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

Integrative transcriptomic and protein analysis of human bronchial BEAS-2B exposed to seasonal urban particulate matter

BACKGROUND

Exposure to particulate matter (PM) is associated with various health effects. Physico-chemical properties influence the toxicological impact of PM, nonetheless the mechanisms underlying PM-induced effects are not completely understood.

OBJECTIVES

Human bronchial epithelial cells were used to analyse the pathways activated after exposure to summer and winter urban PM and to identify possible markers of exposure.

METHODS

BEAS-2B cells were exposed for 24 h to 10 μg/cm(2) of winter PM2.5 (wPM) and summer PM10 (sPM) sampled in Milan. A microarray technology was used to profile the cells gene expression. Genes and microRNAs were analyzed by bioinformatics technique to identify pathways involved in cellular responses. Selected genes and pathways were validated at protein level (western blot, membrane protein arrays and ELISA).

RESULTS

The molecular networks activated by the two PM evidenced a correlation among oxidative stress, inflammation and DNA damage responses. sPM induced the release of pro-inflammatory mediators, although miR-146a and genes related to inflammation resulted up-regulated by both PM. Moreover both PM affected a set of genes, proteins and miRNAs related to antioxidant responses, cancer development, extracellular matrix remodeling and cytoskeleton organization, while miR-29c, implicated in epigenetic modification, resulted up-regulated only by wPM. sPM effects may be related to biological and inorganic components, while wPM apparently related to the high content of organic compounds.

CONCLUSIONS

These results may be helpful for the individuation of biomarkers for PM exposure, linked to the specific PM physico-chemical properties.

Comparison between ultrafine and fine particulate matter collected in Lebanon: Chemical characterization, in vitro cytotoxic effects and metabolizing enzymes gene expression in human bronchial epithelial cells

During the last few years, the induction of toxicological mechanisms by atmospheric ultrafine particles (UFP) has become one of the most studied topics in toxicology and a subject of huge debates. Fine particles (FP) and UFP collected at urban and rural sites in Lebanon were studied for their chemical composition and toxicological effects. UFP were found more enriched in trace elements, secondary inorganic ions, total carbon and organic compounds than FP. For toxicological analysis, BEAS-2B cells were exposed for 24, 48 and 72 h to increasing concentrations of FP, water-UFP suspension (UFPw) and UFP organic extract (UFPorg). Our findings showed that UFP caused earlier alterations of mitochondrial metabolism and membrane integrity from the lowest concentrations. Moreover, a significant induction of CYP1A1, CYP1B1 and AhRR genes expression was showed after cells exposure to UFPorg and to a lesser extent to UFPw and FP samples.

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.

Induction of c-Jun by air particulate matter (PM₁₀) of Mexico city: Participation of polycyclic aromatic hydrocarbons

The carcinogenic potential of urban particulate matter (PM) has been partly attributed to polycyclic aromatic hydrocarbons (PAHs) content, which activates the aryl hydrocarbon receptor (AhR). Here we report the effect of PM with an aerodynamic size of 10 μm (PM10) on the induction of AhR pathway in A549 cells, evaluating its downstream targets CYP1B1, IL-6, IL-8 and c-Jun. Significant increases in CYP1B1 protein and enzyme activity; IL-6 and IL-8 secretion and c-Jun protein were found in response to PM10. The formation of PAH-DNA adducts was also detected. The involvement of AhR pathway was confirmed with Resveratrol as AhR antagonist, which reversed CYP1B1 and c-Jun induction. Nevertheless, in IL-6 and IL-8 secretion, the Resveratrol was ineffective, suggesting an effect independent of this pathway. Considering the role of c-Jun in oncogenesis, its induction by PM may be contributing to its carcinogenic potential through induction of AhR pathway by PAHs present in PM10.

