Experimental mycotoxic nephropathy in pigs provoked by a diet containing ochratoxin A and penicillic acid

Foodborne Diseases Due to Underestimated Hazard of Joint Mycotoxin Exposure at Low Levels and Possible Risk Assessment

The subject of this review paper is to evaluate the underestimated hazard of multiple mycotoxin exposure of animals/humans for the appearance of foodborne ailments and diseases. The significance of joint mycotoxin interaction in the development of foodborne diseases is discussed, and appropriate conclusions are made. The importance of low feed/food levels of some target mycotoxins co-contaminations in food and feedstuffs for induction of target foodborne mycotoxicoses is also studied in the available literature. The appropriate hygiene control and the necessary risk assessment in regard to possible hazards for animals and humans are also discussed, and appropriate suggestions are made. Some internationally recognized prophylactic measures, management of the risk, and the necessity of elaboration of new international regulations in regard to the maximum permitted levels are also carefully discussed and analysed in the cases of multiple mycotoxin contaminations. The necessity of harmonization of mycotoxin regulations and control measures at international levels is also discussed in order to facilitate food trade between the countries and to ensure global food safety.

Aspergillus ochraceus: Metabolites, Bioactivities, Biosynthesis, and Biotechnological Potential

Fungus continues to attract great attention as a promising pool of biometabolites. Aspergillus ochraceus Wilh (Aspergillaceae) has established its capacity to biosynthesize a myriad of metabolites belonging to different chemical classes, such as isocoumarins, pyrazines, sterols, indole alkaloids, diketopiperazines, polyketides, peptides, quinones, polyketides, and sesquiterpenoids, revealing various bioactivities that are antimicrobial, cytotoxic, antiviral, anti-inflammatory, insecticidal, and neuroprotective. Additionally, A. ochraceus produces a variety of enzymes that could have variable industrial and biotechnological applications. From 1965 until June 2022, 165 metabolites were reported from A. ochraceus isolated from different sources. In this review, the formerly separated metabolites from A. ochraceus, including their bioactivities and biosynthesis, in addition, the industrial and biotechnological potential of A. ochraceus are highlighted.

New Evidences about the Carcinogenic Effects of Ochratoxin A and Possible Prevention by Target Feed Additives

A review of the carcinogenic effects of ochratoxin A (OTA) on various tissues and internal organs in laboratory and farm animals is made. Suggestions are made regarding how to recognize and differentiate the common spontaneous neoplastic changes characteristic for advanced age and the characteristic neoplasia in different tissues and organs in laboratory animals/poultry exposed to OTA. The synergistic effects of OTA together with its natural combination of penicillic acid are also investigated regarding possible carcinogenic effects. The malignancy and the target location of OTA-induced neoplasia is studied. The sex-differences of such neoplasia are investigated in the available literature. The time of appearance of the first neoplasia is investigated in long-term carcinogenic studies with OTA-treated animals. The possibility of target feed additives or herbs to counteract the toxic and carcinogenic effects of OTA is studied in the available literature. Some effective manners of prophylaxis and/or prevention against OTA contamination of feedstuffs/foods or animal production are suggested. The suitability of various laboratory animals to serve as experimental model for humans with regard to OTA-induced tumorigenesis is investigated.

Biomarkers of Deoxynivalenol, Citrinin, Ochratoxin A and Zearalenone in Pigs after Exposure to Naturally Contaminated Feed Close to Guidance Values

This study applied multi-mycotoxin liquid chromatography with tandem mass spectrometric detection (LC-MS/MS) methods to determine the biomarkers of exposure in urine and serum samples from a dose-response study with pigs. The 24 studied pigs were divided into three groups: a control and two experimental ones (with different levels of feed contamination). They were exposed to feed prepared from cereals contaminated with deoxynivalenol (DON), zearalenone (ZEN), ochratoxin A (OTA) and citrinin (CIT) for 14 days. After that, both experimental groups received the same feed as the control group for the next 14 days to determine the kinetics of the disappearance of mycotoxin biomarkers. Urine samples were collected daily in the morning and blood samples-eight-times during the experiment. The study reported herein was the first prolonged exposure experiment for multiple mycotoxins like OTA and CIT in pigs. The urinary and serum levels of all biomarkers correlated well with the respective toxin intake; thereby demonstrating that they are suitable biomarkers of exposure in pigs. Urine is a good candidate to monitor DON, ZEN, OTA, CIT exposure while serum may be used to monitor DON, OTA and CIT. Additionally, OTA has even been quantified in both matrices in the experimental groups two weeks after changing the contaminated feed back to the control, this result differed from those produced by the other mycotoxins which were only quantified during the first two weeks. Therefore both matrices are suitable candidates to monitor prolonged OTA exposure in pigs.

Effects of Single and Repeated Oral Doses of Ochratoxin A on the Lipid Peroxidation and Antioxidant Defense Systems in Mouse Kidneys

Ochratoxin-A (OTA) is a carcinogenic and nephrotoxic mycotoxin, which may cause health problems in humans and animals, and it is a contaminant in foods and feeds. The purpose of the present study is to evaluate the effect of oral OTA exposure on the antioxidant defense and lipid peroxidation in the kidney. In vivo administration of OTA in CD1, male mice (1 or 10 mg/kg body weight in a single oral dose for 24 h and repeated daily oral dose for 72 h or repeated daily oral dose of 0.5 mg/kg bodyweight for 21 days) resulted in a significant elevation of OTA levels in blood plasma. Some histopathological alterations, transcriptional changes in the glutathione system, and oxidative stress response-related genes were also found. In the renal cortex, the activity of the glutathione-system-related enzymes and certain metabolites of the lipid peroxidation (conjugated dienes, trienes, and thiobarbituric reactive substances) also changed.

