Free radical activity and pro-inflammatory effects of particulate air pollution (PM10) in vivo and in vitro

Ambient particulate matter and chronic obstructive pulmonary disease mortality: a nationwide, individual-level, case-crossover study in China

BACKGROUND

Short-term exposure to particulate matter air pollution has been associated with the exacerbations of COPD, but its association with COPD mortality was not fully elucidated. We aimed to assess the association between short-term particulate matter exposure and the risk of COPD mortality in China using individual-level data.

METHODS

We derived 2.26 million COPD deaths from a national death registry database in Chinese mainland between 2013 and 2019. Exposures to fine particulate matter (PM2.5) and coarse particulate matter (PM2.5-10) were assessed by satellite-based models of a 1 × 1 km resolution and assigned to each individual based on residential address. The associations of PM2.5 and PM2.5-10 with COPD mortality were examined using a time-stratified case-crossover design and conditional logistic regressions with distributed lag models. We further conducted stratified analyses by age, sex, education level, and season.

FINDINGS

Short-term exposures to both PM2.5 and PM2.5-10 were associated with increased risks of COPD mortality. These associations appeared and peaked on the concurrent day, attenuated and became nonsignificant after 5 or 7 days, respectively. The exposure-response curves were approximately linear without discernible thresholds. An interquartile range increase in PM2.5 and PM2.5-10 concentrations was associated with 4.23% (95% CI: 3.75%, 4.72%) and 2.67% (95% CI: 2.18%, 3.16%) higher risks of COPD mortality over lag 0-7 d, respectively. The associations of PM2.5 and PM2.5-10 attenuated slightly but were still significant in the mutual-adjustment models. A larger association of PM2.5-10 was observed in the warm season.

INTERPRETATION

This individual-level, nationwide, case-crossover study suggests that short-term exposure to PM2.5 and PM2.5-10 might act as one of the environmental risk factors for COPD mortality.

FUNDING

This study is supported by the National Key Research and Development Program of China (2023YFC3708304 and 2022YFC3702701), the National Natural Science Foundation of China (82304090 and 82030103), the 3-year Action Plan for Strengthening the Construction of the Public Health System in Shanghai (GWVI-11.2-YQ31), and the Science and Technology Commission of Shanghai Municipality (21TQ015).

PM2.5 and its components and respiratory disease healthcare encounters - Unanticipated increased exposure-response relationships in recent years after environmental policies

Prior studies reported excess rates (ERs) of cardiorespiratory events associated with short-term increases in PM2.5 concentrations, despite implementation of pollution-control policies. In 2017, Federal Tier 3 light-duty vehicle regulations began, and to-date there have been no assessments of population health effects of the policy. Using the NYS Statewide Planning and Research Cooperative System (SPARCS) database, we obtained hospitalizations and ED visits with a principal diagnosis of asthma or chronic obstructive pulmonary disease (COPD) for residents living within 15 miles of six urban PM2.5 monitoring sites in NYS (2014-2019). We used a time-stratified case-crossover design and conditional logistic regression (adjusting for ambient temperature, relative humidity, and weekday) to estimate associations between PM2.5, POC (primary organic carbon), SOC (secondary organic carbon), and rates of respiratory disease hospitalizations and emergency department (ED) visits from 2014 to 2019. We evaluated demographic disparities in these relative rates and compared changes in ERs before (2014-2016) and after Tier 3 implementation (2017-2019). Each interquartile range increase in PM2.5 was associated with increased ERs of asthma or COPD hospitalizations and ED visits in the previous 7 days (ERs ranged from 1.1%-3.1%). Interquartile range increases in POC were associated with increased rates of asthma ED visits (lag days 0-6: ER = 2.1%, 95% CI = 0.7%, 3.6%). Unexpectedly, the ERs of asthma admission and ED visits associated with PM2.5, POC, and SOC were higher during 2017-2019 (after Tier 3) than 2014-2016 (before Tier-3). Chronic obstructive pulmonary disease analyses showed similar patterns. Excess Rates were higher in children (<18 years; asthma) and seniors (≥65 years; COPD), and Black, Hispanic, and NYC residents. In summary, unanticipated increases in asthma and COPD ERs after Tier-3 implementation were observed, and demographic disparities in asthma/COPD and PM2.5, POC, and SOC associations were also observed. Future work should confirm findings and investigate triggering of respiratory events by source-specific PM.

Histological Assessment of Respiratory Tract and Liver of BALB/c Mice Nebulized with Tocilizumab

Pulmonary drug delivery offers a minimally invasive and efficient method for treating lung conditions, leveraging the lungs' extensive surface area and blood flow for rapid drug absorption. Nebulized therapies aim to deliver drugs directly to the lung tissue. This study investigates the histological impact of nebulized tocilizumab-a monoclonal antibody targeting IL-6, traditionally administered intravenously for rheumatoid arthritis and severe COVID-19-on a murine model. Thirty BALB/c mice were nebulized with tocilizumab (10 mg, 5 mg, and 2.5 mg) and six controls were nebulized with saline solution. They were euthanized 48 h later, and their organs (lungs, nasal mucosa, and liver) were analyzed by a microscopic histological evaluation. The results indicate that all the mice survived the 48 h post-nebulization period without systemic compromise. The macroscopic examination showed no abnormalities, and the histopathological analysis revealed greater lung vascular changes in the control group than in the nebulized animals, which is attributable to the euthanasia with carbon dioxide. Additionally, increased alveolar macrophages were observed in the nebulized groups compared to controls. No significant histological changes were observed in the liver, indicating the safety of nebulized tocilizumab. In conclusion, these findings suggest the potential of nebulized tocilizumab for treating pulmonary inflammation, warranting further research to establish its efficacy and safety in clinical settings.

Differential Inflammatory Cytokine Elaboration in Serum from Brick Kiln Workers in Bhaktapur, Nepal

Previous studies involving workers at brick kilns in the Kathmandu Valley of Nepal have investigated chronic exposure to hazardous levels of fine particulate matter (PM2.5) common in ambient and occupational environments. Such exposures are known to cause and/or exacerbate chronic respiratory diseases, including chronic obstructive pulmonary disease (COPD) and asthma. However, there is a paucity of data regarding the status of systemic inflammation observed in exposed workers at brick manufacturing facilities within the country. In the current study, we sought to elucidate systemic inflammatory responses by quantifying the molecular cytokine/chemokine profiles in serum from the study participants. A sample of participants were screened from a kiln in Bhaktapur, Nepal (n = 32; 53% female; mean ± standard deviation: 28.42 ± 11.47 years old) and grouped according to job category. Blood was procured from participants on-site, allowed to clot at room temperature, and centrifuged to obtain total serum. A human cytokine antibody array was used to screen the inflammatory mediators in serum samples from each of the participants. For the current study, four job categories were evaluated with n = 8 for each. Comparisons were generated between a control group of administration workers vs. fire master workers, administration workers vs. green brick hand molders, and administration workers vs. top loaders. We discovered significantly increased concentrations of eotaxin-1, eotaxin-2, GCSF, GM-CSF, IFN-γ, IL-1α, IL-1β, IL-6, IL-8, TGF-β1, TNF-α, and TIMP-2 in serum samples from fire master workers vs. administration workers (p < 0.05). Each of these molecules was also significantly elevated in serum from green brick hand molders compared to administration workers (p < 0.05). Further, each molecule in the inflammatory screening with the exception of TIMP-2 was significantly elevated in serum from top loaders compared to administration workers (p < 0.05). With few exceptions, the fire master workers expressed significantly more systemic inflammatory molecular abundance when compared to all other job categories. These results reveal an association between pulmonary exposure to PM2.5 and systemic inflammatory responses likely mediated by cytokine/chemokine elaboration. The additional characterization of a broader array of inflammatory molecules may provide valuable insight into the susceptibility to lung diseases among this population.

Impact of Airborne Exposure to PM10 Increases Susceptibility to P. aeruginosa Infection

The effects of exposure to airborne particulate matter with a size of 10 μm or less (PM10) on C57BL/6 mouse corneas, their response to Pseudomonas aeruginosa (PA) infection, and the protective effects of SKQ1 were determined. C57BL/6 mouse corneas receiving PBS or SKQ1 were exposed to control (air) or PM10 for 2 weeks, infected, and the disease was documented by clinical score, PMN quantitation, bacterial plate count, RT-PCR and Western blot. PBS-treated, PM10-exposed corneas did not differ at 1 day postinfection (dpi), but exhibited earlier (3 dpi) corneal thinning compared to controls. By 3 dpi, PM10 significantly increased corneal mRNA levels of several pro-inflammatory cytokines, but decreased IL-10, NQO1, GR1, GPX4, and Nrf2 over control. SKQ1 reversed these effects and Western blot selectively confirmed the RT-PCR results. PM10 resulted in higher viable bacterial plate counts at 1 and 3 dpi, but SKQ1 reduced them at 3 dpi. PM10 significantly increased MPO in the cornea at 3 dpi and was reduced by SKQ1. SKQ1, used as an adjunctive treatment to moxifloxacin, was not significantly different from moxifloxacin alone. Exposure to PM10 increased the susceptibility of C57BL/6 to PA infection; SKQ1 significantly reversed these effects, but was not effective as an adjunctive treatment.

