Amyloid Beta 25–35 induces blood-brain barrier disruption in vitro

The amyloid β-peptide (Aβ) is transported across the blood-brain barrier (BBB) by binding with the receptor for advanced glycation end products (RAGE). Previously, we demonstrated that the Aβ fraction 25–35 (Aβ_25–35) increases RAGE expression in the rat hippocampus, likely contributing to its neurotoxic effects. However, it is still debated if the interaction of Aβ with RAGE compromises the BBB function in Alzheimer’ disease (AD). Here, we evaluated the effects of Aβ_25–35 in an established in vitro model of the BBB. Rat brain microvascular endothelial cells (rBMVECs) were treated with 20 μM active Aβ_25–35 or the inactive Aβ_35–25 (control), for 24 h. Exposure to Aβ_25–35 significantly decreased cell viability, increased cellular necrosis, and increased the production of reactive oxygen species (ROS), which triggered a decrease in the enzyme glutathione peroxidase when compared to the control condition. Aβ_25–35 also increased BBB permeability by altering the expression of tight junction proteins (decreasing zonula occludens-1 and increasing occludin). Aβ_25–35 induced monolayer disruption and cellular disarrangement of the BBB, with RAGE being highly expressed in the zones of disarrangement. Together, these data suggest that Aβ_25–35-induces toxicity by compromising the functionality and integrity of the BBB in vitro.