Deoxynivalenol Biomarkers in the Urine of UK Vegetarians

Deoxynivalenol Induces Drp-1-Mediated Mitochondrial Dysfunction via Elevating Oxidative Stress

Mitochondrial dysfunction is often linked to neurotoxicity and neurological diseases and stems from oxidative stress, yet effective therapies are lacking. Deoxynivalenol (DON or vomitoxin) is one of the most common and hazardous type-B trichothecene mycotoxins, which contaminates crops used for food and animal feed. Despite the abundance of preliminary reports, comprehensive investigations are scarce to explore the relationship between these fungal metabolites and neurodegenerative disorders. The present study aimed to elucidate the precise role of DON in mitochondrial dynamics and cell death in neuronal cells. Excessive mitochondrial fission is associated with the pathology of several neurodegenerative diseases. Human SH-SY5Y cells were treated with different concentrations of DON (250-1000 ng/mL). Post 24 and 48 h DON treatment, the indexes were measured as follows: generation of reactive oxygen species (ROS), ATP levels, mitochondrial membrane potential, calcium levels, and cytotoxicity in SH-SY5Y cells. The results showed that cytotoxicity, intracellular calcium levels, and ROS in the DON-treated group increased, while the ATP levels and mitochondrial membrane potential decreased in a dose-dependent manner. With increasing DON concentrations, the expression levels of P-Drp-1, mitochondrial fission proteins Mff, and Fis-1 were elevated with reduced activities of MFN1, MFN2, and OPA1, further resulting in an increased expression of autophagic marker LC3 and beclin-1. The reciprocal relationship between mitochondrial damage and ROS generation is evident as ROS can instigate structural and functional deficiencies within the mitochondria. Consequently, the impaired mitochondria facilitate the release of ROS, thereby intensifying the cycle of damage and exacerbating the overall process. Using specific hydroxyl, superoxide inhibitors, and calcium chelators, our study confirmed that ROS and Ca2+-mediated signaling pathways played essential roles in DON-induced Drp1 phosphorylation. Therefore, ROS and mitochondrial fission inhibitors could provide critical research tools for drug development in mycotoxin-induced neurodegenerative diseases.

Toxicokinetics and metabolism of deoxynivalenol in animals and humans

Deoxynivalenol (DON) is the most widespread mycotoxin in food and feedstuffs, posing a persistent health threat to humans and farm animals. The susceptibilities of DON vary significantly among animals, following the order of pigs, mice/rats and poultry from the most to least susceptible. However, no study comprehensively disentangles factors shaping species-specific sensitivity. In this review, the toxicokinetics and metabolism of DON are summarized in animals and humans. Generally, DON is fast-absorbed and widely distributed in multiple organs. DON is first enriched in the plasma, liver and kidney and subsequently accumulates in the intestine. There are also key variations among animals. Pigs and humans are highly sensitive to DON, and they have similar absorption rates (1 h < t_max < 4 h), high bioavailability (> 55%) and long clearance time (2 h < t_1/2 < 4 h). Also, both species lack detoxification microorganisms and mainly depend on liver glucuronidation and urine excretion. Mice and rats have similar toxicokinetics (t_max < 0.5 h, t_1/2 < 1 h). However, a higher proportion of DON is excreted by feces as DOM-1 in rats than in mice, suggesting an important role of gut microbiota in rats. Poultry is least sensitive to DON due to their fast absorption rate (t_max < 1 h), low oral bioavailability (5-30%), broadly available detoxification gut microorganisms and short clearance time (t_1/2 < 1 h). Aquatic animals have significantly slower plasma clearance of DON than land animals. Overall, studies on toxicokinetics provide valuable information for risk assessment, prevention and control of DON contamination.

Mycotoxins in Serum and 24-h Urine of Vegans and Omnivores from the Risks and Benefits of a Vegan Diet (RBVD) Study

Scope Vegans might have a higher exposure to mycotoxins due to their heightened consumption of typical mycotoxin containing food sources. Yet, data on internal exposure among vegans in comparison to omnivores are currently lacking. Methods and Results This cross-sectional study included 36 vegans and 36 omnivores (50% females, 30-60 years). A set of 28 and 27 mycotoxins was analyzed in 24-h urine and serum samples, respectively, by validated multi-mycotoxin methods (HPLC-MS/MS). Ochratoxin A (OTA), 2'R-OTA, and enniatin B in serum as well as deoxynivalenol-glucuronide in 24-h urine were quantified in 57 to 100% of the samples. Serum OTA levels were twofold higher in vegans than in omnivores (median 0.24 versus 0.12 ng/mL; P <0.0001). No further significant differences were observed. Serum OTA levels were associated with intake of "vegan products" (r = 0.50, P <0.0001) and "pasta & rice" (r = 0.33, P = 0.006). Sensitivity analyses advise cautious interpretation. Furthermore, serum levels of 2'R-OTA were related to coffee consumption (r = 0.64, P <0.0001). Conclusion Our results indicate a higher exposure of vegans to OTA, but not to other mycotoxins. However, larger studies with repeated measurements are required to better evaluate the exposure to mycotoxins from plant-based diets. This article is protected by copyright. All rights reserved.

