Ochratoxin A induces oxidative DNA damage and G1 phase arrest in human peripheral blood mononuclear cells in vitro

1H NMR Spectroscopy Primitivo Red Wine Screening After Grape Pomace Repassage for Possible Toxin Contamination Removal

Food safety and quality awareness have reached significant relevance as consumers are more interested in authentic foods and drinks with specific organoleptic values. Among foodstuffs, grape products can be contaminated by Ochratoxin A (OTA), a mycotoxin that can occur in red grape after infection with Aspergillus carbonarius. The high affinity of grape pomace with OTA makes its use advantageous as an adsorbing/decontaminating material whether the pomace is fresh, has undergone pressing, or has undergone a stabilizing process. The effects of different grape repassage treatments on wine metabolic profiles were studied by 1H NMR spectroscopy coupled with metabolomics. The relative quantification of discriminating metabolites for activated-carbon-treated samples revealed higher levels of ethyl acetate and succinate than for the grape-pomace-repassed wine samples. On the contrary, the latter exhibited a relatively high content of glycerol, lactate, tartaric, isobutanol, isopentanol, and polyphenols. Although a specific decrease in aromatic compounds such as gallic acid, tyrosine, and tyrosol was also observed compared with the controls, for the pomace-based processes, the activated carbon treatment led to a marked general impoverishment of the metabolomic profiles, with a reduction in organic acids and glycerol. The repassage of wine over the grape pomace did not significantly affect the quality attributes of the wine, offering an alternative natural adsorbing/decontaminating material for the removal of OTA.

Quercetin protects the liver of broiler chicken against oxidative stress and apoptosis induced by ochratoxin A

Ochratoxin A (OTA) is a mycotoxin that causes major health concerns in human and animals. Quercetin (QUE) is a flavonoid that possesses antioxidant, anti-inflammatory and anti-apoptotic properties. This report aims to investigate the ameliorative effects of QUE against OTA-induced hepatotoxicity in broiler chicken. Forty broiler chicks were equally allocated into 4 groups: Group I (control), Group II (OTA), Group III (QUE) and Group IV (OTA + QUE). OTA (0.5 mg/kg) and QUE (0.5 g/kg) were incorporated into the chicken feed for 42 days. The results presented a significant decrease in body weight and elevation in feed conversion ratio, and a significant elevation of the activities of serum alanine aminotransferase and aspartate aminotransferase enzymes in the OTA birds. Additionally, there was a significant decrease in catalase activity and reduced glutathione content and a significant elevation in malondialdehyde level in the liver of OTA-exposed birds. Various hepatocellular lesions were also noticed in the OTA-exposed birds. OTA exposure up-regulated the phosphatase and tensin homologue (PTEN) and the pro-apoptotic genes and down-regulated the anti-apoptotic genes in the liver. The addition of QUE ameliorated most of the hepatotoxic effects of OTA.

Protective Effects of Carotenoid-Loaded Nanostructured Lipid Carriers Against Ochratoxin-A-Induced Cytotoxicity

Ochratoxin A (OTA) is a mycotoxin produced by Aspergillus ochraceous and various Penicillium species, which are known for contaminating agricultural products and posing significant health risks, which include immunotoxicity. This study aims to evaluate the potential of nanostructured lipid carriers (NLCs) loaded with a carotenoid-enriched extract from pumpkin peel (Cucurbita maxima L.) in mitigating the toxic effects of OTA. To address the poor bioavailability and instability of carotenoids, nanoencapsulation techniques were employed to enhance their delivery and efficacy. NLCs were formulated using hydrogenated sunflower oil, pumpkin oil, and soy lecithin using hot high-pressure homogenization. The in vitro study involved co-digesting OTA-contaminated bread with an NLC formulation and assessing the impact of the encapsulated carotenoid on OTA bioaccessibility, bioavailability, and cellular toxicity using Caco-2 and Jurkat T cells. Even though no significant influence was observed on the bioaccessibility and bioavailability of OTA, carotenoid-loaded NLCs exhibited cytoprotective effects by improving cell viability and mitigating OTA-induced toxicity in both Caco-2 and Jurkat T cells. Particularly, the flow cytometry analysis highlighted the ability of carotenoids to mitigate OTA-induced cellular damage by decreasing ROS production and limiting mitochondrial mass changes. The study suggests that the encapsulation of carotenoids in NLCs represents a promising strategy to enhance their protective effects against OTA toxicity, potentially offering a novel approach to food safety and public health protection. The study underscores the potential of nanotechnology in improving the bioavailability and efficacy of natural antioxidants to mitigate mycotoxin-induced damage.

Involvement of multiple epigenetic mechanisms by altered DNA methylation from the early stage of renal carcinogenesis before proliferative lesion formation upon repeated administration of ochratoxin A

Ochratoxin A (OTA) is a rat renal carcinogen that induces karyomegaly and micronuclei in proximal tubular epithelial cells (PTECs). We previously performed comprehensive gene profiling of alterations in promoter-region methylation and gene expression in PTECs of rats treated with OTA for 13 weeks. The OTA-specific gene profile was obtained by excluding genes showing expression changes similar to those upon treatment with 3-chloro-1,2-propanediol, a renal carcinogen not inducing karyomegaly. In this study, we validated the candidate genes using methylated DNA enrichment PCR and real-time RT-PCR, and identified Gen1, Anxa3, Cdkn1a, and Osm as genes showing OTA-specific epigenetic changes. These genes and related molecules were subjected to gene expression and immunohistochemical analyses in the PTECs of rats treated with OTA, other renal carcinogens, or non-carcinogenic renal toxicants for 4 or 13 weeks. Cdkn1a upregulation and increase of p21WAF1/CIP1+ karyomegalic PTECs were observed with OTA, matching the findings associated with micronucleus-inducing carcinogens. This suggested that the increase of p21WAF1/CIP1+ karyomegalic PTECs is linked to micronucleus formation, which in turn accelerates chromosomal instability. The upregulation of Cdkn1a-related genes with OTA suggests the acquisition of a senescence-associated secretory phenotype, which promotes the establishment of a carcinogenic environment. Meanwhile, OTA specifically caused a decrease of GEN1+ PTECs reflecting Gen1 downregulation and an increase of ANXA3+ PTECs reflecting Anxa3 upregulation, as well as Osm upregulation. OTA may efficiently disrupt pathways for repairing the DNA double-strand breaks that it itself causes, via Gen1 downregulation, and enhance cell proliferation through the upregulation of Anxa3 and Osm. This may exacerbate the chromosomal instability from the early stage of OTA-induced renal carcinogenesis before proliferative lesions form. OTA may cause renal carcinogenesis involving multiple epigenetic mechanisms.

Grape pomace as a novel functional ingredient: Mitigating ochratoxin A bioaccessibility and unraveling cytoprotective mechanisms in vitro

Mycotoxins, secondary metabolites produced by molds, pose significant health risk through contamination of globally consumed cereals. Ochratoxin A (OTA), a prevalent mycotoxin in cereals, is associated with various health hazards, including immunotoxicity. This study explores the bioaccessibility of OTA in bread and its impact on the gastrointestinal barrier. A focus is placed on grape pomace (GP), a by-product of the wine industry, as a potential mitigator of OTA toxicity. Results demonstrate that GP reduces OTA bioaccessibility in the human gastrointestinal system from 94% to 81% at intestinal level, showing promise in limiting the absorption of the harmful toxin. Additionally, GP exhibits cytoprotective effects, enhancing cell viability and mitigating OTA-induced toxicity in both Caco-2 and Jurkat T cells. In view of the above, to understand the mechanisms by which OTA exhibits its toxic effects, flow cytometry was chosen as the main technique for the analysis of cell cycle, reactive oxygen species levels and mitochondrial parameters. Cytofluorimetric evaluation indicates GP's potential in limiting OTA-induced damage at cellular level. The study suggests that GP could serve as functional ingredient to reduce mycotoxin bioaccessibility and toxicity in cereal-based foods, offering a novel and promising approach to enhance food safety and protect public health. The finding highlights the potential of utilizing grape pomace in food formulations to mitigate mycotoxin contamination, providing a valuable contribution to the ongoing efforts to ensure the safety of globally consumed cereal products.

