Patulin immunotoxicology: effect on phagocyte activation and the cellular and humoral immune system of mice and rabbits

An overview of mycotoxicoses in rabbits

Mycotoxicoses are usually a consideration in large animal species but can affect companion animals as well. Due to increasing interest and the ease of using rabbits as laboratory models, a growing number of published experimental studies discuss the effects of various mycotoxins on this species. However, the available evidence is fragmented and heterogeneous, and has not recently been collated in a review, to my knowledge. Although mycotoxicoses in rabbits are typically subclinical, clinical signs can include weight loss, anorexia, gastrointestinal disorders, stunted growth, reproductive abnormalities, and susceptibility to infections. An antemortem diagnosis typically relies on a comprehensive clinical history, and assessment of clinical signs and relevant laboratory findings, with confirmation of exposure achieved through the measurement of mycotoxin concentrations in feed or target organs. My review focuses on the clinicopathologic and histopathologic effects of the mycotoxins most important in rabbits, including fumonisins, ochratoxins, aflatoxins, trichothecenes, and zearalenone. This review offers a thorough overview of the effects of mycotoxins in rabbits, serving as a one-stop resource for veterinary practitioners, diagnosticians, and researchers.

Immunosuppressive effects of the mycotoxin patulin in macrophages

Patulin (PAT) is a fungi-derived secondary metabolite produced by numerous fungal species, especially within Aspergillus, Byssochlamys, and Penicillium genera, amongst which P. expansum is the foremost producer. Similar to other fungi-derived metabolites, PAT has been shown to have diverse biological features. Initially, PAT was used as an effective antimicrobial agent against Gram-negative and Gram-positive bacteria. Then, PAT has been shown to possess immunosuppressive properties encompassing humoral and cellular immune response, immune cell function and activation, phagocytosis, nitric oxide and reactive oxygen species production, cytokine release, and nuclear factor-κB and mitogen-activated protein kinases activation. Macrophages are a heterogeneous population of immune cells widely distributed throughout organs and connective tissue. The chief function of macrophages is to engulf and destroy foreign bodies through phagocytosis; this ability was fundamental to his discovery. However, macrophages play other well-established roles in immunity. Thus, considering the central role of macrophages in the immune response, we review the immunosuppressive effects of PAT in macrophages and provide the possible mechanisms of action.

The Nrf1 transcription factor is induced by patulin and protects against patulin cytotoxicity

Patulin is a mycotoxin produced by a variety of molds that is found in various food products. The adverse health effects associated with exposure to patulin has led to many investigations into the biological basis driving the toxicity of patulin. Nevertheless, the mechanisms through which mammalian cells resists patulin-mediated toxicity is poorly understood. Here, we show that loss of the Nrf1 transcription factor renders cells sensitive to the acute cytotoxic effects of patulin. Nrf1 deficiency leads to accumulation of ubiquitinated proteins and protein aggregates in response to patulin exposure. Nrf1 expression is induced by patulin, and activation of proteasome genes by patulin is Nrf1-dependent. These findings suggest the Nrf1 transcription factor plays a crucial role in modulating cellular stress response against patulin cytotoxicity.

Toxic effects of patulin on mouse oocytes and its possible mechanisms

Patulin is a secondary metabolite mainly secreted by fungi and is the most common mycotoxin found in apples and apple-based products. For the past few years, numerous studies suggested the wide distribution and toxicity of patulin. In this study, we investigated the toxic effect of patulin on mouse oocytes and its possible mechanisms. The results showed that patulin treatment did not affect meiotic resumption, but inhibited oocyte maturation as indicated by failure of first polar body extrusion. Further mechanistic study showed that patulin treatment disturbed normal spindle assembly, chromosome alignment and morphology. We also found increased oxidative stress by testing the level of ROS and decreased mitochondrial membrane potential, indicating mitochondria dysfunction. In summary, our results suggest that patulin treatment causes oocyte meiotic arrest by disturbing normal spindle assembly and chromosome alignment, which may be caused by dysfunctions of mitochondria.

Natural Thiols, but Not Thioethers, Attenuate Patulin-Induced Endoplasmic Reticulum Stress in HepG2 Cells

Patulin, a mycotoxin, is known to have cytotoxic effects, but few studies have focused on the involvement of the endoplasmic reticulum (ER) stress response in patulin toxicity and the natural compounds that attenuate it in HepG2 cells. This study tested the ability of patulin to induce ER stress, and that of four thiols and three thioethers to attenuate patulin-induced ER stress in HepG2 cells. Patulin dose-dependently inhibited cell proliferation (IC₅₀, 8.43 μM). Additionally, patulin was found to increase the expression levels of ER stress-related genes and/or protein markers, including BiP, CHOP, and spliced XBP1, in HepG2 cells compared to the vehicle control, indicating its potential in ER stress induction. Patulin-induced cytotoxicity in HepG2 cells was reduced by naturally occurring thiol compounds (glutathione, L-acetyl-L-cysteine, cysteine, and captopril), but not by thioether compounds (sulforaphane, sulforaphene, and S-allyl-L-cysteine). Patulin-thiol co-treatment decreased CHOP expression and BiP and CHOP levels in HepG2 cells but did not alter BiP expression. Spliced XBP1 expression was decreased by patulin-thiol co-treatment. Thus, patulin induced ER stress in HepG2 cells and thiols, but not in thioethers, attenuated patulin-induced ER stress.

