Ochratoxin A-mediated DNA and protein damage: roles of nitrosative and oxidative stresses

Ochratoxin A triggers endoplasmic reticulum stress through PERK/NRF2 signaling and DNA damage during early embryonic developmental competence in pigs

Ochratoxin A (OTA), a mycotoxin found in foods, has a deleterious effect on female reproduction owing to its endocrine-disrupting activity mediated through endoplasmic reticulum (ER) stress and reactive oxygen species (ROS) production. However, the mechanisms of OTA-induced ER stress in pig embryos during in vitro culture (IVC) are not yet fully understood. In the present study, porcine embryos were cultured for two days in an IVC medium supplemented with 0.5, 1.0, and 5.0 μM OTA, which led to an OTA-induced reduction in the developmental rate of blastocysts. The mRNA-seq transcriptome analysis revealed that the reduced blastocyst development ability of OTA-exposed porcine embryos was caused by ER stress, ultimately resulting in the accumulation of ROS and the occurrence of apoptosis. The expression levels of some UPR/PERK signaling-related genes (DDIT3, EIF2AK3, EIF2S1, NFE2L2, ATF4, EIF2A, and KEAP1) were found to differ in OTA-exposed pig embryos. OTA induces DNA damage by triggering an increase in RAD51/γ-H2AX levels and suppressing p-NRF2 activity. This effect is mediated through intracellular ROS and superoxide accumulation in the nuclei of porcine embryos. The cytotoxicity of OTA increased the activation of the PERK signal pathways (p-PERK, PERK, p-eIF2α, eIF2α, ATF4, and CHOP) in porcine embryos, with abnormal distribution of the ER observed around the nucleus. Collectively, our findings indicate that ER stress is a major cause of decline in the development of porcine embryos exposed to OTA. Therefore, OTA exposure induces ER stress and DNA damage via oxidative stress by disrupting PERK/NRF2 signaling activity in the developmental competence of porcine embryos during IVC.

Selenomethionine attenuates ochratoxin A-induced small intestinal injury in rabbits by activating the Nrf2 pathway and inhibiting NF-κB activation

The aim of this study was to investigate whether selenomethionine (SeMet) could attenuate intestinal injury in rabbits induced by ochratoxin A (OTA). Sixty 35-day-old IRA rabbits with similar weights were randomly assigned to the control group, OTA group (0.2 mg OTA/kg b.w), OTA+ 0.2 mg/kg Se (0.2 mg OTA/kg b.w + 0.2 mg SeMet/kg feed), OTA+ 0.4 mg/kg Se (0.2 mg OTA/kg b.w + 0.4 mg SeMet/kg feed) and OTA+ 0.6 mg/kg Se (0.2 mg OTA/kg b.w + 0.6 mg SeMet/kg feed). The rabbits were examined after oral administration of different doses of SeMet for 21 days and were intragastrically administered OTA for 7 consecutive days. The results showed that pretreatment with different doses of SeMet protected against the changes in serum biochemical indicators and the decline in production performance caused by OTA exposure. In addition, the activities of SOD, GSH-PX and T-AOC were significantly increased, and the levels of MDA and ROS were decreased after SeMet pretreatment; thus, oxidative damage in rabbit jejunum tissue due to OTA exposure was inhibited. SeMet stimulates Nrf2 and inhibits the NF-κB signalling pathway; the anti-inflammatory response and antioxidative stress in rabbits were improved, and the intestinal barrier damage caused by OTA exposure was improved. In summary, SeMet alleviates OTA-induced intestinal toxicity in rabbits by activating the Nrf2 pathway and inhibiting NF-κB activation. Moreover, 0.4 mg/kg SeMet induced the most significant improvement.

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.

In-vitro alleviation of ochratoxin a mediated cytotoxicity using N-acetyl-L-tryptophan glucoside pretreatment

AIMS

Ochratoxin A (OTA) has been reported to exhibit nephrotoxicity through induction of cell redox homeostasis perturbation, mitochondrial hyperpolarization and depolarization, protein synthesis inhibition, apoptosis, etc. In the present examination, the protective efficiency of novel synthesized molecule, N-acetyl-L-Tryptophan glucoside (NATG) towards OTA prompted toxicity was evaluated using Human Embryonic Kidney (HEK-293) cells.

MAIN METHODS & KEY FINDINGS

The cells were treated with NATG (0-200 μg/ml) before OTA treatment (0-20 μg/ml) the and protection efficiency of NATG was evaluated using MTT and SRB assay. OTA-induced intracellular ROS and its inhibition via NATG (10 μg/ml) pre-treatment was evaluated using the 2',7'-dichlorodihydrofluorescein diacetate (H₂DCFDA) probe. Protective effects of NATG pre-treatment on OTA treated cells had been evaluated in terms of oxidative stress, cell cycle perturbations, mitochondrial membrane disturbance and apoptotic modulation through flowcytometry. Results of the study demonstrated that NATG provides significant protection to HEK -293 cells against OTA induced toxicity primarily by reducing oxidative stress, maintaining mitochondrial membrane homeostasis and inhibiting apoptosis. Furthermore, molecular docking study demonstrated that NATG may efficiently bind with OTA binding pocket on phenylalanyl t-RNA synthetase, resulting in inhibiting OTA incorporation within the newly synthesized peptides and therefore may ameliorate OTA mediated protein synthesis inhibition.

SIGNIFICANCE

Present study demonstrated a significant protective efficacy of N acetyl-L- tryptophan glucoside (NATG) against OTA induced toxicity in HEK -293 cells. In future, NATG can be developed as a potential protective agent against OTA induced toxicity in humans.

