Department of Biosciences, Università degli Studi di Milano, Milan, Italy.
Fondazione Grigioni per il Morbo di Parkinson, Milan, Italy.
Brain. 2020 Mar 1;143(3):920-931. doi: 10.1093/brain/awaa008.
A variety of cellular processes, including vesicle clustering in the presynaptic compartment, are impaired in Parkinson's disease and have been closely associated with α-synuclein oligomerization. Emerging evidence proves the existence of α-synuclein-related pathology in the peripheral nervous system, even though the presence of α-synuclein oligomers in situ in living patients remains poorly investigated. In this case-control study, we show previously undetected α-synuclein oligomers within synaptic terminals of autonomic fibres in skin biopsies by means of the proximity ligation assay and propose a procedure for their quantification (proximity ligation assay score). Our study revealed a significant increase in α-synuclein oligomers in consecutive patients with Parkinson's disease compared to consecutive healthy controls (P < 0.001). Proximity ligation assay score (threshold value > 96 using receiver operating characteristic) was found to have good sensitivity, specificity and positive predictive value (82%, 86% and 89%, respectively). Furthermore, to disclose the role of putative genetic predisposition in Parkinson's disease aetiology, we evaluated the differential accumulation of oligomers in a unique cohort of 19 monozygotic twins discordant for Parkinson's disease. The significant difference between patients and healthy subjects was confirmed in twins. Intriguingly, although no difference in median values was detected between consecutive healthy controls and healthy twins, the prevalence of healthy subjects positive for proximity ligation assay score was significantly greater in twins than in the consecutive cohort (47% versus 14%, P = 0.019). This suggests that genetic predisposition is important, but not sufficient, in the aetiology of the disease and strengthens the contribution of environmental factors. In conclusion, our data provide evidence that α-synuclein oligomers accumulate within synaptic terminals of autonomic fibres of the skin in Parkinson's disease for the first time. This finding endorses the hypothesis that α-synuclein oligomers could be used as a reliable diagnostic biomarker for Parkinson's disease. It also offers novel insights into the physiological and pathological roles of α-synuclein in the peripheral nervous system.
多种细胞过程，包括突触前隔室中的囊泡聚集，在帕金森病中受到损害，并且与α-突触核蛋白寡聚化密切相关。新出现的证据证明了α-突触核蛋白相关病理学在周围神经系统中的存在，尽管在活体患者中存在α-突触核蛋白寡聚体的原位情况仍未得到充分研究。在这项病例对照研究中，我们通过邻近连接测定法在皮肤活检中的自主纤维突触末梢中显示了以前未检测到的α-突触核蛋白寡聚体，并提出了一种对其进行定量的方法（邻近连接测定评分）。我们的研究显示，与连续的健康对照组相比，连续的帕金森病患者的α-突触核蛋白寡聚体显著增加（P < 0.001）。发现邻近连接测定评分（使用接收者操作特征的阈值> 96）具有良好的敏感性、特异性和阳性预测值（分别为 82%、86%和 89%）。此外，为了揭示潜在遗传易感性在帕金森病发病机制中的作用，我们在一组独特的 19 对帕金森病不一致的同卵双胞胎中评估了寡聚体的差异积累。在双胞胎中证实了患者和健康受试者之间的显著差异。有趣的是，尽管在连续的健康对照组和健康双胞胎之间没有检测到中位数的差异，但在双胞胎中邻近连接测定评分阳性的健康受试者的患病率明显高于连续队列（47%对 14%，P = 0.019）。这表明遗传易感性在疾病发病机制中很重要，但不是充分的，并且增强了环境因素的贡献。总之，我们的数据首次提供了证据表明，α-突触核蛋白寡聚体在帕金森病患者的皮肤自主纤维突触末梢中积累。这一发现支持了α-突触核蛋白寡聚体可以作为帕金森病可靠诊断生物标志物的假说。它还为α-突触核蛋白在周围神经系统中的生理和病理作用提供了新的见解。
