Deoxynivalenol impairs the immune functions of neutrophils

New insights into micro-algal astaxanthin's effect on deoxynivalenol-induced spleen lymphocytes pyroptosis in Cyprinus carpio: Involving mitophagy and mtROS-NF-κB-dependent NLRP3 inflammasome

Deoxynivalenol (DON) is one of the most common sources of fungal toxins in fish feed, posing a significant risk to the immune and reproductive systems of fish. Microalgal astaxanthin (MIA), a potent antioxidant derived from microalgae, confers multifarious advantages upon piscine organisms, notably encompassing its anti-inflammatory and antioxidant prowess. Herein, we investigated the potential of MIA in ameliorating the immunotoxicity of DON on carp (Cyprinus carpio L.) based on spleen lymphocytes treated with DON (1.5 ng/ml) and/or MIA (96 μM). Firstly, CCK8 results showed that DON resulted in excessive death of spleen lymphocytes. Secondly, spleen lymphocytes treated with DON had a higher proportion of pyroptosis, and the mRNA and protein levels of pyroptosis (NLRP3, IL-1β and ASC) in spleen lymphocytes were increased. Thirdly, the relative red fluorescence intensity of JC-1 and DCFH-DA showed decreased mitochondrial membrane potential and increased ROS in spleen lymphocytes treated with DON. Mitochondrial ATP, DNA and NADPH/NADP+ analysis revealed decreased mitochondrial ATP, DNA and NADPH/NADP+ levels in DON-treated lymphocytes, corroborating the association between DON exposure and elevated intracellular ATP, DNA and NADPH/NADP+ in lymphocytes. DON exposure resulted in the downregulation of mitophagy-related genes and proteins (PINK1, Parkin and LC3) in lymphocytes. Notably, these effects were counteracted by treatment with MIA. Furthermore, DON led to the elevated secretion of inflammatory factors (TNF-α, IL-4 and IFN-γ), thereby inducing immune dysfunction in spleen lymphocytes. Encouragingly, MIA treatment effectively mitigated the immunotoxic effects induced by DON, demonstrating its potential in ameliorating pyroptosis, mitochondrial dysfunction and mitophagy impairment via regulating the mtROS-NF-κB axis in lymphocytes. This study sheds light on safeguarding farmed fish against agrobiological threats posed by DON, highlighting the valuable applications of MIA in aquaculture.

From ribosome to ribotoxins: understanding the toxicity of deoxynivalenol and Shiga toxin, two food borne toxins

Ribosomes that synthesize proteins are among the most central and evolutionarily conserved organelles. Given the key role of proteins in cellular functions, prokaryotic and eukaryotic pathogens have evolved potent toxins to inhibit ribosomal functions and weaken their host. Many of these ribotoxin-producing pathogens are associated with food. For example, food can be contaminated with bacterial pathogens that produce the ribotoxin Shiga toxin, but also with the fungal ribotoxin deoxynivalenol. Shiga toxin cleaves ribosomal RNA, while deoxynivalenol binds to and inhibits the peptidyl transferase center. Despite their distinct modes of action, both groups of ribotoxins hinder protein translation, but also trigger other comparable toxic effects, which depend or not on the activation of the ribotoxic stress response. Ribotoxic stress response-dependent effects include inflammation and apoptosis, whereas ribotoxic stress response-independent effects include endoplasmic reticulum stress, oxidative stress, and autophagy. For other effects, such as cell cycle arrest and cytoskeleton modulation, the involvement of the ribotoxic stress response is still controversial. Ribotoxins affect one organelle yet induce multiple toxic effects with multiple consequences for the cell. The ribosome can therefore be considered as the cellular "Achilles heel" targeted by food borne ribotoxins. Considering the high toxicity of ribotoxins, they pose a substantial health risk, as humans are highly susceptible to widespread exposure to these toxins through contaminated food sources.

