Oxidative potential of particulate matter 2.5 as predictive indicator of cellular stress

International audienceParticulate air pollution being recognized to be responsible for short and long term health effects, regulations for particulate matter with an aerodynamic diameter less than 2.5 (PM2.5) are more and more restrictive. PM2.5 regulation is based on mass without taking into account PM2.5 composition that drives toxicity. Measurement of the oxidative potential (OP) of PM could be an additional PM indicator that would encompass the PM components involved in oxidative stress, the main mechanism of PM toxicity. We compared different methods to evaluate the intrinsic oxidative potential of PM2.5 sampled in Paris and their ability to reflect the oxidative and inflammatory response in bronchial epithelial cells used as relevant target organ cells. The dithiothreitol depletion assay, the antioxidant (ascorbic acid and glutathione) depletion assay (OPAO), the plasmid scission assay and the dichlorofluorescein (DCFH) oxidation assay used to characterize the OP of PM2.5 (10-100 mu g/mL) provided positive results of different magnitude with all the PM2.5 samples used with significant correlation with different metals such as Cu and Zn as well as total polyarotnatic hydrocarbons and the soluble organic fraction. The OPAO assay showed the best correlation with the production of intracellular reactive oxygen species by NCI -H292 cell line assessed by DCFH oxidation and with the expression of anti -oxidant genes (superoxide dismutase 2, heme-oxygenase-1) as well as the proinflammatory response (Interleukin 6) when exposed from 1 to 10 mu g/cm(2). The OPAO assay appears as the most prone to predict the biological effect driven by PM2.5 and related to oxidative stress. (C) 2017 Elsevier Ltd. All rights reserved

Involvement of oxidative stress and calcium signaling in airborne particulate matter - induced damages in human pulmonary artery endothelial cells

International audienceRecent studies have revealed that particulate matter (PM) exert deleterious effects on vascular function. Pulmonary artery endothelial cells (HPAEC), which are involved in the vasomotricity regulation, can be a direct target of inhaled particles. Modifications in calcium homeostasis and oxidative stress are critical events involved in the physiopathology of vascular diseases. The objectives of this study were to assess the effects of PM2.5 on oxidative stress and calcium signaling in HPAEC. Different endpoints were studied, (i) intrinsic and intracellular production of reactive oxygen species (ROS) by the H2DCF-DA probe, (ii) intrinsic, intracellular and mitochondrial production of superoxide anion (O2radical dot−) by electronic paramagnetic resonance spectroscopy and MitoSOX probe, (iii) reactive nitrosative species (RNS) production by Griess reaction, and (vi) calcium signaling by the Fluo-4 probe. In acellular conditions, PM2.5 leads to an intrinsic free radical production (ROS, O2radical dot−) and a 4 h-exposure to PM2.5 (5–15 μg/cm2), induced, in HPAEC, an increase of RNS, of global ROS and of cytoplasmic and mitochondrial O2radical dot− levels. The basal intracellular calcium ion level [Ca2 +]i was also increased after 4 h-exposure to PM2.5 and a pre-treatment with superoxide dismutase and catalase significantly reduced this response. This study provides evidence that the alteration of intracellular calcium homeostasis induced by PM2.5 is closely correlated to an increase of oxidative stress