Acute amyloid-β exposure disrupts insulin signaling in hCMEC/D3 blood–brain barrier endothelial cells

BACKGROUND: Brain insulin resistance and cerebrovascular dysfunction emerge early in late-onset Alzheimer's disease, but how amyloid-β (Aβ) disrupts insulin signaling at the cerebrovascular blood-brain barrier-a major site of insulin receptor signaling and transport into the brain-remains unclear. METHODS: We exposed two distinct human blood-brain-barrier endothelial cell models to soluble Aβ40 or Aβ42 for 1 h, followed by 100 nM insulin for 10 min. Protein and phosphoprotein responses were quantified by reverse-phase protein array, and differential expression was evaluated using linear models. RESULTS: In hCMEC/D3 cells, Aβ40 reduced insulin-stimulated Akt activation and converted insulin's normal inhibition of AMPK into modest stimulation. Aβ42 did not alter insulin-stimulated Akt signaling but moderately suppressed basal Akt activation. Because the iBMEC model did not show insulin-induced activation of PI3K-Akt signaling, mechanistic interpretation of Aβ effects on insulin-responsive signaling focused on hCMEC/D3 cells. CONCLUSIONS: These findings identify acute Aβ40-sensitive impairment of insulin-responsive Akt signaling in hCMEC/D3 BBB endothelial cells. The results define candidate signaling nodes for further mechanistic study of Aβ effects on BBB insulin-signaling dysfunction.