Cytochrome P450 enzymes mediated by DNA methylation is involved in deoxynivalenol-induced hepatoxicity in piglets

Contamination of aflatoxin B1, deoxynivalenol and zearalenone in feeds in China from 2021 to 2024

BACKGROUND

This study was carried out to investigate the individual and combined contamination of aflatoxin B1 (AFB1), deoxynivalenol (DON), and zearalenone (ZEN) in feeds in China between 2021 and 2024. A total of 23,003 feed samples, including 17,489 feedstuff samples and 5,514 complete feed samples, were collected from different provinces of China for mycotoxin analysis.

RESULTS

The analyzed mycotoxins displayed considerably high contamination in the feed samples, with the individual contamination of AFB1, DON, and ZEN were 20.0%-100%, 33.3%-100%, and 85.0%-100%, respectively. The average concentrations of AFB1, DON, and ZEN were 1.2-728.7 μg/kg, 106-8,634.8 μg/kg, and 18.1-3,341.6 μg/kg, respectively. Notably, the rates over China's safety standards for AFB1, DON, and ZEN in raw ingredients were 9.7%, 2.7%, and 15.7%, respectively. Meanwhile, 3.5%, 1.1%, and 8.7% of analyzed complete feeds exceeded China's safety standards for AFB1, DON, and ZEN, respectively. Moreover, the co-contamination rates of AFB1, DON, and ZEN in more than 70% of raw ingredients and 87.5% of complete feed products were 60.0%-100% and 61.5%-100%, respectively.

CONCLUSION

This study reveals that the feeds in China have commonly been contaminated with AFB1, DON, and ZEN alone and their combination during the past four years. These findings highlight the significance of monitoring mycotoxin contaminant levels in domestic animal feed and the importance of carrying out feed administration and remediation strategies for mycotoxin control.

NNMT is involved in deoxynivalenol-induced hepatocyte toxicity via promoting ferroptosis

Deoxynivalenol (DON) is a common contamination mycotoxin that which exerts significant hepatotoxicity, posing a serious threat to human and animal health. Ferroptosis has been linked to the development of hepatotoxicity induced by DON. However, the mechanism by which DON promotes ferroptosis in hepatocytes is not well understood. Although studies have shown that DON upregulates the expression of nicotinamide N-Methyltransferase (NNMT), its role in DON hepatotoxicity has not been elucidated. In this study, we found that DON inhibited SLC7A11/GPX4 and increased cytosolic free Fe2 + and lipid ROS, thereby inducing ferroptosis of HepG2 cells. Overexpression of NNMT markedly downregulated the expression of SLC7A11, GPX4, GCLC, and NQO1, exacerbated the DON-induced increase in free Fe2+ and lipid ROS, thus promoting ferroptosis. Silencing or inhibition of NNMT produced opposite effects and abolished the DON-induced ferroptosis. Further application of SLC7A11 and GPX4 inhibitor treatments confirmed that following DON exposure, NNMT triggered ferroptosis by inhibiting SLC7A11 and GPX4, to reduce cell viability and inhibit cell growth. Taken together, this study found that DON-induced NNMT may enhance ferroptosis by inhibiting the SLC7A11/GPX4 proteins in HepG2 cells. These findings provide valuable insights for controlling DON hepatotoxicity and hepatocellular carcinoma.

Disorders of Iron Metabolism: A "Sharp Edge" of Deoxynivalenol-Induced Hepatotoxicity

BACKGROUND/OBJECTIVES

Deoxynivalenol (DON), known as vomitoxin, is one of the most common mycotoxins produced by Fusarium graminearum, with high detection rates in feed worldwide. Ferroptosis is a novel mode of cell death characterized by lipid peroxidation and the accumulation of reactive oxygen species. Although it has been demonstrated that DON can induce ferroptosis in the liver, the specific mechanisms and pathways are still unknown. The aim of this experiment was to investigate that DON can induce iron metabolism disorders in the livers of mice, thereby triggering ferroptosis and causing toxic damage to the liver.

METHODS

Male C57 mice were treated with DON at a 5 mg/kg BW concentration as an in vivo model. After sampling, organ coefficient monitoring, liver function test, histopathological analysis, liver Fe2+ content test, and oxidative stress-related indexes were performed. The mRNA and protein expression of Nrf2 and its downstream genes were also detected using a series of methods including quantitative real-time PCR, immunofluorescence double-labeling, and Western blotting analysis.