Urinary deoxynivalenol as a biomarker of exposure in different age, life stage and dietary practice population groups

The Fusarium mycotoxin deoxynivalenol (DON) and its modified forms are present in most samples of grain and grain-based products. Due to the widespread presence of DON in these highly consumed food commodities, nearly all individuals are exposed to DON. Previous estimates of the dietary DON intake in Norway indicated that children's dietary intake is close to or exceed the TDI of 1 µg/kg bw/day for the sum of DON and three modified forms. One aim of the current study was to determine whether the concentrations of DON in morning urine differ between population groups like men, women, children, vegetarians, and pregnant women. An additional aim was to compare a set of models for estimating the dietary intake of DON based on urinary DON concentrations and also compare these models with DON-intakes estimated using food consumption data. DON and metabolites were detected in the morning urine from 256 out of 257 individuals and with concentrations in similar range as reported from other countries. Children have higher urinary DON-concentration than adults and elderly. The urinary DON-concentration in pregnant women and vegetarians did not differ from other adults. The estimated intake of DON was higher for children than for other age groups on a body weight basis. The correlations between different models for estimating DON-intake based on urinary concentration as well as based on individual food consumption were good (0.79-0.99), but with some outliers. We conclude that Norwegians are exposed to DON in the same range as reported from other countries and that children have a higher exposure than adults. Furthermore, we conclude that intake estimates based on urinary DON concentration is a useful tool for evaluation of the exposure at population level, but due to outliers, the estimates for individuals are uncertain. There are also uncertainties in intake estimates both from food consumption and from urinary DON concentration, and we could not conclude on which approach provides the most accurate exposure estimate.

Development of a multi-mycotoxin LC-MS/MS method for the determination of biomarkers in pig urine

An LC-MS/MS method has been developed for the sensitive and selective determination of 35 mycotoxins (biomarkers of exposure) in pig urine samples. Sample preparation includes creatinine adjustment (with the developed LC-UV method) with enzymatic hydrolysis of pig urine samples followed by liquid-liquid (LLE) extraction. The LLE protocol, as well as enzymatic hydrolysis for indirect mycotoxin glucuronides determination, was optimized in this study. Additionally, two other sample preparation protocols were compared with the developed LLE method: immunoaffinity columns and solid-phase extraction cartridges (Oasis HLB). The detection and quantification of the biomarkers were performed using triple quadrupole mass spectrometry.The method was validated with regard to the guidelines specified by the EMEA (European Medicines Agency). The extraction recoveries were higher than 60% for 77% of the analytes studied, with the intra- and inter-day relative standard deviation being lower than 20% for most of the compounds at four different concentration levels. The limits of quantification ranged from 0.1 ng/mL for zearalenone and sterigmatocystin to 8 ng/mL for nivalenol. To the best knowledge of the authors, the matrix effect was evaluated for the first time in this study for six different urine samples, and the coefficient of variation was found to be lower than 15% for most analytes studied. Finally, the developed method was applied to analyse 56 pig urine samples. Deoxynivalenol (1-20 ng/mL), zearalenone (0.1-1.5 ng/mL) and ochratoxin A (1.5-15 ng/mL) were the main analytes detected in these samples. Moreover, the co-occurrence of alternariol monomethyl ether and alternariol in pig urine is reported herein for the first time.

Human Mycotoxin Biomonitoring: Conclusive Remarks on Direct or Indirect Assessment of Urinary Deoxynivalenol

Deoxynivalenol is one of the most ubiquitous mycotoxins in the Western diet through its presence in cereals and cereal products. A vast amount of studies indicate the worrying level of exposure to this toxin, while even high percentages of the population exceed the tolerable daily intake. To evaluate and assess dietary exposure, analysis of urinary levels of deoxynivalenol and its glucuronides has been proposed as a reliable methodology. An indirect preliminary method was used based on the cleavage of deoxynivalenol glucuronides through the use of enzymes (β-glucuronidase) and subsequent determination of "total deoxynivalenol" (sum of free and released mycotoxins by hydrolysis). Next, a direct procedure for quantification of deoxynivalenol-3-glucuronide and deoxynivalenol-15-glucuronide was developed. As deoxynivalenol glucuronides reference standards are not commercially available, the indirect method is widely applied. However, to not underestimate the total deoxynivalenol exposure in urine, the direct and indirect methodologies need to be compared. Urinary samples (n = 96) with a confirmed presence of deoxynivalenol and/or deoxynivalenol glucuronides were analysed using both approaches. The indirect method clarified that not all deoxynivalenol glucuronides were transformed to free deoxynivalenol during enzymatic treatment, causing an underestimation of total deoxynivalenol. This short communication concludes on the application of direct or indirect assessment of urinary deoxynivalenol.

