library_construction_protocol: The mice brains were physically and enzymatically dissociated using gentleMACS C tubes (Miltenyi) and enzyme mix papain (20 Units/ml) and DNase I (100 ug/ml). The enzyme mix was pre-warmed at 37oC for 30 minutes. The brains were cut into 2 mm x 2 mm pieces and transferred into the pre-warmed enzyme mix in C tubes. The C tubes were then placed on gentleMACS Dissociator and run brain tissue program 1 to 3. After each program finished, the C tubes were incubated at 37oC for 5 minutes. After the final incubation, the dissociated brain cells were passed through a 100 mm strainer and washed with DMEM.  The washed cells were then reconstituted in 10 ml of 30% Percoll and centrifuged 1000 x g for 10 minutes, with a full break. The cell pellet was reconstituted in staining buffer with Ly6G microbeads and incubated for 10 minutes at 4oC before being sorted with MS Column (Miltenyi). The flow-through was collected (Ly6G negative selection) and washed with staining buffer (PBS with 10% FBS). The cell pellet was reconstituted in staining buffer with CD11b microbeads (1:200) and incubated for 15 minutes at 4oC before being sorted with MS Column (CD11b positive selection). RNA was extracted using RNeasy micro kits (Qiagen) following the manufacturer's protocol. Libraries were prepared with SMART-Seq V4 PLUS Kit (R400752, Takara Bio, Japan) following the manufacturer's instructions.