Characteristics and oxidative stress on rats and traffic policemen of ambient fine particulate matter from Shenyang

Early biological effects in outdoor workers exposed to urban air pollution: A systematic review

Urban outdoor workers (OWs), identified as professionals spending most of their working shifts in an urban environment, are exposed for at least 8 h/day to traffic air pollution, leading to potential health risks. This paper reports the results of a systematic review aimed at identifying the potential health outcomes of exposure to air pollutants for OWs, focusing mainly on police officers, drivers and street vendors. Health outcomes were analysed in terms of early biological effects quantified with specific measured indicators. The main inclusion criterion was the assessment of at least one early biological effect (genetic and epigenetic damage/alterations, inflammation or oxidative stress indicators, or hormonal imbalance) in a population of OWs exposed to urban air pollution. By applying the PRISMA workflow, 82 papers were included in this study. The results showed that the measured pollutant concentrations were significantly below the current occupational limit values, while exceeds the indications of WHO for urban air pollution. This exposure led to significant alterations of biological markers in OWs with respect to non-exposed subjects. In particular, OWs presented an increased frequency of micronuclei and DNA adducts as the main DNA alterations, while police officers (a category of highly exposed OWs) showed hormonal alterations affecting mainly the hypothalamic-pituitary-gonadal axis. Concerning oxidative stress and inflammation, all the analysed matrices (i.e. blood, sputum, urine and lachrymal fluids) showed increased indices for OWs respect to non-exposed groups. Therefore, the evaluation of effect biomarkers to detect early alterations provides crucial information for supporting the occupational risk management of OWs and, at broader level, allows for an insight of the early-stage health outcomes due to urban air pollution.

Exploring the adverse effect of fine particulate matter (PM2.5) on wildland firefighters' pulmonary function and DNA damage

Chiang Mai encounters severe pollution during the wildfire season. Wildland firefighters encounter various hazards while engaged in fire suppression operations, which encompass significant exposure to elevated concentrations of air pollutants resulting from combustion, especially particulate matter. The adverse effects of wildfire smoke on respiratory health are a significant concern. The objective of this study was to examine the potential adverse effects of PM2.5 exposure on the respiratory function and DNA damage of wildland firefighters. This prospective cohort study conducted in Chiang Mai from January to May 2022 planned to evaluate the health status of wildland firefighters during the pre-peak, peak, and post-peak ambient air pollution seasons. The measurement of PM2.5 was done at every forest fire station, as well as utilizing data from the Pollution Control Department. Participants received general health examinations, spirometry evaluations, and blood tests for DNA damage analysis. Pair t-tests and multiple regression models were used to examine the connection between pulmonary function parameters (FVC, FEV1) and PM2.5 concentration, with a significance level of P < 0.05. Thirty-three peak-season and twenty-one post-peak-season participants were enrolled. Four pre-peak-season wildland firefighters had FVC and FEV1 declines of > 15%. Multiple regression analysis showed a negative association between PM2.5 exposure and FVC% predicted (- 2.81%, 95% CI - 5.27 to - 0.34%, P = 0.027) and a marginally significant negative correlation with FVC (- 114.38 ml, 95% CI - 230.36 to 1.59 ml, P = 0.053). The remaining pulmonary measures showed a statistically insignificant decline. There were no significant changes in DNA damage detected. Wildland firefighters suffered a significant decline in pulmonary function associated with PM2.5 exposure. Spirometry is crucial for monitoring and promptly identifying respiratory issues that occur during wildfire seasons. Further research is recommended to explore DNA damage alterations and their potential association with PM2.5.

Oxidative stress indices induced by industrial and urban PM2.5-bound metals in A549 cells

The detrimental effects of atmospheric fine particulate matter (PM_2.5) on human health are of major global concern. PM_2.5-bound metals are toxic compounds that contribute to cellular damage. To investigate the toxic effects of water-soluble metals on human lung epithelial cells and their bioaccessibility to lung fluid, PM_2.5 samples were collected from both urban and industrial areas in the metropolitan city of Tabriz, Iran. Oxidative stress indices, including proline content, total antioxidant capacity (TAC), cytotoxicity, and DNA damage levels of water-soluble components of PM_2.5, were evaluated. Furthermore, an in vitro test was conducted to assess the bioaccessibility of various PM_2.5-bound metals to the respiratory system using simulated lung fluid. PM_2.5 average concentrations in urban and industrial areas were 83.11 and 97.71 μg/m³, respectively. The cytotoxicity effects of PM_2.5 water-soluble constituents from urban areas were significantly higher than in industrial areas and the IC₅₀ was found to be 96.76 ± 3.34 and 201.31 ± 5.96 μg/mL for urban and industrial PM_2.5 samples, respectively. In addition, higher PM_2.5 concentrations increased the proline content in a concentration-dependent manner in A549 cells, which plays a protective role against oxidative stress and prevents PM_2.5-induced DNA damage. Also, the partial least squares regression revealed that Be, Cd, Co, Ni, and Cr, were significantly correlated with DNA damage and proline accumulation, which caused cell damage through oxidative stress. The results of this study showed that PM_2.5-bound metals in highly polluted metropolitan city caused substantial changes in the cellular proline content, DNA damage levels and cytotoxicity in human lung A549 cells.

