Genotoxicity induced by fine urban air particulate matter in the macrophages cell line RAW 264.7

Pathogenic Mechanisms of Secondary Organic Aerosols

Air pollution represents a major health problem and an economic burden. In recent years, advances in air pollution research has allowed particle fractionation and identification of secondary organic aerosol (SOA). SOA is formed from either biogenic or anthropogenic emissions, through a mass transfer from the gaseous mass to the particulate phase in the atmosphere. They can have deleterious impact on health and the mortality of individuals with chronic inflammatory diseases. The pleiotropic effects of SOA could involve different and interconnected pathogenic mechanisms ranging from oxidative stress, inflammation, and immune system dysfunction. The purpose of this review is to present recent findings about SOA pathogenic roles and potential underlying mechanisms focusing on the lungs; the latter being the primary exposed organ to atmospheric pollutants.

Suitability of Nanoparticles to Face Benzo(a)pyrene-Induced Genetic and Chromosomal Damage in M. galloprovincialis. An In Vitro Approach

Benzo(a)pyrene (B(a)P) is a well-known genotoxic agent, the removal of which from environmental matrices is mandatory, necessitating the application of cleaning strategies that are harmless to human and environmental health. The potential application of nanoparticles (NPs) in the remediation of polluted environments is of increasing interest. Here, specifically designed NPs were selected as being non-genotoxic and able to interact with B(a)P, in order to address the genetic and chromosomal damage it produces. A newly formulated pure anatase nano-titanium (nano-TiO2), a commercial mixture of rutile and anatase, and carbon black-derived hydrophilic NPs (HNP) were applied. Once it had been ascertained that the NPs selected for the work did not induce genotoxicity, marine mussel gill biopsies were exposed in vitro to B(a)P (2 μg/mL), alone and in combination with the selected NPs (50 µg/mL nano-TiO2, 10 µg/mL HNP). DNA primary reversible damage was evaluated by means of the Comet assay. Chromosomal persistent damage was assessed on the basis of micronuclei frequency and nuclear abnormalities by means of the Micronucleus-Cytome assay. Transmission Electron Microscopy (TEM) was performed to investigate the mechanism of action exerted by NPs. Pure Anatase n-TiO2 was found to be the most suitable for our purpose, as it is cyto- and genotoxicity free and able to reduce the genetic and chromosomal damage associated with exposure to B(a)P.

Systems chemo-biology analysis of DNA damage response and cell cycle effects induced by coal exposure

Cell cycle alterations are among the principle hallmarks of cancer. Consequently, the study of cell cycle regulators has emerged as an important topic in cancer research, particularly in relation to environmental exposure. Particulate matter and coal dust around coal mines have the potential to induce cell cycle alterations. Therefore, in the present study, we performed chemical analyses to identify the main compounds present in two mineral coal samples from Colombian mines and performed systems chemo-biology analysis to elucidate the interactions between these chemical compounds and proteins associated with the cell cycle. Our results highlight the role of oxidative stress generated by the exposure to the residues of coal extraction, such as major inorganic oxides (MIOs), inorganic elements (IEs) and polycyclic aromatic hydrocarbons (PAH) on DNA damage and alterations in the progression of the cell cycle (blockage and/or delay), as well as structural dysfunction in several proteins. In particular, IEs such as Cr, Ni, and S and PAHs such as benzo[a]pyrene may have influential roles in the regulation of the cell cycle through DNA damage and oxidative stress. In this process, cyclins, cyclin-dependent kinases, zinc finger proteins such as TP53, and protein kinases may play a central role.

Effects of emissions from sugar cane burning on the trachea and lungs of Wistar rats

Objective:

To evaluate the effects of exposure to emissions from sugar cane burning on inflammatory mechanisms in tissues of the trachea and lung parenchyma in Wistar rats after different periods of exposure.

Methods:

This was an experimental open randomized study. The animals were divided into four groups: a control group (CG) underwent standard laboratory conditions, and three experimental groups were exposed to emissions from sugar cane burning over different periods of time, in days-1 (EG1), 7 (EG7), and 21 (EG21). After euthanasia with 200 mg/kg of ketamine/xylazine, fragments of trachea and lung were collected and fixed in 10% formalin. Histological analyses were performed with H&E and picrosirius red staining.

Results:

No inflammatory infiltrates were found in the tissues of CG rats. The histological examination of tissues of the trachea and lung parenchyma revealed that the inflammatory process was significantly more intense in EG7 than in the CG (p < 0.05 and p < 0.01, respectively). In comparison with the CG and EG1, angiogenesis in the lung parenchyma and collagen deposition in tracheal tissues were significantly greater only in EG21 (p < 0.001 and p < 0.01, respectively).

