Relation of 8-ketotrichothecene and zearalenone analog structure to inhibition of mitogen-induced human lymphocyte blastogenesis

4-Phenylbutyric acid alleviated 3-acetyldeoxynivalenol-induced immune cells response by inhibiting endoplasmic reticulum stress in mouse spleen

3-Acetyldeoxynivalenol (3-Ac-DON), an acetylated derivative of deoxynivalenol (DON), has contaminated grains and grain-based products in general and been harmful to human and animal health. However, the damage effects and regulatory mechanisms to the host immune system have not been well explored. In the present study, our results revealed that 3-Ac-DON significantly decreased spleen index, elevated MPO activity, upregulated mRNA and protein levels of IL-1α, IL-1β, IL-6, IL-17A, TNF-α, M-CSF, G-CSF, CCL2, IFN-β, and IL-10 in the spleen and serum. Interestingly, 4-phenylbutyric acid (4-PBA), an inhibitor of endoplasmic reticulum (ER) stress, largely abolished the above adverse effects. Importantly, 3-Ac-DON enhanced the mRNA abundances of ER stress-related indicators, such as BIP, IRE1A, ATF6, XBP-1, EIF2A, ATF4, and CHOP, which were abolished by 4-PBA, indicating the inhibiting effects of ER stress by 4-PBA in the spleen. Furthermore, 3-Ac-DON reshaped the populations of innate immune cells (neutrophils, macrophages, dendritic cells, natural killer cells) and adaptive immune cells (T lymphocytes, helper T cells, suppressor T cells, and B lymphocytes) in the peripheral blood and spleen lymphocytes. In conclusion, our studies demonstrated that the adverse effects of 3-Ac-DON on immune cells response could be implemented by ER stress and the ameliorative effect of 4-PBA.

Zearalenone and the Immune Response

Zearalenone (ZEA) is an estrogenic fusariotoxin, being classified as a phytoestrogen, or as a mycoestrogen. ZEA and its metabolites are able to bind to estrogen receptors, 17β-estradiol specific receptors, leading to reproductive disorders which include low fertility, abnormal fetal development, reduced litter size and modification at the level of reproductive hormones especially in female pigs. ZEA has also significant effects on immune response with immunostimulatory or immunosuppressive results. This review presents the effects of ZEA and its derivatives on all levels of the immune response such as innate immunity with its principal component inflammatory response as well as the acquired immunity with two components, humoral and cellular immune response. The mechanisms involved by ZEA in triggering its effects are addressed. The review cited more than 150 publications and discuss the results obtained from in vitro and in vivo experiments exploring the immunotoxicity produced by ZEA on different type of immune cells (phagocytes related to innate immunity and lymphocytes related to acquired immunity) as well as on immune organs. The review indicates that despite the increasing number of studies analyzing the mechanisms used by ZEA to modulate the immune response the available data are unsubstantial and needs further works.

Toxicokinetic profile of fusarenon-X and its metabolite nivalenol in the goat (Capra hircus)

The main aim of this research was to evaluate the toxicokinetic characteristics of fusarenon-X (FX) and its metabolite, nivalenol (NIV), in goats. The amounts of FX and NIV in post-mitochondrial (S-9), microsomal and cytosolic fractions of diverse tissues of the goat were also investigated. FX was intravenously (iv) or orally (po) administered to goats at dosages of 0.25 and 1 mg/kg bw, respectively. The concentrations of FX and NIV in plasma, feces and urine were quantified by liquid chromatography tandem-mass spectrometry (LC-ESI-MS/MS). The concentrations of FX in plasma were quantified up to 8 h with both routes of administration. A large amount of NIV (metabolite) was quantifiable in plasma, urine and feces after both administrations. The C_max value of FX was 413.39 ± 206.84 ng/ml after po administration. The elimination half-life values were 1.64 ± 0.32 h and 4.69 ± 1.25 h after iv and po administration, respectively. In vitro experiments showed that the conversion FX-to-NIV mainly occurs in the liver microsomal fraction. This is the first study that evaluates the fate and metabolism of FX in ruminant species.

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.

Comparative Analysis of Zearalenone Effects on Thyroid Receptor Alpha (TRα) and Beta (TRβ) Expression in Rat Primary Cerebellar Cell Cultures

Thyroid receptors play an important role in postnatal brain development. Zearalenone (ZEN), a major mycotoxin of Fusarium fungi, is well known to cause serious health problems in animals and humans through various mechanisms, including the physiological pathways of thyroid hormone (TH). In the present study, we aimed to investigate the expression of thyroid receptors α (TRα) and β (TRβ) in primary cerebellar neurons in the presence or absence of glia and following ZEN treatment, using quantitative reverse transcription-polymerase chain reaction (qRT-PCR) and Western blot. Primary cerebellar granule cells were treated with low doses of ZEN (0.1 nM) in combination with physiologically relevant concentrations of l-thyroxine (T4), 3,3′,5-triiodo-l-thyronine (T3) and 17β-estradiol (E2). Expression levels of TRα and TRβ at mRNA and protein levels were slightly modified by ZEN administered alone; however, along with thyroid and steroid hormones, modelling the physiological conditions, expression levels of TRs varied highly depending on the given treatment. Gene expression levels were also highly modulated by the presence or absence of glial cells, with mostly contrasting effects. Our results demonstrate divergent transcriptional and translational mechanisms involved in the expression of TRs implied by ZEN and hormonal milieu, as well as culturing conditions.

