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: 10455417
• 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/10455417
• 关键词: 3-Dimensional; Affect; Antipsychotic Agents; Area; Binding; CX3CR1 gene; Cell Count; Cell surface; Chronic; Cognitive; 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; Life; Ligand Binding; Link; Macrophage-1 Antigen; Mediating; Mediator of activation protein; 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; hippocampal pyramidal neuron; improved; inhibitor; mortality; novel; receptor; 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）是一种严重的慢性精神疾病，以认知功能障碍为特征。深圳 在退伍军人中患病率较高，并与退伍军人残疾和死亡率增加有关。 全基因组关联研究已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深圳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很重要，因为小胶质细胞参与吞噬 锥体神经元上的树突棘。脊柱，接收锥体的大部分兴奋输入 神经元是 SZ 中认知功能受损的关键介质。脊柱密度较低 主要存在于深圳前额皮质 (PFC) 的深层 3 中，据报道，PFC 层 3 有助于促进 疾病影响认知过程。因此，我们假设深部树突棘缺陷 SZ 中 PFC 第 3 层是由于小胶质细胞对棘的吞噬作用增加所致。 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表现出 能够增强脊柱吞噬作用的关键分子特征概况（目标 1）？我们将量化水平 新发现和建立的转录本均由小胶质细胞选择性表达， 参与激光显微切割深部树突棘的吞噬作用（或吞噬作用的抑制） 深圳 PFC 区域 46 的第 3 层（n=32；50% 退伍军人）和未受影响的比较对象（n=32；50%） 退伍军人）。我们预测 SZ 受试者的小胶质细胞特异性标记物的 mRNA 水平较高，这些标记物可促进 脊柱吞噬作用和抑制吞噬作用的标记物的 mRNA 水平降低。我们也会用小说 四标记 RNAscope 方法可量化单个小胶质细胞的转录水平，以确定是否全部或 只有一些小胶质细胞在 SZ 中表现出分子改变。我们预测转录本促进脊柱 吞噬作用仅在 SZ 的一小部分小胶质细胞中升高，这可以解释脊柱的发现 密度降低约 20%，并且在 SZ 的 PFC 深层 3 中最为突出。 其次，SZ PFC 深层 3 的脊柱缺陷是否与分子和形态学相关？ 表明附近单个小胶质细胞脊柱吞噬作用增加的特征（目标 2）？小胶质细胞及其 相关过程有自己单独的区域组织，允许对树突进行量化 刺完全位于单个小胶质细胞的范围内。因此，在相同的研究对象中 在目标 1 中，我们将使用五重标记共聚焦免疫荧光显微镜方法来量化 使用限制在领土范围内的 3D 采样区域内的两个标记识别的刺密度 单个小胶质细胞。我们还将量化 CR3 的水平，CR3 参与补体介导的 小胶质细胞对棘的吞噬作用、CD68（一种吞噬细胞标记物）以及小胶质细胞过程体积和 复杂性，与单个小胶质细胞中脊柱吞噬作用的水平有关。我们预测 棘密度与 CR3 和 CD68 水平以及小胶质细胞过程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。 研究 SZ 中小胶质细胞介导的脊柱吞噬作用与脊柱缺陷之间的关系 将有助于寻找可修复树突棘的小胶质细胞抑制剂的新分子靶点 患有精神分裂症的退伍军人的缺陷并修复突触连接，以及可能的认知功能障碍。