Immunosuppression following dietary aflatoxin B1 exposure: a review of the existing evidence

Effects of aflatoxin and fumonisin on gene expression of growth factors and inflammation-related genes in a human hepatocyte cell line

Aflatoxin B1 (AFB1) and fumonisin B1 (FB1) are mycotoxins widely distributed in maize and maized-based products, often occurring together. The implications of co-exposure to aflatoxin and fumonsin for human health are numerous, but a particular concern is the potential of FB1 to modulate AFB1 hepatotoxicity. This study evaluated the toxicity of these mycotoxins, alone or combined, in a human non-tumorigenic liver cell line, HHL-16 cells, and assessed the effects of AFB1 and FB1 on expression of genes involved in immune and growth factor pathways. The results demonstrated that in HHL-16 cells, both AFB1 and FB1 had dose-dependent and time-dependent toxicity, and the combination of them showed a synergistic toxicity in the cells. Moreover, AFB1 caused upregulation of IL6, CCL20, and BMP2, and downregulation of NDP. In combination of AFB1 with FB1, gene expression levels of IL6 and BMP2 were significantly higher compared to individual FB1 treatment, and had a tendency to be higher than individual AFB1 treatment. This study shows that FB1 may increase the hepatoxicity of AFB1 through increasing the inflammatory response and disrupting cell growth pathways.

Dietary supplementation of Capsicum powder affects the growth, immunoglobulins, pro-inflammatory cytokines, adipokines, meat, and liver histology of aflatoxin B1 exposed broiler chickens

The effects of dietary supplementation with Capsicum annuum fruit pericarp powder (CPP) and Capsicum annuum fruit seed powder (CSP) on the health and performance of broiler chickens exposed to aflatoxin B1 (AFB1) was investigated. Four dietary groups were established: CON (control), AFT (0.5 mg/kg AFB1), CPAF (0.5 g/kg CPP and 0.5 mg/kg AFB1), and CSAF (0.5 g/kg CSP and 0.5 mg/kg AFB1). The AFT group shows a significant (P < 0.05) reduction in the relative growth rate compared to CON, CPAF, and CSAF. In contrast, the latter two groups exhibit growth rates similar (P > 0.05) to CON. Additionally, immunoglobulin levels (IgG, IgM, and IgA) in the AFT group are significantly (P < 0.05) lower compared to the other treatment groups. Serum interleukin-6 levels in the CPAF and CSAF groups were similar (P > 0.05) to CON but higher (P < 0.05) than in AFT. Tumor necrosis factor-alpha levels were elevated (P < 0.05) in AFT compared to the other treatment groups. Interferon-gamma concentrations in AFT were significantly (P < 0.05) lower than in the other treatment groups. The liver histology reveals that the AFT treatment group has periportal hepatic inflammation. In contrast, the CPAF and CSAF treatment groups exhibit normal hepatic microanatomy. In conclusion, 0.5 g/kg CPAF dietary supplementation may help to ameliorate the adverse effects of AFB1 exposure on broiler chicken health, specifically the growth, immune parameters and liver histology.

AFB1 induced free radicals cause encephalopathy in goat kids via intrinsic pathway of apoptosis: pathological and immunohistochemical confirmation of non-hepatic neuroaflatoxicosis

Aflatoxins, particularly AFB1, are the most common feed contaminants worldwide, causing significant economic losses to the livestock sector. The current paper describes an outbreak of aflatoxicosis in a herd of 160 male young goat kids (3-4 months), of which 68 young kids succumbed over a period of 25 days after showing neurological signs of abnormal gait, progressive paralysis and head pressing. The haematobiochemical investigation showed reduced haemoglobin, leucocyte count, PCV level, increased levels of AST, ALT, glucose, BUN, creatinine and reduced level of total protein. Grossly, kids had pale mucous membranes, pale and swollen liver; right apical lobe consolidation, and petechiation of the synovial membrane of the hock joints. The microscopic changes were characterized by multifocal hemorrhages, status spongiosus/ vacuolation, vasculitis, focal to diffuse gliosis, satellitosis, and ischemic apoptotic neurons in different parts of the brain and spinal cord. These changes corresponded well with strong immunoreactivity for AFB1 in neurons, glia cells (oligodendrocytes, astrocytes, and ependymal cells) in various anatomical sites of the brain. The higher values of LPO and reduced levels of antioxidant enzymes (Catalase, SOD, GSH) with strong immunoreactivity of 8-OHdG in the brain indicating high level of oxidative stress. Further, the higher immunosignaling of caspase-3 and caspase-9 in the brain points towards the association with intrinsic pathway of apoptosis. The toxicological analysis of feed samples detected high amounts of AFB1 (0.38ppm). These findings suggest that AFB1 in younger goat kids has more of neurotoxic effect mediated through caspase dependent intrinsic pathway.

