Coffee effects on reverse-cholesterol transport ‘could reduce atherosclerosis’
MedWire News: Compounds found in coffee significantly increase the expression of proteins involved in reverse-cholesterol transport, say scientists who believe regular coffee drinking may decrease the risk for atherogenesis.
Previous research has shown that regular coffee consumption can decrease the risk for death from cardiovascular disease, probably because of the antioxidant phenolic compounds they contain.
Indeed, it has recently been demonstrated that the caffeic and ferulic acids found in coffee inhibit the development of atherosclerosis in mice via their ability to attenuate inflammation.
For the present study, Katsunori Ikewaki (National Defence Medical College, Saitama, Japan), and co-workers investigated the effects of coffee phenolic acids on reverse-cholesterol transport from macrophages in vivo in mice, as well as in cells isolated from healthy human volunteers.
In vitro analysis revealed that both caffeic acid and ferulic acid significantly enhanced the efflux of cholesterol mediated by high-density lipoprotein cholesterol (HDL) cholesterol from cultured THP-1 macrophages. Interestingly, the efflux of apolipoprotein (apo)A-I was not significantly altered by caffeic or ferulic acid exposure.
These observations were explained by the finding that both phenolic acids increased the expression of the ATP-binding cassette transporter (ABC)G1 and scavenger receptor class B type I (SRBI), both of which enhance HDL-cholesterol-mediated cholesterol efflux from macrophages but not the efflux of apoA-I. These changes were seen in vitro and in cells from human blood samples taken 30 minutes before and after drinking coffee.
The investigators also traced labelled cholesterol in mice and found increased cholesterol excretion in the feces after administration of ferulic acid, confirming that phenolic coffee compounds not only increase the first efflux step of reverse-cholesterol transport but also enhance the entire reverse-cholesterol transport process.
“Coffee intake has an anti-atherogenic effect on HDL cholesterol by increasing ABCG1 and SRBI expression and enhancing HDL-mediated cholesterol efflux from the macrophages by its plasma phenolic acids,” summarize the researchers in the journal Circulation Research.
“In addition to the anti-oxidative properties, the potential cardioprotective properties of coffee might therefore be associated with an enhanced anti-atherogenic function of HDL cholesterol,” they conclude.
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By Philip Ford