T-2 toxin impairment of enteric reovirus clearance in the mouse associated with suppressed immunoglobulin and IFN-gamma responses

The Mechanisms of Altered Blood-Brain Barrier Permeability in CD19 CAR T-Cell Recipients

Cluster of differentiation 19 (CD19) chimeric antigen receptor (CAR) T cells are a highly effective immunotherapy for relapsed and refractory B-cell malignancies, but their utility can be limited by the development of immune effector cell-associated neurotoxicity syndrome (ICANS). The recent discovery of CD19 expression on the pericytes in the blood-brain barrier (BBB) suggests an important off-target mechanism for ICANS development. In addition, the release of systemic cytokines stimulated by the engagement of CD19 with the CAR T cells can cause endothelial activation and decreased expression of tight junction molecules, further damaging the integrity of the BBB. Once within the brain microenvironment, cytokines trigger a cytokine-specific cascade of neuroinflammatory responses, which manifest clinically as a spectrum of neurological changes. Brain imaging is frequently negative or nonspecific, and treatment involves close neurologic monitoring, supportive care, interleukin antagonists, and steroids. The goal of this review is to inform readers about the normal development and microstructure of the BBB, its unique susceptibility to CD19 CAR T cells, the role of individual cytokines on specific elements of the brain's microstructural environment, and the clinical and imaging manifestations of ICANS. Our review will link cellular pathophysiology with the clinical and radiological manifestations of a complex clinical entity.

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.

Hypoxia, oxidative stress, and immune evasion: a trinity of the trichothecenes T-2 toxin and deoxynivalenol (DON)

T-2 toxin and deoxynivalenol (DON) are type A and B trichothecenes, respectively. They widely occur as pollutants in food and crops and cause a series of toxicities, including immunotoxicity, hepatotoxicity, and neurotoxicity. Oxidative stress is the primary mechanistic basis of these toxic effects. Increasing amounts of evidence have shown that mitochondria are significant targets of apoptosis caused by T-2 toxin- and DON-induced oxidative stress via regulation of Bax/B-cell lymphoma-2 and caspase-3/caspase-9 signaling. DNA methylation and autophagy are involved in oxidative stress related to apoptosis, and hypoxia and immune evasion are related to oxidative stress in this context. Hypoxia induces oxidative stress by stimulating mitochondrial reactive oxygen species production and regulates the expression of cytokines, such as interleukin-1β and tumor necrosis factor-α. Programmed cell death-ligand 1 is upregulated by these cytokines and by hypoxia-inducible factor-1, which allows it to bind to programmed cell death-1 to enable escape of immune cell surveillance and achievement of immune evasion. This review concentrates on novel findings regarding the oxidative stress mechanisms of the trichothecenes T-2 toxin and DON. Importantly, we discuss the new evidence regarding the connection of hypoxia and immune evasion with oxidative stress in this context. Finally, the trinity of hypoxia, oxidative stress and immune evasion is highlighted. This work will be conducive to an improved understanding of the oxidative stress caused by trichothecene mycotoxins.

Betulinic Acid Ameliorates the T-2 Toxin-Triggered Intestinal Impairment in Mice by Inhibiting Inflammation and Mucosal Barrier Dysfunction through the NF-κB Signaling Pathway

T-2 toxin, a trichothecene mycotoxin produced by Fusarium, is widely distributed in crops and animal feed and frequently induces intestinal damage. Betulinic acid (BA), a plant-derived pentacyclic lupane-type triterpene, possesses potential immunomodulatory, antioxidant and anti-inflammatory biological properties. The current study aimed to explore the protective effect and molecular mechanisms of BA on intestinal mucosal impairment provoked by acute exposure to T-2 toxin. Mice were intragastrically administered BA (0.25, 0.5, or 1 mg/kg) daily for 2 weeks and then injected intraperitoneally with T-2 toxin (4 mg/kg) once to induce an intestinal impairment. BA pretreatment inhibited the loss of antioxidant capacity in the intestine of T-2 toxin-treated mice by elevating the levels of CAT, GSH-PX and GSH and reducing the accumulation of MDA. In addition, BA pretreatment alleviated the T-2 toxin-triggered intestinal immune barrier dysregulation by increasing the SIgA level in the intestine at dosages of 0.5 and 1 mg/kg, increasing IgG and IgM levels in serum at dosages of 0.5 and 1 mg/kg and restoring the intestinal C3 and C4 levels at a dosage of 1 mg/kg. BA administration at a dosage of 1 mg/kg also improved the intestinal chemical barrier by decreasing the serum level of DAO. Moreover, BA pretreatment improved the intestinal physical barrier via boosting the expression of ZO-1 and Occludin mRNAs and restoring the morphology of intestinal villi that was altered by T-2 toxin. Furthermore, treatment with 1 mg/kg BA downregulated the expression of p-NF-κB and p-IκB-α proteins in the intestine, while all doses of BA suppressed the pro-inflammatory cytokines expression of IL-1β, IL-6 and TNF-α mRNAs and increased the anti-inflammatory cytokine expression of IL-10 mRNA in the intestine of T-2 toxin-exposed mice. BA was proposed to exert a protective effect on intestinal mucosal disruption in T-2 toxin-stimulated mice by enhancing the intestinal antioxidant capacity, inhibiting the secretion of inflammatory cytokines and repairing intestinal mucosal barrier functions, which may be associated with BA-mediated inhibition of the NF-κB signaling pathway activation.

