Metabolism and cytotoxic effects of T-2 toxin and its metabolites on human cells in primary culture

Abstract

T-2 toxin belongs to the large group of trichothecene mycotoxins synthesized by various Fusarium molds which can infect raw agriculture materials. Among the trichothecenes, T-2 toxin is one of the most potent mycotoxins and poses a potential health risk in human nutrition. Several acute and chronic toxic effects were observed in humans after consumption of contaminated food. Due to the rapid metabolism of T-2 toxin by esterases, several metabolites can be found in food and also in vivo after ingestion. The aim of this work was to determine the effects of T-2 toxin and of several of its metabolites, namely HT-2 toxin, neosolaniol, T-2-triol and T-2 tetraol, on two human cells in primary culture: human renal proximal tubule epithelial cells (RPTEC) and normal human lung fibroblasts (NHLF). Concerning the cytotoxicity of T-2 toxin and its metabolites, different studies were performed with animal cells and cell lines but there are only little data about cytotoxic effects in human cells. The use of human cells in primary culture gives a good completion of the already known data because these might be limited due to the disadvantages of cell lines (e.g., immortalization, tumor derivation, longtime cultivation). In order to study the cytotoxicity and mode of cell death, the parameters cell viability, caspase-3-activity and LDH-release were measured after exposure to T-2 toxin and several of its metabolites. With IC 50 values of 0.2 and 0.5 μM T-2 toxin showed the strongest cytotoxic effect in both cells with triggering apoptosis as kind of cell death starting at a concentration of 100 nM. The metabolites HT-2 toxin and neosolaniol revealed weaker cytotoxic effects (IC 50: 0.7–3.0 μM) and induced apoptosis at higher concentrations (>1 μM). The other metabolites were less cytotoxic (IC 50: 8.3–25.1 μM) and did not activate caspase-3. In addition to the analysis of cytotoxic effects, we also studied the metabolism of T-2 toxin in these cells in primary culture. Using LC–ESI-MS/MS we could demonstrate that both cells are able to transform T-2 toxin into HT-2 toxin. Further metabolic activity could only be observed in renal proximal tubule (RPTEC) cells by forming neosolaniol as a second metabolite.