Detection of the pathological and disease-associated alpha-synuclein (αSynD) in the brain is required to formulate the definitive diagnosis of multiple system atrophy (MSA) and Parkinson’s disease (PD). We recently showed that αSynD can be detected in the olfactory mucosa (OM) of MSA and PD patients. For this reason, we have performed the first interlaboratory study based on α-synuclein Real-Time Quaking-Induced Conversion (αSyn_RT-QuIC) analysis of OM samples collected from PD and MSA patients with the parkinsonian (MSA-P) and cerebellar (MSA-C) phenotypes. OM samples were prospectively collected from patients with a probable diagnosis of MSA-P (n = 20, mean disease duration 4.4 years), MSA-C (n = 10, mean disease duration 4 years), PD (n = 13, mean disease duration 8 years), and healthy control subjects (HS) (n = 11). Each sample was analyzed by αSyn_RT-QuIC in two independent specialized laboratories, one located in Italy (ITA-lab) and one located in the USA (USA-lab). Both laboratories have developed and used harmonized αSyn_RT-QuIC analytical procedures. Results were correlated with demographic and clinical data. The αSyn_RT-QuIC analysis reached a 96% interrater agreement of results (IAR) between laboratories (Kappa = 0.93, 95% CI 0.83–1.00). In particular, αSyn_RT-QuIC seeding activity was found in the OM of 9/13 patients with PD (sensitivity 69%, IAR 100%) and 18/20 patients with MSA-P (sensitivity 90%, IAR 100%). Interestingly, samples collected from patients with MSA-C did not induce αSyn_RT-QuIC seeding activity, except for one subject in USA-lab. Therefore, we found that MSA-P and MSA-C induced opposite effects. Regardless of disease diagnosis, the αSyn_RT-QuIC seeding activity correlated with some clinical parameters, including the rigidity and postural instability. Our study provides evidence that OM-αSynD may serve as a novel biomarker for accurate clinical diagnoses of PD, MSA-P, and MSA-C. Moreover, αSyn_RT-QuIC represents a reliable assay that can distinguish patients with MSA-P from those with MSA-C, and may lead to significant advancements in patients stratification and selection for emerging pharmacological treatments and clinical trials.

中文翻译：

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通过嗅黏膜的 RT-QuIC 分析区分 MSA-P 和 MSA-C：两个专业实验室之间对测定重现性的首次评估

需要检测大脑中的病理和疾病相关的 α-突触核蛋白 (αSynD) 以制定多系统萎缩 (MSA) 和帕金森病 (PD) 的明确诊断。我们最近表明，可以在 MSA 和 PD 患者的嗅黏膜 (OM) 中检测到 αSynD。出于这个原因，我们对从帕金森病 (MSA-P) 和小脑 (MSA) 的 PD 和 MSA 患者收集的 OM 样本进行了基于 α-突触核蛋白实时震颤诱导转换 (αSyn_RT-QuIC) 分析的第一个实验室间研究-C) 表型。从可能诊断为 MSA-P（n = 20，平均病程 4.4 年）、MSA-C（n = 10，平均病程 4 年）、PD（n = 13，平均病程）的患者中前瞻性收集 OM 样本持续 8 年）和健康对照受试者 (HS) (n = 11)。每个样品在两个独立的专业实验室中由 αSyn_RT-QuIC 分析，一个位于意大利 (ITA-lab)，另一个位于美国 (USA-lab)。两个实验室都开发并使用了统一的 αSyn_RT-QuIC 分析程序。结果与人口统计学和临床​​数据相关。αSyn_RT-QuIC 分析在实验室之间达到 96% 的结果一致性 (IAR) (Kappa = 0.93, 95% CI 0.83–1.00)。特别是，在 9/13 名 PD 患者（敏感性 69%，IAR 100%）和 18/20 名 MSA-P 患者（敏感性 90%，IAR 100%）的 OM 中发现了 αSyn_RT-QuIC 播种活性。有趣的是，从 MSA-C 患者收集的样本并没有诱导 αSyn_RT-QuIC 播种活动，除了美国实验室的一名受试者。因此，我们发现 MSA-P 和 MSA-C 会产生相反的效果。无论疾病诊断如何，αSyn_RT-QuIC 播种活动与一些临床参数相关，包括僵硬和姿势不稳定性。我们的研究提供的证据表明，OM-αSynD 可以作为一种新的生物标志物，用于准确诊断 PD、MSA-P 和 MSA-C。此外，αSyn_RT-QuIC 代表了一种可靠的检测方法，可以区分 MSA-P 患者和 MSA-C 患者，并可能在新兴药物治疗和临床试验的患者分层和选择方面取得重大进展。