Fig. 2

sTREM2 promotes microgliosis in 5×FAD mice and microglial migration. a The hippocampus was dissected from vehicle- or sTREM2-injected 5×FAD mice. After RNA extraction, the relative mRNA levels of Iba1 and GFAP in the hippocampus shown as a bar graph were determined by quantitative real-time PCR. β-actin was used as an internal control (n = 4 mice per group, paired Student’s t test). b Iba1 and GFAP proteins were analyzed by Western blotting 7 days after sTREM2 injection to the hippocampus of 5×FAD mice. c Quantitation of the protein levels of Iba1 and GFAP in b (n = 4 mice per group, paired Student’s t test). d Coronal sections from injected 5×FAD mice were stained with DAPI (blue) for nuclei, Ki67 (green) for proliferating cells, and Iba1 (red) for microglia. Representative z-stack images of the hippocampus regions are shown. Original magnification ×20; scale bar, 100 μm. Images on the right represent enlarged Ki67-positive cells with a scale bar equal to 20 μm. e Quantitation of the number of Iba1-positive cells in d (n = 5 mice, 22 fields of each group for analysis, paired Student’s t test). f Quantitation of the number of proliferating microglial cells, as indicated by the co-staining of Ki67 and Iba1 (Iba1⁺Ki67⁺) (n = 5 mice, 22 fields of each group for analysis, paired Student’s t test). g Primary microglial cells (10⁵) from WT mice were plated onto transwell chamber inserts. Following 24-h incubation with vehicle (PBS), native sTREM2 protein (100 nM), or heat-inactivated sTREM2 protein (100 nM), cells migrated through the membrane were stained with hematoxylin and eosin and imaged under a Nikon inverted microscope. Scale bar, 100 µm. h Quantitation of the number of migrated cells (n = 9 from three independent experiments, one-way ANOVA). All data are presented as mean ± SEM. *p < 0.05; **p < 0.01; ****p < 0.0001; ns, not significant