Combination of Selenomethionine and N-Acetylcysteine Alleviates the Joint Toxicities of Aflatoxin B1 and Ochratoxin A by ERK MAPK Signal Pathway in Porcine Alveolar Macrophages

Energy Metabolism Enhance Perylenequinone Biosynthesis in Shiraia sp. Slf14 through Promoting Mitochondrial ROS Accumulation

Perylenequinones (PQs) are important natural compounds that have been extensively utilized in recent years as agents for antimicrobial, anticancer, and antiviral photodynamic therapies. In this study, we investigated the molecular mechanisms regulating PQ biosynthesis by comparing Shiraia sp. Slf14 with its low PQ titer mutant, Slf14(w). The results indicated that the strain Slf14 exhibited a higher PQ yield, a more vigorous energy metabolism, and a more pronounced oxidation state compared to Slf14(w). Transcriptome analysis consistently revealed that the differences in gene expression between Slf14 and Slf14(w) are primarily associated with genes involved in redox processes and energy metabolism. Additionally, reactive oxygen species (ROS) were shown to play a crucial role in promoting PQ synthesis, as evidenced by the application of ROS-related inhibitors and promoters. Further results demonstrated that mitochondria are significant sources of ROS, which effectively regulate PQ biosynthesis in Shiraia sp. Slf14. In summary, this research revealed a noteworthy finding: the higher energy metabolism of the strain Slf14 is associated with increased intracellular ROS accumulation, which in turn triggers the activation and expression of gene clusters responsible for PQ synthesis.

Selenium maintains intestinal epithelial cells to activate M2 macrophages against deoxynivalenol injury

Selenium (Se) is indispensable in alleviating various types of intestinal injuries. Here, we thoroughly investigated the protective effect of Se on the regulation of the epithelial cell-M2 macrophages pathway in deoxynivalenol (DON)-induced intestinal damage. In the present study, Se has positive impacts on gut health by improving gut barrier function and reducing the levels of serum DON in vivo. Furthermore, our study revealed that Se supplementation increased the abundances of GPX4, p-PI3K, and AKT, decreased the levels of 4-HNE and inhibited ferroptosis. Moreover, when mice were treated with DON and Fer-1(ferroptosis inhibitor), ferroptosis was suppressed and PI3K/AKT pathway was activated. These results indicated that GPX4-PI3K/AKT-ferroptosis was a predominant pathway in DON-induced intestinal inflammation. Interestingly, we discovered that both the number of M2 anti-inflammatory macrophages and the levels of CSF-1 decreased while the pro-inflammatory cytokine IL-6 increased in the intestine and MODE-K cells supernatant. Therefore, Se supplementation activated the CSF-1-M2 macrophages axis, resulting in a decrease in IL-6 expression and an enhancement of the intestinal anti-inflammatory capacity. This study provides novel insights into how intestinal epithelial cells regulate the CSF-1-M2 macrophage pathway, which is essential in maintaining intestinal homeostasis confer to environmental hazardous stimuli.

Selenomethionine protects the liver from dietary deoxynivalenol exposure via Nrf2/PPARγ-GPX4-ferroptosis pathway in mice

Deoxynivalenol (DON) is a significant Fusarium toxin that has gained global attention due to its high frequency of contamination in food and feed. It was reported to have hepatotoxicity, immunotoxicity, and reproduction toxicity in organs. On the other hand, Selenomethionine (SeMet) was proven to have anti-oxidation, tissue repairing, immunity improvement, and antifungal mycotoxin infection functions. However, the molecular mechanism by which SeMet alleviates DON damage is not yet clear. C57BL/6 mice were randomly divided into three groups, Se-A and Se-A+DON were fed with a diet containing 0.2 mg/kg Se whereas Se-S+DON were fed with a diet of 1.0 mg/kg Se. After feeding for four weeks, the mice were gavaged for 21 days with DON (2.0 mg/kg BW) or ultrapure water once per day. In the present study, we showed that SeMet significantly decreased the lipid peroxidation product malondialdehyde, and increased activities of antioxidant enzymes superoxide dismutase and total antioxidant capacity after DON exposure. In addition, our investigation revealed that SeMet regulated pathways related to lipid synthesis and metabolisms, and effectively mitigated DON-induced liver damage. Moreover, we have discovered that SeMet downregulation of N-acylethanolamine and HexCer accumulation induced hepatic lipotoxicity. Further study showed that SeMet supplementation increased protein levels of glutathione peroxidase 4 (GPX4), peroxisome proliferator-activated receptor γ (PPARγ), nuclear erythroid 2-related factor 2 (Nrf2), and upregulated target proteins, indicating suppression of oxidative stress in the liver. Meanwhile, we found that SeMet significantly reduced the DON-induced protein abundances of Bcl2, Beclin1, LC3B and proteins related to ferroptosis (Lpcat3, and Slc3a2), and downregulation of Slc7a11. In conclusion, SeMet protected the liver from damage by enhancing the Nrf2/PPARγ-GPX4-ferroptosis pathway, inhibiting lipid accumulation and hepatic lipotoxicity. The findings of this study indicated that SeMet has a positive impact on liver health by improving antioxidant capacity and relieving lipotoxicity in toxin pollution.

