Genetic control of diabetes and insulitis in the nonobese diabetic (NOD) mouse

Prevention of autoimmune insulitis in nonobese diabetic mice by expression of major histocompatibility complex class I Ld molecules

Nonobese diabetic (NOD) mice spontaneously develop a T-cell-mediated autoimmune disease that is similar in many respects to insulin-dependent diabetes mellitus in humans. NOD mice were shown to express major histocompatibility complex class I Kd and Db antigens. To examine the possible involvement of major histocompatibility complex class I molecules in the development of autoimmune insulitis, we attempted to express a different type of class I molecule in NOD mice by crossing C57BL/6 mice transgenic for the class I Ld gene with NOD mice. The backcross progeny expressed the Ld antigen on the peripheral blood lymphocytes at a level comparable with that of the BALB/c mice. The cell surface expression of endogenous class I and class II antigens on the peripheral blood lymphocytes was not affected. Analysis of these mice revealed that the expression of the class I Ld antigen significantly reduced the incidence of insulitis at 20 weeks of age. In situ hybridization of a biotinylated probe on mouse chromosomes showed that the Ld transgene was located in the E area of chromosome 6 with which no genetic linkage to insulin-dependent diabetes mellitus was demonstrated. These results suggest that the NOD-type class I molecules are involved in the development of insulitis in NOD mice.

Acquired allo-tolerance to major or minor histocompatibility antigens indifferently contributes to preventing diabetes development in non-obese diabetic (NOD) mice

Diabetes in NOD mice represents the end stage of a genetically-programmed autoimmune process mediated by T lymphocytes and directed against insulin-producing beta cells. We have shown in a previous study that the course of the disease is significantly inhibited in NOD mice which have been made tolerant at birth to foreign histocompatibility antigens. This early T cell manipulation results in a significant delay of disease onset, reduced overall incidence and less severe alterations of islet cells. In order to characterize better the nature of the foreign tolerogenic determinants responsible for this protection, we have now examined separately the contribution of MHC and non-MHC antigens. Two lines of congenic mice were used as donors of tolerogenic cells, NOD.H-2b, which differ from NOD by the MHC-encoded antigens only, and B10.H-2g7, which differ by all the minor histocompatibility antigens encoded by the B10 background, but which share with NOD mice the same MHC haplotype. Our results show that NOD recipients of F1 semi-compatible cells become specifically tolerant to the set of alloantigens to which they were neonatally exposed. Unresponsiveness, assessed by lack of CTL generation, is profound and specific. Yet, despite the fact that distinct sets of alloreactive T cell precursors are silenced, mice made tolerant indifferently to major or minor histocompatibility antigens are significantly protected against overt diabetes. These results could mean that each set of MHC and non-MHC encoded determinants can independently cross-tolerize a sufficient proportion of the autoreactive repertoire to slow the natural course of the disease. Alternatively, neonatally-acquired tolerance might induce polyclonal activation of the immune system resulting in the suppression or the immunodeviation of potentially harmful, autoreactive T cell clones.

Autoimmune syndromes in major histocompatibility complex (MHC) congenic strains of nonobese diabetic (NOD) mice. The NOD MHC is dominant for insulitis and cyclophosphamide-induced diabetes

The development of autoimmune diabetes in the nonobese diabetic (NOD) mouse is controlled by multiple genes. At least one diabetogenic gene is linked to the major histocompatibility complex (MHC) of the NOD and is most likely represented by the two genes encoding the alpha and beta chains of the unique NOD class II molecule. Three other diabetogenic loci have recently been identified in the NOD mouse and are located on chromosomes 1, 3, and 11. In addition to the autoimmune diabetes which is caused by destruction of the insulin-producing beta cells in the pancreas, other manifestations of autoimmunity are seen in the NOD mouse. These include mononuclear cell inflammation of the submandibular and lacrimal glands, as well as the presence of circulating autoantibodies. To determine the effect of the non-MHC diabetogenic genes on the development of autoimmunity, we constructed the NOD.B10-H-2b (NOD.H-2b) strain, which possesses the non-MHC diabetogenic genes from the NOD mouse, but derives its MHC from the C57BL/10 (B10) strain. The NOD.H-2b strain does not develop insulitis, cyclophosphamide-induced diabetes, or spontaneous diabetes. It does, however, develop extensive lymphocytic infiltrates in the pancreas and the submandibular glands that are primarily composed of Thy 1.2+ T cells and B220+ B cells. In addition, autoantibodies are present in NOD.H-2b mice which recognize the "polar antigen" on the insulin-secreting rat tumor line RINm38. These observations demonstrate that the non-MHC genes in the NOD strain, in the absence of the NOD MHC, significantly contribute to the development of autoimmunity. The contribution of a single dose of the NOD MHC to autoimmunity was assessed with a (NOD x NOD.H-2b)F1 cross. Although only approximately 3% of F1 females developed spontaneous diabetes, approximately 50% of both female and male F1 mice developed insulitis, and 25% of females and 17% of males became diabetic after treatment with cyclophosphamide. These data demonstrate that the MHC-linked diabetogenic genes of the NOD mouse are dominant with decreasing levels of penetrance for the following phenotypes: insulitis greater than cyclophosphamide-induced diabetes greater than spontaneous diabetes.

