In vitro effects of trichothecenes on human dendritic cells

Comprehensive Insights into Ochratoxin A: Occurrence, Analysis, and Control Strategies

Ochratoxin A (OTA) is a toxic mycotoxin produced by some mold species from genera Penicillium and Aspergillus. OTA has been detected in cereals, cereal-derived products, dried fruits, wine, grape juice, beer, tea, coffee, cocoa, nuts, spices, licorice, processed meat, cheese, and other foods. OTA can induce a wide range of health effects attributable to its toxicological properties, including teratogenicity, immunotoxicity, carcinogenicity, genotoxicity, neurotoxicity, and hepatotoxicity. OTA is not only toxic to humans but also harmful to livestock like cows, goats, and poultry. This is why the European Union and various countries regulate the maximum permitted levels of OTA in foods. This review intends to summarize all the main aspects concerning OTA, starting from the chemical structure and fungi that produce it, its presence in food, its toxicity, and methods of analysis, as well as control strategies, including both fungal development and methods of inactivation of the molecule. Finally, the review provides some ideas for future approaches aimed at reducing the OTA levels in foods.

Immunotoxicity of Three Environmental Mycotoxins and Their Risks of Increasing Pathogen Infections

Aflatoxin B1 (AFB1), ochratoxin A (OTA), and deoxynivalenol (DON) are the three mycotoxins that have received the most scholarly attention and have been tested most routinely in clinics. These mycotoxins not only suppress immune responses but also induce inflammation and even increase susceptibility to pathogens. Here, we comprehensively reviewed the determining factors for the bidirectional immunotoxicity of the three mycotoxins, their effects on pathogens, and their action mechanisms. The determining factors include mycotoxin exposure doses and times, as well as species, sex, and some immunologic stimulants. Moreover, mycotoxin exposure can affect the infection severity of some pathogens, including bacteria, viruses, and parasites. Their specific action mechanisms include three aspects: (1) mycotoxin exposure directly promotes the proliferation of pathogenic microorganisms; (2) mycotoxins produce toxicity, destroy the integrity of the mucosal barrier, and promote inflammatory response, thereby improving the susceptibility of the host; (3) mycotoxins reduce the activity of some specific immune cells and induce immune suppression, resulting in reduced host resistance. The present review will provide a scientific basis for the control of these three mycotoxins and also provide a reference for research on the causes of increased subclinical infections.

Fuzzy Model for the Automatic Recognition of Human Dendritic Cells

Background and objective: Nowadays, foodborne illness is considered one of the most outgrowing diseases in the world, and studies show that its rate increases sharply each year. Foodborne illness is considered a public health problem which is caused by numerous factors, such as food intoxications, allergies, intolerances, etc. Mycotoxin is one of the food contaminants which is caused by various species of molds (or fungi), which, in turn, causes intoxications that can be chronic or acute. Thus, even low concentrations of Mycotoxin have a severely harmful impact on human health. It is, therefore, necessary to develop an assessment tool for evaluating their impact on the immune response. Recently, researchers have approved a new method of investigation using human dendritic cells, yet the analysis of the geometric properties of these cells is still visual. Moreover, this type of analysis is subjective, time-consuming, and difficult to perform manually. In this paper, we address the automation of this evaluation using image-processing techniques. Methods: Automatic classification approaches of microscopic dendritic cell images are developed to provide a fast and objective evaluation. The first proposed classifier is based on support vector machines (SVM) and Fisher's linear discriminant analysis (FLD) method. The FLD-SVM classifier does not provide satisfactory results due to the significant confusion between the inhibited cells on one hand, and the other two cell types (mature and immature) on the other hand. Then, another strategy was suggested to enhance dendritic cell recognition results that are emitted from microscopic images. This strategy is mainly based on fuzzy logic which allows us to consider the uncertainties and inaccuracies of the given data. Results: These proposed methods are tested on a real dataset consisting of 421 images of microscopic dendritic cells, where the fuzzy classification scheme efficiently improved the classification results by successfully classifying 96.77% of the dendritic cells. Conclusions: The fuzzy classification-based tools provide cell maturity and inhibition rates which help biologists evaluate severe health impacts caused by food contaminants.

