Sex differences in ochratoxin a toxicity in F344 rats after 7 and 21 days of daily oral administration

Effect of Bioactive Ingredients on Urinary Excretion of Aflatoxin B1 and Ochratoxin A in Rats, as Measured by Liquid Chromatography with Fluorescence Detection

Aflatoxin B1 (AFB1) and ochratoxin A (OTA) are highly toxic mycotoxins present in food and feed, posing serious health risks to humans and animals. This study aimed to validate an efficient and cost-effective analytical method for quantifying AFB1 and OTA in rat urine using immunoaffinity column extraction and liquid chromatography with fluorescence detection (IAC-LC-FD). Additionally, the study evaluated the effect of incorporating fermented whey and pumpkin into the feed on the urinary excretion of these mycotoxins. The limits of detection and quantification were determined to be 0.1 µg/kg and 0.3 µg/kg, respectively, for both mycotoxins in feed, and 0.2 ng/mL and 0.6 ng/mL, respectively, in urine. The method demonstrated robust recovery rates ranging from 74% to 119% for both AFB1 and OTA in both matrices. In feed samples, the levels of AFB1 and OTA ranged from 4.3 to 5.2 µg/g and from 5.4 to 8.8 µg/g, respectively. This validated method was successfully applied to analyze 116 urine samples from rats collected during the fourth week of an in vivo trial. The results indicated that the addition of fermented whey and pumpkin to the feed influenced mycotoxin excretion in urine, with variations observed based on the sex of the rats, type of mycotoxin, and exposure dosage.

Protective Effect of Boric Acid Against Ochratoxin A-Induced Toxic Effects in Human Embryonal Kidney Cells (HEK293): A Study on Cytotoxic, Genotoxic, Oxidative, and Apoptotic Effects

The present study evaluates the protective properties of boric acid (BA) against the toxic effects induced by ochratoxin A (OTA) in human embryonic kidney cells (HEK293). The focus is on various parameters such as cytotoxicity, genotoxicity, oxidative stress, and apoptosis. OTA is a known mycotoxin that has harmful effects on the liver, kidneys, brain, and nervous system. BA, on the other hand, a boron-based compound, is known for its potential as a vital micronutrient with important cellular functions. The results show that BA administration not only increases cell viability but also mitigates the cytotoxic effects of OTA. This is evidenced by a reduction in the release of lactate dehydrogenase (LDH), indicating less damage to cell membranes. In addition, BA shows efficacy in reducing genotoxic effects, as the frequency of micronucleus (MN) and chromosomal aberrations (CA) decreases significantly, suggesting a protective role against DNA damage. In addition, the study shows that treatment with BA leads to a decrease in oxidative stress markers, highlighting its potential as a therapeutic intervention against the deleterious effects of OTA. These results emphasize the need for further research into the protective mechanisms of boron, particularly BA, in combating cell damage caused by OTA.

Development and application of the physiologically-based toxicokinetic (PBTK) model for ochratoxin A (OTA) in rats and humans

Ochratoxin A (OTA) is a common fungal toxin frequently detected in food and human plasma samples. Currently, the physiologically based toxicokinetic (PBTK) model plays an active role in dose translation and can improve and enhance the risk assessment of toxins. In this study, the PBTK model of OTA in rats and humans was established based on knowledge of OTA-specific absorption, distribution, metabolism, and excretion (ADME) in order to better explain the disposition of OTA in humans and the discrepancies with other species. The models were calibrated and optimized using the available kinetic and toxicokinetic (TK) data, and independent test datasets were used for model evaluation. Subsequently, sensitivity analyses and population simulations were performed to characterize the extent to which variations in physiological and specific chemical parameters affected the model output. Finally, the constructed models were used for dose extrapolation of OTA, including the rat-to-human dose adjustment factor (DAF) and the human exposure conversion factor (ECF). The results showed that the unbound fraction (Fup) of OTA in plasma of rat and human was 0.02-0.04% and 0.13-4.21%, respectively. In vitro experiments, the maximum enzyme velocity (Vmax) and Michaelis-Menten constant (Km) of OTA in rat and human liver microsomes were 3.86 and 78.17 μg/g min-1, 0.46 and 4.108 μg/mL, respectively. The predicted results of the model were in good agreement with the observed data, and the models in rats and humans were verified. The PBTK model derived a DAF of 0.1081 between rats and humans, whereas the ECF was 2.03. The established PBTK model can be used to estimate short- or long-term OTA exposure levels in rats and humans, with the capacity for dose translation of OTA to provide the underlying data for risk assessment of OTA.

