Mechanisms underlying resistance of pancreatic islets from ALR/Lt mice to cytokine-induced destruction.
Nuclear and mitochondrial genomes combine in ALR/Lt mice to produce systemically elevated defenses against free radical damage, rendering these mice resistant to immune-mediated pancreatic islet destruction. We analyzed the mechanism whereby isolated islets from ALR mice resisted proinflammatory stress mediated by combined cytokines (IL-1beta, TNF-alpha, and IFN-gamma) in vitro. Such damage entails both superoxide and NO radical generation, as well as peroxynitrite, resulting from their combination. In contrast to islets from other mouse strains, ALR islets expressed constitutively higher glutathione reductase, glutathione peroxidase, and higher ratios of reduced to oxidized glutathione. Following incubation with combined cytokines, islets from control strains produced significantly higher levels of hydrogen peroxide and NO than islets from ALR mice. Nitrotyrosine was generated in NOD and C3H/HeJ islets but not by ALR islets. Western blot analysis showed that combined cytokines up-regulated the NF-kappaB inducible NO synthase in NOD-Rag and C3H/HeJ islets but not in ALR islets. This inability of cytokine-treated ALR islets to up-regulate inducible NO synthase and produce NO correlated both with reduced kinetics of IkappaB degradation and with markedly suppressed NF-kappaB p65 nuclear translocation. Hence, ALR/Lt islets resist cytokine-induced diabetogenic stress through enhanced dissipation and/or suppressed formation of reactive oxygen and nitrogen species, impaired IkappaB degradation, and blunted NF-kappaB activation. Nitrotyrosylation of beta cell proteins may generate neoantigens; therefore, resistance of ALR islets to nitrotyrosine formation may, in part, explain why ALR mice are resistant to type 1 diabetes when reconstituted with a NOD immune system.
Diabetes Institute, Children's Hospital of Pittsburgh, University of Pittsburgh School of Medicine, 3460 5th Avenue, Pittsburgh, PA 15221, USA. cem65@pitt.edu
Clayton E
CE
Mathews
Wilma L
WL
Suarez-Pinzon
Jeffrey J
JJ
Baust
Ken
K
Strynadka
Edward H
EH
Leiter
Alex
A
Rabinovitch
D021581:Active Transport, Cell Nucleus; D000818:Animals; D015415:Biomarkers / Q000378:metabolism; D002478:Cells, Cultured; D016207:Cytokines / Q000633:toxicity*; D003922:Diabetes Mellitus, Type 1 / Q000276:immunology* / Q000378:metabolism / Q000473:pathology* / Q000503:physiopathology; D005260:Female; D005609:Free Radicals / Q000378:metabolism; D051550:I-kappa B Kinase; D020672:I-kappa B Proteins / Q000378:metabolism; D007113:Immunity, Innate / Q000235:genetics; D018836:Inflammation Mediators / Q000633:toxicity; D007515:Islets of Langerhans / Q000201:enzymology / Q000276:immunology* / Q000378:metabolism / Q000473:pathology*; D051379:Mice; D008809:Mice, Inbred C3H; D016688:Mice, Inbred NOD; D008815:Mice, Inbred Strains; D016328:NF-kappa B / Q000037:antagonists & inhibitors / Q000378:metabolism; D019001:Nitric Oxide Synthase / Q000096:biosynthesis; D052247:Nitric Oxide Synthase Type II; D018384:Oxidative Stress; D017346:Protein Serine-Threonine Kinases / Q000172:deficiency / Q000378:metabolism; D026361:Reactive Nitrogen Species / Q000096:biosynthesis; D051996:Transcription Factor RelA
D015415:Biomarkers; D016207:Cytokines; D005609:Free Radicals; D020672:I-kappa B Proteins; D018836:Inflammation Mediators; D016328:NF-kappa B; D026361:Reactive Nitrogen Species; D051996:Transcription Factor RelA; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; C496317:Nos2 protein, mouse; D017346:Protein Serine-Threonine Kinases; C496564:Chuk protein, mouse; D051550:I-kappa B Kinase; C496562:Ikbkb protein, mouse; C496566:Ikbke protein, mouse