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

HLA gene variations and mycotoxin toxicity: Four case reports

Mycotoxins are produced by certain molds that can cause many health effects. We present four human cases of prolonged consistent mycotoxins exposure linked to genetic variations in human leukocyte antigen (HLA) alleles. The HLA-DR/DQ isotype alleles are linked to mycotoxins susceptibility due to the lack of proper immune response; individuals with these alleles are poor eliminators of mycotoxins from their system. Four subjects with variations in their HLA-DR alleles were exposed to mycotoxins from living in mold-infested houses and experienced persistent mold-related symptoms long after moving out from the mold-infested houses and only exposed to the levels of molds found in the ambient air. From one of the subjects, two urine samples were collected ~ 18 months apart after the cessation of exposure. Urinary elimination rate was extremely slow for two of the mycotoxins (ochratoxin A [OTA] and mycophenolic acid [MPA]) detected in both samples. In 18 months, decline in OTA level was only ~ 3-fold (estimated t½ of ~ 311 days) and decline in MPA level was ~ 11-fold (estimated t½ of ~ 160 days), which was ~ 10- and ~ 213-fold slower than expected in individuals without HLA-DR alleles, respectively. We estimated that ~ 4.3 and ~ 2.2 years will be required for OTA and MPA to reach < LLQ in urine, respectively. Three other subjects with variations in HLA-DR alleles were members of a family who lived in a mold-infested house for 4 years. They kept experiencing mold-related issues >2 years after moving to a non-mold-infested house. Consistent exposure was confirmed by the presence of several mycotoxins in urine >2 years after the secession of higher than background (from outdoor ambient air) exposure. This was consistent with the extremely slow elimination of mycotoxins from their system. Variations in HLA-DR alleles can, consequently, make even short periods of exposure to chronic exposure scenarios with related adverse health effects. It is, therefore, important to determine genetic predisposition as a reason for prolonged/lingering mold-related symptoms long after the cessation of higher than background exposure. Increased human exposure to mycotoxins is expected from increased mold infestation that is anticipated due to rising CO2, temperature, and humidity from the climate change with possibly increased adverse health effects, especially in individuals with genetic susceptibility to mold toxicity.

Association of plasma aflatoxin with persistent detection of oncogenic human papillomaviruses in cervical samples from Kenyan women enrolled in a longitudinal study

BACKGROUND

Cervical cancer is caused by oncogenic human papillomaviruses (HR-HPV) and is common among Kenyan women. Identification of factors that increase HR-HPV persistence is critically important. Kenyan women exposed to aflatoxin have an increased risk of HR-HPV detection in cervical specimens. This analysis was performed to examine associations between aflatoxin and HR-HPV persistence.

METHODS

Kenyan women were enrolled in a prospective study. The analytical cohort for this analysis included 67 HIV-uninfected women (mean age 34 years) who completed at least two of three annual study visits and had an available blood sample. Plasma aflatoxin was detected using ultra-high pressure liquid chromatography (UHPLC)-isotope dilution mass spectrometry. Annual cervical swabs were tested for HPV (Roche Linear Array). Ordinal logistic regression models were fitted to examine associations of aflatoxin and HPV persistence.

RESULTS

Aflatoxin was detected in 59.7% of women and was associated with higher risk of persistent detection of any HPV type (OR = 3.03, 95%CI = 1.08-8.55, P = 0.036), HR-HPV types (OR = 3.63, 95%CI = 1.30-10.13, P = 0.014), and HR-HPV types not included in the 9-valent HPV vaccine (OR = 4.46, 95%CI = 1.13-17.58, P = 0.032).

CONCLUSIONS

Aflatoxin detection was associated with increased risk of HR-HPV persistence in Kenyan women. Further studies, including mechanistic studies are needed to determine if aflatoxin synergistically interacts with HR-HPV to increase cervical cancer risk.

