Chemical characterization of fine and ultrafine PM, direct and indirect genotoxicity of PM and their organic extracts on pulmonary cells.

Particulate matter in ambient air constitutes a complex mixture of fine and ultrafine particles composed of various chemical compounds including metals, ions, and organics. A multidisciplinary approach was developed by studying physico-chemical characteristics and mechanisms involved in the toxicity of particulate atmospheric pollution. PM0.3-2.5 and PM2.5 including ultrafine particles were sampled in Dunkerque, a French industrialized seaside city. PM samples were characterized from a chemical and toxicological point of view. Physico-chemical characterization evidenced that PM2.5 comes from several sources: natural ones, such as soil resuspension and marine sea-salt emissions, as well as anthropogenic ones, such as shipping traffic, road traffic, and industrial activities. Human BEAS-2B lung cells were exposed to PM0.3-2.5, or to the Extractable Organic Matter (EOM) of PM0.3-2.5 and PM2.5. These exposures induced several mechanisms of action implied in the genotoxicity, such as oxidative DNA adducts and DNA Damage Response. The toxicity of PM-EOM was higher for the sample including the ultrafine fraction (PM2.5) containing also higher concentrations of polycyclic aromatic hydrocarbons. These results evidenced the major role of organic compounds in the toxicity of PM.

Influence of aging in the modulation of epigenetic biomarkers of carcinogenesis after exposure to air pollution.

BACKGROUND: Classified as carcinogenic to humans by the IARC in 2013, fine air particulate matter (PM2.5) can be inhaled and retained into the lung or reach the systemic circulation. This can cause or exacerbate numerous pathologies to which the elderly are often more sensitive. METHODS: In order to estimate the influence of age on the development of early cellular epigenetic alterations involved in carcinogenesis, peripheral blood mononuclear cells sampled from 90 patients from three age classes (25-30, 50-55 and 75-80 years old) were ex vivo exposed to urban PM2.5. RESULTS: Particles exposure led to variations in telomerase activity and telomeres length in all age groups without any influence of age. Conversely, P16INK4A gene expression increased significantly with age after exposure to PM2.5. Age could enhance MGMT gene expression after exposure to particles, by decreasing the level of promoter methylation in the oldest people. CONCLUSION: Hence, our results demonstrated several tendencies in cells modification depending on age, even if all epigenetic assays were carried out after a limited exposure time allowing only one or two cell cycles. Since lung cancer symptoms appear only at an advanced stage, our results underline the needs for further investigation on the studied biomarkers for early diagnosis of carcinogenesis to improve survival.

Nature of fly ash amendments differently influences oxidative stress alleviation in four forest tree species and metal trace element phytostabilization in aged contaminated soil: A long-term field experiment.

Aided phytostabilization using coal fly ashes (CFAs) is an interesting technique to clean-up polluted soils and valorizing industrial wastes. In this context, our work aims to study the effect of two CFAs: silico-aluminous (CFA1) and sulfo-calcic (CFA2) ones, 10 years after their addition, on the phytostabilization of a highly Cd (cadmium), Pb (lead) and Zn (zinc) contaminated agricultural soil, with four forest tree species: Robinia pseudoacacia, Alnus glutinosa, Acer pseudoplatanus and Salix alba. To assess the effect of CFAs on trees, leaf fatty acid composition, malondialdehyde (MDA), oxidized and reduced glutathione contents ratio (GSSG: GSH), 8-hydroxy-2'-deoxyguanosine (8-OHdG), Peroxidase (PO) and Superoxide dismutase (SOD) activities were examined. Our results showed that CFA amendments decreased the CaCl2-extractable fraction of Cd and Zn from the soil. However, no significant effect was observed on metal trace element (MTE) concentrations in leaves. Fatty acid percentages were only affected by the addition of sulfo-calcic CFA. The most affected species were A. glutinosa and R. pseudoacacia in which C16:0, C18:0 and C18:2 percentages increased significantly whereas the C18:3 decreased. The addition of sulfo-calcic CFA induced the antioxidant systems response in tree leaves. An increase of SOD and POD activities in leaves of trees planted on the CFA2-amended plot was recorded. Conversely, silico-aluminous CFA generated a reduction of lipid and DNA oxidation associated with the absence or low induction of anti-oxidative processes. Our study evidenced oxidative stress alleviation in tree leaves due to CFA amendments. MTE mobility in contaminated soil and their accumulation in leaves differed with the nature of CFA amendments and the selected tree species.

