Recent Advances and Perspectives in Deoxynivalenol Research

Mycotoxins are secondary metabolites produced by molds. Although the primary role of these toxins is thought to be related to the colonisation of the environment by the fungi—mycotoxins are able to kill other micro-organisms (antimicrobial effect) and/or plant cells (mycotoxin-producing fungi being necrophagic)—the exposure of animals and humans to mycotoxins through the consumption of mycotoxin-contaminated food and feeds leads to diseases and death. Among the different mycotoxins described (more than 350 mycotoxins have been identified), deoxynivalenol (DON or vomitoxin) produced by Fusarium species has attracted the most attention due to its prevalence and toxicity. DON is part of a family of mycotoxins called trichothecenes that are small sesquiterpenoids with an epoxide group at positions 12–13 allowing their binding to ribosomes causing the so-called ribosome stress response, characterized by the activation of various protein kinases that lead to alterations in gene expression and cellular toxicity in animals, humans and plants. Here, we compiled very recent findings regarding DON and its derivatives: i) their prevalence in human food; ii) the estimation of the exposure of humans to them using biological markers; iii) their roles during plant–fungi interaction; iv) the alteration caused by them in animals and humans, particularly at low doses that are close to those observed in farm animals and human consumers; v) possible strategies to decrease their presence in food and feeds. Overall, this book will give the reader a clear and global view on this important mycotoxin produced by Fusarium species which is responsible for huge economic loss and health issues

Reinforcing and broadening resistance against Fusarium diseases in durum wheat by an udp-glucosyltransferase transgene and its pyramiding with a pectin methyl esterase inhibitor transgene

Many species of the genus Fusarium are phytopathogenic fungi of a wide range of cereal crop plants, including wheat. F. graminearum is the main causal agent of Fusarium Head Blight (FHB), while F. culmorum and F. pseudograminearum are the main responsible species of Fusarium Crown Rot (FCR). Fusarium diseases represent major agricultural problems worldwide, causing reduction of grain yield, grain quality and food safety. The latter is associated with contamination of grains with mycotoxins, particularly deoxynivalenol (DON), which cause health problems in humans and animals. DON is a protein synthesis inhibitor, acting as a virulence factor during pathogenesis and resulting essential for fungal spread along the spike. Conversion of DON to deoxynivalenol-3-\u3b2-D-glucoside (D3G) by the activity of specific UDP-glucosyltransferases (UGTs), is one of the mechanisms involved in enhancing plant tolerance to DON. Previous studies demonstrated that the expression of the barley HvUGT13248 gene confers resistance to DON in Arabidopsis thaliana (Shin et al. 2012, J Exp Bot. 63:4731-40) and type II resistance to FHB (i.e. resistance to fungal spread within host tissues) in bread wheat (Li et al. 2015, MPMI 28:1237-46). Improvement of FHB resistance is a major target in both bread and durum wheat. The latter, however, is especially vulnerable, as effective sources of resistance are particularly limited. Therefore, we decided to verify whether the expression of the HvUGT13248 gene could enhance FHB resistance in durum wheat as well. To this aim, transgenic lines of Triticum durum cv. Svevo, constitutively expressing the HvUGT13248 gene, were produced. Transgenic plants in which presence of transcript and protein was confirmed, were infected with F. graminearum and evaluated for FHB severity, DON content and D3G conversion as compared to wild type plants. Our results showed that the HvUGT13248 gene determines in durum wheat a significant reduction of FHB symptoms (up to 30%) compared to control plants. This effect, however, was mainly evident at early infection stages, progressively decreasing at later stages. This outcome differs from what observed in transgenic bread wheat expressing the same UGT gene, in which FHB severity did not exceed 20% up to the last stages of infection (Li et al. 2015). To verify further the effectiveness of the DON-detoxifying approach, durum wheat lines with the same HvUGT13248 transgene were challenged with F. culmorum, also able to produce DON. A significant reduction of FCR symptoms compared to Svevo plants was observed. This represents the first report of improvement of FCR resistance associated with overexpression of an UGT involved in DON-detoxification. Recently, in order to combine in the same plant genes controlling two different mechanisms of type II resistance to FHB, we have crossed two types of durum wheat transgenic lines, one expressing the HvUGT13248 gene, the other AcPMEI, coding for a kiwi pectin methyl esterase inhibitor, known to increase resistance by strengthening the cell wall pectin fraction. On selected carriers of both transgenes, and in control lines with individual or no transgenes, the efficacy of the novel assembly will be verified against FHB and FCR

Mislocalization of the exitatory amino-acid transporters (EAATs) in human astrocytoma and non-astrocytoma cancer cells: effect of the cell confluence