Ameliorative effects of camel milk and silymarin upon aflatoxin B1 induced hepatic injury in rats

Aflatoxin B1 (AFB1) poses a major risk to both human and animal health because it contaminates food, feed, and grains. These dangerous effects can be mitigated using natural components. The purpose of this study was to examine the ameliorative effects of camel milk and silymarin supplementation upon aflatoxin B1 induced hepatic injury in rats. This improvement was assessed by measuring leukocytic and deferential counts, serum biochemical parameters, and gene expression of Tumor Necrosis Factor (TNF-α), antioxidant gene (NAD(P)H quinone oxidoreductase 1 (NQO1)), and base excision repair genes (APE1 and OGG1) in the liver tissue, in addition to liver histopathology. Sixty mature males Wister white rats were used to perform the present study; the rats were distributed in six groups (ten rats/group). The control group (without any treatment) received saline by gavage. The camel milk group received 1 ml of camel milk/kg body weight. The silymarin group received 1 ml of silymarin suspension solution at a dose of 20 mg of silymarin/kg of b.wt. The aflatoxin group received an aflatoxin-contaminated diet at a dose of 1.4 mg of aflatoxin /kg of diet and received saline. The camel milk + aflatoxin group received the same previous oral doses of camel milk and an aflatoxin-contaminated diet at the same time. The silymarin + aflatoxin group received the same previous doses of silymarin orally and an aflatoxin-contaminated diet at the same time. The obtained data indicated the deleterious effect of aflatoxin B1 on the leukocytic count, activity of AST and ALT, serum proteins, ferritin, alpha-fetoprotein, carcinoembryonic antigen, liver pathology, and the expression of the studied genes. However, these deleterious effects were mitigated by camel milk and silymarin supplementation. Thus, we could conclude that the ingestion of camel milk and silymarin mitigated the negative effects of AFB1 on the hematology, activity of AST and ALT, serum proteins, ferritin, alpha-fetoprotein, carcinoembryonic antigen, liver pathology, and gene expression in the rat model.

Aflatoxigenic Aspergillus Modulates Aflatoxin-B1 Levels through an Antioxidative Mechanism

Aflatoxins (AFs) are considered to play important functions in species of Aspergillus section Flavi including an antioxidative role, as a deterrent against fungivorous insects, and in antibiosis. Atoxigenic Flavi are known to degrade AF-B1 (B1). To better understand the purpose of AF degradation, we investigated the degradation of B1 and AF-G1 (G1) in an antioxidative role in Flavi. Atoxigenic and toxigenic Flavi were treated with artificial B1 and G1 with or without the antioxidant selenium (Se), which is expected to affect levels of AF. After incubations, AF levels were measured by HPLC. To estimate which population would likely be favoured between toxigenic and atoxigenic Flavi under Se, we investigated the fitness, by spore count, of the Flavi as a result of exposure to 0, 0.40, and 0.86 µg/g Se in 3%-sucrose cornmeal agar (3gCMA). Results showed that levels B1 in medium without Se were reduced in all isolates, while G1 did not significantly change. When the medium was treated with Se, toxigenic Flavi significantly digested less B1, while levels of G1 significantly increased. Se did not affect the digestion of B1 in atoxigenic Flavi, and also did not alter levels of G1. Furthermore, atoxigenic strains were significantly fitter than toxigenic strains at Se 0.86 µg/g 3gCMA. Findings show that while atoxigenic Flavi degraded B1, toxigenic Flavi modulated its levels through an antioxidative mechanism to levels less than they produced. Furthermore, B1 was preferred in the antioxidative role compared to G1 in the toxigenic isolates. The higher fitness of atoxigenic over toxigenic counterparts at a plant non-lethal dose of 0.86 µg/g would be a useful attribute for integration in the broader biocontrol prospects of toxigenic Flavi.

Current Insights in Fungal Importance-A Comprehensive Review

Besides plants and animals, the Fungi kingdom describes several species characterized by various forms and applications. They can be found in all habitats and play an essential role in the excellent functioning of the ecosystem, for example, as decomposers of plant material for the cycling of carbon and nutrients or as symbionts of plants. Furthermore, fungi have been used in many sectors for centuries, from producing food, beverages, and medications. Recently, they have gained significant recognition for protecting the environment, agriculture, and several industrial applications. The current article intends to review the beneficial roles of fungi used for a vast range of applications, such as the production of several enzymes and pigments, applications regarding food and pharmaceutical industries, the environment, and research domains, as well as the negative impacts of fungi (secondary metabolites production, etiological agents of diseases in plants, animals, and humans, as well as deteriogenic agents).