A new method and tool for detection and quantification of PM oxidative potential

Airborne particulate matter (PM) contains several quinones, which are able to generate reactive oxygen species impacting on cell viability. A method able to detect and quantify PM oxidative potential, based on the cytochrome c (cyt-c) reduction by means of superoxide anion produced through quinones redox cycling in the presence of reducing agents, is here described. Tris(2-carboxyethyl)phosphine resulted to be the most efficient reducing agent among the ones tested. The procedure included rapid particles extraction, followed by two alternative analytical methods, a spectrophotometric assay based on the initial rate of cyt-c reduction at 550 nm, and an amperometric assay, based on self-assembled monolayers modified gold electrodes. The smallest amount of PM needed to obtain an evaluable signal is 2 μg. The described procedure may represent a starting point to develop devices for PM measurements in polluted atmospheric environments.

Genotoxic and epigenotoxic effects of fine particulate matter from rural and urban sites in Lebanon on human bronchial epithelial cells

Assessment of air pollution by particulate matter (PM) is strongly required in Lebanon in the absence of an air quality law including updated air quality standards. Using two different PM2.5-0.3 samples collected at an urban and a rural site, we examined genotoxic/epigenotoxic effects of PM exposure within a human bronchial epithelial cell line (BEAS-2B). Inorganic and organic contents evidence the major contribution of traffic and generating sets in the PM2.5-0.3 composition. Urban PM2.5-0.3 sample increased the phosphorylation of H2AX, the telomerase activity and the miR-21 up-regulation in BEAS-2B cells in a dose-dependent manner. Furthermore, urban PM2.5-0.3 induced a significant increase in CYP1A1, CYP1B1 and AhRR genes expression. The variable concentrations of transition metals and organic compounds detected in the collected PM2.5-0.3 samples might be the active agents leading to a cumulative DNA damage, critical for carcinogenesis.

Toxicity of atmospheric particle-bound PAHs: an environmental perspective

Atmospheric polycyclic aromatic hydrocarbons (PAHs) are environmental pollutants that represent a risk not only to humans, but to all living organisms. High-molecular weight PAHs are more toxic than lighter relatives, and also have a higher tendency to bind onto air particles (i.e., particle matter, PM). PM is a major constituent of air pollution. Adequate assessment of the biological impact of PM requires the analysis, not only of the effects on human health, but also on the environment. Since the aquatic systems work as a natural sink to these air pollutants, assessing the effects of particle-bound PAHs on aquatic organisms may further characterize its potential aquatic toxicity, also providing simple and low-cost alternative assays to investigate PM biological effects in vivo. We review the current scientific literature, addressing the atmospheric PAHs fate, transformation and deposition, pertinent particle-bound PAHs toxicity data, and the potential aquatic toxic burden. Conceptual and experimental procedures that could improve future investigations and risk assessments are also considered.

Mechanisms linked to differences in the mutagenic potential of 1,3-dinitropyrene and 1,8-dinitropyrene

This study explores and characterizes the toxicity of two closely related carcinogenic dinitro-pyrenes (DNPs), 1,3-DNP and 1,8-DNP, in human bronchial epithelial BEAS-2B cells and mouse hepatoma Hepa1c1c7 cells. Neither 1,3-DNP nor 1,8-DNP (3–30 μM) induced cell death in BEAS-2B cells. In Hepa1c1c7 cells only 1,3-DNP (10–30 μM) induced a mixture of apoptotic and necrotic cell death after 24 h. Both compounds increased the level of reactive oxygen species (ROS) in BEAS-2B as measured by CM-H₂DCFDA-fluorescence. A corresponding increase in oxidative damage to DNA was revealed by the formamidopyrimidine-DNA glycosylase (fpg)-modified comet assay. Without fpg, DNP-induced DNA damage detected by the comet assay was only found in Hepa1c1c7 cells. Only 1,8-DNP formed DNA adduct measured by ³²P-postlabelling. In Hepa1c1c cells, 1,8-DNP induced phosphorylation of H2AX (γH2AX) and p53 at a lower concentration than 1,3-DNP and there was no direct correlation between DNA damage/DNA damage response (DR) and induced cytotoxicity. On the other hand, 1,3-DNP-induced apoptosis was inhibited by pifithrin-α, an inhibitor of p53 transcriptional activity. Furthermore, 1,3-DNP triggered an unfolded protein response (UPR), as measured by an increased expression of CHOP, ATF4 and XBP1. Thus, other types of damage possibly linked to endoplasmic reticulum (ER)-stress and/or UPR could be involved in the induced apoptosis. Our results suggest that the stronger carcinogenic potency of 1,8-DNP compared to 1,3-DNP is linked to its higher genotoxic effects. This in combination with its lower potency to induce cell death may increase the probability of causing mutations.

