Toxic Effects of Aflatoxin B1 in Chinese Sea Bass (Lateolabrax maculatus).

This study was performed to assess the effects of dietary aflatoxin B1 (AFB1) on the growth, antioxidant and immune response, digestive enzyme activities, and intestinal morphology of Lateolabrax maculatus during a 56-day feeding trial. Four diets were formulated including 0, 0.1, 0.5, and 1.0 mg/kg of AFB1. Each diet was randomly assigned to 3 fish tanks with 40 fish per tank. Results indicated that the fish's final body weight, weight gain rate, specific growth rate, feed intake, condition factor, viscerosomatic index, hepatosomatic index, and intestinesomatic index decreased (p < 0.01) as dietary AFB1 increased. AFB1 levels in diets increased (p < 0.05) serum total antioxidant capacity (TAOC), superoxide (SOD), catalase, malondialdehyde (MDA), alkaline phosphatase (AKP), and lysozyme (LZM), and increased (p < 0.05) the TAOC, SOD, MDA, AKP, LZM, and immunoglobulin M in the livers of the fish. Dietary AFB1 decreased (p < 0.05) intestinal trypsin activity and induced intestinal injury. In summary, dietary AFB1 up to 1.0 mg/kg was toxic to L. maculatus as judged by reduced growth, enhanced antioxidant and immune response, decreased intestinal trypsin activity, and impaired intestinal morphology.

Saccharomyces cerevisiae Cell Wall-Based Adsorbent Reduces Aflatoxin B1 Absorption in Rats.

Mycotoxins are naturally occurring toxins that can affect livestock health and performance upon consumption of contaminated feedstuffs. To mitigate the negative effects of mycotoxins, sequestering agents, adsorbents, or binders can be included to feed to interact with toxins, aiding their passage through the gastrointestinal tract (GI) and reducing their bioavailability. The parietal cell wall components of Saccharomyces cerevisiae have been found to interact in vitro with mycotoxins, such as, but not limited to, aflatoxin B1 (AFB1), and to improve animal performance when added to contaminated diets in vivo. The present study aimed to examine the pharmacokinetics of the absorption of radiolabeled AFB1 in rats in the presence of a yeast cell wall-based adsorbent (YCW) compared with that in the presence of the clay-based binder hydrated sodium calcium aluminosilicate (HSCAS). The results of the initial pharmacokinetic analysis showed that the absorption process across the GI tract was relatively slow, occurring over a matter of hours rather than minutes. The inclusion of mycotoxin binders increased the recovery of radiolabeled AFB1 in the small intestine, cecum, and colon at 5 and 10 h, revealing that they prevented AFB1 absorption compared with a control diet. Additionally, the accumulation of radiolabeled AFB1 was more significant in the blood plasma, kidney, and liver of animals fed the control diet, again showing the ability of the binders to reduce the assimilation of AFB1 into the body. The results showed the potential of YCW in reducing the absorption of AFB1 in vivo, and in protecting against the damaging effects of AFB1 contamination.

An improved overall risk probability-based method for assessing the combined health risks of chemical mixtures: An example about mixture of aflatoxin B1 and microcystin LR by dietary intake.

Previous studies on the risk assessment of chemicals with respect to human health have focused mainly on the safety of individual substances. Recently, public health policy emphasizes the combined effects of mixtures. An overall risk probability (ORP)-based method long with the combined toxicity factor (cuv) can be used to evaluate the combined toxicity of chemical mixtures from the environment and foods on human health. However, the procedure for calculating the cuv accurately and quantitatively in the ORP method is yet unclear. In this study, an improved ORP-based method (IORP) was developed by introducing a variable time t, and the cuv was analyzed quantitatively using simultaneous equations and based on the principle of least squares regression. This phenomenon can be explained based on the example of the mixture of aflatoxin B1 (AFB1) and microcystin LR (MC-LR) by dietary intake in order to understand the application of this method. The IORP approach makes it possible for estimating the combined effects of mixtures for human health by dietary pathway.