Smoker extracellular vesicles influence status of human bronchial epithelial cells.

Cigarette smoking is a habit that has spread all over the world and is a significant risk factor for many diseases including cardiovascular disease, chronic obstructive pulmonary disease (COPD), asthma and lung cancer. Evaluation and understanding of tobacco health effects are of major interest worldwide and answer to important societal concerns. Identification of new biomarkers of exposure to tobacco smoke potentially implicated in COPD or lung carcinogenesis would allow a better observation of tobacco exposed population, thanks to screening establishment at reversible stages of pathological processes. In this study, we questioned whether cigarette smoking alters miRNA profiles of Extracellular Vesicles (EVs) present in human Broncho Alveolar Lavages (BALs), which could affect surrounding normal bronchial epithelial cells status. To this aim, BALs were carried out on 10 Smokers and 10 Non-Smokers, and EVs were isolated from the supernatants and characterized. We then compared the amount of 10 microRNAs (miRNAs) present in Smokers versus Non-Smokers BAL EVs and performed statistical analysis to discuss the biological significance by the smoking status and to evaluate BAL EV miRNAs as potential biomarkers of tobacco exposure. Finally, we tested the effects of smokers versus non-smokers EVs on human bronchial epithelial cells (BEAS-2B) to compare their influence on the cells status. Our study shows for the first time in human samples that smoking can alter lung EV profile that can influence surrounding bronchial epithelial cells.

Fine and ultrafine atmospheric particulate matter at a multi-influenced urban site: Physicochemical characterization, mutagenicity and cytotoxicity.

Particulate Matter (PM) air pollution is one of the major concerns for environment and health. Understanding the heterogeneity and complexity of fine and ultrafine PM is a fundamental issue notably for the assessment of PM toxicological effects. The aim of this study was to evaluate mutagenicity and cytotoxicity of a multi-influenced urban site PM, with or without the ultrafine fraction. For this purpose, PM2.5-0.3 (PM with aerodynamic diameter ranging from 0.3 to 2.5 µm) and PM2.5 were collected in Dunkerque, a French coastal industrial city and were extensively characterized for their physico-chemical properties, including inorganic and organic species. In order to identify the possible sources of atmospheric pollution, specific criteria like Carbon Preference Index (CPI) and PAH characteristic ratios were investigated. Mutagenicity assays using Ames test with TA98, TA102 and YG1041 Salmonella strains with or without S9 activation were performed on native PM sample and PM organic extracts and water-soluble fractions. BEAS-2B cell viability and cell proliferation were evaluated measuring lactate dehydrogenase release and mitochondrial dehydrogenase activity after exposure to PM and their extracts. Several contributing sources were identified in PM: soil resuspension, marine emissions including sea-salt or shipping, road traffic and industrial activities, mainly related to steelmaking or petro-chemistry. Mutagenicity of PM was evidenced, especially for PM2.5, including ultrafine fraction, in relation to PAHs content and possibly nitro-aromatics compounds. PM induced cytotoxic effects at relatively high doses, while alteration of proliferation with low PM doses could be related to underlying mechanisms such as genotoxicity.

Usefulness of toxicological validation of VOCs catalytic degradation by air-liquid interface exposure system.

Toluene is one of the most used Volatile Organic Compounds (VOCs) in the industry despite its major health impacts. Catalytic oxidation represents an efficient remediation technique in order to reduce its emission directly at the source, but it can release by-products. To complete the classical performance assessment using dedicated analytical chemistry methods, we propose to perform an untargeted toxicological validation on two efficient catalysts. Using biological system allows integrating synergy and antagonism in toxic effects of emitted VOCs and by-products, often described in case of multi-exposure condition. Catalysts Pd/α-Al2O3 and Pd/γ-Al2O3 developed for the oxidation of toluene were both coupled to a Vitrocell® Air-Liquid Interface (ALI) system, for exposure of human A549 lung cells during 1h to toluene or to catalysts exhaust before quantification of xenobiotics metabolizing enzymes. This study validated initially the Vitrocell® as an innovative, direct and dynamic model of ALI exposure in the assessment of the performances of new catalysts, showing the presence of chemically undetected by-products. The comparison of the two catalysts showed then that fewer organic compounds metabolizing genes were induced by Pd/γ-Al2O3 in comparison to Pd/α-Al2O3, suggesting that Pd/γ-Al2O3 is more efficient for toluene total oxidation from a toxicological point of view.

Characterisation and seasonal variations of particles in the atmosphere of rural, urban and industrial areas: Organic compounds.

