Environmentally relevant level of aflatoxin B 1 elicits toxic pro-inflammatory response in murine CNS-derived cells

Curcumin attenuates aflatoxin B1-induced ileum injury in ducks by inhibiting NLRP3 inflammasome and regulating TLR4/NF-κB signaling pathway

Aflatoxin B1 (AFB1) is a widespread toxic contamination in feed for animals. The primary active component of turmeric, curcumin (Cur), is an antioxidant and an anti-inflammatory. However, it is yet unknown how AFB1 affects the intestinal epithelial barrier and whether Cur acts as a protective mechanism when exposed to AFB1. Here, we explored the mechanism of AFB1-induced intestinal injury from intestinal epithelial barrier, inflammation, pyroptosis, and intestinal flora, and evaluated the protective role of Cur. We found that AFB1 caused weight loss and intestinal morphological damage that is mainly characterized by shortened intestinal villi, deepened crypts, and damaged intestinal epithelium. Exposure to AFB1 decreased the expression of Claudin-1, MUC2, ZO-1, and Occludin and increased the expression of pyroptosis-related factors (NLRP3, GSDMD, Caspase-1, IL-1β, and IL-18) and inflammation-related factors (TLR4, NF-κB, IκB, IFN-γ, and TNF-α). Furthermore, ileal gut microbiota was altered, and simultaneously, the Lactobacillus abundance was decreased. The gut microbiota interacts with a wide range of physiologic functions and disease development in the host through its metabolites, and disturbances in gut microbial metabolism can cause functional impairment of the ileum. Meanwhile, Cur can ameliorate histological ileum injuries and intestinal flora disturbance caused by AFB1. We found that Cur reversed the effects of AFB1 through modulating both NLRP3 inflammasome and the TLR4/NF-κB signaling pathway. In conclusion, AFB1 can induce inflammatory damage and pyroptosis in duck ileum, while Cur has obviously protective effects on all the above damages.

The Ameliorative Role of Lico A on Aflatoxin B1-Triggered Hepatotoxicity Partially by Activating Nrf2 Signal Pathway

Aflatoxin B1 (AFB1) is one of the most harmful and toxic mycotoxins in foods and feeds, posing a serious health risk to both humans and animals, especially its hepatotoxicity. Nuclear factor-erythroid 2-related factor 2 (Nrf2), an important nuclear transcription factor, is generally recognized as a potential target for phytochemicals to ameliorate liver injury. The current study sought to elucidate the molecular processes by which licochalcone A (Lico A), a compound derived from Xinjiang licorice Glycyrrhiza inflate, protects against AFB1 toxicity. In vivo, male wild-type (WT) and Nrf2 knockout (Nrf2-/-) C57BL/6 mice were orally administered AFB1 at 1.5 mg/kg body weight (BW) with or without Lico A at 5 mg/kg. In vitro, AML12 cells were utilized to evaluate the protective effect and mechanism of Lico A against the AFB1-induced hepatotoxicity. Our findings demonstrated that AFB1 caused severe hepatotoxicity, while Lico A treatment successfully relieved the toxicity. Meanwhile, Lico A effectively improved liver injury, inflammatory mediators, oxidative insults, apoptosis, liver fibrosis, and pyroptosis, which contributed to the inhibition of toll receptor 4 (TLR4)-NF-κB/MAPK and NOD-like receptors protein 3 (NLRP3)/caspase-1/GSDMD signaling pathway activation. Furthermore, Lico A was able to enhance the Nrf2 antioxidant signaling pathway. Intriguingly, Lico A still had a protective effect on AFB1-caused liver injury in mice via the inhibition of inflammation and pyroptosis, while apoptosis and liver fibrosis were blocked in the absence of Nrf2. To sum up, the present study first elucidated that Lico A ameliorated AFB1-induced hepatotoxic effects and its main mechanism involved the inhibitory effects on oxidative stress, apoptosis, liver fibrosis, inflammation, and pyroptosis, which might be partially dependent on the regulation of Nrf2. The work may enrich the role and mechanism of Lico A's resistance to liver injury caused by various factors, and its application is promising.

Cellular and molecular mechanisms of aflatoxin B1-mediated neurotoxicity: The therapeutic role of natural bioactive compounds

Aflatoxin B1 (AFB1), a dietary toxin from the mold Aspergillus species, is well acknowledged to elicit extra-hepatic toxicity in both animals and humans. The neurotoxicity of AFB1 has become a global public health concern. Contemporary research on how AFB1 enters the brain to elicit neuronal dysregulation leading to noxious neurological outcomes has increased greatly in recent years. The current review discusses several neurotoxic outcomes and susceptible targets of AFB1 toxicity at cellular, molecular and genetic levels. Specifically, neurotoxicity studies involving the use of brain homogenates, neuroblastoma cell line IMR-32, human brain microvascular endothelial cells, microglial cells, and astrocytes, as well as mammalian and non-mammalian models to unravel the mechanisms associated with AFB1 exposure are highlighted. Further, some naturally occurring bioactive compounds with compelling therapeutic effects on AFB1-induced neurotoxicity are reviewed. In conclusion, available data from literature highlight AFB1 as a neurotoxin and its possible pathological contribution to neurological disorders. Further mechanistic studies aimed at discovering and developing effective therapeutics for AFB1 neurotoxicity is warranted.

Lipidomic profiling study on neurobehavior toxicity in zebrafish treated with aflatoxin B1

Mycotoxin aflatoxin B1 (AFB1) has been proven to cause neurotoxicity, but its potential interference with the normal function of brain tissue is not fully defined. As the indispensable role of lipids in maintaining the normal function of brain tissue, the aim of this study is to clarify the effect of AFB1 short-term (7 days) exposure on brain tissue from the perspective of lipid metabolism. In this study, zebrafish were exposed to two concentrations (5, 20 μg/L). Through quantitative analysis of AFB1, the detection of AFB1 in zebrafish brain tissue was discovered for the first time, combined with the changes in zebrafish neurobehavior, the occurrence of brain injury was deduced. Subsequently, 1734 lipids in zebrafish brain tissue were mapped using ion mobility time-of-flight mass spectrometry (UPLC-QTOF-IMS-MS), which has great advantages in lipid detection. Comparative analysis of the abnormal lipid metabolism in zebrafish brain revealed 114 significantly changed lipids, mainly involving two pathways of sphingolipid metabolism and fatty acid degradation. This study discovered the detection of AFB1 in the brain and revealed a potential link between AFB1-induced behavioral abnormalities and lipid metabolism disorders in brain tissue, providing reliable evidence for elucidating the neurotoxicity of AFB1.

