基質金屬蛋白酶-9在鼷鼠罹患廣東住血線蟲症誘發腦障壁損傷之研究

血液-中樞神經系統障壁（blood- central nervous system barrier）可調節物質的傳輸，如離子、大分子、免疫細胞及病原體。本試驗利用廣東住血線蟲（Angiostrongylus cantonensis）感染鼷鼠之動物模型，來研究基質金屬蛋白酶（Matrix metalloproteinase, MMP）-9在感染時，造成血腦障壁（blood-brain barrier）及血腦脊髓液障壁（blood- cerebrospinal fluid barrier）損傷之角色。結果顯示，廣東住血線蟲感染鼷鼠會促進核轉錄因子（nuclear factor kappa-light-chain-enhancer of B cells, NF-κB）及核因子抑制蛋白（inhibitor of κB, IκB）的磷酸化，給予MG132處理組發現，經MG132處理會減少NF-κB的磷酸化及MMP-9的活性，顯示感染誘發MMP-9的活化是藉由核轉錄因子這個路徑。在廣東住血線蟲感染的鼷鼠腦部發現緊密連結蛋白claudin-5表現量是減少的，但在腦脊髓液中是增加的，給予廣效型基質金屬蛋白酶抑制劑（GM6001）能減輕claudin-5的降解，意味著感染會造成血腦脊髓液障壁損傷而促使claudin-5釋放到腦脊髓液中，是與MMP-9活性有關。進一步，以廣東住血線蟲感染MMP-9基因剔除鼠相較於對照組的結果發現，MMP-9基因剔除會減少因感染造成血腦障壁瓦解（緊密連結降解、細胞基底膜瓦解及星狀膠細胞損傷）及血腦障壁通透性增加。這些結果顯示，在廣東住血線蟲感染鼷鼠誘發嗜伊紅性腦膜腦炎中，血腦障壁及血腦脊髓液障壁的破壞，是與MMP-9有密切關聯的。本試驗結果顯示MMP-9在感染廣東住血線蟲侵入腦部誘發嗜伊紅性腦膜腦炎之病理機轉扮演重要的角色，並提供一個新的治療策略，達到降低死亡率的目的。

The blood- central nervous system barrier regulates the movement of ions, macromolecules, immune cells and pathogens. The objective of this study was to investigate the role of the matrix metalloproteinase (MMP)-9 in the disruption of blood-brain barrier (BBB) and blood- cerebrospinal fluid (CSF) barrier during infection with rat nematode lungworm Angiostrongylus cantonensis. The results showed that phosphorylation of IκB and NF-κB was increased in brain, treatment with MG132 reduced the phosphorylation of NF-κB and the activity of MMP-9, indicating upregulation of MMP-9 through the NF-κB signaling pathway during infection. Claudin-5 was reduced in the brain but elevated in the CSF, treatment with the MMP inhibitor GM6001 attenuated the degradation of claudin-5, implying that A. cantonensis infection caused blood-CSF barrier breakdown by MMP-9 and led to claudin-5 release into the CSF. In addition, BBB disruption is associated with tight junction protein degradation, basal membrane disruption, and astrocyte damage led to elevate BBB permeability, which attenuated in MMP-9 knockout mice compared with wild-type mice during A. cantonensis infection. These results suggested that disruption of BBB and blood-CSF barrier was caused by MMP-9 in angiostrongyliasis meningoencephalitis. This study improves understanding of molecular mechanisms that underlie brain invasion by A. cantonensis, which is a key step in the pathogenesis of meningoencephalitis, and can offer a new strategy to reduce mortality.