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Mol Neurobiol. 2019 Mar 9. doi: 10.1007/s12035-019-1539-9. [Epub ahead of print]

Canonical Wnt Pathway Maintains Blood-Brain Barrier Integrity upon Ischemic Stroke and Its Activation Ameliorates Tissue Plasminogen Activator Therapy.

Author information

1
Neuroscience Axis, Research Center of CHU de Québec - Université Laval, 2705 Laurier Boulevard, Quebec City, QC, G1V 4G2, Canada.
2
Department of Psychiatry and Neuroscience, Faculty of Medicine, Université Laval, Québec City, QC, Canada.
3
Department of Molecular Medicine, Faculty of Medicine, Université Laval, Québec City, QC, Canada.
4
Neuroscience Axis, Research Center of CHU de Québec - Université Laval, 2705 Laurier Boulevard, Quebec City, QC, G1V 4G2, Canada. ayman.el-ali@crchudequebec.ulaval.ca.
5
Department of Psychiatry and Neuroscience, Faculty of Medicine, Université Laval, Québec City, QC, Canada. ayman.el-ali@crchudequebec.ulaval.ca.

Abstract

Stroke induces blood-brain barrier (BBB) breakdown, which promotes complications like oedema and hemorrhagic transformation. Administration of recombinant tissue plasminogen activator (rtPA) within a therapeutic time window of 4.5 h after stroke onset constitutes the only existing treatment. Beyond this time window, rtPA worsens BBB breakdown. Canonical Wnt pathway induces BBB formation and maturation during ontogeny. We hypothesized that the pathway is required to maintain BBB functions after stroke; thus, its activation might improve rtPA therapy. Therefore, we first assessed pathway activity in the brain of mice subjected to transient middle cerebral artery occlusion (MCAo). Next, we evaluated the effect of pathway deactivation early after stroke onset on BBB functions. Finally, we assessed the impact of pathway activation on BBB breakdown associated to delayed administration of rtPA. Our results show that pathway activity is induced predominately in endothelial cells early after ischemic stroke. Early deactivation of the pathway using a potent inhibitor, XAV939, aggravates BBB breakdown and increases hemorrhagic transformation incidence. On the other hand, pathway activation using a potent activator, 6-bromoindirubin-3'-oxime (6-BIO), reduces the incidence of hemorrhagic transformation associated to delayed rtPA administration by attenuating BBB breakdown via promotion of tight junction formation and repressing endothelial basal permeability independently of rtPA proteolytic activity. BBB preservation upon pathway activation limited the deleterious effects of delayed rtPA administration. Our study demonstrates that activation of the canonical Wnt pathway constitutes a clinically relevant strategy to extend the therapeutic time window of rtPA by attenuating BBB breakdown via regulation of BBB-specific mechanisms.

KEYWORDS:

Blood-brain barrier; Brain endothelial cells; Canonical Wnt pathway; Hemorrhagic transformation; Ischemic stroke; Tight junctions; Tissue plasminogen activator

PMID:
30852795
DOI:
10.1007/s12035-019-1539-9

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