Han Sun-Ho, Kim Jun Seok, Lee Youngju, Choi Heesun, Kim Jong-Won, Na Duk Lyul, Yang Eun Gyeong, Yu Myeong-Hee, Hwang Daehee, Lee Cheolju, Mook-Jung Inhee
Department of Biochemistry and Biomedical Sciences, Seoul National University, College of Medicine, 28 Yungun-dong, Jongro-gu, Seoul 110-799, Korea;
Mol Cell Proteomics. 2014 Feb;13(2):407-19. doi: 10.1074/mcp.M113.028639. Epub 2013 Dec 8.
Apolipoprotein E (ApoE) polymorphism has been appreciated as a valuable predictor of Alzheimer disease (AD), and the associated ε4 allele has been recognized as an indicator of susceptibility to this disease. However, serum ApoE levels have been a controversial issue in AD, due to the great variability regarding the different target detection methods, ethnicity, and the geographic variations of cohorts. The aim of this study was to validate serum ApoE levels in relation to AD, particularly using two distinct detection methods, liquid chromatography-selected reaction monitoring (SRM) mass spectrometry and microsphere-based fluorescence-activated cell sorting (FACS) analysis, to overcome experimental variations. Also, comparison of serum ApoE levels was performed between the level of protein detection by FACS and peptide level by SRM in both control and AD patients. Results from the two detection methods were cross-confirmed and validated. Both methods produced fairly consistent results, showing a significant decrease of serum ApoE levels in AD patients relative to those of a control cohort (43 control versus 45 AD, p < 0.0001). Significant correlation has been revealed between results from FACS and SRM (p < 0.0001) even though lower serum ApoE concentration values were measured in protein by FACS analysis than in peptide-level detections by SRM. Correlation study suggested that a decrease of the serum ApoE level in AD is related to the mini-mental state exam score in both results from different experimental methods, but it failed to show consistent correlation with age, gender, or clinical dementia rating.
载脂蛋白E（ApoE）基因多态性已被视为阿尔茨海默病（AD）的一项重要预测指标，与之相关的ε4等位基因被认为是该疾病易感性的一个指标。然而，由于不同的目标检测方法、种族以及队列研究的地域差异存在很大变异性，血清ApoE水平在AD研究中一直是一个有争议的问题。本研究的目的是验证血清ApoE水平与AD的关系，特别是使用两种不同的检测方法，即液相色谱-选择反应监测（SRM）质谱法和基于微球的荧光激活细胞分选（FACS）分析法，以克服实验变异性。此外，还在对照患者和AD患者中比较了FACS检测的蛋白质水平和SRM检测的肽水平之间的血清ApoE水平。两种检测方法的结果相互交叉确认并得到验证。两种方法得出的结果相当一致，显示AD患者的血清ApoE水平相对于对照队列显著降低（43名对照者与45名AD患者，p < 0.0001）。尽管FACS分析检测的蛋白质中血清ApoE浓度值低于SRM肽水平检测值，但FACS和SRM的结果之间仍显示出显著相关性（p < 0.0001）。相关性研究表明，不同实验方法的结果均显示AD患者血清ApoE水平降低与简易精神状态检查评分有关，但与年龄、性别或临床痴呆评定量表未显示出一致的相关性。
