The role of reactive nitrogen/oxygen intermediates in cytokine-induced trophoblast apoptosis

Reactive oxygen and nitrogen intermediates (ROI, RNI), such as superoxide a nion, nitric oxide (NO) and peroxynitrite, are present in villous trophobla sts and mediate TNF-alpha-induced apoptosis in other cell types. We therefo re proposed that ROI/RNI mediate cytokine-induced apoptosis of cultured vil lous cytotrophoblasts. Treatment of cultures of highly purified term cytotr ophoblasts with TNF-alpha and IFN-gamma had no effect on NO synthase (NOS) protein expression measured by immunoblot analysis: iNOS was not expressed and eNOS expression was unaffected. NO production assessed by nitrite level s was below detection limits of the Griess reaction and the NOS inhibitors L-NAME :Ind L-NMMA did not decrease cytokine-stimulated apoptosis. Trophobl asts produced ROI and expressed Cu/Zn superoxide dismutase (SOD) protein bu t neither was affected by cytokine treatment. ROI scavengers (exogenous SOD , ascorbic acid and butylated hydroxyanisole) also had no effect on cytokin e-stimulated apoptosis. Nitrotyrosine immunoblot analysis indicated peroxyn itrite production but again cytokines did not reproducibly alter expression patterns or band intensities. Exogenous peroxynitrite stimulated cytotroph oblast apoptosis but only at high levels (1000 mu M). We conclude that, alt hough present in cultured villous cytotrophoblasts, ROI/RNI are not induced by TNF-alpha and IFN-gamma and do not mediate cytokine-induced apoptosis. (C) 1999 W. B. Saunders Company Ltd.