All ETDs from UAB

Advisory Committee Chair

Hubert M Tse

Advisory Committee Members

David D Chaplin

Kathryn Haskins

Robin G Lorenz

Chad Steele

Casey T Weaver

Document Type

Dissertation

Date of Award

2015

Degree Name by School

Doctor of Philosophy (PhD) Heersink School of Medicine

Abstract

Type 1 Diabetes (T1D) is an autoimmune disease culminating in pancreatic β-cell destruction, inducing reactive oxygen species (ROS), pro-inflammatory cytokines, and islet-infiltrating leukocutes. Macrophages, one of the first islet-infiltrating cells in T1D, secrete ROS and pro-inflammatory cytokines, which lyse pancreatic β-cells and activate diabetogenic T cells to further propagate β-cell destruction, while autoreactive CD4 T cells recruit islet-infiltrating, pro-inflammatory, M1 macrophages, and enhance CD8 T cell cytotoxicity. We previously demonstrated the importance of NADPH oxidase (NOX)-derived ROS synthesis in T1D, as Non-obese diabetic (NOD) mice lacking NOX-derived superoxide (NOD.Ncf1m1J) exhibited a delay in spontaneous and adoptive transfer of T1D. In concert with T1D protection, NOD.Ncf1m1J macrophages and CD4 T cells were less pro-inflammatory. Therefore, we hypothesized that dampened ROS synthesis within NOD.Ncf1m1J mice contributed to blunted pro-inflammatory M1 and/or enhanced anti-inflammatory M2 macrophages. Analysis of islet-resident NOD.Ncf1m1J macrophages during spontaneous T1D progression revealed a skewed M2 phenotype, indicating that targeting macrophage redox status may represent a promising therapy in halting T1D. Based on the lessened Th1 cytokine response by NOX-deficient NOD mice, we created the NOD.BDC-2.5.Ncf1m1J mouse, possessing superoxide-deficient, autoreactive CD4 T cells to further dissect the role of ROS on diabetogenic CD4 T cells. We hypothesized that NOX-deficient NOD.BDC-2.5 CD4 T cells would display reduced diabetogenicity, but surprisingly, stimulated NOD.BDC-2.5.Ncf1m1J CD4 T cells displayed enhanced pro-inflammatory T helper (Th) 1 cytokines and chemokines compared to NOX-intact CD4 T cells. Transfer of NOX-deficient NOD.BDC-2.5 CD4 T cells into NOD.Rag recipients elicited enhanced diabetogenicity, partly due to defective T regulatory (Treg) cell suppression, demonstrating an essential role for NOX-derived superoxide in maintaining peripheral tolerance. To further characterize ROS modulation of non-autoreactive CD4 T cell responses, we generated the OT-II.Ncf1m1J mouse, possessing superoxide-deficient CD4 T cells recognizing OVA323-339. OT-II.Ncf1m1J CD4 T cells displayed attenuated Th1 cytokine and chemokine responses, in concert with reduced IL-12 signaling, further highlighting the function of ROS as a pro-inflammatory third signal. Collectively, these results demonstrate that NOX-derived superoxide plays very complex roles in the immune response. With functions in immune response activation and attenuation, ROS potently affect innate and adaptive immune responses under autoreactive and non-autoreactive conditions.

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