Abstract
Background: Neutrophil activation and neutrophil extracellular traps (NETs) participate in downstream microvascular thromboinflammation (DMT) and blood brain barrier disruption in acute ischemic stroke (AIS).
Objectives: The aim of this study was to test whether deoxyribonuclease 1 (DNase 1) infusion, which cleaves extracellular DNA, could reduce DMT in a transient middle cerebral artery (MCA) occlusion stroke model in rats.
Methods: Eighteen rats were subjected to 120-minute transient MCA occlusion. DNase 1 (3 mg/kg, 20% intravenous, and 80% intraperitoneal injection) or vehicle were randomly infused 30 minutes after MCA occlusion. Main outcome criteria were the infarct volume assessed with magnetic resonance imaging, neurological disability, and the rate of hemorrhagic transformation measured at 24 hours. Brain DMT was assessed with biomarkers of platelet, coagulation, and neutrophil activation quantified in brain homogenates.
Results: The infusion of DNase 1 significantly reduced the infarct volume (P = .024) and improved 24-hour neurological outcome (P = .031) compared with vehicle. Staining for fibrin(ogen) and citrullinated histones H3 colocalized with extracellular DNA in the occluded microvessels. Brain thrombin–antithrombin complexes and fibrinogen deposits were significantly reduced in DNase 1-treated rats compared with vehicle (P = .027 and P = .036, respectively). The blood brain barrier disruption
assessed with brain immunoglobulin G measurement and brain edema were also reduced in DNase 1-treated rats (P = .015 and P = .031, respectively).

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