Neuroimmune interactions in Rett syndrome

神经免疫相互作用和表观遗传机制在遗传和环境风险的界面上起作用 决定常见和罕见脑部疾病的严重程度和进展的因素。一个最好的例子 一种复杂的单基因疾病是Rett综合征，这是一种X连锁的显性神经发育障碍，由 通过MECP2的突变。Rett综合征在两个水平上是表观遗传学的：第一，X对MECP2的调节 第二，因为MECP2编码了一种已知的表观遗传调节因子--甲基CpG 结合蛋白2.Rett综合征女孩的MECP2突变是杂合的，这些突变主要是生殖系的 父性的从头活动。Rett婴儿出生时看起来很正常，然后经历了一次退化 婴儿期晚期的认知和运动功能。Rett综合征的小鼠模型也概括了在 出现可检测到的神经症状和运动障碍。而MeCP2蛋白是最高的 在神经元中表达，人类RETT患者和小鼠模型都表现出系统免疫， 线粒体和代谢表现，很可能是继发性的原因突变的破坏 神经元动态平衡。Rett领域所缺乏的是对分子如何在时间上理解 大脑内不同细胞类型的疾病进展标志与免疫系统相互作用 大脑内外的反应。我们建议研究关键时间的分子特征 基于人类突变的新的Rett综合征小鼠模型的神经免疫发病机制要点。 皮层特定细胞类型的表观基因组学研究，包括小胶质细胞、兴奋性神经元和抑制性细胞 神经元将与1)来自海马和下丘脑的单细胞转录产物整合，2) 免疫功能障碍的测量，以及3)代谢物和肠道微生物区系。第一个的目标是 目的是在症状进展的背景下描述神经免疫相互作用的时间进程 患有雷特综合征。第一个目标的结果将揭示免疫反应的分子动力学 加重神经元功能障碍，反之亦然。在第二个目标中，我们建议先调节小胶质细胞 以直接测试小胶质细胞在症状的时间和严重程度中的作用 在这个Rett老鼠模型中。将在出现症状前的小鼠中注射脂多糖以激活小胶质细胞，从而 为了验证“二次打击”激活的小胶质细胞将增加发病的严重程度和速度的假设 Rett综合征模型中的神经学和运动学症状。作为一项互惠实验，小胶质细胞将 在使用药物PLX5622的青春期小鼠中耗尽，并在短期药物后允许补充 治疗或在成年期持续耗尽，以检验小胶质细胞是关键的假设 症状进展的中介物。从这些实验中，我们期望获得完整的分子时间 解释MeCP2突变如何与大脑和外周免疫反应相互作用的事件过程。我们 还将确定Rett综合征中激活的小胶质细胞是否会加速疾病的严重性，并成为一种 未来临床前研究的重要治疗靶点。

Neuroimmune interactions and epigenetic mechanisms act at the interface of genetic and environmental risk factors that determine the severity and progression of both common and rare brain disorders. A prime example of a complex monogenic disease is Rett syndrome, an X-linked dominant neurodevelopmental disorder caused by mutations in MECP2. Rett syndrome is epigenetic at two levels: first in the regulation of MECP2 by X chromosome inactivation, and second because MECP2 encodes a known epigenetic regulator, methyl CpG binding protein 2. Girls with Rett syndrome are heterozygous for MECP2 mutations that are primarily germ-line paternal de novo events. Rett babies are born apparently normal, and then experience a regression in cognitive and motor functions in late infancy. Mouse models of Rett syndrome also recapitulate the delay in the onset of detectable neurological symptoms and motor deficits. While the MeCP2 protein is most highly expressed in neurons, both human Rett patients and mouse models exhibit system-wide immune, mitochondrial, and metabolic manifestations that are likely secondary to the causal mutation’s disruption of neuronal homeostasis. What is lacking in the Rett field is a temporal understanding of how the molecular signatures of disease progression in distinct cell types within the brain interact with the immune system’s responses inside and outside of the brain. We propose to investigate the molecular signatures of critical time points of neuroimmune pathogenesis in a novel Rett syndrome mouse model based on a human mutation. Epigenomic investigation of specific cell types in cortex, including microglia, excitatory neurons, and inhibitory neurons will be integrated with 1) single cell transcriptomics from hippocampus and hypothalamus, 2) measurements of immune dysfunction, and 3) metabolite and gut microbiota profiles. The objective of the first aim will be to characterize the time course of neuroimmune interactions in the context of symptom progression in Rett syndrome. Results from the first aim will reveal the molecular dynamics of how immune responses exacerbate neuronal dysfunction and vice versa. In the second aim, we propose to modulate the microglia prior to the onset of disease progression to directly test the role of microglia in the timing and severity of symptoms in this Rett mouse model. LPS injections in pre-symptomatic mice will be performed to activate microglia so as to test the hypothesis that microglia activated by a “second hit” will increase the severity and speed of onset of neurologic and motor symptoms in the Rett syndrome model. As a reciprocal experiment, microglia will be depleted in adolescent mice using the drug PLX5622 and either allowed to replenish after short term drug treatment or continuously depleted through adulthood to test the hypothesis that microglia are critical mediators of symptom progression. From these experiments, we expect to obtain an integrated molecular time course of events explaining how Mecp2 mutation interacts with immune responses in brain and periphery. We will also determine if activated microglia in Rett syndrome may accelerate the disease severity and be an important therapeutic target for future pre-clinical investigations.