Mycotoxin surveillance on wheats in Shandong province, China, reveals non-negligible probabilistic health risk of chronic gastrointestinal diseases posed by deoxynivalenol

Abnormal climate changes have resulted in over-precipitation in many regions. The occurrence and contamination levels of mycotoxins in crops and cereals have been elevated largely. From 2017 to 2019, we did investigation targeting 15 mycotoxins shown in the wheat samples collected from Shandong, a region suffering over-precipitation in China. We found that deoxynivalenol (DON) was the dominant mycotoxin contaminating wheats, with detection rates 304/340 in 2017 (89.41%), 303/330 in 2018 (91.82%), and 303/340 in 2019 (89.12%). The ranges of DON levels were < 4 to 580 μg/kg in 2017, < 4 to 3070 μg/kg in 2018, and < 4 to 1540 μg/kg in 2019. The exposure levels were highly correlated with local precipitation. Male exposure levels were generally higher than female's, with significant difference found in 2017 (1.89-fold, p = 0.023). Rural exposure levels were higher than that of cities but not statistically significant (1.41-fold, p = 0.13). Estimated daily intake (EDI) and margin of exposure (MoE) approaches revealed that 8 prefecture cities have probabilistically extra adverse health effects (vomiting or diarrhea) cases > 100 patients in 100,000 residents attributable to DON exposure. As a prominent wheat-growing area, Dezhou city reached ~ 300/100,000 extra cases while being considered as a major regional contributor to DON contamination. Our study suggests that more effort should be given to the prevention and control of DON contamination in major wheat-growing areas, particularly during heavy precipitation year. The mechanistic association between DON and chronic intestinal disorder/diseases should be further investigated.

4-Phenylbutyric acid alleviated 3-acetyldeoxynivalenol-induced immune cells response by inhibiting endoplasmic reticulum stress in mouse spleen

3-Acetyldeoxynivalenol (3-Ac-DON), an acetylated derivative of deoxynivalenol (DON), has contaminated grains and grain-based products in general and been harmful to human and animal health. However, the damage effects and regulatory mechanisms to the host immune system have not been well explored. In the present study, our results revealed that 3-Ac-DON significantly decreased spleen index, elevated MPO activity, upregulated mRNA and protein levels of IL-1α, IL-1β, IL-6, IL-17A, TNF-α, M-CSF, G-CSF, CCL2, IFN-β, and IL-10 in the spleen and serum. Interestingly, 4-phenylbutyric acid (4-PBA), an inhibitor of endoplasmic reticulum (ER) stress, largely abolished the above adverse effects. Importantly, 3-Ac-DON enhanced the mRNA abundances of ER stress-related indicators, such as BIP, IRE1A, ATF6, XBP-1, EIF2A, ATF4, and CHOP, which were abolished by 4-PBA, indicating the inhibiting effects of ER stress by 4-PBA in the spleen. Furthermore, 3-Ac-DON reshaped the populations of innate immune cells (neutrophils, macrophages, dendritic cells, natural killer cells) and adaptive immune cells (T lymphocytes, helper T cells, suppressor T cells, and B lymphocytes) in the peripheral blood and spleen lymphocytes. In conclusion, our studies demonstrated that the adverse effects of 3-Ac-DON on immune cells response could be implemented by ER stress and the ameliorative effect of 4-PBA.

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.

Zearalenone and deoxynivalenol inhibited IL-4 receptor-mediated Th2 cell differentiation and aggravated bacterial infection in mice

