Plasma VAP-1/SSAO Activity Predicts Intracranial Hemorrhages and Adverse Neurological Outcome After Tissue Plasminogen Activator Treatment in Stroke

Vascular adhesion protein-1 (VAP-1) is a cell surface and circulating enzyme involved in recruitment of lymphocytes and neutrophils through its semicarbazide-sensitive amine oxidase (SSAO) activity. We aimed to study plasma VAP-1/SSAO activity in relation to the risk for intracranial bleeding complications in patients with stroke treated with tissue plasminogen activator (tPA), the greatest safety concern with this treatment. In 141 patients with ischemic stroke, we measured VAP-1/SSAO activity in plasma taken before tPA administration. Hemorrhagic events were classified according to brain CT criteria and functional outcomes evaluated using the National Institutes of Health Stroke Scale. We also assessed the potential therapeutic effect of blocking VAP-1/SSAO activity in a rat embolic stroke model treated with tPA. We saw significantly higher levels of plasma VAP-1/SSAO activity in patients who subsequently experienced hemorrhagic transformation. Elevated plasma VAP-1/SSAO activity also predicted worse neurological outcome in these patients. In the rat model, we confirmed that use of the inhibitor semicarbazide prevented adverse effects caused by delayed tPA administration, leading to a smaller infarct volume. Our data demonstrate that baseline VAP-1/SSAO activity predicts parenchymal hemorrhage after tPA, suggesting the safety of thrombolytic agents could be improved by considering VAP-1/SSAO activity. Furthermore, anti-VAP-1/SSAO drugs given with tPA may prevent neurological worsening in patients with ischemic stroke.