Figure 4.

Wild-type sTREM2 blocks Aβ-induced membrane permeabilization and neuronal loss, but R47H sTREM2 inhibits less. A, 10 μM of monomeric Aβ was aggregated ±1 μM wild-type (WT) or R47H human sTREM2 for 6 h, diluted to 200 nM, and membrane permeabilization assay was performed. Error bars = SD of three independent experiments; ∗∗p < 0.01; statistics: two-sample t-test. B, 10 μM of monomeric Aβ was aggregated for 6 h, diluted to 200 nM, then incubated for 30 min with vehicle, 200 nM WT sTREM2 or R47H sTREM2, before the membrane permeabilization assay was performed. Error bars = SD of three independent experiments; ∗∗p < 0.01; statistics: two-sample t-test. C and D, mixed neuronal–glial cocultures were treated with either: vehicle, 250 nM monomeric Aβ, 250 nM Aβ + 25 nM WT sTREM2 or 250 nM Aβ + 25 nM R47H sTREM2. Three days later, cultures were stained with isolectin B4 (green, to identify microglia), propidium iodide (red, to identify dead cells), and Hoechst 33342 (blue, to identify cells and whether apoptotic) and imaged (representative fields: C), and the number of apoptotic, necrotic, and healthy neurons were quantified (mean data: D). Loss is the decrease in neuronal density relative to vehicle-treated cultures. Error bars = SEM; ∗∗p < 0.01, ∗∗∗p < 0.001, ∗∗∗∗p < 0.0001; n = 4 independent experiments on separate cell cultures. Statistical analysis was by one-way ANOVA and Tukey's post-hoc test.