Molecular Mechanisms of Formation of Blood-Brain-Barrier ; Effects of Astrocyte-Secreting Factors

中枢神经系统的毛细血管内皮作为一种高度选择性的渗透屏障，相当于血脑屏障（BBB），但负责屏障功能的分子尚未确定。在本研究中，我们评估了紧密连接相关蛋白ZO-1和7 H6在脑内皮屏障功能发展中的作用。从猪脑中分离毛细血管内皮细胞并以汇合密度培养。然后用星形胶质细胞条件培养基（CM）、8-（4-氯苯硫基）环腺苷酸（cAMP）和磷酸二酯酶抑制剂的组合处理。在10小时内诱导了10倍以上的屏障功能，在跨内皮电阻和菊糖和甘露醇的渗透性方面。同时，在对照中检测不到的7 H6抗原在细胞边缘被诱导，而ZO-1的表达在对照和处理的细胞之间没有显著变化。这些结果表明星形胶质细胞CM和CAMP在BBB诱导中的重要性，并提示7 H6抗原在屏障功能的发展中起关键作用。本研究还提示星形胶质细胞CM和cAMP在脑毛细血管内皮细胞诱导7 H6抗原中可能起不同的作用。

The capillary endothelium of the central nervous system functions as a highly selective permeability barrier, corresponding to the blood-brain barrier (BBB), but the molecules responsible for the barrier function have not been identified. In the present study, we assessed the roles of the tight junction-associated proteins ZO-1 and 7H6 in the development of brain endothelial barrier function. Capillary endothelial cells were isolated from porcine brain and cultured at a confluent density. Then they were treated with a combination of astrocyte conditioned medium (CM), 8-(4-chlorophenylthio) cyclic AMP (cAMP) and phosphodiesterase inhibitor. More than 10-fold higher barrier function was induced within 10-h, in terms of transendothelial electrical resistance and permeability to inulin and mannitol. Concomitantly, 7H6 antigen, which was not detectable in the control, was induced at the cell border, whereas the expression of ZO-1 did not change significantly between the control and treated cells. These results showed the importance of astrocyte CM and CAMP for the induction of the BBB and suggested the crucial role of 7H6 antigen in the development of the barrier function. This study also suggested that astrocyte CM and cAMP may function differently in the induction of 7H6 antigen in brain capillary endothelial cells.