Atmospheric aerosol samples (PM2.5-0.3, i.e., atmospheric particles ranging from 0.3 to 2.5µm) were collected during two periods: spring-summer 2008 and autumn-winter 2008-2009, using high volume samplers equipped with cascade impactors. Two sites located in the Northern France were compared in this study: a highly industrialised city (Dunkirk) and a rural site (Rubrouck). Physicochemical analysis of particulate matter (PM) was undertaken to propose parameters that could be used to distinguish the various sources and to exhibit seasonal variations but also to provide knowledge of chemical element composition for the interpretation of future toxicological studies. The study showed that PM2.5-0.3 concentration in the atmosphere of the rural area remains stable along the year and was significantly lower than in the urban or industrial ones, for which concentrations increase during winter. High concentrations of polycyclic aromatic hydrocarbons (PAHs), dioxins, furans and dioxin like polychlorinated biphenyls (DL-PCBs), generated by industrial activities, traffic and municipal wastes incineration were detected in the samples. Specific criteria like Carbon Preference Index (CPI) and Combustion PAHs/Total PAHs ratio (CPAHs/TPAHs) were used to identify the possible sources of atmospheric pollution. They revealed that paraffins are mainly emitted by biogenic sources in spring-summer whereas as in the case of PAHs, they have numerous anthropogenic emission sources in autumn-winter (mainly from traffic and domestic heating).

In vitro short-term exposure to air pollution PM2.5-0.3 induced cell cycle alterations and genetic instability in a human lung cell coculture model.

Although its adverse health effects of air pollution particulate matter (PM2.5) are well-documented and often related to oxidative stress and pro-inflammatory response, recent evidence support the role of the remodeling of the airway epithelium involving the regulation of cell death processes. Hence, the overarching goals of the present study were to use an in vitro coculture model, based on human AM and L132 cells to study the possible alteration of TP53-RB gene signaling pathways (i.e. cell cycle phases, gene expression of TP53, BCL2, BAX, P21, CCND1, and RB, and protein concentrations of their active forms), and genetic instability (i.e. LOH and/or MSI) in the PM2.5-0.3-exposed coculture model. PM2.5-0.3 exposure of human AM from the coculture model induced marked cell cycle alterations after 24h, as shown by increased numbers of L132 cells in subG1 and S+G2 cell cycle phases, indicating apoptosis and proliferation. Accordingly, activation of the TP53-RB gene signaling pathways after the coculture model exposure to PM2.5-0.3 was reported in the L132 cells. Exposure of human AM from the coculture model to PM2.5-0.3 resulted in MS alterations in 3p chromosome multiple critical regions in L132 cell population. Hence, in vitro short-term exposure of the coculture model to PM2.5-0.3 induced cell cycle alterations relying on the sequential occurrence of molecular abnormalities from TP53-RB gene signaling pathway activation and genetic instability.

Effects of environmental cadmium and lead exposure on adults neighboring a discharge: Evidences of adverse health effects.

The purpose of the study was to determine Pb and Cd concentrations in humans and to assess the effect of co-exposure to these metals on biomarkers of oxidative stress and nephrotoxicity. Blood and urine levels of Pb and Cd, oxidative stress and urinary renal biomarkers were measured in 77 subjects neighboring a discharge and 52 in the control site. Exposed subjects showed significantly higher levels of lead and cadmium in blood and urine than the controls. Excessive production of reactive oxygen species induced by these metals in exposed subjects conducted to a decrease in antioxidant defense system (GPx, Selenium, GSH) and an increase in lipid peroxidation (MDA). Moreover, changes in markers of nephrotoxicity (high urinary concentrations of total protein, RBP and CC16, as well as GSTα and LDH increased activities) suggested the occurrence of discrete and early signs of impaired renal function for the discharge neighboring population.

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.

Arbuscular mycorrhizal fungal inoculation protects Miscanthus × giganteus against trace element toxicity in a highly metal-contaminated site.