Sustainable and efficient method utilizing N-acetyl-L-cysteine for complete and enhanced ochratoxin A clearance by antagonistic yeast

With the increasing global climate change, ochratoxin A (OTA) pollution in food and environment has become a serious and potential risk element threatening food safety and human health. Biodegradation of mycotoxin is an eco-friendly and efficient control strategy. Still, research works are warranted to develop low-cost, efficient, and sustainable approaches to enhance the mycotoxin degradation efficiency of microorganisms. In this study, the activities of N-acetyl-L-cysteine (NAC) against OTA toxicity were evidenced, and its positive effects on the OTA degradation efficiency of antagonistic yeast, Cryptococcus podzolicus Y3 were verified. Co-culturing C. podzolicus Y3 with 10 mM NAC improved 100% and 92.6% OTA degradation rate into ochratoxin α (OTα) at 1 d and 2 d. The excellent promotion role of NAC on OTA degradation was observed even at low temperatures and alkaline conditions. C. podzolicus Y3 treated with OTA or OTA+NAC promoted reduced glutathione (GSH) accumulation. GSS and GSR genes were highly expressed after OTA and OTA+NAC treatment, contributing to GSH accumulation. In the early stages of NAC treatment, yeast viability and cell membrane were reduced, but the antioxidant property of NAC prevented lipid peroxidation. Our finding provides a sustainable and efficient new strategy to improve mycotoxin degradation by antagonistic yeasts, which could be applied to mycotoxin clearance.

Astaxanthin Alleviates Aflatoxin B1-Induced Oxidative Stress and Apoptosis in IPEC-J2 Cells via the Nrf2 Signaling Pathway

Aflatoxin B1 (AFB1), a typical fungal toxin found in feed, is highly carcinogenic. Oxidative stress is one of the main ways it exerts its toxicity; therefore, finding a suitable antioxidant is the key to reducing its toxicity. Astaxanthin (AST) is a carotenoid with strong antioxidant properties. The aim of the present research was to determine whether AST eases the AFB1-induced impairment in IPEC-J2 cells, and its specific mechanism of action. AFB1 and AST were applied to IPEC-J2 cells in different concentrations for 24 h. The AST (80 µM) significantly prevented the reduction in the IPEC-J2 cell viability that was induced by AFB1 (10 μM). The results showed that treatment with AST attenuated the AFB1-induced ROS, and cytochrome C, the Bax/Bcl2 ratio, Caspase-9, and Caspase-3, which were all activated by AFB1, were among the pro-apoptotic proteins which were diminished by AST. AST activates the Nrf2 signaling pathway and ameliorates antioxidant ability. This was further evidenced by the expression of the HO-1, NQO1, SOD2, and HSP70 genes were all upregulated. Taken together, the findings show that the impairment of oxidative stress and apoptosis, caused by the AFB1 in the IPEC-J2 cells, can be attenuated by AST triggering the Nrf2 signaling pathway.

BDE-47 Induces Immunotoxicity in RAW264.7 Macrophages through the Reactive Oxygen Species-Mediated Mitochondrial Apoptotic Pathway

Polybrominated diphenyl ethers (PBDEs) are classic and emerging pollutants that are potentially harmful to the human immune system. Research on their immunotoxicity and mechanisms suggests that they play an important role in the resulting pernicious effects of PBDEs. 2,2',4,4'-Tetrabrominated biphenyl ether (BDE-47) is the most biotoxic PBDE congener, and, in this study, we evaluated its toxicity toward RAW264.7 cells of mouse macrophages. The results show that exposure to BDE-47 led to a significant decrease in cell viability and a prominent increase in apoptosis. A decrease in mitochondrial membrane potential (MMP) and an increase in cytochrome C release and caspase cascade activation thus demonstrate that cell apoptosis induced by BDE-47 occurs via the mitochondrial pathway. In addition, BDE-47 inhibits phagocytosis in RAW264.7 cells, changes the related immune factor index, and causes immune function damage. Furthermore, we discovered a significant increase in the level of cellular reactive oxygen species (ROS), and the regulation of genes linked to oxidative stress was also demonstrated using transcriptome sequencing. The degree of apoptosis and immune function impairment caused by BDE-47 could be reversed after treatment with the antioxidant NAC and, conversely, exacerbated by treatment with the ROS-inducer BSO. These findings indicate that oxidative damage caused by BDE-47 is a critical event that leads to mitochondrial apoptosis in RAW264.7 macrophages, ultimately resulting in the suppression of immune function.

