Overexpression of APP and PS1 in the brain but not in the retina. (A, C, F, and G) Representative immunofluorescence images showing the distribution of APP and PS1 in the brain (A and C) and retina (F and G) of AD donors and mice. (B, D, E, H, and I) Quantitative analysis revealed that, compared to healthy controls, the levels of APP and PS1 in the brains of AD patients show an increasing trend (n = 3). When compared to age-matched WT mice, the percentage of APP⁺ and PS1⁺ areas in the hippocampus and cortex increased in 5×FAD mice, but there was no significant difference observed in the retina (n = 5). (J and K) Western blot analysis of APP and PS1 protein levels in the brain and retina of WT and 5×FAD mice, with corresponding grayscale values (n = 6). (L) UMAPs showed cell clusters of retinal tissue in 10-mo-old WT and 5×FAD mice based on single-cell sequencing data. (M) UMAP clustering plot showing the distribution and expression levels of App in different cell clusters of retinas from WT and 5×FAD mice. (N) Violin plot showing the gene expression levels of App in retinal endothelial cells and pericytes from WT and 5×FAD mice. (O) UMAP clustering plot showing the distribution and expression levels of Psen1 in different cell clusters of retinas from WT and 5×FAD mice. (P) Violin plot showing the gene expression levels of Psen1 in retinal ganglion cells and macrophages/microglia from WT and 5×FAD mice. (Q) Gene expression dot plots showed the expression of App and Psen1 in the retinas of WT and 5×FAD mice, and the results indicated no significant differences in RNA expression at the cellular level across various cell populations. Data are representative of two independent experiments. Data are presented as mean ± SEM. Statistical analysis was performed using two-tailed unpaired t tests (B, H, I, N, and P) or one-way ANOVA with post hoc Tukey tests (D, E, and K). Source data are available for this figure: SourceData F4.