Arbuscular mycorrhizal fungus (AMF)-assisted phytoremediation could constitute an ecological and economic method in polluted soil rehabilitation programs. The aim of this work was to characterize the trace element (TE) phytoremediation potential of mycorrhizal Miscanthus × giganteus. To understand the mechanisms involved in arbuscular mycorrhizal symbiosis tolerance to TE toxicity, the fatty acid compositions and several stress oxidative biomarkers were compared in the roots and leaves of Miscanthus × giganteus cultivated under field conditions in either TE-contaminated or control soils. TEs were accumulated in greater amounts in roots, but the leaves were the organ most affected by TE contamination and were characterized by a strong decrease in fatty acid contents. TE-induced oxidative stress in leaves was confirmed by an increase in the lipid peroxidation biomarker malondialdehyde (MDA). TE contamination decreased the GSSG/GSH ratio in the leaves of exposed plants, while peroxidase (PO) and superoxide dismutase (SOD) activities were increased in leaves and in whole plants, respectively. AMF inoculation also increased root colonization in the presence of TE contamination. The mycorrhizal colonization determined a decrease in SOD activity in the whole plant and PO activities in leaves and induced a significant increase in the fatty acid content in leaves and a decrease in MDA formation in whole plants. These results suggested that mycorrhization is able to confer protection against oxidative stress induced by soil pollution. Our findings suggest that mycorrhizal inoculation could be used as a bioaugmentation technique, facilitating Miscanthus cultivation on highly TE-contaminated soil.

Temporal-spatial variations of the physicochemical characteristics of air pollution Particulate Matter (PM2.5-0.3) and toxicological effects in human bronchial epithelial cells (BEAS-2B).

While the evidence for the health adverse effects of air pollution Particulate Matter (PM) has been growing, there is still uncertainty as to which constituents within PM are most harmful. Hence, to contribute to fulfill this gap of knowledge, some physicochemical characteristics and toxicological endpoints (i.e. cytotoxicity, oxidative damage, cytokine secretion) of PM2.5-0.3 samples produced during two different seasons (i.e. spring/summer or autumn/winter) in three different surroundings (i.e. rural, urban, or industrial) were studied, thereby expecting to differentiate their respective adverse effects in human bronchial epithelial cells (BEAS-2B). Physicochemical characteristics were closely related to respective origins and seasons of the six PM2.5-0.3 samples, highlighting the respective contributions of industrial and heavy motor vehicle traffic sources. Space- and season-dependent differences in cytotoxicity of the six PM2.5-0.3 samples could only be supported by considering both the physicochemical properties and the variance in air PM concentrations. Whatever spaces and seasons, dose- and even time-dependent increases in oxidative damage and cytokine secretion were reported in PM2.5-0.3-exposed BEAS-2B cells. However, the relationship between the chemical composition of each of the six PM2.5-0.3 samples and their oxidative or inflammatory potentials seemed to be very complex. These results supported the role of inorganic, ionic and organic components as exogenous source of Reactive Oxygen Species and, thereafter, cytokine secretion. Nevertheless, one of the most striking observation was that some inorganic, ionic and organic chemical components were preferentially associated with early oxidative events whereas others in the later oxidative damage and/or cytokine secretion. Taken together, these results indicated that PM mass concentration alone might not be able to explain the health outcomes, because PM is chemically nonspecific, and supported growing evidence that PM-size, composition and emission source, together with sampling season, interact in a complex manner to produce PM2.5-0.3-induced human adverse health effects.

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.

Xenobiotic metabolism induction and bulky DNA adducts generated by particulate matter pollution in BEAS-2B cell line: geographical and seasonal influence.

Airborne particulate matter (PM) toxicity is of growing interest as diesel exhaust particles have been classified as carcinogenic to humans. However, PM is a mixture of chemicals, and respective contribution of organic and inorganic fractions to PM toxicity remains unclear. Thus, we analysed the link between chemical composition of PM samples and bulky DNA adduct formation supported by CYP1A1 and 1B1 genes induction and catalytic activities. We used six native PM samples, collected in industrial, rural or urban areas, either during the summer or winter, and carried out our experiments on the human bronchial epithelial cell line BEAS-2B. Cell exposure to PM resulted in CYP1A1 and CYP1B1 genes induction. This was followed by an increase in EROD activity, leading to bulky DNA adduct formation in exposed cells. Bulky DNA adduct intensity was associated to global EROD activity, but this activity was poorly correlated with CYPs mRNA levels. However, EROD activity was correlated with both metal and polycyclic aromatic hydrocarbon (PAH) content. Finally, principal components analysis revealed three clusters for PM chemicals, and suggested synergistic effects of metals and PAHs on bulky DNA adduct levels. This study showed the ability of PM samples from various origins to generate bulky DNA adducts in BEAS-2B cells. This formation was promoted by increased expression and activity of CYPs involved in PAHs activation into reactive metabolites. However, our data highlight that bulky DNA adduct formation is only partly explained by PM content in PAHs, and suggest that inorganic compounds, such as iron, may promote bulky DNA adduct formation by supporting CYP activity.

