Exposure of sea bream (Sparus aurata) to toxic concentrations of benzo[a]pyrene: possible human health effect.

Polycyclic aromatic hydrocarbons (PAHs) can accumulate in the food chain, due to their lipophilic properties. Fish can accumulate contaminants including PAHs and frequent consumption of such contaminated fish can pose risk to human health. The aim of this study was to clarify if acute exposure of sea bream (Sparus aurata, a fish species of great economic importance in the Atlantic and Mediterranean areas) to a PAH, benzo[a]pyrene (B[a]P), at a dose that can induce CYP1A and pathological changes in fish gills, liver and muscle, can induce accumulation in muscle. We investigated the cytotoxic effects (as changes in cell viability, DNA laddering and glutathione content) of in vitro exposure of human peripheral blood mononuclear cells (PBMCs) to organic extracts obtained from muscle of sea breams previously exposed via water to B[a]P (2mg/l, for 12, 24 and 72 h). At this level of exposure, B[a]P caused morphological changes, inflammatory response and CYP1A induction not only in sea bream gills and liver but also in muscle; furthermore, in fish muscle we observed a substantial B[a]P accumulation, which may be associated with the increased CYP1A activity in liver and especially in muscle. However, when PBMCs were exposed to organic extracts obtained from sea bream muscle contaminated with B[a]P, a toxic, although modest effect was revealed, consisting in a significant decrease in cell glutathione levels without alterations in cell viability and DNA laddering. This suggests that consumption of sea breams from B[a]P contaminated waters might represent a risk for human health.

Immunohistochemical localization of Toll-like receptor 2 in skin Langerhans' cells of striped dolphin (Stenella coeruleoalba).

The skin is the primary interface between the body and the environment, and has a central role in host defence. In the epidermis, Langerhans' cells form an interconnecting network of dendritic cells, that play a central role within inflammatory and immune responses of terrestrial and aquatic mammals, but few studies aimed at their characterization have been carried out in cetaceans, so far. Toll-like receptors are crucial players in the innate immune response to microbial invaders. These receptors are expressed on immune cells, such as monocytes, macrophages, dendritic cells, and granulocytes. The aim of this preliminary study was to describe the expression of Toll-like receptor 2 in a stranded striped dolphin (Stenella coeruleoalba) skin. Immunoreactive cells were predominantly found within the stratified squamous epithelium. Other Toll-like receptor 2 positive cells of varying morphology, were found, and may help to increase the knowledge on the interaction occurring between dolphins and the environment in which they live at their most crucial interface: the skin.