Reversing Autoimmune Diabetes with Gene Therapy Induced Islet Neogenesis

Baylor College Of Medicine, Houston TX

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Abstract

DESCRIPTION (provided by applicant): 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.