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)研究面临的挑战中，很少有比临床前疾病的早期发现更紧迫的了。目前还没有在大脑不可逆转的恶化之前诊断帕金森病的方法。缺乏有用的生物标记物也是疾病修正疗法研究的障碍，导致了人们的强烈共识，即开发PD生物标记物的重大倡议至关重要。嗅觉是帕金森病的首批受害者之一，高达90%的患者会出现嗅觉丧失。此外，在基于人群的前瞻性研究中发现嗅觉受损和随后的帕金森病诊断之间存在关联，这表明嗅觉障碍是特发性帕金森病的非常早期的迹象。尽管近年来嗅觉作为帕金森病的生物标志物的兴趣显著增加，但嗅觉丧失的机制及其与帕金森病的因果关系仍不清楚，-突触核病是帕金森病的主要病理标志。这一知识差距已经成为诊断和治疗进展的主要障碍。因此，了解导致帕金森病临床前和症状阶段嗅觉丧失的嗅觉系统神经解剖学变化是至关重要的，因为在定义明确的动物模型中理解这一途径将显著影响我们对多巴胺能神经元丧失机制的了解，同时为快速和客观地评估疾病风险提供了一种手段。我们的总体假设是，帕金森病患者的嗅觉损害是基于特定神经解剖学变化的早期事件，具有可测量的功能影响，并与上游-突触核蛋白毒性直接相关。我们将利用一个成熟的帕金森病小鼠遗传模型，即mThy1-hSNCA转基因小鼠的α-突触核蛋白聚集沉积，并强调在前驱阶段的实验来评估嗅觉系统。这一模型与人类帕金森病的嗅觉功能障碍的病因高度相关，因为它的结构和与人类帕金森病的表面有效性有关。此外，我们将通过开发：i)标记气味受体表达的转基因小鼠(M72-或P2-IRES-tau-lacZ)来精确跟踪嗅觉神经元(OSNs)及其刻板的嗅觉感觉图，ii)TYFP转基因小鼠用于分析二尖瓣细胞、它们的神经电路和无创性皮质投射，以及iii)先进的无创功能神经成像(fMRI、MEMRI和GT-tMRI)，从而实现对嗅觉系统损伤的高水平定义。通过结合行为、生化和组织学评估，我们将阐明帕金森病患者早期嗅觉丧失的神经解剖学基础，同时也将阐明联核症在帕金森病相关性嗅觉功能障碍中的作用。提出了三个目标：目标1-了解突触后-突触核蛋白毒性在脑内结构和功能改变中的作用 帕金森病患者的嗅觉感觉神经元及其刻板的嗅觉映射导致嗅觉受损。目的2-阐明-突触核蛋白聚集异常如何引起嗅球二尖瓣细胞及其神经回路和调制中间神经元的结构改变，从而导致帕金森病患者嗅觉受损。目的3-阐明异常的-突触核蛋白聚集体如何改变二尖瓣细胞的无毛皮质投射和靶点，从而损害帕金森病患者的气味识别和辨别能力。这些研究意义重大，因为这些结果将加深对帕金森病嗅觉丧失机制及其与病理-突触核蛋白的关系的理解。我们的结果将反过来提供新疗法的线索，以及有助于早期检测、预测和监测疾病进展或疾病修饰疗法结果的生物标记物。我们的方法是创新的，因为它们利用了尖锐的遗传学和尖端分析工具，而且这项研究具有很高的可行性 该团队在嗅觉、帕金森病、神经退行性变、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.