Abstract
Purpose :
Aβ42, an end product of the amyloidogenic pathway, is a component of drusen in age-related macular degeneration (AMD) and of senile plaques in Alzheimer’s disease (AD). In AMD, Aβ contributes to the chronic inflammation and the alteration of morphology and function in the retinal pigment epithelial (RPE) and retina as well as the activation of senescence signaling. A previous study showed that Elovanoids (ELVs) counteract Aβ-peptide-induced senescence progression (Do KV et al., PNAS, 2019). We hypothesize that ELVs and NPD1 deter formation of amyloid-β towards the prosurvival sAPPa and inhibit senescence-associated secretory phenotype (SASP) in primary human RPE cells.
Methods :
Plasmid construct containing Swedish double mutant APP protein (APPsw), which dominantly produces sAPPβ (a precursor of amyloid beta), was transfected into human RPE cells. After 24h, ELVs alone, NPD1 alone or the combination of ELVs and NPD1 were added at 500nM concentrations in sAPPβ overexpressed cells. After 24h and 48h of treatment, the medium were collected, precipitated and subjected to the Western Blots for holo-APP precursor, sAPPβ for amyloidogenic pathway, and sAPPα for non-amyloidogenic pathway. The cellular samples are also collected for α-secretase (ADAM10), β-secretase (BACE1) and γ-secretase (PS1) measurement. eGFP transfected cells were used as negative controls. Finally, the cells were fixed for β-galactosidase staining.
Results :
At 24h, higher sAPPα production was observed in the ELV treatment. At 48h, higher sAPPα production was observed in the NPD1 treatment. In contrast, reverse production of sAPPβ was observed, lower level with ELV treatment 24h and with NPD1 at 48h. An equal amount of holo-APP, regarded as total of all sAPP forms, was detected in all studied conditions. The mechanisms involve the increase of α-secretase (ADAM10) and decrease of β-secretase (BACE1) by ELVs and NPD1. As a result, these two lipid mediators suppress the OAβ-induced senescence phenotype, which was demonstrated by the β-galactosidase staining assay.
Conclusions :
ELVs and NPD1 shift the amyloidogenic pathway to the non-amyloidogenic pathway and protect the human RPE cells from senescence, which is activated by overexpression in Swedish double mutant APP.
This is a 2020 ARVO Annual Meeting abstract.