Aflatoxin B1 exposure triggers inflammation and premature skin aging via ERMCS/Ca2+/ROS signaling cascade

Aflatoxin B1 (AFB1) is a recognized hazard environmental contaminant mainly found in cereal and fruits. The toxicity of AFB1 exposure to various organs has been revealed in some literature. In current study, we explored the effect of AFB1 exposure on premature aging/senescence of skin. In vivo, 8-week-old C57 mice were used as models to evaluate the effect of dietary AFB1 exposure on premature skin aging. The results showed that AFB1 exposure caused premature skin aging by testing aging markers. Additionally, AFB1 led to oxidative stress and inflammatory response. In vitro, AFB1 exposure triggered premature cellular senescence in mouse skin fibroblasts cells (L929 cells) by assessing a range of cellular senescence-related markers. Further, the potential molecular mechanism by which AFB1 induce the premature skin aging was studied. ROS and Ca2+ is proven to be the key molecules in AFB1-induced cellular senescence. Further, through eliminating Ca2+, AFB1-caused oxidative stress and cellular senescence were both attenuated, suggesting that Ca2+ overload in the mitochondria results in cellular senescence by increasing ROS production. Next, we analyzed the causes of Ca2+ overload, and results showed that AFB1 exposure induces Ca2+ overload through increasing the formation of mitoguardin (Miga) and vesicle-associated membrane protein (VAMP)-associated protein (Vap33)-mediated endoplasmic reticulum (ER)-mitochondria contact sites (ERMCS). AFB1 exposure also inhibited mitophagy, leading to accelerate L929 cell senescence. In short, combining in vivo and in vitro results, we demonstrate that exposure to AFB1 causes premature skin aging, which is dependent on ERMCS/Ca2+/ROS/ signaling axis. The current study suggests that prolonged exposure to AFB1 makes skin more vulnerable to damage.

Immunotoxicity and the mechanisms of aflatoxin B1-induced growth retardation in shrimp and alleviating effects of bile acids

Aflatoxin B1 (AFB1) is one of the most toxic mycotoxins prevalent in the environment and food chain, posing severe health risks to humans and animals. Bile acids are natural detergents synthesized from cholesterol and play a key role in the excretion of toxins in vertebrates. Here, pacific white shrimp (Litopenaeus vannamei) served as an animal model to examine the toxicity mechanisms of AFB1 and assess the potential alleviating effects of bile acids against AFB1. Our results revealed that AFB1 exposure significantly inhibited the growth performance and immune response of shrimp, accompanied by AFB1 accumulation and histological damage. Mechanistically, AFB1-induced DNA damage activated DNA repair mechanisms and induced the arrest of cell cycle via the ATR-cyclin B/cdc2 pathway. Additionally, AFB1 directly suppressed the immune response and growth performance of shrimp by inhibiting Toll and IMD pathways and the secretion of digestive enzymes. Notably, dietary bile acids significantly reduced AFB1 accumulation and alleviated AFB1-induced growth retardation and immunotoxicity in shrimp, and CCKAR, ATR, and Relish may be key mediators of the alleviating effects of bile acids. Our study provided new insights into the toxicity mechanisms of AFB1 in invertebrates and highlighted the potential of bile acids to alleviate AFB1 toxicity.

Discovering the Protective Effects of Quercetin on Aflatoxin B1-Induced Toxicity in Bovine Foetal Hepatocyte-Derived Cells (BFH12)

Aflatoxin B1 (AFB1) induces lipid peroxidation and mortality in bovine foetal hepatocyte-derived cells (BFH12), with underlying transcriptional perturbations associated mainly with cancer, cellular damage, inflammation, bioactivation, and detoxification pathways. In this cell line, curcumin and resveratrol have proven to be effective in mitigating AFB1-induced toxicity. In this paper, we preliminarily assessed the potential anti-AFB1 activity of a natural polyphenol, quercetin (QUE), in BFH12 cells. To this end, we primarily measured QUE cytotoxicity using a WST-1 reagent. Then, we pre-treated the cells with QUE and exposed them to AFB1. The protective role of QUE was evaluated by measuring cytotoxicity, transcriptional changes (RNA-sequencing), lipid peroxidation (malondialdehyde production), and targeted post-transcriptional modifications (NQO1 and CYP3A enzymatic activity). The results demonstrated that QUE, like curcumin and resveratrol, reduced AFB1-induced cytotoxicity and lipid peroxidation and caused larger transcriptional variations than AFB1 alone. Most of the differentially expressed genes were involved in lipid homeostasis, inflammatory and immune processes, and carcinogenesis. As for enzymatic activities, QUE significantly reverted CYP3A variations induced by AFB1, but not those of NQO1. This study provides new knowledge about key molecular mechanisms involved in QUE-mediated protection against AFB1 toxicity and encourages in vivo studies to assess QUE's bioavailability and beneficial effects on aflatoxicosis.

Anti-inflammation-based treatment of atherosclerosis using Gliclazide-loaded biomimetic nanoghosts

In the study, a biomimetic platform for anti-inflammatory-based treatment of atherosclerotic plaque was developed. Gliclazide (GL) as an anti-inflammasome agent was encapsulated in PLGA nanoparticles (NP), which were coated by monocyte membrane using an extrusion procedure. The size and zeta potential of the nanoghost (NG) changed to 292 and - 10 nm from 189.5 to -34.1 in the core NP. In addition, the actual size of 62.5 nm with a coating layer of 5 nm was measured using TEM. The NG was also showed a sustained release profile with the drug loading content of about 4.7%. Beside to attenuated TNFα, decrease in gene expression levels of NLRP3, MyD88, NOS, IL-1β, IL-18 and caspases 1/3/8/9 in LPS-primed monocytes exposed to NG strongly indicated remarkable inflammation control. After systemic toxicity evaluation and pharmacokinetic analysis of NP and NG, intravenous NG treatment of rabbits with experimentally induced atherosclerosis revealed remarkably less plaque lesions, foam cells, lipid-laden macrophages, and pathological issues in tunica media of aorta sections. Higher expression of CD163 than CD68 in aorta of NG-treated rabbits strongly reveals higher M2/M1 macrophage polarization. The bio/hemocompatible, biomimetic and anti-inflammatory NG can be considered as a potential platform for immunotherapy of particularly atherosclerosis in the field of personalized medicine.

Aflatoxin B1 Increases Soluble Epoxide Hydrolase in the Brain and Induces Neuroinflammation and Dopaminergic Neurotoxicity

Parkinson's disease (PD) is an increasingly common neurodegenerative movement disorder with contributing factors that are still largely unexplored and currently no effective intervention strategy. Epidemiological and pre-clinical studies support the close association between environmental toxicant exposure and PD incidence. Aflatoxin B1 (AFB1), a hazardous mycotoxin commonly present in food and environment, is alarmingly high in many areas of the world. Previous evidence suggests that chronic exposure to AFB1 leads to neurological disorders as well as cancer. However, whether and how aflatoxin B1 contributes to the pathogenesis of PD is poorly understood. Here, oral exposure to AFB1 is shown to induce neuroinflammation, trigger the α-synuclein pathology, and cause dopaminergic neurotoxicity. This was accompanied by the increased expression and enzymatic activity of soluble epoxide hydrolase (sEH) in the mouse brain. Importantly, genetic deletion or pharmacological inhibition of sEH alleviated the AFB1-induced neuroinflammation by reducing microglia activation and suppressing pro-inflammatory factors in the brain. Furthermore, blocking the action of sEH attenuated dopaminergic neuron dysfunction caused by AFB1 in vivo and in vitro. Together, our findings suggest a contributing role of AFB1 to PD etiology and highlight sEH as a potential pharmacological target for alleviating PD-related neuronal disorders caused by AFB1 exposure.