Computational Studies of Aflatoxin B1 (AFB1): A Review

Aflatoxin B₁ (AFB₁) exhibits the most potent mutagenic and carcinogenic activity among aflatoxins. For this reason, AFB₁ is recognized as a human group 1 carcinogen by the International Agency of Research on Cancer. Consequently, it is essential to determine its properties and behavior in different chemical systems. The chemical properties of AFB₁ can be explored using computational chemistry, which has been employed complementarily to experimental investigations. The present review includes in silico studies (semiempirical, Hartree-Fock, DFT, molecular docking, and molecular dynamics) conducted from the first computational study in 1974 to the present (2022). This work was performed, considering the following groups: (a) molecular properties of AFB₁ (structural, energy, solvent effects, ground and the excited state, atomic charges, among others); (b) theoretical investigations of AFB₁ (degradation, quantification, reactivity, among others); (c) molecular interactions with inorganic compounds (Ag⁺, Zn²⁺, and Mg²⁺); (d) molecular interactions with environmentally compounds (clays); and (e) molecular interactions with biological compounds (DNA, enzymes, cyclodextrins, glucans, among others). Accordingly, in this work, we provide to the stakeholder the knowledge of toxicity of types of AFB₁-derivatives, the structure-activity relationships manifested by the bonds between AFB₁ and DNA or proteins, and the types of strategies that have been employed to quantify, detect, and eliminate the AFB₁ molecule.

Association of Plasma Aflatoxin With Persistent Detection of Oncogenic Human Papillomaviruses in Cervical Samples From Kenyan Women Enrolled in a Longitudinal Study

Background Cervical cancer is common among Kenyan women and is caused by oncogenic human papillomaviruses (HR-HPV). Identification of factors that increase HR-HPV persistence is critically important. Kenyan women exposed to aflatoxin have an increased risk of cervical HR-HPV detection. This analysis was performed to examine associations between aflatoxin and HR-HPV persistence. Methods Kenyan women were enrolled in a prospective study. The analytical cohort for this analysis included 67 HIV-uninfected women (mean age 34 years) who completed at least two of three annual study visits and had an available blood sample. Plasma aflatoxin was detected using ultra-high pressure liquid chromatography (UHPLC)-isotope dilution mass spectrometry. Annual cervical swabs were tested for HPV (Roche Linear Array). Ordinal logistic regression models were fitted to examine associations of aflatoxin and HPV persistence. Results Aflatoxin was detected in 59.7% of women and was associated with higher risk of persistent detection of any HPV type (OR = 3.03, 95%CI = 1.08-8.55, P = 0.036), HR-HPV types (OR = 3.63, 95%CI = 1.30-10.13, P = 0.014), and HR-HPV types not included in the 9-valent HPV vaccine (OR = 4.46, 95%CI = 1.13-17.58, P = 0.032). Conclusions Aflatoxin detection was associated with increased risk of HR-HPV persistence in Kenyan women. Further studies are needed to determine if aflatoxin synergistically interacts with HR-HPV to increase cervical cancer risk.

Aflatoxin M1 and ochratoxin A induce a competitive endogenous RNA regulatory network of intestinal immunosuppression by whole-transcriptome analysis

Aflatoxin M1 (AFM1) and ochratoxin A (OTA) are common mycotoxins in cereal foods and milk products, and may cause serious negative impacts on human health. The intestine is crucial for immune regulation as it protects host homeostatic health from external contaminants; however, the underlying mechanisms of AFM1 and OTA mediated intestinal immunotoxicity remain unclear. In this study, whole transcriptome analysis was used to characterize BALB/c mouse intestines exposed to individual and combined AFM1 and OTA [3.0 mg/kg body weight (BW)] for 28 days to screen for key intestinal immunotoxicity-related differentially expressed mRNAs (DEmRNAs), differentially expressed microRNAs (DEmiRNAs), differentially expressed long non-coding RNAs (DElncRNAs), and associated enriched signaling pathways. Functional validation was then conducted in intestinal differentiated Caco-2 cells using different inhibitor assays to verify the accuracy of transcriptome and the importance of the key screened regulatory factors. In vivo data revealed that AFM1 and OTA exposure disrupted the intestines and exerted intestinal immunosuppression effects. When compared with AFM1, OTA had stronger intestinal toxicity in combined treatments. Further analyses of competitive endogenous RNA (ceRNA) regulatory networks in mice showed that AFM1 and OTA mediated-intestinal immunosuppression was putatively explained as follows: (i) toxins affected DEmRNAs regarding transfer and transduction mechanisms between cells (Csf1, Csf1r, Cxcl10, Cx3cr1, and Irf1), which were regulated by key DEmiRNAs (miR-106-x, miR-107-y, and miR-124-y) and the DElncRNA Rian, and (ii) toxins inhibited transforming growth factor-β-activated kinase 1 (TAK1)/I-kappaB kinase (IKK)/inhibitor of kappa Bα (IκBα)/p65 nuclear factor-κB (NF-κB) signaling phosphorylation levels, which was validated in differentiated Caco-2 cells using the TAK1 inhibitor (5Z-7-oxozeaenol). In conclusion, we evaluated the risk of co-exposure to AFM1 and OTA and associated health hazards from a whole transcriptome perspective.

