Immunomodulation by Different Types of N-Oxides in the Hemocytes of the Marine Bivalve Mytilus galloprovincialis

Abstract

The potential toxicity of engineered nanoparticles (NPs) for humans and the environment represents an emerging issue. Since the aquatic environment represents the ultimate sink for NP deposition, the development of suitable assays is needed to evaluate the potential impact of NPs on aquatic biota. The immune system is a sensitive target for NPs, and conservation of innate immunity represents an useful basis for studying common biological responses to NPs. Suspension-feeding invertebrates, such as bivalves, are particularly at risk to NP exposure, since they have extremely developed systems for uptake of nano and microscale particles integral to intracellular digestion and cellular immunity. Evaluation of the effects of NPs on functional parameters of bivalve immunocytes, the hemocytes, may help understanding the major toxic mechanisms and modes of actions that could be relevant for different NP types in aquatic organisms.In this work, a battery of assays was applied to the hemocytes of the marine bivalve Mytilus galloprovincialis to compare the in vitro effects of different n-oxides (n-TiO2, n-SiO2, n-ZnO, n-CeO2) chosen on the basis of their commercial and environmental relevance. Physico-chemical characterization of both primary particles and NP suspensions in artificial sea water-ASW was performed. Hemocyte lysosomal and mitochondrial parameters, oxyradical and nitric oxide production, phagocytic activity, as well as NP uptake, were evaluated. The results show that different n-oxides rapidly elicited differential responses hemocytes in relation to their chemical properties, concentration, behavior in sea water, and interactions with subcellular compartments. These represent the most extensive data so far available on the effects of NPs in the cells of aquatic organisms. The results indicate that Mytilus hemocytes can be utilized as a suitable model for screening the potential effects of NPs in the cells of aquatic invertebrates, and may provide a basis for future experimental work for designing environmentally safer nanomaterials.

Comparative Effects of Ingested PVC Micro Particles With and Without Adsorbed Benzo(a)pyrene vs. Spiked Sediments on the Cellular and Sub Cellular Processes of the Benthic Organism Hediste diversicolor

“…Similar conclusions are drawn by Gopalakrishnan et al (2011) in hemocytes of the gastropod abalone H. diversicolor, by Liu et al (2014) in hemocytes of the clam V. philippinarum as well as by Danion et al (2011) in hemocytes of sea bass D. labrax exposed to B[a]P. According to these authors the immunosuppressive effects of B[a]P could be explained by the substantial disruption of sub cellular processes and organelle's functioning of the immune system's cells in the exposed organism. On the other hand, none of the exposure conditions induced a significant release of lysozyme thus supporting some previously reported conclusions that in hemocytes of invertebrates, the assessment of a sole parameter cannot be considered as entirely illustrative of immunocompetence (Ciacci et al, 2012). On the contrary, all treatments involving B[a]P clearly affected mitochondrial activity of coelomocytes.…”

“…The obtained cell suspension was centrifuged at 200 g at 4 • C for 5 min to recover the cells; water was discarded and the pellet gentle resuspended in 2 ml ASW. In detail, phagocytosis analysis was assessed by quantifying cellular intake of Neutral Red-stained Zymosan according to Ciacci et al (2012). 100 uL of cell suspension was incubated with stained Zymosan with 20 to 40 cells from each exposure condition then examined using image analysis by ImageJ release 1.51 K shareware software (NiH, USA).…”

“…Lysozyme activity in coelomic cell suspensions obtained from organisms exposed to the different conditions was determined spectrophotometrically at 450 nm utilizing M. lysodeikticus and referenced against results of organisms exposed to natural sediment (Ciacci et al, 2012).…”

In vivo effects of Aphanizomenon flos-aquae DC-1 aphantoxins on gas exchange and ion equilibrium in the zebrafish gill

“…The mitochondrial hyperplasia observed 1 h after aphantoxin administration may be considered a compensatory mechanism in response to an increased demand for energy to deal with cellular toxins, as has been observed in previous studies (Das et al, 2014). The decreased mitochondrial density observed in chloride cells (from 3 to 12 h) may be attributed to cellular damage due to increased membrane permeability and osmotic imbalance, which is similar to the previous results (Ciacci et al, 2012). Therefore, the current study suggests that aphantoxins or PSPs may trigger ultrastructural damage in both the epithelial and chloride cells in the zebrafish gill, which may represent important markers for respiratory toxicity as a result of aphantoxin or PSP exposure.…”

Zinc Oxide Nanoparticles: The Hidden Danger

“…This results in cytotoxicity, oxidative stress, and mitochondrial dysfunction [7,9,11,53,56]. Mansouri et al (2015) [34] and Yang et al (2015) [33], reported higher Zn concentration in the liver tissues of rodents orally administered ZnO-NPs and showed elevated serum AST and ALT.…”