FAM19A3, a novel secreted protein, modulates the microglia/macrophage polarization dynamics and ameliorates cerebral ischemia

In this study, we have identified FAM19A3 as a gene that is significantly upregulated in the microglia in the middle cerebral artery occlusion (MCAO) mouse model. FAM19A3 expression and secretion were promoted by M2 stimuli, and this indicated that FAM19A3 might be an M2-type gene. Indeed, recombinant FAM19A3 promoted M2 polarization and inhibited M1 polarization of microglia in vitro. Similarly, recombinant FAM19A3 promoted M2 polarization of microglia and macrophages in vivo, and attenuated cerebral ischemia in the MCAO mouse model. Thus, the newly-identified secreted protein FAM19A3 modulates the microglia/macrophage polarization dynamics and ameliorates cerebral ischemia.