Detection of acute toxicity of aflatoxin B1 to human hepatocytes in vitro and in vivo using chimeric mice with humanized livers.

Aflatoxin B1 (AFB1), a mycotoxin, is acutely hepatotoxic to many animals including humans. However, there are marked interspecies differences in sensitivity to AFB1-induced toxicity depending on bioactivation by cytochrome P450s (CYPs). In the present study, we examined the applicability of chimeric mice with humanized livers and derived fresh human hepatocytes for in vivo and vitro studies on AFB1 cytotoxicity to human hepatocytes. Chimeric mice with highly humanized livers and SCID mice received daily injections of vehicle (corn oil), AFB1 (3 mg/kg), and carbon tetrachloride (50 mg/kg) for 2 days. Histological analysis revealed that AFB1 promoted hepatocyte vacuolation and inflammatory cell infiltration in the area containing human hepatocytes. A novel human alanine aminotransferase 1 specific enzyme-linked immunosorbent assay demonstrated the acute toxicity of AFB1 to human hepatocytes in the chimeric mouse livers. The sensitivity of cultured fresh human hepatocytes isolated from the humanized liver mice for AFB1 cytotoxicity was comparable to that of primary human hepatocytes. Long-term exposure to AFB1 (6 or 14 days) produced a more severe cytotoxicity. The half-maximal lethal concentration was 10 times lower in the 2-week treatment than after 2 days of exposure. Lastly, the significant reduction of AFB1 cytotoxicity by a pan-CYP inhibitor or transfection with CYP3A4 specific siRNA clearly suggested that bioactivation of AFB1 catalyzed by CYPs was essential for AFB1 cytotoxicity to the human hepatocytes in our mouse model. Collectively, our results implicate the humanized liver mice and derived fresh human hepatocytes are useful models for studies of AFB1 cytotoxicity to human hepatocytes.

Acute aflatoxin B1-induced gastro-duodenal and hepatic oxidative damage is preceded by time-dependent hyperlactatemia in rats.

Elevated serum lactate concentration has been used to predict the risk of fatality in various disease states in acutely ill patients or poisoning with different chemicals. However, its utility in predicting disease progression during acute aflatoxicosis has not been investigated. This study was designed to evaluate changes in blood lactate levels following acute exposure to aflatoxin B1 (AFB1) and to determine whether changes in blood lactate levels bear any relationship with biochemical and/or morphological lesions in the stomach, duodenum, and liver. Twenty-one male Wistar rats were randomly divided into three groups (n = 7 rats /group) including Group A (control) receiving vehicle alone and Groups B and C treated with single oral doses of AFB1 at 2.5 and 5 mg/kg, respectively. AFB1 produced significant (p < 0.05) time- and dose-dependent increase in blood lactate concentration as early as 1 h following its administration, with further increases observed at 3 h and 6 h. The hyperlactatemia accompanied tissue oxidative changes including increased H2O2 and MDA, as well as depletion in glutathione, glutathione peroxidase, superoxide dismutase, and total thiols in gastro-duodenal and hepatic tissues. The oxidative changes were reflected in morphological alterations observed at histopathology with more severe lesions observed with the higher dose of AFB1. Serum levels of pro-inflammatory cytokines (TNF-α and IL-1ß) were, however, differently modified by AFB1 administration. Taken together, the results from this study gives indication that hyperlactatemia may find utility in predicting the severity of tissue damage induced by acute AFB1 exposure.

Predicting the Acute Liver Toxicity of Aflatoxin B1 in Rats and Humans by an In Vitro-In Silico Testing Strategy.

