Serum levels of ochratoxin A in dogs with chronic kidney disease (CKD): a retrospective study

Individual and combined occurrences of the prevalent mycotoxins in commercial feline and canine food

Mycotoxins, such as aflatoxin B1 (AFB1), deoxynivalenol (DON), fumonisins (FBs), ochratoxin A (OTA), T-2 toxin (T-2), and zearalenone (ZEN), can contaminate animal feeds and pose risks to animal health and production performance. These mycotoxins are commonly found in cereals and grains, with the increased use of cereals in pet food, there is a rising concern about mycotoxin contamination among pet owners. To address this, we analyzed imported brands of feline and canine food from the Chinese market produced in 2021-2022. Ninety-three samples were analyzed, comprising 45 feline food and 48 canine food samples. Among them, 14 were canned food and 79 were dry food. The results indicate that AFB1, DON, FBs, OTA, T-2, and ZEN occurred in 32.26%, 98.92%, 22.58%, 73.12%, 55.91%, and 7.53% of the samples, respectively. The most prevalent mycotoxin was DON, followed by OTA, T-2, AFB1, and FBs, whereas ZEN was less frequently detected. The mean concentrations of the six mycotoxins in pet feed samples were 3.17 μg/kg for AFB1, 0.65 mg/kg for DON, 2.15 mg/kg for FBs, 6.27 μg/kg for OTA, 20.00 μg/kg for T-2, and 30.00 μg/kg for ZEN. The levels of mycotoxins were generally below the limits of the Pet Feed Hygiene Regulations of China and the EU. Notably, a substantial majority of the pet food samples (88 out of 93) were contaminated by two or more mycotoxins. AFB1, FBs, OTA, and ZEN occurred slightly more often in feline food than in canine food. Except for OTA, the contamination rates for the other five mycotoxins in canned food were lower than those in dry food. Moreover, except for AFB1, the levels of the other five mycotoxins in canned foods were lower than those in dry foods. This study highlights the widespread contamination of pet foods with mycotoxins, which poses a significant risk to pets from continuous exposure to multiple mycotoxins.

Ameliorative impacts of astaxanthin against atrazine-induced renal toxicity through the modulation of ionic homeostasis and Nrf2 signaling pathways in mice

Astaxanthin (ASX), a red pigment belonging to carotenoids, has antioxidant activity and anti-oxidative stress effect. Atrazine (ATZ), a frequently used herbicide, whose degradation products are the cause for nephrosis and other oxidative stress associated diseases. This study was aimed to reveal the potential protective mechanism of astaxanthin against atrazine-induced nephrosis. Atrazine was orally given (250 mg/kg bw) to the mice along with astaxanthin (100 mg/kg bw) for 28 days. Serum biochemical indicators, oxidative stress biomarkers, ATPase activities, ion concentration, histomorphology, and various renal genes expression linked with apoptosis, Nrf2 signaling pathway, and aquaporins (AQPs) were assessed. It was found that serum creatinine (SCr), blood urea nitrogen (BUN), and MDA levels were significantly increased after the treatment of atrazine, whereas serum renal oxidative stress indicators like CAT, GSH, T-AOC, SOD decreased. Renal histopathology showed that atrazine significantly damaged renal tissues. The activities of Ca 2+-Mg 2+-ATPase were increased whereas Na +-K +-ATPase decreased significantly (P < 0.05). Moreover, results confirmed that the expression of AQPs, Nrf2, and apoptosis genes were also altered after atrazine administration. Interestingly, astaxanthin supplementation significantly (P < 0.05) improved atrazine-induced nephrotoxicity via decreasing SCr, BUN, oxidative stress, ionic homeostasis and reversing the changes in AQPs, Nrf2, and apoptosis gene expression. These findings collectively suggested that astaxanthin has strong potential ameliorative impact against atrazine induced nephrotoxicity.

