T-2 toxin is a cytochrome P450 1A1 inducer and leads to MAPK/p38- but not aryl hydrocarbon receptor-dependent interleukin-8 secretion in the human intestinal epithelial cell line Caco-2

Identification of Biotransformation Products of T-2 Toxin in HepG2 Cells Using LC-Q-TOF MS

The T-2 toxin (T-2) is a type A trichothecene found in cereals. The formation of metabolites is a frequent cause of mycotoxin-induced toxicity. In this work, the conversion of T-2 during biotransformation reactions in HepG2 cells was evaluated. For this, HepG2 cells were exposed to 30 (IC50/2) and 60 (IC50) nM of T-2 for 0, 1, 2, 3, 6, 8 and 24 h, and the concentrations of T-2 and its metabolites HT-2, T2-triol, T2-tetraol and neosolaniol were determined in both the cell fraction and culture medium through liquid chromatography coupled to high-resolution mass spectrometry-time of flight (LC-Q-TOF MS). Results showed a fast metabolization of T-2 (>90%) during the first 2 h, with HT-2 as its main (>95%) biotransformation product. The cell fraction showed higher levels (p < 0.05) of HT-2 (39.9 ± 2.1 nM) compared to the culture medium (12.53 ± 2.4 nM). This trend was also observed for the identified metabolites. T2-triol reached its maximum concentration (1.7 ± 0.4 nM) at 2 h, and at later times a time-dependent increase in the T2-tetraol and neosolaniol concentrations was observed. The identification of T-2 metabolites shows the need to continue combined toxicity studies of mycotoxins for a correct risk characterization of these natural contaminants.

Insights into the intestinal toxicity of foodborne mycotoxins through gut microbiota: A comprehensive review

Mycotoxins, which are fungal metabolites, pose a significant global food safety concern by extensively contaminating food and feed, thereby seriously threatening public health and economic development. Many foodborne mycotoxins exhibit potent intestinal toxicity. However, the mechanisms underlying mycotoxin-induced intestinal toxicity are diverse and complex, and effective prevention or treatment methods for this condition have not yet been established in clinical and animal husbandry practices. In recent years, there has been increasing attention to the role of gut microbiota in the occurrence and development of intestinal diseases. Hence, this review aims to provide a comprehensive summary of the intestinal toxicity mechanisms of six common foodborne mycotoxins. It also explores novel toxicity mechanisms through the "key gut microbiota-key metabolites-key targets" axis, utilizing multiomics and precision toxicology studies with a specific focus on gut microbiota. Additionally, we examine the potential beneficial effects of probiotic supplementation on mycotoxin-induced toxicity based on initial gut microbiota-mediated mycotoxicity. This review offers a systematic description of how mycotoxins impact gut microbiota, metabolites, and genes or proteins, providing valuable insights for subsequent toxicity studies of mycotoxins. Furthermore, it lays a theoretical foundation for preventing and treating intestinal toxicity caused by mycotoxins and advancing food safety practices.

Role of DNA methylation-related chromatin remodeling in aryl hydrocarbon receptor-dependent regulation of T-2 toxin highly inducible Cytochrome P450 1A4 gene

Mycotoxins are toxic secondary metabolites produced by food-contaminating fungi, which lead to global epigenetic changes and cause toxicity to both farm animals and humans. However, whether mycotoxins induce gene-specific epigenetic alterations associated with inducible downstream gene expression is unclear as are the underlying regulatory mechanisms. Here, we found that T-2 toxin and its deacetylated metabolites but not deoxynivalenol (DON) or other representative mycotoxins highly induced the expression of cytochrome P450 1A4 (CYP1A4) in both Leghorn male hepatoma (LMH) cells and chicken primary hepatocytes, and this effect was related to the regulation of both aryl hydrocarbon receptor (AhR) and DNA methylation. We used methylation-sensitive restriction enzyme digestion-qPCR (MSRE-qPCR) and chromatin immunoprecipitation (ChIP) assays and found that the binding of DNA methyltransferase 1 (DNMT1) and histone deacetylase 2 (HDAC2) to highly methylated CpG island 3-2 at the enhancer of CYP1A4 was accompanied by the recruitment of the repressive histone modification marker H3K27me3, inducing a silent state. In turn, T-2 toxin stimulation enriched the binding of AhR to demethylated CpG island 3-2, which facilitated p300 and H3K9ac recruitment and ultimately generated an activated chromatin structure at the enhancer by increasing the active histone modification markers, including H3K4me3, H3K27ac, and H3K14ac. Interestingly, T-2 toxin-induced AhR activation also facilitated RNA polymerase II binding to CpG island 2, which may form a transcriptionally active chromatin structure at the promoter and ultimately transactivate CYP1A4. Our findings provide novel insights into the epigenetic regulation of T-2 toxin-induced gene expression.