Origanum vulgare Essential Oil Modulates the AFB1-Induced Oxidative Damages, Nephropathy, and Altered Inflammatory Responses in Growing Rabbits

The current study was performed to investigate the toxic effects of aflatoxin B1 (AFB1) through the evaluation of kidney function tests and histopathological examination of renal tissues, targeting the therapeutic role of Marjoram (Origanum vulgare essential oil-OEO) in improving health status. Forty-eight New Zealand Whites growing rabbits (four weeks old) weighing on average 660.5 ± 2.33 g were randomly and equally distributed into four groups, each of which had four replicas of three animals as the following: Control group (only basal diet), AFB1 group (0.3 mg AFB1/kg diet), OEO group (1 g OEO/kg diet) and co-exposed group (1 g OEO/kg + 0.3 mg AF/kg diet). Our study lasted eight weeks and was completed at 12 weeks of age. The results revealed that OEO decreased the toxic effects of AFB1 in rabbit kidneys by substantially reducing the cystatin C levels in the AFB1 group. Additionally, OEO decreased oxidative stress and lipid peroxidation levels in the co-exposed group. Moreover, OEO reduced DNA damage and inflammatory response in addition to the down-regulation of stress and inflammatory cytokines-encoding genes. Besides, OEO preserved the cytoarchitecture of rabbits' kidneys treated with AFB1. In conclusion, O. vulgare essential oil supplementation ameliorated the deleterious effects of AFB1 on the rabbits' kidneys by raising antioxidant levels, decreasing inflammation, and reversing oxidative DNA damage.

Deep Genotypic Species Delimitation of Aspergillus Section Flavi Isolated from Brazilian Foodstuffs and the Description of Aspergillus annui sp. nov. and Aspergillus saccharicola sp. nov

Aspergillus section Flavi is a fungal group that is important in food because it contains spoilage and potentially aflatoxigenic species. Aflatoxins are metabolites that are harmful to human and animal health and have been recognized as the primary natural contaminant in food. Therefore, recognizing the biodiversity of this group in food is necessary to reduce risks to public health. Our study aimed to investigate the diversity of Aspergillus section Flavi isolated from Brazilian foodstuffs such as cassava, sugarcane, black pepper, paprika, Brazil nuts, yerba-mate, peanuts, rice, and corn. A polyphasic approach integrating phenotypic data and multilocus genotypic analyses (CaM, BenA, and RPB2) was performed for 396 strains. Two new species in the Aspergillus subgenus Circumdati section Flavi are proposed using maximum-likelihood analysis, Bayesian inference, and coalescence-based methods: Aspergillus saccharicola sp. nov. and Aspergillus annui sp. nov. A. saccharicola sp. nov. belongs to the series Flavi, is a potentially aflatoxigenic species (B1, B2, G1, and G2), closely related to Aspergillus arachidicola, and was found mostly in sugarcane. A. annui sp. nov. was isolated from samples of sweet paprika. To accommodate A. annui sp. nov., a new series Annuorum was proposed.

Protective and detoxifying effects conferred by selenium against mycotoxins and livestock viruses: A review

Animal feed can easily be infected with molds during production and storage processes, and this can lead to the production of secondary metabolites, such as mycotoxins, which eventually threaten human and animal health. Furthermore, livestock production is also not free from viral infections. Under these conditions, the essential trace element, selenium (Se), can confer various biological benefits to humans and animals, especially due to its anticancer, antiviral, and antioxidant properties, as well as its ability to regulate immune responses. This article reviews the latest literature on the antagonistic effects of Se on mycotoxin toxicity and viral infections in animals. We outlined the systemic toxicity of mycotoxins and the primary mechanisms of mycotoxin-induced toxicity in this analysis. In addition, we pay close attention to how mycotoxins and viral infections in livestock interact. The use of Se supplementation against mycotoxin-induced toxicity and cattle viral infection was the topic of our final discussion. The coronavirus disease 2019 (COVID-19) pandemic, which is currently causing a health catastrophe, has altered our perspective on health concerns to one that is more holistic and increasingly embraces the One Health Concept, which acknowledges the interdependence of humans, animals, and the environment. In light of this, we have made an effort to present a thorough and wide-ranging background on the protective functions of selenium in successfully reducing mycotoxin toxicity and livestock viral infection. It concluded that mycotoxins could be systemically harmful and pose a severe risk to human and animal health. On the contrary, animal mycotoxins and viral illnesses have a close connection. Last but not least, these findings show that the interaction between Se status and host response to mycotoxins and cattle virus infection is crucial.

