Maresin1 Decreased Microglial Chemotaxis and Ameliorated Inflammation Induced by Amyloid-β42 in Neuron-Microglia Co-Culture Models.

Inflammation resolution is regulated by specialized pro-resolving lipid mediators (SPMs) and the levels of SPMs are found decreased in Alzheimer's disease (AD) brain. We have previously found that one of the SPMs, Maresin1 (MaR1), improved neuronal survival and increase microglial phagocytosis of amyloid-β 1-42 (Aβ42); however, the mechanisms underlying the protective mechanism remain further investigation. We aim to investigate the effects of MaR1 on microglial chemotaxis and activation in this study. Both indirect and direct primary neuron and microglia co-culture system was used in this study. Our results showed MaR1 downregulated the increased microglial chemotaxis induced by Aβ42. The microglial inactivation marker CD200R was downregulated by Aβ42 and upregulated by MaR1. Pro-inflammatory cytokines secretion such as tumor necrosis factor (TNF)-α were increased by Aβ42 and these changes were revised by MaR1 treatment. In addition, the levels of chemokine monocyte chemoattractant protein (MCP)-1 were increased while the levels of anti-inflammatory factor IL-10 secretion were decreased by Aβ42, and these changes were abolished by MaR1 treatment. Moreover, by proteomics analysis, we identified cell signaling pathways affected by MaR1 were not only limited to inflammation-related pathways such as P38, but also in pathways involved in cell survival, autophagy, axon formation, and apoptosis, including PI3K/AKT, mTOR, ERK, caspase3, Cdc42, and p75NTR. In conclusion, MaR1 promoted inflammation resolution by inhibiting chemotaxis and regulating activation of microglia. MaR1 played a neuroprotective role by affecting cell signaling pathways involving inflammation, cell survival, autophagy, axon formation, and apoptosis inhibition.