Autoimmune diabetes in the nonobese diabetic mouse: suppression of immune defects by bone marrow transplantation and implications for therapy

Mechanisms Of Complete Freund's Adjuvant Protection Against Diabetes in Bb Rats: Induction Of Non-Specific Suppressor Cells

We have previously reported that a single injection of complete Freund's adjuvant (CFA) can prevent diabetes appearance in diabetes-prone (DP) BB rats. In this study, we investigated further the mechanism of CFA-induced protection from diabetes. We found that adoptive transfer of splenic cells from CFA-treated DP rats into young DP rats protected the latter from diabetes development. This suggested that CFA-induced protection from diabetes resulted from activation of regulatory (suppressor) cells. Cell mixing experiments in vitro indicated that CFA activated splenic cells with antigen-nonspecific suppressor activity (suppression of lymphoproliferative responses to lipopolysaccharide and to allogeneic splenic cells). Fractionation of splenic cells on Percoll revealed that the suppressor activity resided in low density cells relatively depleted of T-cells, B-cells, macrophages and NK cells. These results suggest that non-specific (natural) suppressor cells in CFA-treated BB rats may be responsible for suppressing autoimmune responses and preventing insulitis and diabetes development.

The NOD mouse: a model for insulin-dependent diabetes mellitus

Nonobese diabetic (NOD) mice spontaneously develop autoimmune T cell-mediated insulin-dependent diabetes mellitus (IDDM). This unit presents a protocol for maintaining NOD mice under conditions permissive to full expression of their autoimmune potential. Methods are also described for diagnosing IDDM on the basis of glycosuria and glycosemia as well as for the semiquantitation of insulitis, a valuable subphenotype diagnostic of prediabetes in these mice, including a procedure for aldehyde fuchsin staining to identify beta granules in beta islet cells for diagnostic purposes. An adoptive-transfer method is also included in which leukocytes, purified T cells, or T cell infiltrates obtained from the insulitic pancreas tissue of NOD mice are injected into prediabetic NOD or diabetes-resistant F1 mice, which then develop disease in an accelerated fashion. This protocol also includes alternative steps in which bone-marrow cells from NOD mice are transferred to syngeneic, irradiated NOD mice, allowing for reconstitution with a diabetogenic immune system. Steps for isolating pancreatic islet cells, which can then be used for a variety of purposes (e.g., as a source of islet antigens to establish and maintain autoreactive T cell lines) are included. Finally, steps are outlined that can be used to introduce transgenes into NOD mice. This protocol also discusses important considerations for introduction of targeted mutations produced in embryonic stem cells derived from other inbred strains, or introduction of other genes from non-diabetes-prone strains.

Prevention of diabetes in nonobese diabetic mice by nonmyeloablative allogeneic bone marrow transplantation

OBJECTIVE

Autoimmune diabetes in nonobese diabetic (NOD) mice can be prevented by allogeneic bone marrow transplantation (BMT) from diabetes-resistant murine strains. Donor-specific tolerance can also be induced by BMT; however, clinical application of nonmyeloablative conditioning prior to BMT may be essential for reducing transplant-related toxicity and mortality. In this study, we have attempted to treat autoimmunity using a new nonmyeloablative regimen for BMT.

MATERIALS AND METHODS

Naïve NOD were irradiated with 650 cGy and injected intravenously (i.v.) with splenocytes from overtly diabetic NOD mice for induction of diabetes mellitus. Three days later, experimental mice received allogeneic C57BL/6 or (C57BL/6 x BALB/c) F1 bone marrow (BM) cells i.v. for intentional activation of donor-reactive cells, and 24 hours later intraperitoneal injection of cyclophosphamide (CY) for selective depletion of alloreactive cells. In order to induce chimerism, recipients were given a second IV inoculum of donor BM 1 day after CY.

RESULTS

Our method of nonmyeloablative BMT converted recipients to full or to mixed chimeras and prevented development of diabetes. Although NOD mice treated with 200 mg/kg CY died of graft-vs-host disease (GVHD), we observed diabetes-free survival for >300 days in 90% of C57BL/6 --> NOD BM chimeras treated with 60 mg/kg CY.

CONCLUSION

Our data show that allogeneic BMT after reduced-intensity conditioning based on deletion of activated donor-reactive host cells by means low-dose CY results in prevention of autoimmune diabetes by converting recipients to stable, GVHD-free BM chimeras.

