title: Microglial cell activation is a source of metalloproteinase generation during hemorrhagic transformation.
abstract: Hemorrhage and edema accompany evolving brain tissue injury after ischemic stroke. In patients, these events have been associated with metalloproteinase (MMP)-9 in plasma. Both the causes and cellular sources of MMP-9 generation in this setting have not been defined. MMP-2 and MMP-9 in nonhuman primate tissue in regions of plasma leakage, and primary murine microglia and astrocytes, were assayed by immunocytochemistry, zymography, and real-time RT-PCR. Ischemia-related hemorrhage was associated with microglial activation in vivo, and with the leakage of plasma fibronectin and vitronectin into the surrounding tissue. In strict serum-depleted primary cultures, by zymography, pro-MMP-9 was generated by primary murine microglia when exposed to vitronectin and fibronectin. Protease secretion was enhanced by experimental ischemia (oxygen-glucose deprivation, OGD). Primary astrocytes, on each matrix, generated only pro-MMP-2, which decreased during OGD. Microglia-astrocyte contact enhanced pro-MMP-9 generation in a cell density-dependent manner under normoxia and OGD. Compatible with observations in a high quality model of focal cerebral ischemia, microglia, but not astrocytes, respond to vitronectin and fibronectin, found when plasma extravasates into the injured region. Astrocytes alone do not generate pro-MMP-9. These events explain the appearance of MMP-9 antigen in association with ischemia-induced cerebral hemorrhage and edema.
authors.affiliation: Division of Hematology, Department of Medicine, University of Washington School of Medicine, Seattle, WA 98104, USA. grgdlzop@u.washington.edu
authors.forename: Gregory J
authors.initials: GJ
authors.lastname: del Zoppo
authors.forename: Harald
authors.initials: H
authors.lastname: Frankowski
authors.forename: Yu-Huan
authors.initials: YH
authors.lastname: Gu
authors.forename: Takashi
authors.initials: T
authors.lastname: Osada
authors.forename: Masato
authors.initials: M
authors.lastname: Kanazawa
authors.forename: Richard
authors.initials: R
authors.lastname: Milner
authors.forename: Xiaoyun
authors.initials: X
authors.lastname: Wang
authors.forename: Naohisa
authors.initials: N
authors.lastname: Hosomi
authors.forename: Takuma
authors.initials: T
authors.lastname: Mabuchi
authors.forename: James A
authors.initials: JA
authors.lastname: Koziol
mesh_terms: D000818:Animals; D001253:Astrocytes / Q000378:metabolism / Q000473:pathology; D001929:Brain Edema / Q000201:enzymology* / Q000473:pathology / Q000503:physiopathology; D002545:Brain Ischemia / Q000201:enzymology* / Q000473:pathology / Q000503:physiopathology; D015687:Cell Hypoxia; D002478:Cells, Cultured; D004792:Enzyme Precursors / Q000378:metabolism*; D005353:Fibronectins / Q000378:metabolism; D018093:Gelatinases / Q000378:metabolism*; D006801:Humans; D020300:Intracranial Hemorrhages / Q000201:enzymology* / Q000473:pathology / Q000503:physiopathology; D020780:Matrix Metalloproteinase 9 / Q000378:metabolism*; D051379:Mice; D017628:Microglia / Q000201:enzymology* / Q000473:pathology; D048530:Papio anubis; D019096:Vitronectin / Q000378:metabolism
chemical_list: D004792:Enzyme Precursors; D005353:Fibronectins; D019096:Vitronectin; D018093:Gelatinases; C120487:pro-matrix metalloproteinase 9; C069860:progelatinase; D020780:Matrix Metalloproteinase 9