Exposure to ambient particulate matter and hyperuricemia: An eight-year prospective cohort study on male traffic officers in China

BACKGROUND AND OBJECTIVES

Studies on the effects of airborne particulates of diameter ≤ 1 µm (PM₁), airborne particulates of diameter ≤ 2.5 µm (PM_2.5) and airborne particulates of diameter ranges from 1 to 2.5 µm (PM_1-2.5) on incidence of hyperuricemia are limited. We aimed to investigate the associations between PM₁, PM_2.5, and PM_1-2.5 and hyperuricemia among male traffic officers.

METHODS

We conducted a prospective cohort study of 1460 traffic officers without hyperuricemia in Guangzhou, China from 2009 to 2016. Exposures of PM₁ and PM_2.5 were estimated with a spatiotemporal model. PM_1-2.5 concentrations were calculated by subtracting PM₁ from PM_2.5 concentrations. Cox's proportional hazards regressions models were used to examine the association between PM₁, PM_2.5, and PM_1-2.5 and hyperuricemia, adjusted for potential confounders. Associations between PM₁, PM_2.5, and PM_1-2.5 and serum uric acid (SUA) levels were evaluated with multiple linear regression models.

RESULTS

Hazard ratios (HRs) and 95% confidence intervals (CIs) of hyperuricemia associated with 10 μg/m³ increment in PM₁, PM_2.5, and PM_1-2.5 were 1.67 (95% CI:1.30-2.36), 1.49 (95% CI: 1.27-1.75), and 2.18 (95% CI: 1.58-3.02), respectively. The SUA concentrations increased by 12.23 μmol/L (95% CI: 5.91-18.56), 6.93 μmol/L (95% CI: 3.02-10.84), and 8.72 μmol/L (95% CI: 0.76-16.68) per 10 μg/m³ increase in PM₁, PM_2.5, and PM_1-2.5, respectively. Stratified analyses indicated the positive associations of PM_2.5 and PM_1-2.5 with SUA levels were stronger in non-smokers, and PM₁, PM_2.5, and PM_1-2.5 with SUA levels were stronger in non-drinkers.

CONCLUSION

Long-term PM₁, PM_2.5, and PM_1-2.5 exposures may increase the risk of hyperuricemia and elevate SUA levels among male traffic officers, especially in non-smokers and non-drinkers.

A comparison of fine particulate matter (PM2.5) in vivo exposure studies incorporating chemical analysis

The complex, variable mixtures present in fine particulate matter (PM_2.5) have been well established, and associations between chemical constituents and human health are expanding. In the past decade, there has been an increase in PM_2.5 toxicology studies that include chemical analysis of samples. This investigation is a crucial component for identifying the causal constituents for observed adverse health effects following exposure to PM_2.5. In this review, investigations of PM_2.5 that used both in vivo models were explored and chemical analysis with a focus on respiratory, cardiovascular, central nervous system, reproductive, and developmental toxicity was examined to determine if chemical constituents were considered in the interpretation of the toxicity findings. Comparisons between model systems, PM_2.5 characteristics, endpoints, and results were made. A vast majority of studies observed adverse effects in vivo following exposure to PM_2.5. While limited, investigations that explored connections between chemical components and measured endpoints noted significant associations between biological measurements and a variety of PM_2.5 constituents including elements, ions, and organic/elemental carbon, indicating the need for such analysis. Current limitations in available data, including relatively scarce statistical comparisons between collected toxicity and chemical datasets, are provided. Future progress in this field in combination with epidemiologic research examining chemical composition may support regulatory standards of PM_2.5 to protect human health.

Short-term PM exposure and social stress cause pulmonary and cardiac dysfunction

Ambient particulate matter (PM) exposure increases risk for cardiopulmonary health problems which may be exacerbated in a stressful environment. Co-exposure to PM and stress characterizes the experience of many deployed military personnel and first responders but has not been thoroughly investigated. This is especially relevant to military personnel who have been exposed to high PM levels in conjunction with stressful military conflict situations. To understand the mechanisms and time-course of the health consequences following burn pit exposure, we exposed mice to moderate levels of ambient PM less than 2.5 μM in diameter (PM_2.5) alone or in combination with psychological stress. We found male mice exposed to PM_2.5 alone or in combination with stress had significantly reduced pulmonary function when subjected to methacholine, indicating increased airway hyperreactivity. These mice experienced increased goblet cell hyperplasia in their lungs, with no change in alveolar density. Mice exposed to PM_2.5 and/or stress also exhibited reduced cardiac contractility, right ventricular (RV) output, and changes in RV capillary density and cardiac inflammatory markers. Taken together, these data indicate that short-term exposure to PM_2.5 with or without stress causes a clear reduction in pulmonary and cardiac function. We believe that this model is well-suited for the study of military and other occupational exposures, and future work will identify potential mechanisms, including the inflammatory progression of these co-exposures.

PM2.5 deregulated microRNA and inflammatory microenvironment in lung injury

PM2.5 negatively affects human health, particularly lung injury. However, the role of PM2.5-regulated miRNAs in lung injury remains unknown. MiRNA array results showed mmu-miR-467c-5p regulated Prdx6 expression to adapt to lung injury condition, and deregulated miRNAs regulated macrophages to build a localized inflammatory microenvironment. In addition, miRNAs were transferred into adjacent alveolar epithelial cells, regulating the expressions of cell injury signaling pathway-targeted genes, and accelerating local lung tissue injury. NO and RAGE were increased in the coculture supernatant, and SPD was decreased. PM2.5 exposure induced local lung injury, promoted inflammation in local lung tissues, increased capillary permeability in the lung tissue, and rearranged the local lung tissue structure. We also confirmed in AECOPD patients TNF-α and IL-1β levels are obviously higher than healthy person. These findings provide new mechanistic insights regarding PM2.5 and targeted miRNAs in the inflammatory microenvironment, which increases our knowledge of PM2.5-lung injury interactions.