RESULTS

DON can cause damage to the liver of a mouse. Specifically, we found that mouse livers in the DON group exhibited pathological damage in cell necrosis, inflammatory infiltration, cytoplasmic vacuolization, elevated relative liver weight, and significant changes in liver function indexes. Meanwhile, the substantial reduction in the levels of glutathione (GSH), catalase (CAT), superoxide dismutase (SOD), and total antioxidant capacity (T-AOC) in the DON group indicated that DON also caused oxidative stress in the liver. Notably, DON exposure increased the levels of Fe2+ and Malondialdehyde (MDA) in the liver, which provides strong evidence for the occurrence of iron metabolism and ferroptosis disorders. Most importantly, mRNA and protein expression of Nrf2, an important pathway for iron metabolism and ferroptosis, along with its downstream genes, heme oxygenase (HO-1), quinone oxidoreductase (NQO1), glutathione peroxidase (GPX4), and solute carrier gene (SLC7a11), were significantly inhibited in the DON group.

CONCLUSIONS

Based on our results, the Nrf2 pathway is closely associated with DON-induced iron metabolism disorders and ferroptosis in mouse livers, suggesting that maintaining hepatic iron homeostasis and activating the Nrf2 pathway may be a potential target for mitigating DON hepatotoxicity in the future.

18beta-glycyrrhetinic acid alleviates deoxynivalenol-induced hepatotoxicity by inhibiting GPX4-dependent ferroptosis

Deoxynivalenol (DON), a mycotoxin that severely contaminates agri-food products can cause hepatotoxicity. Ferroptosis is an iron-dependent form of cell death, and the liver is an important organ for iron accumulation. 18beta-glycyrrhetinic acid (GA) has anti-ferroptosis and hepatoprotective effects. This study aimed to investigate the role of ferroptosis in the protective effects of GA against DON-induced hepatotoxicity in HepG2 cells and mice. The in vitro results revealed that DON (0.4 μM) decreased GPX4, SLC7A11, GCLC, NQO1, and Nrf2 expression; promoted TFR-1 expression and MDA, 4-HNE, and total ROS production; accelerated GSH depletion; and enhanced lipid ROS accumulation and Fe(II) overload, leading to ferroptosis. Pre-treatment with GA (0.4 and 6 μM) reversed these changes and alleviated DON-induced ferroptosis, thereby increasing cell viability and proliferation. In vivo results also showed that GA (10 mg/kg bw) pre-administration attenuated DON (2 mg/kg bw)-induced mouse liver injury, in part by inhibiting ferroptosis through reducing mitochondrial damage and lipid peroxidation. In addition, GA prevented erastin- and RSL3-induced ferroptosis by promoting GPX4 and SLC7A11 expression. Altogether, GA attenuated DON-induced hepatotoxicity by preventing ferroptosis via activation of GPX4-dependent pathway. The findings of this study provide a theoretical basis for the prevention of food mycotoxin toxicity.

Necroptosis contributes to deoxynivalenol-induced liver injury and inflammation in weaned piglets

BACKGROUND

The aim of this study was to investigate the role of necroptosis in deoxynivalenol (DON)-induced liver injury and inflammation in weaned piglets.

METHODS

In Exp. 1, 12 weaned piglets were divided into 2 groups including pigs fed basal diet and pigs fed diet contaminated with 4 mg/kg DON for 21 d. In Exp. 2, 12 weaned piglets were divided into 2 groups including control piglets and piglets given a gavage of 2 mg/kg body weight (BW) DON. In Exp. 3, 24 weaned piglets were used in a 2 × 2 factorial design and the main factors including necrostatin-1 (Nec-1) (DMSO or 0.5 mg/kg BW Nec-1) and DON challenge (saline or 2 mg/kg BW DON gavage). On 21 d in Exp. 1, or at 6 h post DON gavage in Exp. 2 and 3, pigs were killed for blood samples and liver tissues. Liver histology, blood biochemical indicators, and liver inflammation and necroptosis signals were tested.

RESULTS

Dietary or oral gavage with DON caused liver morphological damage in piglets. Dietary DON led to hepatocyte damage indicated by increased aspartate transaminase (AST) activity and AST/alanine aminotransferase (ALT) ratio, and DON gavage also caused hepatocyte damage and cholestasis indicated by increased AST and alkaline phosphatase (AKP) activities. Dietary DON caused liver necroptosis indicated by increased protein abundance of total receptor interacting protein kinase 3 (t-RIP3) and total mixed lineage kinase domain-like protein (t-MLKL). Moreover, DON gavage increased mRNA expression of interleukin (IL)-6 and IL-1β in liver. DON gavage also induced liver necroptosis demonstrated by increased protein abundance of t-RIP3, phosphorylated-RIP3 (p-RIP3), t-MLKL and p-MLKL. However, pretreatment with Nec-1, a specific inhibitor of necroptosis, inhibited liver necroptosis indicated by decreased protein expression of t-RIP3, p-RIP3, t-MLKL and p-MLKL. Nec-1 pretreatment reduced liver morphological damage after DON gavage. Pretreatment with Nec-1 also attenuated liver damage induced by DON indicated by decreased activities of AST and AKP. Furthermore, Nec-1 pretreatment inhibited liver mRNA expression of IL-6 and IL-1β after DON challenge.

