Resistance to type 1 diabetes induction in 12-lipoxygenase knockout mice

J Clin Invest. 1999 May 15;103(10):1431-6. doi: 10.1172/JCI5241.

Abstract

Leukocyte 12-lipoxygenase (12-LO) gene expression in pancreatic beta cells is upregulated by cytotoxic cytokines like IL-1beta. Recent studies have demonstrated that 12-LO inhibitors can prevent glutamate-induced neuronal cell death when intracellular glutathione stores are depleted. Therefore, 12-LO pathway inhibition may prevent beta-cell cytotoxicity. To evaluate the role of 12-LO gene expression in immune-mediated islet destruction, we used 12-LO knockout (12-LO KO) mice. Male homozygous 12-LO KO mice and control C57BL/6 mice received 5 consecutive daily injections of low-dose streptozotocin to induce immune-mediated diabetes. Fasting serum glucose and insulin levels were measured at 7-day intervals, and the mice were followed up for 28 days. 12-LO KO mice were highly resistant to diabetes development compared with control mice and had higher serum insulin levels on day 28. Isolated pancreatic islets were treated with IL-1beta, TNF-alpha, and IFN-gamma for 18 hours. Glucose-stimulated insulin secretion in cytokine-treated islets from C57/BL6 mice decreased 54% from that of untreated islets. In marked contrast, the same cytokine mix led to only a 26% decrease in islets from 12-LO KO mice. Furthermore, cytokine-induced 12-hydroxyeicosatetraenoic acid (12-HETE) production was absent in 12-LO KO islets but present in C57/BL6 islets. Isolated peritoneal macrophages were stimulated for 48 hours with IFN-gamma + LPS and compared for nitrate/nitrite generation. 12-LO KO macrophages generated 50% less nitrate/nitrite when compared with C57BL/6 macrophages. In summary, elimination of leukocyte 12-LO in mice ameliorates low dose streptozotocin-induced diabetes by increasing islet resistance to cytokines and decreasing macrophage production of nitric oxide.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Arachidonate 12-Lipoxygenase / genetics*
  • Diabetes Mellitus, Experimental / enzymology
  • Diabetes Mellitus, Experimental / genetics
  • Diabetes Mellitus, Experimental / physiopathology
  • Diabetes Mellitus, Type 1 / enzymology*
  • Diabetes Mellitus, Type 1 / genetics*
  • Diabetes Mellitus, Type 1 / physiopathology
  • In Vitro Techniques
  • Insulin / metabolism
  • Insulin Secretion
  • Interferon-gamma / pharmacology
  • Interleukin-1 / pharmacology
  • Islets of Langerhans / drug effects
  • Islets of Langerhans / enzymology
  • Islets of Langerhans / metabolism
  • Male
  • Mice
  • Mice, Inbred C57BL
  • Mice, Knockout
  • Nitric Oxide / biosynthesis
  • Recombinant Proteins
  • Superoxides / metabolism
  • Tumor Necrosis Factor-alpha / pharmacology

Substances

  • Insulin
  • Interleukin-1
  • Recombinant Proteins
  • Tumor Necrosis Factor-alpha
  • Superoxides
  • Nitric Oxide
  • Interferon-gamma
  • Arachidonate 12-Lipoxygenase