Polycyclic aromatic hydrocarbons are associated with increased risk of chronic obstructive pulmonary disease during haze events in China

Fine particulate matter disrupts bile acid homeostasis in hepatocytes via binding to and activating farnesoid X receptor

Fine particulate matter (PM2.5)-induced metabolic disorders have attracted increasing attention, however, the underlying molecular mechanism of PM2.5-induced hepatic bile acid disorder remains unclear. In this study, we investigated the effects of PM2.5 components on the disruption of bile acid in hepatocytes through farnesoid X receptor (FXR) pathway. The receptor binding assays showed that PM2.5 extracts bound to FXR directly, with half inhibitory concentration (IC50) value of 21.7 μg/mL. PM2.5 extracts significantly promoted FXR-mediated transcriptional activity at 12.5 μg/mL. In mouse primary hepatocytes, we found PM2.5 extracts (100 μg/mL) significantly decreased the total bile acid levels, inhibited the expression of bile acid synthesis gene (Cholesterol 7 alpha-hydroxylase, Cyp7a1), and increased the expression of bile acid transport genes (Multidrug resistance associated protein 2, Abcc2; and Bile salt export pump, Abcb11). Moreover, these alterations were significantly attenuated by knocking down FXR in hepatocytes. We further divided the organic components and water-soluble components from PM2.5, and found that two components bound to and activated FXR, and decreased the bile acid levels in hepatocytes. In addition, benzo[a]pyrene (B[a]P) and cadmium (Cd) were identified as two bioactive components in PM2.5-induced bile acid disorders through FXR signaling pathway. Overall, we found PM2.5 components could bind to and activate FXR, thereby disrupting bile acid synthesis and transport in hepatocytes. These new findings also provide new insights into PM2.5-induced toxicity through nuclear receptor pathways.

Benzo[a]pyrene evokes epithelial-mesenchymal transition and pulmonary fibrosis through AhR-mediated Nrf2-p62 signaling

Benzo[a]pyrene (BaP) and its metabolic end product benzo(a)pyren-7,8-dihydrodiol-9,10-epoxide (BPDE), are known toxic environmental pollutants. This study aimed to analyze whether sub-chronic BPDE exposure initiated pulmonary fibrosis and the potential mechanisms. In this work, male C57BL6/J mice were exposed to BPDE by dynamic inhalation exposure for 8 weeks. Our results indicated that sub-chronic BPDE exposure evoked pulmonary fibrosis and epithelial-mesenchymal transition (EMT) in mice. Both in vivo and in vitro, BPDE exposure promoted nuclear translocation of Snail. Further experiments indicated that nuclear factor erythroid 2-related factor 2 (Nrf2) and p62 were upregulated in BPDE-exposed alveolar epithelial cells. Moreover, Nrf2 siRNA transfection evidently attenuated BPDE-induced p62 upregulation. Besides, p62 shRNA inhibited BPDE-incurred Snail nuclear translocation and EMT. Mechanically, BPDE facilitated physical interaction between p62 and Snail in the nucleus, then repressed Snail protein degradation by p62-dependent autophagy-lysosome pathway, and finally upregulated transcriptional activity of Snail. Additionally, aryl hydrocarbon receptor (AhR) was activated in BPDE-treated alveolar epithelial cells. Dual-luciferase assay indicated activating AhR could bind to Nrf2 gene promoter. Moreover, pretreatment with CH223191 or α-naphthoflavone (α-NF), AhR antagonists, inhibited BPDE-activated Nrf2-p62 signaling, and alleviated BPDE-induced EMT and pulmonary fibrosis in mice. Taken together, AhR-mediated Nrf2-p62 signaling contributes to BaP-induced EMT and pulmonary fibrosis.

Computer-aided discovery of novel aryl hydrocarbon receptor ligands to regulate CYP1A1 expression in inflammatory macrophages

The environmental factor aryl hydrocarbon receptor (AhR), a key protein connecting the external environmental signals (e.g., environmental endocrine disruptor TCDD) to internal cellular processes, is involved in the activation of peripheral macrophages and inflammatory response in human body. Thus, there is widespread interest in finding compounds to anti-inflammatory response in macrophages by targeting human AhR. Here, ensemble docking based-virtual screening was first used to screen a library (~200,000 compounds) against human AhR ligand binding domain (LBD) and 25 compounds were identified as potential inhibitors. Then, 9 out of the 25 ligands were found to down-regulate the mRNA expression of CYP1A1 (a downstream gene of AhR signaling) in AhR overexpressing macrophages. The most potent compound AE-411/41415610 was selected for further study and found to reduce both mRNA and protein expressions level of CYP1A1 in mouse peritoneal macrophage. Moreover, protein chip signal pathway analysis indicated that AE-411/41415610 play a role in regulating JAK-STAT and AKT-mTOR pathways. In sum, the discovered hits with novel scaffolds provided a starting point for future design of more effective AhR-targeted lead compounds to regulate CYP1A1 expression of inflammatory peritoneal macrophages.

Association of environmental polycyclic aromatic hydrocarbons exposure with periodontitis in NHANES 2009-2014: A mixtures approach

BACKGROUND

Polycyclic aromatic hydrocarbons (PAHs) can invade and cause harm to the human body through various pathways, but there is currently little research on the relationship between mixed-PAHs exposure and periodontitis. The purpose of this study was to examine the effects of mixed-urinary PAHs exposure on periodontitis in adults in the United States.

METHODS

The cross-sectional study included 2749 subjects selected from the National Health and Nutrition Examination Survey (NHANES) 2009-2014 cycles. A professional examination of the periodontal status was conducted to distinguish between periodontitis and non-periodontitis based on the Centers for Disease Control and Prevention/American Academy of Periodontology (CDC/AAP) case definition. Laboratory testing of urine samples was performed to obtain the levels of urinary PAHs. Pearson correlation coefficients were utilized to determine the degree of correlation between urinary PAHs, while weighted binary logistic regression and Bayesian kernel machine regression (BKMR) were employed to evaluate the relationship between urinary PAHs and periodontitis.

RESULTS

In a single-exposure model, 3-hydroxyfluorene (OH-3F), 2-hydroxyfluorene (OH-2F), 1-hydroxyphenanthrene (OH-1Ph), and 2-hydroxyphenanthrene and 3-hydroxyphenanthrene (OH-2,3Ph) were positively associated with periodontitis risk. In the mixed-exposure model, BKMR analysis demonstrated that mixed exposure to urinary PAHs was positively associated with periodontitis, with OH-2F being the most critical factor for the overall mixed effects (posterior inclusion probability [PIP] = 0.98). Univariate exposure-response function and univariate effects analysis revealed a positive correlation between urinary OH-2F levels and periodontitis.

CONCLUSIONS

The study reveals a significant positive correlation between exposure to mixed PAHs and periodontitis, with a particular emphasis on the pivotal role of OH-2F. Mitigating PAHs in the environment may serve as a preventive measure against periodontitis and alleviate its global public health burden.

Modeling PAH Mixture Interactions in a Human In Vitro Organotypic Respiratory Model

One of the most significant challenges in human health risk assessment is to evaluate hazards from exposure to environmental chemical mixtures. Polycyclic aromatic hydrocarbons (PAHs) are a class of ubiquitous contaminants typically found as mixtures in gaseous and particulate phases in ambient air pollution associated with petrochemicals from Superfund sites and the burning of fossil fuels. However, little is understood about how PAHs in mixtures contribute to toxicity in lung cells. To investigate mixture interactions and component additivity from environmentally relevant PAHs, two synthetic mixtures were created from PAHs identified in passive air samplers at a legacy creosote site impacted by wildfires. The primary human bronchial epithelial cells differentiated at the air-liquid interface were treated with PAH mixtures at environmentally relevant proportions and evaluated for the differential expression of transcriptional biomarkers related to xenobiotic metabolism, oxidative stress response, barrier integrity, and DNA damage response. Component additivity was evaluated across all endpoints using two independent action (IA) models with and without the scaling of components by toxic equivalence factors. Both IA models exhibited trends that were unlike the observed mixture response and generally underestimated the toxicity across dose suggesting the potential for non-additive interactions of components. Overall, this study provides an example of the usefulness of mixture toxicity assessment with the currently available methods while demonstrating the need for more complex yet interpretable mixture response evaluation methods for environmental samples.

Quantitative structure-activity relationship model development for estimating the predicted No-effect concentration of petroleum hydrocarbon and derivatives in the ecological risk assessment

Quantitative structure-activity relationship (QSAR) is a cost-effective solution to directly and accurately estimating the environmental safety thresholds (ESTs) of pollutants in the ecological risk assessment due to the lack of toxicity data. In this study, QSAR models were developed for estimating the Predicted No-Effect Concentrations (PNECs) of petroleum hydrocarbons and their derivatives (PHDs) under dietary exposure, based on the quantified molecular descriptors and the obtained PNECs of 51 PHDs with given acute or chronic toxicity concentrations. Three high-reliable QSAR models were respectively developed for PHDs, aromatic hydrocarbons and their derivatives (AHDs), and alkanes, alkenes and their derivatives (ALKDs), with excellent fitting performance evidenced by high correlation coefficient (0.89-0.95) and low root mean square error (0.13-0.2 mg/kg), and high stability and predictive performance reflected by high internal and external verification coefficient (Q2LOO, 0.66-0.89; Q2F1, 0.62-0.78; Q2F2, 0.60-0.73). The investigated quantitative relationships between molecular structure and PNECs indicated that 18 autocorrelation descriptors, 3 information index descriptors, 4 barysz matrix descriptors, 6 burden modified eigenvalues descriptors, and 1 BCUT descriptor were important molecular descriptors affecting the PNECs of PHDs. The obtained results supported that PNECs of PHDs can be accurately estimated by the influencing molecular descriptors and the quantitative relationship from the developed QSAR models, that provided a new feasible solution for ESTs derivation in the ecological risk assessment.