Long term preliminary studies on toxic and carcinogenic effect of individual or simultaneous exposure to ochratoxin A and penicillic acid in mice

Carcinogenic effects of ochratoxin A (OTA) on liver, kidneys, intestine, muscles and subcutaneous tissue of BALB/c albino mice divided in three experimental and one control groups (30 mice in each group - 15 males and 15 females) and exposed to 10 ppm OTA and/or 50-60 ppm penicillic acid (PA) in the diet were seen. A total 22 neoplasias were found to be induced in the mice during 20 months' experimental period. Among them 14 were malignant and 8 benign. The number of neoplasias was significantly higher in the mice treated simultaneously with OTA and PA (14) compared to those in mice treated with OTA only (8). The number of malignant neoplasias was also higher (14) compared to benign neoplasias (8). Nine of a total fourteen malignant neoplasis and five of a total eight benign neoplasias were seen in the male mice. Pathological changes in mice after two weeks' experimental period were characterized by degenerative changes in kidneys, liver and gastrointestinal tract, which were better expressed in the mice exposed simultaneously to OTA and PA. A strong synergistic effect was found between OTA and PA towards tumorogenesis. It seems that mice are not a good experimental model for humans with regard to OTA-induced tumourigenesis, because the target organ of OTA-toxicity in humans or pigs is mainly the kidney, but not the liver, intestines, subcutaneous tissue or muscles as seen in this study.

Mycotoxicoses in veterinary medicine: Aspergillosis and penicilliosis

Molds and mycotoxins are contaminants of animal feed causing spoilage and clinical intoxication. Animal exposure to mycotoxins reflects diet composition with major differences occurring between animals kept predominantly of pastures, i.e. ruminants and horses, and those consuming formulated feed like pigs and poultry. Mixed feeds are composed of several ingredients, often sourced from different continents. Subsequently, practitioners may confront endemic diseases and signs of toxin exposure related to toxins imported accidentally with contaminated feed materials from other countries and continents. Mycotoxins comprise more than 300 to 400 different chemicals causing a variety of clinical symptoms. Mycotoxin exposure causes major economic losses due to reduced performance, impaired feed conversion and fertility, and increased susceptibility to environmental stress and infectious diseases. In acute cases, clinical symptoms following mycotoxin ingestion are often non-specific, hindering an immediate diagnosis. Furthermore, most mold species produce more than one toxin, and feed commodities are regularly contaminated with various mold species resulting in complex mixtures of toxins in formulated feeds. The effects of these different toxins may be additive, depending on the level and time of exposure, and the intensity of the clinical symptoms based on age, health, and nutritional status of the exposed animal(s). Threshold levels of toxicity are difficult to define and discrepancies between analytical data and clinical symptoms are common in daily practice. This review aims to provide an overview of Aspergillus and Penicillium toxins that are frequently found in feed commodities and discusses their effects on animal health and productivity.

Cryptic Secondary Metabolites from the Sponge-Associated Fungus Aspergillus ochraceus

The fungus Aspergillus ochraceus was isolated from the Mediterranean sponge Agelas oroides. The initial fermentation of the fungus on solid rice medium yielded 16 known compounds (4⁻19). The addition of several inorganic salts to the rice medium mainly influenced the accumulation of these secondary metabolites. Fermentation of the fungus on white bean medium yielded the new waspergillamide B (1) featuring an unusual p-nitrobenzoic acid as partial structure. Moreover, two new compounds, ochraspergillic acids A and B (2 and 3), which are both adducts of dihydropenicillic acid and o- or p-aminobenzoic acid, were isolated from the co-culture of the fungus with Bacillus subtilis. Compound 2 was also detected in axenic fungal cultures following the addition of either anthranilic acid or tryptophan to the rice medium. The structures of the new compounds were established by 1D and 2DNMR experiments as well as from the HRMS data. The absolute configuration of 1 was elucidated following hydrolysis and derivatization of the amino acids using Marfey's reagent. Viomellein (9) and ochratoxin B (18) exhibited strong cytotoxicity against the A2780 human ovarian carcinoma cells with IC50 values of 5.0 and 3.0 µM, respectively.

Secondary metabolite production by cereal-associated penicillia during cultivation on cereal grains

Cereals are vulnerable substrates for fungal growth and subsequent mycotoxin contamination. One of the major fungal genera to colonize the ecosystem of stored grain is Penicillium, especially species in the series of Viridicata and Verrucosa. Culturing these species on grains, we hoped to induce the production of relevant secondary metabolites produced by these fungi in the early stage of cereal breakdown. In a multivariate setup six different cereal grains (wheat, rye, barley, oat, rice, and maize), one kind of white beans, and two standard fungal media, Yeast Extract Sucrose agar (YES agar) and Czapek Yeast Autolysate agar (CYA agar), were inoculated with the ten most important cereal-associated species from Penicillium (P. aurantiogriseum, P. cyclopium, P. freii, P. melanoconidium, P. neoechinulatum, P. polonicum, P. tricolor, P. viridicatum, P. hordei, and P. verrucosum). P. nordicum is a meat-associated species, which was included due to its chemical association with P. verrucosum, in addition to see if a substrate change would alter the profile of known chemistry. We found that cereals function very well as substrates for secondary metabolite production, but did not present significantly different secondary metabolite profiles, concerning known chemistry, as compared to standard laboratory agar media. However, white beans altered the semi-quantitative secondary metabolite profiles for several species. Correlations between substrates and certain metabolites were observed, as illuminated by principal component analysis. Many bioactive secondary metabolites were observed for the first time in the analyzed fungal species, including ergot type alkaloids in P. hordei.