CONCLUSIONS

Our data demonstrate for the first time that necroptosis contributes to DON-induced liver injury and inflammation in piglets.

DNA ligase III mediates deoxynivalenol exposure-induced DNA damage in intestinal epithelial cells by regulating oxidative stress and interaction with PCNA

Deoxynivalenol (DON) is a widely distributed mycotoxin that is severely cytotoxic and genotoxic to animals and humans. The gut is the initial site of DON exposure and absorption, which can cause severe intestinal damage. However, the underlying mechanisms and effective therapeutic approaches remain unknown. Here, the study indicated that DON exposure caused significant DNA damage in intestinal porcine epithelial cells (IPEC-J2), enhanced significantly the expression of γ-H2AX and 8-hydroxy-2'-deoxyguanosine, and altered the mRNA expression of key genes in the DNA repair pathway. Among them, ligases3 (LIG3) is the key DNA damage/repair gene and the only ligase responsible for the replication and maintenance of mitochondrial DNA. The expression of LIG3 was significantly decreased after DON exposure and showed a dose-dependent effect, decreased expression of LIG3 exacerbates DON-induced cytotoxicity and genotoxicity, decreased cell viability, induced apoptosis and cell cycle arrest, activation of inflammatory factors and MAPK pathway. Furthermore, LIG3 directly binds and regulates PCNA and play a positive regulatory role in the cellular cytotoxicity and genotoxicity upon DON exposure. Collectively, the findings elucidate the regulatory function of LIG3 in DON-induced DNA damage, providing valuable insights into identifying molecular targets for the comprehensive prevention and control of DON contamination.

CYP2E1 mediated deoxynivalenol-induced hepatocyte toxicity by regulating ferroptosis

Deoxynivalenol (DON), one of the most common mycotoxins in food and feed, can cause acute and chronic liver injury, posing a serious health risk to humans and animals. One of the important manifestations of DON-induced hepatotoxicity is ferroptosis. It has been reported that CYP2E1 can mediated ferroptosis, but the role of DON-induced CYP2E1 in DON-induced ferroptosis in hepatocytes is unknown. In the present study, we observed that DON significantly increased the expression of CYP2E1 and decreased the expression of the ferroptosis inhibitory proteins GPX4 and SLC7A11, as well as GCLC and NQO1. This resulted in an increase in the levels of cell lipid ROS and FeII, 4-HNE, which ultimately led to cell ferroptosis. Notably, knockdown of CYP2E1 resulted in an increase in DON-induced low levels of GPX4 and SLC7A11, a decrease in DON-induced high levels of lipid ROS, FeII and cell secreted 4-HNE, thus ameliorating cell ferroptosis. Moreover, the ferroptosis inhibitor ferrostatin-1 was observed to antagonise the cell growth inhibitory toxicity induced by DON exposure. This was achieved by blocking the increase in lipid ROS and FeII overload, which in turn reduced the extent of ferroptosis and increased IGF-1 protein expression. In conclusion, the present study demonstrated that CYP2E1 played a regulatory role in DON-induced ferroptosis in hepatocytes. Targeting ferroptosis may prove an effective strategy for alleviating DON-induced cell growth retardation toxicity. These findings provided a potential target and strategies to mitigate DON hepatotoxicity in the future.