Trichothecenes: immunomodulatory effects, mechanisms, and anti-cancer potential

Paradoxically, trichothecenes have both immunosuppressive and immunostimulatory effects. The underlying mechanisms have not been fully explored. Early studies show that dose, exposure timing, and the time at which immune function is assessed influence whether trichothecenes act in an immunosuppressive or immunostimulatory fashion. Recent studies suggest that the immunomodulatory function of trichothecenes is also actively shaped by competing cell-survival and death-signaling pathways. Autophagy may also promote trichothecene immunosuppression, although the mechanism may be complicated. Moreover, trichothecenes may generate an "immune evasion" milieu that allows pathogens to escape host and vaccine immune defenses. Some trichothecenes, especially macrocyclic trichothecenes, also potently kill cancer cells. T-2 toxin conjugated with anti-cancer monoclonal antibodies significantly suppresses the growth of thymoma EL-4 cells and colon cancer cells. The type B trichothecene diacetoxyscirpenol specifically inhibits the tumor-promoting factor HIF-1 in cancer cells under hypoxic conditions. Trichothecin markedly inhibits the growth of multiple cancer cells with constitutively activated NF-κB. The type D macrocyclic toxin Verrucarin A is also a promising therapeutic candidate for leukemia, breast cancer, prostate cancer, and pancreatic cancer. The anti-cancer activities of trichothecenes have not been comprehensively summarized. Here, we first summarize the data on the immunomodulatory effects of trichothecenes and discuss recent studies that shed light on the underlying cellular and molecular mechanisms. These mechanisms include autophagy and major signaling pathways and their crosstalk. Second, the anti-cancer potential of trichothecenes and the underlying mechanisms will be discussed. We hope that this review will show how trichothecene bioactivities can be exploited to generate therapies against pathogens and cancer.

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.

An overview of the toxicology and toxicokinetics of fusarenon-X, a type B trichothecene mycotoxin

Fusarenon-X (FX) is a type B trichothecene mycotoxin that is frequently observed along with deoxynivalenol (DON) and nivalenol (NIV) in agricultural commodities. This review aims to give an overview of the literature concerning the toxicology and toxicokinetics of FX. FX is primarily found in cereals grown in temperate regions, but it can also be found worldwide because of the global transport of products. The major toxicity of FX occurs through inhibition of protein synthesis, followed by the disruption of DNA synthesis. Moreover, FX has also been shown to induce apoptosis in in vitro and in vivo studies. The targets of FX are organs containing actively proliferating cells, such as the thymus, spleen, skin, small intestine, testes and bone marrow. FX causes immunosuppression, intestinal malabsorption, developmental toxicity and genotoxicity. In addition, sufficient evidence of carcinogenicity in experimental animals is currently lacking, and the International Agency for Research on Cancer (IARC) classifies it as a group 3 carcinogen.

Toxicology of deoxynivalenol and its acetylated and modified forms

Mycotoxins are the most frequently occurring natural contaminants in human and animal diet. Among them, deoxynivalenol (DON), produced by Fusarium, is one of the most prevalent and thus represents an important health risk. Recent detection methods revealed new mycotoxins and new molecules derivated from the "native" mycotoxins. The main derivates of DON are the acetylated forms produced by the fungi (3- and 15-acetyl-DON), the biologically "modified" forms produced by the plant (deoxynivalenol-3-β-D-glucopyranoside), or after bacteria transformation (de-epoxy DON, 3-epi-DON and 3-keto-DON) as well as the chemically "modified" forms (norDON A-C and DON-sulfonates). High proportions of acetylated and modified forms of DON co-occur with DON, increasing the exposure and the health risk. DON and its acetylated and modified forms are rapidly absorbed following ingestion. At the molecular level, DON binds to the ribosome, induces a ribotoxic stress leading to the activation of MAP kinases, cellular cell-cycle arrest and apoptosis. The toxic effects of DON include emesis and anorexia, alteration of intestinal and immune functions, reduced absorption of the nutrients as well as increased susceptibility to infection and chronic diseases. In contrast to DON, very little information exists concerning the acetylated and modified forms; some can be converted back to DON, their ability to bind to the ribosome and to induce cellular effects varies according to the toxin. Except for the acetylated forms, their toxicity and impact on human and animal health are poorly documented.

Zearalenone affects immune-related parameters in lymphoid organs and serum of rats vaccinated with porcine parvovirus vaccine

Rats were administered zearalenone (ZEA) via gavage at dosages of 0, 1, 5, and 30 mg/kg for 36 days. On treatment day 8, inactivated porcine parvovirus vaccine (Vac) was injected intraperitoneally. Antibody production against porcine parvovirus was then measured as a function of ZEA treatment. Compared to the vaccine alone, ZEA treatment, with or without Vac, decreased the serum level of IgG. The level of IgM decreased in all ZEA groups at day 22, but the decrease was sustained only in the medium-dose ZEA group at day 36. The level of IgA was unchanged in the Vac only and ZEA groups at day 22, but was decreased in the 5 mg/kg ZEA plus Vac group compared to the Vac only group at day 36. The level of IgE was decreased by all doses of ZEA at day 22, but was unaffected in ZEA plus Vac groups compared to the Vac only group. The levels of IL-1 in the thymus and spleen; INF-γ in serum; IL-2, IL-6, and IL-10 in the thymus; and IL-10 and IFN-γ in the spleen decreased after ZEA administration. Furthermore, the levels of IL-1β in the spleen and mesenteric lymph node, IL-1β in the thymus, IL-2 in the thymus and spleen, IL-6 in the thymus, IL-10 and IFN-γ in the spleen, and GM-CSF and TNF-α in the thymus decreased after vaccination in rats exposed to ZEA. In conclusion, these results suggest that ZEA exposure via drinking water can cause an immunosuppressive effect by decreasing immunoglobulins in serum and cytokines in lymphoid organs.

Effects of zearalenone on oxidative stress and inflammation in weanling piglets

Zearalenone (ZEN) is a non-steroidal estrogenic mycotoxin produced by the fungi of Fusarium genera. Piglets were fed for 18 days with a control or a ZEN (316 ppb) contaminated diet. At the end of the experiment tissue samples were taken for assessment of: lymphocyte proliferation, monocytes and granulocytes respiratory burst, inflammatory cytokine synthesis in blood and liver, expression of genes involved in oxidative stress or in inflammation, plasma biochemical parameters, total antioxidant status and nitric oxide synthesis. In blood, ZEN increases the respiratory burst of monocytes and the inflammatory cytokine (TNF alpha, IL-1 beta, IFN gamma) synthesis, while in liver, ZEN decreases the synthesis of all inflammatory cytokines investigated. In liver and spleen, different effect on the expression of genes involved in oxidative stress and inflammation was observed. While in liver, ZEN decrease the expression of cyclooxigenase gene, but increase the expression of glutathione peroxydase and catalase genes; in spleen, ZEN induces a decrease of the superoxide dismutase gene expression together with an increase of the cyclooxigenase. In conclusion, our results showed that liver, spleen and blood may also be target tissues in weanling piglets fed ZEN contaminated diet, with different effects on oxidative stress and inflammation.

