PAs/MMPs 酵素系統在鼷鼠感染 犬蛔蟲造成肺部病變機制之探討

PAs/MMPs cascade activation in Toxocara canis-induced pulmonary pathogenesis of BALB/c mice

簡慧曇(Hui-Tan Chien)

指導教授 ： 李秀雄

中山醫學大學/醫學院/醫學研究所/碩士(2006年)

https://doi.org/10.6834/CSMU.2006.00047

摘要

寄生於犬科動物腸道內的犬蛔蟲(Toxocara canis; T. canis)，若感染人或鼠等非犬科動物則可能造成犬蛔蟲幼蟲移行症，像是出現呼吸系統症狀。但至今有關纖溶酶原活化物與基質金屬蛋白酶在犬蛔蟲致病機轉中所扮演的角色仍不清楚。本研究探討鼷鼠感染2,000顆具感染力的犬蛔蟲胎蟲卵造成肺部病變及纖溶酶原活化物(plasminogen activators; PAs)與基質金屬蛋白酶(matrix metalloproteinases; MMPs)的活化情形。
觀察鼷鼠肺部組織切片，在感染後第4天至14天的感染組白血球浸潤及出血發炎現象逐漸嚴重。利用casein及gelatin zymography分析細胞外基質降解相關蛋白的活性，結果發現相較於未感染組，感染後第4天肺部70 kDa tPA及55 kDa uPA的活性有明顯增加。感染後第4到7天，94 kDa MMP-9的活性也有明顯增加，以感染後第4天達到最高活性。而感染後第7到56天，68 kDa MMP-2的活性也有明顯增加。西方墨點法分析細胞基質降解情形，測出感染組220 kDa單體纖維結合蛋白(fibronectin; FN)的蛋白表現有明顯增加的情形。以免疫組織化學染色法偵測tPA、uPA、MMP-2、MMP-9及纖維結合蛋白分布情形。
這些結果觀察到當犬蛔蟲感染造成鼷鼠急性發炎、胞外基質降解等肺部病變的同時，纖溶酶原活化物與基質金屬蛋白酶的活化也有增加的現象，顯示彼此有密切的關聯性。研究結論推測，犬蛔蟲感染鼷鼠模式可能有助於了解纖溶酶原活化物與基質金屬蛋白酶在肺部發炎機轉中所扮演的角色。

關鍵字

纖溶酶原活化物 ； 基質金屬蛋白酶犬蛔蟲

並列摘要

Toxocara canis (T. canis), the ascarid of canids, is well known to infect noncanids, including humans and mice, and causes toxocariasis such as respiratory symptoms. Heretofore, nothing was known about the association among plasminogen activators (PAs), matrix metalloproteinases (MMPs) and the pathogenesis of T. canis infection. In the present work, we investigated the pulmonary pathological alteration and the activity of PAs and MMPs in lungs of BALB/c mice after infection with 2,000 infective embryonated eggs.
A gradual increase in pathological effects after infection culminated in a severe infiltration of leukocytes and hemorrhage from days 4 to 14 post-infection (PI). Casein zymogram analysis demonstrated that 70 kDa tPA and 55 kDa uPA from the lungs at day 4 PI were active against the casein/plasminogen substrate. Gelatin zymography using substrate gelatin manifested a significant increase in the relative activity of 94 kDa MMP-9 and 68 kDa MMP-2 in T. canis -infected mice. By Western blot analysis, the protein level of 220 kDa fibronectin (FN) monomer showed a significant increase in T. canis-infected mice, compared with uninfected control. Infection with T. canis in BALB/c mice induced PAs and MMPs activity in parallel with the pathological changes of early stage pulmonary inflammation.
In conclusion, we observed PAs/MMPs cascade activation in pulmonary pathogenesis caused by T. canis larva migration. Thus, murine T. canis infection may prove to be useful in understanding the role of PAs and MMPs in pulmonary inflammation.

並列關鍵字

plasminogen activators ； matrix metalloproteinases ； Toxocara canis

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