Detoxification of DON-induced hepatotoxicity in mice by cold atmospheric plasma

Deoxynivalenol (DON) is one of the most common mycotoxins distributed in food and feed, which causes severe liver injury in humans and animals. Cold atmospheric plasma (CAP) has received much attention in mycotoxin degradation due to the advantages of easy operation, high efficiency, and low temperature. So far, the majority of studies have focused on the degradation efficiency and mechanism of CAP on DON, while there is still little information available on the hepatotoxicity of DON after CAP treatment. Herein, this study aimed to investigate the effect of CAP on DON-induced hepatotoxicity both in vitro and in vivo and its underlying mechanisms. The results showed that 120-s CAP treatment achieved 97 % degradation of DON. The vitro hepatotoxicity of DON in L02 cells was significantly reduced with CAP treatment time. Meanwhile, CAP markedly alleviated DON-induced liver injury in mice including the balloon-like degeneration of liver tissues and elevation of AST and ALP level. The underlying mechanism for CAP detoxification of DON-induced hepatotoxicity was further elucidated. The results showed that DON caused severe oxidative stress in cells by suppressing the antioxidant signaling pathway of Nrf2/HO-1/NQO-1, consequently leading to mitochondrial dysfunction and cell apoptosis, accompanied by cellular senescence and inflammation. CAP blocked DON inhibition on the Nrf2/HO-1/NQO-1 signaling pathway through the efficient degradation of DON, accordingly alleviating the oxidative stress and liver injury induced by DON. Therefore, CAP is an effective method to eliminate DON hepatotoxicity, which can be applied in the detoxification of mycotoxin-contaminated food and feed to ensure human and animal health.

Folic acid protects against isoniazid-induced liver injury via the m6A RNA methylation of cytochrome P450 2E1 in mice

Background

Cytochrome P450 2E1 (CYP2E1) converts isoniazid (INH) to toxic metabolites and is critical in INH-induced liver injury. The aim is to investigate the effect of folic acid (FA) on CYP2E1 and INH-induced liver injury.

Methods

Male Balb/c mice were used. The mice in the control group only received an AIN-93M diet. The AIN-93M diet was supplemented with 0.66 g INH/kg diet for the mice in the INH and FA groups. The mice in the FA group were treated with additional 0.01 g FA/kg diet. The one-carbon cycle metabolites, the expressions of CYP2E1 and the DNA and RNA methylation levels were detected to reveal the potential mechanism.

Results

FA treatment significantly reduced the alanine aminotransferase level and alleviated the liver necrosis. The mRNA and protein expressions of CYP2E1 were significantly lower in the FA group than those in the INH group. The N6-methyladenosine RNA methylation level of Cyp2e1 significantly increased in the FA group compared with the INH group, while the DNA methylation levels of Cyp2e1 were similar between groups. Additionally, the liver S-adenosyl methionine (SAM)/S-adenosyl homocysteine (SAH) was elevated in the FA group and tended to be positively correlated with the RNA methylation level of Cyp2e1.

Conclusion

FA alleviated INH-induced liver injury which was potentially attributed to its inhibitory effect on CYP2E1 expressions through enhancing liver SAM/SAH and RNA methylation.

Remediation Strategies for Mycotoxins in Animal Feed

Mycotoxins occur widely in various animal feedstuffs, with more than 500 mycotoxins identified so far [...].

Resveratrol protects against deoxynivalenol-induced ferroptosis in HepG2 cells

Deoxynivalenol (DON) is one of the most serious mycotoxins that contaminate food and feed, causing hepatocyte death. However, there is still a lack of understanding regarding the new cell death modalities that explain DON-induced hepatocyte toxicity. Ferroptosis is an iron-dependent type of cell death. The aim of this study was to explore the role of ferroptosis in DON-exposed HepG2 cytotoxicity and the antagonistic effect of resveratrol (Res) on its toxicity, and the underlying molecular mechanisms. HepG2 cells were treated with Res (8μM) or/and DON (0.4μM) for 12hours. We examined cell viability, cell proliferation, expression of ferroptosis-related genes, levels of lipid peroxidation and Fe(II). The results revealed that DON reduced the expression levels of GPX4, SLC7A11, GCLC, NQO1, and Nrf2 while promoting the expression of TFR1, GSH depletion, accumulation of MDA and total ROS. DON enhanced production of 4-HNE, lipid ROS and Fe(II) overload, resulting in ferroptosis. However, pretreatment with Res reversed these changes, attenuating DON-induced ferroptosis, improving cell viability and cell proliferation. Importantly, Res prevented Erastin and RSL3-induced ferroptosis, suggesting that Res exerted an anti-ferroptosis effect by activating SLC7A11-GSH-GPX4 signaling pathways. In summary, Res ameliorated DON-induced ferroptosis in HepG2 cells. This study provides a new perspective on the mechanism of DON-induced hepatotoxicity formation, and Res may be an effective drug to alleviate DON-induced hepatotoxicity.

