血管內皮細胞的活化在動脈粥狀硬化的生成與血管斑塊的穩定度有舉足輕重的影響。最近的臨床報告指出利用抗血管新生素有效的劑量可以有效的抑制動脈粥狀硬化血管創傷中的斑塊形成與前期發炎反應。在人類血纖維蛋白溶酶原中已經被發現有五個相似的片段。根據我們之前的研究，利用突變的方式在含有人類血纖維蛋白溶酶原五個片段上除去兩個糖化位置與增強在第五個片段上的離氨基酸吸附能力可以有效的增強人類血纖維蛋白溶酶原片段抑制血管新生的能力。我們計畫使用自發性動脈硬化缺陷小鼠與頸動脈結紮手術以探討人類血纖維蛋白溶酶原片段對於動脈粥狀硬化的功能。在自發性動脈硬化缺陷小鼠實驗中，我們發現，小鼠接受四星期的持續性皮下注射人類血纖維蛋白溶酶原片段或突變後的人類血纖維蛋白溶酶原片段可以有效的抑制小鼠主動脈血管斑塊的形成。同時在頸動脈結紮手術實驗中也發現這些人類血纖維蛋白溶酶原片段可以有效的抑制血管栓塞。為了進一步研究我們在動物實驗上觀察到的結果，我們利用腫瘤壞死因子刺激人類臍帶內皮細胞使其表現出細胞間粘附分子-1與血管黏著分子-1，模擬出動脈粥狀硬化的前期發炎反應。並使用前處理的方式處理人類血纖維蛋白溶酶原片段，結果發現人類血纖維蛋白溶酶原片段可以抑制前期發炎反應中的細胞間粘附分子-1與血管黏著分子-1的表現。且經由突變後的人類血纖維蛋白溶酶原片段具有較好的效果。由動物實驗結果和細胞實驗結果指出，人類血纖維蛋白溶酶原片段可能藉由抑制動脈硬化前期發炎反應中細胞間粘附分子-1與血管黏著分子-1的表現，進而降低小鼠體內動脈粥狀硬化的程度。並且這些突變或許可為人類血纖維蛋白溶酶原片段在動脈粥狀硬化上的利用開啟新的方向。

　　Activation of vascular endothelial cells (ECs) plays an important role in atherogenesis and plaque instability. Recent clinical report indicated that potential treatment of angiostatin (kringle 1-4) could reduce the plaque formation and proinflammatory effect in atherosclerotic lesions. Kringle 1-5 (K1-5) is consisted of the first five kringle domains of plasminogen. According to our previous study, the mutation had been created at the potential glycosylation sites and the Lys binding site at kringle 5, which was denominated as K1-5N289A/T346A/L532R. The K1-5N289A/T346A/L532R was demonstrated to be more potent than angiostatin in inhibition of angiogenesis and atherosclerosis. We used the apolipoprotein E (ApoE) deficient mice model and the ligation model to test the function of kringle protein in atherogenesis. In apoE deficient mice that received K1-5 or K1-5N289A/T346A/L532R injection for 4 weeks, and the lesion area in aorta was notably decreased. In the ligation model, the left common carotid arteries of C57BL/6 mice were ligated near the carotid bifurcation and then injected with K1-5 or K1-5N289A/T346A/L532R for 4 weeks. The carotid neointima formation in the C57BL/6 mice was decreased by treatment of K1-5N289A/T346A/L532R. We designed to treat K1-5 or K1-5N289A/T346A/L532R on HUVECs for 30 minutes before treatment of TNF-alpha for 24 hours to explore the mechanism in vitro. The results showed that K1-5N289A/T346A/L532R was more potent than K1-5 in reducing the intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) expression. Based on these observations, K15 and K1-5N289A/T346A/L532R might inhibit the proinflammatory effect and plaque formation in vivo through inhibition of ICAM-1, VCAM-1 expression in ECs, and we found that K1-5N289A/T346A/L532R had more effect than K1-5 in inhibiting proinflammation of atherogenesis. In the future, we will investigate the mechanism of how K1-5 and K1-5N289A/T346A/L532R inhibit the expression of ICAM-1 and VCAM-1 in ECs. The increase of Lys binding ability and the altered glycosylation sites of mutant K1-5 proteins may provide a new strategy in improving the anti-atherosclerotic function of K1-5.

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