An update on T2-toxins: metabolism, immunotoxicity mechanism and human assessment exposure of intestinal microbiota

Mycotoxins are naturally produced secondary metabolites or low molecular organic compounds produced by fungus with high diversification, which cause mycotoxicosis (food contamination) in humans and animals. T-2 toxin is simply one of the metabolites belonging to fungi trichothecene mycotoxin. Specifically, Trichothecenes-2 (T-2) mycotoxin of genus fusarium is considered one of the most hotspot agricultural commodities and carcinogenic compounds worldwide. There are well-known examples of salmonellosis in mice and pigs, necrotic enteritis in chickens, catfish enteric septicemia and colibacillosis in pigs as T-2 toxic agent. On the other hand, it has shown a significant reduction in the Salmonella population's aptitude in the pig intestinal tract. Although the impact of the excess Fusarium contaminants on humans in creating infectious illness is less well-known, some toxins are harmful; for example, salmonellosis and colibacillosis have been frequently observed in humans. More than 20 different metabolites are synthesized and excreted after ingestion, but the T-2 toxin is one of the most protuberant metabolites. Less absorption of mycotoxins in intestinal tract results in biotransformation of toxic metabolites into less toxic variants. In addition to these, effects of microbiota on harmful mycotoxins are not limited to intestinal tract, it may harm the other human vital organs. However, detoxification of microbiota is considered as an alternative way to decontaminate the feed for both animals and humans. These transformations of toxic metabolites depend upon the formation of metabolites. This study is complete in all perspectives regarding interactions between microbiota and mycotoxins, their mechanism and practical applications based on experimental studies.

Contamination, Detection and Control of Mycotoxins in Fruits and Vegetables

Mycotoxins are secondary metabolites produced by pathogenic fungi that colonize fruits and vegetables either during harvesting or during storage. Mycotoxin contamination in fruits and vegetables has been a major problem worldwide, which poses a serious threat to human and animal health through the food chain. This review systematically describes the major mycotoxigenic fungi and the produced mycotoxins in fruits and vegetables, analyzes recent mycotoxin detection technologies including chromatography coupled with detector (i.e., mass, ultraviolet, fluorescence, etc.) technology, electrochemical biosensors technology and immunological techniques, as well as summarizes the degradation and detoxification technologies of mycotoxins in fruits and vegetables, including physical, chemical and biological methods. The future prospect is also proposed to provide an overview and suggestions for future mycotoxin research directions.

Effects of a Low Dose of T-2 Toxin on the Percentage of T and B Lymphocytes and Cytokine Secretion in the Porcine Ileal Wall

Plant materials used in the production of pig feed are frequently contaminated with mycotoxins. T-2 toxin is a secondary metabolite of selected Fusarium species, and it can exert a harmful influence on living organisms. Most mycotoxins enter the body via the gastrointestinal tract, and they can modulate the gut-associated lymphoid tissue (GALT) function. However, little is known about the influence of low T-2 toxin doses on GALT. Therefore, the aim of this study was to evaluate the effect of T-2 toxin administered at 50% of the lowest-observed-adverse-effect level (LOAEL) on the percentage of CD2+ T cells, CD4+ T helper cells, CD8+ cytotoxic T cells, CD4+CD8+ double-positive T cells, TCRγδ+ cells, CD5+CD8- B1 cells, and CD21+ B2 cells, and the secretion of proinflammatory (IFN-γ, IL-1β, IL-2, IL-12/23p40, IL-17A), anti-inflammatory, and regulatory (IL-4, IL-10, TGF-β) cytokines in the porcine ileal wall. The results of the study revealed that T-2 toxin disrupts the development of tolerance to food antigens by enhancing the secretion of proinflammatory and regulatory cytokines and decreasing the production of anti-inflammatory TGF-β. T-2 toxin triggered the cellular response, which was manifested by an increase in the percentage of CD8+ T cells and a decrease in the percentage of B2 and Tγδ lymphocytes.

Fungal Toxins and Host Immune Responses

Fungi are ubiquitous organisms that thrive in diverse natural environments including soils, plants, animals, and the human body. In response to warmth, humidity, and moisture, certain fungi which grow on crops and harvested foodstuffs can produce mycotoxins; secondary metabolites which when ingested have a deleterious impact on health. Ongoing research indicates that some mycotoxins and, more recently, peptide toxins are also produced during active fungal infection in humans and experimental models. A combination of innate and adaptive immune recognition allows the host to eliminate invading pathogens from the body. However, imbalances in immune homeostasis often facilitate microbial infection. Despite the wide-ranging effects of fungal toxins on health, our understanding of toxin-mediated modulation of immune responses is incomplete. This review will explore the current understanding of fungal toxins and how they contribute to the modulation of host immunity.

