Decoding cerebrospinal fluid huntingtin biomarkers

项目总结 本项目的目标是将脑脊液(CSF)亨廷顿蛋白(HTT)的功能定量作为一种 亨廷顿病(HD)生物标志物。一期一期降温治疗HD的临床试验 最近得出结论，突变型HTT(MtHTT)蛋白在脑脊液中呈剂量依赖性减少 治疗过的病人。这种测量的使用是基于我们之前使用一种新型的超灵敏mtHTT的工作 检测实验证明抑制整个小鼠中枢神经系统的HTT导致相关性降低 脑脊液mtHTT，但要在临床上有意义地使用这一方法还需要进一步的研究。治疗性 正在试验中的策略预计主要活跃在大脑表面区域，而其他正在开发的策略包括 预计主要活跃于大脑更深层的区域或特定类型的细胞。为此，有必要 了解局部和细胞类型对脑脊液mtHTT的影响，以便预测治疗引起的变化 针对目标组织的手段(S)。到处表达mtHTT的小鼠脑和脑脊液中mtHTT的比较 除了研究中的大脑区域或细胞类型外，mtHTT表达无处不在的人将被用来识别 对脑脊液mtHTT的比例贡献，并提供了一种推断治疗引起的变化幅度的方法 脑脊液中的人的脑组织。还有必要了解mtHTT是如何进入脑脊液的。脑与脑的比较 有神经变性和无神经变性的系统中的脑脊液HTT将被用来区分被动释放HTT AS 由于HTT主动转运到脑脊液，细胞死亡并破裂。此外，其脑清除量的动力学 MtHTT将通过细胞内或细胞外直接向小鼠脑内输送mtHTT蛋白来描述 并随后在多个产后时间点测量脑、脑脊液和血浆mtHTT。 HTT分泌和淋巴系统的扰动将被用来研究mtHTT是如何从 进入脑细胞，进入脑脊液，最终进入血液。同时，mtHTT将被纵向量化 HD患者和对照组的脑脊液和血浆样本，并与表型数据进行比较，以确定如何 生物体液mtHTT在典型的临床试验间隔内随个体进展而变化，从而分离 依赖于时间和治疗的变化。这也将决定脑脊液mtHTT浓度是否可以用于 更准确地预测疾病的转化和进展。我们还将尝试量化wtHTT蛋白在 研究HTT的潜在细胞外功能，并为临床试验提供等位基因识别 有选择性的药物。这些研究的结果将为解释临床定量提供必要的基础。 CSFHTT，确定哪些类型的治疗可以通过这一措施进行有效的评估，并确定 纵向脑脊液HTT定量在HD病情监测和临床试验选择中的价值 参与者。

PROJECT SUMMARY The goal of this project is to functionalize quantitation of cerebrospinal fluid (CSF) huntingtin (HTT) protein as a Huntington disease (HD) biomarker. The first Phase I/IIa HTT lowering clinical trial for the treatment of HD recently concluded demonstrating dose-dependent reduction of mutant HTT (mtHTT) protein in the CSF of treated patients. The use of this measure was based on our previous work using a novel ultrasensitive mtHTT detection assay to demonstrate that suppression of HTT in the entire mouse CNS results in correlative reduction of CSF mtHTT, but further studies are required for meaningful use of this measure in the clinic. The therapeutic under trial is expected to mostly be active in superficial brain regions, while other strategies in development are expected to mostly be active in deeper brain regions or specific cell types. For this reason, it is necessary to know the regional and cell type contributions to CSF mtHTT in order to predict what a treatment-induced change means for the targeted tissue(s). Comparison of brain and CSF mtHTT in mice that express mtHTT everywhere except the brain region or cell type at study to those with ubiquitous mtHTT expression will be used to discern the proportional contributions to CSF mtHTT and provide a way to infer magnitude of treatment-induced changes in the brain by those in CSF. It will also be necessary to know how mtHTT enters CSF. Comparison of brain and CSF HTT in systems with and without neurodegeneration will be used to distinguish passive release of HTT as cells die and break open from active transport of HTT to CSF. Furthermore, the kinetics of brain clearance of mtHTT will be delineated by ectopic delivery of intra- or extracellular mtHTT protein directly to the brains of mice and subsequent measurement of brain, CSF, and plasma mtHTT at multiple post-delivery time points. Perturbation of HTT secretion and the glymphatic system will be used to investigate how mtHTT moves from inside cells of the brain to the CSF and eventually the blood. Concurrently, mtHTT will be quantified in longitudinal CSF and plasma samples from HD patients and controls and compared to phenotypic data to determine how biofluid mtHTT changes over typical clinical trial intervals and with progression in individuals, thus separating time- and treatment-dependent changes. This will also determine if CSF mtHTT concentration can be used to more accurately predict disease conversion and progression. We will also attempt to quantify wtHTT protein in CSF to investigate potential extracellular functions of HTT as well as enable allelic discrimination for trials of selective agents. The results of these studies will provide the necessary basis to interpret clinical quantitation of CSF HTT, determine which types of therapeutics could be effectively evaluated by this measure, and ascertain the predictive value of longitudinal CSF HTT quantitation in monitoring HD progression and selecting clinical trial participants.