Damage effects of dust storm PM2.5 on DNA in alveolar macrophages and lung cells of rats

Lipid Dysregulation Induced by Gasoline and Diesel Exhaust Exposure and the Interaction with Age

Limited knowledge exists regarding gasoline and diesel exhaust effects on lipid metabolism. This study collected gasoline and diesel exhaust under actual driving conditions and conducted inhalation exposure on male young and middle-aged C57BL/6J mice for 4 h/day for 5 days to simulate commuting exposure intensity. Additionally, PM2.5 from actual roadways, representing gasoline and diesel vehicles, was generated for exposure to human umbilical vein endothelial cells (HUVECs) and normal liver cells (LO2) for 24, 48, and 72 h to further investigate exhaust particle toxicity. Results showed that diesel exhaust reduced total cholesterol and low-density lipoprotein cholesterol levels in young mice, indicating disrupted lipid metabolism. Aspartate aminotransferase and alanine aminotransferase levels increased by 53.7% and 21.7%, respectively, suggesting potential liver injury. Diesel exhaust exposure decreased superoxide dismutase and increased glutathione peroxidase levels. Cell viability decreased, and reactive oxygen species levels increased in HUVECs and LO2 following exposure to exhaust particles, with dose- and time-dependent effects. Diesel exhaust particles exhibited more severe inhibition of cell proliferation and oxidative damage compared to gasoline exhaust particles. These findings provide novel evidence of the risk of disrupted lipid metabolism due to gasoline and diesel exhaust, emphasizing the toxicity of diesel exhaust.

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.

On-Chip Free-Flow Measurement Revealed Possible Depletion of Macrophages by Indigestible PM2.5 within a Few Hours by the Fastest Intervals of Serial Phagocytosis

To understand the influence of indigestible particles like particulate matter 2.5 (PM2.5) on macrophages, we examined the time course of the series phagocytosis of indigestible 2 μm polystyrene spheres (PS). Five kinds of antigens were used as samples for phagocytosis; Zymosan, non-coated 2 μm PS, bovine serum albumin (BSA)-coated PS (BSA-PS), IgG-coated PS (IgG-PS), and IgG-BSA-coated PS (IgG/BSA-PS). To keep the surrounding concentration of antigens against single macrophages constant, antigens flowed at a continuous rate of 0.55 μm/s within a culture dish as a free-flow measurement assay (on-chip free-flow method). The interval of series phagocytosis for IgG/BSA-PS was the shortest among five samples; it was six times faster than Zymosan in terms of engulfment frequency, and up to 50 particles were engulfed within two hours, maintaining constant intervals until reaching the maximum number. The rate of increase in the total number of phagocytozed IgG/BSA-PS over time was constant, at 1.5 particles/min, in series phagocytosis with a 33-cell population, indicating that the phagocytosis rate constant remained constant independent of the number of phagocytoses. Reaction model fitting of the results showed that IgG/BSA-PS had the highest efficiency in terms of the phagocytosis rate constant, 2.3 × 10-2 particles/min, whereas those of IgG-PS, BSA-PS, PS, and Zymosan were 1.4 × 10-2, 1.1 × 10-2, 4.2 × 10-3, and 3.6 × 10-3 particles/min, respectively. One-by-one feeding of IgG/BSA-PS with optical tweezers was examined to confirm the phagocytosis intervals, and we found that the intervals remained constant until several times before the maximum number of antigens for engulfment, also indicating no change in the phagocytosis rate constant regardless of the history of former phagocytosis and phagocytosis number. Simultaneous phagocytosis of two IgG-BSA-decorated microneedle engulfments also showed that the initiation and progress of two simultaneous engulfments on the two different places on a cell were independent and had the same elongation velocity. Therefore, each phagocytosis of indigestible antigens does not affect both in series or in simultaneous subsequent phagocytosis until reaching the maximum capacity of the phagocytosis number. The results suggest (1) no change in the phagocytosis rate constant regardless of the history of phagocytosis numbers and attachment timing and positions, and (2) IgG-BSA decoration of indigestible microparticles in blood accelerates their engulfment faster, resulting in a severe shortage of macrophages within the shortest time.

Heavy metal analysis in of indoor and outdoor dust extracts and cytotoxicity evaluation and inflammation factors on lung, gastric and skin cell lines

Dust particles (DPs) are one of the most important public health concerns in the urban environment. The presence of heavy metals (HMs) on the surface of DPs might increase the health risk of exposure to the DPs. Accordingly, The purpose of this study was to examine the content of HMs in the outdoor and indoor DPs in Neyshabur city and assess the cytotoxic effects of DPs exposure on lung, gastric, and skin cell lines. To this end, the city was divided into three areas, high-traffic, medium-traffic, and low-traffic (rural). The average concentration of the HMs in the indoor DPs were as follows, 655.5 μg g-1 for Zn, 114.6 μg g-1 for Cu, 77.7 μg g-1 for Cr, 108.6 μg g-1 for Ni, 52 μg g-1 for Pb, 12 μg g-1 for Co, and 3.3 μg g-1 for Cd, while the average concentration of Zn, Cu, Cr, Ni, Pb, Co, Cd in the outdoor DPs were 293.7 μg g-1, 200.6 μg g-1, 100.7 μg g-1, 68.4 μg g-1, 44.7 μg g-1, 18.6 μg g-1, 0.25 μg g-1, respectively. A higher concentration of HMs, as well as cytotoxicity, were revealed in the indoor samples compared to outdoor ones. The degree of cytotoxicity of DPs collected from high-traffic areas was higher than that of low and medium-traffic ones. In addition, treatment of AGS and L929 cells with indoor dust samples induced the expression level of inflammatory agents such as TNFα, IL6, and, CYP1A1 genes more than in outdoor dust samples (P < 0.05). Briefly, a higher level of HMs concentration and cytotoxicity effect on the given cell lines was observed in the samples taken from indoor environments and high-traffic areas.