Mycotoxin and Gut Microbiota Interactions

The interactions between mycotoxins and gut microbiota were discovered early in animals and explained part of the differences in susceptibility to mycotoxins among species. Isolation of microbes present in the gut responsible for biotransformation of mycotoxins into less toxic metabolites and for binding mycotoxins led to the development of probiotics, enzymes, and cell extracts that are used to prevent mycotoxin toxicity in animals. More recently, bioactivation of mycotoxins into toxic compounds, notably through the hydrolysis of masked mycotoxins, revealed that the health benefits of the effect of the gut microbiota on mycotoxins can vary strongly depending on the mycotoxin and the microbe concerned. Interactions between mycotoxins and gut microbiota can also be observed through the effect of mycotoxins on the gut microbiota. Changes of gut microbiota secondary to mycotoxin exposure may be the consequence of the antimicrobial properties of mycotoxins or the toxic effect of mycotoxins on epithelial and immune cells in the gut, and liberation of antimicrobial peptides by these cells. Whatever the mechanism involved, exposure to mycotoxins leads to changes in the gut microbiota composition at the phylum, genus, and species level. These changes can lead to disruption of the gut barrier function and bacterial translocation. Changes in the gut microbiota composition can also modulate the toxicity of toxic compounds, such as bacterial toxins and of mycotoxins themselves. A last consequence for health of the change in the gut microbiota secondary to exposure to mycotoxins is suspected through variations observed in the amount and composition of the volatile fatty acids and sphingolipids that are normally present in the digesta, and that can contribute to the occurrence of chronic diseases in human. The purpose of this work is to review what is known about mycotoxin and gut microbiota interactions, the mechanisms involved in these interactions, and their practical application, and to identify knowledge gaps and future research needs.

Immunopathological effects of experimental T-2 mycotoxicosis in Wistar rats

It is well known that T-2 toxin has cytotoxic radiomimetic like effects on the immune system. Because of scant research data demonstrating the chronic effects of low doses of the T-2 toxin on humoral and cellular responses in rats, the present experiment was undertaken. The animals were divided into four groups, namely, group I (0.5 ppm), group II (0.75 ppm) and group III (1.0 ppm) and group IV (control) were given toxin-free diet for 12 weeks and eight animals each were sacrificed at 2, 4, 6, 8, 10, and 12-week of the experimental period. The humoral immune response was evaluated based on hemagglutination test (HA), and levels of serum immunoglobulins (IgA, IgG, IgM) while the cell-mediated immune response was evaluated by delayed-type hypersensitivity (DTH) response to ovalbumin, lymphocyte stimulation index, analyses of CD4⁺ and CD8⁺ T lymphocytes and mRNA expression levels of selected cytokines like IL-2, IFN-γ, IL-4 and IL-10 by quantitative Real-time PCR in experimental groups. T-2 treatment caused suppression in both humoral and cell-mediated immune responses as evidenced by a decrease in all these parameters in toxin fed animals compared to the control in the dose and duration-dependent manner. This dose-dependent effect on the immune system has been further reflected largely by the depletion of lymphocytes from lymphoid organs as observed histopathologically in the spleen, thymus, and Peyer's patches in the present study.

