Aflatoxin-lysine adducts in blood serum of the Malawian rural population and aflatoxin contamination in foods (groundnuts, maize) in the corresponding areas

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.

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 in cereals and groundnut from small holder farming households in Malawi

Aflatoxin contamination in commonly consumed cereals and nuts may place children at higher risk of stunting and adults at risk of developing liver cancer. This study investigated knowledge on aflatoxins and the level of aflatoxin B₁ contamination in commonly consumed cereals and nuts in Malawi. It also included an examination of the proportion of cereals and nuts contaminated above regulatory maximum limits. Aflatoxin contamination in samples was assessed using an enzyme-linked immunosorbent assay (ELISA) method. Less than half of all households knew that consumption of aflatoxin contaminated grain is associated with stunting and lowered immunity. Sorghum samples were the most contaminated and millet the least contaminated. Aflatoxin contamination was highest in southern Malawi and least in northern Malawi. Observed results indicate that this population is at risk of poor health due to lack of knowledge and aflatoxin exposure. Strategies to address contamination should therefore include a comprehensive education campaign to increase knowledge and promote accessible strategies.

HPLC–MS/MS method for the simultaneous determination of aflatoxins in blood: toxicokinetics of aflatoxin B1 and aflatoxin M1 in rats

Mycotoxins are highly toxic fungal metabolites that can pose health threats to humans and animals. Aflatoxins are a type of mycotoxin produced mainly by Aspergillus flavus and A. parasiticus. A sensitive high performance liquid chromatography–tandem mass spectrometry (HPLC–MS/MS) method with multiple reaction monitoring (MRM) modes was developed for the determination of aflatoxins in blood after acetonitrile precipitation extraction. The limits of quantification of aflatoxins ranged from 0.05 to 0.2 ng/mL. Intra-day accuracy ranged from 92 to 111.0%, and intra-day precision (n = 6) ranged from 1 to 8%. Inter-day accuracy and precision were 94.0–102.0% and 2.0–8.0%, respectively. The toxicokinetics of AFB1 and its metabolite AFM1 after a single oral administration (AFB1 1 mg/kg body weight) were studied in male Sprague–Dawley rats. The blood AFB1 and AFM1 profiles could be adequately described by a noncompartmental model. The highest concentration of AFB1 (Cmax 93.42 ± 23.01 ng/mL) was observed with Tmax at 0.15 ± 0.034 h. AFB1 was rapidly metabolized to AFM1 which reached its peak blood concentration (Cmax 53.86 ± 12.12 ng/mL) at 0.33 ± 0.11 h. The HPLC–MS/MS method was simple and sensitive, appropriate for studying the in vivo toxicokinetics of aflatoxins.

Micro-climatic variations across Malawi have a greater influence on contamination of maize with aflatoxins than with fumonisins

This study reports levels of aflatoxin and fumonisin in maize samples (n = 1294) from all agroecological zones (AEZs) in Malawi. Most maize samples (> 75%) were contaminated with aflatoxins and 45% with fumonisins, which co-occurred in 38% of the samples. Total aflatoxins varied across the AEZs, according to mean annual temperature (P < 0.05) of the AEZs. Samples from the lower Shire AEZ (median = 20.8 µg/kg) had higher levels of aflatoxins (P < 0.05) than those from the other AEZs (median = 3.0 µg/kg). Additionally, the majority (75%) of the positive samples from the lower Shire AEZ had aflatoxin levels exceeding the EU regulatory limit (4 µg/kg), whereas 25%, 37%, and 39% of positive samples exceeded the threshold in the mid-elevation, Lake Shore and upper and middle Shire, and highlands AEZs, respectively. The lower Shire AEZ is characterised by higher mean temperatures throughout the year and low erratic rainfall. However, total fumonisins did not show significant variation across AEZs, but all positive samples exceeded 150 µg/kg, required for tolerable daily intake of 1.0 µg/kg body weight per day, established by the European Food Safety Authority Panel on Contaminants in the Food Chain. Therefore, results of this study suggest that contamination of maize with aflatoxin responds to micro-climate more than with fumonisins. In addition, the data will be useful to public health policy-makers and stakeholders to articulate and implement monitoring and mitigation programs.

Analytical Validation of a Direct Competitive ELISA for Multiple Mycotoxin Detection in Human Serum

Mycotoxin exposure in humans is primarily assessed through its occurrence in external sources, such as food commodities. Herein, we have developed a direct competitive ELISA to facilitate the detection of aflatoxin B1 (AFB1), deoxynivalenol (DON), fumonisin (FUM B1/B2), ochratoxin A (OTA), and zearalenone (ZEA) in human serum. The analytical validation of the assay followed practices endorsed by the international research community and the EU directive 96/23/EC in order to examine detection capability, recovery, and cross-reactivity. The assay demonstrated a lower limit of quantitation (LLOQ) for AFB1 [0.61 ng/mL (hereon ng/mL = ppb)], DON (19.53 ppb), FUM (4.88 ppb), OTA (19.53 ppb), and ZEA (0.15 ppb). Recovery from human serum for all mycotoxins spanned from 73% to 106%. Likewise, the specificity for monoclonal antibodies against cross-reactant mycotoxins ranged from 2% to 11%. This study compares the LLOQ and recovery values with commercial and emerging immuno-based methods for detecting mycotoxins in foodstuffs. The LLOQ values from the present study were among the lowest in commercial or emerging methods. Despite the differences in the extraction protocols and matrices, the recovery range in this study, commercial tests, and other procedures were similar for all mycotoxins. Overall, the assay detected AFB1, DON, FUM, OTA, and ZEA in human serum with excellent accuracy, precision, and specificity.