Conclusions:

In this sample, emissions from sugar cane burning induced acute focal and diffuse inflammation in the lamina propria of tracheal tissues, with no loss of ciliated epithelial tissue. In the lung parenchyma of the animals in the experimental groups, there was interstitial and alveolar edema, together with polymorphonuclear cell infiltrates.

Synergistic inflammatory effect of PM10 with mycotoxin deoxynivalenol on human lung epithelial cells

The presence of deoxynivalenol (DON), a mycotoxin produced by Fusarium species, has been reported worldwide in food and feedstuffs. Even though oral intake is the main route of exposure, DON inhalation is also of concern in workers and exposed population. Particulate matter (PM) is one of the most important causes of air quality detriment and it induces several adverse health effects. Therefore it is of primary importance to understand possible combined effects of DON and PM. The alveolar type II, A549, and the bronchial epithelial, BEAS-2B, cell lines were exposed for 24 h to different concentrations of DON (10-1000 ng/ml), PM10 (5 μg/cm(2), sampled in summer or winter season), and a combination of these pollutants. Cell death, interleukins release and cell cycle alteration were analysed; protein array technique was also applied to evaluate proteins activation related to MAP-kinases cascade. Our results demonstrate that low doses of PM and DON used alone have scarce toxic effects, while induce cytotoxicity and inflammation when used in combination. This observation outlines the importance of investigation on the combined effects of air pollutants for their possible outcomes on human health.

Effect of particles of ashes produced from sugarcane burning on the respiratory system of rats

The practice of burning sugarcane obtained by non-mechanized harvesting exposes workers and the people of neighboring towns to high concentrations of particulate matter (PM) that is harmful to health, and may trigger a series of cardiorespiratory diseases. The aim of this study was to analyze the chemical composition of the micro-particles coming from sugarcane burning residues and to verify the effects of this micro-particulate matter on lung and tracheal tissues. Micro-particulate matter (PM10) was obtained by dissolving filter paper containing burnt residues in NaCl solution. This material was instilled into the Wistar rats' nostrils. Histological analyses (hematoxylin and eosin - HE) of cardiac, lung and tracheal tissues were performed. Inflammatory mediators were measured in lung tissues by using ELISA. The chemical composition of the particulate material revealed a large quantity of the phthalic acid ester, high concentrations of phenolic compounds, anthracene and polycyclic aromatic hydrocarbons (PAH). Histological analysis showed a reduction in subjacent conjunctive tissue in the trachea, lung inflammation with inflammatory infiltrate formation and reduction of alveolar spaces and a significant increase (p<0.05) in the release of IL-1α, IL-1β, IL-6, and INF-γ in the group treated with PM10 when compared to the control group. We concluded that the burning sugarcane residues release many particles, which have toxic chemical compounds. The micro-particulate matter can induce alterations in the respiratory system.

Genetic damage of organic matter in the Brazilian Amazon: a comparative study between intense and moderate biomass burning

BACKGROUND

The biomass burning that occurs in the Amazon region has an adverse effect on environmental and human health. However, in this region, there are limited studies linking atmospheric pollution and genetic damage.

OBJECTIVE

We conducted a comparative study during intense and moderate biomass burning periods focusing on the genetic damage and physicochemical analyses of the particulate matter (PM).

METHOD

PM and black carbon (BC) were determined; organic compounds were identified and quantified using gas chromatography with flame ionization detection, the cyto-genotoxicity test was performed using two bioassays: cytokinesis-block micronucleus (CBMN) in A549 cells and Tradescantia pallida micronucleus (Trad-MCN) assay.

RESULTS

The PM10 concentrations were lower than the World Health Organization air quality standard for 24h. The n-alkanes analyses indicate anthropogenic and biogenic influences during intense and moderate biomass burning periods, respectively. Retene was identified as the most abundant polycyclic aromatic hydrocarbon during both sampling periods. Carcinogenic and mutagenic compounds were identified. The genotoxic analysis through CBMN and Trad-MCN tests showed that the frequency MCN from the intense burning period is significantly higher compared to moderate burning period.

CONCLUSIONS

This is the first study using human alveolar cells to show the genotoxic effects of organic PM from biomass burning samples collected in Amazon region. The genotoxicity of PM can be associated with the presence of several mutagenic and carcinogenic compounds, mainly benzo[a]pyrene. These findings have potential implications for the development of pollution abatement strategies and can minimize negative impact on health.