From the gut to the brain: journey and pathophysiological effects of the food-associated trichothecene mycotoxin deoxynivalenol

Mycotoxins are fungal secondary metabolites contaminating food and causing toxicity to animals and humans. Among the various mycotoxins found in crops used for food and feed production, the trichothecene toxin deoxynivalenol (DON or vomitoxin) is one of the most prevalent and hazardous. In addition to native toxins, food also contains a large amount of plant and fungal derivatives of DON, including acetyl-DON (3 and 15ADON), glucoside-DON (D3G), and potentially animal derivatives such as glucuronide metabolites (D3 and D15GA) present in animal tissues (e.g., blood, muscle and liver tissue). The present review summarizes previous and very recent experimental data collected in vivo and in vitro regarding the transport, detoxification/metabolism and physiological impact of DON and its derivatives on intestinal, immune, endocrine and neurologic functions during their journey from the gut to the brain.

Toxicity of deoxynivalenol and its acetylated derivatives on the intestine: differential effects on morphology, barrier function, tight junction proteins, and mitogen-activated protein kinases

The intestinal epithelium is the first barrier against food contaminants and is highly sensitive to mycotoxins, especially de oxynivalenol (DON). Consumption of DON-contaminated food is associated with outbreaks of gastroenteritis. In cereals and their byproducts, DON is present together with two acetylated derivatives, 3-ADON and 15-ADON. The aim of this study was to compare the intestinal toxicity of DON and A-DONs, using noncytotoxic doses. The toxicity was assessed using in vitro (intestinal epithelial cell line), ex vivo (intestinal explants), and in vivo (animals exposed to mycotoxin-contaminated diets) models. The effects were studied on cell proliferation, barrier function, and intestinal structure. The mechanism of toxicity was investigated by measuring the expression of the tight junction proteins and of phosphorylated ERK1/2, p38, and JNK, which are effectors of signaling pathway involved in cellular programs including embryogenesis, proliferation, differentiation, and apoptosis. On proliferating cells, 3-ADON was less toxic than DON, which was less toxic than 15-ADON. On differentiated cells, 15-ADON impaired the barrier function, whereas DON and 3-ADON did not have a significant effect. Similarly, ex vivo and in vivo, 15-ADON caused more histological lesions than DON or 3-ADON. At the molecular level, the 15-ADON activated the mitogen-activated protein kinases (MAPK) ERK1/2, p38, and JNK in the intestinal cell line, explants, and the jejunum from exposed animals at lower dose than DON and 3-ADON. Our results show that the higher toxicity of 15-DON is due to its ability to activate the MAPK. Given that cereal-based foods are contaminated with DON and acetylated-DON, the higher toxicity of 15-ADON should be taken into account.

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.

Analysis of the Fusarium graminearum species complex from wheat, barley and maize in South Africa provides evidence of species-specific differences in host preference

Species identity and trichothecene toxin potential of 560 members of the Fusarium graminearum species complex (FGSC) collected from diseased wheat, barley and maize in South Africa was determined using a microsphere-based multilocus genotyping assay. Although three trichothecene types (3-ADON, 15-ADON and NIV) were represented among these isolates, strains with the 15-ADON type predominated on all three hosts. A significant difference, however, was identified in the composition of FGSC pathogens associated with Gibberella ear rot (GER) of maize as compared to Fusarium head blight (FHB) of wheat or barley (P<0.001). F. graminearum accounted for more than 85% of the FGSC isolates associated with FHB of wheat and barley (N=425), and was also the dominant species among isolates from maize roots (N=35). However, with the exception of a single isolate identified as an interspecific hybrid between Fusariumboothii and F. graminearum, GER of maize (N=100) was exclusively associated with F. boothii. The predominance of F. graminearum among FHB isolates, and the near exclusivity of F. boothii among GER isolates, was observed across all cultivars, collection dates, and provinces sampled. Because these results suggest a difference in host preference among species of the FGSC, we hypothesize that F. graminearum may be less well adapted to infect maize ears than other members of the FGSC.

A theoretical study on vomitoxin and its tautomers

In the present work, the structural and electronic properties of vomitoxin (deoxynivalenol, a mycotoxin) and all of its possible tautomers have been investigated by the application of B3LYP/6-31G(d,p) type quantum chemical calculations. According to the results of the calculations, tautomer V(4) has been found to be the most stable one among all the structures both in the gas and aqueous phases. The calculations also indicated that, vomitoxin and V(2) possess the deepest and the highest lying HOMO levels, respectively. Hence, V(2) is to be more susceptible to oxidations than the others. On the other hand, V(5)(S) and vomitoxin have the lowest and the next lowest LUMO energies, respectively. Whereas, V(1) and V(2) possess quite highly lying (within the group) LUMO energy levels which result in comparatively unfavorable reduction potentials. Some important geometrical and physicochemical properties and the calculated IR spectra of the systems have also been reported in the study.