Mechanisms of PM10 Disruption of the Nrf2 Pathway in Cornea

We have previously shown that PM10 exposure causes oxidative stress and reduces Nrf2 protein levels, and SKQ1 pre-treatment protects against this damage in human corneal epithelial cells (HCE-2). The current study focuses on uncovering the mechanisms underlying acute PM10 toxicity and SKQ1-mediated protection. HCE-2 were pre-treated with SKQ1 and then exposed to 100 μg/mL PM10. Cell viability, oxidative stress markers, programmed cell death, DNA damage, senescence markers, and pro-inflammatory cytokines were analyzed. Nrf2 cellular location and its transcriptional activity were determined. Effects of the Nrf2 inhibitor ML385 were similarly evaluated. Data showed that PM10 decreased cell viability, Nrf2 transcriptional activity, and mRNA levels of antioxidant enzymes, but increased p-PI3K, p-NFκB, COX-2, and iNOS proteins levels. Additionally, PM10 exposure significantly increased DNA damage, phosphor-p53, p16 and p21 protein levels, and β-galactosidase (β-gal) staining, which confirmed the senescence. SKQ1 pre-treatment reversed these effects. ML385 lowered the Nrf2 protein levels and mRNA levels of its downstream targets. ML385 also abrogated the protective effects of SKQ1 against PM10 toxicity by preventing the restoration of cell viability and reduced oxidative stress. In conclusion, PM10 induces inflammation, reduces Nrf2 transcriptional activity, and causes DNA damage, leading to a senescence-like phenotype, which is prevented by SKQ1.

Impact of particulate air pollution on airway injury and epithelial plasticity; underlying mechanisms

Air pollution plays an important role in the mortality and morbidity of chronic airway diseases, such as asthma and chronic obstructive pulmonary disease (COPD). Particulate matter (PM) is a significant fraction of air pollutants, and studies have demonstrated that it can cause airway inflammation and injury. The airway epithelium forms the first barrier of defense against inhaled toxicants, such as PM. Airway epithelial cells clear airways from inhaled irritants and orchestrate the inflammatory response of airways to these irritants by secreting various lipid mediators, growth factors, chemokines, and cytokines. Studies suggest that PM plays an important role in the pathogenesis of chronic airway diseases by impairing mucociliary function, deteriorating epithelial barrier integrity, and inducing the production of inflammatory mediators while modulating the proliferation and death of airway epithelial cells. Furthermore, PM can modulate epithelial plasticity and airway remodeling, which play central roles in asthma and COPD. This review focuses on the effects of PM on airway injury and epithelial plasticity, and the underlying mechanisms involving mucociliary activity, epithelial barrier function, airway inflammation, epithelial-mesenchymal transition, mesenchymal-epithelial transition, and airway remodeling.

Heme oxygenase-1 alleviates allergic airway inflammation by suppressing NF-κB-mediated pyroptosis of bronchial epithelial cells

Allergic asthma development and pathogenesis are influenced by airway epithelial cells in response to allergens. Heme oxygenase-1 (HO-1), an inducible enzyme responsible for the breakdown of heme, has been considered an appealing target for the treatment of chronic inflammatory diseases. Herein, we report that alleviation of allergic airway inflammation by HO-1-mediated suppression of pyroptosis in airway epithelial cells (AECs). Using house dust mite (HDM)-induced asthma models of mice, we found increased gasdermin D (GSDMD) in the airway epithelium. In vivo administration of disulfiram, a specific inhibitor of pore formation by GSDMD, decreased thymic stromal lymphopoietin (TSLP) release, T helper type 2 immune response, alleviated airway inflammation, and reduced airway hyperresponsiveness (AHR). HO-1 induction by hemin administration reversed these phenotypes. In vitro studies revealed that HO-1 restrained GSDMD-mediated pyroptosis and cytokine TSLP release in AECs by binding Nuclear Factor-Kappa B (NF-κB) p65 RHD domain and thus controlling NF-κB-dependent pyroptosis. These data provide new therapeutic indications for purposing HO-1 to counteract inflammation, which contributes to allergic inflammation control.

ANRIL regulating the secretion of Muc5ac induced by atmospheric PM2.5 via NF-κB pathway in Beas-2B cells

PM2.5 can cause airway inflammation and promote the excessive secretion of mucin 5ac (Muc5ac), which can further induce many respiratory diseases. Antisense non-coding RNA in the INK4 locus (ANRIL) might regulate the inflammatory responses mediated by nuclear factor kappa-B (NF-κB) signaling pathway. Beas-2B cells were used to clarify the role of ANRIL in the secretion of Muc5ac induced by PM2.5 . The siRNA was used to silence ANRIL expression. Normal and gene silenced Beas-2B cells were respectively exposed to different doses of PM2.5 for 6, 12, and 24 h. The survival rate of Beas-2B cells was detected by methyl thiazolyl tetrazolium (MTT) assay. Tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β) and Muc5ac levels were determined by enzyme linked immunosorbent assay (ELISA). The expression levels of NF-κB family genes and ANRIL were detected by real time polymerase chain reaction (PCR). The levels of NF-κB family proteins and NF-κB family phosphorylated proteins were determined using Western blot. Immunofluorescence experiments were performed to observe the nuclear transposition of RelA. PM2.5 exposure increased the levels of Muc5ac, IL-1β and TNF-α, and ANRIL gene expression (p < .05). With the dose and time of PM2.5 exposure increasing, the protein levels of inhibitory subunit of nuclear factor kappa-B alpha (IκB-α), RelA, and NF-κB1 decreased, the protein levels of phosphorylated RelA (p-RelA) and phosphorylated NF-κB1 (p-NF-κB1) increased, and RelA nuclear translocation increased, which indicated that the NF-κB signaling pathway was activated (p < .05). Silencing ANRIL could decrease the levels of Muc5ac, IL-1β, TNF-α, decrease NF-κB family genes expression, inhibit the degradation of IκB-α and the activation of NF-κB pathway (p < .05). ANRIL played a regulatory role in the secretion of Muc5ac and the inflammation induced by atmospheric PM2.5 via NF-κB pathway in Beas-2B cells. ANRIL could be a target for prevention and treatment of the respiratory diseases caused by PM2.5 .

Air pollution and mortality in patients with chronic obstructive pulmonary disease: a cohort study in South Korea

Background

Evidence on whether long-term exposure to air pollution increases the mortality risk in patients with chronic obstructive pulmonary disease (COPD) is limited.

Objectives

We aimed to investigate the associations of long-term exposure to particulate matter with diameter <10 µm (PM10) and nitrogen dioxide (NO2) with overall and disease-specific mortality in COPD patients.

Design

We conducted a nationwide retrospective cohort study of 121,423 adults ⩾40 years diagnosed with COPD during 1 January to 31 December 2009.

Methods

Exposure to PM10 and NO2 was estimated for residential location using the ordinary kriging method. We estimated the risk of overall mortality associated with 1-, 3-, and 5-years average concentrations of PM10 and NO2 using Cox proportional hazards models and disease-specific mortality using the Fine and Gray method adjusted for age, sex, income, body mass index, smoking, comorbidities, and exacerbation history.

Results

The adjusted hazard ratios (HRs) for overall mortality associated with a 10 µg/m3 increase in 1-year PM10 and NO2 exposures were 1.004 [95% confidence interval (CI) = 0.985, 1.023] and 0.993 (95% CI = 0.984, 1.002), respectively. The results were similar for 3- and 5-year exposures. For a 10-µg/m3 increase in 1-year PM10 and NO2 exposures, the adjusted HRs for chronic lower airway disease mortality were 1.068 (95% CI = 1.024, 1.113) and 1.029 (95% CI = 1.009, 1.050), respectively. In stratified analyses, exposures to PM10 and NO2 were associated with overall mortality in patients who were underweight and had a history of severe exacerbation.

Conclusion

In this large population-based study of patients with COPD, long-term PM10 and NO2 exposures were not associated with overall mortality but were associated with chronic lower airway disease mortality. PM10 and NO2 exposures were both associated with an increased risk of overall mortality, and with overall mortality in underweight individuals and those with a history of severe exacerbation.

Exposure to ambient gaseous air pollutants and adult lung function: a systematic review

Exposure to hazardous air pollutants is identified as most obvious premature mortality factors in the world. Numerous epidemiological studies have estimated exposure to air pollutants may cause pulmonary toxicity and the incidence of respiratory diseases including chronic obstructive pulmonary disease (COPD), chronic bronchitis and asthma. The currently research was performed to evaluation the association between gaseous pollutants and lung function in healthy adults. Articles related to this study were selected from researches of Scopus, PubMed, and Web of Science databases. A total of 2,644 articles were retrieved and 39 records were reviewed after removing duplicates and excluding irrelevant studies. The result of this systematic review indicated that there is some evidence on decreasing lung function with exposure to gaseous air pollutants (NO₂, SO₂, and O₃) which can have negative effects on human health. Although according to the evidence changes in lung function are mostly linked to the exposure to environmental pollutants including CO, O₃, NO₂ and SO₂, the results should be interpreted with caution considering some following issues discussed in this review. Therefore, further studies are required considering well-designed studies in large scales to strengthen the evidence.

