Effect of exposure time, particle size and uptake pathways in immune cell lysosomal cytotoxicity of mussels exposed to silver nanoparticles

Abstract

Cytotoxicity evaluation of hemocytes (lysosomal membrane stability [LMS] assay) from Mytilus galloprovincialis Lamarck, exposed to a sublethal dose (100 μg/L) of two size of silver nanoparticles (AgNPs: <50 nm and <100 nm) – prior to and after inhibition of potential uptake pathways (i.e., clathrin- and caveolae-mediated endocytosis) within different times of exposure (3, 6, 12 h) – showed that there was a significant cytotoxic effect on immune cells of mussels exposed for different times to either AgNP size (p < 0.01); the greater effect was with the smaller size. However, hemocytes seemed more sensitive to the larger AgNP after clathrin-mediated endocytosis was blocked (p < 0.01); this was not so with inhibition of caveolae-mediated endocytosis. Dimethyl-sulfoxide (DMSO) did not impart a carrier-mediated effect despite an enhanced cytotoxicity when DMSO was present with AgNP. From these results, it is concluded that the immunotoxicity of AgNP in mussels was size-dependent as well as length of exposure-dependent. It was also clear that nanoparticles (NP) internalization mechanisms were a major factor underlying any toxicity.

Keywords:

• Hemocyte
• endocytosis
• nanotoxicity
• amantadine
• nystatin
• lysosomal membrane stability

Acknowledgements

This study was funded by the Immuno-Microbiology, Environmental and Carcinogensis IMEC Research Unit at the University of Carthage (Tunisia). The authors thank Drs. Abdessalem Kouki (EM) for the assistance in TEM analyses and Saidani Zouhair (XRD diffraction) for assistance in AgNP characterizations. The authors also thank Dr. David Sheehan at the Proteomic Research Group in the School of Biochemistry and Cell Biology at University College Cork (Ireland), for reviewing this paper.

Disclosure statement

No potential conflict of interest was reported by the authors.