Defining a clinically relevant time point for astrocyte targeted therapy in ALS

描述（由申请人提供）：肌萎缩性侧索硬化症（ALS）是全球最常见的神经肌肉疾病之一。它是一种毁灭性的运动神经元（MN）疾病，导致肌肉麻痹，最终导致呼吸衰竭，导致死亡。目前还没有有效的治疗方法来显著改变人类的病程。90%的ALS病例是散发的（SALS），其中没有已知的遗传或环境原因。其余10%的患者患有该疾病的家族变异（FALS）。大约20%的FALS在编码超氧化物歧化酶1 （SOD1）的基因内发生突变。对于这些FALS患者，突变体SOD1 （mtSOD1）是一个明确的药理学靶点，并且在几种ALS小鼠模型中已经证实mtSOD1的减少可以延长寿命。FALS和SALS的临床和病理表现相同，均发生显著的胶质细胞增生，星形胶质细胞和小胶质细胞增殖增加，并伴有选择性MN细胞死亡。最近使用mtSOD1动物模型的研究表明，非神经元细胞有助于疾病的发生和进展，并且非细胞自主运动神经元死亡的证据越来越多。事实上，已经有研究表明，通过培养转基因小鼠，将带螺纹的mtSOD1与表达胶质纤维酸性蛋白（GFAP）启动子的Cre的小鼠接触，可以降低星形胶质细胞中mtSOD1的表达，这对疾病有显著的影响。这些杂交表明，疾病进展明显减慢，对生存的影响是深远的。然而，这些研究仍然存在一个重要的问题：从星形胶质细胞中去除mtSOD1以延缓疾病进展和延长生存期的时机是什么？我们认为，确定疾病进展过程中mtSOD1切除仍然有效的最新时间点是很重要的，因为许多患者是在发病后才被诊断出来的。因此，确定ALS的“不可逆转点”对于治疗发展至关重要。我们最近报道了一种非常有效的方法，通过系统递送基于腺相关病毒血清型9 （AAV9）的载体，靶向成人中枢神经系统中的胶质细胞，主要是星形胶质细胞。这一发现将使我们的实验室能够在ALS小鼠模型疾病的不同时间点（发病、早期和晚期）有效地抑制胶质细胞中的mtSOD1，使我们能够解决这一重要问题，并形成这一翻译建议的基础。具体来说，我们将：确定在星形胶质细胞中mtSOD1减少提供治疗益处的临床相关时间框架。在本项目完成后，我们期望能够确定降低胶质细胞中mtSOD1的最佳时间点和最新时间点，从而延缓疾病进展，延长SOD1G93A小鼠的生存期。这项工作将产生重要的见解，揭示减弱ALS异常胶质细胞毒性的最佳治疗时间窗口，为在患者中去除mtSOD1的翻译方法提供基础。

DESCRIPTION (provided by applicant): Amyotrophic lateral sclerosis (ALS) is one of the most common neuromuscular diseases worldwide. It is a devastating motor neuron (MN) disease, resulting in muscle paralysis and ultimately respiratory failure leading to death. There is currently no effective therapy to significantly alter the disease course in humans. 90% of ALS cases are sporadic (SALS), in which no known genetic or environmental cause is known. The remaining 10% of patients have a familial variant of the disease (FALS). Approximately 20% of FALS have mutations within the gene encoding superoxide dismutase 1 (SOD1). For these FALS patients, mutant SOD1 (mtSOD1) is a clear pharmacological target, and it is well established that reduction of mtSOD1 prolongs lifespan in several ALS mouse models. The clinical and pathological presentation of both FALS and SALS is identical, in which striking gliosis, increase proliferation of astrocytes and microglia, occurs accompanied by selective MN cell death. Recent studies using mtSOD1 animal models have shown that non-neuronal cells contribute to disease onset and progression, and evidence for non-cell autonomous motor neuron death has mounted. Indeed, it has been shown that the reduction of mtSOD1 expression in astrocytes by breeding transgenic mice contacting the floxed mtSOD1 with mice expressing Cre from the glial fibrillary acidic protein (GFAP) promoter had significant effects in the disease These crosses showed that disease progression was significantly slowed and the effect on survival was profound. However, an important question remains from these studies: What is the timing for removing mtSOD1 from astrocytes that delays disease progression and extends survival? We believe that it is important to identify the latest time point during disease progression in which the removal of mtSOD1 is still efficacious, as many patients are diagnosed after disease onset. Therefore, it is crucial for therapy development to identify the 'point of no return' in ALS. We recently reported a very efficient method to target glia, predominantly astrocytes, in the adult Central Nervous System via systemic delivery of a vector based on Adeno-associated virus serotype 9 (AAV9).This discovery will enable our laboratory to efficiently suppress mtSOD1 in glia at various time points during disease (onset, early and late phase) in ALS mouse models allowing us to address this important question and forming the basis of this translational proposal. Specifically, we will: Determine the clinically relevant time frames when reduction of mtSOD1 in astrocytes provides therapeutic benefit. At the completion of this project, it is our expectation that we will have identified the optimal as well as the latest time points for decreasing mtSOD1 in glia that results in delayed disease progression and extends survival of SOD1G93A mice. This work will generate important insights to unravel the optimal therapeutic time window for attenuating aberrant glial cell toxicity in ALS providing the basis for a translational approach to remove mtSOD1 in patients.