Cellular Response to Diesel Engine Exhaust Particulate Exposures: Impact of Extraction Method and Reactive Oxygen Species as a Biomarker

Oxidative stress induction by diesel engine particulate was investigated. The objectives were: to determine the temporal profile of cell oxidant generation, elucidate engine condition effects on particulate toxicity, and assess filter extraction impact on potency. Calu-3 cells were exposed to particulate from a tier 1 diesel engine, an off-road diesel generator, and a soot generator. Particulate filters were extracted into different solvents, using multiple sonication methods; with reactive oxygen species and cell death biomarkers measured upon exposure. Dose-dependent effects and an effective dose of > 35 Âľg/mL were observed for all particulate types. Greater oxidative potential was positively associated with engine load in the tier 1 system, but tier 3 diesel generator particulate was most potent (> 18 Âľg/mL effective dose). Additionally, phosphate buffer extracted particulate, and sonicator probe use enhanced the oxidative stress response. The methods validated can be applied to larger matrices of diesel particulate exposures, incorporating various emission control technologies, testing cycles, and fuel types.M.A.S