Deletion of 12/15-lipoxygenase alters macrophage and islet function in NOD-Alox15(null) mice, leading to protection against type 1 diabetes development

PLoS One. 2013;8(2):e56763. doi: 10.1371/journal.pone.0056763. Epub 2013 Feb 21.

Abstract

Aims: Type 1 diabetes (T1D) is characterized by autoimmune depletion of insulin-producing pancreatic beta cells. We showed previously that deletion of the 12/15-lipoxygenase enzyme (12/15-LO, Alox15 gene) in NOD mice leads to nearly 100 percent protection from T1D. In this study, we test the hypothesis that cytokines involved in the IL-12/12/15-LO axis affect both macrophage and islet function, which contributes to the development of T1D.

Methods: 12/15-LO expression was clarified in immune cells by qRT-PCR, and timing of expression was tested in islets using qRT-PCR and Western blotting. Expression of key proinflammatory cytokines and pancreatic transcription factors was studied in NOD and NOD-Alox15(null) macrophages and islets using qRT-PCR. The two mouse strains were also assessed for the ability of splenocytes to transfer diabetes in an adoptive transfer model, and beta cell mass.

Results: 12/15-LO is expressed in macrophages, but not B and T cells of NOD mice. In macrophages, 12/15-LO deletion leads to decreased proinflammatory cytokine mRNA and protein levels. Furthermore, splenocytes from NOD-Alox15(null) mice are unable to transfer diabetes in an adoptive transfer model. In islets, expression of 12/15-LO in NOD mice peaks at a crucial time during insulitis development. The absence of 12/15-LO results in maintenance of islet health with respect to measurements of islet-specific transcription factors, markers of islet health, proinflammatory cytokines, and beta cell mass.

Conclusions: These results suggest that 12/15-LO affects islet and macrophage function, causing inflammation, and leading to autoimmunity and reduced beta cell mass.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Arachidonate 12-Lipoxygenase / genetics*
  • Arachidonate 12-Lipoxygenase / metabolism
  • Arachidonate 15-Lipoxygenase / genetics*
  • Arachidonate 15-Lipoxygenase / metabolism
  • Diabetes Mellitus, Type 1 / genetics*
  • Diabetes Mellitus, Type 1 / therapy
  • Humans
  • Insulin / metabolism
  • Insulin-Secreting Cells / cytology
  • Insulin-Secreting Cells / metabolism
  • Interleukin-12 / metabolism
  • Islets of Langerhans / cytology
  • Islets of Langerhans / enzymology
  • Islets of Langerhans / metabolism
  • Macrophages / cytology
  • Macrophages / enzymology*
  • Macrophages / metabolism
  • Mice
  • Mice, Inbred NOD / genetics
  • Oxygenases / genetics*

Substances

  • 12-15-lipoxygenase
  • Insulin
  • Interleukin-12
  • Oxygenases
  • Alox15 protein, mouse
  • Arachidonate 12-Lipoxygenase
  • Arachidonate 15-Lipoxygenase
  • nitric oxide dioxygenase

Grant support

This work was funded by grants from the Juvenile Diabetes Research Foundation (www.jdrf.org,40-2009-711), and the American Diabetes Association (www.diabetes.org, 7-11-JF-33). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.