Mechanisms of deoxynivalenol-induced gene expression and apoptosis

Fusarium infection of agricultural staples such as wheat, barley and corn with concurrent production of deoxynivalenol (DON) and other trichothecene mycotoxins is an increasingly common problem worldwide. In addition to its emetic effects, chronic dietary exposure to DON causes impaired weight gain, anorexia, decreased nutritional efficiency and immune dysregulation in experimental animals. Trichothecenes are both immunostimulatory or immunosuppressive depending on dose, frequency and duration of exposure as well as type of immune function assay. Monocytes, macrophages, as well as T- and B-lymphocytes of the immune system can be cellular targets of DON and other trichothecenes. In vitro exposure to low trichothecene concentrations upregulates expression both transcriptionally and post-transcriptionally of cytokines, chemokines and inflammatory genes with concurrent immune stimulation, whereas exposure to high concentrations promotes leukocyte apoptosis with concomitant immune suppression. DON and other trichothecenes, via a mechanism known as the 'ribotoxic stress response', bind to ribosomes and rapidly activate mitogen-activated protein kinases (MAPKs). The latter are important transducers of downstream signalling events related to immune response and apoptosis. Using cloned macrophages, two critical upstream transducers of DON-induced MAPK activation have been identified. One transducer is double-stranded RNA (dsRNA)-activated protein kinase (PKR), a widely expressed serine/threonine protein kinase that can be activated by dsRNA, interferon and other agents. The other transducer is haematopoetic cell kinase (Hck), a non-receptor associated Src oncogene family kinase. Pharmacological inhibitors and gene suppression studies have revealed that Hck and PKR contribute to DON-induced gene expression and apoptosis. PKR, Hck and other kinases bind to the ribosome and are activated following DON interaction. Future studies will focus on the sequence of molecular events at the ribosome level that drive selective activation of these upstream kinases.

Cytotoxicity effects induced by Zearalenone metabolites, alpha Zearalenol and beta Zearalenol, on cultured Vero cells

Zearalenone (Zen) is a non-steroidal estrogenic mycotoxin produced by several species of Fusarium. It has been implicated in several mycotoxicosis in farm animals and in humans. The major metabolites of this mycotoxin in various species are alpha and beta Zearalenol. In vivo, Zen is mainly reduced to these alcoholic metabolites which cause reproductive tract disorders and impaired fertility due to their estrogenic activities. In this study, we examined the cytotoxicity of alpha and beta Zearalenol in cultured cells. For this purpose, the MTT assay was carried out and the influence of alpha and beta Zearalenol on protein and DNA syntheses was assessed. To evaluate the cell stress caused by these two metabolites, oxidative stress measured by MDA induction and stress protein induction (Hsp 70, Hsp 27) were tested. Results showed that alpha and beta Zearalenol were metabolites that caused cytotoxicity by inhibiting cell viability, protein and DNA syntheses and inducing oxidative damage and over-expression of stress proteins. However, the Zen metabolites exhibited lower toxicity than Zen, with beta zearalenol being the more active of the two metabolites.

Quantum chemical treatment of nivalenol and its tautomers

Nivalenol, a highly poisonous mycotoxin, and its possible tautomers have been considered theoretically by RHF/6-31G/d,p) and B3LYP/6-31G(d,p) calculations together with a semi-empirical PM3 method. The calculations revealed that some of the tautomers are more stable and exothermic than nivalenol. The calculated IR spectra as well as some geometrical and physicochemical properties of the structures considered have been presented.

Mycotoxins nivalenol and deoxynivalenol differentially modulate cytokine mRNA expression in Jurkat T cells

Deoxynivalenol (DON) and its hydroxylated form nivalenol (NIV) are Fusarium mycotoxins that occur in cereal grains alone or in combination. Several studies have shown that these metabolites affect lymphocyte functions. However, the molecular mechanisms underlying their activities are still partially known. To address this issue, we examined the influence of NIV and DON in modulating IFNgamma, IL-2 and IL-8 mRNA levels in Jurkat T cells. In PMA/ionomycin stimulated cells, pre-incubated with increasing concentrations of NIV, transcription was induced in the range 0.06-2 microM; higher concentrations of NIV were found non-stimulating (4 microM) or inhibitory (8 microM) for IFNgamma and IL-2 whereas IL-8 was still induced. DON administration elicited a similar profile for IL-8 and IFNgamma, whilst IL-2 mRNA was induced in a broader range of concentrations. Combination of NIV and DON at 1:1 and 1:10 ratios essentially restored the cytokine transcriptional pattern observed with NIV alone but the level of transcripts, with the exception of IL-8, peaked at lower concentrations suggesting interactive effects. Moreover both mycotoxins caused inhibition of cell proliferation, mediated by induction of apoptosis, confirming previous results and highlighting the usefulness of Jurkat as a T-cell model to study the effects of mycotoxins on the immune functions in humans.

Differential induction of apoptosis by type A and B trichothecenes in Jurkat T-lymphocytes

Several studies have shown that the mycotoxins T-2 toxin, diacetoxyscirpenol (DAS), deoxynivalenol (DON) and nivalenol (NIV) affect lymphocyte functioning. However, the molecular mechanisms underlying the immunomodulatory effects of these trichothecenes are not defined yet. In this study, the potency of the type A trichothecenes T-2 toxin and DAS, and the type B trichothecenes DON (and its metabolite de-epoxy-deoxynivalenol; DOM-1) and NIV to reduce mitochondrial activity and to induce apoptosis of Jurkat T cells (human T lymphocytes) were examined. T-2 toxin and DAS are much more cytotoxic at low concentrations than DON and NIV as shown by the AlamarBlue cytotoxicity assay. In addition, the mechanism whereby DON and NIV induced cytotoxicity is mainly via apoptosis as we observed phosphatidylserine externalization, mitochondrial release of cytochrome c, procaspase-3 degradation and Bcl-2 degradation. In contrast, type A trichothecenes reduce the mitochondrial activity at approximately 1000-fold lower concentrations than the type B trichothecenes, resulting in necrosis. These data suggest that the mechanisms resulting in cytotoxic effects are different for type A and type B trichothecenes.

