Ether-Lipid and Docosahexaenoic Acid (dha) Levels in Erythrocytes of Patients With Glaucoma

Abstract

Purpose: : Neuronal tissues such as the brain and the retina are known to contain elevated amounts of phospholipids with a vinyl-ether double bond (ether-lipids or plasmalogens) as well as high concentrations of long-chain omega-3 polyunsaturated fatty acids (docosahexaenoic acid or DHA). Abnormal blood levels of ether-lipids and DHA have been associated with several neurological disorders such as Alzheimer Disease. Since many observations bring up the idea of pathogenetic similarities between Alzheimer Disease and glaucoma, the aim of our work was to check whether ether-lipid and DHA levels were modified in glaucoma patients.

Methods: : Blood samples were collected from 41 healthy subjects and 43 primary open-angle glaucoma patients. The stage of glaucoma was determined according to the Hodapp and Parrish classification. Erythrocytes were isolated from total blood and then washed with 0.9% NaCl. Following lipid extraction, phospholipids were isolated using silica cartridges. The ether-lipid content and the fatty acid composition of erythrocyte phospholipids were determined using capillary column gas chromatography.

Results: : The levels of ether-lipids were significantly decreased in glaucoma patients and especially those having C18:0, C18:1 n-9 and C18:1 n-7 in the sn-1 position of glycerol. No correlation could be established between erythrocyte ether-lipid levels and the severity of glaucoma. The levels of DHA were increased in early glaucoma patients while they were decreased in moderate and advanced glaucoma when compared to controls. The Mean Deviation (MD) and the Pattern Standard Deviation (PSD) were linearly correlated to erythrocyte DHA levels (r²=0.87 and r²=0.99, respectively).

Conclusions: : The mechanisms responsible for reduction in blood levels of DHA and ether-lipids in patients with glaucoma are not yet elucidated. However, the roles of ether-lipids in the protection against oxidative stress and the possible action of DHA in neuroprotection make these results very consistent with the pathogenesis of glaucoma.

Keywords: clinical laboratory testing • lipids • visual fields