respiratory symptoms and quality of life.

CONCLUSION

Indoor PM2.5 and cigarette smoke exposure may lead to increased AM BC deposition. Black carbon content in AMs is associated with worse COPD morbidity in current and former smokers, which remained after sensitivity analysis adjusting for cigarette smoke burden. Airway macrophage BC, which may alter macrophage function, could serve as a predictor of experiencing worse respiratory symptoms and impaired lung function.

Inhalable microplastics prevails in air: Exploring the size detection limit

Microplastics (MPs) are ubiquitous in the environment, including the atmosphere. Yet, the size detection limit in measuring airborne MPs undermines the determination of the human MP exposure level through inhalation and also restricts the understanding of airborne MPs pollution behavior. To comprehensively and accurately assess the MPs pollution features in air, we demonstrate a qualitative and quantitively method using Raman microscopy to characterize the suspended atmospheric MPs. Our methodology has achieved detailed characterization of MPs down to 1 μm and ensured all the MPs to be counted regardless of their transparency. Further, a case study of indoor and outdoor samples from eight sampling sites were conducted in Shanghai, China. Inhalable MPs prevails in all samples with higher concentrations occur indoors. Indoor MPs varied strongly in composition compare to outdoor. Ventilation played an important role in lowering indoor MPs concentrations, and MPs in better ventilated indoors displayed similar distribution patterns as outdoors. MPs detected were mainly Polyethylene, Polyester, Phenolic Resin and Polyvinyl chloride. 77% of the Polyethylene detected were transparent films, suggesting the fragmentation from PE film products, such as plastic bags and cling films. Our work confirmed the widespread existences of inhalable MPs in air and provides solid foundations for future studies to understand the realistic MPs exposure conditions through inhalation.

Determinants of carbon load in airway macrophages in pregnant women

The airway macrophages carbon loading (AMCL) has been suggested to be a biomarker of the long-term exposure to air pollution; however, to date no study has characterized AMCL for the pregnancy period. Therefore, this study aimed to assess the determinants of AMCL during pregnancy in Iran, a middle-income country. This study was based on a sample of 234 pregnant women with term and normal vaginal delivery who were residing in Sabzevar, Iran (2019). We characterized 35 potential determinants of personal exposure to air pollution for each participant, including six personal, nine indoor, and 20 home-outdoor factors. We applied Deletion/Substitution/Addition algorithm to identify the most relevant determinants that could predict AMCL levels. The median (IQR) of AMCL level was 0.12 (0.30) μm² with a successful sputum induction in 82.9% (194) of participants. Ambient residential PM_2.5 levels were positively associated with higher AMCL levels. On the other hand, increased residential distance to the traffic lights, squares and ring-roads, the duration of opening window per day, and opening window during cooking were inversely associated with AMCL levels. Our findings provide novel insights on the different personal, indoor, and outdoor determinants of personal exposure to air pollution during pregnancy in a middle-income country.

Evaluating carbon content in airway macrophages as a biomarker of personal exposure to fine particulate matter and its acute respiratory effects

It remains unclear whether carbon content in airway macrophages (AM) can predict personal short-term exposure to fine particulate matter (PM_2.5) air pollution and its respiratory health effects. We aimed to evaluate the pathway from personal PM_2.5 exposure to adverse respiratory outcomes through AM carbon content. We designed a longitudinal panel study with 3 scheduled follow-ups among 113 non-smoking patients of chronic obstructive pulmonary disease in Shanghai, China, from April 2017 to January 2019. We quantified AM carbon content from induced sputum by image analysis, tested lung function and measured sputum levels of 4 pro-inflammatory cytokines and 2 anti-inflammatory cytokines. We applied the "meet in the middle" approach incorporating linear mixed-effect models to evaluate the associations from external PM_2.5 exposure to respiratory outcomes through AM carbon content. Our results indicated that personal exposure to PM_2.5 within 24 h was significantly associated with decreased forced expiratory volume in 1s and anti-inflammatory cytokines, as well as increased macrophages and pro-inflammatory cytokines. These changes were accompanied by increased areas of AM carbon and higher percentage of AM area occupied by carbon, both of which were associated with increased levels of pro-inflammatory cytokines and decreased levels of anti-inflammatory cytokines. Exposure to ambient black carbon and organic carbon in PM_2.5 within 2 days was significantly associated with increased AM carbon area and percentage of AM area occupied by carbon. Our findings reinforced the causality in respiratory health effects of PM_2.5 in which increased AM carbon content might serve as a valid exposure biomarker.