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.

A critical review of producers of small lactone mycotoxins: patulin, penicillic acid and moniliformin

A very large number of filamentous fungi has been reported to produce the small lactone mycotoxins patulin, penicillic acid and moniliformin. Among the 167 reported fungal producers of patulin, only production by 29 species could be confirmed. Patulin is produced by 3 Aspergillus species, 3 Paecilomyces species, 22 Penicillium species from 7 sections of Penicillium, and one Xylaria species. Among 101 reported producers of penicillic acid, 48 species could produce this mycotoxin. Penicillic acid is produced by 23 species in section Aspergillus subgenus Circumdati section Circumdati, by Malbranchea aurantiaca and by 24 Penicillium species from 9 sections in Penicillium and one species that does not actually belong to Penicillium (P. megasporum). Among 40 reported producers of moniliformin, five species have been regarded as doubtful producers of this mycotoxin or are now regarded as taxonomic synonyms. Moniliformin is produced by 34 Fusarium species and one Penicillium species. All the accepted producers of patulin, penicillic acid and moniliformin were revised according to the new one fungus – one name nomenclatural system, and the most recently accepted taxonomy of the species.

Comparative effect of ochratoxin A on inflammation and oxidative stress parameters in gut and kidney of piglets

Ochratoxin A (OTA) is a secondary metabolite produced by fungi of Aspergillus and Penicillium genra. OTA is mainly nephrotoxic but can also cause hepatotoxicity, mutagenicity, teratogenicity, neurotoxicity and immunotoxicity. As recent studies have highlighted the close relationship between gastrointestinal tract and kidney, as principal organs involved in absorption and respective excretion of xenobiotics, the aim of the present study was to analyze the effect of a subchronic exposure (30 days) to 0.05 mg/kg OTA on immune response and oxidative stress parameters at the level of intestine and kidney of young swine. The experiment was realised on twelve crossbred weaned piglets randomly allotted to both control group or toxin group fed 0.050 mg OTA/kg feed. Our results have shown that a subchronic intoxication with a low dose of OTA for 30 days affected the immune response and the anti-oxidant self-defense at gut and kidney level. The gene expression of both markers of signaling pathways involved in inflammation and inflammatory cytokines were affected in a much higher extent in the gut than in the kidney Of OTA intoxicated piglets.

Diabetogenic Effects of Ochratoxin A in Female Rats

In this study, the diabetogenic effects of long term Ochratoxin A (OTA) administration in rats were investigated, and its role in the etiology of diabetes mellitus (DM) was examined utilizing 42 female Wistar rats for these purposes. The rats were divided into three different study and control groups according to the duration of the OTA administration. The rats received 45 μg OTA daily in their feed for 6, 9 and 24 weeks, respectively. Three control groups were also used for the same time periods. Blood and pancreatic tissue samples were collected during the necropsy at the end of the 6, 9 and 24 weeks. The plasma values of insulin, glucagon and glucose were determined for the study and control groups. Pancreatic lesions were evaluated via histopathological examination and insulin and glucagon expression in these lesions was subsequently determined using immunohistochemical methods. Statistically significant decreases in insulin levels were observed, in contrast to increases in blood glucagon and glucose levels. Histopathological examinations revealed slight to moderate degeneration in Langerhans islet cells in all OTA-treated groups. Immunohistochemistry of pancreatic tissue revealed decreased insulin and increased glucagon expression. This study demonstrated that OTA may cause pancreatic damage in the Langerhans islet and predispose rats to DM.

Effects of Electron Beam Irradiation on Zearalenone and Ochratoxin A in Naturally Contaminated Corn and Corn Quality Parameters

Zearalenone (ZEN) and ochratoxin A (OTA) are secondary toxic metabolites widely present in grains and grain products. In this study, the effects of electron beam irradiation (EBI) on ZEN and OTA in corn and the quality of irradiated corn were investigated. Results indicated that EBI significantly affected ZEN and OTA. The degradation rates of ZEN and OTA at 10 kGy in solution were 65.6% and 75.2%, respectively. The initial amounts significantly affected the degradation rate. ZEN and OTA in corn were decreased by the irradiation dose, and their degradation rates at 50 kGy were 71.1% and 67.9%, respectively. ZEN and OTA were more easily degraded in corn kernel than in corn flour. Moisture content (MC) played a vital role in ZEN and OTA degradation. High MC was attributed to high ZEN and OTA degradation. The quality of irradiated corn was evaluated on the basis of irradiation dose. L* value changed, but this change was not significant (p > 0.05). By contrast, a* and b* decreased significantly (p < 0.05) with irradiation dose. The fatty acid value increased significantly. The pasting properties, including peak, trough, breakdown, and final and setback viscosities, were also reduced significantly (p < 0.05) by irradiation. Our study verified that EBI could effectively degrade ZEN and OTA in corn. Irradiation could also affect corn quality.

Penicillium Species and Their Associated Mycotoxins

Penicillium are very diverse and cosmopolite fungi, about 350 species are recognized within this genus. It is subdivided in four subgenera Aspergilloides, Penicillium, Furcatum, and Biverticillium; recently the first three has been included in Penicillium genus, and Biverticillium under Talaromyces. They occur worldwide and play important roles as decomposers of organic materials, cause destructive rots in the food industry where produces a wide range of mycotoxins; they are considered enzyme factories, and common indoor air irritants. In terms of human health are rarely associated as human pathogen because they hardly growth at 37°, while the main risk is related to ingestion of food contaminated by mycotoxins produced by several species of Penicillium. Various mycotoxins can occur in foods and feeds contaminated by Penicillium species, the most important are ochratoxin A and patulin; for which regulation are imposed in a number of countries, and at a less extent cyclopiazonic acid. In this chapter we summarize the main aspect of the morphology, ecology and toxigenicity of Penicillium foodborne mycotoxigenic species which belong mainly in subgenus Penicillium sections Brevicompacta, Chrysogena, Fasciculata, Penicillium, and Roquefortorum.

