Fig 1: Pathological microglial activation induces sCSF1R elevation in vivo and in vitro. a-b Representative images (a) and quantification (b) of nuclei (blue) and Iba1 (red) immunostaining in the hippocampus of seven- to eight-month-old wild-type (WT) mice, LPS-injected WT mice, and 5×FAD mice (n = 6–8 mice per group; unpaired Student’s t-test). Scale bars, 150 μm. c-e Representative images (c) and quantification (d-e) of nuclei (blue), Iba1 (red), CD68 (green), and Clec7a (yellow) immunostaining in the hippocampus of seven- to eight-month-old WT mice, LPS-injected WT mice, and 5×FAD mice (n = 6–8 mice per group; unpaired Student’s t-test). Scale bars, 25 μm. f ELISA-based quantification of sCSF1R in the CSF from seven- to eight-month-old WT mice, LPS-injected WT mice, and 5×FAD mice (n = 6 mice per group; one-way ANOVA). g-i Western blot analysis of full-length CSF1R, shed sCSF1R, and Iba1 in the hippocampal lysates from seven- to eight-month-old WT mice, LPS-injected WT mice, and 5×FAD mice (n = 6–8 mice per group; unpaired Student’s t-test). j-l Western blot analysis of full-length CSF1R in cell lysates and sCSF1R in culture media from primary microglia after 3-hour treatment with 10 µM oligomeric Aβ42 (oAβ) and fibrillar Aβ42 (fAβ) (n = 6–8; from three independent experiments; unpaired Student’s t-test). m-o Western blot analysis of full-length CSF1R in cell lysates and sCSF1R in culture media from primary microglia treated with 10 ng/mL LPS or 25 ng/mL GM-CSF (n = 6; from three independent experiments; one-way ANOVA). Data are presented as mean ± SEM. *p < 0.05; **p < 0.01; ***p < 0.001; ****p < 0.0001; ns, not significant