Alveolar Type II Cell Damage and Nrf2-SOD1 Pathway Downregulation Are Involved in PM2.5-Induced Lung Injury in Rats

The general toxicity of fine particulate matter (PM_2.5) has been intensively studied, but its pulmonary toxicities are still not fully understood. To investigate the changes of lung tissue after PM_2.5 exposure and identify the potential mechanisms of pulmonary toxicity, PM_2.5 samples were firstly collected and analyzed. Next, different doses of PM_2.5 samples (5 mg/kg, 10 mg/kg, 20 mg/kg) were intratracheally instilled into rats to simulate lung inhalation of polluted air. After instillation for eight weeks, morphological alterations of the lung were examined, and the levels of oxidative stress were detected. The data indicated that the major contributors to PM_2.5 mass were organic carbon, elemental carbon, sulfate, nitrate, and ammonium. Different concentrations of PM_2.5 could trigger oxidative stress through increasing reactive oxygen species (ROS) and 8-hydroxy-2'-deoxyguanosine (8-OHdG) levels, and decreasing expression of antioxidant-related proteins (nuclear factor erythroid 2-related factor 2 (Nrf2), superoxide dismutase 1 (SOD1) and catalase). Histochemical staining and transmission electron microscopy displayed pulmonary inflammation, collagen deposition, mitochondrial swelling, and a decreasing number of multilamellar bodies in alveolar type II cells after PM_2.5 exposure, which was related to PM_2.5-induced oxidative stress. These results provide a basis for a better understanding of pulmonary impairment in response to PM_2.5.

Organic carbon and acidic ions in PM2.5 contributed to particle bioreactivity in Chinese megacities during haze episodes

Fine particulate matter (PM_2.5) has been linked to cardiopulmonary disease and systemic effects in humans. However, few studies have investigated the particle bioreactivity in Chinese megacities during haze episodes. The objective of this study was to determine the contributions of chemical components in PM_2.5 to particle bioreactivity in Chinese megacities during haze episodes. PM_2.5 samples were collected in 14 megacities across China from 23 December 2013 to 16 January 2014. Average PM_2.5 concentrations ranged 88.92~199.67 μg/m³. Organic carbon (OC), elemental carbon (EC), anions, and cations per unit of PM_2.5 were linked to cellular bioreactivity (i.e., reactive oxygen species (ROS) as assessed by dichlorodihydrofluorescein diacetate (DCFH) and inflammation as assessed by interleukin (IL)-6 in A549 cells). The contributions of chemicals in PM_2.5 to ROS and inflammation were examined by the Pearson correlation coefficient and random forests. These results indicated that OC, Ca²⁺, SO₄^2-, Cl^-, F^-, K⁺, and NO₃^- contributed to ROS production, whereas OC, Cl^-, EC, K⁺, F^-, Na⁺, and Ca²⁺ contributed to inflammation. In conclusion, PM_2.5-contained OC and acidic ions are important in regulation of oxidative stress and inflammation during haze episodes. Our findings suggest that severe haze PM_2.5 events cause deterioration in air quality and may adversely affect human health.

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.

Environmental Exposures and Lung Aging: Molecular Mechanisms and Implications for Improving Respiratory Health

PURPOSE OF REVIEW

Inhaled environmental exposures cause over 12 million deaths per year worldwide. Despite localized efforts to reduce environmental exposures, tobacco smoking and air pollution remain the urgent public health challenges that are contributing to the growing prevalence of respiratory diseases. The purpose of this review is to describe the mechanisms through which inhaled environmental exposures accelerate lung aging and cause overt lung disease.

RECENT FINDINGS

Environmental exposures related to fossil fuel and tobacco combustion and occupational exposures related to silica and coal mining generate oxidative stress and inflammation in the lungs. Sustained oxidative stress causes DNA damage, epigenetic instability, mitochondrial dysfunction, and cell cycle arrest in key progenitor cells in the lung. As a result, critical repair mechanisms are impaired, leading to premature destruction of the lung parenchyma. Inhaled environmental exposures accelerate lung aging by injuring the lungs and damaging the cells responsible for wound healing. Interventions that minimize exposure to noxious antigens are critical to improve lung health, and novel research is required to expand our knowledge of therapies that may slow or prevent premature lung aging.

PM2.5 induces autophagy-mediated cell apoptosis via PI3K/AKT/mTOR signaling pathway in mice bronchial epithelium cells

Air pollution can highly impact the respiratory system in healthy individuals. Studies have indicated that particles with an aerodynamic diameter of ≤2.5 µm (PM2.5) can be considered to be harmful for lung alveoli and bronchial epithelium cells. PM2.5 can be directly inhaled and can deeply penetrate into the lung alveoli, causing lung dysfunction. However, the toxicological mechanism mediated by PM2.5 for respiratory disease has still not been clearly determined. The purpose of the current study was to investigate the effects of PM2.5 on mouse bronchial epithelium cells (MBECs) and explored the possible mechanism mediated by PM2.5 in MBECs. The results of the current study indicated that PM2.5 markedly decreased lung function, including total lung capacity, residual volume, vital capacity and airway resistance in experimental mice. The results demonstrated that PM2.5 markedly induced inflammatory responses, oxidative injury and MBEC apoptosis. PM2.5 increased interleukin (IL)-1β and IL-6 expression, and reactive oxygen species production in MBECs. Furthermore, PM2.5 specifically induced PI3K, AKT and mTOR expression in MBECs. Disruption of PI3K/AKT/mTOR signaling was also indicated to effectively inhibit apoptosis of MBECs. In conclusion, the results of the current study systematically demonstrated the role of apoptosis-mediated MBEC apoptosis in PM2.5-treated mice, and provides a potential strategy for preclinical intervention in patients with PM2.5-induced lung diseases.

