Single domain antibodies (VHHs) are potentially disruptive therapeutics, with important biological value for treatment of several diseases, including neurological disorders. However, VHHs have not been widely used in the central nervous system (CNS), largely because of their restricted blood-brain barrier (BBB) penetration. Here, we propose a gene transfer strategy based on BBB-crossing adeno-associated virus (AAV)-based vectors to deliver VHH directly into the CNS. As a proof-of-concept, we explored the potential of AAV-delivered VHH to inhibit BACE1, a well-characterized target in Alzheimer's disease. First, we generated a panel of VHHs targeting BACE1, one of which, VHH-B9, shows high selectivity for BACE1 and efficacy in lowering BACE1 activity in vitro. We further demonstrate that a single systemic dose of AAV-VHH-B9 produces positive long-term (12 months plus) effects on amyloid load, neuroinflammation, synaptic function, and cognitive performance, in the AppNL-G-F Alzheimer's mouse model. These results constitute a novel therapeutic approach for neurodegenerative diseases, which is applicable to a range of CNS disease targets.

中文翻译：

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AAV 介导的抗 BACE1 VHH 递送可减轻阿尔茨海默病模型中的病理学。

单域抗体 (VHH) 是潜在的破坏性疗法，对于治疗包括神经系统疾病在内的多种疾病具有重要的生物学价值。然而，VHH 尚未广泛用于中枢神经系统 (CNS)，主要是因为它们的血脑屏障 (BBB) 渗透受限。在这里，我们提出了一种基于 BBB 交叉腺相关病毒 (AAV) 载体的基因转移策略，以将 VHH 直接递送到 CNS 中。作为概念验证，我们探索了 AAV 传递的 VHH 抑制 BACE1 的潜力，BACE1 是阿尔茨海默病中一个特征明确的靶标。首先，我们生成了一组针对 BACE1 的 VHH，其中一个 VHH-B9 显示出对 BACE1 的高选择性和在体外降低 BACE1 活性的功效。我们进一步证明，在 AppNL-GF 阿尔茨海默病小鼠模型中，单次全身剂量的 AAV-VHH-B9 对淀粉样蛋白负荷、神经炎症、突触功能和认知能力产生长期（12 个月以上）的积极影响。这些结果构成了一种新的神经退行性疾病治疗方法，适用于一系列中枢神经系统疾病靶点。