Effects of Compound Mycotoxin Detoxifier on Alleviating Aflatoxin B1-Induced Inflammatory Responses in Intestine, Liver and Kidney of Broilers

In order to alleviate the toxic effects of aflatoxins B1 (AFB1) on inflammatory responses in the intestine, liver, and kidney of broilers, the aflatoxin B1-degrading enzyme, montmorillonite, and compound probiotics were selected and combined to make a triple-action compound mycotoxin detoxifier (CMD). The feeding experiment was divided into two stages. In the early feeding stage (1−21 day), a total of 200 one-day-old Ross broilers were randomly divided into four groups; in the later feeding stage (22−42 day), 160 broilers aged at 22 days were assigned to four groups: Group A: basal diet (4.31 μg/kg AFB1); Group B: basal diet with 40 μg/kg AFB1; Group C: Group A plus 1.5 g/kg CMD; Group D: Group B plus 1.5 g/kg CMD. After the feeding experiment, the intestine, liver, and kidney tissues of the broilers were selected to investigate the molecular mechanism for CMD to alleviate the tissue damages. Analyses of mRNA abundances and western blotting (WB) of inflammatory factors, as well as immunohistochemical (IHC) staining of intestine, liver, and kidney tissues showed that AFB1 aggravated the inflammatory responses through NF-κB and TN-α signaling pathways via TLR pattern receptors, while the addition of CMD significantly inhibited the inflammatory responses. Phylogenetic investigation showed that AFB1 significantly increased interleukin-1 receptor-associated kinase (IRAK-1) and mitogen-activated protein kinase (MAPK) activities (p < 0.05), which were restored to normal levels by CMD addition, indicating that CMD could alleviate cell inflammatory damages induced by AFB1.

Seleno-Metabolites and Their Precursors: A New Dawn for Several Illnesses?

Selenium (Se) is an essential element for human health as it is involved in different physiological functions. Moreover, a great number of Se compounds can be considered potential agents in the prevention and treatment of some diseases. It is widely recognized that Se activity is related to multiple factors, such as its chemical form, dose, and its metabolism. The understanding of its complex biochemistry is necessary as it has been demonstrated that the metabolites of the Se molecules used to be the ones that exert the biological activity. Therefore, the aim of this review is to summarize the recent information about its most remarkable metabolites of acknowledged biological effects: hydrogen selenide (HSe-/H2Se) and methylselenol (CH3SeH). In addition, special attention is paid to the main seleno-containing precursors of these derivatives and their role in different pathologies.

Genome-Scale CRISPR Knockout Screening Identifies BACH1 as a Key Regulator of Aflatoxin B1-Induced Oxidative Damage

Aflatoxin B₁ (AFB₁) is amongst the mycotoxins commonly affecting human and animal health, raising global food safety and control concerns. The mechanisms underlying AFB₁ toxicity are poorly understood. Moreover, antidotes against AFB₁ are lacking. Genome-wide CRISPR/Cas9 knockout screening in porcine kidney cells identified the transcription factor BTB and CNC homolog 1 (BACH1) as a gene required for AFB₁ toxicity. The inhibition of BACH1 expression in porcine kidney cells and human hepatoma cells resulted in increased resistance to AFB₁. BACH1 depletion attenuates AFB₁-induced oxidative damage via the upregulation of antioxidant genes. Subsequently, virtual structural screening identified the small molecule 1-Piperazineethanol, α-[(1,3-benzodioxol-5-yloxy)methyl] -4-(2-methoxyphenyl) (M2) as an inhibitor of BACH1. M2 and its analogues inhibited AFB₁-induced porcine and human cell death in vitro, while M2 administration significantly improved AFB₁-induced symptoms of weight loss and liver injury in vivo. These findings demonstrate that BACH1 plays a central role in AFB₁-induced oxidative damage by regulating antioxidant gene expression. We also present a potent candidate small-molecule inhibitor in developing novel treatments for AFB₁ toxicity.

Corticosterone potentiates ochratoxin A-induced microglial activation

Microglial activation in the central nervous system (CNS) has been associated with brain damage and neurodegenerative disorders. Ochratoxin A (OTA) is a mycotoxin that occurs naturally in food and feed and has been associated with neurotoxicity, while corticosteroids are CNS’ physiological function modulators. This study examined how OTA affected microglia activation and how corticosteroids influenced microglial neuroinflammation. Murine microglial cells (BV-2) were stimulated by OTA, and the potentiation effects on OTA-induced inflammation were determined by corticosterone pre-treatment. Expressions of pro-inflammatory mediators including tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), interleukin-6 (IL-6), and inducible nitric oxide synthase (iNOS) were determined. Phosphorylation of mitogen-activated protein kinases (MAPKs) was analyzed by western blotting. OTA significantly increased the mRNA expression of IL-6, TNF-α, IL-1β, and iNOS and also elevated IL-6 and NO levels. Corticosterone pre-treatment enhanced the neuroinflammatory response to OTA in a mineralocorticoid receptor (MR)-dependent mechanism, which is associated with increases in extracellular signal-regulated kinase (ERK) and p38 MAPK activation. In response to OTA, microglial cells produced pro-inflammatory cytokines and NO, while corticosterone increased OTA-induced ERK and p38 MAPK phosphorylation via MR. Findings indicated the direct role of OTA in microglia activation and neuroinflammatory response and suggested that low corticosterone concentrations in the brain exacerbated neurodegeneration.

