Assessing skin biomarkers for preclinical diagnosis of PD and non-PD Parkinsonism

摘要 疾病相关的α-突触核蛋白(α-Synd)，以错误折叠蛋白的形式积聚和沉积 大脑中的聚集物是帕金森病(PD)和其他疾病的病理标志 引起非帕金森病的联核病，如多系统萎缩(MSA)和痴呆 路易氏小体(DLb)。目前，对这些疾病的明确诊断通常需要检测α综合征 尸检大脑样本。帕金森病和非帕金森病的一个未得到满足的医学需求是为 诊断、定义疾病严重程度并评估潜在的神经保护疗法 标本。值得注意的是，通过免疫组织化学或免疫组织化学方法在PD患者的皮肤中观察到了aSynD 而免疫荧光显微镜的灵敏度从0-100%变化很大。值得注意的是， 使用名为实时震动诱导转换(RT-QuIC)的超灵敏测试，我们最近的初步研究 研究表明，在帕金森病尸检皮肤组织中可以很容易地检测到αSYND特异性种子活性 特异性和敏感度均为100%。此外，蛋白质错误折叠循环扩增(PMCA)， 另一种检测α同步播种活性的高灵敏度方法，即使在甲醛固定的小鼠脑组织中也是如此 MSA患者，也能够检测到PD患者的皮肤α同步播种活动，但在非PD对照组中检测不到。我们 假设RT-QuIC和PMCA是建立皮肤α综合征的高度敏感和强大的平台 作为帕金森病死后和死前诊断的生物标志物。要检验这一假设，请看以下内容 将致力于三个目标：(1)建立皮肤aSynD作为帕金森病死后诊断的生物标志；(2) 用RT-QIC和RT-QIC评估皮肤综合征作为生前诊断和确定帕金森病严重程度的生物标志物 以及(3)确定皮肤α综合征是诊断非帕金森病的生物标记物 和DLB，以及区分同核病和变态病，如皮质基底部变性和 进行性核上性麻痹。我们相信，这项研究产生的新知识将进一步应用于 其他神经退行性疾病，包括最常见的神经退行性疾病阿尔茨海默氏症 疾病，其中疾病特异的错误折叠蛋白，如tau蛋白和Aβ肽也被 在受影响患者的皮肤中发现。

ABSTRACT The disease-associated alpha-synuclein (αSynD) that accumulates and deposits as misfolded protein aggregates in the brain is the pathological hallmark of Parkinson disease (PD), and also of other synucleinopathies causing non-PD parkinsonism such as multiple system atrophy (MSA) and dementia with Lewy bodies (DLB). Currently, a definitive diagnosis of these disorders often requires the detection of αSynD in autopsy brain samples. An unmet medical need for PD and non-PD parkinsonism is to identify biomarkers for diagnosis, defining disease severity, and assessing potential neuroprotective therapeutics in easily accessible specimens. Notably, aSynD has been observed in the skin of PD patients by immunohistochemistry or immunofl3`2uorescence microscopy whereas the sensitivity varied dramatically from 0-100%. Remarkably, using the ultrasensitive assay termed real-time quaking-induced conversion (RT-QuIC), our recent preliminary studies have shown that the αSynD-specific seeding activity is readily detectable in autopsy skin tissues of PD patients with 100% specificity and sensitivity. Moreover, the protein misfolding cyclic amplification (PMCA), another highly sensitive assay that detects αSynD seeding activity even in formaldehyde-fixed brain tissue of a MSA patient, is also able to detect skin αSynD seeding activity in PD patients but not in non-PD controls. We hypothesize that RT-QuIC and PMCA are highly sensitive and robust platforms to establish skin αSynD as a biomarker for postmortem and premortem diagnoses of PD. To test this hypothesis, the following three Aims will be pursued: (1) to establish skin aSynD as a biomarker for postmortem diagnosis of PD; (2) Assess skin SynD as a biomarker for premortem diagnosis and defining PD severity using RT-QuIC and PMCA; and (3) Determine skin αSynD as a biomarker for diagnosis of non-PD synucleinopathies such as MSA and DLB as well as differentiate synucleinopathies from tauopathies such as corticobasal degeneration and progressive supranuclear palsy. We believe that new knowledge generated from this study will further apply to other neurodegenerative diseases including the most common neurodegenerative disease Alzheimer's disease, where the disease-specific misfolded proteins such as tau protein and Aβ peptides have been also found in the skin of affected patients.