Engineering a Cure for Diabetes Abstract
Type 1 diabetes (T1D) is a chronic, life threatening, autoimmune disease. Currently there is no effective therapy for this disease. Accumulated evidence suggests that T lymphocytes including T helper 1 (Th1) and T helper 2 (Th2) play a crucial role in T1D development. The disease is primarily mediated by Th1 lymphocytes that synthesize inflammatory cytokine interferon ¦Ã (INF-¦Ã), whereas Th2 cells, which produce anti-inflammatory cytokines, have a beneficial, protective role. Thus, induction of selective deviation (skewing) of harmful Th1 responses towards a protective Th2 phenotype using Th2 cytokines such as IL-13 represents the most promising antigen-specific therapeutic approach. The objective of this study is to produce large amounts of IL-13 in transgenic plants and to test if the plant-derived cytokines can be used for oral administration to treat T1D. The human IL-13 gene was cloned and fused with the bacterial CTB gene encoding the mucosal carrier CTB protein that will facilitate effective delivery of the CTB-IL-13 recombinant protein to the gut mucosal cells. CTB-IL-13 and IL-13 were cloned into a plant transformation vector under the control of a constitutive expression promoter. Low-nicotine tobacco was used for Agrobacterium-mediated genetic transformation. PCR analysis confirmed the presence of the transgenes in the transgenic plants. The expression of IL-13 and CTB-IL-13 in the transgenic plants was demonstrated by northern blot hybridization and western blot analysis. The plant-derived IL-13 was shown to be biologically active, retaining its ability to induce T-cell proliferation. The availability of transgenic tobacco plants expressing IL-13 and CTB-IL-13 provides a solid foundation for the development of a plant-based, safe, cost-effective, oral therapy for treatment of T1D.
