Circulating ether‐lipids as an early marker of POAG

Abstract

Abstract 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. Conclusion 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.