Characteristics of inflammation induced by fusarenon-X, a trichothecene mycotoxin from Fusarium species

Fusarenon-X (F-X) is one of the trichothecene mycotoxins, which have been suggested to induce Fusarium mycotoxicoses. Administration of F-X to experimental animals causes diarrhea, skin irritation, and foot edema. In the present work the properties of F-X-induced inflammation were examined. F-X increased capillary permeability of the abdominal blood vessels in a dose-dependent manner in mice. The F-X-induced increase of the abdominal capillary permeability was not inhibited by 200 mg/kg po of phenylbutazone, 200 mg/kg po of aspirin, 40 mg/kg po of phentolamine, 50 mg/kg po of diphenhydramine, 100 mg/kg po of dibenzyline, 200 mg/kg of hydrocortisone, and 4 mg/kg sc of reserpine. These results suggest that the permeability increment by F-X may not be mediated by serotonin, histamine, norepinephrine, prostaglandins, leukotrienes, and thromboxanes. The increment by F-X also appears to result from histological changes in the capillary blood vessels which are possibly induced by F-X-induced inhibition of protein synthesis, and/or from unidentified inflammatory chemical mediators.     

General pharmacological studies of fusarenon-X, a trichothecene mycotoxin from Fusarium species.

Fusarenon-X (F-X) is one of the trichothecene mycotoxins. In the present work, pharmacological properties of F-X were examined. (1) F-X induced hypothermia but did not produce appreciable behavioral changes of mice. (2) In anesthetized rats, F-X caused a rise in the blood pressure and a decrease in the respiratory rate but induced no significant change in the heart rate. (3) In isolated tissues such as fundus muscle, vas deferens, tracheal muscle, ileum, and atrium, F-X had no detectable effects on spontaneous activity and the responsiveness to agonists. (4) Subplantar administration of F-X into rat hindpaw induced edema. F-X had little influence on the histamine release from mast cells and the membrane stability of erythrocytes. (5) F-X decreased the spontaneous peristalsis of intestine but increased the intestinal propulsion of charcoal meal. (6) F-X induced vomiting in dogs which was suppressed by preliminary administration of chlorpromazine and metoclopramide. F-X may induce vomiting by stimulating the chemoreceptor trigger zone in dogs.     

Modulation of murine host response to enteric reovirus infection by the trichothecene deoxynivalenol.

Based on the known capacity of deoxynivalenol (DON) to target gut lymphoid tissue and IgA production, it was hypothesized that this mycotoxin interferes with the immune response to enteric reovirus infection. When mice were orally gavaged, first with 25 mg/kg bw DON, and then with reovirus serotype 1, strain Lang (T1/L) 2 or 12 h later, viral titers in the GI tract were 10-fold higher than control mice after 5 days. Virus was almost completely cleared in both treatment and control groups from intestinal tissue after 10 days. Real-time PCR indicated that, in infected control mice, reovirus lambda2 core spike (L2 gene) RNA per g feces in infected mice that were pretreated with DON was significantly higher at 1, 3, and 5 days than in infected mice only. In reovirus-infected mice, DON at doses of 10 and 25 mg/kg bw but not 2 and 5 mg/kg bw increased fecal L2 RNA, whereas DON doses as low as 2 mg/kg potentiated L2 RNA levels in Peyer's patches (PP). Reovirus-specific IgA levels in feces of mice treated with DON were significantly elevated, as were specific IgA responses in lamina propria and PP fragment cultures. Similar effects were observed for serum IgA and IgG. DON suppressed IFN-gamma responses in PP to reovirus at 3 and 5 days as compared to infected controls, while IL-2 mRNA concentrations were unaffected. Although reovirus alone did not induce Th2 cytokine mRNAs in PP, DON exposure significantly elevated IL-4, IL-6, and IL-10 mRNA expression at various times during the infection. ELISPOT revealed that mRNA expression data corresponded to suppression of IFN-gamma- and enhancement of IL-4-producing cell responses in PP cultures from DON-treated mice. Taken together, these data suggest that DON transiently increased both severity of the reovirus infection and shedding in feces as well as elevated reovirus IgA responses. These effects corresponded to suppressed Th1 and enhanced Th2 cytokine expression.     

