GPR34 senses myelin debris to promote neuroinflammation and pathology

Sterile neuroinflammation is a major driver of multiple neurological diseases. Myelin debris, which is released from the damaged myelin sheaths during demyelination, can act as an inflammatory stimulus to promote sterile inflammation and neurological pathologies, but the mechanism is poorly understood. Here, we show that lysophosphatidylserine (LysoPS)-GPR34 axis plays a critical role in microglia-mediated myelin debris sensing and the subsequent neuroinflammation. Myelin debris-induced microglia activation and proinflammatory cytokine expression relied on its lipid component LysoPS. Both myelin debris and LysoPS promoted microglia to produce IL-1and IL-6 via GPR34 and its downstream PI3K-AKT and ERK signaling. In vivo, LysoPS production and GPR34 signaling were found to be essential for neuroinflammation and pathologies in the mouse models of multiple sclerosis and stroke. Importantly, pharmacologic blockade of GPR34 showed potential therapeutic effects on these disease models. Thus, our results identify GPR34 as a key receptor to sense myelin debris and promote neuroinflammation, and suggest it as a potential target for demyelination-associated diseases.