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

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

Sargassum horneri (Turner) inhibit urban particulate matter-induced inflammation in MH-S lung macrophages via blocking TLRs mediated NF-κB and MAPK activation

ETHNOPHARMACOLOGICAL RELEVANCE

Sargassum horneri is a nutrient rich edible brown seaweed with numerous biological properties found in shallow coastal areas of Korean peninsula. S. horneri traditionally used as a medicinal ingredient to treat several disease conditions such as hyperlipidemia, hypertension, heart disease, and inflammatory diseases (furuncle). However, to utilize S. horneri as an active ingredient for functional foods and human health applications requires to conform the bioactive properties and underlying mechanisms of those activities.

AIM OF THE STUDY

Here, we investigated anti-inflammatory mechanisms of commercial grade 70% ethanol extract separated from S. horneri (SHE) on inflammatory response in particulate matter (PM)-induced MH-S lung macrophages; where PM in breathable air one of the major health concern in Korea.

MATERIALS AND METHODS

We compared the anti-inflammatory effects of SHE on the activity of toll-like receptors (TLR) activation, NF-κB, MAPKs, and pro-inflammatory cytokine secretion in MH-S lung macrophages exposed to PM as a lung inflammation model.

RESULTS

According to the results, PM-stimulation, induced the levels of NO, PGE2, TNF-α, IL-1β, IL-6, iNOS, and COX2 (P < 0.05) in MH-S macrophages. In addition, phosphorylation levels of NF-κB and MAPKs were also increased with the PM stimulation through the upregulated expression of TLR. However, SHE treatment significantly repressed the secretions of inflammatory cytokines and reduced protein expression such as PGE2, TNF-α, IL-6, IL-1β, NF-κB, and MAPKs from PM-activated macrophages. Specifically, SHE inhibited the upregulated mRNA expression levels of TLR2, TLR3, TLR4, and TLR7 in PM-induced MH-S cells; known biomarkers of downstream activation of NF-κB and MAPKs.

CONCLUSION

These results suggested that SHE is a potential inhibitor of PM-induced inflammatory responses in lung macrophages. Thus, SHE could inhibit PM-induced chronic inflammation in lungs via blocking TLR/NF-κB/MAPKs signal transduction. Therefore, it was concluded that SHE may be a useful substance to develop as functional product to reduce inflammation against PM-induced inflammation.

Long-term (2006-2015) variations and relations of multiple atmospheric pollutants based on multi-remote sensing data over the North China Plain

In this analysis, the Aqua/MODIS aerosol optical thickness (AOD), Aura/OMI tropospheric NO₂ and SO₂ column concentration from 2006 to 2015 were used to statistically analyze the spatial distribution characteristics and variation trends of three polluted parameters from three temporal scales of monthly, seasonal and annual average. The results showed that the minimum values of NO₂ and SO₂ column concentrations both appeared in July and August, and the maximum values appeared in December and January, which was contrary to the variations in AOD. The highly polluted levels were mainly distributed in Shijiazhuang, Xingtai, and Yancheng cities of Hebei Province, and gradually transported to Zhengzhou, Henan Province, north and southwest of Shandong Province, and Tianjin, along the main line of Taiyuan-Linyi, Shanxi Province. AOD and NO₂ had significant differences on the seasonal average scale, whereas SO₂ had little changes. These pollutants had declined year by year since 2011, in the 10-year period, AOD and SO₂ respectively decreased by 17.14% and 10.57%, and only NO₂ rose from 8.69 × 10¹⁵ molecules/cm² in 2006 to 9.10 × 10¹⁵ molecules/cm² in 2015 with the increase rate of 4.79%. Integrated with MODIS-released fire products and the Multi-resolution Emission Inventory for China (MEIC), high AOD values in summer were usually accompanied by frequent biomass burning, and heavy heating demand of coal burning led to largest NO₂ and SO₂ levels in winter. Both inter-annual variations of MEIC NOx and OMI-observed NO₂ responded to emission reductions of vehicle exhaustions positively, but vehicle population in Henan and Shandong provinces need to be further controlled. The significant decline of SO₂ is mainly attributed to the enforcement of de-sulfurization devices in power plants. Our study found that in the treatment of complex atmospheric pollution, in addition to strict control of common sources of emissions from AOD, NO₂ and SO₂, it is also necessary to consider their individual characteristics.