DNA methylome-based validation of induced sputum as an effective protocol to study lung immunity: construction of a classifier of pulmonary cell types

Flow cytometry is a classical approach used to define cell types in peripheral blood. While DNA methylation signatures have been extensively employed in recent years as an alternative to flow cytometry to define cell populations in peripheral blood, this approach has not been tested in lung-derived samples. Here, we compared bronchoalveolar lavage with a more cost-effective and less invasive technique based on sputum induction and developed a DNA methylome-based algorithm that can be used to deconvolute the cell types in such samples. We analysed the DNA methylome profiles of alveolar macrophages and lymphocytes cells isolated from the pulmonary compartment. The cells were isolated using two different methods, sputum induction and bronchoalveolar lavage. A strong positive correlation between the DNA methylome profiles of cells obtained with the two isolation methods was found. We observed the best correlation of the DNA methylomes when both isolation methods captured cells from the lower parts of the lungs. We also identified unique patterns of CpG methylation in DNA obtained from the two cell populations, which can be used as a signature to discriminate between the alveolar macrophages and lymphocytes by means of open-source algorithms. We validated our findings with external data and obtained results consistent with the previous findings. Our analysis opens up a new possibility to identify different cell populations from lung samples and promotes sputum induction as a tool to study immune cell populations from the lung.

Small Airway Wall Thickening Assessed by Computerized Tomography Is Associated With Low Lung Function in Chinese Carbon Black Packers

Nanoscale carbon black as virtually pure elemental carbon can deposit deep in the lungs and cause pulmonary injury. Airway remodeling assessed using computed tomography (CT) correlates well with spirometry in patients with obstructive lung diseases. Structural airway changes caused by carbon black exposure remain unknown. Wall and lumen areas of sixth and ninth generations of airways in 4 lobes were quantified using end-inhalation CT scans in 58 current carbon black packers (CBPs) and 95 non-CBPs. Carbon content in airway macrophage (CCAM) in sputum was quantified to assess the dose-response. Environmental monitoring and CCAM showed a much higher level of elemental carbon exposure in CBPs, which was associated with higher wall area and lower lumen area with no change in total airway area for either airway generation. This suggested small airway wall thickening is a major feature of airway remodeling in CBPs. When compared with wall or lumen areas, wall area percent (WA%) was not affected by subject characteristics or lobar location and had greater measurement reproducibility. The effect of carbon black exposure status on WA% did not differ by lobes. CCAM was associated with WA% in a dose-dependent manner. CBPs had lower FEV1 (forced expiratory volume in 1 s) than non-CBPs and mediation analysis identified that a large portion (41-72%) of the FEV1 reduction associated with carbon black exposure could be explained by WA%. Small airway wall thickening as a major imaging change detected by CT may underlie the pathology of lung function impairment caused by carbon black exposure.

Modeling residential indoor concentrations of PM2.5 , NO2 , NOx , and secondhand smoke in the Subpopulations and Intermediate Outcome Measures in COPD (SPIROMICS) Air study