<p>Abstract</p> <p>Background</p> <p>Astrocytomas are cancers of the brain in which high levels of extracellular glutamate plays a critical role in tumor growth and resistance to conventional treatments. This is due for part to a decrease in the activity of the glutamate transporters, i.e. the Excitatory Amino Acid Transporters or EAATs, in relation to their nuclear mislocalization in astrocytoma cells. Although non-astrocytoma cancers express EAATs, the localization of EAATs and the handling of L-glutamate in that case have not been investigated.</p> <p>Methods</p> <p>We looked at the cellular localization and activity of EAATs in human astrocytoma and non-astrocytoma cancer cells by immunofluorescence, cell fractionation and L-glutamate transport studies.</p> <p>Results</p> <p>We demonstrated that the nuclear mislocalization of EAATs was not restricted to astrocytoma and happened in all sub-confluent non-astrocytoma cancer cells we tested. In addition, we found that cell-cell contact caused the relocalization of EAATs from the nuclei to the plasma membrane in all human cancer cells tested, except astrocytoma.</p> <p>Conclusions</p> <p>Taken together, our results demonstrated that the mislocalization of the EAATs and its associated altered handling of glutamate are not restricted to astrocytomas but were also found in human non-astrocytoma cancers. Importantly, we found that a cell contact-dependent signal caused the relocalization of EAATs at the plasma membrane at least in human non-astrocytoma cancer cells, resulting in the correction of the altered transport of glutamate in such cancer cells but not in astrocytoma.</p

Ethnopharmacology and therapeutic potential of Anchusa strigosa: a comprehensive review

Anchusa strigosa Banks and Sol. is a rough flowering plant of the Boraginaceae family native to Eastern Mediterranean region that is widely used in traditional herbal medicine, mainly for the treatment of wounds, abdominal pain, and arthritis, to name a few. This article aims to gather knowledge related to the medicinal properties of A. strigosa. Specifically, it summarizes its traditional uses and pharmacological activities in the treatment of various diseases. Moreover, its botanical, ecological, and phytochemical characteristics are also discussed. Research showed that this plant is rich in pyrrolizidine alkaloids, particularly in the leaves. Other bioactive metabolites identified in this plant include flavonoids, phenolic acids, triterpenes, organic acids, and volatile organic compounds. These phytochemicals are responsible for the reported pharmacological properties of A. strigosa, including antimicrobial, antioxidant, anticancer, anti-inflammatory, antiarthritic, gastric protective, antidiabetic, and pro-wound healing. This warrants further investigation into the molecular mechanism of action behind the observed effects to elucidate its therapeutic potential. Nevertheless, more research on this plant is needed to ensure its efficacy and safety

Investigating Host Microbiota Relationships Through Functional Metagenomics

The human Intestinal mucus is formed by glycoproteins, the O- and N-linked glycans which constitute a crucial source of carbon for commensal gut bacteria, especially when deprived of dietary glycans of plant origin. In recent years, a dozen carbohydrate-active enzymes from cultivated mucin degraders have been characterized. But yet, considering the fact that uncultured species predominate in the human gut microbiota, these biochemical data are far from exhaustive. In this study, we used functional metagenomics to identify new metabolic pathways in uncultured bacteria involved in harvesting mucin glycans. First, we performed a high-throughput screening of a fosmid metagenomic library constructed from the ileum mucosa microbiota using chromogenic substrates. The screening resulted in the isolation of 124 clones producing activities crucial in the degradation of human O- and N-glycans, namely sialidases, beta-D-N-acetyl-glucosaminidase, beta-D-N-acetyl-galactosaminidase, and/or beta-D-mannosidase. Thirteen of these clones were selected based on their diversified functional profiles and were further analyzed on a secondary screening. This step consisted of lectin binding assays to demonstrate the ability of the clones to degrade human intestinal mucus. In total, the structural modification of several mucin motifs, sialylated mucin ones in particular, was evidenced for nine clones. Sequencing their metagenomic loci highlighted complex catabolic pathways involving the complementary functions of glycan sensing, transport, hydrolysis, deacetylation, and deamination, which were sometimes associated with amino acid metabolism machinery. These loci are assigned to several Bacteroides and Feacalibacterium species highly prevalent and abundant in the gut microbiome and explain the metabolic flexibility of gut bacteria feeding both on dietary and human glycans

Effect of Bacillus subtilis Strains on Intestinal Barrier Function and Inflammatory Response