Protective Effect of SeMet on Liver Injury Induced by Ochratoxin A in Rabbits

Ochratoxin A (OTA) is second only to aflatoxin in toxicity among mycotoxins. Recent studies have shown that selenomethionine (SeMet) has a protective effect on mycotoxin-induced toxicity. The purpose of this study was to investigate the protective effect and mechanism of SeMet on OTA-induced liver injury in rabbits. Sixty 35-day-old rabbits with similar body weight were randomly divided into five groups: control group, OTA group (0.2 mg/kg OTA), OTA + 0.2 mg/kg SeMet group, OTA + 0.4 mg/kg SeMet group and OTA + 0.6 mg/kg SeMet group. Rabbits were fed different doses of the SeMet diet for 21 d, and OTA was administered for one week from day 15 (the control group was provided the same dose of NaHCO3 solution). The results showed that 0.4 mg/kg SeMet could significantly improve the liver injury induced by OTA poisoning. SeMet supplementation can improve the changes in physiological blood indexes caused by OTA poisoning in rabbits and alleviate pathological damage to the rabbit liver. SeMet also increased the activities of SOD, GSH-Px and T-AOC and significantly decreased the contents of ROS, MDA, IL-1β, IL-6 and TNF-α, effectively alleviating the oxidative stress and inflammatory response caused by OTA poisoning. In addition, OTA poisoning inhibits Nrf2 and HO-1 levels, ultimately leading to peroxide reaction, while SeMet activates the Nrf2 signaling pathway and enhances the expression of the HO-1 downstream Nrf2 gene. These results suggest that Se protects the liver from OTA-induced hepatotoxicity by regulating Nrf2/HO-1 expression.

MicroRNA regulates the toxicological mechanism of four mycotoxins in vivo and in vitro

Mycotoxins can cause body poisoning and induce carcinogenesis, often with a high mortality rate. Therefore, it is of great significance to seek new targets that indicate mycotoxin activity and to diagnose and intervene in mycotoxin-induced diseases in their early stages. MicroRNAs (miRNAs) are physiological regulators whose dysregulation is closely related to the development of diseases. They are thus important markers for the occurrence and development of diseases. In this review, consideration is given to the toxicological mechanisms associated with four major mycotoxins (ochratoxin A, aflatoxin B1, deoxynivalenol, and zearalenone). The roles that miRNAs play in these mechanisms and the interactions between them and their target genes are explained, and summarize the important role of histone modifications in their toxicity. As a result, the ways that miRNAs are regulated in the pathogenicity signaling pathways are revealed which highlights the roles played by miRNAs in preventing and controlling the harmful effects of the mycotoxins. It is hoped that this review will provide a theoretical basis for the prevention and control of the damage caused by these mycotoxins.

Mycotoxins’ Toxicological Mechanisms Involving Humans, Livestock and Their Associated Health Concerns: A Review

Mycotoxins are well established toxic metabolic entities produced when fungi invade agricultural/farm produce, and this happens especially when the conditions are favourable. Exposure to mycotoxins can directly take place via the consumption of infected foods and feeds; humans can also be indirectly exposed from consuming animals fed with infected feeds. Among the hundreds of mycotoxins known to humans, around a handful have drawn the most concern because of their occurrence in food and severe effects on human health. The increasing public health importance of mycotoxins across human and livestock environments mandates the continued review of the relevant literature, especially with regard to understanding their toxicological mechanisms. In particular, our analysis of recently conducted reviews showed that the toxicological mechanisms of mycotoxins deserve additional attention to help provide enhanced understanding regarding this subject matter. For this reason, this current work reviewed the mycotoxins’ toxicological mechanisms involving humans, livestock, and their associated health concerns. In particular, we have deepened our understanding about how the mycotoxins’ toxicological mechanisms impact on the human cellular genome. Along with the significance of mycotoxin toxicities and their toxicological mechanisms, there are associated health concerns arising from exposures to these toxins, including DNA damage, kidney damage, DNA/RNA mutations, growth impairment in children, gene modifications, and immune impairment. More needs to be done to enhance the understanding regards the mechanisms underscoring the environmental implications of mycotoxins, which can be actualized via risk assessment studies into the conditions/factors facilitating mycotoxins’ toxicities.

Prevalence of Aspergillus-Derived Mycotoxins (Ochratoxin, Aflatoxin, and Gliotoxin) and Their Distribution in the Urinalysis of ME/CFS Patients

Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is a known complex, multi-organ system disorder with a sudden or subacute onset. ME/CFS occurs most commonly among women between 30 and 50 years of age. The current diagnostic criteria of ME/CFS, as defined by the Centers for Disease Control and Prevention, includes: profound fatigue and post-exertional malaise (>6 mo) unrelieved by rest, persistent cognitive impairment or orthostatic intolerance, and chronic unrefreshing sleep. Despite reported associations between ME/CFS onset and exposure to infectious agents (viral, bacterial, or fungal), the pathophysiology of ME/CFS remains unknown. In this prevalence study, we investigated the rates of Aspergillus-derived toxin levels, Aflatoxin (AF), Ochratoxin A (OTA), and Gliotoxin (GT), in the urinalysis of 236 ME/CFS patients with a history of chronic exposure to mold (i.e., from water-damaged buildings). Among ME/CFS patients reporting chronic exposure to mold, we found evidence of exposure in 92.4 percent of patients, with OTA being the most prevalent mycotoxin. Mold distributions (OTA, AF, and GT) in the urinalysis all demonstrated right skewness, while the distribution of age of ME/CFS patients diagnosed showed no deviation from normality. This study aims to provide preliminary, epidemiological evidence among ME/CFS patients who were diagnosed in South Florida with a history of exposure to mycotoxins. Based on these findings, we proposed how future control studies should approach investigating the association between chronic mold exposure and the diagnosis of ME/CFS.

Si-Based Hydrogen-Producing Nanoagent Protects Fetuses From Miscarriage Caused by Mother-to-Child Transmission

Mother-to-child transmission of viruses and bacteria increases the risk of miscarriage and various diseases in children. Such transmissions can result in infections and diseases in infants or the induction of an inflammatory immune response through the placenta. Recently, we developed a silicon (Si)-based hydrogen-producing nanoagent (Si-based agent) that continuously and effectively produces hydrogen in the body. Since medical hydrogen has antioxidative, anti-inflammatory, antiallergic, and antiapoptotic effects, we investigated the effects of our Si-based agent on mother-to-child transmission, with a focus on the rate of miscarriage. In pregnant mice fed a diet containing the Si-based agent, lipopolysaccharide (LPS)-induced miscarriage due to mother-to-child transmission was reduced and inflammation and neutrophil infiltration in the placenta were suppressed. We also found that the Si-based agent suppressed IL-6 expression in the placenta and induced the expression of antioxidant and antiapoptotic genes, such as Hmox1 and Ptgs2. The observed anti-inflammatory effects of the Si-based agent suggest that it may be an effective preventative or therapeutic drug for miscarriage or threatened miscarriage during pregnancy by suppressing maternal inflammation caused by bacterial and viral infections.