Betulinic Acid Alleviates Spleen Oxidative Damage Induced by Acute Intraperitoneal Exposure to T-2 Toxin by Activating Nrf2 and Inhibiting MAPK Signaling Pathways

T-2 toxin, which is mainly produced by specific strains of Fusarium in nature, can induce immunotoxicity and oxidative stress, resulting in immune organ dysfunction and apoptosis. Betulinic acid (BA), a pentacyclic triterpenoids from nature plants, has been demonstrated to possess immunomodulating and antioxidative bioactivities. The purpose of the study was to explore the effect of BA on T-2 toxin-challenged spleen oxidative damage and further elucidate the underlying mechanism. We found that BA not only ameliorated the contents of serum total cholesterol (TC) and triglyceride (TG) but also restored the number of lymphocytes in T-2 toxin-induced mice. BA dose-dependently reduced the accumulation of reactive oxygen species (ROS), enhanced superoxide dismutase (SOD) activity, and decreased malondialdehyde (MDA) content, as well as increased the total antioxidant capacity (T-AOC) in the spleen of T-2-toxin-exposed mice. Moreover, BA reduced inflammatory cell infiltration in the spleen, improved the morphology of mitochondria and enriched the number of organelles in splenocytes, and dramatically attenuated T-2 toxin-triggered splenocyte apoptosis. Furthermore, administration of BA alleviated the protein phosphorylation of p38, c-Jun N-terminal kinase (JNK), and extracellular signal-regulated kinases (ERK); decreased the protein expression of kelch-like erythroid cell-derived protein with CNC homology [ECH]-associated protein1 (Keap1); and increased the protein expression of nuclear factor erythroid 2 [NF-E2]-related factor (Nrf2) and heme oxygenase-1 (HO-1) in the spleen. These findings demonstrate that BA defends against spleen oxidative damage associated with T-2 toxin injection by decreasing ROS accumulation and activating the Nrf2 signaling pathway, as well as inhibiting the mitogen-activated protein kinase (MAPK) signaling pathway.

Presence of Mycotoxins in Milk Thistle (Silybum marianum) Food Supplements: A Review

The consumption of herbal-based supplements, which are believed to have beneficial effects on human health with no side effects, has become popular around the world and this trend is still increasing. Silybum marianum (L.) Gaertn, commonly known as milk thistle (MT), is the most commonly studied herb associated with the treatment of liver diseases. The hepatoprotective effects of active substances in silymarin, with silybin being the main compound, have been demonstrated in many studies. However, MT can be affected by toxigenic micro-fungi and contaminated by mycotoxins with adverse effects. The beneficial effect of silymarin can thus be reduced or totally antagonized by mycotoxins. MT has proven to be affected by micro-fungi of the Fusarium and Alternaria genera, in particular, and their mycotoxins. Alternariol-methyl-ether (AME), alternariol (AOH), beauvericin (BEA), deoxynivalenol (DON), enniatin A (ENNA), enniatin A1 (ENNA1), enniatin B (ENNB), enniatin B1 (ENNB1), HT-2 toxin (HT-2), T-2 toxin (T-2), tentoxin (TEN), and zearalenone (ZEA) seem to be most significant in MT-based dietary supplements. This review focuses on summarizing cases of mycotoxins in MT to emphasize the need for strict monitoring and regulation, as mycotoxins in relation with MT-based dietary supplements are not covered by European Union legislation.

Automatic Human Dendritic Cells Segmentation Using K-Means Clustering and Chan-Vese Active Contour Model

BACKGROUND AND OBJECTIVE

Nowadays, the number of pathologies related to food are multiplied. Mycotoxins are one of the most severe food contaminants that cause serious effects on the human health. Therefore, it is necessary to develop an assessment tool for evaluating their impact on the immune response. Recently, a new investigational method using human dendritic cells was endorsed by biologists. Nevertheless, analysis of the morphological features and the behavior of these cells remains merely visual. In addition, this manual analysis is difficult and time-consuming. Here, we focus mainly on automating the evaluation process by using advanced image processing technology.

METHODS

An automatic segmentation approach of microscopic dendritic cell images is developed to provide a fast and objective evaluation. First, a combination of K-means clustering and mathematical morphology is used to detect dendritic cells. Second, a region-based Chan-Vese active contour model is used to segment the detected cells more precisely. Finally, dendritic cells are extracted by a filtering based on eccentricity measure.

RESULTS

The proposed scheme is tested on an actual dataset containing 421 microscopic dendritic cell images. The experimental results show high conformity between the results of the proposed scheme and ground-truth elaborated by biological expert. Moreover, a comparative study with other state-of-art segmentation schemes demonstrates the efficiency of the proposed method. It gives the highest average accuracy rate (99.42 %) compared to recent studied approaches.

CONCLUSIONS

The proposed image segmentation method for morphological analysis of dendrite inhibition can consistently be used as an assessment tool for biologists to facilitate the evaluation of serious health impacts of mycotoxins.