Pharmacokinetics and 28-day repeated-dose toxicity of enniatin B after oral administration in mice

Enniatins are emerging mycotoxins that contaminate foods. The present study investigated the oral pharmacokinetics and 28-day repeated-dose oral toxicity of enniatin B (ENNB) in CD1 (ICR) mice. In the pharmacokinetic study, male mice received a single oral or intravenous dose of ENNB [30 mg/kg body weight (BW) and 1 mg/kg BW, respectively]. After oral dosing, ENNB exhibited 139.9% bioavailability, a 5.1-hr elimination half-life, 5.26% fecal excretion from 4 to 24 h post-dose, and upregulation of Cyp7a1, Cyp2a12, Cyp2b10, and Cyp26a1 in the liver 2 h post-dosing. In the 28-day toxicity study, ENNB was administered to male and female mice by oral gavage at 0, 7.5, 15, and 30 mg/kg BW/day. Females (7.5 and 30 mg/kg) showed dose-unrelated decreased food consumption without accompanying changes in clinical parameters. Males (30 mg/kg) showed low red blood cell counts and high blood urea nitrogen levels and absolute kidney weights; however, other related parameters including the histopathology of systemic organs/tissues were unchanged. These results suggest that ENNB may not induce toxicity after 28 days of oral administration in mice, despite high absorption. The no-observed-adverse-effect level of ENNB after 28 days of repeated oral doses was 30 mg/kg BW/day for both sexes of mice.

Genomic analysis of Fisher F344 rat kidneys from a reproductive study following dietary ochratoxin A exposure

Ochratoxin A (OTA) is a mycotoxin produced by species of Penicillium and Aspergillus, and is found in many commodities including cereal grains, nuts, and coffee. OTA is a renal carcinogen and nephrotoxin at high concentrations, targeting the proximal tubules. This study uses transcriptomics and the previously reported apical data (Bondy et al., 2021) to infer mode-of-action of OTA toxicity in male and female rats exposed to low doses of OTA in utero and throughout development. Our findings support a male-specific activation of the innate and adaptive immune responses in F1 pups to OTA exposure. This was not found in the female F1 pups, and may be due to female-specific increased p38 activity and VDR signaling. Differentially expressed genes related to karyomegaly, MAPK activity, and immune activation appears to develop from in utero exposure to OTA whereas those related to decreased kidney and liver function, and changes to reproductive pathways occur in both rat generations. Together, these transcriptional results confirm that dietary exposure to OTA causes renal toxicity as well as alterations to hepatic and reproductive pathways in rats. In utero exposure of rats to OTA results in sex-specific alterations in immune response pathways, VDR signaling, and p38 activity.

Ochratoxin A in Slaughtered Pigs and Pork Products

Ochratoxin A (OTA) is a mycotoxin that is produced after the growth of several Aspergillus and Penicillium spp. in feeds or foods. OTA has been proved to possess nephrotoxic, hepatotoxic, teratogenic, neurotoxic, genotoxic, carcinogenic and immunotoxic effects in animals and humans. OTA has been classified as possibly carcinogenic to humans (Group 2B) by the IARC in 2016. OTA can be mainly found in animals as a result of indirect transmission from naturally contaminated feed. OTA found in feed can also contaminate pigs and produced pork products. Additionally, the presence of OTA in pork meat products could be derived from the direct growth of OTA-producing fungi or the addition of contaminated materials such as contaminated spices. Studies accomplished in various countries have revealed that pork meat and pork meat products are important sources of chronic dietary exposure to OTA in humans. Various levels of OTA have been found in pork meat from slaughtered pigs in many countries, while OTA levels were particularly high in the blood serum and kidneys of pigs. Pork products made from pig blood or organs such as the kidney or liver have been often found to becontaminated with OTA. The European Union (EU) has established maximum levels (ML) for OTA in a variety of foods since 2006, but not for meat or pork products. However, the establishement of an ML for OTA in pork meat and meat by-products is necessary to protect human health.

