Yu Fengshan, Kamada Hiroshi, Niizuma Kuniyasu, Endo Hidenori, Chan Pak H
Department of Neurosurgery, Stanford University School of Medicine, Stanford, California, USA.
J Neurotrauma. 2008 Mar;25(3):184-95. doi: 10.1089/neu.2007.0438.
Matrix metalloproteinase-9 (MMP-9) activation plays an important role in blood-brain barrier (BBB) dysfunction after central nervous system injury. Oxidative stress is also implicated in the pathogenesis after cerebral ischemia and spinal cord injury (SCI), but the relationship between MMP-9 activation and oxidative stress after SCI has not yet been clarified. We examined MMP-9 expression after SCI using copper/zinc-superoxide dismutase (SOD1) transgenic (Tg) rats. Our results show that MMP-9 activity significantly increased after SCI in both SOD1 Tg rats and their wild-type (Wt) littermates, although the increase was less in the SOD1 Tg rats. This pattern of MMP-9 expression was further confirmed by immunostaining and Western blot analysis. In situ zymography showed that gelatinolytic activity increased after SCI in the Wt rats, while the increase was less in the Tg rats. Evans blue extravasation increased in both the Wt and Tg rats, but was less in the SOD1 Tg rats. Inhibitor studies showed that, with an intrathecal injection of SB-3CT (a selective MMP-2/MMP-9 inhibitor), the MMP activity, Evans blue extravasation, and apoptotic cell death decreased after SCI. We conclude that increased oxidative stress after SCI leads to MMP-9 upregulation, BBB disruption, and apoptosis, and that overexpression of SOD1 in Tg rats decreases oxidative stress and further attenuates MMP-9 mediated BBB disruption.
基质金属蛋白酶-9（MMP-9）的激活在中枢神经系统损伤后的血脑屏障（BBB）功能障碍中起重要作用。氧化应激也与脑缺血和脊髓损伤（SCI）后的发病机制有关，但SCI后MMP-9激活与氧化应激之间的关系尚未阐明。我们使用铜/锌超氧化物歧化酶（SOD1）转基因（Tg）大鼠检测了SCI后的MMP-9表达。我们的结果表明，SCI后SOD1 Tg大鼠及其野生型（Wt）同窝仔鼠的MMP-9活性均显著增加，尽管SOD1 Tg大鼠的增加幅度较小。免疫染色和蛋白质印迹分析进一步证实了这种MMP-9表达模式。原位酶谱分析表明，Wt大鼠SCI后明胶酶活性增加，而Tg大鼠的增加幅度较小。伊文思蓝外渗在Wt和Tg大鼠中均增加，但SOD1 Tg大鼠中较少。抑制剂研究表明，鞘内注射SB-3CT（一种选择性MMP-2/MMP-9抑制剂）后，SCI后MMP活性、伊文思蓝外渗和凋亡细胞死亡减少。我们得出结论，SCI后氧化应激增加导致MMP-9上调、BBB破坏和细胞凋亡，并且Tg大鼠中SOD1的过表达降低了氧化应激并进一步减轻了MMP-9介导的BBB破坏。
