Absence of tight junctions between microvascular endothelial cells inhuman cerebellar hemangioblastomas
Absence of tight junctions between microvascular endothelial cells inhuman cerebellar hemangioblastomas
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DOI：
10.1227/01.neu.0000223372.18607.d7
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发表时间：
2006-09-01
期刊：
影响因子：
4.8
通讯作者：
Takahashi, Jun A.
中科院分区：
文献类型：
--
作者：
Chen, Yizhao;Tachibana, Osamu;Takahashi, Jun A.
目的：内皮细胞紧密连接是血脑屏障的主要屏障。在人类血管母细胞瘤中，囊肿形成是常见且重要的临床表现。虽然大多数研究者认为血管母细胞瘤中的囊肿形成可能是由BBB的破坏引起的，但囊肿形成的潜在分子机制仍然未知。目前，关于人血管母细胞瘤微血管内皮细胞紧密连接改变的报道较少。本研究旨在探讨人血管母细胞瘤微血管扩张过程中紧密连接及其主要分子组分的变化。通过电子显微镜检查血管母细胞瘤和对照脑的微血管中的紧密连接。采用免疫组织化学和免疫荧光双镜技术分析CLN 5在正常脑和血管母细胞瘤中的表达及其与星形细胞终足的关系。实时定量逆转录聚合酶链反应和Western印迹法检测CLN 5在血管母细胞瘤中的表达水平。三重免疫荧光显微镜分析血管内皮生长因子，血管内皮生长因子-R1，胎盘生长因子的血管母细胞瘤的微血管上的共表达。将临床和实验数据进行相关分析，采用单因素方差分析、Kruskal-Wallis检验和斯皮尔曼等级相关检验。结果：在对照组脑中，由连续的紧密连接链密封。在囊性血管母细胞瘤中，在相邻的内皮细胞之间可以发现明显的细胞旁裂隙。部分内皮细胞间存在粘附连接，但无紧密连接。与对照组相比，囊性血管母细胞瘤中CLN 5的表达降低（P < 0.05）。在大多数血管母细胞瘤中检测到磷酸化CLN 5，但在对照脑中未检测到。血管母细胞瘤中的微血管显示星形细胞终足明显缺失。在内皮细胞中检测到血管内皮生长因子、血管内皮生长因子-R1和胎盘生长因子的共表达。斯皮尔曼等级相关性检验显示，CLN 5表达越高，囊性形成越少（相关系数= -0.520; P = 0.009）。结论：小脑血管母细胞瘤中血脑屏障紧密连接的连续性被中断。在血管母细胞瘤的微血管中可以发现星形细胞终足和紧密连接的显著缺失，这可能导致这些肿瘤中的BBB的破坏。这些发现表明，紧密连接的缺乏可能在血管母细胞瘤的囊肿形成中发挥作用。
OBJECTIVE: Endothelial tight junctions form the main barrier of the blood-brain barrier (BBB). In human hemangioblastomas, cyst formation is a common and important clinical manifestation. Although most researchers consider that the cyst formation in hemangioblastomas may be caused by the breakdown of the BBB, the underlying molecular mechanisms for cyst formation remain unknown. At present, there are few reports about the change of tight junctions in microvessel endothelium of human hemangioblastomas. The purpose of this research is to investigate the change of tight junction and its major molecular components in microvessel enclothelium of human hemangioblastomas.METHODS: Twenty-four consecutive patients with cerebellar hemangioblastomas were studied. Tight junctions in the microvessels of hemangioblastomas and the control brain were examined by electron microscopy. Immunohistochemistry and double immunofluorescent microscopy were used to analyze the expression of CLN5 and its relationship with astrocytic endfeet in the control brain and hemangioblastomas. Quantitative real-time reverse-transcriptase polymerase chain reaction and Western blots were used to investigate the expression level of CLN5 in hemangioblastomas. Triple immunofluorescent microscopy was used to analyze the coexpression of vascular endothelial growth factor, vascular endothelial growth factor-R1, and placenta growth factor on microvessels of hemangioblastomas. Clinical and experimental data were correlated and analyzed by the one-way analysis of variance, Kruskal-Wallis test, and Spearman rank correlation test. the paracellular cleft between adjacent endothelial cells isRESULTS: In the control brain, sealed by continuous strands of tight junctions. In cystic hemangioblastomas, a significant paracellular cleft could be found between adjacent endothelial cells. Some endothelial cells were connected with adherens junction and no tight junction was found between them. Compared with the control brain, expression of CLN5 was decreased in cystic hemangioblastomas (P < 0.05). Phosphorylated CLN5 was detected in most hemangioblastomas, but not in the control brain. Microvessels in hemangioblastomas showed a significant absence of astrocytic endfeet. Coexpression of vascular endothelial growth factor, vascular endothelial growth factor-R1, and placenta growth factor was detected in the endothelial cells. The Spearman rank correlation test showed a significant correlation between a greater degree of CLN5 expression and less morphological cystic formation in these patients studied (correlation coefficient = -0.520; P = 0.009).CONCLUSION: The continuity of tight junctions of the BBB is interrupted in human cerebellar hemangioblastomas. Significant absence of astrocytic endfeet and tight junctions can be found in microvessels of hemangioblastomas, which may lead to the breakdown of the BBB in these tumors. These findings suggest that the absence of tight junctions might play a role in cyst formation of hemangioblastomas.