Effect of chronic treatment with acetylsalicylic acid and clopidogrel on atheroprogression and atherothrombosis in ApoE-deficient mice in vivo

Summary

Acetylsalicylic acid (ASA) and the thienopyridine clopidogrel are established anti-platelet drugs that significantly reduce secondary cardiovascular events in patients with manifest atherosclerosis. However, their impact on atherosclerotic lesion development remains controversial. Four-week-old ApoE-deficient mice were randomly assigned to four groups receiving a cholesterol diet together with either ASA (5 mg/kg), or clopidogrel (25 mg/kg), or a combination of both ASA and clopidogrel, or vehicle for 8–12 weeks. Using intravital microscopy we found that daily administration of ASA in combination with clopidogrel reduces platelet thrombus formation following rupture of atherosclerotic plaque in vivo by ∼50%. However, therapy with ASA or clopidogrel alone, or in combination for a period of 8–12 weeks had no significant effect on adhesion of platelets to dysfunctional endothelial cells or on atherosclerotic lesion formation in the aortic root or the carotid artery. In conclusion, anti-platelet therapy is effective in reducing platelet adhesion and subsequent thrombus formation following rupture of atherosclerotic plaque in vivo. However, our data do not support a role of either drug in the primary prevention of atherosclerosis in ApoE-deficient mice.

Keywords

Atherosclerosis - platelet pharmacology - antiplatelet agents - atherothrombosis - animal models

