Co-assessment of cell cycle and micronucleus frequencies demonstrates the influence of serum on the in vitro genotoxic response to amorphous monodisperse silica nanoparticles of varying sizes

Serum proteins have been shown to modulate the cytotoxic and genotoxic responses to nanomaterials. The aim was to investigate the influence of serum on the induction of micronuclei (MN) by nanoparticles (NPs) of different sizes. Therefore, A549 human lung carcinoma cells and amorphous monodisperse silica nanoparticles (SNPs) were used as models. Assessment of the cell viability, cell cycle changes and induction of MN by SNPs ranging from 12 to 174 nm was performed in presence or absence of serum, applying the in vitro flow cytometry-based MN assay. Here, it has been demonstrated that serum has an influence on these end points, with a lower cell viability in absence of serum compared with the presence of serum. Further, cell cycle changes, specifically, G(1) and S-phase arrest, were observed in absence of serum for four out of six SNPs tested. A size-dependent MN induction was observed: larger SNPs being more active in absence of serum. In addition, the serum influence was characterised by a size-dependency for cytotoxic and genotoxic effects, with a higher influence of serum for smaller particles. The data indicate that the in vitro micronucleus assay in presence and absence of serum could be advised for hazard assessment because it demonstrates a higher sensitivity in serum-free conditions than in conditions with serum. However, this recommendation applies only if the cell line used is able to proliferate under serum-free conditions because cell division is a prerequisite for MN expressio

Lung exposure to nanoparticles modulates an asthmatic response in a mouse model

The aim of this study was to investigate the modulation of an asthmatic response by titanium dioxide (TiO₂) or gold (Au) nanoparticles (NPs) in a murine model of diisocyanate-induced asthma. On days 1 and 8, BALB/c mice received 0.3% toluene diisocyanate (TDI) or the vehicle acetone-olive oil (AOO) on the dorsum of both ears (20 μL). On day 14, the mice were oropharyngeally dosed with 40 μL of a NP suspension (0.4 mg·mL⁻¹ (∼0.8 mg·kg⁻¹) TiO₂ or Au). 1 day later (day 15), the mice received an oropharyngeal challenge with 0.01% TDI (20 μL). On day 16, airway hyperreactivity (AHR), bronchoalveolar lavage (BAL) cell and cytokine analysis, lung histology, and total serum immunoglobulin E were assessed. NP exposure in sensitised mice led to a two- (TiO₂) or three-fold (Au) increase in AHR, and a three- (TiO₂) or five-fold (Au) increase in BAL total cell counts, mainly comprising neutrophils and macrophages. The NPs taken up by BAL macrophages were identified by energy dispersive X-ray spectroscopy. Histological analysis revealed increased oedema, epithelial damage and inflammation. In conclusion, these results show that a low, intrapulmonary doses of TiO₂ or Au NPs can aggravate pulmonary inflammation and AHR in a mouse model of diisocyanate-induced asthma.status: publishe