缺氧诱导因子-1α、水通道蛋白-4 和基质金属蛋白酶-9 在创伤性脑损伤后血脑屏障破坏和脑水肿中的作用。
The role of hypoxia-inducible factor-1α, aquaporin-4, and matrix metalloproteinase-9 in blood-brain barrier disruption and brain edema after traumatic brain injury.
机构信息
Department of Neurological Surgery, Wayne State University School of Medicine, Detroit, Michigan 48201, USA.
出版信息
J Neurosurg. 2011 Jan;114(1):92-101. doi: 10.3171/2010.6.JNS10207. Epub 2010 Jul 9.
OBJECT
The present study investigated the role of hypoxia-inducible factor-1α (HIF-1α), aquaporin-4 (AQP-4), and matrix metalloproteinase-9 (MMP-9) in blood-brain barrier (BBB) permeability alterations and brain edema formation in a rodent traumatic brain injury (TBI) model.
METHODS
The brains of adult male Sprague-Dawley rats (400-425 g) were injured using the Marmarou closed-head force impact model. Anti-AQP-4 antibody, minocycline (an inhibitor of MMP-9), or 2-methoxyestradiol (2ME2, an inhibitor of HIF-1α), was administered intravenously 30 minutes after injury. The rats were killed 24 hours after injury and their brains were examined for protein expression, BBB permeability, and brain edema. Expression of HIF-1α, AQP-4, and MMP-9 as well as expression of the vascular basal lamina protein (laminin) and tight junction proteins (zona occludens-1 and occludin) was determined by Western blotting. Blood-brain barrier disruption was assessed by FITC-dextran extravasation, and brain edema was measured by the brain water content.
RESULTS
Significant (p < 0.05) edema and BBB extravasations were observed following TBI induction. Compared with sham-operated controls, the injured animals were found to have significantly (p < 0.05) enhanced expression of HIF-1α, AQP-4, and MMP-9, in addition to reduced amounts (p < 0.05) of laminin and tight junction proteins. Edema was significantly (p < 0.01) decreased after inhibition of AQP-4, MMP-9, or HIF-1α. While BBB permeability was significantly (p < 0.01) ameliorated after inhibition of either HIF-1α or MMP-9, it was not affected following inhibition of AQP-4. Inhibition of MMP reversed the loss of laminin (p < 0.01). Finally, while inhibition of HIF-1α significantly (p < 0.05) suppressed the expression of AQP-4 and MMP-9, such inhibition significantly (p < 0.05) increased the expression of laminin and tight junction proteins.
CONCLUSIONS
The data support the notion that HIF-1α plays a role in brain edema formation and BBB disruption via a molecular pathway cascade involving AQP-4 and MMP-9. Pharmacological blockade of this pathway in patients with TBI may provide a novel therapeutic strategy.
目的
本研究旨在探讨缺氧诱导因子-1α（HIF-1α）、水通道蛋白-4（AQP-4）和基质金属蛋白酶-9（MMP-9）在啮齿动物创伤性脑损伤（TBI）模型中血脑屏障（BBB）通透性改变和脑水肿形成中的作用。
方法
采用 Marmarou 闭合性颅脑损伤模型致成年雄性 Sprague-Dawley 大鼠（400-425g）脑损伤。伤后 30 分钟静脉给予抗 AQP-4 抗体、米诺环素（MMP-9 抑制剂）或 2-甲氧基雌二醇（2ME2，HIF-1α 抑制剂）。伤后 24 小时处死大鼠，检测其脑组织蛋白表达、BBB 通透性和脑水肿。Western blot 法检测 HIF-1α、AQP-4、MMP-9 及血管基底膜蛋白（层粘连蛋白）和紧密连接蛋白（闭合蛋白-1 和封闭蛋白）的表达。FITC-葡聚糖外渗评估 BBB 破坏，脑水含量测定脑水肿。
结果
TBI 诱导后观察到明显的（p<0.05）水肿和 BBB 外渗。与假手术对照组相比，损伤动物的 HIF-1α、AQP-4 和 MMP-9 表达明显增强（p<0.05），而层粘连蛋白和紧密连接蛋白含量明显降低（p<0.05）。抑制 AQP-4、MMP-9 或 HIF-1α 后，水肿明显减少（p<0.01）。抑制 HIF-1α 或 MMP-9 后 BBB 通透性明显改善（p<0.01），而抑制 AQP-4 后则无明显变化。抑制 MMP 可逆转层粘连蛋白的丢失（p<0.01）。最后，抑制 HIF-1α 可显著抑制 AQP-4 和 MMP-9 的表达（p<0.05），但可显著增加层粘连蛋白和紧密连接蛋白的表达（p<0.05）。
结论
数据支持 HIF-1α 通过涉及 AQP-4 和 MMP-9 的分子途径级联在脑水肿形成和 BBB 破坏中发挥作用的观点。在 TBI 患者中阻断该途径可能提供一种新的治疗策略。
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