Extended Data Fig. 4: APP/PS1Axl^−/−Mertk^−/− microglia are unresponsive to Aβ plaques.

a, Distribution of distance of microglial cell body centroids, in 2 μm bins, from the edge of MX04-labeled Aβ plaques with diameters of 10-15 μm in APP/PS1 (gray) and APP/PS1Axl^−/−Mertk^−/− (red) cortex. Values obtained for 56 and 23 plaques from 3 and 4 mice for APP/PS1 and APP/PS1Axl^−/−Mertk^−/−, respectively. b, Number of imaged GFP⁺ primary processes per PAM (microglia < 5 μm from plaques) in APP/PS1 (gray, A/PS) and APP/PS1Axl^−/−Mertk^−/− (red, A/PS A/M^−/−) cortex. c, Summed length of primary microglial processes per PAM in APP/PS1 (gray) and APP/PS1Axl^−/−Mertk^−/− (red) cortex. d, Process polarization ratio to nearest plaque per NPAM (microglia > 20 μm from plaques; see Materials and Methods) in APP/PS1 (gray) and APP/PS1Axl^−/−Mertk^−/− (red) cortex. e, Quantification of microglial cell density in the cortex of 16 mo APP/PS1 (gray) and APP/PS1Axl^−/−Mertk^−/− (red) mice for microglia 0-10 μm, 10-20 μm, and >20 μm from the edge of the nearest plaque. Data points are from 45-129 cells (PAM) investing 10-29 plaques (b, c), and 21-49 cells peripheral to 7-24 plaques (d) from n = 3 mice per genotype (b-d), Points in e represent 3-5 imaging volumes from 3 APP/PS and 4 APP/PS1Axl^−/−Mertk^−/− mice. Two-way ANOVA with Sidak’s multiple comparison test (a, e) and Mann-Whitney’s test (b-d), Data are represented as mean ±1 STD.

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