Effects of ascorbic acid on patulin in aqueous solution and in cloudy apple juice

Degradation of the mycotoxin patulin (PAT) and the generation of (less toxic) breakdown products, such as (E/Z)-ascladiol (ASC-E/Z) and desoxypatulinic acid (D-PAT), can occur due to chemical, physical and biological treatments. Our study focused on the chemical degradation of PAT in the presence of ascorbic acid (AA) both for pure PAT standard in acidified aqueous solution and for PAT-contaminated cloudy apple juice (CAJ) (obtained via addition of apple mash produced from apples inoculated with Penicillium expansum). Within this framework, different concentrations of AA were evaluated, as well as the presence/absence of oxygen and different storage temperatures. In order to do so, an in-house methodology allowing a good separation of PAT from its reaction and breakdown products was optimized first. The highest PAT reduction (60%) in CAJ with an initial PAT concentration of 100 μg/kg and 0.25% (w/v) AA was achieved after 6 days of incubation at 22 °C in the presence of oxygen. It was also found that the treatment by AA resulted in the generation of degradation products less toxic than PAT (such as (E/Z)-ASC). In conclusion, AA used to improve numerous product quality aspects (e.g. colour (less browning), nutritional value, etc.) and considered as a safe food additive (Food and Drug Administration (FDA) (1999)) has an effect on PAT degradation. It was shown that such degradation generated less toxic compounds in the presence of oxygen. In view of consumers' safety, fortification of apple juice (and possibly apple-based products) with AA could be helpful within an integrated system to ensure products with low levels of patulin. The optimum conditions for such an approach within a legal and practical point of view need to be further explored.

Mycotoxin patulin in food matrices: occurrence and its biological degradation strategies

Patulin is a mycotoxin produced by a number of filamentous fungal species. It is a polyketide secondary metabolite which can gravely cause human health problems and food safety issues. This review deals with the occurrence of patulin in major food commodities from 2008 to date, including historical aspects, source, occurrence, regulatory limits and its toxicity. Most importantly, an overview of the recent research progress about the biodegradation strategies for contaminated food matrices is provided. The physical and chemical approaches have some drawbacks such as safety issues, possible losses in the nutritional quality, chemical hazards, limited efficacy, and high cost. The biological decontamination based on elimination or degradation of patulin using yeast, bacteria, and fungi has shown good results and it seems to be attractive since it works under mild and environment-friendly conditions. Further studies are needed to make clear the detoxification pathways by available potential biosorbents and to determine the practical applications of these methods at a commercial level to remove patulin from food products with special reference to their effects on sensory characteristics of foods.

Development and optimization of a group-specific loop-mediated isothermal amplification (LAMP) assay for the detection of patulin-producing Penicillium species

The mycotoxin patulin is a toxic fungal secondary metabolite occurring in food worldwide. Methods for rapid, simple and specific detection of patulin-producing fungi in food and feed are therefore urgently needed. In the current study, a loop-mediated isothermal amplification (LAMP) assay based on the isoepoxydon dehydrogenase (idh) gene of the patulin biosynthetic pathway was developed and optimized for the group-specific detection of patulin-producing Penicillium species. By testing purified DNA of 174 fungal strains representing 31 genera, the assay was demonstrated to be highly specific for the detection of patulin-producing species in Penicillium, Byssochlamys and Paecilomyces. The assay had a detection limit of 2.5 pg of purified genomic DNA of P. expansum per reaction. Moreover, the assay was demonstrated to detect patulin-producers when conidia were directly added to the master mix as template without any sample preparation. The applicability of the assay in food analyses was successfully tested on artificially contaminated grapes and apples requiring minimal sample preparation. A screening of grapes from the 2018 harvest from different locations in Germany revealed no presence of patulin-producers. The developed LAMP assay is a promising tool for rapid diagnosis in quality control applications in the food and beverage industry.

Low dose exposure of patulin and protective effect of epicatechin on blood cells in vitro

In the present study, we aimed to assess antioxidant status in erythrocytes in vitro after patulin (PAT) and epicatechin exposure by measuring antioxidant enzymes (superoxide-dismutase - SOD, glutathione peroxidase - GPx and catalase - CAT) and parameters associated with oxidative stress (malondialdehyde - MDA and ROS). We also investigated the effect of PAT on viability and count of lymphocytes and lymphocyte subpopulations in rabbit blood in vitro. Whole blood of rabbits was used for analysis of antioxidant changes in rabbit erythrocytes after epicatechin and PAT treatment (separately or in combination, at concentrations of 0.2; 2; 20; 200 µg mL^-1 of epicatechin and 0.5; 5; 10 µg mL^-1 of PAT). Whole blood of rabbits was also used for analysis of count and viability of lymphocytes after PAT treatment at concentrations of 10; 25 and 50 µg mL^-1. Results from our experiment confirmed the ability of epicatechin to protect cells against oxidative stress and lipoperoxidation. Our findings indicate that mycotoxin PAT in low concentrations did not affect the activity of antioxidant enzymes in erythrocytes of rabbits significantly. Only slight non-significant changes in lymphocytes count after treatment with low doses of PAT in rabbit blood were observed.