Ultrastructural Changes in Cultured Rat Alveolar Macrophage Cells Induced by Fine Particulate Matter

Numerous studies have reported the association between fine particle matter (PM) and lung diseases. Alveolar macrophages (AM) are the key lung cells with strong capability of eliminating external particle pollutant. Therefore the prevention of AM from apoptosis induced by fine PM is vital for clinical treatment of increased pulmonary diseases. This study aims to investigate the ultrastructural changes in cultured AM induced by fine PM, which can directly reflect the effect of fine PM on AM apoptosis. In addition, Standard Reference Material for fine PM (SRM 2786) was used in current study due to its relative uniform composition. The results in this study suggested that SRM 2786 induced morphology changes in AM in a dose-dependent manner by transmission electron microscope observation, including nuclear fragmentation, chromatin aggregation, increased numbers of lysosomes and so forth. Consequently, this study provides reliable evidence for us to further investigate the apoptotic mechanism of AM induced by fine PM treatment in the future.

DNA damage caused by inorganic particulate matter on Raji and HepG2 cell lines exposed to ultraviolet radiation

Epidemiological studies have correlated exposure to ultraviolet-irradiated particulate matter with cardiovascular, respiratory, and lung diseases. This study investigated the DNA damage induced by two major inorganic particulate matter compounds found in diesel exhaust, ammonium nitrate and ammonium sulfate, on Burkitt's lymphoma (Raji) and hepatocellular carcinoma (HepG2) cell lines. We found a dose-dependent positive correlation of accumulated DNA damage at concentrations of ammonium nitrate (25 μg/ml, 50 μg/ml, 100 μg/ml, 200 μg/ml, 400 μg/ml) with ultraviolet exposure (250 J/m(2), 400 J/m(2), 600 J/m(2), 850 J/m(2)), as measured by the comet assay in both cell lines. There was a significant difference between the treated ammonium nitrate samples and negative control samples in Raji and HepG2 cells (p<0.001). Apoptosis was shown in Raji and HepG2 cells when exposed to high concentrations of ammonium nitrate (200 μg/ml and 400 μg/ml) for 1h in samples without ultraviolet exposure, as assessed by the comet assay. However, the level of apoptosis greatly diminished after ultraviolet exposure at these concentrations. Over a 24h period, at intervals of 1, 4, 8, 12, 18, and 24h, we also observed that ammonium nitrate decreased viability in Raji and HepG2 cell lines and inhibited cell growth. Ammonium sulfate-induced DNA damage was minimal in both cell lines, but there remained a significant difference (p<0.05) between the ultraviolet radiation treated and negative control samples. These results indicate that the inorganic particulate compound, ammonium nitrate, induced DNA strand breaks at all concentrations, and indications of apoptosis at high concentrations in Raji and HepG2 cells, with ultraviolet radiation preventing apoptosis at high concentrations. We hypothesize that ultraviolet radiation may inhibit an essential cellular mechanism, possibly involving p53, thereby explaining this phenomenon. Further studies are necessary to characterize the roles of apoptosis inhibition induced by DNA damage caused by inorganic particulate matter.

