Fig. 1

Classification of brain macrophages. Brain macrophages are typically categorized into three major types. Microglia are localized in the central nervous system parenchyma and specifically express P2Y purinoceptor 12 (P2RY12), transmembrane protein 119 (TMEM119) and Sal-like protein 1 (SALL1). The other group is perivascular, meningeal and choroid plexus macrophages located at the interface between the parenchyma and the circulation, which are less well defined because many markers are expressed overlapping. BMDMs are distributed in the extensive network of vasculature. CX3CR1, CX3C-chemokine receptor 1; CSF, cerebrospinal fluid; BMDMs, bone marrow-derived macrophages