Combined exposure of MAHs and PAHs enhanced amino acid and lipid metabolism disruption in epithelium leading asthma risk

Monoaromatic hydrocarbons (MAHs) and polycyclic aromatic hydrocarbons (PAHs) are ubiquitous air pollutants from industry, with multiple adverse effects on respiratory system. However, the underlying mechanisms of their mixture to induce asthma is still unclear. Here, we examined mixture of 8 MAHs, mixture of 16 PAHs and a total mixture (MIX) on human bronchial epithelial (16-HBE) cells. Exposure to MIX resulted in increased expressions of asthma alarm cytokines (TSLP, IL-25 and IL-33), indicating potential asthma risk. Exposure to MIX led to significant upregulation of transcriptional level of oxidative stress and inflammation biomarkers through aryl hydrocarbon receptor activation, including SOD-2, NQO-1, IL-1β, IL-6 and IL-8 with 3.1, 19.9, 3.5, 23.4, 18.7, 28.1-fold change, indicated asthma related epithelial cell lesions. A total of 25, 49 and 59 differential metabolites were identified in cells response to MAH, PAH and MIX exposure, respectively, and enrichment analysis demonstrated MIX exposure disturbing alanine, aspartate and glutamate metabolism, glutathione metabolism, methionine metabolism and sphingolipid metabolism, involved in antioxidative defense and inflammation response. Combined exposure of MAHs and PAHs may result in increased toxic risks, and provide evidence to asthma onset and deterioration.

Personal Exposure to Source-Specific Particulate Polycyclic Aromatic Hydrocarbons and Systemic Inflammation: A Cross-Sectional Study of Urban-Dwelling Older Adults in China

Environmental exposure to ambient polycyclic aromatic hydrocarbons (PAHs) can disturb the immune response. However, the evidence on adverse health effects caused by exposure to PAHs emitted from specific sources among different vulnerable subpopulations is limited. In this cross-sectional study, we aimed to evaluate whether exposure to source-specific PAHs could increase systemic inflammation in older adults. The present study included community-dwelling older adults and collected filter samples of personal exposure to PM2.5 during the winter of 2011. Blood samples were collected after the PM2.5 sample collection. We analyzed PM2.5 bound PAHs and serum inflammatory cytokines (interleukin (IL)1β, IL6, and tumor necrosis factor alpha levels. The Positive Matrix Factorization model was used to identify PAH sources. We used a linear regression model to assess the relative effects of source-specific PM2.5 bound PAHs on the levels of measured inflammatory cytokines. After controlling for confounders, exposure to PAHs emitted from biomass burning or diesel vehicle emission was significantly associated with increased serum inflammatory cytokines and systemic inflammation. These findings highlight the importance of considering exposure sources in epidemiological studies and controlling exposures to organic materials from specific sources.

Long-term cadmium exposure induces chronic obstructive pulmonary disease-like lung lesions in a mouse model

Accumulating evidences demonstrate that long-term exposure to atmospheric fine particles and air pollutants elevates the risk of chronic obstructive pulmonary disease (COPD). Cadmium (Cd) is one of the important toxic substances in atmospheric fine particles and air pollutants. In this study, we aimed to establish a mouse model to evaluate whether respiratory Cd exposure induces COPD-like lung injury. Adult male C57BL/6 mice were exposed to CdCl₂ (10 mg/L, 4 h per day) by inhaling aerosol for either 10 weeks (short-term) or 6 months (long-term). The mean serum Cd concentration was 6.26 μg/L in Cd-exposed mice. Lung weight and coefficient were elevated in long-term Cd-exposed mice. Pathological scores and alveolar destructive indices were increased in long-term Cd-exposed mouse lungs. Mean linear intercept and airway wall thickness were accordingly elevated in Cd-exposed mice. Inflammatory cell infiltration was obvious and inflammatory cytokines, including TNF-α, IL-1β, IL-6, IL-8, IL-10 and TGF-β, were up-regulated in Cd-exposed mouse lungs. α-SMA, N-cadherin and vimentin, epithelial-mesenchymal transition markers, and extracellular matrix collagen deposition around small airway, determined by Masson's trichrome staining, were shown in Cd-exposed mouse lungs. COPD-characteristic lung function decline was observed in long-term Cd-exposed mice. These outcomes show that long-term respiratory exposure to Cd induces COPD-like lung lesions for the first time.

In vitro data for fire pollutants: contribution of studies using human cell models towards firefighters' occupational

Firefighters are the principal line of defense against fires, being at elevated risk of exposure to health-relevant pollutants released during fires and burning processes. Although many biomonitoring studies exist, only a limited number of human in vitro investigations in fire risk assessment are currently available. In vitro studies stand out as valuable tools to assess the toxicity mechanisms involved following exposure to fire pollutants at a cellular level. The aim of the present review was to contextualize existing in vitro studies using human cell models exposed to chemicals emitted from fire emissions and wood smoke and discuss the implications of the observed toxic outcomes on adverse health effects detected in firefighters. Most of the reported in vitro investigations focused on monocultures respiratory models and exposure to particulate matter (PM) extracts collected from fire effluents. Overall, (1) a decrease in cellular viability, (2) enhanced oxidative stress, (3) increased pro-inflammatory cytokines levels and (4) elevated cell death frequencies were noted. However, limited information remains regarding the toxicity mechanisms initiated by firefighting activities. Hence, more studies employing advanced in vitro models and exposure systems using human cell lines are urgently needed taking into consideration different routes of exposure and health-related pollutants released from fires. Data are needed to establish and define firefighters' occupational exposure limits and to propose mitigation strategies to promote beneficial human health.

Association between co-exposure of polycyclic aromatic hydrocarbons and chronic obstructive pulmonary disease among the US adults: results from the 2013-2016 National Health and Nutrition Examination Survey

Although existing epidemiological studies have reported the relationship between single polycyclic aromatic hydrocarbon (PAH) exposure and chronic obstructive pulmonary disease (COPD), little is known about the impact of PAH mixture exposure on COPD. Therefore, we aimed to evaluate the associations of single and mixed exposures to PAHs with COPD in US adults using data from NHANES 2013-2016 by fitting three statistical methods, including multiple logistic regression, Bayesian kernel machine regression (BKMR), and quantile-based g-computation (qgcomp) models. This study included 1836 participants aged 40 and older. Multiple logistic regression showed that 2-FLU, 1-PHE, 1-PYR, and 2&3-PHE increased the risk of COPD after adjusting for all covariates. The BKMR model identified positive trends between PAH mixture and the risk of COPD in all adults and males when all PAHs were at or above their 55th percentile compared to all PAHs at their 50th percentile. The qgcomp model suggested that PAH co-exposure increased the risk of COPD (OR:1.44, 95%CI:1.09, 1.90) when each quartile increased in PAH mixture concentration, with 2-FLU having the highest weight. The combined impact also be observed in men. In conclusion, PAHs co-exposure was associated with a higher risk of COPD, especially in males, with the positive impact of 2-FLU being the most important.

Chemical composition, oxidative potential and identifying the sources of outdoor PM2.5 after the improvement of air quality in Beijing

Air pollution poses a serious threat to human health. The implementation of air pollution prevention and control policies has gradually reduced the level of atmospheric fine particles in Beijing. Exploring the latest characteristics of PM_2.5 has become the key to further improving pollution reduction measures. In the current study, outdoor PM_2.5 samples were collected in the spring and summer of Beijing, and the chemical species, oxidative potential (OP), and sources of PM_2.5 were characterized. The mean PM_2.5 concentration during the entire study period was 41.6 ± 30.9 μg m^-3. Although the PM_2.5 level in summer was lower, its OP level was significantly higher than that in spring. SO₄^2-, NH₄⁺, EC, NO^3-, and OC correlated well with volume-normalized OP (OP_v). Strong positive correlations were found between OP_v and the following elements: Cu, Pb, Zn, Ni, As, Cr, Sn, Cd, Al, and Mn. Seven sources of PM_2.5 were identified, including traffic, soil dust, secondary sulfate, coal and biomass burning, oil combustion, secondary nitrate, and industry. Multiple regression analysis indicated that coal and biomass combustion, industry, and traffic were the main contributors to the OP_v in spring, while secondary sulfate, oil combustion, and industry played a leading role in summer. The source region analysis revealed that different pollution sources were related to specific geographic distributions. In addition to local emission reduction policies, multi-provincial cooperation is necessary to further improve Beijing's air quality and reduce the adverse health effects of PM_2.5.

Establishment of an artificial particulate matter-induced lung disease model through analyzing pathological changes and transcriptomic profiles in mice

Particulate matter (PM), an environmental risk factor, is linked with health risks such as respiratory diseases. This study aimed to establish an animal model of PM-induced lung injury with artificial PM (APM) and identify the potential of APM for toxicological research. APM was generated from graphite at 600 °C and combined with ethylene. We analyzed diesel exhaust particulate (DEP) and APM compositions and compared toxicity and transcriptomic profiling in lungs according to the exposure. For the animal study, C57BL/6 male mice were intratracheally administered vehicle, DEP, or APM. DEP or APM increased relative lung weight, inflammatory cell numbers, and inflammatory protein levels compared with the vehicle control. Histological assessments showed an increase in particle-pigment alveolar macrophages and slight inflammation in the lungs of DEP and APM mice. In the only APM group, granulomatous inflammation, pulmonary fibrosis, and mucous hyperplasia were observed in the lungs of some individuals. This is the first study to compare pulmonary toxicity between DEP and APM in an animal model. Our results suggest that the APM-treated animal model may contribute to understanding the harmful effects of PM in toxicological studies showing that APM can induce various lung diseases according to different doses of APM.