Specific upregulation of extracellular miR-6238 in particulate matter-induced acute lung injury and its immunomodulation

Acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) are life-threatening diseases characterized by a severe inflammatory response and the destruction of alveolar epithelium and endothelium. ALI/ARDS is caused by pathogens and toxic environmental stimuli, such as particulate matter (PM). However, the general symptoms of ALI/ARDS are similar, and determining the cause of lung injury is often challenging. In this study, we investigated whether there is a critical miRNA that characterizes PM-induced ALI. We found that the expression of miR-6238 is specifically upregulated in lung tissue and lung-derived extracellular vesicles (EVs) in response to PM exposure. Notably, bacterial endotoxin (Lipopolysaccharide; LPS or peptidoglycan; PTG) does not induce the expression of miR-6238 in the lung. Instead, the expression of miR-155 is dramatically increased in LPS-induced ALI. We further demonstrated that human lung epithelial cells and macrophages predominantly produce miR-6238 and miR-155, respectively. Mechanistically, EV-miR-6238 is effectively internalized into alveolar macrophages (AMs) and regulates inflammatory responses in vivo. CXCL3 is a main target of miR-6238 in AMs and modulates neutrophil infiltration into the lung alveoli. Collectively, our findings suggest that miR-6238 is a novel regulator of pulmonary inflammation and a putative biomarker that distinguishes PM-induced ALI from endotoxin (LPS/PTG)-mediated ALI.

Impact of air pollutants on influenza-like illness outpatient visits under COVID-19 pandemic in the subcenter of Beijing, China

This study aimed to explore the association between air pollutants and outpatient visits for influenza-like illnesses (ILI) under the coronavirus disease 2019 (COVID-19) stage in the subcenter of Beijing. The data on ILI in the subcenter of Beijing from January 1, 2018 to December 31, 2020 were obtained from the Beijing Influenza Surveillance Network. A generalized additive Poisson model was applied to examine the associations between the concentrations of air pollutants and daily outpatient visits for ILI when controlling meteorological factors and temporal trend. A total of 171 943 ILI patients were included. In the pre-coronavirus disease 2019 (COVID-19) stage, an increased risk of ILI outpatient visits was associated to a high air quality index (AQI) and the high concentrations of particulate matter less than 2.5 (PM_2.5 ), particulate matter 10 (PM₁₀ ), sulphur dioxide (SO₂ ), nitrogen dioxide (NO₂ ), and carbon monoxide (CO), and a low concentration of ozone (O₃ ) on lag0 day and lag1 day, while a higher increased risk of ILI outpatient visits was observed by the air pollutants in the COVID-19 stage on lag0 day. Except for PM₁₀ , the concentrations of other air pollutants on lag1 day were not significantly associated with an increased risk of ILI outpatient visits during the COVID-19 stage. The findings that air pollutants had enhanced immediate effects and diminished lag-effects on the risk of ILI outpatient visits during the COVID-19 pandemic, which is important for the development of public health and environmental governance strategies.

Inflammation and the Potential Implication of Macrophage-Microglia Polarization in Human ASD: An Overview

Autism spectrum disorder (ASD) is a heterogeneous collection of neurodevelopmental disorders, difficult to diagnose and currently lacking treatment options. The possibility of finding reliable biomarkers useful for early identification would offer the opportunity to intervene with treatment strategies to improve the life quality of ASD patients. To date, there are many recognized risk factors for the development of ASD, both genetic and non-genetic. Although genetic and epigenetic factors may play a critical role, the extent of their contribution to ASD risk is still under study. On the other hand, non-genetic risk factors include pollution, nutrition, infection, psychological states, and lifestyle, all together known as the exposome, which impacts the mother's and fetus's life, especially during pregnancy. Pathogenic and non-pathogenic maternal immune activation (MIA) and autoimmune diseases can cause various alterations in the fetal environment, also contributing to the etiology of ASD in offspring. Activation of monocytes, macrophages, mast cells and microglia and high production of pro-inflammatory cytokines are indeed the cause of neuroinflammation, and the latter is involved in ASD's onset and development. In this review, we focused on non-genetic risk factors, especially on the connection between inflammation, macrophage polarization and ASD syndrome, MIA, and the involvement of microglia.

Biochemical evidence of PM2.5 critical components for inducing myocardial fibrosis in vivo and in vitro

PM_2.5 constituents are tightly linked to the initiation of many cardiovascular diseases (CVDs). Little is known, however, about the events which critical components of PM_2.5 can induce the initiating events in CVDs. C57BL/6 female mice were exposed to PM_2.5 (3 mg/kg b.w.) from four different cities (Taiyuan, Beijing, Hangzhou, and Guangzhou) by oropharyngeal aspiration every other day. PM_2.5 from Taiyuan increased the diastolic function of the hearts and induced myocardial fibrosis with increased areas of interstitial fibrosis through the NOX4/TGF-β1/Smad 3/Col1a1 pathways. Pb, Cr, Mn, Zn, and most of the polycyclic aromatic hydrocarbons (PAHs) were positively associated with the related indicators of cardiac diastolic function and myocardial fibrosis by using Pearson correlation (R² = 0.9085-0.9897). To determine the critical components in PM_2.5 that can induce the occurrence of myocardial fibrosis, BEAS-2b cells were treated with one or more of five candidate components with/without Guangzhou PM_2.5, and then the conditioned medium of BEAS-2b was used to culture AC16 cells. The results showed that Zn + Pb + Mn + BaP with PM_2.5 from Guangzhou exposure significantly increased reactive oxygen species production of BEAS-2b cells and induced a dramatic increase of myocardial fiber-related gene expression (Col1a1 and TGF-β) in AC16 cells. It indicated that the different mass concentrations of Zn, Pb, Mn, and ΣPAHs in PM_2.5 might be the critical factors that modulated myocardial fibrosis induction by targeted. Our study provided a novel avenue for further elucidation of molecular mechanisms of PM_2.5 components-induced myocardial fibrosis.

Impacts of long-term ambient particulate matter and gaseous pollutants on circulating biomarkers of inflammation in male and female health professionals

BACKGROUND

Systemic inflammation may serve as a biological mechanism linking air pollution to poor health but supporting evidence from studies of long-term pollutant exposure and inflammatory cytokines is inconsistent.

OBJECTIVE

We studied associations between multiple particulate matter (PM) and gaseous air pollutants and pro- and anti-inflammatory cytokines within two nationwide cohorts of men and women.

METHODS

Data were obtained from 16,151 women in the Nurses' Health Study and 7,930 men in the Health Professionals' Follow-up Study with at least one measure of circulating adiponectin, C-Reactive Protein (CRP), Interleukin-6 (IL-6) or soluble tumor necrosis-factor receptor-2 (sTNFR-2). Exposure to PM with aerodynamic diameter ≤2.5, 2.5-10, and ≤10 μm (PM2.5, PM2.5-10, PM10) and nitrogen dioxide (NO2) was estimated using spatio-temporal models and were linked to participants' addresses at the time of blood draw. Averages of the 1-, 3-, and 12-months prior to blood draw were examined. Associations between each biomarker and pollutant were estimated from linear regression models adjusted for individual and contextual covariates.

RESULTS

In adjusted models, we observed a 2.72% (95% CI: 0.43%, 5.95%), 3.11% (-0.12%, 6.45%), and 3.67% (0.19%, 7.26%) increase in CRP associated with a 10 μg/m3 increase in 1-, 3-, and 12- month averaged NO2 in women. Among men, there was a statistically significant 5.96% (95% CI: 0.07%, 12.20%), 6.99% (95% CI: 0.29%, 14.15%), and 8.33% (95% CI: 0.35%, 16.94%) increase in CRP associated with a 10 μg/m3 increase in 1-, 3-, and 12-month averaged PM2.5-10, respectively. Increasing PM2.5-10 was associated with increasing IL-6 and sTNFR-2 among men over shorter exposure durations. There were no associations with exposures to PM2.5 or PM10, or with adiponectin. Findings were robust to sensitivity analyses restricting to disease-free controls and non-movers.

CONCLUSIONS

Across multiple long-term pollutant exposures and inflammatory markers, associations were generally weak. Focusing on specific pollutant-inflammatory mechanisms may clarify pathways.

Correlation of Air Pollution and Prevalence of Acute Pulmonary Embolism in Northern Thailand

BACKGROUND

The relationship between the level of air pollution and acute pulmonary embolism (APE) has had inconsistent results.

OBJECTIVE

This study aimed to analyze the relationship between the high level of air pollution exposure and APE.

METHODS

A ten-year retrospective cohort, single-center study was performed on patients diagnosed with APE from October 2010 to December 2020. The association between air pollution and monthly APE case diagnosis was analyzed.

RESULTS

A total number of 696 patients was included. The effect of every 10 µg/m³ increment of particulate matters with an aerodynamic diameter < 10 µm (PM₁₀) on total monthly APE cases (unprovoked PE and provoked PE) was increased significantly at lag 4, 5 and 6 months with adjusted RR (95% CI) of 1.06 (1.01, 1.12), p = 0.011, 1.07 (1.01, 1.13), p = 0.021 and 1.06 (1.01, 1.12), p = 0.030, respectively. Adjusted RR for APE was significantly increased for PM₁₀ in the second tertile ((adjusted RR (95% CI) 1.76 (1.12, 2.77)), p = 0.014.

