Comparative cytotoxicity of fumonisin B1 and moniliformin in chicken primary cell cultures

Mitophagy-regulated Necroptosis plays a vital role in the nephrotoxicity of Fumonisin B1 in vivo and in vitro

Fumonisin B1 (FB1), one of the most widely distributed mycotoxins found in grains and feeds as contaminants, affects many organs including the kidney once ingested. However, the nephrotoxicity of FB1 remains to be further uncovered. The connection between necroptosis and nephrotoxicity of FB1 has been investigated in this study. The results showed that mice exposed to high doses of FB1 (2.25 mg/kg b.w.) developed kidney damage, with significant increases in proinflammatory cytokines (Il-6, Il-1β), kidney injury-related markers (Ngal, Ntn-1), and gene expressions linked to necroptosis (Ripk1, Ripk3, Mlkl). The concentration-dependent damage effects of FB1 on PK-15 cells contain cytotoxicity, cellular inflammatory response, and necroptosis. These FB1-induced effects can be neutralized by pretreatment with the necroptosis inhibitor Nec-1. Additionally, FB1 caused mitochondrial damage and mitophagy in vivo and in vitro, whereas Mdivi-1, a mitophagy inhibitor, prevented these effects on PK-15 cells as well as, more crucially, necroptosis. In conclusion, the RIPK1/RIPK3/MLKL signal route of necroptosis, which may be controlled by mitophagy, mediated nephrotoxicity of FB1. Our findings clarify the underlying molecular pathways of FB1-induced nephrotoxicity.

Fumonisin B1 Induces Immunotoxicity and Apoptosis of Chicken Splenic Lymphocytes

Fumonisin B₁ (FB₁), produced by Fusarium, is among the most abundant and toxic mycotoxin contaminations in feed, causing damages to the health of livestock. However, the mechanisms of FB₁ toxicity in chickens are less understood. As splenic lymphocytes play important roles in the immune system, the aim of this study was to investigate the immunotoxic effects and mechanisms of FB₁ on chicken splenic lymphocytes. In the present study, the chicken primary splenic lymphocytes were harvested and treated with 0, 2.5, 5, 10, 20 and 40 μg/mL FB₁. Then, the cell proliferation, damage, ultrastructure, inflammation and apoptosis were evaluated. Results showed that the proliferation rate of splenic lymphocytes was decreased by FB₁ treatments. The activity of lactate dehydrogenase (LDH) was increased by FB₁ treatments in a dose-dependent manner, implying the induction of cell damage. Consistently, the ultrastructure of splenic lymphocytes showed that FB₁ at all the tested concentrations caused cell structure alterations, including nuclear vacuolation, mitochondrial swelling and mitochondrial crest fracture. Besides, immunosuppressive effects of FB₁ were observed by the decreased concentrations of interleukin-2 (IL-2), IL-4, IL-12 and interferon-γ (IFN-γ) in the cell culture supernatant. Furthermore, apoptosis was observed in FB₁-treated cells by flow cytometry. The mRNA expressions of apoptosis-related genes showed that the expression of Bcl-2 was decreased, while the expressions of the P53, Bax, Bak-1, and Caspase-3 were increased with FB₁ treatment. Similar results were found in the concentrations of apoptosis-related proteins in the cell supernatant by ELISA assay. Moreover, regression analysis indicated that increasing FB₁ concentration increased LDH activity, concentrations of Bax, Bak-1 and mRNA expression of Bak-1 linearly, increased M1 area percentage quadratically, decreased concentration of IFN-γ, mRNA expression of Bcl-2 linearly, and decreased concentrations of IL-2 and IL-4 quadratically. Besides, regression analysis also showed reciprocal relationships between IL-12 concentration, Caspase-3 mRNA expression and increasing FB₁ concentration. The increasing FB₁ concentration could decrease IL-12 concentration and increase Caspase-3 mRNA expression. Altogether, this study reported that FB₁ induced the immunotoxicity of chicken splenic lymphocytes and caused splenic lymphocytes apoptosis by the Bcl-2 family-mediated mitochondrial pathway of caspase activation.

Emerging Mycotoxins: Beyond Traditionally Determined Food Contaminants

Modern analytical techniques can determine a multitude of fungal metabolites contaminating food and feed. In addition to known mycotoxins, for which maximum levels in food are enforced, also currently unregulated, so-called "emerging mycotoxins" were shown to occur frequently in agricultural products. The aim of this review is to critically discuss the relevance of selected emerging mycotoxins to food and feed safety. Acute and chronic toxicity as well as occurrence data are presented for enniatins, beauvericin, moniliformin, fusaproliferin, fusaric acid, culmorin, butenolide, sterigmatocystin, emodin, mycophenolic acid, alternariol, alternariol monomethyl ether, and tenuazonic acid. By far not all of the detected compounds are toxicologically relevant at their naturally occurring levels and are therefore of little or no health concern to consumers. Still, gaps in knowledge have been identified for several compounds. These gaps should be closed by the scientific community in the coming years to allow a proper risk assessment.

