The proton-pump inhibitor lansoprazole enhances amyloid beta production

Abstract

A key event in the pathogenesis of Alzheimer's disease (AD) is the accumulation of amyloid-β (Aβ) species in the brain, derived from the sequential cleavage of the amyloid precursor protein (APP) by β- and γ-secretases. Based on a systems biology study to repurpose drugs for AD, we explore the effect of lansoprazole, and other proton-pump inhibitors (PPIs), on Aβ production in AD cellular and animal models. We found that lansoprazole enhances Aβ37, Aβ40 and Aβ42 production and lowers Aβ38 levels on amyloid cell models. Interestingly, acute lansoprazole treatment in wild type and AD transgenic mice promoted higher Aβ40 levels in brain, indicating that lansoprazole may also exacerbate Aβ production in vivo. Overall, our data presents for the first time that PPIs can affect amyloid metabolism, both in vitro and in vivo.

Figure 1. Lansoprazole and similar PPIs increase Aβ levels at 5 µM–50 µM range in AD-like cells.

A, Treatment of PS70 cells with lansoprazole at different concentrations (250 nM–50 µM) for 24 h increased Aβ40 and Aβ42 levels, as measured by ELISA immunoassays (n = 6± SD) p<0.05 (+), p<0.01 (*). B, Similar treatment with omeprazole, pantoprazole and esomeprazole at different concentrations (5 µM–50 µM) also increased Aβ40 and Aβ42 levels (n = 4± SD) p<0.05 (+), p<0.01 (*).

Figure 2. Lansoprazole changes the production levels of several Aβ species.

A, MALDI-MS analysis of Aβ-immunoprecipitated species from conditioned PS70 supernatants. Cells treated with lansoprazole at 50 µM for 24 h showed a significant increase on Aβ42 compared to vehicle spectrum. DAPT treated cells were used as a negative control, showing none Aβ species as expected. B, Western blot analysis of the different Aβ species present in treated PS70 supernatants. A decrease on Aβ38 and increase on Aβ42 was detected in conditioned media of treated cells with lansoprazole at 50 µM for 24 h. Short and long exposures are shown for better visualization. C, Aβ40/42 levels in conditioned media from treated PS70 cells were measured by ELISA immunoassays (n = 3± SD) p<0.01 (*). Cells treated with both lansoprazole at 50 µM and R-flurbiprofen at 200 µM for 24 h displayed reduced Aβ42 levels when compared to lansoprazole-only treated cells, indicating the lansoprazole is capable to counteract the R-flurbiprofen Aβ42 lowering effect. D, Western blot analysis of APP and BACE1 protein levels in total lysates, showing no differences between treated and non-treated cells. A representative experiment is shown (n = 3 independent experiments). E, Western blot analysis of sAPPβ and sAPPα protein levels in conditioned media. The immunoblot shows an increase in sAPPβ in conditioned media from cells treated with lansoprazole. A representative experiment is shown (n = 3 independent experiments).

Figure 3. Lansoprazole raises Aβ40 production in mice.

A, Non-transgenic mice were treated 5 consecutive days with 100 kg/mg of lansoprazole (n = 10). Soluble Aβ40 and Aβ42 from brain extracts were measured by ELISA (n = 10± SD) p<0.05 (+). Lansoprazole increased Aβ40 levels in non-transgenic mice. B, 3xTg-ADwere treated 5 consecutive days with 100 kg/mg of lansoprazole (n = 6). Soluble Aβ40 and Aβ42 from brain extracts were measured by ELISA (n = 6± SD) p<0.05 (+), p<0.01 (*). Lansoprazole increased soluble Aβ40 levels in 3xTg-AD mice in a dose-dependent manner.

Figure 4. Hypothetical mechanisms of lansoprazole on Aβ production.

Aβ peptides are produced from the consecutive cleavage of APP by BACE1 (β-secretase) and γ-secretase. The first cleavage generates soluble APPβ (sAPPβ) and the C99 C-terminal fragment, while the subsequent one releases Aβ peptides and the amyloid precursor protein intracellular domain (AICD). In basal conditions (left), a variety of Aβ species are formed. Conversely, when cells are treated with lansoprazole (right), BACE1 activity could be increased, generating more sAPPβ and C99 fragments and subsequently increasing the overall Aβ production. Lansoprazole also could act as an inverse GSM, shifting the γ–secretase cleavage, augmenting Aβ42 and reducing Aβ38. Together, lansoprazole is able to increase Aβ37, Aβ40 and Aβ42 species and decrease Aβ38.