Transcriptional profiling of CD11b+ microglia isolated from cerebellum and olfactory bulb-removed brains of K18-seeded P301L, PBS-injected P301L and PBS-injected FVB at 1-week, 1-month, and 3-months post-injection.

To gain deeper insights into the relationship between Tau spreading and microglial response, we conducted a comprehensive analysis of microglial heterogeneity in K18-seeded P301L mice at 1 week, 1 month, and 3 months post-injection. We compared these findings with those from control groups: P301L mice injected with PBS and their non-transgenic counterparts, the FVB mice also subjected to PBS injection. For this purpose, we employed CITE-seq to investigate CD11b positive cells isolated from cerebellum and olfactory bulb-removed brains. P301L mice represent a transgenic lineage originating from FVB mice, characterized by their expression of the human tau protein, specifically the 4R/2N isoform. At the age of 3 months, both the transgenic P301L mice and their non-transgenic FVB counterparts were injected with either PBS or K18. Subsequently, the brains of K18-seeded P301L, PBS-injected P301L, and PBS-injected FVB mice were extracted at 1-week, 1-month, and 3-month time points post-injection. After removing the cerebellum and olfactory bulbs, the remaining brain tissue was physically and enzymatically dissociated in the presence of Actinomycin D and Brefeldin A. Following dissociation, CITE-seq antibodies (ADTs and HTOs) and CD11b-PE/Cy5 staining were used. The DAPI-CD11b+ cells were subsequently isolated using fluorescence-activated cell sorting (FACS).