Figure 4.

iPSC-derived microglia (iMGL) from APOE4 carriers show increased protein expression of lysozyme C and altered microglial morphology

(A) Representative immunofluorescence images of lysozyme C staining. Scale bar, 50 μm.

(B) The percentage of cells expressing lysozyme C is increased in APOE4 relative to APOE3 iMGL. Data are presented as mean (±SEM) values. APOE3 samples are shown in blue and APOE4 samples in green. ∗∗∗∗p < 0.0001; unpaired t test.

(C) Representative images of IBA1 staining used for branch length analysis. Scale bar, 25 μm; arrows point to representative branches.

(D) APOE4 iMGL have significantly shorter branch length per cell compared with APOE3 iMGL. APOE4 iMGL include both heterozygous and homozygous lines. Data are shown as the mean branch length per cell (±SEM); APOE3 males and females are shown in light and dark blue, respectively, whereas APOE4 males are shown in green and APOE4 females are in pink. ∗p < 0.05, ∗∗∗∗p < 0.0001; Bonferroni’s multiple comparisons adjusted p values relative to APOE3 iMGL.

(E) A greater proportion of APOE4 iMGL have zero branches, whereas a decreased proportion have one branch. Data are shown as the proportion of cells characterized as having a given number of branches (±SEM). ∗∗p < 0.01 relative to the number of APOE3 cells with zero branches; ∗p < 0.05 relative to the number of APOE3 cells with 1 branch; t test with Sidak-Bonferroni multiple comparisons test correction.