Zearalenone induces ROS-mediated mitochondrial damage in porcine IPEC-J2 cells

Estrogen receptor β plays a protective role in zearalenone-induced oxidative stress in normal prostate epithelial cells

Zearalenone (ZEA) - a fungal mycotoxin is reported to both cause the oxidative stress associated with death of cells as well as induction of the proliferation of cells, depending on its concentration and the type of cells. ZEA due to its structural similarity to naturally occurring estrogens is able to bind to estrogen receptors and triggers estrogen-associated signaling pathways. The aim of this study is to evaluate whether the induction of oxidative stress in normal epithelial prostate PNT1A cells is associated with estrogenic activity of ZEA. We observed that ZEA-induced oxidative stress in PNT1A cells is associated with a decrease in the oxidative stress defense enzymes expression, cell cycle arrest in G2/M cell cycle phase as well as the decreased migration of cells. The results also suggest that the observed effect might be associated with the nuclear factor kappa-light-chain-enhancer of activated B cells (NFκB)- hypoxia inducible factor 1 alpha (HIF-1α) signaling pathway. The usage of estrogen receptor β (ERβ) selective antagonist 4-[2-phenyl-5,7-bis(trifluoromethyl)pyrazolo[1,5-a]pyrimidin-3-yl]-phenol PHTPP showed that ERβ activity is able to decrease the ZEA-induced oxidative stress, but is not enough to counteract it, indicating that ZEA-induced oxidative stress is only partially associated with estrogenic activity of ZEA.

Zearalenone Induces Estrogen-Receptor-Independent Neutrophil Extracellular Trap Release in Vitro

Zearalenone (ZEA) is a non-steroidal estrogenic mycotoxin synthesized in Fusarium species, mainly Fusarium graminearum and Fusarium culmorum, and it has strong estrogenic activity and causes genotoxic effects, reproductive disorders, and immunosuppressive effects. Neutrophil extracellular trap (NET) has been studied for many years. Initially, NET was considered a form of the innate response that combats invading microorganisms. However, NET is involved in a series of pathophysiological mechanisms, including thrombosis, tissue necrosis, autoinflammation, and even autoimmunity. We recently found that polymorphonuclear neutrophils response to ZEA exposure by undergoing NET formation. However, the molecular mechanisms involved in this process remain poorly characterized. Here, we analyze whether estrogen receptors (ERs) can affect NET formation after ZEA stimulation. The involvement of ERs is investigated with the selective ER antagonists. Moreover, we investigate the mechanisms of NET formation using immunofluorescence staining, fluorescence microplate, and western blot analysis. Our results show that ERs (ERα and ERβ) are not involved in ZEA-induced NET formation, but reactive oxygen species (ROS), extracellular signal-regulated kinase (ERK), and p38 are postulated to be involved. Specifically, we provide data demonstrating that ZEA-induced ROS may promote activation of ERK and p38 as well as subsequent NET release. We are the first to demonstrate this new mechanism of ZEA-induced NET formation, which may help in understanding the role of ZEA in overexposure diseases and provide a relevant basis for therapeutic applications.

Protective Effects of Melatonin Against Zearalenone Toxicity on Porcine Embryos in vitro

Zearalenone (ZEA) is an estrogenic mycotoxin produced by Fusarium fungi commonly found in corn, wheat, and other cereals which can infect food and feed commodities, and ZEA mainly has reproductive toxicity which causes widely reproductive disorders in pigs and other animals. However, the toxicity and the functional ways of ZEA on early embryo development is still unclear. In present study we showed that exposure to ZEA (10 μM) significantly decreased the 2-cell and blastocyst developmental rate in porcine early embryos in vitro. ZEA treatment resulted in the occurrence of oxidative stress, showing with increased reactive oxygen species (ROS) level, following with aberrant mitochondrial distribution. Moreover, we found positive signals of γH2A.X in the ZEA-treated embryos, indicating that ZEA induced DNA damage, and the increased autophagy confirmed this. These results suggested that ZEA induced oxidative stress, which further caused mitochondria dysfunction and DNA damage on early embryonic development. We next investigated the effects of melatonin on the ZEA-treated embryo development, and we found that melatonin supplementation could significantly ameliorate ZEA-induced oxidative stress, aberrant mitochondria distribution and DNA damage. In all, our results showed that ZEA was toxic for porcine embryos cultured in vitro and melatonin supplementation could protect their development from the effects of ZEA.