Cytotoxic response in human lung epithelial cells and ion characteristics of urban-air particles from Torino, a northern Italian city

Recently, much attention has been devoted to urban air pollution because epidemiological studies have reported health impacts related to particulate matter (PM). PM10 and PM2.5 were collected during different seasons in Torino, a northern Italian city, and were characterised by inorganic chemical species (secondary particulates and bio-available iron). The biological effects of aqueous and organic solvent PM extracts on human epithelial lung A549 were evaluated, and the effects on cell proliferation and lactate dehydrogenase (LDH) release were assayed. The average PM10 concentration during the sampling period was 47.9 ± 18.0 μg/m(3); the secondary particles accounted for 49 % ± 9 % of the PM10 total mass, and the bio-available iron concentration was 0.067 ± 0.045 μg/m(3). The PM2.5/PM10 ratio in Torino ranged from 0.47 to 0.90 and was higher in cold months than in warm months. The PM10 and PM2.5 extracts inhibited cell proliferation and induced LDH release in a dose-dependent manner with a seasonal trend. The PM10 extract had a stronger effect on LDH release, whereas the PM2.5 extract more strongly inhibited cell proliferation. No significant differences were observed in the effects induced by the two extracts, and no significant correlations were found between the biological effects and the PM components evaluated in this study, thus emphasising the importance of the entire mixture in inducing a cytotoxic response.

Proinflammatory effects and oxidative stress within human bronchial epithelial cells exposed to atmospheric particulate matter (PM(2.5) and PM(>2.5)) collected from Cotonou, Benin

After particulate matter (PM) collection in Cotonou (Benin), a complete physicochemical characterization of PM2.5 and PM>2.5 was led. Then, their adverse health effects were evaluated by using in vitro culture of human lung cells. BEAS-2B (bronchial epithelial cells) were intoxicated during short-term exposure at increasing PM concentrations (1.5-96 μg/cm(2)) to determine global cytotoxicity. Hence, cells were exposed to 3 and 12 μg/cm(2) to investigate the potential biological imbalance generated by PM toxicity. Our findings showed the ability of both PM to induce oxidative stress and to cause inflammatory cytokines/chemokines gene expression and secretion. Furthermore, PM were able to induce gene expression of enzymes involved in the xenobiotic metabolism pathway. Strong correlations between gene expression of metabolizing enzymes, proinflammatory responses and cell cycle alteration were found, as well as between proinflammatory responses and cell viability. Stress oxidant parameters were highly correlated with expression and protein secretion of inflammatory mediators.

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.

Satellite-based PM concentrations and their application to COPD in Cleveland, OH

A hybrid approach is proposed to estimate exposure to fine particulate matter (PM(2.5)) at a given location and time. This approach builds on satellite-based aerosol optical depth (AOD), air pollution data from sparsely distributed Environmental Protection Agency (EPA) sites and local time-space Kriging, an optimal interpolation technique. Given the daily global coverage of AOD data, we can develop daily estimate of air quality at any given location and time. This can assure unprecedented spatial coverage, needed for air quality surveillance and management and epidemiological studies. In this paper, we developed an empirical relationship between the 2 km AOD and PM(2.5) data from EPA sites. Extrapolating this relationship to the study domain resulted in 2.3 million predictions of PM(2.5) between 2000 and 2009 in Cleveland Metropolitan Statistical Area (MSA). We have developed local time-space Kriging to compute exposure at a given location and time using the predicted PM(2.5). Daily estimates of PM(2.5) were developed for Cleveland MSA between 2000 and 2009 at 2.5 km spatial resolution; 1.7 million (∼79.8%) of 2.13 million predictions required for multiyear and geographic domain were robust. In the epidemiological application of the hybrid approach, admissions for an acute exacerbation of chronic obstructive pulmonary disease (AECOPD) was examined with respect to time-space lagged PM(2.5) exposure. Our analysis suggests that the risk of AECOPD increases 2.3% with a unit increase in PM(2.5) exposure within 9 days and 0.05° (∼5 km) distance lags. In the aggregated analysis, the exposed groups (who experienced exposure to PM(2.5) >15.4 μg/m(3)) were 54% more likely to be admitted for AECOPD than the reference group. The hybrid approach offers greater spatiotemporal coverage and reliable characterization of ambient concentration than conventional in situ monitoring-based approaches. Thus, this approach can potentially reduce exposure misclassification errors in the conventional air pollution epidemiology studies.