Congenital aflatoxicosis, mal-detoxification genomics & ontogeny trigger immune-mediated Kotb disease biliary atresia variant: SANRA compliant review

Biliary atresia (BA) is the most common indication for pediatric liver transplantation. We describe The BA variant: Kotb disease. Liver tissue in the Kotb disease BA is massively damaged by congenital aflatoxicosis resulting in inflammation, adhesions, fibrosis, bile duct proliferation, scarring, cholestasis, focal syncytial giant cell transformation, and typical immune response involving infiltration by CD4+, CD8+, CD68+, CD14+, neutrophil infiltration, neutrophil elastase spill, heavy loads of aflatoxin B1, accelerated cirrhosis, disruption of p53 and GSTPi, and have null glutathione S transferase M1 (GSTM1). All their mothers are heterozygous for GSTM1. This inability to detoxify aflatoxicosis results in progressive inflammatory adhesions and obliterative cholangiopathy early in life. The typical disruption of both p53 and GSTPi causes loss of fidelity of hepatic regeneration. Hence, regeneration in Kotb disease BA typically promotes accelerated cirrhosis. The immune response in Kotb disease BA is for damage control and initiation of regeneration, yet, this friendly fire incurs massive structural collateral damage. The Kotb disease BA is about actual ongoing hepatic entrapment of aflatoxins with lack of ability of safe disposal due to child detoxification-genomics disarray. The Kotb disease BA is a product of the interaction of persistent congenital aflatoxicosis, genetic lack of GSTM1 detoxification, ontogenically impaired activity of other hepatic detoxification, massive neutrophil-elastase, immune-induced damage, and disturbed regeneration. Ante-natal and neonatal screening for aflatoxicosis, avoiding cord milking, and stringent control of aflatoxicosis content of human, poultry and live-stock feeds might prove effective for prevention, prompt diagnosis and management based on our recent understanding of its patho-genomics.

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.

Decrease in Aflatoxin M1 Concentration in Milk during Cholesterol Removal by Application of β-Cyclodextrin

Approximately one-third of humankind is chronically exposed to the carcinogenic aflatoxin M1 contained in milk. As β-cyclodextrin is frequently used in the food industry, its effect on aflatoxin M1 concentration was investigated during cholesterol removal from milk due to the similarity among the physicochemical properties of aflatoxin M1 and cholesterol. Moreover, the elimination of cholesterol using β-cyclodextrin has been successfully applied in many studies without any substantial effect on the quality of the treated milk. Therefore, milk samples were spiked with aflatoxin M1 within the range from 0.20 to 2.00 µg/kg, and cholesterol removal was carried out by 2.0% (w/w) β-cyclodextrin addition, as this concentration is enough for the sufficient removal of cholesterol. It was found that the mean cholesterol concentration decreased by 92.3%, while the aflatoxin M1 concentration decreased to 0.53 ± 0.04 µg/kg, i.e., by 39.1% after treatment (n = 2). This mitigation procedure itself is easy and inexpensive and thus is fully applicable with a high potential for complete decontamination of aflatoxin M1 milk. This method will therefore considerably improve the food safety issues associated with aflatoxin M1 presence in milk and dairy products.

