Chandellier interneurons and the excitation/inhibition balance in the human prefrontal cortex in autism

孤独症患者前额叶皮层Chandellier中间神经元与兴奋/抑制平衡 关于自闭症大脑皮层的病理学知之甚少。我们之前资助的R 01的目标是 格兰特的目标是解开自闭症患者大脑皮层的病理学。具体来说，我们建议 发现哪些细胞类型（如果有的话）在人类自闭症患者的大脑皮层中发生了改变。我们量化的 在人的每一层内，锥体神经元、中间神经元的特定亚型和神经胶质细胞的数量 颞叶和前额叶皮层的变化我们确定了锥体神经元和神经胶质细胞的数量 在自闭症病例的颞叶大脑皮层中， 并在几篇研究文章中发表了我们的结果（Camacho等人，2014; Kim等人，2015）。但我们 发现前额叶皮层中一种特定的中间神经元亚型的数量减少 在自闭症病例中，小清蛋白（PV）+ Chandellier细胞（Hashemi等，2016）。Chandellier（Ch）细胞是 皮层中的一个主要中间神经元，具有直接与锥体神经元的起始段形成突触的轴突 轴突，创造一个突出的结构称为“墨盒”。因此，Ch细胞是主要的中间神经元， 调节兴奋性投射神经元最终输出的亚型。因此，损失的一小部分 Ch细胞可能严重损害锥体细胞和整个大脑皮层的功能。事实上，变化 在Ch细胞中，先前已经报道了在神经系统疾病中的盒/结和/或功能，例如 精神分裂症和癫痫。基于我们的发现，我们建议通过以下方式来定义Ch细胞在自闭症中的作用： 解开它们的形态和连接特性 我们假设，我们在自闭症患者大脑皮层中发现的PV+ Ch细胞数量减少， Ch细胞盒的数量减少和每个盒的突触扣的数量减少， 随之而来的是锥体神经元轴突起始段上Ch对称突触的丧失，以及 最终损害皮质投射神经元的功能。我们还假设， 每盒GABA和GABA相关蛋白的量，以及锥体轴突中GABRAα2受体的量 初始段。这种抑制性突触结构的减少会引起皮层突触的过度兴奋。 自闭症的神经回路此外，我们假设在自闭症中， 患者症状的严重程度和Ch细胞的数量。 我们将确定Ch细胞盒（Aim 1）的数量和长度是否有变化， Ch药筒中GABA能系统的改变（目的2），如果轴- 自闭症死后脑的前额叶皮层（BA 9，BA 45，BA 46）中的轴突突触（Aim 3）。我们将 免疫组化标记盒和GABA相关蛋白，高尔基体染色标记Ch细胞，并分析 用三维电子显微镜观察突触结构。我们将使用Stereoinvestigator，Neurolucida， Image J，FIB/SEM EM和高通量3D重建。我们将从自闭症患者中获得的数据 组（目标1-3）具有特定症状和其他患者特征。 对自闭症大脑皮层中GABA系统的元素进行全面的量化， 将自闭症研究领域推向一个新的方向。该项目将提供一个全面的 了解GABA能系统在人类大脑皮层自闭症中的作用，并将产生很大的影响 致力于为自闭症患者提供新型治疗的转化研究。 !

Chandellier interneurons and the excitation/inhibition balance in the human prefrontal cortex in autism Little is known about the pathology of the cerebral cortex in autism. The goal of our previously funded R01 grant was to unravel the pathology of the cerebral cortex in patients with autism. Specifically, we proposed to discover which cell type(s), if any, are altered in the cerebral cortex of human autistic cases. We quantified the number of pyramidal neurons, specific subtypes of interneurons, and glial cells, within each layer of the human temporal and prefrontal cortex in autism. We determined that the number of pyramidal neurons and glial cells in the temporal cerebral cortex of autistic cases did not differ from that in typically developing control cases, and published our results in several research articles (Camacho et al., 2014; Kim et al., 2015). However, we discovered that there is a decrease in the number of one specific interneuronal subtype in the prefrontal cortex of autistic cases, the parvalbumin (PV)+ Chandellier cell (Hashemi et al., 2016). Chandellier (Ch) cells are the main interneuron in the cortex possessing axons that synapse directly on the initial segment of the pyramidal axon, creating a prominent structure called “cartridge”. Consequently, the Ch cell is the main interneuronal subtype that regulates the final output of excitatory projection neurons. Therefore, the loss of a small number of Ch cells may critically impair function of pyramidal cells and of the cerebral cortex as a whole. Indeed, changes in Ch cells cartridges/boutons and/or function have previously been reported in neurological diseases, such as schizophrenia and epilepsy. Based on our discovery, we propose to define the role of Ch cells in autism by unraveling their morphological and connectional properties. We hypothesize that the decreased number of PV+ Ch cells we discovered in the autistic cortex translates into a decrease in the number of Ch cell cartridges and a decrease in the number of synaptic buttons per cartridge, with the consequent loss of Ch symmetric synapses on the pyramidal neuron axonal initial segment, and ultimately impaired function of cortical projection neurons. We also hypothesize that there is a decreased amount of GABA and GABA related proteins per cartridge, and of GABRAα2 receptors in the pyramidal axonal initial segment. This reduction of inhibitory synapse structure would cause hyperexcitation of cortical synaptic circuits in autism. Additionally, we hypothesize that in autism there is a negative correlation between the severity of the patient' symptoms and the number of Ch cells. We will determine if there is an alteration in the number and length of Ch cell cartridges (Aim1), if there is an alteration in the GABAergic system in Ch cartridges (Aim 2), and if there is an alteration in the number of axo- axonic synapses (Aim 3) in the prefrontal cortex (BA9, BA45, BA46) of the autism postmortem brain. We will label cartridges and GABA related proteins with immunochemistry, Ch cells with Golgi staining, and analyze synapse structure with 3D electronic microscopy. We will analyze data using Stereoinvestigator, Neurolucida, Image J, FIB/SEM EM, and high-throughput 3D reconstruction. We will correlate data obtained for the autistic group (Aim 1-3) with specific symptoms and other patient characteristics. Providing a comprehensive quantification of the elements of the GABA system in the autism cerebral cortex is necessary to move the field of autism research in a new direction. This project will provide a thorough understanding of the GABAergic system in the human cerebral cortex in autism, and will have a great impact on translational research directed towards providing novel treatment for individuals with autism. !