Role of cyclooxygenase-2 in deoxynivalenol-induced immunoglobulin a nephropathy

Cytotoxicity of the Fusarium mycotoxin deoxynivalenol on mammalian and avian cell lines

Trichothecenes are mycotoxins that occur in grains and can lead to acute and chronic poisoning in animals and humans. Deoxynivalenol (DON) is a type B trichothecene affecting protein synthesis, immune system, leading to brain, blood and kidney disorders. The aim of this work was to evaluate in vitro the cytotoxicity and the pathological effects of DON in short-term experiments on cells from non-tumour and tumour permanent cell lines and to compare their sensitivity. Cell cultivation of BALB/c 3T3, DEC 99, MDA-MB-231, MCF-7 and Hela cells was performed. Quantitative and qualitative methods evaluating cytotoxicity on the base of statistical and morphological analyses for determining the impact on the viability and proliferative activity were used: Neutral Red Uptake (NRU) cytotoxicity test, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) test and fluorescence microscopy. The cytotoxic effect of DON was assessed after an exposure period of 24 h. DON treatment induced significant alterations in the growth and morphology of the cells, involving early and late apoptosis and necrosis signs. Statistically significant decrease of the viability of all cell lines was established at concentrations of DON starting from 1.9 µg/mL to 3.7 µg/mL, the mean IC50 concentrations were calculated. According to the IC50 values the hierarchical order of cell lines’ sensitivity was determined.

Celecoxib reduces Deoxynivalenol induced proliferation, inflammation and protein kinase C translocation via modulating downstream targets in mouse skin

Exposure to mycotoxins is mostly by ingestion but also occurs by the dermal and inhalation routes. The present study for the first time demonstrated that mycotoxin Deoxynivalenol (DON), permeates through Swiss albino mice skin, which demands awareness of health risks in people who are dermally exposed to mycotoxins especially agricultural farmers. Despite the widespread contamination of DON in food commodities studies to alleviate DON's toxicity are sparsely reported. Thus effective measures to combat mycotoxins associated toxicity remains an imperative aspect to be considered from the angle of dermal exposure. Topical application of Celecoxib (1-2 mg), followed by DON (100 μg) application on the dorsal side of mice, resulted in substantial decrease in DON-induced (i) edema, hyperplasia, cell proliferation (ii) inhibition of cytokine and prostaglandin-E2 levels (iii) phosphorylation of ERK1/2, JNK, p38, MAPKKs, CREB, P90-RSK (iv) downregulation of c-Jun, c- Fos, phospho-NF-kB and their downstream target proteins cyclin D1 and COX-2. Using Ro-31-8220 (Protein-Kinase-C inhibitor), it was observed PKC was responsible for DON induced upregulation of COX-2 and iNOS proteins. Treatment of Celecoxib decreased DON-induced translocation of Protein Kinase C isozymes (α,ε,γ), demonstrating the role of PKC in DON-mediated biochemical and molecular alterations responsible for its dermal toxicity. The present findings indicate that topical application of celecoxib is effective in the management of inflammatory skin disorders induced by foodborne fungal toxin DON. The skin permeation potential of Celecoxib, a selective cyclooxygenase-2 (COX-2) inhibitor NSAID, was also assessed, and the results indicated that the permeation was relatively lower as compared to the oral mode of administration. Hence topical use of celecoxib may be preferred over oral dosing because of lower systemic absorption and to avoid the unwanted side effects. This study provides a prospect for exploring the clinical efficacy of topically applied COX-2 inhibitors for the management of inflammatory skin disorders induced by foodborne fungal toxins.

The Effects of Deoxynivalenol and Zearalenone on the Pig Large Intestine. A Light and Electron Microscopy Study

The contamination of feed with mycotoxins results in reduced growth, feed refusal, immunosuppression, and health problems. Deoxynivalenol (DON) and zearalenone (ZEN) are among the most important mycotoxins. The aim of the study was to examine the effects of low doses of these mycotoxins on the histological structure and ultrastructure of the large intestine in the pig. The study was performed on 36 immature gilts of mixed breed (White Polish Big × Polish White Earhanging), which were divided into four groups administrated per os with ZEN at 40 µg/kg BW, DON at 12 µg/kg BW, a mixture of ZEN (40 µg/kg BW) and DON (12 µg/kg BW) or a placebo. The pigs were killed by intravenous overdose of pentobarbital after one, three, and six weeks of treatment. The cecum, ascending and descending colon samples were prepared for light and electron microscopy. Administration of toxins did not influence the architecture of the mucosa and submucosa in the large intestine. ZEN and ZEN + DON significantly decreased the number of goblet cells in the cecum and descending colon. The mycotoxins changed the number of lymphocytes and plasma cells in the large intestine, which usually increased in number. However, this effect differed between the intestine segments and toxins. Mycotoxins induced some changes in the ultrastructure of the mucosal epithelium. They did not affect the expression of proliferative cell nuclear antigen and the intestinal barrier permeability. The obtained results indicate that mycotoxins especially ZEN may influence the defense mechanisms of the large intestine.