Identification of genes showing altered DNA methylation and gene expression in the renal proximal tubular cells of rats treated with ochratoxin A for 13 weeks

Ochratoxin A (OTA) is a mycotoxin that causes renal carcinogenicity following the induction of karyomegaly in proximal tubular cells after repeated administration to rats. Here, we performed gene profiling regarding altered DNA methylation and gene expression in the renal tubules focusing on the mechanism of OTA-induced carcinogenesis. For this purpose, OTA or 3-chloro-1,2-propanediol (3-MCPD), a renal carcinogen not inducing karyomegaly, was administered to rats for 13 weeks, and DNA methylation array and RNA sequencing analyses were performed on proximal tubular cells. Genes for which OTA altered the methylation status and gene expression level, after excluding genes showing similar expression changes by 3-MCPD, were subjected to confirmation analysis of the transcript level by real-time reverse-transcription PCR. Gene Ontology (GO)-based functional annotation analysis of validated genes revealed a cluster of hypermethylated and downregulated genes enriched under the GO term "mitochondrion," such as those associated with metabolic reprogramming in carcinogenic process (Clpx, Mrpl54, Mrps34, and Slc25a23). GO terms enriched for hypomethylated and upregulated genes included "response to arsenic-containing substance," represented by Cdkn1a involved in cell cycle arrest, and "positive regulation of IL-17 production," represented by Osm potentiating cell proliferation promotion. Other genes that did not cluster under any GO term included Lrrc14 involved in NF-κB-mediated inflammation, Gen1 linked to DNA repair, Has1 related to chromosomal aberration, and Anxa3 involved in tumor development and progression. In conclusion, a variety of genes engaged in carcinogenic processes were obtained by epigenetic gene profiling in rat renal tubular cells specific to OTA treatment for 13 weeks.

The Effect of Aflatoxin B1 on Tumor-Related Genes and Phenotypic Characters of MCF7 and MCF10A Cells

The fungal toxin aflatoxin B1 (AB1) and its reactive intermediate, aflatoxin B1-8, 9 epoxide, could cause liver cancer by inducing DNA adducts. AB1 exposure can induce changes in the expression of several cancer-related genes. In this study, the effect of AB1 exposure on breast cancer MCF7 and normal breast MCF10A cell lines at the phenotypic and epigenetic levels was investigated to evaluate its potential in increasing the risk of breast cancer development. We hypothesized that, even at low concentrations, AB1 can cause changes in the expression of important genes involved in four pathways, i.e., p53, cancer, cell cycle, and apoptosis. The transcriptomic levels of BRCA1, BRCA2, p53, HER1, HER2, cMyc, BCL2, MCL1, CCND1, WNT3A, MAPK1, MAPK3, DAPK1, Casp8, and Casp9 were determined in MCF7 and MCF10A cells. Our results illustrate that treating both cells with AB1 induced cytotoxicity and apoptosis with reduction in cell viability in a concentration-dependent manner. Additionally, AB1 reduced reactive oxygen species levels. Phenotypically, AB1 caused cell-cycle arrest at G1, hypertrophy, and increased cell migration rates. There were changes in the expression levels of several tumor-related genes, which are known to contribute to activating cancer pathways. The effects of AB1 on the phenotype and epigenetics of both MCF7 and MCF10A cells associated with cancer development observed in this study suggest that AB1 is a potential risk factor for developing breast cancer.

Aspergillus awamori attenuates ochratoxin A-induced renal and cardiac injuries in rabbits by activating the Nrf2/HO-1 signaling pathway and downregulating IL1β, TNFα, and iNOS gene expressions

Ochratoxin A (OTA) is one of the most dangerous and that pollute agricultural products, inducing a variety of toxic effects in humans and animals. The current study explored the protective effect of different concentrations of Aspergillus awamori (A. awamori) against OTA (0.3 mg/kg diet) induced renal and cardiac damage by exploring its mechanism of action in 60 New Zealand white male rabbits. Dietary supplementation of A. awamori at the selected doses of 50, 100, and 150 mg/kg diet, respectively, for 2 months significantly improved the rabbit's growth performance; modulated the suppressed immune response and restored the altered hematological parameters; reduced the elevated levels of renal injury biomarkers such as urea, creatinine, and alkaline phosphatase; and increased serum total proteins concentrations. Moreover, it also declined enzymatic activities of cardiac injury biomarkers, including AST, LDH, and CK-MB. A. awamori alleviated OTA-induced degenerative and necrotic changes in the kidney and heart of rabbits. Interestingly, A. awamori upregulated Nrf2/OH-1 signaling pathway. Therefore enhanced TAC, CAT, and SOD enzyme activities and reduced OTA-induced oxidative and nitrosative stress by declining iNOS gene expression and consequently lowered MDA and NO levels. In addition to attenuating renal and cardiac inflammation via reducing IL-1β, TNF-α gene expressions in a dose-dependent response. In conclusion,this is the first report to pinpoint that dietary incorporation of A. awamori counteracted OTA-induced renal and cardiac damage by potentiating the rabbit's antioxidant defense system through its potent antioxidant, free radical scavenging, and anti-inflammatory properties in a dose-dependent response. Based on our observations, A. awamori could be utilized as a natural protective agent against ochratoxicosis in rabbits.

The multiple biotoxicity integrated study in grass carp (Ctenopharyngodon idella) caused by Ochratoxin A: Oxidative damage, apoptosis and immunosuppression

Ochratoxin A (OTA) is a common hazardous food contaminant that seriously endangers human and animal health. However, limited study is focused on aquatic animal. This research investigated the multiple biotoxicity of OTA on spleen (SP) and head kidney (HK) in grass carp and its related mechanism. Our data showed that, dietary supplemented with OTA above 1209 μg/kg caused histopathological damages by decreasing the number of lymphocytes and necrotizing renal parenchymal cells. Meanwhile, OTA caused oxidative damage and reduced the isoforms mRNAs transcripts of antioxidant enzymes (e.g., GPX1, GPX4, GSTO) partly due to suppressing NF-E2-related factor 2 (Nrf2). OTA triggered apoptosis through mitochondria and death receptor pathway potentially by p38 mitogen-activated protein kinase (p38MAPK) activation. Besides, OTA exacerbated inflammation by down-regulation of anti-inflammatory factor (e.g., IL-10, IL-4) and up-regulations of pro-inflammatory factors (e.g., TNF-α, IL-6), which could be ascribed to signaling meditation of Janus kinase / signal transducer and activator of transcription (JAK/STAT). Additionally, the safe upper limits of OTA were estimated to be 677.6 and 695.08 μg/kg based on the immune-related indexes (C3 contents in the SP and LZ activities in the HK, respectively). Our study has provided a wide insight for toxicological assessment of feed pollutant in aquatic animals.

Protective Effects of Bacillus Subtilis Fermentation Extract Against Ochratoxin A-induced Nephrotoxicity and Immunotoxicity in Broiler Chickens

Introduction

Ochratoxin A (OTA) is a mycotoxin notably produced by Aspergillus and Penicillium spp. Bacillus subtilis fermentation extract (BSFE) contains specific enzymes which hydrolyse OTA. This study evaluated the efficiency of BSFE in ameliorating the immunotoxic and nephrotoxic effects of OTA in broiler chickens.

Material and Methods

Day-old broiler chicks were divided equally into four groups of ten: control, OTA (0.5 mg/kg feed), BSFE product (1 mL/L water) and OTA + BSFE at the same concentrations. The chicks were vaccinated against avian influenza, Newcastle disease, and infectious bronchitis, and lymphoproliferation was induced in all birds by phytohaemagglutinin-P (PHA-P). Serum samples were taken before sacrifice and organ tissue samples were taken after, in which renal function biomarkers were assayed and the presence of OTA residue was evaluated by high-performance thin-layer chromatography. Protein markers of apoptosis were determined by qPCR, and tissue lesions were examined histopathologically.