Evaluation of renal in vitro models used in ochratoxin research

Ochratoxin A (OTA) induces renal carcinomas in rodents with a specific localisation in the S3 segment of proximal tubules and distinct early severe tissue alterations, which have been observed also in other species. Pronounced species- and sex-specific differences in toxicity occur and similar effects cannot be excluded in humans, however precise mechanism(s) remain elusive until today. In such cases, the use of in vitro models for mechanistic investigations can be very useful; in particular if a non-genotoxic mechanism of cancer formation is assumed which include cytotoxic effects. However, potential genotoxic mechanisms can also be investigated in vitro. A crucial issue of in vitro research is the choice of the appropriate cell model. Apparently, the cellular target of OTA is the renal proximal tubular cell; therefore cells from this tissue area are the most reasonable model. Furthermore, cells from affected species should be used and can be compared to cells of human origin. Another important parameter is whether to use primary cultures or to choose a cell line from the huge variety of cell lines available. In any case, important characteristics and quality controls need to be verified beforehand. Therefore, this review discusses the renal in vitro models that have been used for the investigation of renal ochratoxin toxicity. In particular, we discuss the choice of the models and the essential parameters making them suitable models for ochratoxin research together with exemplary results from this research. Furthermore, new promising models such as hTERT-immortalised cells and 3D-cultures are briefly discussed.

Comparative Ochratoxin Toxicity: A Review of the Available Data

Ochratoxins are a group of mycotoxins produced by a variety of moulds. Ochratoxin A (OTA), the most prominent member of this toxin family, was first described by van der Merwe et al. in Nature in 1965. Dietary exposure to OTA represents a serious health issue and has been associated with several human and animal diseases including poultry ochratoxicosis, porcine nephropathy, human endemic nephropathies and urinary tract tumours in humans. More than 30 years ago, OTA was shown to be carcinogenic in rodents and since then extensive research has been performed in order to investigate its mode of action, however, this is still under debate. OTA is regarded as the most toxic family member, however, other ochratoxins or their metabolites and, in particular, ochratoxin mixtures or combinations with other mycotoxins may represent serious threats to human and animal health. This review summarises and evaluates current knowledge about the differential and comparative toxicity of the ochratoxin group.

Foodborne mycotoxicoses, risk assessment and underestimated hazard of masked mycotoxins and joint mycotoxin effects or interaction

The existing hazard of joint mycotoxin exposure of animals/humans and the significance of masked mycotoxins in foods or feeds and their respective contributions to the development of some food born mycotoxicoses is briefly reviewed. The importance of joint mycotoxin interaction in the complex etiology of some foodborn mycotoxicoses is covered in depth. The toxicity of low contamination levels of some combinations of mycotoxins ingested often by farm animals was carefully studied. The appropriate hygiene control and the necessary risk assessment in regard to mycotoxin contamination of foods and feeds are briefly analyzed and some useful prophylactic measures and management of the risk of mycotoxin contamination, in addition to tolerable daily intakes are also described. A reference is also made to the most suitable methods of veterinary hygiene control in some practical situations in order to prevent mycotoxins contaminating commercial food commodities and endangering public health.

Ochratoxin A promotes porcine circovirus type 2 replication in vitro and in vivo

Ochratoxin A (OTA), a worldwide mycotoxin found in food and feeds, is a potent nephrotoxin in animals and humans. Porcine circovirus-associated disease (PCVAD), including porcine dermatitis and nephropathy syndrome, is a worldwide swine disease. To date, little is known concerning the relationship between OTA and porcine circovirus type 2 (PCV2), the primary causative agent of PCVAD. The effects of OTA on PCV2 replication and their mechanisms were investigated in vitro and in vivo. The results in vitro showed that low doses of OTA significantly increased PCV2 DNA copies and the number of infected cells. Maximum effects were observed at 0.05 μg/ml OTA. The results in vivo showed that PCV2 replication was significantly increased in serum and tissues of pigs fed 75 μg/kg OTA compared with the control group and pigs fed 150 μg/kg OTA. In addition, low doses of OTA significantly depleted reduced glutathione and mRNA expression of NF-E2-related factor 2 and γ-glutamylcysteine synthetase; increased reactive oxygen species, oxidants, and malondialdehyde; and induced p38 and ERK1/2 phosphorylation in PK15 cells. Adding N-acetyl-L-cysteine reversed the changes induced by OTA. Knockdown of p38 and ERK1/2 by their respective specific siRNAs or inhibition of p38 and ERK1/2 phosphorylation by their respective inhibitors (SB203580 and U0126) eliminated the increase in PCV2 replication induced by OTA. These data indicate that low doses of OTA promoted PCV2 replication in vitro and in vivo via the oxidative stress-mediated p38/ERK1/2 MAPK signaling pathway. This suggests that low doses of OTA are potentially harmful to animals, as they enhance virus replication, and partly explains why the morbidity and severity of PCVAD vary significantly in different pig farms.

