Modulating effects of fumonisin B1 and ochratoxin A on leukocytes and messenger cytokines of the human immune system

The multiple biotoxicity integrated study in grass carp (Ctenopharyngodon idella) caused by Ochratoxin A: Oxidative damage, apoptosis and immunosuppression

Ochratoxin A (OTA) is a common hazardous food contaminant that seriously endangers human and animal health. However, limited study is focused on aquatic animal. This research investigated the multiple biotoxicity of OTA on spleen (SP) and head kidney (HK) in grass carp and its related mechanism. Our data showed that, dietary supplemented with OTA above 1209 μg/kg caused histopathological damages by decreasing the number of lymphocytes and necrotizing renal parenchymal cells. Meanwhile, OTA caused oxidative damage and reduced the isoforms mRNAs transcripts of antioxidant enzymes (e.g., GPX1, GPX4, GSTO) partly due to suppressing NF-E2-related factor 2 (Nrf2). OTA triggered apoptosis through mitochondria and death receptor pathway potentially by p38 mitogen-activated protein kinase (p38MAPK) activation. Besides, OTA exacerbated inflammation by down-regulation of anti-inflammatory factor (e.g., IL-10, IL-4) and up-regulations of pro-inflammatory factors (e.g., TNF-α, IL-6), which could be ascribed to signaling meditation of Janus kinase / signal transducer and activator of transcription (JAK/STAT). Additionally, the safe upper limits of OTA were estimated to be 677.6 and 695.08 μg/kg based on the immune-related indexes (C3 contents in the SP and LZ activities in the HK, respectively). Our study has provided a wide insight for toxicological assessment of feed pollutant in aquatic animals.

Ochratoxin A and Kidney Oxidative Stress: The Role of Nutraceuticals in Veterinary Medicine-A Review

The problem of residues of toxic contaminants in food products has assumed considerable importance in terms of food safety. Naturally occurring contaminants, such as mycotoxins, are monitored routinely in the agricultural and food industries. Unfortunately, the consequences of the presence of mycotoxins in foodstuffs are evident in livestock farms, where both subacute and chronic effects on animal health are observed and could have non-negligible effects on human health. Ochratoxin A (OTA) is a common mycotoxin that contaminates food and feeds. Due to its thermal stability, the eradication of OTA from the food chain is very difficult. Consequently, humans and animals are frequently exposed to OTA in daily life. In this review article, we will devote time to highlighting the redox-based nephrotoxicity that occurs during OTA intoxication. In the past few decades, the literature has improved on the main molecules and enzymes involved in the redox signaling pathway as well as on some new antioxidant compounds as therapeutic strategies to counteract oxidative stress. The knowledge shown in this work will address the use of nutraceutical substances as dietary supplements, which would in turn improve the prophylactic and pharmacological treatment of redox-associated kidney diseases during OTA exposure, and will attempt to promote animal feed supplementation.

Molecular and epigenetic modes of Fumonisin B1 mediated toxicity and carcinogenesis and detoxification strategies

Fumonisin B₁ (FB₁) is a natural contaminant of agricultural commodities that has displayed a myriad of toxicities in animals. Moreover, it is known to be a hepatorenal carcinogen in rodents and may be associated with oesophageal and hepatocellular carcinomas in humans. The most well elucidated mode of FB₁-mediated toxicity is its disruption of sphingolipid metabolism; however, enhanced oxidative stress, endoplasmic reticulum stress, autophagy, and alterations in immune response may also play a role in its toxicity and carcinogenicity. Alterations to the host epigenome may impact on the toxic and carcinogenic response to FB₁. Seeing that the contamination of FB₁ in food poses a considerable risk to human and animal health, a great deal of research has focused on new methods to prevent and attenuate FB₁-induced toxic consequences. The focus of the present review is on the molecular and epigenetic interactions of FB₁ as well as recent research involving FB₁ detoxification.