Results

Exposure to OTA significantly decreased the antibody response to the vaccines and the lymphoproliferative response to PHA-P, and significantly elevated the renal function indicators: serum urea, uric acid and creatinine. It also induced oxidative stress (reduced catalase activity and glutathione concentration), lipid peroxidation (increased malondialdehyde content), apoptosis (increased Bax and Caspase-3 and decreased Bcl-2 gene levels) and pathological lesions in kidney, bursa of Fabricius, spleen and thymus tissue. Residues of OTA were detected in the serum and tissue. BSFE mitigated most of these toxic effects.

Conclusion

BSFE counters OTA-induced immunotoxicity and nephrotoxicity because of its content of carboxypeptidase and protease enzymes.

Pumpkin extract and fermented whey individually and in combination alleviated AFB1- and OTA-induced alterations on neuronal differentiation invitro

Food and feed are daily exposed to mycotoxin contamination which effects may be counteracted by functional compounds like carotenoids and fermented whey. Among mycotoxins, the most toxic and studied are aflatoxin B1 (AFB1) and ochratoxin A (OTA), which neurotoxicity is not well reported. Therefore, SH-SY5Y human neuroblastoma cells ongoing differentiation were exposed during 7 days to digested bread extracts contained pumpkin and fermented whey, individually and in combination, along with AFB1 and OTA and their combination, in order to evaluate their presumed effects on neuronal differentiation. The immunofluorescence analysis of βIII-tubulin and dopamine markers pointed to OTA as the most damaging treatment for cell differentiation. Cell cycle analysis reported the highest significant differences for OTA-contained bread compared to the control in phase G₀/G₁. Lastly, RNA extraction was performed and gene expression was analyzed by qPCR. The selected genes were related to neuronal differentiation and cell cycle. The addition of functional ingredients in breads not only enhancing the expression of neuronal markers, but also induced an overall improvement of gene expression compromised by mycotoxins activity. These data confirm that in vitro neuronal differentiation may be impaired by AFB1 and OTA-exposure, which could be modulated by bioactive compounds naturally found in diet.

Study on the mechanism of Salvia miltiorrhiza polysaccharides in relieving liver injury of broilers induced by florfenicol

In order to explore the transcriptomics and proteomics targets and pathways of Salvia miltiorrhiza polysaccharides (SMPs) alleviating florfenicol (FFC)-induced liver injury in broilers, 60 1-day-old broilers were randomly divided into 3 groups: control group ( GP1) was fed tap water, FFC model (GP2) was given tap water containing FFC 0.15 g/L, and SMPs treatment group (GP3) was given tap water containing FFC 0.15 g/L and SMPs 5 g/L. Starting from 1 day of age, the drug was administered continuously for 5 days. On the 6th day, blood was collected from the heart and the liver was taken. Then 3 chickens were randomly taken from each group, and their liver tissues were aseptically removed and placed in an enzyme-free tube. Using high-throughput mRNA sequencing and TMT-labeled quantitative proteomics technology, the transcriptome and proteome of the three groups of broiler liver were analyzed, respectively. The results of the study showed that the liver tissue morphology of the chicks in the GP1 and GP3 groups was complete and there were no obvious necrotic cells in the liver cells. The liver tissue cells in the GP2 group showed obvious damage, the intercellular space increased, and the liver cells showed extensive vacuolation and steatosis. Compared with the GP1 group, the daily gain of chicks in the GP2 group was significantly reduced (P < 0.0 5 or P < 0.01). Compared with the GP2 group, the GP3 group significantly increased the daily gain of chicks (P <0.0 5 or P <0.01). Compared with the GP1 group, the serum levels of ALT, AST, liver LPO, ROS, and IL-6 in the GP2 group were significantly increased (P < 0.0 5 or P < 0.01), and the contents of T-AOC, GSH-PX, IL-4, and IL-10 in the liver were significantly decreased (P < 0.0 5 or P < 0.01). After SMPs treatment, the serum levels of ALT, AST, liver LPO, ROS, and IL-6 were significantly reduced (P < 0.0 5 or P < 0.01), and the contents of T-AOC, GSH-PX, IL-4, and IL-10 in the liver were significantly increased (P < 0.0 5 or P < 0.01). There were 380 mRNA and 178 protein differentially expressed between GP2 group and GP3 group. Part of DEGs was randomly selected for QPCR verification, and the expression results of randomly selected FABP1, SLC16A1, GPT2, AACS, and other genes were verified by QPCR to be consistent with the sequencing results, which demonstrated the accuracy of transcriptation-associated proteomics sequencing. The results showed that SMPs could alleviate the oxidative stress and inflammatory damage caused by FFC in the liver of chicken and restore the normal function of the liver. SMPs may alleviate the liver damage caused by FFC by regulating the drug metabolism-cytochrome P450, PPAR signaling pathway, MAPK signaling pathway, glutathione metabolism, and other pathways.

Selective Activation of Endoplasmic Reticulum Stress by Reactive-Oxygen-Species-Mediated Ochratoxin A-Induced Apoptosis in Tubular Epithelial Cells

Ochratoxin A (OTA), one of the major food-borne mycotoxins, impacts the health of humans and livestock by contaminating food and feed. However, the underlying mechanism of OTA nephrotoxicity remains unknown. This study demonstrated that OTA induced apoptosis through selective endoplasmic reticulum (ER) stress activation in human renal proximal tubular cells (HK-2). OTA increased ER-stress-related JNK and precursor caspase-4 cleavage apoptotic pathways. Further study revealed that OTA increased reactive oxygen species (ROS) levels, and N-acetyl cysteine (NAC) could reduce OTA-induced JNK-related apoptosis and ROS levels in HK-2 cells. Our results demonstrate that OTA induced ER stress-related apoptosis through an ROS-mediated pathway. This study provides new evidence to clarify the mechanism of OTA-induced nephrotoxicity.

Systematic Structure-Based Search for Ochratoxin-Degrading Enzymes in Proteomes from Filamentous Fungi

(1) Background: ochratoxins are mycotoxins produced by filamentous fungi with important implications in the food manufacturing industry due to their toxicity. Decontamination by specific ochratoxin-degrading enzymes has become an interesting alternative for the treatment of contaminated food commodities. (2) Methods: using a structure-based approach based on homology modeling, blind molecular docking of substrates and characterization of low-frequency protein motions, we performed a proteome mining in filamentous fungi to characterize new enzymes with potential ochratoxinase activity. (3) Results: the proteome mining results demonstrated the ubiquitous presence of fungal binuclear zinc-dependent amido-hydrolases with a high degree of structural homology to the already characterized ochratoxinase from Aspergillus niger. Ochratoxinase-like enzymes from ochratoxin-producing fungi showed more favorable substrate-binding pockets to accommodate ochratoxins A and B. (4) Conclusions: filamentous fungi are an interesting and rich source of hydrolases potentially capable of degrading ochratoxins, and could be used for the detoxification of diverse food commodities.

Sterigmatocystin-induced DNA damage triggers cell-cycle arrest via MAPK in human neuroblastoma cells

Sterigmatocystin (STE) is a common mycotoxin found in food and feed. Many studies showed that STE is genotoxic. However, up to now, the potential genotoxicity of STE on human neuronal system remains unknown. In this study, we explored the effect of STE on DNA damage and cell-cycle progression on human neuroblastoma SH-SY5Y cells exposed to various concentrations of STE (0.78, 1.56 and 3.12 µM) for 24 h. The results indicated that STE exposure induced DNA damage, as evidenced by DNA comet tails formation and increased γH2AX foci. Additionally, genotoxicity was confirmed by micronuclei (MN) analysis. Furthermore, we found that STE exposure led to cell-cycle arrest at the S and the G₂/M phase. Considering the important role played by MAPK and p53 signaling pathways in cell-cycle arrest, we explored their potential involvement in STE-induced cell-cycle arrest by using specific inhibitors. The inhibition of JNK and ERK resulted to attenuate S and G₂/M arrest, whereas the inhibition of p38 and p53 attenuated only STE-induced S phase arrest. In conclusion, the present study demonstrates that STE induced DNA damage and triggered MAPK and p53 pathways activation, resulting in cell-cycle arrest at the S and the G₂/M phase.

