Ordinary Gasoline Emissions Induce a Toxic Response in Bronchial Cells Grown at Air-Liquid Interface.

Gasoline engine emissions have been classified as possibly carcinogenic to humans and represent a significant health risk. In this study, we used MucilAir™, a three-dimensional (3D) model of the human airway, and BEAS-2B, cells originating from the human bronchial epithelium, grown at the air-liquid interface to assess the toxicity of ordinary gasoline exhaust produced by a direct injection spark ignition engine. The transepithelial electrical resistance (TEER), production of mucin, and lactate dehydrogenase (LDH) and adenylate kinase (AK) activities were analyzed after one day and five days of exposure. The induction of double-stranded DNA breaks was measured by the detection of histone H2AX phosphorylation. Next-generation sequencing was used to analyze the modulation of expression of the relevant 370 genes. The exposure to gasoline emissions affected the integrity, as well as LDH and AK leakage in the 3D model, particularly after longer exposure periods. Mucin production was mostly decreased with the exception of longer BEAS-2B treatment, for which a significant increase was detected. DNA damage was detected after five days of exposure in the 3D model, but not in BEAS-2B cells. The expression of CYP1A1 and GSTA3 was modulated in MucilAir™ tissues after 5 days of treatment. In BEAS-2B cells, the expression of 39 mRNAs was affected after short exposure, most of them were upregulated. The five days of exposure modulated the expression of 11 genes in this cell line. In conclusion, the ordinary gasoline emissions induced a toxic response in MucilAir™. In BEAS-2B cells, the biological response was less pronounced, mostly limited to gene expression changes.

The Biological Effects of Complete Gasoline Engine Emissions Exposure in a 3D Human Airway Model (MucilAirTM) and in Human Bronchial Epithelial Cells (BEAS-2B).

The biological effects induced by complete engine emissions in a 3D model of the human airway (MucilAirTM) and in human bronchial epithelial cells (BEAS-2B) grown at the air-liquid interface were compared. The cells were exposed for one or five days to emissions generated by a Euro 5 direct injection spark ignition engine. The general condition of the cells was assessed by the measurement of transepithelial electrical resistance and mucin production. The cytotoxic effects were evaluated by adenylate kinase (AK) and lactate dehydrogenase (LDH) activity. Phosphorylation of histone H2AX was used to detect double-stranded DNA breaks. The expression of the selected 370 relevant genes was analyzed using next-generation sequencing. The exposure had minimal effects on integrity and AK leakage in both cell models. LDH activity and mucin production in BEAS-2B cells significantly increased after longer exposures; DNA breaks were also detected. The exposure affected CYP1A1 and HSPA5 expression in MucilAirTM. There were no effects of this kind observed in BEAS-2B cells; in this system gene expression was rather affected by the time of treatment. The type of cell model was the most important factor modulating gene expression. In summary, the biological effects of complete emissions exposure were weak. In the specific conditions used in this study, the effects observed in BEAS-2B cells were induced by the exposure protocol rather than by emissions and thus this cell line seems to be less suitable for analyses of longer treatment than the 3D model.

Comparative Analysis of Toxic Responses of Organic Extracts from Diesel and Selected Alternative Fuels Engine Emissions in Human Lung BEAS-2B Cells.

This study used toxicogenomics to identify the complex biological response of human lung BEAS-2B cells treated with organic components of particulate matter in the exhaust of a diesel engine. First, we characterized particles from standard diesel (B0), biodiesel (methylesters of rapeseed oil) in its neat form (B100) and 30% by volume blend with diesel fuel (B30), and neat hydrotreated vegetable oil (NEXBTL100). The concentration of polycyclic aromatic hydrocarbons (PAHs) and their derivatives in organic extracts was the lowest for NEXBTL100 and higher for biodiesel. We further analyzed global gene expression changes in BEAS-2B cells following 4 h and 24 h treatment with extracts. The concentrations of 50 µg extract/mL induced a similar molecular response. The common processes induced after 4 h treatment included antioxidant defense, metabolism of xenobiotics and lipids, suppression of pro-apoptotic stimuli, or induction of plasminogen activating cascade; 24 h treatment affected fewer processes, particularly those involved in detoxification of xenobiotics, including PAHs. The majority of distinctively deregulated genes detected after both 4 h and 24 h treatment were induced by NEXBTL100; the deregulated genes included, e.g., those involved in antioxidant defense and cell cycle regulation and proliferation. B100 extract, with the highest PAH concentrations, additionally affected several cell cycle regulatory genes and p38 signaling.

