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

Caspase-dependent signaling underlies glioblastoma cell death in response to the fungal metabolite, fusarochromanone

Fungal metabolites continue to show promise as a viable class of anticancer agents. In the present study, we investigated the efficacy of the fungal metabolite, fusarochromanone (FC101), for its antitumor activities in glioblastomas, which have a median survival of less than two years and a poor clinical response to surgical resection, radiation therapy and chemotherapy. Using clinically applicable doses, we demonstrated that FC101 induced glioblastoma apoptotic cell death via caspase dependent signaling, as indicated by the cleavage of poly(ADP-ribose) polymerase, glioblastoma (PARP). FC101 also induced differential reactive oxygen species (ROS) levels in glioblastoma cells, contrasting a defined role of oxidative stress in apoptotic cell death observed with other fungal metabolites. Furthermore, the antitumorigenic effects of FC101 on tumor cell migration were assessed. Cell migration assays revealed that FC101 significantly reduced the migratory capacity of glioblastomas, which are incredibly invasive tumors. Taken together, the present study establishes FC101 as a candidate anticancer agent for the cooperative treatment of glioblastomas.

Oxidative stress-mediated cytotoxicity and metabolism of T-2 toxin and deoxynivalenol in animals and humans: an update

Trichothecenes are a large family of structurally related toxins mainly produced by Fusarium genus. Among the trichothecenes, T-2 toxin and deoxynivalenol (DON) cause the most concern due to their wide distribution and highly toxic nature. Trichothecenes are known for their inhibitory effect on eukaryotic protein synthesis, and oxidative stress is one of their most important underlying toxic mechanisms. They are able to generate free radicals, including reactive oxygen species, which induce lipid peroxidation leading to changes in membrane integrity, cellular redox signaling, and in the antioxidant status of the cells. The mitogen-activated protein kinases signaling pathway is induced by oxidative stress, which also induces caspase-mediated cellular apoptosis pathways. Several new metabolites and novel metabolic pathways of T-2 toxin have been discovered very recently. In human cell lines, HT-2 and neosolaniol (NEO) are the major metabolites of T-2 toxin. Hydroxylation on C-7 and C-9 are two novel metabolic pathways of T-2 toxin in rats. The metabolizing enzymes CYP3A22, CYP3A29, and CYP3A46 in pigs, as well as the enzymes CYP1A5 and CYP3A37 in chickens, are able to catalyze T-2 toxin and HT-2 toxin to form the C-3'-OH metabolites. Similarly to carboxylesterase, CYP3A29 possesses the hydrolytic ability in pigs to convert T-2 toxin to NEO. T-2 toxin is able to down- or upregulate cytochrome P-450 enzymes in different species. The metabolism of DON in humans is region-dependent. Free DON and DON-glucuronide are considered to be the biomarkers for humans. The masked mycotoxin DON-3-β-D-glucoside can be hydrolyzed to free DON in the body. This review will provide useful information on the progress of oxidative stress as well as on the metabolism and the metabolizing enzymes of T-2 toxin and DON. Moreover, the literature will throw light on the blind spots of metabolism and toxicological studies in trichothecenes that have to be explored in the future.

Modification of energy balance induced by the food contaminant T-2 toxin: a multimodal gut-to-brain connection

T-2 toxin is one of the most toxic Fusarium-derived trichothecenes found on cereals and constitutes a widespread contaminant of agricultural commodities as well as commercial foods. Low doses toxicity is characterized by reduced weight gain. To date, the mechanisms by which this mycotoxin profoundly modifies feeding behavior remain poorly understood and more broadly the effects of T-2 toxin on the central nervous system (CNS) have received limited attention. Through an extensive characterization of sickness-like behavior induced by T-2 toxin, we showed that its per os (p.o.) administration affects not only feeding behavior but also energy expenditure, glycaemia, body temperature and locomotor activity. Using c-Fos expression mapping, we identified the neuronal structures activated in response to T-2 toxin and observed that the pattern of neuronal populations activated by this toxin resembled that induced by inflammatory signals. Interestingly, part of neuronal pathways activated by the toxin were NUCB-2/nesfatin-1 expressing neurons. Unexpectedly, while T-2 toxin induced a strong peripheral inflammation, the brain exhibited limited inflammatory response at a time point when anorexia was ongoing. Unilateral vagotomy partly reduced T-2 toxin-induced brainstem neuronal activation. On the other hand, intracerebroventricular (icv) T-2 toxin injection resulted in a rapid (<1h) reduction in food intake. Thus, we hypothesized that T-2 toxin could signal to the brain through neuronal and/or humoral pathways. The present work provides the first demonstration that T-2 toxin modifies feeding behavior by interfering with central neuronal networks devoted to central energy balance. Our results, with a particular attention to peripheral inflammation, strongly suggest that inflammatory mediators partake in the T-2 toxin-induced anorexia and other symptoms. In view of the broad human and breeding animal exposure to T-2 toxin, this new mechanism may lead to reconsider the impact of the consumption of this toxin on human health.

