Increases in serum sphingosine and sphinganine and decreases in complex sphingolipids in ponies given feed containing fumonisins, mycotoxins produced by Fusarium moniliforme

Occurrence of fumonisin-producing black aspergilli in Australian wine grapes: effects of temperature and water activity on fumonisin production by A. niger and A. welwitschiae

Black aspergilli are some of the most common mycotoxigenic fungi in vineyards worldwide. The aims of this research were to assess the occurrence of fumonisin-producing black aspergilli in Australian wine grapes and the effects of environmental factors on fumonisin production by A. niger and A. welwitschiae (syn. A. awamori). Thirty-eight Aspergillus isolates (black aspergilli) were collected from six wine grape varieties grown in Australian vineyards. LC-MS/MS analysis of culture extracts revealed that six isolates produced fumonisins FB₂ and FB₄. Molecular data revealed that all fumonisin-producing isolates were A. niger and A. welwitschiae. None of the reference isolates, A. carbonarius, A. tubingensis, A. japonicus, and A. foetidus, were positive for fumonisin production. The effects of temperature and water activity on the growth and production of fumonisins were studied using two A. niger and an isolate of A. welwitschiae on synthetic grape juice medium (SGJM) at 20 °C, 25 °C, 30 °C, and 35 °C, and 0.92 a_w, 0.95 a_w, and 0.98 a_w levels. All isolates produced FB₂ and FB₄ at 0.95 a_w and 0.98 a_w and 20 °C, 25 °C, and 30 °C. The highest growth rate observed was 14.89 mm/day for A. welwitschiae at 0.98 a_w and 35 °C, whereas the highest fumonisin production observed was 25.3 mg/kg at 0.98 a_w and 20 °C for A. welwitschiae. None of the isolates produced fumonisins at 35 °C at any water activity levels. To our knowledge, this is the first report on the occurrence of fumonisin-positive isolates of Aspergillus from Australian wine grapes and the impact of the environmental factors on fumonisin production by A. welwitschiae.

Mycotoxin Fumonisin B1 Interferes Sphingolipid Metabolisms and Neural Tube Closure during Early Embryogenesis in Brown Tsaiya Ducks

Fumonisin B₁ (FB₁) is among the most common contaminants produced by Fusarium spp. fungus from corns and animal feeds. Although FB₁ has been known to cause physical or functional defects of embryos in humans and several animal species such as Syrian hamsters, rabbits, and rodents, little is known about the precise toxicity to the embryos and the underlying mechanisms have not been fully addressed. The present study aimed to investigate its developmental toxicity and potential mechanisms of action on sphingolipid metabolism in Brown Tsaiya Ducks (BTDs) embryos. We examined the effect of various FB₁ dosages (0, 10, 20 and 40 µg/embryo) on BTD embryogenesis 72 h post-incubation. The sphingomyelin content of duck embryos decreased (p < 0.05) in the highest FB₁-treated group (40 µg). Failure of neural tube closure was observed in treated embryos and the expression levels of a neurulation-related gene, sonic hedgehog (Shh) was abnormally decreased. The sphingolipid metabolism-related genes including N-acylsphingosine amidohydrolase 1 (ASAH1), and ceramide synthase 6 (CERS6) expressions were altered in the treated embryos compared to those in the control embryos. Apparently, FB₁ have interfered sphingolipid metabolisms by inhibiting the functions of ceramide synthase and folate transporters. In conclusion, FB₁-caused developmental retardation and abnormalities, such as neural tube defects in Brown Tsaiya Duck embryos, as well as are partly mediated by the disruption of sphingolipid metabolisms.

Research Progress on Fumonisin B1 Contamination and Toxicity: A Review

Fumonisin B1 (FB1), belonging to the member of fumonisins, is one of the most toxic mycotoxins produced mainly by Fusarium proliferatum and Fusarium verticillioide. FB1 has caused extensive contamination worldwide, mainly in corn, rice, wheat, and their products, while it also poses a health risk and is toxic to animals and human. It has been shown to cause oxidative stress, endoplasmic reticulum stress, cellular autophagy, and apoptosis. This review focuses on the current stage of FB1 contamination, its toxic effects of acute toxicity, immunotoxicity, organ toxicity, and reproductive toxicity on animals and humans. The potential toxic mechanisms of FB1 are discussed. One of the main aims of the work is to provide a reliable reference strategy for understanding the occurrence and toxicity of FB1.

Molecular toxicology and carcinogenesis of fumonisins: a review

Fumonisins, discovered in 1988 are a group of naturally occurring toxins produced by fusarium pathogenic fungi. Besides their presence in animal feeds, contamination of human foods such as corn, millet, oats, rye, barley, wheat and their products are widespread. Exposure to fumonisins results in species and organ specific toxicities including neurological disorders among equids, pulmonary edema in swine, esophageal cancer in humans and both kidney and liver related toxicities in rodents. This review seeks to consolidate groundbreaking research on the science of fumonisins toxicity, highlight recent progress on fumonisins research, and provide an overview of plausible mechanistic biomarkers for fumonisins exposure assessment.

Fusarium: a treasure trove of bioactive secondary metabolites

Covering up to December 2019Fusarium, one of the most common fungal genera, has received considerable attention because of its biosynthetic exuberance, the result of many unique gene clusters involved in the production of secondary metabolites. This review provides the first comprehensive analysis of the secondary metabolites unique to the genus Fusarium, describing their occurrence, bioactivity, and genome features.