Nrf2: a main responsive element in cells to mycotoxin-induced toxicity

Nuclear factor erythroid 2-like 2 (Nrf2) is a transcription factor participating in response to cellular oxidative stress to maintain the redox balance. Generation of reactive oxygen species (ROS) and, in consequence, oxidative stress, are physiological as well as pathological processes which take place in almost all types of cells. Nrf2, in response to oxidative stress, activates expression and production of antioxidant enzymes to remove free radicals. However, the role of Nrf2 seems to be more sophisticated and its increased expression observed in cancer cells allows to draw a conclusion that its role is tissue—and condition—dependent. Interestingly, Nrf2 might also play a crucial role in response to environmental factors like mycotoxins. Thus, the aim of the study is to review the role of Nrf2 in cells exposed to most common mycotoxins to check if the Nrf2 signaling pathway serves as the main response element to mycotoxin-induced oxidative stress in human and animal cells and if it can be a target of detoxifying agents.

Comet assay: a versatile but complex tool in genotoxicity testing

The comet assay is a versatile method for measuring DNA strand breaks in individual cells. It can also be applied to cells isolated from treated animals. In this review, we highlight advantages and limitations of this in vivo comet assay in a regulatory context. Modified versions of the standard protocol detect oxidized DNA bases and may be used to reveal sites of DNA base loss, DNA interstrand crosslinks, and the extent of DNA damage induced indirectly by reactive oxygen species elicited by chemical-induced oxidative stress. The assay is, however, at best semi-quantitative, and we discuss possible approaches to improving DNA damage quantitation and highlight the necessity of optimizing protocol standardization to enhance the comparability of results between laboratories. As a genotoxicity test in vivo, the in vivo comet assay has the advantage over the better established micronucleus erythrocyte test that it can be applied to any organ, including those that are specific targets of chemical carcinogens or those that are the first sites of contact of ingested or inhaled mutagens. We illustrate this by examples of its use in risk assessment for the food contaminants ochratoxin and furan. We suggest that improved quantitation is required to reveal the full potential of the comet assay and enhance its role in the battery of in vivo approaches to characterize the mechanisms of toxicity and carcinogenicity of chemicals and to aid the determination of safe human exposure limits.

Ochratoxin A-induced genotoxic and epigenetic mechanisms lead to Alzheimer disease: its modulation with strategies

Ochratoxin A (OTA) is a naturally occurring mycotoxin mostly found in food items including grains and coffee beans. It induces DNA single-strand breaks and has been considered to be carcinogenic. It is recognized as a serious threat to reproductive health both in males and females. OTA is highly nephrotoxic and carcinogenic, and its potency changes evidently between species and sexes. There is a close association between OTA, mutagenicity, carcinogenicity, and genotoxicity, but the underlying mechanisms are not clear. Reports regarding genotoxic effects in relation to OTA which leads to the induction of DNA adduct formation, protein synthesis inhibition, perturbation of cellular energy production, initiation of oxidative stress, induction of apoptosis, influences on mitosis, induction of cell cycle arrest, and interference with cytokine pathways. All these mechanisms are associated with nephrotoxicity, hepatotoxicity, teratotoxicity, immunological toxicity, and neurotoxicity. OTA administration activates various mechanisms such as p38 MAPK, JNKs, and ERKs dysfunctions, BDNF disruption, TH overexpression, caspase-3 and 9 activation, and ERK-1/2 phosphorylation which ultimately lead to Alzheimer disease (AD) progression. The current review will focus on OTA in terms of recent discoveries in the field of molecular biology. The main aim is to investigate the underlying mechanisms of OTA in regard to genotoxicity and epigenetic modulations that lead to AD. Also, we will highlight the strategies for the purpose of attenuating the hazards posed by OTA exposure.

Ochratoxin A induces reprogramming of glucose metabolism by switching energy metabolism from oxidative phosphorylation to glycolysis in human gastric epithelium GES-1 cells in vitro

Ochratoxin A (OTA) is a ubiquitous mycotoxin with potential nephrotoxic, hepatotoxic and immunotoxic effects. We previously demonstrated that OTA could cause mitochondrial function disturbance in GES-1 cells in vitro, which lead to the presumption that the glucose metabolism of GES-1 cells will be altered by OTA. Therefore in the present study, we explored the toxicity of OTA on glucose metabolism of GES-1 cells and the molecular mechanism. We found that OTA could induce aerobic glycolysis, evidenced shown by increase of glucose consumption, lactate production and cellular ATP concentration. We further detected expressions of GLUT1 and glycolytic enzymes including HK2, PFK1, PKM2 and LDHA as well as tricarboxylic acid (TCA) cycle-associated enzymes including IDH1, OGDH and CS. The results showed that expression of GLUT1 as well as the activities and expressions of HK2, PFK1 and LDHA were significantly increased while IDH1 and OGDH were reduced by OTA. As to PKM2, western blot showed that OTA could elevated the phospho-PKM2 Ser37 protein level and induce the nuclear accumulation of PKM2, which was further supported by immunofluorescence analyses, in addition, pyruvate kinase activity was reduced by OTA. In conclusion, these findings suggest that OTA exposure induces the metabolic shift from oxidative phosphorylation to aerobic glycolysis via regulating the activities and expressions of glycolysis and TCA-cycle associated molecules in GES-1 cells.

Risk assessment of ochratoxin A in food

The European Commission asked EFSA to update their 2006 opinion on ochratoxin A (OTA) in food. OTA is produced by fungi of the genus Aspergillus and Penicillium and found as a contaminant in various foods. OTA causes kidney toxicity in different animal species and kidney tumours in rodents. OTA is genotoxic both in vitro and in vivo; however, the mechanisms of genotoxicity are unclear. Direct and indirect genotoxic and non-genotoxic modes of action might each contribute to tumour formation. Since recent studies have raised uncertainty regarding the mode of action for kidney carcinogenicity, it is inappropriate to establish a health-based guidance value (HBGV) and a margin of exposure (MOE) approach was applied. For the characterisation of non-neoplastic effects, a BMDL 10 of 4.73 μg/kg body weight (bw) per day was calculated from kidney lesions observed in pigs. For characterisation of neoplastic effects, a BMDL 10 of 14.5 μg/kg bw per day was calculated from kidney tumours seen in rats. The estimation of chronic dietary exposure resulted in mean and 95th percentile levels ranging from 0.6 to 17.8 and from 2.4 to 51.7 ng/kg bw per day, respectively. Median OTA exposures in breastfed infants ranged from 1.7 to 2.6 ng/kg bw per day, 95th percentile exposures from 5.6 to 8.5 ng/kg bw per day in average/high breast milk consuming infants, respectively. Comparison of exposures with the BMDL 10 based on the non-neoplastic endpoint resulted in MOEs of more than 200 in most consumer groups, indicating a low health concern with the exception of MOEs for high consumers in the younger age groups, indicating a possible health concern. When compared with the BMDL 10 based on the neoplastic endpoint, MOEs were lower than 10,000 for almost all exposure scenarios, including breastfed infants. This would indicate a possible health concern if genotoxicity is direct. Uncertainty in this assessment is high and risk may be overestimated.

Beauvericin and ochratoxin A mycotoxins individually and combined in HepG2 cells alter lipid peroxidation, levels of reactive oxygen species and glutathione

The co-presence of more than one mycotoxin in food is being evidenced in last food surveys as reported in the literature. Beauvericin (BEA) is a non-legislated emergent mycotoxin while Ochratoxin A (OTA) has been widely studied and legislated. Concentration range individually studied was from 2.5 to 0.3 μM for BEA and from 25 to 3.1 μM for OTA; binary mixture [BEA + OTA] comprised concentrations of 1:10 ratio from [2.5 + 25] to [3.1 + 0.3] μM. Potential of toxicity of BEA in HepG2 cells was the highest at all times assayed (24, 48 and 72h). LPO was performed through malondyaldehyde (MDA) detection denoting in the binary mixture for [1.25 + 12.5] μM and at 24 and 72h the highest disturbance values. ROS denoted differences respect to the control at different times specially for OTA, while in binary combination only for few point times was denoted. Effects detected for ROS and LPO were connected with alterations detected for glutathione levels of oxidized and reduced form. A real scenario of consumers chronically exposed to different mycotoxins and their mixtures is here presented highlighting the good methodology to assess the risk from exposure to combinations of chemicals in food.

