Zearalenone induces chromosome aberrations in mouse bone marrow: preventive effect of 17beta-estradiol, progesterone and Vitamin E

High-Resolution Magic Angle Spinning (HRMAS) NMR Identifies Oxidative Stress and Impairment of Energy Metabolism by Zearalenone in Embryonic Stages of Zebrafish (Danio rerio), Olive Flounder (Paralichthys olivaceus) and Yellowtail Snapper (Ocyurus chrysurus)

Zearalenone (ZEA) is a mycotoxin, commonly found in agricultural products, linked to adverse health impacts in humans and livestock. However, less is known regarding effects on fish as both ecological receptors and economically relevant "receptors" through contamination of aquaculture feeds. In the present study, a metabolomics approach utilizing high-resolution magic angle spinning nuclear magnetic resonance (HRMAS NMR) was applied to intact embryos of zebrafish (Danio rerio), and two marine fish species, olive flounder (Paralichthys olivaceus) and yellowtail snapper (Ocyurus chrysurus), to investigate the biochemical pathways altered by ZEA exposure. Following the assessment of embryotoxicity, metabolic profiling of embryos exposed to sub-lethal concentrations showed significant overlap between the three species and, specifically, identified metabolites linked to hepatocytes, oxidative stress, membrane disruption, mitochondrial dysfunction, and impaired energy metabolism. These findings were further supported by analyses of tissue-specific production of reactive oxygen species (ROS) and lipidomics profiling and enabled an integrated model of ZEA toxicity in the early life stages of marine and freshwater fish species. The metabolic pathways and targets identified may, furthermore, serve as potential biomarkers for monitoring ZEA exposure and effects in fish in relation to ecotoxicology and aquaculture.

Zearalenone induces the senescence of cardiovascular cells in vitro and in vivo

Zearalenone is a contaminant in food and feed products. It has been reported that zearalenone could lead to serious damage to health. So far, it is unclear whether zearalenone could lead to cardiovascular aging-related injury. For this, we assessed the effect of zearalenone on cardiovascular aging. Cardiomyocyte cell lines and primary coronary endothelial cells were used as two cell models in vitro experiments, and Western-blot, indirect immunofluorescence, and flow cytometry were performed to study the effect of zearalenone on cardiovascular aging. Experimental results indicated zearalenone treatment increased Sa-β-gal positive cell ratio, and the expression of senescence markers (p16 and p21) was significantly upregulated. Additionally zearalenone upregulated the inflammation and oxidative stress in cardiovascular cells. Furthermore, the effect of zearalenone on cardiovascular aging was also evaluated in vivo, and the results indicated that zearalenone treatment also led to the aging of myocardial tissue. These findings suggest that zearalenone could lead to cardiovascular aging-related injury. Furthermore, we also preliminarily explored the potential effect of zeaxanthin (which is a powerful antioxidant) on zearalenone-caused aging-related damage in vitro cell model, and found that zeaxanthin could alleviate zearalenone-induced aging-related damage. Collectively, the most important finding of the current work is that zearalenone could lead to cardiovascular aging. Next in importance, we also found that zeaxanthin could partially alleviate zearalenone-induced cardiovascular aging in vitro, indicating that zeaxanthin can be used as a drug or functional food to treat cardiovascular damage caused by zearalenone.

Effects of Intestinal Microorganisms on Metabolism and Toxicity Mitigation of Zearalenone in Broilers

Simple Summary

Zearalenone (ZEN) widely contaminates all the feed crops, and ZEN may cause harmful damage to animals and humans. Different animals have different sensitivity to ZEN. Among these animals, chickens show a strong resistance. Intestinal microorganisms are essential in digestion and degradation. Therefore, we hypothesise whether intestinal microorganisms in chickens play an important role in digesting and degrading ZEN. In this study, we found that intestinal microorganisms could degrade ZEN to a certain degree by both vivo and vitro experiments. We concluded that the intestinal microbiota of broilers had metabolic effects on ZEN and alleviated antioxidant and liver damage caused by ZEN to broilers. Moreover, we found some key bacteria that are important in degrading ZEN.

Abstract

Zearalenone (ZEN) is an estrogenic mycotoxin, and chickens are relatively insensitive to it. In this study, the effects of intestinal microorganisms on ZEN metabolism and toxicity mitigation in broilers were studied by two experiments. Firstly, in vitro, ZEN was incubated anaerobically with chyme from each part of the chicken intestine to study its intestinal microbial metabolism. Then, in vivo, we explored the effects of intestinal microbiota on ZEN by inhibiting intestinal microorganisms. Broilers were fed a control diet, 2.5 mg/kg ZEN diet, microbial inhibition diet or ‘microbial inhibition +2.5 mg/kg ZEN’ diet. In vitro, the results showed that the rates of ZEN degradation by microorganisms in the duodenum, ileum, caecum, and colon were 56%, 12%, 15%, and 17%, respectively, and the microorganisms could convert ZEN into Zearalenol (ZOL). After microbial inhibition in vivo, the content of ZEN and its metabolites in excreta of broilers increased significantly, and antioxidant damage and liver damage were aggravated. 16S rRNA sequencing results showed that antioxidant indices and the content of ZEN and its metabolites in excreta were significantly correlated with the relative abundance of Streptococcus, Lactococcus and Enterococcus, etc. In conclusion, the intestinal microorganisms of broilers play an important role in ZEN metabolism and ZEN-induced antioxidant and liver injury mitigation, among which the key bacteria include Streptococcus, Lactococcus and Enterococcus, etc.

Oxidative stress as a plausible mechanism for zearalenone to induce genome toxicity

Zearalenone (ZEN), a common non-steroidal estrogenic mycotoxin of the Fusarium genus, is one of the most frequent and powerful contaminant of grains and cereal products representing a serious threat for people and livestock health. In fact, ZEN causes cytotoxicity and genotoxicity in a variety of cell types at least in part through binding to estrogen receptors (ERs). The main pathways through which ZEN induces such effects remain, however, elusive. In particular, how the mycotoxin causes DNA damage, dysregulates DNA repair mechanisms, changes epigenome of targeted cells and, not least, affects chromatin conformation and non-coding RNA (ncRNA), is unclear. In the present paper, following extensive review of the literature about such ZEN effects and our own experience in studying the effects of this compound on reproductive processes, we propose that increased production of reactive oxygen species (ROS) and consequently oxidative stress (OS) are central in ZEN genotoxicity. Besides to shed light on the action mechanisms of the mycotoxin, this notion might help to develop effective strategies to counteract its deleterious biological effects.