Glutathione Reduction of Patulin-Evoked Cytotoxicity in HEK293 Cells by the Prevention of Oxidative Damage and the Mitochondrial Apoptotic Pathway

Patulin (PAT) is a mycotoxin frequently detected in moldy fruits and fruit products. This study investigated the protective role of glutathione (GSH), an antioxidant agent, against PAT-induced cytotoxicity and its potential mechanisms in HEK293 cells. The obtained results showed that the addition of GSH significantly increased cell viability and decreased apoptosis induced by PAT. Additionally, GSH decreased intracellular ROS and mitochondrial ROS overproduction, suppressed the decline of the mitochondrial membrane potential, and maintained cellular ATP contents. GSH prevented the impairment of mitochondrial oxidative-phosphorylation system and, especially, enhanced the mRNA and protein levels of electron-transport-chain complex III (UQCRC2) and complex V (ATP5, ATP6 and ATP8). Furthermore, GSH increased endogenous GSH contents; enhanced the antioxidant-enzyme activities of SOD, CAT, GR, and GPx; and modulated oxidative damage. These results suggest that GSH reduces PAT-induced cytotoxicity via inhibition of oxidative damage and the mitochondrial apoptotic pathway in HEK293 cells.

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.

Crocin and quercetin prevent PAT-induced apoptosis in mammalian cells: Involvement of ROS-mediated ER stress pathway

Patulin (PAT) is a secondary metabolite produced by several species of the genera of Penicillium, Aspergillus, and Byssochlamys that can be found in rotting fruits, especially in apples and apple-based products. Exposure to this mycotoxin has been reported to induce intestinal and kidney injuries. The mechanism underlying such toxicity has been linked to the induction of apoptosis which occurred with reactive oxygen species production and endoplasmic reticulum (ER) stress induction. This study aimed to evaluate the effect of the two common dietary compounds Quercetin (QUER), a natural flavonoid, and Crocin (CRO), a natural carotenoid, on PAT-induced toxicity in human colon carcinoma (HCT116) and embryonic kidney cells (HEK293). We showed that antioxidant properties of QUER and CRO help to prevent ER stress activation and lipid peroxidation as evidenced by the reduction in GRP78 and GADD34 expressions and the decrease in malondialdehyde production. Furthermore, we demonstrated their ability to re-establish the loss of the mitochondrial membrane potential to inhibit caspase 3 activation and DNA fragmentation. © 2015 Wiley Periodicals, Inc. Environ Toxicol 31: 1851-1858, 2016.

Crocin protects the liver and kidney from patulin-induced apoptosis in vivo

Patulin (PAT) is a mycotoxin mainly produced by Aspergillus, Penicillium, and Bissochlamys. Given the high risk associated with this mycotoxin, its potential effects have been investigated by many studies. It is known to be teratogenic, mutagenic, and genotoxic, and it has been shown to induce damages in several organs in experimental animals. Our aim was to investigate the preventive effect against PAT-induced apoptosis in vivo using natural carotenoid, Crocin (CRO). Mice were divided into six groups: a control group, a "PAT alone" group, a "CRO alone" group, and a "PAT plus CRO" groups (pre-treatment conditions). Our results showed that CRO restored the normal levels of biochemical parameters in the liver and kidney. The analysis of the protein expression in these organs revealed that PAT-induced toxicity promotes the induction of apoptosis via the increase in P53, Bax, and cytochrome C and the decrease in Bcl2 expressions. We also found that PAT triggered caspase 3 activation and DNA fragmentation. However, pre-treatment with CRO demonstrated a reduction in the induction of apoptosis via the regulation of all tested biomarkers demonstrating that CRO is effective in the protection against PAT hazards. This could be relevant, particularly with the emergent demand for natural products which may counteract the detrimental toxic effects and therefore prevents multiple human diseases.

Patulin induces apoptosis through ROS-mediated endoplasmic reticulum stress pathway

Patulin (PAT) is a toxic metabolite produced by several filamentous fungi of the genera of Penicillium, Aspergillus, and Byssochlamys. PAT is the most common mycotoxin found in apples and apple-based products including juice, compotes, cider, and baby food. Exposure to this mycotoxin has been reported to induce intestinal and kidney injuries. This study investigated the mechanism of PAT-induced toxicity in human colon carcinoma (HCT116) and embryonic kidney cells (HEK293). We demonstrated that PAT activated endoplasmic reticulum (ER) and unfolded protein response as evidenced by up-regulation of GRP78 and GADD34, splicing of XBP1 mRNA, and expression of the proapoptotic factor CHOP. This ER stress response was accompanied by the induction of the mitochondrial apoptotic pathway. Apoptosis occurred with ROS production, drop in mitochondrial membrane potential and caspase activation. Further, we showed that deficiency of the proapoptotic protein Bax or Bak protected cells against PAT-induced apoptosis. The treatment of cells with the ROS scavenger N-acetyl cysteine inhibits the ER stress response and prevents mitochondrial apoptosis. Collectively, our data provide new mechanistic insights in the signaling pathways of the cell death induced by PAT and demonstrate that PAT induces cytotoxicity through a ROS-dependent mechanism involving ER stress and activation of mitochondrial apoptotic pathway in human intestinal and kidney cells.