Influence of agricultural practices on fusarium infection of cereals and subsequent contamination of grain by trichothecene mycotoxins

Fusarium head blight (FHB) of small grain cereals and ear rot in maize are significant diseases across the world. Infection can not only result in reduced yield as a result of shrunken grains but also result in reduced milling and malting quality and the contamination of grains with mycotoxins. Mycotoxins are hazardous to animal and human health. Therefore, guidelines and legislation are in place, or under consideration, in most countries to protect consumers and animal welfare. As fusarium mycotoxins are produced within the growing crop, it is important to understand how agricultural practices affect mycotoxin contamination of grain. Such information could then be used to determine guidelines on "Good Agricultural Practice" (GAP) to minimise the mycotoxin contamination of cereal products. Evidence is provided to show the importance of choice of cultivar, crop rotation, soil cultivation, fertiliser and the chemical and biological control of insects, weeds and fungi.     

Changes in circulatory white blood cells of mice and rats due to acute trichothecene intoxication

In mice, administration of pure T-2 toxin caused a rapid decrease of lymphocyte counts, which was linear with respect to dose, whereas granulocyte counts showed a delayed decrease. The blood cell counts of both cell types attained normal values after 4-7 days. Similar results were obtained for crude A-, B- and macrocyclic type trichothecene. Intoxication of rats with T-2 toxin or crude A-type trichothecene caused changes in white blood cells, which differed quantitatively from those in the mouse: lymphocyte counts decreased less and a rapid transient increase of granulocytes was more obvious. Results of this study show that lymphocyte and granulocyte blood cell counts of small rodents respond sensitively to acute intoxication with various trichothecenes.     

On the effects of Fusarium toxin contaminated wheat and wheat chaff on nutrient utilisation and turnover of deoxynivalenol and zearalenone in vitro (Rusitec).

The objective of the present study was to investigate the effects of Fusarium toxin contaminated wheat and wheat chaff (mycotoxin diet) on nutrient degradability and the metabolism of the mycotoxins deoxynivalenol (DON) and zearalenone (ZON) using the rumen simulations technique (Rusitec). A 6 day application period with control wheat and wheat chaff (control diet) was followed by an 8 day sampling phase. During this time three fermenters received the mycotoxin diet (64.9 mg DON/kg dry matter (DM) and 500 microg ZON/kg DM) and the remaining fermenters served as the controls (1.0mg DON/kg DM and 6 microg ZON/kg DM). Feed residues of the bags and samples of the effluent liquids were pooled per fermenter during the last 8 days of the experiment. Additionally, effluents of the mycotoxin fermenters were taken 6, 12 and 24h after the morning feeding on the first day of the sampling phase. The degradation of organic matter (OM; P<0.05), neutral detergent fibre (NDF; P<0.01) and protein (P<0.001) were increased by administration the Fusarium contaminated diet which was accompanied by an increased ammonia concentration (P<0.01) and increased butyrate (P<0.01), isobutyrate (P<0.01) and isovalerate (P<0.05) values of the mycotoxin effluents in relation to the controls. High proportions of ingested DON of 90% (85-93%) and ingested ZON of 93% (80-104%) were recovered at the pooled feed residues and effluents in form of DON and de-epoxy DON, and ZON and alpha-ZOL after administering the Fusarium toxin contaminated feed. While adsorption of DON as DON and de-epoxy DON in the feed particles was only minor (5%), a higher amount of 38% of ingested ZON was recovered as ZON and alpha-ZOL at the feed residues. The total recovery of DON plus de-epoxy DON in effluents as a percentage of DON intake reached 8%, 9% and 22% of ingested DON at 6, 12 and 24h after application of the contaminated diet the first time, whereby the recovery of de-epoxy DON as percentage of DON intake was only 5% at 24h. Concentrations of ZON and metabolites were lower than detection limits in the time dependent effluent samples.     