Mycotoxins in soil and environment

Mycotoxins are secondary metabolites produced by specific fungi that have harmful effects on animals and humans. Worldwide more than 300 different mycotoxins are already known, frequently with concentrations in harvest products exceeding acceptable limits. Nevertheless, although these compounds have extensively been studied in food and feed, only little is known about their occurrence and fate in soil and agro-environmental matrices, such as manure, sewage sludge, drainage water and sediments. Therefore, the aim of this review was to (i) resume available methods for quantifying mycotoxins in soil, (ii) describe the occurrence and quantities of mycotoxins in soil and related agro-environmental matrices, and (iii) discuss the environmental fate of these target compounds with specific focus on their leaching potential into groundwater. The safest and most reliable method for mycotoxin quantification relies on mass spectrometry, while the extraction method and solvent composition differ depending on the compound under investigation. Mycotoxin levels detected in soils to date were in the μg range, reaching maximum amounts of 72.1 μg kg^-1 for zearalenone, 32.1 μg kg^-1 for deoxynivalenol, 23.7 μg kg^-1 for ochratoxin A, 6.7 μg kg^-1 for nivalenol, and 5.5 μg kg^-1 for aflatoxin. Different compartments in the agroecosystem (cereals, corn, rice, water, manure, sewage sludge) each contained at least one mycotoxin. Mycotoxin retention in soils is controlled by texture, with significant adsorption of the compounds to clays but leaching potentials in sandy soils. We did not find any reports detecting mycotoxins in sediments, although there are increasing reports of mycotoxins in freshwater samples. Overall, it appears that soils and sediments are still underrepresented in research on potential environmental contamination with mycotoxins.

Structure-toxicity relationships, toxicity mechanisms and health risk assessment of food-borne modified deoxynivalenol and zearalenone: A comprehensive review

Mycotoxin, as one of the most common pollutants in foodstuffs, poses great threat to food security and human health. Specifically, deoxynivalenol (DON) and zearalenone (ZEN)-two mycotoxin contaminants with considerable toxicity widely existing in food products-have aroused broad public concerns. Adding to this picture, modified forms of DON and ZEN, have emerged as another potential environmental and health threat, owing to their higher re-transformation rate into parent mycotoxins inducing accumulation of mycotoxin in humans and animals. Given this, a better understanding of the toxicity of modified mycotoxins is urgently needed. Moreover, the lack of toxicity data means a proper risk assessment of modified mycotoxins remains challenging. To better evaluate the toxicity of modified DON and ZEN, we have reviewed the relationship between their structures and toxicities. The toxicity mechanisms behind modified DON and ZEN have also been discussed; briefly, these involve acute, subacute, chronic, and combined toxicities. In addition, this review also addresses the global occurrence of modified DON and ZEN, and summarizes novel methods-including in silico analysis and implementation of relative potency factors-for risk assessment of modified DON and ZEN. Finally, the health risk assessment of modified DON and ZEN has also been discussed comprehensively.

Occurrence, Impact on Agriculture, Human Health, and Management Strategies of Zearalenone in Food and Feed: A Review

Mycotoxins represent an assorted range of secondary fungal metabolites that extensively occur in numerous food and feed ingredients at any stage during pre- and post-harvest conditions. Zearalenone (ZEN), a mycotoxin categorized as a xenoestrogen poses structural similarity with natural estrogens that enables its binding to the estrogen receptors leading to hormonal misbalance and numerous reproductive diseases. ZEN is mainly found in crops belonging to temperate regions, primarily in maize and other cereal crops that form an important part of various food and feed. Because of the significant adverse effects of ZEN on both human and animal, there is an alarming need for effective detection, mitigation, and management strategies to assure food and feed safety and security. The present review tends to provide an updated overview of the different sources, occurrence and biosynthetic mechanisms of ZEN in various food and feed. It also provides insight to its harmful effects on human health and agriculture along with its effective detection, management, and control strategies.

In silico methods for metabolomic and toxicity prediction of zearalenone, α-zearalenone and β-zearalenone

Zearalenone (ZEA), α-zearalenol (α-ZEL) and β-zearalenol (β-ZEL) (ZEA's metabolites) are co/present in cereals, fruits or their products. All three with other compounds, constitute a cocktail-mixture that consumers (and also animals) are exposed and never entirely evaluated, nor in vitro nor in vivo. Effect of ZEA has been correlated to endocrine disruptor alterations as well as its metabolites (α-ZEL and β-ZEL); however, toxic effects associated to metabolites generated once ingested are unknown and difficult to study. The present study defines the metabolomics profile of all three mycotoxins (ZEA, α-ZEL and β-ZEL) and explores the prediction of their toxic effects proposing an in silico workflow by using three programs of predictions: MetaTox, SwissADME and PASS online. Metabolomic profile was also defined and toxic effect evaluated for all metabolite products from Phase I and II reaction (a total of 15 compounds). Results revealed that products describing metabolomics profile were: from O-glucuronidation (1z and 2z for ZEA and 1 ab, 2 ab and 3 ab for ZEA's metabolites), S-sulfation (3z and 4z for ZEA and 4 ab, 5 ab and 6 ab for ZEA's metabolites) and hydrolysis (5z and 7 ab for ZEA's metabolites, respectively). Lipinsky's rule-of-five was followed by all compounds except those coming from O-glucuronidation (HBA>10). Metabolite products had better properties to reach blood brain barrier than initial mycotoxins. According to Pa values (probability of activation) order of toxic effects studied was carcinogenicity > nephrotoxic > hepatotoxic > endocrine disruptor > mutagenic (AMES TEST) > genotoxic. Prediction of inhibition, induction and substrate function on different isoforms of Cytochrome P450 (CYP1A1, CYP1A2, CYP2C9 and CYP3A4) varied for each compounds analyzed; similarly, for activation of caspases 3 and 8. Relying to our findings, the metabolomics profile of ZEA, α-ZEL and β-ZEL analyzed by in silico programs predicts alteration of systems/pathways/mechanisms that ends up causing several toxic effects, giving an excellent sight and direct studies before starting in vitro or in vivo assays contributing to 3Rs principle; however, confirmation can be only demonstrated by performing those assays.