Examination of the taxonomic position of Penicillium strains used in blue cheese production based on the partial sequence of β-tubulin

Penicillium roqueforti is a well known starter used for blue cheese production. Two closely related species, P. carneum and P. paneum, were previously classified as varieties of P. roqueforti. Penicillium roqueforti does not produce patulin, a mycotoxin harmful for human health, whereas both P. carneum and P. paneum actively produce this toxin. From the viewpoint of food safety, it is thus important to confirm that P. carneum and P. paneum are not used for cheese production. In the present study, the taxonomic position of Penicillium strains used for blue cheese production was examined on the basis of the partial sequence of β-tubulin. Twenty-eight Penicillium strains isolated from blue cheeses were investigated. All the examined strains belonged to P. roqueforti. Therefore, the Penicillium strains used for production of the blue cheese samples examined here do not negatively impact on human health.

Kinetics of the thermal degradation of patulin in the presence of ascorbic acid

Degradation of the mycotoxin patulin between 25 and 85 °C without and with added ascorbic acid was studied, and the effectiveness of linear and nonlinear models for predicting reaction rates was compared. In agreement with previous reports, ascorbic acid significantly increased (P ≤ 0.05) the rate of patulin degradation at all temperatures studied. The data for patulin degradation in the absence of ascorbic acid were adequately modeled using a zero-order linear kinetic model. However, the predictive abilities of zero and higher-order linear models were not adequate to describe the more complex reactions that likely occurred when ascorbic acid was added. In contrast, the nonlinear Weibull model adequately described the patulin-ascorbic acid reaction throughout the temperature range studied. Zero-order rate constants and Weibull scale values for each of the respective reactions followed the Arrhenius law. Activation energies of 58.7 ± 3.9 and 29.6 ± 1.9 kJ mol⁻¹ for the reaction without and with ascorbic acid, respectively, confirmed decreased patulin stability in the presence of ascorbic acid and suggested that the mechanisms for the 2 degradation reactions were different.

EGFR-mediated Akt and MAPKs signal pathways play a crucial role in patulin-induced cell proliferation in primary murine keratinocytes via modulation of Cyclin D1 and COX-2 expression

Patulin (PAT), a present day major contaminant of commercial apple and apple products is reported to be carcinogenic, embryotoxic, and immunotoxic. While oral and inhalation are considered to be the most prevalent routes of exposure to this toxin, exposure through skin is now being extensively investigated. Our previous study showed that short-term dermal exposure to PAT resulted in toxicological injury to the skin, while long-term exposure induced skin tumorigenesis. In this study, we explore the mechanism involve in proliferation of mouse keratinocytes by PAT. Our study revealed that PAT rapidly induces phosphorylation of EGFR, activation of the Ras/MAPKs, and Akt pathways. This in-turn leads to the activation of NF-κB/AP-1 transcription factors which then binds to the promoter region of the cell growth regulatory genes Cyclin D1 and COX-2 inducing their expression leading ultimately to PMKs proliferation. Inhibition of EGFR or the Ras/MAPKs, PI3/Akt pathways with different pharmacological inhibitors or knockdown of NF-κB, c-jun, c-fos, Cyclin D1, and COX-2 with siRNA inhibited PAT-induced PMKs proliferation.

Patulin in apple juice and its risk assessments on albino mice

The contamination of apple juice with patulin mycotoxin is a major risk factor in food safety. This study focuses to assess the biochemical and histopathological effects of patulin in apple juice samples collected from different outlets retailing in Jeddah, Kingdom of Saudi Arabia. On the basis of the selected dose level, 152.5 ppb patulin/ml was administered daily orally for up to 6 weeks to male albino mice. The exposure to contaminated samples revealed significant elevation of all the studied blood parameters (alanine aminotransferase, aspartate aminotransferase and alkaline phosphatase activities as well as creatinine, urea and uric acid contents). On the other hand, and with regard to the accumulated neuronal toxicity of the tested dose level, the toxic signs were recorded as significant increase in the aggressive and locomotor behavioral changes. In addition, the brain areas monoamines concentration revealed variable increased changes. The potential maximal changes in norepinephrine, dopamine and serotonin5-hydroxytryptamine levels attained in cortex, hypothalamus, striatum, hippocampus, midbrain and pons and medulla were assessed. Moreover, the histological examination revealed degeneration and necrosis in liver tissues and degenerated glomeruli and hemorrhage between the tubules of the cortical region in kidney tissues. The study declared that patulin-contaminated (152.5 ppb) apple juice exhibited liver, kidney and neurotoxicological effects in 6 weeks orally administered mice.