Effect of the Fusarium toxin deoxynivalenol (DON) on IgA, IgM and IgG concentrations and proliferation of porcine blood lymphocytes

An important effect of the trichothecene mycotoxins is the impairment of the immune function, but immunotoxicity studies have mainly been conducted on the mouse model. In the present study, the effect of deoxynivalenol (DON) on the proliferation of ConA stimulated porcine peripheral blood lymphocytes (PBL) was assessed in vitro after adding of 70-560 ng DON per ml medium, and in vivo after chronic and acute (one single dose) dietary DON exposure (5.7 mg/kg). Immunoglobulin (IgA, IgG, IgM) concentrations were measured by ELISA in supernatants and serum of pigs. The proliferation rate was estimated with two different assays (BrdU incorporation and MTT cleavage). In vitro the ConA stimulated proliferation was inhibited to 50% (IC50) at 200 and 309 ng DON/ml for the BrdU and MTT assay, respectively, indicating a higher sensitivity of DNA synthesis to DON. Immunoglobulin concentrations in the supernatant after in vitro proliferation of PBL with increasing DON concentrations for 72 h were significantly decreased, with IC50 values of 120.6, 84.1 and 71.7 ng DON/ml for IgA, IgM and IgG, respectively. In vivo significant inhibition of lymphocyte proliferation was observed only in the DON acute group using the MTT assay, but values tended to be decreased in the BrdU assay and after chronic DON exposure. Immunoglobulins (IgA, IgM and IgG) in the supernatant of cultured lymphocytes were not significantly affected after dietary DON exposure. Serum IgA of pigs showed no significant differences between the groups, whereas IgM and IgG were significant increased in the DON acute group.

Patterns of trichothecene production, genetic variability, and virulence to wheat of Fusarium graminearum from smallholder farms in Nepal

Fusarium graminearum causes wheat head blight and contaminates grain with the trichothecenes 4-deoxynivalenol and nivalenol. Sequence analysis of trichothecene genes indicates that nivalenol production is the ancestral trait; however, deoxynivalenol producers occur worldwide and predominate in North and South America and in Europe. Analysis of a large field population (>500 strains) from Nepal identified three groups that were both genetically distinct and polymorphic for trichothecene production: SCAR1 comprising 95% deoxynivalenol producers, SCAR2 comprising 94% nivalenol producers, and SCAR3/5 comprising 34% deoxynivalenol producers/63% nivalenol producers. The ability to cause wheat head blight differed between SCAR groups and trichothecene chemotypes: deoxynivalenol producers were more virulent than nivalenol producers across all three SCAR groups and within the SCAR3/5 genetic background. These data support the hypothesis that production of deoxynivalenol rather than nivalenol confers a selective advantage to this important wheat pathogen.

Alkali extraction of beta-d-glucans from Saccharomyces cerevisiae cell wall and study of their adsorptive properties toward zearalenone

The isolated cell wall of Saccharomyces cerevisiae has some capacity to adsorb zearalenone (affinity near 30%) and reduce the bioavailability of toxins in the digestive tract. The adsorption process was quantified in vitro, and the data obtained when plotted with Hill's equation indicated a cooperative process. The model showed that the adsorption capacity was related to the yeast cell wall composition. This work focused on the role of various beta-d-glucan types in the efficacy of zearalenone adsorption by yeast cell wall and sought to elucidate some of the adsorption mechanisms. Zearalenone was mixed at 37 degrees C with a constant quantity of alkali-soluble or alkali-insoluble beta-d-glucans isolated from yeast cell walls, and the amount of adsorbed zearalenone was measured. Given that the alkali solubility of beta-d-glucans is a determining factor for their three-dimensional conformation and that the alkali-insoluble fraction had a greater affinity (up to 50%) than the alkali-soluble fraction ( approximately 16%), it was concluded that the three-dimensional structure strongly influences the adsorption process. The alkali insolubility of beta-d-glucans led to the formation of single and/or triple helices, which have been identified as the most favorable structures for zearalenone adsorption efficacy. The beta(1,3)-d-glucan and beta(1,6)-d-glucan compositions of the two alkali-extracted fractions and their involvement in the adsorption process are discussed.

Differential upregulation of TNF-alpha, IL-6, and IL-8 production by deoxynivalenol (vomitoxin) and other 8-ketotrichothecenes in a human macrophage model

The effects of deoxynivalenol (DON or vomitoxin) and four closely related 8-ketotrichothecenes on proinflammatory cytokine and chemokine production were evaluated in a clonal human macrophage model. U-937 cells, which represent a human monocytelike histocytic lymphoma, were differentiated into macrophages by preincubation with phorbol 12-myristate 13-acetate (PMA). Differentiated macrophages were incubated with DON in the absence or presence of lipopolysaccharide (LPS), and supernatant was analyzed by enzyme-linked immunosorbent assay (ELISA) for the proinflammatory cytokines interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-alpha), and for the chemokine interleukin-8 (IL-8). In the absence of LPS, DON at 500 or 1,000 ng/ml upregulated TNF-alpha production as early as 3 h and up to 6 h, whereas 100 to 1,000 ng/ml of DON significantly increased production of IL-6 from 3 to 24 h and IL-8 from 6 to 48 h. In cells costimulated with 0.2 microg/ml LPS, DON at 500 or 1000 ng/ml markedly superinduced TNF-alpha and IL-8 production. Although 100 ng/ml of DON also potentiated LPS-induced IL-6 production, 500 or 1,000 ng/ ml of the toxin suppressed the LPS-induced IL-6 response. Four other 8-ketotrichothecenes, fusarenon X, nivalenol, 3-acetyl DON, and 15-acetyl DON, were also capable of upregulating or suppressing TNF-alpha, IL-6, and IL-8 production at concentrations similar to that of DON. In total, the results suggest that DON and other 8-ketotrichothecenes have the potential to both directly induce and superinduce proinflammatory cytokine and chemokine expression in human macrophages, even at toxin concentrations that are cytotoxic.

A colorimetric technique for detecting trichothecenes and assessing relative potencies

We tested a novel colorimetric toxicity test, based on inhibition of beta-galactosidase activity in the yeast Kluyveromyces marxianus, for sensitivity to a range of mycotoxins. A variety of trichothecene mycotoxins could be detected. The order of toxicity established with this bioassay was verrucarin A > roridin A > T-2 toxin > diacetoxyscirpenol > HT-2 toxin > acetyl T-2 toxin > neosolaniol > fusarenon X > T-2 triol > scirpentriol > nivalenol > deoxynivalenol > T-2 tetraol. The sensitivity of detection was high, with the most potent trichothecene tested, verrucarin A, having a 50% effective concentration (concentration of toxin causing 50% inhibition) of 2 ng/ml. Other mycotoxins (cyclopiazonic acid, fumonisin B1, ochratoxin A, patulin, sterigmatocystin, tenuazonic acid, and zearalenone) could not be detected at up to 10 micrograms/ml, nor could aflatoxins B1 and M1 be detected at concentrations up to 25 micrograms/ml. This test should be useful for trichothecene detection and for studies of relevant interactions-both between trichothecenes themselves and between trichothecenes and other food constituents.