Selenium Yeast Alleviates Ochratoxin A-Induced Hepatotoxicity via Modulation of the PI3K/AKT and Nrf2/Keap1 Signaling Pathways in Chickens

The aim of this study was to investigate the protective effects of selenium yeast (Se-Y) against hepatotoxicity induced by ochratoxin A (OTA). The OTA-induced liver injury model was established in chickens by daily oral gavage of 50 µg/kg OTA for 21 days. Serum biochemistry analysis, antioxidant analysis, as well as the qRT-PCR and Western blot (WB) analyses were then used to evaluate oxidative damage and apoptosis in chicken liver tissue. The results showed that Se-Y significantly increased liver coefficient induced by OTA (P < 0.05). OTA + Se-Y treated group revealed that Se-Y reduced the OTA-induced increase in glutamic pyruvic transaminase (ALT), glutamic oxaloacetic transaminase (AST) and malonaldehyde (MDA) content, and reversed the decrease in antioxidant capacity (T-AOC), glutathione peroxidase (GSH-Px) and total superoxide dismutase (T-SOD) (P < 0.05). In this study, we found that OTA is involved in the mRNA expression levels about Nrf2/Keap1 and PI3K/AKT signaling pathways, such as oxidative stress-related genes (Nrf2, GSH-Px, GLRX2 and Keap1) and apoptosis-related genes (Bax, Caspase3, P53, AKT, PI3K and Bcl-2). Besides, significant downregulations of protein expression of HO-1, MnSOD, Nrf2 and Bcl-2, as well as a significant upregulation of Caspase3 and Bax levels were observed after contaminated with OTA (P < 0.05). Notably, OTA-induced apoptosis and oxidative damage in the liver of chickens were reverted back to normal level in the OTA + Se-Y group. Our findings indicate that pretreatment with Se-Y effectively ameliorates OTA-induced hepatotoxicity.

Astaxanthin Protects OTA-Induced Lung Injury in Mice through the Nrf2/NF-κB Pathway

The aim of this research was to evaluate the potential protective mechanism of astaxanthin (ASTA) against oxidative damage and inflammation caused by ochratoxin (OTA) in mouse lung. We divided mice into a control group (CG), an OTA group (PG), an astaxanthin group (AG), and an OTA+ASTA group (JG). Oxidative indices (malondialdehyde (MDA), total superoxide dismutase (T-SOD), and reduced glutathione (GSH)) and inflammatory markers (interleukin 1β (IL-1β), interleukin 6 (IL-6), and tumor necrosis factor α (TNF-α)) were assayed in the lung, and the lung-weight-to-body-weight ratio was calculated. Apoptosis was detected in pathological sections by the TdT-mediated dUTP nick-end labeling (TUNEL) assay. Oxidative damage and inflammation were detected in the lung of mice after exposure to OTA. Besides, Nrf2- and NF-κB-pathway-associated proteins were detected by Western blot. In contrast with OTA, ASTA significantly raised the expression of Nrf2, HO-1, and MnSOD, while the expression of other proteins (Keap1, TLR4, and NF-κB) was significantly decreased. These results indicate that ASTA exerted protective effects against OTA-induced oxidative damage and inflammation in the lung by regulating the Nrf2 and NF-κB pathways.

Zinc supplementation alleviates OTA-induced oxidative stress and apoptosis in MDCK cells by up-regulating metallothioneins

AIMS

The present study was to investigate the protective effects of Zn supplementation in OTA-induced apoptosis of Madin-Darby canine kidney (MDCK) epithelial cells and explore the potential mechanisms. Aiming to provides a new insight into the treatment strategy of OTA-induced nephrotoxicity by nutritional regulation.

MAIN METHODS

Initially, through MTT and LDH assay revealed that Zn supplementation significantly suppressed OTA-induced cytotoxicity in MDCK cells. Then, the production of reactive oxygen species (ROS) was detected by using a DCFH-DA assay. Annexin V-FITC/PI, Hoechst 33258 staining and Flow cytometry were used to detect the apoptosis. The expressions of apoptosis-related molecules were determined by RT-PCR, Western blotting. Interestingly, OTA treatment slightly increased the levels of Metallothionein-1 (MT-1) and Metallothionein-2 (MT-2) by using RT-PCR, Western blotting assay; while Zn supplementation further improved the increase of MT-1 and MT-2 induced by OTA. However, the inhibitive effects of Zn supplementation were significantly blocked after double knockdown of MT-1 and MT-2 by using Small Interfering RNA (siRNA) Transfection method.

KEY FINDINGS

Our study provides supportive data for the potential roles of Zn in reducing OTA-induced oxidative stress and apoptosis in MDCK cells.

SIGNIFICANCE

Zn is one of the key structural components of many proteins, which plays an important role in several physiological processes such as cell survival and apoptosis. This metal is expected to contribute to the conservative and adjuvant treatment of kidney disease and should therefore be investigated further.

An in vitro attempt at precision toxicology reveals the involvement of DNA methylation alteration in ochratoxin A-induced G0/G1 phase arrest

Precision toxicology evaluates the toxicity of certain substances by isolating a small group of cells with a typical phenotype of interest followed by a single cell sequencing-based analysis. In this in vitro attempt, ochratoxin A (OTA), a typical mycotoxin and food contaminant, is found to induce G0/G1 phase cell cycle arrest in human renal proximal tubular HKC cells at a concentration of 20 μM after a 24h-treatment. A small number of G0/G1 phase HKC cells are evaluated in both the presence and absence of OTA. These cells are sorted with a flow cytometer and subjected to mRNA and DNA methylation sequencing using Smart-Seq2 and single-cell reduced-representation bisulfite sequencing (scRRBS) technology, respectively. Integrated analysis of the transcriptome and methylome profiles reveals that OTA causes abnormal expression of the essential genes that regulate G1/S phase transition, act as signal transductors in G1 DNA damage checkpoints, and associate with the anaphase-promoting complex/cyclosome. The alteration of their DNA methylation status is a significant underlying epigenetic mechanism. Furthermore, Notch signaling and Ras/MAPK/CREB pathways are found to be suppressed by OTA. This attempt at precision toxicology paves the way for a deeper understanding of OTA toxicity and provides an innovative strategy to researchers in the toxicology and pharmacology field.

Impact of dietary Trichosporon mycotoxinivorans on ochratoxin A induced immunotoxicity; In vivo study

Ochratoxin A (OA), the secondary metabolite of certain Aspergillus and Penicillium species, is one of the potent biological immune-suppressor. The present study was designed to explore the in-vivo efficacy of Trichosporon mycotoxinivorans (TR); yeast strain isolated from the hindgut of the termite Mastotermes darwiniensis, against the immunotoxicity of OA in broiler birds. For this purpose, broiler chicks were offered diet added with TR (0.5, 1.0 or 2.0 g/kg feed) and/or OA (0.15, 0.3 or 1.0 mg/kg feed) for 42 days. Dietary OA at all levels, resulted in significant reduction (p ≤ 0.05) in the immune response of broiler birds as recorded by vacuolation and darkly stained pyknotic nuclei in bursa of Fabricius and thymus, humoral immune responses to sheep red blood cells (SRBC), in-vivo lymphoproliferative response to Phytohemagglutinin-P (PHA-P) and mononuclear phagocytic system function assay. Addition of TR in broiler diet significantly reduced (p ≤ 0.05) the immunotoxicity of OA at 0.15 and 0.30 mg/kg; however, against higher dietary level of OA (1.0 mg/kg), a partial protection was observed. Feeding TR alone had no immunomodulatory effect at any of tested level. Dietary addition of TR is proposed as an approach to combat the OA mediated immunological damages in broiler birds.

