The cholesterol content of Western diets plays a major role in the paradoxical increase in high-density lipoprotein cholesterol and upregulates the macrophage reverse cholesterol transport pathway.

Objective: A high-saturated fatty acid- and cholesterol-containing (HFHC) diet is considered to be a major risk factor for cardiovascular disease. The present study aimed to determine the effects of this Western-type diet on high-density lipoprotein (HDL) metabolism and reverse cholesterol transport (RCT) from macrophages to feces.
Methods and Results: Experiments were carried out in mice fed a low-fat, low-cholesterol diet, an HFHC diet, or an HFHC diet without added cholesterol (high-saturated fatty acid and low-cholesterol [HFLC]). The HFHC diet caused a significant increase in plasma cholesterol, HDL cholesterol, and liver cholesterol and enhanced macrophage-derived [(3)H]cholesterol flux to feces by 3- to 4-fold. These effects were greatly reduced in mice fed the HFLC diet. This HFHC diet-mediated induction of RCT was sex independent and was not associated with obesity or insulin resistance. The HFHC diet caused 1.4- and 3-fold increases in [(3)H]cholesterol efflux to plasma and HDL-derived [(3)H]tracer fecal excretion, respectively. Unlike a low-fat, low-cholesterol and HFLC diets, the HFHC diet increased liver ABCG5/G8 expression. The effect of the HFHC diet on fecal macrophage-derived [(3)H]cholesterol excretion was totally blunted in ABCG5/G8-deficient mice.
Conclusion: Despite its deleterious effects on atherosclerosis, the HFHC diet promoted a sustained compensatory macrophage-to-feces RCT. Our data provide direct evidence of the crucial role of dietary cholesterol signaling through liver ABCG5/G8 upregulation in the HFHC diet-mediated induction of macrophage-specific RCT.