Fig. 2

Myelin phagocytosis by microglia shows sex- and IDE-dependent effects, while myelin degradation remains unaltered. Myelin management was assessed by flow cytometry experiments. The histogram of control microglia without myelin was used to define the fluorescence threshold to classify an event as DiI-positive microglia. A, B Time-course experiments of myelin phagocytosis by WT and IDE-KO male (A) and female (B) microglia exposed to myelin-DiI for 3–18 h. Histograms of a representative experiment of 3 h phagocytosis are shown in the insets. C, D Time-course experiments of myelin degradation by WT and IDE-KO male (C) and female (D) microglia exposed to myelin-DiI for 3 h (phagocytosis time), followed by degradation times ranging from 3 to 24 h. Histograms of a representative experiment of 24 h degradation are shown. Dots in the graphs represent the average ± SEM of 2 independent experiments with 2 male and 2 female cultures, with at least 10,000 cells/sample. Statistical differences were assessed by three-way ANOVA considering the factors genotype, sex and time, followed by post-hoc pairwise comparisons by Holm–Sidak method. Sex factor was significant in both phagocytosis (p < 0.001) and degradation (p = 0.04) experiments. Phagocytosis in males: factor genotype (p = 0.005), WT vs IDE-KO at 3 h (p = 0.23), 6 h (p = 0.011), 18 h (p = 0.049). Phagocytosis in females: factor genotype (p = 0.009), WT vs IDE-KO at 3 h (p = 0.003), 6 h (p = 0.12), 18 h (p = 0.98). Degradation in males: factor genotype (p = 0.28), WT vs IDE-KO at 0 h (p = 0.21), 3 h (p = 0.87), 6 h (p = 0.72), 18 h (p = 0.67). Degradation in females: factor genotype (p = 0.07), WT vs IDE-KO at 0 h (p = 0.03), 3 h (p = 0.22), 6 h (p = 0.56), 24 h (p = 0.46). *p < 0.05; **p < 0.01