Natural mycotoxin contamination in dog food: A review on toxicity and detoxification methods

Nowadays, the companion animals (dogs or other pets) are considered as members of the family and have established strong emotional relationships with their owners. Dogs are long lived compared to food animals, so safety, adequacy, and efficacy of dog food is of great importance for their health. Cereals, cereal by-products as well as feedstuffs of plant origin are commonly employed food resources in dry food, yet are potential ingredients for mycotoxins contamination, so dogs are theoretically more vulnerable to exposure when consumed daily. Aflatoxins (AF), deoxynivalenol (DON), fumonisins (FUM), ochratoxin A (OTA), and zearalenone (ZEA) are the most frequent mycotoxins that might present in dog food and cause toxicity on the growth and metabolism of dogs. An understanding of toxicological effects and detoxification methods (physical, chemical, or biological approaches) of mycotoxins will help to improve commercial ped food quality, reduce harm and minimize exposure to dogs. Herein, we outline a description of mycotoxins detected in dog food, toxicity and clinical findings in dogs, as well as methods applied in mycotoxins detoxification. This review aims to provide a reference for future studies involved in the evaluation of the risk, preventative strategies, and clear criteria of mycotoxins for minimizing exposure, reducing harm, and preventing mycotoxicosis in dog.

Protective effect of selenomethionine on kidney injury induced by ochratoxin A in rabbits

The purpose of this study was to investigate the protective effect and mechanism of selenomethionine (SeMet) on ochratoxin A (OTA)-induced nephrotoxicity in rabbits. In total, sixty Ira rabbits were randomly divided into 5 groups (the control group, OTA group, 0. 2 mg/kg SeMet + OTA group, 0. 4 mg/kg SeMet + OTA group, and 0. 6 mg/kg SeMet + OTA group). The rabbits were fed diets supplemented with different doses of SeMet for 21 days and given 0. 2 mg/kg OTA starting on day 15 for a week. The results showed that the SeMet supplementation could improve the changes in blood physiological indices and renal function decline caused by OTA poisoning, and alleviate pathological kidney injury in the rabbits. SeMet also increased the activities of total antioxidant capacity, superoxide dismutase, and glutathione peroxidase, and decreased the contents of malondialdehyde and reactive oxygen species and the expression of interleukin-1β, interleukin-6, and tumor necrosis factor-α in the damaged kidneys of the rabbits. In addition, the expression of nuclear factor erythroid 2-related factor 2 (Nrf2) and its downstream gene heme oxygenase 1 (HO-1) was also inhibited after OTA poisoning, while SeMet activated the Nrf2 signaling pathway and enhanced the expression of Nrf2 and the downstream gene HO-1. In conclusion, SeMet protected against kidney injury caused by OTA in rabbits, and the mechanism may be the activation of the Nrf2 signaling pathway.

Effects of dietary Glycyrrhiza polysaccharide on growth performance, blood parameters and immunity in weaned piglets

The purpose of this study was to evaluate the effects of dietary Glycyrrhiza polysaccharide (GCP) on growth performance, blood parameters and immunity in weaned piglets. A total of 240 (10.33 ± 0.62 kg body weight) 35-day-old (Duroc × Landrace × White) weaned piglets were randomly assigned to four dietary treatments, with six replicate pens per treatment and 10 piglets per pen (five males and five females). The dietary treatments continued for 21 days and comprised a basal diet supplemented with 0 (control group), 500, 1000 and 2000 mg/kg GCP. The results showed that the inclusion of 1000 and 2000 mg/kg GCP increased the average daily gain and decreased the feed conversion rate compared with the control group (p < 0.05). The piglets treated with 500 and 1000 mg/kg GCP had a lower diarrhoeal incidence than the control group (p < 0.05). Moreover, supplementation with 1000 mg/kg GCP increased the counts of white blood cells, neutrophils, red blood cells, and platelets, and elevated alkaline phosphatase, total protein, globulin, glucose, triglyceride, immunoglobulin A, immunoglobulin G, and total antioxidant capacity levels (p < 0.05), and decreased malondialdehyde content compare with the control group (p < 0.05). In addition, relative to the control group, piglets fed 500 and 1000 mg/kg GCP had significantly lower expression of interleukin-6 mRNA in spleen (p < 0.05). Our results indicate that dietary supplementation with GCP can improve growth performance, blood parameters and immunity in weaned piglets. Our study suggests that adding 1000 mg/kg GCP to the diet had the most beneficial effect.

