SCOPE:
To investigate whether docosahexaenoic acid (DHA) could inhibit linoleic acid (LA) induced monocyte chemoattractant protein (MCP)-1 expression in human retinal pigment epithelial (RPE) cells.

METHODS AND RESULTS:
ARPE-19 cells were pretreated with DHA and then exposed to LA. The expression of MCP-1 and PPARγ was examined using RT-PCR and Western blot analysis. LA at 10, 25, or 50 μM induced expression of MCP ARPE-19 cells in a dose-dependent manner (p < 0.05). DHA at 50 and 100 μM effectively inhibited LA-induced MCP-1 expression and production (p < 0.05) and NF-κB activation. In addition, the culture medium from LA-stimulated ARPE-19 cells could induce tube formation in choroidal endothelial cells (RF6A), whereas 100 μM DHA inhibited tube formation. DHA at 100 μM increased the expression and activity of PPARγ (p < 0.05). Pretreatment with PPARγ inhibitor (GW9662) abolished the inhibitory effect of DHA (100 μM) on LA-induced IκB degradation, p65 translocation, and MCP-1 expression in ARPE-19 cells (p < 0.05), as well as tube formation in RF6A.

CONCLUSION:
DHA reduced LA-induced MCP-1 expression via a PPARγ- and NF-κB-dependent pathway in ARPE-19 cells. These results suggest the molecular mechanisms underlying the beneficial effects of increased consumption of DHA and reduced consumption of LA on age-related macular degeneration.