Development of cell free messenger RNA-based non-invasive diagnostic biomarker for Alzheimer's Disease

阿尔茨海默氏病（AD）是痴呆症的最常见原因，影响超过4000万人， 预计到2050年将增长三倍虽然验尸是确定AD的金标准 病理学、脑脊液（CSF）中淀粉样蛋白β（A β）和tau水平的评估和/或正电子发射 断层摄影（PET）目前被广泛用作替代物。然而，成像方式是昂贵的，并且CSF 手术是侵入性的。因此，需要高度可及且成本有效的非侵入性诊断方法。 AD和轻度认知障碍（MCI）患者最终将发展为AD。过去两 几十年来，循环核酸已经成为多种疾病中液体活检的可行来源。最近 使用死后人脑组织样本进行的全转录组表征研究 表明AD患者的转录谱与健康个体显著不同。因此，我们认为， 循环信使RNA（mRNA）似乎是AD的有希望的非侵入性诊断生物标志物来源。 尽管无细胞mRNA（cf-mRNA）的定量曾经被认为是具有挑战性的，因为它们的低表达性。 在循环中的丰度，我们和其他人已经开发了一个强大的下一代测序（NGS）的基础上， 用于准确定量cf-mRNA的平台。随后，我们进行了初步的cf-mRNA 多种疾病的分析研究，包括神经退行性疾病、肝病和癌症， 证明了其作为开发用于诊断和监测的非侵入性生物标志物的平台的实用性。 疾病特别是，我们最近分析了126名AD受试者的血浆cf-mRNA转录组， 与115名年龄匹配的对照组相比。我们发现有相当数量的基因 AD患者血浆中的基因表达异常，其中一些基因与认知功能障碍的严重程度相关 在AD科目中。这些AD相关失调的cf-mRNA转录物能够有力地鉴定AD 受试者，并证明了cf-mRNA作为非侵入性生物标志物开发来源的潜力。在 在这项提议中，我们将首先优化和建立临床级方案，以最大限度地减少 下游cf-mRNA Seq分析。然后，我们将分析特征明确的AD患者的cf-mRNA转录组， 和MCI受试者样本以及其他神经系统疾病，并建立诊断和预后分类器 用于AD和MCI，使用全面的生物信息学方法。我们将随后验证性能 这些分类器在预期使用的临床确认队列中。

Alzheimer’s disease (AD) is the most common cause of dementia, affecting over 40 million people and is projected to triple by 2050. Although post-mortem examination is the gold standard for establishing AD pathology, assessment of amyloid β (Aβ) and tau levels in cerebrospinal fluid (CSF) and/or positron-emission tomography (PET) are currently used widely as surrogates. However, imaging modalities are costly and CSF procedure is invasive. Therefore, there is a need for highly accessible and cost-effective non-invasive diagnostic tests for AD and patients with mild cognitive impairment (MCI) who will eventually develop AD. Over the last two decades, circulating nucleic acids have emerged as a viable source of liquid biopsy in multiple diseases. Recent whole-transcriptome characterization studies using post-mortem human brain tissue samples have demonstrated that the transcriptional profile of AD patients differ significantly from healthy individuals. Therefore, circulating messenger RNA (mRNA) appear to be a promising non-invasive diagnostic biomarker source for AD. Although quantification of cell-free mRNAs (cf-mRNAs) was once considered challenging due to their low abundance in the circulation, we and others have developed a robust next generation sequencing (NGS) based platform for accurate quantification of cf-mRNA. Subsequently, we have conducted preliminary cf-mRNA profiling studies in multiple diseases including neurodegenerative diseases, liver diseases and cancers and demonstrated its utility as a platform to develop non-invasive biomarkers for diagnosis and monitoring of diseases. In particular, we have recently profiled plasma cf-mRNA transcriptomes of 126 AD subjects and compared to those of 115 age matched controls. We discovered that a substantial number of genes were dysregulated in plasma of AD subjects and some of these genes correlated with severity of cognitive impairment in AD subjects. These AD associated dysregulated cf-mRNA transcripts were able to robustly identify AD subjects and demonstrated the potential of cf-mRNA as a source for non-invasive biomarker development. In this proposal, we will first optimize and establish clinical-grade protocols to minimize potential variabilities for the downstream cf-mRNA Seq profiling. We will then profile the cf-mRNA transcriptome of well-characterized AD and MCI subject samples as well as other neurological diseases and build diagnostic and prognostic classifiers for AD and MCI using comprehensive bioinformatic approaches. We will subsequently validate the performance of these classifiers in intended-use clinical validation cohorts.