The impact of extractable organic matter from gasoline and alternative fuel emissions on bronchial cell models (BEAS-2B, MucilAir™).

Air pollution caused by road traffic has an unfavorable impact on the environment and also on human health. It has previously been shown, that complete gasoline emissions lead to toxic effects in cell models originating from human airways. Here we focused on extractable organic matter (EOM) from particulate matter, collected from gasoline emissions from fuels with different ethanol content. We performed cytotoxicity evaluation, quantification of mucin and extracellular reactive oxygen species (ROS) production, DNA breaks detection, and selected gene deregulation analysis, after one and five days of exposure of human bronchial epithelial model (BEAS-2B) and a 3D model of the human airway (MucilAir™). Our data suggest that the longer exposure had more pronounced effects on the parameters of cytotoxicity and mucin production, while the impacts on ROS generation and DNA integrity were limited. In both cell models the expression of CYP1A1 was induced, regardless of the exposure period or EOM tested. Several other genes, including FMO2, IL1A, or TNF, were deregulated depending on the exposure time. In conclusion, ethanol content in the fuels did not significantly impact the toxicity of EOM. Biological effects were mostly linked to xenobiotics metabolism and inflammatory response. BEAS-2B cells were more sensitive to the treatment.

Transcription profiles in BEAS-2B cells exposed to organic extracts from particulate emissions produced by a port-fuel injection vehicle, fueled with conventional fossil gasoline and gasoline-ethanol blend.

Emissions from road traffic are among the major contributors to air pollution worldwide and represent a serious environmental health risk. Although traffic-related pollution has been most commonly associated with diesel engines, increasing evidence suggests that gasoline engines also produce a considerable amount of potentially hazardous particulate matter (PM). The primary objective of this study was to compare the intrinsic toxic properties of the organic components of PM, generated by a conventional gasoline engine fueled with neat gasoline (E0), or gasoline-ethanol blend (15 % ethanol, v/v, E15). Our results showed that while E15 has produced, compared to gasoline and per kg of fuel, comparable particle mass (µg PM/kg fuel) and slightly more particles by number, the organic extract from the particulate matter produced by E15 contained a larger amount of harmful polycyclic aromatic hydrocarbons (PAHs), as determined by the chemical analysis. To examine the toxicity, we monitored genome-wide gene expression changes in human lung BEAS-2B cells, exposed for 4 h and 24 h to a subtoxic dose of each PM extract. After 4 h exposure, numerous dysregulated genes and processes such as oxidative stress, lipid and steroid metabolism, PPARα signaling and immune response, were found to be common for both extract treatments. On the other hand, 24 h exposure resulted in more distinctive gene expression patterns. Although we identified several common modulated processes indicating the metabolism of PAHs and activation of aryl hydrocarbon receptor (AhR), E15 specifically dysregulated a variety of other genes and pathways related to cancer promotion and progression. Overall, our findings suggest that the ethanol addition to gasoline changed the intrinsic properties of PM emissions and increased the PAH content in PM organic extract, thus contributing to a more extensive toxic response particularly after 24 h exposure in BEAS-2B cells.

Markers of lipid oxidation and inflammation in bronchial cells exposed to complete gasoline emissions and their organic extracts.

