IL-33-PU.1 transcriptome reprogramming drives functional state transition and clearance activity of microglia in Alzheimer's disease

Impairment of microglial clearance activity contributes to beta-amyloid (Aß) pathology in Alzheimer disease (AD). While the transcriptome profile of microglia directs microglial functions, how the microglial transcriptome can be regulated to alleviate AD pathology is largely unknown. Here, we show that injection of interleukin (IL)-33 in an AD transgenic mouse model ameliorates Aß pathology by reprogramming microglial epigenetic and transcriptomic profiles to induce a microglial subpopulation with enhanced phagocytic activity. These IL-33–responsive microglia (IL-33RM) express distinct transcriptome signature, highlighted by major histocompatibility complex class II genes, and restored homeostatic signature genes. IL-33–induced remodeling of chromatin accessibility and PU.1 transcription factor binding at the signature genes of IL-33RM control their transcriptome reprogramming. Specifically, disrupting PU.1–DNA interaction abolishes the microglial state transition and Aß clearance induced by IL-33. Thus, we define a PU.1-dependent transcriptional pathway that drives the IL-33–induced functional state transition of microglia, resulting in enhanced Aß clearance. Overall design: Single-cell transcriptomic and epigenetic profiling of microglia upon IL-33 treatment in APP/PS1 mice