阿尔茨海默病脑内β淀粉样蛋白沉淀与胆固醇和载脂蛋白E基因启动子多态性的相关性

Relationship of cholesterol and apolipoprotein E promoter-491 A/T polymorphisms to beta-amyloid deposition in Alzheimer disease

目的:观察胆固醇与载脂蛋白E基因启动子多态性,分析其与阿尔茨海默病患者神经元内β-淀粉状蛋白质沉积的关系。方法:同时选择2000-01/2005-12美国南卡罗莱纳州立大学科学中心阿尔茨海默病尸检患者132例作为病例组,非阿尔茨海默病尸检患者132例作为对照组。病例组存在β-淀粉状蛋白质沉积(+),对照组不存在β-淀粉状蛋白质沉积(-)。血浆胆固醇含量为临床病例记录。从阿尔茨海默病病例组及匹配对照组患者尸检肝脏石蜡块中提纯Genomic DNA。采用DNA聚合酶链反应(PCR)扩增载脂蛋白E基因启动子,限制性核酸内切酶酶切消化PCR产物并电泳测定酶切结果。匹配临床记录血浆胆固醇含量指标进行统计分析。结果:两组数据患者全部进入结果。①第1轮DNA聚合酶链反应及电泳结果发现载脂蛋白E基因启动子PCR产物存在包括目的(1274bp)在内的多个条带。第2轮DNA聚合酶链反应及电泳结果发现只存在目的带(228bp)一个条带。②全部病例组和对照组载脂蛋白E基因启动子427基因型均为TT。病例组载脂蛋白E基因启动子491多态性位点基因型AA表达明显多于对照组(107,66例,P<0.01),对照组基因型AT及TT明显多于病例组,差异有显著性意义(54,20例;12,5例;P<0.01),基因型AA患者β-淀粉状蛋白在脑内沉积机会增加。③病例组血浆胆固醇含量与对照组之间差异有显著性意义[(6.05±0.17),(5.21±0.15)mmol/L,P<0.05],高血浆胆固醇含量增加β-淀粉状蛋白在脑内沉积。结论:血浆胆固醇水平与载脂蛋白E基因启动子491多态性位点与阿尔茨海默病患者神经元内β-淀粉状蛋白质沉积相关。

AIM： To observe the cholesterol levels and brain apolipoprotein E （APOE） promoter polymorphisms, and explore their relationship with β-amyloid deposition in patients with Alzheimer disease （AD）. METHODS： 132 autopsided patients with Alzheimer disease were selected from Carolina State University as case group and 132 autopsied patients with no Alzheimer disease were also selected as control between January 2000 and December 2005. β-amyloid deposition was only found in the control group. Plasma cholesterol levels ware from the clinical records. Genomic DNA was extracted from the paraffin liver block of the case and matched control samples. APOE promoter was amplified with PCR, and the products were digested with restriction enzyme, and identified by electrophoresis. RESULTS： All patients ware involved in the result analysis. （1）The first cycle DNA PCR and electrophoresis results showed that many bands including the target band of 1 274 bp ware found in the PCR products of APOE promoter, while in the second cycle, only the target band of 228 bp was found. （2）APOE promoter-427 genotype of both groups was TT. The expression of genotype AA at the apolipoprotein E gene-491 polymorphism locus in the case group was significantly more than that of the control group （107, 66 cases, P〈 0.01）, and that of genotypes AT and TT in the control group was more than that of the case group significantly （54, 20 cases; 12, 5 cases; P〈 0.01）; 13-amyloid deposition would be increased in genotype AA patients. （3）There ware significant differences in the plasma cholesterol level between the case group and control group [（6.05＋0.17）, （5.21 ＋0.15） mmol/L, P 〈 0.05], and high cholesterol level may promote brain β-amyloid deposition. CONCLUSION： Plasma cholesterol level and APOE promoter-491 polymorphisms are associated with brain β-amyloid deposition in patients with Alzheimer disease.