T-2 Toxin-Induced Oxidative Stress Leads to Imbalance of Mitochondrial Fission and Fusion to Activate Cellular Apoptosis in the Human Liver 7702 Cell Line

T-2 toxin, as a highly toxic mycotoxin to humans and animals, induces oxidative stress and apoptosis in various cells and tissues. Apoptosis and mitochondrial fusion/fission are two tightly interconnected processes that are crucial for maintaining physiological homeostasis. However, the role of mitochondrial fusion/fission in apoptosis of T-2 toxin remains unknown. Hence, we aimed to explore the putative role of mitochondrial fusion/fission on T-2 toxin induced apoptosis in normal human liver (HL-7702) cells. T-2 toxin treatment (0, 0.1, 1.0, or 10 μg/L) for 24 h caused decreased cell viability and ATP concentration and increased production of (ROS), as seen by a loss of mitochondrial membrane potential (∆Ψm) and increase in mitochondrial fragmentation. Subsequently, the mitochondrial dynamic imbalance was activated, evidenced by a dose-dependent decrease and increase in the protein expression of mitochondrial fusion (OPA1, Mfn1, and Mfn2) and fission (Drp1 and Fis1), respectively. Furthermore, the T-2 toxin promoted the release of cytochrome c from mitochondria to cytoplasm and induced cell apoptosis triggered by upregulation of Bax and Bax/Bcl-2 ratios, and further activated the caspase pathways. Taken together, these results indicate that altered mitochondrial dynamics induced by oxidative stress with T-2 toxin exposure likely contribute to mitochondrial injury and HL-7702 cell apoptosis.

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.

Effects of fusariotoxin co-exposure on THP-1 human immune cells

Deoxynivalenol (DON), nivalenol (NIV), T-2 toxin (T2), fumonisin B1 (FB1), zearalenone (ZEA), and moniliformin (MON) mycotoxins are common food and feed contaminants produced by Fusarium spp. However, while they are usually found to co-occur in a large range of commodities, only few data are available on mycotoxin co-exposure effects and cellular response mechanisms. In this study, the individual and combined toxic effects of these fusariotoxins were evaluated on the THP-1 human immune cell line as major fusariotoxins are mostly potent immunomodulators. In particular, four relevant fusariotoxin mixtures, namely DON-MON, DON-FB1, DON-ZEA, and NIV-T2, were studied using several parameters including cell viability as well as the expression of cell surface markers and the main mitogen-activated protein kinases (MAPKs). After 48 h exposure, a reduction of cell viability in a dose-dependent manner was observed for T2, the most cytotoxic mycotoxin, followed by NIV, DON, MON, FB1, and ZEA. Regarding mycotoxin mixtures, they mainly showed antagonism on cell viability reduction. Interestingly, at concentrations inhibiting 50% of cell viability, most viable cells exhibited surface marker loss and thus became potentially non-functional. In addition, during the first 18 h of exposure, the effects of mycotoxin mixtures on early cell apoptosis and necrosis were found to be different from those induced by the toxins alone. At the molecular level, after 1 h exposure of individual and combined mycotoxins, the three main MAPK signaling pathways (p38, SAPK/JNK, and ERK1/2) were activated, highlighting a fast reaction of the exposed cells even at low cytotoxicity levels.

The Effect of Deoxynivalenol on Selected Populations of Immunocompetent Cells in Porcine Blood-A Preliminary Study

Deoxynivalenol (DON) is one of the most prevalent mycotoxins in Europe. Pigs are an animal species that is most susceptible to this mycotoxin. Deoxynivalenol causes significant losses in pig production by lowering feed intake, decreasing daily weight gains, disrupting immune responses, and increasing susceptibility to diseases. The aim of this experiment was to determine the influence of feed contaminated with DON at concentrations insignificantly higher than recommended by the European Commission (900 µg/kg). The experimental feed contained 1008 μg DON/kg. The experiment was performed on eight weaners from the same litter. The animals were randomly divided into two groups: an experimental group (M, n = 4) fed contaminated feed and a control group (C, n = 4) administered feed free of mycotoxins. The experiment lasted for six weeks, and peripheral blood samples were collected from the animals for analyses of selected morphological parameters and changes in the percentages of CD4⁺8-, CD4-8⁺, and CD4⁺8⁺ lymphocytes and antigen-presenting cells (APC) with CD14⁺172⁺ (monocytes), CD172ahigh4-14- (conventional dendritic cells, cDC), and CD172adim4⁺14- (plasmacytoid dendritic cells, pDC) phenotypes. The morphological parameters of porcine blood samples were determined by flow cytometry with non-fluorescent particle-size calibration standards, and no differences were observed between groups M and C. An immunophenotyping analysis of lymphocytes and dendritic cells (DC) revealed an increase in the percentage of CD4⁺8-, CD172ahigh4-14-, and CD172adim4⁺14- cells, and a decrease in the number of CD4-8⁺ cells in group M. The results of this experiment suggest that prolonged exposure to low doses of DON can change the proportions of immunocompetent cells (a shift towards humoral immunity), without affecting their overall counts.

