Dietary Exposure to the Food Contaminant Deoxynivalenol Triggers Colonic Breakdown by Activating the Mitochondrial and the Death Receptor Pathways

Lycopene alleviates Deoxynivalenol-induced toxicity in Porcine intestinal epithelial cells by mediating mitochondrial function

Deoxynivalenol (DON) is widely found in food and feed, posing a threat to human and animal health. Lycopene (Lyc) is a natural plant extracts with significant antioxidant properties. This study was conducted to investigate the protective effects of Lyc on IPEC-J2 cells upon DON exposure. The detection of cell viability and trypan blue staining showed that Lyc alleviated cell damage and decreased cell apoptotic rate induced by DON. The analysis of reactive oxygen species (ROS) level and antioxidant parameter measurements showed that Lyc significantly down-regulated the content of ROS and restored antioxidant enzyme activity. Furthermore, mitochondrial membrane potential (ΔΨm) detection, mitochondrial DNA copy number (mtDNAcn) assay and adenosine triphosphate (ATP) concentration detection showed Lyc improved mitochondrial function after DON exposure. The results of transcriptome analysis, ROS detection and CCK8 assay suggested that Lyc may activated the oxidative phosphorylation (OXPHOS) to improve mitochondrial function. Conclusively, our results suggested that Lyc alleviated DON-induced oxidative stress by improving mitochondrial function through OXPHOS signaling pathway.

Individual cytotoxicity of three major type A trichothecene, T-2, HT-2, and diacetoxyscirpenol in human Jurkat T cells

Mycotoxins are toxic, fungal secondary metabolites that contaminate agricultural commodities, food, and feed. Among them, T-2, HT-2, and diacetoxyscirpenol (DAS; the major type A trichothecene) are primarily produced from Fusarium species. These mycotoxins exert numerous toxicological effects in animals and humans, such as dermatotoxicity, haematotoxicity, hepatotoxicity, nephrotoxicity, neurotoxicity, and immunotoxicity. In the present study, human Jurkat T cells were used as a model to investigate apoptotic cell death induced by T-2, HT-2, and DAS. The results showed that T-2, HT-2, and DAS decreased cell viability and increased production of Reactive Oxygen Species in a time- and dose-dependency. Based on their IC50 values, they could be ranked in decreasing order of cytotoxicity as T-2 > HT-2 > DAS. All tested mycotoxins caused DNA fragmentation, up-regulated cytochrome C, caspase 3, and caspase 9 mRNA levels, and down-regulated the relative expression of Bcl-2 and caspase 8. The effects of these trichothecenes on apoptosis were determined based on flow cytometry. At the IC50 concentrations, the percentages of apoptotic cells were significantly higher than for the controls. Taken together, these data suggested that T-2, HT-2, and DAS could induce apoptosis through the mitochondrial apoptotic pathway.

Deoxynivalenol Exposure Induced Colon Damage in Mice Independent of the Gut Microbiota

SCOPE

To investigate whether deoxynivalenol (DON) can induce intestinal damage through gut microbiota in mice.

METHODS AND RESULTS

Mice are orally administered DON (1 mg kg-1 bw day-1 ) for 4 weeks, and then recipient mice receive fecal microbiota transplantation (FMT) from DON-exposed mice after antibiotic treatment. Furthermore, the mice are orally treated with DON (1 mg kg-1 bw day-1 ) for 4 weeks after antibiotic treatment. Histological damage, disruption of tight junction protein expression, and increased oxidative stress and apoptosis in the colon as well as higher serum lipopolysaccharides are observed after DON exposure. Moreover, DON exposure changes the composition and diversity of the gut microbiota as well as the contents of fecal metabolites (mainly bile acids). Differential metabolic pathways may be related to mitochondrial metabolism, apoptosis, and inflammation following DON exposure. However, only a decrease in mRNA levels of occludin and claudin-3 is observed in the colon of recipient mice after FMT. After depleting the gut microbiota in mice, DON exposure can also cause histological damage, disorders of tight junction protein expression, and increased oxidative stress and apoptosis in the colon.

CONCLUSIONS

DON exposure can induce colon damage in mice independent of the gut microbiota.

