机械损伤诱导脑内皮源性微泡释放:对创伤性脑损伤期间脑血管损伤的影响。
Mechanical Injury Induces Brain Endothelial-Derived Microvesicle Release: Implications for Cerebral Vascular Injury during Traumatic Brain Injury.
作者信息
Andrews Allison M, Lutton Evan M, Merkel Steven F, Razmpour Roshanak, Ramirez Servio H
机构信息
Department of Pathology and Laboratory Medicine, Lewis Katz School of Medicine at Temple UniversityPhiladelphia, PA, USA; The Shriners Hospitals Pediatric Research CenterPhiladelphia, PA, USA.
Department of Pathology and Laboratory Medicine, Lewis Katz School of Medicine at Temple University Philadelphia, PA, USA.
出版信息
Front Cell Neurosci. 2016 Feb 29;10:43. doi: 10.3389/fncel.2016.00043. eCollection 2016.
It is well established that the endothelium responds to mechanical forces induced by changes in shear stress and strain. However, our understanding of vascular remodeling following traumatic brain injury (TBI) remains incomplete. Recently published studies have revealed that lung and umbilical endothelial cells produce extracellular microvesicles (eMVs), such as microparticles, in response to changes in mechanical forces (blood flow and mechanical injury). Yet, to date, no studies have shown whether brain endothelial cells produce eMVs following TBI. The brain endothelium is highly specialized and forms the blood-brain barrier (BBB), which regulates diffusion and transport of solutes into the brain. This specialization is largely due to the presence of tight junction proteins (TJPs) between neighboring endothelial cells. Following TBI, a breakdown in tight junction complexes at the BBB leads to increased permeability, which greatly contributes to the secondary phase of injury. We have therefore tested the hypothesis that brain endothelium responds to mechanical injury, by producing eMVs that contain brain endothelial proteins, specifically TJPs. In our study, primary human adult brain microvascular endothelial cells (BMVEC) were subjected to rapid mechanical injury to simulate the abrupt endothelial disruption that can occur in the primary injury phase of TBI. eMVs were isolated from the media following injury at 2, 6, 24, and 48 h. Western blot analysis of eMVs demonstrated a time-dependent increase in TJP occludin, PECAM-1 and ICAM-1 following mechanical injury. In addition, activation of ARF6, a small GTPase linked to extracellular vesicle production, was increased after injury. To confirm these results in vivo, mice were subjected to sham surgery or TBI and blood plasma was collected 24 h post-injury. Isolation and analysis of eMVs from blood plasma using cryo-EM and flow cytometry revealed elevated levels of vesicles containing occludin following brain trauma. These results indicate that following TBI, the cerebral endothelium undergoes vascular remodeling through shedding of eMVs containing TJPs and endothelial markers. The detection of this shedding potentially allows for a novel methodology for real-time monitoring of cerebral vascular health (remodeling), BBB status and neuroinflammation following a TBI event.
内皮细胞对由剪切应力和应变变化引起的机械力产生反应,这一点已得到充分证实。然而,我们对创伤性脑损伤(TBI)后血管重塑的理解仍不完整。最近发表的研究表明,肺和脐内皮细胞会响应机械力(血流和机械损伤)的变化而产生细胞外微泡(eMVs),如微粒。然而,迄今为止,尚无研究表明脑内皮细胞在TBI后是否会产生eMVs。脑内皮高度特化,形成血脑屏障(BBB),该屏障调节溶质向脑内的扩散和转运。这种特化很大程度上归因于相邻内皮细胞之间紧密连接蛋白(TJPs)的存在。TBI后,BBB处紧密连接复合物的破坏导致通透性增加,这在很大程度上促成了损伤的第二阶段。因此,我们检验了这样一个假设,即脑内皮细胞通过产生含有脑内皮蛋白(特别是TJPs)的eMVs来响应机械损伤。在我们的研究中,原代成人脑微血管内皮细胞(BMVEC)受到快速机械损伤,以模拟TBI原发性损伤阶段可能发生的内皮突然破坏。在损伤后2、6、24和48小时从培养基中分离eMVs。对eMVs的蛋白质印迹分析表明,机械损伤后TJP闭合蛋白、PECAM-1和ICAM-1呈时间依赖性增加。此外,与细胞外囊泡产生相关的小GTP酶ARF6的激活在损伤后增加。为了在体内证实这些结果,对小鼠进行假手术或TBI,并在损伤后24小时收集血浆。使用冷冻电子显微镜和流式细胞术从血浆中分离和分析eMVs,发现脑外伤后含有闭合蛋白的囊泡水平升高。这些结果表明,TBI后,脑内皮通过释放含有TJPs和内皮标志物的eMVs进行血管重塑。这种释放的检测可能为实时监测TBI事件后脑血管健康(重塑)、BBB状态和神经炎症提供一种新方法。