CONCLUSIONS

We conclude that PM₁₀ is associated with an increased prevalence of APE cases. The policy for tighter control of air pollution in our country is needed to reduce the impact of air pollutants on people's health.

Co-exposure to multiple air pollutants and sleep disordered breathing in patients with or without obstructive sleep apnea: A cross-sectional study

BACKGROUND

Air pollution may be a contributing risk factor for obstructive sleep apnea (OSA). However, the health effects of co-exposure to multiple air pollutants on OSA patients remain unclear.

OBJECTIVES

To assess the joint effect of multi-pollutant on sleep disordered breathing (SDB) parameters in patients with or without OSA and identify the dominant pollutants.

METHODS

A total of 2524 outpatients from April 2020 to May 2021 were recruited in this cross-sectional study. Ambient air pollutant data were obtained from the nearest central monitoring stations to participants' residential address. SDB parameters were measured by the ApneaLink devices, including apnea-hypopnea index (AHI), hypopnea index (HI), oxygen desaturation index (ODI), average oxygen saturation (SpO₂), percentage sleep time with <90% saturation (T90), and desaturation. Bayesian kernel machine regression (BKMR) was applied to evaluate the effects of multiple pollutants.

RESULTS

Significant associations were observed between air pollutants and SDB parameters (including increases in AHI, HI, ODI, and desaturation) among patients with OSA. Co-exposure to air pollutants was positively correlated with AHI, HI, and ODI. PM₁₀ and O₃ dominated the effects of pollutant mixtures on OSA, with the highest posterior inclusion probability (PIP) values of 0.592 and 0.640, respectively. Stratified analysis showed that, compared to male patients with OSA, stronger effects on the SDB parameters were observed in female patients. Stronger associations were also found in the warm season than those in the cold season.

CONCLUSION

Co-exposure to air pollutants was associated with SDB parameters among patients with OSA, PM₁₀ and O₃ might play the dominant roles.

Association of PM2.5 and PM10 with Acute Exacerbation of Chronic Obstructive Pulmonary Disease at lag0 to lag7: A Systematic Review and Meta-Analysis

This study aimed to conduct a meta-analysis to investigate whether short-term exposure to fine (PM_2.5) and coarse (PM₁₀) particulate matter was associated with acute exacerbation of chronic obstructive pulmonary disease (AECOPD) hospitalization, emergency room visit, and outpatient visit at different lag values. PubMed, Embase, and the Cochrane Library were searched for relevant papers published up to March 2021. For studies reporting results per 1-µg/m³ increase in PM_2.5, the results were recalculated as per 10-µg/m³ increase. We manually calculated the RRs for these two studies and transferred the RRs to estimate 10 µg/m³ increases in PM_2.5. Automation tools were initially used to remove ineligible studies. Two reviewers independently screened the remaining records and retrieved reports. Twenty-six studies (28 datasets; 7,018,419 patients) were included. There was a significant association between PM_2.5 and AECOPD events on lag0 (ES = 1.01, 95%CI: 1.01-1.02, p < 0.001; I²=88.6%, P_{heterogeneity}<0.001), lag1 (ES = 1.00, 95%CI: 1.00-1.01, p < 0.001; I²=82.5%, P_{heterogeneity}<0.001), lag2 (ES = 1.01, 95%CI: 1.01-1.01, p < 0.001; I²=90.6%, P_{heterogeneity}<0.001), lag3 (ES = 1.01, 95%CI: 1.00-1.01, p < 0.001; I²=88.9%, P_{heterogeneity}<0.001), lag4 (ES = 1.00, 95%CI: 1.00-1.01, p < 0.001; I²=83.7%, P_{heterogeneity}<0.001), and lag7 (ES = 1.00, 95%CI: 1.00-1.00, p < 0.001; I²=0.0%, P_{heterogeneity}=0.743). The subgroup analyses showed that PM_2.5 influenced the rates of hospitalization, emergency room visits, and outpatient visits. Similar trends were observed with PM₁₀. The risk of AECOPD events (hospitalization, emergency room visit, and outpatient visit) was significantly increased with a 10-µg/m³ increment in PM_2.5 and PM₁₀ from lag0 to lag7.List Of Abbreviations: particulate matter (PM_2.5 and PM₁₀); acute exacerbation of chronic obstructive pulmonary disease (AECOPD); Chronic obstructive pulmonary disease (COPD); Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA); Effect sizes [48]; confidence intervals (CIs).

Particulate matter (PM10) induces in vitro activation of human neutrophils, and lung histopathological alterations in a mouse model

The epidemiological association between exposure to particulate matter (PM₁₀) and various respiratory and cardiovascular problems is well known, but the mechanisms driving these effects remain unclear. Neutrophils play an essential role in immune defense against foreign agents and also participate in the development of inflammatory responses. However, the role of these cells in the PM₁₀ induced inflammatory response is not yet fully established. Thus, this study aims to evaluate the effect of PM₁₀ on the neutrophil-mediated inflammatory response. For this, neutrophils from healthy adult human donors were in vitro exposed to different concentrations of PM₁₀. The cell viability and cytotoxic activity were evaluated by MTT. LDH, propidium iodide and reactive oxygen species (ROS) were quantified by flow cytometry. Interleukin 8 (IL-8) expression, peptidyl arginine deiminase 4 (PAD₄), myeloperoxidase (MPO), and neutrophil elastase (NE) expression were measured by RT-PCR. IL-8 was also quantified by ELISA. Fluorescence microscopy was used to evaluate neutrophil extracellular traps (NETs) release. The in vivo inflammatory responses were assessed in BALB/c mice exposed to PM₁₀ by histopathology and RT-PCR. The analysis shows that PM₁₀ exposure induced a cytotoxic effect on neutrophils, evidenced by necrosis and LDH release at high PM₁₀ concentrations. ROS production, IL-8, MPO, NE expression, and NETs release were increased at all PM₁₀ concentrations assessed. Neutrophil infiltration in bronchoalveolar lavage fluid (BALF), histopathological changes with inflammatory cell infiltration, and CXCL1 expression were observed in PM₁₀-treated mice. The results suggest that lung inflammation in response to PM₁₀ could be mediated by neutrophils activation. In this case, these cells migrate to the lungs and release pro-inflamatory mediators, including ROS, IL-8, and NETs. Thus, contributing to the exacerbation of respiratory pathologies, such as allergies, infectious and obstructive diseases.

Glycine max (soy) based diet improves antioxidant defenses and prevents cell death in cadmium intoxicated lungs

Cadmium (Cd) is a toxic metal and an important environmental contaminant. We analyzed its effects on oligoelements, oxidative stress, cell death, Hsp expression and the histoarchitecture of rat lung under different diets, using animal models of subchronic cadmium intoxication. We found that Cd lung content augmented in intoxicated groups: Zn, Mn and Se levels showed modifications among the different diets, while Cu showed no differences. Lipoperoxidation was higher in both intoxicated groups. Expression of Nrf-2 and SOD-2 increased only in SoCd. GPx levels showed a trend to increase in Cd groups. CAT activity was higher in intoxicated groups, and it was higher in Soy groups vs. Casein. LDH activity in BAL increased in CasCd and decreased in both soy-fed groups. BAX/Bcl-2 semiquantitative ratio showed similar results than LDH activity, confirmed by Caspase 3 immunofluorescence. The histological analysis revealed an infiltration process in CasCd lungs, with increased connective tissue, fused alveoli and capillary fragility. Histoarchitectural changes were less severe in soy groups. Hsp27 expression increased in both intoxicated groups, while Hsp70 only augmented in SoCd. This show that a soy-diet has a positive impact upon oxidative unbalance, cell death and morphological changes induced by Cd and it could be a good alternative strategy against Cd exposure.

Systematic review of preclinical studies on the neutrophil-mediated immune response to air pollutants, 1980-2020

Preclinical evidence about the neutrophil-mediated response in exposure to air pollutants is scattered and heterogeneous. This has prevented the consolidation of this research field around relevant models that could advance towards clinical research. The purpose of this study was to systematic review the studies of the neutrophils response to air pollutants, following the recommendations of the Cochrane Collaboration and the PRISMA guide, through 54 search strategies in nine databases. We include 234 studies (in vitro, and in vivo), being more frequent using primary neutrophils, Balb/C and C57BL6/J mice, and Sprague-Dawley and Wistar rats. The most frequent readouts were cell counts, cytokines and histopathology. The temporal analysis showed that in the last decade, the use of mice with histopathological and cytokine measurement have predominated. This systematic review has shown that study of the neutrophils response to air pollutants started 40 years ago, and composed of 100 different preclinical models, 10 pollutants, and 11 immunological outcomes. Mechanisms of neutrophils-mediated immunopathology include cellular activation, ROS production, and proinflammatory effects, leading to cell-death, oxidative stress, and inflammatory infiltrates in lungs. This research will allow consolidating the research efforts in this field, optimizing the study of causal processes, and facilitating the advance to clinical studies.

Arterial Blood Gas and Rotational Thromboelastometry Parameters in Healthy Rescuers Incidentally Exposed to Nitroglycerin, Nitrogen Compounds, and Combustion Products

INTRODUCTION

Acute exposure to nitrogen compounds combined with a massive inhalation of air pollutants can influence respiratory and cardiovascular symptoms and coagulation abnormalities in accidentally exposed healthy adults during cave detonation operations.

