| 摘要: | 心肌缺血再灌注傷害是冠狀動脈疾病發生以及死亡的主要原因，當心肌缺血再 灌注傷害時會大量增加細胞激素(cytokines)和趨化因子(chemokines)造成大量的白血 球在梗塞受傷區域周圍浸潤，造成發炎反應，這發炎反應不只是會引起心肌細胞的 細胞凋亡，還會損害心臟的功能，所以限制心肌缺血再灌注傷害誘發的發炎反應， 不只是會降低心肌缺血再灌注傷害的死亡率，還會減少心肌缺血再灌注傷害誘發的 心律不整以及心肌梗塞體積大小。 Lumbrokinase 是近年由中藥地龍所抽提出的蛋白質分解酵素，其由具有生物活 性的酵素組成，包括 plasminogen activator 和 plasmin，在 Lumbrokinase 中的酵素只 有在纖維蛋白存在的情況下才有血栓溶解的活性，所以相較於其他的血栓溶解劑， 像是 streptokinase 以及 urokinase，臨床上利用 Lumbrokinase 進行血栓溶解比較不會 有出血的危險。臨床上， Lumbrokinase 在於穩定心絞痛的病患已經被用於改善心肌 的灌流。在我們的預試驗中，我們利用左冠狀動脈結紮一小時而後再灌注三小時研 究 Lumbrokinase 在 大 鼠 心 肌 缺 血 再 灌 注 傷 害 的 心 臟 保 護 作 用 ， 研 究 發 現 Lumbrokinase 是一個很有潛力的心臟保護劑可以減少心肌梗塞的體積，此外， Lumbrokinase 可以減少心肌缺血再灌注傷害所引起的 TLR4, COX-2 以及 iNOS 蛋白 質表現增加，相反的，Lumbrokinase 會增加心肌缺血再灌注傷害後梗塞區域 Sirt1 蛋白質的表現。 在本計劃中第一年，我們將大白鼠冠狀動脈結紮造成心肌缺血一小時後再灌 注三小時引發心肌梗塞，評估 Lumbrokinase 對抗心律不整以及心肌梗塞的心臟保護 作用，此外，我們還會評估實驗中血液氣體分壓，存活率，同時評估心肌缺血再灌 注傷害後血漿中細胞損傷因子 creatinine kinase 以及 lactate dehydrogenase 的活性以 及血漿中一氧化氮的濃度，計畫中第二年，我們將研究 TLRs 訊息傳遞路徑在 Lumbrokinase 對抗心肌缺血再灌注傷害的心臟保護作用中所扮演的角色，計畫中第 三年，我們將研究 Sirt1 訊息傳遞路徑在 Lumbrokinase 對抗心肌缺血再灌注傷害的 心臟保護作用中所扮演的角色，並評估 Lumbrokinase在心肌缺血再灌注傷害，是否 會減少氧化壓力，細胞凋亡，以及維持心肌粒線體的功能，我們研究的結果可以提 供有價值的機轉，了解 Lumbrokinase 抗發炎作用在對抗心肌缺血再灌注傷害的心臟 保護作用中的作用機制，此研究提供一個模式可以篩選保護心臟對抗心肌缺血再灌 注傷害的藥物。
Myocardial ischemia-reperfusion (I-R) injury is one of the world's fastest growing disease with is a major contributor to the morbidity and mortality associated with coronary artery disease. Myocardial I-R injury is characterized by a rapid increase in cytokines and chemokines and an influx of leukocytes into the vulnerable region bordering the infarction. This inflammatory response not only results in myocardial apoptosis but also compromises myocardial function. Therefore, limiting myocardial I-R induced myocardial inflammation may not only lower mortality, but also reduce myocardial I-R induced ventricular arrhythmia and myocardial infarction. Lumbrokinase, an extract of lumbricus rubellus, is a group of bioactive proteolytic enzymes include plasminogen activator and plasmin which is identified in recently years. The enzyme in lumbrokinase can only demonstrate thrombolytic activity in the presence of fibrin; therefore, lumbrokinase has the advantage of not causing hemorrhage owing to hyperfibrinolysis during treatment, in contrast with either streptokinase or urokinase. In clinical, lumbrokinase has been used to improve myocardial perfusion in patient with stable angina. In our preliminary studies, we ligated left coronary artery 1 hour following 3 hours reperfusion to investigate the cardioprotective effects of lumbrokinase in the rats under myocardial I-R injury. We found that lumbrokinase reduce myocardial infarction is a potent cardioprotective agent in myocardial I-R injury rats. In addition, we found that lumbrokinase significantly suppressed the myocardial I-R induced TLR4, COX-2, and iNOS expression increase in the occluded zone. In contrast, treatment with lumbrokinase increased the Sirt1 expression. In this project, we will evaluate the cardioprotective effect of lumbrokinase on myocardial arrhythmia and myocardial infarction on rats subjected to 1 hr ischemia and 3 hours reperfusion in the first year. In addition, we will monitor blood gas, survival rate and plasma lactate dehydrogenase, creatinine kinase and nitric oxide concentration in rats subjected to myocardial I-R injury. In the second year, we will investigate the role of TLRs signaling in mediating the protective mechanisms of lumbrokinase. In the third year, we will examine the role of Sirt1 signaling on the cardioprotective effect of lumbrokinase on rats subjected to myocardial I-R injury. We also test whether lumbrokinase will reduce oxidative stress, apoptosis, and maintain mitochondrial function in myocardium in rats under myocardial I-R injury. Our results in the present study will provide valuable contribution to understand the anti-inflammatory mechanism of lumbrokinase on rats subjected to myocardial I-R injury. This study provided a model to screen more new compounds for treatment patients with myocardial I-R injury. |
