%0 Journal Article
%A García Culebras, Alicia
%A Palma Tortosa, Sara
%A Moraga Yébenes, Ana
%A García Yébenes, Isaac
%A Durán Laforet, Violeta
%A Cuartero Desviat, María Isabel
%A Parra Gonzalo, Juan De La
%A Barrios Muñoz, Ana L.
%A Díaz Guzmán, Jaime
%A Pradillo Justo, Jesús Miguel
%A Moro Sánchez, María Ángeles
%A Lizasoaín Hernández, Ignacio
%T Toll-Like Receptor 4 Mediates Hemorrhagic Transformation After Delayed Tissue Plasminogen Activator Administration in In Situ Thromboembolic Stroke
%D 2017
%@ 0039-2499
%U https://hdl.handle.net/20.500.14352/95746
%X Background and purpose: Hemorrhagic transformation is the main complication of revascularization therapies after stroke. Toll-like receptor 4 (TLR4) is implicated in cerebral damage and inflammation in stroke. This study was designed to determine the role of TLR4 in hemorrhagic transformation development after tissue plasminogen activator (tPA) administration.Methods: Mice expressing (TLR4+/+) or lacking functional TLR4 (TLR4-/-) were subjected to middle cerebral artery occlusion using an in situ thromboembolic model by thrombin injection into the middle cerebral artery, and tPA (10 mg/kg) was administered 20 minutes or 3 hours after ischemia. Infarct size, hemorrhages, IgG extravasation, matrix metalloproteinase 9 expression, and neutrophil infiltration were assessed 24 hours after ischemia.Results: In TLR4+/+, early reperfusion (tPA at 20 minutes) resulted infarct volume, whereas late recanalization (tPA at 3 hours) did not modify lesion size and increased the rate of the most severe hemorrhages. In TLR4-/- mice, both early and late reperfusion did not modify lesion size. Importantly, late tPA administration did not result in worse hemorrhages and in an increased bleeding area as occurred in TLR4+/+ group. In TLR4-/- animals, late reperfusion produced a lesser increase in matrix metalloproteinase 9 expression when compared with TLR4+/+ animals.Conclusions: Our results demonstrate TLR4 involvement in hemorrhagic transformation induced by delayed tPA administration, very likely by increasing matrix metalloproteinase 9 expression.
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