Direct and reflex cardiovascular effects of trichothecene mycotoxins

Intravenous injection of T-2 toxin or roridin-A (2 mg/kg) into pentobarbital-anesthetized (30 mg/kg) dogs produced, respectively, decreased systolic pressure within 30 min and atrio-ventricular block within 60 min. Within 45 +/- 15 min after injection of each toxin heart rate increased and remained elevated for at least 4 hr. The increase in sinus rate was reduced by 50% when dogs were pretreated with i.v. propranolol--HCl (5 mg/kg); pretreatment with atropine sulphate (5 mg/kg) did not alter the effect of the trichothecenes. Upon administration of T-2 toxin or roridin-A (30 mg/l) to isolated arterially perfused canine right atria, sinus rate decreased by 12% and 28%, respectively, and sinus node cell diastolic potentials became more negative by 7% and 10%, respectively. Sino-atrial block observed in 50% of the isolated atrial preparations perfused with roridin-A disappeared when toxin perfusion was discontinued. Perfusion with T-2 toxin or roridin-A produced no significant effects on atrial muscle cell action potentials. The cardiovascular response to systemic trichothecenes was hypotension followed by propranolol-sensitive tachycardia. The direct effects on conduction system cells may contribute to the overall deleterious action on the cardiovascular system.     

LPS priming potentiates and prolongs proinflammatory cytokine response to the trichothecene deoxynivalenol in the mouse

Simultaneous exposure to lipopolysaccharide (LPS) markedly amplifies induction of proinflammatory cytokine expression as well as IL-1-driven lymphocyte apoptosis by trichothecene deoxynivalenol (DON) in the mouse. The purpose of this research was to test the hypothesis that LPS priming will sensitize a host to DON-induced proinflammatory cytokine induction and apoptosis. In mice primed with LPS (1 mg/kg bw) ip. and treated 8 h later with DON po., the minimum DON doses for inducing IL-1alpha, IL-1beta, IL-6 and TNF-alpha serum proteins and splenic mRNAs were significantly lower than the DON doses required for vehicle-primed mice. LPS priming also decreased onset time and dramatically increased magnitude and duration of cytokine responses. LPS-primed mice maintained heightened sensitivity to DON for up to 24 h. LPS priming doses as low as 50 microg/kg bw evoked sensitization. DNA fragmentation analysis and flow cytometry also revealed that mice primed with LPS (1 mg/kg) for 8 h and exposed to DON (12.5 mg/kg) exhibited massive thymocyte loss by apoptosis 12 h later compared to mice exposed to DON or LPS alone. LPS priming decreased DON-induced p38 and ERK 1/2 phosphorylation suggesting that enhanced mitogen-activated protein kinase activation was not involved in increased cytokine responses. Taken together, exposure to LPS rendered mice highly susceptible to DON induction of cytokine expression and this correlated with increased apoptosis in the thymus.     

Pharmacokinetics of the trichothecene mycotoxin verrucarol in dogs

Verrucarol is a simple trichothecene which is structurally related to T-2 and HT-2 toxins. Several macrocyclic trichothecenes which are ester derivatives of verrucarol possess antitumor activity. The pharmacokinetics of verrucarol has been studied in eight dogs following iv and oral administrations (0.4 and 0.8 mg/kg, respectively). The iv study showed that verrucarol has a mean (+/- SD) clearance of 11 +/- 5.5 mL/min/kg, a volume of distribution of 1.2 +/- 0.6 L/kg, and a terminal half-life of 1.6 +/- 0.5 h. Following oral administration, the absolute bioavailability of verrucarol was 44 +/- 33%, and its terminal half-life was similar to that obtained after iv administration. In comparison with T-2 and HT-2 toxins, verrucarol has a longer half-life and a lower clearance, and its liver extraction ratio is about one third of that of T-2 and HT-2 toxins. Therefore, verrucarol is less susceptible to a liver first-pass effect and its partially absorbed after oral administration. These characteristics make verrucarol the first partially absorbed trichothecene whose pharmacokinetics was investigated following oral administration.     

Studies on mechanisms of diarrhea induced by fusarenon-X, a trichothecene mycotoxin from Fusarium species: fusarenon-X-induced diarrhea is not mediated by cyclic nucleotides

Cardinal signs of red mold toxicosis in man and farm animals are vomiting, nausea, diarrhea, and food refusal. The red mold toxicosis has been suggested to be induced by trichothecenes, which are produced by Fusarium fungi. Fusarenon-X (F-X) is one of the trichothecene mycotoxins. The ip injection of F-X to rats causes an expansion of the small intestine and watery diarrhea. In this study, we measured the concentrations of protein, sodium, potassium, and calcium in the serum of rat treated with F-X for the sake of demonstrating the loss of serum protein and the decreases of serum sodium and calcium by F-X. Since it is well known that some diarrheal diseases are due to the increase of cyclic nucleotide level in the intestinal mucosa, we also measured cyclic AMP and cyclic GMP levels in the intestinal mucosa. It was demonstrated that F-X did not increase the cyclic AMP and cyclic GMP levels in the jejunal and the ileal mucosa at 8 and 24 hr after F-X treatment. The results obtained in this work suggest that F-X-induced diarrhea is not mediated by the cyclic nucleotide system.     