Fungicidal Impact of Salvadora Persica L. (Miswak) Extract on Growth of Foodborne Pathogens, Aspergillus Species

Several investigations have focused on studying the suppressing influence of Salvadora persica (miswak) on oral microbes; however, studies regarding its fungicidal activity versus human aspergillosis-related illness are still scarce. The current research was designed to evaluate the fungicidal action of S persica aquatic root extract in terms of radial growth rate and inhibition zone (IZO) versus 3 pathogenic Aspergillus species, namely, A niger, A flavus, and A fumigatus in vitro. The results revealed that the plant extract (50 and 100 mg/mL) exhibited a prohibiting influence on the growth of the tested fungal species. The high concentration (100 mg/mL) of the plant extract was efficient in prohibiting the growing rate of the tested Aspergillus species after 6 days exposure period. Aspergillus niger and A flavus showed the largest inhibition ratios (60% and 54.4%, respectively) and IZO (33.00 ± 0.05 mm and 25.50 ± 0.18 mm, respectively) versus the control counterparts. Aspergillus fumigatus showed the minimum inhibition ratio (39%) and IZO (20.31 ± 0.05). The present data showed that the extract of S persica possesses potential fungicidal influence versus the tested pathogenic Aspergillus species and this may support the utilization of this extract as a promising antifungal agent versus aspergillosis.

Protective Role of Selenium in Immune-Relevant Cytokine and Immunoglobulin Production by Piglet Splenic Lymphocytes Exposed to Deoxynivalenol

Deoxynivalenol (DON) is a mycotoxin that causes immunosuppression, especially in swine. Selenium (Se) is essential for proper functioning of the immune system in animals. However, little is known about the effects of DON and Se on cytokine or immunoglobulin production in piglets. Here, we addressed this gap by examining piglet splenic lymphocyte responses in vitro. Cells were stimulated with concanavalin A, a T cell stimulatory lectin, in the absence or presence of DON (0.1, 0.2, 0.4, and 0.8 μg/mL), Se (Na₂SeO₃, 2 μM), or combinations of Se 2 μM and DON 0.1-0.8 μg/mL for 12, 24, or 48 h. At each time point, supernatants and cells were collected and the expression of cytokine and immunoglobulin protein and mRNA was examined. Compared with control and Se-alone treatments, DON exposure significantly and dose dependently decreased the expression levels of IL-2, IL-4, IL-6, IL-10, IFN-γ, IgG, and IgM mRNA and protein. By contrast, co-treatment with DON + Se significantly increased the mRNA and protein levels of all factors examined, except IL-4 and IL-6, compared with DON treatment alone. The results of this investigation demonstrate that Se has the potential to counteract DON-induced immunosuppression in piglets and is a promising treatment for DON-mediated toxicity.

Magneto-controlled aptasensor for simultaneous electrochemical detection of dual mycotoxins in maize using metal sulfide quantum dots coated silica as labels

Currently there is an urgent need for multi-mycotoxin detection methods due to the co-occurrence of multiple mycotoxins in food raw materials and their augmented toxicity. Herein, a magneto-controlled aptasensor has been developed for simultaneous electrochemical detection of ochratoxin A (OTA) and fumonisin B1 (FB1), two typical mycotoxins found in food crops world-wide. This aptasensor was designed using the high specificity between the target and aptamer with heavy CdTe or PbS quantum dots (QDs) coated silica as labels and the complementary DNA functionalized magnetic beads as capture probes. In presence of targets, the aptamer preferred to form the target-aptamer binding which forced the partial release of the preloaded labels from the magnetic beads. After a one-step incubation and a simple magnetic separation, the electrochemical signals of Cd²⁺ and Pb²⁺ dissolved from the reserved labels which had negative correlation with targets contents, was measured based on the difference of peak potentials. This aptasensor provided a wide detection range of 10pgmL^-1 to 10ngmL^-1 for OTA and 50pgmL^-1 to 50ngmL^-1 for FB1, and succeeded in real maize samples. This method provides a new avenue for high throughput screen of mycotoxins due to the advantages of simple instrument, low sample consumption, short assay times, and lower detection costs per assay. Moreover, it could be readily expanded for the simultaneous detection of a large panel of mycotoxins by using different metal sulfide QDs when their specific aptamers are available.

Fusarium proliferatum strains change fumonisin biosynthesis and accumulation when exposed to host plant extracts

Fumonisin concentrations in mycelia and media were studied in liquid Fusarium proliferatum cultures supplemented with host plant extracts. Furthermore, the kinetics of fumonisin accumulation in media and mycelia collected before and after extract addition was analysed as well as the changes in the expression of the FUM1 gene. Fumonisin content in culture media increased in almost all F. proliferatum strains shortly after plant extracts were added. The asparagus extract induced the highest FB level increase and the garlic extract was the second most effective inducer. Fumonisin level decreased constantly until 14th day of culturing, though for some strains also at day 8th an elevated FB level was observed. Pineapple extract induced the highest increase of fum1 transcript levels as well as fumonisin synthesis in many strains, and the peas extract inhibited fungal growth and fumonisin biosynthesis. Moreover, fumonisins were accumulated in mycelia of studied strains and in the respective media.

