Abstract TMP28: Inhibition of Integrin α 5 β 1 With the Small Peptide Atn-161 Reduces Infarct Volume and Improves Functional Recovery Through Reduction of Blood-brain Barrier Permeability

Abstract

Reperfusion-induced injury after recanalization is exacerbated by blood-brain barrier (BBB) dysfunction after ischemic stroke. Endothelial cell integrin receptors, specifically the β 1 subtype, play a direct role in BBB dysfunction through regulation of barrier-forming tight junction (TJ) proteins. We hypothesize that inhibition of an endothelial specific β 1 integrin, α 5 β 1 , after oxygen-glucose deprivation (OGD) in vitro and also after experimental stroke in vivo will stabilize the BBB through the TJ claudin-5, reducing infarct volumes and improving functional recovery. First, stroke was simulated in vitro by OGD or TNF- α treatment of brain endothelial cell monolayers. Treatment with the small peptide α 5 β 1 inhibitor ATN-161 (10 μM) resulted in decreased barrier permeability as measured by trans-endothelial cell electrical resistance and FITC-dextran permeability. Immunocytochemistry showed extracellular localization and upregulation of claudin-5 with ATN-161 treatment. Next, transient tandem middle cerebral artery occlusion was performed on 12-week-old male mice for 1 hour. On confocal and SEM imaging, post-stroke α 5 β 1 expression was upregulated primarily in the luminal vascular surface by post-stroke day (PSD) 2 rather than at the basement membrane (next to its extracellular matrix ligands). IP injection of ATN-161 (1 mg/kg) immediately after reperfusion and on PSD 1, and PSD2 caused a significant, but transient and acute (after the initial dose only) change in animal pulse distension, but no change in body temperature or heart rate. Infarct volumes, measured by TTC stain, were significantly reduced in ATN-161 treated animals. Furthermore, BBB integrity was improved by ATN-161 as determined by IgG staining and FITC-Dextran injection. Functional recovery, assessed by a 5-item Neuroscore, was also significantly improved. In conclusion, inhibition of α 5 β 1 by ATN-161 was well tolerated, reduced infarct volume, and improved behavioral recovery. Additional studies showed this result was likely due to reduced BBB permeability through the TJ claudin-5. Therefore, inhibition of α 5 β 1 with ATN-161 could represent a novel therapeutic approach for stroke worthy of further investigation.