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

Ablation of reactive oxygen species intensifies diabetogenic CD4 T cell effector responses (#102)

Lindsey E Padgett 1 , Hubert M Tse 1
  1. University of Alabama-Birmingham, Birmingham, AL, United States

In Type 1 diabetes (T1D), infiltrating leukocytes generate reactive oxygen species (ROS) and pro-inflammatory cytokines that collectively participate in β-cell destruction and enhance autoreactive T cell responses.  Our laboratory previously demonstrated that superoxide-deficient Non-Obese Diabetic (NOD.Ncf1m1J) mice are T1D-resistant partly due to skewed T cell responses.  To further dissect the role of ROS on autoreactive T cell effector responses, our laboratory generated the NOD.BDC-2.5.Ncf1m1J mouse, possessing diabetogenic CD4 T cells unable to synthesize superoxide.  We hypothesized that like NOD.Ncf1m1J, dampening ROS would diminish NOD.BDC-2.5 diabetogenic T cell responses.  Interestingly, in contrast to NOD.Ncf1m1J, IFN-γ was upregulated 2-fold by NOD.BDC-2.5.Ncf1m1J CD4 T cells compared to NOD.BDC-2.5 upon polyclonal stimulation (295.2 ±12.4ng/mL vs. 156.0 ±4.8ng/mL; p=0.0045).  Synthesis of TNF-α, a β-cell lytic pro-inflammatory cytokine, was significantly increased by superoxide-deficient CD4 T cells compared to NOD.BDC-2.5 upon polyclonal stimulation (1.10 ±0.04ng/mL vs. 0.80 ±0.04ng/mL; p=0.0006).  In addition to an enhanced in vitro pro-inflammatory cytokine response, adoptive transfer of pre-activated NOD.BDC-2.5.Ncf1m1J CD4 T cells was more diabetogenic, as 63% of NOD.scid recipients (n=11, p=0.0662) by 9 days post transfer were hyperglycemic, in contrast to only 17% of wild-type-transferred mice (n=7).  Providing mechanistic evidence for the enhanced pro-inflammatory profile and diabetogenicity in the absence of superoxide, activated NOD.BDC-2.5.Ncf1m1J CD4 T cells displayed 1.5- and 2-fold enhanced phosphorylation of redox-sensitive tyrosine kinases within the T cell receptor (TCR) signaling cascade, lymphocyte-specific protein tyrosine kinase (P-Lck (Y505)) and linker for activation of T cells (P-LAT (Y191)), respectively, compared to NOD.BDC-2.5.  Future experiments will further analyze the redox-sensitive cues that modulate TCR adaptor molecule activation profiles within NOD.BDC-2.5.Ncf1m1J T cells and investigate macrophage recruitment within CD4 T cell adoptive transfers, a BDC-2.5 T cell mechanism of disease transfer.  Ultimately, unraveling the redox-dependent signals for maturing autoreactive T cell responses may pinpoint novel targets for T1D prevention.