Differential transcriptional profiles identify microglial- and macrophage-specific gene markers expressed during virus-induced neuroinflammation
Differential transcriptional profiles identify microglial- and macrophage-specific gene markers expressed during virus-induced neuroinflammation
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DOI：
10.1186/s12974-019-1545-x
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发表时间：
2019-07-20
影响因子：
9.3
通讯作者：
Fujinami, Robert S.
中科院分区：
文献类型：
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作者：
DePaula-Silva, Ana Beatriz;Gorbea, Carlos;Fujinami, Robert S.
在健康的中枢神经系统（CNS）中，小胶质细胞处于稳态状态，外周巨噬细胞不存在于大脑中。小胶质细胞在维持中枢神经系统稳态和作为感染和炎症的第一反应者中发挥关键作用，外周巨噬细胞在神经炎症期间浸润中枢神经系统。由于它们的起源和功能不同，区分这些细胞群对于理解神经炎性疾病至关重要。在中枢神经系统非感染性条件下，通过比较小胶质细胞和外周巨噬细胞或体外骨髓巨噬细胞的基因谱，发现了有价值的小胶质细胞特异性基因。然而，在病毒诱导的神经炎症期间从中枢神经系统中分离出浸润中枢神经系统的巨噬细胞和小胶质细胞，比较它们之间基因谱的研究缺乏。方法采用流式细胞术分离小鼠脑脊髓炎病毒感染C57BL/6J小鼠脑内的小胶质细胞和浸润性巨噬细胞，采用RNA-Seq和qPCR验证，检测这些细胞的差异转录谱。我们利用定义亚细胞定位的原始文献来确定从转录谱中提取的特定蛋白质是否在细胞表面表达。流式细胞术检测骨髓细胞上表达的触发受体1 （TREM-1）蛋白的表面表达和细胞特异性。我们还研究了这些分离的小胶质细胞和浸润性巨噬细胞的转录谱中的免疫反应基因谱。结果我们已经鉴定并验证了新的小胶质细胞和巨噬细胞特异性基因，编码细胞表面蛋白，在神经炎症高峰期表达。证实TREM-1蛋白在神经炎症高峰期通过浸润巨噬细胞而非小胶质细胞表达。我们还通过检查嗜神经病毒感染期间小胶质细胞和浸润性巨噬细胞的免疫反应基因谱，确定了独特和冗余的免疫功能。结论神经炎症期间细胞表面特异性基因的差异表达可能用于区分小胶质细胞和巨噬细胞，并为进一步利用靶向和操纵神经炎症期间的特异性细胞反应提供资源。
BackgroundIn the healthy central nervous system (CNS), microglia are found in a homeostatic state and peripheral macrophages are absent from the brain. Microglia play key roles in maintaining CNS homeostasis and acting as first responders to infection and inflammation, and peripheral macrophages infiltrate the CNS during neuroinflammation. Due to their distinct origins and functions, discrimination between these cell populations is essential to the comprehension of neuroinflammatory disorders. Studies comparing the gene profiles of microglia and peripheral macrophages, or macrophages in vitro-derived from bone marrow, under non-infectious conditions of the CNS, have revealed valuable microglial-specific genes. However, studies comparing gene profiles between CNS-infiltrating macrophages and microglia, when both are isolated from the CNS during viral-induced neuroinflammation, are lacking.MethodsWe isolated, via flow cytometry, microglia and infiltrating macrophages from the brains of Theiler's murine encephalomyelitis virus-infected C57BL/6J mice and used RNA-Seq, followed by validation with qPCR, to examine the differential transcriptional profiles of these cells. We utilized primary literature defining subcellular localization to determine whether or not particular proteins extracted from the transcriptional profiles were expressed at the cell surface. The surface expression and cellular specificity of triggering receptor expressed on myeloid cells 1 (TREM-1) protein were examined via flow cytometry. We also examined the immune response gene profile within the transcriptional profiles of these isolated microglia and infiltrating macrophages.ResultsWe have identified and validated new microglial- and macrophage-specific genes, encoding cell surface proteins, expressed at the peak of neuroinflammation. TREM-1 protein was confirmed to be expressed by infiltrating macrophages, not microglia, at the peak of neuroinflammation. We also identified both unique and redundant immune functions, through examination of the immune response gene profiles, of microglia and infiltrating macrophages during neurotropic viral infection.ConclusionsThe differential expression of cell surface-specific genes during neuroinflammation can potentially be used to discriminate between microglia and macrophages as well as provide a resource that can be further utilized to target and manipulate specific cell responses during neuroinflammation.