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，其特征是黑质多巴胺能神经元的明显缺失。已确定的潜在病理生理机制包括α-突触核蛋白（αSyn）的聚集和随后的神经元内包涵体（Lewy小体，LB）的形成。αSyn参与神经元可塑性和突触囊泡的运输和释放。此外，αSyn水平通过几种生化途径调节DA稳态。可能的是，可溶性和聚集的αSyn的平衡对于（多巴胺能）神经元的活力至关重要，尽管可溶性单体、寡聚体和不溶性、聚集的αSyn的确切作用仍有待澄清。到目前为止，小的前纤维低聚物被认为是主要的神经毒性的罪魁祸首和LB可能会提供一个保护机制，而隔离的有毒低聚物结构。目前治疗PD的既定策略是对症治疗。然而，最近的研究集中在基础病理生理学上，例如靶向αSyn聚集和扩散的免疫疗法。尽管如此，任何化合物递送的主要问题是血脑屏障（BBB）的穿透，血脑屏障提供了阻止超过98%的小分子通过的有效障碍。低强度聚焦超声（FUS）是一种新技术，它利用声能治疗特定的大脑区域，而无需打开颅骨。FUS联合静脉注射充气微泡（MB）已被用于短暂和安全地打开BBB。因此，PD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）代表FUS的感兴趣的靶点。昆士兰州脑研究所的Götz实验室开发了一种FUS（SUS）的扫描超声方法，该方法允许对整个小鼠大脑进行FUS治疗。使用各种超声应用模式，他们报告了在不同AD小鼠模型中细胞外淀粉样蛋白-β斑块和细胞内tau纤维的大量清除。我们的项目的目的是研究在小鼠Thy-1启动子控制下过表达人野生型αSyn的转基因小鼠中重复应用各种SUS模型的效果。除运动和认知功能外，还将使用免疫组织化学和分子技术在不同脑区和血浆中评估SUS对αSyn水平、寡聚体形成和聚集的影响。此外，还将研究突触功能和多巴胺稳态中的α Syn相关机制以及对小胶质细胞活化和清除机制的影响。总之，这项研究可能与聚焦超声的治疗翻译和人类PD患者的预期应用高度相关。此外，该项目还将深入了解可能的新方法，以在BBB中与SUS结合提供靶向治疗。

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.