Some factors influencing patulin production by Penicillium expansum in pome fruits

BACKGROUND

The objective of our study was to examine the effects of Penicillium expansum on patulin production in relation to isolates, species and cultivar type, incidence and severity of decay. In addition, patulin production at different incubation times and its diffusion were also investigated. These factors were evaluated in pome fruits inoculated with P. expansum and kept at 20 °C for short periods of time.

RESULTS

The ability of five P. expansum isolates to grow and produce patulin in inoculated Golden Delicious apples varied among the strains from below the limit of quantification to 662 µg kg(-1). Variety and species of pome fruits influenced patulin production. P. expansum isolate PE97.IT produced a higher patulin content in apples than in pears. The highest patulin production was 386 µg kg(-1) in Golden Delicious. No blue mould symptom appeared in pears inoculated with P. expansum and no patulin was detected after 3 days at 20 °C. However, patulin increased with incubation time after 6 and 8 days. No patulin was detected in healthy pear tissue but it was high in the decayed area.

CONCLUSION

Since patulin production is associated primarily with infected rotten tissue, patulin control is possible by using healthy fruits, sorting damaged and rotten fruits before processing.

Biosynthesis and toxicological effects of patulin

Patulin is a toxic chemical contaminant produced by several species of mold, especially within Aspergillus, Penicillium and Byssochlamys. It is the most common mycotoxin found in apples and apple-derived products such as juice, cider, compotes and other food intended for young children. Exposure to this mycotoxin is associated with immunological, neurological and gastrointestinal outcomes. Assessment of the health risks due to patulin consumption by humans has led many countries to regulate the quantity in food. A full understanding of the molecular genetics of patulin biosynthesis is incomplete, unlike other regulated mycotoxins (aflatoxins, trichothecenes and fumonisins), although the chemical structures of patulin precursors are now known. The biosynthetic pathway consists of approximately 10 steps, as suggested by biochemical studies. Recently, a cluster of 15 genes involved in patulin biosynthesis was reported, containing characterized enzymes, a regulation factor and transporter genes. This review includes information on the current understanding of the mechanisms of patulin toxinogenesis and summarizes its toxicological effects.

Evaluation of patulin toxicity in the thymus of growing male rats

Patulin is a mycotoxin produced by several Penicillium, Aspergillus, and Byssachlamys species growing on food products. In this study, we investigated the effects of patulin on the thymus of growing male rats aged five to six weeks. The rats were receiving it orally at a dose of 0.1 mg kg-1 bw a day for either 60 or 90 days. At the end of the experiment, the thymus was examined for histopathology by light microscopy and for epidermal growth factor (EGF) and its receptor (EGFR) by immunolocalisation. For morphometry we used the Bs200prop program to analyse images obtained with the Olympus BX51 light microscope. Cell ultrastructure was studied by electron microscopy. In rats treated with patulin, the thymus showed haemorrhage, plasma cell hyperplasia, a dilation and fibrosis in the cortex, enlarged interstitial tissue between the thymic lobules, enlarged fat tissue, thinning of the cortex, and blurring of the cortico-medullary demarcation. Electron microscopy showed signs of cell destruction, abnormalities of the nucleus and organelles, and loss of mitochondrial cristae. However, no differences were observed in thymus EGF and EGFR immunoreactivity between treated and control rats.

Toxicology of mycotoxins

Humans are exposed to mycotoxins via ingestion, contact and inhalation. This must have occurred throughout human history and led to severe outbreaks. Potential diseases range from akakabio-byo to stachybotryotoxicosis and cancer. The known molecular bases of toxicology run the gamut of 23 compounds, from aflatoxins (AFs) to zearalenone, ochratoxin A and deoxynivalenol. Ergotism is one of the oldest recognized mycotoxicosis, although mycotoxin science only commenced in the 1960s with the discovery of AFs in turkey feed. AFs are carcinogenic. Some others are suspected carcinogens. The effects of mycotoxins are acute or chronic in nature. Mycotoxins are well known in the scientific community, although they have a low profile in the general population. An incongruous situation occurs in United States where mycotoxins from "moldy homes" are considered to be a significant problem, although there is a general debate about seriousness. This contrasts with the thousands of deaths from mycotoxins that occur, even now, in the technologically less developed countries (e.g., Indonesia, China, and Africa). Mycotoxins are more toxic than pesticides. Studies are moving from whole animal work to investigating the biochemical mechanisms in isolated cells, and the mechanisms of toxicity at the molecular level are being elucidated. The stereochemical nature of AFs has been shown to be important. In addition, the effect of multiple mycotoxins is being increasingly investigated, which will more accurately represent the situation in nature. It is anticipated that more fungal metabolites will be recognized as dangerous toxins and permitted statutory levels will decrease in the future.

