鼷鼠感染廣東住血線蟲誘發蛋白分解酵素與血液-中樞神經系統障壁損傷

廣東住血線蟲主要侵犯中樞神經系統造成嗜伊紅性白血球浸潤到蜘蛛膜下腔引起嗜伊紅性腦膜炎，鼷鼠感染廣東住血線蟲誘發嗜伊紅性腦膜炎，在腦脊髓液中組織型血纖維酶原活化因子(tissue-type plasminogen activator, tPA)、尿激酶血纖維活化因子(urokinase-type plasminogen activator, uPA)及基質金屬蛋白酶-9 (matrix metalloproteinases-9, MMP-9)的活性均比未感染的鼷鼠有明顯增加。在本研究中發現，腦脊髓液中嗜伊紅性白血球數量與總蛋白質濃度及白蛋白濃度有高度的相關性，分別以substrate zymography偵測tPA、uPA及MMP-9的活性、RT-PCR及Western blotting偵測MMP-9及TIMP-1 mRNA和蛋白質表現；再利用Spearman’s ranking進行相關性分析，結果顯示，類腦脊髓液中嗜伊紅性白血球數量、總蛋白質濃度及白蛋白濃度與tPA、uPA及MMP-9的活性有明顯的相關性，且MMP-9/TIMP-1間的不平衡與嗜伊紅性腦膜炎有關，在組織免疫化學染色發現MMP-9和TIMP-1的表現主要在嗜伊紅性白血球及巨噬細胞上。當使用MMPs專一抑制劑(GM6001)處理感染廣東住血線蟲的鼷鼠，類腦脊髓液中嗜伊紅性白血球、MMP-9活性及總蛋白質濃度比未處理組有明顯減少。因此，PAs和MMP-9活性的增加及MMP-9/TIMP-1處於不平衡狀態與廣東住血線蟲誘發血液-中樞神經系統之障壁損壞造成嗜伊紅性腦膜炎有關，且腦脊髓液中嗜伊紅性白血球數量與總蛋白質濃度及白蛋白濃度可作為血液-中樞神經系統之障壁損壞的指標。

Angiostrongylosis is a neurological disorder caused by invasion of the central nervous system and induced the infiltration of eosinophils into the subarachnoid space. The pathological changes are eosinophilic meningitis and eosinophilic meningoencephalitis by developing larvae of Angiostrongylus cantonensis. The activities of tissue-type plasminogen activator (tPA), urokinase-type activator (uPA) and MMP-9 in cerebrospinal fluid (CSF) were significantly increased in Angiostrongylus cantonensis infected mice with eosinophilic meningitis compared to that in uninfected mice. The cerebrospinal-like fluid eosinophils significantly correlated with total protein and albumin. The uPA, tPA, and MMP-9 activities were detected by substrate zymography. MMP-9 and tissue inhibitors of metalloproteinases -1(TIMP-1) mRNA and protein levels were examined by RT-PCR and immunoblots, respectively. In cerebrospinal-like fluid, the expression of eosinophils, total protein and albumin contents correlated significantly with uPA, tPA, and MMP-9 intensity by Spearman’s ranking correlation test. MMP-9/TIMP-1 imbalance in angiostrongylosis may be associated with eosinophilic meningitis. Immunohistochemistry demonstrated that MMP-9 and TIMP-1 localized in eosinophils and macrophages. In addition, administration of MMPs inhibitor, GM6001, in infected mice, MMP-9 enzyme activity, albumin concentrations and eosinophils declined significantly from their preinjection highs. These results suggested that PAs and MMP-9 proteolytic cascade and MMP-9/TIMP-1 imbalance may be associated with blood-CNS barrier disruption and CSF total protein, albumin and eosinophil might be an indicator of the blood-CNS barrier damage in eosinophilic meningitis caused by Angiostrongylus cantonensis.