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.

Proteomic changes in chicken primary hepatocytes exposed to T-2 toxin are associated with oxidative stress and mitochondrial enhancement

T-2 toxin is a mycotoxin that is toxic to plants, animals, and humans. However, its molecular mechanism remains unclear, especially in chickens. In this study, using 2D electrophoresis with MALDI-TOF/TOF-MS, 53 proteins were identified as up- or downregulated by T-2 toxin in chicken primary hepatocytes. Functional network analysis by ingenuity pathway analysis showed that the top network altered by T-2 toxin is associated with neurological disease, cancer, organismal injury, and abnormalities. Most of the identified proteins were associated with one of eight functional classes, including cell redox homeostasis, transcriptional or translational regulation, cell cycle or cell proliferation, stress response, lipid metabolism, transport, carbohydrate metabolism, and protein degradation. Subcellular location categorization showed that the identified proteins were predominantly located in the mitochondrion (34%) and interestingly, the expression of all the identified mitochondrial proteins was increased. Further cellular analysis showed that T-2 toxin was able to induce the ROS accumulation and could lead to an increase in mitochondrial mass and adenosine 5'-triphosphate content, which indicated that oxidative stress and mitochondrial enhancement occurred in T-2 toxin-treated cells. Overall, these results characterize the global proteomic response of chicken primary hepatocytes to T-2 toxin, which may lead to a better understanding of the molecular mechanisms underlying its toxicity.

Cryptococcus gattii is killed by dendritic cells, but evades adaptive immunity by failing to induce dendritic cell maturation

During adaptive immunity to pathogens, dendritic cells (DCs) capture, kill, process, and present microbial Ags to T cells. Ag presentation is accompanied by DC maturation driven by appropriate costimulatory signals. However, current understanding of the intricate regulation of these processes remains limited. Cryptococcus gattii, an emerging fungal pathogen in the Pacific Northwest of Canada and the United States, fails to stimulate an effective immune response in otherwise healthy hosts leading to morbidity or death. Because immunity to fungal pathogens requires intact cell-mediated immunity initiated by DCs, we asked whether C. gattii causes dysregulation of DC functions. C. gattii was efficiently bound and internalized by human monocyte-derived DCs, trafficked to late phagolysosomes, and killed. Yet, even with this degree of DC activation, the organism evaded pathways leading to DC maturation. Despite the ability to recognize and kill C. gattii, immature DCs failed to mature; there was no increased expression of MHC class II, CD86, CD83, CD80, and CCR7, or decrease of CD11c and CD32, which resulted in suboptimal T cell responses. Remarkably, no increase in TNF-α was observed in the presence of C. gattii. However, addition of recombinant TNF-α or stimulation that led to TNF-α production restored DC maturation and restored T cell responses. Thus, despite early killing, C. gattii evades DC maturation, providing a potential explanation for its ability to infect immunocompetent individuals. We have also established that DCs retain the ability to recognize and kill C. gattii without triggering TNF-α, suggesting independent or divergent activation pathways among essential DC functions.

The effect of T-2 toxin on percentages of CD4+, CD8+, CD4+CD8+ and CD21+ lymphocytes, and mRNA expression levels of selected cytokines in porcine ileal Peyer’s patches

The immune system is one of the main toxicity targets of the T-2 toxin. In view of scant research data demonstrating the effect of T-2 on cellular and humoral responses in gut-associated lymphoid tissue (GALT), this study set out to investigate the effects of chronic exposure to low doses of the T-2 toxin (200 μg T-2 toxin kg-1 feed) on percentages of CD4+ and CD8+ T lymphocytes, CD4+/CD8+double-positive T lymphocytes, CD21+B cells, and IL-2, IFN-γ, IL-4 and IL-10 mRNA expression levels in porcine ileal Peyer’s patches. The investigated material comprised ileum sections sampled from piglets (aged 8-10 weeks, body weight of 15-18 kg) on days 14, 28 and 42 of the experiment.