Risperidone Toxicity on Human Blood Lymphocytes in Nano molar Concentrations

Risperidone is an atypical antipsychotic drug used for the pharmacotherapy of psychiatric disorders. Some reports indicate that risperidone is toxic to various systems of the body, including the immune system. This study evaluated the toxicity effect of risperidone on human blood lymphocytes. To achieve this aim, lymphocytes were isolated using Ficoll paque plus. The results showed that risperidone (12, 24 and 48 nM) causes toxicity in human blood lymphocytes by increasing the level of intracellular reactive oxygen species (ROS), damage to lysosomal membrane, the collapse of the mitochondrial membrane potential (MMP), and increased extracellular oxidized glutathione (GSSG). Also, exposure of human blood lymphocytes to risperidone is associated with a decrease in intracellular glutathione (GSH) levels. Finally, it could be concluded that oxidative stress is one of the mechanisms of risperidone-induced toxicity in human blood lymphocytes.

Estimation of Tolerable Daily Intake (TDI) for Immunological Effects of Aflatoxin

Aflatoxins are toxic chemicals produced by the fungi Aspergillus flavus and Aspergillus parasiticus. In warm climates, these fungi frequently contaminate crops such as maize, peanuts, tree nuts, and sunflower seeds. In many tropical and subtropical regions of the world, populations are coexposed to dietary aflatoxin and multiple infectious pathogens in food, water, and the environment. There is increasing evidence that aflatoxin compromises the immune system, which could increase infectious disease risk in vulnerable populations. Our aim was to conduct a dose-response assessment on a noncarcinogenic endpoint of aflatoxin: immunotoxicological effects. We sought to determine a noncarcinogenic tolerable daily intake (TDI) of aflatoxin, based on the existing data surrounding aflatoxin and biomarkers of immune suppression. To conduct the dose response assessment, mammalian studies were assessed for appropriateness of doses (relevant to potential human exposures) as well as goodness of data, and two appropriate mouse studies that examined decreases in leukocyte counts were selected to generate dose response curves. From these, we determined benchmark dose lower confidence limits (BMDL) as points of departure to estimate a range of TDIs for aflatoxin-related immune impairment: 0.017-0.082 μg/kg bw/day. As aflatoxin is a genotoxic carcinogen, and regulations concerning its presence in food have largely focused on its carcinogenic effects, international risk assessment bodies such as the Joint Expert Committee on Food Additives (JECFA) have never established a TDI for aflatoxin. Our work highlights the importance of the noncarcinogenic effects of aflatoxin that may have broader public health impacts, to inform regulatory standard-setting.

Mold, Mycotoxins and a Dysregulated Immune System: A Combination of Concern?

Fungi represent one of the most diverse and abundant eukaryotes on earth. The interplay between mold exposure and the host immune system is still not fully elucidated. Literature research focusing on up-to-date publications is providing a heterogenous picture of evidence and opinions regarding the role of mold and mycotoxins in the development of immune diseases. While the induction of allergic immune responses by molds is generally acknowledged, other direct health effects like the toxic mold syndrome are controversially discussed. However, recent observations indicate a particular importance of mold/mycotoxin exposure in individuals with pre-existing dysregulation of the immune system, due to exacerbation of underlying pathophysiology including allergic and non-allergic chronic inflammatory diseases, autoimmune disorders, and even human immunodeficiency virus (HIV) disease progression. In this review, we focus on the impact of mycotoxins regarding their impact on disease progression in pre-existing immune dysregulation. This is complemented by experimental in vivo and in vitro findings to present cellular and molecular modes of action. Furthermore, we discuss hypothetical mechanisms of action, where evidence is missing since much remains to be discovered.

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.

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.

