A major problem with tissue plasminogen activator (tPA) therapy for ischemic stroke is the complication of hemorrhage and edema. In our previous grant, we established a quantitative model of tPA-induced hemorrhage in rodent embolic (clot-based) focal ischemia, and showed an overall role for oxidative damage. In this renewal application, we focus on novel signaling mechanisms that are involved. Our overall hypothesis is that after stroke, tPA binds the Low-density-lipoprotein Related Protein (LRP). LRP is a receptor present on neurons; astrocytes and endothelial cells which can trigger MAP kinase signaling cascades, resulting in upregulation of matrix metalloproteinase-9 (MMP-9) in the neurovascular unit (vascular/ astrocytic/neuronal compartments). MMP-9 degrades critical neurovascular matrix substrates that weaken blood vessel integrity and lead to leakage and rupture. To test this overall hypothesis, we will pursue 3 Specific Aims.
In Aim 1, we will examine LRP signaling pathways that upregulate MMP-9 activity after tPA therapy. To do this, we will use in vitro and in vivo models to document the following events: increased levels of LRP after hypoxia/ischemia, tPA-LRP triggering of MAP kinase, activation of AP1 promoter transcription of MMP-9. In vitro experiments will use neurons, astrocytes, and cerebral endothelial cells. In vivo experiments will use the tPA-induced hemorrhage model in rats.
In Aim 2, we wiI1 document a specific role for MMP-9. After focal ischemia, we will compare the severity of tPA-induced edema and hemorrhage in wildtype mice versus MMP-2 knockouts, MMP-7 knockouts, MMP-9 knockouts, and transgenic overexpressors of TIMP1 (an inhibitor of MMPs).
In Aim 3, we develop novel imaging methods to correlate the effects of tPA, MMP-9 activation, and vascular leakage. We will construct an MMP-9 specific probe that enables near-infrared fluorescence imaging of MMP-9 in vivo after tPA. Cranial window imaging experiments in rat and mouse embolic focal ischemia will correlate in real-time MMP-9 upregulation in the neurovascular unit with the onset of vascular leakage. At the NINDS Stroke Program Review Group, proteolytic pathology in the neurovascular unit was identified as a high priority research area. This proposal should fit the goals of the Stroke PRG because it examines novel mechanisms that link tPA, cell signaling, MMPs, and hemorrhagic transformation in the neurovascular unit. ? ? ?

Agency
National Institute of Health (NIH)
Institute
National Institute of Neurological Disorders and Stroke (NINDS)
Type
Research Project (R01)
Project #
2R01NS037074-05
Application #
6574719
Study Section
Special Emphasis Panel (ZRG1-BDCN-3 (01))
Program Officer
Jacobs, Tom P
Project Start
1998-01-01
Project End
2006-12-31
Budget Start
2003-01-01
Budget End
2003-12-31
Support Year
5
Fiscal Year
2003
Total Cost
$403,940
Indirect Cost
Name
Massachusetts General Hospital
Department
Type
DUNS #
073130411
City
Boston
State
MA
Country
United States
Zip Code
02199
Esposito, Elga; Hayakawa, Kazuhide; Maki, Takakuni et al. (2015) Effects of Postconditioning on Neurogenesis and Angiogenesis During the Recovery Phase After Focal Cerebral Ischemia. Stroke 46:2691-4
Hayakawa, Kazuhide; Pham, Loc-Duyen D; Som, Angel T et al. (2011) Vascular endothelial growth factor regulates the migration of oligodendrocyte precursor cells. J Neurosci 31:10666-70
Chou, Sherry H-Y; Lee, Po-Shun; Konigsberg, Rachael G et al. (2011) Plasma-type gelsolin is decreased in human blood and cerebrospinal fluid after subarachnoid hemorrhage. Stroke 42:3624-7
Lee, Brian J; Egi, Yasuhiro; van Leyen, Klaus et al. (2010) Edaravone, a free radical scavenger, protects components of the neurovascular unit against oxidative stress in vitro. Brain Res 1307:22-7
Zhu, Haihao; Fan, Xiang; Yu, Zhanyang et al. (2010) Annexin A2 combined with low-dose tPA improves thrombolytic therapy in a rat model of focal embolic stroke. J Cereb Blood Flow Metab 30:1137-46
Xing, Changhong; Lee, Sunryung; Kim, Woo Jean et al. (2009) Role of oxidative stress and caspase 3 in CD47-mediated neuronal cell death. J Neurochem 108:430-6
Ning, Mingming; Wang, Xiaoying; Lo, Eng H (2009) Reperfusion injury after stroke: neurovascular proteases and the blood-brain barrier. Handb Clin Neurol 92:117-36
Jin, Guang; Tsuji, Kiyoshi; Xing, Changhong et al. (2009) CD47 gene knockout protects against transient focal cerebral ischemia in mice. Exp Neurol 217:165-70
Ji, Ru-Rong; Xu, Zhen-Zhong; Wang, Xiaoying et al. (2009) Matrix metalloprotease regulation of neuropathic pain. Trends Pharmacol Sci 30:336-40
Lok, Josephine; Sardi, S Pablo; Guo, Shuzhen et al. (2009) Neuregulin-1 signaling in brain endothelial cells. J Cereb Blood Flow Metab 29:39-43

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