Protective effects of kefir against zearalenone toxicity mediated by oxidative stress in cultured HCT-116 cells

Kefir is a fermented milk with numerous health favors counting restorative properties of bacterial flora, reduction of the symptoms of lactose intolerance, immune system stimulation, cholesterol reduction, as well as anti-mutagenic and anti-tumor properties. Zearalenone (ZEN) is a mycotoxin produced by some Fusarium species. ZEN often occurs as a contaminant in cereal grains and animal feeds. Human exposure occurs by ingestion of mycotoxin-contaminated products and can cause serious health problems. This study aimed to assess the preventive effect of kefir against ZEN toxicity in cultured HCT-116 colorectal carcinoma cells; by the evaluation of cell viability, oxidative stress status and the initiation of apoptotic cell death pathway. Our results demonstrated that ZEN inhibits cell proliferation which was accompanied by an increase in the generation of free radicals as measured by fluorescent 2,7-dichlorofluorescein (DCF) and Malondialdehyde (MDA). As an adaptive response to this redox status, we showed an induction of heat shock protein expression (Hsp 70) and an activation of antioxidant enzymes; catalase and Superoxide Dismutase (SOD). Moreover, a loss of mitochondrial membrane potential (Δѱm) was observed. The co-treatment as well as the pre-treatment by kefir showed a reduction of ZEN induced damages for all tested markers. However, the pre-treatment seems to be the most efficient, it prevented almost all ZEN hazards. Consequently, oxidative damage appears to be a key determinant of ZEN induced toxicity in cultured HCT-116 cells. In conclusion, we showed that kefir may better exert its virtue on preventive mode rather than on curative one. By this way, kefir as a beverage with highly antioxidant properties could be relevant particularly with the emergent demand for natural products which may counteract the detrimental effects of oxidative stress and therefore prevent multiple human diseases.

The detoxification effect of vitamin C on zearalenone toxicity in piglets

Zearalenone (ZEN), one of the more virulent mycotoxins occurred in various cereals and feed during recent decades and made serious health hazards to plants, animals and humans. Vitamin C (Vc) has been shown to be an effective antidote to zearalenone. In this paper, the effects of diets containing zearalenone on the growth performance, genital organ and immunoglobulin of weaning piglets and the toxicity alleviation of vitamin C were studied. Piglets were weaned at 21 days of age and 32 healthy female hybrid weaning piglets (Duroc × Landrace × Large white) with a mean weight of 12.27 ± 0.30 kg were randomly selected. The thirty-two female weaning piglets were divided into four treatment groups according to body weight: control; basal diet + vitamin C (150 mg/kg); basal diet + 1.0 mg/kg ZEN; basal diet + 1 mg/kg ZEN+vitamin C (150 mg/kg). There were eight replicates in each group. The test period was twenty-eight days. The results demonstrated that dietary zearalenone could significantly increase the length, width and area of vulva (P < 0.05), the genital organ coefficient (P < 0.05), the level of IgA, IgG and IgM (P < 0.05), the level of BUN, CRE, AST and TBIL (P < 0.05), and significantly decrease the level of E2, PROG, LH and FSH (P < 0.05). However, the addition of 150 mg/kg vitamin C to dietary zearalenone prevented deformities in the vulva, decrease in immune response capacity, changes in serum biochemical indicators and disorders in hormones level of the piglets that received the diet containing only zearalenone. In conclusion, feeding ZEN of 1.0 mg/kg can result in a deleterious effect on piglets, which was totally or partly ameliorated by dietary supplementation of vitamin C at concentrations about 150 mg/kg diet. This study systematically investigated the inhibition mechanism of vitamin C on ZEN-induced reproductive toxicity, immunotoxicity and hematological toxicity of piglets, and which provided new ideas for reducing the harm of mycotoxins to the animals through means of nutrition regulation.

Zearalenone Promotes Cell Proliferation or Causes Cell Death?

Zearalenone (ZEA), one of the mycotoxins, exerts different mechanisms of toxicity in different cell types at different doses. It can not only stimulate cell proliferation but also inhibit cell viability, induce cell apoptosis, and cause cell death. Thus, the objective of this review is to summarize the available mechanisms and current evidence of what is known about the cell proliferation or cell death induced by ZEA. An increasing number of studies have suggested that ZEA promoted cell proliferation attributing to its estrogen-like effects and carcinogenic properties. What’s more, many studies have indicated that ZEA caused cell death via affecting the distribution of the cell cycle, stimulating oxidative stress and inducing apoptosis. In addition, several studies have revealed that autophagy and some antioxidants can reverse the damage or cell death induced by ZEA. This review thoroughly summarized the metabolic process of ZEA and the molecular mechanisms of ZEA stimulating cell proliferation and cell death. It concluded that a low dose of ZEA can exert estrogen-like effects and carcinogenic properties, which can stimulate the proliferation of cells. While, in addition, a high dose of ZEA can cause cell death through inducing cell cycle arrest, oxidative stress, DNA damage, mitochondrial damage, and apoptosis.

Crocin protects human embryonic kidney cells (HEK293) from α- and β-Zearalenol-induced ER stress and apoptosis

α-zearalenol (α-ZOL) and β-zearalenol (β-ZOL) are the major metabolites of Zearalenone (ZEN) and are known to induce many toxic effects. In the present study, we investigated the involvement of endoplasmic reticulum (ER) stress in α- and β-ZOL-mediated toxicity in human kidney cells (HEK293) and evaluated the effect of a common dietary compound Crocin (CRO), from saffron. We show that α- and β-ZOL treatment induces ER stress as evidenced by the upregulation of the 78 kDa glucose-regulated protein (GRP78) and the Growth arrest and DNA damage-inducible protein (GADD34). Activation of the ER stress response is associated with activation of the mitochondrial pathway of apoptosis. This apoptotic process is characterized by an increase in ROS generation and lipid peroxidation, a loss of mitochondrial transmembrane potential (ΔΨm) and activation of caspases. We also demonstrate that the antioxidant properties of CRO help to prevent ER stress and reduce α- and β-ZOL-induced apoptosis in HEK293 cells. Our results suggest that saffron consumption might be helpful to prevent α- and β-ZOL-induced ER stress and toxicity.