Biomarkers for the adverse effects on respiratory system health associated with atmospheric particulate matter exposure

Large amounts of epidemiological evidence have confirmed the atmospheric particulate matter (PM_2.5) exposure was positively correlated with the morbidity and mortality of respiratory diseases. Nevertheless, its pathogenesis remains incompletely understood, probably resulting from the activation of oxidative stress, inflammation, altered genetic and epigenetic modifications in the lung upon PM_2.5 exposure. Currently, biomarker investigations have been widely used in epidemiological and toxicological studies, which may help in understanding the biologic mechanisms underlying PM_2.5-elicited adverse health outcomes. Here, the emerging biomarkers to indicate PM_2.5-respiratory system interactions were summarized, primarily related to oxidative stress (ROS, MDA, GSH, etc.), inflammation (Interleukins, FE_NO, CC16, etc.), DNA damage (8-OHdG, γH2AX, OGG1) and also epigenetic modulation (DNA methylation, histone modification, microRNAs). The identified biomarkers shed light on PM_2.5-elicited inflammation, fibrogenesis and carcinogenesis, thus may favor more precise interventions in public health. It is worth noting that some inconsistent findings may possibly relate to the inter-study differentials in the airborne PM_2.5 sample, exposure mode and targeted subjects, as well as methodological issues. Further research, particularly by -omics technique to identify novel, specific biomarkers, is warranted to illuminate the causal relationship between PM_2.5 pollution and deleterious lung outcomes.

Pulmonary health effects of wintertime particulate matter from California and China following repeated exposure and cessation

Epidemiological studies show strong associations between fine particulate matter (PM2.5) air pollution and adverse pulmonary effects. In the present study, wintertime PM2.5 samples were collected from three geographically similar regions-Sacramento, California, USA; Jinan, Shandong, China; and Taiyuan, Shanxi, China-and extracted to form PMCA, PMSD, and PMSX, respectively, for comparison in a BALB/c mouse model. Each of four groups was oropharyngeally administered Milli-Q water vehicle control (50 μL) or one type of PM extract (20 μg/50 μL) five times over two weeks. Mice were necropsied on post-exposure days 1, 2, and 4 and examined using bronchoalveolar lavage (BAL), histopathology, and assessments of cytokine/chemokine mRNA and protein expression. Chemical analysis demonstrated all three extracts contained black carbon, but PMSX contained more sulfates and polycyclic aromatic hydrocarbons (PAHs) associated with significantly greater neutrophil numbers and greater alveolar/bronchiolar inflammation on post-exposure days 1 and 4. On day 4, PMSX-exposed mice also exhibited significant increases in interleukin-1 beta, tumor necrosis factor-alpha, and chemokine C-X-C motif ligands-3 and -5 mRNA, and monocyte chemoattractant protein-1 protein. These combined findings suggest greater sulfate and PAH content contributed to a more intense and progressive inflammatory response with repeated PMSX compared to PMCA or PMSD exposure.

Amelioration of Ambient Particulate Matter (PM2.5)-Induced Lung Injury in Rats by Aerobic Exercise Training

Ambient particulate matter (PM_2.5), as an inflammation-inducing factor, increases the prevalence of lung injury. The aim of this study was to examine the protective effect and mechanism of aerobic exercise on PM_2.5 exposure-induced lung injury. Forty Wistar rats were randomly divided into four groups: sedentary+PM_2.5 exposure, exercise+PM_2.5 exposure, sedentary, and exercise groups. All rats in the exercise-related groups underwent 8-week aerobic interval treadmill training (5daysweek⁻¹, 1hday⁻¹). PM-exposed rats were exposed to ambient PM_2.5 (6h day⁻¹) for 3weeks after the 8-week exercise intervention. Then, ventilation function, histopathological changes, and inflammation responses of pulmonary tissue were examined. Results showed that PM_2.5 exposure induced lung injury as manifested by decreased pulmonary function, abnormal histopathological changes, and increased pro-inflammatory cytokine levels (tumor necrosis factor-α and Interleukin-1α). Aerobic exercise alleviated the airway obstruction, reduced respiratory muscle strength, bronchial mucosal exfoliation, ultrastructure damage, and inflammatory responses induced by PM_2.5 in exercise-related groups. The benefits of exercise were related with the downregulation of p38-mitogen-activated protein kinase (MAPK), and the subsequent inhibition of the pathways of the cyclooxygenase 2 (COX-2) product, prostaglandin E₂ (PGE₂). Thus, pre-exercise training may be an effective way to protect against PM_2.5-induced lung inflammatory injury in rats.