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.

Dysregulation of energy balance by trichothecene mycotoxins: Mechanisms and prospects

Trichothecenes are toxic metabolites produced by fungi that constitute a worldwide hazard for agricultural production and both animal and human health. More than 40 countries have introduced regulations or guidelines for food and feed contamination levels of the most prevalent trichothecene, deoxynivalenol (DON), on the basis of its ability to cause growth suppression. With the development of analytical tools, evaluation of food contamination and exposure revealed that a significant proportion of the human population is chronically exposed to DON doses exceeding the provisional maximum tolerable daily dose. Accordingly, a better understanding of trichothecene impact on health is needed. Upon exposure to low or moderate doses, DON and other trichothecenes induce anorexia, vomiting and reduced weight gain. Several recent studies have addressed the mechanisms by which trichothecenes induce these symptoms and revealed a multifaceted action targeting gut, liver and brain and causing dysregulation in neuroendocrine signaling, immune responses, growth hormone axis, and central neurocircuitries involved in energy homeostasis. Newly identified trichothecene toxicosis biomarkers are just beginning to be exploited and already open up new questions on the potential harmful effects of chronic exposure to DON at apparently asymptomatic very low levels. This review summarizes our current understanding of the effects of DON and other trichothecenes on food intake and weight growth.

Comparative effects of n-3, n-6 and n-9 unsaturated fatty acid-rich diet consumption on lupus nephritis, autoantibody production and CD4+ T cell-related gene responses in the autoimmune NZBWF1 mouse

Mortality from systemic lupus erythematosus (SLE), a prototypical autoimmune disease, correlates with the onset and severity of kidney glomerulonephritis. There are both preclinical and clinical evidence that SLE patients may benefit from consumption of n-3 polyunsaturated fatty acids (PUFA) found in fish oil, but the mechanisms remain unclear. Here we employed the NZBWF1 SLE mouse model to compare the effects of dietary lipids on the onset and severity of autoimmune glomerulonephritis after consuming: 1) n-3 PUFA-rich diet containing docosahexaenoic acid-enriched fish oil (DFO), 2) n-6 PUFA-rich Western-type diet containing corn oil (CRN) or 3) n-9 monounsaturated fatty acid (MUFA)-rich Mediterranean-type diet containing high oleic safflower oil (HOS). Elevated plasma autoantibodies, proteinuria and glomerulonephritis were evident in mice fed either the n-6 PUFA or n-9 MUFA diets, however, all three endpoints were markedly attenuated in mice that consumed the n-3 PUFA diet until 34 wk of age. A focused PCR array was used to relate these findings to the expression of 84 genes associated with CD4+ T cell function in the spleen and kidney both prior to and after the onset of the autoimmune nephritis. n-3 PUFA suppression of autoimmunity in NZBWF1 mice was found to co-occur with a generalized downregulation of CD4+ T cell-related genes in kidney and/or spleen at wk 34. These genes were associated with the inflammatory response, antigen presentation, T cell activation, B cell activation/differentiation and leukocyte recruitment. Quantitative RT-PCR of representative affected genes confirmed that n-3 PUFA consumption was associated with reduced expression of CD80, CTLA-4, IL-10, IL-18, CCL-5, CXCR3, IL-6, TNF-α and osteopontin mRNAs in kidney and/or spleens as compared to mice fed n-6 PUFA or n-9 MUFA diets. Remarkably, many of the genes identified in this study are currently under consideration as biomarkers and/or biotherapeutic targets for SLE and other autoimmune diseases.

Advances in deoxynivalenol toxicity mechanisms: the brain as a target

Deoxynivalenol (DON), mainly produced by Fusarium fungi, and also commonly called vomitoxin, is a trichothecene mycotoxin. It is one of the most abundant trichothecenes which contaminate cereals consumed by farm animals and humans. The extent of cereal contamination is strongly associated with rainfall and moisture at the time of flowering and with grain storage conditions. DON consumption may result in intoxication, the severity of which is dose-dependent and may lead to different symptoms including anorexia, vomiting, reduced weight gain, neuroendocrine changes, immunological effects, diarrhea, leukocytosis, hemorrhage or circulatory shock. During the last two decades, many studies have described DON toxicity using diverse animal species as a model. While the action of the toxin on peripheral organs and tissues is well documented, data illustrating its effect on the brain are significantly less abundant. Yet, DON is known to affect the central nervous system. Recent studies have provided new evidence and detail regarding the action of the toxin on the brain. The purpose of the present review is to summarize critical studies illustrating this central action of the toxin and to suggest research perspectives in this field.