From ribosome to ribotoxins: understanding the toxicity of deoxynivalenol and Shiga toxin, two food borne toxins

Ribosomes that synthesize proteins are among the most central and evolutionarily conserved organelles. Given the key role of proteins in cellular functions, prokaryotic and eukaryotic pathogens have evolved potent toxins to inhibit ribosomal functions and weaken their host. Many of these ribotoxin-producing pathogens are associated with food. For example, food can be contaminated with bacterial pathogens that produce the ribotoxin Shiga toxin, but also with the fungal ribotoxin deoxynivalenol. Shiga toxin cleaves ribosomal RNA, while deoxynivalenol binds to and inhibits the peptidyl transferase center. Despite their distinct modes of action, both groups of ribotoxins hinder protein translation, but also trigger other comparable toxic effects, which depend or not on the activation of the ribotoxic stress response. Ribotoxic stress response-dependent effects include inflammation and apoptosis, whereas ribotoxic stress response-independent effects include endoplasmic reticulum stress, oxidative stress, and autophagy. For other effects, such as cell cycle arrest and cytoskeleton modulation, the involvement of the ribotoxic stress response is still controversial. Ribotoxins affect one organelle yet induce multiple toxic effects with multiple consequences for the cell. The ribosome can therefore be considered as the cellular "Achilles heel" targeted by food borne ribotoxins. Considering the high toxicity of ribotoxins, they pose a substantial health risk, as humans are highly susceptible to widespread exposure to these toxins through contaminated food sources.

Sodium butyrate alleviates deoxynivalenol-induced porcine intestinal barrier disruption by promoting mitochondrial homeostasis via PCK2 signaling

Deoxynivalenol (DON) is one of the most plentiful trichothecenes occurring in food and feed, which brings severe health hazards to both animals and humans. This study aims to investigate whether sodium butyrate (NaB) can protect the porcine intestinal barrier from DON exposure through promoting mitochondrial homeostasis. In a 4-week feeding experiment, 28 male piglets were allocated according to a 2 by 2 factorial arrangement of treatments with the main factors including supplementation of DON (< 0.8 vs. 4.0 mg/kg) and NaB (0.0 vs. 2 g/kg) in a corn/soybean-based diet. Dietary NaB supplementation mitigated the damaged mitochondrial morphology within the jejunal mucosa and the disrupted gut epithelial tight junctions irritated by DON. In IPEC-J2 cells, we found efficient recovery of the intestinal epithelial barrier occurred following NaB administration. This intestinal barrier reparation was facilitated by NaB-induced PCK2-mediated glyceroneogenesis and restoration of mitochondrial structure and function. In conclusion, we elucidated a mechanism of PCK2-mediated improvement of mitochondrial function by NaB to repair porcine intestinal barrier disruption during chronic DON exposure. Our findings highlight the promise of NaB for use in protecting against DON-induced gut epithelial tight junction disruption in piglets.

Emerging mycotoxins induce hepatotoxicity in pigs' precision-cut liver slices and HepG2 cells

Emerging mycotoxins are currently gaining more attention due to their high frequency of contamination in foods and grains. However, most data available in the literature are in vitro, with few in vivo results that prevent establishing their regulation. Beauvericin (BEA), enniatins (ENNs), emodin (EMO), apicidin (API) and aurofusarin (AFN) are emerging mycotoxins frequently found contaminating food and there is growing interest in studying their impact on the liver, a key organ in the metabolization of these components. We used an ex vivo model of precision-cut liver slices (PCLS) to verify morphological and transcriptional changes after acute exposure (4 h) to these mycotoxins. The human liver cell line HepG2 was used for comparison purposes. Most of the emerging mycotoxins were cytotoxic to the cells, except for AFN. In cells, BEA and ENNs were able to increase the expression of genes related to transcription factors, inflammation, and hepatic metabolism. In the explants, only ENN B1 led to significant changes in the morphology and expression of a few genes. Overall, our results demonstrate that BEA, ENNs, and API have the potential to be hepatotoxic.