SCOPE: High-level exposure to aflatoxin B1 (AFB1) is known to cause acute liver damage and fatality in animals and humans. The intakes actually causing this acute toxicity have so far been estimated based on AFB1 levels in contaminated foods or biomarkers in serum. The aim of the present study is to predict the doses causing acute liver toxicity of AFB1 in rats and humans by an in vitro-in silico testing strategy. METHODS AND RESULTS: Physiologically based kinetic (PBK) models for AFB1 in rats and humans are developed. The models are used to translate in vitro concentration-response curves for cytotoxicity in primary rat and human hepatocytes to in vivo dose-response curves using reverse dosimetry. From these data, the dose levels at which toxicity would be expected are obtained and compared to toxic dose levels from available rat and human case studies on AFB1 toxicity. The results show that the in vitro-in silico testing strategy can predict dose levels causing acute toxicity of AFB1 in rats and human. CONCLUSIONS: Quantitative in vitro in vivo extrapolation (QIVIVE) using PBK modeling-based reverse dosimetry can predict AFB1 doses that cause acute liver toxicity in rats and human.

Changes in growth performance, aflatoxin B1 residues, immune response and antioxidant status of Litopenaeus vannamei fed with AFB1-contaminated diets and the regulating effect of dietary myo-inositol supplementation.

This study aimed to investigate if myo-inositol (MI) supplementation could alleviate adverse effects caused by aflatoxin B1 (AFB1) with respect to growth performance, AFB1 residues, immune response and antioxidant status of Litopenaeus vannamei. 800 shrimp (initial weight: 1.1 g) were divided into five groups: MI0 (basal diet); MI0 + LA, MI0 + HA, MI200 + LA and MI200 + HA fed with AFB1-contaminated diets (LA, low concentration AFB1; HA, high concentration AFB1; MI200, adding 200 mg MI kg-1 diet). The results showed that HA significantly decreased growth performance, systemic inositol content and lipid content. AFB1 residues were detected in the hepatopancreas of shrimp, but not the muscle. Histological lesions were observed in MI0 + LA and MI0 + HA groups. HA supplementation raised malondialdehyde and protein carbonyl content and reduced some antioxidant enzyme activities and immune-related genes expression, which was slightly ameliorated by MI supplementation. Our results suggest that myo-inositol may slightly mitigate negative impacts caused by AFB1 in L. vannamei.

Combined effects of aflatoxin B1 and deoxynivalenol on the expression of glutathione redox system regulatory genes in common carp.

The purpose of the present study was to evaluate the short-term effects of aflatoxin B1 (AFB1 ) and deoxynivalenol (DON) exposure on the expression of the genes encoding the glutathione redox system glutathione peroxidase 4a (gpx4a), glutathione peroxidase 4b (gpx4b), glutathione synthetase (gss) and glutathione reductase (gsr) and the oxidative stress response-related transcription factors Kelch-like ECH-associated protein 1 (keap1) and nuclear factor-erythroid 2 p45-related factor 2 (nrf2) in liver, kidney and spleen of common carp. During the 24-hr long experiment, three different doses (5 µg AFB1 and 110 µg DON; 7.5 µg AFB1 and 165 µg DON or 10 µg AFB1 and 220 µg DON/kg bw) were used. The results indicated that the co-exposure of AFB1 and DON initiated free radical formation in liver, kidney and spleen, which was suggested by the increase in Nrf2 dependent genes, namely gpx4a, gpx4b, gss and gsr. Expression of keap1 gene showed upregulation after 8 hr of mycotoxin exposure, and also upregulation of nrf2 gene was found in kidney after 8 hr of exposure, while in the liver, only slight differences were observed. The changes in the expression of the analysed genes suggest that level of reactive oxygen species reached a critical level where other signalling pathway was activated as described by the hierarchical model of oxidative stress.

Colostrum fails to prevent bovine/camelid neonatal neutrophil damage from AFB1.