Traffic-related air pollution. A pilot exposure assessment in Beirut, Lebanon.

Traffic-related volatile organic compounds (VOCs) pollution has frequently been demonstrated to be a serious problem in the developing countries. Benzene and 1,3-butadiene (BD) have been classified as a human carcinogen based on evidence for an increased genotoxic and epigenotoxic effects in both occupational exposure assessment and in vivo/in vitro studies. We have undertaken a biomonitoring of 25 traffic policemen and 23 office policemen in Beirut, through personal air monitoring, assessed by diffusive samplers, as well as through the use of biomarkers of exposure to benzene and BD. Personal benzene, toluene, ethylbenzene, and xylene (BTEX) exposure were quantified by GC-MS/MS, urinary trans, trans-muconic acid (t,t-MA) by HPLC/UV, S-phenyl mercapturic acid (S-PMA), monohydroxy-butenyl mercapturic acid (MHBMA) and dihydroxybutyl mercapturic acid (DHBMA) by ultra-performance liquid chromatography-electrospray tandem mass spectrometry (UPLC/ESI(-)-MS/MS) in MRM (Multiple Reaction Monitoring) mode. We found that individual exposure to benzene in the traffic policemen was higher than that measured in traffic policemen in Prague, in Bologna, in Ioannina and in Bangkok. t,t-MA levels could distinguish between office and traffic policemen. However, median MHBMA levels in traffic policemen were slightly elevated, though not significantly higher than in office policemen. Alternatively, DHBMA concentrations could significantly distinguish between office and traffic policemen and showed a better correlation with personal total BTEX exposure. DHMBA, measured in the post-shift urine samples, correlated with both pre-shift MHMBA and pre-shift DHMBA. Moreover, there was not a marked effect of smoking habits on DHBMA. Taken together, these findings suggested that DHBMA is more suitable than MHBMA as biomarker of exposure to BD in humans. Traffic policemen, who are exposed to benzene and BD at the roadside in central Beirut, are potentially at a higher risk for development of diseases such as cancer than office policemen.

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.

Polycyclic aromatic hydrocarbons within airborne particulate matter (PM(2.5)) produced DNA bulky stable adducts in a human lung cell coculture model.

To extend current knowledge on the underlying mechanisms of air pollution particulate matter (PM(2.5))-induced human lung toxicity, the metabolic activation of polycyclic aromatic hydrocarbons (PAH) within PM(2.5) and PAH-DNA bulky stable adduct patterns in human alveolar macrophage (AM) and/or human lung epithelial L132 cells in mono- and cocultures were studied. In the coculture system, only human AM were exposed to air pollution PM(2.5), unlike L132 cells. Particles, inorganic fraction and positive controls [i.e. TiO(2), thermally desorbed PM (dPM) and benzo[a]pyrene, B[a]P, respectively] were included in the experimental design. Cytochrome P450 (CYP) 1A1 gene expression, CYP1A1 catalytic activity and PAH-DNA bulky stable adducts were studied after 24, 48 and/or 72 h. Relatively low doses of PAH within PM(2.5) induced CYP1A1 gene expression and CYP1A1 catalytic activity in human AM and, thereafter, PAH-DNA bulky stable adduct formation. Adduct spots in PM(2.5) -exposed human AM were higher than those in dPM-exposed ones, thereby showing the incomplete removal of PAH by thermal desorption. PAH within air pollution PM(2.5) induced CYP1A1 gene expression but not CYP1A1 catalytic activity in L132 cells. However, despite the absence of PAH-DNA bulky stable adduct in L132 cells from human AM/L132 cell cocultures exposed to dPM(2.5) or PM(2.5), reliable quantifiable PAH-DNA bulky stable adducts were observed in L132 cells from human AM/L132 cell coculture exposed to B[a]P. Taken together, these results support the exertion of genotoxicity of highly reactive B[a]P-derived metabolites produced within human AM not only in primary target human AM, but also in secondary target L132 cells.

Xenobiotic metabolism and disposition in human lung cell models: comparison with in vivo expression profiles.