METHODS

Italian alpine and cave rescuers widened a cave in the Abisso Luca Kralj in Trieste, Italy. Volunteers inside the cave were accidentally exposed to the fumes from an uncontrolled detonation of blasting gelatin microcharges. We performed a retrospective cohort study on the clinical data, arterial blood gas analysis, and rotational thromboelastometry parameters from the rescuers involved in the accident.

RESULTS

Ninety-three healthy rescuers were involved in the uncontrolled detonation: 47 volunteers handled a mixture of nitrogen compounds (blaster group), and 46 volunteers did not (nonblaster group). After the accident, statistically significant differences (P<0.05) in arterial blood gas values were observed between the groups, with a pattern of mild respiratory acidosis with hypercapnia in the nonblaster group and severe mixed acid-base disorder with hypoxia and hypercapnia in the blaster group. Mild hyperfibrinolysis was observed in 44 volunteers in the blaster group, as were associated bleeding symptoms in 34 volunteers; no significant coagulation modifications were recorded in the nonblaster group.

CONCLUSIONS

Respiratory acidosis with hypoxia, hypercapnia, a compensatory metabolic response, and mild hyperfibrinolysis were probably related to the combined effect of nitrogen compounds and the inhaled toxic products of detonation. Therefore, each element exerts a determinant effect on promoting the biological toxicity of the others.

Effects of ozone and particulate matter on airway epithelial barrier structure and function: a review of in vitro and in vivo studies

The airway epithelium represents a crucial line of defense against the spread of inhaled pathogens. As the epithelium is the first part of the body to be exposed to the inhaled environment, it must act as both a barrier to and sentinel against any inhaled agents. Despite its vital role in limiting the spread of inhaled pathogens, the airway epithelium is also regularly exposed to air pollutants which disrupt its normal function. Here we review the current understanding of the structure and composition of the airway epithelial barrier, as well as the impact of inhaled pollutants, including the reactive gas ozone and particulate matter, on epithelial function. We discuss the current in vitro, rodent model, and human exposure findings surrounding the impact of various inhaled pollutants on epithelial barrier function, mucus production, and mucociliary clearance. Detailed information on how inhaled pollutants impact epithelial structure and function will further our understanding of the adverse health effects of air pollution exposure.

Advances on the immunotoxicity of outdoor particulate matter: A focus on physical and chemical properties and respiratory defence mechanisms

Particulate matter (PM) is acknowledged to have multiple detrimental effects on human health. In this review, we report literature results on the possible link between outdoor PM and health outcomes with a focus on pulmonary infections and the mechanisms responsible for observed negative effects. PM physical and chemical properties, such as size and chemical composition, as well as major emission sources are described for a more comprehensive view about the role played by atmospheric PM in the observed adverse health effects; to this aim, major processes leading to the deposition of PM in the respiratory tract and how this can pave the way to the onset of pathologies are also presented. From the literature works here reviewed, two ways in which PM can threaten human health promoting respiratory infectious diseases are mostly taken into account. The first pathway is related to an enhanced susceptibility and here we will also report on molecular mechanisms in the lung immune system responsible for the augmented susceptibility to pathogens, such as the damage of mechanical defensive barriers, the alteration of the innate immune response, and the generation of oxidative stress. The second one deals with the relationship between infectious agents and PM; here we recall that viruses and bacteria (BioPM) are themselves part of atmospheric PM and are collected during sampling together with particles of different origin; so, data should be analysed with caution in order to avoid any false cause-effect relation. To face these issues a multidisciplinary approach is mandatory as also evident from the ongoing research about the mechanisms hypothesized for the SARS-CoV-2 airborne spreading, which is still controversial and claims for further investigation. Therefore, we preferred not to include papers dealing with SARS-CoV-2.

Indoor particulate air pollution from open fires and the cognitive function of older people

Exposure to indoor air pollution is known to affect respiratory and cardiovascular health, but little is known about its effects on cognitive function. We measured the concentrations and magnetite content of airborne particulate matter (PM) in the indoor environment arising from burning peat, wood or coal in residential open fires. Highest indoor PM_2.5 concentrations (60 μg/m³ i.e. 2.4 times the WHO-recommended 24-h mean) occurred when peat was burned, followed by burning of coal (30 μg/m³) and wood (17 μg/m³). Conversely, highest concentrations of coarser PM (PM_10-2.5) were associated with coal burning (20 μg/m³), with lower concentrations emitted during burning of wood (10 μg/m³) and peat (8 μg/m³). The magnetic content of the emitted PM, greatest (for both PM size fractions) when coal was burned, is similar to that of roadside airborne PM. Exposure to PM, and to strongly magnetic airborne PM, can be greater for individuals spending ~5 h/day indoors with a coal-burning open fire for 6 months/year compared to those commuting via heavily-trafficked roads for 1 h/day for 12 months/year. Given these high indoor PM and magnetite concentrations, and the reported associations between (outdoor) PM and impaired neurological health, we used individual-level data from The Irish Longitudinal Study on Ageing (TILDA) to examine the association between the usage of open fires and the cognitive function of older people. Using a sample of nearly seven thousand older people, we estimated multi-variate models of the association between cognitive function and open fire usage, in order to account for relevant confounders such as socio-economic status. We found a negative association between open fire usage and cognitive function as measured by widely-used cognitive tests such as word recall and verbal fluency tests. The negative association was largest and statistically strongest among women, a finding explained by the greater exposure of women to open fires in the home because they spent more time at home than men. Our findings were also robust to stratifying the sample between old and young, rich and poor, and urban and rural.

Maternal immune response and air pollution exposure during pregnancy: insights from the Early Markers for Autism (EMA) study

BACKGROUND

Perinatal exposure to air pollution and immune system dysregulation are two factors consistently associated with autism spectrum disorders (ASD) and other neurodevelopmental outcomes. However, little is known about how air pollution may influence maternal immune function during pregnancy.

OBJECTIVES

To assess the relationship between mid-gestational circulating levels of maternal cytokines/chemokines and previous month air pollution exposure across neurodevelopmental groups, and to assess whether cytokines/chemokines mediate the relationship between air pollution exposures and risk of ASD and/or intellectual disability (ID) in the Early Markers for Autism (EMA) study.

METHODS

EMA is a population-based, nested case-control study which linked archived maternal serum samples collected during weeks 15-19 of gestation for routine prenatal screening, birth records, and Department of Developmental Services (DDS) records. Children receiving DDS services for ASD without intellectual disability (ASD without ID; n = 199), ASD with ID (ASD with ID; n = 180), ID without ASD (ID; n = 164), and children from the general population (GP; n = 414) with no DDS services were included in this analysis. Serum samples were quantified for 22 cytokines/chemokines using Luminex multiplex analysis technology. Air pollution exposure for the month prior to maternal serum collection was assigned based on the Environmental Protection Agency's Air Quality System data using the maternal residential address reported during the prenatal screening visit.

RESULTS

Previous month air pollution exposure and mid-gestational maternal cytokine and chemokine levels were significantly correlated, though weak in magnitude (ranging from - 0.16 to 0.13). Ten pairs of mid-pregnancy immune markers and previous month air pollutants were significantly associated within one of the child neurodevelopmental groups, adjusted for covariates (p < 0.001). Mid-pregnancy air pollution was not associated with any neurodevelopmental outcome. IL-6 remained associated with ASD with ID even after adjusting for air pollution exposure.

CONCLUSION

This study suggests that maternal immune activation is associated with risk for neurodevelopmental disorders. Furthermore, that prenatal air pollution exposure is associated with small, but perhaps biologically relevant, effects on maternal immune system function during pregnancy. Additional studies are needed to better evaluate how prenatal exposure to air pollution affects the trajectory of maternal immune activation during pregnancy, if windows of heightened susceptibility can be identified, and how these factors influence neurodevelopment of the offspring.

Influence of weather and air pollution on the occurrence of idiopathic pulmonary embolism in the region of Sousse (Tunisia)

Pulmonary embolism (PE) is the most serious manifestation of thromboembolic conditions. Its incidence varies considerably between countries, suggesting its interaction with the external environment. To analyze the influence of climate and air pollution on the occurrence of idiopathic PE in the region of Sousse (Tunisia). A total of 142 patients with idiopathic PE at two academic hospitals in Sousse (Tunisia) were enrolled in the study over a 7-year period. An analysis of two time series (environmental data and PE cases) was performed. Climatic data were collected from the National Institute of Meteorology. Air pollution data were obtained from the modeling platform of the National Agency for Protection of the Environment. The year 2015 was marked by the occurrence of the highest number of cases (24.6%). A statistically significant decrease in PE risk of 41.9% was observed during the summer with an OR of 0.59 (95% CI [0.36-0.94] and p = 0.026), compared with other seasons. Poisson GLM regression showed a significant increased risk of PE of 3.3% for each 1 °C temperature drop. After multiple binary logistic regression, the elevation of PM₁₀ concentration was independently associated with an increased risk of PE (p < 10^-3, OR 79.55, 95% CI [42.28-149.6]). Some environmental parameters may predispose to the onset of idiopathic PE. Understanding their accurate influence may have preventive and curative implications.

