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RESEARCH PRODUCT

Alteration of plasmalogens in erythrocytes of patients with diabetic retinopathy

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Purpose Plasmalogens are phospholipids characterized by a vinyl ether bond and the preferential esterification of polyunsaturated fatty acids (PUFA). We have shown that the lack of plasmalogens leads to abnormal retinal vascularisation. Because we hypothesize that plasmalogens are negative regulators of vascular development, we aimed to check their circulating levels in patients having a retinal pathology with vascular proliferation. Methods Blood samples were collected from 4 control subjects and 42 patients having proliferative or non-proliferative diabetic retinopathy (DR). Patients were classified according to the stage of DR. The plasmalogen content and the fatty acid composition of erythrocyte phospholipids were determined using gas chromatography. Individual species of phospholipids, including plasmalogens, were quantified by liquid chromatography coupled with a triple quadrupole mass spectrometer (HPLC-ESI+MS/MS). Results Gas chromatographic analyzes did not reveal any change in plasmalogens. The analysis of individual species of phospholipids by HPLC-ESI+MS/MS showed reduced levels of plasmalogens in patients with DR. Five species of plasmalogens having PUFA were at reduced concentrations in erythrocytes of DR patients. In parallel, the amounts of conventional phospholipids having docosahexaenoic acid (DHA) were altered in DR patients when compared to control subjects. Conclusion Mechanisms responsible for the reduction in blood levels of plasmalogens and DHA in patients with DR are unknown. Since erythrocyte membrane lipid composition is admitted to reflect the lipid composition of nervous tissues, including the retina, one may suggest that DR patients have altered retinal concentrations of plasmalogens and DHA.