Nontoxic Concentration of Ochratoxin A Aggravates Renal Fibrosis Induced by Adriamycin/Cyclosporine A Nephropathy via TGF-β1/SMAD2/3

Ochratoxin A (OTA) is the most common contaminant in food and feed, which causes nephrotoxicity. Studies revealed that a low level of OTA contamination could also cause physiological dysfunction. Chronic kidney disease (CKD) has become an important public health problem with increasing morbidity. However, the potential effect of nontoxic OTA on CKD remains uncertain. In this study, adriamycin (ADR) and cyclosporine A (CSA) were used to stimulate glomerular nephropathy and tubular nephropathy, respectively. Renal injury was aggravated due to OTA (0.25 mg/kg) exposure in the mouse nephropathy models, assessing by renal histomorphology and the detection of blood urea nitrogen (BUN) and serum creatine (SCr) levels. We noticed that nontoxic dosage of OTA increased the expression of fibrotic factors, α-smooth muscle actin (α-SMA), and Vimentin in a nephropathic mouse, which indicated the exacerbation of ADR/CSA-induced renal fibrosis. We conducted in vitro experiments in glomerular mesangial cells and renal tubular epithelial cells. Nontoxic concentration of OTA was found to exacerbate the cytotoxicity of ADR/CSA and intensify renal fibrosis by activating TGF-β1/SMAD2/3. Thus, this study may provide convincing evidence for the prevention of CKD aggravation and the renewal of food hygiene standards in mycotoxin contamination.

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

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

Ochratoxin A levels in serum of Polish dialysis patients with chronic renal failure

Ochratoxin A (OTA) is a mycotoxin produced by the fungi Aspergillus and Penicillium. It occurs naturally in many products of plant origin and in animals because of the carry-over from feed to meat or milk. Ochratoxin A has nephrotoxic, carcinogenic, hepatotoxic, neurotoxic, and genotoxic properties. Data on ochratoxin concentrations in blood or serum from patients with different kidney disorders are available for several European countries, as well as for Africa and Asia. In this study, we determined OTA concentrations in serum samples from chronic renal failure patients receiving dialysis and from healthy controls, collected in central Poland. Ochratoxin A was analyzed after extraction and purification using immunoaffinity columns by liquid chromatography with fluorescence detection (limit of quantification: 0.1 ng/mL) in 88 patients and 16 healthy volunteers. The dialysis group consisted of 40 women and 48 men aged between 23 and 85 years. The mean OTA concentrations were 0.75 ng/mL (maximum 2.78 ng/mL) in dialysis patients and 0.70 ng/mL (maximum 1.44 ng/mL) in healthy controls. The mean concentrations in patients treated by dialysis were 0.76 and 0.74 ng/ml for women and men, respectively (maximum 2.53 ng/ml for women and 2.78 ng/ml for men). Statistical analysis using Student's t-test showed no statistically significant differences between the control group (non-dialysis patients) and all dialysis patients.

Effects of Dietary Supplementation of gEGF on the Growth Performance and Immunity of Broilers

EGF has been shown to stimulate the growth of animals. In this study, the content of EGF in chicken embryos (gallus EGF, gEGF) aged from 1 to 20 days of incubation were determined by ELISA kit, and the 5-day-old chicken embryos with the highest content of 5593 pg/g were selected to make gEGF crude extracts. A total of 1500 1-day-old Xianju chickens were randomly divided into five groups with six replicates of 50 chickens each. The control group was fed a basal diet, and other treatment diets were supplemented with 4, 8, 16 and 32 ng/kg gEGF crude extract, respectively. The experiment lasted for 30 days. Chicks were harvested at the end of the experiment, and liver, spleen, thymus, bursa and serum samples were collected. Results showed that average daily gain (ADG) and average daily feed intake (ADFI) of 16 ng/kg group were higher than those in the control group (p < 0.05). The serum uric acid (UA) of the 16 ng/kg group was reduced (p < 0.01), and the serum alkaline phosphatase (AKP) of the 16 ng/kg group increased (p < 0.01). The gEGF extract also increased chick's antioxidant capacity, decreased malondialdehyde (MDA) and increased catalase (CAT) in the liver and serum of 16 ng/kg groups in compared to the control group (p < 0.01). Furthermore, immunity was improved by the addition of gEGF to broiler diets. The serum immunoglobin A (IgA) content of 8 and 16 ng/kg groups and the serum immunoglobin M (IgM) content of 4 and 8 ng/kg groups were increased (p < 0.05) compared to the control group. The bursa index of each experimental group was higher than the control group (p < 0.01). These findings demonstrate that the crude extract of gEGF prepared in this experiment could improve the growth performance, antioxidant capacity and immunity of broilers.

Ochratoxin A induces nephrotoxicity in vitro and in vivo via pyroptosis

Ochratoxin A (OTA), a prevalent nephrotoxic mycotoxin contaminant in food and feedstuff, has been reported to induce renal injury. To disclose the nephrotoxicity of continuous administration of OTA and to investigate potential mechanisms related to pyroptosis, male C57BL/6 mice were intraperitoneally injected with 1.0 and 2.0 mg/kg B.W. OTA every other day for 14 days. At 2.0 mg/kg B.W. OTA administration significantly increased histological injury and renal fibrosis molecules (α-SMA, Vimentin, TGF-β) and activated the NOD-like receptor protein 3 (NLRP3) inflammasome and induced pyroptosis compared with control. In the in vitro tests, Madin-Darby canine kidney (MDCK) epithelial cells were exposed to 0-4.0 μg/ml OTA for 24 h in serum-free medium. Data showed that OTA dose-dependently affected cell viability and significantly up-regulated renal fibrosis genes (α-SMA, Vimentin, TGF-β). 2.0 μg/ml OTA significantly induced NLRP3 inflammasome activation and caspase-1-dependent pyroptosis, increasing the expression and secretion of pro-inflammatory cytokines (IL-6, TNF-α) and pyroptosis-related genes (GSDMD, IL-1β, IL-18) in MDCK cells. These outcomes were significantly abrogated after inhibiting NLRP3 activation with inhibitor MCC950 and silencing NLRP3 with small interfering RNA (siRNA). Furthermore, knockdown of caspase-1 also ameliorated OTA-induced renal fibrosis via the inhibition of pyroptosis. Collectively, the chosen doses of OTA-triggered nephrotoxicity through NLRP3 inflammasome activation and caspase-1-dependent pyroptosis both in vitro and in vivo.

A rapid HPLC-FLD method for Ochratoxin A detection in pig muscle, kidney, liver by using enzymatic digestion with MISPE extraction

Ochratoxin A (OTA) is a mycotoxin produced as a secondary metabolite by various Aspergillus and Penicillium species with nephrotoxic, carcinogenic, immunotoxic and teratogenic effects. OTA has been found in several food commodities, including cereals, beer, wine and spices. OTA can also be present in animal products (especially in pig derived products) as a result of carryover from contaminated feed. Permitted level of 1 µg/kg OTA in pig meat or pig-derived products was set in Italy, as in other countries. Key parameters which affected MISPE, should be described such as extraction efficiency and were optimized, analyzed by an isocratic HPLC-FLD method. Under the optimized conditions, for all analyzed matrices mean recovery was > 89%. Method can be applied as alternative routine procedure to detect OTA presence in pig products. Points:  *Aim of the study was to develop and validate a quantitative HPLC-FLD method based on MISPE with complex solid matrices (edible tissues) followed by chromatographic analysis.  *The new method was developed and validated in pig complex matrix and is very sensitive LOD and LOQ respectively 0.001 and 0.003 µg/kg.  *This method is relatively simple to use and with good performances. Was possible to reuse MISPE column with a "regeneration" solution, until to 7 times.