Self-Protection against the Sphingolipid Biosynthesis Inhibitor Fumonisin B1 Is Conferred by a FUM Cluster-Encoded Ceramide Synthase

Fumonisin (FB) mycotoxins produced by species of the genus Fusarium detrimentally affect human and animal health upon consumption, due to the inhibition of ceramide synthase. In the present work, we set out to identify mechanisms of self-protection employed by the FB₁ producer Fusarium verticillioides FB₁ biosynthesis was shown to be compartmentalized, and two cluster-encoded self-protection mechanisms were identified. First, the ATP-binding cassette transporter Fum19 acts as a repressor of the FUM gene cluster. Appropriately, FUM19 deletion and overexpression increased and decreased, respectively, the levels of intracellular and secreted FB₁ Second, the cluster genes FUM17 and FUM18 were shown to be two of five ceramide synthase homologs in Fusarium verticillioides, grouping into the two clades CS-I and CS-II in a phylogenetic analysis. The ability of FUM18 to fully complement the yeast ceramide synthase null mutant LAG1/LAC1 demonstrated its functionality, while coexpression of FUM17 and CER3 partially complemented, likely via heterodimer formation. Cell viability assays revealed that Fum18 contributes to the fungal self-protection against FB₁ and increases resistance by providing FUM cluster-encoded ceramide synthase activity.IMPORTANCE The biosynthesis of fungal natural products is highly regulated not only in terms of transcription and translation but also regarding the cellular localization of the biosynthetic pathway. In all eukaryotes, the endoplasmic reticulum (ER) is involved in the production of organelles, which are subject to cellular traffic or secretion. Here, we show that in Fusarium verticillioides, early steps in fumonisin production take place in the ER, together with ceramide biosynthesis, which is targeted by the mycotoxin. A first level of self-protection is given by the presence of a FUM cluster-encoded ceramide synthase, Fum18, hitherto uncharacterized. In addition, the final fumonisin biosynthetic step occurs in the cytosol and is thereby spatially separate from the fungal ceramide synthases. We suggest that these strategies help the fungus to avoid self-poisoning during mycotoxin production.

Risk assessment for mycotoxin contamination in fish feeds in Europe

Mycotoxins are difficult to monitor continuously, and a tool to assess the risk would help to judge if there is a particular risk due to the inclusion of certain feed ingredients. For this, the toxin contents of 97 commercial fish feeds have been estimated, and the most prominent toxins in fish feed are calculated to be deoxynivalenol, zearalenone, fumonisins and enniatins. These pose a risk to fish well-being, as can be calculated by the Bayesian models for determining the critical concentrations 5% (CC5) for the different toxins. Besides fishmeal, wheat, soybean products and corn are regularly used as fish feed ingredients. The calculated scenarios show that fish are at high risk of toxin contamination if feed ingredients of low quality are chosen for feed production. Due to this, specific maximum allowable levels for several mycotoxins in fish feeds should be established.

Biomarker Evaluation and Toxic Effects of an Acute Oral and Systemic Fumonisin Exposure of Pigs with a Special Focus on Dietary Fumonisin Esterase Supplementation

The mycotoxin fumonisin B1 (FB1) is a frequent contaminant of feed. It causes a disruption of sphingolipid metabolism and pulmonary, hepatic, and immunological lesions in pigs depending on the exposure scenario. One sensitive biomarker for FB1 exposure is the sphinganine (Sa) to sphingosine (So) ratio in blood. The fumonisin esterase FumD, which can be used as a feed additive, converts FB1 into the much less toxic metabolite hydrolyzed FB1 (HFB1). We conducted a single-dose study with barrows allocated to one of five treatments: (1) control (feed, 0.9% NaCl intravenously iv), (2) 139 nmol FB1 or (3) HFB1/kg BW iv, (4) 3425 nmol FB1/kg BW orally (po), or (5) 3321 nmol FB1/kg BW and 240 U FumD/kg feed po. The Sa/So ratio of iv and po FB1 administered groups was significantly elevated in blood and Liquor cerebrospinalis, but no fumonisin-associated differences were reflected in other endpoints. Neither clinical lung affections nor histopathological pulmonary lesions were detected in either group, while some parameters of hematology and clinical biochemistry showed a treatment–time interaction. FumD application resulted in Sa/So ratios comparable to the control, indicating that the enzymatic treatment was effectively preventing the fumonisin-induced disruption of sphingolipid metabolism.

Fusarium Molds and Mycotoxins: Potential Species-Specific Effects

This review summarizes the information on biochemical and biological activity of the main Fusarium mycotoxins, focusing on toxicological aspects in terms of species-specific effects. Both in vitro and in vivo studies have centered on the peculiarity of the responses to mycotoxins, demonstrating that toxicokinetics, bioavailability and the mechanisms of action of these substances vary depending on the species involved, but additional studies are needed to better understand the specific responses. The aim of this review is to summarize the toxicological responses of the main species affected by Fusarium mycotoxins.

Fumonisin B₁ (FB₁) Induces Lamellar Separation and Alters Sphingolipid Metabolism of In Vitro Cultured Hoof Explants

One of the most important hoof diseases is laminitis. Yet, the pathology of laminitis is not fully understood. Different bacterial toxins, e.g. endotoxins or exotoxins, seem to play an important role. Additionally, ingestion of mycotoxins, toxic secondary metabolites of fungi, might contribute to the onset of laminitis. In this respect, fumonsins are of special interest since horses are regarded as species most susceptible to this group of mycotoxins. The aim of our study was to investigate the influence of fumonisin B₁ (FB₁) on primary isolated epidermal and dermal hoof cells, as well as on the lamellar tissue integrity and sphingolipid metabolism of hoof explants in vitro. There was no effect of FB₁ at any concentration on dermal or epidermal cells. However, FB₁ significantly reduced the separation force of explants after 24 h of incubation. The Sa/So ratio was significantly increased in supernatants of explants incubated with FB₁ (2.5–10 µg/mL) after 24 h. Observed effects on Sa/So ratio were linked to significantly increased sphinganine concentrations. Our study showed that FB₁ impairs the sphingolipid metabolism of explants and reduces lamellar integrity at non-cytotoxic concentrations. FB₁ might, therefore, affect hoof health. Further in vitro and in vivo studies are necessary to elucidate the effects of FB₁ on the equine hoof in more detail.

