Abstract
The potent oxidant peroxynitrite (ONOO(-)) is formed after the combination of nitric oxide with superoxide and has been closely associated with the pathology of inflammatory disease. In particular, the generation of ONOO(-) has been linked to central nervous system disorders including Alzheimer's and Parkinson's disease, multiple sclerosis and bacterial and viral meningitis. Specifically, ONOO(-) has been implicated in the loss of blood-brain barrier (BBB) integrity during neuroinflammation, but the precise mechanisms through which the molecule acts to mediate neurovascular breakdown have not been established. The disruptive effects of ONOO(-) could be mediated by either direct or indirect actions on the endothelial cells that comprise the major component of the BBB. The current study has comparatively assessed the direct toxic effects of ONOO(-) on the brain endothelial cell line, b.End3 and C6 astrocytoma and NA neuroblastoma preparations. b.End3 cells were relatively resistant to ONOO(-)-induced cell death compared with C6 and NA cultures. The indirect involvement of ONOO(-) in neuroendothelial disruption was pharmacologically determined via adhesion molecule expression and immunocompetent cell attachment to b.End3 cells. ONOO(-)-targeted drugs, including the selective free radical scavenger, uric acid, the decomposition catalyst 5,10,15,20-tetrakis (4-sulphonatophenyl) porphyrinatoiron (III) (FeTPPS) and the poly(ADP-ribose) polymerase inhibitor N-(6-oxo-5,6-dihydrophenanthridin-2-yl)-(N,N-dimethylamino) acetamide hydrochloride (PJ34) revealed that ONOO(-) was only partly involved in E-selectin, ICAM-1 and VCAM-1 expression on b.End3 cells and also cytokine-induced T-lymphocyte attachment to the cell line. The results indicate that ONOO(-) contributes to b.End3 cell disruption but is not exclusively responsible for the breakdown of neuroendothelial function.