血管附著蛋白1在代謝與動脈硬化疾病的角色

The Role of Vascular Adhesion Protein-1 in Metabolic and Atherosclerotic Diseases

李弘元(Hung-Yuan Li)

指導教授 ： 莊立民 ； 江福田

國立臺灣大學/醫學院/臨床醫學研究所/博士(2010年)

https://doi.org/10.6342/NTU.2010.10022

摘要

目前對於代謝疾病導致動脈硬化的成因與發生，了解仍然有限。初步研究顯示，血管附著蛋白1(vascular adhesion protein-1)會參與發炎反應，也會透過其semicarbazide-sensitive amine oxidase (SSAO)酵素活性催化氧化壓力與advanced glycation end products (AGEs)的產生，而可能參與動脈硬化形成過程。本研究探討血中血管附著蛋白1，是否可以做為代謝與動脈硬化疾病的生物標記，並研究血管附著蛋白1參與發炎與動脈硬化的部分機轉。
利用横斷面的研究設計(656人)，我們發現人類血中血管附著蛋白1與年紀成正相關，女性血中濃度比男性高。我們也發現糖尿病人血中血管附著蛋白1較高，其濃度與糖化血色素以及空腹血糖成正相關，並且在口服葡萄糖水後半小時升高。此外，有慢性腎臟病的人血中血管附著蛋白1也較高，其濃度與白蛋白尿的濃度成正相關，與腎絲球過濾率成負相關。也就是說，年紀大，高血糖以及白蛋白尿這些動脈硬化的危險因子，都與血中血管附著蛋白1濃度有正相關。進一步研究發現，口服葡萄糖水後，血中血管附著蛋白1濃度的變化，與血中氧化壓力與AGEs呈顯著相關，並與頸動脈內膜與中層厚度成正相關，這部分的研究暗示，血糖可能透過改變血中血管附著蛋白1的濃度，進一步增加血中氧化壓力與AGEs，導致動脈硬化的形成。
於是我們在一個第2型糖尿病人的世代中，檢驗血中血管附著蛋白1的預測能力(661人)。我們發現，血中血管附著蛋白1可以預測這些糖尿病人10年的心血管疾病死亡率、癌症死亡率以及全死亡率；血中血管附著蛋白1濃度對於全死亡率的預測能力，與年紀、是否吸菸、血中creatinine濃度及是否有蛋白尿相當。
在動脈硬化的形成過程中，單核球與巨嗜細胞扮演很重要的角色，但是目前並不了解單核球與巨嗜細胞是否表現VAP-1。以往的文獻指出，在脂肪細胞有重要生理功能的蛋白，往往也在單核球或是巨嗜細胞表現，並且具有重要功能。我們利用RT-PCR、西方點墨法、流式細胞儀與免疫螢光染色法，研究人類周邊血液單核球、人類THP-1單核球與巨嗜細胞株後發現，人類單核球與巨嗜細胞的確有表現血管附著蛋白1。而在THP-1巨嗜細胞分化過程中，血管附著蛋白1的mRNA與蛋白表現都顯著增加，暗示VAP-1對於巨嗜細胞的成熟或是功能扮演一定的角色。進一步研究顯示，使用SSAO抑制劑semicarbazide與mofegiline可有效抑制單核球附著到fibronectin的能力；當使用PMA誘導單核球分化為巨嗜細胞時，PMA作用1小時後，細胞附著到fibronectin的能力就顯著上升，此時再使用SSAO抑制劑就無法抑制細胞的附著功能了。此外，我們也發現在巨嗜細胞分化過程中，加入SSAO抑制劑並不會改變巨嗜細胞分泌TNF-α的能力。
總而言之，我們的研究發現血中血管附著蛋白1與動脈硬化的危險因子有關，可以預測糖尿病人10年的心血管疾病死亡率、癌症死亡率與全死亡率；我們也發現人類單核球與巨嗜細胞的確有表現血管附著蛋白1，單核球上的血管附著蛋白1在分化過程中表現增加，並且參與單核球的附著功能。