Quantitative Estimation of Aflatoxin Level in Poultry Feed in Selected Poultry Farms

Statement of Novelty. Poultry feed contamination due to mycotoxins is one of the major threats to the growing poultry industry. Surveillance of different mycotoxins, including aflatoxin, is very important to control economic and health hazards associated with these toxins. Studies reporting aflatoxin levels in poultry feed are limited. Therefore, this study was conducted to examine the occurrence of total aflatoxin in poultry feed. This study is the first-ever documentation about the frequency and quantitative estimations of total aflatoxin levels in poultry feed consumed to provide solid feedback to the poultry industrialists and researchers involved in studying the mycotoxins. Objective. Contamination of poultry feed with mycotoxins such as aflatoxin is a major concern for the poultry industry that results in a significant economic loss and directly affects consumers. Monitoring the aflatoxin levels in poultry feed is crucial for controlling economic loss and decreasing the health hazards to the population. This study was conducted to examine the occurrence of total aflatoxin in poultry feed in a high consumption area. Three different poultry feeds, i.e., starter, grower, and finisher, were assessed through continuous sampling from farms. The incidence of positive samples for aflatoxin contamination was 92.5%. Grower feed had the highest frequency (100%) of aflatoxin positive samples and aflatoxin levels with a mean value of 56.34 ppb. Further, the range of moisture content was around 6.8%-10.98%. No significant correlation between humidity and aflatoxin contamination was revealed when analyzed by Pearson's correlation coefficient with r² of 0.05 and p value of 0.13. The results warrant the need for constant monitoring programs for the prevention of aflatoxin contamination in local poultry farms

Combination of zinc and selenium alleviates ochratoxin A-induced fibrosis via blocking ROS-dependent autophagy in HK-2 cells

BACKGROUND

Ochratoxin A (OTA) is a mycotoxin produced by Aspergillus and Penicillium. The key target organ of OTA toxicity is the kidney, which has a significant impact on human health. Recently, nutrition regulation is suggested to be an effective protection against mycotoxins contamination. The current study investigated the combined protective effects of zinc and selenomethionine (SeMet) (a major component of organic selenium) on OTA-induced renal fibrosis and their potential mechanisms in human renal proximal tubule epithelial cells (HK-2 cells).

METHODS

Cytotoxicity of different concentrations of OTA, zinc and SeMet on HK-2 cells was detected by cell viability, lactate dehydrogenase (LDH) and apoptotic nuclei assays. The expression of fibrosis biomarkers was detected by Real-Time PCR, western blotting and indirect immunofluorescence assays. The production of reactive oxygen species (ROS) was detected by ROS assay kit. The protein expression of autophagy biomarkers was detected by western blotting assay.

RESULTS

Cytotoxicity was induced by OTA treatment in a dose-dependent manner, and it was attenuated by zinc or SeMet application in HK-2 cells. Zinc or SeMet application also down-regulated the expression of fibrosis biomarkers, and the combination of them displayed better effects. In addition, OTA increased intracellular ROS level and activated autophagy in a dose-dependent manner, and it was reversed by zinc and SeMet combined application. With the treatment of hydrogen peroxide (H₂O₂) or rapamycin (the specific activator of autophagy), the combined protective effects of zinc and SeMet were abolished.

CONCLUSIONS

Zinc and SeMet application alleviated OTA-induced cytotoxicity and fibrosis in HK-2 cells. Combination of them was more effective than its individual application. The present study manifest novel insight about the alleviation of OTA-induced nephrotoxicity by nutrition regulation, and had a guiding effect on the clinical supplementation of nutritional elements.