Attenuation effect of polydeoxyribonucleotide on inflammatory cytokines and apoptotic factors induced by particulate matter (PM10) damage in human bronchial cells

Particulate matter (PM) of 10-μm-sized fine dust in the air penetrates the respiratory tract and contributes to the increasing incidence of various lung diseases, but its definite mechanism is not known. Recently, polydeoxyribonucleotide (PDRN) has been shown to have anti-inflammatory and regenerative effects in various tissues. However, the bronchial-related mechanism is not well-understood. Hence, this experiment is intended to demonstrate the beneficial effect of PDRN administration on PM10-induced injury in human bronchial-derived NCI-H358 cells. To confirm the protective effect of PDRN, PM10 was applied after PDRN pretreatment to confirm changes in NCI-H358 cells. Experiments were conducted to measure cell survival, cytotoxicity, inflammation, and apoptotic factor changes. WST-8 assay was used to confirm cell viability, and lactate dehydrogenase assay was used to obtain cytotoxicity. In addition, changes in inflammatory cytokines and apoptotic factors were confirmed by enzyme-linked immunosorbent assay and Western blot. Decreased cell viability and increased cytotoxicity, inflammatory cytokines, and apoptotic factors were observed after exposure to PM10. However, pretreatment with PDRN enhanced cell viability and reduced cytotoxicity. In addition, the expression of inflammatory cytokines such as tumor necrosis factor-α, interleukin-6 (IL-6), and IL-1β, and cell death factors such as Apaf-1, cyt c, caspase-3, caspase-9, Bid, and Bax/Bcl-2 ratio were decreased by PDRN administration in PM10-exposed NCI-H358 cells. PDRN, an A2AR agonist, affects cAMP activation and regulation of phosphorylation of PKA and CREB. In addition, treatment with A2AR antagonist 3,7-dimethyl-1-propargylxanthine significantly blocked PDRN's effect. These anti-cytotoxicity, anti-inflammation, and anti-apoptosis effects of PDRN can be attributed to the adenosine A2AR enhancing effect on PM10-exposed bronchial cells.

Effect of Air Pollution on Glutathione S-Transferase Activity and Total Antioxidant Capacity: Cross Sectional Study in Kuwait

BACKGROUND

Air pollution poses a significant threat to human health worldwide. Investigating potential health impacts is essential to the development of regulations and legislation to minimize health risks.

OBJECTIVES

The aim of the present study was to investigate the potentially hazardous effect of air pollution on the Ali Sabah Al Salem residential area in Kuwait by comparing the pollution level to a control area (Al-Qirawan) by assessing two biomarkers: erythrocyte glutathione S-transferases (e-GST) and total blood antioxidant, and then correlating the activity to pollution-related oxidative stress.

METHODS

The average concentrations of several airborne gases were measured at Ali Sabah Al Salem and Al-Qirawan, including ozone, carbon monoxide, nitrogen dioxide, nitrogen oxides, particulate matter less than 10 μm (PM₁₀), sulfur dioxide, ammonia, carbon dioxide, hydrogen sulfide, methane, and non-methane hydrocarbon. A total of fifty-eight participants were sampled from two different areas and divided into two groups. The study group was composed of 40 residents exposed to polluted ambient air in the Ali Sabah Al Salem residential area. A reference group composed of 18 residents in the Al-Qairawan area living far from major pollution sources was also tested.

RESULTS

All measured gases were higher in concentration at Ali Sabah Al Salem compared to the Al-Qirawan area. Furthermore, PM₁₀ and sulfur dioxide were higher than World Health Organization (WHO) guidelines. The e-GST activity was lower among participants of the Ali Sabah Al Salem residential area compared to participants living in the Al-Qairawan area. The total antioxidant capacity in whole blood of Ali Sabah Al Salem residents was significantly (p<0.0001) higher than in control subjects.

CONCLUSIONS

Residents in Ali Sabah Al Salem are exposed to a high level of air pollution that has a serious impact on glutathione S-transferases levels. Subsequently, regulations on pollution sources are needed to lower current health risks. Furthermore, the present study provides evidence that finger-prick blood sampling is a quick, non-invasive method suitable for screening e-GST activity and total antioxidants which may be applied for surveillance purposes.

PARTICIPANT CONSENT

Obtained.

ETHICS APPROVAL

The study was approved by the Scientific Research Committee of the Public Authority for Applied Education and Training, Kuwait.

COMPETING INTERESTS

The authors declare no competing financial interests.

Brown Carbon Production by Aqueous-Phase Interactions of Glyoxal and SO2

Oxalic acid and sulfate salts are major components of aerosol particles. Here, we explore the potential for their respective precursor species, glyoxal and SO₂, to form atmospheric brown carbon via aqueous-phase reactions in a series of bulk aqueous and flow chamber aerosol experiments. In bulk aqueous solutions, UV- and visible-light-absorbing products are observed at pH 3-4 and 5-6, respectively, with small but detectable yields of hydroxyquinone and polyketone products formed, especially at pH 6. Hydroxymethanesulfonate (HMS), C₂, and C₃ sulfonates are major products detected by electrospray ionization mass spectrometry (ESI-MS) at pH 5. Past studies have assumed that the reaction of formaldehyde and sulfite was the only atmospheric source of HMS. In flow chamber experiments involving sulfite aerosol and gas-phase glyoxal with only 1 min residence times, significant aerosol growth is observed. Rapid brown carbon formation is seen with aqueous aerosol particles at >80% relative humidity (RH). Brown carbon formation slows at 50-60% RH and when the aerosol particles are acidified with sulfuric acid but stops entirely only under dry conditions. This chemistry may therefore contribute to brown carbon production in cloud-processed pollution plumes as oxidizing volatile organic compounds (VOCs) interact with SO₂ and water.

Hazardous effects of urban air particulate matter acute exposure on lung and extrapulmonary organs in mice

Air particulate matter (PM) can lead to extrapulmonary adverse reactions in organs such as liver and heart either by particle translocation from the lung to the systemic circulation or by the release of lung mediators. Young BALB/c mice were intranasal instilled with 1mg/BW of Urban Air Particles from Buenos Aires or Residual Oil Fly Ash. Histopathology, oxidative metabolism and inflammation on lungs and extrapulmonary organs and the systemic response were evaluated. Lung histophatological analysis supported the rise in the number of inflammatory cells in the bronchoalveolar lavage from PM-exposed animals. Also, both PM caused recruitment of inflammatory cells in the liver and heart parenchyma and IL-6 and transaminases augmentation in serum. We have shown that despite morphochemical differences, both urban air PM altered the lung and extrapulmonary organs. Therefore, exposure to urban air PM may distress body metabolism which, in turn could lead to the development and progression of multifactorial diseases.

Pollution, Particles, and Dementia: A Hypothetical Causative Pathway

Epidemiological studies of air pollution have shown associations between exposure to particles and dementia. The mechanism of this is unclear. As these seem unlikely in terms of the very small dose likely to reach the brain in usual Western urban circumstances, we extend our 1995 hypothetical explanation of the association of air pollution with cardiac deaths as a plausible alternative explanation of its associations with dementia. Since our original proposal, it has become apparent that inflammation may be carried by blood from organ to organ by biologic microparticles derived from cell membranes. These transmit inflammatory messages to endothelial cells throughout the body as part of a general defensive response to assumed bacterial infection; particulate air pollution has recently been shown to be associated with their release into the blood. We propose that episodic release of biologic microparticles from pollution-induced lung inflammation causes secondary inflammation in the blood-brain barrier and cerebral microbleeds, culminating over time in cognitive impairment. Ultimately, by incomplete repair and accumulation of amyloid, this increases the risk of Alzheimer’s disease. Importantly, this mechanism may also explain the relationships of other inflammatory conditions and environmental factors with cognitive decline, and point to new opportunities to understand and prevent dementia.

Occurrence, formation, environmental fate and risks of environmentally persistent free radicals in biochars

Biochars are used globally in agricultural crop production and environmental remediation. However, environmentally persistent free radicals (EPFRs), which are stable emerging pollutants, are generated as a characteristic feature during biomass pyrolysis. EPFRs can induce the formation of reactive oxygen species, which poses huge agro-environmental and human health risks. Their half-lives and persistence in both biochar residues and in the atmosphere may lead to potentially adverse risks in the environment. This review highlights the comprehensive research into these bioreactive radicals, as well as the bottlenecks of biochar production leading up to the formation and persistence of EPFRs. Additionally, a way forward has been proposed, based on two main recommendations. A global joint initiative to create an all-encompassing regulations policy document that will improve both the technological and the quality control aspects of biochars to reduce EPFR generation at the production level. Furthermore, environmental impact and risk assessment studies should be conducted in the extensive applications of biochars in order to protect the environmental and human health. The highlighted key research directions proposed herein will shape the production, research, and adoption aspects of biochars, which will mitigate the considerable concerns raised on EPFRs.

