Alpha5Beta1 Integrin inhibition as a Profound Blood-Brain Barrier Stabilizing Neuroprotective Stroke Therapy

Although stroke is the fourth leading cause of death in the U.S., the current treatment strategy of thrombolysis for the majority of strokes due to a blood clot (ischemic) has mixed results. Thus, there is an urgent need for new and better stroke therapies. We have previously demonstrated that a fragment of the brain extracellular matrix component perlecan called domain V, is both neuroprotective and neuroreparative after ischemic stroke by interaction with a particular brain endothelial cell receptor, the £\5£]1 integrin. Intriguingly, preliminary evidence now suggests that mice with an endothelial selective deletion of £\5£]1 integrin are profoundly resistant to experimental ischemic stroke. Furthermore, administration of the £\5£]1 integrin specific inhibitor ATN-161 to stroked wild type mice conveys similar resistance to injury. This appears to occur via poststroke stabilization of the blood-brain barrier through increased function of various brain endothelial cell tight junctions proteins which in turn prevents vasogenic edema, inflammation, and expansion on injury. Therefore, we hypothesize that £\5£]1 integrin could be a particularly effective therapeutic target for stroke. In this application, we propose the following specific aims: 1. Determine the effect of endothelial cell selective ƒÑ5ƒÒ1 integrin deletion on experimental ischemic stroke, 2. Determine the potential of the £\5£]1 integrin as a therapeutic target in experimental ischemic stroke and 3. Determine, in mechanistic detail, the role of ƒÑ5ƒÒ1 integrin in modulating blood-brain barrier integrity and subsequent resistance to ischemic stroke. We will use several novel genetically modified mice (£\5 integrin endothelial cell specific knockdown mice, claudin5 eGFP tagged mice) and newly characterized £\5£]1 integrin inhibitors in experimental stroke models and in vitro endothelial cell barrier assays. We expect to demonstrate that suppression or inhibition of ƒÑ5ƒÒ1 integrin in endothelial cells affords significant blood-brain barrier-mediated resistance to experimental ischemic stroke, supporting our long-term goal of developing ƒÑ5ƒÒ1 integrin as a novel human stroke therapeutic target.