title: Peroxynitrite is a mediator of cytokine-induced destruction of human pancreatic islet beta cells.
abstract: 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.
authors.affiliation: Department of Surgery, University of Alberta, Edmonton, Alberta, Canada.
authors.forename: J R
authors.initials: JR
authors.lastname: Lakey
authors.forename: W L
authors.initials: WL
authors.lastname: Suarez-Pinzon
authors.forename: K
authors.initials: K
authors.lastname: Strynadka
authors.forename: G S
authors.initials: GS
authors.lastname: Korbutt
authors.forename: R V
authors.initials: RV
authors.lastname: Rajotte
authors.forename: J G
authors.initials: JG
authors.lastname: Mabley
authors.forename: C
authors.initials: C
authors.lastname: Szabó
authors.forename: A
authors.initials: A
authors.lastname: Rabinovitch
mesh_terms: D016923:Cell Death; D016207:Cytokines / Q000494:pharmacology*; D004338:Drug Combinations; D006146:Guanidines / Q000494:pharmacology; D006801:Humans; D007150:Immunohistochemistry / Q000379:methods; D066298:In Vitro Techniques; D007371:Interferon-gamma / Q000494:pharmacology; D007375:Interleukin-1 / Q000494:pharmacology; D007515:Islets of Langerhans / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology; D030421:Peroxynitrous Acid / Q000502:physiology*; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology; D014443:Tyrosine / Q000031:analogs & derivatives* / Q000378:metabolism
chemical_list: D016207:Cytokines; D004338:Drug Combinations; D006146:Guanidines; D007375:Interleukin-1; D014409:Tumor Necrosis Factor-alpha; C014363:bis(2-guanidinoethyl)disulfide; D030421:Peroxynitrous Acid; C002744:3-nitrotyrosine; D014443:Tyrosine; D007371:Interferon-gamma