Modeling the emetic potencies of food-borne trichothecenes by benchmark dose methodology

Protective Effect of Selenomethionine on T-2 Toxin-Induced Rabbit Immunotoxicity

T-2 toxin is a trichothecene mycotoxin produced by fusarium species, which is mainly prevalent in grain and livestock feed. One of the main effects of this toxin is immunodepression. Previous studies have shown that T-2 toxin can cause damage to immune organs and impaired immune function in animals. However, selenomethionine (SeMet) as an organic selenium source can not only promote the growth and development of the body but also effectively improve the body's immune function. In this study, rabbits were exposed to 0.4-mg/kg T-2 toxin, and abnormal blood routine indicators were found in the rabbits. HE staining also showed obvious lesions in the spleen and thymus tissue structures, accompanied by a large number of bleeding points. In addition, rabbits showed strong oxidative stress and inflammatory response after T-2 toxin action. 0.2 mg/kg, 0.4 mg/kg, and 0.6 mg/kg organic selenium were added to the feed. However, it was found that 0.2 mg/kg selenium can effectively improve the abnormal changes of blood routine and spleen and thymus tissue of rabbits. On the other hand, it can significantly increase the expression of glutathione peroxidase (GSH-Px), superoxide dismutase (SOD), and total antioxidant capacity (T-AOC) in the spleen and thymus, and downregulate the expression of reactive oxygen species (ROS) and malondialdehyde (MDA). In addition, inflammatory factors interleukin-1 beta (IL-1β) and interleukin-6 (IL-6) and tumor necrosis factor alpha (TNF-α) in blood were also significantly inhibited; the expression of proliferating cell nuclear antigen (PCNA) in the spleen and thymus was also significantly increased after low-dose selenium treatment. Surprisingly, 0.4 mg/kg and 0.6 mg/kg of selenium did not effectively alleviate the immunotoxic effects caused by T-2 toxin, and cause damage to a certain extent. In summary, our results show that 0.2 mg/kg of SeMet can effectively alleviate the immunotoxicity caused by T-2 toxin. Selenium may protect rabbits from T-2 toxin by improving its antioxidant and anti-inflammatory capabilities.

T-2 Toxin-The Most Toxic Trichothecene Mycotoxin: Metabolism, Toxicity, and Decontamination Strategies

Among trichothecenes, T-2 toxin is the most toxic fungal secondary metabolite produced by different Fusarium species. Moreover, T-2 is the most common cause of poisoning that results from the consumption of contaminated cereal-based food and feed reported among humans and animals. The food and feed most contaminated with T-2 toxin is made from wheat, barley, rye, oats, and maize. After exposition or ingestion, T-2 is immediately absorbed from the alimentary tract or through the respiratory mucosal membranes and transported to the liver as a primary organ responsible for toxin's metabolism. Depending on the age, way of exposure, and dosage, intoxication manifests by vomiting, feed refusal, stomach necrosis, and skin irritation, which is rarely observed in case of mycotoxins intoxication. In order to eliminate T-2 toxin, various decontamination techniques have been found to mitigate the concentration of T-2 toxin in agricultural commodities. However, it is believed that 100% degradation of this toxin could be not possible. In this review, T-2 toxin toxicity, metabolism, and decontamination strategies are presented and discussed.

Review article: Role of satiety hormones in anorexia induction by Trichothecene mycotoxins

The trichothecenes, produced by Fusarium, contaminate animal feed and human food in all stages of production and lead to a large spectrum of adverse effects for animal and human health. An hallmark of trichothecenes toxicity is the onset of emesis followed by anorexia and food intake reduction in different animal species (mink, mice and pig). The modulation of emesis and anorexia can result from a direct action of trichothecenes in the brain or from an indirect action in the gastrointestinal tract. The direct action of trichothecenes involved specific brain areas such as nucleate tractus solitarius in the brainstem and the arcuate nuclei in the hypothalamus. Activation of these areas in the brain leads to the activation of specific neuronal populations containing anorexigenic factors (POMC and CART). The indirect action of trichothecenes in the gastrointestinal tract involved, by enteroendocrine cells, the secretion of several gut hormones such as cholecystokinin (CCK) and peptide YY (PYY) but also glucagon-like peptide 1 (GLP-1), gastric inhibitory peptide (GIP) and 5-hydroxytryptamine (5-HT), which transmitted signals to the brain via the gut-brain axis. This review summarizes current knowledge on the effects of trichothecenes, especially deoxynivalenol, on emesis and anorexia and discusses the mechanisms underlying trichothecenes-induced food reduction.

