Vers une meilleure compréhension de la phagocytose des nanotubes de carbone par les macrophages alvéolaires

The main role of alveolar macrophages is the phagocytosis of exogenous particles including nanomaterials, in order to eliminate them and protect the organism against their adverse effects. However, the structure of some materials do not allow macrophages to productive phagocytosis, leading to a frustrated phagocytosis. This incomplete phagocytosis was described with asbestos fibres whose length is higher than the macrophage size. The fibrous shape of carbon nanotubes arouse concern, since some of them could be several µm long. In addition, it was shown that some carbon nanotubes could induce frustrated phagocytosis. This event leads to macrophage cell death, and therefore induction of pro-inflammatory cytokine release, which participate to the establishment of a persistent inflammation that can conduct to pulmonary disease development, such as cancer or fibrosis.
We treated rat alveolar macrophages, NR8383, with carbon nanotubes of different length and diameter. We analysed proliferation and cytotoxicity through real-time cell imaging and cell morphology by May-Grünwald Giemsa staining. We evaluated the expression at the mRNA and protein level of transmembrane receptors and pro-inflammatory cytokines.
Cytologic approach shows morphology modifications, the presence of carbon nanotube potentially inside the cells, and the cooperation of cells to remove particles. Using molecular approach, we showed a modulation of transmembrane receptor and pro-inflammatory cytokine expression, with different intensities according to the length of carbon nanotubes.