Alpha lipoic acid attenuates microvascular endothelial cell hyperpermeability by inhibiting the intrinsic apoptotic signaling

Background: This study examined whether alpha lipoic acid (ALA), an antioxidant with anti-apoptotic properties, synthesized in mitochondria of endothelial cells, would inhibit intrinsic apoptotic signaling and microvascular endothelial cell hyperpermeability. Methods: Rat lung microvascular endothelial cells were transfected with BAK (BH3) peptide (5 mu g/mL) or active caspase-3 (5 mu g/mL) and were pretreated with ALA (10 and 100 mu mol/L. Hyperpermeability was determined using fluorescein isothiocyanate albumin-flux across the cells grown as monolayer. Reactive oxygen species.(ROS) formation was determined using 123 dihydrorhodamine and mitochondrial membrane potential using JC-1. Cytochrome c levels and caspase-3 activity were determined using an enzyme-linked immunosorbent assay and a fluorometric assay, respectively. Results: ALA (100 mu mol/L) pretreatment attenuated BAK (BH3)-induced hyperpermeability and ROS formation. ALA restored BAK (BH3)-induced collapse in mitochondrial membrane potential and decreased BAK (BH3)-induced cytochrome c release and caspase-3 activity. Conclusions: These findings suggest that ALA attenuates BAK-induced monolayer hyperpermeability through the inhibition of ROS formation and intrinsic apoptotic signaling. (C) 2008 Excerpta Medica Inc. All rights reserved.