Exposure to environmental toxicants that affect the immune system and overall health of many mammals is mostly unavoidable. One of the more common substances is the mycotoxins, especially carcinogenic aflatoxin (AF)B1 which also causes immune suppression/dysregulation in exposed hosts. The present study analyzed the effects of naturally occurring levels of AFB1 on apoptosis of healthy bovine and camelid neonatal neutrophils (PMN) that were isolated both before and after host consumption of colostrum. Cells from bovine and camel neonates (n = 12 sets of PMN/mammal/timepoint) were exposed for 24 h to a low level of AFB1 (i.e. 10 ng AFB1/ml) and then intracellular ATP content and caspase-3, -7, and -9 activities (determined by bioluminescence) were assessed. The results indicated a significant lessening of intracellular ATP content and equivalents of luminescence intensity in AFB1-treated PMN in all studied samples, i.e. isolated pre-and post-colostrum consumption. In contrast, caspase-3, -7, and -9 activities in both pre- and post-colostrum consumption bovine and camelid PMN were noticeably increased (∼>2-fold). The damaging effects of AFB1 were more pronounced in bovine neonate PMN than in camelid ones. These results showed that camelid or bovine neonatal PMN collected pre- and post-colostrum are sensitive (moreso after consumption) to naturally occurring levels of AFB1. While merits of colostrum are well known, its failure to mitigate toxic effects of AFB1 in what would translate into a critical period in the development of immune competence (i.e. during the first few days of life in bovine and camelid calves) is surprising. The observed in vitro toxicities can help clarify underlying mechanisms of immune disorders caused by AFs in animals/humans.

Lack of Dose- and Time-Dependent Effects of Aflatoxin B1 on Gene Expression and Enzymes Associated with Lipid Peroxidation and the Glutathione Redox System in Chicken.

Effects of aflatoxin B1 (AFB1) on lipid peroxidation and glutathione system were investigated in chicken liver. In a three-week feeding trial, different doses (<1.0 µg/kg (control diet), 17.0 µg (diet A1), 92.0 µg (diet A2), and 182.0 µg (diet A3) AFB1 kg/feed) were used. Markers of lipid peroxidation, conjugated dienes and trienes showed higher values in A3, while amounts of thiobarbituric acid reactive substances were increased in the A1 group at day 21. Glutathione content was lower at day 14 in Group A2. Glutathione peroxidase 4 activity was increased at days 7 and 21 in the A3 group but reduced in the A2 and A3 groups at day 14. The GPX4 gene was downregulated at day 7 in the A2 group, but overregulated at days 14 and 21, and at day 14 in the A3 group. GSS was downregulated at day 14 in the A1 group but overregulated at day 21 in A1 and A2 groups. GSR was downregulated at days 7 and 21 in all treatment groups, but on day 14, induction was observed in the A3 group. The results indicated that AFB1 did not induce dose- or time-dependent effects on the glutathione redox system and its encoding genes at the dose range used, which means that oxidative stress is not the primary effect of AFB1 toxicity.

Hemoadsorption Improves Survival of Rats Exposed to an Acutely Lethal Dose of Aflatoxin B1.

Mycotoxins, such as aflatoxin B1 (AFB1), pose a serious threat as biological weapons due to their high toxicity, environmental stability, easy accessibility and lack of effective therapeutics. This study investigated if blood purification therapy with CytoSorb (CS) porous polymer beads could improve survival after a lethal aflatoxin dose (LD90). The effective treatment window and potential therapeutic mechanisms were also investigated. Sprague Dawley rats received a lethal dose of AFB1 (0.5-1.0 mg/kg) intravenously and hemoperfusion with a CS or Control device was initiated immediately, or after 30, 90, or 240-minute delays and conducted for 4 hours. The CS device removes AFB1 from circulation and significantly improves survival when initiated within 90 minutes of toxin administration. Treated subjects exhibited improved liver morphology and health scores. Changes in the levels of cytokines, leukocytes and platelets indicate a moderately-severe inflammatory response to acute toxin exposure. Quantitative proteomic analysis showed significant changes in the level of a broad spectrum of plasma proteins including serine protease/endopeptidase inhibitors, coagulation factors, complement proteins, carbonic anhydrases, and redox enzymes that ostensibly contribute to the therapeutic effect. Together, these results suggest that hemoadsorption with CS could be a viable countermeasure against acute mycotoxin exposure.