Human biomonitoring of multiple mycotoxins in hair: first large-scale pilot study

Human biomonitoring (HBM) represents the most accurate approach for assessing the exposure to mycotoxins, but traditional matrices fail to provide information about long-term exposure due to the rapid excretion rates and short half-lives of mycotoxins. Hair emerges as a promising matrix considering that contaminants can form stable links with hair components, such as keratins and melanin. Hence, the aim of the present study was to monitor the presence of up to ten mycotoxins (aflatoxins and Fusarium mycotoxins) in human hair samples (n=100) through a high-performance liquid chromatography coupled to Q-TOF high resolution mass spectrometry. A prevalence of 43% at concentrations ranging from 2.7 to 106.1 ng/g was observed, being enniatins and aflatoxin B1 the most prevalent compounds. Co-occurrence of up to three mycotoxins was observed in 42% of the positive samples. Retrospective untargeted analysis of hair samples tentatively identified up to 128 mycotoxins and related metabolites. These results confirm the accumulation of toxicologically relevant mycotoxins in hair matrix, thus standing as a suitable matrix for assessing long-term exposure.

Aflatoxin B1 and Aflatoxin M1 Induce Compromised Intestinal Integrity through Clathrin-Mediated Endocytosis

With the growing diversity and complexity of diet, humans are at risk of simultaneous exposure to aflatoxin B1 (AFB1) and aflatoxin M1 (AFM1), which are well-known contaminants in dairy and other agricultural products worldwide. The intestine represents the first barrier against external contaminants; however, evidence about the combined effect of AFB1 and AFM1 on intestinal integrity is lacking. In vivo, the serum biochemical parameters related to intestinal barrier function, ratio of villus height/crypt depth, and distribution pattern of claudin-1 and zonula occluden-1 were significantly affected in mice exposed to 0.3 mg/kg b.w. AFB1 and 3.0 mg/kg b.w. AFM1. In vitro results on differentiated Caco-2 cells showed that individual and combined AFB1 (0.5 and 4 μg/mL) and AFM1 (0.5 and 4 μg/mL) decreased cell viability and trans-epithelial electrical resistance values as well as increased paracellular permeability of fluorescein isothiocyanate-dextran in a dose-dependent manner. Furthermore, AFM1 aggravated AFB1-induced compromised intestinal barrier, as demonstrated by the down-regulation of tight junction proteins and their redistribution, particularly internalization. Adding the inhibitor chlorpromazine illustrated that clathrin-mediated endocytosis partially contributed to the compromised intestinal integrity. Synergistic and additive effects were the predominant interactions, suggesting that these toxins are likely to have negative effects on human health.

Human Biomonitoring of Mycotoxins in Blood, Plasma and Serum in Recent Years: A Review

This manuscript reviews the state-of-the-art regarding human biological monitoring (HBM) of mycotoxins in plasma serum and blood samples. After a comprehensive and systematic literature review, with a focus on the last five years, several aspects were analyzed and summarized: a) the biomarkers analyzed and their encountered levels, b) the analytical methodologies developed and c) the relationship between biomarker levels and some illnesses. In the literature reviewed, aflatoxin B1-lysine (AFB1-lys) and ochratoxin A (OTA) in plasma and serum were the most widely studied mycotoxin biomarkers for HBM. Regarding analytical methodologies, a clear increase in the development of methods for the simultaneous determination of multiple mycotoxins has been observed. For this purpose, the use of liquid chromatography (LC) methodologies, especially when coupled with tandem mass spectrometry (MS/MS) or high resolution mass spectrometry (HRMS), has grown. A high percentage of the samples analyzed for OTA or aflatoxin B1 (mostly as AFB1-lys) in the reviewed papers were positive, demonstrating human exposure to mycotoxins. This review confirms the importance of mycotoxin human biomonitoring and highlights the important challenges that should be faced, such as the inclusion of other mycotoxins in HBM programs, the need to increase knowledge of mycotoxin metabolism and toxicokinetics, and the need for reference materials and new methodologies for treating samples. In addition, guidelines are required for analytical method validation, as well as equations to establish the relationship between human fluid levels and mycotoxin intake.

Advances in Crop Improvement and Delivery Research for Nutritional Quality and Health Benefits of Groundnut (Arachis hypogaea L.)