Effects of diets with graded levels of naturally deoxynivalenol-contaminated oats on immune response in growing pigs

A trial was conducted to evaluate the effect of including different levels of deoxynivalenol (DON)-contaminated oats in the complete diets of growing pigs on immune response and performance. The diets contained 0.6, 1.8 and 4.7 mg DON/kg, and both restricted and ad libitum feeding were used. Performance was recorded as weight gain, feed intake, efficiency of feed utilization and carcass quality. Immune response parameters recorded included primary and secondary antibody titres after injections of five different antigens: Human serum albumin (HSA), sheep red blood cells (SRBC), paratuberculosis vaccine (MPT), tetanus toxoid (TT) and diphteria toxoid (DT). A johnin test was also performed. Lymphocyte stimulation response was measured with three different mitogens (PWM, ConA and PHA). A significant, DON dose-dependent reduction in secondary antibody response to tetanus toxoid was observed. A slightly higher mitogen response after PHA stimulation in lymphocytes from the medium and high DON groups compared to the low DON group after 9 weeks was considered inconclusive. No other indication of dose-dependent immune response inhibition or stimulation was found. Significantly reduced feed intake with increased levels of DON was observed in groups fed restricted rations according to weight, but not in animals fed ad libitum.

Effects of mycotoxins on cytokine production and proliferation in EL-4 thymoma cells

The thymoma cell line EL4.IL-2 (EL-4) was used as a T-cell model to assess the immunotoxic effects of several mycotoxins produced by the Aspergillus-Penicillium and the Fusarium groups. EL-4 cells were stimulated with phorbol 12-myristate 12-acetate (PMA) in the presence of mycotoxins at various concentrations for 5 d and culture supernatants were analyzed for interleukins (IL) IL-2 and IL-5 by enzyme-linked immunosorbent assay (ELISA). The cytokine effects were further related to proliferation and cell viability using the MTT [3-(4,5-dimethylthiazol-2-yl) 2,5-diphenyltetrazolium bromide] assay with absorbance at 570 nm (A570) as the endpoint indicator. IL-2 and IL-5 levels were dramatically increased by cyclopiazonic acid at 50-1000 ng/ml, whereas IL-2 was significantly decreased at 10 microgram/ml. Proliferation was slightly increased at 100-1000 ng/ml cyclopiazonic acid but markedly depressed at 5 and 10 microgram/ml. When EL-4 cells were exposed to 5 and 10 microgram/ml of ochratoxin A, IL-2 production was markedly increased while IL-5 production was significantly decreased. The A570 was significantly decreased by ochratoxin A at 10 microgram/ml. IL-2 and Il-5 production was almost totally suppressed by patulin at concentrations > or = 500 ng/ml and by T-2 toxin at > or = 5 ng/ml. These effects occurred concurrently with marked depression of A570 in the MTT assay. Although A570 was unaffected by either zearalenone or alpha-zearalenol exposure, both IL-2 and IL-5 levels were significantly elevated by these toxins at 5 or 10 microgram/ml. IL-2 and IL-5 production were not affected in EL-4 cells cultured with either the Aspergillus-Penicillium toxins aflatoxin B1 and secalonic acid or the Fusarium toxins wortmannin, fumonisin B1, or fusaric acid at concentrations up to 10 microgram/ml. In total, the EL-4 culture studies indicated that cyclopiazonic acid, ochratoxin A, zearalenone, and alpha-zearalenol could stimulate cytokine production whereas patulin and T-2 toxin were inhibitory. Cytokine dysregulation was not always related directly to perturbations in proliferation. The results suggest that the EL-4 thymoma cell line could be a simple and effective in vitro model for evaluating immunotoxicity of various classes of environmental chemicals.

Structure-activity relationships and interactions among trichothecene mycotoxins as assessed by yeast bioassay

A yeast (Kluyveromyces marxianus) bioassay was used to establish the relative toxicity of 16 trichothecenes and some of their interactions. Removal of an isovaleryl group, one or two acetyl groups, or two acetyl plus an isovaleryl groups from T-2 toxin (T2) to form diacetoxyscirpenol, HT-2 toxin (HT2), T2-triol and T-2 tetraol (T2-4ol) decreased toxicity 7, 36, 276 and 558-fold, respectively. A combination of T2 and HT2, T2 and T2-4ol, deoxynivalenol (DON) and nivalenol (NIV), or DON and T2 exhibited synergistic (T2 and HT2 or DON and NIV) or antagonistic (DON and T2) responses.

In vitro vomitoxin exposure alters IgA and IgM secretion by CH12LX B cells. Relationship to proliferation and macromolecular synthesis

The CH12LX cell line was used as a clonal model to assess the direct effects of vomitoxin on IgM and IgA secretion in B cells. When vomitoxin was included in LPS-driven CH12LX B cell cultures, it had multiple effects on Ig secretion. Whereas vomitoxin doses of 115 and 120 ng/ml caused 50% inhibition (ID50) of IgA and IgM production, respectively, toxin concentrations in the 5 to 50 ng/ml range slightly stimulated IgA production. However, low vomitoxin doses did not induce switching of membrane IgM+ CH12LX B cells to membrane IgA+. Total cell number was unaffected at vomitoxin concentrations up to 100 ng/ml but dropped markedly at 200 ng/ml (ID50 = 170 ng/ml). Using the MTT reduction assay as another measure of viability and cell function, vomitoxin was also inhibitory (ID50 = 130 ng/ml). Both thymidine incorporation and leucine incorporation were also inhibited by the toxin with estimated ID50s being 120 and 110 ng/ml, respectively. The results indicate that although at high doses, vomitoxin inhibits proliferation, Ig secretion and DNA/protein synthesis in the clonal B cell model, the toxin marginally stimulated IgA secretion at lower doses.

