Assessment of the Influence of Crystalline Form on Cyto-Genotoxic and Inflammatory Effects Induced by TiO2 Nanoparticles on Human Bronchial and Alveolar Cells

Titanium dioxide nanoparticles (TiO(2)NPs) are increasingly used in consumer products, industrial and medical applications, raising concerns on their potential toxicity. The available in vitro and in vivo studies on these NPs show controversial results. Crystalline structure is the physicochemical characteristic that seems to influence mainly TiO(2)NPs toxicity, so its effect needs to be further studied. We aimed to study whether and how crystalline form influences potential cyto-genotoxic and inflammatory effects induced by two commercial TiO(2)NPs (TiO2-A, mainly anatase; TiO2-B, mainly rutile) in human alveolar A549 and bronchial BEAS-2B cells exposed to 1-40 mu g/mL. Cell viability (WST-1), membrane damage (LDH release), IL-6, IL-8 and TNF-alpha release (ELISA) and direct/oxidative DNA damage (fpg-comet assay) were evaluated. Physicochemical characterization included analysis of crystalline form (TEM and XRD), specific surface area (BET), agglomeration (DLS) and Z-potential (ELS). Our results show that TiO2-A NPs induce in BEAS-2B cytotoxicity and a slight inflammation and in A549 slight oxidative effects, whereas TiO2-B NPs induce genotoxic/oxidative effects in both cell lines, revealing different toxicity mechanisms for the two tested NPs. In conclusion, our study confirms the influence of crystalline form on cellular response, also demonstrating the suitability of our in vitro model to screen early TiO(2)NPs effects.

Automated summary

The study found that TiO2-A NPs induced cytotoxicity and slight inflammation in BEAS-2B cells, and slight oxidative effects in A549 cells, while TiO2-B NPs induced genotoxic/oxidative effects in both cell lines, revealing different toxicity mechanisms for the two tested NPs. The influence of crystalline form on cellular response was confirmed, demonstrating the suitability of the in vitro model to screen early TiO(2)NPs effects.