The mycotoxin zearalenone enhances cell proliferation, colony formation and promotes cell migration in the human colon carcinoma cell line HCT116

Zearalenone (ZEN) and Aflatoxin B1 (AFB1) are fungal secondary metabolites produced by Fusarium and Aspergillus genera, respectively. These mycotoxins are found world-wide as corn and wheat contaminants. AFB1 is probably the most toxic and carcinogenic mycotoxin. It has been demonstrated to be mutagenic, genotoxic, and hepatocarcinogenic. ZEN is a non-steroidal estrogenic mycotoxin that displays hepatotoxicity, immunotoxicity and genotoxicity. Its mutagenic and carcinogenic properties have so far remained controversial and questionable. Using the colon carcinoma cell line HCT116, we will show here that ZEN, at low concentrations, enhances cell proliferation, increases colony formation and fastens cell migration after wound healing. The highest effect of ZEN was observed at a concentration 10 times lower as compared to AFB1. Our findings suggest thus that this mycotoxin exhibits carcinogenesis-like properties in HCT116 cells.

Protective effect of Crocin against zearalenone-induced oxidative stress in liver and kidney of Balb/c mice

Zearalenone (ZEN) is a mycotoxin from Fusarium species commonly found in many food commodities and known to cause reproductive disorders. Several studies have shown that ZEN is hematotoxic and hepatotoxic and causes several alterations of immunological parameters. In the present study, we aimed to evaluate the protective effect of Crocin (CRO), a natural carotenoid, against ZEN-induced toxicity in both renal and hepatic tissues of Balb/c mice. We demonstrated that ZEN (40 mg/kg body weight (b.w.)) induced oxidative stress in both kidney and liver as monitored by measuring the malondialdehyde (MDA) level, the protein carbonyl generation, the catalase and superoxide dismutase activity, and the expression of the heat shock proteins (Hsp70). However, combined treatment of ZEN with different doses of CRO (50, 100, and 250 mg/kg b.w.) significantly reduced ZEN-induced alterations in all tested oxidative stress markers. It could be concluded that CRO was effective in the protection against ZEN-induced toxicity in the liver and kidney of Balb/c mice.

Crocin and Quercetin protect HCT116 and HEK293 cells from Zearalenone-induced apoptosis by reducing endoplasmic reticulum stress

Mycotoxins are considered to be significant contaminants of food and animal feed. Zearalenone (ZEN) is a non-steroidal estrogenic mycotoxin produced by several species of Fusarium in cereals and agricultural products. ZEN has been shown to be cytotoxic, genotoxic, and mutagenic in different cell types. In the present study, we investigated the involvement of endoplasmic reticulum (ER) stress in ZEN-mediated toxicity in human intestine (HCT116) and kidney (HEK293) cells and evaluated the effects of the two common dietary compounds Quercetin (QUER) and Crocin (CRO). We show that ZEN treatment induces ER stress and activates the unfolded protein response (UPR) as evidenced by XBP1 mRNA splicing and upregulation of GRP78, ATF4, GADD34, PDIA6, and CHOP. Activation of the ER stress response is associated with activation of the mitochondrial pathway of apoptosis. This apoptotic process is characterized by an increase in ROS generation and lipid peroxidation, a loss of mitochondrial transmembrane potential (ΔΨm), and an activation of caspases and DNA damages. We also demonstrate that the antioxidant properties of QUER and CRO help to prevent ER stress and reduce ZEN-induced apoptosis in HCT116 and HEK293 cells. Our results suggest that antioxidant molecule might be helpful to prevent ZEN-induced ER stress and toxicity.

Endoplasmic Reticulum Stress Cooperates in Zearalenone-Induced Cell Death of RAW 264.7 Macrophages

Zearalenone (ZEA) is a fungal mycotoxin that causes cell apoptosis and necrosis. However, little is known about the molecular mechanisms of ZEA toxicity. The objective of this study was to explore the effects of ZEA on the proliferation and apoptosis of RAW 264.7 macrophages and to uncover the signaling pathway underlying the cytotoxicity of ZEA in RAW 264.7 macrophages. This study demonstrates that the endoplasmic reticulum (ER) stress pathway cooperated in ZEA-induced cell death of the RAW 264.7 macrophages. Our results show that ZEA treatment reduced the viability of RAW 264.7 macrophages in a dose- and time-dependent manner as shown by the 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide assay (MTT) and flow cytometry assay. Western blots analysis revealed that ZEA increased the expression of glucose-regulated protein 78 (GRP78) and CCAAT/enhancer binding protein homologous protein (CHOP), two ER stress-related marker genes. Furthermore, treating the cells with the ER stress inhibitors 4-phenylbutyrate (4-PBA) or knocking down CHOP, using lentivirus encoded short hairpin interfering RNAs (shRNAs), significantly diminished the ZEA-induced increases in GRP78 and CHOP, and cell death. In summary, our results suggest that ZEA induces the apoptosis and necrosis of RAW 264.7 macrophages in a dose- and time-dependent manner via the ER stress pathway in which the activation of CHOP plays a critical role.

Zearalenone-induced changes in biochemical parameters, oxidative stress and apoptosis in cardiac tissue

Zearalenone (ZEN) is a mycotoxin from Fusarium species commonly found in food commodities and is known to cause reproductive disorders. Several in vivo studies have shown that ZEN is haematotoxic and hepatotoxic and causes several alterations of immunological parameters. Meantime, the available information on the cardiotoxic effects of ZEN is very much limited. In the present study, we investigated the toxic effects of ZEN in heart tissues of Balb/c mice. We demonstrated that ZEN (40 mg kg−1 body weight (b.w.)) increased creatine phosphokinase, lactate dehydrogenase, aspartate transaminase, alanine transaminase, total cholesterol and triglyceride levels and induced oxidative stress as monitored by measuring the malondialdehyde level, the generation of protein carbonyls, the catalase and superoxide dismutase activity and the expression of the heat shock proteins (Hsp 70). We also demonstrated that acute administration of ZEN triggers apoptosis in cardiac tissue. Furthermore, we aimed to evaluate the safety and efficacy of crocin (CRO), a natural carotenoid, to prevent ZEN-induced cardiotoxicity in mice. In fact, combined treatment of ZEN with different doses of CRO (50, 100, and 250 mg kg−1 b.w.) showed a significant reduction of ZEN-induced toxicity for all tested markers in a dose-dependent manner. It could be concluded that CRO was effective in the protection against ZEN-induced toxicity in cardiac tissue.