An update on T-2 toxin and its modified forms: metabolism, immunotoxicity mechanism, and human exposure assessment

T-2 toxin is the most toxic trichothecene mycotoxin, and it exerts potent toxic effects, including immunotoxicity, neurotoxicity, and reproductive toxicity. Recently, several novel metabolites, including 3',4'-dihydroxy-T-2 toxin and 4',4'-dihydroxy-T-2 toxin, have been uncovered. The enzymes CYP3A4 and carboxylesterase contribute to T-2 toxin metabolism, with 3'-hydroxy-T-2 toxin and HT-2 toxin as the corresponding primary products. Modified forms of T-2 toxin, including T-2-3-glucoside, exert their immunotoxic effects by signaling through JAK/STAT but not MAPK. T-2-3-glucoside results from hydrolyzation of the corresponding parent mycotoxin and other metabolites by the intestinal microbiota, which leads to enhanced toxicity. Increasing evidence has shown that autophagy, hypoxia-inducible factors, and exosomes are involved in T-2 toxin-induced immunotoxicity. Autophagy promotes the immunosuppression induced by T-2 toxin, and a complex crosstalk between apoptosis and autophagy exists. Very recently, "immune evasion" activity was reported to be associated with this toxin; this activity is initiated inside cells and allows pathogens to escape the host immune response. Moreover, T-2 toxin has the potential to trigger hypoxia in cells, which is related to activation of hypoxia-inducible factor and the release of exosomes, leading to immunotoxicity. Based on the data from a series of human exposure studies, free T-2 toxin, HT-2 toxin, and HT-2-4-glucuronide should be considered human T-2 toxin biomarkers in the urine. The present review focuses on novel findings related to the metabolism, immunotoxicity, and human exposure assessment of T-2 toxin and its modified forms. In particular, the immunotoxicity mechanisms of T-2 toxin and the toxicity mechanism of its modified form, as well as human T-2 toxin biomarkers, are discussed. This work will contribute to an improved understanding of the immunotoxicity mechanism of T-2 toxin and its modified forms.

Betulinic Acid Attenuates Oxidative Stress in the Thymus Induced by Acute Exposure to T-2 Toxin via Regulation of the MAPK/Nrf2 Signaling Pathway

T-2 toxin, the most toxic of the trichothecenes, is widely found in grains and feeds, and its intake poses serious risks to the health of humans and animals. An important cytotoxicity mechanism of T-2 toxin is the production of excess free radicals, which in turn leads to oxidative stress. Betulinic acid (BA) has many biological activities, including antioxidant activity, which is a plant-derived pentacyclic triterpenoid. The protective effects and mechanisms of BA in blocking oxidative stress caused by acute exposure to T-2 toxin in the thymus of mice was studied. BA pretreatment reduced ROS production, decreased the MDA content, and increased the content of IgG in serum and the levels of SOD and GSH in the thymus. BA pretreatment also reduced the degree of congestion observed in histopathological tissue sections of the thymus induced by T-2 toxin. Besides, BA downregulated the phosphorylation of the p38, JNK, and ERK proteins, while it upregulated the expression of the Nrf2 and HO-1 proteins in thymus tissues. The results indicated that BA could protect the thymus against the oxidative damage challenged by T-2 toxin by activating Nrf2 and suppressing the MAPK signaling pathway.

Research Progress on the Toxic Antagonism of Selenium Against Mycotoxins

Animal feed is prone to becoming infected with molds during production and storage, resulting in secondary metabolite mycotoxins, such as aflatoxin B₁ (AFB₁), T-2 toxins, deoxynivalenol (DON), and ochratoxin A (OTA), which are harmful to humans and animals. Selenium is an essential trace element for humans and animals, and it is also an effective antioxidant. Many studies have shown that selenium can reduce the damage caused by mycotoxins in animals. This article reviews the current literature on the antagonistic effects of selenium on AFB₁, T-2, DON, and OTA toxicity.

Immune Evasion, a Potential Mechanism of Trichothecenes: New Insights into Negative Immune Regulations

Days ago, the Nobel Prize in Physiology or Medicine 2018 was awarded jointly to James P. Allison and Tasuku Honjo “for their discovery of cancer therapy by inhibition of negative immune regulation”. This news has increased the attention on immunotoxicity and immune evasion mechanisms, which are once again hot research topics. Actually, increasing lines of evidence show that trichothecene mycotoxins have a strong immunosuppressive effect. These mycotoxins suppress the host immunity and make them more sensitive to the infection of pathogens, including bacteria and viruses. However, the underlying mechanism(s) in this context is still poorly understood. Interestingly, recent work showed that an immune evasion mechanism might be involved in trichothecene immunotoxicity. In this work, we discuss the potential immune evasion mechanism in trichothecene immunotoxicity. More importantly, under these circumstances, we are pleased to compile a Special Issue entitled “Biochemistry, Molecular Biology, and Toxicology of Natural and Synthetic Toxins” for the International Journal of Molecular Sciences (IJMS). Researchers are encouraged to share their latest interesting findings with the readers of IJMS.