A new ochratoxin A biodegradation strategy using Cupriavidus basilensis Őr16 strain

Ochratoxin-A (OTA) is a mycotoxin with possibly carcinogenic and nephrotoxic effects in humans and animals. OTA is often found as a contaminant in agricultural commodities. The aim of the present work was to evaluate OTA-degrading and detoxifying potential of Cupriavidus basilensis ŐR16 strain. In vivo administration of OTA in CD1 male mice (1 or 10 mg/kg body weight for 72 hours or 0.5 mg/kg body weight for 21 days) resulted in significant elevation of OTA levels in the blood, histopathological alterations- and transcriptional changes in OTA-dependent genes (annexinA2, clusterin, sulphotransferase and gadd45 and gadd153) in the renal cortex. These OTA-induced changes were not seen in animals that have been treated with culture supernatants in which OTA was incubated with Cupriavidus basilensis ŐR16 strain for 5 days. HPLC and ELISA methods identified ochratoxin α as the major metabolite of OTA in Cupriavidus basilensis ŐR16 cultures, which is not toxic in vivo. This study has demonstrated that Cupriavidus basilensis ŐR16 efficiently degrade OTA without producing toxic adventitious metabolites.

Filamentous Fungi and Mycotoxins in Cheese: A Review

Important fungi growing on cheese include Penicillium, Aspergillus, Cladosporium, Geotrichum, Mucor, and Trichoderma. For some cheeses, such as Camembert, Roquefort, molds are intentionally added. However, some contaminating or technological fungal species have the potential to produce undesirable metabolites such as mycotoxins. The most hazardous mycotoxins found in cheese, ochratoxin A and aflatoxin M1, are produced by unwanted fungal species either via direct cheese contamination or indirect milk contamination (animal feed contamination), respectively. To date, no human food poisoning cases have been associated with contaminated cheese consumption. However, although some studies state that cheese is an unfavorable matrix for mycotoxin production; these metabolites are actually detected in cheeses at various concentrations. In this context, questions can be raised concerning mycotoxin production in cheese, the biotic and abiotic factors influencing their production, mycotoxin relative toxicity as well as the methods used for detection and quantification. This review emphasizes future challenges that need to be addressed by the scientific community, fungal culture manufacturers, and artisanal and industrial cheese producers.

Simultaneous quantitative determination of multiple mycotoxins in cereal and feedstuff samples by a suspension array immunoassay

Mycotoxins produced by different species of fungi may coexist in single cereal and feedstuff samples, which could become highly toxic for humans and animals. In order to quantify four mycotoxins (zearalenone, fumonisin B1, deoxynivalenol, and aflatoxin B1) in cereal and feedstuff samples simultaneously, a new suspension array immunoassay was developed. Antimycotoxin monoclonal antibodies were conjugated to the surface of different encoding microspheres (19#, 37#, 39#, and 49#), and mycotoxin-protein conjugates were then coupled with biotin. Using streptavidin-phycoerythrin as a signal reporter protein, this direct competition multiple suspension array immunoassay was optimized. The results showed that the detection limits for zearalenone, fumonisin B1, deoxynivalenol, and aflatoxin B1 were 0.51, 6.0, 4.3, and 0.56 ng/mL, respectively, with detection ranges of 0.73-6.8, 11.6-110.3, 8.6-108.1, and 1.1-14.1 ng/mL, respectively. For the detection of the spiked samples, the recovery rates were between 92.3% and 115.5%. This method also shows a good correlation coefficient (r = 0.99, P < 0.01) with liquid chromatography-tandem mass spectrometry in the detection of toxins in commercial cereal and feedstuff samples. This suspension array immunoassay was high-throughput and accurate for the rapid quantitative detection of multiple mycotoxins in commercial cereal and feedstuff samples.

Deleterious effects of mycotoxin combinations involving ochratoxin A

Ochratoxin A (OTA) is a nephrotoxic mycotoxin with carcinogenic properties. Its presence was detected in various foodstuffs all over the world but with significantly higher frequency and concentrations in areas with endemic nephropathy (EN). Even though food is often contaminated with more than one mycotoxin, earlier studies focused on the occurrence and toxicology of only OTA. Only a limited number of surveys showed that OTA co-occurs in food with mycotoxins (citrinin-CIT, penicilic acid, fumonisin B1-FB1, aflatoxins-AF) which exert nephrotoxic, carcinogenic or carcinogen-promoting activity. This review summarises the findings on OTA and its co-occurrence with the mentioned mycotoxins in food as well as experimental data on their combined toxicity. Most of the tested mycotoxin mixtures involving OTA produced additive or synergistic effects in experimental models suggesting that these combinations represent a significant health hazard. Special attention should be given to mixtures that include carcinogenic and cancer-promoting mycotoxins.

Porcine/chicken or human nephropathy as the result of joint mycotoxins interaction

A survey was made of the literature concerning the occurrence and incidence of mycotoxic nephropathy in pigs and chicks in different countries. Various etiological factors contributing to the development of the disease were considered. The main nephrotoxic fungi as well as the specific conditions for their growth and toxins production were briefly described. A survey was made about the most frequent nephrotoxic fungal contaminants in various feedstuffs from plant origin. In addition, their natural quantities and importance for development of mycotoxic porcine/chick nephropathy (MPN/MCN) are also explored. In addition, a survey was made of the feedstuffs representing the most favorable environment for nephrotoxic fungal growth as well as the most favorable storehouse conditions for this fungal growth were shortly described. The significance of some underestimated fungal species, which can provoke kidney damage, was studied. The importance of joint mycotoxin interaction and newly identified fungal metabolites in the complex etiology of mycotoxic nephropathy ranged in some countries is deeply investigated. The toxicity of the low contamination levels of some combinations of mycotoxins often administered by pigs and chicks in the practice was carefully studied.