Protective Effect of N-Acetylcysteine against Oxidative Stress Induced by Zearalenone via Mitochondrial Apoptosis Pathway in SIEC02 Cells

Zearalenone (ZEN), a nonsteroidal estrogen mycotoxin, is widely found in feed and foodstuffs. Intestinal cells may become the primary target of toxin attack after ingesting food containing ZEN. Porcine small intestinal epithelial (SIEC02) cells were selected to assess the effect of ZEN exposure on the intestine. Cells were exposed to ZEN (20 µg/mL) or pretreated with (81, 162, and 324 µg/mL) N-acetylcysteine (NAC) prior to ZEN treatment. Results indicated that the activities of glutathione peroxidase (Gpx) and glutathione reductase (GR) were reduced by ZEN, which induced reactive oxygen species (ROS) and malondialdehyde (MDA) production. Moreover, these activities increased apoptosis and mitochondrial membrane potential (ΔΨm), and regulated the messenger RNA (mRNA) expression of Bax, Bcl-2, caspase-3, caspase-9, and cytochrome c (cyto c). Additionally, NAC pretreatment reduced the oxidative damage and inhibited the apoptosis induced by ZEN. It can be concluded that ZEN-induced oxidative stress and damage may further induce mitochondrial apoptosis, and pretreatment of NAC can degrade this damage to some extent.

Zearalenone can relieve dextran sulfate sodium-induced inflammatory reaction

In this study, we investigated the influence of zearalenone (ZEA) on the dextran sulfate sodium (DSS)-induced colitis model both in vitro and in vivo. Our results show that the mRNA levels of IL-1β, IL-18, NLRP3, ASC, and caspase-1 in the DSS+ZEA-treated group are lower than those in either the DSS or ZEA group, and the protein expression trends are similar. Furthermore, colitis, which is characterized by body weight loss, stool consistency, and the presence of bloody feces, was significantly alleviated in the DSS+ZEA group when compared with that in the DSS group. In addition, histological analysis showed that inflammatory cell infiltration and tissue damage of the colon in the DSS+ZEA group were recovered compared with that in the DSS-treated group. These results suggest that, instead of aggravating DSS-induced colitis, ZEA relieves the inflammatory reaction in colon tissue, which may be related to its estrogenic activity.

Effects of Quercetin on Proliferation and H₂O₂-Induced Apoptosis of Intestinal Porcine Enterocyte Cells

Weanling stress and toxicosis, which are harmful to the health of pigs' intestines, are associated with oxidative stress. Quercetin (Que) is a polyphenolic compound that shows good anti-cancer, anti-inflammation and anti-oxidation effects. This study aimed to elaborate whether or not Que promotes IPEC-J2 (intestinal porcine enterocyte cells) proliferation and protects IPEC-J2 from oxidative damage. Thus, we examined the effects of Que on proliferation and H₂O₂-induced apoptosis in IPEC-J2. The results showed that Que increased IPEC-J2 viabililty, propelled cells from G1 phase into S phase and down-regulated gene levels of P27 and P21, respectively. Besides, H₂O₂-induced cell damage was alleviated by Que after different exposure times, and Que depressed apoptosis rate, reactive oxygen species (ROS) level and percentage of G1 phase cells and elevated the percentage of cells in G2 phase and S phase and mitochondrial membrane potential (Δψm) after IPEC-J2 exposure to H₂O₂. Meanwhile, Que reduced the value of Bax/Bcl-2 in H₂O₂ exposed cells. In low-degree oxidative damage cells, lipid peroxidation product malondialdehyde (MDA) content and superoxide dismutase (SOD) activity were increased. In turn, Que could reverse the change of MDA content and SOD activity in low-degree damage cells. Nevertheless, catalase (CAT) activity was not changed in IPEC-J2 incubated with Que under low-degree damage conditions. Interestingly, relative expressive levels of the proteins claudin-1 and occludin were not altered under low-degree damage conditions, but Que could improve claudin-1 and occludin levels, slightly. This research indicates that Que can be greatly beneficial for intestinal porcine enterocyte cell proliferation and it protects intestinal porcine enterocyte cells from oxidation-induced apoptosis, and could be used as a potential feed additive for porcine intestinal health against pathogenic factor-induced oxidative damages and apoptosis.

