Analysis of Olfactory Dysfunction for Early Diagnosis of Parkinson's Disease

 描述（由申请人提供）： 在帕金森病（PD）研究所面临的挑战中，很少有比早期发现临床前疾病更紧迫的了。目前还没有方法可以在大脑不可逆恶化之前诊断PD。缺乏有用的生物标志物也是疾病修饰疗法研究的一个障碍，这导致了强烈的共识，即开发PD生物标志物的重大举措至关重要。嗅觉是PD的第一个受害者，高达90%的患者发生嗅觉丧失。此外，在基于人群的前瞻性研究中发现嗅觉受损与随后的PD诊断之间存在关联，表明嗅觉功能障碍是特发性PD的非常早期的体征。尽管近年来使用嗅觉作为PD的生物标志物的兴趣大幅增加，但嗅觉丧失的机制及其与PD的主要病理标志β-突触核蛋白病的因果关系仍不清楚。这种知识差距已经成为诊断和治疗进展的主要障碍。因此，至关重要的是，我们了解嗅觉系统神经解剖学的变化，导致嗅觉丧失的临床前和症状阶段的PD，因为在明确的动物模型中了解这一途径将显着影响我们的知识的机制损失的多巴胺能神经元，并在同一时间提供一种手段，快速和客观的评估疾病的风险。我们的过度假设是PD中的嗅觉损伤是基于具有可测量的功能影响的特定神经解剖学变化的早期事件，并且与上游β-突触核蛋白毒性直接相关。我们将通过利用完善的PD小鼠遗传模型（即mThy 1-hSNCA转基因小鼠中的α-突触核蛋白聚集体沉积）并强调前驱期的实验来评估嗅觉系统。该模型与人类PD嗅觉功能障碍的病因学高度相关，因为它的结构和人类PD的表面有效性。此外，我们将通过以下方式实现嗅觉系统损伤的高水平定义：i）标记的气味受体表达转基因小鼠（M72-或P2-IRES-tau-LacZ），用于精确追踪嗅觉感觉神经元（OSN）和它们的刻板嗅觉感觉图，ii）thy 1-黄色荧光蛋白（YFP）转基因小鼠，用于分析二尖瓣细胞、它们的神经回路和原皮质投射，和iii）先进的非侵入性功能性神经成像（fMRI、MEMRI和GT-tMRI）。通过结合这些敏锐的方式与行为，生化和组织学评估，我们将阐明PD早期嗅觉丧失的神经解剖学基础，同时也解决了突触核蛋白病在PD相关嗅觉功能障碍中的作用。提出了三个目的：目的1 -了解突触后β-突触核蛋白毒性在结构和功能变化中的作用， 嗅觉感觉神经元及其刻板的嗅觉感觉图导致PD患者嗅觉受损。目的2 -阐明异常β-突触核蛋白聚集体如何诱导嗅球僧帽细胞、其神经回路和调节性中间神经元的结构变化，从而导致PD患者嗅觉受损。目的3 -阐明异常β-突触核蛋白聚集体如何改变二尖瓣细胞的原皮质投射和靶点，从而导致PD患者气味识别和辨别能力的损害。这些研究具有重要意义，因为其结果将加深对PD嗅觉丧失机制及其与病理性β-突触核蛋白的关系的理解。我们的研究结果将反过来为新疗法提供线索，以及用于早期检测，预测和监测疾病进展或疾病修饰疗法结果的生物标志物。我们的方法是创新的，因为它们利用了精辟的遗传和尖端的分析工具，这项研究是高度可行的，因为 该团队在嗅觉、PD、神经变性、氧化应激、神经行为测试和先进成像技术方面的专业知识。

 DESCRIPTION (provided by applicant): Of the challenges that face Parkinson's disease (PD) research, few are more pressing than early detection of preclinical disease. Currently no method exists to diagnose PD before the irreversible deterioration of the brain. The lack of useful biomarkers is also a roadblock for studies of disease-modifying therapies, leading to the strong consensus that a major initiative to develop PD biomarkers is essential. Sense of smell is among the first casualties of PD, with olfactory loss occurring in up to 90% of patients. Furthermore, an association between impaired olfaction and subsequent PD diagnosis has been found in prospective population-based studies, suggesting that olfactory dysfunction is a very early sign of idiopathic PD. Although interest in using olfaction as a biomarker for PD has increased substantially in recent years, the mechanism of olfactory loss and its cause-and-effect relationship to -synucleinopathy, a major pathological hallmark of PD, remain unclear. This knowledge gap has created a major roadblock to diagnostic and therapeutic progress. Thus, it is critical that we understand the olfactory system neuroanatomical changes that lead to loss of smell in both the preclinical and symptomatic phases of PD, since an understanding of this pathway in well-defined animal models would significantly impact our knowledge of the mechanisms for loss of dopaminergic neurons, and at the same time provide a means for rapid and objective assessment of disease risk. Our over-arching hypothesis is that olfactory damage in PD is an early event based on specific neuroanatomical changes with measurable functional impact, and is directly linked to upstream -synuclein toxicity. We will assess the olfactory system by capitalizing on a well-established murine genetic model of PD, namely α-synuclein aggregate deposition in mThy1-hSNCA transgenic mice, and emphasizing experiments during the prodromal stage. This model is highly relevant to the etiology of olfactory dysfunction in human PD owing to its construct and face validity with PD in humans. Moreover, we will achieve high-level definition of olfactory system injury by exploiting: i) tagged odorant receptor-expressing transgenic mice (M72- or P2-IRES- tau-LacZ) for precise tracking of olfactory sensory neurons (OSNs) and their stereotypic olfactory sensory map, ii) thy1-yellow fluorescent protein (YFP) transgenic mice for analyzing mitral cells, their neural circuitry and archicortical projections, and iii) advanced non-invasive functional neuroimaging (fMRI, MEMRI, and GT-tMRI). By combining these incisive modalities with behavioral, biochemical, and histological assessments, we will elucidate the neuroanatomical substrate for early olfactory loss in PD, while also addressing the role of synucleinopathy in PD-associated olfactory dysfunction. Three aims are proposed: Aim 1 - To understand the role of post-synaptic -synuclein toxicity in structural and functional changes in the olfactory sensory neurons and their stereotypic olfactory sensory map leading to impaired sense of smell in PD. Aim 2 - To elucidate how abnormal -synuclein aggregates induce structural changes in the olfactory bulb mitral cells, their neural circuitry and modulatory interneurons, leading to impaired sense of smell in PD. Aim 3 - To elucidate how abnormal -synuclein aggregates alter archicortical projections and targets of mitral cells leading to impaire odor identification and discrimination in PD. These studies are significant, as the results will enhance understanding of the mechanisms of olfactory loss in PD and its relationship to pathologic -synuclein. Our results will in turn provide clues to new therapies, as well as biomarkers useful for early detection, prognostication, and monitoring of either disease progression or outcomes of disease-modifying therapies. Our approaches are innovative, since they exploit incisive genetic and cutting-edge analytic tools, and the study is highly feasible due to the team's expertise in olfaction, PD, neurodegeneration, oxidative stress, neurobehavioral testing, and advanced imaging technologies.