針對動脈粥狀硬化性疾病之功能性分子感測成像及活體藥物篩選

Abstract

動脈粥狀硬化性心血管疾病 (atherosclerotic cardiovascular disease) 為已開發國家人民死亡的主因之一。其致命的原因在於血管壁內的不穩定性斑塊 (vulnerable plaque) 破裂後所引起的急性血栓 (acute thrombosis) 所造成的缺血性中風 (ischemic stroke) 及心肌梗塞 (myocardial infarction)。動脈粥狀硬化之致病過程開始于低密度脂蛋白 (low-density lipoprotein, LDL) 堆積于血管內壁，以及其受活性氧化物質 (reactive oxygen species) 氧化修飾為氧化之低密度脂蛋白 (oxidatively modified LDL)．氧化之低密度脂蛋白為動脈粥狀硬化斑塊發炎的主要刺激源，而斑塊的發炎程度則影響到斑塊的穩定程度或易破裂的程度。因此，精確評估血管壁上之低密度脂蛋白堆積、氧化修飾以及斑塊發炎程度，不但有助於心血管疾病之臨床診斷，也對相關藥物的開發有相當助益。基於上述工作於醫藥發展上之重要性，學生在博士期間的工作主要在開發針對動脈粥狀硬化之分子探針及光譜及影像檢測方法．完成的具體工作包含 (1) 開發一個可針對活性氧化物進行”絕對定量”之螢光分子探針；(2) 建立一個評估動脈粥狀硬化斑塊發炎程度的螢光分子影像檢測法；(3) 建立一個於活體斑馬魚以螢光成像與拉曼光譜技術進行動脈粥狀硬化藥物篩選的平台。我的工作突破了以往的研究限制並首次展現 (1) 對細胞內外之活性氧化物分泌進行濃度絕對定量；(2) 於活體動物(斑馬魚)內探討動脈粥狀硬化斑塊的發炎程度；(3) 於活體斑馬魚血管原位評估低密度脂蛋白堆積及氧化修飾，並將此方法應用於藥物篩選。學生期待以上方法及技術能對往後動脈粥狀硬化的基礎研究有所助益，並協助相關藥物之開發以及臨床診斷。

Atherosclerotic cardiovascular disease is a leading cause of death. Sudden rupture of a vulnerable atherosclerotic plaque triggers thrombosis and causes a deadly event such as ischemic stroke or myocardial infarction. Pathogenesis of atherosclerosis includes an accumulation of low-density lipoprotein (LDL) in the vascular wall and its oxidative modification by endogenous reactive oxygen species (ROS). Vascular inflammation induced by the accumulation of oxidatively modified LDL (oxLDL) plays a key role in the vulnerability of atherosclerotic plaque and increases the risk of cardiovascular thrombotic events. As a result, the development of methods for the assessment of such symptoms (i.e., vascular accumulation of LDL and its oxidative modification, and plaque inflammation) is important for the clinical diagnosis, and for the evaluation of the therapeutic efficacy of medications, targeting atherosclerosis. Toward this end, my PhD work focuses on the development of: (1) A quantum dots based molecular probe for the real-time and absolute quantifying ROS in vivo; (2) Fluorescence molecular imaging for the evaluation of plaque inflammation; (3) A platform (comprising confocal fluorescence imaging, Raman spectral analysis, and hypercholesterolemic zebrafish) for the direct assessment of vascular LDL deposition and oxidation in vivo and in situ, and its application for drug screening. Facilitated with these unique approaches, I demonstrated for the first time (1) Absolute quantification of endogenous HOCl in leukocyte; (2) Evaluation of the inflammation of individual atherosclerotic plaques in zebrafish in vivo; (3) Evaluation of the therapeutic activity of anti-atherosclerotic drugs (Atorvastatin and Ezetimibe) on individual plaques in zebrafish in vivo. I envisage that my approach will not only improve our understanding of atherogenesis but also expedite the screening of drugs and clinical diagnosis targeting atherosclerosis.