Microglial Phagocytosis of Dendritic Spines in Veterans with Schizophrenia

精神分裂症退伍军人的小胶质细胞吞噬树突棘

• 批准号: 10619593
• 负责人: DAVID W VOLK
• 金额: --
• 依托单位: VETERANS HEALTH ADMINISTRATION
• 依托单位国家: 美国
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-04-01 至 2025-03-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10619593
• 关键词: 3-Dimensional; Affect; Antipsychotic Agents; Area; Binding; CX3CR1 gene; Cd68; Cell Count; Cell surface; Chronic; Cognitive deficits; Complement; Complement Receptor; Dendritic Spines; Disease; Elements; Functional disorder; General Population; Genes; Genetic; High Prevalence; Immune; Immunofluorescence Microscopy; Impaired cognition; Impairment; Individual; Label; Lasers; Ligand Binding; Link; Macrophage-1 Antigen; Mediating; Mediator; Membrane; Mental disorders; Messenger RNA; Microdissection; Microglia; Molecular; Molecular Target; Monkeys; Morphology; Myeloid Cells; Nature; Phagocytes; Phagocytosis; Phagocytosis Inhibition; Play; Positron-Emission Tomography; Prefrontal Cortex; Process; Purinoceptor; Reporting; Risk Factors; Role; Sampling; Schizophrenia; Study Subject; Synapses; TYROBP gene; Territoriality; Testing; Transcript; Unemployment; Variant; Vertebral column; Veterans; brain cell; cognitive function; cognitive process; density; disability; genome wide association study; glial activation; hippocampal pyramidal neuron; improved; inhibitor; mortality; novel; receptor; remediation; repaired; selective expression

Schizophrenia (SZ) is a severe and chronic psychiatric illness characterized by cognitive dysfunction. SZ has a higher prevalence in Veterans and is associated with increased disability and mortality in Veterans. Genome-wide association studies have identified variants of microglia-related genes as risk factors for SZ. How such genetic factors might be manifest as molecular alterations in microglia in SZ is not clear. Understanding microglial function in SZ is important because microglia are involved in the phagocytosis of dendritic spines on pyramidal neurons. Spines, which receive most of the excitatory input to pyramidal neurons, are critical mediators of the cognitive functions that are impaired in SZ. Spine density is lower principally in deep layer 3 of the prefrontal cortex (PFC) in SZ, and PFC layer 3 has been reported to subserve cognitive processes affected in the illness. Thus, we hypothesize that the dendritic spine deficit in deep layer 3 of the PFC in SZ is due to increased phagocytosis of spines by microglia. Testing our central hypothesis requires answering the following questions. First, do microglia in SZ show a profile of critical molecular features that enables increased spine phagocytosis (Aim 1)? We will quantify levels of both newly discovered and established transcripts that are selectively expressed by microglia and are involved in phagocytosis of dendritic spines (or the inhibition of phagocytosis) in laser microdissected deep layer 3 of PFC area 46 in SZ (n=32; 50% Veterans) and unaffected comparison subjects (n=32; 50% Veterans). We predict that SZ subjects have higher mRNA levels of microglia-specific markers that promote spine phagocytosis and lower mRNA levels of markers that inhibit phagocytosis. We will also use a novel quadruple-label RNAscope approach to quantify transcript levels in individual microglia to determine if all, or only some, microglia show molecular alterations in SZ. We predict that transcripts promoting spine phagocytosis are elevated in only a subset of microglia in SZ, which could account for findings that spine density is ~20% lower and most prominent in deep layer 3 of the PFC in SZ. Second, are spine deficits in deep layer 3 of the PFC in SZ associated with molecular and morphological features that indicate increased spine phagocytosis in nearby individual microglia (Aim 2)? Microglia and their associated processes have their own individual territorial organization, permitting the quantification of dendritic spines located exclusively within the territory of an individual microglia. Therefore, in the same subjects studied in Aim 1, we will use a quintuple-label confocal immunofluorescence microscopy approach to quantify the density of spines identified using two markers within 3D sampling regions constrained to the territorial domain of individual microglia. We will also quantify levels of CR3, which is involved in complement-mediated microglial phagocytosis of spines, and CD68, a phagocytic marker, and microglial process volume and complexity, which are associated with levels of spine phagocytosis, in individual microglia. We predict that spine density is inversely correlated with CR3 and CD68 levels and microglial process volume and complexity in nearby individual microglia in SZ subjects. Investigating the relationship between microglia-mediated spine phagocytosis and spine deficits in SZ will enable the pursuit of novel molecular targets for microglial inhibitors that may remediate dendritic spine deficits and repair synaptic connectivity, and possibly cognitive dysfunction, in Veterans with SZ.

