实验性自身免疫性脑脊髓炎小鼠血脑屏障通透性与紧密连接蛋白-5的变化

目的观察实验性自身免疫性脑脊髓炎(EAE)小鼠血脑屏障(BBB)通透性与紧密连接蛋白-5(claudin-5)表达的变化。方法 40只C57BL/6小鼠随机分为EAE组和正常对照组,应用髓鞘少突胶质细胞糖蛋白35-55诱导制作小鼠EAE模型,每日进行神经功能缺损评分。采用苏木精-伊红、髓鞘染色和免疫组化法观察炎症细胞浸润、髓鞘脱失及轴索损坏程度。伊文思蓝染色和Western blot法观察BBB通透性和claudin-5表达的变化。结果与正常对照组比较,EAE组小鼠神经功能缺损评分、炎症细胞浸润、髓鞘脱失、轴索损坏和BBB通透性均明显增加;而claudin-5表达显著降低(均P0.01)。BBB通透性的变化与平均神经功能缺损评分、炎症细胞浸润和轴索损坏均呈正相关(P0.01);而与claudin-5表达水平呈负相关(P0.05)。结论 EAE发病过程中claudin-5表达减少,可能导致BBB通透性增加,使外周大量的炎症反应细胞向中枢迁移,继而进一步加重中枢的炎症反应。

Changes of Blood-brain Barrier Permeability and Tight Junction Protein Claudin-5 in the Brain of Mice with Experimental Autoimmune Encephalomyelitis

Aim To investigate the changes of blood-brain barrier （BBB） permeability and tight junction protein claudin-5 in the brain of mice with experimental autoimmune encephalomyelitis （EAE）. Methods Forty C57BL/6 mice were randomly divided into a EAE group and a normal control group. EAE was induced with myelin oligodendrocyte glycoprotein35.55. The score ofneurologic impairment was measured twice everyday. HE staining, myelin staining and immunohistochemical staining were used to evaluate the infiltration of inflammatory cells, the degree of myelin depigrnentation and axonal injury. Evans blue staining and Western-blot assay were used to observe the changes of BBB permeability and the expression of claudin-5 in the brain. Results Compared with the normal control group, the score of neurologic impairment, the infiltration of inflammatory ceils, demyelination and axonal injury increased significantly in EAE mice. The BBB permeabilityincreased but the expression of claudin-5 （all P〈0.01） decreased in EAE mice. The mean neurologic impairment scores, the infiltration of inflammatory cells, the degree of myelin depigmentation were positively correlated with the increased BBB permeability, but the expression of claudin-5 negatively correlated with the increased BBB permeability. Conclusion It is probable that reduced expression of claudin-5 directly induced the increasing of BBB permeability in EAE, which result in a lot of peripheral inflammatory cells infiltrating to central nervous system （CNS） and aggravating CNS inflammatory response.