Katika Madhumohan R, Hendriksen Peter J M, van Loveren Henk, A C M Peijnenburg Ad
RIKILT-Institute of Food Safety, Wageningen University and Research Centre , Wageningen , the Netherlands .
J Immunotoxicol. 2015 Jul-Sep;12(3):206-16. doi: 10.3109/1547691X.2014.925995. Epub 2014 Jul 2.
Deoxynivalenol (DON) is one of the most abundant mycotoxins worldwide and mostly detected in cereals and grains. As such, DON poses a risk for many adverse health effects to human and animals. In particular, immune cells are very sensitive to DON, with the initiating step leading to toxicity being a binding to the eukaryotic 60S ribosomal subunit and induction of ribotoxic stress. The present study aimed to: (1) extend insight into the mechanism of action (MOA) of DON in immune cells; and (2) understand why immune cells are more sensitive to DON than most other cell types. Previously published microarray studies have described the effects of DON on immune cells. To build upon these findings, here, immunocytological and biochemical studies were performed using human T-lymphocyte Jurkat cells that were exposed for 3 h to 0.5 µM DON. Induction of ER stress by DON was confirmed by immunocytology demonstrating increased protein expression of two major ER stress markers ATF3 and DDIT3. T-cell activation was confirmed by induction of phosphorylation of protein kinases JNK and AKT, activation of NF-κB (p65), and increased expression of NFAT target gene NUR77; each of these are known inducers of the T-cell activation response. Induction of an oxidative stress response was also confirmed by monitoring the nuclear translocation of major oxidative stress markers NRF2 and KEAP1, as well as by changes (i.e. decreases) in cell levels of reduced glutathione. Lastly, this study showed that DON induced cleavage of caspase-3, an event known to mediate apoptosis. Taken together, these results allowed us to formulate a potential mechanism of action of DON in immune cells, i.e. binding to eukaryotic 60S ribosomal subunit → ribotoxic stress → ER stress → calcium release from the ER into cytoplasm → T-cell activation and oxidative stress → apoptosis. It is proposed that immune cells are more sensitive to DON than other cell types due to the induction of a T-cell activation response by increased intracellular calcium levels.
脱氧雪腐镰刀菌烯醇（DON）是全球范围内最常见的霉菌毒素之一，主要在谷物和粮食中被检测到。因此，DON对人类和动物的健康构成诸多不良影响的风险。特别是，免疫细胞对DON非常敏感，导致毒性的起始步骤是与真核生物60S核糖体亚基结合并诱导核糖体毒性应激。本研究旨在：（1）深入了解DON在免疫细胞中的作用机制（MOA）；（2）理解为什么免疫细胞比大多数其他细胞类型对DON更敏感。先前发表的微阵列研究已经描述了DON对免疫细胞的影响。为了基于这些发现展开研究，在此，使用人T淋巴细胞Jurkat细胞进行免疫细胞化学和生化研究，这些细胞暴露于0.5 μM DON 3小时。免疫细胞化学证实DON诱导内质网应激，表现为两种主要内质网应激标志物ATF3和DDIT3的蛋白表达增加。通过诱导蛋白激酶JNK和AKT的磷酸化、NF-κB（p65）的激活以及NFAT靶基因NUR77表达的增加来确认T细胞活化；这些都是已知的T细胞活化反应诱导剂。通过监测主要氧化应激标志物NRF2和KEAP1的核转位以及细胞内还原型谷胱甘肽水平的变化（即降低），也证实了氧化应激反应的诱导。最后，本研究表明DON诱导了半胱天冬酶-3的裂解，这是一个已知介导细胞凋亡的事件。综上所述，这些结果使我们能够阐述DON在免疫细胞中的潜在作用机制，即与真核生物60S核糖体亚基结合→核糖体毒性应激→内质网应激→内质网中的钙释放到细胞质中→T细胞活化和氧化应激→细胞凋亡。有人提出，免疫细胞比其他细胞类型对DON更敏感是由于细胞内钙水平升高诱导了T细胞活化反应。