Polycyclic aromatic hydrocarbon exposure burden: Individual and mixture analyses of associations with chronic obstructive pulmonary disease risk

Accumulating data demonstrate that polycyclic aromatic hydrocarbons (PAH) exposure is linked to compromised respiratory diseases. This study aimed to analyze urinary PAH metabolites and their associations with chronic obstructive pulmonary disease (COPD) in a sample size of 3015 subjects from a total population of 50,588 from the National Health and Nutrition Examination Survey (NHANES) in 2007-2016. Results showed that the most predominant metabolite was 1-Hydroxynaphthalene (1-NAP, 84%) with a geometric mean concentration of 50,265 ng/L, followed by its homologue 2-NAP (10%), both of which arose from sources including road emission, smoking and cooking. Multiple logistic regression showed that seven of the ten major PAH metabolites were correlated with increased COPD risk: including 1-NAP (OR: 1.83, 95%CI: 1.25, 2.69), 2-Hydroxyfluorene (2-FLU, OR: 2.29, 95%CI: 1.42, 3.68) and 1-Hydroxyphenanthrene (1-PHE, OR: 2.79, 95%CI: 1.85, 4.21), when compared to the lowest tertile after adjusted for covariates. Total exposure burden per PAH congener sub-group demonstrated persistent positive correlation with COPD for ∑PHE (OR: 1.80, 95%CI: 1.34, 2.43) and ∑FLU (OR: 2.74, 95%CI: 1.77, 4.23) after adjusted for covariates. To address the contribution of PAH exposure as mixture towards COPD, weighted quantile sum (WQS) regression analyses revealed that 1-NAP, 9-Hydroxyfluorene (9-FLU), 3-Hydroxyfluorene (3-FLU) and 1-PHE were among the top contributors in the associations with COPD. Our results demonstrate the contemporary yet ongoing exposure burden of PAH exposure for over a decade, particularly towards NAPs and FLUs that contribute significantly to COPD risk, calling for more timely environmental regulation.

Prediction and early warning model of mixed exposure to air pollution and meteorological factors on death of respiratory diseases based on machine learning

In recent years, with the repeated occurrence of extreme weather and the continuous increase of air pollution, the incidence of weather-related diseases has increased yearly. Air pollution and extreme temperature threaten sensitive groups' lives, among which air pollution is most closely related to respiratory diseases. Owing to the skewed attention, timely intervention is necessary to better predict and warn the occurrence of death from respiratory diseases. In this paper, according to the existing research, based on a number of environmental monitoring data, the regression model is established by integrating the machine learning methods XGBoost, support vector machine (SVM), and generalized additive model (GAM) model. The distributed lag nonlinear model (DLNM) is used to set the warning threshold to transform the data and establish the warning model. According to the DLNM model, the cumulative lag effect of meteorological factors is explored. There is a cumulative lag effect between air temperature and PM2.5, which reaches the maximum when the lag is 3 days and 5 days, respectively. If the low temperature and high environmental pollutants (PM2.5) continue to influence for a long time, the death risk of respiratory diseases will continue to rise, and the early warning model based on DLNM has better performance.

Comparative pulmonary toxicity assessment of tungsten trioxide and tungsten trioxide hydrate nanoparticles

Tungsten trioxide (WO₃)-based nanoparticles (NPs) are gaining popularity because of their exciting potential for photocatalytic applications; however, the toxic potential of WO₃-based NPs remains a concern. In this study, we evaluated the toxic risk of WO₃ NPs and hydrated WO₃ NPs (WO₃·H₂O NPs) using lung cells and explored the underlying mechanism. WO₃ NPs and WO₃·H₂O NPs significantly decreased the number of viable cells (59.5 %-85.8 % of control) and promoted apoptosis in human alveolar basal epithelial A549 cells after a 24-h exposure. Both WO₃ NPs and WO₃·H₂O NPs reduced the expression of heme oxygenase-1 (0.15-0.33 folds of control) and superoxide dismutase 2 (0.31-0.66 folds of control) and increased reactive oxygen species production (1.4-2.6 folds of control) and 8-hydroxy-2'-deoxyguanosine accumulation (1.22-1.43 folds of control). The results showed that WO₃ NPs have higher cytotoxicity and oxidative potential than WO₃·H₂O NPs. In addition, the WO₃ NP cellular uptake rate was significantly higher than the WO₃·H₂O NPs uptake rate in pulmonary cells. The greater extent of oxidative adverse effects induced by WO₃-based NPs appears to be related to the enhanced particle uptake. WO₃ NPs and WO₃·H₂O NPs exposure led to the secretion of inflammatory factor interleukin 6 (1.63-3.42 folds of control). Decreases in serpin family A member 1 gene expression (0.28-0.58 folds of control) and increases in the oxidation of neutrophil elastase inhibitor (1.34-1.62 folds of control) in pulmonary cells also suggest that exposure to WO₃ NPs and WO₃·H₂O NPs raises the risk of developing chronic obstructive pulmonary disease. Taken together, our findings indicate that the toxic risk of WO₃ NPs and WO₃·H₂O NPs must be considered when manufacturing and applying WO₃-based NPs.

Selenomethionine mitigate PM2.5-induced cellular senescence in the lung via attenuating inflammatory response mediated by cGAS/STING/NF-κB pathway

Particulate matter 2.5 (PM2.5) is a widely known atmospheric pollutant which can induce the aging-related pulmonary diseases such as acute respiratory distress syndrome (ARDS), chronic obstructive pulmonary disease (COPD) and interstitial pulmonary fibrosis (IPF). In recent years, with the increasing atmospheric pollution, airborne fine PM2.5, which is an integral part of air pollutants, has become a thorny problem. Hence, this study focused on the effect of PM2.5 on cellular senescence in the lung, identifying which inflammatory pathway mediated PM2.5-induced cellular senescence and how to play a protective role against this issue. Our data suggested that PM2.5 induced time- and concentration-dependent increasement in the senescence of A549 cells. Using an inhibitor of cGAS (PF-06928215) and an inhibitor of NF-κB (BAY 11-7082), it was revealed that PM2.5-induced senescence was regulated by inflammatory response, which was closely related to the cGAS/STING/NF-κB pathway activated by DNA damage. Moreover, our study also showed that the pretreatment with selenomethionine (Se-Met) could inhibit inflammatory response and prevent cellular senescence by hindering cGAS/STING/NF-κB pathway in A549 cells exposed to PM2.5. Furthermore, in vivo C57BL/6J mice model demonstrated that aging of mouse lung tissue caused by PM2.5 was attenuated by decreasing cGAS expression after Se-Met treatment. Our findings indicated that selenium made a defense capability for PM2.5-induced cellular senescence in the lung, which provided a novel insight for resisting the harm of PM2.5 to human health.

Effect of polycyclic aromatic hydrocarbons on immunity

Nearly a quarter of the total number of deaths in the world are caused by unhealthy living or working environments. Therefore, we consider it significant to introduce the effect of a widely distributed component of air/water/food-source contaminants, polycyclic aromatic hydrocarbons (PAHs), on the human body, especially on immunity in this review. PAHs are a large class of organic compounds containing two or more benzene rings. PAH exposure could occur in most people through breath, smoke, food, and direct skin contact, resulting in both cellular immunosuppression and humoral immunosuppression. PAHs usually lead to the exacerbation of autoimmune diseases by regulating the balance of T helper cell 17 and regulatory T cells, and promoting type 2 immunity. However, the receptor of PAHs, aryl hydrocarbon receptor (AhR), appears to exhibit duality in the immune response, which seems to explain some seemingly opposite experimental results. In addition, PAH exposure was also able to exacerbate allergic reactions and regulate monocytes to a certain extent. The specific regulation mechanisms of immune system include the assistance of AhR, the activation of the CYP-ROS axis, the recruitment of intracellular calcium, and some epigenetic mechanisms. This review aims to summarize our current understanding on the impact of PAHs in the immune system and some related diseases such as cancer, autoimmune diseases (rheumatoid arthritis, type 1 diabetes, multiple sclerosis, and systemic lupus erythematosus), and allergic diseases (asthma and atopic dermatitis). Finally, we also propose future research directions for the prevention or treatment on environmental induced diseases.