Investigation of the inflammatory and oxidative stress-inducing effects of deoxynivalenol and T-2 toxin exposure in non-tumorigenic human intestinal cell model

Fungi in the Fusarium genus produce trichothecene mycotoxins including deoxynivalenol (DON) and T-2 toxin which may elicit their damaging effects on the gastrointestinal tract following the consumption of contaminated cereal-based foods. The aim of our study was to evaluate the effects of these commonly occurring fusarotoxins alone and in combination using the human, non-cancerous intestinal epithelial cell line HIEC-6. Based on our experimental data, 24 h after treatment with fusarotoxins, hydrogen peroxide levels, intracellular oxidative stress and the amounts of inflammatory interleukins IL-6 and IL-8 significantly increased. Cell membrane localization of the tight junction protein claudin-1 decreased, whereas distribution of occludin remained unchanged. Taken together, the HIEC-6 cell line appears to be a suitable experimental model for monitoring the combined effects of mycotoxins at the cellular level including changes in the redox states of cells.

Beneficial Effects of Rosmarinic Acid on IPEC-J2 Cells Exposed to the Combination of Deoxynivalenol and T-2 Toxin

Mycotoxin contamination in feedstuffs is a worldwide problem that causes serious health issues both in humans and animals, and it contributes to serious economic losses. Deoxynivalenol (DON) and T-2 toxin (T-2) are major trichothecene mycotoxins and are known to challenge mainly intestinal barrier functions. Polyphenolic rosmarinic acid (RA) appeared to have antioxidant and anti-inflammatory properties in vitro. The aim of this study was to investigate protective effects of RA against DON and T-2 or combined mycotoxin-induced intestinal damage in nontumorigenic porcine cell line, IPEC-J2. It was ascertained that simultaneous treatment of DON and T-2 (DT2: 1 μmol/L DON + 5 nmol/L T - 2) for 48 h and 72 h reduced transepithelial electrical resistance of cell monolayer, which was restored by 50 μmol/L RA application. It was also found that DT2 for 48 h and 72 h could induce oxidative stress and elevate interleukin-6 (IL-6) and interleukin-8 (IL-8) levels significantly, which were alleviated by the administration of RA. DT2 administration contributed to the redistribution of claudin-1; however, occludin membranous localization was not altered by combined mycotoxin treatment. In conclusion, beneficial effect of RA was exerted on DT2-deteriorated cell monolayer integrity and on the perturbated redox status of IPEC-J2 cells.

In-Vitro Cell Culture for Efficient Assessment of Mycotoxin Exposure, Toxicity and Risk Mitigation

Mycotoxins are toxic secondary fungal metabolites that commonly contaminate crops and food by-products and thus, animal feed. Ingestion of mycotoxins can lead to mycotoxicosis in both animals and humans, and at subclinical concentrations may affect animal production and adulterate feed and animal by-products. Mycotoxicity mechanisms of action (MOA) are largely unknown, and co-contamination, which is often the case, raises the likelihood of mycotoxin interactions. Mitigation strategies for reducing the risk of mycotoxicity are diverse and may not necessarily provide protection against all mycotoxins. These factors, as well as the species-specific risk of toxicity, collectively make an assessment of exposure, toxicity, and risk mitigation very challenging and costly; thus, in-vitro cell culture models provide a useful tool for their initial assessment. Since ingestion is the most common route of mycotoxin exposure, the intestinal epithelial barrier comprised of epithelial cells (IECs) and immune cells such as macrophages, represents ground zero where mycotoxins are absorbed, biotransformed, and elicit toxicity. This article aims to review different in-vitro IEC or co-culture models that can be used for assessing mycotoxin exposure, toxicity, and risk mitigation, and their suitability and limitations for the safety assessment of animal foods and food by-products.

