Activation of the inflammasome by amorphous silica and TiO₂ nanoparticles in murine dendritic cells

Abstract

Nanomaterials are increasingly used in various food applications. In particular, nanoparticulate amorphous SiO₂ is already contained, e.g., in spices. Since intestinal dendritic cells (DC) could be critical targets for ingested particles, we compared the in vitro effects of amorphous silica nanoparticles with fine crystalline silica, and micron-sized with nano-sized TiO₂ particles on DC. TiO₂- and SiO₂-nanoparticles, as well as crystalline silica led to an upregulation of MHC-II, CD80, and CD86 on DC. Furthermore, these particles activated the inflammasome, leading to significant IL-1β-secretion in wild-type (WT) but not Caspase-1- or NLRP3-deficient mice. Silica nanoparticles and crystalline silica induced apoptosis, while TiO₂ nanoparticles led to enhanced production of reactive oxygen species (ROS). Since amorphous silica and TiO₂ nanoparticles had strong effects on the activation-status of DC, we suggest that nanoparticles, used as food additives, should be intensively studied in vitro and in vivo, to ensure their safety for the consumer.

Keywords::

• Nanoparticles
• amorphous silica
• TiO₂
• NLRP3
• dendritic cells

Acknowledgements

This study was financially supported by grants from the German Research. Council (Deutsche Forschungsgemeinschaft – Graduate College GK 1427 (to I.F. and R.P.F.S.), SFB 704 (to I.F. and V.H.), and FOR 729 (to I.F.). We are grateful to Heike Weighardt, Catrin Albrecht, and Jason Cline for discussion and help on the manuscript.

Declaration of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.