Aβ1–42-RAGE Interaction Disrupts Tight Junctions of the Blood–Brain Barrier Via Ca2+-Calcineurin Signaling

The blood–brain barrier (BBB), which is formed by adherens and tight junctions (TJs) of endothelial cells, maintains homeostasis of the brain. Disrupted intracellular Ca 2+ homeostasis and breakdown of the BBB have been implicated in the pathogenesis of Alzheimer9s disease (AD). The receptor for advanced glycation end products (RAGE) is known to interact with amyloid β-peptide (Aβ) and mediate Aβ transport across the BBB, contributing to the deposition of Aβ in the brain. However, molecular mechanisms underlying Aβ-RAGE interaction-induced alterations in the BBB have not been identified. We found that Aβ 1–42 induces enhanced permeability, disruption of zonula occludin-1 (ZO-1) expression in the plasma membrane, and increased intracellular calcium and matrix metalloproteinase (MMP) secretion in cultured endothelial cells. Neutralizing antibodies against RAGE and inhibitors of calcineurin and MMPs prevented Aβ 1–42 -induced changes in ZO-1, suggesting that Aβ-RAGE interactions alter TJ proteins through the Ca 2+ -calcineurin pathway. Consistent with these in vitro findings, we found disrupted microvessels near Aβ plaque-deposited areas, elevated RAGE expression, and enhanced MMP secretion in microvessels of the brains of 5XFAD mice, an animal model for AD. We have identified a potential molecular pathway underlying Aβ-RAGE interaction-induced breakage of BBB integrity. This pathway might play an important role in the pathogenesis of AD.