Figure 4

Soluble extracellular and membrane-associated Aβ species levels in the brain of APP_Swe/PS1/CCR2^−/− mice transplanted with WT (GFP) BMCs. Hemibrain extracts from soluble extracellular (A and D) and membrane-associated proteins (G and J) of 6-month-old APP_Swe/PS1/CCR2^−/− mice harboring WT (GFP) BMCs were assessed by Western blot on a 10–20% Tris-Tricine denaturing polyacrylamide gel to separate Aβ species using anti-Aβ antibody 6E10. The intensity of each band was quantified by densitometric analysis and normalized to β-actin values. Ratios of Aβ species (Aβ/β-actin) are represented for extracellular (B) and membrane-associated proteins (E). Lower levels of soluble extracellular and membrane-associated Aβ species were found in mice harboring WT BMCs, whereas Aβ oligomer levels increased in mice transplanted with CCR2-deficient BMCs. Correlations were determined between spatial memory decline (water T-maze test) and soluble Aβ species in extracellular (C) and membrane-associated (F) fractions. Results are expressed as the mean ± SEM; n = 4−5; *P < 0.05 and **P < 0.01 versus CCR2^−/− → APP_Swe/PS1; ^#P < 0.05 versus APP_Swe/PS1/CCR2^−/−. One-way ANOVA was performed using Dunnett or Tamhane post hoc tests; for the Dunnett test the control group was APP_Swe/PS1/CCR2^−/− mice. Correlation was estimated by the Spearman correlation coefficient. OD, optical density; , CCR2^−/− → APP_Swe/PS1; , APP_Swe/PS1/CCR2^−/−; , GFP → APP_Swe/PS1/CCR2^−/−.