Homing of GAD65 specific autoimmunity and development of insulitis requires expression of both DQ8 and human GAD65 in transgenic mice

Abstract

MHC-class II genes determine susceptibility in human type-1 diabetes. In their context, presentation of target antigen(s) results in autoimmunity and β-cell destruction. An animal model, in which human β-cell autoantigen(s) are presented to effector-cells in the context of human MHC-class II diabetes susceptibility genes, would be desirable for studying molecular mechanisms of disease and developing antigen-specific immune-interventions. We report the development of antigen-specific insulitis in double-transgenic mice carrying the HLA-DQ8 diabetes susceptibility haplotype and expressing the human autoantigen GAD65 in pancreatic β-cells. Immunization with human GAD65 cDNA resulted in severe insulitis and low antibody levels in double-transgenic mice while control mice were mostly insulitis free. CFA/protein immunization resulted in high antibody levels and modest insulitis. Pancreatic lymphocytic infiltration progressed through stages (exocrine pancreas followed by peri and intra-insulitis). Adoptive transfer of splenocytes from DNA-immunized mice resulted in development of insulitis in recipient transgenics. Our results show that immunization with a clinically relevant, type-1 diabetes human autoantigen, in a humanized genetic setting, results in the development of an immune response that homes to islets of Langerhans. This animal model will facilitate studies of autoimmunity to GAD65 in the context of HLA-DQ8, and development of methods to induce tolerance and prevent insulitis.

Eukaryotic translation initiation factor 5A inhibition alters physiopathology and immune responses in a “humanized” transgenic mouse model of type 1 diabetes

“…We have generated transgenic mice that express high levels of human GAD65 in ␤-cells and at the same time have their endogenous mouse MHC-class II replaced by the human HLA-DQ8 diabetes-susceptibility gene (5,6,8). Our double-transgenic mice develop impaired fasting blood glucose, glucose intolerance, and diabetes when immunized with adenoviral hGAD65.…”

“…Murine MHC-class II molecule-deficient (mII Ϫ ), HLA-DQA1*0301/DQB1*0302 (DQ8) (20), and hGAD65 (19) transgenic mice (5) in BTBR background (6) were used in this study. DQ8 and hGAD65 homozygosity was determined as previously described (5,6). All animal protocols were approved by the University of Wisconsin and the Veterans Affairs animal research committees.…”

“…Recent observations of human islets from diabetic patients have established a prominent role for CD8 ϩ T cells (3, 15). Therefore, facilitating CD4 ϩ T cell regulation of CD8ϩ T cells appears to be a promising therapeutic strategy.A T1D mouse model where antigen-specific diabetes after immunization with a clinically relevant human autoantigen, in the context of human MHC-class II diabetes-susceptibility transgenes occurs, was recently developed (5,6,8). In this transgenic model, human glutamic acid decarboxylase (GAD65) is expressed in pancreatic ␤-cells, and human MHC II (DQ8) is expressed in antigen-presenting cells (APCs).…”

“…In this transgenic model, human glutamic acid decarboxylase (GAD65) is expressed in pancreatic ␤-cells, and human MHC II (DQ8) is expressed in antigen-presenting cells (APCs). Upon a triggering event by which tolerance to GAD65 is broken in the periphery (1), APCs present antigen, activate T cells, and initiate the downstream events that lead to diabetes (5,6,8).Eukaryotic translation initiation factor 5A (eIF5A) is a small (17-kDa), highly conserved protein identified as a translation initiation/elongation factor (11). Studies in mammalian cells have showed that only 5% of protein translation in a quiescent cell is dependent on eIF5A (18) and that, in actively dividing mammalian cells, it is necessary for proteins involved in cell cycle progression (12).…”

Mold and Human Health: Separating the Wheat from the Chaff

“…Examples of literature which do focus on the mechanisms of autoimmune disease are readily found in recent literature and illustrate the absence of any suggestion of a mold association. In contrast, the mechanisms relate to both a genetic predisposition as well as ultimate loss of tolerance [28,[58][59][60][61][62][63][64][65][66][67][68].…”