Poster Presentation The 13th International Congress of the Immunology of Diabetes Society 2013

Natural Killer Cell Function and Phenotype in NOD and NOD-Alox15null Mice (#169)

Nicole M. Lee 1 , Lindsey M. Glenn 2 , Norine S. Kuhn 2 , Margaret A. Morris 2
  1. Biochemistry, Old Dominion University, Norfolk, VA, USA
  2. Eastern Virginia Medical School, Norfolk, VA, United States

Compelling evidence suggests that the gene encoding the 12/15-lipoxygenase (12/15-LO) enzyme plays a significant role in the development of type 1 diabetes (T1D) in the non-obese diabetic (NOD) strain of mice.  Mice lacking 12/15-LO (NOD-Alox15null) are nearly completely protected from T1D development, which may be partially due to the absence of 12/15-LO production by macrophages.  Macrophages have been shown to appear early in T1D development, and as potent producers of IL-12, they are capable of activating natural killer (NK) cells, which also appear in the islets early in the disease process.  We hypothesized that downstream NK cell function would be altered due to indirect (i.e., decreased cytokine production from macrophages), rather than direct effects of the 12/15-LO deficiency.  To test this idea, NK cells were isolated from the spleens and bone marrow of NOD and NOD-Alox15null mice.  mRNA was isolated for use in qRT-PCR assays.  PMA- and ionomycin-stimulated cells from spleen, pancreatic draining lymph nodes, and pancreas tissues were analyzed for cytokine production and extracellular markers by flow cytometry.  As expected, levels of 12/15-lipoxygenase were detected in NOD (ΔCt<0.12 compared to >400 for macrophages), but not NOD-Alox15nullNK cells (ΔCt<0.01).  In the absence of 12/15-LO, both the expression of activating NKG2D and IL-12Rβ1 receptors were significantly increased.  STAT4 and IFN-γ mRNA levels, however, were decreased, which is expected in the absence of 12/15-LO.  Protein levels are currently being assessed.  The Ly49 receptor repertoire was proportionally skewed towards activating receptors in NOD-Alox15nullNK cells.  The alterations seen in NOD-Alox15nullnatural killer cells may affect the pathogenesis of type 1 diabetes, and explain the protection afforded to the NOD-Alox15nullmice.  These studies could form the basis for proposing new therapies to halt immune damage to pancreatic beta cells in T1D.  This work was supported by a Junior Faculty Award from ADA.