Road traffic emissions consist of gaseous components, particles of various sizes, and chemical compounds that are bound to them. Exposure to vehicle emissions is implicated in the etiology of inflammatory respiratory disorders. We investigated the inflammation-related markers in human bronchial epithelial cells (BEAS-2B) and a 3D model of the human airways (MucilAir™), after exposure to complete emissions and extractable organic matter (EOM) from particles generated by ordinary gasoline (E5), and a gasoline-ethanol blend (E20; ethanol content 20% v/v). The production of 22 lipid oxidation products (derivatives of linoleic and arachidonic acid, AA) and 45 inflammatory molecules (cytokines, chemokines, growth factors) was assessed after days 1 and 5 of exposure, using LC-MS/MS and a multiplex immunoassay, respectively. The response observed in MucilAir™ exposed to E5 gasoline emissions, characterized by elevated levels of pro-inflammatory AA metabolites (prostaglandins) and inflammatory markers, was the most pronounced. E20 EOM exposure was associated with increased levels of AA metabolites with anti-inflammatory effects in this cell model. The exposure of BEAS-2B cells to complete emissions reduced lipid oxidation, while E20 EOM tended to increase concentrations of AA metabolite and chemokine production; the impacts on other inflammatory markers were limited. In summary, complete E5 emission exposure of MucilAir™ induces the processes associated with the pro-inflammatory response. This observation highlights the potential negative health impacts of ordinary gasoline, while the effects of alternative fuel are relatively weak.

Content of metals in emissions from gasoline, diesel, and alternative mixed biofuels.

The use of alternative fuels or biofuel blends could be a way to reduce the environmental burden of increasing traffic. The aim of this study was to compare emissions from conventional fuels and alternative biofuels for diesel and spark-ignition engines under comparable conditions, i.e., using the World Harmonized Transient Cycle for a heavy-duty diesel engine and the Artemis CADC driving cycle for automobiles powered by gasoline and alternative fuels. Total contents of Ba, Ce, Cd, Cr, Cu, Fe, Mn, Ni, Pb, V, and Zn were determined in emissions, fuels, and lubricating oils. In addition, the bioaccessibility of metals in emissions was also assessed by extraction in water and in simulated lung fluid (Gamble's solution). Total particulate mass emissions, expressed per kilogram of fuel, and total contents of metals were higher for the diesel engine than for spark-ignition engines. The highest metal contents in emissions from diesel and gasoline fuels were found for Fe, Zn, and Cu. Fe and Cu in emissions from diesel and spark-ignition engines declined with the addition of bio-components in fuels. However, there was no significant decrease in the contents of other metals in emissions from biofuels. The highest degrees of bioaccessibility were observed for Ba, Zn, Cd, and V in emissions from diesel and biodiesel (according to their solubility in water). On the basis of this study, the use of biodiesel (especially methylesters of rapeseed oil) can be recommended to reduce the total mass of particulate and metal emissions from diesel engines.

On-road and laboratory emissions of NO, NO2, NH3, N2O and CH4 from late-model EU light utility vehicles: Comparison of diesel and CNG.

Exhaust emissions of eight Euro 6 light duty vehicles - two station wagons and six vans - half powered by diesel fuel and half by compressed natural gas (CNG) were examined using both chassis dynamometer and on-road testing. A portable on-board FTIR analyzer was used to measure concentrations of reactive nitrogen compounds - NO, NO2 and ammonia, of CO, formaldehyde, acetaldehyde and greenhouse gases CO2, methane and N2O. Exhaust flow was inferred from engine control unit data. Total emissions per cycle were compared and found to be in good agreement with laboratory measurements of NOX, CO and CO2 during dynamometer tests. On diesel engines, mean NOX emissions were 136-1070mg/km in the laboratory and 537-615mg/km on the road, in many cases nearly an order of magnitude higher compared to the numerical value of the Euro 6 limit. Mean N2O emissions were 3-19mg/km and were equivalent to several g/km CO2. The measurements suggest that NOX and N2O emissions from late-model European light utility vehicles with diesel engines are non-negligible and should be continuously assessed and scrutinized. High variances in NOX emissions among the tested diesel vehicles suggest that large number of vehicles should be tested to offer at least some insights about distribution of fleet emissions among vehicles. CNG engines exhibited relatively low emissions of NOX (12-186mg/km) and NH3 (10-24mg/km), while mean emissions of methane were 18-45mg/km, under 1g/km CO2 equivalent, and N2O, CO, formaldehyde and acetaldehyde were negligible. The combination of a relatively clean-burning fuel, modern engine technology and a three-way catalyst has resulted in relatively low emissions under the wide variety of operating conditions encountered during the tests. The on-board FTIR has proven to be a useful instrument capable of covering, with the exception of total hydrocarbons, essentially all gaseous pollutants of interest.