Increased outdoor concentrations of fine particulate matter (PM_2.5 ) and oxides of nitrogen (NO₂ , NO_x ) are associated with respiratory and cardiovascular morbidity in adults and children. However, people spend most of their time indoors and this is particularly true for individuals with chronic obstructive pulmonary disease (COPD). Both outdoor and indoor air pollution may accelerate lung function loss in individuals with COPD, but it is not feasible to measure indoor pollutant concentrations in all participants in large cohort studies. We aimed to understand indoor exposures in a cohort of adults (SPIROMICS Air, the SubPopulations and Intermediate Outcome Measures in COPD Study of Air pollution). We developed models for the entire cohort based on monitoring in a subset of homes, to predict mean 2-week-measured concentrations of PM_2.5 , NO₂ , NO_x , and nicotine, using home and behavioral questionnaire responses available in the full cohort. Models incorporating socioeconomic, meteorological, behavioral, and residential information together explained about 60% of the variation in indoor concentration of each pollutant. Cross-validated R² for best indoor prediction models ranged from 0.43 (NO_x ) to 0.51 (NO₂ ). Models based on questionnaire responses and estimated outdoor concentrations successfully explained most variation in indoor PM_2.5 , NO₂ , NO_x , and nicotine concentrations.

Chronic exposure to diesel exhaust may cause small airway wall thickening without lumen narrowing: a quantitative computerized tomography study in Chinese diesel engine testers

Background

Diesel exhaust (DE) is a major source of ultrafine particulate matters (PM) in ambient air and contaminates many occupational settings. Airway remodeling assessed using computerized tomography (CT) correlates well with spirometry in patients with obstructive lung diseases. Structural changes of small airways caused by chronic DE exposure is unknown. Wall and lumen areas of 6th and 9th generations of four candidate airways were quantified using end-inhalation CT scans in 78 diesel engine testers (DET) and 76 non-DETs. Carbon content in airway macrophage (CCAM) in sputum was quantified to assess the dose-response relationship.

Results

Environmental monitoring and CCAM showed a much higher PM exposure in DETs, which was associated with higher wall area and wall area percent for 6th generation of airways. However, no reduction in lumen area was identified. No study subjects met spirometry diagnosis of airway obstruction. This suggested that small airway wall thickening without lumen narrowing may be an early feature of airway remodeling in DETs. The effect of DE exposure status on wall area percent did not differ by lobes or smoking status. Although the trend test was of borderline significance between categorized CCAM and wall area percent, subjects in the highest CCAM category has a 14% increase in wall area percent for the 6th generation of airways compared to subjects in the lowest category. The impact of DE exposure on FEV1 can be partially explained by the wall area percent with mediation effect size equal to 20%, P_perm = 0.028).

Conclusions

Small airway wall thickening without lumen narrowing may be an early image feature detected by CT and underlie the pathology of lung injury in DETs. The pattern of changes in small airway dimensions, i.e., thicker airway wall without lumen narrowing caused by occupational DE exposure was different to that (i.e., thicker airway wall with lumen narrowing) seen in our previous study of workers exposed to nano-scale carbon black aerosol, suggesting constituents other than carbon cores may contribute to such differences. Our study provides some imaging indications of the understanding of the pulmonary toxicity of combustion derived airborne particulate matters in humans.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12989-021-00406-1.

Household solid fuel use and peak expiratory flow in middle-aged and older adults in China: A large cohort study (2011-2015)

Indoor air pollution caused by solid fuel use in cooking and heating in China is common. The relationship between household solid fuel use and peak expiratory flow (PEF) in middle-aged and older adults in China has not been clarified. The aim of this study was to assess the relationship between long-term household solid fuel use (clean for both cooking and heating, solid for either cooking or heating, and solid for both cooking and heating) and PEF changes in middle-aged and older adults using a nationally representative prospective cohort. Covariance analysis was used to compare PEF changes in different indoor air pollution exposure groups. Separate analysis of cooking and heating as well as sub-group analyses by age, sex and smoking status were conducted, linear mixed growth model analysis was used to evaluate the association between cooking fuel type and PEF. A total of 6818 participants were enrolled in the cohort analysis. Results revealed that solid fuel use in cooking and heating separately or conjointly were associated with reduced PEF (solid fuel use in cooking: least square mean [LSM] = 19.9, 95% confidence interval [CI]: 11.5-28.2, P = 0.03; solid fuel use in heating: LSM = 19.4, 95% CI:11.2-27.5, P = 0.04; both solid fuel use: LSM = 17.6, 95% CI: 9.3-25.9, P for trend <0.0001), especially in participants aged >65 years (LSM = -9.22, 95% CI: 27.9-69.52, P for trend <0.0001), females (LSM = -6.41, 95% CI: 19.12-6.30, P for trend <0.0001) and current or former smokers (LSM = -21.55, 95% CI: 36.14 to -6.97, P < 0.02). Compared to that of participants using clean fuels for cooking, PEF of participants using solid fuels were decreased by 3.5 l/min per 2 years over a 4-year follow-up. This cohort study highlights the adverse effects of indoor air pollution on lung function in middle aged and older adults in China.

