Blood-brain barrier breakdown involves four distinct stages of vascular damage in various models of experimental focal cerebral ischemia
Blood-brain barrier breakdown involves four distinct stages of vascular damage in various models of experimental focal cerebral ischemia
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DOI：
10.1038/jcbfm.2014.199
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发表时间：
2015-02-01
影响因子：
6.3
通讯作者：
Michalski, Dominik
中科院分区：
文献类型：
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作者：
Krueger, Martin;Bechmann, Ingo;Michalski, Dominik
缺血性中风不仅损害神经元功能，而且影响脑血管系统，如血脑屏障（BBB）完整性的丧失所示。因此，治疗性再通包括传统上归因于"再灌注损伤"的出血性转化和出血的增加的风险。为了研究缺血/再灌注相关的血脑屏障开放的机制，我们应用多种免疫荧光标记和电子显微镜在血栓栓塞性中风大鼠模型以及小鼠模型的永久性和短暂性局灶性脑缺血。在这些模型中，通过静脉内给予的异硫氰酸荧光素（FITC）-白蛋白的外渗来鉴定显示BBB破坏的区域。24小时后，在应用的模型中，FITC-白蛋白渗漏区域中紧密连接和粘附连接标志物的表达始终保持不变。然而，用异凝集素B4进行的凝集素染色表明内皮细胞的结构改变，这通过电子显微镜证实。虽然内皮细胞的超微结构改变在所应用的模型（包括再灌注情况）之间没有差异，但我们定期确定了血管改变，我们建议这反映了BBB破裂的四个不同阶段，最终导致内皮细胞的损失。因此，我们的数据有力地表明，缺血相关的血脑屏障衰竭主要是由内皮细胞变性引起的。因此，除了已建立的再通策略外，保护内皮细胞可能代表一种有前途的治疗方法。
Ischemic stroke not only impairs neuronal function but also affects the cerebral vasculature as indicated by loss of blood brain barrier (BBB) integrity. Therefore, therapeutical recanalization includes an enhanced risk for hemorrhagic transformation and bleeding, traditionally attributed to a 'reperfusion injury'. To investigate the mechanisms underlying ischemia-/reperfusion-related BBB opening, we applied multiple immunofluorescence labeling and electron microscopy in a rat model of thromboembolic stroke as well as mouse models of permanent and transient focal cerebral ischemia. In these models, areas exhibiting BBB breakdown were identified by extravasation of intravenously administered fluorescein isothiocyanate (FITC)-albumin. After 24 hours, expression of markers for tight and adherens junctions in areas of FITC-albumin leakage consistently remained unaltered in the applied models. However, lectin staining with isolectin B4 indicated structural alterations in the endothelium, which were confirmed by electron microscopy. While ultrastructural alterations in endothelial cells did not differ between the applied models including the reperfusion scenario, we regularly identified vascular alterations, which we propose to reflect four distinct stages of BBB breakdown with ultimate loss of endothelial cells. Therefore, our data strongly suggest that ischemia-related BBB failure is predominantly caused by endothelial degeneration. Thus, protecting endothelial cells may represent a promising therapeutical approach in addition to the established, recanalizing strategies.