MMP-9在单纯疱疹病毒性脑炎中的表达及对血脑屏障的影响

The expression of MMP-9 and its effect on BBB permeability in herpes simplex encephalitis mice

目的研究单纯疱疹病毒感染小鼠脑组织后MMP-9的变化及对血脑屏障通透性的影响。方法小鼠颅内注射单纯疱疹病毒1型(HSV-1)制造单纯疱疹病毒性脑炎模型,于感染后第3天、第7天,应用明胶酶谱分析检测脑组织中MMP-9活性,免疫荧光共聚焦检测MMP-9的细胞来源,通过检测渗出到脑血管外的伊文斯蓝(Evans Blue,EB)的含量以及脑组织水含量观察血脑屏障的通透性。结果 HSV-1感染后第3天、第7天病毒组中MMP-9活性较正常对照组明显增高,MMP-9活性增高与血脑屏障通透性增高相一致,给予MMP-9抑制剂BB-94后血脑屏障通透性降低,激活的小胶质细胞是MMP-9的主要来源。结论激活的小胶质细胞表达MMP-9破坏血脑屏障,在单纯疱疹病毒性脑炎的发病机制中起着重要作用。

Objective To investigate the expression and the roles of matrix metalloproteinase-9（ MMP-9） protein in brain edema formation in herpes simplex encephalitis（ HSE）. Methods Mice were inoculated intracerebrally with herpes simplex virus type 1（ HSV-1） to form herpes simplex encephalitis. MMP-9 gelatinolytic activity was assessed by zymography from brain tissues 3 days and 7 days after HSV-1 infected. The expression of MMP-9 was detected by immunofluorescence staining in the brain slices. The blood-brain barrier（ BBB） permeability was quantitated by Evans blue dye extravasations and brain water content. Results We found that HSE mice were significantly associated with raised levels of MMP-9 at 3days and 7 days after infection. The results were concordant with the increased BBB permeability and brain water content.The administration of MMP-9 inhibitor BB-94（ 30 mg·kg^- 1） significantly attenuated BBB permeability. Double-labeling experiments showed that the MMP-9 expression was colocalized with actived microglia cells. Conclusion This study demonstrates that excessive activation of MMP-9 from actived microglia is deleterious to the brain,which is associated with the degree of BBB leakage.