Biochemical changes and oxidative stress induced by zearalenone in the liver of pregnant rats

The aim of the present research was to examine the toxic influence of different doses of zearalenone (ZEN) on the liver, especially oxidative stress induced by ZEN on the liver. A total of 48 pregnant Sprague-Dawley rats were randomly assigned into 4 treatments groups with 12 animals in each. The rats were fed with a normal diet treated with 0 mg/kg (control), 50 mg/kg (treatment 1), 100 mg/kg (treatment 2), or 150 mg/kg (treatment 3) ZEN in feed on gestation days (GDs) 0–7 and then all the rats were fed with a normal diet on GDs 8–20. The experimental period lasted 21 days. The results showed that exposure to ZEN induced increase in aspartate amino transferase, alanine aminotransferase, and alkaline phosphatase activities and decrease in total protein and albumin content in a dose-dependent manner and also induce decrease in superoxide dismutase and glutathione peroxidase activities and increase in malondialdehyde content in a dose-dependent manner in the serum and the liver. The increased transcription of cytochrome P450 2E1 (CYP2E1) was detected in the liver after exposure to ZEN. These results suggested that ZEN not only caused damage in the liver of pregnant rats in a dose-dependent manner but also induced the messenger RNA expression of CYP2E1 in the liver.

Cell death in relation to DNA damage after exposure to the jellyfish Pelagia noctiluca nematocysts

Studies on the toxicity of Mediterranean jellyfish have gained attention owing to their weak toxic properties. Our research has been mainly performed on the Scyphomedusae. Pelagia noctiluca is a scyphozoan jellyfish which causes a danger to sea bathers and fishery damages in the Mediterranean Sea. To check whether the cytotoxicity of Pelagia noctiluca nematocysts was associated to DNA lesions, we have looked for DNA fragmentation by means of the Comet and chromosome aberration assays. To specify cell death pathway, we have investigated caspase-3 activation. Our results have shown that nematocysts reduced cell viability and induced DNA fragmentation in a concentration-dependent manner with a maximum effect at 150 000 nematocysts mL(-1). The high percentage of chromosome aberrations also emphasized the genotoxic character of Pelagia noctiluca nematocysts in Vero cells. This fragmentation was correlated to apoptosis induction which was confirmed by caspase-3 activation. In conclusion, the present report has suggested that Pelagia noctiluca nematocysts were able to promote apoptosis in Vero cells and therefore may be useful in cancer therapy.

Evaluation of Oxidative DNA Damage Using an Alkaline Single Cell Gel Electrophoresis (SCGE) Comet Assay, and the Protective Effects of N-Acetylcysteine Amide on Zearalenone-induced Cytotoxicity in Chang Liver Cells

Zearalenone (ZEN) is a non-steroidal estrogenic mycotoxin produced by several species of Fusarium that are found in cereals and agricultural products. ZEN has been implicated in mycotoxicosis in farm animals and in humans. The toxic effects of ZEN are well known, but the ability of an alkaline Comet assay to assess ZEN-induced oxidative DNA damage in Chang liver cells has not been established. The first aim of this study was to evaluate the Comet assay for the determination of cytotoxicity and extent of DNA damage induced by ZEN toxin, and the second aim was to investigate the ability of N-acetylcysteine amide (NACA) to protect cells from ZEN-induced toxicity. In the Comet assay, DNA damage was assessed by quantifying the tail extent moment (TEM; arbitrary unit) and tail length (TL; arbitrary unit), which are used as indicators of DNA strand breaks in SCGE. The cytotoxic effects of ZEN in Chang liver cells were mediated by inhibition of cell proliferation and induction of oxidative DNA damage. Increasing the concentration of ZEN increased the extent of DNA damage. The extent of DNA migration, and percentage of cells with tails were significantly increased in a concentration-dependent manner following treatment with ZEN toxin (p < 0.05). Treatment with a low concentration of ZEN toxin (25 μM) induced a relatively low level of DNA damage, compared to treatment of cells with a high concentration of ZEN toxin (250 μM). Oxidative DNA damage appeared to be a key determinant of ZEN-induced toxicity in Chang liver cells. Significant reductions in cytolethality and oxidative DNA damage were observed when cells were pretreated with NACA prior to exposure to any concentration of ZEN. Our data suggest that ZEN induces DNA damage in Chang liver cells, and that the antioxidant activity of NACA may contribute to the reduction of ZEN-induced DNA damage and cytotoxicity via elimination of oxidative stress.

Comparison of the sequestering properties of yeast cell wall extract and hydrated sodium calcium aluminosilicate in three in vitro models accounting for the animal physiological bioavailability of zearalenone

The sequestration/inactivation of the oestrogenic mycotoxin zearalenone (ZEA) by two adsorbents--yeast cell wall extract (YCW) and hydrated sodium calcium aluminosilicate (HSCAS)--was studied in three laboratory models: (1) an in vitro model was adapted from referenced methods to test for the sequestrant sorption capabilities under buffer conditions at two pH values using liquid chromatography coupled to a fluorescence detector for toxin quantification; (2) a second in vitro model was used to evaluate the sequestrant sorption stability according to pH variations and using ³H-labelled ZEA at low toxin concentration; and (3) an original, ex vivo Ussing chamber model was developed to further understand the transfer of ZEA through intestinal tissue and the impact of each sequestrant on the mycotoxin bioavailability of ³H-labelled ZEA. YCW was a more efficient ZEA adsorbent than HSCAS in all three models, except under very acidic conditions (pH 2.5 or 3.0). The Ussing chamber model offered a novel, ex vivo, alternative method for understanding the effect of sequestrant on the bioavailability of ZEA. The results showed that compared with HSCAS, YCW was more efficient in sequestering ZEA and that it reduced the accumulation of ZEA in the intestinal tissue by 40% (p < 0.001).

