Objective: The main goal of this application is to study the mechanism whereby the low density lipoprotein receptor-related protein 1 (LRP1) modulates the permeability of the BBB under physiological conditions and after an ischemic stroke. Methods In Aim I we will test the hypothesis that under non-ischemic conditions astrocytic LRP1 preserves the integrity of the basement membrane-astrocyte (BM-A) interface by promoting the recruitment of integrins to the membrane of perivascular astrocytic end- feet processes and their binding to its ligands in the basement membrane (BM).
In Aim II we propose that this function is lost under ischemic conditions when the cleavage of the extracellular domain of LRP1 from perivascular astrocytes activates a cell-signaling pathway that increases the permeability of the blood-brain barrier (BBB).
In Aim III we will study in an animal model of ischemic stroke whether inhibition of LRP1 cleavage from perivascular astrocytes with the receptor-associated protein (RAP) prevents the harmful effects of endogenous tPA and/or rtPA on the permeability of the BBB. Research Plan In the first Aim of this application we will use astrocytic cell cultures and a cell adhesion assay. In the second Aim we will use astrocytic cultures, an in vitro model of the blood- brain barrier, real-time PCR, confocal microscopy and co-immunoprecipitation assays. In the third Aim we will use a nanocarrier that we engineered to selectively deliver its content to the BBB in the ischemic tissue and an animal model of cerebral ischemia.
Ischemic stroke accounts for over 6000 admissions to VA hospitals. Cerebral edema and hemorrhagic transformation, produced by increase in the permeability of the blood- brain barrier (BBB), are the two most important causes of death among patients with acute ischemic stroke. This application seeks to understand the mechanism whereby the permeability of the BBB increases following an ischemic stroke and to develop a therapeutic approach to inhibit this complication. This will decrease the morbidity and mortality associated with acute ischemic stroke, according to the guidelines of the VA/HSR&D's Quality Enhancement Research Initiative (QUERI), that seeks to improve the care of VA patients with stroke.
