Peroxynitrite Is a Mediator of Cytokine-Induced Destruction of Human Pancreatic Islet Cells

• Published in: Laboratory investigation Vol. 81; no. 12; pp. 1683 - 1692
• Main Authors: Lakey, Jonathan R T, Suarez-Pinzon, Wilma L, Strynadka, Ken, Korbutt, Gregory S, Rajotte, Ray V, Mabley, Jon G, Szabó, Csaba, Rabinovitch, Alex
• Format: Journal Article
• Language: English
• Published: New York Nature Publishing Group 01.12.2001
• ISSN: 0023-6837; 1530-0307
• DOI: 10.1038/labinvest.3780381

The proinflammatory cytokines, interleukin-1beta (IL-1beta), tumor necrosis factor alpha (TNFalpha), and interferon gamma (IFNgamma), are cytotoxic to pancreatic islet beta cells, possibly by inducing nitric oxide and/or oxygen radical production in the beta cells. Peroxynitrite, the reaction product of nitric oxide and the superoxide radical, is a strong oxidant and cytotoxic mediator; therefore, we hypothesized that peroxynitrite might be a mediator of cytokine-induced islet beta-cell destruction. To test this hypothesis we incubated islets isolated from human pancreata with the cytokine combination of IL-1beta, TNFalpha, and IFNgamma. We found that these cytokines induced significant increases in nitrotyrosine, a marker of peroxynitrite, in islet beta cells, and the increase in nitrotyrosine preceded islet-cell destruction. Peroxynitrite mimicked the effects of cytokines on nitrotyrosine formation and islet beta-cell destruction. L-N(G)-monomethyl arginine, an inhibitor of nitric oxide synthase, prevented cytokine-induced nitric oxide production but not hydrogen peroxide production, nitrotyrosine formation, or islet beta-cell destruction. In contrast, guanidinoethyldisulphide, an inhibitor of inducible nitric oxide synthase and scavenger of peroxynitrite, prevented cytokine-induced nitric oxide and hydrogen peroxide production, nitrotyrosine formation, and islet beta-cell destruction. These results suggest that cytokine-induced peroxynitrite formation is dependent upon increased generation of superoxide (measured as hydrogen peroxide) and that peroxynitrite is a mediator of cytokine-induced destruction of human pancreatic islet beta cells.