Influence of the physicochemical properties of multi-walled carbon nanotubes on their toxicity in lung cells

Multi-walled carbon nanotubes (MWCNTs) are promising nanomaterials because of their various physicochemical properties. However, their production and handling can lead to their aerosolization. Then, they can be inhaled, reach the deep lung and induce health effects. The respiratory system is composed of different cell types, including epithelial cells and alveolar macrophages, which are on the front line following inhalation of MWCNTs. The aim of this study was to evaluate the influence of their physicochemical properties on their toxic effects.<br/>
To address this objective, we use two in vitro models, NR8383 rat alveolar macrophages and BEAS-2B human bronchial epithelial cells. BEAS-2B cells are treated with low concentrations of nanomaterials for 6 weeks in order to evaluate a potential epithelial-mesenchymal transition (EMT). NR8383 macrophages are treated for up to 24 hours in order to study their polarization and cell signalling.<br/>
The first results show that the treatment of BEAS-2B cells with MWCNTs induced a modification of their phenotype in a differential time-scale and concentration depending on their physicochemical properties. This modification is accompanied by a change in the expression of genes specific to EMT. In addition, the treatment of NR8383 with MWCNTs induced a modification of cell signalling, which can be observed in particular through the expression of transmembrane receptors and that of pro-inflammatory cytokines.<br/>
The differential effects observed following treatment of the cells with the different types of MWCNTs can be considered regarding their physical properties, such as their length, diameter and specific surface area, as well as their chemical properties, in other terms their functionalization.