Effects of chronic deoxynivalenol exposure on p53 heterozygous and p53 homozygous mice

Identification and characterization of Achromobacter spanius P-9 and elucidation of its deoxynivalenol-degrading potential

Deoxynivalenol (DON) poses significant challenges due to its frequent contamination of grains and associated products. Microbial strategies for mitigating DON toxicity showed application potential. Eight bacterial isolates with DON degradation activity over 5% were obtained from various samples of organic fertilizer in this study. One of the isolates emerged as a standout, demonstrating a substantial degradation capability, achieving a 99.21% reduction in DON levels. This isolate, underwent thorough morphological, biochemical, and molecular characterization to confirm its identity, and was identified as a new strain of Achromobacter spanius P-9. Subsequent evaluations revealed that the strain P-9 retains its degradation activity after a 24-h incubation, reaching optimal performance at 35 °C with a pH of 8.0. Further studies indicated that Ca2+ ions enhance the degradation process, whereas Zn2+ ions exert an inhibitory effect. This is the pioneering report of DON degradation by Achromobacter spanius, illuminating its prospective utility in addressing DON contamination challenges.

Hazard characterisation for significant mycotoxins in food

This review updates the current status of activities related to hazard characterisation for mycotoxins, with special reference to regulatory work accomplished within the European Union. Because the relevant information on these topics is widely scattered in the scientific literature, this review intends to provide a condensed overview on the most pertinent aspects. Human health risk assessment is a procedure to estimate the nature and potential for harmful effects of mycotoxins on human health due to exposure to them via contaminated food. This assessment involves hazard identification, hazard characterisation, exposure assessment, and risk characterisation. Mycotoxins covered in this review are aflatoxins, ochratoxin A, cyclopiazonic acid, citrinin, trichothecenes (deoxynivalenol, nivalenol, T-2, and HT-2 toxins), fumonisins, zearalenone, patulin, and ergot alkaloids. For mycotoxins with clear genotoxic/carcinogenic properties, the focus is on the margin of exposure approach. One of its goals is to document predictive characterisation of the human hazard, based on studies in animals using conditions of low exposure. For the other, non-genotoxic toxins, individual 'no adverse effect levels' have been established, but structural analogues or modified forms may still complicate assessment. During the process of hazard characterisation, each identified effect is assessed for human relevance. The estimation of a 'safe dose' is the hazard characterisation endpoint. The final aim of all of these activities is to establish a system, which is able to minimise and control the risk for the consumer from mycotoxins in food. Ongoing research on mycotoxins constantly comes up with new findings, which may have to be implemented into this system.

Effect of the mycotoxin deoxynivalenol in combinational therapy with TRAIL on prostate cancer cells

Tumor necrosis factor-related apoptosis-induced ligand (TRAIL) is reported as a promising anti-cancer therapeutic target. Unfortunately, prostate cancer cells (PCa) are partially resistant to TRAIL-induced apoptosis limiting its therapeutic potential. The existing body of knowledge suggests that naturally produced compounds, such as mycotoxin deoxynivalenol (DON), might potentially sensitize cells to TRAIL treatment and improve the efficiency of therapy. Previously, we observed that DON induces oxidative stress and apoptosis in PCa cell lines. Thus we addressed here whether DON can sensitize PCa cells to TRAIL-induced apoptosis. Our data demonstrates that three out of four tested PCa cell lines pretreated with DON increased TRAIL-induced apoptosis detected with flow cytometry. This effect was associated with oxidative stress (LNCaP and DU-145 cell line) and elevated DNA damage (DU-145, LNCaP, and 22Rv1 cell lines). Next, in the animal model we inoculated PC tumor to SCKID mice followed by administration of DON intraperitoneally and/or TRIAL intravenously. During 21 days monitoring of tumor growth, the animals received 7 doses of DON, TRAIL, DON+TRAIL or control injections. No significant reduction in tumor mass was observed after combinational treatment of TRAIL and DON compared to 1 μg/kg of body weight DON treatment alone, which itself decreased the tumor growth. However, despite the lack of the TRAIL + DON effect, DON itself inducing apoptosis is an interesting compound worth investigating in the context of other combination therapies.

Strategies for Improving Photodynamic Therapy Through Pharmacological Modulation of the Immediate Early Stress Response

Photodynamic therapy (PDT) is a minimally to noninvasive treatment modality that has emerged as a promising alternative to conventional cancer treatments. PDT induces hyperoxidative stress and disrupts cellular homeostasis in photosensitized cancer cells, resulting in cell death and ultimately removal of the tumor. However, various survival pathways can be activated in sublethally afflicted cancer cells following PDT. The acute stress response is one of the known survival pathways in PDT, which is activated by reactive oxygen species and signals via ASK-1 (directly) or via TNFR (indirectly). The acute stress response can activate various other survival pathways that may entail antioxidant, pro-inflammatory, angiogenic, and proteotoxic stress responses that culminate in the cancer cell's ability to cope with redox stress and oxidative damage. This review provides an overview of the immediate early stress response in the context of PDT, mechanisms of activation by PDT, and molecular intervention strategies aimed at inhibiting survival signaling and improving PDT outcome.

l-Carnosine Protects Against Deoxynivalenol-Induced Oxidative Stress in Intestinal Stem Cells by Regulating the Keap1/Nrf2 Signaling Pathway

SCOPE

The intestinal epithelium is nourished by various nutrients and subjected to persistent and widespread feed-derived mycotoxin stress. l-Carnosine (LC) possesses robust antioxidant activity; however, its role in protecting intestinal mucosa against deoxynivalenol (DON) is still unclear.