Ma Xing Shi Gan Decoction Attenuates PM2.5 Induced Lung Injury via Inhibiting HMGB1/TLR4/NFκB Signal Pathway in Rat

Ma Xing Shi Gan Decoction (MXD), a classical traditional Chinese medicine prescription, is widely used for the treatment of upper respiratory tract infection. However, the effect of MXD against particulate matters with diameter of less than 2.5 μm (PM2.5) induced lung injury remains to be elucidated. In this study, rats were stimulated with PM2.5 to induce lung injury. MXD was given orally once daily for five days. Lung tissues were harvested to assess pathological changes and edema. Myeloperoxidase (MPO) activity and malonaldehyde (MDA) content in lung were determined to evaluate the degree of injury. To assess the barrier disruption, the bronchoalveolar lavage fluid (BALF) was collected to determine the total protein content and count the number of neutrophils and macrophages. For evaluating the activation of macrophage in lung tissue, CD68 was detected using immunohistochemistry (IHC). The levels of inflammatory factors including tumor necrosis factor-alpha (TNF-α), interleukin-1beta (IL-1β), and interleukin-6 (IL-6) in BALF and serum were measured. In vitro, a PM2.5-activated RAW 264.7 macrophages inflammatory model was introduced. To evaluate the protective effect of MXD-medicated serum, the cell viability and the release of inflammatory factors were measured. The effects of MXD on the High mobility group box-1/Toll-like receptor 4/Nuclear factor-kappa B (HMGB1/TLR4/NFκB) pathway in lung tissue and RAW 264.7 cells were assessed by Western blot. For further confirming the protective effect of MXD was mediated by inhibiting the HMGB1/TLR4/NFκB pathway, RAW 264.7 cells were incubated with MXD-medicated serum alone or MXD-medicated serum plus recombinant HMGB1 (rHMGB1). MXD significantly ameliorated the lung injury in rats, as evidenced by decreases in the pathological score, lung edema, MPO activity, MDA content, CD68 positive macrophages number, disruption of alveolar capillary barrier and the levels of inflammatory factors. In vitro, MXD-medicated serum increased cell viability and inhibited the release of inflammatory cytokines. Furthermore, MXD treatment was found to inhibit HMGB1/TLR4/NFκB signal pathway both in vivo and in vitro. Moreover, the protection of MXD could be reversed by rHMGB1 in RAW 264.7. Taken together, these results suggest MXD protects rats from PM2.5 induced acute lung injury, possibly through the modulation of HMGB1/TLR4/NFκB pathway and inflammatory responses.

Chemical and organic characteristics of PM2.5 particles and their in-vitro cytotoxic effects on lung cells: The Middle East dust storms in Ahvaz, Iran

There are very few reports about the effect of PM_2.5 particles carried by the Middle East dust storms on lung cells. This study aimed to investigate the chemical properties and in-vitro cytotoxic effects of PM_2.5 extracts. Water-soluble fraction and organic solvent-extractable components of the samples collected from the city of Ahvaz, Khuzestan Province, Iran, during the normal and dust storm days of the winter of 2016 were analyzed and then applied on the human lung epithelial cell line (A549). The chemical properties and the cytotoxicity were analyzed by ICP-OES and Lactase Dehydrogenase (LDH) assay, respectively. The results of the independent t-test showed significantly higher mean cytotoxicity in the samples of normal days than that of dust storm days. It could be due to the fact that the cells were exposed to the same amount of water-soluble extract, whether it be from a normal day or a dust storm day, and since the normal air of Ahvaz is severely affected by traffic and industrial pollutants, its normal day samples showed stronger cytotoxic effect. The results of the Kruskal-Wallis test showed that cytotoxic effect increased with the particulate concentration. The highest cytotoxicity levels observed at 62, 125, and 250 μg/mL concentrations after 24-h incubation were 17% (belonging to a dust storm day), 37% (belonging to a normal day), and 47% (belonging to a dust storm day), respectively Since PAH compounds were measured in the particulate phase, their amount was naturally correlated with the quantity of particulates. However, it was observed that the samples of normal days contained the species with stronger human carcinogens ΣPAHs = 0.82 ng/m³.The results of one-way ANOVA showed a significant difference between the incubation times regarding the resulted cytotoxicity levels. In general, as the incubation duration increased, so did the cytotoxicity level. Although normal day particulates had a greater cytotoxic effect on A549 cell line, dust storm days are associated with higher levels of health risk; simply because during dust storms, people inhale much larger amounts of particulates.

Contributions of local pollution emissions to particle bioreactivity in downwind cities in China during Asian dust periods

This study investigated the effects of pollution emissions on the bioreactivity of PM_2.5 during Asian dust periods. PM_2.5 during the sampling period were 104.2 and 85.7 μg m^-3 in Xi'an and Beijing, respectively, whereas PM_2.5 which originated from the Tengger Desert was collected (dust background). Pollution conditions were classified as non-dust days, pollution episode (PE), dust storm (DS)-1, and DS-2 periods. We observed a significant decrease in cell viability and an increase in LDH that occurred in A549 cells after exposure to PM_2.5 during a PE and DS-1 in Xi'an and Beijing compared to Tengger Desert PM_2.5. Positive matrix factorization was used to identify pollution emission sources. PM_2.5 from biomass and industrial sources contributed to alterations in cell viability and LDH in Xi'an, whereas vehicle emissions contributed to LDH in Beijing. OC, EC, Cl^-, K⁺, Mg²⁺, Ca, Ti, Mn, Fe, Zn, and Pb were correlated with cell viability and LDH for industrial emissions in Xi'an during DS. OC, EC, SO₄^2-, S, Ti, Mn, and Fe were correlated with LDH for vehicle emissions in Beijing during DS. In conclusion, the dust may carry pollutants on its surface to downwind areas, leading to increased risks of particle toxicity.