Mycotoxins—Prevention, Detection, Impact on Animal Health

Mycotoxins are defined as secondary metabolites of some species of mold fungi. They are present in many foods consumed by animals. Moreover, they most often contaminate products of plant and animal origin. Fungi of genera Fusarium, Aspergillus, and Penicillum are most often responsible for the production of mycotoxins. They release toxic compounds that, when properly accumulated, can affect many aspects of breeding, such as reproduction and immunity, as well as the overall liver detoxification performance of animals. Mycotoxins, which are chemical compounds, are extremely difficult to remove due to their natural resistance to mechanical, thermal, and chemical factors. Modern methods of analysis allow the detection of the presence of mycotoxins and determine the level of contamination with them, both in raw materials and in foods. Various food processes that can affect mycotoxins include cleaning, grinding, brewing, cooking, baking, frying, flaking, and extrusion. Most feeding processes have a variable effect on mycotoxins, with those that use high temperatures having the greatest influence. Unfortunately, all these processes significantly reduce mycotoxin amounts, but they do not completely eliminate them. This article presents the risks associated with the presence of mycotoxins in foods and the methods of their detection and prevention.

Selenomethionine alleviated Ochratoxin A induced pyroptosis and renal fibrotic factors expressions in MDCK cells

Ochratoxin A (OTA) is universally known to induce nephrotoxicity via inducing oxidative stress and apoptosis, inhibiting protein synthesis and activating autophagy. Our previous studies have proved that OTA induces nephrotoxicity in vitro and in vivo by adjusting the NOD-like receptor protein 3 (NLRP3) inflammasome activation and caspase-1-dependent pyroptosis. Based on these findings, we further investigated the protective role of selenomethionine (SeMet) on OTA-caused nephrotoxicity using the Madin-Darby canine kidney (MDCK) epithelial cells as an in vitro model, proposing to offer a new way for remedying OTA-induced nephrotoxicity by nutritional manipulation. We measured the cell vitality, lactate dehydrogenase (LDH) activity and the expression of renal fibrotic genes, NLRP3 inflammasome and pyroptosis related genes. MTT and LDH results indicated that SeMet supplementation significantly mitigated 2.0 μg/ml OTA-induced cytotoxicity in MDCK cells (p < 0.05). Meanwhile, SeMet alleviated OTA induced increase of reactive oxygen species in MDCK cells. Then, the expressions of α-SMA, Vimentin, and TGF-β were detected both in mRNA and protein levels. The results indicated 8 μM SeMet supplementation could significantly downregulate the expression of OTA-induced renal fibrosis-related genes (p < 0.05). In addition, the upregulation of OTA-induced NLRP3 inflammasome and pyroptosis downstream genes was also significantly inhibited by 8 μM of SeMet (p < 0.05). In summary, SeMet could alleviate OTA-induced renal fibrotic genes expression and reduce NLRP3-caspase-1-dependent pyroptosis. Therefore, SeMet supplementation may become an effective approach for preserving animals from renal injury exposed to OTA.

Anti-Apoptotic Effect of Flavokawain A on Ochratoxin-A-Induced Endothelial Cell Injury by Attenuation of Oxidative Stress via PI3K/AKT-Mediated Nrf2 Signaling Cascade

This study investigates the endothelial protective activity of flavokawain A (FKA) against oxidative stress induced by ochratoxin A (OTA), which acts as a mycotoxin, and its primary mechanisms in in vitro models. Reactive oxygen species, in general, regulate oxidative stress that significantly contributes to the pathophysiology of endothelial dysfunctions. OTA exerts toxicity through inflammation and the accumulation of ROS. This research is aimed at exploring the defensive function of FKA against the endothelial injury triggered by OTA through the Nrf2 pathway regulated by PI3K/AKT. OTA exposure significantly increased the nuclear translocation of NFκB, whereas we found a reduction in inflammation via NFκB inhibition with FKA treatment. FKA increased the PI3K and AKT phosphorylation, which may lead to the stimulation of antioxidative and antiapoptotic signaling in HUVECs. It also upregulated the phosphorylation of Nrf2 and a concomitant expression of antioxidant genes, such as HO-1, NQO-1, and γGCLC, depending on the dose under the oxidative stress triggered by OTA. Knockdown of Nrf2 through small interfering RNA (siRNA) impedes the protective role of FKA against the endothelial toxicity induced by OTA. In addition, FKA enhanced Bcl2 activation while suppressing apoptosis marker proteins. Therefore, FKA is regarded as a potential agent against endothelial oxidative stress caused by the deterioration of the endothelium. The research findings showed that FKA plays a key role in activating the p-PI3K/p-AKT and Nrf2 signaling pathways, while suppressing caspase-dependent apoptosis.