Isosinensetin alleviates the injury of human bronchial epithelial cells induced by PM2.5

Flavonoids which are extracted from citrus peel and pulp have been reported to have multiple beneficial effects on human health. Isosinensetin (ISO) is a type of flavonoid compound, which has several protective effects including anticancer, antioxidant, antiviral, anti-inflammatory and bacteriostatic. However, the molecular mechanism of its antioxidant and anti-inflammatory effects remain unclear. The present study aimed to investigate the intervention effect and possible mechanism of ISO on human bronchial epithelial cells injured by fine particular matter ≤2.5 µm in diameter (PM_2.5). In the present study, the cell viability was detected by Cell Counting Kit-8 method. The levels of pro-inflammatory cytokines were analyzed by ELISA. The level of reactive oxygen species (ROS) was detected by fluorescence probe. The expression levels of proliferating cell nuclear antigen (PCNA), nuclear factor erythroid 2-related factor 2 (Nrf2) and nuclear factor кΒ (NF-кB) proteins were detected by western blotting. The results revealed that ISO evidently increased the viability of 16-HBE cells and sharply decreased the levels of pro-inflammatory factors in cell culture supernatant. ISO significantly inhibited ROS release caused by PM_2.5. Moreover, the expression levels of PCNA, Nrf2 and NF-кB proteins were downregulated after ISO incubation. These results indicated that ISO alleviated 16-HBE-cell injury by PM_2.5 through the ROS-Nrf2/NF-кB signaling pathway.

Interactions of particulate matter and pulmonary surfactant: Implications for human health

Particulate matter (PM), which is the primary contributor to air pollution, has become a pervasive global health threat. When PM enters into a respiratory tract, the first body tissues to be directly exposed are the cells of respiratory tissues and pulmonary surfactant. Pulmonary surfactant is a pivotal component to modulate surface tension of alveoli during respiration. Many studies have proved that PM would interact with pulmonary surfactant to affect the alveolar activity, and meanwhile, pulmonary surfactant would be adsorbed to the surface of PM to change the toxic effect of PM. This review focuses on recent studies of the interactions between micro/nanoparticles (synthesized and environmental particles) and pulmonary surfactant (natural surfactant and its models), as well as the health effects caused by PM through a few significant aspects, such as surface properties of PM, including size, surface charge, hydrophobicity, shape, chemical nature, etc. Moreover, in vitro and in vivo studies have shown that PM leads to oxidative stress, inflammatory response, fibrosis, and cancerization in living bodies. By providing a comprehensive picture of PM-surfactant interaction, this review will benefit both researchers for further studies and policy-makers for setting up more appropriate regulations to reduce the adverse effects of PM on public health.

Effects of PM2.5 and gases exposure during prenatal and early-life on autism-like phenotypes in male rat offspring

BACKGROUND

Epidemiological studies have reported associations between elevated air pollution and autism spectrum disorders (ASD). However, we hypothesized that exposure to air pollution that mimics real world scenarios, is a potential contributor to ASD. The exact etiology and molecular mechanisms underlying ASD are not well understood. Thus, we assessed whether changes in OXTR levels may be part of the mechanism linking PM_2.5/gaseous pollutant exposure and ASD. The current in-vivo study investigated the effect of exposure to fine particulate matter (PM_2.5) and gaseous pollutants on ASD using behavioral and molecular experiments. Four exposure groups of Wistar rats were included in this study: 1) particulate matter and gaseous pollutants exposed (PGE), 2) gaseous pollutants only exposed (GE), 3) autism-like model (ALM) with VPA induction, and 4) clean air exposed (CAE) as the control. Pregnant dams and male pups were exposed to air pollutants from embryonic day (E0) to postnatal day (PND21).

RESULTS

The average ± SD concentrations of air pollutants were: PM_2.5: 43.8 ± 21.1 μg/m³, CO: 13.5 ± 2.5 ppm, NO₂: 0.341 ± 0.100 ppm, SO₂: 0.275 ± 0.07 ppm, and O₃: 0.135 ± 0.01 ppm. The OXTR protein level, catalase activity (CAT), and GSH concentrations in the ALM, PGE, and GE rats were lower than those in control group (CAE). However, the decrements in the GE rats were smaller than other groups. Also in behavioral assessments, the ALM, PGE, and GE rats demonstrated a repetitive /restricted behavior and poor social interaction, but the GE rats had weaker responses compared to other groups of rats. The PGE and GE rats showed similar trends in these tests compared to the VPA rats.

CONCLUSIONS

This study suggested that exposure to ambient air pollution contributed to ASD and that OXTR protein may serve as part of the mechanism linking them.

Biomarkers of exposure, effect, and susceptibility in occupational exposure to traffic-related air pollution: A review

There is a well-recognized association between environmental air pollution exposure and several human diseases. However, the relationship between diseases related to occupational air pollution exposure on roads and high levels of traffic-related air pollutants (TRAPs) is less substantiated. Biomarkers are essential tools in environmental and occupational toxicology, and studies on new biomarkers are increasingly relevant due to the need to determine early biomarkers to be assessed in exposure conditions. This review aimed to investigate the main advances in the biomonitoring of subjects occupationally exposed to air pollution, as well as to summarize the biomarkers of exposure, effect, and susceptibility. Furthermore, we discuss how biomarkers could be used to complement the current application of methods used to assess occupational exposures to xenobiotics present in air pollution. The databases used in the preparation of this review were PubMed, Scopus, and Science Direct. Considering the significant deleterious effects on health associated with chronic occupational exposure to xenobiotics, this topic deserves attention. As it is difficult to avoid occupational exposure to TRAPs, biomonitoring should be applied as a strategy to reduce the toxic effects of workplace exposure.

