IL-2 Suppression by Endocannabinoid Activation of PPARgamma

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DESCRIPTION (provided by applicant): The overall goal of this 5 year research plan is to elucidate the molecular mechanism responsible for the modulation of T cell function and interleukin-2 (IL-2) deregulation by the structurally-related endocannabinoids, anandamide (AEA) and 2-arachidonyl glycerol (2-AG). Presently, the teleological role of the endocannabinoid system is unknown but there is a growing body of evidence suggesting that it may significantly contribute to the maintenance of immunologic homeostasis. Numerous studies have demonstrated profound effects on biological systems by AEA and 2-AG, with the immune system representing one of the most extensively characterized. The significance of the current proposed studies is that they will provide direct mechanistic insight into the molecular mechanism by which endocannabinoids modulate T cell function, specifically IL-2 regulation. Novel preliminary results are presented demonstrating that IL-2 suppression by both AEA and 2-AG are dependent on COX-2 metabolism leading to the activation of the nuclear receptor, peroxisome proliferator activated receptor gamma (PPARgamma), independently of CB1 and CB2. Additional results are present suggesting that the specific mechanism involves the disruption of the nuclear factor of activated T cells (NFAT) by PPARgamma activation. Based on the observations described above and other preliminary data presented in the proposal, our present investigation will test the hypothesis: Suppression of IL-2 by the endocannabinoids, AEA and 2-AG, is mediated through disruption of NFAT regulation by two distinct cannabinoid receptor-independent mechanisms: (a) altered intracellular calcium regulation; and (b) activation of PPARgamma following COX-2-mediated conversion of AEA and 2-AG into PPARgamma agonists. We will test our hypothesis using the following specific aims (SA): SA1 is to characterize the role altered intracellular calcium regulation by AEA and 2-AG plays in deregulation of NFAT and, consequently, suppression of IL-2 gene expression; SA2 is to characterize the role of COX-2 on the deregulation of NFAT and suppression of IL-2 by AEA and 2-AG; SA3 is to characterize the role of PPARgamma activation by AEA and 2-AG treatment in altered NFAT regulation and suppression of IL-2; and SA4 is to identify and characterize the bioactive forms of AEA and 2-AG responsible for PPARgamma activation and to elucidate its contribution to IL- 2 suppression.