The critical role of p16/Rb pathway in the inhibition of GH3 cell cycle induced by T-2 toxin

T-2 toxin is a worldwide trichothecenetoxin and can cause various toxicities.T-2 toxin is involved in G1 phase arrest in several cell lines but molecular mechanism is still not clear. In present study, we used rat pituitary GH3 cells to investigate the mechanism involved in cell cycle arrest against T-2 toxin (40 nM) for 12, 24, 36 and 48 h as compared to control cells. GH3 cells showed a considerable increase in reactive oxygen species (ROS) as well as loss in mitochondrial membrane potential (△Ym) upon exposure to the T-2 toxin. Flow cytometry showed a significant time-dependent increase in percentage of apoptotic cells and gel electrophoresis showed the hallmark of apoptosis oligonucleosomal DNA fragmentation. Additionally, T-2 toxin-induced oxidative stress and DNA damage with a time-dependent significant increased expression of p53 favors the apoptotic process by the activation of caspase-3 in T-2 toxin treated cells. Cell cycle analysis by flow cytometry revealed a time-dependent increase ofG1 cell population along with the significant time-dependent up-regulation of mRNA and protein expression of p16 and p21 and significant down-regulation of cyclin D1, CDK4, and p-RB levels further verify the G1 phase arrest in GH3 cells. Morphology of GH3 cells by TEM clearly showed the damage and dysfunction to mitochondria and the cell nucleus. These findings for the first time demonstrate that T-2 toxin induces G1 phase cell cycle arrest by the involvement of p16/Rb pathway, along with ROS mediated oxidative stress and DNA damage with p53 and caspase cascade interaction, resulting in apoptosis in GH3 cells.

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.

The Influence of Low Doses of Zearalenone and T-2 Toxin on Calcitonin Gene Related Peptide-Like Immunoreactive (CGRP-LI) Neurons in the ENS of the Porcine Descending Colon

The enteric nervous system (ENS) can undergo adaptive and reparative changes in response to physiological and pathological stimuli. These manifest primarily as alterations in the levels of active substances expressed by the enteric neuron. While it is known that mycotoxins can affect the function of the central and peripheral nervous systems, knowledge about their influence on the ENS is limited. Therefore, the aim of the present study was to investigate the influence of low doses of zearalenone (ZEN) and T-2 toxin on calcitonin gene related peptide-like immunoreactive (CGRP-LI) neurons in the ENS of the porcine descending colon using a double immunofluorescence technique. Both mycotoxins led to an increase in the percentage of CGRP-LI neurons in all types of enteric plexuses and changed the degree of co-localization of CGRP with other neuronal active substances, such as substance P, galanin, nitric oxide synthase, and cocaine- and amphetamine-regulated transcript peptide. The obtained results demonstrate that even low doses of ZEN and T-2 can affect living organisms and cause changes in the neurochemical profile of enteric neurons.

Effects of Mycotoxins on mucosal microbial infection and related pathogenesis

Mycotoxins are fungal secondary metabolites detected in many agricultural commodities and water-damaged indoor environments. Susceptibility to mucosal infectious diseases is closely associated with immune dysfunction caused by mycotoxin exposure in humans and other animals. Many mycotoxins suppress immune function by decreasing the proliferation of activated lymphocytes, impairing phagocytic function of macrophages, and suppressing cytokine production, but some induce hypersensitive responses in different dose regimes. The present review describes various mycotoxin responses to infectious pathogens that trigger mucosa-associated diseases in the gastrointestinal and respiratory tracts of humans and other animals. In particular, it focuses on the effects of mycotoxin exposure on invasion, pathogen clearance, the production of cytokines and immunoglobulins, and the prognostic implications of interactions between infectious pathogens and mycotoxin exposure.

The impact of Fusarium mycotoxins on human and animal host susceptibility to infectious diseases

Contamination of food and feed with mycotoxins is a worldwide problem. At present, acute mycotoxicosis caused by high doses is rare in humans and animals. Ingestion of low to moderate amounts of Fusarium mycotoxins is common and generally does not result in obvious intoxication. However, these low amounts may impair intestinal health, immune function and/or pathogen fitness, resulting in altered host pathogen interactions and thus a different outcome of infection. This review summarizes the current state of knowledge about the impact of Fusarium mycotoxin exposure on human and animal host susceptibility to infectious diseases. On the one hand, exposure to deoxynivalenol and other Fusarium mycotoxins generally exacerbates infections with parasites, bacteria and viruses across a wide range of animal host species. Well-known examples include coccidiosis in poultry, salmonellosis in pigs and mice, colibacillosis in pigs, necrotic enteritis in poultry, enteric septicemia of catfish, swine respiratory disease, aspergillosis in poultry and rabbits, reovirus infection in mice and Porcine Reproductive and Respiratory Syndrome Virus infection in pigs. However, on the other hand, T-2 toxin has been shown to markedly decrease the colonization capacity of Salmonella in the pig intestine. Although the impact of the exposure of humans to Fusarium toxins on infectious diseases is less well known, extrapolation from animal models suggests possible exacerbation of, for instance, colibacillosis and salmonellosis in humans, as well.