Genotoxic and epigenotoxic effects in mice exposed to concentrated ambient fine particulate matter (PM2.5) from São Paulo city, Brazil

BACKGROUND

The Metropolitan Area of São Paulo has a unique composition of atmospheric pollutants, and positive correlations between exposure and the risk of diseases and mortality have been observed. Here we assessed the effects of ambient fine particulate matter (PM2.5) on genotoxic and global DNA methylation and hydroxymethylation changes, as well as the activities of antioxidant enzymes, in tissues of AJ mice exposed whole body to ambient air enriched in PM2.5, which was concentrated in a chamber near an avenue of intense traffic in São Paulo City, Brazil.

RESULTS

Mice exposed to concentrated ambient PM2.5 (1 h daily, 3 months) were compared to in situ ambient air exposed mice as the study control. The concentrated PM2.5 exposed group presented increased levels of the oxidized nucleoside 8-oxo-7,8-dihydro-2'-deoxyguanosine in lung and kidney DNA and increased levels of the etheno adducts 1,N6-etheno-2'-deoxyadenosine and 1,N2-etheno-2'-deoxyguanosine in kidney and liver DNA, respectively. Apart from the genotoxic effects, the exposure to PM2.5 led to decreased levels of the epigenetic mark 5-hydroxymethylcytosine (5-hmC) in lung and liver DNA. Changes in lung, liver, and erythrocyte antioxidant enzyme activities were also observed. Decreased glutathione reductase and increased superoxide dismutase (SOD) activities were observed in the lungs, while the liver presented increased glutathione S-transferase and decreased SOD activities. An increase in SOD activity was also observed in erythrocytes. These changes are consistent with the induction of local and systemic oxidative stress.

CONCLUSIONS

Mice exposed daily to PM2.5 at a concentration that mimics 24-h exposure to the mean concentration found in ambient air presented, after 3 months, increased levels of DNA lesions related to the occurrence of oxidative stress in the lungs, liver, and kidney, in parallel to decreased global levels of 5-hmC in lung and liver DNA. Genetic and epigenetic alterations induced by pollutants may affect the genes committed to cell cycle control, apoptosis, and cell differentiation, increasing the chance of cancer development, which merits further investigation.

Physicochemical characterization of ambient PM2.5 in Tehran air and its potential cytotoxicity in human lung epithelial cells (A549)

As air pollution is a major problem in Tehran, this study aimed to investigate the physicochemical characterization of the water-soluble and organic contents of ambient PM_2.5 in Tehran and determine its in vitro toxicological impact on human lung epithelial cells (A549). A total of 11 sampling stations were selected, including three categories: traffic, urban, and suburban. All sampling was carried out in the spring and summer of 2015. Ion chromatography (IC), inductively coupled plasma atomic emission spectroscopy (ICP-AES), and GC-MS were used to analyze ionic compounds, heavy metals, and polycyclic aromatic hydrocarbons (PAHs), respectively, and an ELISA reader was used for cytotoxicity analysis. The most prevalent ionic species found for all three categories was SO₄^2-. PAH concentrations were 43.45±32.71, 50.51±37.27, and 29.13±33.29ng/m³ for traffic, urban, and suburban stations, respectively. For all sampling stations, Al and Fe had the highest values among the investigated heavy metals. Cell viability measurements, carried out using the MTT assay, showed that all three categories of samples cause cytotoxicity, although the urban station samples showed higher cytotoxicity than those from the other stations (p˂0.05). Based on the results of the present study, organic compounds and insoluble particles could be the main causes of cytotoxicity.

Effects of ambient PM2.5 and 9-nitroanthracene on DNA damage and repair, oxidative stress and metabolic enzymes in the lungs of rats

Ambient fine particulate matter (PM2.5) is a complex mixture associated with lung cancer risk. PM2.5-bound nitro-polycyclic aromatic hydrocarbons (NPAHs) have been demonstrated to possess mutagenicity and carcinogenicity. Previous studies showed that PM2.5 induced DNA damage, whereas there is little knowledge of whether 9-nitroanthracene (9-NA), a typical compound of NPAHs in PM2.5, causes DNA damage. Also, the regulating mechanisms of PM2.5 and 9-NA in DNA damage and repair are not yet fully established. Here we sought to investigate the molecular mechanisms of DNA damage and repair in the lungs of male Wistar rats exposed to PM2.5 (1.5 mg per kg body weight) or three different dosages of 9-NA. And then DNA strand breaks, 8-OH-dG formation, DNA-protein crosslink and DNA repair gene expressions in rat lungs were analyzed. In addition, alteration in oxidative stress factors and metabolic enzymes were detected. The results showed that (1) PM2.5 and higher dosage 9-NA (4.0 × 10-5 and 1.2 × 10-4 mg per kg body weight) significantly caused lung DNA damage, accompanied by increasing OGG1 expression while inhibiting MTH1 and XRCC1 expression, elevating the levels of GADD153, hemeoxygenase-1 and malondialdehyde, and promoting the activities of CYP450 isozymes and glutathione S-transferase. (2) 1.3 × 10-5 mg kg-1 9-NA exposure couldn't cause DNA damage and oxidative stress. (3) At the approximately equivalent dose level, PM2.5-induced DNA damage effects were more obvious than 9-NA with positive correlation. It suggests that DNA damage caused by PM2.5 and 9-NA may be mediated partially through influencing the DNA repair capacity and enhancing oxidative stress and biotransformation, and this negative effect of 9-NA might be related to the PM2.5-induced lung genotoxicity.