After 42 days of exposure to T-2, a significant drop in the quantity of the IL-10 product was observed (R=0.94; S.E. 0.49-0.79; p<0.001). A gradual decrease in the amount of IL-4 and IFN-γ cytokine transcripts was found throughout the experiment, but the reported trend was not significant. On experimental days 14 and 42, a significant increase in the percentage of CD8+ T lymphocytes was observed in comparison with the control (p=0.04 and p=0.05, respectively), whereas on day 28, a significant decrease in the percentage of the above subpopulation was noted (p=0.00). The percentage of CD21+B cells in the experimental group decreased steadily in comparison with the control, and the observed drop was significant on days 28 and 42 (p=0.06 and p=0.00, respectively). On days 14 and 28, the percentages of CD4+and CD8+T lymphocytes were lower in the experimental animals than in the control group, and the drop reported on day 28 was statistically significant (p=0.03).

The emerging mycotoxin, enniatin B1, down-modulates the gastrointestinal toxicity of T-2 toxin in vitro on intestinal epithelial cells and ex vivo on intestinal explants

Enniatins, the most prevalent emerging mycotoxins, represent an emerging food safety issue, because of their common co-occurrence with other fusariotoxins such as trichothecenes co-produced by Fusarium spp on field grains and because of their extensive prevalence in grains. In this study, the intestinal toxicity of enniatin B1 (ENN) alone and mixed with the most toxic trichothecene T-2 toxin (T2) was characterized by using two biological models from pig, the most sensitive species: the intestinal cell line IPEC1 (in vitro exposure) and jejunal explants (ex vivo exposure). Dose-dependent decreases in cell proliferation in IPEC1 and in the histopathological scores of explants were observed for ENN at μM-levels and for T2 at nM-levels, with IC50 values for ENN of 15.8 and 29.7 μM, and for T2 of 9.3 and 15.1 nM in vitro and ex vivo, respectively. Interaction analysis by probabilistic and by determinist approaches showed a less than additive effect both in vitro and ex vivo, at IC50 values, with increasing antagonism with decreasing concentrations of toxins. The results obtained by the determinist median-effect dose analysis and by the nonlinear regression analysis were concordant. All the median-effect doses estimated for IPEC cells were included in the IC50 confidence intervals of the nonlinear regression fitting. Given the occurrence of enniatins, potential synergy following the co-occurrence of enniatins and the major fusariotoxins, especially trichothecene B deoxynivalenol should be investigated.

Deoxynivalenol impairs the immune functions of neutrophils

SCOPE

Deoxynivalenol (DON), a mycotoxin produced by Fusarium spp., is toxic to many animal species, with pigs being the most sensitive species to the toxin. The aim of the present study was to determine the effects of DON on pig polymorphonuclear cells (PMNs), the first line of defense against infection.

METHODS AND RESULTS

PMNs isolated from pig blood samples were stimulated with LPS to mimic infection. DON (0.5-10 μM) altered three main functions of pig PMNs: LPS-induced secretion of IL-8, chemotaxis, and phagocytosis capability. This alteration of PMN properties was due to apoptotis induced by DON exposure. Using Western blot and flow cytometry, we demonstrated that this process included the permeabilization of the mitochondrial outer membrane and the activation of caspase-3. The effect of DON was mediated by the phosphorylation of the p38 mitogen-activated protein kinase within the first 30 min of exposure.

CONCLUSION

This study provides evidence that low concentrations of DON can alter the immune functions of porcine PMNs and suggests the involvement of p38 mitogen-activated protein kinase in the signal transduction pathway. These immunosuppressive effects of DON may have implications for humans and/or animals when eating contaminated food/feed.

Trichothecene toxicity in eukaryotes: cellular and molecular mechanisms in plants and animals

Trichothecenes are sesquiterpenoid mycotoxins commonly found as contaminants in cereal grains and are a major health and food safety concern due to their toxicity to humans and farm animals. Trichothecenes are predominantly produced by the phytopathogenic Fusarium fungus, and in plants they act as a virulence factor aiding the spread of the fungus during disease development. Known for their inhibitory effect on eukaryotic protein synthesis, trichothecenes also induce oxidative stress, DNA damage and cell cycle arrest and affect cell membrane integrity and function in eukaryotic cells. In animals, trichothecenes can be either immunostimulatory or immunosuppressive and induce apoptosis via mitochondria-mediated or -independent pathway. In plants, trichothecenes induce programmed cell death via production of reactive oxygen species. Recent advances in molecular techniques have led to the elucidation of signal transduction pathways that manifest trichothecene toxicity in eukaryotes. In animals, trichothecenes induce mitogen-activated protein kinase (MAPK) signalling cascades via ribotoxic stress response and/or endoplasmic reticulum stress response. The upstream signalling events that lead to the activation trichothecene-induced ribotoxic stress response are discussed. In plants, trichothecenes exhibit elicitor-like activity leading to the inductions MAPKs and genes involved in oxidative stress, cell death and plant defence response. Trichothecenes might also modulate hormone-mediated defence signalling and abiotic stress signalling in plants.