Cell cycle alterations induced by urban PM2.5 in bronchial epithelial cells: characterization of the process and possible mechanisms involved

BACKGROUND

This study explores and characterizes cell cycle alterations induced by urban PM2.5 in the human epithelial cell line BEAS-2B, and elucidates possible mechanisms involved.

METHODS

The cells were exposed to a low dose (7.5 μg/cm(2)) of Milan winter PM2.5 for different time points, and the cell cycle progression was analyzed by fluorescent microscopy and flow cytometry. Activation of proteins involved in cell cycle control was investigated by Western blotting and DNA damage by (32)P-postlabelling, immunostaining and comet assay. The formation of reactive oxygen species (ROS) was quantified by flow cytometry. The role of PM organic fraction versus washed PM on the cell cycle alterations was also examined. Finally, the molecular pathways activated were further examined using specific inhibitors.

RESULTS

Winter PM2.5 induced marked cell cycle alteration already after 3 h of exposure, represented by an increased number of cells (transient arrest) in G2. This effect was associated with an increased phosphorylation of Chk2, while no changes in p53 phosphorylation were observed at this time point. The increase in G2 was followed by a transient arrest in the metaphase/anaphase transition point (10 h), which was associated with the presence of severe mitotic spindle aberrations. The metaphase/anaphase delay was apparently followed by mitotic slippage at 24 h, resulting in an increased number of tetraploid G1 cells and cells with micronuclei (MN), and by apoptosis at 40 h. Winter PM2.5 increased the level of ROS at 2 h and DNA damage (8-oxodG, single- and double stand breaks) was detected after 3 h of exposure. The PM organic fraction caused a similar G2/M arrest and augmented ROS formation, while washed PM had no such effects. DNA adducts were detected after 24 h. Both PM-induced DNA damage and G2 arrest were inhibited by the addition of antioxidants and α-naphthoflavone, suggesting the involvement of ROS and reactive electrophilic metabolites formed via a P450-dependent reaction.

CONCLUSIONS

Milan winter PM2.5 rapidly induces severe cell cycle alterations, resulting in increased frequency of cells with double nuclei and MN. This effect is related to the metabolic activation of PM2.5 organic chemicals, which cause damages to DNA and spindle apparatus.

Gold(III) Tetraarylporphyrin Phosphonate Derivatives as Potential Anticancer Agents

5-[4-(Dialkyoxyphosphorylamino)]phenyl-10,15,20- triphenylporphyrinato gold(III)chlorides have been synthesised and evaluated for their in vitro cytotoxic activity against SMMC-7721 human hepatic and sarcoma 180 mouse cancer cell line panels. 5-[4-(Diisopropoxyphosphorylamino)]phenyl-10,15,20- triphenylporphyrinato gold(III)chloride exhibited significant growth inhibitory properties against sarcoma 180 mouse cancer cells (IC50 value = 2.60 μM) and 5-[4-(dipropoxyphosphorylamino)]phenyl-10,15,20-triphenylporphyrinato gold(III)chloride showed significant growth inhibitory properties against SMMC-7721 human hepatic cancer cells (IC50 value = 5.10 μM).

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.

Carbon nanotubes induce oxidative DNA damage in RAW 264.7 cells

The induction of DNA and chromosome damage following in vitro exposure to carbon nanotubes (CNT) was assessed on the murine macrophage cell line RAW 264.7 by means of the micronucleus (MN) and the comet assays. Exposures to two CNT preparations (single-walled CNT (SWCNT > 90%) and multiwalled CNT (MWCNT > 90%) were performed in increasing mass concentrations (0.01-100 microg/ml). The frequency of micronuclei was significantly increased in cells treated with SWCNT (at doses above 0.1 microg/ml), whereas MWCNT had the same effect at higher concentrations (1 microg/ml) (P < 0.05). The results of the comet assay revealed that the effects of treatment with SWCNT were detectable at all concentrations tested (1-100 microg/ml); oxidized purines increased significantly, whereas pyrimidines showed a significant increase (P < 0.001) only at the highest concentration (100 microg/ml). In cells treated with MWCNT, an increase in DNA migration due to the oxidative damage to purines was observed at a concentration of 1 and 10 microg/ml, whereas pyrimidines showed a significant increase only at the highest mass concentration tested. However, both SWCNT and MWCNT induced a statistically significant cytotoxic effect at the highest concentrations tested (P < 0.001). These findings suggest that both the MN and comet assays can reliably detect small amount of damaged DNA at both chromosome and nuclear levels in RAW 264.7 cells. Moreover, the modified version of the comet assay allows the specific detection of the induction of oxidative damage to DNA, which may be the underlying mechanism involved in the CNT-associated genotoxicity.