Chronic exposure to aflatoxin B1 increases hippocampal microglial pyroptosis and vulnerability to stress in mice

BACKGROUND

Chronic aflatoxin B1 (AFB1) exposure may increase the risk of multiple neuropsychiatric disorders. Stress is considered one of the main contributors to major depressive disorder. Whether and how chronic AFB1 exposure affects vulnerability to stress is unclear.

METHODS

Mice were exposed for three weeks to AFB1 (100 µg/kg/d) and/or chronic mild stress (CMS). The vulnerability behaviors in response to stress were assessed in the forced swimming test (FST), sucrose preference test (SPT), and tail suspension test (TST). Microglial pyroptosis was investigated using immunofluorescence, enzyme-linked immunosorbent assays, and western blot assay in the hippocampus of mice. Hippocampal neurogenesis and the effects of AFB1-treated microglia on proliferation and differentiation of neural stem/precursor cells (NSPCs) were assessed via immunofluorescence in the hippocampus of mice.

RESULTS

Mice exposed to CMS in the presence of AFB1 exhibited markedly greater vulnerability to stress than mice treated with CMS or AFB1 alone, as indicated by reduced sucrose preference and longer immobility time in the forced swimming test. Chronic aflatoxin B1 exposure resulted in changes in the microglial morphology and increase in TUNEL⁺ microglia and GSDMD⁺ microglia in the hippocampal dentate gyrus. When mice were exposed to both CMS and AFB1, pyroptosis-related molecules (such as NLRP3, caspase-1, GSDMD-N, and interleukin-1β) were significantly upregulated in the hippocampus. These molecules were also significantly enhanced by AFB1 in primary microglial cultures. AFB1-treated mice showed decrease in the numbers of BrdU⁺, BrdU-DCX⁺, and BrdU-NeuN⁺ cells in the hippocampal dentate gyrus, as well as the percentages of BrdU⁺ cells that were NeuN⁺ in the presence or absence of CMS when compared with vehicle-treated mice. The combination of AFB1 and CMS exacerbated these effects to an even greater extent. The number of DCX⁺ cells correlated negatively with the percentage of ameboid microglia, TUNEL⁺ microglia and GSDMD⁺ microglia in the hippocampal dentate gyrus. AFB1-treated microglia suppressed the proliferation and neuronal differentiation of NSPCs in vitro.

CONCLUSION

Chronic AFB1 exposure induces microglial pyroptosis, promoting an adverse neurogenic microenvironment that impairs hippocampal neurogenesis, which may render mice more vulnerable to stress.

The anti-inflammatory effects of minocycline on lipopolysaccharide-induced paw oedema in rats: a histopathological and molecular study

Minocycline is a semi-synthetic antimicrobial agent with claimed anti-inflammatory properties reported from different experimental models. This study was aimed to evaluate the anti-inflammatory effects of minocycline, compared to the actions of two common anti-inflammatory agents, on lipopolysaccharide (LPS)-induced paw oedema through some clinical, histopathological, haematological and molecular analyses. Forty-eight rats were divided into eight groups (n = 6). In control group (Ctrl), each animal was injected with normal saline into its sub-plantar region of hind paw. In groups 2-7, hind paw oedema was induced by injection of LPS. One hour before injections, groups 1 (Ctrl) and 2 (LPS) were treated orally with distilled water, 3 and 4 with methylprednisolone (Pred) and meloxicam (Melo) and 5-7 with minocycline in doses of 50, 150 and 450 mg/kg (M50, M150 and M450, respectively). The 8th group (MC) was given minocycline (150 mg/kg) orally and normal saline was injected into sub-plantar region. Paw swelling and body temperature were assessed at 0, 2, 4, 6 and 24 h post-injections. At 24 h, samples of blood and liver, kidney, spleen and hind paw tissues were taken for haematological and histopathological examinations. Some samples of the paw were also obtained for molecular analysis of some inflammatory-related cytokines at mRNA level. Paw swelling and body temperature increased in all LPS-injected groups 2 h post-injection. In LPS group, they remained significantly increased up to 24 h; however, these parameters decreased to normal in Pred, Melo and all minocycline groups. The histological findings showed mild-to-moderate signs of inflammation in tissue samples of groups 2-6, but not in group M450. Additionally, gene expression of pro-inflammatory cytokines (IL-1β and IL-6) increased significantly in LPS group compared to other groups. In conclusion, this study supports the role of minocycline as an anti-inflammatory agent with effects comparable to those of meloxicam and methylprednisolone.

A Novel Multicellular Placental Barrier Model to Investigate the Effect of Maternal Aflatoxin B1 Exposure on Fetal-Side Neural Stem Cells

Ingestion of food toxins such as aflatoxin B₁ (AFB₁) during pregnancy may impair fetal neurodevelopment. However, animal model results may not be accurate due to the species' differences, and testing on humans is ethically impermissible. Here, we developed an in vitro human maternal-fetal multicellular model composed of a human hepatic compartment, a bilayer placental barrier, and a human fetal central nervous system compartment using neural stem cells (NSCs) to investigate the effect of AFB₁ on fetal-side NSCs. AFB₁ passed through the HepG2 hepatocellular carcinoma cells to mimic the maternal metabolic effects. Importantly, even at the limited concentration (0.0641 ± 0.0046 μM) of AFB_1, close to the national safety level standard of China (GB-2761-2011), the mixture of AFB₁ crossing the placental barrier induced NSC apoptosis. The level of reactive oxygen species in NSCs was significantly elevated and the cell membrane was damaged, causing the release of intracellular lactate dehydrogenase (p < 0.05). The comet experiment and γ-H2AX immunofluorescence assay showed that AFB₁ caused significant DNA damage to NSCs (p < 0.05). This study provided a new model for the toxicological evaluation of the effect of food mycotoxin exposure during pregnancy on fetal neurodevelopment.

The role of MAPK/NF-κB-associated microglial activation in T-2 toxin-induced mouse learning and memory impairment

T-2 toxin is a mycotoxin with multiple toxic effects and has emerged as an important food pollutant. Microglia play a significant role in the toxicity of various neurotoxins. However, whether they participate in the neurotoxicity of T-2 toxin has not been reported. To clarify this point, an in vivo mouse model of T-2 toxin (4 mg/kg) poisoning was established. The results of Morris water maze and open-field showed that T-2 toxin induced learning and memory impairment and locomotor inhibition. Meanwhile, T-2 toxin induced microglial activation, while inhibiting microglia activation by minocycline (50 mg/kg) suppressed the toxic effect of the T-2 toxin. To further unveil the potential mechanisms involved in T-2 toxin-induced microglial activation, an in vitro model of T-2 toxin (0, 2.5, 5, 10 ng/mL) poisoning was established using BV-2 cells. Transcriptomic sequencing revealed lots of differentially expressed genes related to MAPK/NF-κB pathway. Western blotting results further confirmed that T-2 toxin (5 ng/mL) induced the activation of MAPKs and their downstream NF-κB. Moreover, the addition of inhibitors of NF-κB and MAPKs reversed the microglial activation induced by T-2 toxin. Overall, microglial activation may contribute a considerable role in T-2 toxin-induced behavioral abnormalities, which could be MAPK/NF-κB pathway dependent.

