Advanced glycation end products drive blood-brain barrier lipid dysregulation via RAGE-ABCA1 signaling to promote neurovascular dysfunction in Alzheimer's disease.

Neurovascular dysfunction is an early and critical contributor to Alzheimer's disease (AD), yet the molecular mechanisms linking vascular pathology to metabolic dysregulation remain incompletely understood. Advanced glycation end products (AGEs), which accumulate during aging and metabolic stress, have been implicated in AD pathology; however, their role in cerebrovascular lipid homeostasis is unclear. Here, we demonstrate that AGE accumulation within cerebral microvessels promotes lipid droplet (LD) formation in endothelial cells through receptor for AGE (RAGE)-dependent disruption of cholesterol efflux pathways. In aged APP transgenic mice and human AD brains, we observe increased AGE deposition concomitant with elevated RAGE, DGAT1, and perilipin expression, alongside reduced ABCA1 levels. In human brain endothelial cells, AGE exposure induces lipid metabolic reprogramming characterized by enhanced LD accumulation, upregulation of lipogenic machinery, and suppression of cholesterol efflux. Mechanistically, RAGE silencing restores ABCA1 expression and attenuates LD formation, identifying RAGE as a key upstream regulator. Pharmacological activation of ABCA1 reverses AGE-induced lipid accumulation and reduces RAGE expression, highlighting a therapeutic axis. Furthermore, AGE exposure disrupts blood-brain barrier (BBB) integrity and impairs amyloid-β transport in an in vitro BBB model. In vivo, aging is associated with progressive microvascular LD accumulation, linking metabolic dysfunction to vascular pathology. Together, our findings establish an AGE-RAGE-ABCA1 signaling axis that drives endothelial lipid dysregulation and BBB impairment, providing a mechanistic framework connecting metabolic stress to neurovascular dysfunction in AD.