Variation of airborne DNA mass ratio and fungal diversity in fine particles with day-night difference during an entire winter haze evolution process of Central China

Airborne fungi are a primary component of bioaerosols and proved to impact human health and climatic change. Deoxyribonucleic acid (DNA) is the essential component of most living organisms with relatively stable physicochemical properties. Little is known about day-night and pollution-episode differences of DNA mass ratio and fungal community in fine particles (PM_2.5) during serious winter haze events in China. Here we collected twenty-nine PM_2.5 samples every day and night during an entire winter haze evolution process in a megacity of Central China, Wuhan. DNA extraction and high-throughput sequencing methods were adopted to analyze fungal community. Results showed that mass ratio of DNA in PM_2.5 (R_D/P %) changed with pollution process and showed significant negative correlations with PM_2.5 concentration (r = -0.72, P < 0.05) and temperature (r = -0.74, P < 0.05). R_D/P became lower (4.40 × 10^-4%) after haze episodes than before (7.16 × 10^-4%). R_D/P of night-samples (1.98 × 10^-4-4.97 × 10^-4%) were all lower than those for day-samples (3.05 × 10^-4-9.99 × 10^-4%) for the same period. The fungal species richness became much lower (76 operational taxonomic units (OTUs)) after haze episodes than before (198 OTUs). The species richness of night-samples (119-537 OTUs) were all higher than those of day-samples (71-198 OTUs) for the same period. The OTUs specially owned by night-samples were also more than those by day-samples. Fungal community diversity showed random variations. The fungal community composition of each sample was classified from phylum to genus level. Pathogenic fungi accounted for 8.60% of the entire fungal community. The significantly enriched fungal taxa in the night-sample group (29 taxa) were also much more than that in the day-sample group (9 taxa), which could explain the higher species richness of airborne fungi community in the night during the haze evolution episodes. These findings may serve as an important reference or inspiration to other aerosol studies focusing on human health and behavior of aerosols in the atmosphere.

Exposure to atmospheric pollutants is associated with alterations of gut microbiota in spontaneously hypertensive rats

Atmospheric particulate matter with a diameter <2.5 µm (PM2.5) and pollution are worldwide environmental problems and may have negative effects on cardiovascular disease through the lung and gut. The dynamics of intestinal microflora in response to particulate pollutants is unclear. The present study investigated changes in the gut microbiota related to pollutant exposure using spontaneously hypertensive rats (SHR). DNA was extracted from fecal samples. Amplicon Generation and the quality control of PCR products were performed. PCR products was sequenced on an Illumina HiSeq 2500 platform. Data analysis included: operational taxonomic unit (OTU) clustering and species annotation, alpha diversity, beta diversity, principal coordinates analysis (PCoA), and the use of PICRUSt bioinformatics software. The microbial diversity of the SHR rats was inversely associated with exposure to pollutants. In terms of relative abundance, 24 bacterial genera and 2 genera in particular (Actinobacillus and Fusobacterium) significantly declined, and one genus (Treponema) increased. Moreover, pollutant exposure was associated with the accumulation of genes from the gut microbiota that are implicated in cardiovascular diseases. From the long-term exposure experiment, rats appeared to respond to pollutant injury. In conclusion, these results suggest that the effects of atmospheric pollutants on organisms are not limited to the respiratory tract, but also include the gastrointestinal tract. Pollutants are likely to influence the intestinal microbiota and promote the progression of cardiovascular disease.

Determination of endogenous substance change in PM2.5-induced rat plasma and lung samples by UPLC-MS/MS method to identify potential markers for lung impairment

Exposure to fine particulate matter (PM_2.5) could induce lung impairment aggravation. Moreover, endogenous substances are known to play a significant role in lung impairment. Therefore, the research objectives was to investigate the influence of PM_2.5-induced lung impairment on the levels of the eight endogenous substances, γ-aminobutyric acid (GABA), acetylcholine (ACh), glutamate (Glu), serotonin (5-HT), 5-hydroxyindole-3-acetic acid (5-HIAA), noradrenaline (NE), dopamine (DA), and 3, 4-dihydroxyphenylacetic acid (DOPAC). A sensitive UPLC-MS/MS method for the simultaneous determination of these endogenous substances in rat plasma and lung tissues was developed. The validated method was successfully applied for comparing profiles of analytes in rat plasma and lung tissues. The results indicated that five endogenous substances, namely, GABA, Ach, Glu, DA, and DOPAC, had a significant change in the rats with PM_2.5-induced lung impairment.

PM2.5 induces cell cycle arrest through regulating mTOR/P70S6K1 signaling pathway

Fine particulate matter (PM2.5) pollution has become a serious problem in China. This study aims to elucidate the toxicity mechanism of PM2.5. Protein levels were detected by western blotting and RT-qPCR, and cell cycle was detected by flow cytometry. The results showed that exposure to PM2.5 induces cell cycle arrest and downregulation of the expression of cyclin D1 protein. Moreover, the protein expression of thymidylate synthase (TS) enzyme was found to be downregulated and the mRNA expression of TS was upregulated after PM2.5 exposure. Knockout of TS gene promoted cell cycle arrest and downregulation of the expression of cyclin D1 protein after PM2.5 exposure. Our data further revealed that PM2.5 exposure downregulates the expression of TS and cyclin D1 partially through the downregulation of the mammalian target of rapamycin (mTOR)/P70S6K1 signaling pathway. Thus, these findings indicate that PM2.5-induced cell cycle arrest might be due to the downregulation of mTOR/P70S6K1 signaling pathway, and thus inhibits the expression of TS protein.