May phytophenolics alleviate aflatoxins-induced health challenges? A holistic insight on current landscape and future prospects

The future GCC-connected environmental risk factors expedited the progression of nCDs. Indeed, the emergence of AFs is becoming a global food security concern. AFs are lethal carcinogenic mycotoxins, causing damage to the liver, kidney, and gastrointestinal organs. Long-term exposure to AFs leads to liver cancer. Almost a variety of food commodities, crops, spices, herbaceous materials, nuts, and processed foods can be contaminated with AFs. In this regard, the primary sections of this review aim to cover influencing factors in the occurrence of AFs, the role of AFs in progression of nCDs, links between GCC/nCDs and exposure to AFs, frequency of AFs-based academic investigations, and world distribution of AFs. Next, the current trends in the application of PPs to alleviate AFs toxicity are discussed. Nearly, more than 20,000 published records indexed in scientific databases have been screened to find recent trends on AFs and application of PPs in AFs therapy. Accordingly, shifts in world climate, improper infrastructures for production/storage of food commodities, inconsistency of global polices on AFs permissible concentration in food/feed, and lack of the public awareness are accounting for a considerable proportion of AFs damages. AFs exhibited their toxic effects by triggering the progression of inflammation and oxidative/nitrosative stress, in turn, leading to the onset of nCDs. PPs could decrease AFs-associated oxidative stress, genotoxic, mutagenic, and carcinogenic effects by improving cellular antioxidant balance, regulation of signaling pathways, alleviating inflammatory responses, and modification of gene expression profile in a dose/time-reliant fashion. The administration of PPs alone displayed lower biological properties compared to co-treatment of these metabolites with AFs. This issue might highlight the therapeutic application of PPs than their preventative content. Flavonoids such as quercetin and oxidized tea phenolics, curcumin and resveratrol were the most studied anti-AFs PPs. Our literature review clearly disclosed that considering PPs in antioxidant therapies to alleviate complications of AFs requires improvement in their bioavailability, pharmacokinetics, tissue clearance, and off-target mode of action. Due to the emergencies in the elimination of AFs in food/feedstuffs, further large-scale clinical assessment of PPs to decrease the consequences of AFs is highly required.

Does Bentonite Cause Cytotoxic and Whole-Transcriptomic Adverse Effects in Enterocytes When Used to Reduce Aflatoxin B1 Exposure?

Aflatoxin B1 (AFB1) is a major food safety concern, threatening the health of humans and animals. Bentonite (BEN) is an aluminosilicate clay used as a feed additive to reduce AFB1 presence in contaminated feedstuff. So far, few studies have characterized BEN toxicity and efficacy in vitro. In this study, cytotoxicity (WST-1 test), the effects on cell permeability (trans-epithelial electrical resistance and lucifer yellow dye incorporation), and transcriptional changes (RNA-seq) caused by BEN, AFB1 and their combination (AFB1 + BEN) were investigated in Caco-2 cells. Up to 0.1 mg/mL, BEN did not affect cell viability and permeability, but it reduced AFB1 cytotoxicity; however, at higher concentrations, BEN was cytotoxic. As to RNA-seq, 0.1 mg/mL BEN did not show effects on cell transcriptome, confirming that the interaction between BEN and AFB1 occurs in the medium. Data from AFB1 and AFB1 + BEN suggested AFB1 provoked most of the transcriptional changes, whereas BEN was preventive. The most interesting AFB1-targeted pathways for which BEN was effective were cell integrity, xenobiotic metabolism and transporters, basal metabolism, inflammation and immune response, p53 biological network, apoptosis and carcinogenesis. To our knowledge, this is the first study assessing the in vitro toxicity and whole-transcriptomic effects of BEN, alone or in the presence of AFB1.

Metabolic Disruption by Naturally Occurring Mycotoxins in Circulation: A Focus on Vascular and Bone Homeostasis Dysfunction

Naturally occurring food/feed contaminants have become a significant global issue due to animal and human health implications. Despite risk assessments and legislation setpoints on the mycotoxins' levels, exposure to lower amounts occurs, and it might affect cell homeostasis. However, the inflammatory consequences of this possible everyday exposure to toxins on the vascular microenvironment and arterial dysfunction are unexplored in detail. Circulation is the most accessible path for food-borne toxins, and the consequent metabolic and immune shifts affect systemic health, both on vascular apparatus and bone homeostasis. Their oxidative nature makes mycotoxins a plausible underlying source of low-level toxicity in the bone marrow microenvironment and arterial dysfunction. Mycotoxins could also influence the function of cardiomyocytes with possible injury to the heart. Co-occurrence of mycotoxins can modulate the metabolic pathways favoring osteoblast dysfunction and bone health losses. This review provides a novel insight into understanding the complex events of coexposure to mixed (low levels) mycotoxicosis and subsequent metabolic/immune disruptions contributing to chronic alterations in circulation.

Gasdermin D-mediated microglial pyroptosis exacerbates neurotoxicity of aflatoxins B1 and M1 in mouse primary microglia and neuronal cultures

Aflatoxin B1 (AFB1) disrupts the blood-brain barrier by poisoning the vascular endothelial cells and astrocytes that maintain it. It is important to examine whether aflatoxin B1 or its metabolite, aflatoxin M1 (AFM1), affect microglia, which as the "immune cells" in the brain may amplify their damaging effects. Here we evaluated the toxicity of AFB1 and AFM1 against primary microglia and found that both aflatoxins decreased the viability of primary microglia and increased the leakage of lactate dehydrogenase, gamma-H2AX expression, nuclear lysis, necrosis and apoptosis in a dose-dependent manner. The potential contribution of microglia to the toxic effects of aflatoxins was assessed in transwell co-culture experiments involving microglia, neurons, astrocytes, oligodendrocytes or neural stem/precursor cells. And we found that the toxic effects of both aflatoxins on various types of nervous system cells were greater in the presence of microglia than in their absence. We also found that both aflatoxins induced gasdermin D-mediated microglial pyroptosis and inflammatory cytokine expression by activating the NLRP3 inflammasome. Blockade of gasdermin D activity in AFB1- or AFM1-treated primary microglia using dimethyl fumarate (DMF) reduced the release of IL-1β, IL-18 and nitric oxide, as well as the neurotoxicity of microglia-conditioned medium to neurons, astrocytes, oligodendrocytes and neural stem/precursor cells. These data suggested that the toxicity of AFB1 and AFM1 on various cells of the central nervous system is due, remarkably, the gasdermin D-mediated microglial pyroptosis exacerbates their neurotoxicity.

