Lipid Droplet-Accumulating Microglia as a Therapeutic Node in Neurodegenerative Disease

Abstract Neurodegenerative disorders increasingly reflect failures of cellular state control rather than the linear accumulation of a single toxic lesion. Microglia become trapped in maladaptive states in which inflammatory activation is decoupled from effective cargo processing. Lipid droplet-accumulating microglia (LDAM) represent a recurrent convergence state across aging and neurodegeneration, characterized by persistent neutral lipid sequestration, reduced phagocytosis-to-degradation capacity, oxidative amplification, and chronic but functionally inefficient inflammation. LDAM emerges when lipid substrate influx exceeds the capacity of cholesterol efflux, lysosomal lipophagy, and mitochondrial β-oxidation, converting lipid droplets from transient buffers into stable metabolic anchors. This entrenchment is reinforced by mitochondrial exhaustion, vacuolar H+-ATPase-linked lysosomal deacidification, and inflammasome/interferon locking, often further amplified by cGAS-STING signaling. Together, these constraints converge on a state of metabolic-epigenetic locking that sustains permissive chromatin landscapes at pro-inflammatory loci. On this basis, state-resetting strategies are considered that rebalance lipid flux, restore organelle clearance capacity, and transiently restrain inflammatory amplification, while spatial multiomics and fluid biomarkers are discussed as candidate tools for stage- and niche-resolved stratification of combination interventions.