Pomegranate juice (PJ) consumption antioxidative properties on mouse macrophages, but not PJ beneficial effects on macrophage cholesterol and triglyceride metabolism, are mediated via PJ-induced stimulation of macrophage PON2

ObjectiveTo examine whether the beneficial effects of PJ consumption by mice on their macrophages are mediated via PJ-induced increment in serum paraoxonase 1 (PON1) activity and/or in macrophage PON2 expression.Methods and resultsWe performed studies in peritoneal macrophages (MPM) from C57BL/6 control mice, or from PON1KO mice, or from PON2KO mice that consumed PJ (200 μg of gallic acid equivalents/mouse/day, for 1 month period).PJ consumption by C57BL/6 mice resulted in a significant increment, by 36% in serum PON1 catalytic activities, and upregulated MPM PON2 expression.In MPM from C57BL/6 or from PON1KO mice that consumed PJ, the extent of cell-mediated LDL oxidation was decreased by 22%, and that of cellular superoxide release by 20–26%. In contrast, PJ consumption by PON2KO mice resulted in a minimal inhibitory effect on macrophage oxidative stress by only 4–9%. Unlike PJ antioxidative effects in MPM, PJ anti-atherogenic effects on MPM cholesterol and triglyceride metabolism were similar in all mice groups that consumed PJ. After PJ consumption, cellular cholesterol content was decreased by 14–19%, and this could be attributed to a significant inhibition in MPM cholesterol biosynthesis rate by 20–32%, and/or to stimulation of HDL-mediated cholesterol efflux from the cells by 22–37%. Similarly, MPM triglyceride content and triglyceride biosynthesis rate were both significantly decreased after PJ consumption, by 16–27% and by 22–28%, respectively.ConclusionPJ consumption antioxidative properties on mouse macrophages, but not PJ beneficial effects on macrophage cholesterol and triglyceride metabolism, are mediated via PJ-induced stimulation of macrophage PON2 expression. Serum PON1 stimulation by PJ consumption, however, was not involved in PJ-induced effects on macrophages.