Pre-validation of a reporter gene assay for oxidative stress for the rapid screening of nanobiomaterials.

Engineered nanomaterials have been found to induce oxidative stress. Cellular oxidative stress, in turn, can result in the induction of antioxidant and detoxification enzymes which are controlled by the nuclear erythroid 2-related factor 2 (NRF2) transcription factor. Here, we present the results of a pre-validation study which was conducted within the frame of BIORIMA ("biomaterial risk management") an EU-funded research and innovation project. For this we used an NRF2 specific chemically activated luciferase expression reporter gene assay derived from the human U2OS osteosarcoma cell line to screen for the induction of the NRF2 mediated gene expression following exposure to biomedically relevant nanobiomaterials. Specifically, we investigated Fe3O4-PEG-PLGA nanomaterials while Ag and TiO2 "benchmark" nanomaterials from the Joint Research Center were used as reference materials. The viability of the cells was determined by using the Alamar blue assay. We performed an interlaboratory study involving seven different laboratories to assess the applicability of the NRF2 reporter gene assay for the screening of nanobiomaterials. The latter work was preceded by online tutorials to ensure that the procedures were harmonized across the different participating laboratories. Fe3O4-PEG-PLGA nanomaterials were found to induce very limited NRF2 mediated gene expression, whereas exposure to Ag nanomaterials induced NRF2 mediated gene expression. TiO2 nanomaterials did not induce NRF2 mediated gene expression. The variability in the results obtained by the participating laboratories was small with mean intra-laboratory standard deviation of 0.16 and mean inter laboratory standard deviation of 0.28 across all NRF2 reporter gene assay results. We conclude that the NRF2 reporter gene assay is a suitable assay for the screening of nanobiomaterial-induced oxidative stress responses.

[Air pollution and respiratory diseases: a central role for oxidative stress]. / Pollution atmosphérique et maladies respiratoires: un rôle central pour le stress oxydant.

Epidemiological studies have clearly shown a relationship between respiratory diseases and air pollution. Ozone and ambient particles are the main pollutants contributing to the exacerbation of these pathologies. Their toxicity resides in their ability to generate an oxidative stress. The level of oxidative stress and the specificity of the cellular responses result from complex interactions between pro- and anti-oxidants, leading to differentiated cellular strategies. Hierarchical biological responses: adaptation, inflammation, lesions, can be determined according to the oxidative insult and individual anti-oxidant capacities. A better health risk assessment could be achieved by taking into account the oxidative properties of air pollution especially those of ultrafine particles.