Effect of Fusarium-Derived Metabolites on the Barrier Integrity of Differentiated Intestinal Porcine Epithelial Cells (IPEC-J2)

The human, animal and plant pathogen Fusarium, which contaminates agricultural commodities worldwide, produces numerous secondary metabolites. An example is the thoroughly-investigated deoxynivalenol (DON), which severely impairs gastrointestinal barrier integrity. However, to date, the toxicological profile of other Fusarium-derived metabolites, such as enniatins, beauvericin, moniliformin, apicidin, aurofusarin, rubrofusarin, equisetin and bikaverin, are poorly characterized. Thus we examined their effects—as metabolites alone and as metabolites in combination with DON—on the intestinal barrier function of differentiated intestinal porcine epithelial cells (IPEC-J2) over 72 h. Transepithelial electrical resistance (TEER) was measured at 24-h intervals, followed by evaluation of cell viability using neutral red (NR) assay. Enniatins A, A1, B and B1, apicidin, aurofusarin and beauvericin significantly reduced TEER. Moniliformin, equisetin, bikaverin and rubrofusarin had no effect on TEER. In the case of apicidin, aurofusarin and beauvericin, TEER reductions were further substantiated by the addition of otherwise no-effect DON concentrations. In all cases, viability was unaffected, confirming that TEER reductions were not due to compromised viability. Considering the prevalence of mycotoxin contamination and the diseases associated with intestinal barrier disruption, consumption of contaminated food or feed may have substantial health implications.

Health effects of moniliformin: a poorly understood Fusarium mycotoxin

The contamination of the food and feed chain with mycotoxins and the subsequent threat to human health and animal welfare is evident. Today mycotoxin research is still strongly focused on mycotoxins such as aflatoxins, ochratoxin A and for Fusarium fungi mainly the trichothecenes deoxynivalenol (DON) and T-2 and HT-2 toxins. However, fungi of the Fusarium genus are clearly capable of synthesising other mycotoxins as well, including moniliformin (MON). The occurrence of MON is worldwide and the levels in grains vary from below the limit of quantification to the highest detected value in maize intended for human consumption being close to 20 mg/kg. In Finland and Norway, the reported levels are typically a few hundreds of micrograms per kilogram. The toxicology of MON is not well understood. It is characterised by major species differences but typically MON evokes myocardiac damage. For MON, No Observed Adverse Effect Level (NOAEL) has not been established and a provisional Tolerable Daily Intake (pTDI) value has not been proposed. In our risk assessment, we applied a NOAEL value of 10 mg/kg bw/day which is based on our unpublished subchronic exposure experiments. By applying this value in the risk assessment combined with the estimated intakes from food in Finland and Norway, it seems that MON per se does not pose a clear threat to human health at current levels. On the other hand, one needs to bear in mind the concurrent exposure to other mycotoxins and the fact that the risk assessment of mycotoxin mixtures are in their infancy.

Effects of aflatoxin B(1) and fumonisin B(1) on the viability and induction of apoptosis in rat primary hepatocytes

The present study evaluated the effect of aflatoxin B(1) (AFB(1)) and fumonisin B(1) (FB(1)) either alone, or in association, on rat primary hepatocyte cultures. Cell viability was assessed by flow cytometry after propidium iodine intercalation. DNA fragmentation and apoptosis were assessed by agarose gel electrophoresis and acridine orange and ethidium bromide staining. At the concentrations of AFB(1) and FB(1) used, the toxins did not decrease cell viability, but did induce apoptosis in a concentration and time-dependent manner.

Mycotoxins and skeletal problems in poultry

Bone problems are a major threat in meat-type and breeder poultry globally, raising both welfare and economic concerns. Leg weakness is multifactorial in origin and can be influenced by management, genetics, environment, nutrition and mycotoxins. Various mycotoxins, singly and severally, are known to exert an adverse effect on bone metabolism leading to leg weakness. Leg weakness in poultry as caused by mycotoxins and its alleviation is reviewed.