精神分裂症（SZ）是一种以认知功能障碍为特征的严重慢性精神疾病。SZ 在退伍军人中的患病率较高，并与退伍军人的残疾和死亡率增加有关。 全基因组关联研究已经确定小胶质细胞相关基因的变异是SZ的危险因素。 这些遗传因素如何表现为SZ小胶质细胞的分子改变尚不清楚。 了解SZ中小胶质细胞的功能是重要的，因为小胶质细胞参与了 锥体神经元上的树突棘。棘，接受大部分的兴奋性输入到锥体 神经元是SZ中受损的认知功能的关键介质。脊柱密度较低 主要位于SZ的前额叶皮层（PFC）的深层3，PFC 3层已被报道有助于 认知过程受到疾病的影响。因此，我们假设，树突棘缺陷，在深 SZ中PFC的第3层是由于小胶质细胞对棘的吞噬作用增加。 检验我们的中心假设需要回答以下问题。首先，深圳的小胶质细胞是否显示出 关键的分子特征，使棘吞噬作用增加（目标1）？我们将量化 新发现的和建立的转录本，选择性地由小胶质细胞表达， 在激光显微切割的深部组织中，参与树突棘的吞噬作用（或抑制吞噬作用） SZ（n=32; 50%退伍军人）和未受影响的对照受试者（n=32; 50% 退伍军人）。我们预测SZ受试者有更高的小胶质细胞特异性标志物的mRNA水平， 棘吞噬作用和降低抑制吞噬作用的标记物的mRNA水平。我们也会用一本小说 四重标记RNAscope方法来定量单个小胶质细胞中的转录水平，以确定是否所有或 只有一些小胶质细胞在SZ中显示分子改变。我们预测促进脊柱的转录本 在SZ中，吞噬作用仅在小胶质细胞亚群中升高，这可以解释脊柱 密度低约20%，并且在SZ中PFC的深层3中最显著。 第二，SZ PFC深层3的棘缺陷是否与分子和形态学有关？ 特征，表明在附近的单个小胶质细胞（目标2）增加棘吞噬？小胶质细胞及其 相关的过程有自己的区域组织，允许树突状细胞的量化。 棘只位于一个小胶质细胞的领土内。因此，在研究的同一主题中， 在目标1中，我们将使用五标记共聚焦免疫荧光显微镜方法来定量 使用限制于领土域的3D采样区域内的两个标记识别的棘的密度 单个小胶质细胞。我们还将定量CR 3的水平，CR 3参与补体介导的 棘的小胶质细胞吞噬作用，和CD 68，一种吞噬标志物，和小胶质细胞突起体积， 复杂性，这与棘吞噬作用的水平，在个别小胶质细胞。我们预测 棘密度与CR 3和CD 68水平以及小胶质细胞突起体积和复杂性呈负相关 在SZ受试者附近的个体小胶质细胞中。 小胶质细胞介导的脊髓吞噬功能与SZ脊髓损伤关系的研究 这将使小胶质细胞抑制剂的新的分子靶点的追求，可以修复树突棘 患有SZ的退伍军人的突触连接缺陷和修复，以及可能的认知功能障碍。