Analysis of the T cell receptor (TcR) regions in the NOD, NON and CTS mouse strains define new TcR V alpha haplotypes and new deletions in the TcR V beta region

We have analyzed the T cell receptor (TcR) V alpha and TcR V beta regions in the spontaneous mouse model for insulin-dependent diabetes mellitus, the NOD mouse, and compared it to the regions in the two sister strains, the NON and CTS strains. Based on restriction fragment length polymorphism analysis the TcR V alpha region in the NOD mouse is essentially identical to that of the SJL/J strain. In contrast both the NON and CTS strains have a unique TcR V alpha haplotype. Whereas the NOD and NON strains apparently contains all the TcR V beta genes, the CTS mouse has three deletions in the V beta region. Our analysis does not give any indications for the diabetic phenotype of the NOD mouse.

T cell receptor beta diversity and joining segments in the NOD mouse

Pancreatic beta-cell autoantigen recognition by the immune system appears to be a critical event in the evolution of insulin dependent diabetes. Immune recognition involves antigen presentation by macrophages and subsequent antigen-peptide-class II MHC recognition by T cell receptors (TCR). Using the NOD mouse as a model for human IDD, we hypothesized that germline variability in the D beta nod and/or J beta nod segments could contribute to beta cell autoimmunity by influencing the specific peptides that are recognized. As an initial approach to our hypothesis, we sought to compare these segments to other strains of mice in search of genetic polymorphisms as reported in NZW mice. The germ line TCR beta nod gene did not display evidence of an expansion or contraction in the number of D beta nod or J beta nod segments at the level of resolution provided by restriction fragment length polymorphism analysis. The absence of such polymorphisms suggests that D beta nod or J beta nod segments are not different from nonautoimmune strains of mice.

Peripherin: an islet antigen that is cross-reactive with nonobese diabetic mouse class II gene products

The nonobese diabetic (NOD) mouse, in which major histocompatibility complex genes may be involved in the susceptibility to diabetes, has been developed as a model of autoimmune diabetes. The NOD mouse expresses I-A-encoded class II major histocompatibility complex antigens, which differ from those of other mouse haplotypes by the presence of a serine at position 57 of the A beta chain. Identifying islet autoantigens may help elucidate the role of class II antigens in the activation of autoreactive T cells and, thus, in the development of diabetes. We have detected autoantibodies directed against a 58-kDa islet cell antigen in NOD mice but not in other strains, including lupus-prone mice. Apart from insulin-secreting cells, the 58-kDa antigen was only found to be expressed by neuroblastoma cells and was identified as peripherin, an intermediate filament protein previously characterized in well-defined neuronal populations. This autoantigen cross-reacted with I-Anod class II antigens, suggesting that it may contribute to defective self-tolerance of islet beta cells in the NOD mouse.

Insulin-dependent diabetes mellitus

Type I diabetes occurs as a result of T-cell-mediated beta-cell destruction. Several candidate antigens have been described recently, including glutamic acid decarboxylase, heat shock protein 65 and peripherin. Restricted T-cell receptor V beta gene usage in non-obese diabetic mice has been suggested but not yet proven. In addition to major histocompatibility genes, several non-H-2 predisposing genes have been mapped on chromosomes 1, 3 and 11.