Recent advances in particulate matter and nanoparticle toxicology: a review of the in vivo and in vitro studies

Epidemiological and clinical studies have linked exposure to particulate matter (PM) to adverse health effects, which may be registered as increased mortality and morbidity from various cardiopulmonary diseases. Despite the evidence relating PM to health effects, the physiological, cellular, and molecular mechanisms causing such effects are still not fully characterized. Two main approaches are used to elucidate the mechanisms of toxicity. One is the use of in vivo experimental models, where various effects of PM on respiratory, cardiovascular, and nervous systems can be evaluated. To more closely examine the molecular and cellular mechanisms behind the different physiological effects, the use of various in vitro models has proven to be valuable. In the present review, we discuss the current advances on the toxicology of particulate matter and nanoparticles based on these techniques.

Cytotoxic effects of incense particles in relation to oxidative stress, the cell cycle and F-actin assembly

Epidemiological studies have suggested that combustion-derived smoke, such as that produced during incense burning, is a deleterious air pollutant. It is capable of initiating oxidative stress and mutation; however, the related apoptotic processes remain unclear. In order to elucidate the biological mechanisms of reactive oxygen species (ROS)-induced respiratory toxicology, alveolar epithelial A549 cells were exposed to incense particulate matter (PM), with and without antioxidant N-acetyl-l-cysteine (NAC). The cross-linking associations between oxidative capacity, cell cycle events, actin cytoskeletal dynamics and intracellular calcium signals were investigated. An incense PM suspension caused significant oxidative stress in A549 cells, as shown by inhibition of the cell cycle at G1 and G2/M check-points, and the induction of apoptosis at Sub-G1. At the same time, alterations in the F-actin filamentous assemblies were observed. The levels of intracellular Ca(2+) were increased after incense PM exposure. Antioxidant NAC treatment revealed that oxidative stress and F-actin remodelling was significantly mitigated. This suggests that ROS accumulation could alter cell cycle regulation and anomalous remodelling of the cortical cytoskeleton that allowed impaired cells to enter into apoptosis. This study has elucidated the integral patho-physiological interactions of incense PM and the potential mechanisms for the development of ROS-driven respiratory impairment.

Inflammation-related effects of diesel engine exhaust particles: studies on lung cells in vitro

Diesel exhaust and its particles (DEP) have been under scrutiny for health effects in humans. In the development of these effects inflammation is regarded as a key process. Overall, in vitro studies report similar DEP-induced changes in markers of inflammation, including cytokines and chemokines, as studies in vivo. In vitro studies suggest that soluble extracts of DEP have the greatest impact on the expression and release of proinflammatory markers. Main DEP mediators of effects have still not been identified and are difficult to find, as fuel and engine technology developments lead to continuously altered characteristics of emissions. Involved mechanisms remain somewhat unclear. DEP extracts appear to comprise components that are able to activate various membrane and cytosolic receptors. Through interactions with receptors, ion channels, and phosphorylation enzymes, molecules in the particle extract will trigger various cell signaling pathways that may lead to the release of inflammatory markers directly or indirectly by causing cell death. In vitro studies represent a fast and convenient system which may have implications for technology development. Furthermore, knowledge regarding how particles elicit their effects may contribute to understanding of DEP-induced health effects in vivo, with possible implications for identifying susceptible groups of people and effect biomarkers.