關鍵字

血管附著蛋白1 ； semicarbazide-sensitive amine oxidase ； 糖尿病 ； 動脈硬化 ； 單核球 ； 巨嗜細胞

並列摘要

The understanding of how metabolic abnormality leads to atherosclerosis remains limited. Vascular adhesion protein-1 (VAP-1) has been shown to participate in inflammation, and can catalyze the breakdown of amines through SSAO activity to produce oxidative stress and advanced glycation end products (AGEs). In this study, we explored if serum VAP-1 could be a biomarker for metabolic and atherosclerotic diseases, and investigated part of the mechanism of atherosclerosis which VAP-1 was involved.
In cross-sectional studies including 656 subjects, we found that serum VAP-1 was higher in elderly and in female. Serum VAP-1 was higher in subjects with diabetes and was associated with hemoglobin A1C and fasting glucose levels. In oral glucose challenge test, serum VAP-1 was elevated 30 minutes after glucose ingestion. Besides, serum VAP-1 was higher in subjects with chronic kidney diseases. Serum VAP-1 was positively correlated with albuminuria and was negatively associated with estimated glomerular filtration rate. Taken together, these risk factors for atherosclerosis were correlated with serum VAP-1. We also found a link between serum VAP-1 and carotid intima-medial thickness. The change of serum VAP-1 during oral glucose tolerance test was correlated with systemic oxidative stress, AGEs concentrations, and carotid intima-medial thickness, indicating that hyperglycemia may result in atherosclerosis through its effect on serum VAP-1, oxidative stress and AGEs.
We tested the prediction ability of serum VAP-1 in a cohort of type 2 diabetes (N=661). We found that serum VAP-1 can predict 10-year cardiovascular mortality, cancer-related mortality, and all-cause mortality. The incremental prediction ability of serum VAP-1 was comparable to that of age, smoking, serum creatinine, and proteinuria.
In the literature, proteins which have important physiologic functions in adipocytes are often expressed in monocyte or macrophage and play important physiologic roles. In present study, we demonstrated that monocyte and macrophage do express VAP-1 by RT-PCR, western blot, flow cytometry, and immunofluorocytochemistry on human peripheral blood monocyte, human THP-1 monocyte, and human THP-1 macrophage. In THP-1 macrophage, VAP-1 mRNA and protein expression were up-regulated on differentiation, suggesting a role of VAP-1 in its maturation or function. Inhibition of SSAO activity by semicarbazide or mofegiline can suppress the adhesion of THP-1 monocyte to fibronectin. During differentiation, the adhesion ability significantly increased 1 hour after PMA induction, when SSAO inhibition can no longer suppress adhesion function. Besides, inhibition of SSAO during differentiation can not affect TNF-α secretion by THP-1 macrophage.
In summary, we found that serum VAP-1 was associated with risk factors for atherosclerosis. Serum VAP-1 can predict 10-year cardiovascular, cancer-related, and all-cause mortality. We demonstrated that human monocyte expressed VAP-1, which was up-regulated during differentiation to macrophage, and was involved in its adhesion to fibronectin.

並列關鍵字

vascular adhesion protein-1 ； semicarbazide-sensitive amine oxidase ； diabetes mellitus ； atherosclerosis ； monocyte ； macrophage

參考文獻

32. 魏榮男, 莊立民, 林瑞雄, 趙嘉玲, 宋鴻樟. 1996-2000年台灣地區糖尿病盛行率與住院率. 台灣衛誌 2002; 21:173-180.

1. Rosamond W, Flegal K, Friday G et al. Heart disease and stroke statistics--2007 update: a report from the American Heart Association Statistics Committee and Stroke Statistics Subcommittee. Circulation 2007; 115:e69-171.

2. Yusuf S, Reddy S, Ounpuu S, Anand S. Global burden of cardiovascular diseases: part I: general considerations, the epidemiologic transition, risk factors, and impact of urbanization. Circulation 2001; 104:2746-2753.

3. Fox CS, Evans JC, Larson MG, Kannel WB, Levy D. Temporal trends in coronary heart disease mortality and sudden cardiac death from 1950 to 1999: the Framingham Heart Study. Circulation 2004; 110:522-527.

4. Murray CJ, Lopez AD. Mortality by cause for eight regions of the world: Global Burden of Disease Study. Lancet 1997; 349:1269-1276.