Dietary vegetable choline improves hepatic health of Nile tilapia (Oreochromis niloticus) fed aflatoxin-contaminated diet.

Aflatoxin B1 (AFB1) is one of the most important mycotoxins due to its hepatotoxic and carcinogenic effects on animals. The effect of dietary supplementation with vegetable choline (VC) at 400, 800, and 1200 mg/kg against the deleterious effects of AFB1 (2 ppm/kg diet) in the liver of Nile tilapia (Oreochromis niloticus) was studied. The experimental period was 81 days, and the diet with VC was offered to the fish for 60 days prior to challenge with AFB1. Diets with AFB1 were tested in three replications and animals were analyzed at days 14 and 21 of dietary intake. The addition of VC to tilapia diet increased body weight (days 30 and 60 pre-challenge and day 21 post-challenge). The group fed aflatoxin-contaminated diet presented significantly reduced antioxidant enzymes and increased reactive oxygen species (ROS) levels, thiobarbituric acid reactive species (TBARS) levels, and protein carbonyl (PC) content in the liver. Dietary supplementation with VC at 800 and 1200 mg/kg demonstrated a significant protective effect, avoiding the increase of ROS, TBARS, and PC levels in the liver of tilapia from the aflatoxin contaminated groups. Thus, dietary VC supplementation may be used in tilapia to increase antioxidant status and reduce the negative effects caused by AFB1 toxicity. Based on the findings, it is recommended to use VC as a food supplement for Nile tilapia in order to avoid AFB1 toxication. In addition, decreased aflatoxin toxicity can be attributed to the VC antioxidant property.

The effect of moderate-dose aflatoxin B1 and Salmonella Enteritidis infection on intestinal permeability in broiler chickens.

The effect of dietary aflatoxin B1 (AFB1) and Salmonella Enteritidis infection on intestinal permeability was investigated. Two hundred 1-day-old male Ross 308 broiler chickens were randomly divided into 4 treatments of 5 replicates each (10 birds per replicate), which were fed ad libitum for 3 weeks with the following treatments: control, chickens fed an AFB1-free diet; AF, chickens fed an AFB1-contaminated diet at 470 ng/g; SE, chickens fed an AFB1-free diet and challenged with 108 cfu of S. Enteritidis per bird at 18 days old; AF + SE, chickens fed an AFB1-contaminated diet and challenged with 108 cfu of S. Enteritidis per bird at 18 days old. At day 21 of age, chicks received an oral gavage dose of fluorescein isothiocyanate dextran (FITC-dextran) to evaluate gastrointestinal leakage. Blood and intestinal samples were collected to evaluate serum biochemistry and total intestinal IgA secretion, respectively. Liver tissues were aseptically collected to assess bacterial invasiveness and for histomorphological studies. The results showed that chickens receiving AFB1 presented a significant increment (up to 2.4-fold) in serum FITC-dextran concentration (p < 0.05). Nevertheless, S. Enteritidis infection had no additional effect on gastrointestinal leakage. Furthermore, the ingestion of AFB1 had no impact on the invasive potential of S. Enteritidis. These results suggest that moderate-dose AFB1 adversely affects intestinal barrier function resulting in increased gut permeability in broiler chickens.

Acute oral toxicity test and assessment of combined toxicity of cadmium and aflatoxin B1 in kunming mice.