Ochratoxin A-Induced Hepatotoxicity through Phase I and Phase II Reactions Regulated by AhR in Liver Cells

Ochratoxin A (OTA) is a widespread mycotoxin produced by several species of the genera Aspergillus and Penicillium. OTA exists in a variety of foods, including rice, oats, and coffee and is hepatotoxic, with a similar mode of action as aflatoxin B1. The precise mechanism of cytotoxicity is not yet known, but oxidative damage is suspected to contribute to its cytotoxic effects. In this study, human hepatocyte HepG2 cells were treated with various concentrations of OTA (5-500 nM) for 48 h. OTA triggered oxidative stress as demonstrated by glutathione depletion and increased reactive oxygen species, malondialdehyde level, and nitric oxide production. Apoptosis was observed with 500 nM OTA treatment. OTA increased both the mRNA and protein expression of phase I and II enzymes. The same results were observed in an in vivo study using ICR mice. Furthermore, the relationship between phase I and II enzymes was demonstrated by the knockdown of the aryl hydrocarbon receptor (AhR) and NF-E2-related factor 2 (Nrf2) with siRNA. Taken together, our results show that OTA induces oxidative stress through the phase I reaction regulated by AhR and induces apoptosis, and that the phase II reaction is activated by Nrf2 in the presence of oxidative stress.

A multi-endpoint approach to the combined toxic effects of patulin and ochratoxin a in human intestinal cells

Humans can be exposed to a complex and variable combination of mycotoxins. After ingestion, intestinal mucosa constitutes the first biological barrier that can be exposed to high concentrations of these toxins. The present study aimed to characterize the combined cytotoxicity, genotoxicity and impact on the gastrointestinal barrier integrity of patulin (PAT, 0.7 μM to 100 μM) and ochratoxin A (OTA, 1 μM to 200 μM) mixtures in Caco-2 cells. A dose-ratio deviation was verified for cytotoxicity, implying that OTA was mainly responsible for synergism when dominant in the mixture, while this pattern was changed to antagonism for the highest PAT concentrations. Genotoxicity (comet assay) results were compatible with an interactive DNA damaging effect at the highest PAT and OTA concentrations, not clearly mediated by the formation of oxidative DNA breaks. Regarding gastrointestinal barrier integrity, a potential synergism was attained at low levels of both mycotoxins, changing to antagonism at higher doses. The present results indicate that combined mycotoxins effects may arise at the intestinal level and should not be underestimated when evaluating their risk to human health.

Occurrence of Ochratoxin A in Coffee: Threads and Solutions—A Mini-Review

Ochratoxin A (OTA) is a widespread bioactive extrolite from secondary metabolism of fungi which presence in foods like coffee is of public health concern, particularly for heavy drinkers. Coffee is one of the most consumed and appreciated non-alcoholic beverage in the world. Its production from the plantation to the coffee cup involves several steps that would determine the final concentration of OTA in the beverage. This review gives an overview of OTA contamination in roasted coffee beans in different countries and mitigation strategies for OTA reduction.

DNA damage in rat kidneys and liver upon subchronic exposure to single and combined ochratoxin A and citrinin

The study aimed to check whether ochratoxin A (OTA) and citrinin (CIT) increase DNA damage in the kidney and liver of male Wistar rats (alkaline comet assay), clarify the oxidative nature of DNA damage (hOGG1-modified comet assay), and verify whether resveratrol (RSV) could ameliorate OTA+CIT-induced genotoxicity. Rats were treated orally with OTA (0.125 and 0.250 mg/kg bodyweight (bw)) and CIT (2 mg/kg bw), OTA+CIT combinations and OTA+CIT+RSV (0.250+2+20 mg/kg bw) for 21 days. Both alkaline and hOGG1-modified comet assay showed that DNA damage was more severe in rat kidneys than in liver following mycotoxin treatment. Alkaline comet assay revealed a higher intensity of DNA damage, particularly as measured by tail intensity in the kidneys. Both tail length and tail intensity were OTA dose-dependent, but in combined OTA+CIT treatment these values were similar to CIT alone and lower than in animals treated with single OTA, possibly due to induction of apoptosis. hOGG1-modified comet showed that OTA+CIT evoked greater oxidative DNA damage than single mycotoxins. RSV did not reduce DNA damage measured by alkaline comet assay, but hOGG1-modified comet showed that RSV ameliorated OTA+CIT genotoxicity in the kidneys. Apart from oxidative stress, other mechanisms of DNA damage are involved in OTA and CIT genotoxicity. In rat kidneys RSV can reduce but not overcome oxidative DNA damage induced by combined OTA and CIT.

Ochratoxin A suppresses proliferation of Sertoli and Leydig cells in mice

Ochratoxin A (OTA) is a mycotoxin originating from Penicillium and Aspergillus. In addition to toxic effects in various tissues and cells, including neurons, immune cells, hepatocytes, and nephrons, it also causes carcinogenesis and teratogenesis. Although the negative effects of OTA with respect to the pathogenesis of diseases and the malfunction of various organs have been studied widely, the biological signaling mechanisms in testicular cells are less well known. Therefore, we determined the hazardous effect of OTA in two types of testicular cells: TM3 (mouse Leydig cells) and TM4 (mouse Sertoli cells). Treatment with OTA led to a significant decrease in the proliferation of both cell lines, as revealed by an increased proportion of cells in the sub-G1 phase. In addition, the phosphorylation of signaling molecules belonging to the PI3K (Akt, P70S6K, and S6) and MAPK (ERK1/2 and JNK) pathways was regulated by OTA in a dose-dependent manner in TM3 and TM4 cells. Furthermore, the combination treatment of OTA and signaling inhibitors (LY294002, U0126, or SP600125) exerted synergistic antiproliferative effects in TM3 and TM4 cells. OTA also reduced the concentration of calcium ions in the cytosol and mitochondria, which disrupted the calcium homeostasis necessary for maintaining the normal physiological functions of testicular cells. In conclusion, the results of the present study demonstrate the mechanism underlying the antiproliferative effects of OTA in mouse testicular cells. Exposure to OTA may result in abnormal sperm maturation and the failure of spermatogenesis, which leads to male infertility.

Differential Gene Expression Analysis of Bovine Macrophages after Exposure to the Penicillium Mycotoxins Citrinin and/or Ochratoxin A

Mycotoxins produced by fungal species commonly contaminate livestock feedstuffs, jeopardizing their health and diminishing production. Citrinin (CIT) and ochratoxin A (OTA) are mycotoxins produced by Penicillium spp. and commonly co-occur. Both CIT and OTA can modulate immune response by inhibiting cell proliferation and differentiation, altering cell metabolism, and triggering programmed cell death. The objective of this study was to determine the effects of sublethal exposure (i.e., the concentration that inhibited cell proliferation by 25% (IC₂₅)) to CIT, OTA or CIT + OTA on the bovine macrophage transcriptome. Gene expression was determined using the Affymetrix Bovine Genome Array. After 6 h of exposure to CIT, OTA or CIT + OTA, the number of differentially expressed genes (DEG), respectively, was as follows: 1471 genes (822 up-regulated, 649 down-regulated), 5094 genes (2611 up-regulated, 2483 down-regulated) and 7624 genes (3984 up-regulated, 3640 down-regulated). Of these, 179 genes (88 up-regulated, 91 down-regulated) were commonly expressed between treatments. After 24 h of exposure to CIT, OTA or CIT + OTA the number of DEG, respectively, was as follows: 3230 genes (1631 up-regulated, 1599 down-regulated), 8558 genes (4167 up-regulated, 4391 down-regulated), and 10,927 genes (6284 up-regulated, 4643 down-regulated). Of these, 770 genes (247 up-regulated, 523 down-regulated) were commonly expressed between treatments. The categorization of common biological functions and pathway analysis suggests that the IC₂₅ of both CIT and OTA, or their combination, induces cellular oxidative stress, a slowing of cell cycle progression, and apoptosis. Collectively, these effects contribute to inhibiting bovine macrophage proliferation.

