Table_2_High-Throughput Metabolomics for Discovering Potential Biomarkers and Identifying Metabolic Mechanisms in Aging and Alzheimer’s Disease.DOCX

Alzheimer’s disease (AD) is an aging-related neurodegenerative disease. We aimed to investigate the metabolic mechanisms of aging and AD and to identify potential biomarkers for the early screening of AD in a natural aging population. To analyze the plasma metabolites related to aging, we conducted an untargeted metabolomics analysis using ultra-high-performance liquid chromatography/quadrupole time-of-flight mass spectrometry in a two-stage cross-sectional study. Spearman’s correlation analysis and random forest were applied to model the relationship between age and each metabolite. Moreover, a systematic review of metabolomics studies of AD in the PubMed, Cochrane and Embase databases were searched to extract the differential metabolites and altered pathways from original studies. Pathway enrichment analysis was conducted using Mummichog. In total, 669 metabolites were significantly altered with aging, and 12 pathways were enriched and correlated with aging. Three pathways (purine metabolism, arginine and proline metabolism, and the TCA cycle) were shared between aging and AD. Arginine and proline metabolism play a key role in the progression from healthy to mild cognitive impairment and to AD in the natural aging population. Three metabolites, 16-a-hydroxypregnenolone, stearic acid and PC[16:0/22:5(4Z,7Z,10Z,13Z,16Z)] were finally proposed as potential markers of AD in the natural aging population. The underlying mechanism shared between aging and AD and the potential biomarkers for AD diagnosis were proposed based on multistep comparative analysis.

阿尔茨海默病（AD）是一种与衰老相关的神经退行性疾病。本研究旨在探究衰老与阿尔茨海默病的代谢机制，并在自然衰老人群中筛选可用于阿尔茨海默病早期筛查的潜在生物标志物。为分析与衰老相关的血浆代谢物，本研究采用两阶段横断面研究设计，通过超高效液相色谱-四极杆飞行时间质谱（ultra-high-performance liquid chromatography/quadrupole time-of-flight mass spectrometry）开展非靶向代谢组学（untargeted metabolomics）分析。采用斯皮尔曼相关分析（Spearman’s correlation analysis）与随机森林（random forest）模型，构建年龄与各代谢物之间的关联。此外，本研究对PubMed、Cochrane及Embase数据库中收录的阿尔茨海默病代谢组学研究进行系统综述（systematic review），从原始研究中提取差异代谢物与异常通路。采用Mummichog进行通路富集分析（pathway enrichment analysis）。总计有669种代谢物随衰老发生显著变化，另有12条通路发生富集且与衰老相关。衰老与阿尔茨海默病共享3条通路：嘌呤代谢（purine metabolism）、精氨酸与脯氨酸代谢（arginine and proline metabolism）以及三羧酸循环（TCA cycle）。精氨酸与脯氨酸代谢在自然衰老人群从健康状态进展为轻度认知障碍（mild cognitive impairment），最终发展为阿尔茨海默病的过程中发挥关键作用。最终筛选出16-α-羟基孕烯醇酮（16-a-hydroxypregnenolone）、硬脂酸（stearic acid）以及PC[16:0/22:5(4Z,7Z,10Z,13Z,16Z)]这3种代谢物，作为自然衰老人群中阿尔茨海默病的潜在生物标志物。本研究通过多步比较分析，揭示了衰老与阿尔茨海默病共有的潜在机制，并提出了用于阿尔茨海默病诊断的潜在生物标志物。