Validation study on urinary biomarkers of exposure for aflatoxin B1, ochratoxin A, fumonisin B1, deoxynivalenol and zearalenone in piglets

The multi-biomarker approach was used to validate urinary biomarkers in piglets administered boluses contaminated with mixtures of deoxynivalenol (DON), aflatoxin B1 (AFB1), fumonisin B1 (FB1), zearalenone (ZEA) and ochratoxin A (OTA) at different concentrations. Boluses contaminated with mycotoxins were prepared by slurrying and freezedrying feed material fortified with culture extracts of selected toxigenic fungi. Piglets were individually placed in metabolic cages to collect urine before gavage and 24 h post dose. Urine samples were hydrolysed with β-glucuronidase and analysed by a multi-biomarker LC-MS/MS method developed and validated to identify and measure biomarkers of FB1, OTA, DON, ZEA and AFB1. Urinary levels of FB1, OTA, DON + de-epoxy-deoxynivalenol, ZEA + alphazearalenol and aflatoxin M1 were selected as biomarkers of FB1, OTA, DON, ZEA and AFB1, respectively. Mean percentages of dietary mycotoxins excreted as biomarkers in 24 h post dose urine were 36.8% for ZEA, 28.5% for DON, 2.6% FB1, 2.6% for OTA and 2.5% for AFB1. A good correlation was observed between the amount of mycotoxins ingested and the amount of relevant biomarkers excreted in 24 h post dose urine. Linear dose-response correlation coefficients ranged between 0.68 and 0.78 for the tested couples of mycotoxin/biomarker. The good sensitivity of the LC-MS/MS method and the good dose-response correlations observed in this study permitted to validate the selected mycotoxin biomarkers in piglets at dietary levels close to the maximum permitted levels reported in Commission Directive 2003/100/EC for AFB1 and the guidance values reported in Commission Recommendation 2006/576/EC for DON, ZEA, OTA and FB1.

Biochemical changes in pig serum after ochratoxin A exposure

The objective of this study was to investigate the effect of ochratoxin A (OTA) on serum biochemical parameters of pigs during subchronic treatment with 300 μg OTA/kg of feed for 30 days. OTA treatment resulted in significantly higher (p < 0.05) serum levels of creatinine, urea, potassium and alkaline phosphatase, and significantly lower levels of glucose and total protein. These changes in serum biochemical parameters in treated pigs were indicative of impaired liver and kidney function caused by OTA exposure.

Human ochratoxin a biomarkers--from exposure to effect

Ochratoxin A (OTA) is a nephrotoxic mycotoxin that has received particular attention because of the toxic effects, widespread occurrence in contaminated food and feed chain, suspected causal effect on nephropathies, and, more recently, possibility of exposure by inhalation in domicile and occupational settings. Biomarkers have been used not only to ascertain the role of OTA in inducing chronic renal failure diseases, but also as a means to portray general populations' risk to the mycotoxin. Biomonitoring can thus be used to assess internal OTA exposure, with no need to recognize the main source of exposure. And so it presents undeniable advantages over the monitoring of external dose. With a just right understanding of biomarkers, it is possible to follow the trail from exposure right to effect, and so contribute both to surveillance plans and etiological studies. In recognition of the long serum half-life and the renal elimination of OTA, most of the studies present serum/plasma and/or urine analyses as markers of exposure. In this review and for each of these main matrices, a comparison over the advantages and disadvantages is offered. Although currently limited, an overview of the current knowledge on OTA biomarkers and the influential role of the individual characteristics, namely gender and age, along with season and geographical location is given. Attention is also given to the ongoing debate over the existence of OTA-DNA adducts, a biomarker of effective dose regarded as an alternative to biomarkers of internal dose. Although unspecific, OTA effect biomarkers are also reviewed.

Ochratoxin A in feed of food-producing animals: an undesirable mycotoxin with health and performance effects

Mycotoxins are secondary fungal metabolites, whose presence in feed- and foodstuffs is unavoidable. Ochratoxin A (OTA) is one of the known mycotoxins with greatest public health and agro-economic significance. Several toxic effects have been ascribed following exposure, namely nephrotoxicity, as well negative impacts in the performance of farm animals, resulting in major economic implications. Of no less importance for the route of human exposure that can also embody the carry-over of OTA from feed into animal-derived products is also a concern. For all these reasons the present article updates the worldwide occurrence of OTA in different raw ingredients and finished feed destined to food-producing animals. After that a brief characterization of specie susceptibility and the major rationales is made. An historical overview of field outbreaks linked to OTA exposure in farm animals, concerning the implicated feeds, contamination levels and major clinical and productivity effects is presented. Finally a review of the major animal health and performance potential impacts of animals being reared on contaminated feed is made allied to a perspective regarding its co-occurrence with other mycotoxins, and simultaneous parasitic and bacterial infections. Ultimately, this article aims to be instructive and draw attention to a mycotoxin so often neglected and elapsed from the list of differential diagnosis in farm practice. For the unpredictability and unavoidability of occurrence, OTA will definitely be an enduring problem in animal production.

Development and characterization of a monoclonal antibody against Ochratoxin B and its application in ELISA

A monoclonal antibody specific to ochratoxin B (OTB) was employed for the development of an indirect competitive OTB-ELISA. The optimized OTB-ELISA resulted in a limit of detection (LOD) for OTB of 3 µg/L (8 nM), a limit of quantification (LOQ) of 3.7 µg/L (10 nM), and a 50% inhibitory concentration (IC(50)) of 150 nM. Due to very low cross-reactivity to OTA (2.7%) and structurally related molecules (0%), this OTB-ELISA was found to be suitable to detect OTB with excellent precision in different matrices, i.e., beer, coffee and wine. Therefore, this OTB-ELISA will allow screening of OTB in food and feed products.