Association between environmental toxic metals, arsenic and polycyclic aromatic hydrocarbons and chronic obstructive pulmonary disease in the US adult population

Associations between environmental metals and chemicals and adverse human health effects have emerged recently, but the links among environmental metals and respiratory diseases are less studied. The aim of this study was to assess 14 urinary metals (cadmium, barium, cobalt, molybdenum, mercury, cesium, manganese, antimony, lead, tin, strontium, tungsten, thallium, and uranium), seven species of arsenic (arsenous acid, arsenic acid, arsenobetaine, arsenocholine, dimethylarsinic acid, monomethylarsonic acid, and total arsenic) and seven polycyclic aromatic hydrocarbon (PAH) (1-hydroxynaphthalene, 2-hydroxynaphthalene, 3-hydroxyfluorene, 2-hydroxyfluorene, 1-hydroxyphenanthrene, 1-hydroxypyrene, 2 & 3-hydroxyphenanthrene) compounds' concentrations in urine and the correlation with chronic obstructive pulmonary disease (COPD) in the adult US population. A cross-sectional analysis using the 2013-2014 and 2015-2016 National Health and Nutrition Examination Survey (NHANES) dataset was conducted. Self-questionnaires related to COPD criteria were used to identify the COPD cases. The correlation between urinary metals and PAH compounds and COPD was calculated. The total study population analyzed included 2885 adults aged 20 years and older. Seven types of urinary PAHs including 1-hydroxynaphthalene [odds ratio (OR): 1.832, 95% confidence interval (CI): 1.210, 2.775], 2-hydroxynaphthalene [OR: 3.361, 95% CI: 1.519, 7.440], 3-hydroxyfluorene [OR: 2.641, 95% CI: 1.381, 5.053], 2-hydroxyfluorene [OR: 3.628, 95% CI: 1.754, 7.506], 1-hydroxyphenanthrene [OR: 2.864, 95% CI: 1.307, 6.277], 1-hydroxypyrene [OR: 4.949, 95% CI: 2.540, 9.643] and 2 & 3-hydroxyphenanthrene [OR: 3.487, 95% CI: 1.382, 8.795] were positively associated with COPD. Urinary cadmium [OR: 12.382, 95% CI: 4.459, 34.383] and tin [OR: 1.743, 95% CI: 1.189, 2.555] showed positive associations with increased odds of COPD. The other types of urinary metals were not associated with COPD. The study observed that urinary PAHs, cadmium, and tin are significantly associated with COPD.

Assessment of the association of exposure to polycyclic aromatic hydrocarbons, oxidative stress, and inflammation: A cross-sectional study in Augsburg, Germany

BACKGROUND

Exposure to polycyclic aromatic hydrocarbons (PAHs) has been linked to acute and chronic health effects through the suggested pathways of oxidative stress and inflammation. However, evidence is still limited. We aimed to investigate jointly the relationship of PAHs, oxidative stress, and inflammation.

METHODS

We measured 13 biomarkers of PAH exposure (n = 6: hydroxylated polycyclic aromatic hydrocarbons, [OH-PAHs]), oxidative stress (n = 6: malondialdehyde (MDA); 8-hydroxy-2'-deoxyguanosine (8-OHdG); and 4 representatives of the compound class of F_2α-isoprostanes) in urine, and inflammation (n = 1: high-sensitivity C-reactive protein, [hs-CRP]) in serum from 400 participants at the second follow-up (2013/2014) of the German KORA survey S4. Multiple linear regression models were applied to investigate the interplay between biomarkers.

RESULTS

Concentrations of biomarkers varied according to sex, age, smoking status, season, and a history of obesity, diabetes, or chronic kidney disease. All OH-PAHs were significantly and positively associated with oxidative stress biomarkers. An interquartile range (IQR) increase in sum OH-PAHs was associated with a 13.3% (95% CI: 9.9%, 16.9%) increase in MDA, a 6.5% (95% CI: 3.5%, 9.6%) increase in 8-OHdG, and an 8.4% (95% CI: 6.6%, 11.3%) increase in sum F_2α-isoprostanes. Associations were more pronounced between OH-PAHs and F_2α-isoprostanes but also between OH-PAHs and 8-OHdG for participants with potential underlying systemic inflammation (hs-CRP ≥ 3 mg/L). We observed no association between OH-PAHs and hs-CRP levels. While 8-OHdG was significantly positively associated with hs-CRP (13.7% [95% CI: 2.2%, 26.5%] per IQR increase in 8-OHdG), F_2α-isoprostanes and MDA indicated only a positive or null association, respectively.

CONCLUSION

The results of this cross-sectional study suggest, at a population level, that exposure to PAHs is associated with oxidative stress even in a low exposure setting. Oxidative stress markers, but not PAHs, were associated with inflammation. Individual risk factors were important contributors to these processes and should be considered in future studies. Further longitudinal studies are necessary to investigate the causal chain of the associations.

Spatial-temporal variability and heath impact of particulate matter during a 2019-2020 biomass burning event in Southeast Asia

To understand the characteristics of particulate matter (PM) in the Southeast Asia region, the spatial-temporal concentrations of PM₁₀, PM_2.5 and PM₁ in Malaysia (Putrajaya, Bukit Fraser and Kota Samarahan) and Thailand (Chiang Mai) were determined using the AS-LUNG V.2 Outdoor sensor. The period of measurement was over a year from 2019 to 2020. The highest concentrations of all sizes of PM in Putrajaya, Bukit Fraser and Kota Samarahan were observed in September 2019 while the highest PM₁₀, PM_2.5 and PM₁ concentrations in Chiang Mai were observed between March and early April 2020 with 24 h average concentrations during haze days in ranges 83.7-216 µg m^-3, 78.3-209 µg m^-3 and 57.2-140 µg m^-3, respectively. The average PM_2.5/PM₁₀ ratio during haze days was 0.93 ± 0.05, which was higher than the average for normal days (0.89 ± 0.13) for all sites, indicating higher PM_2.5 concentrations during haze days compared to normal days. An analysis of particle deposition in the human respiratory tract showed a higher total deposition fraction value during haze days than on non-haze days. The result from this study indicated that Malaysia and Thailand are highly affected by biomass burning activity during the dry seasons and the Southwest monsoon.

Adverse pulmonary impacts of environmental concentrations of oil mist particulate matter in normal human bronchial epithelial cell

Airborne oil mist particulate matter (OMPM) is generated during industrial processes such as metalworking and may be associated with pulmonary dysfunction. In this study, we employed the normal human bronchial epithelial BEAS-2B cell line to elucidate the association between pulmonary toxicity and OMPM of 2.5-10 μm, 1.0-2.5 μm and <1.0 μm particle sizes (OMPM_10-2.5, OMPM_2.5-1.0 and OMPM_1.0). We measured OMPM concentrations at a precision machinery factory to estimate lung deposition rates and select realistic environmental concentrations for testing. All OMPMs (1-50 μg/cm²) significantly decreased BEAS-2B cell viability (>38% of control), except for low-dose OMPM_1.0 (1 μg/cm²). OMPM_10-2.5 and OMPM_2.5-1.0, but not OMPM_1.0, induced oxidative stress (1.5-4-fold increase compared with the control) and increased the production of proinflammatory cytokines (1.5-3-fold). However, only OMPM_1.0 induced pulmonary epithelial barrier dysfunction via depletion of zonula occludens (0.65-0.8-fold) and α1-antitrypsin proteins (0.65-0.8-fold). In conclusion, a higher risk of lung disease was associated with smaller particle size OMPM. Exposure to OMPM_1.0 may be a potential risk factor for chronic obstructive pulmonary disease. The evidence also demonstrates that occupational exposure to OMPM may cause pulmonary disease at very low concentrations.

The Aryl Hydrocarbon Receptor (AHR): A Novel Therapeutic Target for Pulmonary Diseases?

The aryl hydrocarbon receptor (AHR) is a cytoplasmic transcription factor that is well-known for regulating xenobiotic metabolism. Studies in knockout and transgenic mice indicate that the AHR plays a vital role in the development of liver and regulation of reproductive, cardiovascular, hematopoietic, and immune homeostasis. In this focused review on lung diseases associated with acute injury and alveolar development, we reviewed and summarized the current literature on the mechanistic role(s) and therapeutic potential of the AHR in acute lung injury, chronic obstructive pulmonary disease, and bronchopulmonary dysplasia (BPD). Pre-clinical studies indicate that endogenous AHR activation is necessary to protect neonatal and adult lungs against hyperoxia- and cigarette smoke-induced injury. Our goal is to provide insight into the high translational potential of the AHR in the meaningful management of infants and adults with these lung disorders that lack curative therapies.

Risk factors in air pollution exposome contributing to higher levels of TNFα in COPD patients

BACKGROUND

Air pollutants are found associated with various health effects in chronic obstructive pulmonary patients. Given the complicate chemical components of air pollutants, it is not clear which components are the main risk factors for these health effects.

OBJECTIVES

Based on the COPD in Beijing (COPDB) study and exposome concept, we examined comprehensively the air pollution components to screen out high-risk factors for systemic inflammation of COPD patients.

METHODS

Concentrations of PM with aerodynamic diameter ≤ 2.5 μm (PM_2.5), ultrafine and accumulated-mode particles (UFPs and Acc), PM_2.5-contained carbonaceous components/elements/water soluble ions, gaseous pollutants, temperature, and relative humidity (RH) were continuously monitored around participants. Urinary polycyclic aromatic hydrocarbons (PAHs) and cotinine, and serum tumor necrosis factor α (TNFα) were measured from 53 COPD and 82 non-COPD participants. Lifestyle variables were recorded using follow-up questionnaire. Linear mixed effects (LME) models were used to assess the associations of TNFα differences with exposure to air pollutants, meteorological variations, and lifestyle.

RESULTS

In COPD patients, the associations of TNFα differences with exposure to ozone, Cd, UFPs, Acc, 2-hydroxydibenzofuran, temperature and RH parameters, and several elements in PM_2.5 were significant in certain time-windows. For example, per interquartile range (IQR) increase in average ozone concentration 14 d before visits was associated with 17.3% (95% confidence interval: 6.8%, 27.7%) TNFα difference. Associations between ozone, Cd, UFPs, Acc, the maximum value of RH, and 2-hydroxydibenzofuran exposure and TNFα differences remained robust in two-pollutant models, and contributed to 19.0%, 10.5%, 2.2%, 1.6%, 2.1%, and 1.5% TNFα differences, respectively. Among the high-risk factors for COPD patients, the responses to UFPs, Acc, and 2-hydroxydibenzofuran were not robust in non-COPD participants.

DISCUSSION

Ozone, Cd, UFPs, Acc, PAHs exposure and RH variation were high-risk factors of systemic inflammation for COPD patients, and the profile of high-risk factors were different from those in general population.

