Schaaf G J, Nijmeijer S M, Maas R F M, Roestenberg P, de Groene E M, Fink-Gremmels J
Department of Veterinary Pharmacology, Pharmacy and Toxicology (VFFT) Faculty of Veterinary Medicine, Utrecht University, P.O. Box 80152, NL 3508 TD Utrecht, The Netherlands.
Biochim Biophys Acta. 2002 Nov 20;1588(2):149-58. doi: 10.1016/s0925-4439(02)00159-x.
Balkan endemic nephropathy (BEN), a disease characterized by progressive renal fibrosis in human patients, has been associated with exposure to ochratoxin A (OTA). This mycotoxin is a frequent contaminant of human and animal food products, and is toxic to all animal species tested. OTA predominantly affects the kidney and is known to accumulate in the proximal tubule (PT). The induction of oxidative stress is implicated in the toxicity of this mycotoxin. In the present study, primary rat PT cells and LLC-PK(1) cells, which express characteristics of the PT, were used to investigate the OTA-mediated oxidative stress response. OTA exposure of these cells resulted in a concentration-dependent elevation of reactive oxygen species (ROS) levels, depletion of cellular glutathione (GSH) levels and an increase in the formation of 8-oxoguanine. The OTA-induced ROS response was significantly reduced following treatment with alpha-tocopherol (TOCO). However, this chain-braking anti-oxidant did not reduce the cytotoxicity of OTA and was unable to prevent the depletion of total GSH levels in OTA-exposed cells. In contrast, pre-incubation of the cell with N-acetyl-L-cysteine (NAC) completely prevented the OTA-induced increase in ROS levels as well as the formation of 8-oxoguanine and completely protected against the cytotoxicity of OTA. In addition, NAC treatment also limited the GSH depletion in OTA-exposed PT- and LLC-PK(1) cells. From these data, we conclude that oxidative stress contributes to the tubular toxicity of OTA. Subsequently, cellular GSH levels play a pivotal role in limiting the short-term toxicity of this mycotoxin in renal tubular cells.
巴尔干地方性肾病（BEN）是一种人类患者以进行性肾纤维化为特征的疾病，与接触赭曲霉毒素A（OTA）有关。这种霉菌毒素是人类和动物食品中常见的污染物，对所有受试动物物种都有毒性。OTA主要影响肾脏，已知会在近端小管（PT）中蓄积。氧化应激的诱导与这种霉菌毒素的毒性有关。在本研究中，使用表达PT特征的原代大鼠PT细胞和LLC-PK(1)细胞来研究OTA介导的氧化应激反应。这些细胞暴露于OTA后，活性氧（ROS）水平呈浓度依赖性升高，细胞内谷胱甘肽（GSH）水平降低，8-氧代鸟嘌呤的形成增加。用α-生育酚（TOCO）处理后，OTA诱导的ROS反应显著降低。然而，这种链断裂抗氧化剂并没有降低OTA的细胞毒性，也无法阻止OTA暴露细胞中总GSH水平的消耗。相比之下，用N-乙酰-L-半胱氨酸（NAC）预孵育细胞可完全阻止OTA诱导的ROS水平升高以及8-氧代鸟嘌呤的形成，并完全保护细胞免受OTA的细胞毒性。此外，NAC处理还限制了OTA暴露的PT和LLC-PK(1)细胞中的GSH消耗。从这些数据中，我们得出结论，氧化应激导致了OTA的肾小管毒性。随后，细胞内GSH水平在限制这种霉菌毒素对肾小管细胞的短期毒性方面起着关键作用。