Effects of ochratoxin A on ER stress, MAPK signaling pathway and autophagy of kidney and spleen in pigs

Ochratoxin A (OTA), a worldwide mycotoxin found in food and feeds, is a potent nephrotoxin and immunotoxin in animals and humans. This research was conducted to evaluate whether endoplasmic reticulum (ER) stress, MAPK signaling pathway and autophagy were induced by OTA in kidney and spleen of pigs. Twenty-seven crossbred pigs randomly allocated to 3 groups were fed for 42 days ad libitum a basal diet without (Con group, 0.00 μg OTA/kg) and with supplementation of OTA at 400 (OTA-L group) and 800 μg/kg (OTA-H group). From each group, 6 pigs were randomly selected for blood collection on days 0, 21, and 42 and 3 pigs were randomly selected for tissue collection on day 42. The results showed that OTA at 400 and 800 μg/kg diets significantly increased OTA concentrations in serum and kidney and spleen induced the histopathological lesions of kidney and spleen, decreased TCR-stimulated T lymphocyte viabilities and IL-2 concentration, increased TNF-α concentration, and decreased T-AOC levels. OTA increased glucose regulated protein 78, p38, and ERK1/2 phosphorylation, and LC3 II and Atg5 protein expression in kidney and spleen of pigs. These results provide new insights into the relationship between OTA and ER stress, p38 and ERK1/2 MAPK signaling pathway and autophagy in pigs.

Ochratoxin A induces nephrotoxicity and immunotoxicity through different MAPK signaling pathways in PK15 cells and porcine primary splenocytes

Ochratoxin A (OTA) is reported to be a potent nephrotoxin and immunotoxin in animals and humans. However, the mechanisms underlying OTA toxicity have not been clearly determined until now. Toxicity of OTA and its mechanism was investigated in PK15 cells and in porcine primary splenocytes. The results showed that OTA at 2.0-8.0 μg/mL for 24 h induced cytotoxicity and apoptosis in a dose-dependent manner in PK 15 cells. OTA at 0.5-4.0 μg/mL for 24 h induced cytotoxicity and apoptosis in a dose-dependent manner in porcine primary splenocytes. In addition, OTA induced p38 and ERK1/2 phosphorylation both in PK15 cells and porcine primary splenocytes. Knock-down of p38 instead of ERK by their specific siRNA significantly eliminated the nephrotoxicity induced by OTA. Contrary, knock-down of ERK1/2 instead of p38 by their specific siRNA significantly eliminated the immunotoxicity induced by OTA. The observed effects indicate that OTA induced nephrotoxicity by p38 signaling pathway in PK15 cells and immunotoxicity by ERK signaling pathway in porcine primary splenocytes.

Effect of rMnSOD on Sodium Reabsorption in Renal Proximal Tubule in Ochratoxin A-Treated Rats

Ochratoxin A (OTA) is a mycotoxin produced by Aspergillus and Penicillium that represent toxic real threat for human beings and animal health. In this study we evaluated the effect of a new recombinant mitochondrial manganese containing superoxide dismutase (rMnSOD) on oxidative stress and on the alterations of fluid reabsorption in renal proximal tubule (PT) as possible causes of OTA nephrotoxicity. Finally, we have measured the concentration of O₂^- in the kidney through dihydroethidium assay (DHE) and nitric oxide (NO) concentration through nitrites and nitrates assay. Male Sprague Dawley rats weighing 120-150 g were treated for 14 days by gavage, as follows: Control group, 12 rats received a corresponding amount of saline solution (including 10% DMSO); rMnSOD group, 12 rats treated with rMnSOD (10 µg/kg bw); OTA group, 12 rats treated with OTA (0.5 mg/kg bw) dissolved in 10% DMSO and then scaled to required volume with corn oil; rMnSOD + OTA, 12 rats treated with rMnSOD (10 µg/kg bw) plus OTA (0.5 mg/kg bw). Our results have shown that rMnSOD restores the alteration of reabsorption in PT in rats treated with OTA plus rMnSOD, probably through the response to pressure natriuresis, where nitric oxide plays a key role. Moreover, rMnSOD prevents the nephrotoxicity induced by OTA probably restoring the balance between superoxide and NO that is most probably the cause of hypertension and renal functional alterations through the inhibition of NO synthase. In conclusion these data provide important information for understanding of mechanism of toxic action of OTA. J. Cell. Biochem. 119: 424-430, 2018. © 2017 Wiley Periodicals, Inc.

Lycopene restores trace element levels in ochratoxin A-treated rats

This study was designed to investigate the in vivo effects of ochratoxin A (OTA) and/or lycopene on the levels of selenium, zinc, and copper in the liver, kidneys, and testes of male Sprague-Dawley rats. The rats were treated with OTA (0.5 mg kg-1 day-1) and/or lycopene (5 mg kg-1 day-1) by gavage for 7 or 14 days. Trace element levels were measured by atomic absorption spectrometry. OTA significantly lowered selenium (20 % in the liver, 17 % in the kidney, and 40 % in the testis), zinc (24 % in the liver, 23 % in the kidney, and 26 % in the testis), and copper levels (40 % in the liver and 10 % in the kidney). Lycopene alone did not affect the trace element levels in any of the organs. In combination with OTA, however, it significantly restored liver, kidney, and testis selenium and zinc levels compared to the group treated with OTA alone. Our results have confirmed that depletion of trace elements in different organs is one of the mechanisms of action of OTA. They also suggest that lycopene interferes with this depleting effect and restores trace element levels, the implications of which need to be further investigated.

Oral Exposure to Atrazine Induces Oxidative Stress and Calcium Homeostasis Disruption in Spleen of Mice

The widely used herbicide atrazine (ATR) can cause many adverse effects including immunotoxicity, but the underlying mechanisms are not fully understood. The current study investigated the role of oxidative stress and calcium homeostasis in ATR-induced immunotoxicity in mice. ATR at doses of 0, 100, 200, or 400 mg/kg body weight was administered to Balb/c mice daily for 21 days by oral gavage. The studies performed 24 hr after the final exposure showed that ATR could induce the generation of reactive oxygen species in the spleen of the mice, increase the level of advanced oxidation protein product (AOPP) in the host serum, and cause the depletion of reduced glutathione in the serum, each in a dose-related manner. In addition, DNA damage was observed in isolated splenocytes as evidenced by increase in DNA comet tail formation. ATR exposure also caused increases in intracellular Ca²⁺ within splenocytes. Moreover, ATR treatment led to increased expression of genes for some antioxidant enzymes, such as HO-1 and Gpx1, as well as increased expression of NF-κB and Ref-1 proteins in the spleen. In conclusion, it appears that oxidative stress and disruptions in calcium homeostasis might play an important role in the induction of immunotoxicity in mice by ATR.

Ochratoxin A activates neutrophils and kills these cells through necrosis, an effect eliminated through its conversion into ochratoxin α

Ochratoxin A (OTA) is a mycotoxin produced by several species of fungi from the Aspergillus and Penicillium genera that frequently grow in improperly stored food products. OTA has carcinogenic, teratogenic and nephrotoxic potential and sustains a high half-life in human blood. Despite the recently efforts to decontaminate OTA through its conversion into its metabolite ochratoxin alpha (OTα), there are just a few reports in literature comparing the toxic effects of these toxins. Thus, herein we studied and compared the proinflammatory and toxicological effects of OTA and its metabolite OTα in human neutrophils in vitro. The effect of OTA and OTα on human neutrophils viability was evaluated by trypan blue, annexin-V and propidium iodide methods as well as by the analysis of cytomorphological alterations. The ATP levels were also evaluated using the luciferin-luciferase bioluminescence assay. The alteration on mitochondrial potential was assessed by a mitoscreen flow cytometry mitochondrial membrane potential detection kit and the intracellular calcium levels through the probe FLUO-4/AM. To study the human neutrophils' oxidative burst, the fluorescent probe dichlorodihydrofluorescein diacetate was used. OTA induced an increase on the intracellular calcium, human neutrophils' oxidative burst followed by depletion of ATP levels and alterations on mitochondrial potential leading to cell death by necrosis, while OTα did not induce significant toxic effects. Our results strongly suggest that the toxicity in human neutrophils induced by OTA started with the release of calcium from internal stores triggering several neutrophils' activities that culminate in cell death by necrosis.