T-2 toxin and HT-2 toxin in grain and grain-based commodities in Europe: occurrence, factors affecting occurrence, co-occurrence and toxicological effects

This paper presents an overview of the occurrence of T-2 toxin and HT-2 toxin in cereals in Europe and derived food products, factors influencing the occurrence, co-occurrence with other trichothecenes, and toxicological effects of T-2 and HT-2 in human. Of all cereals, oats showed to be most susceptible to T-2/HT-2 contamination. Particularly, oats grown in Scandinavia and UK in the period 2003-2007 were highly contaminated. This contamination has reduced in 2008 and 2009. In raw cereals, T-2 and HT-2 levels were highly correlated with each other in most instances, with the HT-2 level being two to seven times higher than the T-2 level. The toxin levels showed not to be correlated with levels of deoxynivalenol and nivalenol. The occurrence of T-2 and HT-2 in the field varied between years, regions, cereal grain varieties, sowing time, and precrop. Organically produced cereals contained lower T-2 and HT-2 levels as compared to conventionally grown cereals. Little or no effects from using fungicides was seen. Processing cereals resulted in low T-2 and HT-2 levels in food products, although oat products contained some T-2 and HT-2. The by-products from food processing, often used for animal feeding, frequently were highly contaminated. T-2 and HT-2 showed to have high acute and subacute toxicity, as they caused haematotoxic, immunotoxic, cytotoxic, and dermal effects. Carcinogenicity of T-2 and HT-2 in human has not been proven. Outbreaks of human toxicosis caused by trichothecenes, including T-2 and HT-2, have been reported. The present overview is deemed to be valuable for risk assessments at the European level, planned to be held by EFSA. It also provides directions for further research, including the ecology of the fungi responsible for T-2 and HT-2, and agronomical practices to reduce the contamination in the field.

Brain oxidative stress after dermal and subcutaneous exposure of T-2 toxin in mice

T-2 toxin belongs to group of mycotoxins and is found as a natural contaminant in cereals, feed and vegetables. In the present study we evaluated acute toxicity of dermal and subcutaneous exposure of T-2 toxin on brain oxidative stress in mice. Mice were exposed to 1 LD50 of T-2 toxin either by dermal (5.94 mg/kg) or subcutaneous (1.54 mg/kg body weight) route and sacrificed at 1, 3 and 7 days post-exposure. T-2 toxin treated animals showed time dependent increase in reactive oxygen species generation, glutathione depletion, lipid peroxidation and protein carbonyl content in brain in both the routes of exposure. Gene expression profile of antioxidant enzymes showed significant increase in superoxide dismutase and catalase in percutaneous route and glutathione reductase and glutathione peroxidase in subcutaneous route. Immunoblot analysis of antioxidant enzymes correlated with gene expression profile. T-2 toxin exposure resulted in down regulation of transcription factor Nrf2 and its downstream target genes of phase II detoxifying enzymes NQO1, Gclc, Gclm and hemeoxygenase-1. Results of our study show that percutaneously and subcutaneously applied T-2 toxin can cause brain oxidative damage possibly after crossing blood-brain barrier by altering its permeability.

Ammonium perfluorooctanoate substantially alters phenotype and cytokine secretion of human monocyte-derived dendritic cells in vitro

Perfluoroalkyl carboxylic acids (PFCA) are commercially used for their surfactant properties combined with chemical and thermal stability. Differentiation of peripheral monocytes to immature dendritic cells (DCs) in the presence of the PFCA, ammonium perfluorooctanoate (APFO, 200 microM) led to a considerably increased expression of CD86 and HLA-DR on immature DCs. However, these phenotypic changes were not reflected by an increased T cell-stimulatory capacity of the cells. Notably, activated, fully mature APFO-treated DCs secreted significantly less IL-12 and IL-10 than control cells. Thus, APFO at non-cytotoxic concentration affects the phenotype and cytokine secretion of human DCs.