Prevalence of Aspergillus-Derived Mycotoxins (Ochratoxin, Aflatoxin, and Gliotoxin) and Their Distribution in the Urinalysis of ME/CFS Patients

Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is a known complex, multi-organ system disorder with a sudden or subacute onset. ME/CFS occurs most commonly among women between 30 and 50 years of age. The current diagnostic criteria of ME/CFS, as defined by the Centers for Disease Control and Prevention, includes: profound fatigue and post-exertional malaise (>6 mo) unrelieved by rest, persistent cognitive impairment or orthostatic intolerance, and chronic unrefreshing sleep. Despite reported associations between ME/CFS onset and exposure to infectious agents (viral, bacterial, or fungal), the pathophysiology of ME/CFS remains unknown. In this prevalence study, we investigated the rates of Aspergillus-derived toxin levels, Aflatoxin (AF), Ochratoxin A (OTA), and Gliotoxin (GT), in the urinalysis of 236 ME/CFS patients with a history of chronic exposure to mold (i.e., from water-damaged buildings). Among ME/CFS patients reporting chronic exposure to mold, we found evidence of exposure in 92.4 percent of patients, with OTA being the most prevalent mycotoxin. Mold distributions (OTA, AF, and GT) in the urinalysis all demonstrated right skewness, while the distribution of age of ME/CFS patients diagnosed showed no deviation from normality. This study aims to provide preliminary, epidemiological evidence among ME/CFS patients who were diagnosed in South Florida with a history of exposure to mycotoxins. Based on these findings, we proposed how future control studies should approach investigating the association between chronic mold exposure and the diagnosis of ME/CFS.

Aflatoxin B1 induces microglia cells apoptosis mediated by oxidative stress through NF-κB signaling pathway in mice spinal cords

Many studies have shown that aflatoxin B1 (AFB1) can cause cytotoxicity in numerous cells and organs induced by oxidative stress. However, the toxic effects and related mechanism of AFB1 on the microglia cells in the spinal cords have not been studied yet. Our results showed that AFB1 significantly reduced the number of microglia cells, increased the oxidants (malonaldehyde and hydrogen peroxide) but decreased the anti-oxidants (superoxide dismutase and total antioxidant capacity) in a dose dependent manner in mice spinal cords. In addition, AFB1 significantly increased the oxidative stress, promoted apoptosis and cell cycle arrest in G2-M phase, and activated NF-κB phosphorylation in BV2 microglia cells. However, the addition of active oxygen scavenger N-acetylcysteine can significantly reduce the ROS production, improve cell cycle arrest, reduce apoptosis, and the expression of phosphorylated NF-κB in BV2 microglia cells. These results indicate that AFB1 induces microglia cells apoptosis through oxidative stress by activating NF-κB signaling pathway.

Preventive Efficiency of Chelidonium majus Ethanolic Extract Against Aflatoxin B1 Induced Neurochemical Deteriorations in Rats

&lt;b&gt;Background and Objective:&lt;/b&gt; Aflatoxins affect many species including humans and animals, therefore the present study was designed to investigate the protective effect of &lt;i&gt;Chelidonium majus&lt;/i&gt; Ethanolic Extract (CMEE) on neurotoxicity induced by Aflatoxin B&lt;sub&gt;1&lt;/sub&gt; (AFB1) in rats. &lt;b&gt;Materials and Methods:&lt;/b&gt; Four groups of male Albino rats were treated orally for 28 days as follows: (1) Control group was daily given DMSO-PBS buffer (1.0 mL per rat), (2) CMEE (300 mg kg&lt;sup&gt;1&lt;/sup&gt;/day) dissolved in DMSO-PBS buffer, (3) AFB1 (80 μg kg&lt;sup&gt;1&lt;/sup&gt;/day) dissolved in DMSO-PBS buffer and (4) Received daily AFB1 (300 mg kg&lt;sup&gt;1&lt;/sup&gt;) in combination with CMEE (300 mg kg&lt;sup&gt;1&lt;/sup&gt;). &lt;b&gt;Results:&lt;/b&gt; CMEE exhibits antioxidant activity &lt;i&gt;in vitro&lt;/i&gt; and neuroameliorative efficiency &lt;i&gt;in vivo&lt;/i&gt; as its administration in combination with AFB1 succeeded significantly in down regulating the elevated levels of inflammatory and apoptotic markers and restoring the values of neurochemical markers (AChE-ase, dopamine and serotonin) that were deteriorated by AFB1 intake. &lt;b&gt;Conclusion:&lt;/b&gt; In conclusion, the neuroprotective effect of CMEE may be mediated through its antioxidant and free radical scavenging activity that proved from the data&lt;i&gt; &lt;/i&gt;of ferric-reducing power ability and DPPH radical scavenging activity.

Food-Origin Mycotoxin-Induced Neurotoxicity: Intend to Break the Rules of Neuroglia Cells

Mycotoxins are key risk factors in human food and animal feed. Most of food-origin mycotoxins could easily enter the organism and evoke systemic toxic effects, such as aflatoxin B1 (AFB1), ochratoxin A (OTA), T-2 toxin, deoxynivalenol (DON), zearalenone (ZEN), fumonisin B1 (FB1), and 3-nitropropionic acid (3-NPA). For the last decade, the researches have provided much evidences in vivo and in vitro that the brain is an important target organ on mycotoxin-mediated neurotoxic phenomenon and neurodegenerative diseases. As is known to all, glial cells are the best regulator and defender of neurons, and a few evaluations about the effects of mycotoxins on glial cells such as astrocytes or microglia have been conducted. The fact that mycotoxin contamination may be a key factor in neurotoxicity and glial dysfunction is exactly the reason why we reviewed the activation, oxidative stress, and mitochondrial function changes of glial cells under mycotoxin infection and summarized the mycotoxin-mediated glial cell proliferation disorders, death pathways, and inflammatory responses. The purpose of this paper is to analyze various pathways in which common food-derived mycotoxins can induce glial toxicity and provide a novel perspective for future research on the neurodegenerative diseases.

