Neutrophil Extracellular Traps In Thrombus Of Patient With Acute Ischaemic Stroke

BackgroundThe latest study shows neutrophil extracellular traps(NETs) play an important role in the venous system thrombosis, can’t be dissolved by rt-PA, and has a resistance to rt-PA on the dissolution of thrombus. Thrombolysis with intravenous alteplase(rt-PA) is the best proven and most effective treatment for acute ischaemic stroke.The overall recanalization rate is 46% after thrombolysis with intravenous rt-PA, and reocclusion occurs in 14–34% of these with arteries recanalized.These phenomena indicate that some unknown componends might exist in arterial thrombosis, which could not to be dissolved by rt-PA, and participate in the reconstruction of the thrombosis after recanalization. Whether NETs is also involved in arterial thrombosis of patients with acute ischemic stroke and affects the effect of intravenous thrombolysis by imply use rt-PA is still unclear.ObjectiveTo evaluate the correlation betwwen the thrombosis and the plasma level of neutrophil-derived circulating free DNA(cf-DNA/NETs) in acute ischaemic stroke, and identify whether the existence of NETs in arterial thrombosis of patients with acute ischaemic stroke.So that, provide new targets and ideas on thrombolysis therapy for acute ischaemic stroke.Materials and MethodsCollected plasma of patients suffered acute ischaemic stroke within 72h(n=120, 13 cases have intravenous thrombolysis) and control group(n = 30) betweent December 2013 and December 2014. Quantification of cf-DNA/NETs was performed with green fluorescent dye binding DNA test. The fluorescence(emission wave length at 485-nm) intensity is a measurement for the amounts of DNA and was quantified by a fluorescence reader. We compared the level of cf-DNA/NETs in the plasma between two groups, and the difference in that before and after intravenous thrombolysis in acute ischaemic stroke group. A total of 10 acute ischaemic stroke patients with arterial thrombosis were recruited within the same time, Electron micrographing,HE staining and NETs immunofluorescence staining was performed after frozen section.ResultOf the 120 patients enrolled in the study, 108 fulfilled the criteria for further follow-up, and 29 fulfilled the criteria in control groups. Compared with this control group, no significant difference in the baseline(including gender, age, blood glucose, level of blood pressure and cholesterin before thrombolysis, the history of Coronary atherosclerotic heart disease, hypertension, diabetes or transient ischemic attack, etc.) between two groups was found. However, the plasma levels of cf-DNA/NETs were significantly increased in patient with acute ischemic stroke(102.88±36.63 ng/ml VS 66.31±23.39 ng/ml, P<0.001), and that is significantly higher after intravenous thrombolysis compared with that before it in patients with acute ischemic stroke(137.08±55.69 ng/ml VS 75.07±33.12 ng/ml, P<0.001). Plasma level of cf-DNA/NETs in acute ischaemsic stroke group were positively correlated with onset time, NIHSS score and diastolic blood pressure(P < 0.01), and it increased along the time lasting, peaked at 24-48 hours, then gradually decreased. But it has no significant relation with age, sex, systolic blood pressure, blood glucose, hypertension, the history of type 2 diabetes, hypercholesterolemia, coronary atherosclerotic heart disease, transient ischemic attack, heart valve disease and atrial fibrillation. Electron micrographing and immunofluorescence staining confirmed that NETs exist in arterial thrombosis from acute ischaemic stroke.ConclusionThe plasma levels of cf-DNA/NETs correlate with acute ischaemic stroke severity. NETs is a structural part of arterial thrombosis in patients with acute ischaemic stroke. It may provide a new target for treatment.