Sitagliptin reduces plaque macrophage content and stabilises arteriosclerotic lesions in Apoe ^sup -/-^ mice

Inhibitors of dipeptidyl peptidase-IV (DPP-IV), such as sitagliptin, increase glucagon-like peptide-1 (GLP-1) concentrations and are current treatment options for patients with type 2 diabetes mellitus. As patients with diabetes exhibit a high risk of developing severe atherosclerosis, we investigated the effect of sitagliptin on atherogenesis in Apoe ^sup -/-^ mice. Apoe ^sup -/-^ mice were fed a high-fat diet and treated with either sitagliptin or placebo for 12 weeks. Plaque size and plaque composition were analysed using Oil Red O staining and immunohistochemistry. Furthermore, in vitro experiments with the modified Boyden chamber and with gelatine zymography were performed to analyse the effects of GLP-1 on isolated human monocyte migration and metalloproteinase-9 (MMP-9) release. Treatment of Apoe ^sup -/-^ mice with sitagliptin significantly reduced plaque macrophage infiltration (the aortic root and aortic arch both showing a 67% decrease; p