Role of epigenetics in mycotoxin toxicity: a review

Mycotoxins can induce cell cycle disorders, cell proliferation, oxidative stress, and apoptosis through pathways such as those associated with MAPK, JAK2/STAT3, and Bcl-w/caspase-3, and cause reproductive toxicity, immunotoxicity, and genotoxicity. Previous studies have explored the toxicity mechanism of mycotoxins from the levels of DNA, RNA, and proteins, and proved that mycotoxins have epigenetic toxicity. To explore the toxic effects and mechanisms of these changes in mycotoxins, this paper summarizes the changes in DNA methylation, non-coding RNA, RNA and histone modification induced by several common mycotoxins (zearalenone, aflatoxin B1, ochratoxin A, deoxynivalenol, T-2 toxin, etc.) based on epigenetic studies. In addition, the roles of mycotoxin-induced epigenetic toxicity in germ cell maturation, embryonic development, and carcinogenesis are highlighted. In summary, this review provides theoretical support for a better understanding of the regulatory mechanism of mycotoxin epigenotoxicity and the diagnosis and treatment of diseases.

Nrf2-/- regulated lung DNA demethylation and CYP2E1 DNA methylation under PM2.5 exposure

Cytochrome P450 (CYP450) can mediate fine particulate matter (PM_2.5) exposure leading to lung injury. Nuclear factor E2-related factor 2 (Nrf2) can regulate CYP450 expression; however, the mechanism by which Nrf2^-/- (KO) regulates CYP450 expression via methylation of its promoter after PM_2.5 exposure remains unclear. Here, Nrf2^-/- (KO) mice and wild-type (WT) were placed in a PM_2.5 exposure chamber (PM) or a filtered air chamber (FA) for 12 weeks using the real-ambient exposure system. The CYP2E1 expression trends were opposite between the WT and KO mice following PM_2.5 exposure. After exposure to PM_2.5, CYP2E1 mRNA and protein levels were increased in WT mice but decreased in KO mice, and CYP1A1 expression was increased after exposure to PM_2.5 in both WT and KO mice. CYP2S1 expression decreased after exposure to PM_2.5 in both the WT and KO groups. We studied the effect of PM_2.5 exposure on CYP450 promoter methylation and global methylation levels in WT and KO mice. In WT and KO mice in the PM_2.5 exposure chamber, among the methylation sites examined in the CYP2E1 promoter, the CpG2 methylation level showed an opposite trend with CYP2E1 mRNA expression. The same relationship was evident between CpG3 unit methylation in the CYP1A1 promoter and CYP1A1 mRNA expression, and between CpG1 unit methylation in the CYP2S1 promoter and CYP2S1 mRNA expression. This data suggests that methylation of these CpG units regulates the expression of the corresponding gene. After exposure to PM_2.5, the expression of the DNA methylation markers ten-eleven translocation 3 (TET3) and 5-hydroxymethylcytosine (5hmC) was decreased in the WT group but significantly increased in the KO group. In summary, the changes in CYP2E1, CYP1A1, and CYP2S1 expression in the PM_2.5 exposure chamber of WT and Nrf2^-/- mice might be related to the specific methylation patterns in their promoter CpG units. After exposure to PM_2.5, Nrf2 might regulate CYP2E1 expression by affecting CpG2 unit methylation and induce DNA demethylation via TET3 expression. Our study revealed the underlying mechanism for Nrf2 to regulate epigenetics after lung exposure to PM_2.5.

Analysis of RIOK2 Functions in Mediating the Toxic Effects of Deoxynivalenol in Porcine Intestinal Epithelial Cells

Deoxynivalenol (DON) is a type of mycotoxin that threatens human and livestock health. Right open reading frame kinase 2 (RIOK2) is a kinase that has a pivotal function in ribosome maturation and cell cycle progression. This study aims to clarify the role of the RIOK2 gene in DON-induced cytotoxicity regulation in porcine intestinal epithelial cells (IPEC-J2). Cell viability assay and flow cytometry showed that the knockdown of RIOK2 inhibited proliferation and induced apoptosis, cell cycle arrest, and oxidative stress in DON-induced IPEC-J2. Then, transcriptome profiling identified candidate genes and pathways that closely interacted with both DON cytotoxicity regulation and RIOK2 expression. Furthermore, RIOK2 interference promoted the activation of the MAPK signaling pathway by increasing the phosphorylation of ERK and JNK. Additionally, we performed the dual-luciferase reporter and ChIP assays to elucidate that the expression of RIOK2 was influenced by the binding of transcription factor Sp1 with the promoter region. Briefly, the reduced expression of the RIOK2 gene exacerbates the cytotoxic effects induced by DON in IPEC-J2. Our findings provide insights into the control strategies for DON contamination by identifying functional genes and effective molecular markers.