Influence of storage conditions of apples on growth and patulin production by Penicillium expansum

Penicillium expansum causes blue mould rot, a serious post-harvest disease of apples, and is the main producer of the mycotoxin patulin. The present study aimed to determine the influence of storage conditions (i.e. temperature and O(2) level) on growth and patulin production by different P. expansum strains on a simulation medium and on apples. Growth was strongly influenced by the temperature, while the used atmosphere (20, 3, and 1% O(2); <1% CO(2)) had no effect. Optimal growth was observed at 25 degrees C for every strain tested. Patulin production was stimulated when the temperature decreased (from 20 to 10 or 4 degrees C), while a further decrease of the temperature to 1 degrees C caused a reduction in patulin production. The temperature at which the stimulation was changed into suppression was strain dependent. Similar results were observed for the O(2) level. A reduction of the O(2) level from 20 to 3% O(2) could stimulate or suppress patulin production depending on the strain, while a clear decrease of the patulin production was observed when the O(2) level was reduced from 3 to 1%. These results show that the induction of limited stress to the fungus, such as lowering the temperature or lowering the O(2) levels stimulates patulin production. However, the combination of different stress conditions (e.g. low temperature and low O(2)) will result in a reduced formation of the toxin. The combination of stress conditions, at which the transition from stimulation to suppression is observed, is strain dependent. Moreover, patulin production is characterized by a high natural variability. The presented results show that the temperature and O(2) level has to be as low as possible during the storage of apples in order to suppress patulin production and to guarantee food safety.

Variability and uncertainty assessment of patulin exposure for preschool children in Flanders

The objective of the present study was to evaluate the patulin exposure of children consuming organic, handcrafted or conventional apple juice through a probabilistic approach and to evaluate the effectiveness of several risk management options aiming to reduce the risk for children due to patulin exposure. However, a large part of the data on patulin contamination of apple juice fell under the limit of detection (LOD). Different methods were tested to deal with these so-called left censored data and a uniform distribution with uncertain bounds was selected to handle this censorship. Variability and uncertainty assessment of patulin exposure showed that 0.9% [90% confidence interval (CI): 0.3-1.8%] of the children consuming only organic apple juice exceed the tolerable daily intake (TDI). For consumers of conventional and handcrafted apple juice this was respectively 0.1% [90% CI: 0-0.3%] and 0% [90% CI: 0-0.2%]. Reduction of the patulin contamination in apple juice to concentrations below 25 microg/kg reduced the percentage of the children exceeding the TDI to 0% [90%CI: 0-0.2%] for organic apple juice. Reduction of the apple juice consumption was less effective than a reduction of the patulin concentration in apple juice and is only useful when the patulin concentration of apple juice is below 25 microg/kg.

Activity of trans-2-hexenal against Penicillium expansum in 'Conference' pears

AIMS

To investigate the effects of trans-2-hexenal on blue mould disease, patulin content and fruit quality in 'Conference' pears.

METHODS AND RESULTS

Fruits, wounded and inoculated with Penicillium expansum or non-inoculated, were exposed to trans-2-hexenal vapour treatment (12.5 microl l(-1)) at 20 degrees C. A greater reduction of decay was obtained by treatment application 24 or 48 h after inoculation, in contrast trans-2-hexenal application 2 h after inoculation was ineffective. Fruit storage temperature (-1 degrees C) after treatment did not affect the antifungal activity. Although 2-h exposure to trans-2-hexenal was effective in reducing blue mould, an exposure of at least 8 h was required to reduce fruit patulin content. Treatments did not affect fruit physical-chemical characteristics. After 6 days at 20 degrees C following exposure, trans-2-hexenal residue in treated fruits was less than the natural content of the compound in unripe fruits.

CONCLUSIONS

trans-2-Hexenal treatment is effective in the reduction of blue mould infections and patulin content in Conference pears when applied 24-48 h after pathogen inoculation.

SIGNIFICANCE AND IMPACT OF THE STUDY

trans-2-Hexenal could be a natural alternative to fungicides in the control of P. expansum infections. Further work is needed to study the methods and conditions avoiding the persistence of off-odours and off-flavours in pears after their exposure to trans-2-hexenal vapours.

Occurrence of patulin in organic, conventional, and handcrafted apple juices marketed in Belgium

The aim of this research was to compare the occurrence of patulin in a large group of organic, conventional, and handcrafted apple juices marketed in Belgium. An analytical procedure based on high-performance liquid chromatography with UV detection was validated and used to analyze 177 apple juice samples: 65 organic, 90 conventional, and 22 handcrafted. Patulin was detected in 22 samples (12%), and quantification was possible in 10 (6%) of these samples. The patulin content was higher than the European legal limit of 50 microg/liter in two samples of organic apple juice. Although, the incidence of patulin in organic (12%), conventional (13%), and handcrafted (10%) apple juices was not significantly different (P = 0.863), the mean concentration of patulin in contaminated samples was significantly higher in organic (43.1 microg/liter) than in conventional (10.2 microg/liter) (P = 0.02) and handcrafted (10.5 microg/liter) (P = 0.037) apple juice. The highest patulin concentrations were found in the most expensive apple juices because of the higher price of organic apple juice. This relation was not observed when only conventional apple juices were analyzed.

