Jiangxi Provincial Institute of Hypertension, The First Affiliated Hospital of Nanchang University, Nanchang 330006, China.
Jiangxi Provincial Key Laboratory of Basic Pharmacology, Nanchang University School of Pharmaceutical Science, Nanchang 330006, China.
Oxid Med Cell Longev. 2019 Nov 12;2019:2340392. doi: 10.1155/2019/2340392. eCollection 2019.
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 and 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 M 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.
人们已经认识到铁过载可能会损害身体健康。血管内皮细胞（VECs）是铁过载损伤的主要靶标之一，其涉及的机制被认为与活性氧（ROS）的过度产生有关。然而，铁过载损伤的 VEC 中 ROS 产生的亚细胞和时间特征、潜在的下游机制以及靶细胞器尚未得到阐述。在这项研究中，我们通过和实验阐明了上述问题。用补充铁的颗粒饮食喂养小鼠 4 个月。结果表明，胸主动脉条的内皮依赖性扩张明显受损，并伴有炎症变化，显微镜分析下可见棕色 TUNEL 阳性染色。此外，血清中不对称二甲基精氨酸（ADMA）的含量增加，而一氧化氮（NO）的水平降低。此外，主动脉组织中二甲基精氨酸二甲氨基水解酶 II（DDAHII）的表达和活性以及内皮型一氧化氮合酶（eNOS）的磷酸化受到抑制。用 50μM 铁葡聚糖处理人脐静脉内皮细胞 48 小时后，细胞活力、NO 含量、DDAHII 的表达和活性以及 eNOS 的磷酸化降低，乳酸脱氢酶和 caspase-3 活性、ADMA 含量和凋亡细胞显著增加。加入 L-精氨酸（L-Arg）或 pAD/DDAHII 后，上述变化得到逆转。通过动态检测细胞质和线粒体中 ROS 生成的变化并干扰不同的信号通路，我们首次证实，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，过多的游离铁离子在细胞质中产生过多的 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，两者结合导致 ROS 爆发，导致线粒体功能障碍和 VEC 受损。
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