In vitro effects of suspensions of selected nanoparticles (C60 fullerene, TiO2, SiO2) on Mitilus hemocytes

As the nanotechnology industries increase production, nanoscale products will enter the aquatic environment, posing a possible threat to aquatic organisms. Suspension-feeding invertebrates may represent a unique target group for nanoparticle (NP) ecotoxicity, since they have highly developed processes for the cellular internalisation of nano- and microscale particles (endocytosis and phagocytosis), which are integral to key physiological functions such as intracellular digestion and cellular immunity. In the marine bivalve Mytilus, short-term exposure to nanosized carbon black (NCB) was shown to significantly affect immune parameters of immune cells, the hemocytes, in vitro. In this work, we further investigated the effects of other types of commercial NPs (C60 fullerene, TiO2 and SiO2 at 1, 5, 10g/ml) on Mytilus hemocytes. Characterization of NP suspensions in artificial sea water (ASW) was performed, indicating the formation of agglomerates of different sizes for different types of NPs. None of the NP tested significantly affected lysosomal membrane stability, indicating the lack of a major toxic effect. However, all NP suspensions induced a concentration-dependent lysozyme release, extracellular oxyradical and nitric oxide (NO) production, to a different extent and with different time courses depending on the concentration and the NP type. The inflammatory effects of NPs were mediated by rapid activation of the stress-activated p38 MAPK. The results further support the hypothesis that in bivalves the immune system represents a significant target for NPs.