A COX-2 metabolite of the endogenous cannabinoid, 2-arachidonyl glycerol, mediates suppression of IL-2 secretion in activated Jurkat T cells

Previous studies from this laboratory have demonstrated that a COX-2 metabolite of the endogenous cannabinoid, 2-arachidonyl glycerol (2-AG), inhibits IL-2 secretion in activated T cells through PPARγ activation independent of the cannabinoid receptors, CB1/CB2. Because numerous cyclooxygenase (COX) products have been shown to activate PPARγ, the primary purpose of the present studies was to determine the role of COX metabolism in the inhibition of IL-2 secretion by 2-AG. Pretreatment with nonselective and COX-2-specific inhibitors completely abrogated 2-AG-mediated suppression of IL-2 secretion. In contrast, pretreatment with COX-1-specific inhibitors had no effect upon 2-AG-mediated inhibition of IL-2 secretion. Interestingly, the current studies also demonstrate that while the potency of 2-AG is comparable between human Jurkat T cells and murine splenocytes, anandamide (AEA) is markedly more potent in suppressing IL-2 production in Jurkat T cells compared to murine splenocytes. Additionally, the present studies also demonstrate that COX-2 protein is readily detectable in resting Jurkat T cells, which is in contrast to resting murine splenocytes in which COX-2 protein is virtually undetectable. Furthermore, COX-2 protein and mRNA levels are significantly increased over basal levels by 2 h following activation of Jurkat cells, whereas increases in COX-2 protein in murine splenocytes are not observed until 4 h after cellular activation. These studies suggest that the potency of AEA in the suppression of IL-2 secretion may correlate with COX-2 protein levels in different T cell models. The present studies are also significant in that they demonstrate 2-AG-mediated inhibition of IL-2 secretion is dependent upon COX-2 metabolism.