A Dipeptidyl Peptidase-4 Inhibitor, Des-Fluoro-Sitagliptin, Improves Endothelial Function and Reduces Atherosclerotic Lesion Formation in Apolipoprotein E–Deficient Mice

Abstract

The aim of this study was to investigate the antiatherogenic effects of the dipeptidyl peptidase-4 inhibitor, des-fluoro-sitagliptin (DFS). The new class of anti-type 2 diabetes drugs, dipeptidyl peptidase-4 inhibitors, improves glucose metabolism by increasing levels of active glucagon-like peptide (GLP)-1. Endothelial function was examined by acetylcholine-induced endothelium-dependent vasorelaxation using aortic rings and atherosclerotic lesion development in the entire aorta in apolipoprotein E-deficient mice fed a high-fat diet with or without DFS, and the antiatherogenic effects of DFS were investigated in cultured human macrophages and endothelial cells. Plasma levels of active GLP-1 were measured in patients with or without coronary artery disease. DFS significantly improved endothelial dysfunction (89.9 ± 3.9% vs. 79.2 ± 4.3% relaxation at 10(-4) mol/l acetylcholine, p < 0.05) associated with increased endothelial nitric oxide synthase phosphorylation and reduced atherosclerotic lesion area (17.7% [15.6% to 25.8%] vs. 24.6% [19.3% to 34.6%], p < 0.01) compared with vehicle treatment. In cultured human macrophages, DFS significantly increased GLP-1-induced cytosolic levels of cyclic adenosine monophosphate compared with GLP-1 alone, resulted in inhibiting phosphorylation of c-jun N-terminal kinase and extracellular signal-regulated kinase 1/2 and nuclear factor-kappa B p65 nuclear translocation through the cyclic adenosine monophosphate/protein kinase A pathway, and suppressed proinflammatory cytokines (i.e., interleukin-1-beta, interleukin-6, and tumor necrosis factor-alpha) and monocyte chemoattractant protein-1 production in response to lipopolysaccharide. DFS-enhanced GLP-1 activity sustained endothelial nitric oxide synthase phosphorylation and decreased endothelial senescence and apoptosis compared with GLP-1 alone. In the human study, fasting levels of active GLP-1 were significantly lower in patients with coronary artery disease than those without (3.10 pmol/l [2.40 to 3.62 pmol/l] vs. 4.00 pmol/l [3.10 to 5.90 pmol/l], p < 0.001). A DPP-4 inhibitor, DFS, exhibited antiatherogenic effects through augmenting GLP-1 activity in macrophages and endothelium.