In vitrotoxicity assessment of silver nanoparticles in the presence of phenolic compounds – preventive agents against the harmful effect?

Abstract

The increasing commercial use of silver nanoparticles (Ag-NPs) will inevitably lead to elevated silver exposure and thus to potential human health complications. In this study the acute toxicity of Ag-NPs <20 nm alone and upon co-administration with food matrix component phenolic compounds (PCs) on the cell-based models of the gastrointestinal tract was investigated. An improved co-culture model of Caco-2 and RajiB cells was applied for more precise in vitro simulation of the gastrointestinal tract. The involvement of two major factors contributing to the toxicity of Ag-NPs, i.e. the release of Ag(+) and the induction of oxidative stress, was investigated. Ag-NPs were cytotoxic for Caco-2 cells with an EC50 of ca. 40 µg/ml. Ag-NPs led to oxidative stress starting from ca. 45 µg/ml. The epithelial barrier integrity disruption by Ag-NPs on Caco-2 cell mono- and co-cultures was established by decreased transepithelial electrical resistances and increased passages of Lucifer Yellow, a paracellular marker. Immunofluorescence staining demonstrated that Ag-NPs affect occludin and zonula occludens 1 distributions, suggesting the opening of tight junctions. Ag(+), corresponding to the release from Ag-NPs, demonstrated a partial contribution in the toxic parameters, induced by Ag-NPs. Two PCs, quercetin and kaempferol, partially protected the Caco-2 cells from Ag-NP-induced toxicity and maintained the epithelial barrier integrity, disrupted by NPs. No protective effect was observed for resveratrol. The protective effect could be beneficial and decrease the potential toxicity of ingested Ag-NPs. However, the precise mechanisms of barrier-integrity-destabilising action of Ag-NPs/Ag(+) and protective effect of PCs still require further elucidation.

The Influence of Silver Nanoparticles on the Blood-Brain and the Blood-Cerebrospinal Fluid Barrier in vitro

“…Again, AgCitrate-NPs exhibited a much weaker effect on tight junction formation in PBCEC. The obtained results of tight junction expression and distribution support the TEER and permeability measurements and are in accordance with the studies of Trickler et al [13] and Martirosyan et al [23]. In addition, the immunofluorescence staining of occludin in the cells of the choroid plexus reveals undisturbed tight junctions, which supports the results of our TEER and permeability measurements.…”

“…Within our study we have analyzed the TEER development, permeability against FITC-Dextrane as well as tight junction expression and distribution upon exposure of barrier-forming cells of CNS origin to Ag-NPs. Similarly to the studies of Trickler et al [13] and Martyrosian et al [23] we detected an increase of BBB permeability against FITC-Dextrane after exposure of PBCEC to Ag-NP which has also been confirmed by a decrease of the TER. Again, AgEO-NPs were found to induce a more severe permeability than AgCitrate-NPs.…”

“…Trickler et al [13] observed an increased permeability against fluorescein in rat brain microvascular endothelial cells after exposure to Ag-NPs, but effects on tight junction formation have not been evaluated. Martirosyan et al [23] reported a decrease of TER and an increase of Luzifer Yellow permeability in Caco-2 cells upon exposure to Ag-NP. In addition, they also observed a change in distribution of the tight junction proteins occludin and ZO-1, which may have caused the barrier dysfunction.…”

Different responses of Caco-2 and MCF-7 cells to silver nanoparticles are based on highly similar mechanisms of action

“…Cellular uptake has been described, which was suggested to occur through endocytosis (Gaiser et al, 2012). Cytotoxicity data is contradictory, varying from absence of cytotoxicity (Chalew & Schwab, 2013;Bouwmeester et al, 2011), to time and dose dependent cytotoxicity (Bohmert et al, 2012(Bohmert et al, , 2015Martirosyan et al, 2014). The human breast cancer MCF-7 epithelial cell line has been used to create a reference collection of gene-expression profiles following treatment with bioactive small molecules.…”

Oxidative stress-mediated inhibition of intestinal epithelial cell proliferation by silver nanoparticles

“…14,16,17,29,30 Treatment of proliferating cells with Ag NP for 24 hours decreased the GSH/GSSG ratio to less than half the level in untreated cells, indicating oxidative stress (Figure 8). Other studies in Caco-2 cells have shown induction of oxidative stress by detection of ROS species production 17,31 and gene expression studies showed upregulation of genes involved in oxidative stress in the Caco-2/M cell model. 32 However, some studies have not detected ROS formation in Caco-2 cells.…”