Angiopoietin-2 aggravates Alzheimer's disease by promoting blood-brain barrier dysfunction and neuroinflammation.

Disruption of the blood-brain barrier (BBB) increases vascular permeability and promotes neuroinflammation, contributing to Alzheimer's disease (AD) progression. However, the molecular drivers of BBB dysfunction and neuroinflammation in AD remain poorly defined. Here, we identify angiopoietin-2 (ANGPT2) as a central mediator of BBB breakdown and AD progression. Transcriptomic analyses of human AD brains revealed elevated ANGPT2 expression in endothelial cells correlating with disease severity. In 5xFAD mice, endothelial-specific Angpt2 deletion reduced β-amyloid deposition, while Angpt2 overexpression via an adeno-associated viral vector exacerbated the plaque burden. Mechanistically, ANGPT2 suppression of TIE2 signaling increased vascular leakage and fibrin deposition, triggering microglial activation and neuroinflammatory responses that accelerated disease progression. Single-nucleus transcriptomic analyses further revealed Angpt2-driven microglial dysfunction and neuronal impairment consistent with memory deficits observed in behavioral assays. These findings establish ANGPT2 as a critical driver of BBB dysfunction and neuroinflammation in AD and highlight its therapeutic potential.