Zearalenone induced toxicity in SHSY-5Y cells: The role of oxidative stress evidenced by N-acetyl cysteine

Zearalenone (ZEN) is a mycotoxin from Fusarium species commonly found in many food commodities and are known to cause reproductive disorders, genotoxic and immunosuppressive effects. Although many studies have demonstrated the cytotoxic effects of ZEN, the mechanisms by which ZEN mediates its cytotoxic effects appear to differ according to cell type and route of exposure. Meantime, the available information on the neurotoxic effects of ZEN is very much limited. In the present study we evaluated the role of oxidative stress in ZEN mediated neurotoxicity in SH-SY5Y cells and investigated the possible underlying mechanism. ZEN induced ROS formation and elevated levels of MDA, loss of mitochondrial membrane potential (MMP) and increase in DNA damage in a dose dependent manner as assessed by COMET assay and agarose gel electrophoresis. However, there was no DNA damage by plasmid breakage assay at 6, 12 and 24h time points. DAPI staining showed apoptotic nuclei at 12 and 24h. Further, ZEN treated SH-SY5Y cells showed a marked suppressive effect on the neuronal gene expression. Use of an antioxidant N-acetylcysteine (NAC) reversed the toxin-induced generation of ROS and also attenuated loss of MMP. Collectively, these results suggest that ROS is the main upstream signal leading to increased ZEN mediated neurotoxicity in SH-SY5Y cells.

Study on the apoptosis mechanism induced by T-2 toxin

T-2 toxin is known to induce apoptosis in mammalian cells. The mechanism of apoptosis induced by T-2 toxin has been proposed to be linked with oxidative stress and mitochondrial pathway. In the current study, the toxic effect of T-2 on Hela, Bel-7402, and Chang liver cells was examined in dose-dependent and time-dependent manner by MTT assay. Caspase-3 was found to be up-regulated under T-2 toxin stress, which suggested that T-2 toxin induced cell apoptosis. Endogenous GSH and MDA levels in all three cell lines were found down- and up-regulated respectively, which indicated the link between toxic effect of T-2 toxin and intracellular oxidative stress. It was also found by MTT assay that NAC, which maintained the level of GSH in cells, could protect cells from death. Western-blot result showed that the level of both activated Caspase-8 and Caspase-9 increased when cells were treated by T-2 toxin. Caspase-9 was found to be activated earlier than Caspase-8. It was also found that p53 was up-regulated under T-2 toxin stress in the study. These results implied that the effect of T-2 toxin on cells was apoptosis rather than necrosis, and it was probably induced through mitochondrial pathway. To the best of our knowledge, the present study is the first to show that JunD is down-regulated in T-2 toxin induced apoptosis. By construction of an over-expression vector for the JunD gene, we observed that the survival ratio of JunD over-expressed cells obviously increased under T-2 toxin stress. These results suggested that the mechanism of T-2 induced cell death was closely connected with oxidative stress, and that JunD plays an important role in the defensive process against T-2 toxin stress.

Dose-related genotoxic effect of T-2 toxin measured by comet assay using peripheral blood mononuclear cells of healthy pigs

T-2 toxin is the most acutely toxic trichothecene mycotoxin: it inhibits protein, DNA and RNA synthesis. The main goal of this study was to evaluate the rate of DNA damage caused by T-2 toxin in porcine mononuclear cells in increasing concentrations (0.1, 0.5 and 1.0 μmol) and after two different incubation periods (24 and 42 h). The lowest concentration caused DNA damage and about 50% of the treated cells could be categorised as having 1 to 4 scores in comet assay. In parallel with the increase of T-2 toxin concentration, the frequency of intact lymphocytes decreased from 50.2% (0.1 μM) to 36.3% (1.0 μM) in the first 24 h. In case of score 3, the highest concentration of T-2 toxin resulted in a 5-fold change, as compared to the lowest dose. Cells with score 4 were found only after exposure to 1.0 μM T-2 toxin. The exposure time did not have a significant effect on the results, while concentration did (P < 0.0001). However, a significant interaction between concentration and time as fixed factors (P < 0.0001) was found. When these were combined as a single factor, the results showed a significant toxin treatment effect on the results. It was concluded that a time- and dose-dependent DNA damaging effect of T-2 toxin could be demonstrated using peripheral blood mononuclear cells from healthy pigs by comet assay.