Proanthocyanidins Protect Epithelial Cells from Zearalenone-Induced Apoptosis via Inhibition of Endoplasmic Reticulum Stress-Induced Apoptosis Pathways in Mouse Small Intestines

This study evaluated the protective effect of proanthocyanidins (PCs) on reducing apoptosis in the mouse intestinal epithelial cell model MODE-K exposed to zearalenone (ZEA) through inhibition of the endoplasmic reticulum stress (ERS)-induced apoptosis pathway. Our results showed that PCs could reduce the rate of apoptosis in MODE-K cells exposed to ZEA (p < 0.01). PCs significantly increased the ZEA-induced antioxidant protective effects on the enzymes superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) and on the content of GSH. PCs also significantly decreased the ZEA-induced increase in the content of malondialdehyde (MDA). The analysis indicated that ZEA increased both mRNA and protein expression levels of C/EBP homologous protein (CHOP), GRP78, c-Jun N-terminal kinase (JNK), and cysteinyl aspartate specific proteinase 12 (caspase-12) (p < 0.05), which are related to the ERS-induced apoptosis pathway. ZEA decreased levels of the pro-apoptotic related protein Bcl-2 (p < 0.05) and increased the anti-apoptotic related protein Bax (p < 0.05). Co-treatment with PCs was also shown to significantly reverse the expression levels of these proteins in MODE-K cells. The results demonstrated that PCs could protect MODE-K cells from oxidative stress and apoptosis induced by ZEA. The underlying mechanism may be that PCs can alleviate apoptosis in mouse intestinal epithelial cells by inhibition of the ERS-induced apoptosis pathway.

Zearalenone Promotes Cell Proliferation or Causes Cell Death?

Zearalenone (ZEA), one of the mycotoxins, exerts different mechanisms of toxicity in different cell types at different doses. It can not only stimulate cell proliferation but also inhibit cell viability, induce cell apoptosis, and cause cell death. Thus, the objective of this review is to summarize the available mechanisms and current evidence of what is known about the cell proliferation or cell death induced by ZEA. An increasing number of studies have suggested that ZEA promoted cell proliferation attributing to its estrogen-like effects and carcinogenic properties. What’s more, many studies have indicated that ZEA caused cell death via affecting the distribution of the cell cycle, stimulating oxidative stress and inducing apoptosis. In addition, several studies have revealed that autophagy and some antioxidants can reverse the damage or cell death induced by ZEA. This review thoroughly summarized the metabolic process of ZEA and the molecular mechanisms of ZEA stimulating cell proliferation and cell death. It concluded that a low dose of ZEA can exert estrogen-like effects and carcinogenic properties, which can stimulate the proliferation of cells. While, in addition, a high dose of ZEA can cause cell death through inducing cell cycle arrest, oxidative stress, DNA damage, mitochondrial damage, and apoptosis.

Mycotoxins and oxidative stress: where are we?

Mycotoxins are the most common contaminants of food and feed worldwide and are considered an important risk factor for human and animal health. Oxidative stress occurs in cells when the concentration of reactive oxygen species exceeds the cell’s antioxidant capacity. Oxidative stress causes DNA damage, enhances lipid peroxidation, protein damage and cell death. This review addresses the toxicity of the major mycotoxins, especially aflatoxin B1, deoxynivalenol, nivalenol, T-2 toxin, fumonisin B1, ochratoxin, patulin and zearalenone, in relation to oxidative stress. It summarises the data associated with oxidative stress as a plausible mechanism for mycotoxin-induced toxicity. Given the contamination caused by mycotoxins worldwide, the protective effects of a variety of natural compounds due to their antioxidant capacities have been evaluated. We review data on the ability of vitamins, flavonoids, crocin, curcumin, green tea, lycopene, phytic acid, L-carnitine, melatonin, minerals and mixtures of anti-oxidants to mitigate the toxic effect of mycotoxins associated with oxidative stress.

