Figure 3. Microglial overexpression of the LDLR transgene reduces its Apoe expression and intracellular apoE level, and is associated with suppressed microglial activation.

(A, B) Western blot and quantification of apoE and LDLR in primarily cultured microglia isolated from P2 pups of WT and LDLR Tg mice (n=3, mixed sex).

(C) qPCR for Ldlr and Apoe in cultured microglia (n=5-6, mixed sex).

(D) Immunofluorescent staining of LDLR and Iba1 in 9-month WT and LDLR Tg mice. Column 1 and 4 (scale bar: 10μm): zoom-in images of square areas in column 2 and 3 (scale bar: 50μm) respectively. Arrow heads point to microglia overexpressing LDLR.

(E, F) qPCR for Ldlr in microglia acutely isolated from 3-month WT and LDLR Tg mice by magnetic beads (E) or by FACS (F) (n=3-4).

(G) qPCR for Apoe in FACS-sorted microglia from 3-month WT and LDLR Tg mice (n=4).

(H, I) Western blot and quantification of apoE level in acutely isolated microglia from 3-month (H) and 20-month (I) WT and LDLR Tg mice (n=3).

(J, K) qPCR for Apoe (J) and DAM/proinflammatory genes (K) in FACS-sorted microglia from 3-month and 20-month WT and LDLR Tg mice (n=3-4), two-way ANOVA with Tukey’s post hoc test, two-sided.

(L) Co-staining of apoE and CD68 in 9-month P301S mice and P301S/LDLR mice (scale bar: 50μm).

(M) Staining and quantification of CD68 in the hippocampus of 9-month P301S and P301S/LDLR mice (n=16-21), scale bar: 500μm. Mann-Whitney test (two-sided).

Data expressed as mean ± SEM. Student’s t-test (two-sided) in (B), (C), (E-I), *p<0.05, **p<0.01 ***p<0.001, ****p<0.0001. See also Figure S1.