Detection of mycotoxins in patients with chronic fatigue syndrome

Over the past 20 years, exposure to mycotoxin producing mold has been recognized as a significant health risk. Scientific literature has demonstrated mycotoxins as possible causes of human disease in water-damaged buildings (WDB). This study was conducted to determine if selected mycotoxins could be identified in human urine from patients suffering from chronic fatigue syndrome (CFS). Patients (n = 112) with a prior diagnosis of CFS were evaluated for mold exposure and the presence of mycotoxins in their urine. Urine was tested for aflatoxins (AT), ochratoxin A (OTA) and macrocyclic trichothecenes (MT) using Enzyme Linked Immunosorbent Assays (ELISA). Urine specimens from 104 of 112 patients (93%) were positive for at least one mycotoxin (one in the equivocal range). Almost 30% of the cases had more than one mycotoxin present. OTA was the most prevalent mycotoxin detected (83%) with MT as the next most common (44%). Exposure histories indicated current and/or past exposure to WDB in over 90% of cases. Environmental testing was performed in the WDB from a subset of these patients. This testing revealed the presence of potentially mycotoxin producing mold species and mycotoxins in the environment of the WDB. Prior testing in a healthy control population with no history of exposure to a WDB or moldy environment (n = 55) by the same laboratory, utilizing the same methods, revealed no positive cases at the limits of detection.

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.

Assessment of genotoxic potential of two mycotoxins in the wing spot test of Drosophila melanogaster

Mycotoxins, the toxic products of molds, exposure causes serious adverse health problems in human, animals, and crops. Determining the potential genotoxic effects of these substances is, therefore, of great importance. We have evaluated the genotoxic toxicity of two trichothecenes – diacetoxyscirpenol (DAS) and T-2 toxin – using the wing somatic mutation and recombination test (SMART) in Drosophila melanogaster. The SMART is based on the principle that the loss of heterozygosis of recessive markers located on the left arm of chromosome 3 – multiple wing hairs ( mwh) at the map position 0.3 and flare-3 ( flr3) at the map position 38.8 – may occur through various mechanisms such as mitotic recombination, mutation, deletion, half-translocation, chromosome loss, and nondisjunction. Both the mycotoxins were administered to third instar larvae (72 ± 4 h old) at concentrations ranging from 5 to 40 μM. Based on our results, DAS and T-2 toxins does not exert genotoxic effects up to a concentration of 40 μM.

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.

Comprehensive gene expression analysis of type B trichothecenes

Type B trichothecenes, deoxynivalenol (DON) and nivalenol (NIV), are secondary metabolites of Fusarium species and are major pollutants in food and feed products. Recently, the production trend of their derivatives, 3-acetyldeoxynivalenol (3-AcDON), 15-acetyldeoxynivalenol (15-AcDON), and 4-acetylnivalenol (4-AcNIV or fusarenon-X), has been changing in various regions worldwide. Although in vivo behavior has been reported, it is necessary to acquire more detailed information about these derivatives. Here, the yeast PDR5 mutant was used for toxicity evaluation, and the growth test revealed that DON, 15-AcDON, and 4-AcNIV had higher toxicity compared to 3-AcDON and NIV. 15-AcDON exerted the most significant gene expression changes, and cellular localization clustering exhibited repression of mitochondrial ribosomal genes. This study suggests that the toxicity trends of both DON products (DON and its derivatives) and NIV products (NIV and its derivatives) are similar to those observed in mammalian cells, with a notable toxic response to 15-AcDON.

