The oxysterol 27-hydroxycholesterol increases β-amyloid and oxidative stress in retinal pigment epithelial cells.

Abstract

BACKGROUND:

Alzheimer's disease (AD) and age-related macular degeneration (AMD) share several pathological features including β-amyloid (Aβ) peptide accumulation, oxidative damage, and cell death. The causes of AD and AMD are not known but several studies suggest disturbances in cholesterol metabolism as a culprit of these diseases. We have recently shown that the cholesterol oxidation metabolite 27-hydroxycholesterol (27-OHC) causes AD-like pathology in human neuroblastoma SH-SY5Y cells and in organotypic hippocampal slices. However, the extent to which and the mechanisms by which 27-OHC may also cause pathological hallmarks related to AMD are ill-defined. In this study, the effects of 27-OHC on AMD-related pathology were determined in ARPE-19 cells. These cells have structural and functional properties relevant to retinal pigmented epithelial cells, a target in the course of AMD.

METHODS:

ARPE-19 cells were treated with 0, 10 or 25 μM 27-OHC for 24 hours. Levels of Aβ peptide, mitochondrial and endoplasmic reticulum (ER) stress markers, Ca2+ homeostasis, glutathione depletion, reactive oxygen species (ROS) generation, inflammation and cell death were assessed using ELISA, Western blot, immunocytochemistry, and specific assays.

RESULTS:

27-OHC dose-dependently increased Aβ peptide production, increased levels of ER stress specific markers caspase 12 and gadd153 (also called CHOP), reduced mitochondrial membrane potential, triggered Ca2+ dyshomeostasis, increased levels of the nuclear factor κB (NFκB) and heme-oxygenase 1 (HO-1), two proteins activated by oxidative stress. Additionally, 27-OHC caused glutathione depletion, ROS generation, inflammation and apoptotic-mediated cell death.

CONCLUSIONS:

The cholesterol metabolite 27-OHC is toxic to RPE cells. The deleterious effects of this oxysterol ranged from Aβ accumulation to oxidative cell damage. Our results suggest that high levels of 27-OHC may represent a common pathogenic factor for both AMD and AD.

• Authors: Bhanu Dasari, Jaya R P Prasanthi, Gurdeep Marwarha, Brij B Singh, Othman Ghribi
• Journal: BMC ophthalmology (BMC Ophthalmol) Vol. 10 Pg. 22 (Sep 13 2010) ISSN: 1471-2415 [Electronic] England
• PMID: 20836858 (Publication Type: Comparative Study, Journal Article, Research Support, N.I.H., Extramural)

Chemical References

• Amyloid beta-Peptides
• Hydroxycholesterols
• Reactive Oxygen Species
• 27-hydroxycholesterol
• Cholesterol
• Calcium

Topics

• Alzheimer Disease (metabolism)
• Amyloid beta-Peptides (metabolism)
• Blotting, Western
• Calcium (metabolism)
• Cells, Cultured
• Cholesterol (metabolism)
• Enzyme-Linked Immunosorbent Assay
• Humans
• Hydroxycholesterols (pharmacology)
• Immunohistochemistry
• Macular Degeneration (metabolism, pathology)
• Microscopy, Confocal
• Oxidative Stress (drug effects)
• Reactive Oxygen Species (metabolism)
• Retinal Pigment Epithelium (metabolism, pathology)