Numerous lung cell lines are currently used as in vitro models for pharmacological and toxicological studies. However, no exhaustive report about the metabolic capacities of these models in comparison with those of lung tissues is available. In the present study, we used a high-throughput quantitative real-time reverse transcription-polymerase chain reaction strategy to characterize the expression profiles of 380 genes encoding proteins involved in the metabolism and disposition of xenobiotics in 10 commonly used lung cell lines (A549, H292, H358, H460, H727, Calu-1, 16HBE, 1 HAEO, BEAS-2B, and L-132) and four primary cultures of human bronchial epithelial cells. Expression results were then compared with those previously obtained in human nontumoral and tumoral lung tissues. Our results revealed disparities in gene expression between lung cell lines or when comparing lung cell lines with primary cells or lung tissues. Primary cell cultures displayed the highest similarities with bronchial mucosa in terms of transcript profiling and therefore seem to be the most relevant in vitro model for investigating the metabolism and bioactivation of toxicants and drugs in bronchial epithelium. H292 and BEAS-2B cell lines, which exhibited the highest homology in gene expression pattern with primary cells and the lowest number of dysregulated genes compared with nontumoral lung tissues, could be used as surrogates for toxicological and pharmacological studies. Overall, our study should provide references for researchers to choose the most appropriate in vitro model for analyzing the cellular effects of drugs or airborne toxicants on the airway.

Prooxidant and proinflammatory potency of air pollution particulate matter (PM2.5₋0.3) produced in rural, urban, or industrial surroundings in human bronchial epithelial cells (BEAS-2B).

Compelling evidence indicates that exposure to air pollution particulate matter (PM) affects human health. However, how PM composition interacts with PM-size to cause adverse health effects needs elucidation. In this study, we were also interested in the physicochemical characteristics and toxicological end points of PM2.5₋0.3 samples produced in rural, urban, or industrial surroundings, thereby expecting to differentiate their respective in vitro adverse health effects in human bronchial epithelial cells (BEAS-2B). Physicochemical characteristics of the three PM2.5₋0.3 samples, notably their inorganic and organic components, were closely related to their respective emission sources. Referring also to the dose/response relationships of the three PM2.5₋0.3 samples, the most toxicologically relevant exposure times (i.e., 24, 48, and 72 h) and doses (i.e., 3.75 µg PM/cm² and 15 µg PM/cm²) to use to study the underlying mechanisms of action involved in PM-induced lung toxicity were chosen. Organic chemicals adsorbed on the three PM2.5₋0.3 samples (i.e., polycyclic aromatic hydrocarbons) were able to induce the gene expression of xenobiotic-metabolizing enzymes (i.e., Cytochrome P4501A1 and 1B1, and, to a lesser extent, NADPH-quinone oxidoreductase-1). Moreover, intracellular reactive oxygen species within BEAS-2B cells exposed to the three PM2.5₋0.3 samples induced oxidative damage (i.e., 8-hydroxy-2'-deoxyguanosine formation, malondialdehyde production and/or glutathione status alteration). There were also statistically significant increases of the gene expression and/or protein secretion of inflammatory mediators (i.e., notably IL-6 and IL-8) in BEAS-2B cells after their exposure to the three PM2.5₋0.3 samples. Taken together, the present findings indicated that oxidative damage and inflammatory response preceeded cytotoxicity in air pollution PM2.5₋0.3-exposed BEAS-2B cells and supported the idea that PM-size, composition, and origin could interact in a complex manner to determine the in vitro responsiveness to PM.

Benzo[a]pyrene, aflatoxine B1 and acetaldehyde mutational patterns in TP53 gene using a functional assay: relevance to human cancer aetiology.

Mutations in the TP53 gene are the most common alterations in human tumours. TP53 mutational patterns have sometimes been linked to carcinogen exposure. In hepatocellular carcinoma, a specific G>T transversion on codon 249 is classically described as a fingerprint of aflatoxin B(1) exposure. Likewise G>T transversions in codons 157 and 158 have been related to tobacco exposure in human lung cancers. However, controversies remain about the interpretation of TP53 mutational pattern in tumours as the fingerprint of genotoxin exposure. By using a functional assay, the Functional Analysis of Separated Alleles in Yeast (FASAY), the present study depicts the mutational pattern of TP53 in normal human fibroblasts after in vitro exposure to well-known carcinogens: benzo[a]pyrene, aflatoxin B(1) and acetaldehyde. These in vitro patterns of mutations were then compared to those found in human tumours by using the IARC database of TP53 mutations. The results show that the TP53 mutational patterns found in human tumours can be only partly ascribed to genotoxin exposure. A complex interplay between the functional impact of the mutations on p53 phenotype and the cancer natural history may affect these patterns. However, our results strongly support that genotoxins exposure plays a major role in the aetiology of the considered cancers.