METHODS AND RESULTS

In this study, 300 mg kg-1 BW LC and 3 mg kg-1 BW DON are orally administered to mice either alone or in combination for 10 days to investigate the role of LC in protecting the intestine against DON. This study found that LC alleviates the growth retardation of mice and repairs the damaged jejunal structure and barrier functions under DON exposure. LC rescues the intestinal stem cells (ISCs), increases the growth advantage in enteroids derived from jejunal crypts of mice in each group ex vivo, improves the proliferation and apoptosis of intestinal cells, and promotes ISC differentiation into absorptive cells, goblet cells, and Paneth cells. Furthermore, LC activates Nrf2 signaling by binding to Keap1 to reverse the striking DON-induced increase in ROS levels.

CONCLUSION

The study findings unveil that LC potentiates the antioxidant capacity of ISCs by regulating the Keap1/Nrf2 signaling pathway, which contributes to the intestinal epithelial regeneration response to DON insult.

Deoxynivalenol Modulates the Viability, ROS Production and Apoptosis in Prostate Cancer Cells

Deoxynivalenol (DON), known as vomitoxin, a type B trichothecene, is produced by Fusarium. DON frequently contaminates cereal grains such as wheat, maize, oats, barley, rye, and rice. At the molecular level, it induces ribosomal stress, inflammation and apoptosis in eukaryotic cells. Our findings indicate that DON modulates the viability of prostate cancer (PCa) cells and that the response to a single high dose of DON is dependent on the androgen-sensitivity of cells. DON appears to increase reactive oxygen species (ROS) production in cells, induces DNA damage, and triggers apoptosis. The effects of DON application in PCa cells are influenced by the mitogen-activated protein kinase (MAPK) and NFΚB- HIF-1α signaling pathways. Our results indicate that p53 is a crucial factor in DON-associated apoptosis in PCa cells. Taken together, our findings show that a single exposure to high concentrations of DON (2-5 µM) modulates the progression of PCa.

Pyrrolidine Dithiocarbamate (PDTC) Inhibits DON-Induced Mitochondrial Dysfunction and Apoptosis via the NF-κB/iNOS Pathway

Oxidative stress is closely linked to the toxic responses of various cell types in normal and pathophysiological conditions. Deoxynivalenol (DON), an inducer of stress responses in the ribosome and the endoplasmic reticulum (ER), causes mitochondrial dysfunction and mitochondria-dependent apoptosis through oxidative stress in humans and animals. The NF-κB pathway, which is closely linked to oxidative stress, is hypothesized to be a critical signaling pathway for DON-induced toxicity and is a potential target for intervention. The present study was conducted to explore the protective effects of pyrrolidine dithiocarbamate (PDTC) from the toxic effects of DON in rat anterior pituitary GH3 cells. Our results showed that DON activated the NF-κB transcription factors and induced cellular oxidative stress, mitochondrial dysfunction, and apoptosis. Morphological studies using transmission electron microscopy (TEM) and cell apoptosis analyses suggested that PDTC prevented DON-induced mitochondrial dysfunction and apoptosis, probably by preventing the DON-induced translocation of NF-κB p65 into the nucleus, and by inhibiting DON-induced iNOS expression. This led to the blocking of the NF-κB pathway and inhibition of iNOS activity.

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.

The Food Contaminant Deoxynivalenol Exacerbates the Genotoxicity of Gut Microbiota

An increasing number of human beings from developed countries are colonized by Escherichia coli strains producing colibactin, a genotoxin suspected to be associated with the development of colorectal cancers. Deoxynivalenol (DON) is the most prevalent mycotoxin that contaminates staple food-especially cereal products-in Europe and North America. This study investigates the effect of the food contaminant DON on the genotoxicity of the E. coli strains producing colibactin. In vitro, intestinal epithelial cells were coexposed to DON and E. coli producing colibactin. In vivo, newborn rats colonized at birth with E. coli producing colibactin were fed a DON-contaminated diet. Intestinal DNA damage was estimated by the phosphorylation of histone H2AX. DON exacerbates the genotoxicity of the E. coli producing colibactin in a time- and dose-dependent manner in vitro Although DON had no effect on the composition of the gut microbiota, and especially on the number of E. coli, a significant increase in DNA damage was observed in intestinal epithelial cells of animals colonized by E. coli strains producing colibactin and coexposed to DON compared to animals colonized with E. coli strains unable to produce colibactin or animals exposed only to DON. In conclusion, our data demonstrate that the genotoxicity of E. coli strains producing colibactin, increasingly present in the microbiota of asymptomatic human beings, is modulated by the presence of DON in the diet. This raises questions about the synergism between food contaminants and gut microbiota with regard to intestinal carcinogenesis.IMPORTANCE An increasing number of human beings from developed countries are colonized by Escherichia coli strains producing colibactin, a genotoxin suspected to be associated with the development of colorectal cancers. Deoxynivalenol (DON) is the most prevalent mycotoxin that contaminates staple food-especially cereal products-in Europe and North America. Our in vitro and in vivo results demonstrate that the intestinal DNA damage induced by colibactin-producing E. coli strains was exacerbated by the presence of DON in the diet. This raises questions about the synergism between food contaminants and gut microbiota with regard to intestinal carcinogenesis.