Fungal Toxins and Host Immune Responses

Fungi are ubiquitous organisms that thrive in diverse natural environments including soils, plants, animals, and the human body. In response to warmth, humidity, and moisture, certain fungi which grow on crops and harvested foodstuffs can produce mycotoxins; secondary metabolites which when ingested have a deleterious impact on health. Ongoing research indicates that some mycotoxins and, more recently, peptide toxins are also produced during active fungal infection in humans and experimental models. A combination of innate and adaptive immune recognition allows the host to eliminate invading pathogens from the body. However, imbalances in immune homeostasis often facilitate microbial infection. Despite the wide-ranging effects of fungal toxins on health, our understanding of toxin-mediated modulation of immune responses is incomplete. This review will explore the current understanding of fungal toxins and how they contribute to the modulation of host immunity.

Mycotoxin Contamination of Consumed Rice in Iran: A Review

: Mycotoxin contamination of rice has been introduced as a big challenge for public health in developing countries in numerous studies. Rice consumption is also considered the main source of secondary metabolites in Iran. Given the diversity of climatic conditions in this region as well as unsuitable storage conditions, including high temperature and humidity, rice can be extremely contaminated via various fungi. The current study is a review of the occurrence of mycotoxins in rice in Iran. In this regard, some investigations had revealed that rice could be contaminated by mycotoxins such as aflatoxins (AFTs) (B1, B2, G1, and G2), deoxynivalenol (DON), fumonisin (FM) (B1 and B2), ochratoxin A (OTA), T-2 toxin, and zearalenone (ZEN). Moreover, the amount of mycotoxins in rice was reported in varying ranges in different provinces and regions and normally less than Iranian maximum tolerated dose (MTD). Given the importance of rice in the Iranian diet, it was finally recommended to screen consumed rice to find about fungal contaminations and mycotoxins.

Immunological effects of AFM1 in experimental subchronic dosing in mice prevented by lactic acid bacteria

AIM

Recently, higher contamination by aflatoxin M1 (AFM1) has been detected in many countries. Unfortunately, many tons of contaminated milk and milk byproducts are removed from the food chain to avoid human contamination; as a consequence of higher economic losses. Fewest number of studies are interested to AFM1 detoxification using lactic acid bacteria.

MATERIALS AND METHODS

In this study, AFM1-degradation using Lactobacillus paracasei BEJ01 (LPBEJ01) was tested in vitro. The preventive effect of LPBEJ01 against AFM1 immunobiological effects in mice are treated orally during 3 weeks with 100 µg AFM1, LPBEJ01 (2 × 10⁹ CFU/ml∼2 mg/kg p.c.) and a mixture of AFM1 and LPBEJ01.

RESULTS

In vitro LPBEJ01 was found able to absorb 98% of AFM1 (100 µg/ml) in liquid medium after 24 h and more than 95% of AFM1 could be eliminated after 24 h in a solid-state fermentation. Animals treated with AFM1 obtained lower body weight than the control ones. The mitogenic response of spleen mononuclear cells (SMCs) in vivo was higher in mice treated with AFM1. The SMC of mice treated with AFM1 produced lower levels of IL-2, higher levels IL-4 and no effect on IL-10 production. The peritoneal macrophages of mice that treated with AFM1 released less H₂O₂, while mice exposed orally with the mixture of AFM1 and LPBEJ01 produced higher levels.

CONCLUSION

LPBEJ01 was safe and it did not have any sign of toxicity. It can be used as an additive for AFM1-detoxification contamination in the food chain in countries suffering from this problem.

Health risk from aflatoxins in processed meat products in Riyadh, KSA

This study investigated the health risks associated with aflatoxins (AFs) in processed meat products (PMP) sold in Riyadh, Kingdom of Saudi Arabia. The occurrence and levels of AFs were assessed using high-performance liquid chromatography with fluorescence detection (HPLC-FD), whereas the cancer risk attributed to the consumption of meat products containing AFs was estimated by means of margin of exposure (MOE) on a scale of 100-600, representing high and low exposure, respectively. The results indicated that 37.5% of the samples were contaminated, with concentrations ranging from 0.30 to 52.93 μg/kg, at an average of 6.4 ± 12.58 μg/kg. The percentage contamination levels with total AFs higher than the permissible Saudi limit of 20 μg/kg were 4% of samples analysed and 10% of contaminated samples. AFB1 and AFG1 were the most prevalent toxins, followed by AFB2; AFG2 was not detected in any sample. The MOE was found to be 175 and 311 for total AFs in processed beef meat and poultry meat products, respectively. These results showed that the daily intake of AF-contaminated PMP may constitute a public health concern. To our knowledge, this is the first study to report the health risk associated with PMP contaminated with AFs.

