CCR5 drives glucose metabolic reprogramming to control microglial synaptic pruning via histone lactylation in a mouse model of depression

Depression is linked to microglial activation, but the precise triggers and downstream pathways remain elusive. Through single-cell RNA sequencing of human blood samples, we find upregulation of the CCL5-CCR5 axis in patients with major depressive disorder. Using a chronic social defeat stress mouse model, we show that CCR5 is specifically elevated in activated hippocampal microglia. Microglia-specific deletion of CCR5 alleviates depressive-like behaviors and prevents microglial activation. Mechanistically, CCR5 binding to VHL stabilizes HIF-1α, redirecting microglial metabolism toward aerobic glycolysis. This metabolic shift results in lactate accumulation, which drives histone H4 lysine 12 lactylation (H4K12la). Genome-wide profiling reveals that H4K12la enrichment at complement gene promoters facilitates their transcription, ultimately leading to excessive microglial engulfment of neuronal spines and synaptic loss. Importantly, either inhibiting glycolysis or exogenous lactate supplementation can respectively rescue or mimic the pathological synaptic pruning and depressive-like behaviors. Our findings indicate a CCR5-driven immune-metabolic-transcriptional axis in microglia that underlies synaptic deficits in depressive-like behaviors, offering potential targets for therapeutic intervention.