Ochratoxin A-Induced Nephrotoxicity: Up-to-Date Evidence

Ochratoxin A (OTA) is a mycotoxin widely found in various foods and feeds that have a deleterious effect on humans and animals. It has been shown that OTA causes multiorgan toxicity, and the kidney is the main target of OTA among them. This present article aims to review recent and latest intracellular molecular interactions and signaling pathways of OTA-induced nephrotoxicity. Pyroptosis, lipotoxicity, organic anionic membrane transporter, autophagy, the ubiquitin-proteasome system, and histone acetyltransferase have been involved in the renal toxicity caused by OTA. Meanwhile, the literature reviewed the alternative or method against OTA toxicity by reducing ROS production, oxidative stress, activating the Nrf2 pathway, through using nanoparticles, a natural flavonoid, and metal supplement. The present review discloses the molecular mechanism of OTA-induced nephrotoxicity, providing opinions and strategies against OTA toxicity.

Curcumin Modulates Nitrosative Stress, Inflammation, and DNA Damage and Protects against Ochratoxin A-Induced Hepatotoxicity and Nephrotoxicity in Rats

Ochratoxin A (OTA) is a fungal toxin of critical concern for food safety both for human health and several animal species, also representing a cancer threat to humans. Curcumin (CURC) is a natural polyphenol that has anti-apoptotic, anti-inflammatory, and antioxidant effects. The aim of this study was to investigate the cytoprotective effect of CURC against OTA-induced nephrotoxicity and hepatotoxicity through the study of the nitrosative stress, pro-inflammatory cytokines, and deoxyribonucleic acid (DNA) damage. Sprague Dawley rats were daily treated with CURC (100 mg/kg b.w.), OTA (0.5 mg/kg b.w), or CURC with OTA by oral gavage for 14 days. Our results demonstrated that OTA exposure was associated with significant increase of pro-inflammatory and DNA oxidative-damage biomarkers. Moreover, OTA induced the inducible nitric oxide synthase, (iNOS) resulting in increased nitric oxide (NO) levels both in kidney and liver. The co-treatment OTA + CURC counteracted the harmful effects of chronic OTA treatment by regulating inflammation, reducing NO levels and oxidative DNA damage in kidney and liver tissues. Histology revealed that OTA + CURC treatment determinates mainly an Iba1+ macrophagic infiltration with fewer CD3+ T-lymphocytes in the tissues. In conclusion, we evidenced that CURC exerted cytoprotective and antioxidant activities against OTA-induced toxicity in rats.

Ochratoxin A Induces Oxidative Stress in HepG2 Cells by Impairing the Gene Expression of Antioxidant Enzymes

Ochratoxin A (OTA) is a mycotoxin frequently found in raw and processed foods. While it is considered a possible human carcinogen, the mechanism of action remains unclear. OTA has been shown to be hepatotoxic in both in vitro and in vivo models and oxidative stress may be one of the factors contributing to its toxicity. Hence, the effect of OTA on human hepatocellular carcinoma, HepG2 cells, was investigated on oxidative stress parameters. The cytotoxicity of OTA on HepG2 was time- and dose-dependent within a range between 0.1 and 10 µM; while 100 μM of OTA increased the intracellular reactive oxygen species (ROS) in a time-dependent manner. Additionally, the levels of glutathione (GSH) were increased by 9.7% and 11.3% at 10 and 100 nM of OTA, respectively; while OTA at 100 μM depleted GSH by 40.5% after 24 h exposure compared with the control. Finally, the mRNA level of catalase (CAT) was downregulated by 2.33-, 1.92-, and 1.82-fold after cells were treated with 1, 10, and 10 μM OTA for 24 h, respectively; which was linked to a decrease in CAT enzymatic activity. These results suggest that oxidative stress is involved in OTA-mediated toxicity in HepG2 cells.

Protection against acute renal injury by naturally occurring medicines which act through Nrf2 signaling pathway

The cellular defense pathway plays a key role in maintaining the homeostasis, tissues and organisms. Nuclear factor E2-related factor 2 (Nrf2), as a key cell signaling pathway, plays an important role in encoding detoxification enzymes and other stress response mediators. Recent studies have shown that it is closely related to the prevention and treatment of acute kidney injury (AKI). Therefore, this article reviews the protective effects of Nrf2-related signaling pathways on acute kidney injury, and summarizes the strategies of natural pharmaceutical ingredients such as flavonoids, alkaloids, terpenes, phenylpropionic acid, polyphenols, and polysaccharides to prevent and treat acute kidney injury. It is of great significance to further study the relationship between Nrf2 regulated signal pathway and kidney disease and the development of new medicines for acute kidney injury treatment. It can also provide new ideas and treatment strategies for clinical treatment of acute kidney injury. PRACTICAL APPLICATIONS: This article reviewed the mechanisms by which the active ingredients of natural medicines slow down acute kidney injury through the Nrf2 pathway. It will help us to understand the regulatory role of the Nrf2 pathway in AKI more comprehensively, and provide a theoretical basis for further exploring the mechanism of more natural drugs to reduce acute kidney injury.