Zearalenone (ZEA)-induced intestinal inflammation is mediated by the NLRP3 inflammasome

To ascertain whether zearalenone (ZEA) could induce intestinal inflammation and investigate its possible mechanism, we investigated inflammatory cytokine release and the activation of the NLRP3 inflammasome after ZEA treatment both in vitro or in vivo. First, intestinal porcine enterocyte cell line (IPEC-J2) cells and mouse peritoneal macrophages were treated with ZEA to detect NLRP3 inflammasome activation, and the role of reactive oxygen species (ROS) in ZEA-induced inflammation was investigated. Then, Balb/c mice were fed a gavage of ZEA, and the disease activity indices (DAIs) and histological analysis were used to assess intestinal inflammation. Our study showed that the mRNA expression of NLRP3 inflammasome, pro-interleukin-1β (pro-IL-1β), and pro-interleukin-18 (pro-IL-18) was up-regulated 0.5- to 1-fold and that the release of IL-1β and IL-18 increased from 48 pg mL^-1 to 55 pg mL^-1 and 110 pg mL^-1 to 145 pg mL^-1, respectively. However, ROS inhibitor N-acetyl-l-cysteine (NAC) reduced IL-1β and IL-18 release to 45 pg mL^-1 and 108 pg mL^-1. Moreover, the same phenomenon was observed in intestinal tissues of ZEA-treated mice. In addition, clinical parameters of treated mice showed stools became loose and contained mucous. In addition, the presence of gross blood stool was found in the last 2 d. Histological analysis showed obvious inflammatory cell infiltration and tissue damage in the colon. These findings uncovered a possible mechanism of intestinal mucosal innate immunity in response to mycotoxin ZEA that ZEA could activate the ROS-mediated NLRP3 inflammasome and, in turn, contribute to the caspase-1-dependent activation of the inflammatory cytokines IL-1β and IL-18.

Protective effect of proanthocyanidin on mice Sertoli cell apoptosis induced by zearalenone via the Nrf2/ARE signalling pathway

This study evaluated the protective effect of proanthocyanidin (PC) on the cytotoxicity of the Sertoli cell TM4 of mice, as induced by zearalenone (ZEA). Flow cytometry was used to detect the apoptosis rate of cells in each group. The activities of antioxidant enzymes and the content of antioxidant substances were detected by using a proprietary kit; the RT-PCR method was used to detect the expression level of mRNA, the related genes of Nrf2/ARE signal pathway, the nuclear factor E2 related factor 2 (Nrf2), heme oxygenase 1 (HO-1), glutathione peroxidase (GSH-Px), quinone oxidoreductase 1 (NQO1), γ-glutamylcysteine synthetase (γ-GCS) and the expression level of mRNA, the apoptosis-related genes, Bcl-2 and Bax; the Western-blot method was used to detect the protein expression levels of Nrf2, GSH-Px, HO-1, γ-GCS and NQO1 in each group. Our results showed that PC could reduce the apoptosis rate of the TM4 cells exposed to ZEA (p < 0.01); PC could enhance the decrease in the activities of T-SOD and GSH-Px induced by ZEA (p < 0.05), reduce the increase in the content of MDA, as caused by ZEA; PC could significantly up-regulate the down-regulation levels of the mRNA and protein of Nrf2, GSH-Px, HO-1, γ-GCS and NQO1 induced by ZEA. PC could enhance the decrease in the mRNA expression level of Bcl-2 and down-regulate the mRNA expression of Bax induced by ZEA (p < 0.05). These results demonstrated that PC conferred protective effects against oxidative damage and apoptosis of TM4 cells induced by ZEA. The protection mechanism of PC on TM4 cells might act through the activation of the Nrf2/ARE signalling pathway.