Antioxidative and antigenotoxic effect of vitamin E against patulin cytotoxicity and genotoxicity in HepG2 cells

Patulin (PAT) is a mycotoxin produced in fruits, mainly in apples, by certain species of Penicillium, Aspergillus, and Byssochlamys. It has been shown that PAT is cytotoxic, genotoxic, and mutagenic in different cell types. Several studies incriminate the oxidative stress as a mechanism of PAT-mediated toxicity. In this context, our aim was to investigate the protective role of Vitamin E (Vit E), an antioxidant agent, against PAT induced cytotoxicity and genotoxicity in cultured HepG2 cells. The obtained results showed that addition of Vit E in cells treated with PAT significantly reduce cell mortality induced by this toxin. In the same conditions, Vit E decreased the intracellular level of ROS, reduced PAT induced p53 expression, and reversed PAT induced DNA damage. In addition, Vit E prevented significantly the percentage of chromosome aberrations induced by PAT in HepG2 cells in a concentration dependant manner. These results suggest that Vit E, an exogenous antioxidant agent, plays an important role in defense against PAT-induced cytotoxicity and genotoxicity, which confirms the involvement of oxidative stress in the induction of DNA damage by PAT in HepG2 cells.

Cellular mechanisms of the cytotoxic effects of the zearalenone metabolites α-zearalenol and β-zearalenol on RAW264.7 macrophages

Zearalenone (ZEN) and its metabolites are commonly found in many food commodities and are known to cause reproductive disorders and genotoxic effects. The major ZEN metabolites are α-zearalenol (α-ZOL) and β-zearalenol (β-ZOL). Although many studies have demonstrated the cytotoxic effects of these metabolites, the mechanisms by which α-ZOL or β-ZOL mediates their cytotoxic effects appear to differ according to cell type and the exposed toxins. We evaluated the toxicity of α-ZOL and β-ZOL on RAW264.7 macrophages and investigated the underlying mechanisms. β-ZOL not only more strongly reduced the viability of cells than did α-ZOL, but it also induced cell death mainly by apoptosis rather than necrosis. The ZEN metabolites induced loss of mitochondrial membrane potential (MMP), mitochondrial changes in Bcl-2 and Bax proteins, and cytoplasmic release of cytochrome c and apoptosis-inducing factor (AIF). Use of an inhibitor specific to c-Jun N-terminal kinase (JNK), p38 kinase or p53, but not pan-caspase or caspase-8, decreased the toxin-induced generation of reactive oxygen species (ROS) and also attenuated the α-ZOL- or β-ZOL-induced decrease of cell viability. Antioxidative enzyme or compounds such as catalase, acteoside, and (E)-1-(3,4-dihydroxyphenethyl)-3-(4-hydroxystyryl)urea suppressed the ZEN metabolite-mediated reduction of cell viability. Further, knockdown of AIF via siRNA transfection diminished the ZEN metabolite-induced cell death. Collectively, these results suggest that the activation of p53, JNK or p38 kinase by ZEN metabolites is the main upstream signal required for the mitochondrial alteration of Bcl-2/Bax signaling pathways and intracellular ROS generation, while MMP loss and nuclear translocation of AIF are the critical downstream events for ZEN metabolite-mediated apoptosis in macrophages.

Differential gene expression in rainbow trout (Oncorhynchus mykiss) liver and ovary after exposure to zearalenone

Zearalenone (ZEA) is a mycotoxin of worldwide occurrence, and it has been shown to produce numerous adverse effects in both laboratory and domestic animals. However, regardless of recent achievements, the molecular mechanisms underlying ZEA toxicity remain elusive, and little is known about transcriptome changes of fish cells in response to ZEA occurrence. In the present study, differential display PCR was used to generate a unique cDNA fingerprint of differentially expressed transcripts in the liver and ovary of juvenile rainbow trout after either 24, 72, or 168 h of intraperitoneal exposure to ZEA (10 mg/kg of body mass). From a total of 59 isolated cDNA bands (ESTs), 5 could be confirmed with Real-Time qPCR and their nucleotide sequences were identified as mRNAs of: acty (β-centractin), the cytoskeleton structural element; bccip, responsible for DNA repair and cell cycle control; enoa (α-enolase), encoding enzyme of the glycolysis process; proc (protein C), that takes part in the blood coagulation process; and frih, encoding the heavy chain of ferritin, the protein complex important for iron storage. Further qPCR analysis of the confirmed ESTs expression profiles revealed significant mRNA level alterations in both tissues of exposed fish during the 168 h study. The results revealed a complex network of genes associated with different biological processes that may be engaged in the cellular response to ZEA exposure, i.e. blood coagulation or iron-storage processes.

Chemopreventive effect of cactus Opuntia ficus indica on oxidative stress and genotoxicity of aflatoxin B1

BACKGROUND

Aflatoxin B1 (AFB1) is potent hepatotoxic and hepatocarcinogenic agent. In aflatoxicosis, oxidative stress is a common mechanism contributing to initiation and progression of hepatic damage. The aim of this work was to evaluate the hepatoprotective effect of cactus cladode extract (CCE) on aflatoxin B1-induced liver damage in mice by measuring malondialdehyde (MDA) level, the protein carbonyls generation and the heat shock proteins Hsp 70 and Hsp 27 expressions in liver. We also looked for an eventual protective effect against AFB1-induced genotoxicity as determined by chromosome aberrations test, SOS Chromotest and DNA fragmentation assay. We further evaluated the modulation of p53, bax and bcl2 protein expressions in liver.

METHODS

Adult, healthy balbC (20-25 g) male mice were pre-treated by intraperitonial administration of CCE (50 mg/Kg.b.w) for 2 weeks. Control animals were treated 3 days a week for 4 weeks by intraperitonial administration of 250 μg/Kg.b.w AFB1. Animals treated by AFB1 and CCE were divided into two groups: the first group was administrated CCE 2 hours before each treatment with AFB1 3 days a week for 4 weeks. The second group was administrated without pre-treatment with CCE but this extract was administrated 24 hours after each treatment with AFB1 3 days a week for 4 weeks.