Reevaluation of arrhythmias and alterations of the autonomic nervous activity induced by T-2 toxin through telemetric measurements in unrestrained rats

This study was conducted to clarify and reevaluate the cardiac and autonomic nervous effects of T-2 toxin, which had been previously examined by several acute experiments, in unrestrained and conscious rats implanted with telemetric transmitters. Two groups of rats were given two subcutaneous injections of 0.1 and 0.5 mg/kg of T-2 toxin with an interval of 3 days. Two other groups of rat were pre-implanted with osmotic minipumps by which atropine (20 mg/kg/day) or propranolol (100 mg/kg/day) was continuously administered preceding subcutaneous injection of T-2 toxin (0.5 mg/kg). The present study demonstrated that T-2 toxin caused marked arrhythmias, such as second-degree atrioventricular (AV) block, sinus bradycardia, supraventricular extrasystole, and ventricular extrasystole, which were accompanied by a significant increase in heart rate and a significant decrease in total power and low- and high-frequency power of heart rate variability, during 3 days of observation after the toxin administration. However, the occurrence of arrhythmia with conduction disturbance such as second-degree atrioventricular blocks was markedly diminished by pretreatment with atropine, while the occurrence of ventricular extrasystole was augmented by atropine. The present study with the telemetric measurement elucidated and confirmed that T-2 toxin produced significant cardiac dysfunctions involving disturbance of the conduction pathway influenced by the autonomic nervous activity and also possible direct effects on cardiac myocytes.

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.

Trichothecene mycotoxins inhibit mitochondrial translation--implication for the mechanism of toxicity

Fusarium head blight (FHB) reduces crop yield and results in contamination of grains with trichothecene mycotoxins. We previously showed that mitochondria play a critical role in the toxicity of a type B trichothecene. Here, we investigated the direct effects of type A and type B trichothecenes on mitochondrial translation and membrane integrity in Saccharomyces cerevisiae. Sensitivity to trichothecenes increased when functional mitochondria were required for growth, and trichothecenes inhibited mitochondrial translation at concentrations, which did not inhibit total translation. In organello translation in isolated mitochondria was inhibited by type A and B trichothecenes, demonstrating that these toxins have a direct effect on mitochondrial translation. In intact yeast cells trichothecenes showed dose-dependent inhibition of mitochondrial membrane potential and reactive oxygen species, but only at doses higher than those affecting mitochondrial translation. These results demonstrate that inhibition of mitochondrial translation is a primary target of trichothecenes and is not secondary to the disruption of mitochondrial membranes.

Trichothecin induces apoptosis of HepG2 cells via caspase-9 mediated activation of the mitochondrial death pathway

Trichothecin, one of fungal toxins which were encountered in food and in the environment, seriously threatens human and animal health. It has been shown that trichothecin changed the morphology of cellular mitochondria. However, the molecular mechanism remains unknown. Here we found that cell viability was attenuated by trichothecin. Features of apoptosis such as homosomal condensation and inter nucleosomal fragmentation were observed. In consistence with the elevated apoptosis rate, expression of anti-apoptotic protein Bcl-2 was diminished and expression of proapoptotic protein Bax was enhanced at mRNA levels. Furthermore, expression of caspase-9 and activity of caspase-3 were increased after the treatment of trichothecin. Accordingly, the mitochondrial membrane potential (∆Ψm) was decreased in a dose-dependent manner. And Ca(2+) overload was induced by trichothecin, followed by the generation of reactive oxygen species (ROS). Collectedly, our results suggested that apoptosis induced by trichothecin is mediated by caspase-9 activation and the decrement of mitochondrial function resulted from the overloaded calcium and ROS production.

N-acetyl-cysteine protects chicken growth plate chondrocytes from T-2 toxin-induced oxidative stress

T-2 toxin is now considered to be related to bone malformation such as incomplete ossification, absence of bones and fused bones. In this study, primary cultures of chicken tibial growth plate chondrocytes (GPCs) were treated with various concentrations of T-2 toxin (5, 50, and 500 n m) in the absence and presence of N-acetyl-cysteine (NAC) to investigate the effects of the antioxidant NAC on T-2 toxin-induced toxicity. Our results showed that T-2 toxin markedly decreased cell viability, alkaline phosphatase activity and glutathione content (P < 0.05). In addition, T-2 toxin significantly increased reactive oxygen species levels and malondialdehyde in a dose-dependent manner. However, the T-2 toxin-induced cytotoxicity was reversed, in part, by the antioxidant NAC (P < 0.05). These results suggest that T-2 toxin inhibits the proliferation and differentiation of GPCs in vitro by altering cellular homeostasis and NAC can protect GPCs against T-2 toxin cytotoxicity by reducing the T-2 toxin-induced oxidative stress.