Nonlinear Influence of Chinese Real Estate Development on Environmental Pollution: New Evidence from Spatial Econometric Model

Environmental pollution is a problem of universal concern throughout the globe. The development of real estate industry not only consumes huge resources, but also has close ties with high-consumption industries such as the construction industry. However, previous studies have rarely explored the impact of real estate development on environmental pollution. Therefore, this paper employs the entropy method to construct a comprehensive index of environmental pollution based on panel data of 31 provinces in China from 2000 to 2017, and empirically examines the impact of real estate development on environmental pollution. This article uses real estate investment to measure the development of the real estate industry. In view of the high spatial autocorrelation of environmental pollution, this paper selects a spatial econometric model. The empirical study found that: (1) By using the Spatial Durbin Model, real estate development has an inverted U-shaped impact on environmental pollution. Meanwhile, most cities have not yet reached the turning point; that is, with the continuous development of the real estate industry, environmental pollution will continue to increase. (2) Further regional heterogeneity found that the inverted U-shaped relationship still exists in coastal and inland areas. (3) Finally, this article used the Spatial Mediation Model to explain the nonlinear impact of real estate development on environmental pollution, with two important mediating variables: population density and industrial structure. Through the above analysis, it can be observed that real estate development has a significant impact on environmental pollution. Thus, the country and the government can reduce environmental pollution by improving the investment structure, using environmentally friendly building materials, guiding population flow and promoting industrial upgrading.

N-acetylcysteine alleviates pulmonary inflammatory response during benzo[a]pyrene-evoked acute lung injury

Benzo[a]pyrene (BaP), a representative polycyclic aromatic hydrocarbon, exists widely in automobile emissions and polluted atmosphere. The current study aimed to describe pulmonary inflammation during BaP-induced acute lung injury (ALI). All mice except controls were intratracheally instilled with a single dose of BaP (90 μg per mouse). The alveolar structure was damaged, accompanied by numerous inflammatory cell infiltration around pulmonary interstitium and small airway. Airway wall area and mean linear intercept were reduced in BaP-exposed mouse lungs. By contrast, airway wall thickness and destructive index were elevated in BaP-exposed mouse lungs. Several inflammatory genes, such as Tnf-α, Il-1β, Il-6, Mip-2, Kc, and Mcp-1, were upregulated in mouse lungs. Phosphorylated IκBα was elevated in BaP-exposed mouse lungs. Nuclear translocation of NF-κB p65 and p50 was accordingly observed in BaP-exposed mouse lungs. Several molecules of the MAPK pathway, including JNK, ERK1/2, and p38, were activated in mouse lungs. Of interest, pretreatment with N-acetylcysteine (NAC), an antioxidant, alleviated BaP-induced ALI. Moreover, NAC attenuated BaP-induced inflammatory cell infiltration in mouse lungs and inflammatory gene upregulation in A549 cells. In addition, NAC attenuated BaP-induced NF-κB activation in A549 cells and mouse lungs. These results suggest that NAC alleviates pulmonary inflammatory response during BaP-evoked ALI.

Free Radicals and Actinobacteria as a Misexplored Goldmine of Antioxidant Compounds

Free radicals are highly reactive unstable molecules, which can be synthesized in different ways, considered harmful and threatening to humans; these chemical species have free traffic throughout the human body, interacting with biological molecules and human body organ tissues. The interaction between free radicals and biological molecules is the main factor for disease development or pre-existing disease symptoms aggravation. Antioxidants are chemical compounds able to donate electric charge to stabilize molecules such as free radicals. Recent studies have proved the benefits of antioxidants intake in health improvement. In this way, the search for natural sources of antioxidants has become an ascending trend. In this field, the microbial sources are considered poorly explored compared to the numerous amount of other compounds obtained from them, especially from Actinobacteria. The searched literature about Actinobacteria highlights an important capacity of producing natural antioxidants; however, there is a lack of in vivo studies of these isolated compounds. In this review, we gathered information that supports our point of view that Actinobacteria is a truly renewable and superficially explored source of natural antioxidants. Furthermore, our purpose is also to point this limitation and stimulate more researches in this area.

Association between exposure to polycyclic aromatic hydrocarbons and lipid peroxidation in patients with chronic obstructive pulmonary disease

Polycyclic aromatic hydrocarbons (PAHs) are toxic airborne pollutants and may cause adverse effects at high level of oxidative stress. Here we hypothesized that individuals with impaired lung function are susceptible to PAHs associated oxidative damage. Hence, we carried out a panel study and conducted four follow-up visits on 40 chronic obstructive pulmonary disease (COPD) patients and 75 healthy controls. Hydroxylated PAHs (OH-PAHs) and malonaldehyde (MDA) were measured in urine as exposure and oxidative stress markers, respectively, which showed significant association in all participants. Quantitatively, a 1-fold increase in OH-PAHs was associated with a 4.1-15.1% elevation of MDA. The association between OH-PAHs and MDA levels became stronger in participants with impaired lung function. For 1% decrease of FEV1/FVC, the increase of MDA associated with a 1-fold increase in OH-PAHs was up to 0.49%, suggesting an increased susceptibility to PAH-induced oxidative damage in individuals with worse lung function. This study observed that impaired lung function modified the association between PAH exposure and oxidative damage, which might accelerate the aggravation of COPD, and therefore highlighted the necessity of protection measures to decrease the additional adverse effects of air pollution exposure. CAPSULE: Individuals with worse lung function may be more susceptible to PAH-induced lipid peroxidation.

Polycyclic aromatic hydrocarbons induce endothelial injury through miR-155 to promote atherosclerosis

Polycyclic aromatic hydrocarbons (PAHs) are considered as an external factor that induces atherosclerotic cardiovascular disease. Although miR-155 is known to be involved in cardiovascular disease, whether it is involved in PAH-induced arteriosclerosis remains unclear. We evaluated the effects of PAHs on vascularization, permeability, and miR-155 expression in HUVECs. We found that PAHs-induced sclerosis of HUVECs was characterized by increasing permeability, decreasing proliferation, and vascular lumen number. The expression of miR-155 was upregulated by PAHs treatment, and transfection with miR-155 inhibitor could reverse above effect of PAHs-induced sclerosis. Meanwhile, transcriptome sequencing revealed that 63 genes were downregulated in the group of PAHs treatment alone, and were then upregulated in the miR-155 inhibitor group. These genes were mainly involved in complement and coagulation cascades, cytokine-cytokine receptor interaction, TNF signaling pathway, and NF-kappa B signaling pathway. Among these 63 genes, SERPIND1 was directly targeted and regulated by miR-155. Further in vivo experiments in ApoE^-/- mice confirmed that PAH accelerates the development of arteriosclerosis by promoting the expression of miR-155 to downregulate the SERPIND1. Therefore, PAH exaggerates atherosclerosis by activating miR-155-dependent endothelial injury. This study provides a fundamental insight on the miR-155 mechanism for PAHs enhancing atherosclerosis and miR-155 potentially serving as a novel drug target.

Air pollution increases human health risks of PM2.5-bound PAHs and nitro-PAHs in the Yangtze River Delta, China

Identifying the nature and extent of atmospheric PM_2.5-bound toxic organic pollutants is beneficial to evaluate human health risks of air pollution. Seasonal observations of PM_2.5-bound polycyclic aromatic hydrocarbons (PAHs) and nitro-PAHs (NPAHs) in the Yangtze River Delta (YRD) were investigated, along with criteria air pollutants and meteorological parameters. With the elevated PM_2.5 level, the percentage of 4-ring PAHs and typical NPAH including 3-Nitrobiphenyl (3-NBP) and 2-Nitrofluoranthene (2-NFLT) increased by 19-40%. PM_2.5-bound 2-NFLT was positively correlated with O₃ and NO₂, suggesting the contribution of atmospheric oxidation capacity to enhance the secondary formation of NPAHs in the atmosphere. Positive matrix factorization (PMF) analysis indicated that traffic emissions (44.9-48.7%), coal and biomass combustion (27.6-36.0%) and natural gas and volatilization (15.3-27.5%) were major sources of PAHs, and secondary formation (39.8-53.8%) was a predominant contributor to total NPAH concentrations. Backward trajectory analysis showed that air masses from North China transported to the YRD region increased PAH and NPAH concentrations. Compare to clean days, the BaP equivalent concentrations of total PAHs and NPAHs during haze pollution days were enhanced by 10-25 and 2-6 times, respectively. The Incremental Lifetime Cancer Risks (ILCRs) of PAHs by inhalation exposure also indicated high potential health risks in the YRD region. The results implied that the health risks of PM_2.5-bound PAHs and NPAHs could be sharply enhanced with the increase of PM_2.5 concentrations.

Benzo(a)pyrene induces MUC5AC expression through the AhR/mitochondrial ROS/ERK pathway in airway epithelial cells

OBJECTIVES

Benzo(a)pyrene (BaP) is a ubiquitous air pollutants, and BaP exposure leads to a risk of respiratory diseases. The oversecretion of airway mucus and high expression of mucin 5AC (MUC5AC) are associated with common respiratory disorders caused by air pollution. We aimed to investigate the effect of BaP on MUC5AC expression, especially the mechanisms by which BaP induces MUC5AC gene expression.

METHODS

The human airway epithelial cell NCI-H292 was used to test the effects of BaP on the expression of MUC5AC in vitro. MUC5AC mRNA and protein expression were assessed with real-time quantitative PCR, immunochemistry, and western blotting. A luciferase assay was conducted to detect the activity of the promoter. The total cellular ROS and mitochondrial ROS were measured by corresponding probes. Small-interfering RNAs were used for gene silencing. AhR-overexpressing cell lines were constructed by transfection with AhR overexpression lentivirus.