Cadmium and aflatoxin B1 (AFB1) are both common and widespread pollutants in food and feed. There are several reports on toxicity induced by Cadmium or AFB1 alone, but few address the toxicity caused by co-exposure to the two substances. In this study, 42 female and 42 male Kunming (KM) mice were divided into seven groups to test the acute oral toxicity of CdCl2 and AFB1, using Karber's method. The combined toxicity was assessed using the Keplinger evaluation system. Acute toxicity symptoms, deaths, and body and organ weights were evaluated, and hematological, blood biochemical, and histopathological analyses were conducted. The results revealed the following median lethal doses (LD50): LD50(Female KM mice) = 62.56 mg/kg; LD50(Male KM mice) = 48.79 mg/kg; LD50(KM mice)=55.27 mg/kg. The combined toxicity of AFB1 and CdCl2 showed an additive effect in mice, and an increase in the mixed dose of AFB1 and CdCl2 resulted in greater toxicity. These results demonstrated that the combined toxicity of AFB1 and CdCl2 was greater than the toxicities of the individual components in mice; thus, this may cause particular challenges when addressing these hazards in food and feed and the associated risk to human and animal health.

Assessment of dietary exposure to aflatoxin B1 from corn arepas in Colombia.

The aim of this research was to evaluate dietary exposure to aflatoxin B1 (AFB1) in corn arepas in Colombia. In addition, in this study an assessment considering compliance to the maximum level of AFB1 (4 µg kg-1) for this food was conducted. AFB1 concentration data in corn arepas were obtained from 168 samples. The samples were collected from factories in 16 departments in Colombia. AFB1 was quantified by High-Performance Liquid Chromatography with a fluorescence detector. Consumption data and body weight (b.w.) were measured from the 2005 Colombian National Survey of Nutritional Status. Probabilistic estimates were made by Monte Carlo simulation of dietary exposure and margin of exposure (MOE) segmented by age group. The results showed that 27% of corn arepa samples were contaminated with AFB1, with an average concentration of 15.1 µg kg-1 and a maximum value of 111.1 µg kg-1. The stochastic dietary exposure assessment showed that the age group most exposed was children between 4 and 8 years old (10.014 ng (kg b.w. day)-1). In addition, the MOE values for all age groups were lower than 10,000, indicating a potential risk for consumers. However, in the scenario where AFB1 concentration level complies with the maximum limit of 4 µg kg-1 AFB1, the level of concern could be reduced for the adult population between 14 and 64 years old because the MOE value is above 10,000.

Lactobacillus rhamnosus GG modulates gastrointestinal absorption, excretion patterns, and toxicity in Holstein calves fed a single dose of aflatoxin B1.

The aim of the present study was to evaluate the effects of Lactobacillus rhamnosus GG (LGG; ATCC 53013) on growth performance and hepatotoxicity in calves fed a single dose of aflatoxin B1 (AFB1) and to investigate the absorption, distribution, and elimination of AFB1 and the hydroxylated metabolite aflatoxin M1 (AFM1) in rumen fluid, blood, and excretions. Twenty-four male Holstein calves were blocked for body weight and age and were randomly assigned to 1 of 3 treatment groups: (1) untreated control, (2) treated with 4.80 mg of AFB1 (AFB1 only), or (3) treated with 1 × 1010 cfu of LGG suspension and 4.80 mg of AFB1 (AFB1 plus LGG). The calves received LGG suspension in 50 mL of phosphate-buffered saline daily via oral administration for 14 d before and on the day they received a single oral dose of AFB1. Body weight was recorded at the beginning of the study (before LGG administration), at the day of AFB1 administration, and at the end of the trial. Rumen fluid, blood, urine, and feces samples were collected continuously for 96 h after AFB1 administration. Average daily gain (ADG) and plasma biochemical parameters were analyzed, and concentrations of AFB1 and AFM1 in the samples were determined for monitoring excretion pattern and toxicokinetics. The results showed that ADG was lower in AFB1-treated animals; LGG administration partially mitigated the decrease in ADG (0.85 ± 0.08 vs. 0.76 ± 0.18 kg of gain/d). The AFB1 treatment increased plasma aspartate aminotransferase, alkaline phosphatase, and lactate dehydrogenase levels. Administration of LGG alleviated the AFB1-induced increase in plasma enzymes activity. The excretion patterns of AFB1 and AFM1 were surprisingly regular; toxins were rapidly detected in all samples after a single oral dose of AFB1, and the peak of toxins concentrations was sequentially reached in rumen fluid, plasma, urine, and feces (except AFM1 in rumen fluid), followed by an exponential decrease. The excretion curves showed that AFB1 and AFM1 concentrations were the highest in feces and urine, respectively. Administration of LGG decreased the concentrations of free AFB1 and AFM1 in rumen fluid and reduced the release of toxins into plasma and urine. Toxicokinetic parameters (except for the time of maximum concentration and the terminal half-life) were reduced by LGG administration. In conclusion, the absorption, distribution, and excretion of AFB1 and AFM1 were rapid in calves fed a single dose of AFB1. Urine was the main route for the excretion of AFM1, and the clearance pattern from the peak of concentration was well fitted by exponential decreasing function. Administration of LGG reduced the absorption of AFB1 in the gastrointestinal tract by increasing the excretion via the feces, thus alleviating the hepatotoxic effect of AFB1.

