Exposure of silver-nanoparticles and silver-ions to lung cells in vitro at the air-liquid interface

Abstract

BackgroundDue to its antibacterial properties, silver (Ag) has been used in more consumer products than any other nanomaterial so far. Despite the promising advantages posed by using Ag-nanoparticles (NPs), their interaction with mammalian systems is currently not fully understood. An exposure route via inhalation is of primary concern for humans in an occupational setting. Aim of this study was therefore to investigate the potential adverse effects of aerosolised Ag-NPs using a human epithelial airway barrier model composed of A549, monocyte derived macrophage and dendritic cells cultured in vitro at the air-liquid interface. Cell cultures were exposed to 20 nm citrate-coated Ag-NPs with a deposition of 30 and 278 ng/cm2 respectively and incubated for 4 h and 24 h. To elucidate whether any effects of Ag-NPs are due to ionic effects, Ag-Nitrate (AgNO3) solutions were aerosolised at the same molecular mass concentrations.ResultsAgglomerates of Ag-NPs were detected at 24 h post exposure in vesicular structures inside cells but the cellular integrity was not impaired upon Ag-NP exposures. Minimal cytotoxicity, by measuring the release of lactate dehydrogenase, could only be detected following a higher concentrated AgNO3-solution. A release of pro-inflammatory markers TNF-α and IL-8 was neither observed upon Ag-NP and AgNO3 exposures as well as was not affected when cells were pre-stimulated with lipopolysaccharide (LPS). Also, an induction of mRNA expression of TNF-α and IL-8, could only be observed for the highest AgNO3 concentration alone or even significantly increased when pre-stimulated with LPS after 4 h. However, this effect disappeared after 24 h. Furthermore, oxidative stress markers (HMOX-1, SOD-1) were expressed after 4 h in a concentration dependent manner following AgNO3 exposures only.ConclusionsWith an experimental setup reflecting physiological exposure conditions in the human lung more realistic, the present study indicates that Ag-NPs do not cause adverse effects and cells were only sensitive to high Ag-ion concentrations. Chronic exposure scenarios however, are needed to reveal further insight into the fate of Ag-NPs after deposition and cell interactions.

Silver nanoparticles induced neurotoxicity through oxidative stress in rat cerebral astrocytes is distinct from the effects of silver ions

“…According to the results in this study, silver ions caused the loss of cell membrane integrity in a dose-dependent manner, while AgNPs did not compromise it in the tested concentration range (0.01-10 mg/ mL). Similar finding was also reported in lung cells, wherein the cellular integrity was not impaired upon agglomerates of AgNPs exposure, but was damaged by a higher concentrated AgNO 3 solution (Herzog et al, 2013). This implied the occurrence of distinct toxicological events in astrocytes stimulated by cytotoxic levels of these two silver species, i.e.…”

“…However, this viewpoint still remains ambiguous as inconsistent evidences are often provided from different scenarios. Substantial comparative toxicity assessments have accordingly been performed using diverse experimental models in vitro and in vivo for diverse AgNPs and silver ions (Bone et al, 2015;Herzog et al, 2013). Most of the studies revealed that ionic silver species caused relatively higher toxicity than AgNPs.…”

Repeated exposure to carbon nanotube-based aerosols does not affect the functional properties of a 3D human epithelial airway model

“…occupational exposures at the workplace or biomedical applications, it is crucial to address the biological effects upon repeated CNTs exposure. Consequently, the aim of this study was to mimic inhalation of CNTs in vitro and reveal the mechanisms that underlay the manifestation of potential adverse effects, by producing MWCNTs aerosols using the Air-Liquid Interface Cell Exposure System (ALICE) as described by Lenz et al (2009) for spherical ZnO nanoparticles (NPs), as well as gold NPs ) and silver NPs (Herzog et al, 2013). Recently, it has further been highlighted as a reliable system for the aerosolisation of high aspect ratio materials such as cellulose nanocrystals .…”

LL37 peptide@silver nanoparticles: combining the best of the two worlds for skin infection control

“…[7] Recent work by Herzog et al, has also demonstrated the biocompatibility of silver nanoparticles with airway epithelial cells. [8] In this study, we tested the combination of AgNP with CSG -LL37 peptide, where the -SH served as stabilizer on the AgNP surface [9] forming LL37@AgNP as a new antimicrobial and anti-biofilm agent. Details of the LL37 synthesis are in SI.…”