Cell-specific molecular mechanisms underlying brain pathology in ASD

 描述(申请人提供)：大多数自闭症谱系障碍(ASD)患者的大脑结构和功能的改变在生命早期就开始了，但它们在发育过程中继续变化，并在一生中变化。这些与年龄相关的差异是特定地区的，在较高级别的认知、社交和情绪大脑区域最为明显。我们的纵向磁共振成像(MRI)研究表明，在五个脑叶中，ASD儿童的颞叶皮质发育最明显地偏离了典型发育，从2岁开始。虽然这种现象在儿童时期最为明显，但我们发现，细胞的变化在整个一生中都在继续和变化。在ASD成人中，颞叶皮质和皮质下区域的神经元数量减少，ASD大脑的一部分具有过度的小胶质细胞激活，表明大脑中存在异常的免疫反应。这些差异是在童年时期存在的，还是退行性细胞丢失的结果，仍然是一个谜。很明显，在ASD大脑中发现的结构和细胞变化因地区和年龄而异，并且是细胞特有的。ASD大脑的异质性和不断变化的病理学为将生物学研究转化为生物疗法的开发提供了复杂的因素，以改变大脑的发育和功能。靶向生物治疗的发展需要了解与试图改变的发病机制直接相关的分子签名。然而，与典型发育中的大脑相比，ASD中与区域、年龄和细胞病理相关的分子转录组改变仍然完全未知和未被探索。事实上，到目前为止，还没有研究集中在ASD患者任何年龄段的任何大脑区域的细胞特异性基因模式。使用核磁共振成像和血液分子研究对大量活着的个体进行研究，可以为我们提供有关全球大脑变化的替代信息。然而，为了揭示特定的细胞病理和潜在的分子转录改变之间的直接联系，有必要从ASD和未受影响的人的身体上提取人脑组织。为了开始解决这一关键的知识差距，我们提议进行一项初步研究，以评估这种新的研究途径的可行性：1)通过对关键的“社会脑”区域--颞上沟(STS)中神经元和小胶质细胞的数量和大小的体视学测量来表征细胞的变化，并将结果与邻近的初级听觉皮质(PAC)进行对比。2)使用激光捕获显微镜和细胞悬浮技术分离神经元和小胶质细胞进行RNA测序，以确定这些区域基因表达的区域和细胞特异性变化。总而言之，这项研究的首要目标是结合特定脑区和细胞类型的细胞和转录改变的标记，描绘ASD大脑异常发育背后的分子机制的详细图景，从而识别可以在更大人群中研究并针对整个生命周期进行干预的分子特征。

 DESCRIPTION (provided by applicant): Alterations in brain structure and function in most individuals with an autism spectrum disorder (ASD) begin early in life, however they continue to change during development and vary throughout lifespan. These age-related differences are region-specific and most evident in higher-order cognitive, social and emotional brain regions. Our longitudinal magnetic resonance imaging (MRI) studies suggest that, of the five lobes, temporal cortical growth in children with ASD deviates most substantially from typical development, beginning at 2 years of life. Although this phenomenon is most evident during childhood, we found that cellular alterations continue and change throughout lifespan. Neuron numbers are reduced in temporal cortical and subcortical regions in ASD adults and a subset of ASD brains has excessive microglial activation, suggesting an aberrant immune response in the brain. Whether these differences exist during childhood or are the result of degenerative cell loss remains a mystery. It is clear though that structural and cellular alterations found in ASD brain vary by region and age, and are cell-specific. The heterogeneity and changing pathology of the ASD brain presents complications for translating biological research to the development of biotheraputics to alter both brain development and function. The development of targeted biological treatments requires an understanding of the molecular signature directly related to the pathogenesis one is attempting to alter. However, molecular transcriptome alterations related to region, age, and cellular pathology in ASD compared to the typically developing brain remains completely unknown and unexplored. In fact, no study to date has focused on cell-specific gene patterns in any brain region at any age in ASD. The study of a large population of live individuals using MRI and molecular studies of blood can provide us with surrogate information on global brain changes. However, postmortem human brain tissue from ASD and unaffected individuals is necessary to uncover the direct link between specific cellular pathology and underlying molecular transcriptomic alterations. To begin to address this critical gap in knowledge, we propose a pilot study to assess the feasibility of this novel avenue of investigation: 1) Characterize cellular alterations with stereological measures of neuronal and microglial cell number and size in superior temporal sulcus (STS), a key "social brain" region, and contrast findings with adjacent primary auditory cortex (PAC). 2) Identify region- and cell-specific alterations in gene expression in these regions using laser capture microscopy and cell suspension techniques to isolate neurons and microglia for RNA-sequencing. In summary, the overarching goal of this research is to combine markers of cellular and transcriptomic alterations in specific brain regions and cell types to paint a detailed picture of the molecular mechanisms that underlie aberrant brain development in ASD, thus identifying molecular signatures that can be investigated in larger populations and targeted for interventions across lifespan.