Fine particulate matter alters the microecology of the murine respiratory tract

Fine particulate matter is a global challenge to human health. We investigated the effects and potential mechanisms of fine particulate matter on respiratory tract microecology in a lung injury mouse model. BALB/c mice were randomized into exposed and control groups. We found that the levels of soluble tumor necrosis factor receptor I was increased following the PM2.5 exposure. 16S rRNA sequencing of respiratory tract lavage fluid confirmed that the composition of the respiratory tract microecology was altered by the exposure. Lactobacillus was the most abundant of bacterial species present. Collectively, these results establish a link between exposure to fine particulate matter and alterations to the respiratory tract microecology. Elucidation of the underlying mechanisms may lead to treatment strategies in lung injury.

Physicochemical characterization and sources of the thoracic fraction of road dust in a Latin American megacity

Road dust has been identified as one of the main sources of outdoor PM₁₀ in Bogota (a Latin American megacity), but there are no studies that have analyzed the physicochemical characteristics and origins of its respirable fraction. A characterization of inorganic compounds (water soluble ions, major and trace elements, organic and elemental carbon) and an analysis of source contributions to the PM₁₀ fraction of road dust were carried out in this study. A total of twenty road dust samples, selected from representative industrial, residential and commercial areas, were swept and resuspended to obtain the thoracic fraction. Size distribution by laser diffraction and individual particle morphology by Scanning Electron Microscopy were also evaluated. The data obtained revealed that the volume (%) of thoracic particles was higher in samples from industrial zones where heavy vehicular traffic, industrial emissions and deteriorated pavements predominated. Crustal elements were the most abundant species, accounting for 49-62% of the thoracic mass, followed by OC (13-29%), water-soluble ions (1.4-3.8%), EC (0.8-1.9%) and trace elements (0.2-0.5%). The Coefficient of Divergence was obtained to identify the spatial variability of the samples. A source apportionment analysis was carried out considering the variability of chemical profiles, enrichment factors and ratios of Fe/Al, K/Al, Ca/Al, Ti/Al, Cu/Sb, Zn/Sb, OC/TC and OC/EC. By means of a PCA analysis, five components were identified, including local soils and pavement erosion (63%), construction and demolition activities (13%), industrial emissions (6%), brake wear (5%) and tailpipe emissions (4%). These components accounted for 91% of the total variance. The results provide data to understand better one of the main sources of PM₁₀ emissions in Bogota, such as road dust. These data will be useful to optimize environmental policies, and they may be used in future studies of human health and air quality modeling.

Effect of PM2.5 environmental pollution on rat lung

Particulate matter smaller than 2.5 μm (PM2.5) is a continuing challenge to pulmonary health. Here, we investigated the mechanisms involved in PM2.5 exposure-induced acute lung injury in rats. We analyzed biochemical and morphological changes following a 2-week "real-world" exposure. And then we found that PM2.5 exposure increased the concentrations of total protein, malondialdehyde, hydrogen peroxide, nitric oxide, and soluble elastin in bronchoalveolar lavage fluid, levels of cytokines in blood, and expression of MMP-9 in airways. Further, alveolar macrophage and neutrophil counts increased following PM2.5 exposure, and edema and lung lesions were observed. Our results suggest that PM2.5 exposure can induce oxidative stress and acute inflammatory responses, which can damage the micro-environment and decrease the repair ability of the lung, resulting in tissue damage.

Ambient Air Pollution and Biomarkers of Health Effect

Recently, the air pollution situation of our country is very serious along with the development of urbanization and industrialization. Studies indicate that the exposure of air pollution can cause a rise of incidence and mortality of many diseases, such as chronic obstructive pulmonary disease (COPD), asthma, myocardial infarction, and so on. However, there is now growing evidence showing that significant air pollution exposures are associated with early biomarkers in various systems of the body. In order to better prevent and control the damage effect of air pollution, this article summarizes comprehensively epidemiological studies about the bad effects on the biomarkers of respiratory system, cardiovascular system, and genetic and epigenetic system exposure to ambient air pollution.

PM2.5 exposure significantly improves the exacerbation of A549 tumor-bearing CB17-SCID mice

Here we investigate the effects and potential mechanisms of PM2.5 on tumor development in a lung cancer mouse model. Tumor-bearing mice (n = 32) were established and randomized into two groups: the PM2.5 or NS exposure group. Compared with the NS exposure group, mice in the PM2.5 exposure group showed an increased number of tumor nodules, increased BAL fluid protein levels, and elevated expressions of MMP1, IL1β and VEGF. Measurement of angiogenesis from blood serum using an angiogenesis antibody array revealed increased levels of 12 angiogenesis factors in mice after PM2.5 exposure. We also isolated bacteria from the upper respiratory tract of the mice and found that the microecosystem of the upper respiratory tract of tumor-bearing mice was perturbed by PM2.5 exposure. Our findings further establish a key link between PM2.5 and lung cancer and further elucidation of these mechanisms may reveal potential treatment strategies for lung cancer.

