Differential regulation of thrombospondin-1 and thrombospondin-2 after focal cerebral ischemia/reperfusion
Differential regulation of thrombospondin-1 and thrombospondin-2 after focal cerebral ischemia/reperfusion
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DOI：
10.1161/01.str.0000047100.84604.ba
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发表时间：
2003-01-01
期刊：
影响因子：
8.3
通讯作者：
Hsu, CY
中科院分区：
文献类型：
--
作者：
Lin, TN;Kim, GM;Hsu, CY
背景与目的：血管生成发生在脑缺血后，血管生成的程度与脑卒中患者的生存相关。然而，缺血后血管生成是短暂的，可能在缺血损伤后几周内完全终止。缺血后血管生成过程溶解的分子机制尚不清楚。虽然血管生成基因在缺血性脑卒中模型中的表达已被研究，但对脑缺血后血管抑制基因的激活尚未进行研究。血小板反应蛋白(TSP)-1和TSP-2是天然存在的血管抑制因子，可抑制体内血管生成。本研究旨在探讨大鼠局灶性缺血模型中TSP-1和TSP-2的表达与血管生成过程演变的关系。方法：大鼠大脑中动脉区域皮质缺血60分钟，再灌注2周。采用Northern和Western blot分析分别在mRNA和蛋白水平上研究TSP-1和TSP-2表达的时间谱。采用原位杂交和免疫组织化学方法检测空间表达模式。采用双免疫染色法确定TSP-1和TSP-2的细胞来源。结果：缺血后TSP-1呈双相表达，分别在缺血后1和72 h达到表达高峰。轻脑膜内皮细胞是第一个TSP-1峰的唯一来源，而内皮细胞、胶质细胞、神经元细胞和巨噬细胞则是第二个TSP-1表达峰的来源。TSP-2的表达时间较晚，呈单相表达，在缺血后2周达到峰值。在内皮细胞、神经元细胞和巨噬细胞中观察到TSP-2的免疫反应性，但在胶质细胞中没有。TSP-1在血管生成高峰期前表达，而TSP-2在血管生成高峰期表达，并持续到血管生成完全消退。结论：两种主要的血管抑制因子TSP-1和TSP-2在缺血脑中的表达强度不同，但不同细胞来源的时间表达谱不同。这些血管抑制因子，尤其是TSP-2的表达可能有助于缺血后血管生成的自发消退。在缺血脑中调控血管生成和血管抑制因子平衡的分子机制有待进一步研究。
Background and Purpose-Angiogenesis occurs after cerebral ischemia, and the extent of angiogenesis has been correlated with survival in stroke patients. However, postischemic angiogenesis is short-lived and may be completely terminated within a few weeks after ischemic insult. The molecular mechanism underlying the dissolution of postischemic angiogenic processes is poorly understood. Although the expression of angiogenic genes has been studied in ischemic stroke models, the activation of angiostatic genes after cerebral ischemia has not been investigated. Thrombospondin (TSP)-1 and TSP-2 are naturally occurring angiostatic factors, which inhibit angiogenesis in vivo. The aim of the present study was to explore the expression of TSP-1 and TSP-2 in relation to the evolution of angiogenic, process in a focal ischemia model in rats.Methods-Rats underwent cortical ischemia in the middle cerebral artery territory for 60 minutes and reperfusion for up to 2 weeks. Northern and Western blot analysis were used to study the temporal profile of TSP-1 and TSP-2 expression at the mRNA and protein level, respectively. In situ hybridization and immunohistochemical studies were used to examine the spatial expression patterns. Double immunostaining was applied to define the cellular origins of TSP-1 and TSP-2.Results-A biphasic expression of TSP-1 was noted after ischemia, peaking at 1 and 72 hours. Endothelial cells in the leptomeninges were the only source of the first TSP-1 peak, whereas endothelial, glial, neuronal, and macrophage cells contributed to the second peak of TSP-1 expression. TSP-2 expression occurred much later and in a monophasic manner, peaking 2 weeks after ischemia. TSP-2 immunoreactivity was observed in endothelial, neuronal, and macrophage, but not glial, cells. TSP-1 was expressed before the peak of angiogenesis, whereas robust TSP-2 expression occurred at the peak of angiogenesis and continued into the period when angiogenesis had completely resolved.Conclusions-Robust expression of TSP-1 and TSP-2, 2 major angiostatic factors, was noted in the ischemic brain with different temporal expression profiles from different cellular origins. The expression of these angiostatic factors, especially TSP-2, likely contributes to the spontaneous resolution of postischemic angiogenesis. Further studies are needed to explore the molecular mechanisms that regulate the balance of angiogenic and angiostatic factors in the ischemic brain.