Role of Nrf2 and mitochondria in cancer stem cells; in carcinogenesis, tumor progression, and chemoresistance

Cancer stem cells (CSCs) are rare sub-population in tumor mass with self-renewal and differentiation abilities; CSCs are considered as the main cells which are responsible for tumor metastasis, cancer recurrence, and chemo/radio-resistance. CSCs are believed to contain low mitochondria in quantity, high concentration of nuclear factor erythroid 2-related factor 2 (Nrf2), and low reactive oxygen species (ROS) levels. Mitochondria regulate certain cellular functions, including controlling of cellular energetics, calcium signaling, cell growth and cell differentiation, cell cycle regulation, and cell death. Also, mitochondria are the main sources of intrinsic ROS production. Dysfunction of CSCs mitochondria due to oxidative phosphorylation is reported in several pathological conditions, including metabolic disorders, age-related diseases, and various types of cancers. ROS levels play a significant role in cellular signal transduction and CSCs' identity and differentiation capability. Nrf2 is a master transcription factor that plays critical functions in maintaining cellular redox hemostasis by regulating several antioxidant and detoxification pathways. Recently, the critical function of Nrf2 in CSCs has been revealed by several studies. Nrf2 is an essential molecule in the maintenance of CSCs' stemness and self-renewal in response to different oxidative stresses such as chemotherapy-induced elevation of ROS. Nrf2 enables these cells to recover from chemotherapy damages, and promotes establishment of invasion and dissemination. In this study, we have summarized the role of Nrf2 and mitochondria function CSCs, which promote cancer development. The significant role of Nrf2 in the regulation of mitochondrial function and ROS levels suggests this molecule as a potential target to eradicate CSCs.

Ochratoxin A presence in Cabernet Sauvignon wine changes antioxidant activity in vitro and oxidative stress markers in vivo

Ochratoxin A (OTA) is a mycotoxin found in grape products and oxidative stress has been reported as an important mechanism involved in its toxicity, classified as possible carcinogenic to humans. Conversely, phenolics are known bioactive compounds in grapes and display great antioxidant properties. However, the biological effects of the concomitant presence of phenolic compounds and OTA remains unclear. The aim of this study was to evaluate, for the first time, the effect of OTA presence in Cabernet Sauvignon wine on antioxidant activity in vitro and on oxidative stress markers in vivo. In addition, the phenolic composition of wine was evaluated by LC-DAD-MS/MS. In vitro assays were based on spectrophotometric methods, while in vivo assays were performed evaluating oxidative stress markers in the nematode Caenorhabditis elegans, an alternative model to animal testing. A total of 23 phenolic compounds were identified in the Cabernet sauvignon red wine, including the anthocyanins delphinidin-3-O-glicoside and malvidin-3-O-glicoside, the flavonol quercetin-3-O-glucuronide and the phenolic acids caffeic, verbascoside and caftaric. Trans-resveratrol and trans-piceid were the only stilbenes found in the samples. OTA presence in the red wine was accompanied by reduction in GSH content and increase in hydroxyl radical generation in vitro. The presence of OTA in wine also increased lipoperoxidation and induced overexpression of the antioxidant enzymes superoxide dismutase and catalase in vivo. This study demonstrates that OTA presence in red wine can reduce its antioxidant potential in vitro and induces oxidative stress in vivo, without affecting the phenolic compounds levels in the samples. Thus, this work provides insights into the negative effects of the presence of OTA in wine, not only by its known toxicity, but also by prejudicing the antioxidant potential of wine. It is important to be aware of these effects when developing a complete description of OTA toxicity in humans.

Effects of Ochratoxin A exposure on DNA damage in porcine granulosa cells in vitro

Ochratoxin A (OTA), a feed mycotoxin, tends to impair the reproductive performance of animals. Our previous studies have demonstrated that OTA exposure inhibits porcine ovarian granulosa cell (GC) proliferation and induces their apoptosis, but the underlying toxic mechanism is still uncertain. In this study, we explored the OTA exposure on porcine GCs in vitro and found that OTA exposure inhibited the proliferation of porcine GCs and arrested cell cycle of GCs in the G2/M phase. The results based on RNA-Seq revealed that 20 μM and 40 μM OTA exposure increase DNA damage of porcine GCs in vitro. The differentially expressed genes (DEGs) of 40 μM OTA exposure were enriched in the pathways of mismatch repair, nucleotide excision repair and homologous recombination in DNA replication compared with control group and 20 μM OTA exposure group. Meanwhile, OTA exposure increased the expression levels of DNA double-strand breaks (DSBs) gene γ-H2AX, and DNA repair related genes, such as BRCA1, XRCC1, PARP1, and RAD51. Above all, our research revealed that OTA might exert deleterious effects on porcine ovarian GCs, influencing DNA repair-related biological processes and causing DNA damage response.

EFSA Panel on Contaminants in the Food Chain (CONTAM), Schrenk D, Bodin L, Chipman JK, del Mazo J, Grasl‐Kraupp B, Hogstrand C, Hoogenboom L(R, Leblanc J, Nebbia CS, Nielsen E, Ntzani E, Petersen A, Sand S, Schwerdtle T, Vleminckx C, Wallace H, Alexander J, Dall'Asta C, Mally A, Metzler M, Binaglia M, Horváth Z, Steinkellner H, Bignami M. 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.

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.

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

The purpose of this study was to investigate the protective effect and mechanism of yeast selenium (Se-Y) on ochratoxin- (OTA-) induced nephrotoxicity of chickens. A total of 80 one-day-old healthy chickens were randomly divided into 4 equal groups: control, OTA (50 μg/kg OTA), Se-Y (0.4 mg/kg Se-Y), and OTA+Se-Y (50 μg/kg OTA+0.4 mg/kg Se-Y). In the OTA chickens, differences in body weight, kidney coefficient, biochemical histological analysis, antioxidant capability, and the expression levels of the PI3K/AKT and Nrf2/Keap1 signaling pathway-related genes were observed. The levels of total superoxide dismutase (T-SOD), antioxidant capacity (T-AOC), catalase (CAT), and glutathione (T-GSH) significantly decreased, but the malondialdehyde (MDA) level of the kidneys significantly increased in the OTA treatment group. More importantly, treatment with Se-Y improved the antioxidant enzyme activities within the kidneys of chickens exposed to OTA. In addition, administration of OTA resulted in apoptosis and was associated with decreased expression of AKT, PI3K, and Bcl-2, which in turn enhanced expression of Caspase3, Bax, and P53. However, Se-Y improved the antioxidant defense system through activation of the Nrf2/Keap1 signaling pathway. Gene expression of Nrf2 and its target genes (HO-1, GSH-px, GLRX2, MnSOD, and CAT) was downregulated following OTA exposure. Conversely, Se-Y treatment resulted in a significant upregulation of the same genes. Besides, significant downregulations of protein expression of HO-1, CAT, MnSOD, Nrf2, and Bcl-2 and a significant upregulation of Caspase3 and Bax levels were observed after contaminated with OTA. Notably, OTA-induced apoptosis and oxidative damage in the kidney of chickens were reverted back to normal level in the OTA+Se-Y group. Taken together, the data suggest that Se-Y alleviates OTA-induced nephrotoxicity in chickens, possibly through the activation of the PI3K/AKT and Nrf2/Keap1 signaling pathways.

