Effect of amyloid beta on ATP-binding cassette transporter expression and activity in porcine brain microvascular endothelial cells

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). 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)). 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.