Brief exposure to nanosized and bulk titanium dioxide forms induces subtle changes in human D384 astrocytes

• Published in: Toxicology letters 2016-07, Vol.254, p.8-21
• Main Authors: De Simone, Uliana, Lonati, Davide, Ronchi, Anna, Coccini, Teresa
• Format: Article
• Language: English
• Subjects: Apoptosis - drug effects; Apoptosis Regulatory Proteins - metabolism; Astrocytes - drug effects; Astrocytes - metabolism; Astrocytes - pathology; Blotting, Western; Cell Line, Tumor; Cellular; CNS; Dose-Response Relationship, Drug; Exposure; Fluorescent Antibody Technique; Human; Humans; In vitro; Markets; Mass Spectrometry; Metal Nanoparticles; Microscopy, Fluorescence; Molecular mechanism; Nanostructure; Nanotoxicity; Oxidative Stress - drug effects; Particle Size; Perturbation methods; Reactive Oxygen Species - metabolism; Safety; Signal Transduction - drug effects; Stress concentration; Time Factors; TiO2; Titanium - metabolism; Titanium - toxicity; Titanium dioxide
• ISSN: 0378-4274; 1879-3169
• DOI: 10.1016/j.toxlet.2016.05.006

•TiO2NPs caused subtle effects in human astrocytes D384 cells at not cytotoxic doses.•Oxidative stress and apoptotic mechanisms occurred after low dose exposure to TiO2NP.•Comparatively, similar effects were observed when testing TiO2 bulk.•Cellular checkpoint perturbations were associated with increasing intracellular Ti. Although nanosized-titanium dioxide particles (TiO2NPs)-containing products are constantly placed on the market, little is known about their possible impact on human health, even regarding to CNS effects. In this study, mechanistic pathways, by which TiO2NPs induce cellular damage and death, have been investigated in human (astrocytes-like) D384 cells and comparatively weighed against the effects produced by the bulk counterpart. Cellular signals evaluated by multiple set of in vitro tests after 24h exposure to TiO2NP concentrations (0.5–125μg/ml) were: ROS production, p-p53, p53, p21, Bax, Bcl-2 and caspase 3. TiO2 cellular uptake was also estimated by both light microscopy and ICP-MS. ROS were generated starting at 1.5μg/ml and further increased at the highest concentrations (≥31μg/ml). At the same low concentration, an increased expression of p-p53, p53, p21, Bax, and activated caspase3 were also observed. Parallely, Bcl-2 decreased along with TiO2NP concentration increase. Similar alterations were observed when testing TiO2 bulk: cellular checkpoint perturbations were associated with rising intracellular Ti. The present data demonstrated that low TiO2NP concentrations were capable, after 24h, to induce subtle cellular perturbation in D384 cells after a single cell treatment, supporting the evidence that both oxidative stress and apoptotic mechanisms may occur in this type of CNS cells.