Products of the cyclooxygenase (COX) have been directly implicated in both inflammatory and thrombotic disease. However, predominant products of the COX enzymes vary between cells and have contrasting biology. A combined genetic and pharmacological approach will be used to elucidate the role of discrete COX products in atherosclerosis, thrombosis and hypertension in vivo. We shall use mutants in a synthesis/response pathway of established significance in inflammation to conduct a genomic and proteomic interrogation of the response to inflammatory and oxidant stimuli in vascular cells. Versatile biomarkers of inflammation and oxidant stress will be combined with lipidomic analyses to integrate the divergent impact of receptor deletion on atherosclerosis in vivo with the mechanistic studies in vitro.
In Specific Aim 1 we shall assess the relevance of PGI2 and PGE2, to the cardiovascular consequences of COX-2 inhibition in vivo. The effect of systemic inhibition of COX-2 in modulating the response to thrombogenic and hypertensive stimuli will be compared with the impact of hetero and homozygous deletion alone and together, of the IP, the EP2 and the EP4.
In Specific Aim 2 we shall assess the role of PGE2 in the promotion of atherosclerosis. The effects of deletion of microsomal PGE synthase (mPGES) on atherosclerosis progression and regression will be compared with that of EP2 and EP4 deletion. The impact of mPGES and EP deletion on oxidant stress, chemokine release and platelet activation will be compared with that of IP deletion and antagonism. Deletion of PG deydrogenase will be utilized to assess the impact of elevating endogenous PGE2 on atherogenesis. In Specifie Aim 3 we shall address comprehensively the cardiovascular biology of PGs of the D, J and F series in vivo. Mast cells and platelets express predominantly DP1, but the chemoattractant DP2 (CRTH2) is coexpressed with DP1 on Th2 and Tc2 lymphocytes, basophils and eosinophils. While both receptor subtypes express similar affinity for PGD2, only CRTH2 expresses affinity for the COX-2 derivative, 15-deoxy PGJ2 that correspond to the concentrations formed in vivo. Mice deficient in DP1 and DP2 (CRTH2) receptors alone and together will be combined with selective receptor subtype antagonism to clarify the role of PGD2 and 15-deoxy PGJ2 in development and regression of atherosclerosis. We shall also address the role of FP activation in atherosclerosis and the functional redundancy between the FP and the TP in vivo. Finally, in Specific Aim 4, we shall assess the impact of deleting pro- (TP, EP1) and anti- (IP, EP4) inflammatory prostanoid receptors on modulating the integrated genomic and proteomic response to oxidant and inflammatory stimuli and its metabolic consequences. We shall use an array of PG products, cytokines and markers of oxidant stress to integrate these observations with the consequences of deleting the same receptors on atherosclerosis in vivo.
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