Oxidative stress induction by T-2 toxin causes DNA damage and triggers apoptosis via caspase pathway in human cervical cancer cells

T-2 toxin is the most toxic trichothecene and both humans and animals suffer from several pathological conditions after consumption of foodstuffs contaminated with trichothecenes. We investigated the molecular mechanism of T-2 toxin induced cytotoxicity and cell death in HeLa cells. T-2 toxin at LC50 of 10 ng/ml caused time dependent increase in cytotoxicity as assessed by dye uptake, lactatedehydrogenase leakage and MTT assay. The toxin caused generation of reactive oxygen species as early as 30 min followed by significant depletion of glutathione levels and increased lipid peroxidation. The results indicate oxidative stress as underlying mechanism of cytotoxicity. Single stranded DNA damage after T-2 treatment was observed as early as 2 and 4h by DNA diffusion assay. The cells exhibited apoptotic morphology like condensed chromatin and nuclear fragmentation after 4h of treatment. Downstream of T-2 induced oxidative stress and DNA damage a time dependent increase in expression level of p53 protein was observed. The increase in Bax/Bcl2 ratio indicated shift in response, in favour of apoptotic process in T-2 toxin treated cells. Western blot analysis showed increase in levels of mitochondrial apoptogenic factors Bax, Bcl-2, cytochrome-c followed by activation of caspases-9, -3 and -7 leading to DNA fragmentation and apoptosis. In addition to caspase-dependent pathway, our results showed involvement of caspase-independent AIF pathway in T-2 induced apoptosis. Broad spectrum caspase inhibitor z-VAD-fmk could partially protect the cells from DNA damage but could not inhibit AIF induced oligonucleosomal DNA fragmentation beyond 4 h. Results of the study clearly show that oxidative stress is the underlying mechanism by which T-2 toxin causes DNA damage and apoptosis.

Our genes are not our destiny: incorporating molecular medicine into clinical practice

In many developed nations, the state of publicly administered health care is increasingly precarious as a result of escalating numbers of chronically ill patients, inadequate medical personnel and hospital facilities, as well as sparse funding for ongoing upgrades to state-of-the-art diagnostic and therapeutic technology - an increased emphasis on aetiology-centred medicine should be considered in order to achieve improved health for patients and populations. Medical practice patterns which are designed to provide quick and effective amelioration of signs and symptoms are frequently not an enduring solution to many health afflictions and chronic disease states. Recent scientific discovery has rendered the drug-oriented algorithmic paradigm commonly found in contemporary evidence-based medicine to be a reductionist approach to clinical practice. Unfolding evidence appears to support a genetic predisposition model of health and illness rather than a fatalistic predestination construct - modifiable epigenetic and environmental factors have enormous potential to influence clinical outcomes. By understanding and applying fundamental clinical principles relating to the emerging fields of molecular medicine, nutrigenomics and human exposure assessment, doctors will be empowered to address causality of affliction when possible and achieve sustained reprieve for many suffering patients.

Clinical medicine and the budding science of indoor mold exposure

Recent research and increasing discussion in the medical literature have brought attention to public health concerns associated with mold exposure. Many kinds of mold and their mold-associated products have the potential to disrupt human molecular biochemistry and physiology, resulting in various types of acute and chronic affliction. As environmental health has not been a focus for medical education, some clinicians are not fully aware of the scope of mold-related health problems and are inadequately equipped to investigate and manage possible cases of mold exposure. As a result, manifestations of mold-related illness often remain misdiagnosed and ineffectually treated. It is important for physicians to be aware of the pathogenesis, the manifestations, the investigations and the management of possible mold exposure. An overview of mold-related health problems and two case histories are presented for consideration.

In vitro atrazine exposure affects the phenotypic and functional maturation of dendritic cells

Recent data suggest that some of the immunotoxic effects of the herbicide atrazine, a very widely used pesticide, may be due to perturbations in dendritic cell (DC) function. As consequences of atrazine exposure on the phenotypic and functional maturation of DC have not been studied, our objective was, using the murine DC line, JAWSII, to determine whether atrazine will interfere with DC maturation. First, we characterized the maturation of JAWSII cells in vitro by inducing them to mature in the presence of growth factors and selected maturational stimuli in vitro. Next, we exposed the DC cell line to a concentration range of atrazine and examined its effects on phenotypic and functional maturation of DC. Atrazine exposure interfered with the phenotypic and functional maturation of DC at non-cytotoxic concentrations. Among the phenotypic changes caused by atrazine exposure was a dose-dependent removal of surface MHC-I with a significant decrease being observed at 1 microM concentration. In addition, atrazine exposure decreased the expression of the costimulatory molecule CD86 and it downregulated the expression of the CD11b and CD11c accessory molecules and the myeloid developmental marker CD14. When, for comparative purposes, we exposed primary thymic DC to atrazine, MHC-I and CD11c expression was also decreased. Phenotypic changes in JAWSII DC maturation were associated with functional inhibition of maturation as, albeit at higher concentrations, receptor-mediated antigen uptake was increased by atrazine. Thus, our data suggest that atrazine directly targets DC maturation and that toxicants such as atrazine that efficiently remove MHC-I molecules from the DC surface are likely to contribute to immune evasion.