Black Carbon Content in Airway Macrophages is Associated with Reduced CD80 Expression and Increased Exacerbations in Former Smokers With COPD

BACKGROUND

Chronic obstructive pulmonary disease (COPD) is characterized by recurrent exacerbations. Macrophages play a critical role in immune response and tissue repair in COPD. Airway macrophages (AM) are exposed to environmental exposures which are retained in the cytoplasmic material. Both biomass and particulate matter have been linked to higher AM black carbon. It is unknown if AM black carbon is associated with COPD morbidity and macrophage phenotype.

METHODS

Former smokers with COPD were enrolled and sputum induction was performed to obtain airway macrophages. Macrophages underwent black carbon quantification and flow cytometry phenotyping. Health information was obtained the same day as sputum induction and prospective exacerbations were assessed by monthly telephone calls.

RESULTS

We studied 30 former smokers with COPD who had a mean age of 67 years and mean forced expiratory volume in 1 second (FEV1)% predicted of 60.8%. Higher AM black carbon content was associated with increased total exacerbations and severe exacerbations and reduced CD80 expression.

CONCLUSION

AM black carbon association with respiratory morbidity is largely unexplored and this is the first study to identify association with prospective exacerbations. Macrophages expressed reduced CD80, a surface marker providing costimulatory signals required for development of antigen-specific immune responses. Our findings suggest that reduced CD80 expression is the pathophysiologic mechanism for the association of AM black carbon content and increased exacerbations. Therefore, beyond solely serving as a marker for increased exposures, AM black carbon content may be a predictor of future exacerbations given a macrophage less equipped to respond to an acute infectious exposure.

Dust Events and Indoor Air Quality in Residential Homes in Kuwait

Kuwait is a developed Middle Eastern country that is impacted by frequent dust storms from regional and/or remote deserts. The effectiveness of keeping homes tightly closed during these events to reduce dust exposures was assessed using indoor and outdoor particle samples at 10 residences within the metropolitan Kuwait City area. Specifically, this study compared indoor and outdoor levels of black carbon and 19 trace elements (Na, Mg, Al, Si, S, Cl, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Br, Sr, and Zr) during dust and non-dust events and found that particle penetration efficiencies were lower during dust storm events (less than 20–30%) than during non-dust storm events (40–60%). Coarse particles had lower penetration efficiency compared to fine particles, which is due to differences in infiltration rates and settling velocities between these two size fractions. Our findings suggest that increasing home insulation could be an effective strategy to reduce indoor exposure to crustal particles from dust storm events in residential houses of Kuwait City.

Carbon content in airway macrophages and genomic instability in Chinese carbon black packers

Carbon black (CB) particulates as virtually pure elemental carbon can deposit deep in the lungs of humans. International Agency for Research on Cancer classified CB as a Group 2B carcinogen due to inconclusive human evidence. A molecular epidemiological study was conducted in an established cohort of CB packers (CBP) to assess associations between CB exposure and genomic instability in peripheral lymphocytes using cytokinesis-block micronucleus assay (CBMN). Carbon content in airway macrophages (CCAM) was quantified as a bio-effective dosimeter for chronic CB exposure. Dose-response observed in CBPs was compared to that seen in workers exposed to diesel exhaust. The association between CB exposure status and CBMN endpoints was identified in 85 CBPs and 106 non-CBPs from a 2012 visit and replicated in 127 CBPs and 105 non-CBPs from a 2018 visit. The proportion of cytoplasm area occupied by carbon particles in airway macrophages was over fivefold higher in current CBPs compared to non-CBPs and was associated with CBMN endpoints in a dose-dependent manner. CB aerosol and diesel exhaust shared the same potency of inducing genomic instability in workers. Circulatory pro-inflammatory factors especially TNF-α was found to mediate associations between CB exposure and CBMN endpoints. In vitro functional validation supported the role of TNF-α in inducing genomic instability. An estimated range of lower limits of benchmark dose of 4.19-7.28% of CCAM was recommended for risk assessment. Chronic CB exposure increased genomic instability in human circulation and this provided novel evidence supporting its reclassification as a human carcinogen.

