  The technological and economic benefits of engineered nanomaterials may be
offset by their adverse effects on living organisms. One of the highly produced
nanomaterials under such scrutiny is amorphous silica nanoparticles, which are
known to have an appreciable, although reversible, inflammatory potential. This
is due to their selective toxicity toward macrophages, and it is thus important
to study the cellular responses of this cell type to silica nanoparticles to
better understand the direct or indirect adverse effects of nanosilica. We have
here studied the responses of the RAW264.7 murine macrophage cells and of the
control MPC11 plasma cells to subtoxic concentrations of nanosilica, using a
combination of pro-teomic and targeted approaches. This allowed us to document
alterations in the cellular cytoskeleton, in the phagocytic capacity of the
cells as well as their ability to respond to bacterial stimuli. More
surprisingly, silica nanoparticles also induce a greater sensitivity of
macrophages to DNA alkylating agents, such as styrene oxide, even at doses
which do not induce any appreciable cell death.
