Author(s)

Amira Zarrouk^1,2, Thomas Nury², Mohamed Hammami¹, Gérard Lizard²

¹Laboratoire de Biochimie (LR12ES05)-Lab-NAFS “Nutrition, Aliments Fonctionnels et Santé Vasculaire”, Faculté de Médecine, Université de Monastir, Monastir, Tunisie.
²Equipe “Biochimie du Peroxysome, Inflammation et Métabolisme Lipidique” (EA 7270), Université de Bourgogne-Franche Comté/INSERM, Dijon, France.

Amyloid peptide, the main component of senile plaques, is a major biological characteristic of Alzheimer’s disease (AD). The aim of the present study conducted on human neuronal SK-N-BE cells was to evaluate whether oligomerized Aβ_1-40-induced cell damages was associated with lipid modifications. Under treatment with Aβ_1-40 (10 - 100 μM; 24 - 48 h), cell viability was recorded with the MTT test and by measuring LDH activity. Mitochondrial transmembrane potential and ATP production were assessed using flow cytometry and a luciferase-based ATP bioluminescence assay, respectively. Annexin V-CF647 staining assay for cell apoptosis detection was performed using flow cytometry. Potentially intracellular cytotoxic lipids (oxysterols: 7α-hydroxycholesterol (7α-OHC), 7β-hydroxycholesterol (7β-OHC), and 7-ketocholesterol (7KC), 24(S)-hydroxycholesterol; arachidonic acid (C20:4 n-6); VLCFAs (C22:0, C24:0, C24:6 and C26:0)) were measured using gas chromatography coupled with mass spectrometry. The cellular level of docosahexaenoic acid (C22:6 n-3), often altered in AD, was also quantified. In the presence of Aβ_1-40, the percentage of MTT-positive cells decreased and was associated with an increase in LDH activity. In addition, treatment with oligomerized Aβ_1-40 induced a decrease of mitochondrial transmembrane potential as well as an apoptotic cell death. Sterol analysis revealed a higher cholesterol level and a significant increase of cytotoxic oxysterols per cell (7KC + 7β-OHC), and of the [(7β-OHC + 7KC)/cholesterol] ratio, considered as a lipid peroxidation index, in Aβ_1-40-treated cells. An enhancement of C20:4 n-6, C22:6 n-3 and saturated VLCFAs was also observed. Therefore, Aβ_1-40-induced side effects are associated with intracellular accumulation of lipids, especially cholesterol, oxysterols (7β-OHC, 7KC), C20:4 n-6, and saturated VLCFAs, which could in turn contribute to neurotoxicity.

SK-N-BE Cells, Oligomerized Aβ_1-40, Cholesterol, Oxysterols, Very Long Chain Fatty Acids

Zarrouk, A. , Nury, T. , Hammami, M. and Lizard, G. (2015) Oligomerized Amyloid-β_1-40 Peptide Favors Cholesterol, Oxysterol, and Fatty Acid Accumulation in Human Neuronal SK-N-BE Cells. International Journal of Clinical Medicine, 6, 813-824. doi: 10.4236/ijcm.2015.611107.