Inducible nitric oxide synthase (iNOS) in pancreatic islets of nonobese diabetic mice: identification of iNOS- expressing cells and relationships to cytokines expressed in the islets.
Inflammatory cytokines and nitric oxide (NO) are candidate mediators of pancreatic islet beta-cell destruction in insulin-dependent diabetes mellitus. In this study, we used a semiquantitative PCR assay to measure levels of messenger RNA (mRNA) expression of the inflammatory cytokines, interleukin-1 alpha (IL-1 alpha), tumor necrosis factor-alpha, and interferon-gamma (IFN gamma), and of the inducible form of NO synthase (iNOS) in mononuclear leukocytes isolated from pancreatic islets of autoimmune diabetes-prone nonobese diabetic (NOD) female mice. We found that mRNA levels of iNOS, IL-1 alpha, and IFN gamma in islet mononuclear leukocytes increased from 5 weeks of age to onset of diabetes ( > 13 weeks of age). To determine whether increased iNOS, IL-1 alpha, and IFN gamma mRNA expressions were related to diabetes development, we compared mRNA levels of these molecules in mononuclear leukocytes from islets of 12 week-old diabetes-prone NOD female mice and three groups of 12-week-old mice with low diabetes risk: NOD female mice injected with complete Freund's adjuvant at 4 weeks of age, NOD male mice, and BALB/c female mice that do not develop diabetes. We found that iNOS, IL-1 alpha, and IFN gamma mRNA levels were higher in mononuclear leukocytes from islets of diabetes-prone NOD female mice than in those from mice correlated with IL-1 alpha and IFN gamma mRNA levels. By using specific antibodies and immunohistochemical methods, we localized iNOS in macrophages as well as in beta-cells of islets from diabetes-prone NOD female mice. These findings suggest that IL-1 alpha and IFN gamma may promote islet beta-cell destruction at least in part by up-regulating iNOS expression an No production by both macrophages and beta-cells in the islets of autoimmune diabetes-prone NOD mice.
Rabinovitch
A
A
Department of Medicine, University of Alberta, Edmonton, Canada.
Suarez-Pinzon
W L
WL
Sorensen
O
O
Bleackley
R C
RC
D000818:Animals; D001483:Base Sequence; D016207:Cytokines / Q000235:genetics*; D003922:Diabetes Mellitus, Type 1 / Q000201:enzymology*; D005260:Female; D015870:Gene Expression; D006801:Humans; D007371:Interferon-gamma / Q000235:genetics; D007375:Interleukin-1 / Q000235:genetics; D007515:Islets of Langerhans / Q000201:enzymology* / Q000378:metabolism; D007963:Leukocytes, Mononuclear / Q000378:metabolism; D008264:Macrophages / Q000201:enzymology; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D016688:Mice, Inbred NOD; D008969:Molecular Sequence Data; D019001:Nitric Oxide Synthase / Q000096:biosynthesis*; D012333:RNA, Messenger / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics
D016207:Cytokines; D007375:Interleukin-1; D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha; D007371:Interferon-gamma; D019001:Nitric Oxide Synthase