過氧化體增生活化受體 β/δ 及視黃醇 X 受體 α 基因多形性與缺血性中風之相關性研究

腦血管疾病為台灣民國100年十大死因的第三位，而缺血性中風為主要的中風類型，約占70％。動脈粥狀硬化為缺血性中風重要危險因子，不僅會造成血管內壁狹窄，其粥狀硬化的斑塊可能脫落形成血栓（thrombosis）而阻塞腦部血流的通過，使得氧氣與養分無法通過，造成受損腦組織缺氧性壞死。過氧化體增生活化受體β/δ（peroxisome proliferator-activated receptor β/δ, PPARβ/δ）於動脈粥狀硬化形成過程中扮演關鍵的角色，包括調節脂質代謝、內皮細胞損傷、巨噬細胞凋亡和發炎反應等過程。另外，視黃醇x受體α（retinoid X receptor α, RXRα）負責調控血管內皮細胞的細胞增生與發炎反應，因此在動脈粥狀硬化形成過程中，RXRα亦是影響的因素之一。故本研究目的即為探討PPARβ/δ、RXRα基因多形性以及傳統危險因子對缺血性中風的獨立與交互作用。本研究採病例對照研究方法，研究對象包括1215位缺血性中風患者與1215位經年齡、性別配對的健康對照組。1215名缺血性中風患者由奇美、羅東博愛、萬芳、新光、亞東、台大和北醫七家醫院所招募。而健康對照組由新光、萬芳及北醫社區健檢民眾所招募。資料收集為利用結構式問卷，經標準化流程收集其基本人口學、相關危險因子與疾病史等資料，並利用禁食八小時靜脈血，測量相關血液生化值資料。使用聚合酶連鎖反應－限制酶片段長度多形性（polymerase chain reaction-restriction fragment length polymorphism, PCR-RFLP）與對照兩組引子的聚合酶連鎖反應（polymerase chain reaction with confronting two-pair primers, PCR-CTPP）鑑定其基因多形性。使用邏輯斯迴歸模式分析PPARβ/δ、RXRα基因多形性與缺血性中風的關係。 PPARβ/δ和RXRα基因多形性與缺血性中風罹患風險未達統計上顯著水準。PPARβ/δ基因進行單套型分析（rs2016520、rs2076167和rs9794）結果顯示，調整傳統危險因子之後，相較於野生型TAC（H1）而言，攜帶TAG（H2）和CGC（H7）者會增加缺血性中風的罹患風險，其風險對比值分別為2.99和1.68。在對照組基因多形性與生化值分析中，顯示PPARβ/δ基因多形性隨著攜帶變異對偶基因增加有較高的低密度脂蛋白表現量。進一步分析PPARβ/δ和RXRα基因多形性與傳統危險因子對於罹患缺血性中風的交互作用情形，雖基因多形性與傳統危險因子之間沒有顯著的交互作用，但基因多形性對於疾病罹患風險仍有部分修飾作用，而PPARβ/δ單套型與高血壓對於罹患缺血性中風的風險性存在加成協同交互作用關係。總結以上，本篇研究發現PPARβ/δ單套型與缺血性中風的風險有相關性，且PPARβ/δ單套型與高血壓對於缺血性中風罹患風險存在加成協同交互作用。

關鍵字

過氧化體增生活化受體β/δ、視黃醇X受體α基因、缺血性中風、基因多形性

並列摘要

Cerebrovascular diseases are the third leading cause of death in Taiwan in 2011. Ischemic stroke is the major subtype of stroke, which accounts for about 70% of the stroke cases. Atherosclerosis is the most important risk factor of ischemic stroke. The atherosclerotic plaques which may fall to thrombosis .Thrombosis can be caused by disorders in blood vessels, blood coagulation, and blood flow. The blocking of blood flow through the brain, resulting in hypoxia necrosis. PPARβ/δ is a critical role for atherosclerosis processes. PPARβ/δ was demonstrated to involve in lipid metabolism, endothelia dysfunction, macrophage apoptosis, and inflammation. In addition, RXRα regulated vascular endothelial cell proliferation and inflammation, and therefore processed formation of atherosclerosis. Hence, we investigated the relationship between gene polymorphisms of PPARβ/δ, RXRα and the risk of developing ischemic stroke. 1215 ischemic stroke patients and 1215 controls were recruited in this study. 1215 ischemic patients were recruited from the department of neurology of Chi-Mei, Lotung Poh-Ai, Wan-Fang, Shin-Kong WHS Memories, Far Eastern Memories National Taiwan University and Taipei Medical University hospitals in Taiwan. 1215 Stroke-free subjects from the regular health examination in Shin-Kong WHS Memories, Wan-Fang and Taipei Medical University hospitals in Taipei were classified as controls. Cases and controls were frequency matched by age and sex. We genotyped three SNPs of PPARβ/δ（rs2016520、rs2076167 and rs9794） and two SNPs of RXRα （ rs11185660 and rs4240711 ） using polymerase chain reaction-restriction fragment length polymorphism（PCR-RFLP） and polymerase chain reaction with confronting two-pair primers（PCR-CTPP） method. We collected conventional vascular risk factors and disease history from all subjects by well-trained research assistants using a structured questionnaire. Fasting glucose, lipid profile, and uric acid were from routine biochemistry tests. Logistic regression model was used to estimate the odds ratio（OR） and 95% confidence interval（CI). Study result showed that PPARβ/δ and RXRα polymorphisms have no significant association with ischemic stroke. A significantly increased risk of ischemic stroke was found in subjects with the TAG and CGC haplotype（rs2016520, rs2076167, rs2076167）of PPARβ/δ, the OR（95%CI） were 2.99（1.23-2.27）and 1.68（1.01-2.81）, respectively. PPARβ/δ polymorphisms was associated with an increased plasma low-density lipoprotein cholesterol（LDL-C） concentration in health subjects and the same effect on PPARβ/δ haplotype were also found. We found that genetic polymorphisms of study genes and traditional risk factors had no significant interaction on the risk of ischemic stroke. However, genetic effects still showed some modification on risk of stroke. Moreover, the significant joint effect between PPARβ/δ haplotype and hypertension on the risk of ischemic stroke was found. In conclusion, our results showed that special type of PPARβ/δ haplotype had significantly increased risk of stroke. There was a synergistic effect between PPARβ/δ haplotype and hypertension on the risk of ischemic stroke.