Anorexia induction by the trichothecene deoxynivalenol (vomitoxin) is mediated by the release of the gut satiety hormone peptide YY

Consumption of deoxynivalenol (DON), a trichothecene mycotoxin known to commonly contaminate grain-based foods, suppresses growth of experimental animals, thus raising concerns over its potential to adversely affect young children. Although this growth impairment is believed to result from anorexia, the initiating mechanisms for appetite suppression remain unknown. Here, we tested the hypothesis that DON induces the release of satiety hormones and that this response corresponds to the toxin's anorectic action. Acute ip exposure to DON had no effect on plasma glucagon-like peptide-1, leptin, amylin, pancreatic polypeptide, gastric inhibitory peptide, or ghrelin; however, the toxin was found to robustly elevate peptide YY (PYY) and cholecystokinin (CCK). Specifically, ip exposure to DON at 1 and 5mg/kg bw induced PYY by up to 2.5-fold and CCK by up to 4.1-fold. These responses peaked within 15-120 min and lasted up to 120 min (CCK) and 240 min (PPY), corresponding with depressed rates of food intake. Direct administration of exogenous PYY or CCK similarly caused reduced food intake. Food intake experiments using the NPY2 receptor antagonist BIIE0246 and the CCK1A receptor antagonist devazepide, individually, suggested that PYY mediated DON-induced anorexia but CCK did not. Orolingual exposure to DON induced plasma PYY and CCK elevation and anorexia comparable with that observed for ip exposure. Taken together, these findings suggest that PYY might be one critical mediator of DON-induced anorexia and, ultimately, growth suppression.

Central inflammation and sickness-like behavior induced by the food contaminant deoxynivalenol: a PGE2-independent mechanism

Deoxynivalenol (DON), one of the most abundant trichothecenes found on cereals, has been implicated in mycotoxicoses in both humans and farm animals. Low-dose toxicity is characterized by reduced weight gain, diminished nutritional efficiency, and immunologic effects. The levels and patterns of human food commodity contamination justify that DON consumption constitutes a public health issue. DON stability during processing and cooking explains its large presence in human food. We characterized here DON intoxication by showing that the toxin concomitantly affects feeding behavior, body temperature, and locomotor activity after both per os and central administration. Using c-Fos expression mapping, we identified the neuronal structures activated in response to DON and observed that the pattern of neuronal populations activated by the toxin resembled those induced by inflammatory signals. By real-time PCR, we report the first evidences for a DON-induced central inflammation, attested by the strong upregulation of interleukin-1β, interleukin-6, tumor necrosis factor-α, cyclooxygenase-2, and microsomal prostaglandin synthase-1 (mPGES-1) messenger RNA. However, silencing prostaglandins E2 signaling pathways using mPGES-1 knockout mice, which are resistant to cytokine-induced sickness behavior, did not modify the responses to the toxin. These results reveal that, despite strong similarities, behavioral changes observed after DON intoxication differ from classical sickness behavior evoked by inflammatory cytokines.

Some food-associated mycotoxins as potential risk factors in humans predisposed to chronic intestinal inflammatory diseases

Mycotoxins are fungal metabolites able to affect the functions of numerous tissues and organs in animals and humans, including intestinal and immune systems. However, the potential link between exposure to some mycotoxins and human chronic intestinal inflammatory diseases, such as celiac and Crohn's diseases or ulcerative colitis, has not been investigated. Instead, several theories based on bacterial, immunological or neurological events have been elaborated to explain the etiology of these pathologies. Here we reviewed the literature on mycotoxin-induced intestinal dysfunctions and compared these perturbations to the impairments of intestinal functions typically observed in human chronic intestinal inflammatory diseases. Converging evidence based on various cellular and animal studies show that several mycotoxins induce intestinal alterations that are similar to those observed at the onset and during the progression of inflammatory bowel diseases. Although epidemiologic evidence is still required, existing data are sufficient to suspect a role of some food-associated mycotoxins in the induction and/or persistence of human chronic intestinal inflammatory diseases in genetically predisposed patients.