Chemical composition of PM10 and its in vitro toxicological impacts on lung cells during the Middle Eastern Dust (MED) storms in Ahvaz, Iran

Reports on the effects of PM10 from dust storm on lung cells are limited. The main purpose of this study was to investigate the chemical composition and in vitro toxicological impacts of PM10 suspensions, its water-soluble fraction, and the solvent-extractable organics extracted from Middle Eastern Dust storms on the human lung epithelial cell (A549). Samples of dust storms and normal days (PM10 < 200 μg m(-3)) were collected from December 2012 until June 2013 in Ahvaz, the capital of Khuzestan Province in Iran. The chemical composition and cytotoxicity were analyzed by ICP- OES and Lactase Dehydrogenase (LDH) reduction assay, respectively. The results showed that PM10 suspensions, their water-soluble fraction and solvent-extractable organics from both dust storm and normal days caused a decrease in the cell viability and an increase in LDH in supernatant in a dose-response manner. Although samples of normal days showed higher cytotoxicity than those of dust storm at the highest treated dosage, T Test showed no significant difference in cytotoxicity between normal days and dust event days (P value > 0.05). These results led to the conclusions that dust storm PM10 as well as normal day PM10 could lead to cytotoxicity, and the organic compounds (PAHs) and the insoluble particle-core might be the main contributors to cytotoxicity. Our results showed that cytotoxicity and the risk of PM10 to human lung may be more severe during dust storm than normal days due to inhalation of a higher mass concentration of airborne particles. Further research on PM dangerous fractions and the most responsible components to make cytotoxicity in exposed cells is recommended.

Combined exposure to nano-silica and lead induced potentiation of oxidative stress and DNA damage in human lung epithelial cells

Growing evidence has confirmed that exposure to ambient particulate matters (PM) is associated with increased morbidity and mortality of cardiovascular and pulmonary diseases. Ambient PM is a complex mixture of particles and air pollutants. Harmful effects of PM are specifically associated with ultrafine particles (UFPs) that can adsorb high concentrations of toxic air pollutants and are easily inhaled into the lungs. However, combined effects of UFPs and air pollutants on human health remain unclear. In the present study, we elucidated the combined toxicity of silica nanoparticles (nano-SiO2), a typical UFP, and lead acetate (Pb), a typical air pollutant. Lung adenocarcinoma A549 cells were exposed to nano-SiO2 and Pb alone or their combination, and their combined toxicity was investigated by focusing on cellular oxidative stress and DNA damage. Factorial analyses were performed to determine the potential interactions between nano-SiO2 and Pb. Our results showed that exposure of A549 cells to a modest cytotoxic concentration of Pb alone induced oxidative stress, as evidenced by elevated reactive oxygen species generation and lipid peroxidation, and reduced glutathione content and superoxide dismutase and glutathione peroxidase activities. In addition, exposure of A549 cells to Pb alone induced DNA damage, as evaluated by alkaline comet assay. Exposure of A549 cells to non-cytotoxic concentration of nano-SiO2 did not induce cellular oxidative stress and DNA damage. However, exposure to the combination of nano-SiO2 and Pb potentiated oxidative stress and DNA damage in A549 cells. Factorial analyses indicated that the potentiation of combined toxicity of nano-SiO2 and Pb was induced by additive or synergistic interactions.

Estimating PM2.5 Concentrations in Xi'an City Using a Generalized Additive Model with Multi-Source Monitoring Data

Particulate matter with an aerodynamic diameter <2.5 μm (PM2.5) represents a severe environmental problem and is of negative impact on human health. Xi'an City, with a population of 6.5 million, is among the highest concentrations of PM2.5 in China. In 2013, in total, there were 191 days in Xi'an City on which PM2.5 concentrations were greater than 100 μg/m3. Recently, a few studies have explored the potential causes of high PM2.5 concentration using remote sensing data such as the MODIS aerosol optical thickness (AOT) product. Linear regression is a commonly used method to find statistical relationships among PM2.5 concentrations and other pollutants, including CO, NO2, SO2, and O3, which can be indicative of emission sources. The relationships of these variables, however, are usually complicated and non-linear. Therefore, a generalized additive model (GAM) is used to estimate the statistical relationships between potential variables and PM2.5 concentrations. This model contains linear functions of SO2 and CO, univariate smoothing non-linear functions of NO2, O3, AOT and temperature, and bivariate smoothing non-linear functions of location and wind variables. The model can explain 69.50% of PM2.5 concentrations, with R2 = 0.691, which improves the result of a stepwise linear regression (R2 = 0.582) by 18.73%. The two most significant variables, CO concentration and AOT, represent 20.65% and 19.54% of the deviance, respectively, while the three other gas-phase concentrations, SO2, NO2, and O3 account for 10.88% of the total deviance. These results show that in Xi'an City, the traffic and other industrial emissions are the primary source of PM2.5. Temperature, location, and wind variables also non-linearly related with PM2.5.

