Effect of the dipeptidyl peptidase-4 inhibitor linagliptin on atherosclerotic lesions in Watanabe heritable hyperlipidemic rabbits: iMap-IVUS and pathological analysis.

Abstract

Dipeptidyl peptidase-4 (DPP-4) inhibitors have potential as a treatment for atherosclerosis. However, it is unclear whether DPP-4 inhibitors stabilize atherosclerotic plaque or alter the composition of complex plaque. Sixteen Watanabe heritable hyperlipidemic rabbits aged 10-12weeks with atherosclerotic plaque in the brachiocephalic artery detected by iMap™ intravascular ultrasound (IVUS) were divided into a DPP-4 inhibitor group and a control group. Linagliptin was administered to the DPP-4 inhibitor group via nasogastric tube at a dose of 10mg/kg/day for 16weeks, and control rabbits received the same volume of 0.5% hydroxyethylcellulose. After evaluation by IVUS at 16weeks, the brachiocephalic arteries were harvested for pathological examination. IVUS revealed that linagliptin significantly reduced the plaque volume and vessel volume (control group vs. DPP-4 inhibitor group: ∆plaque volume, 1.02 ± 0.96mm3 vs. - 3.59 ± 0.92 mm3, P = 0.004; ∆vessel volume, - 1.22 ± 2.36mm3 vs. - 8.66 ± 2.33 mm3, P = 0.04; %change in plaque volume, 6.90 ± 5.62% vs. - 15.06 ± 3.29%, P = 0.005). With regard to plaque composition, linagliptin significantly reduced the volume of fibrotic, lipidic, and necrotic plaque (control group vs. DPP-4 inhibitor group: ∆fibrotic volume, 0.56 ± 1.27mm3 vs. - 5.57 ± 1.46mm3, P = 0.04; ∆lipidic volume, 0.24 ± 0.24mm3 vs. - 0.42 ± 0.16mm3 P = 0.04; ∆necrotic volume, 0.76 ± 0.54mm3 vs. - 0.84 ± 0.25mm3, P = 0.02). Pathological examination did not show any significant differences in the %smooth muscle cell area or %fibrotic area, but infiltration of macrophages into plaque was reduced by linagliptin treatment (%macrophage area: 12.03% ± 1.51% vs. 7.21 ± 1.65%, P < 0.05). These findings indicate that linagliptin inhibited plaque growth and stabilized plaque in Watanabe heritable hyperlipidemic rabbits.