title: MMP-9-positive neutrophil infiltration is associated to blood-brain barrier breakdown and basal lamina type IV collagen degradation during hemorrhagic transformation after human ischemic stroke.
abstract: OBJECTIVE
  An abnormal expression of some matrix metalloproteinases (MMPs) is related with hemorrhagic transformation events after stroke. Our aim was to investigate MMP-2 and MMP-9 in the ischemic brain and its relation with blood-brain barrier breakdown after hemorrhagic transformation in human stroke.
  
  
  METHODS
  We assessed 5 cases of fatal ischemic strokes with hemorrhagic complications; brain samples were obtained from infarct, hemorrhagic, and contralateral tissue. MMP-9 and MMP-2 content was analyzed by zymography and immunohistochemistry was performed to localize MMP-9 and to assess collagen IV integrity in the basal lamina. Laser capture microdissection was performed to isolate blood-brain barrier vessels to study these MMPs.
  
  
  RESULTS
  Overall, MMP-9 levels were higher both in hemorrhagic and nonhemorrhagic infarcted tissue compared to contralateral areas (P<0.0001 and P<0.05). Moreover, levels of the cleaved MMP-9 85kDa-form were significantly elevated in the hemorrhagic compared to nonhemorrhagic and contralateral areas (P=0.033 and P<0.0001). No changes were found for MMP-2 content. Immunostaining revealed a strong MMP-9-positive neutrophil infiltration surrounding brain microvessels associated with severe basal lamina type IV collagen degradation and blood extravasation. Microdissection confirmed that content of MMP-9 was similarly high in microvessel endothelium from hemorrhagic and infarcted areas compared to contralateral hemisphere vessels (P<0.05), pointing to neutrophils surrounding dissected microvessels as the main source of MMP-9 in hemorrhagic areas.
  
  
  CONCLUSIONS
  Our results show a strong neutrophil infiltration in the infarcted and hemorrhagic areas with local high MMP-9 content closely related to basal lamina collagen IV degradation and blood-brain barrier breakdown. Microvessel and inflammatory MMP-9 response are associated with hemorrhagic complications after stroke.
authors.affiliation: Neurovascular Research Laboratory, Neurovascular Unit, Department of Neurology, Universitat Autònoma de Barcelona, Institut de Recerca, Hospital Vall d'Hebron, Barcelona, Spain.
authors.forename: Anna
authors.initials: A
authors.lastname: Rosell
authors.forename: Eloy
authors.initials: E
authors.lastname: Cuadrado
authors.forename: Arantxa
authors.initials: A
authors.lastname: Ortega-Aznar
authors.forename: Mar
authors.initials: M
authors.lastname: Hernández-Guillamon
authors.forename: Eng H
authors.initials: EH
authors.lastname: Lo
authors.forename: Joan
authors.initials: J
authors.lastname: Montaner
mesh_terms: D001485:Basement Membrane / Q000201:enzymology / Q000276:immunology / Q000473:pathology; D001812:Blood-Brain Barrier / Q000201:enzymology* / Q000276:immunology / Q000473:pathology; D001921:Brain / Q000201:enzymology / Q000276:immunology / Q000473:pathology; D002545:Brain Ischemia / Q000276:immunology / Q000378:metabolism* / Q000473:pathology; D002543:Cerebral Hemorrhage / Q000276:immunology / Q000378:metabolism* / Q000473:pathology; D024141:Collagen Type IV / Q000378:metabolism*; D004730:Endothelium, Vascular / Q000201:enzymology / Q000276:immunology / Q000473:pathology; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D020778:Matrix Metalloproteinase 2 / Q000378:metabolism; D020780:Matrix Metalloproteinase 9 / Q000378:metabolism*; D009504:Neutrophils / Q000473:pathology; D020521:Stroke / Q000276:immunology / Q000378:metabolism* / Q000473:pathology
chemical_list: D024141:Collagen Type IV; D020778:Matrix Metalloproteinase 2; D020780:Matrix Metalloproteinase 9