Mitigation of Fumonisin Biomarkers by Green Tea Polyphenols in a High-Risk Population of Hepatocellular Carcinoma

Green tea polyphenols (GTP) are highly effective in inhibiting a variety of tumorigenic effects induced by carcinogens. In this study we assessed GTP mitigation on biomarkers of fumonisin B₁ (FB₁), a class 2B carcinogen, in blood and urine samples collected from an intervention trial. A total of 124 exposed people were recruited and randomly assigned to low-dose (GTP 500 mg, n = 42), high-dose (GTP 1,000 mg, n = 41) or placebo (n = 41) for 3 months. After one-month of intervention, urinary FB₁ was significantly decreased in high-dose group compared to that of placebo group (p = 0.045), with reduction rates of 18.95% in the low-dose group and 33.62% in the high-dose group. After three-month intervention, urinary FB₁ showed significant decrease in both low-dose (p = 0.016) and the high-dose (p = 0.0005) groups compared to that of both placebo group and baseline levels, with reduction rates of 40.18% in the low-dose group and 52.6% in the high-dose group. GTP treatment also significantly reduced urinary excretion of sphinganine (Sa), sphingosine (So), and Sa/So ratio, but had no effect on serum Sa, So, and Sa/So ratio. Analysis with mixed-effect model revealed significant interactions between time and treatment effects of GTP on both urinary free FB₁ levels and Sa/So ratios.

Fusarial toxins: secondary metabolites of Fusarium fungi

Exposure to mycotoxins occurs worldwide, even though there are geographic and climatic differences in the amounts produced and occurrence of these substances.Mycotoxins are secondary chemical metabolites of different fungi. They are natural contaminants of cereals, so their presence is often inevitable. Among many genera that produce mycotoxins, Fusarium fungi are the most widespread in cereal-growing areas of the planet. Fusarium fungi produce a diversity of mycotoxin types, whose distributions are also diverse. What is produced and where it is produced is influenced primarily by environmental conditions, and crop production and storage methods. The amount of toxin produced depends on physical (viz., moisture, relative humidity, temperature, and mechanical damage), chemical (viz., carbon dioxide,oxygen, composition of substrate, insecticides and fungicides), and biological factors (viz., plant variety, stress, insects, spore load, etc.). Moisture and temperature have a major influence on mold growth rate and mycotoxin production.Among the most toxic and prevalent fusaria) toxins are the following: zearalenone,fumonisins, moniliformin and trichothecenes (T-2/HT-2 toxin, deoxynivalenol,diacetoxyscirpenol, nivalenol). Zearalenone (ZEA; ZON, F-2 toxin) isaphy to estrogenic compound, primarily a field contaminant, which exhibits estrogenic activity and has been implicated in numerous mycotoxicoses of farm animals,especially pigs. Recently, evidence suggests that ZEA has potential to stimulate the growth of human breast cancer cells. Fumonisins are also cancer-promoting metabolites,of which Fumonisin 8 I (FBI) is the most important. Moniliformin (MON) isalso highly toxic to both animals and humans. Trichothecenes are classified as gastrointestinal toxins, dermatotoxins, immunotoxins, hematotoxins, and gene toxins.T-2 and HT-2 toxin, and diacetoxyscirpenol (DAS, anguidine) are the most toxic mycotoxins among the trichothecene group. Deoxynivalenol (DON, vomitoxin) and nivalenol although less toxic are important because they frequently occur at levels high enough to cause adverse effects.The presence of mycotoxins in the animal diet can produce significant production losses. Any considerable presence of mycotoxins, in major dietary components,confirms the need to adopt a continuous prevention and control program. Such programs are usually based on several common approaches to minimize mycotoxin contamination in the food chain. Major strategies include preventing fungal growth and therefore mycotoxin formation, reducing or eliminating mycotoxins from contaminated feedstuffs, or diverting contaminated products to low risk uses. Because of the complexity of their chemical structures, mycotoxins also present a major analytical challenge. They are also found in a vast array of feed matrices. Analysis is essential for determining the extent of mycotoxin contamination, for risk analysis, confirming the diagnosis of a mycotoxicosis and for monitoring mycotoxin mitigation strategies.For the future, adequately controlling the mycotoxin problem in the livestock economy will depend on implementing appropriate agricultural management policies,as well as augmenting production and storage systems and analysis methods.Only such policies offer the opportunity to bring solid and long-lasting economical results to the livestock industry that is afflicted with the mycotoxin problem.

