title: Destruction of rat pancreatic islet beta-cells by cytokines involves the production of cytotoxic aldehydes.
abstract: Cytokines produced by mononuclear leukocytes infiltrating pancreatic islets are candidate mediators of islet beta-cell destruction in autoimmune insulin-dependent diabetes mellitus. Cytokines may damage islet beta-cells by inducing oxygen free radical production in the beta-cells. Lipid peroxidation and aldehyde production are measures of oxygen free radical-mediated cell injury. In the current study, we used a HPLC technique to measure levels of different aldehydes produced in rat islets incubated with cytokines. The cytokine combination of interleukin-1beta (10 U/ml), tumor necrosis factor-alpha (10(3) U/ml), and interferon-gamma (10(3) U/ml), and the oxidant, t-butylhydroperoxide, induced significant increases in islet levels of the same aldehydes: butanal, pentanal, 4-hydroxynonenal (4-HNE), and hexanal. Cytokine-induced aldehyde production was associated with islet beta-cell destruction. Thus, cytokine-induced increases in malondialdehyde (MDA; at 4 h) and 4-HNE (at 8 h) preceded islet cell destruction (at 16 h), and the addition of 4-HNE, hexanal, MDA, and pentanal (1-200 microM) to th islets, but not other aldehydes at similar concentrations, produced dose-dependent destruction of islet beta-cells. Furthermore, an antioxidant (lazaroid U78518E) prevented cytokine-induced increases in 4-HNE, hexanal, and MDA and significantly inhibited cytokine-induced decreases in insulin and DNA in the islets. In contrast, N(G)-monomethyl-L-arginine, an inhibitor of nitric oxide synthase, prevented cytokine-induced nitrite production, but did not prevent cytokine-induced increases in 4-HNE, hexanal, and MDA or decreases in insulin and DNA in the islets. These results suggest that cytokines may damage islet beta-cells by inducing oxygen free radicals, lipid peroxidation, and, consequently, the formation of cytotoxic aldehydes in the islet cells.
authors.affiliation: Department of Medicine, University of Alberta, Edmonton, Canada.
authors.forename: W L
authors.initials: WL
authors.lastname: Suarez-Pinzon
authors.forename: K
authors.initials: K
authors.lastname: Strynadka
authors.forename: A
authors.initials: A
authors.lastname: Rabinovitch
mesh_terms: D000447:Aldehydes / Q000378:metabolism*; D000818:Animals; D016923:Cell Death; D002851:Chromatography, High Pressure Liquid; D016207:Cytokines / Q000494:pharmacology*; D007371:Interferon-gamma / Q000494:pharmacology; D007375:Interleukin-1 / Q000494:pharmacology; D007515:Islets of Langerhans / Q000187:drug effects* / Q000502:physiology; D008297:Male; D008315:Malondialdehyde / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology
chemical_list: D000447:Aldehydes; D016207:Cytokines; D007375:Interleukin-1; D014409:Tumor Necrosis Factor-alpha; D008315:Malondialdehyde; D007371:Interferon-gamma; C010463:n-hexanal; C027576:4-hydroxy-2-nonenal