Single-walled carbon nanotubes: geno- and cytotoxic effects in lung fibroblast V79 cells

With the development of nanotechnology, there is a tremendous growth of the application of nanomaterials, which increases the risk of human exposure to these nanomaterials through inhalation, ingestion, and dermal penetration. Among different types of nanoparticles, single-walled carbon nanotubes (SWCNT) with extremely small size (1 nm in diameter) exhibit extraordinary properties and offer possibilities to create materials with astounding features. Since the release of nanoparticles in an enclosed environment is of great concern, a study of possible genotoxic effects is important. Our previous data showed that pharyngeal aspiration of SWCNT elicited pulmonary effects in C57BL/6 mice that was promoted by a robust, acute inflammatory reaction with early onset resulting in progressive interstitial fibrogenic response and the formation of granulomas. In the present study, the genotoxic potential of SWCNT was evaluated in vitro. The genotoxic effects of nanoparticles were examined using three different test systems: the comet assay and micronucleus (MN) test in a lung fibroblast (V79) cell line, and the Salmonella gene mutation assay in strains YG1024/YG1029. Cytotoxicity tests showed loss of viability in a concentration- and time-dependent manner after exposure of cells to SWCNT. Results from the comet assay demonstrated the induction of DNA damage after only 3 h of incubation with 96 microg/cm2 of SWCNT. The MN test indicated some but not significant micronucleus induction by SWCNT in the V79 cell line at the highest concentrations tested. With two different strains of Salmonella typhimurium, no mutations were found following SWCNT exposure.

Characterization and biological effect of Buenos Aires urban air particles on mice lungs

Exposure to increased levels of ambient air particulate matter (PM) is associated with increased cardiopulmonary morbidity and mortality. Its association with adverse health effects and the still unclear mechanisms of action are of concern worldwide. Our objective was to analyze air PM from downtown Buenos Aires (UAP-BA), and evaluate its biological impact on normal airways. We studied the inflammatory response to intranasal instillation of UAP-BA in a short-term-exposure mouse model. We analyzed UAP-BA morphology by scanning electron microscopy and characterized particle chemical composition by energy dispersive X-ray analysis and capillary gas chromatography. We evaluated lung changes by histomorphometry and histochemical methods. Regarding size, surface area and distribution, UAP-BA proved to be small spherical ultrafine particles: free, in clusters and associated to a matrix. The particles contained polycyclic aromatic hydrocarbons, polychlorinated biphenyls and almost no metal traces. Histologically, UAP-BA induced the recruitment of phagocytes, a reduction in air spaces, an increase in mucous PAS positive cells and weak incomplete elastic fiber network. Our results demonstrate that UAP-BA causes adverse biological effects on the respiratory tract generating inflammation that, in turn, may cause tissue injury or organ dysfunction and may contribute to the pathogenesis of lung diseases.

Micronuclei induced by airborne particulate matter from Mexico City

Particulate air pollution is an important environmental health risk. In the present study, we have investigated the ability of chemically characterized water and organic-soluble extracts of PM(10) from two different regions of Mexico City to induce micronuclei in a human epithelial cell line. We also evaluated the association between the chemical characteristics of the PM and its genotoxicity. The airborne particulate samples were collected from an industrial and a residential region; a Hi-Vol air sampler was used to collect PM(10) on glass fiber filters. PM mass was determined by gravimetric analysis of the filters. One section of each PM(10) filter was agitated either with deionized water to extract water-soluble compounds or with dichloromethane to prepare organic-soluble compounds. The chemical composition of the extracts was determined by ion and gas chromatography and atomic adsorption spectroscopy. A549-human alveolar epithelial cells were exposed to different concentrations of PM(10) extracts and the cytokinesis blocked micronucleus assay was performed to measure DNA damage. Even though the industrial region had a higher PM concentration, higher amounts of metals and PAHs were found in the residential area. Both industrial and residential extracts induced a significant concentration-related increase in the micronuclei frequency. The PM(10) water-soluble industrial extract induced significantly more micronuclei than the one of the residential region; inversely, the organic residential extract induced more micronuclei than the one from the industrial region. The association between the induction of micronuclei and the chemical components obtained by the comparative analysis of standardized regression coefficients showed that cadmium and PAHs were significantly associated with micronuclei induction. Data indicate that water-soluble metals and the organic-soluble fraction of PM(10) are both important in the production of micronuclei. Effects observed, point to the risk of PM exposure and shows the need of integrative studies.