Ochratoxin A and aristolochic acid involvement in nephropathies and associated urothelial tract tumours

This review addresses the unresolved aetiology of several nephropathies and associated upper tract tumours diagnosed all over the world, but especially in the Balkan regions. Studies conducted over the last 35 years point to mycotoxins, mainly ochratoxin A (OTA) as the main culprit. Recent theories however have implicated aristolochic acids (AA). The aim of this review is to put forward arguments in favour of the mycotoxin theory and to show the incoherence of the AA theory. It discusses the differences between the epidemiology of Balkan endemic nephropathy (BEN) and aristolochic acid nephropathy (AAN); OTA and AA carcinogenicity; clinical and pathological effects induced by OTA and AA; sources of OTA contamination (food, air, drinking water); OTA- and AA-DNA adduct formation; the role of genetic polymorphisms; and the risk for young children.

Complex etiology and pathology of mycotoxic nephropathy in South African pigs

Spontaneous nephropathy in pigs seen in South Africa was found to have multi-mycotoxic etiology involving several mycotoxins such as ochratoxin A (OTA), penicillic acid (PA) and fumonisin B1 (FB1) in addition to a not yet identified mycotoxin. Contamination levels of OTA were comparatively low (67-75 μg/kg) in contrast to high contamination levels of FB1 (5,289-5,021 μg/kg) and PA (149-251 μg/kg). A heavy contamination with Gibberella fujikuroi var. moniliformis and Penicillium aurantiogriseum complex (mainly P. polonicum) was observed in the fed forages in contrast to the light contamination with Aspergillus ochraceus, P. verrucosum and P. citrinum. The pathomorphological picture of this nephropathy was found to differ from the classical description of mycotoxic porcine nephropathy as originally made in Scandinavia by the extensive vascular changes.

Review of secondary metabolites and mycotoxins from the Aspergillus niger group

Filamentous fungi in the Aspergillus section Nigri (the black aspergilli) represent some of the most widespread food and feed contaminants known but they are also some of the most important workhorses used by the biotechnological industry. The Nigri section consists of six commonly found species (excluding A. aculeatus and its close relatives) from which currently 145 different secondary metabolites have been isolated and/or detected. From a human and animal safety point of view, the mycotoxins ochratoxin A (from A. carbonarius and less frequently A. niger) and fumonisin B(2) (from A. niger) are currently the most problematic compounds. Especially in foods and feeds such as coffee, nuts, dried fruits, and grape-based products where fumonisin-producing fusaria are not a problem, fumonisins pose a risk. Moreover, compounds such as malformins, naptho-gamma-pyrones, and bicoumarins (kotanins) call for monitoring in food, feed, and biotechnology products as well as for a better toxicological evaluation, since they are often produced in large amounts by the black aspergilli. For chemical differentiation/identification of the less toxic species the diketopiperazine asperazine can be used as a positive marker since it is consistently produced by A. tubingensis (177 of 177 strains tested) and A. acidus (47 of 47 strains tested) but never by A. niger (140 strains tested). Naptho-gamma-pyrones are the compounds produced in the highest quantities and are produced by all six common species in the group (A. niger 134 of 140; A. tubingensis 169 of 177; A. acidus 44 of 47; A. carbonarius 40 of 40, A. brasiliensis 18 of 18; and A. ibericus three of three).

Occurrence of ochratoxin A and heavy metals in tissues associated with porcine nephropathy in Serbia

In order to find information on the occurrence of mycotoxic porcine nephropathy in Serbia, during a six month period (2006/2007) samples of blood, kidney and liver from individual animals were collected from healthy slaughtered pigs (n=90) and analysed by HPLC for ochratoxin A (OTA). In addition, the presence of nephrotoxic heavy metals such as cadmium, lead, mercury and arsenic were measured and the kidneys pathohistologically examined. Of the 90 liver samples, 26.6% contained OTA in the range of 0.22-14.5 ng/g. The incidence of OTA in serum and kidney were very similar (30 and 31.1%), but varied between 0.24-220.8 ng/ml and 0.17-52.5 ng/g, respectively. The presence of mercury was confirmed in 33.3% of kidney samples and concentrations ranged between 0.005-0.055 mg/kg, while cadmium was found less frequently (27.7% positive samples) but at higher levels (0.05-1.23 mg/kg). The presence of arsenic was found in only one sample, while lead was not detected in any sample. Histopathological examination of kidneys confirmed tubulopathies with oedema and cell vacuolisation. In addition, haemorrhages and necrosis of proximal kidney tubules' cells were found. These findings indicate that it is likely that most of the kidney injury is related to OTA and other nephrotoxic compounds which enhance the toxicity of OTA.

Effectiveness of mycotoxin sequestration activity of micronized wheat fibres on distribution of ochratoxin A in plasma, liver and kidney of piglets fed a naturally contaminated diet

A study was carried out to determine the ability of dietary micronized wheat fibres (MWF) to decrease the levels of ochratoxin A (OTA) in plasma, kidney and liver of piglets fed a naturally contaminated diet. A total of 96 piglets (weighting 11.4+/-1.5 kg) were fed one of four different diets for 28 days. Diets included (1) control diet, (2) control diet with MWF (1%), (3) OTA naturally contaminated diet (117.45+/-4.74 ng/g), (4) OTA naturally contaminated diet (118.13+/-2.85 ng/g) with MWF (1%). No difference in feed efficiency (P>0.05) could be observed between the different diets. The absolute weight of kidneys and liver were significantly higher in pigs fed the OTA-contaminated diet (diet 3) as compared to the control diet (diet 1) or to the control diet amended with MWF (diet 2) (P<0.05). However the use of MWF (diet 4) significantly protected against these weight changes. A significant protective effect of MWF was also observed in terms of OTA concentration in plasma (45.6% decrease), kidney (40.8% decrease) and liver (26.5% decrease). These results suggest that the addition of MWF is effective in decreasing the bioavailability of OTA from contaminated diets in piglets.