RESULTS

We found that BaP stimulation upregulated the MUC5AC mRNA and protein levels and activated the ERK pathway. Suppressing ERK with U0126 (an ERK inhibitor) or knocking down ERK with siRNA decreased BaP-induced MUC5AC expression. The luciferase activity transfected with the MUC5AC promoter and cAMP-response element (CRE) was increased after BaP treatment, whereas CREB siRNA suppressed the BaP-induced overexpression of MUC5AC. In addition, BaP increased mitochondrial ROS production, and Mito-TEMP, a mitochondrial ROS inhibitor, inhibited BaP-induced MUC5AC expression and ERK activation. BaP increased the mRNA levels of CYP1A1 and CYP1B1, while Alizarin, a CYP1s inhibitor, suppressed the effects of BaP, including the MUC5AC overexpression, ERK activation and mitochondrial ROS generation. BaP induced the translocation of aryl hydrocarbon receptor (AhR) from the cytoplasm to the nucleus. SiRNA-mediated knockdown or chemical inhibition of AhR decreased the BaP-induced expression of MUC5AC, while the overexpression of AhR significantly enhanced the BaP-induced expression of MUC5AC. ITE, an endogenous AhR ligand, also upregulated the mRNA and protein expression of MUC5AC. Furthermore, resveratrol treatment inhibited the BaP-induced MUC5AC overexpression, AhR translocation, mitochondrial ROS production and ERK pathway activation.

CONCLUSION

Here, we highlighted the crucial role of AhR/mitochondrial ROS/ERK pathway activation in BaP-induced MUC5AC overexpression and identified resveratrol as a promising drug to reduce BaP-induced MUC5AC overexpression.

The impact of pyrolysis temperature on physicochemical properties and pulmonary toxicity of tobacco stem micro-biochar

Biochars (BCs) are currently widely used, yet their impact on human health is mostly unknown. We generated micro-tobacco stem-pyrolysed BCs (mTBCs) at different pyrolysis temperatures and assessed pulmonary toxicity in normal human lung epithelial BEAS-2B cells. mTBCs generated at 350 °C (mTBC350) and 650 °C (mTBC650) were analysed and compared for physicochemical properties and adverse effects. Pyrolysis temperature had a significant influence on chemical composition, particle size, specific surface area and aromatic carbon structure. mTBC650 displayed a highly ordered aromatic carbon structure with smaller particle size, high surface area (20.09 m2/g) and high polycyclic aromatic hydrocarbon and metal content. This composition could promote reactive oxygen species accumulation accompanied by greater cytotoxicity, genotoxicity and epithelial barrier malfunction in cultured cells. Thus, the risk of pulmonary toxicity owing to micro-BCs (mBCs) is affected by pyrolysis temperature. Long-term exposure to mBCs produced at high temperatures may lead to or exacerbate pulmonary disease.

Differential time-lag effects of ambient PM2.5 and PM2.5-bound PAHs on asthma emergency department visits

Epidemiological studies have suggested the effects of ambient fine particles (PM_2.5) on asthma, but the effects of specific components of PM_2.5 on asthma remain to be explored. Here, we studied the effect of PM_2.5-bound polycyclic aromatic hydrocarbons (PAHs) on asthma acute exacerbation. The data on daily counts of emergency room visits (ERVs) were obtained from Wan Fang Medical Center, Taipei, Taiwan, from 2012 to 2015. The daily concentrations of PM_2.5 and pollutant gases were obtained from a local air quality monitoring station. The levels of PM_2.5-bound PAH were estimated by an established grid-scale model. Relative risks for ERVs as the increase in the level of ambient pollutants were calculated by using a generalized additive model of Poisson regression. In the present study, we observed statistically significant positive associations between PM_2.5 and asthma ERVs for all age groups. PM_2.5-bound PAH was also associated with asthma ERVs for all age groups. In the adult subgroup analysis, there was a significant association between PM_2.5-bound PAH and asthma ERVs at lags 1 and 2 (RR 1.289, 95% CI 1.050-1.582 and RR 1.242, 95% CI 1.039-1.485). The impacts of air pollution on the risk of pediatric asthma ERV were found to be significant for PM_2.5 at lag day 0 (RR 1.310, 95% CI 1.069-1.606). Moreover, pediatric asthma ERVs were significantly associated with the levels of PM_2.5-bound PAH at lag 1 and 2 days (RR 1.576, 95% CI 1.371-1.810 and RR 1.426, 95% CI 1.265-1.607). The study provides evidence that PM_2.5-bound PAHs were associated with an increased risk of asthma attacks. Our data further suggested that traffic exhaust is a primary source of PM_2.5-bound PAHs.

Potential role of polycyclic aromatic hydrocarbons in air pollution-induced non-malignant respiratory diseases

Epidemiological studies have found strong associations between air pollution and respiratory effects including development and/or exacerbation of asthma and chronic obstructive pulmonary disease (COPD) as well as increased occurrence of respiratory infections and lung cancer. It has become increasingly clear that also polycyclic aromatic hydrocarbons (PAHs) may affect processes linked to non-malignant diseases in the airways. The aim of the present paper was to review epidemiological studies on associations between gas phase and particle-bound PAHs in ambient air and non-malignant respiratory diseases or closely related physiological processes, to assess whether PAH-exposure may explain some of the effects associated with air pollution. Based on experimental in vivo and in vitro studies, we also explore possible mechanisms for how different PAHs may contribute to such events. Epidemiological studies show strongest evidence for an association between PAHs and asthma development and respiratory function in children. This is supported by studies on prenatal and postnatal exposure. Exposure to PAHs in adults seems to be linked to respiratory functions, exacerbation of asthma and increased morbidity/mortality of obstructive lung diseases. However, available studies are few and weak. Notably, the PAHs measured in plasma/urine also represent other exposure routes than inhalation. Furthermore, the role of PAHs measured in air is difficult to disentangle from that of other air pollution components originating from combustion processes. Experimental studies show that PAHs may trigger various processes linked to non-malignant respiratory diseases. Physiological- and pathological responses include redox imbalance, oxidative stress, inflammation both from the innate and adaptive immune systems, smooth muscle constriction, epithelial- and endothelial dysfunction and dysregulated lung development. Such biological responses may at the molecular level be initiated by PAH-binding to the aryl hydrocarbon receptor (AhR), but possibly also through interactions with beta-adrenergic receptors. In addition, reactive PAH metabolites or reactive oxygen species (ROS) may interfere directly with ion transporters and enzymes involved in signal transduction. Overall, the reviewed literature shows that respiratory effects of PAH-exposure in ambient air may extend beyond lung cancer. The relative importance of the specific PAHs ability to induce disease may differ between the biological endpoint in question.

Association Between Consecutive Ambient Air Pollution and Chronic Obstructive Pulmonary Disease Hospitalization: Time Series Study During 2015-2017 in Chengdu China

This paper investigates the association between consecutive ambient air pollution and Chronic Obstructive Pulmonary Disease (COPD) hospitalization in Chengdu China. The three-year (2015-2017) time series data for both ambient air pollutant concentrations and COPD hospitalizations in Chengdu are approved for the study. The big data statistic analysis shows that Air Quality Index (AQI) exceeded the lighted air polluted level in Chengdu region are mainly attributed to particulate matters (i.e., PM_2.5 and PM₁₀). The time series study for consecutive ambient air pollutant concentrations reveal that AQI, PM_2.5, and PM₁₀ are significantly positive correlated, especially when the number of consecutive polluted days is greater than nine days. The daily COPD hospitalizations for every 10 μg/m³ increase in PM_2.5 and PM₁₀ indicate that consecutive ambient air pollution can lead to an appearance of an elevation of COPD admissions, and also present that dynamic responses before and after the peak admission are different. Support Vector Regression (SVR) is then used to describe the dynamics of COPD hospitalizations to consecutive ambient air pollution. These findings will be further developed for region specific, hospital early notifications of COPD in responses to consecutive ambient air pollution.

Airborne PAHs inhibit gap junctional intercellular communication and activate MAPKs in human bronchial epithelial cell line

Inhalation exposures to polycyclic aromatic hydrocarbons (PAHs) have been associated with various adverse health effects, including chronic lung diseases and cancer. Using human bronchial epithelial cell line HBE1, we investigated the effects of structurally different PAHs on tissue homeostatic processes, namely gap junctional intercellular communication (GJIC) and MAPKs activity. Rapid (<1 h) and sustained (up to 24 h) inhibition of GJIC was induced by low/middle molecular weight (MW) PAHs, particularly by those with a bay- or bay-like region (1- and 9-methylanthracene, fluoranthene), but also by fluorene and pyrene. In contrast, linear low MW (anthracene, 2-methylanthracene) or higher MW (chrysene) PAHs did not affect GJIC. Fluoranthene, 1- and 9-methylanthracene induced strong and sustained activation of MAPK ERK1/2, whereas MAPK p38 was activated rather nonspecifically by all tested PAHs. Low/middle MW PAHs can disrupt tissue homeostasis in human airway epithelium via structure-dependent nongenotoxic mechanisms, which can contribute to their human health hazards.