Influence of T-2 and HT-2 toxin on the blood-brain barrier in vitro: new experimental hints for neurotoxic effects

The trichothecene mycotoxin T-2 toxin is a common contaminant of food and feed and is also present in processed cereal derived products. Cytotoxic effects of T-2 toxin and its main metabolite HT-2 toxin are already well described with apoptosis being a major mechanism of action. However, effects on the central nervous system were until now only reported rarely. In this study we investigated the effects of T-2 and HT-2 toxin on the blood-brain barrier (BBB) in vitro. Besides strong cytotoxic effects on the BBB as determined by the CCK-8 assay, impairment of the barrier function starting at low nanomolar concentrations were observed for T-2 toxin. HT-2 toxin, however, caused barrier disruption at higher concentrations compared to T-2 toxin. Further, the influence on the tight junction protein occludin was studied and permeability of both toxins across the BBB was detected when applied from the apical (blood) or the basolateral (brain) side respectively. These results clearly indicate the ability of both toxins to enter the brain via the BBB.

Modulation of intestinal functions following mycotoxin ingestion: meta-analysis of published experiments in animals

Mycotoxins are secondary metabolites of fungi that can cause serious health problems in animals, and may result in severe economic losses. Deleterious effects of these feed contaminants in animals are well documented, ranging from growth impairment, decreased resistance to pathogens, hepato- and nephrotoxicity to death. By contrast, data with regard to their impact on intestinal functions are more limited. However, intestinal cells are the first cells to be exposed to mycotoxins, and often at higher concentrations than other tissues. In addition, mycotoxins specifically target high protein turnover- and activated-cells, which are predominant in gut epithelium. Therefore, intestinal investigations have gained significant interest over the last decade, and some publications have demonstrated that mycotoxins are able to compromise several key functions of the gastrointestinal tract, including decreased surface area available for nutrient absorption, modulation of nutrient transporters, or loss of barrier function. In addition some mycotoxins facilitate persistence of intestinal pathogens and potentiate intestinal inflammation. By contrast, the effect of these fungal metabolites on the intestinal microbiota is largely unknown. This review focuses on mycotoxins which are of concern in terms of occurrence and toxicity, namely: aflatoxins, ochratoxin A and Fusarium toxins. Results from nearly 100 published experiments (in vitro, ex vivo and in vivo) were analyzed with a special attention to the doses used.

Transport of Aflatoxin M(1) in Human Intestinal Caco-2/TC7 Cells

Aflatoxin M(1) (AFM(1)) is a hydroxylated metabolite of aflatoxin B(1) (AFB(1)). After it is formed, it is secreted in the milk of mammals. Despite the potential risk of human exposure to AFM(1), data reported in literature on the metabolism, toxicity, and bioavailability of this molecule are limited and out of date. The aim of the present research was to study the absorption profile of AFM(1) and possible damage to tight junctions (TJ) of the intestinal Caco-2/TC7 clone grown on microporous filter supports. These inserts allowed for the separation of the apical and basolateral compartments which correspond to the in vivo lumen and the interstitial space/vascular systems of intestinal mucosa respectively. In this study, the Caco-2/TC7 cells were treated with different AFM(1) concentrations (10-10,000 ng/kg) for short (40 min) and long periods of time (48 h). The AFM(1) influx/efflux transport and effects on TJ were evaluated by measuring trans-epithelial electrical resistance and observing TJ protein (Zonula occludens-1 and occludin) localization. The results showed that: (i) when introduced to the apical and basolateral compartments, AFM(1) was poorly absorbed by the Caco-2/TC7 cells but its transport across the cell monolayer occurred very quickly (P(app) value of 105.10 ± 7.98 cm/s × 10(-6)). (ii) The integrity of TJ was not permanently compromised after exposure to the mycotoxin. Viability impairment or barrier damage did not occur either. The present results contribute to the evaluation of human risk exposure to AFM(1), although the AFM(1) transport mechanism need to be clarified.