Alleviation of Oral Exposure to Aflatoxin B1-Induced Renal Dysfunction, Oxidative Stress, and Cell Apoptosis in Mice Kidney by Curcumin

Aflatoxin B1 is a contaminant widely found in food and livestock feed, posing a major threat to human and animal health. Recently, much attention from the pharmaceutical and food industries has been focused on curcumin due to its strong antioxidant capacity. However, the therapeutic impacts and potential mechanisms of curcumin on kidney damage caused by AFB1 are still incomplete. In this study, AFB1 triggered renal injury in mice, as reflected by pathological changes and renal dysfunction. AFB1 induced renal oxidative stress and interfered with the Keap1–Nrf2 pathway and its downstream genes (CAT, SOD1, NQO1, GSS, GCLC, and GCLM), as manifested by elevated oxidative stress metabolites and reduced antioxidant enzymes activities. Additionally, AFB1 was found to increase apoptotic cells percentage in the kidney via the TUNEL assay, along with increased expression of Cyt-c, Bax, cleaved-Caspase-3, Caspase-9, and decreased expression of Bcl-2 at the transcriptional and protein levels; in contrast, for mice given curcumin, there was a significant reversal in kidney coefficient, biochemical parameters, pathological changes, and the expression of genes and proteins involved in oxidative stress and apoptosis. These results indicate that curcumin could antagonize oxidative stress and apoptosis to attenuate AFB1-induced kidney damage.

Environmental exposure and clinical correlates of hepatocellular carcinoma in New York City: a case only study

In the U.S., Hepatocellular carcinoma (HCC) incidence rates have increased. We aimed to determine whether environmental exposure plays a role in the high incidence of HCC observed in New York City. We conducted a hospital-based case only study to examine the prevalence of aflatoxin B1 (AFB1)- and polycyclic aromatic hydrocarbon (PAH)-albumin adducts and the distribution of adducts by different characteristics of HCC patients. Blood samples were collected from 155 HCC patients for biomarker analyses. We observed that about 46% and 49% of cases had detectable AFB1- and PAH-albumin adducts, respectively. There were significant differences between AFB1-albumin adducts and selected factors such as HCV infection status (p = 0.04), diabetes (p = 0.03) and Barcelona Clinic Liver Cancer stage (p = 0.02). Cases with detectable PAH-albumin adducts had a smoking history compared with those with nondetectable levels (p = 0.04). The level of AFB1-albumin adducts was positively correlated with plasma bilirubin (r_s = 0.32, p < 0.0001) and adiponectin concentrations (r_s = 0.28, p = 0.0005). The level of aflatoxin B1-albumin adducts was negatively associated with blood albumin concentration (r_s = - 0.28, p = 0.0009) and plasma DNA LINE-1 methylation (r_s = - 0.16, p = 0.04). Our study provides additional evidence that environmental exposures including to aflatoxin might drive the high incidence of HCC observed in the New York City.

Aflatoxin Biosynthesis, Genetic Regulation, Toxicity, and Control Strategies: A Review

Aflatoxins (AFs) are highly toxic and cancer-causing compounds, predominantly synthesized by the Aspergillus species. AFs biosynthesis is a lengthy process that requires as minimum as 30 genes grouped inside 75 kilobytes (kB) of gene clusters, which are regulated by specific transcription factors, including aflR, aflS, and some general transcription factors. This paper summarizes the status of research on characterizing structural and regulatory genes associated with AF production and their roles in aflatoxigenic fungi, particularly Aspergillus flavus and A. parasiticus, and enhances the current understanding of AFs that adversely affect humans and animals with a great emphasis on toxicity and preventive methods.

miR-155 influences cell-mediated immunity in Balb/c mice treated with aflatoxin M1

Aflatoxin M1 (AFM1) is a 4-hydroxylated metabolite of aflatoxin B1 (AFB1). It induces various toxicological effects including immunotoxicity. In the present study, we investigated the effects of AFM1 on immune system and its modulation by MicroRNA (miR)-155. AFM1 was administered intraperitoneally at doses of 25 and 50 µg/kg for 28 days to Balb/c mice and different immune system parameters were analyzed. The levels of miR-155 and targeted proteins were evaluated in isolated T cells from spleens of mice. Spleen weight was reduced in mice exposed to AFM1 compared to negative control. Proliferation of splenocytes in response to phytohemagglutinin-A was reduced in mice exposed to AFM1. IFN-γ was decreased in mice exposed to AFM1, whereas IL-10 was increased. Concentration of IL-4 did not change different in mice exposed to AFM1 compared to negative control. Exposure to AFM1 reduced the expression of miR-155. Significant upregulation of phosphatidylinositol-3, 4, 5-trisphosphate 5-phosphatase 1 (Ship1) and suppressor of cytokine signaling 1 (Socs1) was observed in isolated T cells from spleens of mice treated with AFM1, but the transcription factor Maf (c-MAF) was not affected. These results suggest that miR-155 and targeted proteins might be involved in the immunotoxicity observed in mice exposed to AFM1.

3D-bioprinted HepaRG cultures as a model for testing long term aflatoxin B1 toxicity in vitro

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3D-bioprinting method to produce 3D HepaRG constructs.

