Edrissi Hamidreza, Schock Sarah C, Hakim Antoine M, Thompson Charlie S
University of Ottawa, Neuroscience Graduate Program, 451 Smyth Road, Ottawa, ON, Canada K1H 8M5.
Ottawa Hospital Research Institute, Neuroscience, 451 Smyth Road, Ottawa, ON, Canada K1H 8M5.
Brain Res. 2016 Mar 1;1634:83-93. doi: 10.1016/j.brainres.2015.12.032. Epub 2015 Dec 23.
Numbers of circulating microparticles (MPs) are elevated in a variety of cardiovascular disorders, and recent studies indicate that they are involved in inflammatory intercellular signaling. In the present study the signaling properties of MPs were assessed in an in vitro model of the blood brain barrier. MPs isolated from the plasma of rats exposed to chronic cerebral ischemia caused a significant reduction in the transendothelial electrical resistance (TEER) when applied to in vitro endothelial barriers, while MPs isolated from an equal volume of plasma from unoperated or sham operated rats did not. The reduction in TEER was attenuated by treating endothelial barriers prior to exposure to MPs with the caspase 3 inhibitor AC-DEVD-CHO, the TNF-α inhibitor SPD304, the tumor necrosis factor alpha-converting enzyme (TACE, ADAM 17) inhibitor TAPI-0-1 and the Rho kinase (ROCK) inhibitor Y-27632, and by treating the MPs themselves with these inhibitors prior to applying them to cultured cells. This observation indicates that MPs generated during cerebral ischemia contain pro-TNF-α, active TACE and active ROCK. ROCK and Ras homolog gene family member A (RhoA) were detected in MPs by western blot. The growth factor VEGF stimulated transcellular transport in endothelial barriers while exposure to MPs did not. We conclude that the increase in permeability of artificial barriers induced by MPs is primarily due to enhanced apoptosis induced by activation of the TNF-α pathway and activated caspase 3 and Rho kinases delivered to endothelial cells by MPs.
循环微颗粒（MPs）的数量在多种心血管疾病中都会升高，最近的研究表明它们参与炎症性细胞间信号传导。在本研究中，我们在血脑屏障的体外模型中评估了 MPs 的信号传导特性。从暴露于慢性脑缺血的大鼠血浆中分离出的 MPs，当应用于体外内皮屏障时，会导致跨内皮电阻（TEER）显著降低，而从未手术或假手术大鼠等量血浆中分离出的 MPs 则不会。在用 caspase 3 抑制剂 AC-DEVD-CHO、TNF-α 抑制剂 SPD304、肿瘤坏死因子α转换酶（TACE，ADAM 17）抑制剂 TAPI-0-1 和 Rho 激酶（ROCK）抑制剂 Y-27632 预处理内皮屏障后再暴露于 MPs，以及在将 MPs 应用于培养细胞之前先用这些抑制剂处理 MPs 本身，均可减弱 TEER 的降低。这一观察结果表明，脑缺血期间产生的 MPs 含有前体 TNF-α、活性 TACE 和活性 ROCK。通过蛋白质印迹法在 MPs 中检测到了 ROCK 和 Ras 同源基因家族成员 A（RhoA）。生长因子 VEGF 刺激内皮屏障中的跨细胞转运，而暴露于 MPs 则无此作用。我们得出结论，MPs 诱导的人工屏障通透性增加主要是由于 TNF-α 途径激活诱导的细胞凋亡增强，以及 MPs 传递给内皮细胞的活化 caspase 3 和 Rho 激酶所致。