Therapeutic potential of beta-caryophyllene against aflatoxin B1-Induced liver toxicity: biochemical and molecular insights in rats

Aflatoxin B₁ (AFB₁) is a mycotoxin highly toxic and carcinogenic to humans due to its potential to induce oxidative stress. The Beta-caryophyllene (BCP) have been highlighted for its broad spectrum of pharmacological effects. The present study aimed to investigate the beneficial effects of BCP against the susceptibility of hepatic and renal tissues to AFB₁ toxicity, in biochemical parameters to assess organ function, tissue oxidation, and the immunocontent of oxidative and inflammatory proteins. Male Wistar rats was exposed to AFB₁ (250 μg/kg, i.g.) and/or BCP (100 mg/kg, i.p.) for 14 successive days. It was found that exposure to AFB₁ did not change the measured renal toxicity parameters. Also, AFB₁ increased liver injury biomarkers (gamma glutamyl transferase and alkaline phosphatase) and reduced levels of non-enzymatic antioxidant defenses (ascorbic acid and non-protein thiol), however did not cause changes in the lipid peroxidation levels. Moreover, AFB₁ interfered in oxidative pathway regulated by Kelch-like ECH-associated protein (Keap1)/nuclear factor (erythroid-derived 2)-like 2 (Nrf2), overacting Glutathione-S-Transferase (GST) activity. Lastly, a main effect of AFB₁ on the total interleukin 1 beta (IL-1β) was observed. Remarkably, the associated treatment of AFB₁ + BCP improved altered liver parameters. In addition, BCP and AFB₁ + BCP groups showed an increase in the levels of inhibitor of nuclear factor kappa-B kinase subunit beta (IKKβ). Thus, these results indicated that BCP has potential protective effect against AFB₁ induced hepatotoxicity.

The role of mycotoxins in neurodegenerative diseases: current state of the art and future perspectives of research

Mycotoxins are fungal metabolites that can cause various diseases in humans and animals. The adverse health effects of mycotoxins such as liver failure, immune deficiency, and cancer are well-described. However, growing evidence suggests an additional link between these fungal metabolites and neurodegenerative diseases. Despite the wealth of these initial reports, reliable conclusions are still constrained by limited access to human patients and availability of suitable cell or animal model systems. This review summarizes knowledge on mycotoxins associated with neurodegenerative diseases and the assumed underlying pathophysiological mechanisms. The limitations of the common in vivo and in vitro experiments to identify the role of mycotoxins in neurotoxicity and thereby in neurodegenerative diseases are elucidated and possible future perspectives to further evolve this research field are presented.

Neuroimmune disruptions from naturally occurring levels of mycotoxins

Substantial pieces of evidence support the potential of exogenous toxins in disrupting neuroimmune homeostasis. It appears that mycotoxins are one of the noticeable sources of naturally occurring substances dysregulating the immune system, which involves the physiology of many organs, such as the central nervous system (CNS). The induction of inflammatory responses in microglial cells and astrocytes, the CNS resident cells with immunological characteristics, could interrupt the hemostasis upon even with low-level exposure to mycotoxins. The inevitable widespread occurrence of a low level of mycotoxins in foods and feed is likely increasing worldwide, predisposing individuals to potential neuroimmunological dysregulations. This paper reviews the current understanding of mycotoxins' neuro-immunotoxic features under low-dose exposure and the possible ways for detoxification and clearance as a perspective.

Targeting HMGB1 inhibits T-2 toxin-induced neurotoxicity via regulation of oxidative stress, neuroinflammation and neuronal apoptosis

T-2 toxin, a food-derived mycotoxin, has been identified as a neurotoxin. Nonetheless, T-2 toxin-induced neuroinflammation has never been revealed. As an important therapeutic target for inflammatory diseases and cancers, the role of high mobility group B1 (HMGB1) in mycotoxin-mediated neurotoxicity remains a mystery. In current study, we found that PC12 cells were sensitive to trace amounts of T-2 toxin less than 12 ng/mL, distinguished by decreased cell viability and increased release of lactate dehydrogenase (LDH). Oxidative stress and mitochondrial damage were observed in PC12 cells, manifested as accumulation of oxidative stress products, up-regulation of Nrf2/HO-1 pathway and decrease of mitochondrial membrane potential (MMP), leading to mitochondria-dependent apoptosis. Meanwhile, we first discovered that tiny amounts of T-2 toxin triggered neuroinflammation directly, including raising the expression and translocation of NF-κB and promoting secretion of proinflammatory cytokines such as TNF-α, IL-6, IL-8 and IL-1β. Most interestingly, the increased of HMGB1 was detected both inside and outside the cells. Conversely, HMGB1 siRNA reduced T-2 toxin-mediated oxidative stress, apoptosis and neuroinflammatory outbreak, accompanied by lessened caspase-3 and caspase-9, and decreased secretion of pro-inflammatory cytokines. Taken together, T-2 toxin-stimulated PC12 cells simultaneously displayed apoptosis and inflammation, whereas HMGB1 played a critical role in these neurotoxic processes.

The Scourge of Aflatoxins in Kenya: A 60-Year Review (1960 to 2020)

Aflatoxins are endemic in Kenya. The 2004 outbreak of acute aflatoxicosis in the country was one of the unprecedented epidemics of human aflatoxin poisoning recorded in mycotoxin history. In this study, an elaborate review was performed to synthesize Kenya’s major findings in relation to aflatoxins, their prevalence, detection, quantification, exposure assessment, prevention, and management in various matrices. Data retrieved indicate that the toxins are primarily biosynthesized by Aspergillus flavus and A. parasiticus, with the eastern part of the country reportedly more aflatoxin-prone. Aflatoxins have been reported in maize and maize products (Busaa, chan’gaa, githeri, irio, muthokoi, uji, and ugali), peanuts and its products, rice, cassava, sorghum, millet, yams, beers, dried fish, animal feeds, dairy and herbal products, and sometimes in tandem with other mycotoxins. The highest total aflatoxin concentration of 58,000 μg/kg has been reported in maize. At least 500 acute human illnesses and 200 deaths due to aflatoxins have been reported. The causes and prevalence of aflatoxins have been grossly ascribed to poor agronomic practices, low education levels, and inadequate statutory regulation and sensitization. Low diet diversity has aggravated exposure to aflatoxins in Kenya because maize as a dietetic staple is aflatoxin-prone. Detection and surveillance are only barely adequate, though some exposure assessments have been conducted. There is a need to widen diet diversity as a measure of reducing exposure due to consumption of aflatoxin-contaminated foods.

Grape Seed Waste Counteracts Aflatoxin B1 Toxicity in Piglet Mesenteric Lymph Nodes

Aflatoxin B1 (AFB1) is a mycotoxin that frequently contaminates cereals and cereal byproducts. This study investigates the effect of AFB1 on the mesenteric lymph nodes (MLNs) of piglets and evaluates if a diet containing grape seed meal (GSM) can counteract the negative effect of AFB1 on inflammation and oxidative stress. Twenty-four weaned piglets were fed the following diets: Control, AFB1 group (320 μg AFB1/kg feed), GSM group (8% GSM), and AFB1 + GSM group (8% GSM + 320 μg AFB1/kg feed) for 30 days. AFB1 has an important antioxidative effect by decreasing the activity of catalase (CAT), superoxide dismutase (SOD), and glutathione peroxidase (GPx) and total antioxidant status. As a result of the exposure to AFB1, an increase of MAP kinases, metalloproteinases, and cytokines, as effectors of an inflammatory response, were observed in the MLNs of intoxicated piglets. GSM induced a reduction of AFB1-induced oxidative stress by increasing the activity of GPx and SOD and by decreasing lipid peroxidation. GSM decreased the inflammatory markers increased by AFB1. These results represent an important and promising way to valorize this waste, which is rich in bioactive compounds, for decreasing AFB1 toxic effects in mesenteric lymph nodes.