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3D constructs are more resistant to aflatoxin B1.

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Long-term toxicity assessment is possible.

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An alternative method for animal testing relevance.

In recent years 3D-bioprinting technology has been developed as an alternative to animal testing. It possesses a great potential for in vitro testing as it aims to mimic human organs and physiology. In the present study, an alginate-gelatin-Matrigel based hydrogel was used to prepare 3D-bioprinted HepaRG cultures using a pneumatic extrusion printer. These 3D models were tested for viability and metabolic functions. Using 3D-bioprinted HepaRG cultures, we tested the toxicity of aflatoxin B1 (10 or 20 μM) in vitro and compared the results with 2D HepaRG cultures. There was a dose-dependent toxicity effect on cell viability, reduction of metabolic activity and albumin production. We found that 3D-bioprinted HepaRG cultures are more resistant to aflatoxin B1 treatment than 2D cultures. Although the metabolic activities were reduced upon treatment with aflatoxin B1, the 3D models were still viable and survived longer, up to 3 weeks, than the 2D culture, as visualized by fluorescence microscopy. Furthermore, albumin production recovered slightly in 3D models after one and two weeks of treatment. Taken together, we consider using 3D-bioprinting technology to generate 3D tissue models as an alternative way to study toxicity in vitro and this could also provide a suitable alternative for chronic hepatotoxicity studies in vitro.

Nuts and Non-Alcoholic Fatty Liver Disease: Are Nuts Safe for Patients with Fatty Liver Disease?

Diet and lifestyle interventions are the recommended treatment for patients with non-alcoholic fatty liver disease (NAFLD), with the aim of achieving a 7-10% weight loss. Several dietary patterns have been suggested for this purpose, however, to date, the best one is represented by the Mediterranean diet (MD) as it is rich in macro- and micro- nutrients known for their effectiveness in health-promotion and cardio-vascular disease prevention. Moreover, MD is characterized by the inclusion of nuts. These foods have shown potential benefits in health-promotion as they are rich in fibers, which have lipid-lowering effects, rich in mono- and poly-unsaturated fatty acids, which help reduce insulin-resistance and serum cholesterol, and contain anti-oxidants which reduce oxidative stress and inflammation. Additionally, nuts are associated with a better control, or reduction, of Body Mass Index (BMI). All these effects are useful targets to achieve in NAFLD, so that nuts have been proposed as a suitable dietary treatment supplement for weight and metabolic control in these patients. In recent years, health authorities raised an alert on nuts consumption as these may be at high risk of aflatoxin (AF) contamination, for which controls and legislations are different among countries. AF is a well-known cancerogenic agent and a recognized risk factor for hepatocellular carcinoma. Patients with NAFLD have an overall, inherent sevenfold increased risk of developing hepatocellular carcinoma as compared with the general population. In this context, one could argue that recommending the inclusion of nuts in the diet of NAFLD patients has to be balanced with the risk of potential chronic exposure to AF, and every effort should be pursued to assure the safety of these nutrients. In this review, we aim to summarize the benefits of nuts consumption, the evidence for AF contamination of nuts and the consequent potential risks in patients with NAFLD.

Genetic diversity of aflatoxin-producing Aspergillus flavus isolated from selected groundnut growing agro-ecological zones of Uganda

Background

Groundnut pre- and post-harvest contamination is commonly caused by fungi from the Genus Aspergillus. Aspergillus flavus is the most important of these fungi. It belongs to section Flavi; a group consisting of aflatoxigenic (A. flavus, A. parasiticus and A. nomius) and non-aflatoxigenic (A. oryzae, A. sojae and A. tamarii) fungi. Aflatoxins are food-borne toxic secondary metabolites of Aspergillus species associated with severe hepatic carcinoma and children stuntedness. Despite the well-known public health significance of aflatoxicosis, there is a paucity of information about the prevalence, genetic diversity and population structure of A. flavus in different groundnut growing agro-ecological zones of Uganda. This cross-sectional study was therefore conducted to fill this knowledge gap.

