Plasma lipoproteome in Alzheimer's disease: a proof-of-concept study
Plasma lipoproteome in Alzheimer's disease: a proof-of-concept study
复制标题
DOI：
10.1186/s12014-018-9207-z
复制
发表时间：
2018-09-20
影响因子：
3.8
通讯作者：
Yu, Fang
中科院分区：
文献类型：
--
作者：
Li, Danni;Huang, Fangying;Yu, Fang
背景：尽管血浆总脂蛋白组成的蛋白质被认为是可以识别阿尔茨海默病(AD)的生物标志物，但影响的大小并不大。这项研究的目的是提供初步的概念证明，当测量单个血浆脂蛋白部分时，AD患者和对照组之间的血浆脂蛋白组更有可能不同，而不是在免疫耗竭的血浆中作为总的测量。方法：我们首先建立了一种基于选择性反应监测(SRM)和液相色谱-串联质谱仪的靶向蛋白质组学方法，用于测量血浆脂蛋白中常见的79种蛋白质中的120种胰蛋白酶解肽。然后，在对5例AD患者和5例性别和年龄匹配的对照进行的概念验证病例对照研究中，我们应用靶向蛋白质组学方法，对血浆脂蛋白组分(序贯梯度超速离心法分离)和免疫耗竭血浆(白蛋白和免疫球蛋白G)中的120个胰蛋白酶多肽进行了相对定量。两个样本t检验和总折叠变化的未调整p值被用来评估AD患者和对照组之间的肽相对差异，较低的p值(1.05或<；0.95)暗示更大的肽/蛋白质差异。结果：目标蛋白质组学方法的日内和日间技术精密度(所有SRM转变的平均%CV[SD])分别为3.95%(2.65)和9.31%(5.59)。包括血浆脂蛋白分级在内的整个血浆脂蛋白工作流程的日间技术精密度(平均%CV[SD])为27.90%(14.61)。血浆脂蛋白中属于5种蛋白质的10个胰蛋白酶多肽，与免疫耗竭的血浆中没有的多肽相比，具有未调整的p值&0.05。此外，在极低密度脂蛋白、低密度脂蛋白、低密度脂蛋白和高密度脂蛋白中，有27、32、17和20个胰多肽显示出总的肽折叠差异>；1.05或<；0.95，而在免疫耗竭的血浆中只有6个胰多肽。因此，总体比较表明，当在单个血浆脂蛋白中测量时，血浆脂蛋白质组中的肽/蛋白质差异比在免疫耗竭血浆中作为整体测量时更大。特别地，补体C3‘S多肽IHWESASLLRIHWESASLLRIHWESASLLRIHWESASLLRIHWESASLLRIHWESASLLRIHWESASLLRIHWESASLLRIHWESASLLRIHWESASLLRIHWESASLLRIHWESASLLRIHWESASLLR，其p值分别为0.00007、0.00012和0.0006，极低密度脂蛋白、低密度脂蛋白和低密度脂蛋白的变化分别为1.25、1.17和1.14倍。经阳性假发现率(PFDR)调整后，VLDL的补体C3多肽IHWESASLLR仍有统计学意义(调整后的p值
Background: Although total plasma lipoproteome consists of proteins that have shown promises as biomarkers that can identify Alzheimer's disease (AD), effect sizes are modest. The objective of this study is to provide initial proof-of-concept that the plasma lipoproteome more likely differ between AD cases and controls when measured in individual plasma lipoprotein fractions than when measured as total in immunodepleted plasma.Methods: We first developed a targeted proteomics method based on selected reaction monitoring (SRM) and liquid chromatography and tandem mass spectrometry for measurement of 120 tryptic peptides from 79 proteins that are commonly present in plasma lipoproteins. Then in a proof-of concept case-control study of 5 AD cases and 5 sex- and age-matched controls, we applied the targeted proteomic method and performed relatively quantification of 120 tryptic peptides in plasma lipoprotein fractions (fractionated by sequential gradient ultracentrifugation) and in immunodepleted plasma (of albumin and IgG). Unadjusted p values from two-sample t-tests and overall fold change was used to evaluate a peptide relative difference between AD cases and controls, with lower p values ( 1.05 or < 0.95) suggestive of greater peptide/protein differences.Results: Within-day and between-days technical precisions (mean %CV [SD] of all SRM transitions) of the targeted proteomic method were 3.95% (2.65) and 9.31% (5.59), respectively. Between-days technical precisions (mean % CV [SD]) of the entire plasma lipoproteomic workflow including plasma lipoprotein fractionation was 27.90% (14.61). Ten tryptic peptides that belonged to 5 proteins in plasma lipoproteins had unadjusted p values< 0.05, compared to no peptides in immunodepleted plasma. Furthermore, 27, 32, 17, and 20 tryptic peptides in VLDL, IDL, LDL and HDL, demonstrated overall peptide fold differences > 1.05 or < 0.95, compared to only 6 tryptic peptides in immunodepleted plasma. The overall comparisons, therefore, suggested greater peptide/protein differences in plasma lipoproteome when measured in individual plasma lipoproteins than as total in immunodepleted plasma. Specifically, protein complement C3's peptide IHWESASLLR, had unadjusted p values of 0.00007, 0.00012, and 0.0006 and overall 1.25, 1.17, 1.14-fold changes in VLDL, IDL, and LDL, respectively. After positive False Discovery Rate (pFDR) adjustment, the complement C3 peptide IHWESASLLR in VLDL remained statistically different (adjusted p value