A multicomponent kinetic model established for investigation on atmospheric new particle formation mechanism in H2SO4-HNO3-NH3-VOC system

Secondary new particle formation (NPF) plays a significant role in atmospheric particulate matters (e.g., PM2.5), and has been studied over the past decades. However, the mechanism of NPF still remains ambiguous, setting significant barrier for PM2.5 mitigations, especially in complex atmosphere with multi-pollutants. Since the NPF process can hardly be observed directly by experiment methods due to the measuring limitations, a multicomponent kinetic model (MKM), which can be used to analyze the process and the mechanism of NPF in H₂SO₄-HNO₃-NH₃-VOC (Volatile Organic Compounds) system, has been developed in this paper. According to MKM, seven cases with initial concentrations of total precursor vapors (CPV) in the range of 10⁷-10⁸cm^-3 were calculated to analyze the NPF process. Firstly, the 3nm particle (PM_3nm) formation rate was calculated via MKM, which showed a good agreement with the previous measurements. Moreover, according to MKM calculation, it is found that the peak value of PM_3nm formation rate, i.e., J_m, is proportional to [CPV]², while the time at which J_m occurred, i.e., t_m, is proportional to [CPV]^-1/3, indicating that the increases in CPV would lead to a significant increase of J_m and decrease of t_m. That's why NPF bursts immediately and PM2.5 pollution occurs suddenly in heavily pollutant areas. Afterwards, the roles of precursors in H₂SO₄-HNO₃-NH₃-VOC system were identified. It indicates that H₂SO₄, NH₃ and VOC mainly contribute to the early stage of the NPF, while the growth of the nuclei is mainly driven by HNO₃ and NH₃. And HNO₃ makes increasing contributions at the early stage of NPF with CPV rising (especially above 10⁸cm^-3). Thus in high CPV areas, especially for China, HNO₃ should be paid the same attention as H₂SO₄, NH₃ and VOC. The findings provide important implications for haze mitigations in China and other industrializing countries with multi-pollutant emission sources.

Inhibition of miR-32 activity promoted EMT induced by PM2.5 exposure through the modulation of the Smad1-mediated signaling pathways in lung cancer cells

Epithelial mesenchymal transition (EMT) is a crucial morphological event during tumor progression. The present study reported that EMT could be triggered by airborne fine particulate matter (PM) with a mean diameter of less than 2.5 μm (PM2.5) in human lung cancer cells. We also aimed to elucidate the possible mechanisms of these processes. The results showed that treatment with PM2.5 promoted the activity of the SMAD family member 1 (Smad1)-mediated signaling pathway and downregulated the expression of the inhibitory Smad proteins Smad6 and Smad7 in lung cancer cells. Moreover, the knockdown of Smad1 suppressed the EMT process induced by PM2.5 exposure. Our data further revealed that miR-32 has a negative effect on PM2.5-induced EMT. The results showed that the expression level of miR-32 was significantly upregulated in the PM2.5-induced EMT process. The knockdown of miR-32 enhances the activity of the Smad1-mediated signaling pathway, which promotes the EMT process induced by PM2.5. Thus, these findings indicate that PM2.5 can induce the EMT process through the Smad1-mediated signaling pathway, and miR-32 may act as an EMT inhibitor in lung cancer cells.

Long-term exposure to high air pollution induces cumulative DNA damages in traffic policemen

The specific effects of long-term exposure to high air pollution on human health and biological remain unclear. To explore the adverse health effects as well as biological mechanisms and biomarkers for durative exposure to air pollution, 183 traffic policemen and 88 office policemen were enrolled in this study. The concentration of PM2.5 in both the traffic and office policemen's working environments were obtained. Detailed personal questionnaires were completed and levels of inflammation, oxidative stress and DNA damage markers of all participants were analyzed in this study. The average PM2.5 concentration of the intersections of main roads and the offices of control group were 132.4±48.9μg/m³ and 50.80±38.6μg/m³, respectively. The traffic policemen, who stably exposed to at least 2 times higher PM2.5 in their work area as compared with the control group, have a median average duration of 7.00years, and average cumulative intersection duty time reached 8030h. No statistically significant differences in the levels of inflammation markers were observed between the traffic and office policemen. However, the DNA damage markers in traffic policemen shared significant positive correlation with cumulative intersection duty time and higher than those in the office policemen. Multiple linear regression analysis demonstrated that the increase of cumulative intersection duty time by 1h per day for one year was associated with the increase in 8-hydroxy-20-deoxyguanosine of 0.329% (95% CI: 0.249% to 0.409%), tail DNA of 0.051% (95% CI: 0.041% to 0.061%), micronucleus frequency of 0.036‰ (95% CI: 0.03‰ to 0.043‰), and a decrease in glutathione of 0.482% (95% CI: -0.652% to -0.313%). These findings suggest that long-term exposure to high air pollution could induce cumulative DNA damages, supporting the hypothesis that durative exposure to air pollution is associated with an increased risk of cancer.

Effects of fine air particulates on gene expression in non-small-cell lung cancer

PURPOSE

Airborne particulate matter smaller than 2.5μm (PM_2.5) has been shown to induce adverse health effects through various mechanisms. However, its effects on gene expression in non-small-cell lung cancer (NSCLC) remain undefined. The aim of this study was to analyze the expression profile of PM_2.5-induced adverse health effects on human.

MATERIALS AND METHODS

We performed RNA sequencing to elucidate key molecular effects of PM_2.5 collected from Shenyang China, to identify potential diagnostic markers or therapeutic targets, and further validated these differences in gene expression by using quantitative PCR in A549 and H1299 human non-small-cell lung cancer cell lines. To investigate the functional changes on PM_2.5 exposed cells, we carried out the viability assay for the cell counting, and the Boyden chamber assay for invasion.

RESULTS

We found 143 genes that were expressed at least twice as much, or no more than half as much, in NSCLC cells exposed to PM_2.5 than in unexposed cells. Results showed deregulated genes confronted PM_2.5 exposure were significantly expressed, but commonly expressed in NSCLC cells. In addition, according to the viability assay and the Boyden chamber assay, PM_2.5 exposed cells which have more competent on proliferation and invasion can keep the line with the results in RNA-Seq.

