Search

Pancreatic islet transplantation has the potential to maintain normoglycemia in patients with established type 1 diabetes, thereby obviating the need for frequent insulin injections. Our previous study showed that recombinant IL-12p40-producing islets prevented the recurrence of NOD diabetes. First, to see which immunomodulating molecule-secreting islet grafts can most powerfully prevent diabetes development in NOD mice without immunosuppressant, NOD islets were transfected with one of the following adenoviral vectors: Ad.IL-12p40, Ad.TGF-beta, Ad.CTLA4-Ig, or Ad.TNF-alpha after which they were transplanted under the renal capsule of acutely diabetic NOD mice. The immunomodulating molecules produced by these adenovirus-transfected islets in vitro were 74+/-19ng, 50+/-4ng, 821+/-31ng, and 77+/-18ng/100 islets, respectively. Transplantation of IL-12p40, TNF-alpha, and CTLA4-Ig but not TGF-beta-secreting islets displayed enhanced survival and delayed diabetes recurrence in recent-onset diabetic recipients. IL-12p40-producing islet grafts most powerfully prevented recurrent diabetes in NOD mice. In addition, local production of TNF-alpha and CTLA4-Ig significantly prolonged islet graft survival. In second series of experiment, these manipulated islets were transplanted under the renal capsule of 10-week-old NOD recipients and were also transplanted subcutaneously into 2-week-old NOD recipients. Transplantation of these islets into 2- or 10-week-old pre-diabetic mice failed to protect them from developing diabetes; in fact, transplantation of Ad.TNF-alpha-transfected islets into 2-week-old mice actually accelerated diabetes onset. Taken together, this approach was ineffectual as a prophylactic protocol. In conclusion, this study showed comparisons of the immunomodulating effects of 4 different adenoviral vectors in the same transplantation model and local production of IL-12p40, TNF-alpha and CTLA4-Ig significantly prevented recurrent diabetes in NOD mice.

Rodents have two functional preproinsulin genes named insulin 1 and insulin 2 on different chromosome and have two amino acid differences in insulin B chain. We have established insulin 1 or insulin 2 knockout (KO) non-obese diabetic (NOD) colonies in the animal institute of Kobe University and evaluated anti-insulin autoimmunity. Similar to the previous report, insulin 1-KO provides strong protection from insulitis (islet-infiltration of mononuclear cells) and diabetes, whereas the insulin 2-KO markedly accelerated insulitis and development of diabetes even at further backcross breeding with NOD/Shi/Kbe mice (P

Type 1 diabetes (T1D) is caused mostly by autoimmune destruction of pancreatic β-cells, the precise mechanism of which remains unclear. Two major effector mechanisms have been proposed: direct cell-mediated and indirect cytokine-mediated cytotoxicity. Cytokine-mediated β-cell destruction is presumed mainly caused by NO production. To evaluate the role of iNOS expression in T1D, this study used a novel iNOS inhibitor ONO-1714. ONO-1714 significantly reduced cytokine-mediated cytotoxicity and NO production in both MIN6N9a cells and C57BL/6 islets in the presence of IL-1β, TNF-α, and IFN-γ. To evaluate whether NO contributes to diabetes progression in vivo , ONO-1714 was administered to four different mouse models of autoimmune diabetes: multiple low-dose STZ (MLDS)-induced C57BL/6, CY-induced, adoptive transfer and spontaneous NOD diabetes. Exposure to STZ in vitro induced NO production in MIN6N9a cells and C57BL/6 islets, and in vivo injection of ONO-1714 to MLDS-treated mice significantly reduced hyperglycemia and interestingly, led to complete suppression of cellular infiltration of pancreatic islets. In contrast, when ONO-1714 was injected into spontaneous NOD mice and CY-induced and adoptive transfer models of NOD diabetes, overt diabetes could not be inhibited in these models. These findings suggest that NO-mediated cytotoxicity significantly contributes to MLDS-induced diabetes but not to NOD diabetes.

'Fulminant diabetes' has been recognized as a super-acute onset and non-autoimmune type 1 diabetes. To evaluate autoimmunity against pancreatic beta cell in fulminant diabetes, ELISPOT assay was applied to the peripheral blood of these patients. In our ELISPOT system, GAD65-reactive and insulin B9-23-reactive IFN-gamma spots were detected in 46.3 and 26.0% of autoantibody-positive type 1 diabetes. Also, in fulminant type 1 diabetic patients, IFN-gamma spots in response to GAD65 and insulin B9-23 peptide were detected in 69.2 and 25.0%, respectively. These results suggest that anti-beta cell autoimmunity contributes to develop fulminant type 1 diabetes. Fulminant type 1 diabetes is known to have IDDM-resistant HLA DR2 with similar frequency of non-T1D subjects. In a mouse model, when islet-reactive CD8 cells are transferred to young NOD mice, the recipients develop overt diabetes within 1 week with massive insulitis. In (NOD x Balb/c) F1 mice, which hold idd-resistant genes, transfer of islet-reactive CD8 cells induced diabetes to 60% F1 recipients within 1 week with the later disappearance of insulitis. This mouse model shows very similar feathers to fulminant type 1 diabetes; idd-resistant HLA and no insulitis. These results implicated that once anti-islet immunity is optimally activated, subjects with partially resistant alleles could become overt diabetes.