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J.V. Busik, W. Chen, D.B. Jump, W.J. Esselman; Modification of Caveolae/Lipid Rafts by Docosahexaenoic Acid Inhibits Inflammatory Signaling in Human Retinal Endothelial Cells . Invest. Ophthalmol. Vis. Sci. 2006;47(13):1720.
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© ARVO (1962-2015); The Authors (2016-present)
Docosahexaenoic acid (DHA, 22:6,n3) is the principal n3 polyunsaturated fatty acid (PUFA) in the retina. We have previously demonstrated that DHA inhibited cytokine induced adhesion molecule expression in primary human retinal vascular endothelial (hRVE) cells, the target tissue affected by diabetic retinopathy. Despite the importance of vascular inflammation in diabetic retinopathy, the mechanisms underlying anti–inflammatory effects of DHA in vascular endothelial cells are not understood.
hRVE cells were cultured in the presence or absence of DHA. Isolation of caveolae/lipid raft enriched detergent resistant membrane domains were prepared using sucrose gradient ultracentrifugation. Fatty acids composition and cholesterol content of caveolae/lipid rafts before and after treatment was measured by HPLC. The expression Src family kinases was assayed by Western Blotting and immunohistichemistry.
Disruption of the caveolae/lipid raft structure with a cholesterol depleting agent, methyl–cyclodextrin, as well as inhibition of Src family kinases resident in the caveolae/lipid rafts with the inhibitor, PP2, diminished cytokine induced signaling in hRVE cells. Growth of hRVE cells in media enriched in DHA resulted in significant incorporation of DHA into the major phospholipids of caveolae/lipid rafts, causing an increase in the unsaturation index in the membrane microdomain. Importantly, enrichment of DHA in the caveolae/raft was accompanied by a 70% depletion of cholesterol from caveolae/lipid rafts and displacement of the Scr family kinases, Fyn and c–Yes, from caveolae/lipid rafts.
Incorporation of DHA into fatty acyl chains of phospholipids in caveolae/lipid rafts, followed by cholesterol depletion and displacement of important signaling molecules provides a potential mechanism for anti–inflammatory effect of DHA in hRVE cells.
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