NOD congenic mice genetically protected from autoimmune diabetes remain resistant to transplantation tolerance induction

The loss of self-tolerance leading to autoimmune type 1 diabetes in the NOD mouse model involves at least 19 genetic loci. In addition to their genetic defects in self-tolerance, NOD mice resist peripheral transplantation tolerance induced by costimulation blockade using donor-specific transfusion and anti-CD154 antibody. Hypothesizing that these two abnormalities might be related, we investigated whether they could be uncoupled through a genetic approach. Diabetes-resistant NOD and C57BL/6 stocks congenic for various reciprocally introduced Idd loci were assessed for their ability to be tolerized. Surprisingly, in NOD congenic mice that are almost completely protected from diabetes, costimulation blockade failed to prolong skin allograft survival. In reciprocal C57BL/6 congenic mice with NOD-derived Idd loci, skin allograft survival was readily prolonged by costimulation blockade. These data indicate that single or multiple combinations of evaluated Idd loci that dramatically reduce diabetes frequency do not correct resistance to peripheral transplantation tolerance induced by costimulation blockade. We suggest that mechanisms controlling autoimmunity and transplantation tolerance in NOD mice are not completely overlapping and are potentially distinct, or that the genetic threshold for normalizing the transplantation tolerance defect is higher than that for preventing autoimmune diabetes.

Multidose streptozotocin induction of diabetes in BALB/cBy mice induces a T cell proliferation defect in thymocytes which is reversible by interleukin-4

Thymic T cell function in streptozotocin-treated (STZ) diabetic mice has been examined. STZ administration suppresses thymic T cell proliferation in response to mitogen stimulation in vitro. Secretion of IL-4 was dramatically reduced; however, secretion of IL-2 or IFN-gamma was not significantly inhibited. RT-PCR analysis of thymocyte RNA revealed that levels of IL-4 mRNA were dramatically decreased in STZ-treated mice. Levels of mRNA encoding IFN-gamma were similar, but the appearance was delayed in thymocytes derived from STZ-treated mice, implying differential regulation of IL-4 and IFN-gamma. Defective thymocyte proliferation was partially restored by exposure to IL-2 in vitro; however, IL-4 completely reversed the STZ-induced defect. Administration in vivo of IL-4 before STZ treatment reversed the STZ-induced thymocyte proliferation defect and prevented both pancreatic islet destruction and hyperglycemia. Thymocyte cell surface differentiation markers were not appreciably different from control mice. Collectively these experiments suggest that STZ treatment of mice reduces expression of IL-4 which is associated with development of autoimmune diabetes.

Autoimmunity and type I diabetes

Insulin-dependent diabetes mellitus (IDDM) is a T-cell-mediated autoimmune disease. The effector mechanisms essentially involve cytokine-mediated inflammation ultimately leading to beta-cell destruction. Several candidate autoantigens have been delineated for both the pathogenic T-cell response and the nonpathogenic antibody response used for disease prediction. Because of antigen spreading, it is not yet clear which of these antigens are involved in the triggering of the autoimmune response. In any case, this TH1 autoimmune response is amplified and perpetuated by an immune dysregulation involving TH2 cells. Both effector and regulatory mechanisms are placed under the tight control of major histocompatibility complex (MHC) and non-MHC genes. (Trends Endocrinol Metab 1997; 8:71-74). (c) 1997, Elsevier Science Inc.

The harderian gland in autoimmune diabetes of the nonobese diabetic mouse

Infiltration of the nonobese diabetic (NOD) mouse's Harderian gland (HG) was studied in 1-30-week-old animals. A mononuclear cell invasion of this gland is first seen in 8-week-old female mice (i.e., at a slightly later age than that for the onset of infiltration of pancreatic islets). Infiltrating elements are mainly located at the hilus of the gland or at one or two foci (periacinar infiltration) within the parenchyma. In the latter case, a few elements infiltrate the fibrous connective tissue surrounding the acini (one or more) without damaging them. The most severe histopathological lesion was observed in 16-week-old animals; at this time infiltration ranges from a still focal lesion to complete acinar destruction of the gland. Ultrastructural observations confirm that in several cases acinar cells are destroyed and the HG parenchyma is substituted with infiltrating elements, fibroblasts, and connective tissue. HG infiltration is comparable to the pancreatic inflammatory infiltration; the two processes are very similar, though insulitis starts slightly earlier than HG infiltration. Furthermore, as for insulitis and diabetes incidence, HG infiltration affects NOD males less than females. Moreover, immunocytochemistry has shown that T lymphocytes are the prevalent infiltrating element both in pancreatic islets and HGs. Further studies are required to understand the reasons for autoimmune destruction of this gland.

Endogenous TNF production differs between high and low diabetes incidence non-obese diabetic (NOD) mice

