RESUMEN
In Alzheimer's disease (AD) the blood-brain barrier (BBB) is compromised, thus therapeutic targeting of the BBB to enhance its integrity and function could be a unique approach to treat, slow or hold the progression of AD. Recently, we have developed an in vitro high-throughput screening assay to screen for compounds that increase the integrity of a cell-based BBB model. Results from primary screen identified multiple hit compounds that enhanced the monolayer integrity. Herein, further characterization of selected hit compounds, namely 8-bromoguanosine cyclic monophosphate, JW74, 1,10-phenanthroline monohydrate, SB216763 and α-tocopherol was performed. Compounds were subjected to concentration-dependent studies to determine their EC50 and potency to enhance the cell-based model integrity by the Lucifer Yellow permeability and amyloid-beta (Aß) transport across the monolayer. The compounds demonstrated different EC50s to enhance the monolayer integrity ranging from 0.4 to 12.8⯵M, and different effect on enhancing Aß transport with highest transport observed for α-tocopherol (2.2-fold increase). Such effects were associated with increased levels of tight junction proteins such as claudin-5 and/or ZO-1, and Aß major transport proteins LRP1 and P-glycoprotein. In vivo studies for α-tocopherol were performed in AD mouse model; consistent with the in vitro results α-tocopherol significantly increased BBB integrity measured by IgG extravasation, and reduced brain Aß levels. In conclusion, findings support our developed cell-based BBB model as a functional predictive in vivo tool to select hit compounds, and suggest that enhancing BBB tightness and function has the potential to reduce Aß pathology associated with AD.