Circulating plasmalogens in patients with primary open angle glaucoma

Purpose: Neuronal tissues such as the retina contain high amounts of particular phospholipids named “ether-lipids”. Since abnormal blood levels of ether-lipids have been associated with several neurological disorders, we wanted to check whether ether-lipid levels were modified and associated with the severity of POAG. Methods: Blood samples were collected from 41 healthy subjects and 64 POAG patients. Following lipid extraction from erythrocytes, total phospholipids including ether-lipids were isolated using silica cartridges. The fatty acid profile of phospholipids was determined using capillary column gas chromatography (GC). The individual molecular species of phospholipids and ether-lipids were quantified by tandem liquid chromatography-mass spectrometry. Results: The levels of ether-lipids were significantly decreased in glaucoma patients and especially the choline ether-lipid sub-class. The Mean Deviation (MD) value from Humphrey perimetry was negatively correlated to erythrocyte levels of total choline ether-lipids (r²=0.99). The linear regression model predicted that total choline ether-lipid levels started to decrease about 20 years prior to clinical symptoms. Conclusions: Although the mechanisms responsible for the reduction of erythrocyte levels of ether-lipids in POAG patients remains unclear, the known functions of ether-lipids in the protection against oxidative stress make these results very consistent with the pathogenesis of glaucoma