Transcriptional response to organic compounds from diverse gasoline and biogasoline fuel emissions in human lung cells.

Modern vehicles equipped with Gasoline Direct Injection (GDI) engine have emerged as an important source of particulate emissions potentially harmful to human health. We collected and characterized gasoline exhaust particles (GEPs) produced by neat gasoline fuel (E0) and its blends with 15% ethanol (E15), 25% n-butanol (n-But25) and 25% isobutanol (i-But25). To study the toxic effects of organic compounds extracted from GEPs, we analyzed gene expression profiles in human lung BEAS-2B cells. Despite the lowest GEP mass, n-But25 extract contained the highest concentration of polycyclic aromatic hydrocarbons (PAHs), while i-But25 extract the lowest. Gene expression analysis identified activation of the DNA damage response and other subsequent events (cell cycle arrest, modulation of extracellular matrix, cell adhesion, inhibition of cholesterol biosynthesis) following 4 h exposure to all GEP extracts. The i-But25 extract induced the most distinctive gene expression pattern particularly after 24 h exposure. Whereas E0, E15 and n-But25 extract treatments resulted in persistent stress signaling including DNA damage response, MAPK signaling, oxidative stress, metabolism of PAHs or pro-inflammatory response, i-But25 induced changes related to the metabolism of the cellular nutrients required for cell recovery. Our results indicate that i-But25 extract possessed the weakest genotoxic potency possibly due to the low PAH content.

DNA Damage Potential of Engine Emissions Measured In Vitro by Micronucleus Test in Human Bronchial Epithelial Cells.

Internal combustion engine emissions belong among the major anthropogenic sources of air pollution in urban areas. According to the International Agency for Research on Cancer, there is sufficient evidence of the carcinogenicity of diesel exhaust in human beings. Although alternative fuels, mainly biodiesel, have recently become popular, little is still known about the genotoxicity of emissions from these fuels. We analysed DNA damage expressed as the frequency of micronuclei (MN) in human bronchial epithelial cells (BEAS-2B), induced by extractable organic matter (EOM; tested concentrations: 1, 10 and 25 µg/ml) obtained from particle emissions from various blends of biodiesel with diesel fuels (including neat diesel fuel (B0), a blend of 70% B0 and 30% biodiesel (B30) and neat biodiesel (B100)). We also tested the effect of selected diesel exhaust organic/genotoxic components [benzo[a]pyrene (B[a]P) concentrations: 25, 100 and 200 µM; 1-nitropyrene (1-NP) concentrations: 1, 5 and 10 µM; 3-nitrobenzanthrone (3-NBA) concentrations: 1, 5 and 50 µM]. The cells were treated with the compounds for 28 and 48 hr. Our results showed that most of the tested compounds (except for the 25 µM B[a]P, 28-hr treatment) significantly increased MN frequency. The genotoxicity of EOMs from the engine emissions of diesel and biodiesel engines was comparable. Both nitro-PAH compounds demonstrated higher genotoxic potential in comparison with B[a]P. Considering our results and due to increasing popularity of alternative fuels, it is prudent that the potential genotoxic effects of various fuels are investigated across engine technologies and operating conditions in a relevant model system.