Results

The overall pre- and post-harvest groundnut contamination rates with A. flavus were 30.0 and 39.2% respectively. Pre- and post-harvest groundnut contamination rates with A. flavus across AEZs were; 2.5 and 50.0%; (West Nile), 55.0 and 35.0% (Lake Kyoga Basin) and 32.5 and 32.5% (Lake Victoria Basin) respectively. There was no significant difference (χ² = 2, p = 0.157) in overall pre- and post-harvest groundnut contamination rates with A. flavus and similarly no significant difference (χ² = 6, p = 0.199) was observed in the pre- and post-harvest contamination of groundnut with A. flavus across the three AEZs. The LKB had the highest incidence of aflatoxin-producing Aspergillus isolates while WN had no single Aspergillus isolate with aflatoxin-producing potential. Aspergillus isolates from the pre-harvest groundnut samples had insignificantly higher incidence of aflatoxin production (χ² = 2.667, p = 0.264) than those from the post-harvest groundnut samples. Overall, A. flavus isolates exhibited moderate level (92%, p = 0.02) of genetic diversity across the three AEZs and low level (8%, p = 0.05) of genetic diversity within the individual AEZs. There was a weak positive correlation (r = 0.1241, p = 0.045) between genetic distance and geographic distance among A. flavus populations in the LKB, suggesting that genetic differentiation in the LKB population might be associated to geographic distance. A very weak positive correlation existed between genetic variation and geographic location in the entire study area (r = 0.01, p = 0.471), LVB farming system (r = 0.0141, p = 0.412) and WN farming system (r = 0.02, p = 0.478). Hierarchical clustering using the unweighted pair group method with arithmetic means (UPGMA) revealed two main clusters of genetically similar A. flavus isolates.

Conclusions

These findings provide evidence that genetic differentiation in A. flavus populations is independent of geographic distance. This information can be valuable in the development of a suitable biocontrol management strategy of aflatoxin-producing A. flavus.

Characteristics, Occurrence, Detection and Detoxification of Aflatoxins in Foods and Feeds

Mycotoxin contamination continues to be a food safety concern globally, with the most toxic being aflatoxins. On-farm aflatoxins, during food transit or storage, directly or indirectly result in the contamination of foods, which affects the liver, immune system and reproduction after infiltration into human beings and animals. There are numerous reports on aflatoxins focusing on achieving appropriate methods for quantification, precise detection and control in order to ensure consumer safety. In 2012, the International Agency for Research on Cancer (IARC) classified aflatoxins B1, B2, G1, G2, M1 and M2 as group 1 carcinogenic substances, which are a global human health concern. Consequently, this review article addresses aflatoxin chemical properties and biosynthetic processes; aflatoxin contamination in foods and feeds; health effects in human beings and animals due to aflatoxin exposure, as well as aflatoxin detection and detoxification methods.

Bioactive compounds from Aspergillus niger extract enhance the antioxidant activity and prevent the genotoxicity in aflatoxin B1-treated rats

This study aimed to identify the bioactive compounds of the ethyl acetate extract of Aspergillus niger SH2-EGY using GC-MS and to evaluate their protective role against aflatoxin B₁ (AFB₁)-induced oxidative stress, genotoxicity and cytotoxicity in rats. Six groups of male Sprague-Dawley rats were treated orally for 4 weeks included the control group, AFB₁-treated group (80 μg/kg b.w); fungal extract (FE)-treated groups at low (140) or high dose (280) mg/kg b.w and the groups treated with AFB₁ plus FE at the two tested doses. The GC-MS analysis identified 26 compounds. The major compounds found were 1,2,3,4,6-Penta-trimethylsilyl Glucopyranose, Fmoc-L-3-(2-Naphthyl)-alanine, D-(-)-Fructopyranose, pentakis (trimethylsilyl) ether, bis (2-ethylhexyl) phthalate, trimethylsilyl ether-glucitol, and octadecanamide, N-(2- methylpropyl)-N-nitroso. The in vivo results showed that AFB₁ significantly increased serum ALT, AST, creatinine, uric acid, urea, cholesterol, triglycerides, LDL, carcinoembryonic antigen, alpha-fetoprotein, interleukin-6, Malondialdehyde, nitric oxide, Bax, caspase-3 and P53 mRNA expression, chromosomal aberrations and DNA fragmentation. It decreased serum TP, albumin, HDL, Bcl-2 mRNA expression, hepatic and renal TAC, SOD and GPx content and induced histological changes in the liver and kidney. FE prevented these disturbances in a dosage-dependent manner. It could be concluded that A. niger SH2-EGY extract is safe a promising agent for pharmaceutical and food industries.

Chronic and Acute Toxicities of Aflatoxins: Mechanisms of Action

There are presently more than 18 known aflatoxins most of which have been insufficiently studied for their incidence, health-risk, and mechanisms of toxicity to allow effective intervention and control means that would significantly and sustainably reduce their incidence and adverse effects on health and economy. Among these, aflatoxin B1 (AFB1) has been by far the most studied; yet, many aspects of the range and mechanisms of the diseases it causes remain to be elucidated. Its mutagenicity, tumorigenicity, and carcinogenicity-which are the best known-still suffer from limitations regarding the relative contribution of the oxidative stress and the reactive epoxide derivative (Aflatoxin-exo 8,9-epoxide) in the induction of the diseases, as well as its metabolic and synthesis pathways. Additionally, despite the well-established additive effects for carcinogenicity between AFB1 and other risk factors, e.g., hepatitis viruses B and C, and the hepatotoxic algal microcystins, the mechanisms of this synergy remain unclear. This study reviews the most recent advances in the field of the mechanisms of toxicity of aflatoxins and the adverse health effects that they cause in humans and animals.

