Perivascular macrophages (pvMs) are associated with cerebral vasculature and mediate brain drainage and immune regulation. Here, using reporter mouse models, whole brain and section immunofluorescence, flow cytometry, and single cell RNA sequencing, besides the Lyve1⁺F4/80⁺CD206⁺CX3CR1⁺ pvMs, we identify a CX3CR1^– pvM population that shares phagocytic functions and location. Furthermore, the brain parenchyma vasculature mostly hosts Lyve1⁺MHCII^– pvMs with low to intermediate CD45 expression. Using the double Cx3cr1^GFP x Cx3cr1-Cre;Rosa^tdT reporter mice for finer mapping of the lineages, we establish that CD45^lowCX3CR1^– pvMs are derived from CX3CR1⁺ precursors and require PU.1 during their ontogeny. In parallel, results from the Cxcr4-CreErt2;Rosa26^tdT lineage tracing model support a bone marrow-independent replenishment of all Lyve1⁺ pvMs in the adult mouse brain. Lastly, flow cytometry and 3D immunofluorescence analysis uncover increased percentage of pvMs following photothrombotic induced stroke. Our results thus show that the parenchymal pvM population is more heterogenous than previously described, and includes a CD45^low and CX3CR1^– pvM population.

血管周围巨噬细胞 (pvMs) 与脑血管系统相关并介导脑引流和免疫调节。^{在这里，除了 Lyve1 +} F4/80 ⁺ CD206 ⁺ CX3CR1 ⁺ pvMs 之外，我们还使用报告小鼠模型、全脑和切片免疫荧光、流式细胞术和单细胞 RNA 测序，确定了一个具有吞噬功能和位置的 CX3CR1 ^– pvM 群体。此外，脑实质脉管系统主要承载 Lyve1 ⁺ MHCII ^–具有低到中等 CD45 表达的 pvM。使用双Cx3cr1 ^GFP x Cx3cr1-Cre；蔷薇^_为了更好地绘制谱系，我们确定 CD45^低CX3CR1 ^– pvMs 来自 CX3CR1 ⁺前体，并且在个体发育过程中需要 PU.1。同时，来自Cxcr4-CreErt2 的结果；Rosa26 tdT^谱系追踪模型支持成年小鼠大脑中所有 Lyve1 ⁺ pvM的骨髓独立补充。最后，流式细胞术和 3D 免疫荧光分析发现光血栓诱发中风后 pvMs 的百分比增加。因此，我们的结果表明实质 pvM 群体比之前描述的更加异质，并且包括 CD45^低和 CX3CR1 ^– pvM 群体。