Central nervous system (CNS)-border associated macrophages (BAMs) maintain their steady-state population during adulthood and are not replaced by circulating monocytes under physiological conditions. Their roles in CNS integrity and functions under pathological conditions remain largely unknown. Until recently, BAMs and microglia could not be unequivocally distinguished due to expression of common macrophage markers. We investigated the transcriptional profiles of immunosorted BAMs from rat sham-operated and ischemic brains using RNA sequencing. We found that BAMs express the distinct transcriptional signature than microglia and infiltrating macrophages. The enrichment of functional groups associated with the cell cycle in CD163+ cells isolated 3 days after the ischemic injury indicates the proliferative capacity of these cells. The increased number of CD163+ cells 3 days post-ischemia was corroborated by flow cytometry and detecting the increased number of CD163+ cells positive for a proliferation marker Ki67 at perivascular spaces. CD163+ cells in the ischemic brains up-regulated many inflammatory genes and parenchymal CD163+ cells expressed iNOS, which indicates acquisition of a pro-inflammatory phenotype. In mice, BAMs typically express CD206 and we found a subset of these cells expressing CD169. Chimeric mice generated by transplanting bone marrow of donor Cx3cr1gfpCCR2rfp mice to wild type hosts showed an increased number of CX3CR1+CD169+ perivascular macrophages 3 days post-ischemia. Furthermore, these cells accumulated in the brain parenchyma and we detected replacement of perivascular macrophages by peripheral monocytic cells in the sub-acute phase of stroke. In line with the animal results, post-mortem brain samples from human ischemic stroke cases showed time-dependent accumulation of CD163+ cells in the ischemic parenchyma. Our findings indicate a unique transcriptional signature of BAMs, their local proliferation and migration of inflammatory BAMs to the brain parenchyma after stroke in animal models and humans.

中文翻译：

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定义啮齿动物和人类缺血性中风后CNS边界相关巨噬细胞的分子身份和命运。

中枢神经系统（CNS）边界相关巨噬细胞（BAM）在成年期间保持其稳态种群，在生理条件下不会被循环单核细胞所取代。在病理条件下，它们在中枢神经系统完整性和功能中的作用仍然未知。直到最近，由于常见的巨噬细胞标记物的表达，BAM和小胶质细胞无法被明确地区分。我们调查了使用RNA测序从大鼠假手术和缺血性脑中免疫分类BAM的转录谱。我们发现，BAM比小胶质细胞和浸润性巨噬细胞表达不同的转录特征。在缺血损伤后3天分离的CD163 +细胞中，与细胞周期相关的功能基团的富集表明这些细胞的增殖能力。通过流式细胞术证实了缺血后3天CD163 +细胞数量的增加，并在血管周围空间检测了增殖标记物Ki67阳性的CD163 +细胞数量的增加。缺血性脑中的CD163 +细胞上调了许多炎性基因，实质CD163 +细胞表达了iNOS，这表明获得了促炎表型。在小鼠中，BAM通常表达CD206，我们发现了这些细胞中表达CD169的子集。通过将供体Cx3cr1gfpCCR2rfp小鼠的骨髓移植至野生型宿主而产生的嵌合小鼠在缺血后3天显示CX3CR1 + CD169 +血管周围巨噬细胞数量增加。此外，这些细胞积聚在脑实质中，我们在中风的亚急性期发现外周血单核细胞替代了血管周巨噬细胞。与动物实验结果一致，来自人类缺血性中风病例的验尸脑样本显示缺血性实质中CD163 +细胞的时间依赖性积累。我们的发现表明，在动物模型和人类中风后，BAM的独特转录特征，它们的局部增殖和炎症性BAM的迁移以及向脑实质的迁移。