The Preliminary Study on the Association Between PAHs and Air Pollutants and Microbiota Diversity

The purpose of this study was to investigate the association among polycyclic aromatic hydrocarbons (PAHs) exposure and air pollutants and the diversity of microbiota. Daily average concentrations of six common air pollutants were obtained from China National Environmental Monitoring Centre. The PAHs exposure levels were evaluated by external and internal exposure detection methods, including monitoring atmospheric PAHs and urinary hydroxyl-polycyclic aromatic hydrocarbon (OH-PAH) metabolite levels. We analyzed the diversity of environmental and commensal bacterial communities with 16S rRNA gene sequencing and performed functional enrichment with Phylogenetic Investigation of Communities by Reconstruction of Unobserved States (PICRUSt) and Kyoto Encyclopedia of Genes and Genomes (KEGG). Correlation analysis and logistic regression modeling were conducted to evaluate the relationship of PAHs levels with air pollutants and microbial diversity. Correlation analysis found that the concentrations of atmospheric PAHs were significantly positively correlated with those of PM₁₀, NO₂, and SO₂. There also was a positive correlation between the abundance of the genus Micrococcus (Actinobacteria) and high molecular weight PAHs, and Bacillus, such as genera and low molecular weight PAHs in the atmosphere. Logistic regression showed that the level of urinary 1-OHPyrene was associated with childhood asthma after sex and age adjustment. The level of urinary 1-OHPyrene was significantly positively correlated with that of PM_2.5 and PM₁₀. In addition, the level of 1-OHPyrene was positively correlated with oral Prevotella-7 abundance. Functional enrichment analysis demonstrated that PAHs exposure may disturb signaling pathways by the imbalance of commensal microbiota, such as purine metabolism, pyrimidine metabolites, lipid metabolism, and one carbon pool by folate, which may contribute to public health issues. Our results confirmed that atmospheric PAHs and urinary 1-OHPyrene were correlated with part of six common air pollutants and indicated that PAHs pollution may alter both environmental and commensal microbiota communities associated with health-related problems. The potential health and environmental impacts of PAHs should be further explored.

Genome-Wide Analysis Reveals Mucociliary Remodeling of the Nasal Airway Epithelium Induced by Urban PM2.5

Air pollution particulate matter <2.5 μm (PM2.5) exposure is associated with poor respiratory outcomes. Mechanisms underlying PM2.5-induced lung pathobiology are poorly understood but likely involve cellular and molecular changes to the airway epithelium. We extracted and chemically characterized the organic and water-soluble components of air pollution PM2.5 samples, then determined the whole transcriptome response of human nasal mucociliary airway epithelial cultures to a dose series of PM2.5 extracts. We found that PM2.5 organic extract (OE), but not water-soluble extract, elicited a potent, dose-dependent transcriptomic response from the mucociliary epithelium. Exposure to a moderate OE dose modified the expression of 424 genes, including activation of aryl hydrocarbon receptor signaling and an IL-1 inflammatory program. We generated an OE-response gene network defined by eight functional enrichment groups, which exhibited high connectivity through CYP1A1, IL1A, and IL1B. This OE exposure also robustly activated a mucus secretory expression program (>100 genes), which included transcriptional drivers of mucus metaplasia (SPDEF and FOXA3). Exposure to a higher OE dose modified the expression of 1,240 genes and further exacerbated expression responses observed at the moderate dose, including the mucus secretory program. Moreover, the higher OE dose significantly increased the MUC5AC/MUC5B gel-forming mucin expression ratio and strongly downregulated ciliated cell expression programs, including key ciliating cell transcription factors (e.g., FOXJ1 and MCIDAS). Chronic OE stimulation induced mucus metaplasia-like remodeling characterized by increases in MUC5AC+ secretory cells and MUC5AC mucus secretions. This epithelial remodeling may underlie poor respiratory outcomes associated with high PM2.5 exposure.

An update on immunologic mechanisms in the respiratory mucosa in response to air pollutants

Every day, we breathe in more than 10,000 L of air that contains a variety of air pollutants that can pose negative consequences to lung health. The respiratory mucosa formed by the airway epithelium is the first point of contact for air pollution in the lung, functioning as a mechanical and immunologic barrier. Under normal circumstances, airway epithelial cells connected by tight junctions secrete mucus, airway surface lining fluid, host defense peptides, and antioxidants and express innate immune pattern recognition receptors to respond to inhaled foreign substances and pathogens. Under conditions of air pollution exposure, the defenses of the airway epithelium are compromised by reductions in barrier function, impaired host defense to pathogens, and exaggerated inflammatory responses. Central to the mechanical and immunologic changes induced by air pollution are activation of redox-sensitive pathways and a role for antioxidants in normalizing these negative effects. Genetic variants in genes important in epithelial cell function and phenotype contribute to a diversity of responses to air pollution in the population at the individual and group levels and suggest a need for personalized approaches to attenuate the respiratory mucosal immune responses to air pollution.

Joint effect of polycyclic aromatic hydrocarbons and phthalates exposure on telomere length and lung function

Exposure to polycyclic aromatic hydrocarbons and phthalates are linked to lung function decline and altered relative telomere length (RTL) accompanying with oxidative stress and inflammatory events in human body. However, limited data are available about impacts of co-exposure of PAHs and phthalates on lung function and RTL. We conducted a pilot study with repeated measures during the winter of 2014 and summer of 2015 in Wuhan city, China. Participants took part in the measures of lung function, RTL, urinary monohydroxylated-PAHs (OH-PAHs) and phthalate metabolites over three consecutive days in each season. Linear mixed-effect (LME) models and Bayesian kernel machine regression (BKMR) were used to analyze the relations of OH-PAHs or phthalate metabolites with lung function or RTL. LME models showed the negative associations of 3-day average of hydroxyphenanthrene (2 + 3-, 4-OHPhe) or 1-hydroxypyrene with FEV1, 3-day average of 2 + 3-OHPhe with FVC. BKMR models revealed the negative relation of eight OH-PAHs with FEV1, FVC or RTL; nine phthalate metabolites may counteract an overall effect of eight OH-PAHs on FEV1, FVC or RTL. The findings indicated that urinary phthalate metabolites may counteract the negative association of urinary OH-PAHs on FEV1 or FVC, which may be partially linked to shorter RTL regarding biological aging.

PM2.5-Bound Polycyclic Aromatic Hydrocarbons: Sources and Health Risk during Non-Heating and Heating Periods (Tangshan, China)

Exposure to polycyclic aromatic hydrocarbons (PAHs) may lead to adverse health risks. To understand the potential sources and carcinogenic risks of PAHs in Tangshan, 40 PM_2.5 samples were collected for analysis of eighteen PM_2.5-bound PAHs during non-heating period and heating period. The results display a significant variation. The median concentration of ∑₁₈PAHs during the heating period (282 ng/m³) was higher than during the non-heating period (185 ng/m³). Especially, the median concentration of Benzopyrene (BaP) during the heating period (61.6 ng/m³) was 16.9-fold that during the non-heating period (3.64 ng/m³). It exceeded BaP annual average limit of China (1 ng/m³). Diagnostic ratios (DRs) and principal component analysis (PCA) both indicated that vehicle emissions and coal and biomass combustion were the dominant contributors of PAHs pollution in Tangshan. The incremental lifetime cancer risk (ILCR) of three age groups (children, teenagers, and adults) ranged from 2.56 × 10⁻⁶ to 5.26 × 10⁻⁵ during the entire sampling periods. The 95% risk values of adults exceeded 10⁻⁴ during the heating periods, indicating a potential health risk from PAHs.

A metabolomics study on effects of polyaromatic compounds in oil sand extracts on the respiratory, hepatic and nervous systems using three human cell lines

Polyaromatic compounds (PACs) are by-products of combustion and are the major pollutants from the oil and gas industry. However, the mechanism of PACs induced toxicity still remains elusive. The aim of this study was to elucidate the effects of a typical mixture of PACs found in oil sand extract (OSE) on the respiratory, hepatic and nervous systems in humans using in vitro cell culture models followed by non-targeted metabolomics analysis. OSE collected from Alberta, Canada was fractionated into PAC and alkane fractions, and their effects after 24 h exposure on the cell viability measured by MTT assay in three human cell lines (A549, HepG2, and SK-N-SH) were studied. The PAC fractions showed significant dose-dependent cytotoxicity. A549 cells showed the highest sensitivity to OSE extracts, followed by SK-N-SH and HepG2. In contrast, the alkane fractions showed no effects on cell viability. The three human cell lines were further exposed with the PACs at 10% and 20% lethal concentration for 24 h. Metabolomics analysis of the cell extracts indicated that PACs treatments showed different disruptions on possible metabolic pathways on the three cell lines. PACs altered the sex steroid hormone metabolism and regulated the levels of leukotrienes metabolites in all three cell types. The amino acids L-cysteine, L-glutamine, L-tyrosine that are known to cause respiratory effects were significantly up-regulated in A549 cells. The PACs treated HepG2 cells showed down-regulation in metabolites responsible for the inflammatory mediation. Treatment of the differentiated SK-N-SH cells showed up-regulated metabolites involved with butanoate, fatty acid, and pyrimidine metabolism. Leukotriene metabolites were found to be significantly increased in all PACs treated cells. In conclusion, our results showed that PACs in OSE can alter the metabolism of the human lung, liver and neuronal cells and may induce toxicity in multiple target organs.