CONCLUSION

Our data may provide a more specific understanding of the signaling patterns associated with pathogenesis, and lead to novel markers and therapeutic targets for NSCLC.

PM2.5-induced alterations of cell cycle associated gene expression in lung cancer cells and rat lung tissues

The aim of the current study was to investigate the expression of cell cycle-associated genes induced by fine particulate matter (PM_2.5) in lung cancer cell line and tissues. The pulmonary lymph node metastasis cells (H292) were treated with PM_2.5in vitro. Wistar rats were used to perform an in vivo study. Rats were randomly assigned to experiment and control groups and those in the experiment group were exposed to PM_2.5 once every 15 d, while those in the control group were exposed to normal saline. The cell cycle-associated genes expression was analyzed by real-time PCR. Trachea and lung tissues of rats were processed for scanning electron microscopic (SEM) examinations. Exposure of H292 cells to PM_2.5 dramatically increased the expressions of p53 and cyclin-dependent kinase 2 (CDK2) after 24h of exposure (p<0.01) and markedly increased the expressions of the cell division cycle 2 (Cdc2) and cyclin B after 48h of exposure (p<0.01), while those genes expressions were significantly reduced after 72h of exposure, at which time the expression of p21 was predominant (p<0.01). In vivo studies further demonstrated these results. The results of SEM suggested that both of the trachea and lung tissues were damaged and the degree of damage was time-dependent. In conclusion, PM_2.5 can induce significantly alterations of p53 and CDK2 in the early phase, Cdc2 and cyclin B in mid-term and p21 in long-term exposure. The degree of PM_2.5-induced damage to the trachea and lung tissue was time-dependent.

Fine Particulate Matter Concentrations in Urban Chinese Cities, 2005-2016: A Systematic Review

Background: Particulate matter pollution has become a growing health concern over the past few decades globally. The problem is especially evident in China, where particulate matter levels prior to 2013 are publically unavailable. We conducted a systematic review of scientific literature that reported fine particulate matter (PM_2.5) concentrations in different regions of China from 2005 to 2016. Methods: We searched for English articles in PubMed and Embase and for Chinese articles in the China National Knowledge Infrastructure (CNKI). We evaluated the studies overall and categorized the collected data into six geographical regions and three economic regions. Results: The mean (SD) PM_2.5 concentration, weighted by the number of sampling days, was 60.64 (33.27) μg/m³ for all geographic regions and 71.99 (30.20) μg/m³ for all economic regions. A one-way ANOVA shows statistically significant differences in PM_2.5 concentrations between the various geographic regions (F = 14.91, p < 0.0001) and the three economic regions (F = 4.55, p = 0.01). Conclusions: This review identifies quantifiable differences in fine particulate matter concentrations across regions of China. The highest levels of fine particulate matter were found in the northern and northwestern regions and especially Beijing. The high percentage of data points exceeding current federal regulation standards suggests that fine particulate matter pollution remains a huge problem for China. As pre-2013 emissions data remain largely unavailable, we hope that the data aggregated from this systematic review can be incorporated into current and future models for more accurate historical PM_2.5 estimates.

The effects for PM2.5 exposure on non-small-cell lung cancer induced motility and proliferation

Background

Increasing urbanization and associated air pollution, including elevated levels of particulate matter (PM), are strongly correlated with the development of various respiratory diseases. In particular, PM2.5 has been implicated in promoting lung cancer initiation, growth and progression. Cell migration and proliferation are crucial for the progression of cancer. However, the molecular signatures and biological networks representing the distinct and shared features of non-small cell lung cancer (NSCLC) after PM2.5 exposure are unknown.

Results

Functional assays demonstrated higher proliferation, migration and invasion of cancer cells stimulated with PM2.5. To investigate the complicated mechanisms, we performed global transcriptome profiling of the A549 cell line. Particularly, transcriptome sequencing revealed invasive characteristics reminiscent of cancer cells. By comparing the transcriptomes, we identified distinct molecular signatures and cellular processes defining the invasive and proliferative properties of PM2.5-exposed cells, respectively. Interestingly, under the PM2.5-stimulated condition, the A549 and H1299 cells strengthened obviously properties in motility and proliferation. Based on the network model reconstructing the shared protein–protein interactions, we selected the two most up-regulated genes, interleukin-1β (IL1β) and matrix metalloprotease 1 (MMP1), as key regulators responsible for the effects of PM2.5 exposure. Notably, IL1β and MMP1 expression was elevated in independent assays, which was further enhanced by PM2.5.

Conclusion

Taken together, our systems approach to investigating PM2.5 exposure provides a basis to identify key regulators responsible for the pathological features of NSCLC.

A Bio-assessment of DNA damage by Alkaline Comet Assay in metal workers of Kano metropolis, Nigeria

Metallic work is one of the widespread economic activities in urban Kano. Little or no attention is usually directed at occupational health risk by local or state authorities in Kano. The present work was aimed at the evaluation of DNA damage in metal workers by Alkaline Comet Assay in blood lymphocytes. The results showed that there was significant difference statistically between the level of DNA damage in blood lymphocytes of metal workers and control group (p < 0.05). In addition, the level of damage to DNA in blood of subjects with long term exposure and old age is of serious concern. There is the need to monitor occupational activities that can pose serious health risks. The relative ignorance of the metal workers about the health risks they are exposed to as well as the public should be addressed.