Applications of the comet assay in particle toxicology: air pollution and engineered nanomaterials exposure

Exposure to ambient air particles is associated with elevated levels of DNA strand breaks (SBs) and endonuclease III, formamidopyrimidine DNA glycosylase (FPG) and oxoguanine DNA glycosylase-sensitive sites in cell cultures, animals and humans. In both animals and cell cultures, increases in SB and in oxidatively damaged DNA are seen after exposure to a range of engineered nanomaterials (ENMs), including carbon black, carbon nanotubes, fullerene C60, ZnO, silver and gold. Exposure to TiO2 has generated mixed data with regard to SB and oxidatively damaged DNA in cell cultures. Nanosilica does not seem to be associated with generation of FPG-sensitive sites in cell cultures, while large differences in SB generation between studies have been noted. Single-dose airway exposure to nanosized carbon black and multi-walled carbon nanotubes in animal models seems to be associated with elevated DNA damage levels in lung tissue in comparison to similar exposure to TiO2 and fullerene C60. Oral exposure has been associated with augmented DNA damage levels in cells of internal organs, although the doses have been typically very high. Intraveneous and intraperitoneal injection of ENMs have shown contradictory results dependent on the type of ENM and dose in each set of experiments. In conclusion, the exposure to both combustion-derived particles and ENMs is associated with increased levels of DNA damage in the comet assay. Particle size, composition and crystal structure of ENM are considered important determinants of toxicity, whereas their combined contributions to genotoxicity in the comet assay are yet to be thoroughly investigated.

Investigation on the lung function of general population in Ilam, west of Iran, as a city exposed to dust storm

BACKGROUND

Dust storm is one of the most important natural sources of air pollution in the Middle East that has caused a major concern in recent years. The aim of this study was to evaluate the respiratory tract function of people living in Ilam city (Iran) during dust storm.

METHODS

A sample size of 250 people was selected and the cluster sampling was randomly used from 13 health centers in Ilam city. Pulmonary function test (PFT) was determined via a standard spirometry apparatus. Vital capacity (VC), Forced Vital capacity (FVC), FVC in first second (FEV1), FEV1/VC, FEV1/FVC, peek expiratory flow (PEF), forced expiratory flow (FEF25-75%), forced expiratory flow (FEF25-75%), forced expiratory flow (FEF75-85%), forced mid flow time (FMFT) and maximum voluntary ventilation (MVV) were measured.

RESULTS

Mean values of respiratory capacities measured in all participants excluding FEV1/VC and FMFT were less than predicted mean values by ECCS reference. 21.6% of the population suffered from obstructive lesions. This value among males (24.1%) was more than females (19.6%). This could be related to more exposure (outdoor jobs) of males with dust storms.

CONCLUSION

The results also showed a negative significant relationship between duration of inhabitance in Ilam city and all respiratory capacities. Further studies are needed for confident confirmation of whether reduction of respiratory capacities among Ilamian people is only related to dust storms.

Effects of Long-Term Dust Exposure on Human Respiratory System Health in Minqin County, China

The aim of this study was to assess the effects of long-term sand dust exposure on human respiratory health. Dust events break out frequently in Minqin County, northwest China, whereas Pingliang City, northwest China, is rarely influenced by dust events. Therefore, Minqin and Pingliang were selected as sand dust exposure region and control area, respectively. The incidence of respiratory system diseases and symptoms was determined through a structured respiratory health questionnaire (ATS-DLD-78-A) and personal interviews. The subjects comprised 728 farmers (Minqin, 424; Pingliang, 304) aged 40 years or older, who had nondocumented occupational history to industrial dust exposure. Prevalences (odds ratio [OR], 95% confidence interval [CI]) of chronic rhinitis, chronic bronchitis, and chronic cough increased 9.6% (3.141, 1.776-5.555), 7.5% (2.468, 1.421-4.286), and 10.2% (1.787, 1.246-2.563) in Minqin comparison with Pingliang, respectively, and the differences were significant (p <.01).

Nitrogen dioxide inhalation induces genotoxicity in rats

Nitrogen dioxide (NO(2)) is a ubiquitous reactive free-radical gas, which has been associated with momentary and chronic health effects. In the present study, comet, micronucleus (MN) and DNA-protein crosslinks (DPC) assays were used to investigate the genotoxicity following in vivo inhalation exposure of rats to NO(2). The results show that inhalation exposure of rats to NO(2) induced DNA strand breakage and the formation of DPC in the cells from various internal organs (brain, lung, liver, spleen, kidney and heart), as well as resulted in obvious increase of MN frequency in the bone marrow cells of rats. Furthermore, above genotoxic responses showed significant linear dose-dependent manners. These results implicate that NO(2) is a genotoxic agent and these observations are informative for understanding the mechanisms of adverse effects of nitrogen dioxide.

Inflammatory and degranulation effect of yellow sand on RBL-2H3 cells in relation to chemical and biological constituents

Recent studie pointed out that allergic diseases have increased during the Asian dust storm event (ADSE) in Japan. Daily observations and the atmospheric concentrations of yellow sand (YS) aerosol have been increasing. In this study, YS samples collected from three sites of Japan during ADSE in 2009-2010 were used. The particles were analyzed by X-ray photoelectron spectroscopy (XPS) and X-ray fluorescence-energy dispersive spectrometer (XRF-EDS). We investigate ability of YS extract on enhancing the chemical mediator release and cytokine production from rat basophilic leukemia (RBL-2H3) cells. The dust particles at Fukuoka and Tsukuba were abundant in aluminum (Al), iron (Fe), potassium (K) and titan (Ti) than those at Naha. Concentration of the trace endotoxin and Cryptomeria japonica pollen allergen (Cry j 1) were measured in YS extract. After exposure of RBL-2H3 cells to YS extract, the β-hexosaminidase (β-hex) release, tumor necrosis factor-alpha (TNF-α) production were enhanced in RBL-2H3 cells. This process depends on endotoxin, Cry j 1 and other allergen present in the YS extract. YS water extract also show a strong cytotoxic effect on the cells. This data suggest that low levels of endotoxin and Cry j 1 in YS may cause allergy during the ADSE.