Socio-Economic and Environmental Factors Related to Spatial Differences in Human Non-Tuberculous Mycobacterial Diseases in the Czech Republic

Non-tuberculous mycobacteria (NTM) are ubiquitous environmental bacteria that can induce pulmonary and non-pulmonary diseases in susceptible persons. It is reported that the prevalence of NTM diseases is increasing in developed countries, but this differs by regions and countries. NTM species distribution and the rate of diseases caused by NTM vary widely in the historical territories of Moravia and Silesia (Czech Republic). This epidemiologic study of NTM diseases covers the period 2012–2018, reviews isolates obtained from patients with clinical disease and investigates correlations with related socio-economic and environmental factors. Individual NTM patients were included only once during the studied period and results were presented as incidence rate per year. The most frequently isolated NTM meeting the microbiological and clinical criteria in the study were the Mycobacterium avium-intracellulare complex, followed by Mycobacterium kansasii and Mycobacteriumxenopi. A previously described endemic incidence of M.kansasii in the Karviná district and M.xenopi in the Ostrava district was also observed in this study. The incidence of NTM patients in the whole studied territory was 1.10/100,000 inhabitants (1.33/100,000 in men and 0.88/100,000 in women). The annual incidence of lymphadenitis in children (≤5 years of age) was 2.35/100,000 of the population of children during the 7 year period but increased in the year 2018 to 5.95/100,000. The rate of human tuberculosis in the studied area was 1.97/100,000 inhabitants. The incidence of NTM pulmonary diseases correlated with a lower socio-economic status (r = 0.63) and a higher concentration of benzo[a]pyrene pollution in the air (r = 0.64).

Blood-brain barrier function, cell viability, and gene expression of tight junction-associated proteins in the mouse are disrupted by crude oil, benzo[a]pyrene, and the dispersant COREXIT

Exposure to crude oil, its components, and oil dispersants during a major crude oil spill, such as the Deepwater Horizon Oil Spill, can elicit behavioral changes in animals and humans. However, the underlying mechanisms by which oil spill-related compounds alters behavior remains largely unknown. A major cause of behavioral changes generally is dysfunction of the blood-brain barrier (BBB). We investigated the impact of a crude oil high energy water accommodated fraction (HEWAF), benzo[a] pyrene (BaP; a major component of crude oil), and the oil dispersant COREXIT, on BBB function. BBB function was assessed by measuring transendothelial electrical resistance (TEER) of mouse brain microvascular endothelial cells (BMECs). Within 3 h after treatment, TEER was significantly reduced by exposure to high concentrations of all test compounds. TEER remained reduced in response to COREXIT after 48 h, but this effect waned in BMECs treated with HEWAF and BaP, with low-mid range concentrations inducing increased TEER compared to vehicle controls. At 48 h of treatment, BMEC viability was significantly reduced in response to 2% HEWAF, but was increased in response to BaP (25 and 50 μM). BMEC viability was increased with 80 ppm COREXIT, but was reduced with 160 ppm. Gene expression of tight junction-associated proteins (claudin-5 and tight junction protein-1), and cell adhesion receptor (vascular cell adhesion molecule-1) was reduced in response to HEWAF and COREXIT, but not BaP. Taken together, these data suggest that oil spill-related compounds markedly affect BBB function, and that these changes may underlie the observed behavioral changes due to crude oil exposure.

Formation of environmentally persistent free radicals during the transformation of anthracene in different soils: Roles of soil characteristics and ambient conditions

Transformation of PAHs, i.e., anthracene, and production of environmentally persistent free radicals (EPFRs) on seven types of representative soils were investigated, focusing on the influences of soil characteristics and ambient conditions on these reactions. The transformation rate of anthracene exhibits the order of red earth > yellow earth > latosol ∼ fluvo-aquic soil > brown earth > chernozem > calcic brown soil, which is positively correlated with Fe content in soils. Afterwards, batch reactions on pure representatives of soil minerals, including Fe₂O₃, Fe₃O₄, FeOOH, and MnO₂, demonstrate that anthracene is prone to mineral-promoted transformation. The presence of higher amount of organic carbon lower the transformation rate of anthracene, whereas the formed EPFRs can be stabilized for a longer time. Subsequent experiments associated with the influences of environmental conditions on mineral-promoted reactions suggest that both anthracene transformation and EPFRs generation readily occur under dry condition. Light irradiation not only promotes the formation of EPFRs, but also greatly accelerates the decay of EPFRs and the 1/e lifetime decreases from 5 to 20 d in dark to approximately 1 d. Meanwhile, the anoxic condition is favorable for the persistence of EPFRs. The obtained results suggested the potential environmental risks association with EPFRs in PAHs-contaminated soils.

Pro-inflammatory effects of extracted urban fine particulate matter on human bronchial epithelial cells BEAS-2B

Atmospheric particulate matter (PM) constitutes the major part of urban air pollution and is a heterogeneous mixture of solid and liquid particles of different origin, size, and chemistry. Human exposure to PM in urban areas poses considerable and significant adverse effects on the respiratory system and human health in general. Major contributors to PM content are combustion-related sources such as diesel vehicles, household, and industrial heating. PM is composed of thousands of different high molecular weight organic compounds, including poly-aromatic hydrocarbons (PAHs). The aim of this study was to clarify the cytotoxic effects of the extract of actual urban PM1 with high benzo[a]pyrene (BaP) content collected in Eastern European mid-sized city during winter heating season on human bronchial epithelial cells (BEAS-2B). Decreased cell viability, alteration of cell layer integrity, increased apoptosis, and oxidative stress were observed during the 3-day exposure to the PM extract. In addition, following PM exposure pro-inflammatory cytokine expression was upregulated at gene and protein levels. Morphology and motility changes, i.e., decreased cells' ability to cover scratch area, were also documented. We report here that the extract of urban PM1 may induce bronchial epithelium changes and render it pro-inflammatory and compromised within 3 days.

Transgenic up-regulation of Claudin-6 decreases fine diesel particulate matter (DPM)-induced pulmonary inflammation

Claudin-6 (Cldn6) is a tetraspanin transmembrane protein that contributes to tight junctional complexes and has been implicated in the maintenance of lung epithelial barriers. In the present study, we tested the hypothesis that genetic up-regulation of Cldn-6 influences inflammation in mice exposed to short-term environmental diesel particulate matter (DPM). Mice were subjected to ten exposures of nebulized DPM (PM2.5) over a period of 20 days via a nose-only inhalation system (Scireq, Montreal, Canada). Using real-time RT-PCR, we discovered that the Cldn6 gene was up-regulated in control mice exposed to DPM and in lung-specific transgenic mice that up-regulate Cldn-6 (Cldn-6 TG). Interestingly, DPM did not further enhance Cldn-6 expression in Cldn-6 TG mice. DPM caused increased cell diapedesis into bronchoalveolar lavage fluid (BALF) from control mice; however, Cldn-6 TG mice had less total cells and PMNs in BALF following DPM exposure. Because Cldn-6 TG mice had diminished cell diapedesis, other inflammatory intermediates were screened to characterize the impact of increased Cldn-6 on inflammatory signaling. Cytokines that mediate inflammatory responses including TNF-α and IL-1β were differentially regulated in Cldn6 TG mice and controls following DPM exposure. These results demonstrate that epithelial barriers organized by Cldn-6 mediate, at least in part, diesel-induced inflammation. Further work may show that Cldn-6 is a key target in understanding pulmonary epithelial gateways exacerbated by environmental pollution.

Fluorescence-linked immunosorbent assay for detection of phenanthrene and its homolog

A competitive fluorescence-linked immunosorbent assay (FLISA) was developed using rhodamine B isothiocyanate (RBITC) as the model fluorescent dye conjugate monoclonal antibody (McAb) for detection of Phe and its homolog (acenaphthene, fluorene, fluoranthene, pyrene and indeno [1,2,3-cd] pyrene) in water samples. The detection range of the assay for Phe was from 2.10 to 91.95 ng/mL. The limit of detection was 1.05 ng/mL, which was approximately 2-fold lower than that of traditional ic-ELISA. Compared with traditional ic-ELISA, more than 70 min was saved because of only one immunoreaction step was needed to accomplish the assay. The average recoveries of Phe and its homolog from domestic water, contaminated water and natural water were 100.7%, 100.8% and 101.2% respectively. The accuracy and precision of the developed FLISA were validated with GC-MS/MS. There were good correlation between the two methods from tap water, contaminated water and river water samples were 0.9994, 0.9935 and 0.9967, respectively. The results suggested that the proposed FLISA could be a potential alternative format for rapid, sensitive, and quantitative detection of Phe and its homolog in environmental water.

Industrial PM2.5 cause pulmonary adverse effect through RhoA/ROCK pathway

According to the Chinese Ministry of Health, industrial pollution-induced health impacts have been the leading cause of death in China. While industrial fine particulate matter (PM_2.5) is associated with adverse health effects, the major action mechanisms of different compositions of PM_2.5 are currently unclear. In this study, we treated normal human lung epithelial BEAS-2B cells with industrial organic and water-soluble PM_2.5 extracts under daily alveolar deposition dose to elucidate the molecular mechanisms underlying adverse pulmonary effects induced by PM_2.5, including oxidative damage, inflammatory response, lung epithelial barrier dysfunction, and the recruitment of macrophages. We found that water-soluble PM_2.5 extracts caused more severe cytotoxic effects on BEAS-2B cells compared with that of organic extracts. Both organic and water-soluble PM_2.5 extracts induced activation of the RhoA/ROCK pathway. Inflammatory response, epithelial barrier dysfunction, and the activation of NF-кB caused by both PM_2.5 extracts were attenuated by ROCK inhibitor Y-27632. This indicated that both PM_2.5 extracts could cause damage to epithelial cells through RhoA/ROCK-dependent NF-кB activation. Furthermore, the upregulation of macrophage adhesion induced by both PM_2.5 extracts was also attenuated by Y-27632 in a co-culture model of macrophages and the epithelial cells. Therefore, our results support that industrial PM_2.5 extracts-induced activation of the RhoA/ROCK-dependent NF-кB pathway induces pulmonary adverse effect. Thus, pharmacological inhibition of ROCK activation might have therapeutic potential in preventing lung disease associated with PM_2.5.