Mechanisms of cytokine-induced destruction of rat insulinoma cells: the role of nitric oxide.
Cytokines produced by immune system cells infiltrating pancreatic islets are candidate mediators of islet beta-cell destruction in insulin-dependent diabetes mellitus. In this study, we examined the role of nitric oxide (NO) as a mediator of cytokine-induced islet beta-cell destruction in a rat insulinoma cell line (RINm5F). The cytokine combination of interleukin-1 beta (IL-1 beta; 10 U/ml), tumor necrosis factor-alpha (10(3) U/ml), and interferon-gamma (10(3) U/ml) induced DNA fragmentation (first detected at 6 h), mitochondrial damage (by 12 h), and death (by 24 h) of RIN cells, whereas the individual cytokines did not have these destructive effects. Also, the cytokine combination of IL-1 beta, tumor necrosis factor-alpha, and interferon-gamma induced a 10-fold increase in NO production by RIN cells, and L-NG-monomethyl arginine, an inhibitor of NO synthase, produced a dose-dependent inhibition of cytokine-induced NO production, DNA fragmentation, and cell destruction. However, IL-1 beta, acting alone, induced a 7-fold increase in NO production without causing DNA fragmentation, mitochondrial damage, or cell destruction. In addition, nicotinamide, a known inhibitor of ADP ribosylation and scavenger of oxygen free radicals, inhibited cytokine-induced DNA fragmentation and cell destruction without affecting NO production. We conclude that stimulation of NO production may be a necessary, but not sufficient, condition for cytokine-induced destruction of islet beta-cells.
Suarez-Pinzon
W L
WL
Department of Medicine, University of Alberta, Edmonton, Canada.
Strynadka
K
K
Schulz
R
R
Rabinovitch
A
A
D000818:Animals; D001120:Arginine / Q000031:analogs & derivatives / Q000494:pharmacology; D016207:Cytokines / Q000494:pharmacology*; D004247:DNA / Q000378:metabolism; D007340:Insulinoma / Q000473:pathology*; D009569:Nitric Oxide / Q000502:physiology*; D010190:Pancreatic Neoplasms / Q000473:pathology*; D051381:Rats; D014407:Tumor Cells, Cultured; D019323:omega-N-Methylarginine
D016207:Cytokines; D019323:omega-N-Methylarginine; D009569:Nitric Oxide; D004247:DNA; D001120:Arginine