Effects of repeated low-intensity ultrasound treatment on alpha-synuclein pathology and motor and behavioral outcome in an alpha-synuclein transgenic mouse model

帕金森病（PD）是一种进行性神经退行性疾病，其特征是黑质中多巴胺能神经元的明显丧失。已确定的潜在病理生理机制包括α -突触核蛋白（αSyn）的聚集和随后形成的神经元内包涵体（路易体，LB）。α - syn参与神经元可塑性和突触囊泡的转运和释放。此外，α - syn水平通过多种生化途径调节DA稳态。可能，可溶性αSyn和聚集αSyn的平衡对（多巴胺能）神经元的生存至关重要，尽管可溶性单体、低聚物和不可溶性聚集αSyn的确切作用仍有待阐明。迄今为止，小的纤维前低聚物被认为是主要的神经毒性罪魁祸首，而LBs可能通过分离有毒的低聚物结构提供了一种保护机制。目前治疗帕金森病的既定策略是对症治疗。然而，最近的研究主要集中在潜在的病理生理上，例如针对αSyn聚集和扩散的免疫治疗。然而，任何化合物输送的一个主要问题是血脑屏障（BBB）的穿透，它提供了一个有效的障碍，阻止98%的小分子通过。低强度聚焦超声（FUS）是一种利用声能在不打开颅骨的情况下治疗确定的大脑区域的新技术。FUS联合静脉注射充气微泡（MB）已被用于短暂和安全地打开血脑屏障。因此，帕金森病和其他具有蛋白质聚集的神经退行性疾病，如阿尔茨海默病（AD）是FUS的有趣靶点。昆士兰脑研究所Götz实验室开发了一种FUS （SUS）的扫描超声方法，允许FUS治疗整个小鼠大脑。利用不同的超声应用模式，他们报道了在不同的AD小鼠模型中细胞外淀粉样蛋白-β斑块和细胞内tau原纤维的大量清除。我们的项目目的是研究在小鼠Thy-1启动子控制下，重复应用各种SUS模型对过表达人野生型α - syn的转基因小鼠的影响。除了运动和认知功能外，还将利用免疫组织化学和分子技术评估SUS对不同脑区和血浆αSyn水平、低聚物形成和聚集的影响。此外，α突触相关的突触功能和多巴胺稳态机制以及对小胶质细胞激活和清除机制的影响将被进一步研究。总之，本研究可能与聚焦超声的治疗翻译以及在人类PD患者中的预期应用高度相关。此外，该项目将为跨血脑屏障联合SUS提供靶向治疗的可能新方法提供见解。

Parkinson’s disease (PD) is a progressive neurodegenerative disorder characterized by the distinct loss of dopaminergic neurons in the substantia nigra. Established underlying pathophysiologic mechanisms include the aggregation of alpha-synuclein (αSyn) and the subsequent formation of intraneuronal inclusions (Lewy bodies, LB). αSyn is implicated in neuronal plasticity and the transport and release of synaptic vesicles. In addition, αSyn levels modulate DA homeostasis through several biochemical pathways. Likely, the balance of soluble and aggregated αSyn is critical for the viability of (dopaminergic) neurons although the precise roles of soluble monomers, oligomers and insoluble, aggregated αSyn remain to be clarified. To date, small prefibrillar oligomers are considered the main neurotoxic culprits and LBs may rather provide a protective mechanism by segregating the toxic oligomeric structures. Current established strategies to treat PD are symptomatic. However, recent research focused on the underlying pathophysiology, e.g. immunotherapies targeting αSyn aggregation and spreading. Nonetheless, a major problem for any compound delivery is the penetration of the blood-brain barrier (BBB), which provides an effective obstacle preventing the passage of 98% of small molecules. Low-intensity focused ultrasound (FUS) is a novel technology that uses acoustic energy to treat defined brain areas without opening the skull. FUS in combination with intravenously injected gas-filled microbubbles (MB) has been used to open the BBB transiently and safely. Thus, PD and other neurodegenerative diseases with protein aggregation, such as Alzheimer’s disease (AD) represent interesting targets for FUS. The Götz laboratory of the Queensland Brain Institute developed a scanning ultrasound approach of FUS (SUS) that allows FUS treatment of the entire mouse brain. Using various modes of ultrasound application, they reported massive clearance of extracellular amyloid-β plaques and intracellular tau fibrils in different AD mouse models. The aim of our project is to investigate the effects of repeated application of various SUS models in transgenic mice overexpressing human wild-type αSyn under control of the murine Thy-1 promoter. In addition to motor and cognitive function, the effects of SUS on the αSyn levels, the formation of oligomers, and aggregation will be assessed in different brain regions and the blood plasma using immunohistochemical and molecular techniques. Further, αSyn-related mechanisms in synaptic function and dopamine homeostasis as well as effects on microglial activation and clearance mechanisms will be investigated. Together, this research may be highly relevant for the therapeutic translation of focused ultrasound and the envisioned application in human PD patients. In addition, the project will provide insights into possible novel approaches to deliver targeted therapies in combination with SUS across the BBB.