DL-Selenomethionine Alleviates Oxidative Stress Induced by Zearalenone via Nrf2/Keap1 Signaling Pathway in IPEC-J2 Cells

Zearalenone (ZEN) is a kind of nonsteroidal mycotoxin that is considered a risk affecting the safety of human food and livestock feed that causes oxidative damages in mammalian cells. Selenomethionine (SeMet) was indicated to have antioxidant activity and received great interest in investigating the role of SeMet as a therapeutic agent in oxidation. Therefore, the aim of this study was to investigate the hormetic role of DL-SeMet in porcine intestinal epithelial J2 (IPEC-J2) cells against ZEN-induced oxidative stress injury. As a result of this experiment, 30 μg/mL of ZEN was observed with significantly statistical effects in cell viability. Following the dose-dependent manner, 20 μg/mL was chosen for the subsequent experiments. Then, further results in the current study showed that the ZENinduced oxidative stress with subsequent suppression of the expression of antioxidant stress pathway-related genes species. Moreover, SeMet reversed the oxidative damage and cell death of ZEN toxins to some extent, by a Nrf2/Keap1-ARE pathway. The finding of this experiment provided a foundation for further research on the ZEN-caused cell oxidative damage and the cure technology.

Neuroimmune disruptions from naturally occurring levels of mycotoxins

Substantial pieces of evidence support the potential of exogenous toxins in disrupting neuroimmune homeostasis. It appears that mycotoxins are one of the noticeable sources of naturally occurring substances dysregulating the immune system, which involves the physiology of many organs, such as the central nervous system (CNS). The induction of inflammatory responses in microglial cells and astrocytes, the CNS resident cells with immunological characteristics, could interrupt the hemostasis upon even with low-level exposure to mycotoxins. The inevitable widespread occurrence of a low level of mycotoxins in foods and feed is likely increasing worldwide, predisposing individuals to potential neuroimmunological dysregulations. This paper reviews the current understanding of mycotoxins' neuro-immunotoxic features under low-dose exposure and the possible ways for detoxification and clearance as a perspective.

Selenium enriched Bacillus subtilis yb-1114246 activated the TLR2-NF-κB1 signaling pathway to regulate chicken intestinal β-defensin 1 expression

The aim of this study was to investigate the effects and potential signaling pathway of selenium-enriched Bacillus subtilis (SEBS) on beta defensin 1 (BD1) expression in chicken intestine. Chinese Huainan Partridge chickens (500 individuals) were randomly allocated into five groups, including control, inorganic Se, B. subtilis, SEBS, and a mixture of Se and B. subtilis (Se-BS). After 56 d of feeding, chicken ileal mucous membranes were harvested to detect differences in expression of BD1. The results indicated that BD1 was produced in intestinal crypt cells and secreted into the lumen through the villi brush border. BD1 was up-regulated in distal ileum segments colonized by SEBS and B. subtilis. Chicken primary intestinal crypt cells were cultured and grouped into control, inorganic Se, B. subtilis, SEBS, and Se-BS treatments to identify the receptor of B. subtilis. Results indicated that B. subtilis and SEBS were recognized by toll-like receptor 2 (TLR2), stimulating the NF-κB1 signaling pathway to increase expression of BD-1, which was further enhanced when combined with Se. Pro-inflammatory cytokines TNF-α, IL-1β, and IL-6 were up-regulated with B. subtilis supplementation, and inhibited under the action of Se. In conclusion, B. subtilis and SEBS were recognized by the TLR2 receptor in the ileal mucous membrane, which activated the TLR2-MyD88-NF-κB1 signaling pathway to upregulate BD1 expression. In addition, Se enhanced recognition of B. subtilis and reduced levels of pro-inflammatory factors caused by estrogenic B. subtilis supplementation.

Two-way immune effects of deoxynivalenol in weaned piglets and porcine alveolar macrophages: Due mainly to its exposure dosage

Mycotoxins are toxic metabolites produced by fungal species that occur frequently in cereals and animal forages throughout the world, posing a serious threat to humans and animals. Although some studies showed the immunotoxicity of mycotoxins, little research focused on the two-way effects of mycotoxins on immune response in vitro and vivo. Here, we explored the effects of deoxynivalenol (DON), one of the most widely distributed mycotoxins, on immune function of piglets and porcine alveolar macrophages (PAMs), and found it exhibited bidirectional immune effects due to different exposure doses. Our results revealed that low doses of DON increased the expressions of TNF-α and IL-6 in piglets and PAMs, promoted the chemotaxis and phagocytosis of PAMs and transformed macrophages to M1 phenotype (P < 0.05). Conversely, high doses of DON increased the expressions of TGF-β and IL-10 in piglets and PAMs, inhibited the chemotaxis and phagocytosis of PAMs and induced macrophages M2-type polarization (P < 0.05). Mechanistically, DON exposure significantly activated the TLR4/NFκB pathway at low doses and induced mitophagy-mediated mitochondrial dysfunction at high doses in vitro and vivo. TLR4 interference and mitophagy activator, CCCP, were used to further confirm their roles. Therefore, we concluded that DON exposure at low doses caused immunostimulation via activating TLR4/NFκB, whereas it was immunoinhibitory at high doses through blocking mitophagy. Our study suggested that both high and low doses mycotoxins contamination might be harmful, and further back up the necessity to take a vigilant attitude to minimize humans and animals intake of mycotoxins in the environment.