The phenotype of lymphoid cells and thymic epithelium correlates with development of autoimmune insulitis in NOD in equilibrium with C57BL/6 allophenic chimeras

The mechanisms contributing to the development of autoimmune insulin-dependent diabetes mellitus have been analyzed in allophenic mouse chimeras of the NOD in equilibrium with C57BL/6 strain combination (where NOD is nonobese diabetic). Occurrence of lymphoid cell infiltration (insulitis) in pancreatic islets was observed in the majority of such chimeras. The development of insulitis was found to correlate with major histocompatibility complex chimerism in lymphoid cells and in thymus cortical regions. Chimeras with more than 50% of C57BL/6 lymphoid cells rarely developed insulitis. Our data suggest that the correlation with the thymic cortical region is absolute. Thus, all individuals displaying NOD or NOD/C57BL/6 thymic cortical regions developed insulitis, whereas we have not observed insulitis in chimeras with only C57BL/6 thymic cortical regions. Thus the positive selection of T cells appears to play a crucial role in the development of insulin-dependent diabetes mellitus.

Monoclonal, natural antibodies prevent development of diabetes in the non-obese diabetic (NOD) mouse

The development of diabetes in the non-obese diabetic (NOD) mouse is mediated by T cells of both the CD4+CD8- and CD4-CD8+ phenotypes, while B cells are not involved in the effector stage of the disease. We have recently found, however, that treatments with heterologous, polyclonal immunoglobulin (Ig) preparations, as well as suppressing the developing B cell repertoire for the first 4 weeks of life dramatically reduce the incidence of disease and the severity of insulitis, in treated mice. We have further investigated the influence of Igs on the development of autoimmunity by testing the effect of polyclonal mouse-Ig or monoclonal, natural antibodies derived from normal, neonatal BALB/c mice. We found that repeated administration of high doses of polyclonal Ig (of xenogenic or isogenic origin), given at birth, inhibits the development of insulitis, as well as diabetes. Furthermore, single injections of moderate doses of isogenic, natural monoclonal antibodies (mAb) administered at the same age, while failing to significantly alter the degree of insulitis, efficiently prevent the development of disease. The effect of mAbs was found to be related to V-region specificity, as only some mAbs of a given isotype and origin had the observed effect.

Identification and mapping to chromosome 1 of a susceptibility locus for periinsulitis in non-obese diabetic mice

Insulin-dependent diabetes mellitus (IDDM) is a polygenic disease caused by autoimmune destruction of insulin-producing beta cells in the islets of Langerhans. Its onset is preceded by a long and variable period in which lymphoid cells infiltrate the pancreas but first remain outside the islets (peri-insulitis) before invading them (insulitis). Among susceptibility loci, only the major histocompatibility complex (MHC) has been clearly assigned. Genetic study of the nonobese diabetic (NOD) mouse model for insulin-dependent diabetes mellitus has revealed genetic linkage of insulitis and of early onset diabetes with two non-MHC loci mapping to chromosome 3 and 11 respectively. Here we report a close association of periinsulitis with a third non-MHC locus mapping to chromosome 1. Successive stages in the progression of diabetic disease thus appear to be controlled by distinct genes or sets of genes.

Type 1 diabetes in mice is linked to the interleukin-1 receptor and Lsh/Ity/Bcg genes on chromosome 1

Human type 1 (insulin-dependent) diabetes is a common auto-immune disease of the insulin-producing beta cells of the pancreas which is caused by both genetic and environmental factors. Several features of the genetics and immunopathology of diabetes in nonobese diabetic (NOD) mice are shared with the human disease. Of the three diabetes-susceptibility genes, Idd-1 -3 and -4 that have been mapped in mice to date, only in the case of Idd-1 is there any evidence for the identity of the gene product: allelic variation within the murine immune response I-A beta gene and its human homologue HLA-DQB1 correlates with susceptibility, implying that I-A beta is a component of Idd-1. We report here the mapping of Idd-5 to the proximal region of mouse chromosome 1. This region contains at least two candidate susceptibility genes, the interleukin-1 receptor gene and Lsh/Ity/Bcg, which encodes resistance to bacterial and parasitic infections and affects the function of macrophages.