Mycotoxicosis: mechanisms of immunosuppression

Mycotoxins are structurally diverse secondary metabolites of fungi that grow on feedstuffs consumed by animals and man. The clinical toxicologic syndromes caused by ingestion of fungal toxins have been characterized in domestic animals, poultry and laboratory animals and range from acute mortality to decreased production. Consumption of some mycotoxins, at levels that do not cause overt clinical mycotoxicosis, suppress immune functions and may decrease resistance to infectious disease. The sensitivity of the immune system to mycotoxin-induced immunosuppression arises from the vulnerability of the continually proliferating and differentiating cells that participate in immunemediated activities and regulate the complex communication network between cellular and humoral components. Mycotoxin-induced immunosuppression may be manifested as depressed T or B lymphocyte activity, suppressed immunoglobulin and antibody production, reduced complement or interferon activity, and impaired macrophage-effector cell function. Although the cellular-molecular basis for many of the specific immunosuppressive effects of mycotoxins are presently unclear, inhibition of DNA, RNA and protein synthesis via a variety of different mechanisms appears to be directly or indirectly responsible for the immunosuppressive action of many mycotoxins.

Immunochemical assessment of mycotoxins in 1989 grain foods: evidence for deoxynivalenol (vomitoxin) contamination

To assess the potential for mycotoxin contamination of the human food supply following the 1988 U.S. drought, 92 grain food samples were purchased from retail outlets in the summer of 1989 and surveyed for aflatoxin B1, zearalenone, and deoxynivalenol (DON [vomitoxin]) by monoclonal antibody-based competitive enzyme-linked immunosorbent assay (ELISA). Only one sample (buckwheat flour) was found to contain aflatoxin B1 (12 ng/g), whereas zearalenone was found in 26% of the samples at a mean concentration of 19 ng/g. In contrast, the DON ELISA was positive in 50% of the samples at a detection level of 1.0 micrograms/g. Between 63 and 88% of corn cereals, wheat flour/muffin mixes, rice cereals, and corn meal/muffin mixes yielded positive results for DON, whereas 25 to 50% of oat cereals, wheat- and oat-based cookies/crackers, corn chips, popcorn, and mixed-grain cereals were positive for DON. The mean DON content of the positive samples was 4.0 micrograms/g, and the minimum and maximum levels were 1.2 and 19 micrograms/g, respectively. When positive ELISA samples were also analyzed by high-performance liquid chromatography, a strong correlation between the two methods was found. The presence of DON in the two highest samples, corn meal and mixed-grain cereal, which contained 19 and 16 micrograms/g, respectively, was quantitatively confirmed by gas chromatography-mass spectrometry. The results indicated that DON was present in 1989 retail food products at concentrations that exceeded those found in previous market surveys and that have been experimentally associated with impaired animal health.

Cytotoxic and immunotoxic effects of Fusarium mycotoxins using a rapid colorimetric bioassay

A colorimetric MTT (tetrazolium salt) cleavage test was used to evaluate cytotoxicity of twenty-three Fusarium mycotoxins on two cultured human cell lines (K-562 and MIN-GL1) as well as their inhibitory effect on proliferation of phytohemagglutinin-stimulated human peripheral blood lymphocytes. The values of 50% inhibition of lymphocyte blastogenesis were very close to the 50% cytotoxic doses observed with the more sensitive cell line (MIN-GL1). T-2 toxin was the most cytotoxic with CD50 and ID50 values less than 1 ng/ml. Type A trichothecenes were the most cytotoxic followed by the type B trichothecenes; the non-trichothecenes were the least cytotoxic. The MTT cleavage test, in conjunction with cell culture, is a simple and rapid bioassay to evaluate cytotoxicity and immunotoxicity of Fusarium mycotoxins.

Murine lymphocyte proliferation impaired by substituted neosolaniols and calonectrins--Fusarium metabolites associated with trichothecene biosynthesis

The capacity of Fusarium secondary metabolites associated with trichothecene biosynthesis to inhibit murine spleen lymphocyte proliferation was evaluated and compared to that for well known trichothecenes. Activity of these compounds was not specific for B and T lymphocytes since they inhibited [3H]thymidine (TdR) incorporation in unstimulated, Con A- and LPS-stimulated lymphocytes to the same extent. Concentrations of 8-propionyl neosolaniol and 8-butyrylneosolaniol which inhibited [3H]Tdr uptake by 50% (ID50s) were 0.95 and 0.34 ng/ml, respectively. The ID50 for T-2 toxin was 0.26 ng/ml, indicating that there are minor alterations in 12,13-epoxytrichothecene toxicity resulting from the replacement of the isovaleryl moiety on C8 of the trichothecene skeleton with other bulky acyl groups. ID50 values for 4,15-diacetylnivalenol, fusarenon X, deoxynivalenol and 3-acetyldeoxynivalenol were 25, 38, 120 and 1800 ng/ml, respectively. Comparatively, ID50 values for 3,15-dideacetylcalonectrin, 15-deacetylcalonectrin, and 7,8-dihydroxycalonectrin were 390, 2700 and 2400 ng/ml, respectively, indicating that the modified calonectrins had equivalent or less toxicity. Lymphotoxicity of trichothecenes thus decreased upon substitution of acyl groups at the C8 with keto or hydroxy moieties and was also dependent on the nature of substitutions at the C3, C4 and C15 positions. Sambucinol and the trichothecene precursor trichodiene, metabolites which do not contain a 12,13-epoxide, did not inhibit lymphocyte proliferation. The results suggest the need for further assessment of occurrence and in vivo toxicity of Fusarium metabolites, particularly the substituted neosolaniols and calonectrins.