Integrated transcriptional and proteomic analysis with in vitro biochemical assay reveal the important role of CYP3A46 in T-2 toxin hydroxylation in porcine primary hepatocytes

Both T-2 toxin and its metabolites are highly potent mycotoxins that can cause severe human and animal diseases upon exposure. Understanding the toxic mechanism and biotransformation process of T-2 toxin at a cellular level is essential for the development of counter-measures. We investigated the effect of T-2 toxin in porcine primary hepatocytes using porcine genome array and two-dimensional difference gel electrophoresis with matrix-assisted laser desorption/ionization tandem time of flight mass spectrometry. Integrated transcriptional and proteomic analysis demonstrated that T-2 toxin adversely affected porcine hepatocytes by initiating lipid metabolism disorder, oxidative stress response, and apoptosis. In addition, xenobiotic metabolism genes, including cytochrome P450 3As (CYP3A46 and CYP3A39), carboxylesterase 1Cs (CES1C4 and CES1C5), and epoxide hydrolase (EPHX1), increased in T-2 toxin treatment cells. Using HepG2 cells to over-express the recombinant xenobiotic metabolism genes above and rapid resolution liquid chromatography/tandem mass spectrometry to detect metabolites of T-2 toxin, we determined that porcine CYP3A46 mainly catalyzed T-2 to form 3'-hydroxy-T-2, which was further confirmed by purified CYP3A46 protein. However, recombinant porcine CES1C5 and EPHX1 did not enhance hydrolysis and de-epoxidation of T-2 implying that other esterases and epoxide hydrolases may play dominant roles in those reactions.

Cigarette smoke condensate causes a decrease of the gene expression of Cu-Zn superoxide dismutase, Mn superoxide dismutase, glutathione peroxidase, catalase, and free radical-induced cell injury in SH-SY5Y human neuroblastoma cells

Cigarette smoking condensate (CSC) contains oxidant compounds able to generate superoxide. The aim of the present study was to investigate the effect of the exposure to CSC on: (1) free radical production, (2) the gene expression of the antioxidant enzymes Cu-Zn superoxide dismutase (SOD1), Mn superoxide dismutase (SOD2), Glutathione Peroxidase (GPx), and catalase (CAT), and (3) cell survival in human neuroblastoma SH-SY5Y cells. The results showed that exposure (24 h) to different concentrations (10-150 μg/ml) of CSC caused a dose dependent cell injury that was coupled to the maximal increase of free radical production. These events were prevented by the addition to the incubation medium of the scavenger Vitamin E (50 μM). Furthermore, CSC exposure caused a reduction of the gene expression of the antioxidant enzymes SOD1, SOD2, GPx, and CAT that was counteracted by Vitamin E (50 μM). These results suggest that CSC exposure can induce a free radical overcharge that may be responsible for the inhibition of antioxidant enzymes expression and cell injury in SH-SY5Y human neuroblastoma cells. In fact the scavenger vitamin E can block both cell injury and inhibition of SOD1, SOD2, GPx, and CAT induced by CSC exposure.

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.

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.

Probucol attenuates cyclophosphamide-induced oxidative apoptosis, p53 and Bax signal expression in rat cardiac tissues

Cyclophosphamide (CP) is a widely used in cancer chemotherapy and immunosuppression, which could cause toxicity of the normal cells due to its toxic metabolites. Probucol, cholesterol-lowering drug, acts as potential inhibitor of DNA damage and shows to protect against doxorubicin-induced cardiomyopathy by enhancing the endogenous antioxidant system including glutathione peroxidase, catalase and superoxide dismutase. This study examined the possible protective effects of probucol, a lipid-lowering compound with strong antioxidant properties, against CP-induced cardiotoxicity. This objective could be achieved through studying the gene expression-based on the possible protective effects of probucol against CP-induced cardiac failure in rats. Adult male Wistar albino rats were assigned into 4 treatment groups: Animals in the first (control) and second (probucol) groups were injected intraperitoneally with corn oil and probucol (61 mg/kg/day), respectively, for two weeks. Animals in the third (CP) and fourth (probucol plus CP) groups were injected with the same doses of corn oil and probucol (61 mg/kg/day), respectively, for one week before and one week after a single dose of CP (200 mg/kg, I.P.). The p53, Bax, Bcl2 and oxidative genes signal expression were measured by real time PCR. CP-induced cardiotoxicity was clearly observed by a significant increase in serum creatine phosphokinase isoenzyme (CK-MB) (117%), lactate dehydrogenase (LDH) (64%), free (69%) and esterified cholesterol (42%) and triglyceride (69%) compared to control group. In cardiac tissues, CP significantly increases the mRNA expression levels of apoptotic genes, p53 with 2 folds and Bax with 1.6 fold, and decreases the anti-apoptotic gene Bcl2 with 0.5 fold. Moreover, CP caused down-regulation of antioxidant genes, glutathione peroxidase, catalase, and superoxide dismutase and increased the lipid peroxidation and decreased adenosine triphosphate (ATP) (40%) and ATP/ADP (44%) in cardiac tissues. Probucol pretreatment not only counteracted significantly the CP-induced increase in cardiac enzymes and apoptosis but also it induced a significant increase in mRNA expression of antioxidant enzymes and improved ATP, ATP/ADP, glutathione (GSH) in cardiac tissues. In conclusion, data from the present study suggest that probucol prevents the development of CP-induced cardiotoxicity by a mechanism related, at least in part, to its ability to increase mRNA expression of antioxidant genes and to decrease apoptosis in cardiac tissues with the consequent improvement in mitochondrial oxidative phosphorylation and energy production.

