Unbiased Approaches to Novel Biomarker Discovery in Parkinson's Disease

描述(由申请人提供)：帕金森氏病(PD)和帕金森病内表型的有效、易获得的生物标记物的需求很大。尽管有这种需要，文献中报道的候选标记物很少，迄今为止在帕金森病中描述的最成熟的生化标记物是脑脊液(CSF)标记物，这为广泛使用制造了很大的障碍。直到最近，对帕金森病和许多其他疾病的生物标记的搜索还受到一个事实的限制，即需要一种有针对性的方法--也就是说，除非有先验的理由相信特定的基因/蛋白质将首先提供信息，否则无法找到生物标记。然而，在过去的10年里， 技术的进步使数百名(如果不是数千名)潜在候选人出现了大规模的、无偏见的筛选，这是遗传学/基因组学领域首创的方法上的根本性改变。我们以前曾使用这种无偏见的方法发现并随后复制了血浆表皮生长因子(EGF)水平与帕金森病患者认知障碍之间的新关联，表明低EGF水平可能与帕金森病患者痴呆的发病相关，并可能早于该疾病的发生。与此同时，我们发现低水平的血浆载脂蛋白A1(ApoA1)水平可能预示着多巴胺能系统完整性丧失的风险增加，并发现了五个潜在的血浆生物标志物与帕金森病的下降速度相关。在这里，我们建议建立在这一实践经验的基础上，将我们的发现向前推进到临床翻译的管道中，同时还对450种血浆蛋白进行从头发现筛查，以寻找帕金森病和帕金森病内表型的其他生物标志物。在我们的方法中嵌入了这样一种理解，即无偏见的生物标记物发现方法需要在更多的受试者队列中进行复制，然后通过跨站点复制结果和对生物机制的调查进行验证。因此，我们的目标是：1)验证两个先前复制的基于血浆的帕金森病生物标记物--确定血浆表皮生长因子(EGF)水平是否为帕金森病患者认知能力的生物标记物，以及血浆载脂蛋白A1(ApoA1)水平是否为帕金森病风险的生物标记物，方法是评估它们在独立临床地点的额外患者队列中的表现，并探索它们的生物学方面和临床转译的可能性。2)复制五个新发现的基于血浆的帕金森病下降速度生物标记物--确定Axl受体酪氨酸激酶(Axl)水平是否、在UPenn患者的其他队列中，基质金属蛋白酶-2(MMP-2)、白介素7(IL-7)、表皮生长因子(EGF)和C反应蛋白(CRP)与PD运动功能减退的比率相关，使用替代的测量平台1)和3)使用一种基于蛋白质-DNA-适配子的新技术同时检测450种血浆蛋白，对PD患者运动和认知疾病进展的基于血浆的生物标志物进行无偏见的发现筛选。 公共卫生相关性：目前，帕金森病患者对生物标记物的需求很大，但该领域可能正在达到通过有针对性的生物标记物发现方法所能实现的极限。这里提出的研究可能会将两个已经复制的生物标记物移到临床翻译的打击距离内，同时承诺通过公正的发现发现更多的、更早的线索。因此，他们有很高的潜力通过开发实用的、基于血浆的生物标记物来提高帕金森病第二阶段临床试验的效率和结果，从而实现这一RFA的目标。

DESCRIPTION (provided by applicant): The need for well-validated, easily-accessible biomarkers for Parkinson's disease (PD) and endophenotypes within PD is great. Despite this need, candidate markers reported in the literature are few, and the most well-establishd biochemical biomarkers described to date in PD are cerebrospinal fluid (CSF) markers, creating a substantial barrier to widespread use. Until very recently, the search for biomarkes in PD and many other diseases was limited by the fact that a targeted approach was needed - that is, one could not find a biomarker unless there was a priori reason to believe that a particular gene/protein would be informative in the first place. In the past 10 years, however, technological advances have allowed the advent of large, unbiased screens of hundreds, if not thousands, of potential candidates, a radical change in approach pioneered in the world of genetics/genomics. We have previously used such an unbiased approach to discover, and subsequently replicate, a novel association between plasma levels of epidermal growth factor (EGF) and cognitive impairment in PD, demonstrating that low EGF levels may both correlate with and predate the onset of dementia in PD. In parallel, we hve found that low plasma Apolipoprotein A1 (ApoA1) levels may indicate increased risk for loss of dopaminergic system integrity and uncovered five potential plasma-based biomarkers correlating with rate of decline in PD. Here, we propose to build on this hands-on experience to move our findings forward in a pipeline towards clinical translation while also conducting a de novo discovery screen of 450 plasma proteins for additional biomarkers for PD and endophenotypes within PD. Embedded in our approach is an understanding that unbiased biomarker discovery methods require replication in additional cohorts of subjects, followed by validation through across-site replication of findings and investigations into biological mechanisms. Thus, our aims are: 1) To validate two previously-replicated plasma-based biomarkers in PD -- determining whether plasma epidermal growth factor (EGF) levels are a biomarker for cognitive performance in PD, and whether plasma apolipoprotein A1 (ApoA1) levels are a biomarker for PD risk by evaluating their performance in additional cohorts of patients from independent clinical sites and exploring aspects of their biology and potential for clinical translation~ 2) To replicate five newly-discovered plasma-based biomarkers for rate of decline in PD -- determining whether levels of AXL receptor tyrosine kinase (AXL), matrix metalloproteinase-2 (MMP-2), interleukin-7 (IL-7), EGF, and C-reactive protein (CRP) correlate with rate of PD motor decline in additional cohorts of UPenn patients, using alternative platforms for measurement~ and 3) To perform an unbiased discovery screen for plasma-based biomarkers of motor and cognitive disease progression in PD using a novel, protein-DNA-aptamer-based technology for simultaneous measurement of 450 plasma proteins. PUBLIC HEALTH RELEVANCE: Currently, the need for biomarkers in PD is great, but the field may be reaching the limits of what can be accomplished through a targeted approach to biomarker discovery. The studies proposed here may move two already-replicated biomarkers within striking distance of clinical translation, while promising to uncover additional, earlier-stge leads through unbiased discovery. As such, they have high potential to meet the goal of this RFA by developing practical, plasma-based biomarkers to improve the efficiency and outcome of Phase II clinical trials in PD.