Figure 7

CCR2-deficient BMCs increase MCP-1 expression in APP_Swe/PS1 mice. Representative dark-field photomicrographs of in situ hybridization showing the cortical expression of MCP-1 in the brains of 6-month-old APP_Swe/PS1 and APP_Swe/PS1/CCR2^−/− mice harboring GFP or CCR2^−/− BMC (A–D). MCP-1 qualitative quantification was performed for each group of mice (n = 5−12) (E). Transplantation of CCR2^−/− cells caused an increase in the MCP-1 transcript levels. Brain sections were immunostained for Aβ and iba-1, and the number of plaque-associated microglia was determined in hippocampus (F) and cortex (G). APP_Swe/PS1 and APP_Swe/PS1/CCR2^−/− harboring GFP or CCR2^−/− BMC exhibited less recruitment of microglia in the plaque vicinity. Brain sections of APP_Swe/PS1 (I) and APP_Swe/PS1/CCR2^−/− (J) mice harboring GFP-expressing cells in their bloodstream were labeled to reveal GFP cells (brown cells) together with CX₃CR1 mRNA (silver grains). Results are expressed as the mean ± SEM; n = 8−16; ***P < 0.001 versus APP_Swe/PS1; ^##P < 0.01 and ^###P < 0.001 versus APP_Swe/PS1/CCR2^−/−. One-way ANOVA was performed using Bonferroni or Tamhane post hoc tests. A–D: Arrowheads: MCP-1 positive signal; I and J: black arrowheads: double-labeled cells (GFP/CX₃CR1 mRNA); open arrowheads: CX₃CR1-positive cells (negative for GFP); red arrowheads: GFP-positive cells (negative for CX₃CR1 mRNA). Scale bar 500 µm (A–D) and 50 µm (I and J). E: The plus signs correspond to the intensity and the surface of the signal. The number of the plus signs shows augment proportionally with the intensity and the surface. ■, APP_Swe/PS1; , GFP → APP_Swe/PS1; , CCR2^−/− → APP_Swe/PS1; , APP_Swe/PS1/CCR2^−/−; , GFP → APP_Swe/PS1/CCR2^−/−.