Neuroimmunological insights into brain development and dysfunction: an integrative approach focused on microglial dynamics

项目摘要： 神经发育障碍，如自闭症和智力残疾，影响14%的美国儿童， 超过五千万人。治疗这些疾病的药物疗法实际上是非- 在很大程度上是由于我们对神经回路布线缺陷的理解有限，这些缺陷是其多样性的基础。 和细微的症状虽然已经确定神经发育障碍是通过 遗传（自然）和环境因素（养育）的复杂相互作用，大多数对这些因素的研究 条件的重点是特定的基因突变潜在的罕见子集的疾病，离开 环境因素，影响更广泛的这些条件知之甚少。缓解 为了尽可能多的人遭受痛苦，我们将通过定义 环境因素加剧了神经发育障碍。我们的方法是基于安装 临床和实验证据表明，免疫系统和大脑之间的相互作用受损， 驱动神经病理学，这是一个意想不到的发现，因为免疫和神经系统是经典的 被认为是不同的生物学领域。这项工作的核心假设是， 一种称为小胶质细胞的专门的大脑驻留免疫细胞在协调晚期阶段中起着关键作用。 在神经病理学状态下被认为出错的电路发展：感觉经验依赖性 发育中突触的精细化。如果是这样，小胶质细胞功能的破坏依赖于经验。 精细化可能是神经发育障碍的核心特征，使得小胶质细胞成为神经发育障碍的有希望的靶点。 治疗，特别是因为经验依赖的细化代表了高度可塑性的状态 当大脑可能特别容易接受治疗干预时。利用的独特优势， 作为一个模型系统的小鼠视觉电路，我们将合并小胶质细胞和突触的双光子成像 在活的清醒小鼠的大脑中，使用单细胞基因组学和基于CRISPR的筛选来定义 小胶质细胞在经验依赖的细化。同时，我们将利用母体免疫激活小鼠 模型，以确定可能在神经发育过程中被破坏的特定细化机制。 紊乱考虑到男性患自闭症的可能性至少是女性的三倍，我们的工作也将 评估这些小胶质细胞过程如何根据性别而不同。在这项工作中，我们将开发 研究大脑中小胶质细胞的病毒工具。我们的首要目标是为 开发通过恢复健康来治疗神经发育障碍的新药理学策略 小胶质细胞在出生后大脑发育过程中的功能。除了高风险/高回报的性质， 根据建议，该项目特别适合NIH主任的新创新者奖， 概念新奇，有望实现关键技术进步，并有可能缓解重大医疗保健问题， 影响美国和世界的负担。

Project Summary: Neurodevelopmental disorders such as autism and intellectual disability affect 14% of American children and over 50 million people world-wide. Pharmacological therapies for treating these disorders are virtually non- existent in large part due to our limited understanding of the neural circuit wiring deficits that underlie their diverse and nuanced symptoms. While it has been well-established that neurodevelopmental disorders emerge through a complex interplay of genetics (nature) and environmental factors (nurture), the majority of research into these conditions has focused on specific genetic mutations underlying rare subsets of disorders, leaving the environmental factors that affect a much wider array of these conditions poorly understood. To alleviate the suffering of as many individuals as possible, we will address this major gap in knowledge by defining the environmental factors that exacerbate neurodevelopmental dysfunction. Our approach is based upon mounting clinical and experimental evidence that impairments in interactions between the immune system and the brain drive neuropathology, an unexpected finding given that the immune and nervous systems were classically considered to be distinct biological domains. The central hypothesis underlying the proposed work is that a specialized class of brain-resident immune cells called microglia play a critical role in coordinating a late stage of circuit development that is thought to go awry in neuropathological states: the sensory experience-dependent refinement of developing synapses. If so, the disruption of microglial function in experience-dependent refinement may be a core feature of neurodevelopmental disorders rendering microglia a promising target for treatment, particularly because experience-dependent refinement represents a state of heightened plasticity when the brain may be particularly receptive to therapeutic intervention. Harnessing the unique advantages of the visual circuitry of the mouse as a model system, we will merge two-photon imaging of microglia and synapses in the brains of live, awake mice with single-cell genomics and CRISPR-based screens to define the roles of microglia in experience-dependent refinement. In parallel, we will utilize the maternal immune activation mouse model to identify specific mechanisms of refinement that are likely to be disrupted in neurodevelopmental disorders. Given that males are at least three times more likely to have autism than females, our work will also assess how these microglial processes differ depending upon sex. In the course of this work, we will develop much-needed viral tools for studying microglia in the brain. Our overarching goal is to lay the foundation for the development of new pharmacological strategies for treating neurodevelopmental disorders by restoring healthy microglial function during postnatal brain development. In addition to the high-risk/high-reward nature of the proposal, this project is particularly well-suited for the NIH Director’s New Innovator Award based upon conceptual novelty, promise to achieve key technological advances, and potential to alleviate a major healthcare burden affecting the United States and the world.