Cellular effects of nanosilver in human macrophages: Uptake, oxidative stress, lipid alterations and functional impairment
Dr. Andrea Haase, Federal Institute for Risk Assement (BfR), Berlin
Silver nanoparticles (SNP) belong to the most commercialized nanoparticles. Here we monitored the biological effects of SNP of different sizes (20 nm, 40 nm) and coatings (citrate, peptide) in human macrophages in vitro. We used THP-1 derived macrophages as a cellular model. The cellular uptake was analyzed by confocal Raman microscopy, TEM or Laser postionization secondary neutral mass spectrometry (Laser-SNMS). Cellular responses upon SNP treatment were studied by time-of-flight secondary ion mass spectrometry (TOF-SIMS) and several biological endpoints were evaluated, i.e., cytotoxicity, protein carbonyl formation and induction of heme oxygenase-1 (HO-1).
Toxicity of SNP was dependent on exposure time, dose and particle coating. Nanogold proved mainly inert. All kinds of nanoparticles were efficiently taken up by cells. Aggregates and single particles could be detected throughout whole cells, including nuclei and lysosomes. With TOF-SIMS and Laser-SNMS we visualized intracellular SNP and detected significant changes in the membrane lipid pattern indicating oxidative stress and fluidity changes. We measured strong induction of HO-1 and formation of protein carbonyls with different time patterns. Each type of SNP induced a characteristic carbonylation pattern as resolved by 2D gel electrophoresis. SNP but not nanogold significantly affected the phagocytic activity of macrophages. Some of the particle-mediated effects proved reversible depending on the exposure times and doses applied.
Conclusion: SNP exert adverse effects in human macrophages already at subcytotoxic doses. Different kinds of SNP induce distinguishable effects at cellular and biochemical levels.
Haase A., Arlinghaus H.F., Tentschert J., Jungnickel H., Graf P., Mantion A., Draude F., Galla S., Plendl J., Goetz M.E., Mašić A., Meier W.P., Thünemann A.F., Taubert A. and Luch A. (2011) Application of Laser-SNMS/TOF-SIMS in nanotoxicology: Visualisation of nanosilver in human macrophages and cellular responses, ACS Nano 5, 3059-3068.