Orally administered dipeptidyl peptidase-4 inhibitor (alogliptin) prevents abdominal aortic aneurysm formation through an antioxidant effect in rats

Objective: Dipeptidyl peptidase-4 (DPP-4) inhibitor, a novel antidiabetic drug, has a cardioprotective effect on ischemia-reperfusion injury through an antioxidant effect. However, the effect of DPP-4 inhibitor on aneurysm formation has not been investigated. We aimed to test the hypothesis that the DPP-4 inhibitor, alogliptin, attenuates vascular oxidative stress and thus inhibits abdominal aortic aneurysm (AAA) formation. Methods: AAAs were created with intraluminal elastase and extraluminal calcium chloride in 36 male rats. Rats were divided into three groups: a low dose of alogliptin group (group LD; 1 mg/kg/d), a high-dose group (group HD; 3 mg/kg/d), and a control group (group C, water). Alogliptin was administered by gastric gavage once daily beginning 3 days before surgery. On day 7 after aneurysm preparation, reactive oxygen species (ROS) expression was semiquantified by dihydroethidium staining, and the oxidation product of DNA produced by ROS, 8-hydroxydeoxyguanosine (8-OHdG), was measured by immunohistochemical staining. Blood glucose concentrations were measured. Hematoxylin and eosin and elastica Van Gieson stainings were performed on day 28, and the AAA dilatation ratio was calculated. Results: On day 7 (six in each group), dihydroethidium staining of the aneurysm wall showed a reduced level of ROS expression (4.6 +/- 0.6 in group C, 2.7 +/- 0.3 in group LD, and 1.7 +/- 0.5 in group HD; P<.0001) and showed fewer 8-OHdG-positive cells in alogliptin-treated samples (138.1 +/- 7.4 cells in group C, 102.5 +/- 4.5 cells in group LD, and 66.1 +/- 4.5 cells in group HD; P<.0001) The treatment significantly reduced messenger RNA expression of matrix metalloproteinases (MMPs) in aneurysm walls (relative expression: MMP-2: 2.1 +/- 0.4 in group C, 1.3 +/- 0.3 in group LD, and 0.9 +/- 0.2 in group HD; P<.001; MMP-9: 2.0 +/- 0.5 in group C, 0.3 +/- 0.3 in group LD, and 0.3 +/- 0.2 in group HD; P<.001). On day 28 (six in each group), the aortic wall in groups LD and HD was less dilated (dilatation ratio: 199.2% +/- 11.8% in group C, 159.6% +/- 2.8% in group LD, and 147.1% +/- 1.9% in group HD; P<.02 group C vs HD) and had higher elastin content than in group C. The difference in blood glucose levels among the three groups was not significant. Conclusions: The DPP-4 inhibitor, alogliptin, attenuates aneurysm formation and expansion dose-dependently in a rat AAA model via an antioxidative action.