Primary and Immortalized Human Respiratory Cells Display Different Patterns of Cytotoxicity and Cytokine Release upon Exposure to Deoxynivalenol, Nivalenol and Fusarenon-X

The type B trichothecene mycotoxins deoxynivalenol (DON), nivalenol (NIV) and fusarenon-X (FX) are structurally related secondary metabolites frequently produced by Fusarium on wheat. Consequently, DON, NIV and FX contaminate wheat dusts, exposing grain workers to toxins by inhalation. Those trichothecenes at low, relevant, exposition concentrations have differential effects on intestinal cells, but whether such differences exist with respiratory cells is mostly unknown, while it is required to assess the combined risk of exposure to mycotoxins. The goal of the present study was to compare the effects of DON, NIV and FX alone or in combination on the viability and IL-6 and IL-8-inducing capacity of human epithelial cells representative of the respiratory tract: primary human airway epithelial cells of nasal (hAECN) and bronchial (hAECB) origin, and immortalized human bronchial (16HBE14o-) and alveolar (A549) epithelial cell lines. We report that A549 cells are particularly resistant to the cytotoxic effects of mycotoxins. FX is more toxic than DON and NIV for all epithelial cell types. Nasal and bronchial primary cells are more sensitive than bronchial and alveolar cell lines to combined mycotoxin mixtures at low concentrations, although they are less sensitive to mycotoxins alone. Interactions between mycotoxins at low concentrations are rarely additive and are observed only for DON/NIV and NIV/FX on hAECB cells and DON/NIV/FX on A549 cells. Most interactions at low mycotoxin concentrations are synergistic, antagonistic interactions being observed only for DON/FX on hAECB, DON/NIV on 16HBE14o- and NIV/FX on A549 cells. DON, NIV and FX induce, albeit at different levels, IL-6 and IL-8 release by all cell types. However, NIV and FX at concentrations of low cytotoxicity induce IL-6 release by hAECB and A549 cells, and IL-8 release by hAECN cells. Overall, these data suggest that combined exposure to mycotoxins at low concentrations have a stronger effect on primary nasal epithelial cells than on bronchial epithelial cells and activate different inflammatory pathways. This information is particularly relevant for future studies about the hazard of occupational exposure to mycotoxins by inhalation and its impact on the respiratory tract.

Risks to human and animal health related to the presence of deoxynivalenol and its acetylated and modified forms in food and feed

Deoxynivalenol (DON) is a mycotoxin primarily produced by Fusarium fungi, occurring predominantly in cereal grains. Following the request of the European Commission, the CONTAM Panel assessed the risk to animal and human health related to DON, 3-acetyl-DON (3-Ac-DON), 15-acetyl-DON (15-Ac-DON) and DON-3-glucoside in food and feed. A total of 27,537, 13,892, 7,270 and 2,266 analytical data for DON, 3-Ac-DON, 15-Ac-DON and DON-3-glucoside, respectively, in food, feed and unprocessed grains collected from 2007 to 2014 were used. For human exposure, grains and grain-based products were main sources, whereas in farm and companion animals, cereal grains, cereal by-products and forage maize contributed most. DON is rapidly absorbed, distributed, and excreted. Since 3-Ac-DON and 15-Ac-DON are largely deacetylated and DON-3-glucoside cleaved in the intestines the same toxic effects as DON can be expected. The TDI of 1 μg/kg bw per day, that was established for DON based on reduced body weight gain in mice, was therefore used as a group-TDI for the sum of DON, 3-Ac-DON, 15-Ac-DON and DON-3-glucoside. In order to assess acute human health risk, epidemiological data from mycotoxicoses were assessed and a group-ARfD of 8 μg/kg bw per eating occasion was calculated. Estimates of acute dietary exposures were below this dose and did not raise a health concern in humans. The estimated mean chronic dietary exposure was above the group-TDI in infants, toddlers and other children, and at high exposure also in adolescents and adults, indicating a potential health concern. Based on estimated mean dietary concentrations in ruminants, poultry, rabbits, dogs and cats, most farmed fish species and horses, adverse effects are not expected. At the high dietary concentrations, there is a potential risk for chronic adverse effects in pigs and fish and for acute adverse effects in cats and farmed mink.

Intestinal toxicity of the type B trichothecene mycotoxin fusarenon-X: whole transcriptome profiling reveals new signaling pathways

The few data available on fusarenon-X (FX) do not support the derivation of health-based guidance values, although preliminary results suggest higher toxicity than other regulated trichothecenes. Using histo-morphological analysis and whole transcriptome profiling, this study was designed to obtain a global view of the intestinal alterations induced by FX. Deoxynivalenol (DON) served as a benchmark. FX induced more severe histological alterations than DON. Inflammation was the hallmark of the molecular toxicity of both mycotoxins. The benchmark doses for the up-regulation of key inflammatory genes by FX were 4- to 45-fold higher than the previously reported values for DON. The transcriptome analysis revealed that both mycotoxins down-regulated the peroxisome proliferator-activated receptor (PPAR) and liver X receptor - retinoid X receptor (LXR-RXR) signaling pathways that control lipid metabolism. Interestingly, several pathways, including VDR/RXR activation, ephrin receptor signaling, and GNRH signaling, were specific to FX and thus discriminated the transcriptomic fingerprints of the two mycotoxins. These results demonstrate that FX induces more potent intestinal inflammation than DON. Moreover, although the mechanisms of toxicity of both mycotoxins are similar in many ways, this study emphasize specific pathways targeted by each mycotoxin, highlighting the need for specific mechanism-based risk assessments of Fusarium mycotoxins.