Cellular Effects of T-2 Toxin on Primary Hepatic Cell Culture Models of Chickens

Trichothecene mycotoxins such as T-2 toxin cause severe problems for agriculture, as well as for veterinary medicine. As liver is one of the key organs in metabolism, the main aim of our study was to investigate the immunomodulatory and cytotoxic effects of T-2 toxin, using primary hepatocyte mono-culture and hepatocyte-nonparenchymal cell (predominantly Kupffer cell) co-culture models of chicken. Cultures were exposed to 10 (T10 group), 100 (T100 group) and 1000 (T1000 group) nmol/L T-2 toxin treatment for 8 or 24 h. Alterations of cellular metabolic activity, the production of reactive oxygen species (extracellular H2O2), heat shock protein 70 (HSP70), and the concentration of different inflammatory cytokines such as interleukin (IL-)6 and IL-8 were investigated. Metabolic activity was intensely decreased by T-2 toxin administration in all of the cell culture models, in every applied concentration and incubation time. Concentrations of HSP70 and IL-8 were significantly increased in hepatocyte mono-cultures exposed to higher T-2 toxin levels (both in T100 and T1000 groups for HSP70 and in T1000 group for IL-8, respectively) compared to controls after 24 h incubation. Similarly, IL-6 levels were also significantly elevated in the T100 and T1000 groups in both of mono- and co-cultures, but only after 8 h of incubation time. In spite of the general harmful effects of T-2 toxin treatment, no significant differences were observed on reactive oxygen species production. Furthermore, the two cell culture models showed different levels of H2O2, HSP70, and IL-8 concentrations independently of T-2 toxin supplementation. In conclusion, the established primary cell cultures derived from chicken proved to be proper models to study the specific molecular effects caused by T-2 toxin. Metabolic activity and immune status of the different examined cell cultures were intensively affected; however, no changes were found in H2O2 levels.

T-2 toxin upregulates the expression of human cytochrome P450 1A1 (CYP1A1) by enhancing NRF1 and Sp1 interaction

T-2 toxin is a major pollutant in crops and feedstuffs. Due to its high toxicity in a variety of organisms, T-2 toxin is of great concern as a threat to humans and to animal breeding. Overexpression of CYP1A1 may contribute to carcinogenesis, and CYP1A1 may be a promising target for the prevention and treatment of human malignancies. Therefore, it is essential to understand the regulatory mechanism by which T-2 toxin induces CYP1A1 expression in human cells. In this study, we confirmed that T-2 toxin (100 ng/mL) induced the expression of CYP1A1 in HepG2 cells through NRF1 and Sp1 bound to the promoter instead of through the well-recognized Aromatic hydrocarbon receptors (AhR). In cells treated with T-2 toxin, Sp1, but not NRF1, was significantly upregulated. However, T-2 toxin apparently promoted the interaction between NRF1 and Sp1 proteins, as revealed by IP analysis. Furthermore, in T-2 toxin-treated HepG2 cells, nuclear translocation of NRF1 was enhanced, while knockdown of Sp1 ablated NRF1 nuclear enrichment. Our results revealed that the upregulation of CYP1A1 by T-2 toxin in HepG2 cells depended on enhanced interaction between Sp1 and NRF1. This finding suggests the tumorigenic features of T-2 toxin might be related to the CYP1A1, which provides new insights to understand the toxicological effect of T-2 toxin.

