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Fig. 6 | Journal of Neuroinflammation

Fig. 6

From: Microglia prevent peripheral immune cell invasion and promote an anti-inflammatory environment in the brain of APP-PS1 transgenic mice

Fig. 6

Microglia ablation in APP-PS1 mice resulted in increased CD3+/CD8+ T-cell numbers in the brain, and CD8+ T-cell numbers were highly increased in cortical brain regions of APP-PS1 mice interacting with Iba1+/TMEM119+ and Iba1+/TMEM119 cells. Detailed immunohistochemical analysis of CD8+ T-cell numbers (green) in brains of APP-PS1 mice revealed similar CD8+ T-cell numbers compared to WT when analyzing total sagittal brain sections; however, CD8+ T-cell numbers were significantly increased in cortical brain regions of APP-PS1 mice compared to WT (a). T-cells were mechanically isolated from total brain hemispheres and quantitatively analyzed by flow cytometry after ablation of microglia cells (b, gated for single-living CD45+/CD3+ cells; CD4+ red, CD8+ green). The total number of CD45+/CD3+ T-cells was significantly increased in APP-PS1 mice treated with PLX5622 compared to WT-treated mice (c). CD3+/CD4+ T-cell numbers trend to be increased in APP-PS1 mice treated with PLX5622 (d). CD3+/CD8+ T-cell numbers were significantly increased in APP-PS1 mice treated with PLX5622 compared to APP-PS1 and WT PLX5622-treated mice (e). CD8+ T-cells in APP-PS1 mice were located directly in the brain parenchyma and observed in different interaction types with Iba1+ cells (white), showing either no contact, intermediate, or very tight interaction with brains Iba1+ cells (f). Performing confocal microscopy, we observed very tight cell to cell interactions with Iba1+ cells (g) and orthogonal projections showed CD8+ T-cells associated with Iba1+/TMEM119+ and as well with Iba1+/TMEM119 cells in APP-PS1 mice (arrow, h). CD8+ T-cells that tightly associated to Iba1+ cells showed high expression of Zap70 (red) at sites of the cell membrane, indicating immune synapse formation, and activation of the T-cell receptor complex (arrow, i). Dapi (blue) was used as nucleus stain. One-way ANOVA with Tukey’s multiple comparison test (c, d, e n = 8–9/group) and unpaired Student’s t test (a, n = 5/group) was performed. Scale: 1 mm and 50 μm (a), 20 μm (f), 10 μm (h, i), 5 μm (g)

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