Development of an in vitro co-culture model of the human small intestine in homeostatic or inflamed state and its application in nanotoxicological research

Abstract

The use of nanomaterials in consumer products and medical research continues to increase. This trend is concerning, especially for orally consumed products, since studies on the effects of oral exposure to nanomaterials remain inconclusive. The limited availability of appropriate in vitro models impedes research, even though questions arising from the increasing prevalence of chronic inflammatory conditions of the intestine need to be addressed urgently. This project aimed to develop an in vitro co-culture model of Caco-2 and PMAdifferentiated THP-1 cells to mimic the human intestine in both homeostatic and controlled inflamed states. The two co-culture models were characterised for cytotoxic (barrier integrity, membrane integrity, and metabolic activity) and inflammatory parameters (cytokines, nitric oxide). After establishing the co-culture protocols, the models were used to study the cytotoxic and inflammatory effects of different nanomaterials (silver and copper oxide nanoparticles) in relation to the health status at the time of exposure. Additionally, the co-cultures were applied to investigate the barrier crossing of radio-labelled gold nanoparticles. Especially for silver nanoparticles strikingly different effects were noted between the two conditions. Overall, the effects were more pronounced in the inflamed co-culture supporting the hypothesis of increased susceptibility to nanomaterials in subjects with impaired health.