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Precision-cut rat lung slices in organotypic culture, placed in a biphasic air/liquid system, are used for this study. This model allows to realize pathological and histochemical studies as well as cell and molecular biology investigations. Slices are exposed to a continuous flow of diluted diesel exhausts, with a pO2 regulated at 20% in order to avoid hypoxia-induced effects. The exposure system allows to study concomitantly five exhaust concentrations coming from the same diesel engine, and also to evaluate the impact of particulate matter using a filter placed on the exposition vials. Precision lung slices are exposed for three or six hours to a whole or filtered diesel engine exhaust.

Organotypic cultures of precision-cut rat lung slices are exposed three hours to 5 dilutions of a continuous exhaust flow. The exhausts from three fuelings are tested (filtered and not): gazole, gazole/RME mixture (70 % / 30%) and RME. Different parameters are assessed: ATP and GSH (cell viability), TNFα production (proinflammatory response) and nucleosomes (apoptosis). After exposure, the ATP level is only modified by the highest concentrations of gazole/RME or RME exhausts (filtered and not); the GSH level is decreased for each of the concentrated filtered exhausts. Moreover, only the whole gazole exhaust leads to a modification of TNFα production. At last, the whole gazole exhaust leads to an increase of slice nucleosome level in a dose-dependent way; RME supplementation or filtration significantly attenuates this effect.

Recent improvement in exhaust after-treatment technologies allows particle removal up to 95% with traps and NOx removal up to 40% with reduction catalyst from diesel exhausts. The efficiency of the technology is mainly based on the rate of regulated pollutant emission reduction but very few information is available in term of health hazard potential which may be related to interactions with several of the hundreds of chemical species present under different phases (liquid, gas, solid). It is therefore necessary to develop useful tools to evaluate the global toxicity of Diesel exhaust. A model of bi-compartimental gas/liquid organotypic culture of lung tissue has been specifically developed and used for continuous in vitro exposure to the exhaust gas of a direct injection 1.9 l turbo-charged engine. Regulated emissions (CO, HC, NOx and particles) were measured in raw exhaust.