Effects of Placenta-Derived Mesenchymal Stem Cells on the Particulate Matter-Induced Damages in Human Middle Ear Epithelial Cells

This study was aimed at investigating the effects of placenta-derived mesenchymal stem cells (PL-MSCs) on particulate matter- (PM-) exposed human middle ear epithelial cells (HMEECs). HMEECs were treated with 300 μg/ml PM for 24 hours. The PL-MSCs were cocultured with PM-treated HMEECs. Cells were harvested on days 0, 1, and 4, and the expression of the inflammatory genes TNFα, COX2, IL1β, IL6, and MUC5B in HMEECs and anti-inflammatory genes PTGES, TGFβ, and VEGF in PL-MSCs was examined by qRT-PCR. The culture media were collected to measure the secreted PGE2 level using an enzyme-linked immunosorbent assay. The mRNA expression of TNFα, COX2, IL1β, IL6, and MUC5B in HMEECs increased following PM treatment. PM-treated HMEECs cocultured with PL-MSCs showed alleviated inflammatory reactions represented by lower mRNA expression levels of MUC5B, TNFα, IL1β, and IL6 compared to monocultured PM-treated HMEECs. The mRNA expression levels of PGE2, TGFβ, and VEGF were elevated in cocultured PL-MSCs compared to those of control PL-MSCs. The medium of PM-treated HMEECs cocultured with PL-MSCs exhibited increased PGE2 levels. The increased inflammatory response in PM-treated HMEECs was reversed using PL-MSCs. The PGE2, TGFβ, and VEGF were the mediators of the anti-inflammatory effects of PL-MSCs.

Airborne, Vehicle-Derived Fe-Bearing Nanoparticles in the Urban Environment: A Review

Airborne particulate matter poses a serious threat to human health. Exposure to nanosized (<0.1 μm), vehicle-derived particulates may be hazardous due to their bioreactivity, their ability to penetrate every organ, including the brain, and their abundance in the urban atmosphere. Fe-bearing nanoparticles (<0.1 μm) in urban environments may be especially important because of their pathogenicity and possible association with neurodegenerative diseases, such as Alzheimer's and Parkinson's diseases. This review examines current knowledge regarding the sources of vehicle-derived Fe-bearing nanoparticles, their chemical and mineralogical compositions, grain size distribution and potential hazard to human health. We focus on data reported for the following sources of Fe-bearing nanoparticles: exhaust emissions (both diesel and gasoline), brake wear, tire and road surface wear, resuspension of roadside dust, underground, train and tram emissions, and aircraft and shipping emissions. We identify limitations and gaps in existing knowledge as well as future challenges and perspectives for studies of airborne Fe-bearing nanoparticles.

Impacts of six potential HONO sources on HOx budgets and SOA formation during a wintertime heavy haze period in the North China Plain

The Weather Research and Forecasting/Chemistry (WRF-Chem) model updated with six potential HONO sources (i.e., traffic, soil, biomass burning and indoor emissions, and heterogeneous reactions on aerosol and ground surfaces) was used to quantify the impact of the six potential HONO sources on the production and loss rates of OH and HO₂ radicals and the concentrations of secondary organic aerosol (SOA) in the Beijing-Tianjin-Heibei (BTH) region of China during a winter heavy haze period of Nov. 29-Dec. 3, 2017. The updated WRF-Chem model well simulated the observed HONO concentrations at the Wangdu site, especially in the daytime, and well reproduced the observed diurnal variations of regional-mean O₃ in the BTH region. The traffic emission source was an important HONO source during nighttime but not significant during daytime, heterogeneous reactions on ground/aerosol surfaces were important during nighttime and daytime. We found that the six potential HONO sources led to a significant enhancement in the dominant production and loss rates of HO_x on the wintertime heavy haze and nonhaze days (particularly on the heavy haze day), an enhancement of 5-25 μg m^-3 (75-200%) in the ground SOA in the studied heavy haze event, and an enhancement of 2-15 μg m^-3 in the meridional-mean SOA on the heavy haze day, demonstrating that the six potential HONO sources accelerate the HO_x cycles and aggravate haze events. HONO was the key precursor of primary OH in the BTH region in the studied wintertime period, and the photolysis of HONO produced a daytime mean OH production rate of 2.59 ppb h^-1 on the heavy haze day, much higher than that of 0.58 ppb h^-1 on the nonhaze day. Anthropogenic SOA dominated in the BTH region in the studied wintertime period, and its main precursors were xylenes (42%), BIGENE (31%) and toluene (21%).

Chronic obstructive pulmonary disease exacerbations and progression in relation to ambient air pollutants exposure

Background

The information for the impact of air pollutants on the severity of chronic obstructive pulmonary disease (COPD) and hospital admissions in Bulgaria is scarce. The aim of the study is to assess the relationship between some ambient air pollution and exacerbations levels as well as hospital admissions of patients with COPD in Bulgaria.

Methods

A multi-center, prospective, one-year observational study was conducted among 426 COPD patients. Data from pollution monitoring are collected from the Executive Environment Agency (EEA).

Results

The results showed that the pollution with sulfur dioxide (SO₂) is less than limit concentrations recommended by the European Union and World Health Organization (WHO), while the pollution with PM exceeds limits values of WHO two times. The mean rate of exacerbations in selected towns are between 0.5-3, the number of exacerbations with hospitalization are between 0.2-1.8 and length of hospital stay is between 1-14 days.

Conclusions

The study confirms that air pollution leads to increased number of exacerbations and hospital stay. The patients with mild level of COPD have 0.86 exacerbations and 2.61 days in hospital per year, while in case of very severe COPD these values increase 4 times. Outside pollutions lead to worsening of the disease severity and hospitalizations due to a higher rate of COPD exacerbations.

Toxicological evaluation of airborne particulate matter. Are cell culture technologies ready to replace animal testing?

Exposure to atmospheric particulate matter (PM) can affect human health, causing asthma, atherosclerosis, renal disease and cancer. In the last few years, outdoor air pollution has increased globally, leading to a public health emergency. Epidemiological studies have reported a correlation between the development of severe respiratory and systemic diseases and exposure to PM. To evaluate the toxic effect of PM of different origins, conventional experimental toxicological investigations have been conducted in animals; however, animal experimentation poses major ethical issues and usually differs from human conditions. As an alternative, human cell cultures are increasingly being used to investigate cellular and molecular mechanisms of PM toxicity. Although 2D cell cultures have been proven helpful, they are far from being a valid alternative to animal tests. Recently, 3D cell culture and organ-on-chip technology have provided systems that are more complex and that can be more informative for toxicity studies. In this review, the results of the 2D systems that are most frequently used for PM toxicity evaluations are summarized with a special focus on their limitations. We also examined to which extent 3D cell culture and particularly the organ-on-chip technology may overcome these limitations and represent effective tools to improve airborne PM toxicity evaluations.

Particle toxicology and health - where are we?

BACKGROUND

Particles and fibres affect human health as a function of their properties such as chemical composition, size and shape but also depending on complex interactions in an organism that occur at various levels between particle uptake and target organ responses. While particulate pollution is one of the leading contributors to the global burden of disease, particles are also increasingly used for medical purposes. Over the past decades we have gained considerable experience in how particle properties and particle-bio interactions are linked to human health. This insight is useful for improved risk management in the case of unwanted health effects but also for developing novel medical therapies. The concepts that help us better understand particles' and fibres' risks include the fate of particles in the body; exposure, dosimetry and dose-metrics and the 5 Bs: bioavailability, biopersistence, bioprocessing, biomodification and bioclearance of (nano)particles. This includes the role of the biomolecule corona, immunity and systemic responses, non-specific effects in the lungs and other body parts, particle effects and the developing body, and the link from the natural environment to human health. The importance of these different concepts for the human health risk depends not only on the properties of the particles and fibres, but is also strongly influenced by production, use and disposal scenarios.

CONCLUSIONS

Lessons learned from the past can prove helpful for the future of the field, notably for understanding novel particles and fibres and for defining appropriate risk management and governance approaches.

COPD Patients as Vulnerable Subpopulation for Exposure to Ambient Air Pollution

PURPOSE OF REVIEW

The prevalence of chronic obstructive pulmonary disease (COPD) is increasing worldwide with no known cure and an increasing number of triggers that exacerbate symptoms and speed up progression. This review aims to summarize the evidence for COPD patients being more vulnerable to air pollution exposure assessed as acute effects.

RECENT FINDINGS

Several recent systematic reviews show consistently increased risks for COPD mortality and COPD hospital admission, ranging between 2 and 3% with increasing PM_2.5 or PM₁₀. Similar adverse impacts were shown for NO_2. Also_, adverse health effects among COPD patients were also found for other gaseous pollutants such as ozone and SO₂; most of these studies could not be included in the meta-analysis we reviewed. Data from ten panel studies of COPD patients reported a small but statistically significant decline of FEV1 [- 3.38 mL (95% CI - 6.39 to - 0.37)] per increment of 10 μg/m³ PM₁₀, supporting an impact on respiratory health with increasing PM₁₀ exposure. The combined information from systematic reviews and more recent findings lead us to conclude that COPD patients are more vulnerable to ambient air pollution than healthier people.

Ambient air pollution exposures and risk of drug-resistant tuberculosis

BACKGROUND

Few epidemiological studies have explored the effects of air pollution on the risk of drug-resistant tuberculosis (DR-TB).

OBJECTIVE

To investigate the short and long term residential concentrations of ambient air pollutants (particulate matter <10 μm in diameter (PM₁₀) and particulate matter≤2.5 μm in diameter (PM_2.5), nitrogen dioxide (NO₂), sulfur dioxide (SO₂), ozone (O₃), and carbon monoxide (CO)) in relation to the risk of DR-TB in a typical air pollution city, Jinan city, China.

