Abstract W MP90: Suppression of Endothelial Cell Alpha5Beta1 Integrin Prevents Ischemic Stroke Injury in Mice
Although breakdown of the blood-brain barrier (BBB) leads to significant injury after ischemic stroke, therapies that target this breakdown have been unsuccessful in improving patient outcomes. We hypothesize that the α5β1 integrin, a receptor that is conditionally upregulated in brain endothelial cells following ischemic stroke, could play a critical role in worsening ischemic injury and functional outcome by contributing to BBB breakdown. To investigate this hypothesis, we performed transient CCA/MCA occlusion in endothelial cell specific α5 integrin knockout (α5 KO) mice and wild-type (WT) mice treated with a α5β1 small peptide inhibitor ATN-161. Following experimental stroke, while WT control mice showed significant TTC-visualized infarcts by post-stroke day (PSD) 3, α5 KO mice and WT mice treated with ATN-161 had minimal to no discernible infarcts. Cresyl violet neuronal stain further demonstrated little to no tissue disruption and neuronal injury on PSD 1-3 in the α5 KO stroked brains. Furthermore, the BBB remained intact in the stroked α5 KO mice as evidenced by absent IgG staining in the brain parenchyma which was otherwise abundant in stroked WTs. Likewise, several markers of BBB stability such as the tight junction proteins Claudin-5 and ZO-1 were found to be upregulated in the α5 KO mice after stroke. Importantly, α5 KO mice did not have any difference in cerebrovascular anatomy or collateral brain blood flow that could otherwise account for these results. Finally, in vitro assays of brain endothelial cells exposed to oxygen-glucose deprivation (OGD) demonstrated that ATN-161 could prevent OGD-mediated increased endothelial cell permeability as measured by TEER and FITC-dextran, and enhanced beneficial Claudin-5 rearrangement at the cell surface. Taken together, these results suggest that suppression of α5 integrin in brain endothelial cells conveys significant resistance to experimental ischemic stroke injury due, at least in part, to enhanced BBB stability, and suggest that α5β1 integrin represents a novel and very promising therapeutic target for stroke.
Author Disclosures: J. Roberts: None. L. de Hoog: None. G.J. Bix: None.
- © 2015 by American Heart Association, Inc.