Role of granulysin in MDP-induced PGE2 production in human monocytes (68.2)

Abstract

Abstract Muramyl dipeptide (MDP) is a NOD2 agonist known to induce pyrogenic response in vivo in humans and in animal models. The mechanism of MDP-induced fever was studied in vitro in human primary cells by measuring PGE2, a final mediator of febrile response. Elutriated monocytes produced significant levels of PGE2 following stimulation with LPS but not MDP. However, addition of human CD3 bead-purified T cells significantly augmented COX2 mRNA expression and PGE2 protein production in MDP-activated monocytes. PI3 kinase inhibitor LY294002 and ROS inhibitor DPI all inhibited PGE2 production and COX2 mRNA up-regulation. Studies using trans-well system confirmed that PGE2 production in MDP-activated monocytes did not require direct cell to cell contact between monocytes and T cells. Anti-IFN gamma antibodies did not inhibit the effect of T cells suggesting that factor(s) other than IFN gamma play a role in MDP-induced PGE2 production in monocytes. Jurkat cells did not deliver the missing factor required for PGE2 production in MDP-activated monocytes. cDNA microarray analysis revealed high levels of Granulysin (GNLY) mRNA expression in bead-purified T cells but not in Jurkat cells. Recombinant GNLY induced high levels of PGE2 in monocytes activated with MDP and the effect of GNLY was sensitive to ROS and PI3K inhibitors. In conclusion, our data suggest that GNLY might be one of the molecules that are produced by T cells and contribute to PGE2 production by MDP-activated monocytes.