pectenotoxin-2 and Inflammation

Lipophilic phycotoxins are secondary metabolites produced by phytoplankton. They can accumulate in edible filtering-shellfish and cause human intoxications, particularly gastrointestinal symptoms. Up to now, the in vitro intestinal effects of these toxins have been mainly investigated on simple monolayers of intestinal cells such as the enterocyte-like Caco-2 cell line. Recently, the combination of Caco-2 cells with mucus secreting HT29-MTX cell line has been also used to mimic the complexity of the human intestinal epithelium. Besides, enteric glial cells (EGC) from the enteric nervous system identified in the gut mucosa have been largely shown to be involved in gut functions. Therefore, using a novel model integrating Caco-2 and HT29-MTX cells co-cultured on inserts with EGC seeded in the basolateral compartment, we examined the toxicological effects of two phycotoxins, pectenotoxin-2 (PTX2) and okadaic acid (OA). Cell viability, morphology, barrier integrity, inflammation, barrier crossing, and the response of some specific glial markers were evaluated using a broad set of methodologies. The toxicity of PTX2 was depicted by a slight decrease of viability and integrity as well as a slight increase of inflammation of the Caco-2/HT29-MTX co-cultures. PTX2 induced some modifications of EGC morphology. OA induced IL-8 release and decreased viability and integrity of Caco-2/HT29-MTX cell monolayers. EGC viability was slightly affected by OA. The presence of EGC reinforced barrier integrity and reduced the inflammatory response of the epithelial barrier following OA exposure. The release of GDNF and BDNF gliomediators by EGC could be implicated in the protection observed.

Topics: Caco-2 Cells; Cell Survival; Coculture Techniques; Furans; Gene Expression Regulation; Glial Cell Line-Derived Neurotrophic Factor; HT29 Cells; Humans; Inflammation; Interleukin-8; Intestines; Macrolides; Neuroglia; Nitric Oxide Synthase Type II; Okadaic Acid

Lipophilic phycotoxins are secondary metabolites produced by phytoplanktonic species. They accumulate in filtering shellfish and can cause human intoxications. Humans can be exposed to combinations of several phycotoxins. The toxicological effects of phycotoxin mixtures on human health are largely unknown. Published data on phycotoxin co-exposure show that okadaic acid (OA) is simultaneously found with pectenetoxin-2 (PTX-2), 13-desmethylspirolide C (also known as SPX-1), or yessotoxin (YTX). Therefore, the aim of this study was to examine the effects of three binary mixtures, OA/PTX-2, OA/SPX-1 and OA/YTX on human intestinal Caco-2 cells. A multi-parametric approach for cytotoxicity determination was applied using a high-content analysis platform, including markers for cell viability, oxidative stress, inflammation, and DNA damage. Mixtures effects were analyzed using two additivity mathematical models. Our assays revealed that OA induced cytotoxicity, DNA strand breaks and interleukin 8 release. PTX-2 slightly induced DNA strand breaks, whereas SPX-1 and YTX did not affect the investigated endpoints. The combination of OA with another toxin resulted in reduced toxicity at low concentrations, suggesting antagonistic effects, but in increased effects at higher concentrations, suggesting additive or synergistic effects. Taken together, our results demonstrated that the cytotoxic effects of binary mixtures of lipophilic phycotoxins could not be predicted by additivity mathematical models. In conclusion, the present data suggest that combined effects of phycotoxins may occur which might have the potential to impact on risk assessment of these compounds.

Topics: Animals; Caco-2 Cells; Cell Survival; DNA Damage; Drug Combinations; Drug Interactions; Furans; Humans; Inflammation; Intestines; Macrolides; Marine Toxins; Mollusk Venoms; Okadaic Acid; Oxidative Stress; Oxocins; Pyrans; Shellfish; Spiro Compounds