Mycotoxic porcine nephropathy and spontaneous occurrence of ochratoxin A residues in kidneys of slaughtered swine

In order to find information on the occurrence of mycotoxic porcine nephropathy in Serbia, during a six month period (2006/2007) samples of kidney from individual healthy slaughtered pigs were collected (n=90) and analyzed by HPLC for ochratoxin A. In addition, histological examinations were carried out. The incidence of OTA in kidney was 33,3% and varied between 0.17-52.5 ng/g. Histopathological examination of kidneys confirmed tubulopathies with oedema and cell vacuolization. In addition, hemorrhages and necrosis of proximal kidney tubules cells were found. These findings indicate that it is likely that most of the kidney injury is related to ochratoxin A and other nephrotoxic compounds which enhance the toxicity of OTA.

Survey of slaughtered pigs for occurrence of ochratoxin A and porcine nephropathy in Serbia

Samples of blood, kidney and liver were randomly selected from slaughtered pigs (n=90) and analyzed for ochratoxin A by HPLC. In addition, in order to obtain information on the occurrence of nephropathy, histological examinations were carried out. Of the 90 liver samples, 26.6% contained OTA in the range of 0.22-14.5 ng/g. The incidence of OTA in serum and kidney were very similar (31%, 33.3%), with a maximum concentration of 220.8 ng/mL, and 52.5 ng/g, respectively. Histopathological examination of kidneys confirmed tubulopathies with edema and cell vacuolization. In addition, hemorrhages and necrosis of proximal kidney tubules' cells were found.

Complex etiology, prophylaxis and hygiene control in mycotoxic nephropathies in farm animals and humans

Various etiological factors contributing to the development of mycotoxic nephropathy in farm animals and humans are reviewed. The possible synergistic effect between ochratoxin A (OTA) and other mycotoxins, as penicillic acid (PA) and fumonisin B(1) (FB(1)), contributing to this nephropathy is also considered and discussed. The most convenient ways of prophylaxis and various preventive measures against OTA contamination of feeds or foods are reviewed. A reference is made concerning the most successful methods of veterinary hygiene control in the slaughterhouses in order to prevent the entering of OTA in commercial channels with a view to human health. The economic efficacy of these prophylactic procedures is also considered. An evaluation of human exposure to OTA is made.

Ochratoxin A: An overview on toxicity and carcinogenicity in animals and humans

Ochratoxin A (OTA) is a ubiquitous mycotoxin produced by fungi of improperly stored food products. OTA is nephrotoxic and is suspected of being the main etiological agent responsible for human Balkan endemic nephropathy (BEN) and associated urinary tract tumours. Striking similarities between OTA-induced porcine nephropathy in pigs and BEN in humans are observed. International Agency for Research on Cancer (IARC) has classified OTA as a possible human carcinogen (group 2B). Currently, the mode of carcinogenic action by OTA is unknown. OTA is genotoxic following oxidative metabolism. This activity is thought to play a central role in OTA-mediated carcinogenesis and may be divided into direct (covalent DNA adduction) and indirect (oxidative DNA damage) mechanisms of action. Evidence for a direct mode of genotoxicity has been derived from the sensitive 32P-postlabelling assay. OTA facilitates guanine-specific DNA adducts in vitro and in rat and pig kidney orally dosed, one adduct comigrates with a synthetic carbon (C)-bonded C8-dG OTA adduct standard. In this paper, our current understanding of OTA toxicity and carcinogenicity are reviewed. The available evidence suggests that OTA is a genotoxic carcinogen by induction of oxidative DNA lesions coupled with direct DNA adducts via quinone formation. This mechanism of action should be used to establish acceptable intake levels of OTA from human food sources.

Toxicokinetics and toxicodynamics of ochratoxin A, an update

Ochratoxin A (OTA) is a mycotoxin produced by fungi of two genera: Penicillium and Aspergillus. OTA has been shown to be nephrotoxic, hepatotoxic, teratogenic and immunotoxic to several species of animals and to cause kidney and liver tumours in mice and rats. Because of differences in the physiology of animal species, wide variations are seen in the toxicokinetic patterns of absorption, distribution and elimination of the toxin. Biotransformation of OTA has not been entirely elucidated. At present, data regarding OTA metabolism are controversial. Several metabolites have been characterized in vitro and/or in vivo, whereas other metabolites remain to be characterized. Several major mechanisms have been shown as involved in the toxicity of OTA: inhibition of protein synthesis, promotion of membrane peroxidation, disruption of calcium homeostasis, inhibition of mitochondrial respiration and DNA damage. The contribution of metabolites in OTA genotoxicity and carcinogenicity is still unclear. The genotoxic status of OTA is still controversial because contradictory results were obtained in various microbial and mammalian tests, notably regarding the formation of DNA adducts. More recent studies are focused on the OTA ability to disturb cellular signalling and regulation, to modulate physiological signals and thereby to influence cells viability and proliferation. The present paper offers an update on these different issues. In addition since humans and animals are likely to be simultaneously exposed to several mycotoxins, especially through their diet, the little information available on the combined effects of OTA and other mycotoxins has also been reviewed.