Evaluation of protective efficacy of CC-2 formulation against topical lethal dose of T-2 toxin in mice

T-2 toxin is the type-A trichothecene and a common contaminant of food and cereals, produced by Fusarium species. T-2 toxin easily penetrates skin due to its lipophilic nature and causes skin irritation and blisters in humans. Physical protection of the skin and airway is the only proven effective method of protection. To date, no chemical antidotes are available to prevent T-2 induced lethality. In the present study, we evaluated the protective efficacy of 20% N,N'-dichloro-bis(2,4,6-trichlorophenyl) urea (CC-2) formulation against lethal topical exposure dose of T-2 toxin in mice. None of the animals exposed to only T-2 toxin at lethal dose of 2 and 4 LD50 (11.8 and 23.76 mg/kg body weight) survived beyond 36 and 16 h, respectively. CC-2 application at 5 and 15 min post-exposure protected mice 100% from lethality at 2 LD50. Survival rate was 100% and 50% at 4LD50 dose if CC-2 was applied dermally within 5 and 15 min post-exposure. Recovery profile of surviving animals after 2LD50 T-2 toxin exposure at 1, 3, 7, and 14 days was assessed in terms of hepatic GSH, lipid peroxidation, serum ALP, ALT and AST. Hepatic lipid peroxidation significantly increased in all groups exposed to T-2 toxin by 3 day but normalized by day 7. A delayed GSH depletion was noted in surviving animals on day 7 but recovered by day 14. ALT and AST levels were elevated in all CC-2 protected mice on day 1 and normalized by day 3. ALP level decreased till day 7 in all protected groups. The biochemical variables recovered to control values by 14th day. GC-MS analysis after in vitro interaction of CC-2 formulation with T-2 toxin had shown that nearly 86% of T-2 toxin is decontaminated in 5 min but 8-10% of T-2 toxin was still present even after 60 min of interaction. Results of our study suggest that CC-2 may be an effective dermal decontaminant against lethal topical exposure of T-2 toxin.

Molecular mechanism of interleukin-2-induced mucosal homeostasis

Sustained damage to the mucosal lining in patients with inflammatory bowel disease (IBD) facilitates translocation of intestinal microbes to submucosal immune cells leading to chronic inflammation. Previously, we demonstrated the role of Jak3 in IL-2-induced intestinal epithelial cell (IEC) migration, one of the early events during intestinal wound repair. In this study, we demonstrate that IL-2 also plays a role in IEC homeostasis through concentration-dependent regulation of IEC proliferation and cell death. At lower concentrations (≤50 U/ml), IL-2 promoted proliferation, while at higher concentrations (100 U/ml), it promoted apoptosis. Activation by IL-2 led to tyrosine phosphorylation-dependent interactions between Jak3 and p52ShcA only at lower concentrations. Phosphatase SHP1 dephosphorylated IL-2-induced phosphorylated p52ShcA. Higher concentrations of IL-2 decreased the phosphorylation of Jak3 and p52ShcA, disrupted their interactions, redistributed Jak3 to the nucleus, and induced apoptosis in IEC. IL-2 also induced dose-dependent upregulation of p52shcA and downregulation of jak3-mRNA. Constitutive overexpression and mir-shRNA-mediated knockdown studies showed that expression of both Jak3 and p52ShcA were necessary for IL-2-induced proliferation of IEC. Doxycycline-regulated sh-RNA expression demonstrated that IL-2-induced downregulation of jak3-mRNA was responsible for higher IL-2-induced apoptosis in IEC. Collectively, these data demonstrate a novel mechanism of IL-2-induced mucosal homeostasis through posttranslational and transcriptional regulation of Jak3 and p52ShcA.

Alteration of blood brain barrier permeability by T-2 toxin: Role of MMP-9 and inflammatory cytokines