The immunotoxicity of zearalenone (ZEA) and deoxynivalenol (DON), two of the most common environmental mycotoxins, has been well investigated. However, due to the complexity of the immune system, especially during bacterial infection, many types of immune cells are involved in invasion resistance and bacterial clearance. Of these, T helper 2 (Th2) cells, which are members of the helper T cell family, assist B cells to activate and differentiate into antibody-secreting cells, participate in humoral immune response, and, ultimately, eliminate pathogens. Thus, it is important to identify the stage at which these toxins affect the immune function, and to clarity the underlying mechanisms. In this study, mice infected with Listeria monocytogenes (Listeria) were used to study the effects of ZEA, DON, and ZEA + DON on Th2 differentiation, Interleukin-4 Receptor (IL-4R) expression, costimulatory molecules expression and cytokine secretion after Listeria infection. Naive CD4+ T cells, isolated from mice, were used to verify the in vivo effects and the associated mechanisms. In vivo experiments showed that these toxins aggravated spleen damage after Listeria infection and reduced the differentiation of Th2 cells by affecting the synthesis of IL-4R of CD4+ T cells. In addition, the level of the costimulatory molecule CD154 decreased. Consistent with this, in vitro studies showed that these toxins inhibited the differentiation of mouse naive CD4+ T cell into Th2 subtype and decreased IL-4R levels. In addition, the levels of costimulatory molecules CD154, CD278 and the Th2 cells secrete cytokines IL-4, IL-6, and IL-10 decreased. Based on our in vivo and in vitro experiments, we suggest that ZEA, DON, and ZEA + DON inhibit the expression of costimulatory molecules on CD4+ T cell, and inhibit the IL-4R-mediated Th2 cell differentiation. This may indicate that the body cannot normally resist or clear the pathogen after mycotoxin poisoning.

Low doses of deoxynivalenol inhibit the cell migration mediated by H3K27me3-targeted downregulation of TEM8 expression

Deoxynivalenol (DON) is a mycotoxin produced by multipleFusariumspecies that often contaminates cereals and threatens human and animal health. A wide range of cytotoxic effects, such as the induction of DNA damage, an increase in mitochondrial permeability and the inhibition of macromolecule synthesis, have been reported. However, the effects of DON on cell migration-a fundamental process in living cells critical for normal development, immune responses, and disease processes-and the mechanism underlying these effects are still unclear. Here, we showed that DONsignificantly inhibited the migration of MRC-5, CCD-18Co, HCT116 and WM793 cells at 50 ng/ml, 50 ng/ml, 400 ng/ml and 250 ng/ml, respectively, which maintained cell viability at 90%. Further analysis showed that DON inhibited the expression of tumour endothelial marker 8 (TEM8), a key gene in cell migration. Furthermore, we showed that DON inhibited the expression of TEM8 through increasing the level of H3K27me3 in the TEM8 promoter. Finally, overexpression of TEM8 or treating by H3K27me3-specific inhibitor GSK126 attenuated the inhibitory effect of DON on cell migration. In summary, low doses of DON at approximately dietary exposure significantly inhibited cell migration by downregulating the expression of TEM8 in a manner mediated by H3K27me3, which may generate increasing concerns for the risk of DON exposure.

Paper-Based Microfluidic Device (DON-Chip) for Rapid and Low-Cost Deoxynivalenol Quantification in Food, Feed, and Feed Ingredients

Mycotoxin contamination causes over $5 billion of economic loss per year in the North American food and feed industry. A rapid, low-cost, portable, and reliable method for on-site detection of deoxynivalenol (DON), a representative mycotoxin predominantly occurring in grains, would be helpful to control mycotoxin contamination. In this study, a paper-based microfluidic chip capable of measuring DON (DON-Chip) in food, feed, and feed ingredients was developed. The DON-Chip incorporated a colorimetric competitive immunoassay into a paper microfluidic device and used gold nanoparticles as a signal indicator. Furthermore, a novel ratiometric analysis method was proposed to improve detection resolvability. Detection of DON in the aqueous extracts from solid food, feed, or feed ingredients was successfully validated with a detection range of 0.01-20 ppm (using dilution factors from 10 to 10⁴). Compared with conventional methods, the DON-Chip method could greatly reduce the cost and time of mycotoxin detection in the food and feed industry.

