Date of Award


Degree Type


Degree Name

Doctor of Philosophy




Dr. Shengwu Ma

Second Advisor

Dr. Norm Huner

Third Advisor

Dr.Anthony Jevnikar


Using transgenic plants to express and deliver autoantigens represents an attractive strategy to induce oral tolerance to treat autoimmune diseases. Several challenges remain if this approach is applied to treat diabetes. This thesis aims to address these challenges through an investigation into: 1) the use of transgenic plants to express human preproinsulin, and an adjuvant-autoantigen fusion protein comprising human preproinsulin fused to mIL-4 for oral tolerance induction; 2) the use of transgenic plants to express hGAD67 to induce oral tolerance; 3) the exploration of chloroplasts of the alga Chlamydomonas reinhardtii as a novel expression platform for high-level, industrial scale production of diabetes related antigens like hGAD65 and IGF-I. Oral administration of mIL-4-hIns-SE plants accelerated the diabetes in NOD mice. Increased level of anti-insulin IgG2c subclass, together with the greatest bias to a Thl cytokine pattern in mIL-4-hIns-SE treatment suggested oral mIL-4-hIns-SE may prime a diabetes-favoring Thl-type response, thus accounting for the acceleration. Oral administration of hGAD67 plants reduced insulitis and delayed the onset of diabetes in NOD mice. The protection was associated with the inactivation of GAD autoreactive T-cells as well as a shift in the balance between Thl and Th2 cell responses towards Th2 dominance. hGAD65 and IGF-I was introduced to alga chloroplast by particle bombardment. The accumulation level of hGAD65 reached up to 0.2-0.3% TSP, approximately 5 to 8 fold higher compared to its nuclear expression in transgenic plants. The accumulation level of IGF-I was about 0.026% TSP, which is around 10 fold increased as compared to its nuclear expression in tobacco plants. The antigenicity of algal-derived hGAD65 was iii demonstrated with its immunoreactivity to diabetes sera and by its ability to induce proliferation of spleen cells from NOD mice. The biological activity of algal-derived IGF-I was demonstrated with its ability to induce the proliferation of TF-1 cells.



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