Evaluation of the genotoxicity of Fusarium mycotoxin moniliformin in human peripheral blood lymphocytes

Mycotoxins are fungal secondary metabolites that can be found in contaminated food and feed. There is some evidence to suggest that certain mycotoxins may be mutagenic. Here, we investigate the genotoxicity of the mycotoxin moniliformin (MON) (3-hydroxycyclobut-3-ene-1,2-dione) in human peripheral blood lymphocytes using chromosomal aberration (CA), sister-chromatid exchange (SCE), and micronucleus (MN) analysis. Lymphocyte cultures were treated for 48 h with six different concentrations of MON between 2.5 and 25 microM. CA, SCE, and MN frequencies were significantly increased in a dose-dependent manner compared with the negative control. The mitotic, replication, and cytokinesis-block proliferation indices were not affected by treatment with MON. The results provide evidence to demonstrate that MON can exert cytogenetic effects in human cells in culture.

Analysis of moniliformin in maize plants using hydrophilic interaction chromatography

A novel HPLC method was developed for detection of the Fusarium mycotoxin, moniliformin in whole maize plants. The method is based on hydrophilic interaction chromatography (HILIC) on a ZIC zwitterion column combined with diode array detection and negative electrospray mass spectrometry (ESI(-)-MS). Samples were extracted using acetonitrile-water (85:15), and the extracts were cleaned up on strong anion exchange columns. By this procedure we obtained a recovery rate of 57-74% moniliformin with a limit of detection at 48 ng/g and a limit of quantification at 96 ng/g using UV detection at 229 nm, which is comparable to current methods used. Limit of detection and quantification using ESI(-)-MS detection was 1 and 12 ng/g, respectively. Screening of maize samples infected with the moniliformin producing fungi F. avenaceum, F. tricinctum, or F. subglutinans detected moniliformin levels of 1-12 ng/g in 15 of 28 samples using ESI(-)-MS detection. To our knowledge this is the first example of HILIC separation in mycotoxin analysis.

The Effects of Fumonisin B1 on viability and mitogenic response of avian immune cells

Fumonisin B1 (FB1) is a mycotoxin produced by the fungus Fusarium verticillioides (formerly Fusarium moniliforme) and is found in diverse crops such as corn, wheat, and barley. Many diseases linked to FB1, such as porcine pulmonary edema, rat hepatic cancer, and equine leukoencephalomalacia, indicate a compromised immune system. The purpose of this study was to determine whether FB1 altered immunological responses in various cell populations of Single Comb White Leghorn chicks. Cells collected for this study were obtained from those immunological organs with well-defined responses (i.e., spleen, thymus, and blood). Cell populations were exposed to 5 to 50 microg/mL FB1 in vitro for 24 to 72 h, and viability and mitogenic response were evaluated. The effects of FB1 on the mitogenic response were evaluated in cell populations from the spleen and blood stimulated with the mitogens, lipopolysaccharide, concanavalin A, and pokeweed mitogen and in thymocytes stimulated with concanavalin A. The 3-(4,5-dimethylthazol-2-yl)-diphenyl-2H-tetrazolium bromide (MTT) reduction assay was used to assess viability and mitogenic response. Fumonisin B1 decreased spleen cell viability and mitogenic response, albeit the degree of decrease varied with mitogen and time of exposure. Fumonisin B1 increased number of viable thymic cells at 50 microg/mL but had no effect on the mitogenic response of thymocytes. Fumonisin B1 had no effect on blood lymphocyte viability or mitogenic response.

Effects of moniliformin in presence of cyclohexadepsipeptides on isolated mammalian tissue and cells

Secondary metabolites produced by Fusarium spp. including beauvericin, enniatin and moniliformin are mycotoxins identified in cereal samples. The two cyclohexadepsipeptide mycotoxins beauvericin and enniatin have cytotoxic, antibiotic, insecticidal and ionophoric properties, while moniliformin primarily acts as a cardiotoxic mycotoxin. In this study, we examined the electromechanical and electrophysiological effects of moniliformin and moniliformin with ionophoric mycotoxins on cells (ventricular myocytes, Caco-2 cells) and in multicellular preparations (papillary muscles and terminal ilea of the guinea pig). Additionally, we investigated the influence of moniliformin on cell homeostasis in absence and presence of the cyclodepsipeptide mycotoxins (ventricular myocytes, Caco-2 cells). Experiments were performed using isometric measurements of contractility, intracellular microelectrode and patch-clamp techniques, and fluorescence imaging. While ionophoric cyclohexadepsipeptides affect action potential parameters and cell homeostasis, moniliformin did not change spontaneous rates of activity or cardiac action potentials. Furthermore, moniliformin had no effect on intracellular concentrations of ions and ATP, and did not affect pH. Moniliformin reduced contractility in papillary muscle, terminal ileum, the aorta and the pulmonary artery. However, moniliformin did not alter beauvericin and enniatin induced effects. From our studies, we conclude that moniliformin is not solely a cardiotoxic secondary metabolite, but also exerts its effects on smooth muscle. Moreover, there is no synergistic relationship between moniliformin and the concurrently produced cyclohexadepsipeptide mycotoxins beauvericin and enniatin.