TAK1 knock-down in macrophage alleviate lung inflammation induced by black carbon and aged black carbon

Black carbon (BC) can combine with organic matter and form secondary pollutants known as aged BC. BC and aged BC can cause respiratory system inflammation and induce lesions at relevant sites, but the underlying mechanism has remained unknown. To gain insight into the potential mechanisms, we focused on macrophages and transforming growth factor β-activated kinase 1 (TAK1) which are a crucial factor in inflammation. Our research aims to determine the role of TAK1 in macrophages in pulmonary inflammation induced by particulate matter. In this study, BC and 1,4-naphthoquinone were mixed to model aged BC (1,4NQ-BC) in atmosphere. BC induced mice lung inflammation model, lung macrophage knock-down TAK1 animal model and primary macrophage knock-down TAK1 model were used to explore whether TAK1 in macrophage is a critical role in the process of inflammation. The results showed that the expressions of inflammatory cytokines (IL-1β, IL-6, IL-33) mRNA were significantly increased and the phosphorylation of MAPK and NF-κB signaling pathway related proteins were enhanced in RAW 264.7 cell lines. In vivo studies revealed that the indicators of pulmonary inflammation (pathology, inflammatory cell numbers) and related cytokines (IL-1β, IL-6, IL-33) mRNA expressions in CD11c-Map3k7^-/- animals were significantly lower than wild-type animals after mice were instilled particles. In mice primary macrophages, the expressions of IL-6, IL-33 mRNA were inhibited after TAK1 gene was knock-down. These results unequivocally demonstrated that TAK1 plays a crucial role in BC induced lung inflammation in mice, and we can infer that BC and 1,4NQ-BC cause these inflammatory responses by stimulating pulmonary macrophages.

Urinary lead in relation to combustion-derived air pollution in urban environments. A longitudinal study of an international panel

BACKGROUND

Urinary lead (Pb) is generally considered to have limited use in biomonitoring environmental exposure to lead. Carbon load in airway macrophages (AM BC) is an internal marker to assess long-term exposure to combustion-derived aerosol particles. In urban environments, atmospheric Pb and black carbon may have common sources. We aimed to study the temporal change of urinary Pb (U-Pb) when exposure to outdoor air pollution changes, and the relationship between U-Pb and AM BC.

METHODS

A panel of 50 young healthy adults [mean (SD) 26.7 (5.2) years], including 17 long-term (>1 year) residents in Leuven, Belgium (BE), 15 and 18 newcomers (arrived <3 weeks) from low- and middle-income countries (LMIC) and high-income countries (HIC), respectively, underwent 8 repeated measurements at 6 weeks intervals. In urine spot samples obtained at 5 time points (T1, T2, T4, T6, T8), 24 trace elements were quantified by inductively coupled plasma-mass spectrometry. At each time point, AM BC was quantified as the median surface of black inclusions (in μm²) by means of image analysis of 25 macrophages obtained by induced sputum. Changes in urinary metal concentrations (with and without creatinine correction) and the relationship between U-Pb and AM BC were estimated using linear mixed models adjusted for covariates and potential confounders.

RESULTS

Only U-Pb differed between groups and exhibited significant time trends. Participants from the LMIC group had significantly higher initial U-Pb (1.18 μg/g creat) than the HIC group (0.44 μg/g creat) and BE group (0.45 μg/g creat). In the LMIC group, U-Pb decreased significantly with time by 0.061 μg/g creatinine per 30 days [95% confidence interval (CI): 0.034, 0.088]. U-Pb remained unchanged in the other two groups. An increase in AM BC of 1 μm² was associated with an increase in U-Pb of 0.369 μg/g creat (95% CI: 0.145, 0.593).

