Fig. 6: Microglial SIRPα is downregulated in AD pathology.

a, b Western blot and statistical analysis show SIRPα expression decreased remarkably in the cortex of AD patients. Non-AD = 4, AD patients=5. Two-tailed unpaired t test. Detailed sample information is listed in the Table 1 in Methods section. c, d Flow cytometry analysis displays SIRPα expression of acute isolated microglia from 2-months, 5-months, and 8-months old WT and AD mice. Histograms represent quantification of geometric mean fluorescent intensity (gMFI) of SIRPα. n = 5 mice/group, average of three tests from each mouse, two-way ANOVA via Sidak’s multiple comparisons test. e, f Immunostaining and quantification of SIRPα with microglial marker (Iba-1) in cortex of WT and AD mice (5 months old). Scale bar, 25 μm, n = 5 mice/group; average of 6–8 fields from each mouse, two-tailed unpaired t test. g, h Western blot and statistical analysis of SIRPα protein level in primary cultured microglia after Aβ₄₂ monomer (Aβm) or Aβ₄₂ oligomer (Aβo) treatment. Cells were treated with 0.2 µM Aβ for 24 h before protein analysis. n = 5 experiments, one-way ANOVA, Dunnett’s multiple comparisons test. i, j Flow cytometry analysis shows microglial SIRPα decreased 3 days after intracerebroventricular (ICV) injection of Aβo (2 μg/mouse). Histogram shows the gMFI quantification of microglial SIRPα. n = 5 mice/group (WT male, 3 months age), average of three tests from each mouse. One-way ANOVA analysis with Dunnett’s multiple comparisons test. Data are mean ± s.e.m. *P < 0.05, ***P < 0.001, NS not significant. Detailed statistical information was listed in Supplementary Statistical Data. Source data are provided as a Source Data file.