Evidence of a non-apoptotic mode of cell death in microglial BV-2 cells exposed to different concentrations of zinc oxide nanoparticles.
Fiche publication
Date publication
octobre 2020
Journal
Environmental science and pollution research international
Auteurs
Membres identifiés du Cancéropôle Est :
Dr LIZARD Gérard, Pr MILLOT Nadine
Tous les auteurs :
Sruthi S, Nury T, Millot N, Lizard G
Lien Pubmed
Résumé
Zinc oxide nanoparticles (ZnO NPs) possess huge application potential. However, the toxicity of ZnO NPs is a great cause of concern. Indeed, ZnO NPs have been found to cause neurotoxicity. As microglial dysfunctions have been linked to the neurotoxic potential of NPs, the physico-chemical properties of ZnO NPs were determined and their cytotoxic effects were characterised on murine microglial BV-2 cells. In-house prepared and meticulously characterised ZnO NPs exhibited narrow size distribution with an average size of around 20 nm and a zeta potential at physiological pH around 24 mV. ZnO NPs did not exhibit aggregation in the cell culture medium. When microglial BV-2 cells were exposed for 6 and 24 h to ZnO NPs (5, 10, 20, 40, and 80 μg/mL), several cell damages were observed. Cellular accumulation of NPs in microglial BV-2 cells was associated with cell growth inhibition and cell death induction, measured by the trypan blue exclusion and MTT assays. Mitochondrial dysfunction and lysosomal alteration were associated with increased plasma membrane permeability measured by staining with DiOC(3), acridine orange, and propidium iodide, respectively. In addition, an accumulation of reactive oxygen species (ROS) was detected after staining with dihydroethidium and dihydrorhodamine 123. No apoptotic features were present: no cells with condensed and/or fragmented nuclei (Hoechst staining) characteristic of apoptotic cells, absence of subG1 cells, absence of caspase-3 cleavage, and PARP fragmentation. With ZnO NPs (80 μg/mL), with the annexin V/propidium iodide (PI) assay, few apoptotic cells (annexin V+/PI- cells) were detected whereas (annexin V+/PI+ cells) evocating necrotic cells were mainly identified. No modification of the cells in the different phases of the cell cycle was found. Altogether, our data show that ZnO NPs induce a non-apoptotic mode of cell death associated with an accumulation of ROS, mitochondrial, and lysosomal dysfunction and plasma membrane damages in microglial BV-2 cells.Graphical abstract.
Mots clés
Lysosomal destabilisation, Microglial BV-2 cells, Mitochondrial dysfunction, Non-apoptotic mode of cell death, Oxidative stress, Plasma membrane permeability, Zinc oxide nanoparticles (ZnO NPs)
Référence
Environ Sci Pollut Res Int. 2020 Oct 20;: