Apoptosis and oxidative stress induced by ochratoxin A in rat kidney

Ochratoxin A (OTA) is a widespread mycotoxin produced by several species of fungi. OTA induces a tubular-interstitial nephropathy in humans and in animals. It has been implicated as one of the aetiological agents involved in the development of endemic nephropathy. OTA-induced oxidative stress and apoptosis may play key roles in the development of chronic tubulointerstitial nephritis connected to the long-term exposure to this food contaminant. We studied the effects of low doses of OTA on kidney cells. Wistar rats were treated with 120 g OTA/kg bodyweight daily, for 10, 30 or 60 days. Toxin concentration in kidney was proportional to the time of exposure, and amounted to 547.2, 752.5 and 930.3 ng OTA/g kidney tissue after 10, 30 and 60 days, respectively. OTA treatment caused an increased number of cells undergoing apoptosis in both proximal and distal epithelial kidney cells. The apoptotic cells were visualised using the TUNEL assay and staining with haematoxylin and eosin in situ. The number of apoptotic cells in rats treated for 10, 30 and 60 days increased by 5-, 6.4- and 12.7-fold, respectively, compared with the control cells. However, DNA electrophoresis did not show characteristic fragmentation (DNA laddering). The oxidative stress was evident via increased malondialdehyde formation. The concentration of lipid peroxides showed an increase (36%), but the activity of superoxide dismutase decreased (26%) in 60-day treated rats. In spite of the observed biochemical and morphological changes in the kidney cells, renal functional status was preserved to the end of experiment. This study demonstrates that a combination of morphologic and biochemical markers can be used to monitor early cell death in OTA-induced renal injury. We have shown that the exposure to the relatively low OTA concentrations has activated apoptotic processes and oxidative damage in kidney cells.     

Effects of ochratoxin A on ER stress,MAPK signaling pathway and autophagy of kidney and spleen in pigs

Ochratoxin A (OTA), a worldwide mycotoxin found in food and feeds, is a potent nephrotoxin and immunotoxin in animals and humans. This research was conducted to evaluate whether endoplasmic reticulum (ER) stress, MAPK signaling pathway and autophagy were induced by OTA in kidney and spleen of pigs. Twenty‐seven crossbred pigs randomly allocated to 3 groups were fed for 42 days ad libitum a basal diet without (Con group, 0.00 μg OTA/kg) and with supplementation of OTA at 400 (OTA‐L group) and 800 μg/kg (OTA‐H group). From each group, 6 pigs were randomly selected for blood collection on days 0, 21, and 42 and 3 pigs were randomly selected for tissue collection on day 42. The results showed that OTA at 400 and 800 μg/kg diets significantly increased OTA concentrations in serum and kidney and spleen induced the histopathological lesions of kidney and spleen, decreased TCR‐stimulated T lymphocyte viabilities and IL‐2 concentration, increased TNF‐α concentration, and decreased T‐AOC levels. OTA increased glucose regulated protein 78, p38, and ERK1/2 phosphorylation, and LC3 II and Atg5 protein expression in kidney and spleen of pigs. These results provide new insights into the relationship between OTA and ER stress, p38 and ERK1/2 MAPK signaling pathway and autophagy in pigs.     

Phenolic acid protects of renal damage induced by ochratoxin A in a 28-days-oral treatment in rats

The present study aimed to characterize the chlorogenic acid (ChlA) capacity to reverse the toxic effects induced by ochratoxin A (OTA) in a subacute toxicity test in rats. Male Wistar rats were fed orally by gavage for 28 days with OTA (0.4 mg/kg bw/day), ChlA (5 mg/kg bw/day) or the combination OTA (0.4 mg/kg bw/day) + ChlA (5 mg/kg bw/day). No deaths, no decrease in feed intake or body weight in any experimental group were recorded. The negative control group and the animals treated with ChlA alone showed no changes in any parameters evaluated. In OTA-treated group significant changes such as decrease in urine volume, proteinuria, occult blood, increase in serum creatinine values; decrease in absolute and relative kidney weight and characteristics histopathological lesions that indicated kidney damage were observed. However, limited effect on oxidative stress parameters were detected in kidneys of OTA-treated group. Animals treated with the combination OTA + ChlA were showed as negative control group in the evaluation of several parameters of toxicity. In conclusion, ChlA, at given concentration, improved biochemical parameters altered in urine and serum and pathological damages in kidneys induced by OTA exposure, showing a good protective activity, but not by an apparent antioxidant mechanism.     

Study of ochratoxin A (OTA)-induced oxidative stress markers in broiler chicks

The current study was designed to investigate the effects of ochratoxin A (OTA) on the oxidative stress in day-old broiler chicks. A total of 60-day-old broiler chicks were divided into four equal groups A–D. Group A was control, groups B–D were administered with different levels of OTA (1.6, 3.2 and 6.4?mg/kg of feed), respectively, for 10?days from day one of their age. Superoxide dismutase (SOD), glutathione peroxidase (GPx) and total antioxidant status of blood plasma, RBCs hemolysate and supernatant of tissue homogenates (liver, kidney and muscles) were estimated in all groups on days 11 and 31 in order to determine the oxidative stress in chicks. The results revealed a significant dose-dependent decrease in the SOD, GPx and TAS levels in all OTA-fed groups. It was found persistent even after 21?days of withdrawal of toxin-contaminated feed in all tissues except RBCs hemolysate. Present study described the OTA-induced oxidative stress as indicated by the low levels of SOD, GPx and TAS in different biological samples of broiler chicks.     

Urinary ochratoxin A and ochratoxin alpha in pregnant women

This study determined exposure of pregnant women to ochratoxin A (OTA). Forty samples of first-void urine samples from Croatian women in the third trimester of pregnancy were analyzed for OTA and its major metabolite ochratoxin alpha (OTα). The subjects filled a short food frequency questionnaire (FFQ). Analysis was performed by HPLC-FLD following liquid–liquid extraction. All samples were subjected in parallel to enzymatic treatment (β-glucuronidase/aryl sulfatase) to release OTA and OTα from the conjugates. The median urinary levels of OTA and OTα before treatment were 0.02 (range: nd–1.07) ng/mL and 0.16 (nd–1.86) ng/mL; the concentrations after enzyme hydrolysis were 0.02 (nd–1.11) ng/mL and 1.18 (0.11–7.57) ng/mL. While OTα levels increased significantly following enzymatic treatment, evidence for OTA conjugation was weak. The ratio of urinary OTα medians after and before hydrolysis was 1.5 times higher than previously reported for nonpregnant female subjects, possibly indicating upregulated metabolism and/or elimination of the mycotoxin and metabolites in pregnancy. The mean daily dietary OTA intake calculated from FFQs (1.08 ± 0.57 ng/kg body weight) was well below the provisional tolerable daily intake and the greatest contributors to intake were cereal products, fruit juices, chocolate and coffee.     

Berberine exerts nephroprotective effect against cisplatin-induced kidney damage through inhibition of oxidative/nitrosative stress,inflammation, autophagy and apoptosis

The aim of this study was to investigate the therapeutic activity of isoquinoline alkaloid berberine against cisplatin (CP)-induced nephrotoxicity in mice. Berberine was administered at daily doses of 1, 2 and 3 mg/kg by gavage for two successive days, 48 h after intraperitoneal CP injection (13 mg/kg). Mice were sacrificed 24 h after the last dose of berberine. Histopathological changes and the increase in serum creatinine and blood urea nitrogen (BUN) induced by CP were significantly ameliorated by berberine in a dose-dependent manner. Additionally, oxidative/nitrosative stress, evidenced by the increase in renal 4-hydroxynonenal (4-HNE), 3-nitrotyrosine (3-NT), cytochrome P450 E1 (CYP2E1) and heme oxygenase (HO-1) expression, was significantly reduced. The expression of nuclear factor-kappaB (NF-κB), tumor necrosis factor-α (TNF-α), cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) was markedly suppressed by berberine, indicating the inhibition of inflammatory response. Treatment of CP-intoxicated animals with berberine also significantly reduced the expression of p53, active caspase-3 as well as autophagy marker light chain 3B (LC3B) in the kidneys. The results of the current study showed the nephroprotective activity of berberine against CP-induced renal injury, which could be attributed to the inhibition of oxidative/nitrosative stress, inflammation, autophagy and apoptosis.     

The protective effects of selenium on cadmium-induced oxidative stress and apoptosis via mitochondria pathway in mice kidney

Selenium, an essential trace element, showed the significant protective effects against kidney damage induced by some heavy metals. Our previous research have found that the protection effects of selenium on ROS mediated-apoptosis by mitochondria dysfunction in cadmium (Cd)-induced LLC-PK1 cells. The present study as a continuation of our earlier one to investigate the protective effects and mechanism of selenium on Cd-induced apoptosis of kidney in vivo. Cadmium exposure increased the production of reactive oxygen species (ROS) and altered the levels of oxidative stress related biomarkers in kidney tissue. A concomitant by the loss of mitochondrial membrane potential, cytochrome c release and regulation of VDAC, Bcl-2 and Bax were observed. Apoptotic nature of cell death is confirmed by activation of caspase-3, which is also supported by histological examination. During the process, selenium played a beneficial role against Cd-induced renal damage. Pretreatment with selenium partially blocked Cd-induced ROS generation, inhibited Cd induced mitochondrial membrane potential collapse, prevented cytochrome c release, inhibited caspase activation and changed the level of VDAC, Bcl-2 and Bax. Combining all, results suggest that selenium has an ability to inhibit mitochondrial apoptotic pathway in oxidative stress mediated kidney dysfunction caused by cadmium.     

Disturbed Hsp70 and Hsp27 expression and thiol redox status in porcine kidney PK15 cells provoked by individual and combined ochratoxin A and citrinin treatments

The aim of this study was to explore the oxidative properties of ochratoxin A (OTA) and citrinin (CTN) as a possible underlying mechanism of their individual and/or combined cytotoxicity. Metabolic activity of PK15 porcine kidney cells was significantly reduced with OTA and CTN co-exposures, with synergistic cytotoxic interactions. Single CTN increased both reduced (GSH) and oxidized (GSSG) glutathione after 24 h. However, GSH was significantly lowered with all OTA and CTN combined applications in synergistic manner after 12 and 24 h. GSH/GSSG ratio was reduced in most single and dual treatments, which suggested the presence of oxidative stress. In addition, OTA and CTN exposures significantly decreased concentrations of total thiols, with mycotoxins interactions being synergistic or antagonistic. The expression levels of Hsps were differentially affected by single and dual mycotoxin(s) applications. Single OTA provoked significant down-regulation of Hsp70 and Hsp27 expressions, while CTN stimulated Hsps expressions. Hsps were also up-regulated by dual treatments, and this induction was much stronger then with single CTN. In conclusion, significant alterations in cellular redox status (glutathione, thiols) and protective mechanisms (Hsps) suggest that those disturbances might be involved in OTA and CTN individual and combined mechanisms of cytotoxicity.     

Effect of ochratoxin A on cell survival and collagen homeostasis in human mesangial cells in primary culture

Ochratoxin A (OTA) is a mycotoxin produced by several fungi growing on food source material. The main target of OTA is the kidney. So far, mainly cell lines of different origin have been used to study OTA toxicity. Yet all of them derived from tubule segments and therefore only limited information is available on glomerular effects of OTA. We exposed human mesangial cells in primary culture to OTA in nanomolar concentrations for up to 14 days. Necrotic and apoptotic cell death as well as fibrotic changes were studied. Protein content decreased only when unusual high OTA concentrations were used (1 μM). By contrast, an increase of caspase-3 activity or LDH release was observed after five days already at 10 nM OTA. A decrease of collagen I secretion was accompanied by a virtually unchanged collagen III and fibronectin secretion. Collagen IV secretion was slightly increased at low OTA concentrations (0.3–10 nM). We conclude that OTA has only a minor effect on human mesangial cells in primary culture. OTA did not influence collagen homeostasis substantially. Based on the data presented here, a risk of mesangial damage by OTA exposure is unlikely.     

A comparison between the effects of ochratoxin A and aristolochic acid on the inflammation and oxidative stress in the liver and kidney of weanling piglets

Naunyn-Schmiedeberg's Archives of Pharmacology - Ochratoxin A (OTA) and aristolochic acid (AA) are toxins that can frequently contaminate cereals and cereals-based products. The present study...     

IDH2 gene deficiency accelerates unilateral ureteral obstruction-induced kidney inflammation through oxidative stress and activation of macrophages

Mitochondrial NADP⁺-dependent isocitrate dehydrogenase 2 (IDH2) produces NADPH, which is known to inhibit mitochondrial oxidative stress. Ureteral obstruction induces kidney inflammation and fibrosis via oxidative stress. Here, we investigated the role and underlying mechanism of IDH2 in unilateral ureteral obstruction (UUO)-induced kidney inflammation using IDH2 gene deleted mice (IDH2^–/–). Eight- to 10-week-old female IDH2^–/– mice and wild type (IDH2^+/+) littermates were subjected to UUO and kidneys were harvested 5 days after UUO. IDH2 was not detected in the kidneys of IDH2^–/– mice, while UUO decreased IDH2 in IDH2^+/+ mice. UUO increased the expressions of markers of oxidative stress in both IDH2^+/+ and IDH2^–/– mice, and these changes were greater in IDH2^–/– mice compared to IDH2^+/+ mice. Bone marrow-derived macrophages of IDH2^–/– mice showed a more migrating phenotype with greater ruffle formation and Rac1 distribution than that of IDH2^+/+ mice. Correspondently, UUO-induced infiltration of monocytes/macrophages was greater in IDH2^–/– mice compared to IDH2^+/+ mice. Taken together, these data demonstrate that IDH2 plays a protective role against UUO-induced inflammation through inhibition of oxidative stress and macrophage infiltration.     

Inula crithmoides extract protects against ochratoxin A-induced oxidative stress, clastogenic and mutagenic alterations in male rats

Ochratoxin A (OTA) is a mycotoxin often found in cereals and agricultural products. There is unequivocal evidence of renal carcinogenicity of OTA in male rats, although the mechanism of action is unknown. Several reports suggest that exposure to OTA resulted in oxidative stress, genotoxicity and DNA damage. Therefore, the aim of the current study was to evaluate the protective effects of aqueous extract of Inula crithmoides growing in Egypt against OTA-induced mutagenicity and oxidative stress. Forty male Sprague-Dawley rats were divided into four groups and treated for 15 days as follows: control group and the groups treated with OTA (3mg/kg b.w), I. crithmoides extract alone (370mg/kg b.w) and OTA+I. crithmoides extract. Blood and tissue samples were collected for different biochemical analyses. Bone marrow micronucleus test and blood for random amplified polymorphism DNA-PCR (RAPD-PCR) method were performed to assess the antigenotoxic effect of the extract. The results indicated that OTA induced toxicological effects typical to those reported in the literature and increased the frequencies of MnPCEs in bone marrow. The RAPD-PCR analysis revealed the appearance of new bands in DNA resulting from genetic alteration. The extract alone was safe and succeeded in counteracting the oxidative stress and protect against the cytotoxicity resulting from OTA.     

Protective effect of Aquilegia vulgaris (L.) against lead acetate-induced oxidative stress in rats

Oxidative stress has been proposed as a possible mechanism involved in lead toxicity. The current study was carried out to evaluate the antioxidant activity of the ethanol extract of Aquilegia vulgaris (L.) against lead acetate (LA)-induced oxidative stress in male rats. Tested animals were treated orally with A. vulgaris extract (100 ppm) in combination with, before, or after LA treatment (20 ppm). The results indicated that the extract alone did not induce any significant changes in body weight gain, food intake, serum biochemical chemistry or the histological picture of the liver and kidney. However, it increased significantly the level of Glutathione (GSH). On the other hand, LA decreased food intake, body weight gain and induced oxidative stress as indicated by the significant changes in serum biochemical parameters and histological picture of liver and kidney and increased lipid peroxide and reduces GSH levels in liver tissues. The extract succeeded to improve the histological pictures of liver and kidney and the biochemical parameters towards the normal values of the control. Moreover, this improvement was pronounced in the animals treated with the extract after LA intoxication.     

Ochratoxin A in human blood and Balkan endemic nephropathy

The etiology of Balkan endemic nephropathy, a kidney disease encountered among the rural population living in regions along several big rivers on the Balkan Peninsula, remains unknown in spite of many hypotheses put forward and tested. One hypothesis involves mycotoxins as the causal agent. The mycotoxin ochratoxin A has been demonstrated to have a potent nephrotoxic effect in all mammalian species tested so far.The results of analysis of ochratoxin A in human blood samples by an analytical method based on the measurement of fluorescence spectra, before and after incubation with carboxypeptidase A, is described. For a 2-g-sample the detection limit of the method is 1–2 ng/g serum. High performance liquid chromatography used for the confirmation of ochratoxin A identity by means of several derivatives of the molecule is also described. Out of more than 600 samples collected in an endemic region in Yugoslavia about 7% were positive for ochratoxin A. The highest concentration found was 40 ng ochratoxin A/g serum.     

缬沙坦对糖尿病肾病大鼠肾脏氧化应激的影响

目的观察缬沙坦干预治疗后糖尿病大鼠肾脏氧化应激的变化,探讨缬沙坦保护肾脏的部分机制。方法以链脲佐菌素建立糖尿病大鼠模型,缬沙坦干预治疗10周,观察大鼠糖代谢、肾功能及肾皮质内丙二醛(MDA)含量、超氧化物歧化酶(SOD)活性。结果糖尿病大鼠糖化血红蛋白、血尿素氮、24h尿总蛋白、尿白蛋白定量(24h)、24h尿量、肾皮质MDA含量显著升高;肾皮质SOD活性显著降低。缬沙坦干预治疗组上述指标改善,差异有统计学意义。结论氧化应激参与了糖尿病肾病(DN)的发病过程,缬沙坦对DN的治疗作用部分是通过抗氧化实现的。     

Control of ochratoxin A production in grapes

Ochratoxin A (OTA) is a mycotoxin commonly present in cereals, grapes, coffee, spices, and cocoa. Even though the main objective of the food and feed chain processors and distributors is to avoid the extended contamination of plant-derived foods and animal feeds with mycotoxins, until now, complete OTA removal from foods and feedstuffs is not feasible. Prevention through pre-harvest management is the best method for controlling mycotoxin contamination. However, in the case that the contamination occurs after this stage, the hazards associated with OTA must be managed through post-harvest strategies. Due to the increasing number of fungal strains resistant to chemical fungicides and the impact of these pesticides on the environment and human health, maximum levels of chemical residues have been regulated in many products. Alternative methods are necessary to substitute or complement treatments with fungicides to control fungi under field or storage conditions. Yeasts are considered one of the most potent biocontrol agents due to their biology and non-toxic properties. Epiphytic yeasts are the major component of the microbial community on the surface of grape berries and they are evolutionarily adapted to this ecological niche. Nowadays, several yeast species included in different genera are considered as potential biocontrol agents to control both, growth of ochratoxigenic Aspergillus species and OTA accumulation.     

Fate of the teratogenic and carcinogenic ochratoxin A in human perfused placenta

Ochratoxin A (OTA) is one of the most frequent mycotoxins detected in human blood worldwide. Apart from its well known nephrotoxicity, OTA-induced teratogenicity and carcinogenicity proven in animals are potential effects also in humans. Pregnant women have been exposed to this food contaminant via dietary exposure in a continuous and widespread manner. Although the transplacental transfer of OTA has been demonstrated in laboratory animals and the presence of OTA in human fetal samples has been reported, little is known about the role of human placenta in OTA toxicokinetics. In this study, human perfused placenta was used to reveal the actual placental toxicokinetics of OTA using concentrations found in serum of pregnant women. Moreover, the effect of protein concentration and biological significance of placental transporters on the OTA transfer in human placenta were also determined. Our study is the first to pursue the transfer of OTA through perfused human placenta. The transfer of OTA through term human placenta was barely detectable in all perfusions. Inhibitors of neither ABCG2 nor ABCC2 increased the transport of OTA to fetal circulation in placental perfusion, and thus these transporters apparently do not have biological significance in inhibiting transplacental transfer of OTA. Human albumin has inhibited OTA transfer through a tight monolayer of BeWo b30 cells. Finding from this study clearly contradict the existing epidemiological studies reporting higher OTA levels in fetal than in maternal circulation in vivo.     

The relationship between ochratoxin A and blood pressure in adolescents

Ochratoxin A (OTA) is a chemical produced by some fungal species, and although its toxic effects have been shown in many animal studies, there are limited studies in humans. We aimed to examine the relationship between OTA and hypertension. 50 newly diagnosed hypertensive patients and 33 healthy individuals aged between 12 and 14 were included in the study. Anthropometric measurements, blood pressure measurements, complete blood count, blood biochemical parameters, urine lead level and urine OTA level were measured. OTA was detected in the urine samples of 90.9% of the control group, 100% of the hypertensive group and 85.7% of the obese+hypertensive group. Median urinary OTA was 32.9 ng/g creatinine for hypertensive group, 32.2 ng/g creatinine for hypertensive+obese group, 18.8 ng/g creatinine for the control group. Multivariate logistic regression analysis revealed a positive association between last quartile of urinary OTA level and being hypertensive [AOR:5.93 (95%CI: 1.27–27.61)] in adolescents without obesity. Hypertensive cases could be evaluated for OTA exposure in further studies.