CONCLUSION

This panel study demonstrates that U-Pb may be a valid alternative to blood Pb for biomonitoring changes in exposure to lead, at least at group level. In addition, we identified a positive association between U-Pb and AM BC, a biomarker of exposure to traffic-related air pollution, suggesting the existence of common sources of Pb and black carbon in urban environments.

Mitochondrial DNA content in blood and carbon load in airway macrophages. A panel study in elderly subjects

BACKGROUND

Mitochondria are sensitive to air pollutants due to their lack of repair capacity. Changes in mitochondrial DNA copy number (mtDNAcn) or content is a proxy of mitochondrial damage and has been associated with recent exposure to traffic-derived air pollutants, nitrogen dioxide (NO₂) and black carbon (BC). Inhaled BC can be phagocytosed by airway macrophages (AMs), and its amount in AM reflects personal exposure to traffic-related air pollution.

OBJECTIVES

The present study investigated the relation between the internal marker AM BC and ambient NO₂ concentration and examined the associations of mtDNAcn with NO₂ and AM BC.

METHODS

A panel of 20 healthy retired participants (10 couples) living in Belgium underwent repeated assessments of health and air pollution exposure at 11 time points over one year. We increased exposure contrast temporarily by moving participants for 10 days to Milan, Italy (high exposure) and to Vindeln, Sweden (low exposure). Personal exposure to NO₂ was measured during 5 consecutive days prior to each assessment time point. The amount of BC was assessed by image analysis in AMs retrieved from induced sputum collected at 7 time points. Blood mtDNAcn was determined by qPCR at each time point. Associations between AM BC and NO₂, and of mtDNAcn with NO₂ and AM BC were estimated using linear mixed effect models adjusted for covariates and potential confounders.

RESULTS

Mean concentrations of 5-day average NO₂ were higher in Milan (64 μg/m³) and lower in Vindeln (4 μg/m³) than Belgium (26 μg/m³). Each 10 μg/m³ increment in NO₂ exposure during the last 5 days was associated with 0.07 μm² (95% CI: 0.001 to 0.012) increase in median area of AM BC. A 10 μg/m³ increase in NO₂ was associated with 3.9% (95% CI: 2.2 to 5.5%) decrease in mtDNAcn. Consistently, each 1 μm² increment in median area of AM BC was associated with 24.8% (95% CI: 6.8 to 39.3%) decrease in mtDNAcn.

CONCLUSION

In this quasi-experimental setting involving moving persons to places with high and low ambient air pollution, we found changes in AM BC according to ambient air pollution levels measured during the previous 5 days. Both higher ambient NO₂ and the internal lung BC load, paralleled mitochondrial compromises as exemplified by lower mtDNA content.

Association of size-fractionated indoor particulate matter and black carbon with heart rate variability in healthy elderly women in Beijing

Associations between size-fractionated indoor particulate matter (PM) and black carbon (BC) and heart rate variability (HRV) and heart rate (HR) in elderly women remain unclear. Twenty-nine healthy elderly women were measured for 24-hour HRV/HR indices. Real-time size-fractionated indoor PM and BC were monitored on the same day and on the preceding day. Mixed-effects models were applied to investigate the associations between pollutants and HRV/HR indices. Increases in size-fractionated indoor PM were significantly associated with declines in power in the high-frequency band (HF), power in the low-frequency band (LF), and standard deviation of all NN intervals (SDNN). The largest decline in HF was 19% at 5-minute moving average for an interquartile range (IQR) increase (24 μg/m³ ) in PM_0.5 . The results showed that smaller particles could lead to greater reductions in HRV indices. The reported associations were modified by body mass index (BMI): Declines in HF at 5-minute average for an IQR increase in PM_0.5 were 34.5% and 1.0% for overweight (BMI ≥25 kg/m² ) and normal-weight (BMI <25 kg/m² ) participants, respectively. Moreover, negative associations between BC and HRV indices were found to be significant in overweight participants. Increases in size-fractionated indoor PM and BC were associated with compromised cardiac autonomic function in healthy elderly women, especially overweight ones.

