Relationship between Inflammation and Aspirin and Clopidogrel Antiplatelet Responses in Acute Ischemic Stroke

Objective: We measured serum levels of proinflammatory/prothrombotic markers P-selectin, CD40L, matrix metalloproteinase 9 (MMP-9), intracellular adhesion molecule 1 (ICAM-1), and interleukin (IL)-6 in ischemic stroke patients, correlating their levels with the results of aspirin (ASA) and clopidogrel antiplatelet responses, using 3 point of care platelet function instruments, thromboelastograph (TEG), Accumetrics (ACU), and impedance aggregometer (IMP). Methods: Patients on chronic ASA regimen at the time of stroke were switched to 300 mg clopidogrel loading dose and 75 mg clopidogrel maintenance dose. Serum levels of the aforementioned inflammatory mediators were measured in 51 patients at baseline (on ASA regimen), and at 26 +/- 5 hours and 64 +/- 18 hours postclopidogrel administration by enzyme-linked immunosorbent assay. Results: P-selectin, CD40L, and MMP-9 serum levels were reduced; ICAM-1 and IL-6 serum levels showed no difference postclopidogrel administration relative to baseline. Patients' stratification based on ASA dose showed more significant reductions in P-selectin, CD40L, and MMP-9 serum levels postclopidogrel administration in patients who were on baseline 81 mg ASA, as compared to patients on 325 mg ASA. Measurement with TEG was sensitive for correlating ASA antiplatelet responses to serum levels of inflammatory markers, whereas measurements with ACU and IMP were sensitive for correlating clopidogrel antiplatelet responses to serum levels of inflammatory markers. Conclusion: Clopidogrel exerts both platelet-dependent and platelet-independent anti-inflammatory effects. The association between platelet function and inflammation depends on the platelet function analyzer, the type of antiplatelet agent, the nature of the inflammatory marker, and the time of measurement relative to the time of drug administration.