title: Mimicking exposures to acute and lifetime concentrations of inhaled silver nanoparticles by two different in vitro approaches.
abstract: In the emerging market of nano-sized products, silver nanoparticles (Ag NPs) are widely used due to their antimicrobial properties. Human interaction with Ag NPs can occur through the lung, skin, gastrointestinal tract, and bloodstream. However, the inhalation of Ag NP aerosols is a primary concern. To study the possible effects of inhaled Ag NPs, an in vitro triple cell co-culture model of the human alveolar/airway barrier (A549 epithelial cells, human peripheral blood monocyte derived dendritic and macrophage cells) together with an air-liquid interface cell exposure (ALICE) system was used in order to reflect a real-life exposure scenario. Cells were exposed at the air-liquid interface (ALI) to 0.03, 0.3, and 3 µg Ag/cm(2) of Ag NPs (diameter 100 nm; coated with polyvinylpyrrolidone: PVP). Ag NPs were found to be highly aggregated within ALI exposed cells with no impairment of cell morphology. Furthermore, a significant increase in release of cytotoxic (LDH), oxidative stress (SOD-1, HMOX-1) or pro-inflammatory markers (TNF-α, IL-8) was absent. As a comparison, cells were exposed to Ag NPs in submerged conditions to 10, 20, and 30 µg Ag/mL. The deposited dose per surface area was estimated by using a dosimetry model (ISDD) to directly compare submerged vs ALI exposure concentrations after 4 and 24 h. Unlike ALI exposures, the two highest concentrations under submerged conditions promoted a cytotoxic and pro-inflammatory response after 24 h. Interestingly, when cell cultures were co-incubated with lipopolysaccharide (LPS), no synergistic inflammatory effects were observed. By using two different exposure scenarios it has been shown that the ALI as well as the suspension conditions for the lower concentrations after 4 h, reflecting real-life concentrations of an acute 24 h exposure, did not induce any adverse effects in a complex 3D model mimicking the human alveolar/airway barrier. However, the highest concentrations used in the ALI setup, as well as all concentrations under submerged conditions after 24 h, reflecting more of a chronic lifetime exposure concentration, showed cytotoxic as well as pro-inflammatory effects. In conclusion, more studies need to address long-term and chronic Ag NP exposure effects.
authors.affiliation: Adolphe Merkle Institute, BioNanomaterials, University of Fribourg, Rte de l'Ancienne Papeterie, CP 209, 1723 Marly, Switzerland.
authors.forename: Fabian
authors.initials: F
authors.lastname: Herzog
authors.affiliation: Inorganic Chemistry and Center for Nanointegration Duisburg-Essen (CeNIDE), University of Duisburg-Essen, Universitaetsstrasse 5-7, 45141 Essen, Germany.
authors.forename: Kateryna
authors.initials: K
authors.lastname: Loza
authors.affiliation: Adolphe Merkle Institute, BioNanomaterials, University of Fribourg, Rte de l'Ancienne Papeterie, CP 209, 1723 Marly, Switzerland.
authors.forename: Sandor
authors.initials: S
authors.lastname: Balog
authors.affiliation: Adolphe Merkle Institute, BioNanomaterials, University of Fribourg, Rte de l'Ancienne Papeterie, CP 209, 1723 Marly, Switzerland.
authors.forename: Martin J D
authors.initials: MJ
authors.lastname: Clift
authors.affiliation: Inorganic Chemistry and Center for Nanointegration Duisburg-Essen (CeNIDE), University of Duisburg-Essen, Universitaetsstrasse 5-7, 45141 Essen, Germany.
authors.forename: Matthias
authors.initials: M
authors.lastname: Epple
authors.affiliation: Institute of Anatomy, University of Bern, Baltzerstrasse 2, 3012 Bern, Switzerland.
authors.forename: Peter
authors.initials: P
authors.lastname: Gehr
authors.affiliation: Adolphe Merkle Institute, BioNanomaterials, University of Fribourg, Rte de l'Ancienne Papeterie, CP 209, 1723 Marly, Switzerland ; Department of Chemistry, University of Fribourg, Chemin du Musée 9, 1700 Fribourg, Switzerland.
authors.forename: Alke
authors.initials: A
authors.lastname: Petri-Fink
authors.affiliation: Adolphe Merkle Institute, BioNanomaterials, University of Fribourg, Rte de l'Ancienne Papeterie, CP 209, 1723 Marly, Switzerland ; Respiratory Medicine, Department of Clinical Research, Inselspital University Hospital, University of Bern, Murtenstrasse 50, 3008 Bern, Switzerland.
authors.forename: Barbara
authors.initials: B
authors.lastname: Rothen-Rutishauser
keywords: air–liquid exposure; dosimetry; lung cells in vitro; silver nanoparticles; toxicity