In vitro effect of ochratoxin A and deoxynivalenol on the expression of interleukin 5 and interferon-gamma in broiler chicken lymphocytes

Cytokines are proteins secreted by cells of innate and acquired immunity, produced in response to various antigens and responsible for mediating several function of these cells. Our study evaluated the profile of cytokines interleukin 5 (IL-5) and interferon gamma (IFN-γ), induced in lymphocytes of broiler chickens in response to secondary fungal metabolites ochratoxin A (OTA) and deoxynivalenol (DON) at concentrations of 0.001, 0.01, 0.1 and 1 μg/ml. The quantification of the cytokines was analysed at 24, 48 and 72 h after incubation with mycotoxins, using real-time PCR (qRT-PCR). The results obtained showed that OTA induced mRNA synthesis of IL-5 at concentrations 0.001, 0.1 and 1 μg/ml after 24 h of lymphocyte incubation, while at 48 h only the expression of the IL-5 cytokine at a concentration of 1 μg/ml (P<0.05) was detected. DON in a concentration of 1 μg/ml induced the expression of IL-5 in the lymphocytes only at 48 h post-incubation period (P<0.05). Regarding IFN-γ, gene expression was not observed in the lymphocytes of broiler chickens incubated with OTA and DON. The data obtained represent a profile of response mediated by T helper 2 cells to the exposure of broiler chicken immune cells to different concentrations of OTA and DON.

Polyphenols as possible bioprotectors against cytotoxicity and DNA damage induced by ochratoxin A

The present study aimed to investigate the protective effects of luteolin (L), chlorogenic acid (ChlA) and caffeic acid (CafA) against cyto-genotoxic effects caused by OTA. Vero cells and rat lymphocytes were used and viability was measured by neutral red uptake, MTT and trypan blue dye exclusion method. L (50 and 100μg/mL), ChlA (100 and 200μg/mL) and CafA (10-50μg/mL) reduced the damage induced by OTA (10μg/mL) on both cells type shown a good protective effect. The comet and micronucleus tests in Balb/c mice were performed. ChlA (10mg/kg bw) reduced OTA (0.85mg/kg bw)-induced DNA damage on blood and bone marrow cells, CafA (10mg/kg bw) showed protective effect only in blood cells and luteolin (2.5mg/kg bw) failed to protect DNA integrity on cells. In conclusion, polyphenols tested reduced the toxicity caused by OTA on different target cells with good protective effect, being ChlA the compound that showed the best effects.

Modulation of innate and antigen-specific immune functions directed against Listeria monocytogenes by fungal toxins in vitro

Mycotoxins, a large group of secondary fungal metabolites, are ubiquitously present in the environment and are potentially harmful to exposed humans and animals. Despite increasing interest in this group of fungal metabolites it is still difficult to estimate the relative toxic potential of one individual mycotoxin compared with others. We therefore compared the effects of some of the most important mycotoxins on effector cells of the innate and adaptive immune system in an in vitro model. Our data show clear differences of various mycotoxins in regard of their immunotoxic potential on mouse macrophages and T cells. Our results also indicate differences in the susceptibility of specific immune effector functions of macrophages and T cells exposed to mycotoxins. Thus, our results enhance the understanding of role of mycotoxins in the pathogenesis of human and animal diseases.

Regulation of IL-8 promoter activity by verrucarin A in human monocytic THP-1 cells

Macrocyclic trichothecenes have been frequently detected in fungi in water-damaged buildings and exhibited higher toxicity than the well-studied trichothecenes; however, the mechanism underlying their toxicity has been poorly understood. In this study, transcriptional regulation of the cytokine interleukin (IL)-8 by a macrocyclic trichothecene, verrucarin A (VA), in human monocytic THP-1 cells is reported. Consistent with previous findings, VA was 100-fold more cytotoxic than deoxynivalenol (DON), while ochratoxin A (OA) was not cytotoxic. In cells transduced with the wild-type IL-8 promoter luciferase construct, VA induced a biphasic dose response composed of an upregulation of luciferase expression at low concentrations of 0.01-1 ng/ml and a downregulation at high levels of 10 ng/ml and higher. In contrast, DON induced a sigmoid-shaped dose response with the EC50 of 11.6 ng/ml, while OA did not markedly affect the IL-8 expression. When cells were transduced with IL-8 promoter with a mutation of transcription factor nuclear factor-κB (NF-κB)-binding site, VA (1 ng/ml), DON (1000 ng/ml), and tumor necrosis factor (TNF) α (20 ng/ml)-induced luciferase expression were impaired. In addition, the NF-κB inhibitor caffeic acid phenethyl ester inhibited VA-, DON-, and TNFα-induced luciferase expression. Mutation of the CCAAT/enhancer-binding protein (CEBP) β binding site of the IL-8 promoter affected only DON-, but not VA- and TNFα-induced luciferase expression. Taken together, these results suggested that VA activated IL-8 promoter via an NF-κB-dependent, but not CEBPβ-dependent, pathway in human monocytes.