• References

• 1 Massberg S, Brand K, Grüner S. et al. A critical role of platelet adhesion in the initiation of atherosclerotic lesion formation. J Exp Med 2002; 196: 887-896.
• 2 Massberg S, Schürzinger K, Lorenz M. et al. Reduced platelet adhesion, attenuated atherosclerosis and increased resistance to focal cerebral ischemia in mice lacking GPIIb integrin. Circulation 2005; 112: 1180-1188.
• 3 Massberg S, Gawaz M, Grüner S. et al. A crucial role of glycoprotein VI for platelet recruitment to the injured arterial wall in vivo. J Exp Med 2003; 197: 41-49.
• 4 Falati S, Gross P, Merrill-Skoloff G. et al. Real-time in vivo imaging of platelets, tissue factor and fibrin during arterial thrombus formation in the mouse. Nat Med 2002; 8: 1175-1181.
• 5 The CAPRIE Steering Commitee.. A randomized, blinded trial of clopidogrel versus aspirin in patients at risk of ischaemic events. Lancet 1996; 348: 1329-1339.
• 6 Evangelista V, Totani L, Rotondo S. et al. Prevention of cardiovascular disease in type-2 diabetes: how to improve the clinical efficacy of aspirin. Thromb Haemost 2005; 93: 8-16.
• 7 Herbert JM, Dol F, Bernat A. et al. The antiaggregating and antithrombotic activity of clopidogrel is potentiated by aspirin in several experimental models in the rabbit. Thromb Haemost 1998; 80: 512-518.
• 8 Momi S, Pitchford SC, Alberti PF. et al. Nitroaspirin plus clopidogrel versus aspirin plus clopidogrel against platelet thromboembolism and intimal thickening in mice. Thromb Haemost 2005; 93: 535-543.
• 9 Bierbach B, Horstick G, Berg O. et al. Potent low dose platelet inhibitory effects of clopidogrel and aspirin on coronary thrombus formation in an animal model of acute unstable angina. Thromb Haemost 2006; 95: 354-361.
• 10 Cayatte AJ, Due Y, Oliver-Krasinski J. et al. The thromboxane receptor antagonist S18886 but not as- pirin inhibits atherogenesis in Apo E-deficient mice. Arterioscler Thromb Vasc Biol 2000; 20: 1724-1728.
• 11 Paul A, Calleja L, Camps J. et al. The continuous administration of aspirin attenuates atherosclerosis in apolipoprotein E-deficient mice. Life Sci 2000; 68: 457-465.
• 12 Tous M, Ferré N, Vilella E. et al. Aspirin attenuates the initiation but not the progression of atherosclerosis in apolipoprotein E-deficient mice fed a high-fat, highcholesterol diet. Basic Clin Pharmacol Toxicol 2004; 95: 15-19.
• 13 Bhatt DL, Fox KA, Hacke W. et al. Clopidogrel and aspirin versus aspirin alone for the prevention of atherothrombotic events. N Engl J Med 2006; 354: 1706-1717.
• 14 Ridker PM, Cook NR, Lee I-M. et al. A randomized trial of low-dose aspirin in the primary prevention of cardiovascular disease in women. N Engl J Med 2005; 352: 1293-1304.
• 15 Cyrus T, Sung S, Zhao L. et al. Effect of low-dose aspirin on vascular inflammation, plaque stability, and atherogenesis in low-density lipoprotein receptor-deficient mice. Circulation 2002; 106: 1282-1287.
• 16 Evangelista V, Manarini S, Dell'Elba G. et al. Clopidogrel inhibits platelet-leukocyte adhesion and platelet-dependent leukocyte activation. Thromb Haemost 2005; 94: 568-577.
• 17 Abele S, Weyand M, Wollin M. et al. Clopidogrel reduces the development of transplant arteriosclerosis. Thorac Cardiovasc Surg 2006; 131: 1161-1166.
• 18 Lorenz RL, Boehlig B, Uedelhoven WM. et al. Superior antiplatelet action of alternate day pulsed dosing versus split dose administration of aspirin. Am J Cardiol 1989; 64: 1185-1188.
• 19 Müller I, Besta F, Schulz C. et al. Prevalence of clopidogrel non-responders among patients with stable angina pectoris scheduled for elective coronary stent placement. Thromb Haemost 2003; 89: 783-787.
• 20 Fleming I, Schulz C, Fichtlscherer B. et al. AMPactivated protein kinase (AMPK) regulates the insulininduced activation of the nitric oxide synthase in human platelets. Thromb Haemost 2003; 90: 863-871.
• 21 Massberg S, Müller I, Besta F. et al. Effects of 2 different antiplatelet regimens with abciximab or tirofiban on platelet function in patients undergoing coronary stenting. Am Heart J 2003; 146: e19.
• 22 Thebault JJ, Kieffer G, Cariou R. Single-dose pharmacodynamics of clopidogrel. Sem Thromb Haemost 1999; 25 (Suppl. 02) 3-8.
• 23 Cadroy Y, Bossavy J-P, Thalamas C. et al. Early potent antithrombotic effect with combined aspirin and a loading dose of clopidogrel on experimental arterial thrombogenesis in humans. Circulation 2000; 101: 2823-2828.
• 24 Daykin HJ, Sturgeon SA, Jones C. et al. Arterial antithrombotic effects of aspirin, heparin, enoxaparin and clopidogrel alone, or in combination, in the rat. Thromb Res 2006; 118: 755-762.
• 25 The CREDO Investigators.. Early and sustained dual oral antiplatelet therapy following percutaneous coronary intervention (CREDO). A randomized controlled trial. JAMA 2002; 288: 2411-2420.
• 26 Vilahur G, Segalés E, Salas E. et al. Effects of a novel platelet nitric oxide donor (LA816), aspirin, clopidogrel, and combined therapy in inhibiting flowand lesion-dependent thrombosis in the porcine ex vivo model. Circulation 2004; 110: 1686-1693.
• 27 Herbert JM, Tissinier A, Defreyn G. et al. Inhibitory effect of clopidogrel on platelet adhesion and intimal proliferation after arterial injury in rabbits. Arterioscler Thromb 1993; 13: 1171-1179.
• 28 Li M, Zhang Y, Ren H. et al. Effect of clopidogrel on the inflammatory progression of early atherosclerosis in rabbits model. Atherosclerosis. 2007 [In press