Fumonisin biomarkers in maize eaters and implications for human disease

Maize is the predominant food source contaminated by fumonisins and this has particular health risks for communities consuming maize as a staple diet. The main biochemical effect of fumonisins is the inhibition of ceramide biosynthesis causing an increase in sphingoid bases and sphingoid base 1-phosphates and a depletion of the complex sphingolipids, thereby disrupting lipid metabolism and sphingolipid-mediated processes and signalling systems. Attempts to use the elevation of sphinganine as a human biomarker of fumonisin exposure have to date been unsuccessful. Consequently, recent research has focussed on developing a urinary exposure biomarker based on the measurement of the nonmetabolised toxin. In animals, fumonisins are poorly absorbed in the gut and are mostly excreted unmetabolised in faeces, with only a small percentage (0.25-2.0%) in urine. This appears to also be true in humans were fumonisin B1 (FB1) is detectable in urine soon after exposure, but in very small amounts relative to total intake. However, with modern sensitive and selective analytical methods such as liquid chromatography-tandem mass spectrometry, these low levels can be readily determined. The first study to show a positive correlation between consumption of maize and urinary FB1 was conducted in a Mexican population consuming tortillas as a staple food. Further validation of this relationship was achieved in a South African subsistence farming community with a positive correlation between urinary FB1 and fumonisin exposure, as assessed by food analysis and food intake data. The most recent developments are aimed at measuring multiple mycotoxin biomarkers in urine, including FB1. Current exposure studies in Guatemala are combining the urinary biomarker with measurement of sphinganine-1-phosphate in blood spots as a measure of biochemical effect. Thus, the urinary FB1 biomarker could contribute considerably in assessing the adverse health impact of fumonisin exposure.

Comparative effects of fumonisins on sphingolipid metabolism and toxicity in ducks and turkeys

Fumonisins (FBs) are mycotoxins that are found worldwide in maize and maize products. Their main toxic effects have been well characterized in poultry, but differences between species have been demonstrated. Ducks appeared very sensitive to toxicity, whereas turkeys are more resistant. At the same time, alterations of sphingolipid metabolism, with an increase of the concentration of the free sphinganine (Sa) in serum and liver, have been demonstrated in the two species, but the link between the toxicity of FBs and Sa accumulation remains difficult to interpret. The aim of the present work was to compare the effects of FBs (10 mg FB1 + FB2/kg body weight) on sphingolipid metabolism in ducks and turkeys. Growth, feed consumption, and serum biochemistry were also investigated to evaluate toxicity. The main results showed that FBs increased Sa concentrations in liver and serum in ducks and turkeys, but these accumulations were not directly correlated with toxicity. Sa accumulation was higher in the livers of turkeys than in ducks, whereas Sa levels were higher in the sera of ducks than in turkeys. Hepatic toxicity was more pronounced in ducks than in turkeys and accompanied a decrease of body weight and an increase of serum biochemistry in ducks but not in turkeys. So, although FBs increase Sa concentration in the livers of both species, this effect is not directly proportional to toxicity. The mechanisms of FB toxicity and/or the mechanisms of protection of ducks and turkeys to the Sa accumulation within the liver remain to be established.

Occurrence, Rapid Analysis, and Detoxification of Fumonisins in Maize and its Feeds: Review

Maize (Zea mays L.) is one of the main cereals as a source of food, forage and processed products for industry, especially for feeds. However, in worldwide approximately 25% of crops are affected by mycotoxins annually, especially in feeds with fumonisins(FUM). Moreover, the exact mechanism of FUM toxicity is not completely established. This paper gives an overview about the occurrence, toxicity, rapid non-invasive analysis, and detoxification of FUM in maize and its feeds. Due to economic losses engendered by FUM and its impact on animal and human health, several strategies for detecting mycotoxins with non-invasive methods and detoxifying contaminated feeds have been described.

Toxins and adverse drug reactions affecting the equine nervous system

This article provides an overview of the more common toxins and adverse drug reactions, along with more rare toxins and reactions (Table 1), that result in neurologic dysfunction in horses. A wide variety of symptoms, treatments, and outcomes are seen with toxic neurologic disease in horses. An in-depth history and thorough physical examination are needed to determine if a toxin or adverse drug reaction is responsible for the clinical signs. Once a toxin or adverse drug reaction is identified, the specific antidote, if available, and supportive care should be administered promptly.

Biomonitoring of Fusarium spp. Mycotoxins: Perspectives for an Individual Exposure Assessment Tool

Fusarium species are probably the most prevalent toxin-producing fungi of the northern temperate regions and are commonly found on cereals grown in the temperate regions of America, Europe and Asia. Among the toxins formed by Fusarium we find trichothecenes of the A-type or B-type, zearalenone, fumonisins or nivalenol. The current exposure assessment consists of the qualitative and/or quantitative evaluation based on the knowledge of the mycotoxin occurrence in the food and the dietary habits of the population. This process permits quantifying the mycotoxin dietary intake through deterministic or probabilistic methods. Although these methods are suitable to assess the exposure of populations to contaminants and to identify risk groups, they are not recommended to evaluate the individual exposition, due to a low accuracy and sensitivity. On the contrary, the use of biochemical indicators has been proposed as a suitable method to assess individual exposure to contaminants. In this work, several techniques to biomonitor the exposure to fumonisins, deoxynivalenol, zearalenone or T-2 toxin have been reviewed.