The short-term effects of indoor size-fractioned particulate matter and black carbon on cardiac autonomic function in COPD patients

BACKGROUND

Previous studies have reported adverse health effects of indoor air pollutants especially particulate matter (PM) and black carbon (BC). Patients with chronic obstructive pulmonary disease (COPD) have been shown to be more likely with cardiovascular comorbidities in which cardiac autonomic dysfunction plays an important role. However, there is little evidence for the effect of indoor PM and BC exposures on cardiac autonomic function in COPD patients.

OBJECTIVES

To evaluate the association between exposure to indoor size-fractioned PM and BC and changes in HRV and HR in COPD patients.

METHODS

Forty-three doctor diagnosed, stable COPD patients were recruited and measured for 24-h HRV and HR. Real-time indoor size-fractioned PM and BC were monitored on the day before and the day of performing health measurements. Mixed-effects models were used to estimate the associations between indoor PM and BC and HRV indices and HR after controlling for potential confounders.

RESULTS

Increasing levels of size-fractioned PM and BC were associated with decreased HRV indices and increased HR. An IQR (3.14μg/m³) increase in 8-h BC moving average and an IQR (20.72μg/m³) increase in 5-min PM_0.5 moving average concentrations were associated with declines of 7.45% (95% CI: -10.89%, -3.88%) and 16.40% (95% CI: -21.06%, -11.41%) in LF, respectively. The smaller the particles size, the greater effects on HRV indices and HR. Patients' BMI modified the associations between size-fractioned PM and BC and their HRV and HR. For an IQR increase in PM_0.5, there was decline in HF of 34.85% (95% CI: -39.08%, -30.33%) in overweight patients, compared to a 2.01% (95% CI: -6.44%, 11.19%) increase in normal-weight patients.

CONCLUSIONS

Exposures to indoor PM and BC were associated with altered cardiac autonomic function in COPD patients, and the associations for HRV measures of parasympathetic activity (e.g., HF) were more apparent in overweight patients.

Carbonaceous particulate matter on the lung surface from adults living in São Paulo, Brazil

Accumulation of carbonaceous particulate matter (PM) in the lung is associated with chronic disease. The amount of carbonaceous PM in airway macrophages is reported to be associated with exposure to both fossil fuel PM and cigarette smoke. However, the contribution of these exposures to carbonaceous PM at the lung surface is unclear.

Design of the Subpopulations and Intermediate Outcome Measures in COPD (SPIROMICS) AIR Study

Introduction

Population-based epidemiological evidence suggests that exposure to ambient air pollutants increases hospitalisations and mortality from chronic obstructive pulmonary disease (COPD), but less is known about the impact of exposure to air pollutants on patient-reported outcomes, morbidity and progression of COPD.

Methods and analysis

The Subpopulations and Intermediate Outcome Measures in COPD (SPIROMICS) Air Pollution Study (SPIROMICS AIR) was initiated in 2013 to investigate the relation between individual-level estimates of short-term and long-term air pollution exposures, day-to-day symptom variability and disease progression in individuals with COPD. SPIROMICS AIR builds on a multicentre study of smokers with COPD, supplementing it with state-of-the-art air pollution exposure assessments of fine particulate matter, oxides of nitrogen, ozone, sulfur dioxide and black carbon. In the parent study, approximately 3000 smokers with and without airflow obstruction are being followed for up to 3 years for the identification of intermediate biomarkers which predict disease progression. Subcohorts undergo daily symptom monitoring using comprehensive daily diaries. The air monitoring and modelling methods employed in SPIROMICS AIR will provide estimates of individual exposure that incorporate residence-specific infiltration characteristics and participant-specific time-activity patterns. The overarching study aim is to understand the health effects of short-term and long-term exposures to air pollution on COPD morbidity, including exacerbation risk, patient-reported outcomes and disease progression.

Ethics and dissemination

The institutional review boards of all the participating institutions approved the study protocols. The results of the trial will be presented at national and international meetings and published in peer-reviewed journals.