Quercetin but not myricetin increases cholesterol efflux in PMA-differenciated human THP-1 macrophages

A low HDL-cholesterol (HDL-C) concentration is an indenpendent risk factor for cardiovascular disease (CVD). In the subendothelial space, macrophages become foam cells following cholesterol accumulation. Circulating HDL particles favor cholesterol excretion by interacting with ATP binding cassette A1 (ABCA1) and G1 (ABCG1) as well as scavenger receptor class B type 1 (SRB1) found on macrophage cell surface. Some studies have suggested that consumption of flavonoid-rich food, such as wine, could be cardioprotective and that a plasma HDL-C increase could explain, at least partly, this effect. Research objective: Study the impact of flavonoids on cholesterol efflux in human THP-1 macrophages. Materials and methods: In PMA-differentiated human THP-1 macrophages, [ 3 H]cholesterol efflux has been measured following flavonoids (quercetine dihydrates, quercetin-3-β-D-glucoside and myricetin) treatments. Furthermore, ABCG1, ABCA1 and SRB1 protein level has also been determined by polyacrylamide gel electrophoresis and western blot following different treatments. Results: Significant increases in cholesterol efflux were observed following quercetin but not myricetin treatments. While no significant change was observed in ABCG1 protein level, ABCA1 and SRB1 significantly increased following quercetin treatment. Those results suggest that ABCA1 and SRB1 could be implicated in the increase in cholesterol efflux observed following quercetin treatment in THP-1 macrophages. Present results also suggest that quercetin, but not myricetin, exert a beneficial impact on HDL-C mediated cholesterol efflux in macrophages which could, at least partly, explain the benefits associated with the consumption of flavonoid-rich beverage such as wine. Complementary studies should be performed in order to better understand molecular and cellular mechanism implicated to the increase in cholesterol efflux in human macrophages following quercetin treatment.