Dose-dependent effects of T-2 toxin on performance, lipid peroxidation, and genotoxicity in broiler chickens

The objective of the present study was to evaluate the effects of different concentrations of T-2 toxin in feed on performance, lipid peroxidation, and genotoxicity in vivo. For a 17-d period, T-2 toxin was added to the diet of the chickens. Fifty 22-d-old male broiler chickens were divided into 5 groups that were supplemented with different concentrations of T-2 toxin: control (0.0 mg/kg of feed), T 0.5 (0.5 mg/kg of feed), T 1.5 (1.5 mg/kg of feed), T 4.5 (4.5 mg/kg of feed), and T 13.5 (13.5 mg/kg of feed). Deoxyribonucleic acid fragmentation in spleen leukocytes, malondialdehyde in plasma and liver, total plasma antioxidative status, glutathione peroxidase activity, and total serum Ig (IgA and IgG) were measured. Feed consumption and BW gain decreased when the concentration of T-2 toxin was 4.5 and 13.5 mg/kg of feed. Compared with the control group, the rate of DNA damage increased significantly in the group fed 13.5 mg of T-2 toxin/kg of feed. In contrast to DNA fragmentation, indicators of oxidative stress did not show differences between groups fed T-2 toxin and the control. More serum IgA was detected in the group T 13.5 compared with the control, whereas there were no differences in serum IgG levels. The results of the present study indicate that impaired performance, DNA fragmentation in spleen leukocytes, and elevated serum IgA levels induced by T-2 toxin are dose-dependent. Based on our results, we could not confirm the hypothesis that oxidative stress is among the mechanisms by which T-2 toxin induces DNA fragmentation.

Expression of COX-2 and hsp72 in peritoneal macrophages after an acute ochratoxin A treatment in mice

Ochratoxin A (OTA) is a secondary fungal metabolite produced by Aspergillus and Penicillium strains that elicits a broad spectrum of toxicological effects in animals and man. A single oral OTA administration (10 mg/kg) in mice induced after 24 h oxidative damage and polymorphonuclear leukocyte (PMN) infiltration in parenchymal organs. In fact, OTA treatment increased lipid peroxidation (via malondialdehyde formation) in kidney and liver and PMN accumulation in duodenum, as shown by myeloperoxidase activity. Following in vivo OTA treatment an increase of cyclooxygenase-2 and of heat shock protein 72 expression was evidenced in peritoneal macrophage lysates by Western blot. That OTA modulates these proteins involved in the inflammatory process indicates that the mycotoxin is able to activate immune cells. This study suggests that the oxidative stress, the neutrophil accumulation in parenchymal tissues and the modulation of inflammatory parameters in peritoneal macrophages induced by OTA are involved in its toxicity, and represent early events related to several aspects of OTA mycotoxicosis.

Effects of the Fusarium toxin deoxynivalenol from naturally contaminated wheat given subchronically or as one single dose on the in vivo protein synthesis of peripheral blood lymphocytes and plasma proteins in the pig

Trichothecenes, such as deoxynivalenol (DON), are known to inhibit the protein synthesis in vitro by binding at the 60S subunit of eukaryotic ribosomes. Therefore, cells and tissues with high protein turnover, such as lymphocytes and the liver (albumin and fibrinogen synthesis), were suggested to react most sensitively to DON. However, to the author's knowledge this observation was not proven in vivo in pigs, which were regarded as the farm animals most susceptible to DON. A total of 31 castrated male, crossbred German Landrace x Pietrain pigs weighing approx. 40 kg were fed a DON contaminated diet (5.7 mg/kg) either acutely (one single dose) or subchronically (4 weeks) or a control diet (0.1 mg/kg). In addition, one group received an intravenous injection of 53 microg DON/kg LW. One hour after feeding, a "flooding dose" of the stable isotope l-[(2)H(5)]-phenylalanine (125 mg/kg LW) was given and frequent blood samples (permanent catheter) were collected over a 60 min period. The molar percent excess (MPE) of plasma free and protein-bound phenylalanine were measured by GC/MS. No differences could be observed in the plasma concentrations of total protein, albumin, fibrinogen and serum enzymes between the groups. On the other hand, fractional synthesis rates (FSR, %/d) of albumin were significantly decreased by 43%, 45% and 26% and FSR of lymphocytes declined by 27%, 19% and 24%, whereas fibrinogen was not significantly affected after subchronic or one single oral and intravenous DON exposure, respectively. Additionally, the absolute synthesis rate (ASR, g/d) of albumin and the proportion of albumin to total body protein synthesis were reduced in the same manner, whereas the albumin secretion time ranged between 6.8 and 34.4 min and was not affected by treatment. In conclusion, the flooding dose technique appeared to be suitable for distinguishing DON-related effects on the protein synthesis, while determination of plasma protein concentrations seemed not to be an appropriate parameter.