Lipid Composition of the Human Eye: Are Red Blood Cells a Good Mirror of Retinal and Optic Nerve Fatty Acids?

International audienceBACKGROUND: The assessment of blood lipids is very frequent in clinical research as it is assumed to reflect the lipid composition of peripheral tissues. Even well accepted such relationships have never been clearly established. This is particularly true in ophthalmology where the use of blood lipids has become very common following recent data linking lipid intake to ocular health and disease. In the present study, we wanted to determine in humans whether a lipidomic approach based on red blood cells could reveal associations between circulating and tissue lipid profiles. To check if the analytical sensitivity may be of importance in such analyses, we have used a double approach for lipidomics. METHODOLOGY AND PRINCIPAL FINDINGS: Red blood cells, retinas and optic nerves were collected from 9 human donors. The lipidomic analyses on tissues consisted in gas chromatography and liquid chromatography coupled to an electrospray ionization source-mass spectrometer (LC-ESI-MS). Gas chromatography did not reveal any relevant association between circulating and ocular fatty acids except for arachidonic acid whose circulating amounts were positively associated with its levels in the retina and in the optic nerve. In contrast, several significant associations emerged from LC-ESI-MS analyses. Particularly, lipid entities in red blood cells were positively or negatively associated with representative pools of retinal docosahexaenoic acid (DHA), retinal very-long chain polyunsaturated fatty acids (VLC-PUFA) or optic nerve plasmalogens. CONCLUSIONS AND SIGNIFICANCE: LC-ESI-MS is more appropriate than gas chromatography for lipidomics on red blood cells, and further extrapolation to ocular lipids. The several individual lipid species we have identified are good candidates to represent circulating biomarkers of ocular lipids. However, further investigation is needed before considering them as indexes of disease risk and before using them in clinical studies on optic nerve neuropathies or retinal diseases displaying photoreceptors degeneration

Long-chain polyunsaturated fatty acid (LCPUFA) supplementation for infants born preterm

Copyright © 2007 by the American Academy of Pediatrics.During gestation, the placenta actively enriches the fetal circulation with long-chain polyunsaturated fatty acids (LCPUFA), and significant quantities are concentrated in brain and retinal tissues. Preterm infants are denied the usual gestational accretion of LCPUFA, prompting the addition of these fatty acids to preterm formula. Electrophysiologic assessment of visual maturation has shown improved retinal sensitivity and visual acuity with LCPUFA formula supplementation, although the optimal dose has not been determined. Developmental assessment trials of infants fed LCPUFA-supplemented formulas have shown varied results, as have trials assessing the growth of infants fed such formulas. Comparative trials have shown no increased incidence of sepsis, necrotizing enterocolitis, or bronchopulmonary dysplasia among preterm infants fed LCPUFA-supplemented formulas. Further research is required to determine the overall balance of LCPUFA in the diets of preterm infants fed either human milk or infant formula.Lisa G. Smithers; Robert A. Gibson; Maria Makride

Developmental sensitivity of the piglet brain to docosahexanoic acid

Human formula-fed infants have a lower concentration of docosahexanoic acid (DHA) in cerebral cortex compared with breast-fed infants. It is uncertain whether this biochemical deficit is reversible in later infancy. We used a piglet model to determine whether a critical window exists for the deposition of DHA in cerebral cortex during early postnatal development. Milk formula supplemented with DHA was fed to piglets for one of two 14-day periods commencing at either 2 or 16 d of life (early or late supplementation). Comparison of cortical DHA levels in response to supplemented formula was made with age-matched piglets receiving a control formula devoid of DHA. The level of DHA incorporated into whole brain during supplemented formula-feeding seemed to be less with increasing postnatal age. However, when cerebral cortex was examined, dietary DHA was efficiently incorporated during both early and late supplementation periods. Thus, analysis of whole brain was misleading, emphasizing the need to consider the effect of myelination when interpreting developmental changes in brain fatty acids. We conclude that the piglet cerebral cortex is responsive to dietary DHA during the postnatal phase of the brain growth spurt. The lower cortical DHA levels of human formula-fed infants may, therefore, be reversible in later infancy. Plasma phospholipid DHA levels were approximately doubled and liver phospholipid DHA levels increased 50% relative to starting values during control formula-feeding. This suggests a higher rate of DHA synthesis in the piglet in comparison with the human infant, which may be an important limitation of the piglet model.Scott A Morris, Karen N Simmer, Robert Van Barneveld, and Robert A Gibso