The contribution of non-MHC genes to susceptibility to autoimmune diseases

Genetic studies of experimental models of autoimmune diseases, including systemic lupus-like syndromes and organ-specific autoimmunity, provide major information on genetic control of autoimmune diseases. In addition to genes known to be linked to the major histocompatibility complex (MHC), these studies point to multiple genes located outside the MHC that influence the onset and the progression of autoimmune diseases. Identification of these genes and of their interrelationships is now a major task that will be facilitated by recent progress in molecular biology and gene mapping. Among candidate genes, antigen-receptor genes (i.e., immunoglobulin- and T-cell receptor genes) most likely contribute an important part of the autoimmune susceptibility in several of these animal models. Available linkage data suggest a similar involvement of these antigen-receptor genes in several human autoimmune diseases. In addition to a better understanding of pathogenic mechanisms associated with autoimmunity, the knowledge of these disease-predisposing genes is expected to permit a better classification of often complex syndromes as well as the design of new treatments.

Genetic dissection of T cell receptor V beta gene requirements for spontaneous murine diabetes

It has been demonstrated, in certain autoimmune disease models, that pathogenic T cells express antigen receptors of limited diversity. It has been suggested that the T cells responsible for the pathogenesis of type I diabetes mellitus might similarly demonstrate restricted T cell receptor (TCR) usage. Recently, attempts have been made to identify the V beta subset(s) that initiates and/or perpetuates the antiislet response in a mouse model of spontaneous autoimmune diabetes (non-obese diabetic [NOD] mice). In studies reported here, we have bred NOD mice to a mouse strain that congenitally lacks approximately one-half of the conventional TCR V beta alleles. Included in this deletion are TCR V beta gene products previously implicated as being involved in the pathogenesis of NOD disease. By studying second backcross-intercross animals, we were able to demonstrate that this deletion of TCR V beta gene segments did not prevent the development of insulitis or diabetes.

Genetic analysis of autoimmune type 1 diabetes mellitus in mice

Two genes, Idd-3 and Idd-4, that influence the onset of autoimmune type 1 diabetes in the nonobese diabetic mouse have been located on chromosomes 3 and 11, outside the chromosome 17 major histocompatibility complex. A genetic map of the mouse genome, analysed using the polymerase chain reaction, has been assembled specifically for the study. On the basis of comparative maps of the mouse and human genomes, the homologue of Idd-3 may reside on human chromosomes 1 or 4 and Idd-4 on chromosome 17.

Genetic analysis of susceptibility to diabetes mellitus in F2-hybrids between diabetes-prone BB and various MHC-recombinant congenic rat strains

The occurrence of diabetes mellitus was analysed in F2 hybrids bred from diabetic BB male rats and females of congenic rat strains carrying different major histocompatibility (RT1) haplotypes on the common LEW strain genetic background. Permissiveness for the disease in BB rats is probably determined by class II genes of the RT1 complex, which are also present in normal rats. Class I and class III genes, notably the Hsp70 genes in the class III region, do not appear to be involved. Among the diabetic F2 hybrids, about 90% are shown by DNA analysis to be homozygous for the class II genes of the permissive RT1 haplotype. The segregation patterns are in accord with the action of two independent recessive genes, one of them being RT1-linked.

Prevention of diabetes in NOD mice treated with antibody to murine IFN gamma

The NOD mouse is studied as an animal model of human insulin-dependent diabetes mellitus (IDDM). To evaluate the role of IFN gamma in the pathogenesis of the disease, we have studied the effect of anti-IFN gamma mAb on the expression of insulitis and clinical diabetes. Treatment of mice with anti-IFN gamma mAb prevented the induction of early IDDM by cyclophosphamide as well as the adoptive transfer of diabetes by spleen cells from diabetic NOD mice. The protection against induction of diabetes by cyclophosphamide was observed in animals treated with the anti-IFN gamma mAb within 24 h following the first cyclophosphamide injection but not in animals in which mAb treatment was started 7 days later. Transfer of disease was prevented both in adult irradiated and in newborn recipients. The absence of clinical signs in these mice was corroborated by a significant reduction of both the extent and severity of insulitis. Over-expression of Ia antigen on endothelial cells lining the islets was also considerably reduced in mice treated with mAb. These data strongly suggest a role for IFN gamma during the autoimmune process leading to beta cell destruction in diabetes and prompt further investigation of the use of such antibodies in the immunoprevention of IDDM.

