Conjugated linoleic acids can change phagocytosis of human Monocytes/Macrophages by reduction in Cox-2 expression

Prostaglandin E-2 produced endogenously (by cyclooxygenases) can regulate macrophage phagocytosis. Cyclooxygenase activity reduction (mainly through inhibition of inducible Cox-2) can induce PGE(2) synthesis depression and can activate the phagocytosis process. There are no reports in the literature explaining whether conjugated linoleic acid dienes (trans-10, cis-12 CLA and cis-9, trans-11 CLA) modify the phagocytic activity of human macrophages. For the purpose of this study, monocytes were isolated from venous blood, incubated for 7 days with 30 mu M CLAs, and then (in some experiments) LPS (1 mu g/mL) was added to the medium. Subsequently, monocyte/macrophage phagocytosis, NF-kappa B transcription factor activity, Cox-2 and PPAR gamma mRNA expression (and the amounts of Cox-2 and PPAR gamma proteins) and PGE(2) synthesis were determined. Both CLA isomers increased macrophage phagocytosis through inhibition of Cox-2 expression (might by inactivation the NF-kappa B pathway). The inhibition of mRNA Cox-2 expression contributed (particularly with respect to trans-10, cis-12 CLA) to a decrease in protein Cox-2 synthesis and to reduction of prostaglandin E-2 content in the cell. The inhibition of PGE(2) synthesis (by CLA treatment) enhanced the phagocytosis process in macrophages.