社区与医院获得性感染铜绿假单胞菌药物敏感性对比研究

目的：了解社区与医院感染中铜绿假单胞菌的耐药性及其主要耐药基因,为临床合理用药提供依据。方法：收集2013年1月-2015年1月间在军区门诊部和华西医院分离到的597株铜绿假单胞菌,其中医院感染339株,社区感染258株。MIC 法检测其药敏结果。对105株细菌利用PCR法扩增耐药相关基因,采用SPSS16.0统计软件进行分析。结果：社区感染铜绿假单胞菌耐药率普遍低于医院感染铜绿假单胞菌,如哌拉西林（20.4%,10.1%）、头孢他啶（21.5%,11.6%）;医院感染组 OPRD2, VIM, OXA-10基因检出率为60.0%、44.3%、88.6%,社区感染组基因检出率分别为34.3%、14.3%、71.4%,两组基因检出率比较差异有统计学意义（P<0.05）。结论：医院感染铜绿假单胞菌耐药率高于社区感染铜绿假单胞菌,而金属β－内酰胺酶、碳青霉烯水解酶的产生和OPRD2缺失是医院感染铜绿假单胞菌的耐亚胺培南的主要机制,所以合理选择用药,加强医院的感染监测是控制细菌耐药性产生的有效措施。     

Emetic activity of the trichothecene 15-acetyldeoxynivalenol in swine

The emetic activity of 15-acetyldeoxynivalenol (15-ADON), a deoxynivalenol (DON) precursor, was evaluated in swine over a dose range of 25-200 micrograms/kg body weight and found to be very similar to that of DON. The minimum effective oral doses for 15-ADON and DON were 75 and 50 micrograms/kg, respectively, with 3/15 of the 15-ADON- and 4/15 of the DON-treated pigs exhibiting emesis, over the total dose range. The minimum effective ip doses for 15-ADON and DON were also 75 and 50 micrograms/kg, respectively, with 9/15 pigs in each group exhibiting emesis, over the total dose range. For pigs receiving 15-ADON and DON ip, increased dosage was associated with decreased average time to vomition, increased duration of emesis and increased average number of vomitions.     

Impaired murine resistance to Salmonella typhimurium following oral exposure to the trichothecene T-2 toxin

On orally exposing Salmonella-resistant C3H/HeN mice to the trichothecene T-2 toxin (1 mg/kg body weight), challenging with Salmonella typhimurium, and continuing to dose with T-2 toxin on alternate days for 3 wk, the LD50 for the organism decreased by five orders of magnitude, in comparison with control mice not treated with T-2 toxin. In the absence of S. typhimurium, T-2 toxin did not cause lethal effects when administered at this level. Increased mortality in response to S. typhimurium challenge was dependent on T-2 toxin dose in the range 0 to 1 mg/kg for this regimen. The toxin did not significantly affect intestinal infection but did increase splenic counts in mice challenged with a range of S. typhimurium doses and also accelerated body-weight loss in infected animals. Mice challenged with the organism exhibited similar mortality when T-2 toxin treatment was begun 1 day prior to infection or at 5 or 9 days after infection. A time-related decrease in mortality, relative to that found for the standardized co-challenge described above, was observed when T-2 toxin administration was begun at 9, 13 or 23 days after infection. The results indicated that, depending on the challenge dose of the organism, both early and late phase acquired immune response to S. typhimurium could be impaired by T-2 toxin. Markedly enhanced susceptibility to gram-negative bacterial infection is another manifestation of trichothecene toxicity and may be an important aetiological factor in animal health problems that are associated with these mycotoxins.     

Amplified proinflammatory cytokine expression and toxicity in mice coexposed to lipopolysaccharide and the trichothecene vomitoxin (deoxynivalenol).