Subchronic exposure of individual and combined ochratoxin A and citrinin selectively affects the expression of rat renal organic cation transporters

Ochratoxin A (OTA) and citrinin (CIT) are nephrotoxins found co-occurring in various human/animal food/feed and recognized as a health threat. However, most studies investigate individual effects and neglect their combined nephrotoxic effects in mammals. Previous studies have indicated that organic anion/cation transporters (OATs/OCTs) localized in renal proximal tubules mediate the transport of OTA and CIT. Still, little is known about the in vivo effects of individual/combined OTA and CIT on protein localization/expression of OCTs, physiologically/pharmacologically important renal transporters. Here, we used Western blot and immunofluorescence microscopy to study the effects of subchronic (21-day) exposure to individual/combined OTA (0.125 and 0.250 mg kg^-1 b.w.) and CIT (20 mg kg^-1 b.w.) on protein localization/expression of organic cation transporters (rOct1/Slc22a1 and rOct2/Slc22a2) in kidneys of Wistar rats. Since the antioxidant resveratrol (RSV) has shown measurable protective effects against OTA- and CIT-related oxidative stress toxicity in vitro, we investigated the effects of an OTA + CIT + RSV combination on rOct1/2 localization/expression in the same model. Individual OTA induced a dose-dependent decrease of rOct1 but not rOct2 protein expression, whereas their localization pattern remained unchanged. Individual CIT did not affect the renal rOct1/2 protein localization/expression. Combined OTA + CIT exposure induced a significant decrease of rOct1 protein expression by an OTA250 dose, whereas oral co-administration of OTA + CIT + RSV resulted in a significant decrease of rOct1/2 protein expression. Thus, we revealed an OTA-related selective effect on the rOct1/2 protein expression and a non-specific adverse effect of RSV in the OTA + CIT + RSV combination on the renal organic cation transport system in rat.

Time Course of Renal Transcriptomics after Subchronic Exposure to Ochratoxin A in Fisher Rats

The mycotoxin ochratoxin A (OTA) is a potent nephrocarcinogen, mainly in male rats. The aim of this study was to determine the time course of gene expression (GeneChip® Rat Gene 2.0 ST Array, Affymetrix) in kidney samples from male and female F344 rats, treated daily (p.o) with 0.50 mg/kg b.w. (body weight) of OTA for 7 or 21 days, and evaluate if there were differences between both sexes. After OTA treatment, there was an evolution of gene expression in the kidney over time, with more differentially expressed genes (DEG) at 21 days. The gene expression time course was different between sexes with respect to the number of DEG and the direction of expression (up or down): the female response was progressive and consistent over time, whereas males had a different early response with more DEG, most of them up-regulated. The statistically most significant DEG corresponded to metabolism enzymes (Akr1b7, Akr1c2, Adh6 down-regulated in females; Cyp2c11, Dhrs7, Cyp2d1, Cyp2d5 down-regulated in males) or transporters (Slc17a9 down-regulated in females; Slco1a1 (OATP-1) and Slc51b and Slc22a22 (OAT) down-regulated in males). Some of these genes had also a basal sex difference and were over-expressed in males or females with respect to the other sex.

Ochratoxin A induces glomerular injury through activating the ERK/NF-κB signaling pathway

Ochratoxin A (OTA) was reported to induce proximal tubules nephrotoxicity in humans and animals. However, the toxicity of OTA on glomeruli has rarely been studied. We investigated OTA-induced glomerular injury and the underlying mechanisms. Mice were intraperitoneally treated with OTA (0, 0.5, 1.5 and 2.5 mg/kg b.w.) on alternate day for 3 weeks. OTA exposure decreased the weight gain ratio, the kidney index and increased the levels of serum creatinine and blood urea nitrogen. It induced also fragmentation and atrophy in glomeruli, and increased the expression of TNF-α, IL-6, COX-2, TGF-β, α-SMA and vimentin in a dose-dependent manner. Human mesangial cells (HMC) were treated with OTA (0-8 μM) for 48 h. Treatment of HMC cells with OTA increased cell inhibition rate, up-regulated the expression of IL-6, TGF-β, α-SMA and vimentin in a dose-dependent manner. Additionally, it enhanced the phosphorylation of ERK1/2 and p65, degradation of IκB-α and translocation of p65 into the nucleus. OTA-induced toxicity was attenuated by NF-κB and ERK1/2 inhibitors. In conclusion, these results suggest that OTA exposure induces glomerular injury via activation of the ERK/NF-κB signaling pathway, and provide novel insights into the research of OTA induced nephrotoxicity.