Trichothecenes: immunomodulatory effects, mechanisms, and anti-cancer potential

Paradoxically, trichothecenes have both immunosuppressive and immunostimulatory effects. The underlying mechanisms have not been fully explored. Early studies show that dose, exposure timing, and the time at which immune function is assessed influence whether trichothecenes act in an immunosuppressive or immunostimulatory fashion. Recent studies suggest that the immunomodulatory function of trichothecenes is also actively shaped by competing cell-survival and death-signaling pathways. Autophagy may also promote trichothecene immunosuppression, although the mechanism may be complicated. Moreover, trichothecenes may generate an "immune evasion" milieu that allows pathogens to escape host and vaccine immune defenses. Some trichothecenes, especially macrocyclic trichothecenes, also potently kill cancer cells. T-2 toxin conjugated with anti-cancer monoclonal antibodies significantly suppresses the growth of thymoma EL-4 cells and colon cancer cells. The type B trichothecene diacetoxyscirpenol specifically inhibits the tumor-promoting factor HIF-1 in cancer cells under hypoxic conditions. Trichothecin markedly inhibits the growth of multiple cancer cells with constitutively activated NF-κB. The type D macrocyclic toxin Verrucarin A is also a promising therapeutic candidate for leukemia, breast cancer, prostate cancer, and pancreatic cancer. The anti-cancer activities of trichothecenes have not been comprehensively summarized. Here, we first summarize the data on the immunomodulatory effects of trichothecenes and discuss recent studies that shed light on the underlying cellular and molecular mechanisms. These mechanisms include autophagy and major signaling pathways and their crosstalk. Second, the anti-cancer potential of trichothecenes and the underlying mechanisms will be discussed. We hope that this review will show how trichothecene bioactivities can be exploited to generate therapies against pathogens and cancer.

Study on the Association among Mycotoxins and other Variables in Children with Autism

Environmental factors and genetic susceptibility are implicated in the increased risk of autism spectrum disorder (ASD). Mycotoxins are agricultural contaminants of fungal origin that represent real risk factors for human health and especially for children. Thus, the main hypothesis of this work is that the deterioration of the clinical manifestation of autism in children may result from the exposure to mycotoxins through the consumption of contaminated food. Within a cross-sectional study, a group of autistic children (n = 172) and a group of controls (n = 61) (siblings and non-parental) were recruited in North and South Italy. All children had blood and urine samples taken, for testing some mycotoxins by a LC-MS/MS validated method. Blood samples were also tested for assessing specific IgG against food and fungal antigens and cytokines. The analyses outputs highlighted statistically significant differences comparing mycotoxins levels between (i) children groups both in urine (deoxynivalenol and de-epoxydeoxynivalenol, p = 0.0141 and p = 0.0259, respectively) and serum (aflatoxin M1, ochratoxin A and fumonisin B1, p = 0.0072, p = 0.0141 and p = 0.0061, respectively); (ii) a group of selected fungal IgGs, and IgGs against wheat and gluten and (iii) cytokines. These results suggest the need for a deeper examination of the role that mycotoxins may have on the etiology of ASD.

The Effect of Deoxynivalenol on Selected Populations of Immunocompetent Cells in Porcine Blood-A Preliminary Study

Deoxynivalenol (DON) is one of the most prevalent mycotoxins in Europe. Pigs are an animal species that is most susceptible to this mycotoxin. Deoxynivalenol causes significant losses in pig production by lowering feed intake, decreasing daily weight gains, disrupting immune responses, and increasing susceptibility to diseases. The aim of this experiment was to determine the influence of feed contaminated with DON at concentrations insignificantly higher than recommended by the European Commission (900 µg/kg). The experimental feed contained 1008 μg DON/kg. The experiment was performed on eight weaners from the same litter. The animals were randomly divided into two groups: an experimental group (M, n = 4) fed contaminated feed and a control group (C, n = 4) administered feed free of mycotoxins. The experiment lasted for six weeks, and peripheral blood samples were collected from the animals for analyses of selected morphological parameters and changes in the percentages of CD4⁺8-, CD4-8⁺, and CD4⁺8⁺ lymphocytes and antigen-presenting cells (APC) with CD14⁺172⁺ (monocytes), CD172ahigh4-14- (conventional dendritic cells, cDC), and CD172adim4⁺14- (plasmacytoid dendritic cells, pDC) phenotypes. The morphological parameters of porcine blood samples were determined by flow cytometry with non-fluorescent particle-size calibration standards, and no differences were observed between groups M and C. An immunophenotyping analysis of lymphocytes and dendritic cells (DC) revealed an increase in the percentage of CD4⁺8-, CD172ahigh4-14-, and CD172adim4⁺14- cells, and a decrease in the number of CD4-8⁺ cells in group M. The results of this experiment suggest that prolonged exposure to low doses of DON can change the proportions of immunocompetent cells (a shift towards humoral immunity), without affecting their overall counts.