A single oral exposure to the trichothecene vomitoxin (VT) has been previously shown in the mouse to increase splenic mRNA levels for several cytokines in as little as 2 h. Since one underlying mechanism for these effects likely involves superinduction of transiently expressed cytokine genes, VT may also potentially amplify cytokine responses to inflammatory stimuli. To test this possibility, the effects of oral VT exposure on tumor necrosis factor-alpha (TNF-alpha), interleukin-6 (IL-6), and IL-1beta expression were measured in mice that were intraperitoneally injected with lipopolysaccharide (LPS), a prototypic inflammatory agent. As anticipated, VT alone at 1, 5, and 25 mg/kg body weight increased splenic mRNA expression of all three cytokines after 3 h in a dose-response fashion. LPS injection at 1 and 5 mg/kg body weight also induced proinflammatory cytokine mRNA expression. There was a synergistic increase in TNF-alpha splenic mRNA levels in mice treated with both VT and LPS as compared to mice treated with either toxin alone, whereas the effects were additive for IL-6 and IL-1beta mRNA expression. When relative mRNA levels were examined over a 12-h period in mice given LPS (1 mg/kg) and/or VT (5 mg/kg), significant enhancement was observed up to 6, 12, and 3 h for TNF-alpha, IL-6, and IL-1beta, respectively. When plasma cytokine concentrations were measured, TNF-alpha was found to peak at 1 h and was significantly increased at 1, 3, and 6 h if mice were given LPS and VT, whereas LPS or VT alone caused much smaller increases in plasma TNF-alpha Plasma IL-6 peaked at 3 h in LPS, VT, and LPS/VT groups, with the combined toxin group exhibiting additive effects. Plasma IL-1beta was not detectable. The potential for VT and LPS to enhance toxicity was examined in a subsequent study. Mortality was not observed up to 72 h in mice exposed to a single oral dose of VT at 25 mg/kg body weight or to an intraperitoneal dose of LPS at 1 or 5 mg/kg body weight; however, all mice receiving VT and either LPS dose became moribund in less than 40 h. The principal histologic lesions in the moribund mice treated with VT and LPS were marked cell death and loss in thymus, Peyer's patches, spleen, and bone marrow. In all of these lymphoid tissues, treatment-induced cell death had characteristic histologic features of apoptosis causing lymphoid atrophy. These results suggest that LPS exposure may markedly increase the toxicity of trichothecenes and that the immune system was a primary target of these interactive effects.     

The fates of trichothecene mycotoxins, nivalenol and fusarenon-X, in mice

In order to investigate the comparative fates of nivalenol (NIV) and 4-acetyl derivative of NIV (fusarenon-X, FX) in mice, ³H-FX or ³H-NIV was given p.o. to mice. Radioactivity was excreted mainly via the urine in mice given ³H-FX, but mainly via the feces in mice given ³H-NIV. The plasma radioactivity reached a peak at 30 or 60 min after the administration of ³H-FX or ³H-NIV, respectively. The plasma peak level was 5 times higher, and the area under curve (AUC) was 10 times higher, in ³H-FX-administered than ³H-NIV-administered mice. These findings clearly demonstrate that FX is absorbed from the gastrointestinal tract more rapidly and efficiently than NIV. The HPLC profile of radioactivity of acetonitrile extracts of urine and feces indicated that FX is rapidly metabolized to NIV after being absorbed from the gastrointestinal tract. In vitro incubation of tissue homogenates with ³H-FX demonstrated that the liver and kidney are the organs responsible for the FX-to-NIV conversion. Thus this study demonstrated that the higher oral toxicity of FX than NIV that has been observed in mice and rats is due to the efficient absorption of FX than NIV from the gastrointestinal tract, followed by its rapid conversion to NIV by the liver and kidney.     

Treatment of murine Fusarium verticillioides infection with liposomal amphotericin B plus terbinafine

Using a murine model of disseminated infection by Fusarium verticillioides, the efficacy of liposomal amphotericin (L-AmB) B at 10mg/kg body weight once daily and terbinafine (TRB) at 150 mg/kg body weight twice daily, alone and in combination, was evaluated. The combination of L-AmB with TRB was the only treatment able to prolong survival and to reduce fungal loads in the spleen and kidneys of mice infected with either strain of F. verticillioides used. The results suggest that this combination may have a role in the treatment of F. verticillioides infection.