Amelioration of ochratoxin-A induced cytotoxicity by prophylactic treatment of N-Acetyl-L-Tryptophan in human embryonic kidney cells

Ochratoxin A (OTA) is known to induce nephro-toxicity via induction of cellular redox homeostasis perturbation, mitochondrial hyperpolarisation and depolarization, protein synthesis inhibition leading to apoptosis. In the present study, protective efficacy of N-Acetyl-L-Tryptophan (NAT) against OTA induced toxicity was evaluated using Human Embryonic Kidney (HEK-293) cells. Cells were treated with NAT (0-200 μg/ml) before OTA treatment (0-20 μg/ml) and protective efficacy of NAT was evaluated using MTT and SRB assay. OTA-induced intracellular ROS generation and its inhibition by NAT (2.5 μg/ml) pre-treatment was evaluated using 2',7'-dichlorodihydrofluorescein diacetate (H₂DCFDA) probe. Effects of NAT pre-treatment on OTA treated cells were also evaluated in terms of cell cycle perturbations and mitochondrial membrane potential disturbance using flowcytometry. Results of the study demonstrated significant (∼89 % cell growth in comparison to 50% in OTA alone group; P < 0.05) protection by NAT to the HEK-293 cells against OTA mediated cell death in terms of cell viability. Further, significant reduction in ROS levels and mitochondrial membrane potential disturbance was also observed in NAT pre-treated plus OTA cells as compared to only OTA treated cells. Significant (p < 0.05) arrest in G0 and S phase of cell cycle was observed in OTA treated cells that was found to be inhibited by NAT pre-treatment to OTA treated cells. Also, molecular docking analysis demonstrated higher probability of NAT to bind with OTA binding pocket on phenylalanyl t-RNA synthetase, resulting in inhibition of OTA incorporation in the newly synthesized peptides and thus may ameliorate OTA induced protein synthesis inhibition. Conclusively, present study suggested that NAT offers protection against OTA toxicity in HEK-293 cells by counterbalancing oxidative stress, cell cycle regulation, mitochondrial membrane potential stabilization, protein synthesis inhibition and cell death retardation.

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.

PCV2 infection aggravates ochratoxin A-induced nephrotoxicity via autophagy involving p38 signaling pathway in vivo and in vitro

Ochratoxin A (OTA) is reported to induce nephrotoxicity in animals and humans. Porcine circovirus type 2 (PCV2) could induce porcine dermatitis and nephropathy syndrome. To date, little is known whether virus infection aggravates mycotoxin-induced toxicity. This work aimed to study the effects of PCV2 infection on OTA-induced nephrotoxicity and its mechanism in vivo and vitro. The results in vivo showed that PCV2 infection aggravated OTA-induced poor growth performance, nephrotoxicity, p38 phosphorylation and autophagy as demonstrated by Atg5, LC3 II and p62 protein expressions in kidney of pigs. The results in vitro indicated that PCV2 infection significantly aggravated OTA-induced nephrotoxicity as demonstrated by cell viabilities, annexin V/PI binding and caspase 3 activities, and induced p38 phosphorylation and autophagy in PK15 cells. p38 inhibitor decreased Atg5 and LC3 protein expression induced by PCV2 infection and OTA combined treatment. Adding autophagy inhibitor 3-MA or CQ alleviated the aggravating effects of PCV2 infection on OTA-induced nephrotoxicity. Atg5-specific siRNA eliminated the aggravating effects of PCV2 infection on OTA-induced nephrotoxicity. Taken together, these data indicate that in vivo and in vitro PCV2 infection aggravated OTA-induced nephrotoxicity via p38-mediated autophagy.

European contribution to the study of ROS: A summary of the findings and prospects for the future from the COST action BM1203 (EU-ROS)

The European Cooperation in Science and Technology (COST) provides an ideal framework to establish multi-disciplinary research networks. COST Action BM1203 (EU-ROS) represents a consortium of researchers from different disciplines who are dedicated to providing new insights and tools for better understanding redox biology and medicine and, in the long run, to finding new therapeutic strategies to target dysregulated redox processes in various diseases. This report highlights the major achievements of EU-ROS as well as research updates and new perspectives arising from its members. The EU-ROS consortium comprised more than 140 active members who worked together for four years on the topics briefly described below. The formation of reactive oxygen and nitrogen species (RONS) is an established hallmark of our aerobic environment and metabolism but RONS also act as messengers via redox regulation of essential cellular processes. The fact that many diseases have been found to be associated with oxidative stress established the theory of oxidative stress as a trigger of diseases that can be corrected by antioxidant therapy. However, while experimental studies support this thesis, clinical studies still generate controversial results, due to complex pathophysiology of oxidative stress in humans. For future improvement of antioxidant therapy and better understanding of redox-associated disease progression detailed knowledge on the sources and targets of RONS formation and discrimination of their detrimental or beneficial roles is required. In order to advance this important area of biology and medicine, highly synergistic approaches combining a variety of diverse and contrasting disciplines are needed.

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.