T-2 toxin is a cytotoxic fungal secondary metabolite produced by different species of Fusarium such as F. sporotichioides, F. poae, F. equiseti, F. acuminatum etc. This class of mycotoxins causes a number of pathologies including nervous disorders, cardiovascular alterations, immunodepression and hemostatic derangements. In the present study, mechanism of T-2 toxin induced alteration of blood-brain barrier (BBB) permeability was assessed in terms of oxidative stress, gene expression of MMP-9, MMP-2 and their inhibitors TIMP-1 and TIMP-2, activation of inflammatory cytokines in both brain and peripheral tissue spleen. Gel zymography was used to show the activity of MMP-9 and MMP-2. The percutaneous exposure of 1 LD50 T2 toxin caused a reversible alteration in BBB permeability as observed by extravasation of Evans blue dye. Maximum dye level was observed on day 3 and reduced by day 7. A significant GSH depletion was observed on days 1 and 3. Brain ROS and lipid peroxidation levels increased significantly on 1 and 3 days and decreased by day 7. The SOD levels in brain showed significantly higher activity on 3 days (4-fold) and 7 days (5-fold) of toxin exposure compared to control. A similar trend was observed with catalase enzyme levels. The gene expression analysis of cNOS and iNOS showed varying levels of expression on different time points of post exposure. MMP-9 expression was significantly high on days 3 and 7 in brain with corresponding alteration in TIMP-1. MMP-2 and TIMP-2 showed no effect. Gene expression analysis of the inflammatory cytokines, IL-1α, IL-1β, IL-6 and TNF-α showed elevated levels on day 7 in brain. As spleen plays an important role in inflammatory response we analyzed MMP-9, MMP-2 and inflammatory cytokines in spleen. The MMP-9 was activated on day 7. MMP-2 activity was found to be elevated on 3 and 7 days and TIMP-2 mRNA level increased on 1 and 3 days in spleen. Inflammatory cytokines, IL-1 α, IL-1β, IL-6 and TNF-α showed elevated levels on days 1 and 3 in spleen indicating an early effect in spleen than in brain. In summary, the results of the study showed that the T-2 induced alteration in BBB permeability is mediated through oxidative stress, activation of MMP-9, and proinflammatory cytokines in brain as well as contribution from peripheral tissue spleen.

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.

Transcriptomic-based bioassays for the detection of type A trichothecenes

The type A trichothecenes T-2 toxin (T-2) and HT-2 toxin (HT-2) are hazardous Fusarium products that contaminate many field crops growing in cold to temperate regions across the world. Toxicity studies in laboratory and farm animals have been used to derive a temporary tolerable daily intake (t-TDI) for the sum of T-2 and HT-2 of no more than 60 ng/kg body weight. To protect the consumers, it is now necessary to screen a large number of food samples for the presence of these poisonous fungal metabolites. Towards that goal, we discovered that the transcriptional apparatus of a human carcinoma cell line (MCF7) provides a sensitive biological sensor of type A trichothecenes. In fact, exposure of this easy-to-culture cell line to T-2 or HT-2 results in the regulation of >2,000 different transcripts with expression changes ranging from >5,000-fold gene inductions to >40-fold gene repressions. These transcriptional responses have been exploited to develop practical microchip and reverse transcription-polymerase chain reaction (RT-PCR) assays for the detection of type A trichothecenes at parts per billion levels.

Dietary glucomannan improves the vaccinal response in pigs exposed to aflatoxin B1 or T-2 toxin

The aim of the study was to investigate whether dietary supplementation with yeast-derived glucomannan protects pigs against the deleterious effects that exposure to aflatoxin B1 (AFB1) or T-2 toxin has on the vaccinal immune response and drug-metabolising enzymes. Three doses of pure mycotoxin (AFB1 trial: 482, 968 and 1,912 µg/kg feed; T-2 toxin trial: 593, 1,155 and 2,067 µg/kg feed) with or without dietary glucomannan supplementation (2 g/ kg feed) were tested in weaned pigs for 28 days. At days 4 and 15 pigs were immunised with ovalbumin to study the humoral and cell-mediated antigen-specific immune responses. The effects of AFB1 and T-2 toxin intake alone in pigs have already been published. In all parameters investigated no differences were apparent between animals receiving the unsupplemented control diet or the control diet containing glucomannan. In the AFB1 trial glucomannan decreased the severity of liver lesions in animals exposed to 968 µg/kg feed. Exposure to both AFB1 and T-2 toxin were associated with impaired phase I liver enzyme activities, but glucomannan demonstrated a limited protective effect on these enzymes. With regard to the immune defence system, both toxins modulated the vaccinal immune response; AFB1 impaired specific cellular response and T-2 toxin the specific humoral response. Glucomannan supplementation restored the ovalbumin-specific lymphocyte proliferation that was delayed in pigs exposed to AFB1, regardless of dose. In the T-2 toxin trial glucomannan supplementation restored anti-ovalbumin immunoglobulin G production, which was significantly reduced in pigs exposed to both medium and high doses of the toxin. In conclusion, glucomannan dietary supplementation demonstrated no deleterious effects in control animals and protective effects against AFB1 and T-2 toxin immunotoxicity during a vaccinal protocol.

