Assessment of single-nucleotide variant discovery protocols in RNA-seq data from human cells exposed to mycotoxins

Food and feed contamination by nonlegislated mycotoxins beauvericin (BEA) and enniatin B (ENB) is a worldwide health concern in the present. The principal objective of this work is to assess some of the existing protocols to discover the single nucleotide variants (SNVs) in transcriptomic data obtained by RNA-seq from Jurkat cells in vitro samples individually exposed to BEA and ENB at three concentration levels (1.5, 3 and 5 µM). Moreover, previous transcriptomic results will be compared with new findings obtained using a different protocol. SNVs rs201003509 in BEA exposed cells and the rs36045790 in ENB were found in the differentially expressed genes in all doses compared to controls by means of the Genome Analysis Toolkit (GATK) Best Practices workflow. SNV-RNA-seq complementary pipeline did not show any SNV. Concerning gene expression, discrepant results were found for 1.5 µM BEA exposed cells compared with previous findings. However, 354 overlapped differentially expressed genes (DEGs) were identified in the three ENB concentrations used, with 147 matches with respect to the 245 DEGs found in the previous results. In conclusion, the two discovery SNVs protocols based on variant calling from RNA-seq used in this work displayed very different results and there were SNVs found manually not identified by any pipeline. Additionally, the new gene expression analysis reported comparable but non identical DEGs to the previous transcriptomic results obtained from these RNA-seq data.

Occurrence and Dietary Exposure Assessment to Enniatin B through Consumption of Cereal-Based Products in Spain and the Catalonia Region

Enniatin B (ENNB) is a mycotoxin produced by moulds from the Fusarium genera and its toxic effects are still not fully elucidated, hence a safe reference exposure value has not been established yet. ENNB is the most prevalent emerging mycotoxin and is widely found in cereal-based products, nevertheless, there are no comprehensive exposure assessment studies. For that reason, the aim of this study was to characterise the occurrence of ENNB and estimate the exposure of the Spanish and Catalan populations. A total of 347 cereal-based products were collected in 2019 and were analysed using liquid chromatography-tandem mass spectrometry. Consumption data were obtained from the national food consumption surveys (ENALIA) and a regional survey conducted in Catalonia. The global exposure was estimated using deterministic and probabilistic methods. The results showed a high occurrence of close to 100% in all foodstuffs, with a range from 6 to 269 µg/kg, and a strong correlation with the levels of deoxynivalenol. Children aged one-nine years were the most exposed, showing mean estimates in the range 308-324 ng/kg bw/day and 95th percentiles 697-781 ng/kg bw/day. This study stresses the need for further toxicological data to establish reference doses and conclude formal risk assessment, accounting for the co-occurrence with deoxynivalenol.

Pilot Study: Does Contamination with Enniatin B and Beauvericin Affect the Antioxidant Capacity of Cereals Commonly Used in Animal Feeding?

Increasing consumption of cereals has been associated with reduced risk of several chronic diseases, as they contain phytochemicals that combat oxidative stress. Cereal contamination by the “emerging mycotoxins” beauvericin (BEA) and enniatins (ENs) is a worldwide health problem that has not yet received adequate scientific attention. Their presence in feeds represents a risk for animals and a potential risk for humans because of their carry-over to animal-derived products. This preliminary study aimed to investigate if the total antioxidant capacity (TAC) of corn, barley, and wheat flours could be influenced by contamination with increasing levels of BEA and ENN B. The highest TAC value was observed in barley compared with wheat and corn (p < 0.001) before and after contamination. No effect of mycotoxin or mycotoxin level was found, whereas cereal x mycotoxin exhibited a significant effect (p < 0.001), showing a lower TAC value in wheat contaminated by ENN B and in barley contaminated by BEA. In conclusion, barley is confirmed as a source of natural antioxidants with antiradical potentials. Additional studies with a larger sample size are necessary to confirm the obtained results, and investigations of the toxic effects of these emergent mycotoxins on animals and humans should be deepened.

A Review of the Mycotoxin Enniatin B

Mycotoxin enniatin B (ENN B) is a secondary metabolism product by Fusarium fungi. It is a well-known antibacterial, antihelmintic, antifungal, herbicidal, and insecticidal compound. It has been found as a contaminant in several food commodities, particularly in cereal grains, co-occurring also with other mycotoxins. The primary mechanism of action of ENN B is mainly due to its ionophoric characteristics, but the exact mechanism is still unclear. In the last two decades, it has been a topic of great interest since its potent mammalian cytotoxic activity was demonstrated in several mammalian cell lines. Moreover, the co-exposure in vitro with other mycotoxins enhances its toxic potential through synergic effects, depending on the concentrations tested. Despite its clear cytotoxic effect, European Food Safety Authority stated that acute exposure to ENNs, such as ENN B, does not indicate concern for human health, but a concern might be the chronic exposure. However, given the lack of relevant toxicity data, no firm conclusion could be drawn and a risk assessment was not possible. In fact, very few studies have been carried out in vivo and, in these studies, no adverse effects were observed. So, research on toxicological effects induced by ENN B is still on-going. Recently, some studies are dealing with new advances regarding ENN B. This review summarizes the information on biochemical and biological activity of ENN B, focusing on toxicological aspects and on the latest advances in research on ENN B.

Comparative Oral Bioavailability, Toxicokinetics, and Biotransformation of Enniatin B1 and Enniatin B in Broiler Chickens

A toxicokinetic study of the Fusarium mycotoxins enniatin B1 (ENN B1) and enniatin B (ENN B) was performed in broiler chickens. Each animal received ENN B1 or B orally via an intracrop bolus and intravenously at a dose of 0.2 mg/kg body weight. Both enniatins were poorly absorbed after oral administration, with absolute oral bioavailabilities of 0.05 and 0.11 for ENNs B1 and B, respectively. Both enniatins were readily distributed to the tissues, with mean volumes of distribution of 25.09 and 33.91 L/kg for ENNs B1 and B, respectively. The mean total body clearance was rather high, namely, 6.63 and 7.10 L/h/kg for ENNs B1 and B, respectively. Finally, an UHPLC-HRMS targeted approach was used to investigate the phase I and II biotransformations of both mycotoxins. Oxygenation was the major phase I biotransformation pathway for both ENNs B1 and B. Neither glucuronide nor sulfate phase II metabolites were detected.