Aquilegia vulgaris L. extract counteracts oxidative stress and cytotoxicity of fumonisin in rats

Exposure to fumonisins (FB) is known to have toxic and carcinogenic effects in different animal species, and to express toxicity in cells via the induction of oxidative stress. The aim of the current study was to evaluate the protective effects of the ethanol extract of Aquilegia vulgaris L. against the oxidative stress and the genotoxicity using micronucleus assay and random amplified polymorphism DNA (RAPD-PCR) in FB-treated rats. Sixty mature female Sprague-Dawley were divided into six treatment groups and treated for 4 weeks as follow: the control group, the group fed FB-contaminated diet (200 mg/kg diet), the groups treated orally with the extract (5 and 10 mg/kg bw) and the groups fed FB-contaminated diet and treated with the extract at the two doses. The results showed that treatment with FB alone disturbed lipid profile in serum, increases Sa/So ratio, induces micronucleated polychromatic erythrocytes (Mn-PCEs) in bone marrow, increases DNA and RNA in liver accompanied with significant changes in histological picture The extract alone at the two tested doses did not induce any significant changes in the biochemical or histological picture. The combined treatment showed significant improvements in all biochemical, cytogenetic parameters tested and histological pictures in the liver tissues. Moreover, this improvement was more pronounced in the group received the high dose of the extract. It could be concluded that the ethanol extract of A. vulgaris induced its protective effect via the increase in the antioxidant capacity, inhibition of lipid peroxidation and scavenging of free radicals.

Mycotoxins in animal and human patients

The majority of human food and animal feed production occurs in a highly managed agroecosystem. Management decisions include variety grown, tillage and irrigation methods and practices, fertilization, pest and disease control, harvesting methods, and storage and transportation practices. This system is generally managed for optimum returns to labor and capital investments. The spores of toxigenic fungi have ubiquitous distribution and toxigenic fungi exploit food sources when conditions of moisture and temperature are above minimums for growth. The safety margins in the agroecosystem are close and are influenced by extrinsic factors such as climatic events. Control of fungal growth is important in management of raw feedstuffs, foodstuffs, condiments-spices, botanicals, and other consumable substances as they are grown, harvested, stored, and transported. The risk factors for mycotoxin production are weather conditions during crop growth and when the crop is mature, damage to seeds before, during, and after harvest, how commodities are physically handled, the presence of weed seeds and other foreign material in grain, and how commodity moisture and temperature are managed during storage and transportation. Diversion of commodities and by-products from human consumption to animal feedstuffs can increase the risk of mycotoxicoses in animals. The toxicology of selected toxigenic fungi and the mycotoxins they produce are reviewed.

A review of the toxic effects and mechanisms of action of fumonisin B1

Fumonisin B(1) (FB(1)) is a mycotoxin produced by the fungus Fusarium verticillioides, which commonly infects corn and other agricultural products. Fusarium species can also be found in moisture-damaged buildings, and, therefore, exposure of humans to Fusarium mycotoxins including FB(1) may take place. FB(1) bears a clear structural similarity to the cellular sphingolipids, and this similarity has been shown to disturb the metabolism of sphingolipids by inhibiting the enzyme ceramide synthase leading to accumulation of sphinganine in cells and tissues. FB(1) is neurotoxic, hepatotoxic, and nephrotoxic in animals, and it has been classified as a possible carcinogen to humans. The cellular mechanisms behind FB(1)-induced toxicity include the induction of oxidative stress, apoptosis, and cytotoxicity, as well as alterations in cytokine expression. The effects of FB(1) on different parameters vary markedly depending on what types of cells are studied or what species they originate from. These aspects are important to consider when evaluating the toxic potential of FB(1).

Maternal fumonisin exposure as a risk factor for neural tube defects

Fumonisins are mycotoxins produced by the fungus F. verticillioides, a common contaminant of maize (corn) worldwide. Maternal consumption of fumonisin B(1)-contaminated maize during early pregnancy has recently been associated with increased risk for neural tube defects (NTDs) in human populations that rely heavily on maize as a dietary staple. Experimental administration of purified fumonisin to mice early in gestation also results in an increased incidence of NTDs in exposed offspring. Fumonisin inhibits the enzyme ceramide synthase in de novo sphingolipid biosynthesis, resulting in an elevation of free sphingoid bases and depletion of downstream glycosphingolipids. Increased sphingoid base metabolites (i.e., sphinganine-1-phosphate) may perturb signaling cascades involved in embryonic morphogenesis by functioning as ligands for sphingosine-1-P (S1P) receptors, a family of G-protein-coupled receptors that regulate key biological processes such as cell survival/proliferation, differentiation and migration. Fumonisin-induced depletion of glycosphingolipids impairs expression and function of the GPI-anchored folate receptor (Folr1), which may also contribute to adverse pregnancy outcomes. NTDs appear to be multifactorial in origin, involving complex gene-nutrient-environment interactions. Vitamin supplements containing folic acid have been shown to reduce the occurrence of NTDs, and may help protect the developing fetus from environmental teratogens. Fumonisins appear to be an environmental risk factor for birth defects, although other aspects of maternal nutrition and genetics play interactive roles in determining pregnancy outcome. Minimizing exposures to mycotoxins through enhanced agricultural practices, identifying biomarkers of exposure, characterizing mechanisms of toxicity, and improving maternal nutrition are all important strategies for reducing the NTD burden in susceptible human populations.

Evaluation of sphingolipids in Wistar rats treated to prolonged and single oral doses of fumonisin b₁

The objective of the present study was to evaluate sphingolipid levels (sphingosine-So and sphinganine-Sa) and to compare the Sa/So ratio in liver, serum and urine of Wistar rats after prolonged administration (21 days) of fumonisin B(1) (FB(1)). In parallel, the kinetics of sphingolipid elimination in urine was studied in animals receiving a single dose of FB(1). Prolonged exposure to FB(1) caused an increase in Sa levels in urine, serum and liver. The most marked effect on sphingolipid biosynthesis was observed in animals treated with the highest dose of FB(1). Animals receiving a single dose of FB(1) presented variations in Sa and So levels and in the Sa/So ratio.