RESULTS

Our results clearly showed that AFB1 induced significant alterations in oxidative stress markers. In addition, it has a genotoxic potential and it increased the expression of pro apoptotic proteins p53 and bax and decreased the expression of bcl2. The treatment of CCE before or after treatment with AFB1, showed (i) a total reduction of AFB1 induced oxidative damage markers, (ii) an anti-genotoxic effect resulting in an efficient prevention of chromosomal aberrations and DNA fragmentation compared to the group treated with AFB1 alone (iii) restriction of the effect of AFB1 by differential modulation of the expression of p53 which decreased as well as its associated genes such as bax and bcl2.

CONCLUSION

We concluded that CCE might have a hepatoprotective effect against aflatoxicosis in mice, probably acting by promoting the antioxidant defence systems.

In vitro and in vivo induction of chromosome aberrations by alpha- and beta-zearalenols: comparison with zearalenone

Zearalenone (ZEN) is a non-steroidal estrogenic mycotoxin produced by Fusarium fungi. It contaminates different components of the food chain and can cause serious economic and public health problems. The major metabolites of ZEN in various animal species are alpha- and beta-zearalenol (α-, β-ZOL). Some in vivo studies have shown that these two metabolites are as toxic as the mother molecule (ZEN), but other investigations have demonstrated that α- and β-ZOL are less toxic than ZEN. Thus, the aim of the present study was to evaluate cytotoxicity and genotoxicity of α- and β-ZOL in vivo, in mouse bone-marrow cells and in vitro, in cultured HeLa cells, and to compare it with ZEN. ZEN showed the same cytotoxicity as α-ZOL and both are more cytotoxic than β-ZOL. Genotoxicity of ZEN and its derivatives was assessed by the chromosome aberration assay. Our results show that ZEN as well as α- and β-ZOL increased the percentage of chromosome aberrations in mouse bone-marrow cells and in HeLa cells. In the two systems, ZEN and α-ZOL exhibited the same range of genotoxicity and both were more genotoxic than β-ZOL. Furthermore, our results show that either ZEN or its two metabolites inhibited cell viability in a dose-dependent manner. We conclude that biotransformation of ZEN may be considered as only a partial detoxification pathway since the resulting metabolites remain relatively toxic.

Alteration of in vitro and acute in vivo toxicity of textile dyeing wastewater after chemical and biological remediation

INTRODUCTION

Textile industry is one of the most common and essential sectors in Tunisia. However, the treatment of textile effluents becomes a university because of their toxic impacts on waters, soils, flora, and fauna.

MATERIALS AND METHODS

The aim of this work was to evaluate the ability of Pseudomonas putida mt-2 to decolorize a textile wastewater and to compare the biologic decolorization process to the chemical one currently used by the textile industry.

RESULTS

P. putida exhibited a high decolorizing capacity of the studied effluent, compared to the coagulation-flocculation method with decolorization percentage of 86% and 34.5%, respectively. Genotoxicity of the studied effluent, before and after decolorization by P. putida mt-2, was evaluated in vitro, using the SOS chromotest, and in vivo, in mouse bone marrow, by assessing the percentage of cells bearing different chromosome aberrations compared to not treated mice. In addition, textile effluent statistically significant influenced acetylcholinesterase and butyrylcholinesterase activities and lipid peroxidation (p < 0.01) when compared to not-treated mice. Coagulation-flocculation treatment process used by industry was revealed to be ineffective. Indeed toxicities persisted after treatment and the effluent did not show any statistically significant decrease in toxicities compared to non-treated effluent. Our results indicate that P. putida is a promising and improved alternative to treating industrial scale effluent compared to current chemical decolorization procedures used by the Tunisian textile industry.

Mycotoxin zearalenone induces AIF- and ROS-mediated cell death through p53- and MAPK-dependent signaling pathways in RAW264.7 macrophages

Zearalenone (ZEN) is commonly found in many food commodities and is known to cause reproductive disorders and genotoxic effects. However, the mode of ZEN-induced cell death of macrophages and the mechanisms by which ZEN causes cytotoxicity remain unclear. The present study shows that ZEN treatment reduces viability of RAW264.7 cells in a dose-dependent manner. ZEN causes predominantly necrotic and late apoptotic cell death. ZEN treatment also results in the loss of mitochondrial membrane potential (MMP), mitochondrial changes in Bcl-2 and Bax proteins, and cytoplasmic release of cytochrome c and apoptosis-inducing factor (AIF). Pre-treatment of the cells with either z-VAD-fmk or z-IETD-fmk does not attenuate ZEN-mediated cell death, whereas catalase suppresses the ZEN-induced decrease in viability in RAW264.7 cells. Treating the cells with c-Jun N-terminal kinase (JNK), p38 mitogen-activated protein kinase (MAPK), or p53 inhibitor prevented ZEN-mediated changes, such as MMP loss, cellular reactive oxygen species (ROS) increase, and cell death. JNK or p38 MAPK inhibitor inhibited mitochondrial alterations of Bcl-2 and Bax proteins with attendant decreases in cellular ROS levels. Knockdown of AIF via siRNA transfection also diminished ZEN-induced cell death. Further, adenosine triphosphate was markedly depleted in the ZEN-exposed cells. Collectively, these results suggest that ZEN induces cytotoxicity in RAW264.7 cells via AIF- and ROS-mediated signaling, in which the activations of p53 and JNK/p38 play a key role.

Effects of zearalenone and its derivatives on porcine immune response

Zearalenone (ZEN), a mycotoxin produced by several Fusarium spp., is most commonly found as a contaminant in stored grain and has chronic estrogenic effects on mammals. In this in vitro study, we compared the effects of zearalenone (ZEN) and some of its derivatives: α-zearalenol (α-ZOL), β-zearalenol (β-ZOL), and zearalanone (ZAN) on several peripheral blood mononuclear cell (PBMC) parameters: cytotoxicity, proliferation, as well as antibody and cytokine synthesis. The amounts of toxins necessary to inhibit viability, in a dehydrogenase enzyme activity assay (MTT test), by 50% were: 22.7 μM for ZEN, 29.1 μM for α-ZOL, 17.3 μM for β-ZOL and 26.3 μM for ZAN. The administration of 10 μM toxin induced a decrease in the ConA stimulated proliferation of PBMC by 19.6% for ZAN, 45.4% for ZEN, 43.6% for α-ZOL and 85.2% for β-ZOL, when compared to the control stimulated cells. Also, ZEN and its metabolites at concentrations higher than 5 μM induced a significant decrease of the IgG, IgA or IgM levels. Concentrations of 5 and 10 μM of ZEN and ZAN significantly decreased the TNF-α synthesis in the supernatant of the stimulated cells; 10 μM of ZAN also decreased IL-8 synthesis. In conclusion, our results show that ZEN and ZEN derivatives altered several parameters of the humoral and cellular immune response. Therefore, our results are clinically relevant as ZEN and its metabolites are frequent contaminants of animal feed and we have shown that intoxicated animals are incapable of inducing an adequate immune response.

