Targeted neuromodulation strategies to delay hypoglossal motoneuron death and preserve tongue strength, function, and structure in a mouse model of ALS

项目摘要 肌萎缩侧索硬化症（ALS）最严重的后果之一是吞咽障碍 （吞咽困难），其与显著的发病率、抑郁/社会隔离和早期死亡率相关。从 从神经学的角度来看，ALS中的吞咽困难归因于由以下引起的进行性舌无力： 脑干舌下神经元及其支配舌的轴突（舌下神经）变性 肌肉.进行性舌无力和萎缩最终使几乎所有ALS患者无法进食， 自然饮水;相反，它们必须依靠喂食管生存。尽管多次危及生命 ALS吞咽困难的后果，目前的治疗，包括FDA批准的药物利鲁唑和 依达拉奉对吞咽功能无有益影响。因此，临床上迫切需要识别 针对吞咽困难的潜在病理生理学的有效治疗解决方案，以保护吞咽 功能，并通过代理，显着延长生存期和改善ALS患者的生活质量。 在这个项目中，为了满足这种临床需求，我们将利用ALS的翻译小鼠模型， 吞咽困难，探索光遗传学刺激（opto-stim）作为靶向舌的治疗策略。的 opto-stim治疗是一种基于基因治疗的方法，已被证明可以促进神经元存活， 生长和神经系统损伤中的肌肉神经再支配。在我们的方法中，我们将使用opto-stim选择性地 “刺激”舌下神经元，引起小鼠必须克服的舌肌收缩/阻力， 当自愿从水龙头喝水时，舌头充分伸出。我们假设这个政权， 协同整合光遗传学和舌头运动训练的好处，有可能预防 或减缓舌下神经退化和相关的舌无力的进展。 为了探讨光刺激治疗的效果，我们的项目分为两个目标。在目标1中，我们将应用 在ALS小鼠中每周三次进行高频和低频光刺激治疗，在临床疾病时开始 开始（即，体重开始下降），并评估对舌运动和吞咽的治疗效果 功能（通过荧光透视）和舔力（通过力-舔力计）从疾病发作到末期（即，20%重量 损失）。在目标2中，我们将采用各种组织学评估来量化相应的神经可塑性。 舌下神经核神经元、舌下神经和舌肌对每种刺激的反应变化 神经调节策略以建立临床病理相关性。我们的研究结果将提供深入了解 ALS中基于光遗传学的治疗策略的治疗效果和机制。光遗传学一直是 获得越来越显著的翻译潜力，并且可能对晚期ALS特别有益。 不能参加替代治疗方案但仍可能对治疗有反应的患者。

Project Summary One of the most debilitating consequences of amyotrophic lateral sclerosis (ALS) is swallowing impairment (dysphagia), which is associated with significant morbidity, depression/social isolation, and early mortality. From a neurological perspective, dysphagia in ALS has been attributed to progressive tongue weakness caused by degeneration of brainstem hypoglossal neurons and their axons (hypoglossal nerve) innervating the tongue muscles. Progressive tongue weakness and atrophy ultimately render nearly all ALS patients unable to eat and drink naturally; instead, they must depend on a feeding tube for survival. Despite the multiple life-threatening consequences of dysphagia in ALS, current therapies, including the FDA-approved drugs riluzole and edaravone, have no beneficial effect on swallowing function. Therefore, there is an urgent clinical need to identify effective therapeutic solutions targeting the underlying pathophysiology of dysphagia to preserve swallowing function, and by proxy, significantly extend survival and improve the quality of life for ALS patients. In this project, to address this clinical need, we will leverage a translational mouse model of ALS with dysphagia to explore optogenetic stimulation (opto-stim) as a therapeutic strategy targeting the tongue. The opto-stim treatment is a gene therapy-based approach that has been shown to promote neuronal survival, nerve growth, and muscle reinnervation in nervous system injury. In our approach, we will use opto-stim to selectively “excite” hypoglossal neurons to cause tongue muscle contraction/resistance that mice must overcome to sufficiently protrude the tongue while voluntarily drinking from a waterspout. We hypothesize that this regime, synergistically integrating the benefits of optogenetics and tongue exercise training, has the potential to prevent or slow down the progression of hypoglossal degeneration and associated tongue weakness. To explore the effects of opto-stim treatment, our project is divided into two aims. In Aim 1, we will apply high- and low-frequency opto-stim treatments three times per week in ALS mice, initiated at clinical disease onset (i.e., start of body weight decline), and assess the treatment effect on tongue motility and swallowing function (via fluoroscopy) and lick force (via force-lickometer) from disease onset to end-stage (i.e., 20% weight loss). In Aim 2, we will employ a variety of histological assessments to quantify the corresponding neuroplastic changes in the hypoglossal nucleus neurons, hypoglossal nerve, and the tongue muscles in response to each neuromodulation strategy to establish clinico-pathological correlations. Our results will provide insight into therapeutic effects and mechanisms of optogenetic-based treatment strategies in ALS. Optogenetics has been gaining increasingly significant translational potential and may be particularly beneficial for advanced-stage ALS patients who cannot participate in alternative treatment programs but may still respond to treatment.