Mannan Oligosaccharide Protects against the Aflatoxin-B1-Promoted Influenza Replication and Tissue Damages in a Toll-Like-Receptor-4-Dependent Manner.

Our previous study reported that aflatoxin B1 (AFB1) promoted influenza replication. Mannan oligosaccharide (MOS), derived from the cell walls of yeast, is a potent immunomodulator. Here, we investigated the role of MOS in AFB1-promoted influenza replication and further explored the underlying mechanisms. In vitro and in vivo, the exposure to AFB1 alone resulted in significantly decreased weight gain and increased viral replication as well as lung and spleen damages. Increased influenza replication coupled with increases in toll-like receptor 4 (TLR4), phosphorylated nuclear factor κB, and tumor necrosis factor α (TNF-α) levels. However, MOS given in conjunction with exposure to AFB1 significantly reversed these above changes. A further study indicated that MOS activity was abolished by TLR4 knockout or TLR4 overexpression. Surprisingly, TNF-α played no role in the MOS-mediated protective effects. Collectively, our data suggest that MOS alleviates the AFB1-promoted influenza replication, inflammation, and tissue damages in a TLR4-dependent manner.

Assessing the combined toxicity of the natural toxins, aflatoxin B1, fumonisin B1 and microcystin-LR by high content analysis.

As human co-exposure to natural toxins through food and water is inevitable, risk assessments to safeguard health are necessary. Aflatoxin B1 and fumonisin B1, frequent co-contaminants of maize and microcystin-LR, produced in freshwater by cyanobacteria are all naturally occurring potent toxins that threaten human health. Populations in the poorest regions of the world may suffer repeated simultaneous exposure to these contaminants. Using High Content Analysis, multiple cytotoxicity endpoints were measured for the individual toxins and mixtures in various cell lines. Results highlighted that significant cytotoxic effects were observed for aflatoxin B1 in all cell lines while no cytotoxic effects were observed for fumonisin B1 or microcystin-LR. Aflatoxin B1/microcystin-LR was cytotoxic in the order HepG2 > Caco-2 > MDBK. Fumonisin B1/microcystin-LR affected MDBK cells. The ternary mixture was cytotoxic to all cell lines. Most combinations were additive, however antagonism was observed for binary and ternary mixtures in HepG2 and MDBK cell lines at low and high concentrations. Synergy was observed in all cell lines, including at low concentrations. The combination of these natural toxins may pose a significant risk to populations in less developed countries. Furthermore, the study highlights the complexity around trying to regulate for human exposure to multiple contaminants.

Serum and hepatic oxidative damage induced by a diet contaminated with fungal mycotoxin in freshwater silver catfish Rhamdia quelen: Involvement on disease pathogenesis.