Effects of patulin on thymus capillary of rats

Patulin is a mycotoxin that is produced by species of Penicillum, Aspergillus, and Byssochylamys molds that may grow on a variety of foods including fruit, grains and cheese. Patulin, at a dose of 0.1 mg kg(-1) bw day(-1) was administered orally to growing male rats aged 5-6 weeks for a period of 60 or 90 days. The dose of patulin used in the present study was based on estimated human exposure levels. At the end of these periods, the thymus glands of patulin-treated and control Wistar rats were removed and ultrastructural changes in capillary cells of the thymus of patulin-treated Wistar rats were determined by electron microscopy. The walls of thymus capillaries of the 60-day patulin-treated rat groups (P-60) exhibited degeneration observable in electron microscopic sections. For example, loss of cytoplasm and mitochondrial cristae of cells, swollen endothelial cells, increased thickness of the basement membrane, closed lumen of capillaries, accumulation of fibrous material at the periphery of the capillaries and nuclear anomalies were seen in these sections. Such degeneration and changes were also observed in sections of capillaries of the 90-day patulin-treated rat groups (P-90). The levels of degeneration of endothelial cell nucleus of P-90 were greater than those of P-60. This study demonstrated the ultrastructural degeneration of thymus capillary cells of patulin-treated rats. The results obtained from this study may provide a guide to research dealing with the toxic effects of patulin on tissue and organ ultrastructure.

The effects of the Penicillium mycotoxins citrinin, cyclopiazonic acid, ochratoxin A, patulin, penicillic acid, and roquefortine C on in vitro proliferation of porcine lymphocytes

The in vitro effect of each of the Penicillium mycotoxins citrinin (CIT), cyclopiazonic acid (CPA), ochratoxin A (OTA), patulin (PAT), penicillic acid (PIA) and roquefortine C (RQC) on mitogen induced lymphocyte proliferation was determined using purified lymphocytes from 6 piglets. Dose response curves for each mycotoxin were generated and the concentrations producing 50% inhibition of cell proliferation (IC(50)) were estimated. OTA and PAT were the most potent toxins with IC(50) of 1.3 and 1.2 micromol/l, respectively (0.52 and 0.18 mg/l, respectively). Based on molar concentrations, OTA was 15, 30, 40, and 65 times more potent as an inhibitor than PIA, CIT, CPA and RQC, respectively.

Apple quality, storage, and washing treatments affect patulin levels in apple cider

Patulin is a mycotoxin produced primarily by Penicillium expansum, a mold responsible for rot in apples and other fruits. The growth of this fungus and the production of patulin are common in fruit that has been damaged. However, patulin can be detected in visibly sound fruit. The purpose of this project was to determine how apple quality, storage, and washing treatments affect patulin levels in apple cider. Patulin was not detected in cider pressed from fresh tree-picked apples (seven cultivars) but was found at levels of 40.2 to 374 microg/liter in cider pressed from four cultivars of fresh ground-harvested (dropped) apples. Patulin was not detected in cider pressed from culled tree-picked apples stored for 4 to 6 weeks at 0 to 2 degrees C but was found at levels of 0.97 to 64.0 microg/liter in cider pressed from unculled fruit stored under the same conditions. Cider from controlled-atmosphere-stored apples that were culled before pressing contained 0 to 15.1 microg of patulin per liter, while cider made from unculled fruit contained 59.9 to 120.5 microg of patulin per liter. The washing of ground-harvested apples before pressing reduced patulin levels in cider by 10 to 100%, depending on the initial patulin levels and the type of wash solution used. These results indicate that patulin is a good indicator of the quality of the apples used to manufacture cider. The avoidance of ground-harvested apples and the careful culling of apples before pressing are good methods for reducing patulin levels in cider.

Patulin in apple-based foods: occurrence and safety evaluation

Patulin is a mycotoxin produced by certain species of Penicillium and Aspergillus, often detectable in mouldy fruits and their derivatives. On the basis of a PMTDI of 0.4 microgram/kg bw, limit values of 50 micrograms/kg or 50 micrograms/l of patulin have been set in fruit derivatives. To estimate the quantity of patulin that can be taken in with the diet, we analysed by HPLC samples of apples and apple derivatives which are most likely to be contaminated with patulin. In apple juices and in homogenized baby-foods, the mycotoxin concentration was always below the established limits, while in some samples of juice with pulp the mycotoxin content exceeded the safe levels. In rotten apples, not only was the amount of patulin extraordinarily high in the rotten area, but the mycotoxin had also spread to the part unaffected by mould. The data presented in this study indicate that the intake of patulin with apple derivatives is usually below the tolerable level of 0.4 microgram/kg bw/day, but since the patulin content in apples can vary considerably, the quality of fruits used in the production of apple derivatives should be strictly controlled in order not to exceed the safe limits.

