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Type 1 diabetes (T1D) is an autoimmune disease resulting in pancreatic b-cell lysis via reactive oxygen species (ROS), pro-inflammatory cytokines, and islet-infiltrating leukocytes. One promising treatment for T1D is islet transplantation, but its clinical application is constrained due to islet availability, adverse effects of immunosuppressants on islet function, and declining graft survival. Islet encapsulation may provide an immunoprotective barrier to aid in preserving function and curbing immune-mediated rejection post transplantation. We previously demonstrated that a cytoprotective nanothin multilayer coating consisting of tannic acid (TA), an immunomodulatory antioxidant, and poly (N-vinylpyrrolidone) (PVPON), curtailed immune responses involved in transplant rejection. We hypothesized that (PVPON/TA) coating may hinder the synthesis of redox-sensitive chemokines that recruit immune cells to sites of islet engraftment and blunt ROS-dependent cues necessary for M1 macrophage differentiation. (PVPON/TA) coatings elicited a 7-fold decrease in M1 macrophage-derived pro-inflammatory chemokines CCL5 and CXCL10, blunted M1 macrophage activation markers, and curbed diabetogenic CD4 T cell migration approximately 2-fold. Importantly, murine islet encapsulation with (PVPON/TA) material restored euglycemia in immunodeficient-diabetic mice post transplantation. Our studies demonstrate that (PVPON/TA) multilayer coatings represent a promising immunomodulatory biomaterial for islet transplantation. Future studies will evaluate the efficiency of PVPON/TA coated islets in curbing hyperglycemia by allotransplantation into diabetic rodent models.

Reactive oxygen species (ROS) induces Type-1 diabetes (T1D) by directly killing pancreatic β-cells, triggering pro-inflammatory cytokine production, and promoting autoreactive T cell maturation. We hypothesize that free radical synthesis in T1D can synergize and enhance autoimmune responses in T1D onset and progression. Free radicals can be identified by immuno-spin trapping with 5,5-dimethyl-1-pyrroline N-oxide (DMPO) and utilizing a DMPO-specific antibody to detect DMPO-radical adducts. We previously reported a delay in spontaneous T1D onset in Non-obese diabetic (NOD) mice impaired in NADPH Oxidase (NOX)-derived superoxide synthesis (NOD.Ncf1m1J). Bone marrow-derived macrophages (BM-Mϕ) from NOD.Ncf1m1J mice infected with Coxsackie virus CB3 strain displayed a significant decrease (p

In autoimmune Type 1 diabetes (T1D), islet-infiltrating leukocytes synthesize noxious free radicals to collectively mediate b-cell lysis and enhance diabetogenic T cell responses as a pro-inflammatory third signal. We recently demonstrated a crucial role for NADPH oxidase (NOX)-dependent superoxide in T1D, as NOX-deficient Non-obese diabetic (NOD.Ncf1m1J) mice were highly resistant to autoimmune diabetes due to an enhanced alternatively-activated M2 macrophage phenotype, diminished pro-inflammatory cytokine and Type I interferon synthesis upon Toll-like receptor stimulation, dampened Th1 cytokine responses, and blunted CD8 T cell cytotoxicity. To further define the synergy between free radicals and T1D, we employed a 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) immuno-spin trapping technique to identify the generation of free radicals upon T cell activation and infection with Coxsackie B4 (CB4) virus, a putative diabetogenic enterovirus and hypothesized that NOD.Ncf1m1J immune cells would exhibit severe reductions in DMPO adducts. In the absence of superoxide, NOD.Ncf1m1J macrophages and CD4 T cells exhibited a significant decrease in DMPO adducts upon CB4 infection and autoantigen stimulation, respectively, in contrast to wild type cells. Future studies will utilize this technique to visualize the interface between free radicals and immune cells during spontaneous T1D progression and determine if immuno-spin trapping can be used as a biomarker during spontaneous T1D progression.

In Type 1 diabetes (T1D), infiltrating leukocytes secrete reactive oxygen species (ROS) and pro-inflammatory cytokines that participate in β-cell destruction and enhance T cell autoreactivity. We previously demonstrated that superoxide-deficient Non-obese diabetic (NOD.Ncf1m1J) mice were T1D-resistant due, in part, to blunted Th1 CD4 and cytotoxic CD8 T cell responses. To dissect the role of ROS on autoreactive CD4 T cells, we created the NOD.BDC-2.5.Ncf1m1J (BDC-2.5.Ncf1m1J) mouse with diabetogenic, superoxide-deficient CD4 T cells and hypothesized that reducing ROS would diminish autoreactivity. BDC-2.5.Ncf1m1J splenocytes stimulated with the BDC-2.5 mimotope or islets displayed elevated IFN-γ and pro-inflammatory chemokine ligands CXCL10 and CCL5 (p