Tumour necrosis factor (TNF) has been implicated in the pathogenesis of insulin-dependent diabetes mellitus (IDDM). To investigate a possible role for TNF in IDDM we compared endogenous TNF production in two lines of non-obese diabetic (NOD) mice, NOD/Lt and NOD/WEHI, that have a high and low incidence of diabetes, respectively. Preliminary experiments had shown that the lower syngeneic mixed lymphocyte reaction (SMLR) in NOD/Lt mice could be corrected by TNF-alpha. Plasma TNF-alpha was measured in 8 week-old female non-diabetic mice primed with 1000 units IV of murine interferon gamma (IFN-gamma) followed after 3 hours by 5 micrograms IV of lipopolysaccharide (LPS). Two hours later plasma was collected and TNF measured by ELISA. Plasma TNF in NOD/Lt mice was 9.2 +/- 2.4 ng/ml (mean +/- SEM, n = 16) compared to 2.5 +/- 0.5 ng/ml in NOD/WEHI mice (n = 15) and 7.6 +/- 1.0 ng/ml in BALB/c mice (n = 14). Time course studies demonstrated higher levels of both immunoreactive and bioactive TNF in NOD/Lt compared to NOD/WEHI mice up to 4 hours post-stimulation. A separate group of female NOD/Lt mice had IFN-gamma/LPS-stimulated plasma TNF-alpha measured at 10 weeks and were followed to age 30 weeks. The mean stimulated plasma TNF-alpha level was consistently higher in those mice that developed diabetes compared to those that remained non-diabetic, the difference being significant when mice were 21 weeks of age. These results suggest that endogenous TNF-alpha production may be a trait marker of IDDM susceptibility.

NOD mouse colonies around the world--recent facts and figures

Non-obese diabetic (NOD) mice are commonly used in autoimmune research. However, the diversity of these mice in developing autoimmune disease under different conditions prompted a group of researchers to compile a questionnaire on this subject. Here Paolo Pozzilli and colleagues comment on the results of this survey.

A multiplicity of protein antigens in subcellular fractions of rat insulinoma tissue are able to stimulate T cells obtained from non-obese diabetic mice

Type 1 (insulin-dependent) diabetes mellitus is a T-cell mediated autoimmune disease with a number of different proteins being implicated as target autoantigens. A 38 kDa protein residing in the insulin secretory granule of insulinoma tissue is recognized by T-cell clones from a newly-diagnosed Type 1 diabetic patient. We have investigated the capacity of normal rat pancreatic beta-cell extracts and various subcellular fractions of transplantable RIN tissue to induce proliferation of T cells from non-obese diabetic (NOD) mice and H-2 identical NON.NOD-H-2g7 control mice. Normal rat islet beta-cell protein fractions induced intense, dose-dependent proliferation of NOD splenic T cells, but only marginal proliferative responses of NON.NOD-H-2g7 splenic T cells. To further localize the target antigens, four different subcellular fractions from RIN tissue were used as a source of antigen; here in particular the cytosolic proteins showed dose-dependent activation capacity with splenic T cells in NOD animals. These activities were absent in control mice. There was no proliferation after incubation with microsome preparations from other rat endocrine tissues. Purified carboxypeptidase H did not have any stimulatory activity on NOD T cells. Fractionation of the RIN cytosolic proteins showed a large number of different fractions eliciting proliferative activity. These results demonstrate that NOD T cells respond to a large number of potential islet beta-cell target antigens and it will be necessary to utilize NOD T-cell clones to identify the number and nature of these antigens.

Immunotherapy at clinical diagnosis of insulin-dependent diabetes: an approach still worth considering

Immunointervention at the time of clinical diagnosis of insulin-dependent diabetes has been adopted in many centers throughout the world, with the aim of inducing and maintaining clinical remission (for example, reduction of insulin replacement therapy with normalization of metabolic parameters). Several approaches have been considered, ranging from the use of different kinds of immunosuppression to the use of free oxygen radical scavengers. Although the period of latency before the onset of overt hyperglycemia should be regarded as the most favorable time for any sort of immunointervention, adjuvant treatment at diagnosis (in addition to intensive insulin therapy) may offer clinical advantages in the long term. Thus, maintenance of some residual beta-cell function as a result o f such an approach may improve metabolic control and help to prevent the insurgence of late diabetic complications.

Tumor necrosis factor production is deficient in diabetes-prone BB rats and can be corrected by complete Freund's adjuvant: a possible immunoregulatory role of tumor necrosis factor in the prevention of diabetes

The Bio-Breeding (BB) rat develops spontaneous insulin-dependent diabetes mellitus (IDDM) and provides a useful animal model to study this human autoimmune disease. Treatment of BB rats with tumor necrosis factor (TNF) has been reported to prevent the development of IDDM. This suggests that deficient TNF production may be involved in the immunopathogenesis of autoimmune diabetes. In this study, we evaluated TNF production in diabetes-resistant (DR) BB rats, diabetes-prone (DP) BB rats, and DP BB rats protected from diabetes by the immunoadjuvant, complete Freund's adjuvant (CFA). TNF production in short-term cultures of peritoneal macrophages from DP rats was significantly less than that from control DR rats, both in the basal state and after stimulation with either interferon-gamma (IFN-gamma) or lipopolysaccharide (LPS) in vivo and in vitro. In contrast, TNF production by macrophages from CFA-injected DP rats (basal and IFN-gamma or LPS-stimulated) was equal to or greater than that by macrophages from DP rats and similar to TNF production by macrophages from CFA-injected DR rats. These results suggest that development of autoimmune diabetes in BB rats may be causally related to deficient macrophage production of TNF, and that upregulation of TNF production may protect against diabetes development.