Dual antiplatelet therapy improves functional recovery and inhibits inflammation after cerebral ischemia/reperfusion injury

Background: Dual antiplatelet therapy with aspirin and clopidogrel (ASA+CPG) during the first 21 days has been shown to reduce the risk of major ischemic events in patients with transient ischemic attack (TIA) or minor stroke. However, the mechanisms underlying combination treatment with ASA+CPG in experimental ischemic stroke has not been fully elucidated. Methods: Minor cerebral ischemia was induced in mice by transient distal middle cerebral artery occlusion (tdMCAO). Two doses of ASA+CPG (12 mg/kg/day and 24 mg/kg/day) or vehicle were administered by gavage daily. Neurological behaviors were assessed using the modified Garcia scores, Rotarod test, Y maze, and open field test. Platelet function was assessed in vitro by flow cytometry and in vivo by bleeding and clotting time. The neutrophil ratio and the levels of inflammatory cytokines were measured by flow cytometry and the Meso Scale Discovery (MSD) electrochemilunimescence, respectively. Results: Sensorimotor function was partially recovered with ASA+CPG treatment after ischemia. Anxiety levels and cognitive functions showed improvement in the ASA+CPG group at 12 mg/kg/day after 21 days. Both tail bleeding time and flow cytometry showed significantly decreased platelet function after ASA+CPG treatment. Notably, ASA+CPG at 12 mg/kg/day prolonged clotting time at 28 days after injury. Furthermore, the ratio of neutrophils, an indicator of inflammation, was reduced with 12 mg/kg/day ASA+CPG treatment in the bone marrow (BM) at 21 days and in the peripheral blood (PB) at 21 and 28 days after tdMCAO. Both doses of ASA+CPG decreased pro-inflammatory cytokine interleukin (IL)-6 expression 21 days after stroke. Taken together, these results demonstrated that combination treatment with ASA+CPG improved long-term neurological function after stroke and may inhibit platelet-neutrophil interaction by decreasing the concentration of pro-inflammatory cytokine, IL-6. Conclusions: These findings indicate a neuroprotective effect of combination treatment with ASA+CPG for a duration of 21 days in an experimental acute minor stroke model. These findings provide further evidence that dual antiplatelet therapy may be a viable neuroprotective treatment to decrease the recurrence of stroke.