Type 1 diabetes (T1D) results from an autoimmune destruction of pancreatic insulin-producing (-cells. Though exogenous insulin replacement corrects hyperglycemia, a restoration of physiological glucose responsiveness has been elusive until the advent of islet replacement therapy which is limited by a significant donor shortage, a requirement for long-term immunosuppression and poor long-term islet survival. We have successfully used in vivo gene transfer of Ngn3/Betacellulin as a modality to generate insulin-producing islet-like clusters in the liver that reverse diabetes in the STZ-diabetic mouse model. This proposal is based on the hypothesis that gene therapy-induced islets, engineered to resist autoimmune destruction by transgene-mediated suppression of cytokine signaling, can restore euglycemia in T1D. Any islet neogenesis is still susceptible to destruction by cytokines ?released from auto-reactive T-cells. Blocking the intracellular signaling of these apoptosis-inducing cytokines could therefore prevent the destruction of these new islets. SOCS-1 &SOCS-3 have been shown to negatively regulate the signaling of these cytokines in islets. We, therefore, reasoned that Ngn3-induced islet neogenesis could be protected from cytokine-induced apoptosis by over-expression of SOCS-1 and SOCS-3 in the NOD mouse, an autoimmune mouse model of type 1 diabetes. The broad goal of this proposal, therefore, is to induce endogenous islet neogenesis that is resistant to cytokine mediated apoptosis, as a means to restore euglycemia and glucose tolerance, in an autoimmune diabetes mouse model. The data from this research will provide a proof-of-concept for in vivo gene therapy-induced engineered islet neogenesis as a viable curative therapy for autoimmune type 1 diabetes.
The specific aims of this proposal are: 1.To restore euglycemia and glucose tolerance in diabetic NOD mice by protecting the ectopic islet neogenesis, induced using Neurogenin3 (Ngn3), with SOCS-1/SOCS-3 delivered to the liver via a helper dependent adenoviral (HDAd) vector and assess glucose-stimulated insulin secretion in vivo. 2. To elucidate the mechanism underlying the response to Ngn3-BTC-SOCS treatment by studying the immune system after therapy in these mice by directly assessing plasma and tissue cytokine levels along with autoreactive and regulatory T-cell functions. An assessment whether autoimmunity persists in these treated mice will also be established by adoptive transfer of their splenocytes into NOD-Scid mice.
The need for islet replacement strategies that do not depend on donor availability and chronic immunosuppression compels us to look for induction of islet neogenesis as an alternative approach. With encouraging preliminary results, this proposal addresses this need by using in vivo gene therapy, in NOD mice, to induce ectopic islet neogenesis that is engineered by target cell specific over expression of the cytokine signaling suppressor, SOCS-1 and SOCS-3 individually or in combination. The results from this study will lead to strong data to further refine in vivo gene therapy as part of a potential curative islet regenerative approach.
| Li, Rongying; Lee, Jeongkyung; Kim, Mi-sun et al. (2015) PD-L1-driven tolerance protects neurogenin3-induced islet neogenesis to reverse established type 1 diabetes in NOD mice. Diabetes 64:529-40 |
| Yechoor, Vijay; Chan, Lawrence (2010) Minireview: beta-cell replacement therapy for diabetes in the 21st century: manipulation of cell fate by directed differentiation. Mol Endocrinol 24:1501-11 |