A Review: Epigenetic Mechanism in Ochratoxin A Toxicity Studies

Ochratoxin A (OTA) is a natural contaminant that has displayed nephrotoxicity and hepatotoxicity in mammals. It contaminates a great variety of foodstuffs and threatens people's lives. The molecular mechanism of OTA-induced toxicity has been studied since 1965. Moreover, epigenetic mechanisms are also studied in OTA-induced toxicity. Additionally, the mode of OTA epigenetic research has been advanced in research hotspots. However, there is still no epigenetic study of OTA-induced toxicity. In this review, we discuss the relationship between these epigenetic mechanisms and OTA-induced toxicity. We found that studies on the epigenetic mechanisms of OTA-induced toxicity all chose the whole kidney or liver as the model, which cannot reveal the real change in DNA methylation or miRNAs or histone in the target sites of OTA. Our recommendations are as follows: (1) the specific target site of OTA should be detected by advanced technologies; and (2) competing endogenous RNAs (ceRNA) should be explored with OTA.

PRESENCE OF CITRININ IN GRAINS AND ITS POSSIBLE HEALTH EFFECTS

Background:

Citrinin is a mycotoxin produced by several species of the genera Aspergillus, Penicillium and Monascus and it occurs mainly in stored grain. Citrinin is generally formed after harvest and occurs mainly in stored grains, it also occurs in other plant products. Often, the co-occurrence with other mycotoxins is observed, especially ochratoxin A, which is usually associated with endemic nephropathy. At the European Union level, systematic monitoring of Citrinin in grains began with the aim of determining its highest permissible amount in food. Thus, far the systematic monitoring of the above mentioned mycotoxin in Croatia is yet to begin.

Materials and Methods:

The main goal of this study was to determine the presence of Citrinin in grains sampled in the area of Međimurje, Osijek-Baranja, Vukovar-Srijem and Brod-Posavina County. For the purpose of identification and quantification of citrinin, high performance liquid chromatograph (HPLC) with fluorescence was used (Calibration curve k > 0.999; Intra assay CV = 2.1%; Inter assay CV = 4.3%; LOQ < 1 μg/kg).

Results:

From the area of Međimurje County, 10 samples of corn and 10 samples of wheat were analyzed. None of the samples contained Citrinin (<1 μg/kg). From the area of Osijek-Baranja and Vukovar-Srijem County, 15 samples from each County were analyzed. The mean value for the samples of Osijek-Baranja County was 19.63 μg/kg (median=15.8 μg/kg), while for Vukovar-Srijem County the mean value of citrinin was 14,6 μg/kg (median=1.23 μg/kg). From 5 analyzed samples from Brod-Posavina County, one of the samples contained citrinin in the amount of 23.8 μg/kg, while the registered amounts in the other samples were <1 μg/kg.

Conclusion:

The results show that grains from several Counties contain certain amounts of Citrinin possibly indicating a significant intake of citrinin in humans. It must be stated that grains and grain-based products are the basis of everyday diet of all age groups, especially small children, where higher intake of citrinin can occur. Consequently, we emphasize the need for systematic analysis of larger amount of samples, from both large grains and small grains, especially in the area of Brod-Posavina County, in order to obtain more realistic notion of citrinin contamination of grains and to asses the health risk in humans.

Mycotoxins as human carcinogens-the IARC Monographs classification

Humans are constantly exposed to mycotoxins (e.g. aflatoxins, ochratoxins), mainly via food intake of plant and animal origin. The health risks stemming from mycotoxins may result from their toxicity, in particular their carcinogenicity. In order to prevent these risks, the International Agency for Research on Cancer (IARC) in Lyon (France)-through its IARC Monographs programme-has performed the carcinogenic hazard assessment of some mycotoxins in humans, on the basis of epidemiological data, studies of cancer in experimental animals and mechanistic studies. The present article summarizes the carcinogenic hazard assessments of those mycotoxins, especially aflatoxins (aflatoxin B1, B2, G1, G2 and M1), fumonisins (fumonisin B1 and B2) and ochratoxin A (OTA). New information regarding the genotoxicity of OTA (formation of OTA-DNA adducts), the role of OTA in oxidative stress and the identification of epigenetic factors involved in OTA carcinogenesis-should they indeed provide strong evidence that OTA carcinogenicity is mediated by a mechanism that also operates in humans-could lead to the reclassification of OTA.

An overview of chemical inhibitors of the Nrf2-ARE signaling pathway and their potential applications in cancer therapy

The Nuclear factor erythroid 2-related factor 2 (Nrf2) is a key transcription factor regulating a wide array of genes for antioxidant and detoxification enzymes in response to oxidative and xenobiotic stress. A large number of Nrf2-antioxidant response element (ARE) activators have been screened for use as chemopreventive agents in oxidative stress-related diseases and even cancer. However, constitutive activation of Nrf2 occurs in a variety of cancers. Aberrant activation of Nrf2 is correlated with cancer progression, chemoresistance, and radioresistance. In this review, we examine recent studies of Nrf2-ARE inhibitors in the context of cancer therapy. We enumerate the possible Nrf2-inhibiting mechanisms of these compounds, their effects sensitizing cancer cells to chemotherapeutic agents, and the prospect of applying them in clinical cancer therapy.

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.

Maternal-Fetal Cancer Risk Assessment of Ochratoxin A during Pregnancy

Increasing evidence has demonstrated that in utero exposure to environmental chemicals may interfere with fetal development and increase the risk of disease and cancer development later in life. Ochratoxin A (OTA) has been proven to induce diverse toxic effects including teratogenicity, carcinogenicity, immunotoxicity and potential endocrine disruption. Due to the continuous and widespread occurrence of OTA as a potential contaminant of staple foods, there is increasing concern of in utero exposure of fetus to this mycotoxin. In this study, maternal-fetal risk assessment of OTA during pregnancy was conducted using the benchmark dose approach for genotoxic carcinogens. The daily intake of OTA for Egyptian pregnant women was estimated based on their serum OTA level using the refined Klaassen equation for pregnancy. Fetal exposure level was also estimated based on the maternal data. Comparison between the estimated daily exposure and the negligible cancer risk intake (NCRI), and the calculation of margin of exposure (MOE) implicated that OTA exposure from dietary intake would be of low health concern for this general subpopulation of Egyptian women. This subpopulation of pregnant women was generally estimated not to be in high-risk for toxicity induced by OTA.

