Metabolic reprogramming via SIRT2-deficient microglial large extracellular vesicles ameliorates alzheimer’s pathology

BACKGROUND: Current therapies for Alzheimer's disease (AD) offer only symptomatic relief, highlighting the urgent need for disease-modifying approaches capable of halting or reversing neurodegeneration. Extracellular vesicles (EVs) have attracted growing interest as therapeutic vehicles owing to their inherent capacity to bypass the blood-brain barrier and deliver complex biological cargo to the central nervous system. METHODS: Here, we examined whether large EVs (LEVs) derived from microglia with stable Sirtuin-2 knockdown (SIRT2-KD) confer the neuroprotective effects associated with SIRT2 inhibition. LEVs harvested from SIRT2-KD microglia were administered intranasally to APP/PS1 mice. We assessed microglial uptake of LEVs, along with subsequent changes in cellular metabolism, migration toward amyloid-beta (Aβ) plaques, phagocytic activity, and downstream pathological and behavioral outcomes. Proteomic and acetylomic profiling were employed to characterize the molecular cargo of LEVs-SIRT2-KD. RESULTS: LEVs-SIRT2-KD were readily internalized by microglia in vivo following intranasal delivery. Uptake of these vesicles markedly enhanced microglial bioenergetics, driving coordinated upregulation of both oxidative phosphorylation and glycolysis. This metabolic shift was accompanied by improved microglial recruitment to Aβ plaques and increased phagocytic clearance. Consequently, treated mice showed reduced Aβ plaque deposition, restored synaptic integrity, and reversal of cognitive deficits. Proteomic and acetylomic analyses revealed that LEVs-SIRT2-KD are selectively enriched in proteins and acetylation modifications linked to energy metabolism and phagocytic function, offering a mechanistic basis for the observed metabolic reprogramming. CONCLUSION: Together, these results identify LEVs as a critical vesicle subtype mediating the effects of SIRT2 knockdown and support a cell-free therapeutic strategy for AD centered on EVs-driven metabolic reprogramming of microglia.