Transcriptomic and proteomic profiling reveals the intestinal immunotoxicity induced by aflatoxin M1 and ochratoxin A

Mycotoxins-contaminated milk could threaten human health; therefore, it is necessary to demonstrate the toxicological effect of mycotoxins in milk. Most recently, researchers have paid more attention to the immunotoxic effects of the individual cereal-contaminating mycotoxins, namely, zearalenone and deoxynivalenol. However, there is scant information about the intestinal immunotoxicity of aflatoxin M1 (AFM1), let alone that of a combination of AFM1 and ochratoxin A (OTA), which often co-occur in milk. To reveal the inflammatory response caused by these mycotoxins, expression of inflammation-related genes in differentiated Caco-2 cells was analyzed, demonstrating a synergistic effect of the mixture of AFM1 (4 μg/mL) and OTA (4 μg/mL). Integrative transcriptomic and proteomic analyses were also performed. A cross-omics analysis identified several mechanisms underlying this synergy: (i) compared with stimulation with either compound alone, combined use resulted in stronger induction of proteins involved in immunity-related pathways; (ii) combination of the two agents targeted different points in the same pathways; and (iii) combination of the two agents activated specific inflammation-related pathways. These results suggested that combined use of AFM1 and OTA might exacerbate intestinal inflammation, indicating that regulatory authorities should pay more attention to food contamination by multiple mycotoxins when performing risk assessments.

Risk assessment of aflatoxins in food

EFSA was asked to deliver a scientific opinion on the risks to public health related to the presence of aflatoxins in food. The risk assessment was confined to aflatoxin B1 (AFB1), AFB2, AFG1, AFG2 and AFM1. More than 200,000 analytical results on the occurrence of aflatoxins were used in the evaluation. Grains and grain-based products made the largest contribution to the mean chronic dietary exposure to AFB1 in all age classes, while 'liquid milk' and 'fermented milk products' were the main contributors to the AFM1 mean exposure. Aflatoxins are genotoxic and AFB1 can cause hepatocellular carcinomas (HCCs) in humans. The CONTAM Panel selected a benchmark dose lower confidence limit (BMDL) for a benchmark response of 10% of 0.4 μg/kg body weight (bw) per day for the incidence of HCC in male rats following AFB1 exposure to be used in a margin of exposure (MOE) approach. The calculation of a BMDL from the human data was not appropriate; instead, the cancer potencies estimated by the Joint FAO/WHO Expert Committee on Food Additives in 2016 were used. For AFM1, a potency factor of 0.1 relative to AFB1 was used. For AFG1, AFB2 and AFG2, the in vivo data are not sufficient to derive potency factors and equal potency to AFB1 was assumed as in previous assessments. MOE values for AFB1 exposure ranged from 5,000 to 29 and for AFM1 from 100,000 to 508. The calculated MOEs are below 10,000 for AFB1 and also for AFM1 where some surveys, particularly for the younger age groups, have an MOE below 10,000. This raises a health concern. The estimated cancer risks in humans following exposure to AFB1 and AFM1 are in-line with the conclusion drawn from the MOEs. The conclusions also apply to the combined exposure to all five aflatoxins.

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.

Aflatoxin M1 binding by lactic acid bacteria in milk

This research focused on biocontrol solution to increase food safety through studying lactic acid bacteria (LAB) which can bind aflatoxins in milk. Aflatoxins are toxic contaminants found in feeds and foods. In milk aflatoxin is found in metabolised form, aflatoxin M1 (AFM1). Three indigenous LAB Lactobacillus strains and one Lactococcus strain isolated from Kenyan spontaneously fermented foods were tested for their AFM1 binding abilities in different conditions and after different treatments along with two reference Lactobacillus strains. Binding of AFM1 in different concentrations was examined with unconcentrated, concentrated, heat treated and concentrated heat-treated LAB cultures. Observed binding of AFM1 by LAB varied between 11 to 100%, being approximately at the level of 40% throughout the analysis sets. The results of this study suggest that the aflatoxin binding ability by LAB strain is not strongly strain specific and depends on many external and condition variables. Also, the methods used in determination of aflatoxin binding warrant critical evaluation.

