Alterations in the Levels of Amyloid-β, Phospholipid Hydroperoxide, and Plasmalogen in the Blood of Patients with Alzheimer’s Disease: Possible Interactions between Amyloid-β and These Lipids

Article type: Research Article

Authors: Yamashita, Shinji^{a; b} | Kiko, Takehiro^b | Fujiwara, Hironori^{c; d} | Hashimoto, Michio^e | Nakagawa, Kiyotaka^{b; *} | Kinoshita, Mikio^a | Furukawa, Katsutoshi^c | Arai, Hiroyuki^c | Miyazawa, Teruo^{b; f; g}

Affiliations: [a] Department of Food Science, Obihiro University of Agriculture and Veterinary Medicine, Obihiro, Japan | [b] Food and Biodynamic Chemistry Laboratory, Graduate School of Agricultural Science, Tohoku University, Sendai, Japan | [c] Department of Geriatrics and Gerontology, Institute of Development, Aging and Cancer, Tohoku University, Sendai, Japan | [d] Institute of Natural Medicine, University of Toyama, Toyama, Japan | [e] Department of Environmental Physiology, Shimane University Faculty of Medicine, Izumo, Japan | [f] Food and Biotechnology Innovation Project, New Industry Creation Hatchery Center (NICHe), Tohoku University, Sendai, Japan | [g] Food and Health Science Research Unit, Graduate School of Agricultural Science, Tohoku University, Sendai, Japan

Correspondence: [*] Correspondence to: Kiyotaka Nakagawa, PhD, Food and Biodynamic Chemistry Laboratory, Graduate School of Agricultural Science, Tohoku University, Sendai, Japan. Tel.: +81 22 717 8906; Fax: +81 22 717 8905; E-mail: [email protected].

Abstract: Aside from accumulation of amyloid-β (Aβ) peptide in the brain, Alzheimer’s disease (AD) has been reported as being associated with peroxidation of major phospholipids (e.g., phosphatidylcholine (PtdCho)) and degradation of antioxidative phospholipids (e.g., ethanolamine plasmalogen (PlsEtn)). In addition to its presence in the brain, Aβ is also found in blood; however, there is still little information about the levels of PtdCho hydroperoxide (PCOOH) and PlsEtn in the blood of patients with AD. In this study, by assuming a possible interaction among Aβ, PCOOH, and PlsEtn in blood circulation, we evaluated the levels of these molecules and correlations in blood samples that had been obtained from our former AD study for PCOOH measurement (Kiko et al., J Alzheimers Dis 28, 593-600, 2012). We found that when compared to controls, plasma from patients with AD showed lower concentrations of PlsEtn species, especially PlsEtn bearing the docosahexaenoic acid (DHA) moiety. In addition, lower PlsEtn and higher PCOOH levels were observed in red blood cells (RBCs) of patients with AD. In both AD and control blood samples, RBC PCOOH levels tended to correlate with plasma levels of Aβ40, and each PlsEtn species showed different correlations with plasma Aβ. These results, together with in vitro data suggesting Aβ aggregation due to a decrease in levels of PlsEtn having DHA, led us to deduce that Aβ is involved in alterations in levels of PCOOH and PlsEtn species observed in the blood of patients with AD.

Keywords: Alzheimer’s disease, amyloid-β, phospholipid hydroperoxide, plasmalogen

DOI: 10.3233/JAD-150640

Journal: Journal of Alzheimer's Disease, vol. 50, no. 2, pp. 527-537, 2016