Cell proliferation and cell cycle alterations in oesophageal p53-mutated cancer cells treated with cisplatin in combination with photodynamic therapy

OBJECTIVES

The major goal of anti-cancer therapies is selective destruction of tumour cells with minimum side effects on normal cells. Towards this aim, combination of different therapeutic modalities has been evaluated for improving control of neoplastic diseases and quality of life for the patient. Photodynamic therapy (PDT) is a procedure for treatment of various types of cancer, but its combination with other established treatments has not been evaluated in detail. We have used KYSE-510 cells from a human oesophageal carcinoma as an in vitro model to investigate whether cisplatin (CDDP) could be combined with PDT to increase cell death with respect to single treatments.

MATERIALS AND METHODS

p53-mutated KYSE-510 cells were treated with CDDP alone or in combination with PDT. Analyses of cell viability, cell cycle progression and apoptosis induction were carried out at specific times after treatments.

RESULTS

Decrease in cell viability, cell cycle arrest at the G(2)/M- and S-phases boundary, and apoptosis induction were observed after single and combined treatments.

CONCLUSIONS

Our results show that low CDDP doses (0.25-1 microm) induce cell mortality and cell cycle perturbation, which were more evident when given in combination with PDT, but in contrast to work of other authors no synergistic activity was found. Apoptosis occurred via intrinsic pathways in treated cells, although it did not represent the predominant mode of cell death.

DNA damage and DNA damage responses in THP-1 monocytes after exposure to spores of either Stachybotrys chartarum or Aspergillus versicolor or to T-2 toxin

We have characterized cell death in THP-1 cells after exposure to heat-treated spores from satratoxin G-producing Stachybotrys chartarum isolate IBT 9631, atranone-producing S. chartarum isolate IBT 9634, and sterigmatocystin-producing Aspergillus versicolor isolate IBT 3781, as well as the trichothecenes T-2 and satratoxin G. Spores induced cell death within 3-6 h, with Stachybotrys appearing most potent. IBT 9631 induced both apoptosis and necrosis, while IBT 9634 and IBT 3781 induced mostly necrosis. T-2 toxin and satratoxin G caused mainly apoptosis. Comet assay +/- formamidopyrimidine DNA glycosylase showed that only the spore exposures induced early (3h) oxidative DNA damage. Likewise, only the spores increased the formation of reactive oxygen species (ROS), suggesting that spores as particles may induce ROS formation and oxidative DNA damage. Increased Ataxia Telangiectasia Mutated (ATM) phosphorylation, indicating DNA damage, was observed after all exposures. The DNA damage response induced by IBT 9631 as well as satratoxin G was characterized by rapid (15 min) activation of p38 and H2AX. The p38 inhibitor SB 202190 reduced IBT 9631-induced H2AX activation. Both IBT 9631 and T-2 induced activation of Chk2 and H2AX after 3 h. The ATM inhibitor KU 55933, as well as transfection of cells with ATM siRNA, reduced this activation, suggesting a partial role for ATM as upstream activator for Chk2 and H2AX. In conclusion, activation of Chk2 and H2AX correlated with spore- and toxin-induced apoptosis. For IBT 9631 and satratoxin G, additional factors may be involved in triggering apoptosis, most notably p38 activation.