Protective Effect of Astaxanthin on Ochratoxin A-Induced Kidney Injury to Mice by Regulating Oxidative Stress-Related NRF2/KEAP1 Pathway

The present study aimed to investigate the effects of astaxanthin (ASX) on ochratoxin A (OTA)-induced renal oxidative stress and its mechanism of action. Serum kidney markers, histomorphology, ultrastructural observation, and oxidative stress indicators were assessed. Meanwhile, quantitative real-time reverse transcription PCR and western blotting detection of NRF2 (encoding nuclear factor, erythroid 2 like) and members of the NRF2/KEAP1 signaling pathway (KEAP1 (encoding Kelch-like ECH-associated protein), NQO1 (encoding NAD(P)H quinone dehydrogenase), HO-1 (encoding heme oxygenase 1), γ-GCS (gamma-glutamylcysteine synthetase), and GSH-Px (glutathione peroxidase 1)) were performed. Compared with the control group, the OTA-treated group showed significantly increased levels of serum UA (uric acid) and BUN (blood urea nitrogen), tubular epithelial cells were swollen and degenerated, and the levels of antioxidant enzymes decreased significantly, and the expression of NRF2 (cytoplasm), NQO1, HO-1, γ-GCS, and GSH-Px decreased significantly. More importantly, after ASX pretreatment, compared with the OTA group, serum markers were decreased, epithelial cells appeared normal; the expression of antioxidant enzymes increased significantly, NQO1, HO-1, γ-GCS and GSH-Px levels increased significantly, and ASX promoted the transfer of NRF2 from the cytoplasm to the nucleus. These results highlight the protective ability of ASX in renal injury caused by OTA exposure, and provide theoretical support for ASX’s role in other mycotoxin-induced damage.

Risk assessment of the exposure to mycotoxins in dogs and cats through the consumption of commercial dry food

Dry feed for dogs and cats sold in Europe are mostly formulated with cereals and cereal by-products, so the contamination of this food with mycotoxins represents a potential risk for these pets. We analyzed a representation of the best-selling feed brands in Spain. The presence of Aflatoxins (B₁, B₂, G₁, and G₂), Ochratoxin A, T-2 and HT-2 toxins, Deoxynivalenol, Zearalenone, and Fumonisins (B₁ and B₂) was quantified, using immunoaffinity columns and LC-MS/MS. In general, mycotoxins were frequently and simultaneously (6-11) detected, with AFB₁, FB₁, FB₂, Deoxynivalenol, and HT-2 detected in 100% of the samples. However, the concentrations of most of them are among the lowest reported so far. Fumonisins were the exception since we report the highest concentrations to date, particularly in cat feed. We practically found no significant differences in the level of mycotoxin contamination in relation to the presumed quality of the feed. We also calculated the daily exposure, and evaluated the acute and chronic health risk posed by these feeds. None of the brands analyzed presented acute risk for any of the mycotoxins. However, the high levels of fumonisins found in some samples could become problematic, if there are hidden forms of them. This is also evident in relation to long-term risk, since in the case of fumonisins the level of exposure exceeds the tolerable daily intake level in 3.5 and 12 times, for dogs and cats respectively. The exposure levels to zearalenone and deoxynivalenol could also be of long-term concern, especially considering the possibility that the continuous exposure to several mycotoxins simultaneously might produce potentiated toxic effects as a result of their synergistic action. Further research on the potential adverse health effects deriving from chronic exposure to low doses of multi-mycotoxin mixtures in pets is needed.

Occurrence of Mycotoxins in Extruded Commercial Cat Food

The occurrence of the most important mycotoxins (deoxynivalenol, fumonisin B1 and B2, aflatoxins B1, B2, G1, and G2, ochratoxin A, zearalenone, T-2, and HT-2 toxins) was determined in 64 extruded cat foods purchased in Italy through ultra-performance liquid chromatography coupled with tandem mass spectrometry. Deoxynivalenol and fumonisins were the most common contaminants (quantified in 80 and 95% of the samples, respectively). Conversely, aflatoxins B2, G1, and G2 were not identified in any sample. Some cat foods exceeded the regulatory limit for aflatoxin B1 (n = 3) or the guidance values for zearalenone (n = 3), fumonisins (n = 2), ochratoxin A (n = 1), and T-2 (n = 1) recently established for pets in the European Union. A widespread co-occurrence of mycotoxins was observed (28, 42, and 8% of the samples contained quantifiable amounts of two, three, and four mycotoxins, respectively). This study describes criticisms regarding the mycotoxin issue in pet food and suggests an improvement of the monitoring of the pet food chain.

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

AIMS

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

MAIN METHODS

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

KEY FINDINGS

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

SIGNIFICANCE

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