Demyelination-derived lysophosphatidylserine promotes microglial dysfunction and neuropathology in a mouse model of Alzheimer's disease.

Microglia dysfunction-associated neuroinflammation is an important driver of Alzheimer's disease (AD), but the mechanism is poorly understood. Here, we show that demyelination promotes neuroinflammation and cognitive impairment via the lysophosphatidylserine (LysoPS)-GPR34 axis in AD. Demyelination is observed at the early stage and is accompanied by an increase in LysoPS in myelin debris in a 5xFAD mouse model of AD. Reducing the content of LysoPS in myelin or inhibiting its receptor GPR34 via genetic or pharmacological approaches can reduce microglial dysfunction and neuroinflammation and improve microglial Aβ phagocytosis, subsequently resulting in less Aβ deposition and memory restoration in 5xFAD mice. Furthermore, increased LysoPS production and microglial GPR34 expression were also observed in the brains of AD patients. These results reveal the pathogenic role of demyelination-derived LysoPS in microglial dysfunction and AD pathology and suggest that blocking GPR34 as a therapeutic strategy beyond targeting Aβ.