Effects of mycotoxin-contaminated feed on farm animals

Mycotoxins are secondary products produced by fungi in cereals and are frequently found in the livestock industry as contaminants of farm animal feed. Studies analyzing feed mycotoxins have been conducted worldwide and have confirmed the presence of mycotoxins with biological activity, including aflatoxin, ochratoxin A, fumonisin, zearalenone, and deoxynivalenol, in a large proportion of feed samples. Exposure to mycotoxins can cause immunotoxicity and impair reproductive function in farm animals. In addition, exposure of tissues, such as the kidneys, liver, and intestines, to mycotoxins can exert histopathological changes that can interfere with animal growth and survival. This review describes previous studies regarding the presence of major mycotoxins in the feed of farm animals, especially pigs and poultry. Moreover, it describes the adverse effects of mycotoxins in farm animals following exposure, as well as the biological activity of mycotoxins in animal-derived cells. Mycotoxins have been shown to regulate signaling pathways, oxidative stress, endoplasmic reticulum stress, apoptosis, and proliferation in porcine and bovine cells. A clear understanding of the effects of mycotoxins on farm animals will help reduce farm household economic loss and address the health concerns of people who consume these meat and dairy products.

Occurrence and Characterization of Fungi and Mycotoxins in Contaminated Medicinal Herbs

Traditional medicinal herbs are widely used and may be contaminated with mycotoxigenic fungi during cultivation, harvesting, and storage, causing spoilage and mycotoxin production. We evaluated the predominant mycoflora and extent of mycotoxin contaminations in 48 contaminated samples of 13 different medicinal herbs. In total, 70.8% of herbs were slightly contaminated with aflatoxins (<5 μg kg-1). Codonopsis radix samples contained ochratoxin A (OTA) (360-515 μg kg-1), and Scutellariae radix samples contained OTA (49-231 μg kg-1) and citrinin (15-53 μg kg-1). Forty samples (83.3%) contained fungal contamination. Sixty-nine strains were characterized via morphological and molecular identification. The predominant mycoflora comprised four genera, Aspergillus spp. (26.1%), Penicillium spp. (24.6%), Rhizopus spp. (14.5%), and Trichoderma spp. (11.6%). Aflatoxins, OTA, and citrinin were detected in 37 cultures by high-performance liquid chromatography-tandem mass spectrometry. Approximately 21.6% of Aspergillus and Penicillium isolates produced mycotoxins. One Penicillium polonicum strain isolated from Scutellariae radix synthesized citrinin. Multiplex PCR analysis showed that three Aspergillus flavus strains harbored aflatoxin biosynthesis genes. One Aspergillus flavus strain isolated from Amomi fructus produced AFB1 and AFB2. To the best of our knowledge, the citrinin production by Aspergillus chevalieri and Penicillium sacculum was first reported in this study, which poses a potential risk of mycotoxin contamination in medicinal herbs.

Long-Time Instead of Short-Time Exposure in Vitro and Administration in Vivo of Ochratoxin A Is Consistent in Immunosuppression

Ochratoxin A (OTA) is a mycotoxin produced by Aspergillus and Penicillium, contaminating in a wide variety of foods and feeds. Mycotoxins, including OTA, could cause immunosuppression in almost all previous studies in vivo. However, the vast majority of results in vitro showed that mycotoxins caused immunostimulation. Why the results of studies in vitro are contrary to studies in vivo is unknown. Our study aims to explore the underlying reason and mechanism of the paradoxical effect. In this study, porcine alveolar macrophage cell line 3D4/21 was chosen as an in vitro model and treated with 1.0 μg/mL OTA for different times. Some indexes, such as expression of inflammatory cytokines, migration, phagocytosis, macrophage polarization, autophagy-related proteins, and Akt1 phosphorylation, were detected. The results showed that pro-inflammatory cytokine expression, migration, and phagocytosis were increased, with macrophage polarization to the M1 phenotype at 24 h of OTA exposure. Surprisedly, anti-inflammatory cytokine expression was increased, cell phagocytosis and migration were decreased, and macrophage polarization was switched from M1 to M2 at 72 h of OTA exposure. Furthermore, we found that long-time exposure of OTA also suppressed autophagy, and the autophagy activator blocked the OTA-induced immunosuppression. Phosphorylation of Akt1 plays a positive role in autophagy inhibition. In conclusion, long-time instead of short-time exposure of OTA in vitro induced immunosuppression. The immunosuppression mechanism of OTA in vitro involved inhibition of autophagy through upregulating p-Akt1. Our results provide new insight into research on the mechanism of mycotoxin-induced immunosuppression in vitro.

