12527 Determining The Impact Of Dampened Oxidative Stress On Islet Function And Gene Expression During Diabetes Onset In NOD Mice
Authors: Coutinho Kristen V , Deeba Iztiba M , Shinde Harshraj , Feduska Joseph , Burnette KaLia , Poole Samuel O , Tse Hubert M , Hunter Chad S 
Published: October 2024

Abstract
Disclosure: K.V. Coutinho: None. H. Shinde: None. J. Feduska: None. K. Burnette: None. S.O. Poole: None. H.M. Tse: None. C.S. Hunter: None.
Type 1 diabetes (T1D) arises from autoimmune destruction of insulin-producing pancreatic β-cells. Revealing the mechanisms underlying T1D onset are critical for therapeutic development but not completely understood. NADPH oxidase (NOX) generates superoxide, a precursor of reactive oxygen species (ROS), to regulate cell survival, differentiation, signaling, and autoimmune responses in T1D. NOD (Non-Obese Diabetic) mice spontaneously develop T1D, featuring increased cytokine/chemokine synthesis, inflammatory responsive macrophages and T cells, and ROS. Here, we harness NOD mice deficient in NOX-derived superoxide (NOD.Ncf1m[1]J), which have significantly lower T1D incidence. However, the impacts on islet β-cells in this T1D resistant model are unknown. We assessed a time course of glucose homeostasis between 6-20 weeks (W), spanning the onset T1D in NOD mice. Surprisingly, comparative glucose tolerance testing (GTT) in NOD.Ncf1m[1]J mice revealed increased glucose intolerance at 10W with no differences at 6, 14, and 20W as compared to NOD. Insulin tolerance was similar between the two models at all stages examined. This suggests superoxide production is necessary for β-cell function, despite that NOD.Ncf1m[1]J mice are T1D resistant. To understand islet transcriptomic changes between NOD and NOD.Ncf1m[1]J mice, we conducted comparative bulk islet RNA sequencing from 6 to 20W. Principal component analysis was applied to ensure differences between genotypes at each timepoint. Quality control methods within the Nextflow core pipeline were used to ensure sample quality. As expected, NOD.Ncf1m[1]J mice had decreased Ncf1 and immune response-related mRNA levels. Expression of T-cell exhaustion (Pdcd1, Lag3, and Tigit) genes remained level in NOD mice, but had significantly lower expression at 6W in NOD.Ncf1m[1]J mice. Interestingly, Ctla4, encoding a gene product that inhibits T-cell function, was upregulated at 14W in NOD.Ncf1m[1]J mice. Furthermore, GO analysis of downregulated NOD.Ncf1m[1]J gene sets include T-cell activation, response to IFN-β and IFN-γ at 6W, and decreased cytokine production at 20W. Supporting the dysregulation of β-cell function, Bace2, encoding a protease that limits β-cell function and mass, was upregulated with NOD. Ncf1m[1]J. Additionally, 14W β-cell function gene expression was decreased in the NOD.Ncf1m[1]J mice, including Slc2a2, which encodes the β-cell GLUT2 glucose transporter, and Glp1r, which is involved in preserving β-cell mass and function. Taken together, NOX-derived superoxide, whose loss decreases T1D incidence, may also dampen β-cell gene expression and function. Future directions will include comparative NOD and NOD.Ncf1m[1]J single cell transcriptomics to determine cell type specific transcriptional signatures between islet and immune cell subtypes.
Presentation: 6/2/2024