Climate, Soil Management, and Cultivar Affect Fusarium Head Blight Incidence and Deoxynivalenol Accumulation in Durum Wheat of Southern Italy

Fusarium head blight (FHB) is a multifaceted disease caused by some species of Fusarium spp. A huge production of mycotoxins, mostly trichothecenes, often accompanied this disease. Amongst these toxic compounds, deoxynivalenol (DON) and its derivatives represent a major issue for human as well as for animal health and farming. Common and durum wheat are amongst the hosts of trichothecene-producing Fusaria. Differences in susceptibility to fungal infection and toxin accumulation occur in wheat cultivars. Recently, increasing incidence and severity of Fusarium infection and a higher DON accumulation in durum wheat were observed in Italy, especially in Northern regions. In this study, we analyzed wheat yield, technological parameters, the incidence of Fusarium infection and DON content in kernel samples of durum wheat coming from three locations of Southern Italy with different climatic conditions and grown during two seasons, with two methods of cultivation. Four different durum wheat cultivars prevalently cultivated in Southern Italian areas were chosen for this study. Our analysis showed the effects of environment and cultivar types on wheat productivity and key technological parameters for the quality level of the end-product, namely pasta. Notably, although a low rate of mycotoxin contamination in all study sites was assessed, an inverse relation emerged between fungal infection/DON production and durum wheat yield. Further, our study pinpoints the importance of environment conditions on several quality traits of durum wheat grown under Mediterranean climate. The environmental conditions at local level (microscale) and soil management practices may drive FHB outbreak and mycotoxin contamination even in growing area suitable for cropping this wheat species.

Exposure to zearalenone mycotoxin alters in vitro porcine intestinal epithelial cells by differential gene expression

The gut represents the main route of intoxication with mycotoxins. To evaluate the effect and the underlying molecular changes that occurred when the intestine is exposed to zearalenone, a Fusarium sp mycotoxin, porcine epithelial cells (IPEC-1) were treated with 10μM of ZEA for 24h and analysed by microarray using Gene Spring GX v.11.5. Our results showed that 10μM of ZEA did not affect cell viability, but can increase the expression of toll like receptors (TLR1-10) and of certain cytokines involved in inflammation (TNF-α, IL-1β, IL-6, IL-8, MCP-1, IL-12p40, CCL20) or responsible for the recruitment of immune cells (IL-10, IL-18). Microarray results identified 190 genes significantly and differentially expressed, of which 70% were up-regulated. ZEA determined the over expression of ITGB5 gene, essential against the attachment and adhesion of ETEC to porcine jejunal cells and of TFF2 implicated in mucosal protection. An up-regulation of glutathione peroxidase enzymes (GPx6, GPx2, GPx1) was also observed. Upon ZEA challenge, genes like GTF3C4 responsible for the recruitment of polymerase III and initiation of tRNA transcription in eukaryotes and STAT5B were significantly higher induced. The up-regulation of CD97 gene and the down-regulation of tumour suppressor genes (DKK-1, PCDH11X and TC531386) demonstrates the carcinogenic potential of ZEA.

Immunohistochemical detection of interleukin-8 in inflamed porcine tissues

The objective of this study was to identify the specific localization of interleukin-8 (IL-8) in cells in situ in a variety of inflammatory processes in different tissues from pigs. Our hypothesis was that IL-8 primarily is a neutrophil related cytokine present in all extravascular neutrophils while expression also occurs in other cell types in response to an inflammatory stimulus. Using IL-8 immunohistochemistry we discovered that neutrophils were the predominant IL-8 positive cell population while epithelial cell types and endothelium of postcapillary venules could be positive when situated in close vicinity of an inflammatory lesion. Furthermore, endothelial cells of newly formed vessels in granulation tissue were positive in some specimens. Some sub-populations of inflammatory neutrophils were, however, IL-8 negative which could reflect some phase of neutrophil swarming.