Cytotoxic Effects of Ochratoxin A in Neuro-2a Cells: Role of Oxidative Stress Evidenced by N-acetylcysteine

Ochratoxin-A (OTA), is toxic secondary metabolite and is found to be a source of vast range of toxic effects like hepatotoxicity, nephrotoxicity. However, the information available currently regarding neurotoxic effects exerted by OTA is scanty. Hence, the present study was aimed to evaluate the neurotoxic effects of OTA and the possible mechanisms of toxicity as well as the role of cytotoxic oxidative stress on neuronal (Neuro-2a) cell line was evaluated in vitro. Results of the MTT and LDH assay showed that, OTA induced dose-dependent cell death in Neuro-2a cells and EC50 value was determined as 500 nM. OTA induced high levels of reactive oxygen species (ROS) and elevated levels of malondialdehyde, also loss of mitochondrial membrane potential was observed in a dose depended manner. Effects of OTA on ROS induced chromosomal DNA damage was assessed by Comet assay and plasmid DNA damage assay in which increase in DNA damage was observed in Neuro-2a cells by increasing the OTA concentration. Further western blotting analysis of OTA treated Neuro-2a cells indicated elevated expression levels of c-Jun, JNK3 and cleaved caspase-3 leading to apoptotic cell death. Other hand realtime-Q-PCR analysis clearly indicates the suppressed expression of neuronal biomarker genes including AChE, BDNF, TH and NOS2. Further N-acetylcysteine (NAC) pretreatment to Neuro-2a cells followed by OTA treatment clearly evidenced that, the significant reversal of toxic effects exerted by OTA on Neuro-2a cells. In the present study, results illustrate that ROS a principle event in oxidative stress was elevated by OTA toxicity in Neuro-2a cells. However, further in vivo, animal studies are in need to conclude the present study reports and the use of NAC as a remedy for OTA induced neuronal stress.

Toxicity study of ochratoxin A using HEK293 and HepG2 cell lines based on microRNA profiling

Ochratoxin A (OTA) induced DNA damage, cytotoxicity, and apoptosis in mammalian cell lines. Micro RNAs (miRNAs) are involved in physiological and developmental processes and contribute to cancer development and progression. In our study, high-throughput miRNA profiling and Kyoto Encyclopedia of Genes and Genomes analysis were applied to comparatively study the toxicity of OTA in HEK293 cells and HepG2 cells treated with 25 μM OTA for 24 h. In these two cells, the same changing miRNAs were mostly related to signal transduction pathways, whereas the different changing miRNAs were mostly related to human cancer pathways. DGCR8, Dicer1, and Drosha were significantly suppressed in HEK293 cells, indicating an impairment of miRNA biogenesis. The damage seemed more extensive in HEK293 cells. Cell models and in vivo models were also compared. Many miRNAs in vitro were markedly different from those in vivo; however, OTA toxicity was observed both in vitro and in vivo. The classification of deregulated pathways is similar. The biogenesis of miRNA was impaired in both lines. In conclusion, deregulated miRNAs in vitro are mostly related to human cancer and signal transduction pathways. The deregulated pathways in vivo are similar to those in vitro.

Quercetin protects human peripheral blood mononuclear cells from OTA-induced oxidative stress, genotoxicity, and inflammation

Ochratoxin A (OTA) is one of the most abundant food-contaminating mycotoxins world wide, and is detrimental to human and animal health. This study evaluated the protective effect of quercetin against OTA-induced cytotoxicity, genotoxicity, and inflammatory response in lymphocytes. Cytotoxicity determined by MTT assay revealed IC20 value of OTA to be 20 µM, which was restored to near control values by pretreatment with quercetin. Oxidative stress parameters such as antioxidant enzymes, LPO and PCC levels indicated that quercetin exerted a protective effect on OTA-induced oxidative stress. Quercetin exerted an antigenotoxic effect on OTA-induced genotoxicity, by significantly reducing the number of structural aberrations in chromosomes and comet parameters like, % olive tail moment from 2.76 ± 0.02 to 0.56 ± 0.02 and % tail DNA from 56.23 ± 2.56 to 12.36 ± 0.56 as determined by comet assay. OTA-induced NO, TNF-α, IL-6, and IL-8 were significantly reduced in the quercetin pretreated samples indicating its anti-inflammatory role. Our results demonstrate for the first time that quercetin exerts a cytoprotective effect against OTA-induced oxidative stress, genotoxicity, and inflammation in lymphocytes. © 2014 Wiley Periodicals, Inc. Environ Toxicol 31: 855-865, 2016.

Cytotoxicity, apoptosis, DNA damage and methylation in mammary and kidney epithelial cell lines exposed to ochratoxin A

This study aimed to investigate the in vitro damage induced by ochratoxin A (OTA) in BME-UV1 and MDCK epithelial cells. Both cells lines were treated with OTA (0 up to 10 μg/mL), and cell viability (MTT assay), membrane stability (lactate dehydrogenase (LDH) release assay) and apoptotic cell rate (Tunel assay) were investigated. Further, the effect of the incubation with OTA has been evaluated at DNA level by the determination of DNA integrity, by the quantification of DNA adduct formation (8-hydroxy-2'-deoxyguanosine (8-OHdG)) and by the assessment of the global DNA methylation status (5-methyl-cytosine (5-mC)). The obtained results showed that after 24 h of OTA treatment, BME-UV1 cell viability was reduced in a dose-dependent way. OTA significantly (P < 0.05) increased LDH release in BME-UV1 cells at all concentrations tested. OTA (1.25 μg/mL) induced 35 % LDH release in MDCK cells (P < 0.05). A significant (P < 0.05) change in percentages of apoptotic BME-UV1 (10 ± 0.86) and MDCK (25 ± 0.88) cells was calculated when the cells were co-incubated with OTA. The level of 8-OHdG adduct formation was significantly (P < 0.05) increased in BME-UV1 cells treated with 1.25 μg/mL of OTA. The results of the present study suggest that a different mechanism of action may occur in these cell lines. Graphical abstract Study results overview.

Ochratoxin A: Molecular Interactions, Mechanisms of Toxicity and Prevention at the Molecular Level

Ochratoxin A (OTA) is a widely-spread mycotoxin all over the world causing major health risks. The focus of the present review is on the molecular and cellular interactions of OTA. In order to get better insight into the mechanism of its toxicity and on the several attempts made for prevention or attenuation of its toxic action, a detailed description is given on chemistry and toxicokinetics of this mycotoxin. The mode of action of OTA is not clearly understood yet, and seems to be very complex. Inhibition of protein synthesis and energy production, induction of oxidative stress, DNA adduct formation, as well as apoptosis/necrosis and cell cycle arrest are possibly involved in its toxic action. Since OTA binds very strongly to human and animal albumin, a major emphasis is done regarding OTA-albumin interaction. Displacement of OTA from albumin by drugs and by natural flavonoids are discussed in detail, hypothesizing their potentially beneficial effect in order to prevent or attenuate the OTA-induced toxic consequences.

Phenolic acid protects of renal damage induced by ochratoxin A in a 28-days-oral treatment in rats

The present study aimed to characterize the chlorogenic acid (ChlA) capacity to reverse the toxic effects induced by ochratoxin A (OTA) in a subacute toxicity test in rats. Male Wistar rats were fed orally by gavage for 28 days with OTA (0.4mg/kg bw/day), ChlA (5mg/kg bw/day) or the combination OTA (0.4mg/kg bw/day)+ChlA (5mg/kg bw/day). No deaths, no decrease in feed intake or body weight in any experimental group were recorded. The negative control group and the animals treated with ChlA alone showed no changes in any parameters evaluated. In OTA-treated group significant changes such as decrease in urine volume, proteinuria, occult blood, increase in serum creatinine values; decrease in absolute and relative kidney weight and characteristics histopathological lesions that indicated kidney damage were observed. However, limited effect on oxidative stress parameters were detected in kidneys of OTA-treated group. Animals treated with the combination OTA+ChlA were showed as negative control group in the evaluation of several parameters of toxicity. In conclusion, ChlA, at given concentration, improved biochemical parameters altered in urine and serum and pathological damages in kidneys induced by OTA exposure, showing a good protective activity, but not by an apparent antioxidant mechanism.