Validation of fumonisin biomarkers in F344 rats

Fumonisins (FNs) are ubiquitous contaminants of cereal grains. Fumonisin B(1) (FB(1)) was linked to several animal and human diseases. To validate FB(1) biomarkers for studying human disease risks, F344 rats were administered by gavage with either a single dose of 0, 10 or 25 mg FB(1)/kg body weight (BW) or repeated doses of 0, 1.0, or 2.5 mg FB(1)/kg BW/day for 5 weeks. FB(1) excretion and FB(1)-induced metabolic alterations of sphingolipids in rat urine, feces and serum were assessed. Dose-dependent urinary and fecal excretion of free FB(1) were found in both single-dose- and repeat-dose-treated rats. In the single-dose study, urinary sphinganine (Sa) to sphingosine (So) ratio (Sa/So) reached a maximum at day 7 for the high-dose group and at day 5 for the low-dose group, whereas serum Sa/So showed only marginal changes. In the repeat-dose study, urinary Sa/So was persistently elevated at 2 weeks, while serum Sa/So was unchanged. Time course changes of sphinganine 1-phosphate (SaP) and sphingosine 1-phosphate (SoP) were also examined. Although serum Sa/So and SaP/SoP ratios showed no signs of time- or dose-dependent changes, a 10-fold increase in urinary SaP/SoP was observed, suggesting that urinary SaP/SoP is a more sensitive biomarker for FB(1) exposure. The accumulation of SaP and SoP was evident in the time course of SaP/Sa and SoP/So, which may reflect activity changes of enzymes closely related to the metabolism and catabolism of SaP and SoP. These results provide concrete evidence towards the practical use of excreted FB(1), Sa/So and SaP/SoP as biomarkers of exposure to FNs.

Efficacy of royal jelly against the oxidative stress of fumonisin in rats

Fumonisins (FB) are mycotoxins produced by Fusarium verticillioides, frequently associated with corn. It produces toxicity, including teratogenicity, equine leukoencephalomalacia, porcine pulmonary edema, hepatic or renal damage in most animal species and perturb sphingolipid metabolism. The aim of the present study was to evaluate the protective effects of royal jelly (RJ) against FB toxicity. Sixty male Sprague-Dawley rats were divided into six treatment groups including the control group; group fed FB-contaminated diet (200mg/kg diet) and the groups treated orally with RJ (100 or 150mg/kg body weight) with or without FB for 3 weeks. FB alone decreased body weight gain, feed intake, GPX and SOD. Whereas it increased in ALT, AST, triglycerides, cholesterol, HDL, LDL, createnine and uric acid levels. Animals received FB showed severe histological and histochemical changes in liver and kidney tissues. Cotreatment with FB plus RJ resulted in a significant improvement in all the tested parameters and the histological and histochemical pictures of the liver and kidney. These improvements were pronounced in animals fed FB-contaminated diet plus the high dose of RJ. It could be concluded that RJ have a protective effects against FB toxicity and this protection was dose dependent.

Fumonisin B1: Oxidative status and DNA damage in rats

Fumonisin B(1) (FB(1)) is a carcinogenic mycotoxin involved in several animal diseases and assumed to be involved in the etiology of some human tumors. FB(1) disturbs the metabolism of sphinganine (Sa) and sphingosine (So), increasing the ratio of their concentrations (Sa/So). FB(1) is mutagenic in cell cultures, but the mechanism of its genotoxicity is not understood. The aim of this study was to see whether DNA lesions in kidney and liver cells of rats treated with FB(1) were related to the changes in the oxidative status or to the disturbance of the sphingolipid metabolism. Male Wistar rats were receiving either FB(1) (0.5 mg/kg b.w./day, i.p. for 2 or 7 days) or solvent only and were sacrificed 24 h after the last treatment. The ratio of Sa and So concentrations and parameters of oxidative status (catalytic activity of catalase and the concentrations of protein carbonyls and malondialdehyde, MDA) were measured in plasma and liver and kidney homogenates, while DNA damage was measured in liver and kidney using the comet assay. In plasma and liver and kidney homogenates catalase activity and the concentrations of protein carbonyls and MDA were not affected by the 2-day treatment with FB(1), but the ratio of Sa and So in plasma and liver and kidney homogenates was significantly higher than in controls (0.99+/-0.27 versus 0.38+/-0.08, 1.05+/-0.12 versus 0.59+/-0.09 and 4.51+/-0.51 versus 0.54+/-0.17, respectively) (p<0.05). After the 2-day treatment, the tail length and tail intensity measured with the comet assay in the liver homogenate did not change, while in the kidney homogenate, the difference between the treated and control animals was significant in both the tail length (26.4+/-0.7 microm versus 14.6+/-0.1 microm) and tail intensity (8.0+/-0.4% versus 1.7+/-0.02% DNA) (p<0.05). After the 7-day treatment all measured parameters significantly differed from controls (p<0.05). This study showed that FB(1) causes DNA lesions in the kidney of experimental animals before affecting the catalytic activity of catalase and the concentration of protein carbonyls and MDA. The ratio of Sa and So significantly increases in all tissues already after 2-day treatment thus indicating that the metabolism of sphingolipids may have an important role in the DNA damage caused by FB(1).

