Microglia-mediated extracellular matrix disruption drives neuronal dysfunction, motor impairments, and sedation...

Alcohol abuse is the primary risk factor for alcohol use disorder (AUD), a leading cause of preventable morbidity and mortality worldwide. While direct effects of alcohol on neuronal function are well established, the role of microglia in acute and chronic neurological dysfunction in AUD remains underappreciated. Using mouse models of binge and high-intensity alcohol exposure and longitudinal in vivo imaging, we found that microglia exhibited acute and progressive morphological responses that preceded but paralleled ethanol-induced sedation. Ethanol also induced microglia-dependent extracellular matrix (ECM) disruption, synapse elimination, and reduced neuronal activity and density. Genetic deletion of microglial Myd88 protected against ethanol-induced microglial reactivity, neuronal damage and dysfunction, intoxication, and motor impairments by preventing ECM disruption. Frontal cortex ECM was similarly disrupted in human brain tissue from individuals with AUD. These findings identify microglia as cellular drivers of brain dysfunction following alcohol abuse and MyD88 as a critical therapeutic target for AUD.