MFG-E8 enhances microglial phagocytosis of oAβ through CD47. (A) Microglia were treated with 1 μg/mL of isotype-matched control IgG (a, b), 100 ng/mL MFG-E8 (b − f), 1 μg/mL of anti-CD36 neutralizing antibody (c), 1 μg/mL of anti-CD47 neutralizing antibody (d), the peptide antagonist 4N1K 10 μg/mL (e) or 100 μg/mL (f) for 1 h, and then 5 μM oAβ was added to the culture for 24 h. Primary antibodies against Rab7 (green), oAβ (red) and nuclei (blue) were used (a − f). Scale bar = 50 μm. (B) Quantification of the phagocytosis index. Results show the means with S.E.M. (n = 3), in which 10 randomly selected fields were analyzed. Significant differences compared with the isotype-matched control samples (#) or samples treated only with MFG-E8 (*) are noted. ***: P <0.001; ###: P <0.001 (one-way ANOVA with Tukey’s post-hoc test). (C) The effects of blockade of CD36 and CD47 in MFG-E8-treated microglia on neuronal survival. Neuron − microglia co-cultures were pre-treated with MFG-E8 for 1 h in the presence of anti-CD36 neutralizing antibody, anti-CD47 neutralizing antibody, and 10 μg/mL or 100 μg/mL 4N1K. Then, the cultures were treated with oAβ for 24 h. The neuronal survival rate was estimated. The results are presented as the means with S.E.M. (n = 5), in which 10 randomly selected fields were analyzed. Significant differences compared with the isotype-matched control samples (#) or samples treated only with MFG-E8 (*) are noted. *: P <0.05; ###: P <0.001 (one-way ANOVA with Tukey’s post-hoc test).