Elevated membrane IgA+ and CD4+ (T helper) populations in murine Peyer's patch and splenic lymphocytes during dietary administration of the trichothecene vomitoxin (deoxynivalenol)

Recent investigations indicate that dietary exposure to the trichothecene vomitoxin increases total and antigen-specific serum immunoglobulin A (IgA) and glomerular IgA accumulation in mice. In this study, the effects of 25 ppm dietary vomitoxin on the histological and lymphocytic profile of component immune organs in the mucosal lymphocyte migratory pathway were evaluated in the B6C3F1 mouse. Vomitoxin administration resulted in marked stimulation of the size and frequency of germinal centres in Peyer's patches, mesenteric lymph nodes and the spleen. A slight increase in the percentage of B cells in the Peyer's patch was observed, although vomitoxin treatment had no effect on the percentage of B cells in the spleen. The percentage of IgA+ cells in Peyer's patches and spleen were approximately twice that of controls at 4, 8 and 12 wk of vomitoxin exposure whereas the percentage of IgG+ cells decreased in these two organs. Exposure to vomitoxin increased the percentage of T cells in Peyer's patches and the spleen. The percentage of CD4+ cells (T helper subset) increased slightly in Peyer's patches and more markedly (30-50%) in the spleen following vomitoxin treatment. Contrastingly, there was only a slight increase in the percentage of CD8+ cells (T cytotoxic/suppressor subset) in the spleens of vomitoxin-treated mice in comparison with controls, and no effect in Peyer's patches. The relative effects of vomitoxin on these two T cells populations was also reflected in increased CD4+: CD8+ ratios in Peyer's patches and spleen. These results are consistent with the hypothesis that dietary vomitoxin modulates normal regulation of the IgA response at the Peyer's patch level and that this is manifested in an altered lymphocyte distribution pattern in both the mucosal and systemic compartment. Notably increased levels of IgA+ and CD4+ cells are indicative of IgA-producing progenitors and T helper subsets, respectively, that in tandem could favour IgA hyperproduction and elevated IgA in serum.

Uptake of the naturally occurring 3-alpha-hydroxy isomer of T-2 toxin by a murine B cell hybridoma

The uptake of the naturally occurring 3-alpha-hydroxy isomer of T-2 toxin (alpha-T-2 toxin) was investigated in a murine B cell hybridoma as a model for trichothecene-lymphocyte interactions. alpha-[3H]T-2 toxin was prepared by oxidation of T-2 toxin and reduction with [3H]NaBH4 followed by normal phase and reverse phase high-performance liquid chromatography. Uptake of alpha-[3H]T-2 toxin by hybridoma cells was both time- and concentration-dependent. The antibiotic anisomycin inhibited uptake of alpha-[3H]T-2 toxin by hybridoma cells, which suggests ribosomal involvement in the uptake mechanism. Uptake of alpha-[3H]T-2 toxin was also inhibited by verrucarin A, roridin A and deoxynivalenol, and the inhibition followed a trichothecene structure-activity rank similar to that established for protein synthesis inhibition and in vivo toxicity. The characteristics of uptake of alpha-[3H]T-2 toxin by isolated splenocytes were qualitatively similar to those of the hybridoma but accumulation at equilibrium was less. Accumulation of alpha-[3H]T-2 toxin by erythrocytes, cells lacking ribosomes, did not increase with time and was not affected by the presence of unlabelled toxin. The results suggested that specific accumulation and uptake of alpha-[3H]T-2 toxin by the murine B cell hybridoma and spleen cells were highly consistent with a model based on intracellular binding of T-2 toxin to ribosomes.

Altered serum immunoglobulin response to model intestinal antigens during dietary exposure to vomitoxin (deoxynivalenol)

The effect of dietary vomitoxin on the serum IgA and IgG responses to two model intestinal antigens, casein and cholera toxin (CT), were assessed in 4 experimental groups: (1) mice fed casein-based diet, (2) mice fed casein-based diet containing 25 ppm vomitoxin, (3) mice fed casein-based diet and immunized with CT, and (4) mice fed casein-based diet containing 25 ppm vomitoxin and immunized with CT. Unimmunized and CT-immunized mice that were fed vomitoxin exhibited increased levels of total serum IgA relative to matched control animals fed the standard diet. Relative concentrations of casein-specific IgA were greater in both unimmunized mice and CT-immunized mice fed standard diet with vomitoxin than in matched controls fed standard diet only. CT-specific serum IgA in CT-immunized mice was not affected by vomitoxin feeding, but relative levels of CT-specific IgA were higher in unimmunized mice fed vomitoxin than in unimmunized mice fed standard diet. Both casein- and CT-specific serum IgG were depressed in mice fed vomitoxin. Significant differences in total, casein-specific and CT-specific IgA within the intestinal contents were not observed between CT-immunized mice fed vomitoxin and those fed the control diet. The results suggest that vomitoxin altered regulation of the normal immunoglobulin response to intestinal antigens and that this was manifested in the systemic compartment.

Dysregulation of IgA production and IgA nephropathy induced by the trichothecene vomitoxin

The effect of dietary exposure to vomitoxin on serum immunoglobulin A (IgA) was evaluated in the B6C3F1 mouse. Levels of serum IgA were elevated maximally in mice fed 25 ppm vomitoxin in comparison with levels in mice fed 2, 10 or 50 ppm vomitoxin. Significant increases were detectable after as few as 4 wk in mice fed 25 ppm vomitoxin, and IgA levels were increased more than 17-fold after 24 wk of toxin exposure. Serum IgA also exhibited a marked shift from primarily monomeric IgA to primarily polymeric IgA during vomitoxin treatment. Serum IgG and IgM decreased in treated mice, suggesting that the effect was isotype-specific. Elevated serum IgA was not observed in mice when control diet was fed at levels equivalent to those consumed by vomitoxin-treated mice, which exhibited feed refusal. IgA production was significantly increased in both spontaneous and mitogen-stimulated splenocyte cultures from mice exposed to vomitoxin in comparison with cultures prepared from ad lib. or feed-restricted controls. Immunofluorescence staining revealed marked accumulation of mesangial IgA and electron microscopy showed electron-dense deposits in the glomeruli of vomitoxin-treated mice but not in those of controls. Dysregulation of IgA production and accumulation of glomerular IgA as observed in this study were highly analogous to the characteristics of human IgA nephropathy, the most common form of glomerulonephritis worldwide.