Curcumin Mitigates AFB1-Induced Hepatic Toxicity by Triggering Cattle Antioxidant and Anti-inflammatory Pathways: A Whole Transcriptomic In Vitro Study

Aflatoxin B1 (AFB1) toxicity in livestock and human beings is a major economic and health concern. Natural polyphenolic substances with antioxidant properties have proven to be effective in ameliorating AFB1-induced toxicity. Here we assessed the potential anti-AFB1 activity of curcumin (pure curcumin, C, and curcumin from Curcuma longa, CL) in a bovine fetal hepatocyte-derived cell line (BFH12). First, we measured viability of cells exposed to AFB1 in presence or absence of curcumin treatment. Then, we explored all the transcriptional changes occurring in AFB1-exposed cells cotreated with curcumin. Results demonstrated that curcumin is effective in reducing AFB1-induced toxicity, decreasing cells mortality by approximately 30%. C and CL induced similar transcriptional changes in BFH12 exposed to AFB1, yet C treatment resulted in a larger number of significant genes compared to CL. The mitigating effects of curcuminoids towards AFB1 toxicity were mainly related to molecular pathways associated with antioxidant and anti-inflammatory response, cancer, and drug metabolism. Investigating mRNA changes induced by curcumin in cattle BFH12 cells exposed to AFB1 will help us to better characterize possible tools to reduce its consequences in this susceptible and economically important food-producing species.

Neurotoxic effects of aflatoxin B1 on human astrocytes in vitro and on glial cell development in zebrafish in vivo

Aflatoxin B1 is one of the well-known mycotoxins and mainly found in contaminated animal feed and various agricultural products inducing acute and chronic toxicology, tumor, and abnormal neural development. However, the effects of aflatoxin B1 on the human brain, especially on astrocytes, have not been studied in depth. In the present study, we studied the neurotoxic effects of aflatoxin B1, in vitro and in vivo. Aflatoxin B1 decreased the proliferation and stopped cell cycle progression at the sub G0/G1 stage with an increase in BAX, BAK, and cytochrome c proteins in human astrocytes. In addition, it increased the mitochondrial depolarization, oxidative stress, and calcium influx in both the cytosol and mitochondria. Surprisingly, inhibition of calcium overload in the cytosol and mitochondria, using calcium chelators and an inhibitor, partially rescued the proliferation of aflatoxin B1-treated astrocytes. Based on the toxicity assays using zebrafish models, aflatoxin B1 decreased the embryo survival rate with physiological changes and an increase in the caspase and tp53 genes. It also decreased the expression of gfap, mbp, and olig2 in the transgenic zebrafish embryo's brain and axon. Our results revealed the specific mechanism of the neurotoxic effects of aflatoxin B1 on human astrocytes and zebrafish glial cells.

Fucoidan Ameliorates Oxidative Stress, Inflammation, DNA Damage, and Hepatorenal Injuries in Diabetic Rats Intoxicated with Aflatoxin B1

The current study was carried out to evaluate the ameliorative effect of fucoidan against aflatoxicosis-induced hepatorenal toxicity in streptozotocin-induced diabetic rats. Sixty-four Wister albino male rats were randomly assigned into eight groups (8 rats each) that received normal saline, fucoidan (FUC) at 100 mg/kg/day orally for 4 weeks, streptozotocin (STZ) at 50 mg/kg/i.p. single dose, STZ plus FUC, aflatoxin B₁ (AFB₁) at 50 μg/kg/i.p. after one month of the beginning of the experiment for 2 weeks, AFB₁ plus FUC, STZ plus AFB₁, or STZ plus AFB₁ and FUC. Injection of rats with STZ induced hyperglycemia. Rats with STZ-induced diabetes, with or without AFB₁ intoxication, had significantly elevated activities of serum aspartate aminotransferase, alanine aminotransferase, and alkaline phosphatase, and levels of serum urea, creatinine, cholesterol, 8-oxo-2′-deoxyguanosine, interleukin-1β, interleukin-6, and tumor necrosis factor-α. In addition, these rats exhibited increased lipid peroxidation and reduced glutathione concentration and activities of superoxide dismutase, catalase, and glutathione peroxidase enzymes in the hepatic and renal tissues. In contrast, administration of FUC to diabetic rats, with or without AFB₁ intoxication, ameliorated the altered serum parameters, reduced oxidative stress, DNA damage, and inflammatory biomarkers, and enhanced the antioxidant defense system in the hepatic and renal tissues. These results indicated that FUC ameliorated diabetes and AFB₁-induced hepatorenal injuries through alleviating oxidative stress, DNA damage, and inflammation.

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.

Naturally Occurring Level of Aflatoxin B1 Injures Human, Canine and Bovine Leukocytes Through ATP Depletion and Caspase Activation

Aflatoxin (AF) B₁ is a potent hepatotoxic, mutagenic, teratogenic mycotoxin and may cause immune suppression/dysregulation in humans and animals. Toxic effects of AFB₁ on key mammalian immune cells (ie, leukocytes) needs to be mechanistically elucidated. In this study, along with the determination of AFB₁'s LC₅₀ for certain leukocytes, we analyzed the effect of naturally occurring levels of AFB₁ on apoptosis/necrosis of neutrophils, lymphocytes, and monocytes from healthy young humans (20- to 25-year-old male), dogs (1- to 2-year-old Persian/herd breed), and cattle (1- to 2-year-old cattle). Leukocytes were incubated for approximately 24 hours with naturally occurring levels of AFB₁ (10 ng/mL). Intracellular adenosine triphosphate (ATP) depletion and caspase-3/7 activity were then determined by luciferase-dependent bioluminescence (BL). Furthermore, the necrotic leukocytes were measured using propidium iodide (PI)-related flow cytometry. A significant decrease (24%-45%, 33.2% ± 2.7%) in intracellular ATP content was observed in AFB₁-treated neutrophils, lymphocytes, and monocytes in all studied mammals. Also, with such a low level (10 ng/mL) of AFB₁, BL-based caspase-3/7 activity (BL intensity) in all 3 tested mammalian leukocyte lineages was noticeably increased (∼>2-fold). Flow cytometry-based PI staining (for viability assay) of the AFB₁-treated leukocytes showed slightly/insignificantly more increase of necrotic (PI⁺) neutrophils, lymphocytes, and monocytes in human, dogs, and cattle. Even though in vitro LC₅₀s for AFB_1' (∼20,000-40,000 ng/mL) were approximately 2,000 to 4,000 times higher than background, these studies demonstrate leukocytes from human and farm/companion animals are sensitive to naturally occurring levels of AFB₁. The observed in vitro ATP depletion and caspase activation in AFB₁-exposed leukocytes can partially explain the underlying mechanisms of AFB₁-induced immune disorders in mammals.

Lactobacillus plantarum C88 protects against aflatoxin B1-induced liver injury in mice via inhibition of NF-κB-mediated inflammatory responses and excessive apoptosis

Background

Probiotics play an important role in the human and animal defense against liver damage. However, the protective mechanism of Lactobacillus plantarum C88 on chronic liver injury induced by mycotoxin remains unclear.

