BACKGROUND The accumulation of pathological tau is the main component of neurofibrillary tangles and other tau aggregates in several neurodegenerative diseases, referred to as tauopathies. Recently, immunotherapeutic approaches targeting tau have been demonstrated to be beneficial in decreasing tauopathy in animal models. We previously found that passive immunotherapy with anti-tau antibody to human tau or expression of an anti-tau secreted single-chain variable fragment (scFv) in the central nervous system of a mouse model of tauopathy decreased but did not remove all tau-associated pathology. Although these and other studies demonstrate that conventional immunotherapeutic approaches targeting tau can influence tau pathogenesis, the majority of pathological tau remains in the cytosol of cells, not typically accessible to an extracellular antibody. Therefore, we reasoned targeting intracellular tau might be more efficacious in preventing or decreasing tauopathy. METHODS By utilizing our anti-tau scFv, we generated anti-tau intrabodies for the expression in the cytosol of neurons. To enhance the degradation capacity of conventional intrabodies, we engineered chimeric anti-tau intrabodies fused to ubiquitin harboring distinct mutations that shuttle intracellular tau for either the proteasome or lysosomal mediated degradation. To evaluate the efficacy in delaying or eliminating tauopathy, we expressed our tau degrading intrabodies or controls in human tau transgenic mice by adeno-associated virus prior to overt tau pathology and after tau deposition. RESULTS Our results demonstrate, the expression of chimeric anti-tau intrabodies significantly reduce tau protein levels in primary neuronal cultures expression human tau relative to a non-modified anti-tau intrabody. We found the expression of engineered tau-degrading intrabodies destined for proteasomal-mediated degradation are more effective in delaying or eliminating tauopathy than a conventional intrabody in aged human tau transgenic mice. CONCLUSION This study, harnesses the strength of intrabodies that are amendable for targeting specific domains or modifications with the cell-intrinsic mechanisms that regulate protein degradation providing a new immunotherapeutic approach with potentially improved efficacy.

中文翻译：

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用工程化的tau降解体内抗体靶向tauopathy。

背景技术病理tau的积累是神经原纤维缠结和其他tau聚集体在几种神经退行性疾病（称为tauopathies）中的主要成分。最近，在动物模型中，针对tau的免疫治疗方法已被证明对减少tauopathy有好处。我们先前发现，针对人tau蛋白的抗tau抗体或在tauopathy小鼠模型的中枢神经系统中抗tau分泌的单链可变片段（scFv）的表达，被动免疫疗法有所减少，但并未消除所有与tau相关的病理。尽管这些研究和其他研究表明，靶向tau的常规免疫治疗方法可以影响tau的发病机理，但大多数病理性tau仍保留在细胞的细胞质中，通常是细胞外抗体无法接近的。因此，我们认为靶向细胞内tau可能在预防或减少tau病方面更有效。方法利用我们的抗tau scFv，我们产生了抗tau抗体，用于在神经元的细胞质中表达。为了增强常规体内抗体的降解能力，我们设计了与泛素融合的嵌合抗tau抗体，这些抗体具有独特的突变，这些突变将胞内tau穿梭于蛋白酶体或溶酶体介导的降解中。为了评估延迟或消除tau病的功效，我们在明显的tau病理之前和tau沉积后，通过腺相关病毒在人类tau转基因小鼠中表达了tau降解体内或对照。结果我们的结果表明，相对于未修饰的抗tau抗体，嵌合抗tau抗体的表达显着降低了表达人tau的原代神经元培养物中tau蛋白的水平。我们发现，工程化的tau降解内体的表达比常规的体内tau蛋白更能有效地延缓或消除tau病。结论这项研究利用可调节靶向特定结构域或修饰的体内抗体的强度，利用调节蛋白质降解的细胞内在机制，提供了一种新的免疫治疗方法，其疗效可能得到改善。我们发现，工程化的tau降解内体的表达比常规的体内tau蛋白更能有效地延缓或消除tau病。结论本研究利用可调节靶向特定结构域或修饰的体内抗体的强度，利用调节蛋白质降解的细胞内在机制，提供了一种新的免疫治疗方法，可能会改善疗效。我们发现，工程化的tau降解内体的表达比常规的体内tau蛋白更能有效地延缓或消除tau病。结论本研究利用可调节靶向特定结构域或修饰的体内抗体的强度，利用调节蛋白质降解的细胞内在机制，提供了一种新的免疫治疗方法，可能会改善疗效。