Network modulation to improve gene therapy in CLN3 disease

项目总结 三分之二的溶酶体储存障碍(LSD)会影响大脑，但大多数LSD治疗并没有改善 中枢神经系统(CNS)症状。几项脑定向基因疗法的试验都没有显示出 临床受益，尽管恢复了中枢神经系统的蛋白质表达。在研究对象中，结果尤其糟糕 已经发展出神经功能缺陷，这表明仅有表达的挽救可能不足以纠正 一旦疾病的神经元回路被建立，它就会发挥作用。 CLN3病是一种典型的LSD，也是儿童痴呆症最常见的原因，患者发生 失明、癫痫和痴呆症。已经开发了几种CLN3病小鼠模型。虽然所有人 简而言之，在患者中看到的存储积累，行为表型是微妙的和可变的。至 克服了这一限制，我们在网络级别的电生理学上确定了健壮的、可重复的表型 研究了两个CLN3模型，一个是基因敲除模型，另一个是人类突变模型。与组织病理学不同，生理学 措施直接反映功能，因此，可能是一个更好的读数为治疗发展。 我们的研究表明，传统上被认为是一种退行性疾病的CLN3疾病，很早就中断了 神经发育，特别是在海马体，这是CLN3疾病的一个脆弱区域。关于体外电压 敏感染料成像(VSDI)和活体脑电(EEG)记录，Cln3-/-小鼠减少 海马齿状回(DG)的兴奋性、较快的脑电背景活动和海马区的丧失 尖锐的波纹，编码新记忆的振荡。此外，DG神经发生被上调，可能是因为 一种代偿机制，在疾病早期(2个月)而不是晚(6个月)。类似的网络变化也出现在其他 神经退行性变的模型，包括阿尔茨海默病(AD)。内嗅神经的脑深部刺激 皮质已被证明可以改善阿尔茨海默病小鼠模型的结果。 在此之前，我们发现在P0非常早的Cln3基因替换纠正了Cln3中的网络动态 基因敲除老鼠。我们的中心假设是，异常的神经元回路发育将限制 当基因替换将改善网络生理学时的时间窗，即‘治疗窗’ CLN3病。此外，我们预测，改变关键回路的活动可能会改变治疗 基因治疗的窗口和疗效。我们的具体目标是：1)确定齿状回发育异常 在CLN3病小鼠中，2)通过以下方法确定纠正海马区电路动力学的治疗窗口 基因替换，以及3)测试修改内嗅皮层活动是否改变电路缺陷和对基因的反应 心理治疗。在这种情况下，我们将以CLN3疾病为代表，探讨LSD与 网络活动和对基因治疗的反应。我们的长期目标是开发网络导向疗法 当与基因替代相结合时，可以改善LSD的预后。

PROJECT SUMMARY Two-thirds of lysosomal storage disorders (LSD) affect the brain, yet most LSD treatments do not improve central nervous system (CNS) symptoms. Several trials of brain-directed gene therapy have failed to show clinical benefit despite restoring protein expression in the CNS. Outcomes are especially poor in subjects who have developed neurologic deficits, suggesting rescue of expression alone may be insufficient to correct function once diseased neuronal circuits are established. In CLN3 Disease, a representative LSD and the most common cause of pediatric dementia, patients develop blindness, seizures, and dementia. Several CLN3 disease mouse models have been developed. While all recapitulate the storage accumulation seen in patients, behavioral phenotypes are subtle and variable. To overcome this limitation, we identified robust, reproducible phenotypes on network-level electrophysiology studies in two CLN3 models, a knockout and a human mutation model. Unlike histopathology, physiologic measures directly reflect function and, therefore, may be a better readout for therapy development. Our work suggests CLN3 disease, traditionally considered a degenerative disorder, disrupts early neurodevelopment, especially in the hippocampus, a vulnerable region in CLN3 disease. On in vitro voltage sensitive dye imaging (VSDI) and in vivo electroencephalogram (EEG) recordings, Cln3-/- mice have decreased excitability of the hippocampal dentate gyrus (DG), faster EEG background activity, and loss of hippocampal sharp wave ripples, oscillations that encode new memories. Also, DG neurogenesis is upregulated, perhaps as a compensatory mechanism, early (2mo) but not later (6mo) in disease. Similar network changes arise in other models of neurodegeneration including Alzheimer’s disease (AD). Deep brain stimulation of the entorhinal cortex has been shown to improve outcomes in mouse models of AD. Previously, we found that very early Cln3 gene replacement at p0 corrects network dynamics in a Cln3 knockout mouse. Our central hypothesis is that abnormal neuronal circuit development will limit the window of time, i.e. ‘therapeutic window’, when gene replacement will improve network physiology in CLN3 disease. Furthermore, we predict that altering activity in a key circuit could modify the therapeutic window and efficacy of gene therapy. Our Specific Aims are to: 1) define abnormal dentate gyrus development in CLN3 disease mice, 2) determine the therapeutic window for correction of hippocampal circuit dynamics by gene replacement, and 3) test if modifying entorhinal cortex activity alters circuit defects and response to gene therapy. In this way we will use CLN3 Disease as a representative LSD, to explore the relationship between network activity and response to gene therapy. Our long-term goal is to develop network-directed therapies that, when combined with gene replacement, improve outcomes in LSDs.