Mycotoxins: cytotoxicity and biotransformation in animal cells

Mycotoxins are secondary metabolites produced by many microfungi. Hitherto, over 300 mycotoxins with diverse structures have been identified. They contaminate most cereals and feedstuffs, which threaten human and animal health by exerting acute, sub-acute and chronic toxicological effects, with some considered as carcinogens. Many mycotoxins at low concentrations are able to induce the expression of cytochrome P450 and other enzymes implicated in the biotransformation and metabolization of mycotoxins in vivo and in vitro. Mycotoxins and their metabolites elicit different cellular disorders and adverse effects such as oxidative stress, inhibition of translation, DNA damage and apoptosis in host cells, thus causing various kinds of cytotoxicities. In this review, we summarize the biotransformation of mycotoxins in animal cells by CYP450 isoforms and other enzymes, their altered expression under mycotoxin exposure, and recent progress in mycotoxin cytotoxicity in different cell lines. Furthermore, we try to generalize the molecular mechanisms of mycotoxin effects in human and animal cells.

The naturally born fusariotoxin enniatin B and sorafenib exert synergistic activity against cervical cancer in vitro and in vivo

During the last decades substantial progress has been made in developing systemic cancer therapy. However, tumors are frequently intrinsically resistant against structurally and mechanistically unrelated drugs. Thus, it is of predominant interest to overcome drug resistance and to encourage the research for novel chemotherapeutic approaches. Recently, we have introduced enniatins, naturally occurring cyclohexadepsipeptides produced by filamentous fungi of the genus Fusarium, as potential anticancer drugs. Here, we expend this approach by demonstrating antiangiogenic properties for enniatin B (Enn B) indicated by a strong inhibition of human endothelial cell migration and tube formation. Moreover, combination of Enn B with the clinically approved multi-kinase inhibitor sorafenib (Sora) displayed profound synergistic in vitro and in vivo anticancer effects against cervical cancer. Subsequent studies showed that this strong synergism is accompanied by a marked increase in mitochondrial injury and apoptosis induction reflected by mitochondrial membrane depolarization, caspase-7 activation, and subsequent cleavage of PARP. Additionally, cells were shown to stop DNA synthesis and accumulate in S and G2/M phase of the cell cycle. The multifaceted characteristics underlying this strong synergism were suggested to be based on interference with the p38 MAPK as well as the ERK signaling pathways. Finally, also in vivo studies revealed that the combination treatment is distinctly superior to single drug treatments against the KB-3-1 cervix carcinoma xenograft model. Taken together, our data confirm the anticancer benefits of the naturally occurring fusariotoxin Enn B and further present Enn B/Sora as a novel combination strategy especially for the treatment of cervical cancer.

Crosstalk of JNK1-STAT3 is critical for RAW264.7 cell survival

T-2 toxin, a major compound of trichothecenes, inhibits protein synthesis and induces inflammation and cell apoptosis through the activation of MAPK pathway. The JAK/STAT pathway has recently been shown to be downstream targets of trichothecenes. However, whether there is any crosstalk between JNK and JAK/STAT pathways in trichothecene toxicity has not been studied. In the present study, we explored this potential in RAW264.7 cells treated with T-2 toxin. Our results revealed a crosstalk between JNK1 and STAT3 after T-2 toxin treatment, which was mediated by K-Ras. T-2 toxin treatment resulted in rapid phosphorylation, and more importantly, JNK1-STAT3 signaling pathway was shown to maintain the normal function of the mitochondria and to inhibit T-2 toxin-induced apoptosis. Therefore, this pathway was considered to be a potential cell survival pathway. Breakdown and degranulation of ribosomes in the rough endoplasmic reticulum and swelling of mitochondria were clearly visible after the cells had been incubated with T-2 toxin for 12h. Our data suggest that T-2 toxin had a Janus face: it induced both apoptotic and cell survival pathways. These results suggest that the crosstalk and the balance between MAPK and JAK/STAT pathway might be involved in T-2 toxin-induced apoptosis in RAW264.7 cells.