Research Progress on the Toxic Antagonism of Selenium Against Mycotoxins

Animal feed is prone to becoming infected with molds during production and storage, resulting in secondary metabolite mycotoxins, such as aflatoxin B₁ (AFB₁), T-2 toxins, deoxynivalenol (DON), and ochratoxin A (OTA), which are harmful to humans and animals. Selenium is an essential trace element for humans and animals, and it is also an effective antioxidant. Many studies have shown that selenium can reduce the damage caused by mycotoxins in animals. This article reviews the current literature on the antagonistic effects of selenium on AFB₁, T-2, DON, and OTA toxicity.

Selenium Deficiency Aggravates Aflatoxin B1-Induced Immunotoxicity in Chick Spleen by Regulating 6 Selenoprotein Genes and Redox/Inflammation/Apoptotic Signaling

BACKGROUND

Selenium (Se) plays a protective role in aflatoxin B1 (AFB1)-induced splenic immunotoxicity in chicks.

OBJECTIVE

This study was designed to reveal the underlying mechanism of Se-mediated protection against AFB1-induced splenic injury in broilers.

METHODS

Four groups of 1-d-old Cobb male broilers (n = 5 cages/diet, 6 chicks/cage) were arranged in a 3-wk 2 × 2 factorial design trial whereby they were fed an Se-deficient, corn- and soy-based diet [base diet (BD), 36 μg Se/kg], BD plus 1.0 mg AFB1/kg, BD plus 0.3 mg Se/kg, or BD plus 1.0 mg AFB1/kg and 0.3 mg Se/kg (as 2-hydroxy-4-methylselenobutanoic acid). Serum and spleen were collected at week 3 to assay for cytokines, histology, redox status, selected inflammation- and apoptosis-related genes and proteins, and the selenogenome.

RESULTS

Dietary AFB1 induced growth retardation and spleen injury, decreasing (P < 0.05) body weight gain, feed intake, feed conversion efficiency, and serum interleukin-1β by 17.8-98.1% and increasing (P < 0.05) the spleen index and serum interleukin-6 by 37.6-113%. It also reduced the splenic lymphocyte number, the white pulp region, and histiocyte proliferation in Se-adequate groups. However, Se deficiency aggravated (P < 0.05) these AFB1-induced alterations by 16.2-103%. Moreover, Se deficiency decreased (P < 0.05) splenic glutathione peroxidase (GPX) activity and glutathione-S transferase and glutathione concentrations by 35.6-89.4% in AFB1-exposed groups. Furthermore, Se deficiency upregulated (P < 0.05) the apoptotic (Caspase 3 and Caspase 9) and antimicrobial (β defensin 1 and 2) genes, but downregulated (P < 0.05) antiapoptotic (B-cell lymphoma 2) and inflammatory (E3 ubiquitin-protein ligase CBL-B) genes at the mRNA and/or protein level in AFB1 supplementation groups. Additionally, Se deficiency downregulated (P < 0.05) GPX3, thioredoxin reductase 1 (TXNRD 1), GPX4, and selenoprotein (SELENO) S, and upregulated (P < 0.05) SELENOT and SELENOU in spleen in AFB1 administered groups.

CONCLUSIONS

Dietary Se deficiency exacerbated AFB1-induced spleen injury in chicks, partially through the regulation of oxidative stress, inflammatory and apoptotic signaling, and 6 selenoproteins.

Aflatoxin B1 Induces Immunotoxicity through the DNA Methyltransferase-Mediated JAK2/STAT3 Pathway in 3D4/21 Cells

As the most toxic mycotoxin of all of the fungal toxins, aflatoxin B₁ (AFB₁) has carcinogenesis, heptotoxicity, and immunotoxicity. DNA methylation plays a critical role in gene expression regulation of the pathological process. However, the relationship between DNA methylation and AFB₁-induced immunotoxicity was not yet reported. Therefore, the objectives of this study were to verify AFB₁-induced immunotoxicity and investigate the potential role of the DNA methyltransferase (DNMT) family in AFB₁-induced immunotoxicity and the pathway mechanism in 3D4/21 cells. The results showed that AFB₁ could induce cytotoxicity, apoptosis, pro-inflammatory cytokine expression, DNA damage, and oxidative stress and decrease phagocytotic capacity. Meanwhile, the levels of DNMT1 and DNMT3a were significantly increased in 0.04 and 0.08 μg/mL AFB₁ compared to the control. Inhibition of DNMT1 and DNMT3a by 5-Aza-2dc could reverse changes of the above parameters. Further, the JAK2/STAT3 pathway was significantly activated in 0.04 μg/mL AFB₁. Inhibition of p-JAK2 and p-STAT3 by AG490 could alleviate AFB₁-induced immunotoxicity. Moreover, inhibition of DNMT1 and DNMT3a by 5-Aza-2dc could suppress the phosphorylation of JAK2 and STAT3. Taken together, AFB₁-induced immunotoxicity is related to the JAK2/STAT3 pathway mediated by DNMTs in 3D4/21 cells.