  The molecular responses of macrophages to copper-based nanoparticles have
been investigated via a combination of proteomic and biochemical approaches,
using the RAW264.7 cell line as a model. Both metallic copper and copper oxide
nanoparticles have been tested, with copper ion and zirconium oxide
nanoparticles used as controls. Proteomic analysis highlighted changes in
proteins implicated in oxidative stress responses (superoxide dismutases and
peroxiredoxins), glutathione biosynthesis, the actomyosin cytoskeleton, and
mitochondrial proteins (especially oxidative phosphorylation complex subunits).
Validation studies employing functional analyses showed that the increases in
glutathione biosynthesis and in mitochondrial complexes observed in the
proteomic screen were critical to cell survival upon stress with copper-based
nanoparticles; pharmacological inhibition of these two pathways enhanced cell
vulnerability to copper-based nanoparticles, but not to copper ions.
Furthermore, functional analyses using primary macrophages derived from bone
marrow showed a decrease in reduced glutathione levels, a decrease in the
mitochondrial transmembrane potential, and inhibition of phagocytosis and of
lipopolysaccharide-induced nitric oxide production. However, only a fraction of
these effects could be obtained with copper ions. In conclusion, this study
showed that macrophage functions are significantly altered by copper-based
nanoparticles. Also highlighted are the cellular pathways modulated by cells
for survival and the exemplified cross-toxicities that can occur between
copper-based nanoparticles and pharmacological agents.