Immunological evaluation of the mycotoxin patulin in female B6C3F1 mice

Patulin is a mycotoxin produced by many fungal species of the genera Penicillium, Aspergillus and Bryssochamys. Previous literature reports have suggested that patulin is toxic to the immune system. The studies presented were conducted to provide a comprehensive assessment of the effects of patulin on the immune system. Unlike previous reports, the doses of patulin used (0.08, 0.16, 0.32, 0.64, 1.28 and 2.56 mg/kg) were based on predicted human exposure levels. Female B6C3F1 mice were exposed orally to patulin for 28 days. Effects were not observed on final body weight or body weight gain. Relative weight of the liver, spleen, thymus, kidneys with adrenals, and lungs was not affected. Peripheral blood leucocyte and lymphocyte counts were decreased by approximately 30% in the two highest dose groups. The leucocyte differential was not altered. Total spleen cell, total T-cell (CD3+), helper T-cell (CD4+CD8-), B-cell (surface immunoglobulin+) and monocyte (MAC-3+) counts were not changed. Cytotoxic T-cell (CD8+CD4-) counts were increased 50% only by the highest dose. Natural killer cell (NK1.1+CD3-) and monocyte (MAC-1+) counts were increased 30% and 24%, respectively, only in the 0.08 mg/kg group. Humoral immune function as assessed by antibody-forming cell response and serum IgM titre to sheep erythrocytes, and cell-mediated immune function evaluated utilizing natural killer cell activity and the mixed lymphocyte reaction were not altered. Oral exposure to patulin for 28 days did not alter the ability of female B6C3F1 mice to mount either a cell-mediated or humoral immune response.

Immunotoxicity of mycotoxins

The immune system is primarily responsible for defense against invading organisms. The effects of several mycotoxins on the immune responses have been investigated; however, most data concern laboratory animals. In some instances, farm animals and cells derived from livestock species have been employed to evaluate the immunotoxicity of mycotoxins. Immune responses are highly variable, and cost considerations usually preclude the use of dairy cattle as experimental models. Immunosuppression caused by aflatoxin B1 has been demonstrated in various livestock species (e.g., turkeys, chickens, and pigs) and also in laboratory animals (mice, guinea pigs, and rabbits). The response of bovine lymphocytes to aflatoxin in vitro is similar to that of other laboratory animals. Trichothecenes are potent immunosuppressive agents that directly affect immune cells and also modify immune responses as a consequence of tissue damage elsewhere. Sheep and calves treated with fusarium T-2 toxin develop leukopenia and decreased functioning of peripheral lymphocytes. Immunosuppressive effects of ochratoxin A, rubratoxin B, and patulin have been reported. Citrinin produced lymphopenia but stimulated responses against antigens. Antibodies against mycotoxins conjugated to proteins have been produced and are useful for analytical purposes.

Perinatal thymocyte antigen expression and postnatal immune development altered by gestational exposure to tetrachlorodibenzo-p-dioxin (TCDD)

In utero exposure to the environmental contaminant 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) was found to alter expression of murine thymocyte fetal cell-surface markers. Pregnant mice were treated (via gavage) with 0, 1.5, or 3.0 micrograms TCDD/kg/day in corn oil on gestational days (gd) 6-14. Offspring were examined on gd 18 and postnatally on d6, d14, and d21, and at 7, 8, and 10 weeks of age. Severe thymic atrophy and cellular depletion were found both pre- and postnatally in TCDD-exposed mice. Immunocytochemical localization of the Thy 1.2 antigen on gd 18 thymocytes revealed no TCDD-related changes in cellular distribution. Flow cytometric analysis, however, indicated that the TCDD treatment resulted in a significant decrease in the percentage of CD4+8+ fetal thymocytes, as well as significantly increased CD4-8- and CD4-8+ thymocytes. The increased CD4-8+ population after TCDD was not from induction of Ts cells. At 7-8 weeks postnatally, no differences existed between control and treatment groups in mitogen responses and antibody plaque response. However, altered thymocyte antigen expression was found to correlate with altered postnatal immune function, as evidenced by decreased cytotoxic T lymphocyte response at 8 weeks of age. Taken together, these results indicate that immunosuppression following prenatal exposure to TCDD can be readily detected by qualitative and quantitative changes in the cell surface phenotype of fetal thymocytes. Furthermore, the observed altered distribution suggests that TCDD inhibits normal thymocyte maturational processes.

Effect of patulin on microbicidal activity of mouse peritoneal macrophages

Patulin, a fungal metabolite shown previously to exert immunosuppressive effects on the cellular and humoral immune systems, was examined for its in vitro effects on some functions of murine peritoneal macrophages. The cells were pre-incubated for 2 hr with mycotoxin concentrations of 0.01-2 micrograms/ml. Phagocytosis and phagosome-lysosome fusion were diminished above 0.1 microgram patulin/ml and lysosomal enzymes and microbicidal activity above 0.5 microgram/ml, whereas O2- production was inhibited only above 2 micrograms/ml. This indicated that the killing mechanism did not depend on products of the oxidative burst. The concentrations used did not decrease the cell viability. Under natural circumstances, patulin may constitute a health risk for animals.