Cytotoxicity of Fusarium mycotoxins to mammalian cell cultures as determined by the MTT bioassay

Fusarium mycotoxins occur worldwide in cereal grains and animal feeds and cause outbreaks of Fusarium mycotoxicoses in humans and animals. In this study mammalian cell cultures were used to screen the cytotoxicity of the most common Fusarium mycotoxins; deoxynivalenol (DON), zearalenone (ZEN), fumonisin B(1) (FB(1)) and moniliformin (MON). The most sensitive cell line for each Fusarium mycotoxin was determined for further toxicological investigations as an alternative to whole animal testing. Chinese hamster ovary cells (CHO-K1) were found to be the most sensitive for DON and FB(1) with IC(50) values of 0.27 and 85.5 microg/ml, respectively, after 48-h exposure. The hepatocellular carcinoma cells (HepG2) showed the highest sensitivity to MON with IC(50) values of 39.5 for 48 h and 26.8 microg/ml for 72-h exposure. Balb/c mice keratinocyte cell line (C5-O) was found to be the most sensitive to ZEN with IC(50) of 24.1 microg/ml after 72-h exposure. DON was found the most cytotoxic to the cell cultures of all the mycotoxins tested, followed by MON, ZEN, and FB(1). The results indicated that CHO-K1, C5-O, and HepG2 cells were found to be the sensitive cell lines for preliminary screening of DON, ZEN and MON contaminated feed and food extracts, respectively.

Moniliformin in Norwegian grain

Norwegian grain samples (73 oats, 75 barley, 83 wheat) from the 2000-02 growing seasons were examined for contamination with moniliformin, and the association between the fungal metabolite and the number of kernels infected with common Fusaria was investigated. Before quantification of moniliformin using ion pairing reversed-phase high-performance liquid chromatography with diode array ultraviolet light detection, all samples were extracted using acetonitrile/water (84/16) and disposable strong anion exchange columns used for clean up. The limit of detection was 40 microg kg(-1). Moniliformin was found in 25, 32 and 76% of the barley, oats and wheat samples, respectively. The maximum concentrations of moniliformin in barley, oats and wheat were 380, 210 and 950 microg kg(-1), respectively. At the same time, the prevalence and infection level of the moniliformin-producing F. avenaceum/arthrosporioides was as high as 100 and >53% on average, respectively. Moniliformin concentrations were significantly correlated to the variables grain species, growing season and infection with F. avenaceum/arthrosporioides and F. culmorum. The survey indicates that the prevalence of moniliformin in Norwegian grain is high, especially in wheat. On the other hand, field conditions in Norway do not seem to favour contamination of grain with high levels of moniliformin.

Cytotoxicity assays for mycotoxins produced by Fusarium strains: a review

Mycotoxins are naturally occurring toxic secondary metabolites of fungi that may be present in food and feed. Several of these mycotoxins have been associated with human and animal diseases. Fusarium species, found worldwide in cereals and other food types for human and animal consumption, are the most important toxigenic fungi in northern temperate regions. The overall economical loss and the detrimental health effects in humans and animals of mycotoxin contamination are enormous and therefore, rapid screening methods will form an important tool in the protection of humans and animals as well as to minimize economical losses by early detection. An overview of methods for the determination of cytotoxicity and the application of such bioassays to screen solid fungal cultures, cereals, respectively, food/feedstuffs for the presence and toxic potential of Fusarium mycotoxins is presented. Various cell lines including different endpoints of toxicity using vertebrate cells and the predictive value of the in vitro assays are reviewed. Bioassays are compared with existing chemical analytical methods and the possibilities and limitations of such systems are discussed. The review is based on 149 references.

Correlation of moniliformin, but not fumonisin B1 levels, in culture materials of Fusarium isolates to acute death in ducklings

Five isolates of Fusarium moniliforme and two isolates Fusarium proliferatum of the Section Liseola were each fermented on rice for 21 d at 25 C. Each Fusarium-fermented rice, when dried and mixed into a poultry diet (10% by weight), caused a varied degree of acute mortality in baby Pekin ducklings. The acute (death in less than 48 h) mortality correlated significantly only to the amount of moniliformin in fermented rice, thus in the diet, but not to the amount of fumonisin B1 in fermented rice. This correlation of moniliformin concentration and noncorrelation of fumonisin B1 concentrations to acute toxicity were confirmed by duckling assay using diets containing these purified mycotoxins.