Detection and Concentration of Plasma Aflatoxin is Associated with Detection of Oncogenic Human Papillomavirus in Kenyan Women

BACKGROUND

Cervical cancer is common in Kenyan women. Cofactors in addition to infection with oncogenic human papillomavirus (HPV) are likely to be important in causing cervical cancer, as only a small percentage of HPV-infected women will develop this malignancy. Kenyan women are exposed to dietary aflatoxin, a potent carcinogen and immunosuppressive agent, which may be such a co-factor.

METHODS

Demographics, behavioral data, plasma, and cervical swabs were collected from 88 HIV-uninfected Kenyan women without cervical dysplasia. HPV detection was compared between women with or without plasma AFB1-lys and evaluated in relation to AFB1-lys concentration.

RESULTS

Valid HPV testing results were available for 86 women (mean age 34.0 years); 49 women (57.0%) had AFB1-lys detected and 37 (43.0%) had none. AFB1-lys detection was not associated with age, being married, having more than secondary school education, home ownership, living at a walking distance to health care ≥60 minutes, number of lifetime sex partners, or age of first sex. AFB1-lys detection and plasma concentrations were associated with detection of oncogenic HPV types.

CONCLUSIONS

AFB1-lys-positivity and higher plasma AFB1-lys concentrations were associated with higher risk of oncogenic HPV detection in cervical samples from Kenya women. Further studies are needed to determine if aflatoxin interacts with HPV in a synergistic manner to increase the risk of cervical cancer.

C9-13 chlorinated paraffins cause immunomodulatory effects in adult C57BL/6 mice

Short-chain chlorinated paraffins (SCCPs, C_10-13) were listed as persistent organic pollutants (POPs) by the Stockholm Convention in 2017 and pose extensive exposure risks to humans. To our knowledge, there have been no studies reporting the immmunomodulatory effects of SCCPs until now. C₉-CPs have also been shown to be present in the environment. In this study, adult male C57BL/6 mice were exposed to 1, 10, or 100 mg/kg/d C_9-13-CPs by gavage for 28 d. The results showed that compared to those of the controls, exposure to C_9-13-CPs led to increased spleen weight, delimited germinal centers, enhanced energy metabolism, and elevated glutathione content, but no variation in the malonaldehyde level in the spleen was observed. Exposure to C_9-13-CPs also increased the populations of splenic lymphocytes, T lymphocytes, NK cells, and the ratio of the CD3⁺/CD19⁺ subsets and CD4⁺/CD8⁺ subsets compared to those of the controls. RNA-seq revealed 424 differentially expressed genes (DEGs) (fold change ≥ 1.5, FDR < 0.05) in the spleen between the control group and the 100 mg/kg/d C_9-13-CPs-treated group. KEGG analysis demonstrated that folate biosynthesis, pathways in cancer and thyroid hormone signaling were the three most significantly enriched pathways, and despite not reaching statistical significance, some immune-related pathways were also enriched in the KEGG functional enrichment analysis, including the chemokine signaling pathway (FDR < 0.0584), the NF-κB signaling pathway (FDR < 0.0663), Th17 cell differentiation (FDR < 0.0839), and the Jak-STAT signaling pathway. Moreover, compared to those of the controls, exposure to C_9-13-CPs enhanced the Concanavalin A (Con A)-stimulated cultured splenocyte proliferation, while the exposure showed no effect on the splenocyte proliferation that was stimulated by lipopolysaccharides (LPS). Taken together, these results demonstrated that subacute exposure to C_9-13-CPs could have immunomodulatory effects in mice. The present study helps to provide an understanding of the comprehensive health risks posed by C_9-13-CPs.