Results

In this study, the addition of L. plantarum C88 obviously ameliorated the increased contents of alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), total cholesterol and triglyceride, the diminish contents of total protein and albumin in serum of mice challenged with AFB₁. Simultaneously, L. plantarum C88 attenuated the inflammatory response via significantly reducing the levels of pro-inflammatory factors, including interleukin-1β (IL-1β), IL-6, IL-8, interferon-γ (IFN-γ) and tumor necrosis factor-α (TNF-α) in serum. Furthermore, L. plantarum C88 remarkably down-regulated the nuclear factor kappa B (NF-κB) signaling pathways by weakening the expression of toll-like receptor 2 (TLR2) and TLR4, and inhibited NF-κB nuclear translocation through enhancing the expression of NF-κB inhibitor (IκB). Neutralization experiments confirmed that L. plantarum C88 decreased the levels of some pro-inflammatory factors due to the suppression of the NF-κB signaling pathways. Besides, L. plantarum C88 decreased the levels of Bax and Caspase-3, elevated the level of Bcl-2, and reduced mRNA expressions of Fatty acid synthetase receptor (Fas), FAS-associated death domain (FADD), TNF receptor associated death domain (TRADD) and Caspase-8 in the liver.

Conclusions

Probiotic L. plantarum C88 prevented AFB₁-induced secretion of pro-inflammatory cytokines by modulating TLR2/NF-κB and TLR4/NF-κB pathways. The molecular mechanisms of L. plantarum C88 in ameliorating AFB₁-induced excessive apoptosis included regulating the mitochondrial pathway and cell death receptor pathways.

Electronic supplementary material

The online version of this article (10.1186/s12866-019-1525-4) contains supplementary material, which is available to authorized users.

HPLC quantitation of aflatoxin B1 from fungal mycelium culture

Aflatoxins are mycotoxins that contaminate agricultural products when infected by toxigenic Aspergillus flavus. Methods for quantifying aflatoxin from culture using chromatography are available but are not optimized for population studies. We provide details of a method for preparation and quantitation of aflatoxin B₁ from fungal cultures that satisfy those needs.

Bioluminescence-based detection of astrocytes apoptosis and ATP depletion induced by biologically relevant level aflatoxin B1

Although brain accumulation of aflatoxin B1 (AFB1) suggests potential impact on brain cells, including astrocytes, there still exists a scarcity of research on this issue within the literature. This research investigates the apoptosis effect of AFB1 on primary mouse astrocytes. To this aim, a MTT colorimetric assay on astrocytes was performed to measure the toxicity/LC50 of various concentrations (0-320,000 nM) of AFB1 for 24 h. Further, the astrocytes were exposed to concentrations of 8, 16 and 32 nM of AFB1 for 24, 48 and 72 h. Concentration of intracellular ATP) and caspase-3/7 activity was then determined by luciferase-dependent bioluminescence. Furthermore, the percentage of apoptotic cells was obtained using flow cytometry (annexin V+/propidium iodide (PI)−; cytochrome c release from mitochondria, a hallmark of cell damage, was carried out by Western blot as well. MTT assay at post-exposure hours (PEH) 24 revealed that the LC50 of AFB1 was ~80,000 nM. Though at PEH 48 only 32 nM of AFB1 resulted in a significant diminished intracellular ATP content, at PEH 72 both 8 and 32 nM of AFB1 led to a significant ATP depletion in astrocytes. Similar patterns of changes were observed in bioluminescence intensity of AFB1-treated astrocytes. Flow cytometry-based annexin V and PI staining of astrocytes at PEH 24, 48 and 72 showed that 32 nM of AFB1 significantly and time dependently increased the percentage of apoptotic astrocytes (annexin V+/PI−). With 32 nM of AFB1, caspase-3/7 activity in astrocytes was increased ~4-fold at PEH 72. A remarkable release of cytochrome c was only detected in astrocytes exposed to 32 nM AFB1 for PEH 72. The results indicated that a biologically relevant level of AFB1 (32 nM) induces apoptosis in astrocytes through ATP depletion and caspases activation.

Gliotoxin penetrates and impairs the integrity of the human blood-brain barrier in vitro

Cerebral fungal infections represent an important public health concern, where a key element of pathophysiology is the ability of the fungi to cross the blood-brain barrier (BBB). Yet the mechanism used by micro-organisms to cross such a barrier and invade the brain parenchyma remains unclear. This study investigated the effects of gliotoxin (GTX), a mycotoxin secreted by Aspergillus fumigatus, on the BBB using brain microvascular endothelial cells (BMECs) derived from induced pluripotent stem cells (iPSCs). We observed that both acute (2 h) and prolonged (24 h) exposure to GTX at the level of 1 μM or higher compromised BMECs monolayer integrity. Notably, acute exposure was sufficient to disrupt the barrier function in iPSC-derived BMECs, resulting in decreased transendothelial electrical resistance (TEER) and increased fluorescein permeability. Further, our data suggest that such disruption occurred without affecting tight junction complexes, via alteration of cell-matrix interactions, alterations in F-actin distribution, through a protein kinase C-independent signaling. In addition to its effect on the barrier function, we have observed a low permeability of GTX across the BBB. This fact can be partially explained by possible interactions of GTX with membrane proteins. Taken together, this study suggests that GTX may contribute in cerebral invasion processes of Aspergillus fumigatus by altering the blood-brain barrier integrity without disrupting tight junction complexes.

Human Microglial Cells Undergo Proapoptotic Induction and Inflammatory Activation upon in vitro Exposure to a Naturally Occurring Level of Aflatoxin B1

OBJECTIVE

Knowledge regarding interactions of AFB1 with the human nervous system and how a naturally occurring level of AFB1 could potentially induce neuroimmune dysregulation is very limited. To assess the cellular effects of AFB1 on the human brain, we used the human microglia cell line CHME5 as a model to pinpoint its potential in vivo translation.

METHODS

We used the CHME5 cell line culture system, multiplex qPCR, (chemi)bioluminescence, Luminex ELISA, and flow cytometry assays to evaluate the toxic effects of a naturally occurring level of AFB1 on human microglia.

RESULTS

A low concentration of AFB1 upregulates the mRNA expression of many proinflammatory molecules, such as TLRs, MyD88, NFκB, and CxCr4, induces intracellular ATP depletion, and increases caspase-3/7 activity at different time points following exposure to the toxin. Furthermore, AFB1-exposed microglia secreted significantly higher levels of IFN-γ and GM-CSF after treatment. We also observed a slight increase in the percentage of apoptotic microglia (annexin V+/PI-) at 48 h posttreatment.

CONCLUSION

Our work confirmed that the environmentally relevant level of AFB1 could cause an inflammatory reaction in human microglial cells that is potentially harmful or toxic to the homeostasis of the human central nervous system and might increase susceptibility to neurodegenerative diseases.