Iron Overload Damages the Endothelial Mitochondria via the ROS/ADMA/DDAHII/eNOS/NO Pathway
Iron Overload Damages the Endothelial Mitochondria via the ROS/ADMA/DDAHII/eNOS/NO Pathway
复制标题
铁过载通过 ROS/ADMA/DDAHII/eNOS/NO 途径损伤内皮线粒体
DOI：
10.1155/2019/2340392
复制
发表时间：
2019-11-12
影响因子：
--
通讯作者：
He, Ming
中科院分区：
文献类型：
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作者：
He, Huan;Qiao, Yang;He, Ming
人们已经认识到，铁超载可能会损害身体的健康。血管内皮细胞（vascular endothelial cells，VECs）是铁超负荷损伤的主要靶细胞之一，其机制被认为与活性氧（reactive oxygen species，ROS）的过度产生有关。然而，ROS产生的亚细胞和时间特征，潜在的下游机制，以及铁超载损伤的VEC靶细胞器尚未阐明。在这项研究中，我们阐明了上述问题，通过在体内和体外实验。小鼠连续4个月喂食补充有铁的颗粒饲料。结果显示，胸主动脉条的内皮依赖性舒张功能明显受损，并伴有炎症变化，在显微镜分析中，棕色TUNEL阳性染色明显。此外，血清不对称二甲基精氨酸（ADMA）含量增加，而一氧化氮（NO）水平下降。此外，二甲基精氨酸二甲氨基水解酶II（DDAHII）的表达和活性，以及在主动脉组织中的内皮型一氧化氮合酶（eNOS）的磷酸化，被抑制。50 μM右旋糖酐铁处理人脐静脉内皮细胞48 h后，细胞活力、NO含量、DDAH Ⅱ表达和活性、eNOS磷酸化水平降低，乳酸脱氢酶、caspase-3活性、ADMA含量和凋亡细胞明显增加。加入L-精氨酸（L-Arg）或pAD/DDAH Ⅱ后，上述变化被逆转。通过动态检测细胞质和线粒体中ROS产生的变化，并对信号通路的不同方面进行干预，我们首次证实了过量的ROS来源于细胞质，并激活ROS诱导的ROS释放（RIRR）机制，导致线粒体功能障碍。总之，我们的数据表明，过量的游离铁离子在细胞质中产生过量的ROS。因此，过量的ROS通过激活ADMA/eNOS/DDAHII/NO途径产生一个恶性循环，通过激活RIRR机制产生另一个恶性循环，当两者结合时，诱导ROS爆发，导致线粒体功能障碍和受损的VEC。
It has been recognized that iron overload may harm the body's health. Vascular endothelial cells (VECs) are one of the main targets of iron overload injury, and the mechanism involved was thought to be related to the excessive generation of reactive oxygen species (ROS). However, the subcellular and temporal characteristics of ROS generation, potential downstream mechanisms, and target organelles in VECs injured by iron overload have not been expounded yet. In this study, we elucidated the abovementioned issues through both in vivo and in vitro experiments. Mice were fed pellet diets that were supplemented with iron for 4 consecutive months. Results showed that the thoracic aortic strips' endothelium-dependent dilation was significantly impaired and associated with inflammatory changes, noticeable under brown TUNEL-positive staining in microscopy analysis. In addition, the serum content of asymmetric dimethylarginine (ADMA) increased, whereas nitric oxide (NO) levels decreased. Furthermore, the dimethylarginine dimethylaminohydrolase II (DDAHII) expression and activity, as well as the phosphorylation of endothelial nitric oxide synthase (eNOS) in aortic tissue, were inhibited. Human umbilical vein endothelial cells were treated with 50 μM iron dextran for 48 hours, after which the cell viability, NO content, DDAHII expression and activity, and phosphorylation of eNOS decreased and lactate dehydrogenase and caspase-3 activity, ADMA content, and apoptotic cells significantly increased. After the addition of L-arginine (L-Arg) or pAD/DDAHII, the abovementioned changes were reversed. By dynamically detecting the changes of ROS generation in the cytoplasm and mitochondria and interfering with different aspects of signaling pathways, we have confirmed for the first time that excessive ROS originates from the cytoplasm and activates the ROS-induced ROS release (RIRR) mechanism, leading to mitochondrial dysfunction. Together, our data suggested that excessive free iron ions produced excess ROS in the cytoplasm. Thus, excess ROS create one vicious circle by activating the ADMA/eNOS/DDAHII/NO pathway and another vicious circle by activation of the RIRR mechanism, which, when combined, induce a ROS burst, resulting in mitochondrial dysfunction and damaged VECs.