Evaluation of sphinganine and sphingosine as human breast cancer chemotherapeutic and chemopreventive agents

No comparative study of the effects of sphingolipid metabolites on proliferation and differentiation in normal human breast epithelial cells versus stem cells and tumorigenic cells has been reported. The purpose of this study was to evaluate the chemotherapeutic and chemopreventive potential of sphingoid bases (sphingosine and sphinganine) using a novel cell culture system of normal human breast epithelial cells (HBEC) developed from breast tissues of healthy women obtained during reduction mammoplasty (Type I HBEC with stem cell characteristics and Type II HBEC with basal epithelial cell phenotypes) and transformed tumorigenic Type I HBEC. The results show that sphinganine inhibited the growth and induced apoptosis of transformed tumorigenic Type I HBEC more potently than sphingosine (IC(50) for sphinganine 4 microM; sphingosine 6.4 microM). Both sphinganine and sphingosine at high concentrations (8-10 lM) arrested the cell cycle at G(2)/M. Sphinganine inhibited the growth and caused death of Type I HBEC more strongly than sphingosine. In comparison, Type II HBEC (normal differentiated cells) were less sensitive to the growth-inhibitory effects of sphingoid bases than Type I HBEC (stem cells) or transformed tumorigenic Type I HBEC, suggesting that sphingoid bases may serve as chemotherapeutic agents. At concentrations (0.05, 0.1, and 0.5 microM) that are below the growth-inhibitory range, sphingoid bases induced differentiation of Type I HBEC to Type II HBEC, as detected morphologically and via expression of a tumor suppressor protein, maspin, which is a marker of Type II HBEC. Thus, sphingoid bases may function as chemotherapeutic as well as chemopreventive agents by preferentially inhibiting cancer cells and eliminating stem cells from which most breast cancer cells arise.

Effects of fumonisins on liver and kidney sphinganine and the sphinganine to sphingosine ratio during chronic exposure in ducks

Sa and the Sa/So ratio are very sensitive biomarkers of exposure to fumonisins in several species. We previously demonstrated that increases in Sa and in the Sa/So ratio in serum were less pronounced when ducks ingested fumonisins for more than 7 weeks than when animals were exposed for only 1-2 weeks [S.T. Tran, D. Tardieu, A. Auvergne, J.D. Bailly, R. Babilé, S. Durand, G. Benard, P. Guerre, Serum sphinganine and the sphinganine to sphingosine ratio as biomarker of dietary fumonisins during chronic exposure in ducks, Chem. Biol. Interact., in press]. The aim of this study was to investigate the kinetics of Sa and of the Sa/So in both liver and kidney of ducks that have been previously tested for Sa and the Sa/So ratio in serum. Analysis were performed on treatment days 0, 7, 14, 28 and 77 in five groups of ducks fed fumonisins obtained from an extract of Fusarium verticillioides culture material by daily gavage to obtain an exposure equal to 0, 2, 8, 32 and 128 mg FB1/kg feed. Sa and the Sa/So ratio in tissues were then correlated with Sa and the Sa/So ratio previously obtained in serum. The amounts on sphinganine 1-phosphate (Sa1P) and sphingosine1-phosphate (So1P) in the liver were also investigated. On day 7 of treatment, 2mg/kg FB1 in the feed were sufficient to increase Sa and the Sa/So ratio in liver (by 165 and 148%, respectively) and kidney (by 193 and 104%, respectively). At a rate of 128 mg/kg FB1 in the feed, a very high increase in Sa concentration was observed in both liver and kidney without mortality and/or signs of necrosis (respective increase of 2034 and 3768%). Although the precise mechanism of the resistance of ducks to fumonisin-induced hepatotoxicity is still uncertain, it might be linked to the rate at which the sphingoid bases sphinganine and sphingosine are converted to their 1-phosphate or other metabolite and eliminated from target tissues.

Serum sphinganine and the sphinganine to sphingosine ratio as a biomarker of dietary fumonisins during chronic exposure in ducks

Sphinganine concentration (Sa) and sphinganine to sphingosine ratio (Sa/So) are sensitive biomarkers of fumonisin B1 (FB1) exposure in animals and have been proposed to reveal FB1 exposure in humans. They correlate with liver and kidney toxicity and often precede signs of toxicity. However, the use of Sa and Sa/So is confusing during chronic exposure. Indeed, some authors report altered sphingolipids metabolism, whereas others fail to demonstrate significant effect. The aim of this study was to investigate the kinetics of Sa and Sa/So in the serum of ducks over a 77-day exposure to 0, 2, 8, 32 and 128 mg FB1/kg feeds. Serum biochemistry was also investigated to reveal hepatotoxicity. The results obtained indicate that the kinetics of sphingolipids and serum biochemistry are closely linked with the duration of the exposure. After a strong and rapid increase Sa and Sa/So decrease then stabilize. The lowest investigated dose able to determine a detectable effect is 2 mg/kg feeds, the Sa/So ratio being the most sensitive biomarker of FB1 exposure.

S-adenosylmethionine or 5′-methylthioadenosine are unable to prevent fumonisin B1 hepatotoxicity in mice despite increased oxidation in liver

