Differential thrombogenesis effects of EPA and DHA mediated by HDL

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Project Summary Epidemiological studies suggest that the consumption of omega-3 polyunsaturated fatty acids (n-3 PUFAs) derived from fish oil, mainly consisting of eicosapentaenoic acid (EPA; 20:5 n-3) and docosahexaenoic acid (DHA; 22:6 n-3), is associated with lower cardiovascular risk. However, interventional clinical trials aimed at reducing cardiovascular incidents by supplementation with n-3 PUFAs have yielded inconsistent results. The mechanisms responsible for the benefit of n-3 PUFAs on cardiovascular risk are still not completely understood. Mounting evidence suggests that in addition to lowering triglycerides, the triglyceride-independent effects of n-3 PUFAs also contribute to their cardiovascular benefits. It is likely that differential effects of EPA and DHA also contribute to the inconsistent clinical results. A head-to-head comparison of the biological effects of EPA and DHA in a relevant population is urgently required. Based on our preliminary data, we hypothesize that EPA and DHA have differential effects on thrombogenesis in patients with atherogenic dyslipidemia that are mediated by the modification of HDL particle function. We propose a proof-of-concept clinical study comparing the biological effects, particularly the thrombogenesis and antiplatelet effects, of an adequate dose of EPA and DHA head-to- head in atherogenic dyslipidemia subjects. We will also examine the mechanism of how HDL particles mediate these antithrombotic effects. Specific Aim1: To test the hypothesis that EPA and DHA differentially affect platelet activation and thrombosis in vivo in subjects with atherogenic dyslipidemia. Human subjects with atherogenic dyslipidemia will be randomized to dietary supplementation with four grams of either EPA or DHA n-3 PUFAs in a single-blinded fashion for eight weeks. At baseline and after the supplementation, various markers of thrombogenesis will be assessed. Specific Aim 2: To test the hypothesis that the effects of n-3 PUFAs on platelets are mediated by the modulation of HDL particle function. At baseline and post n-3 PUFA supplementation, HDL particle composition and HDL functions will be analyzed, respectively. We will further test our hypothesis mechanistically in an HDL-deficient mouse model. HDL-dependent bioactive lipid production will be characterized in both human and mouse studies. These studies will provide insight into a new paradigm of understanding the puzzling clinical evidence of n-3 PUFAs and may ultimately lead to the development of novel therapies to combat cardiometabolic risk.