Safety evaluation of Ochratoxin A and Citrinin after 28 days repeated dose oral exposure to Wistar rats

Mycotoxins, ochratoxin A (OTA), and citrinin (CTN) are toxic metabolites of filamentous fungi. The most common fungal species that produce OTA and CTN belong to genera Aspergillus, Penicillium, Fusarium, and Monascus, and these fungal species are found to be contaminant a wide range of grains, food, and food product. The aim of our study was to evaluate the sub-acute repeated dose oral toxicity of OTA and CTN in experimental rodents by following OECD test guidelines for testing chemicals no. 407 with minor modifications. Twenty-five rats of each sex were divided equally into five groups; vehicle control, OTA 25 μg/kg b. wt., OTA 100 μg/kg b. wt., CTN 25 μg/kg b.wt. and CTN 100 μg/kg b. wt. The results of this study showed no abnormal clinical signs during 28 days of the experimental period. We did not found any significant changes in body weight gain, food consumption pattern, organ weight, hematology except few parameters, and biochemical values in any of the treatment and control groups. However, histopathological observations revealed severe nephrotoxicity and mild follicular depletion in the spleen of 100 μg/kg b. wt. treated groups of both OTA and CTN mycotoxins. The findings of our study are of its first kind that reports the systemic toxicity of OTA and CTN oral exposure to laboratory rodents.

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.

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.

Oxidative stress as a mechanism of combined OTA and CTN toxicity in rat plasma, liver and kidney

Ochratoxin A (OTA) and citrinin (CTN) commonly coexist in grains. Aiming to evaluate oxidative stress in OTA + CTN toxicity, male Wistar rats were orally treated with two doses of OTA (0.125 and 0.250 mg kg−1 of body weight (b.w.)), CTN (2 mg kg−1 of b.w.) and resveratrol (RSV; 20 mg kg−1 of b.w.) and combined daily during 3 weeks. Protein carbonyl concentrations were measured in kidneys and liver; catalytic activity of glutathione peroxidase (GPx), superoxide dismutase (SOD), catalase (CAT) and glutathione (GSH) level in plasma, kidneys and liver, while malondialdehyde (MDA) concentration was measured in plasma, kidneys, liver and urine. Mycotoxin treatment significantly increased MDA concentration in plasma and kidney and decreased SOD activity in the liver. Rats treated with CTN and OTA125 + CTN had lower plasma GPx activity. Concentration of GSH in the kidney and protein carbonyls in the kidney and liver as well as GPx activity in the kidney and liver, SOD activity in the kidney and CAT activity in the liver were not affected. Protective effect of RSV was observed on GSH in the kidney and plasma and MDA in the kidney, plasma and urine. Oxidative stress is involved in OTA + CTN toxicity in vivo because such treatment affects parameters of oxidative stress, particularly in plasma. RSV can reduce but not overcome oxidative stress induced by combined OTA and CTN treatment.

Sex-dependent gene expression after ochratoxin A insult in F344 rat kidney

Ochratoxin A (OTA) is a potent rodent nephrocarcinogen; being males more sensitive than females. The objective was to study the response between sexes at gene expression level (whole genome transcriptomics) in kidneys of F344 rats treated with 0.21 or 0.50 mg/kg bw OTA for 21 days. DNA methylation analysis of selected genes was also studied (MALDI-TOF mass spectrometry). OTA-induced response was dose-dependent in males and females, although clearer in males. Females showed a higher number of altered genes than males but functional analysis revealed a higher number of significantly enriched toxicity lists in 0.21 mg/kg treated males. OTA modulated damage, signaling and metabolism related lists, as well as inflammation, proliferation and oxidative stress in both sexes. Eleven toxicity lists (damage, fibrosis, cell signaling and metabolism) were exclusively altered in males while renal safety biomarker and biogenesis of mitochondria lists were exclusively enriched in females. A high number of lists (39) were significantly enriched in both sexes. However, they contained many sex-biased OTA-modulated genes, mainly phase I and II, transporters and nuclear receptors, but also others related to cell proliferation/apoptosis. No biologically relevant changes were observed in the methylation of selected genes.