Amyotrophic Lateral Sclerosis: treating the circuit behind the disease

肌萎缩侧索硬化症：治疗疾病背后的回路

• 批准号: MR/Y014901/1
• 负责人: Ilary Allodi
• 金额: $ 111.3万
• 依托单位: University of St Andrews
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2024
• 资助国家: 英国
• 起止时间: 2024 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=MR%2FY014901%2F1
• 关键词: Amyotrophic; Lateral; Sclerosis; treating; circuit

The incurable disease Amyotrophic lateral sclerosis (ALS) is characterized by loss of motor neurons (MNs), which are the nerve cells directly controlling movements since they connect to the muscles in the periphery of the body. So, MNs can be considered the output of the brain; however, they are activated by a complex circuit of nerve cells found in the spinal cord that decodes the information coming from the brain and activates the MNs in a synchronised manner. These decoding neurons (also called interneurons) can either excite or inhibit the MNs depending on which part of the circuit needs to be engaged to perform the desired movement. We recently discovered that, in a mouse model of ALS, a group of inhibitory interneurons loses its connection to the MNs early in disease, and cannot activate them properly anymore. These changes in connectivity can contribute to MNs dysregulation and degeneration. We also saw that loss of connectivity led to symptoms resembling the ones observed in patients, which included changes in the stride and speed of locomotion (Allodi et al 2021, Nature Communication). In a new study (Mora et al 2022), we used an approach which uses viral infection to deliver genes as therapy, called gene therapy. We delivered a gene that naturally stimulates connections between nerve cells, and we increased the levels of this gene specifically in the inhibitory interneurons. This approach allowed us to stabilise the connectivity between the inhibitory interneurons and the MNs, and as a consequence we increased MN survival and ameliorated ALS symptoms in mice. However, to date, our results are obtained from a mouse model carrying the SOD1 mutation known to cause familial ALS, which accounts only for the 2% of the ALS cases. For this reason, we are now planning to broaden our investigations also to other ALS-causing genetic mutations and to clarify if the loss of connectivity between inhibitory interneurons and MNs is a common event in ALS pathology. If this happen to be the case, our new gene therapy could be apply to a wider number of ALS cases in the future. In this project, we will investigate if the inhibitory interneurons are affected in two other mouse models carrying the TDP-43 and the FUS mutations, utilising an approach that allows us to visualise the connections between interneurons and MNs, and to quantify them. This approach was previously established in the lab (Allodi et al 2021, Nature Communication) and will help us identifying the potential loss of connectivity. Secondly, we will investigate if inhibitory interneurons are also affected in sporadic ALS. Thanks to our collaboration with the Bjspebjerg Brain Bank in Denmark, we can analyse post-mortem tissue from 21 donors which were diagnosed with sporadic ALS. Here, inhibitory interneurons will be quantified to elucidate their potential degeneration in sporadic ALS cases. The inhibitory interneurons will be counted instead of their connections, because the level of degeneration in the human post-mortem tissue is high and we expect a lot of the connectivity to be lost. Finally, we will generate an improved gene therapy to deliver the gene that naturally stimulates connectivity in humans. Despite the promising results, our current approach (Mora et al 2022) has translational limitations because uses a genetic strategy not applicable in humans. However, the inhibitory interneurons can be targeted using a DNA sequence that is specific (like a barcode) and conserved in mouse, chimps, and humans. This sequence can be used as an enhancer. The enhancer will target only the specific inhibitory interneurons and force the expression of our treatment in the cells. Importantly, this new gene therapy can be administered by intravenous injection, so it does not require invasive treatments. We hope that this strategy will slow down inhibitory interneurons from losing their connections and MNs from degeneration.

可治疗的肌萎缩性侧索硬化症（ALS）的特征是运动神经元（MNS）的丧失，它们是直接控制运动运动的神经细胞，因为它们连接到了人体外围的肌肉。因此，可以将MN视为大脑的输出。但是，它们被脊髓中的神经细胞的复杂回路激活，该神经细胞的复杂电路将来自大脑的信息解码并以同步方式激活MNS。这些解码神经元（也称为中间神经元）可以激发或抑制MNS，具体取决于需要参与电路的哪一部分以执行所需的运动。我们最近发现，在ALS的小鼠模型中，一组抑制性中间神经元在疾病早期失去了与MNS的联系，并且无法正确激活它们。连通性的这些变化可能导致MNS失调和变性。我们还看到连通性丧失导致症状类似于患者中观察到的症状，其中包括运动的步伐和速度的变化（Allodi等，2021年，自然传播）。在一项新研究（Mora等，2022年）中，我们使用了一种使用病毒感染作为疗法的方法，称为基因治疗。我们传递了一个自然刺激神经细胞之间连接的基因，并在抑制性神经元中特别增加了该基因的水平。这种方法使我们能够稳定抑制性中间神经元与MN之间的连通性，因此我们增加了MN的存活率并改善了小鼠的ALS症状。但是，迄今为止，我们的结果是从携带已知引起家族ALS的SOD1突变的小鼠模型获得的，该模型仅占ALS病例的2％。因此，我们现在计划将我们的研究也扩大到其他引起ALS的基因突变，并阐明抑制性中间神经元和MN之间连通性丧失是否是ALS病理学中的常见事件。如果情况恰好是这种情况，我们的新基因疗法将来可能适用于更多的ALS病例。在该项目中，我们将研究抑制性中间神经元是否在携带TDP-43和FUS突变的其他两个小鼠模型中受到影响，并利用一种方法使我们能够可视化中间神经元与MN之间的连接并量化它们。这种方法先前是在实验室（Allodi等2021，自然传播）中建立的，将有助于我们确定连通性的潜在丧失。其次，我们将研究抑制性神经元是否也受到零星ALS的影响。由于我们与丹麦的BJSpebjerg脑库的合作，我们可以分析21个被诊断为零星ALS的捐助者的验尸组织。在这里，将量化抑制性神经元以阐明其在零星ALS病例中的潜在变性。抑制性中间神经元将被计数而不是它们的连接，因为人验尸组织中的变性水平很高，我们预计会丢失很多连接性。最后，我们将产生改进的基因疗法，以提供自然刺激人类连通性的基因。尽管结果有令人鼓舞，但我们当前的方法（Mora等，2022）具有翻译局限性，因为使用了不适用于人类的遗传策略。但是，可以使用特定的DNA序列（如条形码）和小鼠，黑猩猩和人类保守的DNA序列来靶向抑制性中间神经元。该序列可以用作增强子。增强子将仅靶向特定的抑制性中间神经元，并迫使我们在细胞中治疗的表达。重要的是，这种新的基因疗法可以通过静脉注射来进行，因此不需要侵入性治疗。我们希望这种策略将减慢抑制性中间神经元因退化而失去其连接和MN的抑制性中间神经元。