Characterization of the microglial phenotype under specific pro-inflammatory and anti-inflammatory conditions: Effects of oligomeric and fibrillar amyloid-beta.

M1 and M2 are the extremes of the differentiation spectrum of activated macrophages. Since microglia are members of the same cell lineage, we have characterized their transcription profile and their phagocytic activity under different conditions. LPS or IFN-gamma induce a M1-like phenotype, while IL-10 or IL-4 differentiate microglia towards a M2-deactivated or M2-alternatively-activated phenotype respectively. These differentiation processes also affect the Notch pathway. In order to study the polarization induced by Abeta, microglia was stimulated with different forms of the peptide. The oligomeric Abeta is a stronger M1-inductor than the fibrillar form. Moreover, a cytokine-induced anti-inflammatory environment reduces the microglial reactivity towards oligomeric Abeta.