It has been recognized that oxidative stress is implicated in the initiation and progression of diseases due to the excessive formation of free radicals and impairment of the antioxidant defense system, contributing to the mortality of affected animals. The occurrence of a disequilibrium between the antioxidant/oxidant status in serum and liver of freshwater fish fed with aflatoxin B1 (AFB1) remains poorly understood and limited to only a few oxidant variables. Thus, the aim of this study was to evaluate whether an AFB1-contaminated diet causes disturbance on the antioxidant and oxidant status in silver catfish (Rhamdia quelen) of freshwater. Serum and hepatic reactive oxygen species (ROS), metabolites of nitric oxide (NOx), and lipid hydroperoxide increased on days 14 and 21 post-feeding in animals that received AFB1 contaminated diet compared to the control group (basal diet), while protein carbonylation levels increased on day 21 post-feeding. On the other hand, serum and hepatic antioxidant capacity against peroxyl radical and vitamin C levels, as well as glutathione peroxidase and catalase activities were lower on days 14 and 21 post-feeding in animals that received AFB1 contaminated diet compared to the control group. No difference was observed between groups regarding the superoxide dismutase activity and glutathione levels. Based on these evidences, an AFB1-contaminated diet causes a disturbance on serum and hepatic antioxidant/oxidant system due to lipid and protein damage elicited by excessive ROS and NOx production. Also, the antioxidant defense system was unable to avoid or minimize ROS and NOx deleterious effects, and consequently, the oxidative damage. In summary, this disturbance can contribute to understand the pathophysiology and mortality of fish after the consumption of AFB1-contaminated diets.

Effects of dietary adsorbent on milk aflatoxin M1 content and the health of lactating dairy cows exposed to long-term aflatoxin B1 challenge.

The objective of this study was to evaluate the effects of Solis Mos (Novus International Inc., St. Charles, MO) on milk aflatoxin M1 (AFM1) content, lactation performance, plasma biochemical parameters, and ruminal fermentation in dairy cows exposed to long-term aflatoxin B1 (AFB1) challenge. Forty dairy cows were grouped according to days in milk (33 ± 7 d; mean ± SD) and milk production (33.9 ± 3.1 kg) and randomly assigned to 1 of 4 treatments: control (no additive), 20 µg of AFB1/kg of diet dry matter (AF), addition of Solis Mos at 0.25% of diet dry matter (SM), and MIX (AF + SM). The experiment lasted 9 wk, including an adaptation period during the first week. Dry matter intake, milk yield, and milk composition were measured on d 6 and 7 of each week. Milk AFM1, plasma biochemical parameters, and ruminal fermentation variables were analyzed on the last days of wk 1 and 9. No differences were observed in dry matter intake, milk yield, percentages of milk protein, milk fat, and lactose, and somatic cell counts across the treatments. Addition of adsorbent in the AFB1-contaminated diet significantly reduced the milk AFM1 concentrations (0.19 vs. 0.13 µg/kg) and transfer rates (1.38 vs. 0.89%). Dairy cows fed an AFB1-contaminated diet had lower superoxide dismutase activity, total antioxidant capacity, glutathione peroxidase, and levels of IgG and IgA, and higher levels of malondialdehyde in the plasma. Inclusion of Solis Mos in the diet increased the plasma superoxide dismutase activity, total antioxidant capacity, and IgG levels, and decreased the malondialdehyde level. Neither AFB1 nor Solis Mos affected the plasma levels of glutamic oxaloacetic transaminase, glutamic pyruvic transaminase, alkaline phosphatase, or IgM. Long-term inclusion of adsorbent Solis Mos in the diet did not affect lactation performance or liver function, but it reduced milk AFM1 concentrations and oxidative stress and improved the immunological condition and ruminal fermentation in lactating dairy cows exposed to long-term AFB1 challenge.