Zearalenone Exposure Disrupts STAT-ISG15 in Rat Colon: A Potential Linkage between Zearalenone and Inflammatory Bowel Disease

Zearalenone (ZEN), a prevalent mycotoxin contaminating food and known for its intestinal toxicity, has been suggested as a potential risk factor for inflammatory bowel disease (IBD), although the exact relationship between ZEN exposure and IBD remains unclear. In this study, we established a rat model of colon toxicity induced by ZEN exposure to investigate the key targets of ZEN-induced colon toxicity and explore the underlying connection between ZEN exposure and IBD. Histological staining of the rat colon revealed significant pathological changes resulting from ZEN exposure (p < 0.01). Furthermore, the proteomic analysis demonstrated a notable upregulation of protein expression levels, specifically STAT2 (0.12 ± 0.0186), STAT6 (0.36 ± 0.0475) and ISG15 (0.43 ± 0.0226) in the rat colon (p < 0.05). Utilizing bioinformatics analysis, we combined ZEN exposure and IBD clinical sample databases to reveal that ZEN exposure may increase the risk of IBD through activation of the STAT-ISG15 pathway. This study identified novel targets for ZEN-induced intestinal toxicity, providing the basis for further study of ZEN exposure to IBD.

A novel toxic effect of foodborne trichothecenes: The exacerbation of genotoxicity

Trichothecenes (TCT) are very common mycotoxins. While the effects of DON, the most prevalent TCT, have been extensively studied, less is known about the effect of other trichothecenes. DON has ribotoxic, pro-inflammatory, and cytotoxic potential and induces multiple toxic effects in humans and animals. Although DON is not genotoxic by itself, it has recently been shown that this toxin exacerbates the genotoxicity induced by model or bacterial genotoxins. Here, we show that five TCT, namely T-2 toxin (T-2), diacetoxyscirpenol (DAS), nivalenol (NIV), fusarenon-X (FX), and the newly discovered NX toxin, also exacerbate the DNA damage inflicted by various genotoxins. The exacerbation was dose dependent and observed with phleomycin, a model genotoxin, captan, a pesticide with genotoxic potential, and colibactin, a bacterial genotoxin produced by the intestinal microbiota. For this newly described effect, the trichothecenes ranked in the following order: T-2>DAS > FX > NIV ≥ DON ≥ NX. The genotoxic exacerbating effect of TCT correlated with their ribotoxic potential, as measured by the inhibition of protein synthesis. In conclusion, our data demonstrate that TCT, which are not genotoxic by themselves, exacerbate DNA damage induced by various genotoxins. Therefore, foodborne TCT could enhance the carcinogenic potential of genotoxins present in the diet or produced by intestinal bacteria.

Curcumin mitigates deoxynivalenol-induced intestinal epithelial barrier disruption by regulating Nrf2/p53 and NF-κB/MLCK signaling in mice

Deoxynivalenol (DON) induces intestinal epithelial barrier disruption, posing a threat to the body. Curcumin (Cur) possesses pharmacological bioactivities such as antioxidant and anti-inflammatory effects that help maintain intestinal health. Here, the protective effects of Cur against DON-induced intestinal epithelial barrier disruption were explored. Cur (75 or 150 mg/kg body weight [B.W.]) alleviated DON-induced (2.4 mg/kg B.W.) inhibition of growth performance and morphological damage to intestinal epithelium in mice. Cur also significantly attenuated DON-induced intestinal epithelial barrier disruption and structural damage to the tight junctions (TJs), as assessed by ultrastructure observation, serum FITC-dextran concentrations and diamine oxidase activity. Cur mitigated the DON-induced increase in reactive oxygen species, malondialdehyde and 8-hydroxy-2'-deoxyguanosine levels; p53, cytoplasmic cytochrome c, Bax, and Bcl-2 expression; and TUNEL-positive cell rate and caspase-3 activity. It decreased the total antioxidant capacity and expression of nuclear Nrf2 and its downstream target genes. Lastly, Cur attenuated the DON-induced increase in MLCK, p-MLC, nuclear NF-κB p65 expression, and the NF-κB downstream target genes; decrease in the expression of TJs proteins (claudin-1, occludin, and zonula occludens-1 [ZO-1]); and abnormal ZO-1 distribution. Overall, Cur mitigated the DON-induced disruption of the intestinal epithelial barrier by regulating the Nrf2/p53-mediated apoptotic pathway and NF-κB/MLCK-mediated TJs pathway in mice.