Wood smoke particles from different combustion phases induce similar pro-inflammatory effects in a co-culture of monocyte and pneumocyte cell lines

BACKGROUND

Exposure to particulate matter (PM) has been linked to several adverse cardiopulmonary effects, probably via biological mechanisms involving inflammation. The pro-inflammatory potential of PM depends on the particles' physical and chemical characteristics, which again depend on the emitting source. Wood combustion is a major source of ambient air pollution in Northern countries during the winter season. The overall aim of this study was therefore to investigate cellular responses to wood smoke particles (WSPs) collected from different phases of the combustion cycle, and from combustion at different temperatures.

RESULTS

WSPs from different phases of the combustion cycle induced very similar effects on pro-inflammatory mediator release, cytotoxicity and cell number, whereas WSPs from medium-temperature combustion were more cytotoxic than WSPs from high-temperature incomplete combustion. Furthermore, comparisons of effects induced by native WSPs with the corresponding organic extracts and washed particles revealed that the organic fraction was the most important determinant for the WSP-induced effects. However, the responses induced by the organic fraction could generally not be linked to the content of the measured polycyclic aromatic hydrocarbons (PAHs), suggesting that also other organic compounds were involved.

CONCLUSION

The toxicity of WSPs seems to a large extent to be determined by stove type and combustion conditions, rather than the phase of the combustion cycle. Notably, this toxicity seems to strongly depend on the organic fraction, and it is probably associated with organic components other than the commonly measured unsubstituted PAHs.

Wood smoke particles from different combustion phases induce similar pro-inflammatory effects in a co-culture of monocyte and pneumocyte cell lines

BACKGROUND

Exposure to particulate matter (PM) has been linked to several adverse cardiopulmonary effects, probably via biological mechanisms involving inflammation. The pro-inflammatory potential of PM depends on the particles' physical and chemical characteristics, which again depend on the emitting source. Wood combustion is a major source of ambient air pollution in Northern countries during the winter season. The overall aim of this study was therefore to investigate cellular responses to wood smoke particles (WSPs) collected from different phases of the combustion cycle, and from combustion at different temperatures.

RESULTS

WSPs from different phases of the combustion cycle induced very similar effects on pro-inflammatory mediator release, cytotoxicity and cell number, whereas WSPs from medium-temperature combustion were more cytotoxic than WSPs from high-temperature incomplete combustion. Furthermore, comparisons of effects induced by native WSPs with the corresponding organic extracts and washed particles revealed that the organic fraction was the most important determinant for the WSP-induced effects. However, the responses induced by the organic fraction could generally not be linked to the content of the measured polycyclic aromatic hydrocarbons (PAHs), suggesting that also other organic compounds were involved.

CONCLUSION

The toxicity of WSPs seems to a large extent to be determined by stove type and combustion conditions, rather than the phase of the combustion cycle. Notably, this toxicity seems to strongly depend on the organic fraction, and it is probably associated with organic components other than the commonly measured unsubstituted PAHs.

Season linked responses to fine and quasi-ultrafine Milan PM in cultured cells

Exposure to urbane airborne particulate matter (PM) is related to the onset and exacerbation of cardiovascular and respiratory diseases. The fine (PM1), and quasi-ultrafine (PM0.4) Milan particles collected during different seasons have been characterised and the biological effects on human epithelial lung A549, monocytes THP-1 cells and their co-culture, evaluated and compared with the results obtained on the PM10 and PM2.5 fractions. Chemical composition and transmission electron microscopy (TEM) analysis of PM0.4 showed that this fraction was very similar to PM1 for biological responses and dimension. All the winter fractions increased within 1h the level of reactive oxygen species (ROS), while only summer PM2.5 had this effect on A549 cells. The phosphorylation of H2AX (γH2AX), a marker of double strand DNA breaks (DSBs), was increased by all the winter fractions on A549 and THP-1 cells while summer PM samples did not induced this effect. PM0.4 and PM1 biological effects are partly similar and related to the season of sampling, with effects on ROS and DNA damage induced only by winter PM fractions. The winter PM damaging effect on DNA correlates with the presence of organic compounds.

