Impact of after-treatment devices and biofuels on diesel exhausts genotoxicity in A549 cells exposed at air-liquid interface.

Using an air-liquid interface (ALI) device in dynamic conditions, we evaluated the efficiency of fuel after-treatment strategies (diesel oxidation catalysis, DOC, and diesel particulate filter, DPF, devices) and the impact of 7% and 30% rapeseed methyl esters (RME) blending on oxidative stress and genotoxicity induced in A549 lung cells after 3h exposure to whole Diesel exhausts. Oxidative stress was studied using assays of ROS production, glutathione level, catalase and superoxide-dismutase (SOD) activities. No oxidative stress and no clear differences on cytotoxicity patterns between biodiesel and standard Diesel exhausts were found. A weak but significant genotoxicity (8-oxodGuo adducts) and, for standard Diesel only, a DNA damage response (DDR) as evidenced by ƔH2AX foci, remained after DOC+DPF flowing. All together, these data could contribute to the improvement of the after treatment strategies and to health risk assessment of current diesel exhausts.

Comparative mutagenicity and genotoxicity of particles and aerosols emitted by the combustion of standard vs. rapeseed methyl ester supplemented bio-diesel fuels: impact of after treatment devices: oxidation catalyst and particulate filter.

Diesel exhausts are partly responsible for the deleterious effects on human health associated with urban pollution, including cardiovascular diseases, asthma, COPD, and possibly lung cancer. Particulate fraction has been incriminated and thus largely investigated for its genotoxic properties, based on exposure conditions that are, however, not relevant for human risk assessment. In this paper, original and more realistic protocols were used to investigate the hazards induced by exhausts emitted by the combustion of standard (DF0) vs. bio-diesel fuels (DF7 and DF30) and to assess the impact of exhaust treatment devices (DOC and DPF). Mutagenicity and genotoxicity were evaluated for (1) resuspended particles ("off line" exposure that takes into account the bioavailability of adsorbed chemicals) and for (2) the whole aerosols (particles+gas phase components) under continuous flow exposure ("on line" exposure). Native particles displayed mutagenic properties associated with nitroaromatic profiles (YG1041), whereas PAHs did not seem to be involved. After DOC treatment, the mutagenicity of particles was fully abolished. In contrast, the level of particle deposition was low under continuous flow exposure, and the observed mutagenicity in TA98 and TA102 was thus attributable to the gas phase. A bactericidal effect was also observed in TA102 after DOC treatment, and a weak but significant mutagenicity persisted after DPF treatment for bio-diesel fuels. No formation of bulky DNA-adducts was observed on A549 cells exposed to diesel exhaust, even in very drastic conditions (organic extracts corresponding to 500 µg equivalent particule/mL, 48 h exposure). Taken together, these data indicate that the exhausts issued from the bio-diesel fuels supplemented with rapseed methyl ester (RME), and generated by current diesel engines equipped with after treatment devices are less mutagenic than older ones. The residual mutagenicity is linked to the gas phase and could be due to pro-oxydants, mainly for RME-supplemented fuels.

[Toxicological study of emissions resulting from a diesel and a gazoline engine using an organotypic culture of lung slice]. / Etude toxicologique des gaz d'échappement issus de moteurs diesel et essence sur une culture organotypique de tissu pulmonaire.

INTRODUCTION: Many studies were carried out in vivo and/or in vitro for better understanding toxic effects of exhausts or particles emitted by Diesel vehicles. Few studies were interested in Gazoline engines when progress of metrology made it possible to highlight the presence of small particles with a strong capacity of penetration within pulmonary tissue. The aim of this study is to compare the toxic impact of the emissions of Diesel and Gasoline engines of recent technology. MATERIALS AND METHODS: Biological material was constituted by an organotypic rat lung precision slice. It was exposed to a continuous flow exhausts thanks to a preparation and dilutions system of these emissions placed on the line of exhaust. A measurement of the biological markers involved in the process of the lung tissue reaction to the air-contaminants was carried out. RESULTS: With Diesel exhausts, the results showed a stability of the rate of ATP and an increase in enzymatic activities of the antioxydant system (GPx and catalase). Gazoline emissions, as for them, were responsible for a cytotoxic attack of the pulmonary tissue defined by a reduction in the rate of ATP as well as a deterioration of the system of detoxication with reduction in the antioxydant enzymatic activities. CONCLUSION: These results show that toxicological profiles obtained with this system of exposure depends on the engine technology used, highlighting thus the specific response of the model in relation with the type of atmospheres which it is exposed.

Rotating wall vessel as a new in vitro shear stress generation system: application to rat coronary endothelial cell cultures.

In this paper, we describe a simple new design for the application of controlled, top-hat profiled wall shear stress forces in a way that is independent of hydrostatic pressure and oxygen tension, based on a rotating wall vessel system. This system has been applied to the culture of rat coronary endothelial cells obtained with a Langendorff-derived procedure isolation. Endothelial cells are immunopurified on the basis of RECA expression, and conservation of endothelial phenotype has been assessed on the basis of morphology, RECA and von Willebrand factor expressions and diI-Ac-LDL uptake. Shear stress induced by the rotating wall vessel was measured using a mathematical formula specifically designed for this type of model, and its impact on coronary endothelial cells was evaluated. Shear stress produced cell orientation parallel to the flux direction, elevated NO production and decreased monocyte adhesion. Cells were kept viable and functional for at least 4 days under shear. This simple design allows the handling and management of numerous vials in parallel and appears to be suitable for large-scale studies of both the acute and chronic impact of modulation of the physico-chemical environment on endothelial cell physiology and function.