Probabilistic dietary based estimation of the burden of aflatoxin-induced hepatocellular carcinoma among adult Malawians

The risk of aflatoxin-induced hepatocellular carcinoma (HCC) among adults (average body weight of 60 kg) in Malawi was assessed based on aflatoxin B1 (AFB1) exposure through groundnut and maize consumption, by Monte Carlo simulation. The risk (cases per year per 100,000 people) of aflatoxin-induced HCC was estimated based on the AFB1 exposures estimated by this study and hepatitis B virus infection prevalence published for Malawi. AFB1 exposures were estimated by probabilistically combining data of AFB1 contamination in 338 groundnut and 604 maize samples with data of per capita groundnut and maize consumption in 274 households. Aflatoxins in the samples were analysed using validated LC-MS/MS, HPLC and VICAM based methods. The groundnut and maize consumption survey was based on household expenditure technique. The simulated mean AFB1 exposures through consumption of groundnuts, maize, and combination thereof were 28±65, 42±174, and 71±211 ng/kg. body weight (bw)/day, respectively. The estimated HCC risks were 1.26±2.72, 1.86±6.66 and 3.10±6.85 cases per 100,000 persons per year, respectively. Further, hypothetical eradication of hepatitis B virus (HBV) reduced the risk of HCC by 78%. This reaffirms the need for integrating HBV vaccination in the fight of aflatoxin induced HCC.

Using disease-burden method to evaluate the strategies for reduction of aflatoxin exposure in peanuts

Aflatoxin is a fungal secondary metabolite with high toxicity that is capable of contaminating various types of food crops. It has been identified as a Group 1 human carcinogen by the International Agency for Research on Cancer. Chronic aflatoxin exposure has caused worldwide concern as a matter of public food safety. Peanuts and peanut products are the major sources of aflatoxin exposure. Therefore, some reduction interventions have been developed to minimize contamination throughout the peanut production chain. The purpose of this study is to estimate the efficacy of interventions in reducing the health impact of hepatocellular carcinoma caused by aflatoxin contamination in peanuts. The estimated total Disability-Adjusted Life Years (DALYs) were calculated using FDA-iRISK software. Six aflatoxin reduction strategies were evaluated, including good agricultural practice (GAP), biocontrol, Purdue Improved Crop Storage packaging, basic processing, ozonolysis, and ultraviolet irradiation. The results indicated that basic processing could prevent huge public health loss of 4,079.7-21,833 total DALYs per year. In addition, GAP and biocontrol were both found to be effective strategies in the farm field. Meanwhile, the other three interventions had limited effectiveness in reducing total DALYs. In conclusion, this study could help farmers, processing plants, and government policy makers to alleviate aflatoxin contamination issues in the peanut production chain.

UHPLC-ToF-MS method for determination of multi-mycotoxins in maize: Development and validation

An Ultra-High Performance Liquid Chromatography combined with Time-of-Flight Mass Spectrometry (UHPLC–ToF-MS) method has been developed for determination of nine mycotoxins, namely aflatoxins (AFB₁, AFB₂, AFG₁ and AFG₂), ochratoxin A (OTA), zearalenone (ZEA), toxin T2 (T2) and fumonisins (FB₁ and FB₂) in maize. The method included a two-step extraction with acetonitrile 80% (v/v). After optimization, the analytical method was validated. The different concentrations tested take in account the Maximum Levels (ML) for maize (Commission Regulation EC no. 1881/2006) and good results for repeatability (%RSD_r ≤ 15.4%), reproducibility (%RSD_R ≤ 15.9%) and recovery (77.8–110.4%, except for AFG2 at 2 μg/kg which presented a recovery of 73.4%) were achieved. These met the performance criteria imposed by Commission Regulation (EC) no. 401/2006. The method was applied to twenty-two samples from Portuguese producers of maize. Fumonisins were the most frequently detected mycotoxins, but the levels do not exceed those imposed by European legislation.

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A UHPLC–ToF-MS method was developed for determination of nine mycotoxins in maize.

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Validation of the method was performed taking in account the EU maximum legal limits for maize.

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Good results for repeatability, reproducibility and recovery were achieved.

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The method was applied to 22 samples from Portuguese producers of maize.

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Fumonisins were the most frequently detected mycotoxins.

Immunotoxicity of aflatoxin M1 : as a potent suppressor of innate and acquired immune systems in a subacute study

BACKGROUND

Although, to date, there have been several in vitro and in vivo studies of immunomodulatory effects of aflatoxin M₁ (AFB₁ ), little is known about the effect of AFM₁ on various aspects of innate and acquired immunity. In the present study, AFM₁ was administered intraperitoneally, at doses of 25 and 50 μg kg^-1 , body mass for 28 days and various immunological parameters were measured.