Fumonisins are mycotoxins produced by the fugus Fusarium verticillioides, a common fungus growing on corn. Fumonisin B(1) (FB(1)) is the most toxic and prevalent fumonisin detected in corn and corn-based foods. It produces species-, gender-specific damage, and is hepatotoxic and nephrotoxic in rodents. Disruption of sphingolipid metabolism resulting from inhibition of ceramide synthase leads to alterations of cell signaling events, particularly tumor necrosis factor (TNF)alpha signal pathways and to the toxic effects of FB(1). It has been reported that FB(1) toxicity involves oxidative stress. S-adenosylmethionine (SAM) and methylthioadenosine (MTA), an intermediate metabolite in SAM metabolism, are hepatoprotective by modulating TNFalpha expression and increasing reduced glutathione (GSH) levels. The current study investigated the effects of SAM and MTA on FB(1) hepatotoxicity in C57BL/6N mice. The animals were given SAM or MTA by intraperitoneal injection of 25 mg kg(-1) body weight every 12 h when they received subcutaneous injection of 2.25 mg FB(1) kg(-1) body weight once daily for 5 days. The results showed that neither SAM nor MTA protected FB(1)-induced liver damage indicated by the increases in activities of plasma alanine aminotransferase and aspartate aminotransferase as well as the number of apoptotic hepatocytes. Both agents prevented an increase of free sphingosine but not sphinganine. Neither SAM nor MTA modified the FB(1)-induced expression of TNFalpha, interleukin (IL)-1alpha or IL-1 receptor antagonist. The decreased GSH in liver following FB(1) treatment was not protected by either agent. The data indicate that SAM and MTA are ineffective in protecting against FB(1) toxic effects.

Individual and Combined Effects of Fusarium moniliforme Culture Material, Containing Known Levels of Fumonisin B1, and Salmonella Gallinarum Infection on Liver of Japanese Quail

Three hundred day-old Japanese quail (Coturnix coturnix japonica) were divided into two groups with 150 quail in each group. One group was maintained on quail mash alone, while Fusarium moniliforme culture material was added to quail mash in the second group from day 5 of age and was supplied at a rate of 150 ppm fumonisin B1 (FB1)/kg mash. At day 21, each group was further subdivided into two groups, yielding four groups with 75 birds apiece, which served as the control (group CX), the Salmonella Gallinarum alone group (group CS), the FB1 alone group (group FX), and the group fed FB1 and infected with Salmonella Gallinarum (group FS). An oral challenge with Salmonella Gallinarum organisms (2 x 10(4) colony-forming units/ml) was given to groups CS and FS at 21 days of age. Three quail each were necropsied on day 21 (0 day interval) from groups CX and FX only. At subsequent intervals (i.e., 1, 2, 3, 5, 7, 10, 14, and 21 days postinfection [DPI]), three quail were euthanatized from all four groups (CX, CS, FX, and FS). The gross and microscopic lesions were recorded in both mortality and euthanatized birds at the above intervals. The ultrastructural studies were done at 5 DPI. Mild to moderate hepatomegaly and pale discoloration of liver were observed in group FX, while congestion, hemorrhages, necrosis, and mild to severe hepatomegaly were the predominant gross lesions in both infected groups (CS and FS). The gross lesions in quail inoculated with Salmonella Gallinarum alone (group CS) generally developed slowly, appeared more widely scattered, and involved comparatively less surface area in contrast to the rapidly progressive and frequently confluent lesions in the combination group (FS), especially in the first 5 days of infection. Mild to marked hepatocellular swelling, multifocal hepatic necrosis, and hepatocellular and bile duct hyperplasia were the characteristic microscopic changes in the FX group. Microscopic lesions in quail of group CS comprised congestion, vacuolar changes, and focal necrosis in early stages, followed by granulomatous lesions at later intervals. Similar but more severe lesions were observed in the combination group (FS). Based on transmission electron microscopy, the maximum effect of FB1 toxicity was observed on mitochondria and endoplasmic reticulum. In general, the mitochondriae showed diverse form and structure, some of which appeared to lose their intact outer membrane, and the mitochondrial cristae were disoriented. The deformity in the cisternae structure of rough endoplasmic reticulum, with their rearrangement into round or tubular forms either bearing granular surface or leading to accumulation of smooth endoplasmic reticulum, was evident only in groups FX and FS. We conclude that the continuous presence of fumonisins in the diets of young quail might increase their susceptibility to or the severity of Salmonella Gallinarum infection.

Myriocin prevents fumonisin B1-induced sphingoid base accumulation in mice liver without ameliorating hepatotoxicity

Fumonisin B(1) (FB(1)), a mycotoxin produced by Fusarium verticillioides present on corn and corn-based products, causes species- and organ-specific diseases. The hepatotoxic effects of FB(1) in mice have been closely correlated with the accumulation of free sphinganine, a marker for ceramide synthase inhibition, and reduced biosynthesis of more complex sphingolipids. It has been shown that FB(1) modulates expression of many cell signaling factors. In the current study we used myriocin, a specific inhibitor of serine palmitoyltransferase, to investigate the role of free sphinganine accumulation in FB(1)-induced hepatotoxicity and increased expression of selected signaling genes in BALB/c mice. The mice were pretreated daily with intraperitoneal injection of 1.0 mg/kg myriocin 30 min before subcutaneous injections of 2.25 mg/kg of FB(1) for 3 days. Results showed that myriocin alone was not hepatotoxic and the combination of myriocin plus FB(1) completely prevented the FB(1)-induced elevation of hepatic free sphinganine and prevented the FB(1)-induced induction of selected cell signaling genes, suggesting that accumulation of free sphinganine and/or its metabolites contribute to the FB(1)-modulation of the cell signaling factors. However, the combination of myriocin and FB(1) did not prevent FB(1)-increased concentration of plasma alanine aminotransferase and only slightly attenuated aspartate aminotransferase; it did not affect the FB(1)-induced hepatocyte apoptosis or increased cell proliferation. A longer combined treatment of myriocin and FB(1) was highly toxic. The hepatotoxic effects in mice seen in this study are most likely due to a combination of factors including accumulation of free sphinganine, depletion of more complex sphingolipids and sphingomyelin, or other unknown mechanisms.