[论文解读] Cyclooxygenase Inhibition Limits Blood-Brain Barrier Disruption following Intracerebral Injection of Tumor Necrosis Factor-alpha in the Rat

Eduardo Candelario‐Jalil, Saeid Taheri+6 more|ArXiv.org|Nov 13, 2007

Barrier Structure and Function Studies参考文献 35被引用 8

一句话总结

本研究证明，环氧化酶（COX）抑制，尤其是通过COX-1阻断，可显著限制大鼠脑内肿瘤坏死因子-α（TNF-α）诱导的血脑屏障（BBB）破坏。通过使用吲哚美辛及选择性COX抑制剂，作者表明COX抑制可减少BBB通透性，减弱MMP-9和MMP-3的活化，并维持谷胱甘肽水平，提示COX-1在神经炎症性BBB破坏中起关键介导作用。

ABSTRACT

Increased permeability of the blood-brain barrier (BBB) is important in neurological disorders. Neuroinflammation is associated with increased BBB breakdown and brain injury. Tumor necrosis factor-a (TNF-a) is involved in BBB injury and edema formation through a mechanism involving matrix metalloproteinase (MMP) upregulation. There is emerging evidence indicating that cyclooxygenase (COX) inhibition limits BBB disruption following ischemic stroke and bacterial meningitis, but the mechanisms involved are not known. We used intracerebral injection of TNF-a to study the effect of COX inhibition on TNF-a-induced BBB breakdown, MMP expression/activity and oxidative stress. BBB disruption was evaluated by the uptake of 14C-sucrose into the brain and by magnetic resonance imaging (MRI) utilizing Gd-DTPA as a paramagnetic contrast agent. Using selective inhibitors of each COX isoform, we found that COX-1 activity is more important than COX-2 in BBB opening. TNF-a induced a significant upregulation of gelatinase B (MMP-9), stromelysin-1 (MMP-3) and COX-2. In addition, TNF-a significantly depleted glutathione as compared to saline. Indomethacin (10 mg/kg; i.p.), an inhibitor of COX-1 and COX-2, reduced BBB damage at 24 h. Indomethacin significantly attenuated MMP-9 and MMP-3 expression and activation, and prevented the loss of endogenous radical scavenging capacity following intracerebral injection of TNF-a. Our results show for the first time that BBB disruption during neuroinflammation can be significantly reduced by administration of COX inhibitors. Modulation of COX in brain injury by COX inhibitors or agents modulating prostaglandin E2 formation/signaling may be useful in clinical settings associated with BBB disruption.

研究动机与目标

• 研究环氧化酶（COX）同工酶在大鼠脑内注射TNF-α后血脑屏障（BBB）破坏中的作用。
• 确定COX抑制是否可限制神经炎症模型中BBB通透性、基质金属蛋白酶（MMP）活化及氧化应激。
• 阐明COX-1与COX-2在TNF-α诱导的炎症过程中介导BBB破坏的相对贡献。
• 评估COX抑制剂在涉及BBB破坏和神经炎症状况下的神经保护潜力。

提出的方法

• 向大鼠脑内注射TNF-α以诱导神经炎症和BBB破坏。
• 使用选择性COX-1和COX-2抑制剂评估同工酶对BBB通透性的特异性贡献。
• 通过14C-蔗糖摄取及Gd-DTPA对比剂磁共振成像（MRI）测量BBB完整性。
• 通过明胶酶谱法和Western印迹法评估MMP-9和MMP-3的表达与活性。
• 量化脑内谷胱甘肽水平以评估氧化应激与抗氧化能力。
• 给予吲哚美辛（10 mg/kg，腹腔注射）以评估非选择性COX抑制的效果。

实验结果

研究问题

• RQ1 COX抑制是否可减轻大鼠脑内注射TNF-α后BBB的破坏？
• RQ2 在TNF-α诱导的BBB破坏中，COX同工酶（COX-1或COX-2）的哪一种起更显著的作用？
• RQ3 在神经炎症背景下，COX抑制是否可减少MMP-9和MMP-3的表达与活化？
• RQ4 COX抑制是否可通过防止谷胱甘肽耗竭来维持内源性抗氧化能力？
• RQ5 COX活性、MMP上调与氧化应激之间是否存在BBB破坏的机制关联？

主要发现

• 与COX-2抑制相比，COX-1抑制在减轻TNF-α注射后BBB破坏方面更为有效。
• 吲哚美辛（10 mg/kg，腹腔注射）显著降低了24小时后脑内14C-蔗糖的摄取，表明BBB通透性下降。
• TNF-α显著上调了脑内MMP-9、MMP-3及COX-2的表达。
• 吲哚美辛显著减弱了MMP-9和MMP-3的表达与活化。
• TNF-α导致脑内谷胱甘肽显著耗竭，而吲哚美辛治疗可防止该现象。
• COX抑制维持了内源性自由基清除能力，提示其在神经炎症中对氧化应激具有保护作用。