Groundnut is an important global food and oil crop that underpins agriculture-dependent livelihood strategies meeting food, nutrition, and income security. Aflatoxins, pose a major challenge to increased competitiveness of groundnut limiting access to lucrative markets and affecting populations that consume it. Other drivers of low competitiveness include allergens and limited shelf life occasioned by low oleic acid profile in the oil. Thus grain off-takers such as consumers, domestic, and export markets as well as processors need solutions to increase profitability of the grain. There are some technological solutions to these challenges and this review paper highlights advances in crop improvement to enhance groundnut grain quality and nutrient profile for food, nutrition, and economic benefits. Significant advances have been made in setting the stage for marker-assisted allele pyramiding for different aflatoxin resistance mechanisms-in vitro seed colonization, pre-harvest aflatoxin contamination, and aflatoxin production-which, together with pre- and post-harvest management practices, will go a long way in mitigating the aflatoxin menace. A breakthrough in aflatoxin control is in sight with overexpression of antifungal plant defensins, and through host-induced gene silencing in the aflatoxin biosynthetic pathway. Similarly, genomic and biochemical approaches to allergen control are in good progress, with the identification of homologs of the allergen encoding genes and development of monoclonal antibody based ELISA protocol to screen for and quantify major allergens. Double mutation of the allotetraploid homeologous genes, FAD2A and FAD2B, has shown potential for achieving >75% oleic acid as demonstrated among introgression lines. Significant advances have been made in seed systems research to bridge the gap between trait discovery, deployment, and delivery through innovative partnerships and action learning.

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.

Evaluation of emerging biomarkers of renal damage and exposure to aflatoxin-B1 in Mexican indigenous women: a pilot study

Aflatoxins (AFs) are mycotoxins produced by Aspergillus parasiticus and Aspergillus flavus which frequently contaminate maize. These compounds are considered toxic, especially AFB₁ which has been classified as a human carcinogen, due to its relationship with the generation of hepatocellular carcinoma. Studies in vivo, in animal models, prove that chronic consumption of AFB₁ has an association with renal adverse effects, but evidence in humans is scarce. Therefore, the main objective of this research was to conduct a pilot study to evaluate the correlation between exposure to AFB₁ and early-stage renal damage in indigenous women of San Luis Potosí, Mexico. Exposure to AFB₁ was measured through the biomarker AFB₁-lysine and renal damage through kidney injury molecule-1 (KIM-1), neutrophil gelatinase-associated lipocalin (NGAL), and cystatin-C (Cys-C). AFB₁-Lys was measured by HPLC-FLD. The method was validated with a correlation coefficient of 0.99 and limit of detection and quantification of 3.5 and 4.7 pg mL^-1, respectively. Levels of NGAL, KIM-1, and Cys-C were determined (median (P25-P75), 5.96 (3.16-15.91), 0.137 (0.137-0.281), and 18.49 (5.76-29.57) ng mL^-1, respectively). Additionally, glomerular filtration rate (GFR) (83.3 (59.8-107.4) mL/min/1.73 m²) and serum creatinine (SCr) (0.88 (0.72-1.22) mg dL^-1) were obtained. The median concentrations for AFB₁-Lys were 2.08 (1.89-5.8) pg mg^-1 of albumin. Statistically significant correlations between AFB₁-Lys/KIM-1 (Rho = 0.498, p = 0.007) and AFB₁/Cys-C (Rho = 0.431, p = 0.014) were found. Our results indicate that women are exposed to AFB₁, due to the fact that the AFB₁-Lys biomarker was found in a high percentage of the study population (83%). In addition, the results of exposure to AFB₁ show a strong significant correlation between KIM-1 and Cys-C that may indicate the toxic renal effect. These results are alarming because of the high toxicity of this compound and require adequate intervention to reduce AFB₁ exposure in these populations.

A Critical Review of Aflatoxin Contamination of Peanuts in Malawi and Zambia: The Past, Present, and Future

Peanut (Arachis hypogaea L.) is an important crop in Malawi and Zambia. The crop is valued for soil improvement in cereal-based cropping systems, for improving the livelihoods of farming households who consume it and also sell it for cash, and for earning foreign exchange when exported. Research and development efforts have resulted in an increase in both peanut production area and productivity. However, a key challenge that still needs to be solved in these countries is how to produce peanuts with acceptable levels of aflatoxin contamination. Data continues to show that aflatoxin continues to be a problem in both formal and informal trade. As a result, unlike 30 years ago, most of the peanut trade has now shifted to domestic and regional markets that do not restrict the sale of aflatoxin-contaminated peanuts. Impacts of aflatoxin contamination on health and also on the full cost burden of control are not well documented. Technologies are available for mitigating against aflatoxin contamination. The advantages, disadvantages, and gaps associated with these technologies are discussed. Considerable money and effort continues to be invested in Malawi and Zambia into mitigating aflatoxin contamination, but evidence of long-term success is limited. Based on past and current initiatives, the prospects of eliminating aflatoxin in the near future at the household level and in trade are not promising.