Abrogation of iNOS proteins level and pro-inflammatory cytokines reduction in primary microglial cells from galectin-3 knockout mice after activation with α-synuclein. Primary microglial culture from wild-type mice shows robust iNOS expression following exposure of 20 μm α-synuclein aggregates, or LPS (100 ng/ml), for 12 h (A). Lower concentrations of α-synuclein aggregates, 5 μm and below, failed to induce iNOS expression in wild- type microglia (A). Primary microglia from galectin-3 knockout mice completely lack iNOS up regulation following exposure of 20 μm α-synuclein aggregates for 12 h (B). Cytokine levels in culture medium from primary microglial cells were measured after 12 h incubation with α-synuclein aggregates. Treatment of wild-type microglia with 5 and 20 μm α-synuclein aggregates for 12 h induced increased levels of IL-1β, IL-12, IFN-γ and IL-4 (C). Treatment of galectin-3 knockout microglia for 12 h reduced levels of IL-1β IL-12 using 20 μm α-synuclein aggregates. Cytokine levels of IFN-γ and IL-4 did not change in galectin-3 knockout compared to wild-type microglia. Two-way ANOVA, *P < 0.05, **P < 0.01, n = 5, mean ± S.E.M.