We use cookies on our website. Some are necessary for the operation of the website. You can also allow cookies for statistical purposes. You can adjust the data protection settings or agree to all cookies directly.
Data Protection Declaration
Imprint
Studies on the anti-oxidative responses of lung cells as an endpoint for the assessment of aerosols after exposure at the air-liquid interface
Project
Project code: BfR-ZEBET-08-1328-209
Contract period: 01.11.2007
- 30.09.2011
Purpose of research: Applied research
For the toxicological investigation of substances, which can enter the human body by inhalation, there are so far no accepted alternatives for animal tests. This applies in particular to insoluble nanoparticles. Therefore, new methods must be developed for the evaluation of the toxic potential of nanoparticles in occupational atmospheres, e.g. during the production by nanoparticles, or during the use of nanoparticle-based products, whereby animal test should be avoided as far as possible. In order to achieve this objective, the use of in vitro methods directly at the source of particles is favoured; however, the particle concentrations are frequently low so that the biological effects are not detectable.The long-term goal is, to further develop the in vitro bioassay for the toxicological evaluation of aerosols, which has been developed at Forschungszentrum Karlsruhe. Improvements regarding dose determination and sensitive biological endpoints, which can be measured in an easy way, are expected. Therefore, the understanding of mechanisms of the particle effects on cellular and molecular level must be improved.We recently showed that oxidative stress represents a key event in the cellular response to particles from combustion processes. In consequence, the cells increase their anti-oxidative defences to counteract pro-apoptotic stimuli, e.g. by induction of the enzyme heme oxygenase-1 (HO-1) and by an increase of the cellular glutathione level. The results suggest the involvement of the redox-sensitive transcription factors Nrf2 and AP-1 in the activation of the target genes. However, the exact mechanism is not well understood. The studies will be accomplished first under submerged conditions and later by exposure of the cells at the air-liquid interface.
The operation of the exposure system as well as the generation and measurement of aerosol are accomplished at the Institute for Technical Chemistry of the Forschungszentrum Karlsruhe. The system is continuously improved in particular regarding the deposition efficiency of particles. The study focused on SiO2 nanoparticles (NP) since they were more toxic in RAW264.7 macrophages than TiO2- and Fe2O3-NPs, in particular in the absence of serum. Cell death was mainly caused by necrotic processes. SiO2 NPs induced activation of MAP kinases ERK1/2, p38 und JNK1/2 in dependence of time and dose. While the antioxidative cell response (HO-1, NQO1 und GCLC) was very weak, the inflammatory genes TNFß, COX-2, iNOS, IL-6, Cxcl2, IL-1ß, MCP-1, FOS were significantly enhanced on mRNA level. On protein level however, only small amounts of TNF-ß, COX-2, IL-1ß and IL-6 were detected. Since the antioxidant N-acetyl-cysteine had no effect on all endpoints it was concluded that oxidative stress does not play a role in SiO2 NP-induced cell responses. The observed effects are possibly a result of the particle-induced cytotoxicity. SiO2-NPs were also exposed to A549 epithelial cells as an aerosol and the effects were compared to a submerged exposure. A549 cells were less sensitive to the aerosol compared to submerged exposure at similar doses.
Section overview
Subjects
- Animal health
Framework programme
Funding programme
Excutive institution
BfR - Centre for Documentation and Evaluation of Alternatives to Animal Experiments (BfR - ZEBET)
