Oxidative and nitrosative stress mediated by cyclosporine A in endothelial cells

Cyclosporine A (CsA) therapy is associated with side effects related to oxidative stress. We characterized the reactive oxygen and nitrogen species produced in the extracellular and intracellular compartments of bovine aortic endothelial cells (BAEC) exposed to CsA. CsA induced a dose-dependent increase of the intracellular oxidation of the NO-sensitive fluorescent probe DAF-2/DA. In agreement with this, CsA produced a dose-dependent accumulation of nitrites in the supernatants of BAEC. In contrast, in BAEC treated with CsA, the presence of superoxide anion could only be detected in the intracellular compartment, as measured by the oxidation of dihydroethidium. The formation of peroxynitrite was assessed in the intracellular compartment, by flow cytometry with dihydrorhodamine 123 and immuno-cytochemical nitrotyrosine formation. Tyrosine nitration of endothelial cells could represent a relevant pathophysiological mechanism underlying the vascular injury associated to the use of Cyclosporine A.