MiR-122 partly mediates the ochratoxin A-induced GC-2 cell apoptosis

Ochratoxin A (OTA) is a mycotoxin which has been shown to be nephrotoxic, hepatotoxic, and immunotoxic to animals, and mainly exists in the mildew grain. MicroRNAs (miRNAs) regulate a wide variety of cellular processes. However, the toxic effects of OTA on the germ cell and whether miRNAs mediate the effects of OTA-induced GC-2 cell apoptosis are still not clear. In the present study, OTA treatment resulted in a dose-dependent increase apoptosis in GC-2 cells. MiR-122 was increased in the OTA-treated GC-2 cells. It showed that Bcl-w was down-regulated after OTA treatment, and caspase-3 was obviously activated. Cyclin G1 (CCNG1) was significantly decreased, and inversely the expression of p53 was increased. Inhibition of miR-122 partly relieved the OTA-induced GC-2 cell apoptosis. These results indicate that OTA induces GC-2 cell apoptosis by causing the increase of caspase-3 activity and that miR-122 partly mediates the OTA-induced cell apoptosis.

Effect of Penicillium mycotoxins on the cytokine gene expression, reactive oxygen species production, and phagocytosis of bovine macrophage (BoMacs) function

Bovine macrophages (BoMacs) were exposed to the following Penicillium mycotoxins (PM): citrinin (CIT), ochratoxin A (OTA), patulin (PAT), mycophenolic acid (MPA) and penicillic acid (PA). PM exposure at the concentration that inhibits proliferation by 25% (IC25) differentially for 24h altered the gene expression of various cytokines. OTA significantly induced IL-1α expression (p<0.05), while the expression of IL-6 was suppressed (p<0.01). MPA significantly induced the expression of IL-1α (p<0.05) and reduced the expression of IL-12α (p<0.01) and IL-10 (p<0.01). PAT significantly suppressed the expression of IL-23 (p<0.01), IL-10 (p<0.05) and TGF-β (p<0.05). Some PMs also affected reactive oxygen species (ROS) and phagocytosis of Mycobacterium avium ssp. Paratuberculosis (MAP) at higher concentrations. PAT and PA for example, significantly decreased the percent phagocytosis of MAP at 5.0 (p<0.01) and 15.6 μM (p<0.01), respectively, but only PA significantly suppressed PAM-3-stimulated ROS production at 62.5 (p<0.05) and 250.0 μM (p<0.01). OTA significantly increased the percent phagocytosis of MAP at 6.3 (p<0.05) and 12.5 μM (p<0.01). These findings suggest that exposure to sub-lethal concentrations of PMs can affect macrophage function, which could affect immunoregulation and innate disease resistance to pathogens.

The Putative Role of Viruses, Bacteria, and Chronic Fungal Biotoxin Exposure in the Genesis of Intractable Fatigue Accompanied by Cognitive and Physical Disability

Patients who present with severe intractable apparently idiopathic fatigue accompanied by profound physical and or cognitive disability present a significant therapeutic challenge. The effect of psychological counseling is limited, with significant but very slight improvements in psychometric measures of fatigue and disability but no improvement on scientific measures of physical impairment compared to controls. Similarly, exercise regimes either produce significant, but practically unimportant, benefit or provoke symptom exacerbation. Many such patients are afforded the exclusionary, non-specific diagnosis of chronic fatigue syndrome if rudimentary testing fails to discover the cause of their symptoms. More sophisticated investigations often reveal the presence of a range of pathogens capable of establishing life-long infections with sophisticated immune evasion strategies, including Parvoviruses, HHV6, variants of Epstein-Barr, Cytomegalovirus, Mycoplasma, and Borrelia burgdorferi. Other patients have a history of chronic fungal or other biotoxin exposure. Herein, we explain the epigenetic factors that may render such individuals susceptible to the chronic pathology induced by such agents, how such agents induce pathology, and, indeed, how such pathology can persist and even amplify even when infections have cleared or when biotoxin exposure has ceased. The presence of active, reactivated, or even latent Herpes virus could be a potential source of intractable fatigue accompanied by profound physical and or cognitive disability in some patients, and the same may be true of persistent Parvovirus B12 and mycoplasma infection. A history of chronic mold exposure is a feasible explanation for such symptoms, as is the presence of B. burgdorferi. The complex tropism, life cycles, genetic variability, and low titer of many of these pathogens makes their detection in blood a challenge. Examination of lymphoid tissue or CSF in such circumstances may be warranted.

Mycotoxigenic moulds and mycotoxins in flours consumed in Turkey

BACKGROUND

Aflatoxins (AFs) and ochratoxin A (OTA) are metabolites produced by several fungi of the genera Aspergillus and Penicillium and have been found to contaminate human foods and animal feeds. The aim of this study was to investigate the abundance and diversity of total microfungi and mycotoxigenic fungi in 25 samples of different grain-based flours from four regions of Turkey (Thrace and Central, Northwest and West Anatolia) and to evaluate the level of AF and OTA contamination. Microscopic and polymerase chain reaction analyses were used to identify fungi, while high-performance liquid chromatography was used for the detection of AFs and OTA.

RESULTS

A total of 551 fungal strains were obtained from the samples and identified morphologically and by multi-locus gene sequencing. All samples were contaminated with fungi ((2-4.8) × 10(4) colony-forming units g(-1) ) and three of them exceeded the European Commission (EC) limits. The data also revealed that 70.5 and 14.7% of the fungal isolates were positive for AF and OTA production respectively. In addition, 21 samples were contaminated by AFs (14.98 and 22.4 µg kg(-1) for AFB1 ) and OTA (3.02 and 4.76 µg kg(-1) ) and three of them exceeded the EC limits.

CONCLUSION

This study is the first report on problems with the occurrence of microfungi, mycotoxin contamination, AFs and OTA in different grain-based flour samples from Turkey and highlights developable points of current limits for food and public health safety.

