Neuroimmune interactions in Rett syndrome

神经免疫相互作用和表观遗传机制作用于遗传和环境风险的界面 这些因素决定了常见和罕见脑部疾病的严重程度和进展。一个最好的例子 Rett综合征是一种X连锁显性神经发育障碍， MECP2的突变。Rett综合征在两个水平上是表观遗传的：首先是X染色体对MECP 2的调节， 染色体失活，其次是因为MECP2编码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突变是杂合子，主要是生殖系突变。 父亲的从头事件。Rett婴儿出生时表面上是正常的，然后经历一个回归， 认知和运动功能。Rett综合征的小鼠模型也概括了 出现可检测的神经症状和运动缺陷。虽然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全系统免疫， 线粒体和代谢表现，可能是继发于因果突变的破坏， 神经元内稳态雷特场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特征与免疫系统的 大脑内外的反应。我们建议研究临界时间的分子特征 基于人类突变的新型Rett综合征小鼠模型的神经免疫发病机制。 皮质中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神经元 神经元将与1）来自海马和下丘脑的单细胞转录组学整合，2） 免疫功能障碍的测量，和3）代谢物和肠道微生物群谱。第一个目标是 目的将是表征在症状进展的背景下神经免疫相互作用的时间过程 Rett综合征第一个目标的结果将揭示免疫反应的分子动力学 加剧神经元功能障碍，反之亦然。在第二个目标中，我们建议调节小胶质细胞， 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小鼠模型中。将在症状前小鼠中进行LPS注射以激活小胶质细胞， 为了验证“二次打击”激活的小胶质细胞会增加中风发作的严重性和速度的假设， Rett综合征模型中的神经和运动症状。作为一个相互的实验，小胶质细胞将 在使用药物PLX 5622的青春期小鼠中耗尽，并且在短期药物给药后允许补充 治疗或在成年期持续耗尽，以测试小胶质细胞是关键的假设， 症状进展的介质。从这些实验中，我们期望得到一个完整的分子时间 事件的过程解释了Mecp2突变如何与大脑和外周的免疫反应相互作用。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程度， 是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.