Strong tight junctions and curtailed inflammatory responses under stressful conditions are key for optimal digestive health. Bacillus-based probiotics are increasingly being used to maintain broilers' health, but their mode of action is often not well-defined. In the present study we used Caco-2 cells as a model for intestinal epithelia and assessed the effect of three Bacillus-based probiotics on intestinal barrier function and intestinal inflammation. Experimental results showed that one of the three tested strains, Bs 29784, significantly reinforced intestinal barrier integrity under basal conditions through an up-regulation of the expression of tight junction's proteins, whereas the others had no or detrimental effects. When Caco-2 cells were pre-treated with Bacillus subtilis strains, the subsequent IL-8 release to various pro-inflammatory signals (IL-1β, deoxynivalenol, or flagellin) was blunted compared to cells that had not been pretreated, but to a different extent depending on the strain of Bacillus used. Bs 29784, was able to significantly decrease IL-8 production in all stressed conditions tested. Mechanistically, Bs 29784 appeared to limit nuclear translocation of NF-κB during IL-1β exposure by preventing IκB degradation. The effects of Bs 29784 were observed independently with supernatant and cells but in a lesser extent than with the combination, indicating that they can thus likely be attributed to both secreted metabolites and cell-associated compounds. Moreover, under inflammatory conditions, Bs 29784 significantly reduced the upregulation of iNOS protein levels further underlining its intestinal anti-inflammatory potential. Our data show that Bacillus-based probiotics may indeed improve digestive health by strengthening intestinal barrier and limiting inflammatory responses and that these properties are strain-dependent

In silico identification of two peptides with antibacterial activity against multidrug-resistant Staphylococcus aureus

Here we report two antimicrobial peptides (AMPs), HG2 and HG4 identified from a rumen microbiome metagenomic dataset, with activity against multidrug-resistant (MDR) bacteria, especially methicillin-resistant Staphylococcus aureus (MRSA) strains, a major hospital and community-acquired pathogen. We employed the classifier model design to analyse, visualise, and interpret AMP activities. This approach allowed in silico discrimination of promising lead AMP candidates for experimental evaluation. The lead AMPs, HG2 and HG4, are fast-acting and show anti-biofilm and anti-inflammatory activities in vitro and demonstrated little toxicity to human primary cell lines. The peptides were effective in vivo within a Galleria mellonella model of MRSA USA300 infection. In terms of mechanism of action, HG2 and HG4 appear to interact with the cytoplasmic membrane of target cells and may inhibit other cellular processes, whilst preferentially binding to bacterial lipids over human cell lipids. Therefore, these AMPs may offer additional therapeutic templates for MDR bacterial infections

In silico identification of two peptides with antibacterial activity against multidrug-resistant Staphylococcus aureus

Here we report two antimicrobial peptides (AMPs), HG2 and HG4 identified from a rumen microbiome metagenomic dataset, with activity against multidrug-resistant (MDR) bacteria, especially methicillin-resistant Staphylococcus aureus (MRSA) strains, a major hospital and community-acquired pathogen. We employed the classifier model design to analyse, visualise, and interpret AMP activities. This approach allowed in silico discrimination of promising lead AMP candidates for experimental evaluation. The lead AMPs, HG2 and HG4, are fast-acting and show anti-biofilm and anti-inflammatory activities in vitro and demonstrated little toxicity to human primary cell lines. The peptides were effective in vivo within a Galleria mellonella model of MRSA USA300 infection. In terms of mechanism of action, HG2 and HG4 appear to interact with the cytoplasmic membrane of target cells and may inhibit other cellular processes, whilst preferentially binding to bacterial lipids over human cell lipids. Therefore, these AMPs may offer additional therapeutic templates for MDR bacterial infections

The rumen microbiome:An underexplored resource for novel antimicrobial discovery

Antimicrobial peptides (AMPs) are promising drug candidates to target multi-drug resistant bacteria. The rumen microbiome presents an underexplored resource for the discovery of novel microbial enzymes and metabolites, including AMPs. Using functional screening and computational approaches, we identified 181 potentially novel AMPs from a rumen bacterial metagenome. Here, we show that three of the selected AMPs (Lynronne-1, Lynronne-2 and Lynronne-3) were effective against numerous bacterial pathogens, including methicillin-resistant Staphylococcus aureus (MRSA). No decrease in MRSA susceptibility was observed after 25 days of sub-lethal exposure to these AMPs. The AMPs bound preferentially to bacterial membrane lipids and induced membrane permeability leading to cytoplasmic leakage. Topical administration of Lynronne-1 (10% w/v) to a mouse model of MRSA wound infection elicited a significant reduction in bacterial counts, which was comparable to treatment with 2% mupirocin ointment. Our findings indicate that the rumen microbiome may provide viable alternative antimicrobials for future therapeutic applicationpublishersversionPeer reviewe

Squalamine: An Appropriate Strategy against the Emergence of Multidrug Resistant Gram-Negative Bacteria?

We reported that squalamine is a membrane-active molecule that targets the membrane integrity as demonstrated by the ATP release and dye entry. In this context, its activity may depend on the membrane lipid composition. This molecule shows a preserved activity against bacterial pathogens presenting a noticeable multi-resistance phenotype against antibiotics such as polymyxin B. In this context and because of its structure, action and its relative insensitivity to efflux resistance mechanisms, we have demonstrated that squalamine appears as an alternate way to combat MDR pathogens and by pass the gap regarding the failure of new active antibacterial molecules