Sitagliptin promotes macrophage-to-faeces reverse cholesterol transport through reduced intestinal cholesterol absorption in obese insulin resistant CETP-apoB100 transgenic mice

Dipeptidyl peptidase-4 inhibitors (DPP-4i) improve glycaemic control in type 2 diabetes, but their benefits on reverse cholesterol transport (RCT) remain unknown. We evaluated the effects of DPP-4i sitagliptin 500 mg/kg/day on RCT in obese insulin-resistant CETP-apoB100 transgenic mice. Metformin 300 mg/kg/day orally was used as a reference compound. Both metformin and sitagliptin showed the expected effects on glucose parameters. Although no significant effect was observed on total cholesterol and high-density lipoprotein (HDL) cholesterol levels, sitagliptin, but not metformin, increased faecal cholesterol mass excretion by 132% (p < 0.001 vs. vehicle), suggesting a potent effect on cholesterol metabolism. Mice were then injected i.p. with 3H-cholesterol labelled macrophages to measure RCT over 48 h. Compared with vehicle, sitagliptin significantly increased macrophage-derived 3H-cholesterol faecal excretion by 39%. Administration of 14C-cholesterol labelled olive oil orally showed a significant reduction of 14C-tracer plasma appearance over time with sitagliptin, indicating that this drug promotes RCT through reduced intestinal cholesterol absorption.