Airborne urban particles (Milan winter-PM2.5) cause mitotic arrest and cell death: Effects on DNA, mitochondria, AhR binding and spindle organization

Airborne particulate matter (PM) is considered to be an important contributor to lung diseases. In the present study we report that Milan winter-PM2.5 inhibited proliferation in human bronchial epithelial cells (BEAS-2B) by inducing mitotic arrest. The cell cycle arrest was followed by an increase in mitotic-apoptotic cells, mitotic slippage and finally an increase in "classical" apoptotic cells. Exposure to winter-PM10 induced only a slight effect which may be due to the presence of PM2.5 in this fraction while pure combustion particles failed to disturb mitosis. Fewer cells expressing the mitosis marker phospho-histone H3 compared to cells with condensed chromosomes, suggest that PM2.5 induced premature mitosis. PM2.5 was internalized into the cells and often localized in laminar organelles, although particles without apparent plasma membrane covering were also seen. In PM-containing cells mitochondria and lysosomes were often damaged, and in mitotic cells fragmented chromosomes often appeared. PM2.5 induced DNA strands breaks and triggered a DNA-damage response characterized by increased phosphorylation of ATM, Chk2 and H2AX; as well as induced a marked increase in expression of the aryl hydrocarbon receptor (AhR)-regulated genes, CYP1A1, CYP1B1 and AhRR. Furthermore, some disturbance of the organization of microtubules was indicated. It is hypothesized that the induced mitotic arrest and following cell death was due to a premature chromosome condensation caused by a combination of DNA, mitochondrial and spindle damage.

The Toll-like receptor gene family is integrated into human DNA damage and p53 networks

In recent years the functions that the p53 tumor suppressor plays in human biology have been greatly extended beyond “guardian of the genome.” Our studies of promoter response element sequences targeted by the p53 master regulatory transcription factor suggest a general role for this DNA damage and stress-responsive regulator in the control of human Toll-like receptor (TLR) gene expression. The TLR gene family mediates innate immunity to a wide variety of pathogenic threats through recognition of conserved pathogen-associated molecular motifs. Using primary human immune cells, we have examined expression of the entire TLR gene family following exposure to anti-cancer agents that induce the p53 network. Expression of all TLR genes, TLR1 to TLR10, in blood lymphocytes and alveolar macrophages from healthy volunteers can be induced by DNA metabolic stressors. However, there is considerable inter-individual variability. Most of the TLR genes respond to p53 via canonical as well as noncanonical promoter binding sites. Importantly, the integration of the TLR gene family into the p53 network is unique to primates, a recurrent theme raised for other gene families in our previous studies. Furthermore, a polymorphism in a TLR8 response element provides the first human example of a p53 target sequence specifically responsible for endogenous gene induction. These findings—demonstrating that the human innate immune system, including downstream induction of cytokines, can be modulated by DNA metabolic stress—have many implications for health and disease, as well as for understanding the evolution of damage and p53 responsive networks.

Among the most prominently studied regulators of gene function is the p53 tumor suppressor, which has many roles in human biology. The transcriptional master regulator p53 directly targets expression of >200 genes. Previously, we sought to define the p53 network in terms of functionality, specifically the ability of target response element sequences (REs) to support p53 transactivation. Here we identify p53 target canonical and noncanonical REs in the family of Toll-like Receptor (TLR) innate immune response genes and establish p53 regulation of most TLR genes. We address p53 responsiveness in primary human lymphocytes and alveolar macrophages collected from healthy volunteers. Notably, all TLR genes show responses to DNA damage, and most are p53-mediated. However, there is considerable variability between individuals, suggesting that DNA and p53 metabolic stresses can markedly differ in impact on the innate immune system as well as downstream appearance of cytokines. Indeed, we report a SNP in a p53 RE within the TLR8 promoter that alters p53 responsiveness in primary human cells. Furthermore, the p53-mediated expression of TLRs is unique to primates. Overall, these findings identify a new, pivotal role for the well-known human tumor suppressor p53, namely, integration of DNA damage and innate immune responses.

Asian dust storm particles induce a broad toxicological transcriptional program in human epidermal keratinocytes

Exposure to airborne dust particles originated from seasonal Asian dust storms in Chinese and Mongolian deserts results in increased incidence of a range of diseases including asthma, contact dermatitis and conjunctivitis. The areas affected by Asian dust particles extend from East China to the west coast of North America. In order to study toxicological mechanisms in human skin, we evaluated the effects of dust particles collected during Asian dust storms (Asian dust particles) on gene expression in human epidermal keratinocytes (HEK). In HEK, exposure to Asian dust particles significantly increased gene expressions of cytochrome P450 1A1 (CYP1A1), CYP1A2, and CYP1B1, which is an indication of aryl hydrocarbon receptor (AHR) activation. In addition, Asian dust particles increased gene transcription of the cytokines IL-6, IL-8, and GM-CSF, which have broad pro-inflammatory and immunomodulatory properties. Asian dust particles significantly up-regulated expression of caspase 14 in HEK, suggesting that Asian dust particles directly affect keratinocyte differentiation. We also demonstrated that protein extract of pollen, a material frequently adsorbed onto Asian dust particles, potentially contributes to the increased transcription of IL-6, CYP1A1, CYP1A2, and CYP1B1. Taken together, these studies suggest that Asian dust particles can exert toxicological effects on human skin through the activation of the cellular detoxification system, the production of pro-inflammatory and immunomodulatory cytokines, and changes in the expression of proteins essential in normal epidermal differentiation.