Exposure of intestinal explants to NX, but not to DON, enriches the secretome in mitochondrial proteins

NX is a type A trichothecene produced by Fusarium graminearum with limited information on its toxicity. NX is structurally similar to deoxynivalenol (DON), only differing by the lacking keto group at C8. Because of the structural similarity of the two toxins as well as their potential co-occurrence in food and feed, it is of interest to determine the toxicity of this new compound. In this study, we compared the protein composition of the extracellular media of pig intestinal explants (secretome) exposed to 10 µM of DON or NX for 4 h compared with controls. The combination of two complementary quantitative proteomic approaches (a gel-based and a gel-free approach) identified 18 and 23 differentially abundant proteins (DAPs) for DON and NX, respectively, compared to controls. Functional analysis suggested that, whereas DON toxicity was associated with decreased cell viability and cell destruction, NX toxicity was associated with an enrichment of mitochondrial proteins in the secretome. The presence of these proteins may be associated with the already known ability of NX to induce an intestinal inflammation. Overall, our results indicated that DON- and NX-induced changes in the extracellular proteome of intestinal explants are different. The increased leakage/secretion of mitochondrial proteins by NX may be a feature of NX toxicity.

The foodborne contaminant deoxynivalenol exacerbates DNA damage caused by a broad spectrum of genotoxic agents

Humans are exposed to different contaminants including mycotoxins. Deoxynivalenol (DON), a potent ribosome inhibitor, is a highly prevalent mycotoxin in the food chain worldwide. Although DON is not genotoxic, we previously showed that it exacerbates the genotoxicity of colibactin, a DNA-crosslinking toxin produced by bacteria in the gut. In the present study, we investigated whether this phenotype can be extended to other genotoxic compounds with different modes of action. Our data showed that, at a dose that can be found in food, DON exacerbated the DNA damage caused by etoposide, cisplatin and phleomycin. In contrast, de-epoxy-deoxynivalenol (DOM-1), a modified form of DON that does not induce ribotoxic stress, did not exacerbate DNA damage. The effect of DON was mimicked with other ribosome inhibitors such as anisomycin and cycloheximide, suggesting that ribotoxicity plays a key role in exacerbating DNA damage. In conclusion, a new effect of DON was identified, this toxin aggravates the DNA damage induced by a broad spectrum of genotoxic agents with different modes of action. These results are of utmost importance as our food can be co-contaminated with DON and DNA-damaging agents.

Deoxynivalenol triggers porcine intestinal tight junction disorder through hijacking SLC5A1 and PGC1α-mediated mitochondrial function

Deoxynivalenol (DON) is a mycotoxin frequently occurring in human and animal food worldwide, which raises increasing public health concerns. Growing evidence suggests that mitochondria is a pivotal molecular target for DON. However, the contribution of mitochondrial dysfunction to the pathogenesis of DON-induced gut epithelial barrier disruption remains poorly understood. In an animal experiment, piglets exposed to 2.89 mg DON/kg feed for 4 weeks showed altered metabolomic profiling in the serum and compromised transcriptome in the jejunum. DON exposure also impaired mitochondrial structure in the jejunal mucosa, corresponding with dysfunction of the tight junctions. In IPEC-J2 cells, metabolomic and transcriptomic analyses revealed that DON exposure perturbed biological processes occurring in the mitochondria and disordered the expression of genes involved in mitochondrial energy metabolism. Fuel utilization from glucose was affected by DON exposure, as were mitochondrial morphological dynamics leading to increased fragmentation. A marked loss of Na⁺/glucose cotransporter (SLC5A1) and peroxisome proliferator activated receptor-γ co-activator 1α (PGC1α) was observed in DON-treated cells. Taken together, our data highlight the critical role of impaired mitochondrial energy metabolism and mitochondrial biogenesis in abnormal intestinal tight junction upon DON exposure, and provide a potential mitochondrial target for intestinal mucosal restoration following DON exposure.