Antimicrobial properties of silver and the advances of nanotechnology have led to the development of silver nanoparticles (AgNPs) that can be found in more and more food-related applications such as coatings or sprays. Some unauthorised food supplements are also sold to treat infections or boost immune defences. All these applications could result in ingestion of AgNPs that will undoubtedly raise with the increasing incorporation of AgNPs in consumer products. Nevertheless, only few studies among existing literature have focused on the gut, despite the major role of this organ in immunity. In addition, this organ is exposed to the highest concentrations of ingested components, compared to internal tissues. However, numerous studies have observed a toxicity of AgNPs in different in vitro cellular models. Regarding inflammation, studies are not unambiguous. Most in vivo studies suggested anti-inflammatory properties of silver, presenting beneficial properties for wound and burn treatments. Nevertheless, in vitro studies are less unanimous. The general purpose of this study was to investigate the inflammatory properties of AgNPs on the intestinal barrier, using an in vitro model of the small intestine achieved by Caco-2 cell cultures. This study confirmed the need of appropriate controls in the study of nanomaterials toxicity. In this context, in vitro models could provide a toolbox for comprehensive toxicity assessment. Furthermore, in our model, AgNPs were unable to induce the inflammatory NF-κB pathway, even inhibiting its activation by an inflammatory cocktail. A part of this inhibition is due to silver nanoparticles themselves. In addition, AgNPs, induced a polarised secretion of the pro-inflammatory chemokine interleukin-8, which might be mediated by an oxidative stress response pathway i.e. the Nrf2 signalling pathway. This effect is mainly related to silver ions present in AgNPs suspensions. In conclusion, AgNPs seem to affect inflammatory responses in Caco-2 cells. (SC - Sciences) -- UCL, 2020