Immunomodulatory effects of feed-borne Fusarium mycotoxins in chickens infected with coccidia

The potential for Fusarium mycotoxins to modulate immunity was studied in chickens raised to 10 weeks of age using an enteric coccidial infection model. Experimental diets included: control, diets containing grains naturally contaminated with Fusarium mycotoxins, and diets containing contaminated grains + 0.2% polymeric glucomannan mycotoxin adsorbent (GMA). Contaminated diets contained up to 3.8 microg/g deoxynivalenol (DON), 0.3 microg/g 15-acetyl DON and 0.2 microg/g zearalenone. An optimized mixture (inducing lesions without mortality) of Eimeria acervulina, E. maxima and E. tenella was used to challenge birds at 8 weeks of age. Immune parameters were studied prior to challenge, at the end of the challenge period (7 days post-inoculation, PI), and at the end of the recovery period (14 days PI). Total serum immunoglobulin (Ig) A and IgG concentrations in challenged birds fed the contaminated diet were higher than controls at the end of the challenge period. Serum concentration of IgA, but not IgG, was significantly decreased at the end of the recovery period in birds fed the contaminated diet. The percentage of CD4+ and CD8+ cell populations in blood mononuclear cells decreased significantly at the end of the challenge period in birds fed the control or the contaminated diet compared to their percentages prior to challenge. The pre-challenge percentage of CD8+ population was restored at the end of the recovery period only in birds fed the control diet. Interferon-gamma (IFN-gamma) gene expression in caecal tonsils was up-regulated in challenged birds fed the contaminated diet at the end of the challenge period. No significant effect of diet was observed on oocyst counts despite the changes in the studied immune parameters. It was concluded that Fusarium mycotoxins modulate the avian immune system. This modulation involves alteration of gene expression but apparently does not enhance susceptibility or resistance to a primary coccidial challenge.

3,3'-Diindolylmethane stimulates murine immune function in vitro and in vivo

3,3'-Diindolylmethane (DIM), a major condensation product of indole-3-carbinol, exhibits chemopreventive properties in animal models of cancer. Recent studies have shown that DIM stimulates interferon-gamma (IFN-gamma) production and potentiates the IFN-gamma signaling pathway in human breast cancer cells via a mechanism that includes increased expression of the IFN-gamma receptor. The goal of this study was to test the hypothesis that DIM modulates the murine immune function. Specifically, the effects of DIM were evaluated in a panel of murine immune function tests that included splenocyte proliferation, reactive oxygen species (ROS) generation, cytokine production and resistance to viral infection. DIM was found to induce proliferation of splenocytes as well as augment mitogen- and interleukin (IL)-2-induced splenocyte proliferation. DIM also stimulated the production of ROS by murine peritoneal macrophage cultures. Oral administration of DIM, but not intraperitoneal injection, induced elevation of serum cytokines in mice, including IL-6, granulocyte colony-stimulating factor (G-CSF), IL-12 and IFN-gamma. Finally, in a model of enteric virus infection, oral DIM administration to mice enhanced both clearance of reovirus from the GI tract and the subsequent mucosal IgA response. Thus, DIM is a potent stimulator of immune function. This property might contribute to the cancer inhibitory effects of this indole.

Docosahexaenoic acid-enriched fish oil consumption modulates immunoglobulin responses to and clearance of enteric reovirus infection in mice

We hypothesized that consumption of the (n-3) PUFA, docosahexaenoic acid (DHA), modulates the mucosal immune response to enteric infection with respiratory enteric orphan virus (reovirus), a model intestinal pathogen. Mice were fed either AIN-93G control diet, containing 10 g/kg corn oil and 60 g/kg high oleic acid safflower oil, or AIN-93G, containing 10 g/kg corn oil and 60 g/kg DHA-enriched fish oil, for 4 wk and then orally gavaged with reovirus strain Type 1 Lang, (T1/L). Reovirus-specific IgA antibody was first detectable in the feces of mice fed a control diet at 6 d postinfection (PI) and was further elevated at 8 and 10 d PI. IgA responses in DHA-fed mice were similar at 6 and 8 d PI but greater at 10 d PI (P < 0.05). Both reovirus-specific serum IgA and IgG(2a) were comparably induced in mice fed control or DHA diets. Reovirus-specific IgA and IgG(2a) secretion by ex vivo Peyer's patch, lamina propria, and spleen cultures derived from control and DHA groups were comparable. Although both groups carried similar numbers of reovirus plaque forming units per intestine, DHA-fed mice shed nearly 10 times more viral RNA in feces than control mice at 2, 4, and 6 d PI (P < 0.05). However, viral RNA was not detectable in either group at 8 and 10 d. Taken together, these data suggest that DHA consumption did not markedly alter mucosal or systemic Ig responses to reovirus but delayed clearance of the virus from the intestinal tract.