Application of mimotope peptides of fumonisin b1 in Peptide ELISA

Anti-fumonisin B(1) (FB(1)) McAb 1D11 was used as the target for biopanning from a phage random loop-constrained heptapeptide library. After three cycles of panning, seven phages with three mimotope peptides were selected to mimic the binding of FB(1) to 1D11. After the identification of phage ELISA, the phage clone that showed the best linear range of detection was chosen for further research. One peptide with the inserted peptide sequence of the phage was synthetized, named CT-452. An indirect competitive ELISA (peptide ELISA) for detecting FB(1) was established using the CT-452-bovine serum albumin conjugate as coating antigen. The linear range of the inhibition curve was 1.77-20.73 ng/mL. The half inhibitory concentration (IC50) was 6.06 ng/mL, and the limit of detection was 1.18 ng/mL. This method was compared with conventional indirect ELISA (commercial ELISA kit) and high-performance liquid chromatography (HPLC), and the results showed the reliability of the peptide ELISA for the determination of FB(1) in cereal samples. The relationship between the CT-452 and FB(1) standard concentrations in peptide ELISA was evaluated. The results indicated that synthetic peptide CT-452 can replace the FB(1) standard to establish an immunoassay free of FB(1).

[Determination of fumonisins B1 and B2 in corn by high performance liquid chromatography with post-column derivatization method]

A high performance liquid chromatography-fluorescence detection with post-column derivatization method was developed to detect fumonisin B1 (FB1) and fumonisin B2 (FB2) in corn. Several factors, such as the pH of derivatization buffer, concentration and flow rate of derivatization reagents, excitation wavelength, emission wavelength, which affected the detection of fumonisins were optimized. The separation was performed on a ZORBAX SB C18 column operated at 40 degrees C with the gradient elution by two mobile phases of 0.1 mol/L sodium dihydrogen phosphate solution (pH 3.3) and methanol at a flow rate of 0.8 mL/min. The derivatization was performed at ambient temperature. The o-phthalaldehyde (OPA) flow rate was 0.4 mL/min. The results showed that the optimum conditions were pH 10.5 of the derivatization reagent, OPA concentration at 2 g/L, and excitation wavelength of 335 nm, emission wavelength of 440 nm. The linear plots of FB1 and FB2 were obtained between 0.2 to 20 mg/L, with the correlation coefficients above 0.999 for both FB1 and FB2. The limits of detection of fumonisins B1 and B2 were 0.02 mg/kg. The mean recoveries at the three spiked levels of 0.1 - 4.0 mg/kg were 82.5% - 89.8%. This method is accurate, simple, rapid and suitable for the determination of fumonisins B1 and B2 in corn.

Fluorescence spectroscopic investigation of competitive interactions between ochratoxin A and 13 drug molecules for binding to human serum albumin

Ochratoxin A (OTA) is a highly toxic mycotoxin found worldwide in cereals, foods, animal feeds and different drinks. Based on previous studies, OTA is one of the major causes of the chronic tubulointerstitial nephropathy known as Balkan endemic nephropathy (BEN) and exerts several other adverse effects shown by cell and/or animal models. It is a well-known fact that OTA binds to various albumins with very high affinity. Recently, a few studies suggested that reducing the bound fraction of OTA might reduce its toxicity. Hypothetically, certain drugs can be effective competitors displacing OTA from its albumin complex. Therefore, we examined 13 different drug molecules to determine their competing abilities to displace OTA from human serum albumin (HSA). Competitors and ineffective chemicals were identified with a steady-state fluorescence polarization-based method. After characterization the competitive abilities of individual drugs, drug pairs were formed and their displacing activity were tested in OTA-HSA system. Indometacin, phenylbutazone, warfarin and furosemide showed the highest competing capacity but ibuprofen, glipizide and simvastatin represented detectable interaction too. Investigations of drug pairs raised the possibility of the presence of diverse binding sites of competing drugs. Apart from the chemical information obtained in our model, this explorative research might initiate future designs for epidemiologic studies to gain further in vivo evidence of long-term (potentially protective) effects of competing drugs administered to human patients.

