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Supplemental Digital Content is available in the text.A major risk factor for the development of Alzheimer’s disease (AD) is increasing age, but the reason behind this association has not been identified. It is thought that the changes in endocytosis seen in AD patients are causal for this condition. Thus, we hypothesized that the increased risk of developing AD associated with ageing may be because of changes in endocytosis. We investigated using Western blotting whether the expression of endocytic proteins involved in clathrin-mediated and clathrin-independent endocytosis are altered by increasing age in a mouse model of amyloid pathology. We used mice transgenic for human amyloid precursor protein containing the V717I London mutation. We compared the London mutation mice with age-matched wild-type (WT) controls at three ages, 3, 9 and 18 months, representing different stages in the development of pathology in this model. Having verified that the London mutation mice overexpressed amyloid precursor protein and β-amyloid, we found that the expression of the smallest isoform of PICALM, a key protein involved in the regulation of clathrin-coated pit formation, was significantly increased in WT mice, but decreased in the London mutation mice with age. PICALM levels in WT 18-month mice and clathrin levels in WT 9-month mice were significantly higher than those in the London mutation mice of the same ages. The expression of caveolin-1, involved in clathrin-independent endocytosis, was significantly increased with age in all mice. Our results suggest that endocytic processes could be altered by the ageing process and such changes could partly explain the association between ageing and AD.

Current therapies for Alzheimer’s disease only treat the symptoms of the disease. We have previously developed a novel monoclonal antibody, 2B3, which binds to the -secretase cleavage site in amyloid precursor protein (APP) and reduces the production of amyloid- (A) in human cell lines. To determine whether the antibody was likely to be effective in mouse models of amyloid pathology in vivo, we investigated whether 2B3 could also bind to APP in mouse primary cortical neurones. Primary cortical neurones were produced from E15.5–17.5 C57Bl6 wild-type and transgenic APPV717I (London mutation) embryos. The percentage of the neuronal population was determined by immunocytochemistry. Cells were treated with 10 gml 2B3 or an irrelevant IgG for 48 h and A40 levels determined by ELISA. The population of cells was found to contain over 75 neurones and 2B3 bound effectively to these cells. No differences in A40 were detected between wild-type and transgenic cells. Importantly, 2B3 significantly inhibited the production of A40 by 75.15±1.37 of the media control, whereas an irrelevant IgG only significantly reduced A40 levels by 23.35±5.55 of the media control. The reduction in A40 produced by 2B3 was significantly greater than that caused by the IgG. These data indicate that 2B3 binds to APP in mouse neurones and can inhibit A40, similar to our previous findings. The antibody is probably therefore acting by steric hindrance of -secretase and these data suggest that it will be effective in mice in vivoand could be an alternative potential therapy for Alzheimer’s disease.