Background
Deposition of amyloid-β peptide (Aβ(1-42)) within the brain is characteristic of Alzheimer's disease. Little is known of the effects of Aβ(1-42) on blood-brain barrier (BBB) ATP-binding Cassette (ABC) efflux transporters which influence BBB permeability. The effects of Aβ(1-42) on ABCB1, ABCC5 and ABCG2 activity and expression and pregnane X receptor (PXR) and constitutive androstane receptor (CAR) transcription factors expression were determined in primary porcine brain endothelial cells (PBECs).
Conclusion
Aβ(1-42) inhibits multiple ABC transporters and PXR and CAR in PBECs. General significance: Aβ(1-42) reduces ABC transporter activity and expression in BBB endothelial cells and has the potential to influence BBB permeability characteristics.
Methods
The effect of Aβ(1-42) on transporter activity was determined by measurement of intracellular accumulation of the fluorescent probes calcein (ABCB1), GS-MF (ABCC5) and Hoechst 33342 (ABCG2). Expression of transporters and transcription factors was assessed by Western blotting.
Results
Treatment of PBECs with Aβ(1-42) significantly decreased activity of ABCB1 (Aβ(1-42) at 10 μg/ml, 25 μg/ml and 50 μg/ml), ABCC5 (Aβ(1-42) at 25 μg/ml and 50 μg/ml) and ABCG2 (Aβ(1-42) at 10 μg/ml, 25 μg/ml and 50 μg/ml). Aβ(1-42) also significantly decreased expression of ABCB1 (p < 0.05 at 25 μg/ml and 50 μg/ml), ABCG2 (p < 0.05 at 25 μg/ml and p ≤ 0.001 at 50 μg/ml), ABCC5 (p < 0.05 at 25 μg/ml and 50 μg/ml), PXR (p < 0.05 at 10 μg/ml, 25 μg/ml and 50 μg/ml Aβ(1-42)) and CAR (p < 0.05 at 25 μg/ml and 50 μg/ml Aβ(1-42)).
Significance
Aβ(1-42) reduces ABC transporter activity and expression in BBB endothelial cells and has the potential to influence BBB permeability characteristics.