Thrombin inhibition by dabigatran attenuates atherosclerosis in ApoE deficient mice

INTRODUCTION: Atherosclerosis is a chronic inflammatory disease characterized by endothelial cell damage, infiltration, proliferation and accumulation of macrophages, lymphocytes and transformed vascular smooth muscle cells within the vascular wall and procoagulation processes involving activation of plasmatic coagulation events and platelets. Numerous studies suggested a close interaction between thrombin action and atherogenesis, but possibly underlying mechanisms are multiple and specific treatment options were missing until now. MATERIAL AND METHODS: Atherosclerosis prone 12 weeks old ApoE(–/–) mice were fed a cholesterol rich diet for 4 weeks and were concomitantly treated orally with placebo or the thrombin inhibitor dabigatran (1.2 g/kg/day). RESULTS: The thrombin time (HEMOCLOT(®)) was significant extended in dabigatran treated animals. Vascular oxidative stress was significantly reduced during thrombin inhibition, as assessed by L012 chemiluminescence in aortic segments (212 ±84 vs. 69 ±21 RLU/s/mg dry weight, p = 0.048). Organ chamber experiments of isolated aortic rings showed that dabigatran treatment significantly improved endothelium-derived vasorelaxation (p < 0.001). Dabigatran treated mice developed less atherosclerotic lesions (6.2 ±0.2% vs. 9 ±1.1%, p = 0.037) and showed less infiltration of atherosclerotic lesions with macrophages (2.59 ±0.3% vs. 5.14 ±0.7%, p = 0.0046), as determined by systematic histological and immunohistological analyses of the aortic root. Blood pressure, body weight and food intake were not altered by the treatment. CONCLUSIONS: The thrombin inhibitor dabigatran reduces vascular oxidative stress and inflammation, improves endothelial function and decreases atherosclerosis in mice.