Effects of purified zearalenone on growth performance, organ size, serum metabolites, and oxidative stress in postweaning gilts

Zearalenone (ZEA), an estrogenic mycotoxin, is produced mainly by Fusarium fungi. Previous studies indicated that acute ZEA exposure induced oxidative stress and damage in multiple organs. Therefore, the present study was designed to investigate the adverse effects of dietary ZEA (1.1 to 3.2 mg/kg of diet) on oxidative stress and organ damage in postweaning gilts. A total of 20 gilts (Landrace × Yorkshire × Duroc) weaned at d 21 with an average BW of 10.36 ± 1.21 kg was used in the study. Gilts were housed in a temperature-controlled room, divided into 4 treatments, and fed a basal diet only (control) or basal diet supplemented with purified ZEA at a dietary concentration of 1 (ZEA1), 2 (ZEA2), or 3 (ZEA3) mg/kg of diet for 18 d ad libitum. The actual ZEA contents (analyzed) were 0, 1.1 ± 0.02, 2.0 ± 0.01, and 3.2 ± 0.02 mg/kg for control, ZEA1, ZEA2, and ZEA3, respectively. Gilts fed different amounts of dietary ZEA grew similarly with no difference (P > 0.05) in feed intake. Vulva size increased linearly over the 18 d of feeding in gilts fed diets containing 1.1 mg of ZEA/kg or greater (P < 0.001). Relative weight of genital organs, liver, and kidney increased linearly (P < 0.05) in a ZEA-dose-dependent manner. Serum aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, γ-glutamate transferase, urea, and creatinine (P < 0.05), and malondialdehyde concentrations in both serum and liver (P < 0.001) were also increased linearly in a ZEA-dose-dependent manner. However, spleen relative weight (P = 0.002) and activities of total superoxide dismutase and glutathione peroxidase (in both serum and liver (P < 0.05) were decreased linearly as dietary ZEA increased. Results showed that besides genital organs, the liver, kidney, and spleen may also be target tissues in young gilts fed diets containing 1.1 to 3.2 mg of ZEA/kg for 18 d. Increased key liver enzymes in the serum suggest progressive liver damage caused by feeding ZEA, and an increase in oxidative stress in gilts is another potential impact of ZEA toxicity in pigs.

Zearalenone activates pregnane X receptor, constitutive androstane receptor and aryl hydrocarbon receptor and corresponding phase I target genes mRNA in primary cultures of human hepatocytes

The mycotoxin zearalenone (ZEN) is found worldwide as a contaminant in cereals and grains. ZEN subchronic and chronic toxicities are dominated by reproductive disorders in different mammalian species which have made ZEN established mammalian endocrine disrupter. Over the last 30 years of ZEN biotransformation study, the toxin was thought to undergo reductive metabolism only, with the generation in several species of α- and β-isomers of zearalenol. However, recent investigations have noticed that the mycoestrogen is prone to oxidative metabolism leading to hydroxylation of ZEN though the involvement of different cytochromes P450 (CYPs) isoforms. The aim of the present study was to further explore the effect of ZEN on regulation of some CYPs using primary cultures of human hepatocytes. For this aim, using real time RT-PCR, we monitored in a first time, the effect of ZEN on mRNA levels of pregnane X receptor (PXR), constitutive androstane receptor (CAR) and aryl hydrocarbon receptor (AhR), nuclear receptors known to be involved in the regulation of some CYPs. In a second time, we looked for ZEN effect on expression of PXR, CAR and AhR corresponding phase I target genes (CYP3A4, CYP3A5, CYP2B6, CYP2C9, CYP1A1 and CYP1A2). Finally, we realised the luciferase assay in HepG2 treated with the toxin and transiently transfected with p-CYP3A4-Luc in the presence of a hPXR vector or transfected with p-CYPA1-Luc.Our results clearly showed that ZEN activated human PXR, CAR and AhR mRNA levels in addition to some of their phase I target genes mainly CYP3A4, CYP2B6 and CYP1A1 and at lesser extent CYP3A5 and CYP2C9 at ZEN concentrations as low as 0.1 μM.

Acid violet 7 and its biodegradation products induce chromosome aberrations, lipid peroxidation, and cholinesterase inhibition in mouse bone marrow

INTRODUCTION

Acid violet 7 (AV7), mostly used in food, paper, cosmetic, and especially in textile industries, was degraded by Pseudomonas putida mt-2 at concentrations up to 200 mg/l.

MATERIALS AND METHODS

In this study, toxicity of AV7, before and after biodegradation, was evaluated in vivo, in mouse bone marrow, by assessing the percentage of cells bearing different chromosome aberrations, membrane lipid peroxidation, and acetylcholinesterasic activity inhibition. The studies included same conditions for animal treatment, corresponding to increasing doses by intraperitoneal (ip) injection.

RESULTS

Results indicated that AV7 showed a significant ability to induce chromosome aberrations, lipid peroxidation, and acetylcholinesterase inhibitory effect. The toxicity of AV7 increased significantly after static biodegradation with P. putida mt-2 and totally disappeared after shaken incubation. In addition, the toxicity generated by the pure azo dye and the corresponding azoreduction metabolites (4'-aminoacetanilide (4'-AA) and 5-acetamido-2-amino-1-hydroxy-3,6-naphtalene disulfonic acid (5-ANDS)) were compared. 4'-AA and 5-ANDS would be responsible of static biodegradation medium toxicity. The present study demonstrates that P. putida mt-2, incubated under aerobic condition, has a catabolism which enables it to degrade AV7, and especially to completely detoxify the dye mixture.