Anti-inflammatory effect of docosahexaenoic acid on cytokine-induced adhesion molecule expression in human retinal vascular endothelial cells.
OBJECTIVE
Docosahexaenoic acid (DHA(22:6n3)), the principal n3-polyunsaturated fatty acid (PUFA) in the retina, has been shown to have a pronounced anti-inflammatory effect in numerous in vivo and in vitro studies. Despite the importance of vascular inflammation in diabetic retinopathy, the anti-inflammatory role of DHA(22:6n3) in cytokine-stimulated human retinal vascular endothelial cells (hRVECs) has not been addressed.


METHODS
Cytokine-induced expression of cell adhesion molecules (CAMs) was assessed by Western blot. The effect of DHA(22:6n3) on cytokine-induced nuclear factor (NF)-kappaB signaling was analyzed by Western blot analysis and electrophoretic mobility shift assay (EMSA).


RESULTS
Stimulation of hRVECs with VEGF(165), TNFalpha, or IL-1beta for 6 to 24 hours caused significant induction of intracellular adhesion molecule (ICAM)-1 and vascular cell adhesion molecule (VCAM)-1 expression. Pretreatment of the cells with 100 microM of BSA-bound DHA(22:6n3) for 24 hours remarkably inhibited cytokine-induced CAM expression. IL-1beta, TNFalpha, and VEGF(165) induced nuclear translocation and binding of p65 and p50 NF-kappaB isoforms to the VCAM-1 promoter. DHA(22:6n3) pretreatment inhibited cytokine-induced NF-kappaB binding by 25% to 40%. Moreover, DHA(22:6n3) diminished IL-1beta induced phosphorylation of the inhibitor of nuclear factor (NF)-kappaB (I-kappaBalpha), thus preventing its degradation.


CONCLUSIONS
IL-1beta, TNFalpha, and VEGF(165) induced CAM expression in hRVECs through activation of the NF-kappaB pathway. DHA(22:6n3) inhibited cytokine induced CAM expression through suppression of NF-kappaB nuclear translocation and upstream I-kappaBalpha phosphorylation and degradation. DHA(22:6n3) could be an important anti-inflammatory agent in the face of increased cytokine production and CAM expression in the diabetic retina.
Chen
Weiqin
W
Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, 48824, USA.
Esselman
Walter J
WJ
Jump
Donald B
DB
Busik
Julia V
JV
D015153:Blotting, Western; D015815:Cell Adhesion Molecules / Q000378:metabolism*; D016207:Cytokines / Q000494:pharmacology*; D004281:Docosahexaenoic Acids / Q000494:pharmacology*; D004591:Electrophoresis, Polyacrylamide Gel; D024202:Electrophoretic Mobility Shift Assay; D004730:Endothelium, Vascular / Q000187:drug effects*; D006801:Humans; D007375:Interleukin-1 / Q000494:pharmacology; D016328:NF-kappa B / Q000378:metabolism; D010766:Phosphorylation; D012171:Retinal Vessels; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology; D042461:Vascular Endothelial Growth Factor A / Q000494:pharmacology
D015815:Cell Adhesion Molecules; D016207:Cytokines; D007375:Interleukin-1; D016328:NF-kappa B; D014409:Tumor Necrosis Factor-alpha; D042461:Vascular Endothelial Growth Factor A; D004281:Docosahexaenoic Acids