Deoxynivalenol globally affects the selection of 3' splice sites in human cells by suppressing the splicing factors, U2AF1 and SF1

Deoxynivalenol (DON) is one of the most abundant mycotoxins and has adverse effects on several biological processes, posing risks of protein synthesis-disrupting effects and ribotoxic response. Therefore, chronic exposure to DON would fundamentally reshape the global expression pattern. Whether DON causes toxic effects on mRNA splicing, a fundamental biological process, remains unclear. In this study, we found that administration of the relative low dosage of DON dramatically changed the alternative splicing of pre-mRNA in HepG2 cells. The overall number of transcripts with aberrant selection of 3' splice sites was significantly increased in DON-exposed HepG2 cells. This effect was further confirmed in two other human cell lines, HEK293 and Caco-2, suggesting that this DON-induced alteration in splicing patterns was universal in human cells. Among these DON-induced changes in alternative splicing, the expression levels of two related splicing factors, SF1 and U2AF1, which are essential for 3' splice site recognitions, were strongly suppressed. Overexpression of either of the two splicing factors strongly alleviated the DON-induced aberrant selection of 3' splice sites. Moreover, SF1 was required for human cell proliferation in DON exposure, and the restoration of SF1 expression partially reinstated the proliferation potential for DON-treated cells. In conclusion, our study suggests that DON, even at a low dosage, has great potential to change gene expression globally by affecting not only protein synthesis but also mRNA processing in human cells.

Characterization of Phase I and Glucuronide Phase II Metabolites of 17 Mycotoxins Using Liquid Chromatography-High-Resolution Mass Spectrometry

Routine mycotoxin biomonitoring methods do not include many mycotoxin phase I and phase II metabolites, which may significantly underestimate mycotoxin exposure especially for heavily metabolized mycotoxins. Additional research efforts are also needed to measure metabolites in vivo after exposure and to establish which mycotoxin metabolites should be prioritized for the inclusion during large-scale biomonitoring efforts. The objective of this study was to perform human in vitro microsomal incubations of 17 mycotoxins and systematically characterize all resulting metabolites using liquid chromatography-high-resolution mass spectrometry (LC-HRMS). The results obtained were then used to build a comprehensive LC-MS library and expand a validated 17-mycotoxin method for exposure monitoring to screening of additional 188 metabolites, including 100 metabolites reported for the first time. The final method represents one of the most comprehensive LC-HRMS methods for mycotoxin biomonitoring or metabolism/fate studies.

Dietary Deoxynivalenol Exposure Assessment in University Students from Japan

This study was conducted to give a preliminary estimation of deoxynivalenol (DON) dietary exposure in Japanese university students (n = 30, aged 22-25 years) using a biomarker approach and to examine the correlation between wheat food intake and DON exposure levels. Spot urine samples were collected from 30 students of Azabu University, Tokyo. Urine samples were treated with enzyme digestion (for total DON measurement) and without (for unconjugated DON analysis) before clean-up using an immuno-affinity column and analysis using an LC-MS method, with a 13C15- DON internal standard used for accurate quantification. The limit of detection for this method is 0.5 ng/mL urine. The geometric mean (95% CI) of DON concentration was 2.03 (1.64 - 6.87) ng per mL urine. Ninety of the urine samples had detectable levels of urinary DON. The DON dietary intake exposure estimation suggested that one out of the 30 subjects had an intake of DON that exceeded Joint FAO/WHO Expert Committee on Food Additives (JECFA) provisional maximum tolerable daily intake (PMTDI) level. Mean ratio of free DON to total DON was determined to be 19%. Wheat intake assessed using a basic food frequent questionnaire method did not show a significant correlation with the urinary DON level.

Assessment of Urinary Deoxynivalenol Biomarkers in UK Children and Adolescents

Deoxynivalenol (DON), the mycotoxin produced mainly by Fusarium graminearum and found in contaminated cereal-based foodstuff, has been consistently detected in body fluids in adults. Available data in children and adolescents are scarce. This study assessed urinary DON concentrations in children aged 3-9 years (n = 40) and adolescents aged 10-17 years (n = 39) in the UK. Morning urine samples were collected over two consecutive days and analysed for free DON (un-metabolised form), DON-glucuronides (DON-GlcA), deepoxy deoxynivalenol (DOM-1), and total DON (sum of free DON, DON-GlcA, and DOM-1). Total DON was detected in the urine of >95% of children and adolescents on both days. Mean total DON concentrations (ng/mg creatinine) were 41.6 and 21.0 for children and adolescents, respectively. The greatest total DON levels were obtained in female children on both days (214 and 219 ng/mg creatinine on days 1 and 2, respectively). Free DON and DON-GlcA were detected in most urine specimens, whereas DOM-1 was not present in any sample. Estimation of dietary DON exposure suggested that 33-63% of children and 5-46% of adolescents exceeded current guidance regarding the maximum provisional tolerable daily intake (PMTDI) for DON. Although moderate mean urinary DON concentrations were shown, the high detection frequency of urinary DON, the maximum biomarker concentrations, and estimated dietary DON exposure are concerning.