Oxidative stress-mediated cytotoxicity and metabolism of T-2 toxin and deoxynivalenol in animals and humans: an update

Trichothecenes are a large family of structurally related toxins mainly produced by Fusarium genus. Among the trichothecenes, T-2 toxin and deoxynivalenol (DON) cause the most concern due to their wide distribution and highly toxic nature. Trichothecenes are known for their inhibitory effect on eukaryotic protein synthesis, and oxidative stress is one of their most important underlying toxic mechanisms. They are able to generate free radicals, including reactive oxygen species, which induce lipid peroxidation leading to changes in membrane integrity, cellular redox signaling, and in the antioxidant status of the cells. The mitogen-activated protein kinases signaling pathway is induced by oxidative stress, which also induces caspase-mediated cellular apoptosis pathways. Several new metabolites and novel metabolic pathways of T-2 toxin have been discovered very recently. In human cell lines, HT-2 and neosolaniol (NEO) are the major metabolites of T-2 toxin. Hydroxylation on C-7 and C-9 are two novel metabolic pathways of T-2 toxin in rats. The metabolizing enzymes CYP3A22, CYP3A29, and CYP3A46 in pigs, as well as the enzymes CYP1A5 and CYP3A37 in chickens, are able to catalyze T-2 toxin and HT-2 toxin to form the C-3'-OH metabolites. Similarly to carboxylesterase, CYP3A29 possesses the hydrolytic ability in pigs to convert T-2 toxin to NEO. T-2 toxin is able to down- or upregulate cytochrome P-450 enzymes in different species. The metabolism of DON in humans is region-dependent. Free DON and DON-glucuronide are considered to be the biomarkers for humans. The masked mycotoxin DON-3-β-D-glucoside can be hydrolyzed to free DON in the body. This review will provide useful information on the progress of oxidative stress as well as on the metabolism and the metabolizing enzymes of T-2 toxin and DON. Moreover, the literature will throw light on the blind spots of metabolism and toxicological studies in trichothecenes that have to be explored in the future.

Cell-based models for mycotoxin screening and toxicity evaluation: an update

This review presents the applications of cell-based models in mycotoxin research, with a focus on models for mycotoxin screening and cytotoxicity evaluation. Various cell-based models, cell and cell culture condition related factors, toxicity endpoints and culture systems as well as predictive value of cell-based bioassays are reviewed. Advantages, drawbacks and technical problems regarding set up and validation of consistent, robust, reproducible and high-throughput cell-based models are discussed. Various cell-based models have been developed and used as screening tests for mycotoxins but the data obtained are difficult to compare. However, the results highlight the potential of cell-based models as promising in vitro platforms for the initial screening and cytotoxicity evaluation of mycotoxins and as a significant analytical approach in mycotoxin research before any animal or human clinical studies. To develop cell-based models as powerful high-throughput laboratory platforms for the analysis of large numbers of samples, there are mainly two fundamental requirements that should be met, i.e. the availability of easy-to-use and, if possible, automated cell platforms and the possibility to obtain reproducible results that are comparable between laboratories. The transition from a research model to a test model still needs optimisation, standardisation, and validation of analytical protocols. The validation of a cell-based bioassay is a complex process, as several critical points, such as the choice of the cellular model, the assay procedures, and the appropriate use and interpretation of the results, must be strictly defined to ensure more consistency in the results. The development of cell-based models exploring the third dimension together with automation and miniaturisation will bring cellular platforms to a level appropriate for cost-effective and large-scale analysis in the field of mycotoxin research.

Toxic effects of dietary exposure to T-2 toxin on intestinal and hepatic biotransformation enzymes and drug transporter systems in broiler chickens

