Nox2 contributes to hyperinsulinemia-induced redox imbalance and impaired vascular function.
Nox2 contributes to hyperinsulinemia-induced redox imbalance and impaired vascular function.
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DOI：
10.1016/j.redox.2017.06.001
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发表时间：
2017-10
期刊：
影响因子：
11.4
通讯作者：
Phillips SA
中科院分区：
文献类型：
--
作者：
Mahmoud AM;Ali MM;Miranda ER;Mey JT;Blackburn BK;Haus JM;Phillips SA
胰岛素抵抗会促进血管内皮功能障碍以及心血管疾病的后续发展。之前我们发现，健康成年人在进行高胰岛素钳夹后，骨骼肌小动脉血流诱导的扩张（FID）会减少。因此，我们假设高胰岛素血症（胰岛素抵抗的标志）通过诱导 NADPH 氧化酶（Nox）系统介导的氧化应激而导致微血管内皮细胞功能障碍。我们检查了胰岛素的影响，其水平与人类高胰岛素血症相当，对 1) 在存在和不存在 Nox 抑制剂的情况下，来自人类骨骼肌组织的分离小动脉的 FID 和 2) 人类脂肪微血管内皮细胞 (HAMEC) 一氧化氮 (NO)、内皮 NO 合酶 (eNOS) 的表达和 Nox 介导的氧化应激。在六名瘦健康参与者（平均年龄 25.5±1.6 岁，BMI 21.8±0.9）中，经过 60 分钟的离体胰岛素孵育后，活性氧 (ROS) 增加，而 NO 和小动脉 FID 减少。与 Nox 同工型 2 (Nox2) 抑制剂 VAS2870 共孵育后，这些变化被逆转。在 HAMEC 中，胰岛素诱导的 Nox2 表达和 P47phox 磷酸化的时间依赖性增加与超氧化物产生的增加相呼应。相反，eNOS 的磷酸化和超氧化物歧化酶（SOD2 和 SOD3）亚型的表达显示出双相反应，在早期时间点表达增加，随后急剧减少。胰岛素诱导 eNOS 解偶联，与 NO 下降和 ROS 产生激增同步。这些效应可被 Tempol（SOD 模拟物）、四氢生物蝶呤（BH4；eNOS 辅因子）和 VAS2870 逆转。最后，胰岛素诱导硝基酪氨酸的形成，通过抑制一氧化氮或超氧化物的生成来逆转硝基酪氨酸的形成。总之，高胰岛素血症可能通过诱导微血管内皮细胞中 Nox2 介导的超氧化物产生来减少 FID，从而减少 NO 的可用性并增强过氧亚硝酸盐的形成。因此，Nox2通路应被视为预防高胰岛素血症期间氧化应激相关内皮功能障碍的靶点。高胰岛素血症会损害 FID 并诱导人体肌肉小动脉中 ROS 的产生。内皮细胞中胰岛素诱导的 ROS 产生由 NADPH 氧化酶介导。长时间暴露于高胰岛素水平会降低 eNOS 磷酸化和 NO 产生。
Insulin resistance promotes vascular endothelial dysfunction and subsequent development of cardiovascular disease. Previously we found that skeletal muscle arteriolar flow-induced dilation (FID) was reduced following a hyperinsulinemic clamp in healthy adults. Therefore, we hypothesized that hyperinsulinemia, a hallmark of insulin resistance, contributes to microvascular endothelial cell dysfunction via inducing oxidative stress that is mediated by NADPH oxidase (Nox) system. We examined the effect of insulin, at levels that are comparable with human hyperinsulinemia on 1) FID of isolated arterioles from human skeletal muscle tissue in the presence and absence of Nox inhibitors and 2) human adipose microvascular endothelial cell (HAMECs) expression of nitric oxide (NO), endothelial NO synthase (eNOS), and Nox-mediated oxidative stress. In six lean healthy participants (mean age 25.5±1.6 y, BMI 21.8±0.9), reactive oxygen species (ROS) were increased while NO and arteriolar FID were reduced following 60 min of ex vivo insulin incubation. These changes were reversed after co-incubation with the Nox isoform 2 (Nox2) inhibitor, VAS2870. In HAMECs, insulin-induced time-dependent increases in Nox2 expression and P47phox phosphorylation were echoed by elevations of superoxide production. In contrast, phosphorylation of eNOS and expression of superoxide dismutase (SOD2 and SOD3) isoforms showed a biphasic response with an increased expression at earlier time points followed by a steep reduction phase. Insulin induced eNOS uncoupling that was synchronized with a drop of NO and a surge of ROS production. These effects were reversed by Tempol (SOD mimetic), Tetrahydrobiopterin (BH4; eNOS cofactor), and VAS2870. Finally, insulin induced nitrotyrosine formation which was reversed by inhibiting NO or superoxide generation. In conclusions, hyperinsulinemia may reduce FID via inducing Nox2-mediated superoxide production in microvascular endothelial cells which reduce the availability of NO and enhances peroxynitrite formation. Therefore, the Nox2 pathway should be considered as a target for the prevention of oxidative stress-associated endothelial dysfunction during hyperinsulinemia. Hyperinsulinemia impairs FID and induces ROS production in human muscle arterioles. Insulin-induced ROS production in endotelial cells is mediated by NADPH oxidase. Long exposure to high insulin levels reduces eNOS phosphorylation and NO production.