The effect of curcumin on human bronchial epithelial cells exposed to fine particulate matter: a predictive analysis

Fine particulate matter (PM_2.5) has been associated in humans with inflammation, oxidative stress and cancer. Studies had shown that curcumin could potentially inhibit these effects; however, there had been no in vivo or in vitro reports about the effects of curcumin on organisms exposed to PM_2.5. This predictive study explored the possible biological functions and pathways involved in the mechanism of curcumin inhibition of the hazardous effects of PM_2.5. For predictive analysis, microarray data were used to investigate the effect of PM_2.5 on human bronchial epithelial cells (HBEC), and human target proteins of curcumin were retrieved from PubChem. Two protein-protein interaction (PPI) networks were established based upon differential genes and target proteins, respectively, and the common network of these two networks was found. Functional and pathway analysis of the common network was performed using the Ingenuity Pathways Analysis (IPA) software. The results suggested that the predictive effects of curcumin on HBEC exposed to PM_2.5 were involved in bio-functions, including inflammatory response of airway, cancerogenesis, and apoptosis, and in pathways such as cancer, glucocorticoid receptor signaling, and NF-kappaB signaling. This study predicted for the first time that curcumin could be a potential therapeutic agent for protecting the human airway from the hazardous effects of PM_2.5.

Gene expression profiling and pathway analysis of human bronchial epithelial cells exposed to airborne particulate matter collected from Saudi Arabia

Epidemiological studies have established a positive correlation between human mortality and increased concentration of airborne particulate matters (PM). However, the mechanisms underlying PM related human diseases, as well as the molecules and pathways mediating the cellular response to PM, are not fully understood. This study aims to investigate the global gene expression changes in human cells exposed to PM(10) and to identify genes and pathways that may contribute to PM related adverse health effects. Human bronchial epithelial cells were exposed to PM(10) collected from Saudi Arabia for 1 or 4 days, and whole transcript expression was profiled using the GeneChip human gene 1.0 ST array. A total of 140 and 230 genes were identified that significantly changed more than 1.5 fold after PM(10) exposure for 1 or 4 days, respectively. Ingenuity Pathway Analysis revealed that different exposure durations triggered distinct pathways. Genes involved in NRF2-mediated response to oxidative stress were up-regulated after 1 day exposure. In contrast, cells exposed for 4 days exhibited significant changes in genes related to cholesterol and lipid synthesis pathways. These observed changes in cellular oxidative stress and lipid synthesis might contribute to PM related respiratory and cardiovascular disease.

Chemical characterization and source apportionment of fine and coarse particulate matter inside the refectory of Santa Maria Delle Grazie Church, home of Leonardo Da Vinci's "Last Supper"

The association between exposure to indoor particulate matter (PM) and damage to cultural assets has been of primary relevance to museum conservators. PM-induced damage to the "Last Supper" painting, one of Leonardo da Vinci's most famous artworks, has been a major concern, given the location of this masterpiece inside a refectory in the city center of Milan, one of Europe's most polluted cities. To assess this risk, a one-year sampling campaign was conducted at indoor and outdoor sites of the painting's location, where time-integrated fine and coarse PM (PM(2.5) and PM(2.5-10)) samples were simultaneously collected. Findings showed that PM(2.5) and PM(2.5-10) concentrations were reduced indoors by 88 and 94% on a yearly average basis, respectively. This large reduction is mainly attributed to the efficacy of the deployed ventilation system in removing particles. Furthermore, PM(2.5) dominated indoor particle levels, with organic matter as the most abundant species. Next, the chemical mass balance model was applied to apportion primary and secondary sources to monthly indoor fine organic carbon (OC) and PM mass. Results revealed that gasoline vehicles, urban soil, and wood-smoke only contributed to an annual average of 11.2 ± 3.7% of OC mass. Tracers for these major sources had minimal infiltration factors. On the other hand, fatty acids and squalane had high indoor-to-outdoor concentration ratios with fatty acids showing a good correlation with indoor OC, implying a common indoor source.