RESULTS

Several parameters related to immune function were suppressed: organ mass, cellularity of spleen, proliferation response to lipopolysaccaride and phytohemagglutinin-A, hemagglutination titer, delayed type of hypersensitivity response, spleen cell subtypes, serum hemolytic activity, serum immunoglobulin G level and cytokine production. AFM₁ did not cause changes in body mass, hematological parameters or the concentration of immunoglobulin M in blood serum.

CONCLUSIONS

Overall, the data suggested that AFM₁ suppressed innate and acquired immunity. Therefore, with respect to consumer safety, it is extremely important to further control the level of AFM₁ in milk, and this should be considered as a precedence for risk management actions. © 2018 Society of Chemical Industry.

Aflatoxin exposure in Nigerian children with severe acute malnutrition

Aflatoxin exposure is an important public health concern in sub-Saharan Africa as well as parts of Latin America and Asia. In addition to hepatocellular carcinoma, chronic aflatoxin exposure is believed to play a role in childhood growth impairment. The most reliable biomarker of chronic aflatoxin exposure is the aflatoxin-albumin adduct, as measured by ELISA or isotope dilution mass spectrometry (IDMS). In this report, we have used high resolution LC-MS/MS with IDMS to quantitate AFB₁-lysine in an extremely vulnerable population of Nigerian children suffering from severe acute malnutrition. To increase the sensitivity and reliability of the analyses, a labelled AFB₁-¹³C₆¹⁵N₂-lysine internal standard was synthesized. AFB₁-lysine concentrations in this population ranged between 0.2 and 59.2 pg/mg albumin, with a median value of 2.6 pg/mg albumin. AFB₁-lysine concentrations were significantly higher in stunted children (median = 4.6 pg/mg) compared to non-stunted (1.2 pg/mg), as well as in children with severe acute malnutrition (4.3 pg/mg) compared to controls (0.8 pg/mg). The median concentrations were also higher in children with kwashiorkor (6.3 pg/mg) compared to those suffering from marasmus (0.9 pg/mg). This is the first report of the use of high-resolution mass spectrometry to quantitate AFB₁-lysine in humans.

Aflatoxin B1 and sterigmatocystin in wheat and wheat products from supermarkets in China

Wheat is an important cereal but it is often contaminated with mycotoxins. The natural occurrence of aflatoxin B₁ (AFB₁) and sterigmatocystin (STC) was determined in 178 food samples (32 wheat samples and 146 wheat products) purchased from Chinese supermarkets. The methodology was validated, the wheat and wheat products samples were treated with a modified QuEChERS (quick, easy, cheap, effective, rugged, and safe) and quantified by liquid chromatography-tandem mass spectrometry (LC-MS/MS). From these samples 18.8% of wheat and 8.2% of cracker samples were contaminated with AFB₁. Mean levels were 0.06 µg/kg and 0.05µg/kg, respectively. There was no AFB₁ contamination in white bread or whole meal bread. Meanwhile 53.1% of wheat, 59.2% of crackers, 20.8% of white bread and 16% of whole meal bread samples were contaminated with STC. The mean levels were 0.07, 0.79, 0.12 and 0.12 µg/kg respectively. Although the levels were low, this demonstrates the need for more comprehensive surveys for these two mycotoxins in wheat and wheat products from China.

Aflatoxin B1 Induces Reactive Oxygen Species-Mediated Autophagy and Extracellular Trap Formation in Macrophages

Aflatoxins are a group of highly toxic mycotoxins with high carcinogenicity that are commonly found in foods. Aflatoxin B1 (AFB1) is the most toxic member of the aflatoxin family. A recent study reported that AFB1 can induce autophagy, but whether AFB1 can induce extracellular traps (ETs) and the relationships among innate immune responses, reactive oxygen species (ROS), and autophagy and the ETs induced by AFB1 remain unknown. Here, we demonstrated that AFB1 induced a complete autophagic process in macrophages (MΦ) (THP-1 cells and RAW264.7 cells). In addition, AFB1 induced the generation of MΦ ETs (METs) in a dose-dependent manner. In particular, the formation of METs significantly reduced the AFB1 content. Further analysis using specific inhibitors showed that the inhibition of either autophagy or ROS prevented MET formation caused by AFB1, indicating that autophagy and ROS were required for AFB1-induced MET formation. The inhibition of ROS prevented autophagy, indicating that ROS generation occurred upstream of AFB1-induced autophagy. Taken together, these data suggest that AFB1 induces ROS-mediated autophagy and ETs formation and an M1 phenotype in MΦ.