METHODS

A total of 752 new culture-confirmed TB cases reported in TB prevention and control institutions of Jinan from January 1, 2014 to December 31, 2015 were included. Average individual-level concentrations of air pollution for 5 different exposure windows, vary from 90 days to 720 days to diagnosis were estimated using measurements from monitor closest to the patient home addresses. Logistic regression model adjusted for potential confounders was employed to evaluate correlation between air pollution and DR-TB risk at different five exposure windows individually.

RESULTS

There were substantially increased mono-drug resistance and poly-drug resistance risks for ambient PM_2.5, PM₁₀, O₃, and CO exposures. High exposure to PM_2.5, PM₁₀, and CO was also significantly associated with increased incidence of multi-drug resistance (MDR) both in the single- and multi-pollutants regression models. The dominant positive associations for PM_2.5was observed at 540 days exposure, for O₃ was observed at 180 days exposure, and for PM₁₀ and CO was observed from 90 days to 540 days exposures.

CONCLUSIONS

Our finding suggest that exposure to ambient air pollution (PM_2.5, PM₁₀, O₃, and CO) are associated with increased risk of DR-TB. We provided epidemiological evidence of association between pollution exposure and mono-, poly- and multi-drug resistance.

Oxidative Potential by PM2.5 in the North China Plain: Generation of Hydroxyl Radical

Adverse health effects of ambient PM_2.5 ( d_p < 2.5 μm) can be associated with the production of reactive oxygen species (ROS), among which hydroxyl radical (•OH) is the most reactive. However, •OH generated by PM_2.5 has not been quantified and studied in the North China Plain (NCP), which has suffered from heavy air pollution in recent years. In this study, PM_2.5 samples were collected at an urban site (Beijing) and a suburban site (Wangdu), extracted in a cell-free surrogate lung fluid (SLF), and •OH generated in the extracts were quantified. The results show that more •OH is produced on heavily polluted days than that on clean days (2.0 and 1.6 times higher in Beijing and Wangdu, respectively). The production of •OH per unit mass (ng/μg·PM_2.5) decreases with the increase of ambient PM_2.5 concentration because SO₄^2-, NO₃^-, and NH₄⁺ dominate the increased PM_2.5, while these secondary inorganic components do not contribute to the generation of •OH. Trace metals (e.g., Fe, Cu, Se) and carbonaceous species (organic carbon and elemental carbon) correlate well with the •OH production, indicating that particles from combustion sources including coal combustion, vehicle exhaust, and industry contribute more to •OH generation.

Particulate matter and markers of glycemic control and insulin resistance in type 2 diabetic patients: result from Wellcome Trust Genetic study

There is growing evidence that air pollution is associated with increased risk of type 2 diabetes (T2DM). However, information related to whether particulate matter (PM) contributing to worsened metabolic control in T2DM patients is inconsistent. We examined the association of PM₁₀ exposure with glucose-function parameters in young-onset T2DM patients. We investigated the association between a year ambient concentration of PM₁₀ at residential places, using AERMOD dispersion model, with fasting plasma glucose (FPG), hemoglobin A1c (HbA1c), 2 h post meal plasma glucose (2hPG), homeostasis model assessment of insulin resistance (HOMA-IR), β-cell function (HOMA-β) and disposition index (DI) in 1213 diabetic patients from the Wellcome Trust Genetic study at the Diabetes Unit, KEM Hospital Research Center, Pune, India. We used linear regression models and adjusted for a variety of individual and environmental confounding variables. Possible effect modification by age, gender, waist-to-hip ratio (WHR) and smoking status were investigated. Sensitivity analysis assessed the impact of relative humidity (RH) and temperature a day before examination and anti-diabetic and HHR medication (Hydralazine, Hydrochlorothiazide and Reserpine). We found that 1 SD increment in background concentration of PM₁₀ at residential places (43.83 µg/m³) was significantly associated with 2.25 mmol/mol and 0.38 mmol/l increase in arithmetic means of HbA1c and 2hPG, respectively. A similar increase in PM₁₀ was also associated with 4.89% increase in geometric mean of HOMA-IR. The associations remained significant after adjustment to RH and temperature, and WHR and smoking enhanced the size of the effect. Our study suggests that long-term exposure to PM₁₀ is associated with higher glycaemia and insulin resistance. In context of our previous demonstration of association of SO₂ and NO _x and plasma C-reactive protein, we suggest that air pollution could influence progression of diabetes complications. Prospective studies and interventions are required to define mechanism and confirm causality.

Ambient air pollution and cardiovascular diseases: From bench to bedside

Air pollution has a great impact on health, representing one of the leading causes of death worldwide. Previous experimental and epidemiological studies suggested the role of pollutants as risk factors for cardiovascular diseases. For this reason, international guidelines included specific statements regarding the contribution of particulate matter exposure to increase the risk of these events. In this review, we summarise the main evidence concerning the mechanisms involved in the processes linking air pollutants to the development of cardiovascular diseases.

Effect of Particulate Matter Air Pollution on Cardiovascular Oxidative Stress Pathways

SIGNIFICANCE

Particulate matter (PM) air pollution is a leading cause of global cardiovascular morbidity and mortality. Understanding the biological action of PM is of particular importance in improvement of public health. Recent Advances: Both fine (PM <2.5 μM) and ultrafine particles (<0.1 μM) are widely believed to mediate their effects through redox regulated pathways. A rather simplistic graded ramp model of redox stress has been replaced by a more sophisticated understanding of the role of oxidative stress in signaling, and the realization that many of the observed effects may involve disruption and/or enhancement of normal endogenous redox signaling and induction of a potent immune-mediated response, through entrainment of multiple reactive oxygen species (ROS).

CRITICAL ISSUES

The molecular events by which pulmonary oxidative stress in response to inhalational exposure to air pollution triggers inflammation, major ROS (e.g., superoxide, hydroxyl radical, nitric oxide, and peroxynitrite) generated in air pollution exposure, types of oxidative tissue damage in target organs, contributions of nonimmune and immune cells in inflammation, and the role of protective proteins (e.g., surfactant, proteins, and antioxidants) are highly complex and may differ depending on models and concomitant disease states.

FUTURE DIRECTIONS

While the role of oxidative stress in the lung has been well demonstrated, the role of oxidative stress in mediating systemic effects especially in inflammation and injury processes needs further work. The role of antioxidant defenses with chronic exposure will also need further exploration. Antioxid. Redox Signal. 28, 797-818.

Ecklonia cava Extract and Dieckol Attenuate Cellular Lipid Peroxidation in Keratinocytes Exposed to PM10

Airborne particulate matter can cause oxidative stress, inflammation, and premature skin aging. Marine plants such as Ecklonia cava Kjellman contain high amounts of polyphenolic antioxidants. The purpose of this study was to examine the antioxidative effects of E. cava extract in cultured keratinocytes exposed to airborne particulate matter with a diameter of <10 μm (PM10). After the exposure of cultured HaCaT keratinocytes to PM10 in the absence and presence of E. cava extract and its constituents, cell viability and cellular lipid peroxidation were assessed. The effects of eckol and dieckol on cellular lipid peroxidation and cytokine expression were examined in human epidermal keratinocytes exposed to PM10. The total phenolic content of E. cava extract was the highest among the 50 marine plant extracts examined. The exposure of HaCaT cells to PM10 decreased cell viability and increased lipid peroxidation. The PM10-induced cellular lipid peroxidation was attenuated by E. cava extract and its ethyl acetate fraction. Dieckol more effectively attenuated cellular lipid peroxidation than eckol in both HaCaT cells and human epidermal keratinocytes. Dieckol and eckol attenuated the expression of inflammatory cytokines such as tumor necrosis factor- (TNF-) α, interleukin- (IL-) 1β, IL-6, and IL-8 in human epidermal keratinocytes stimulated with PM10. This study suggested that the polyphenolic constituents of E. cava, such as dieckol, attenuated the oxidative and inflammatory reactions in skin cells exposed to airborne particulate matter.

Association of PM2.5 with sleep-disordered breathing from a population-based study in Northern Taiwan urban areas

Recent studies suggest that exposure to air pollution might be associated with severity of sleep-disordered breathing (SDB). However, the association between air pollution exposure, especially particulate matter with aerodynamic diameters <= 2.5 μm (PM_2.5), and SDB is still unclear. We collected 4312 participants' data from the Taipei Medical University Hospital's Sleep Center and air pollution data from the Taiwan Environmental Protection Administration. Associations of particulate matter with aerodynamic diameters <=10 μm (PM₁₀), PM_2.5, nitrogen dioxide (NO₂), ozone (O₃) and sulfur dioxide (SO₂) with apnea-hypopnea index (AHI) and oxygen desaturation index (ODI) were investigated by generalized additive models. We found that an interquartile range (IQR) increase in 1-year mean PM_2.5 (3.4 μg/m³) and NO₂ (2.7 ppb) was associated with a 4.7% and 3.6% increase in AHI, respectively. We also observed the association of an IQR increase in 1-year mean PM_2.5 with a 2.5% increase in ODI. The similar pattern was found in the association of daily mean PM_2.5 exposure with increased AHI. Moreover, participants showed significant AHI and ODI responses to air pollution levels in spring and winter. We concluded that exposure to PM_2.5 was associated with SDB. Effects of air pollution on AHI and ODI were significant in spring and winter.