Immunohistochemistry (IHC) was performed as described [49 (link)]. Briefly, hippocampal sections from AD patients were retrieved with 10% (v:v) formic acid for 15 min at 37°C and then blocked with 5% (w:v) BSA. Blocked sections were stained with antibodies against Aβ and ATP6V0C overnight. Antibodies 6E10 (1:1000), ATP6V0C (1:500), MAP2 (1:3000) were used to detect human Aβ, ATP6V0C, and MAP2, respectively. Secondary antibodies used in IHC assays are as follows: Alexa Fluor 488 goat anti-rabbit IgG (H + L) (Invitrogen, A11008), Alexa Fluor 594 goat anti-mouse IgG (H + L) (Invitrogen, A11005), DyLight405-AffiniPure Goat Anti-Chicken IgY (IgG) (H + L) (Jackson ImmunoResearch, 103-475-155).