Downregulation of Rad51 participates in OTA-induced DNA double-strand breaks in GES-1 cells in vitro

Ochratoxin A (OTA), a mycotoxin produced by ubiquitous Aspergilli, is carcinogenic, teratogenic, and nephrotoxic in both humans and animals. Our previous study found that OTA induced DNA double-strand breaks (DSBs) and resulted in G2 phase arrest in human gastric epithelium immortalized (GES-1) cells. DSBs can cause genomic instability, mutations, and neoplastic transformations, and improper repair of DSBs may lead to the development of cancer. Rad51 is a key protein in the homologous recombination (HR) pathway of DSBs repair. The roles of Rad51 in the repair of DNA damage vary in response to different types of cytotoxic agents. The effect of OTA on Rad51 expression and its putative role in the OTA-induced DSBs in GES-1 cells are still not clear enough. The aim of the current study is to elucidate the role of Rad51 in OTA-induced DSBs in GES-1 cells. The results showed that OTA treatment decreased Rad51 expression in a dose- and time-dependent manner. Specific downregulation of Rad51 by siRNA induced DSBs and G2 phase arrest. Rad51 overexpression by transfection with a Rad51-expressing plasmid partly rescued the DSBs and G2 phase arrest in OTA-treated cells. The findings indicate that downregulation of Rad51 contributes to OTA-induced DNA damage in GES-1 cells. Knockdown of p53 with siRNA for 48h effectively reversed the downregulation of Rad51, and decreased the OTA-induced DSBs in GES-1 cells. In addition, the downregulation of Rad51 induced by OTA could be significantly attenuated with specific ERK inhibitor PD98059 or specific p38 MAPK inhibitor SB203580 pre-treatment in GES-1 cells. Thus, the results suggest that downregulation of Rad51 participates in OTA-induced DNA double-strand breaks in GES-1 cells in vitro. And p53, ERK and p38 signaling pathways are all involved in the process.

Mycotoxins' activity at toxic and sub-toxic concentrations: differential cytotoxic and genotoxic effects of single and combined administration of sterigmatocystin, ochratoxin A and citrinin on the hepatocellular cancer cell line Hep3B

Food safety organizations indicate the likelihood of constant human and animal exposure to mycotoxin mixtures as a possible negative public health impact. Risk assessment demonstrates that certain mycotoxins of Aspergillus and Penicillium spp. are toxic and hold a significant genotoxic efficacy at nanomolar concentrations. The aim of the current study was to investigate the potential cytogenetic effects of sterigmatocystin (STER), ochratoxin A (OTA) and citrinin (CTN) alone or in combination, at pM to μΜ concentrations, on the human hepatocellular cancer cell line Hep3B. MTT reduction, mitotic divisions, cell cycle delays and sister chromatid exchange rates (SCE) were determined as endpoints of metabolic activity, cytotoxicity, cytostaticity, and genotoxicity, respectively. All mycotoxin treatments induce SCE rates from 10-12 M, while their cytotoxic and cytostatic potential varies. In PRI and MI assays, but not at MTT, STER alone or in combination with OTA + CTN appeared cytostatic and cytotoxic, even at 10-12 M, while CTN alone and all other combinations displayed substantial cellular survival inhibition in doses ≥ 10-8 M. Co-administration of STER + OTA or STER + CTN in concentrations ≤ 10-1 M, increased the MI and MTT activity, while it did not affect the PRI. Mycotoxin co-treatments revealed in general similar-to-additive or antagonistic genotoxic and cytotoxic effects. Our results for the first time describe that STER alone or in combination with OTA and/or CTN share a cytotoxic and cytogenetic potential even at picoMolar concentrations on human hepatoma cells in vitro.

Environment, dysbiosis, immunity and sex-specific susceptibility: a translational hypothesis for regressive autism pathogenesis

Background

Autism is an increasing neurodevelopmental disease that appears by 3 years of age, has genetic and/or environmental etiology, and often shows comorbid situations, such as gastrointestinal (GI) disorders. Autism has also a striking sex-bias, not fully genetically explainable.

Objective

Our goal was to explain how and in which predisposing conditions some compounds can impair neurodevelopment, why this occurs in the first years of age, and, primarily, why more in males than females.

Methods

We reviewed articles regarding the genetic and environmental etiology of autism and toxins effects on animal models selected from PubMed and databases about autism and toxicology.

Discussion

Our hypothesis proposes that in the first year of life, the decreasing of maternal immune protection and child immune-system immaturity create an immune vulnerability to infection diseases that, especially if treated with antibiotics, could facilitate dysbiosis and GI disorders. This condition triggers a vicious circle between immune system impairment and increasing dysbiosis that leads to leaky gut and neurochemical compounds and/or neurotoxic xenobiotics production and absorption. This alteration affects the ‘gut-brain axis’ communication that connects gut with central nervous system via immune system. Thus, metabolic pathways impaired in autistic children can be affected by genetic alterations or by environment–xenobiotics interference. In addition, in animal models many xenobiotics exert their neurotoxicity in a sex-dependent manner.

Conclusions

We integrate fragmented and multi-disciplinary information in a unique hypothesis and first disclose a possible environmental origin for the imbalance of male:female distribution of autism, reinforcing the idea that exogenous factors are related to the recent rise of this disease.

Toxicity of ochratoxin a and its modulation by antioxidants: a review

Ochratoxin A (OTA) is a mycotoxin involved in the development of different types of cancers in rats, mice and humans. A growing number of in vitro and in vivo studies has been collected and has described evidence compatible with a role for oxidative stress in OTA toxicity and carcinogenicity. Because the contribution of the oxidative stress response in the development of cancers is well established, a role in OTA carcinogenicity is plausible. Several studies have been performed to try to counteract the adverse effects of oxygen radicals generated under OTA-exposure. A number of molecules with various antioxidant properties were tested, using in vivo or in vitro models. Protection against OTA-induced DNA damage, lipid peroxidation, as well as cytotoxicity were observed, further confirming the link between OTA toxicity and oxidative damage. These studies demonstrated that antioxidants are able to counteract the deleterious effects of chronic consumption or exposure to OTA and confirmed the potential effectiveness of dietary strategies to counteract OTA toxicity.