Lactobacillus reuteri CRL 1098 and Lactobacillus acidophilus CRL 1014 differently reduce in vitro immunotoxic effect induced by Ochratoxin A

Ochratoxin A (OTA) is a widespread mycotoxin contaminating several food products which causes detrimental health effects. The ability of Lactobacillus reuteri CRL 1098 and Lactobacillus acidophilus CRL 1014 to prevent OTA effects on TNF-α and IL-10 production and apoptosis induction in human peripheral blood mononuclear cells (PBMC) was investigated. Membrane rafts participation in these responses was also evaluated. L. reuteri reduced by 29% the OTA inhibition of TNF-α production whereas L. acidophilus increased 8 times the TNF-α production by OTA treated-PBMC. Also, both bacteria reversed apoptosis induced by OTA by 32%. However, neither of the bacteria reversed the OTA inhibition on IL-10 production. On the other hand, the lactobacilli were less effective to reverse OTA effects on disrupted-rafts PBMC. This study shows that two lactobacilli strains can reduce some negative OTA effects, being membrane rafts integrity necessary to obtain better results. Also, the results highlight the potential capacity of some lactobacilli strains usually included in natural dietary components in milk-derived products and cereals feed, to reduce OTA toxicity once ingested by humans or animals.

Generation of a highly reactive chicken-derived single-chain variable fragment against Fusarium verticillioides by phage display

Fusarium verticillioides is the primary causal agent of Fusarium ear and kernel rot in maize, producing fumonisin mycotoxins that are toxic to humans and domestic animals. Rapid detection and monitoring of fumonisin-producing fungi are pivotally important for the prevention of mycotoxins from entering into food/feed products. Chicken-derived single-chain variable fragments (scFvs) against cell wall-bound proteins from F. verticillioides were isolated from an immunocompetent phage display library. Comparative phage enzyme-linked immunosorbant assays (ELISAs) and sequencing analyses identified four different scFv antibodies with high sensitivity. Soluble antibody ELISAs identified two highly sensitive scFv antibodies, FvCA3 and FvCA4, with the latter being slightly more sensitive. Three-dimensional modeling revealed that the FvCA4 may hold a better overall structure with CDRH3, CDRL1 and CDRL3 centered in the core region of antibody surface compared with that of other scFvs. Immunofluorescence labeling revealed that the binding of FvCA4 antibody was localized to the cell walls of conidiospores and hyphae of F. verticillioides, confirming the specificity of this antibody for a surface target. This scFv antibody was able to detect the fungal mycelium as low as 10(-2) μg/mL and contaminating mycelium at a quantity of 10(-2) mg/g maize. This is the first report that scFv antibodies derived from phage display have a wide application for rapid and accurate detection and monitoring of fumonisin-producing pathogens in agricultural samples.

Toxicology of mycotoxins

Humans are exposed to mycotoxins via ingestion, contact and inhalation. This must have occurred throughout human history and led to severe outbreaks. Potential diseases range from akakabio-byo to stachybotryotoxicosis and cancer. The known molecular bases of toxicology run the gamut of 23 compounds, from aflatoxins (AFs) to zearalenone, ochratoxin A and deoxynivalenol. Ergotism is one of the oldest recognized mycotoxicosis, although mycotoxin science only commenced in the 1960s with the discovery of AFs in turkey feed. AFs are carcinogenic. Some others are suspected carcinogens. The effects of mycotoxins are acute or chronic in nature. Mycotoxins are well known in the scientific community, although they have a low profile in the general population. An incongruous situation occurs in United States where mycotoxins from "moldy homes" are considered to be a significant problem, although there is a general debate about seriousness. This contrasts with the thousands of deaths from mycotoxins that occur, even now, in the technologically less developed countries (e.g., Indonesia, China, and Africa). Mycotoxins are more toxic than pesticides. Studies are moving from whole animal work to investigating the biochemical mechanisms in isolated cells, and the mechanisms of toxicity at the molecular level are being elucidated. The stereochemical nature of AFs has been shown to be important. In addition, the effect of multiple mycotoxins is being increasingly investigated, which will more accurately represent the situation in nature. It is anticipated that more fungal metabolites will be recognized as dangerous toxins and permitted statutory levels will decrease in the future.