Amyloid precursor protein processing and inflammatory markers modulated by pulsatile stretch of human cerebral endothelial cells

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Abstract

Objective: Amyloid β (Aβ), a hallmark of Alzheimer’s disease, is generated via enzymatic cleavage of amyloid precursor protein (APP). Increased APP expression is associated with elevated amyloid burden. Markers associated with vascular stiffness such as increased pulsatility, inflammation and endothelial dysfunction are associated with Alzheimer’s disease. This study investigated whether pulsatile stretch of human cerebral microvascular endothelial cells (hCMEC) alters expression of key proteins involved in amyloid deposition (APP), inflammation (intercellular cell adhesion molecule-1, ICAM-1) and endothelial dysfunction (endothelial nitric oxide synthase, eNOS). Design and Method: hCMECs were subjected to 5%, 10% or 15% magnitude cyclic stretch for 18 hours at 1 Hz and were compared to the control (0% stretch) using RT-qPCR and/ or western blots (n = 5–10). Secreted Aβ42 in the cell culture supernatants was measured by ELISA (n = 8–10) while LDH activity being measured using a commercial LDH assay kit (n = 7–9). Results: APP mRNA was significantly higher than the static control (104 ± 17%) at 5% (211 ± 35%, P = 0.001), 10% (199 ± 19%, P = 0.01) and 15% (242 ± 17%, P = 0.0001) but with minimal change in eNOS mRNA. APP protein expression was significantly higher at 10% of cyclic stretch magnitude (161 ± 21%, P = 0.05) compared to both the static control (100%) and 5% cyclic stretch magnitude (108 ± 12%). Protein expression of eNOS was significantly higher at 15% stretch magnitude (362 ± 63%) relative to 0% (100%; P = 0.001), 5% (190 ± 49%, P = 0.05) and 10% (130 ± 18%, P = 0.01) cyclic stretch magnitude. In contrast, ICAM-1 protein expression at cyclic stretch magnitudes of 10% (124.8 ± 10%, P = 0.05) and 15% (128 ± 15%, P = 0.05) was significantly higher than at 5% cyclic stretch magnitude (87 ± 9%). Aβ42 levels in the supernatant had a positive linear relationship with increased stretch magnitude (P = 0.01). There was no relationship of LDH activity with cell stretch, with maximum cell death being 8% of the initial seeding density. Conclusions: Increasing cyclic stretch of cerebral vascular ECs altered the expression of APP and the secretion of Aβ42. Findings mechanistically support the association of elevated vascular pulsatility and stiffness with Alzheimer’s disease.
Original languageEnglish
Article numberO-05
Pages (from-to)110-111
Number of pages2
JournalPulse (Basel, Switzerland)
Volume4
Publication statusPublished - 2016
EventThe Pulse of Asia 2016 - Seoul, Korea, Republic of
Duration: 24 Sep 201626 Sep 2016

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