The effects of the mycotoxin T-2 on hepatic and intestinal drug-metabolizing enzymes (cytochrome P450) and drug transporter systems (MDR1 and MRP2) in poultry were investigated during this study. Broiler chickens received either uncontaminated feed, feed contaminated with 68μg/kg or 752μg/kg T-2 toxin. After 3weeks, the animals were euthanized and MDR1, MRP2, CYP1A4, CYP1A5 and CYP3A37 mRNA expression were analyzed using qRT-PCR. Along the entire length of the small intestine no significant differences were observed. In the liver, genes coding for CYP1A4, CYP1A5 and CYP3A37 were significantly down-regulated in the group exposed to 752μg/kg T-2. For CYP1A4, even a contamination level of 68μg/kg T-2 caused a significant decrease in mRNA expression. Expression of MDR1 was not significantly decreased in the liver. In contrast, hepatic MRP2 expression was significantly down-regulated after exposure to 752μg/kg T-2. Hepatic and intestinal microsomes were prepared to test the enzymatic activity of CYP3A. In the ileum and liver CYP3A activity was significantly increased in the group receiving 752μg/kg T-2 compared to the control group. The results of this study show that drug metabolizing enzymes and drug transporter mechanisms can be influenced due to prolonged exposure to relevant doses of T-2.

Trichothecene toxicity in eukaryotes: cellular and molecular mechanisms in plants and animals

Trichothecenes are sesquiterpenoid mycotoxins commonly found as contaminants in cereal grains and are a major health and food safety concern due to their toxicity to humans and farm animals. Trichothecenes are predominantly produced by the phytopathogenic Fusarium fungus, and in plants they act as a virulence factor aiding the spread of the fungus during disease development. Known for their inhibitory effect on eukaryotic protein synthesis, trichothecenes also induce oxidative stress, DNA damage and cell cycle arrest and affect cell membrane integrity and function in eukaryotic cells. In animals, trichothecenes can be either immunostimulatory or immunosuppressive and induce apoptosis via mitochondria-mediated or -independent pathway. In plants, trichothecenes induce programmed cell death via production of reactive oxygen species. Recent advances in molecular techniques have led to the elucidation of signal transduction pathways that manifest trichothecene toxicity in eukaryotes. In animals, trichothecenes induce mitogen-activated protein kinase (MAPK) signalling cascades via ribotoxic stress response and/or endoplasmic reticulum stress response. The upstream signalling events that lead to the activation trichothecene-induced ribotoxic stress response are discussed. In plants, trichothecenes exhibit elicitor-like activity leading to the inductions MAPKs and genes involved in oxidative stress, cell death and plant defence response. Trichothecenes might also modulate hormone-mediated defence signalling and abiotic stress signalling in plants.

T-2 toxin induced Salmonella Typhimurium intoxication results in decreased Salmonella numbers in the cecum contents of pigs, despite marked effects on Salmonella-host cell interactions

The mycotoxin T-2 toxin and Salmonella Typhimurium infections pose a significant threat to human and animal health. Interactions between both agents may result in a different outcome of the infection. Therefore, the aim of the presented study was to investigate the effects of low and relevant concentrations of T-2 toxin on the course of a Salmonella Typhimurium infection in pigs. We showed that the presence of 15 and 83 μg T-2 toxin per kg feed significantly decreased the amount of Salmonella Typhimurium bacteria present in the cecum contents, and a tendency to a reduced colonization of the jejunum, ileum, cecum, colon and colon contents was noticed. In vitro, proteomic analysis of porcine enterocytes revealed that a very low concentration of T-2 toxin (5 ng/mL) affects the protein expression of mitochondrial, endoplasmatic reticulum and cytoskeleton associated proteins, proteins involved in protein synthesis and folding, RNA synthesis, mitogen-activated protein kinase signaling and regulatory processes. Similarly low concentrations (1-100 ng/mL) promoted the susceptibility of porcine macrophages and intestinal epithelial cells to Salmonella Typhimurium invasion, in a SPI-1 independent manner. Furthermore, T-2 toxin (1-5 ng/mL) promoted the translocation of Salmonella Typhimurium over an intestinal porcine epithelial cell monolayer. Although these findings may seem in favour of Salmonella Typhimurium, microarray analysis showed that T-2 toxin (5 ng/mL) causes an intoxication of Salmonella Typhimurium, represented by a reduced motility and a downregulation of metabolic and Salmonella Pathogenicity Island 1 genes. This study demonstrates marked interactions of T-2 toxin with Salmonella Typhimurium pathogenesis, resulting in bacterial intoxication.