High-resolution linkage mapping for susceptibility genes in human polygenic disease: insulin-dependent diabetes mellitus and chromosome 11q

Insulin-dependent diabetes mellitus (IDDM) has a complex pattern of genetic inheritance. In addition to genes mapping to the major histocompatibility complex (MHC), several lines of evidence point to the existence of other genetic susceptibility factors. Recent studies of the nonobese diabetic mouse (NOD) model of IDDM have suggested the presence, on mouse chromosome 9, of a susceptibility gene linked to the locus encoding the T-cell antigen, Thy-1. A region on human chromosome 11q is syntenic to this region on mouse chromosome 9. We have used a set of polymorphic DNA markers from chromosome 11q to investigate this region for linkage to a susceptibility gene in 81 multiplex diabetic pedigrees. The data were investigated by maximization of lod scores over genetic models and by multiple-locus affected-sib-pair analysis. We were able to exclude the presence of a susceptibility gene (location scores less than -2) throughout greater than 90% of the chromosome 11q homology region, under the assumption that the susceptibility factor would cause greater than 50% of affected sib pairs to share two alleles identical by descent. Theoretical estimates of the power to map susceptibility genes with a high-resolution map of linked markers in a candidate region were made, using HLA as a model locus. This result illustrates the feasibility that IDDM linkage studies using mapped sets of polymorphic DNA markers have, both for other areas of the genome in IDDM and for other polygenic diseases. The analytic approaches introduced here will be useful for affected-sib-pair studies of other complex phenotypes.

Persistent MHV (mouse hepatitis virus) infection reduces the incidence of diabetes mellitus in non-obese diabetic mice

The frequency of diabetes mellitus was compared in non-obese diabetic mice before and after inadvertent exposure of the colony to mouse hepatitis virus infection. Prior to exposure, diabetes prevalence and cumulative diabetes incidence in 7-month-old mice was 65% and 25% in females and males, respectively. Diabetes incidence/quarter revealed a seasonal pattern with peaks in winter. After mouse hepatitis exposure, the diabetes incidence in the colony decreased and testing for mouse hepatitis antibody in blood samples revealed a persistent infection. In the offspring of mice delivered by caesarean section, the diabetic incidence increased sharply from a nadir of 36% to 95% and from 9% to 65% in females and males, respectively. In individual mice, diabetes resistance was strongly correlated to high titres of mouse hepatitis virus antibody. The results of this inadvertent viral infection demonstrate that a diabetes-susceptible genotype is strongly modulated by environmental factors. Investigators studying this diabetes model should strive for specific pathogen-free colony status and a high incidence of diabetes before attempting to investigate therapeutic modalities.

Human variable number of tandem repeat probes as a source of polymorphic markers in experimental animals

Human VNTR (Variable Number of Tandem Repeat) markers are examined as a source of polymorphism for linkage studies in inbred strains of mice and rats. High frequencies of cross-hybridization are found under fingerprinting conditions that detect many distinct minisatellite loci in these species. Linkage studies suggest that minisatellite markers are widely distributed in the mouse genome, in contrast to humans where they are clustered, particularly in telomeric regions. Human VNTR probes can be used to screen in mouse genomic libraries to isolate mouse specific VNTR sequences. Some of these sequences reveal fingerprint patterns under stringent hybridization conditions.

Susceptibility to type I diabetes in women is associated with the CD3 epsilon locus on chromosome 11

Type I diabetes is associated with the DQ loci of the MHC and to a lesser extent with the T cell antigen receptor (TcR) beta chain genes. The non-obese diabetic (NOD) mouse is an animal model of human diabetes, in which up to 90% of female mice develop overt insulin-dependent diabetes. Genetic studies in the NOD mouse suggest that there are at least three diabetogenic genes; one that maps to the MHC, another that may map to the mouse Thy-I locus, and a third that has still to be identified. We have investigated loci in the vicinity of the human Thy-I locus on chromosome 11q23 and report here the results of restriction fragment length polymorphism (RFLP) analysis of the CD3 epsilon locus of 168 Caucasoid patients with type I diabetes. While no association was found between this locus and type I diabetes, a significant difference in the frequency of the CD3 epsilon 8-kb allele was found between male and female patients (0.268 versus 0.430; P less than 0.0025, Pc = 0.02) and between female patients and healthy female controls (0.430 versus 0.267; P less than 0.015). These results suggest that a gene residing on chromosome 11q23 may confer susceptibility to type I diabetes in women.

Pertussigen treatment retards, but fails to prevent, the development of type I, insulin-dependent diabetes mellitus (IDDM) in NOD mice

Current evidence supports an autoimmune etiopathogenesis for Type I, insulin-dependent diabetes mellitus (IDDM) in which the pancreatic beta (beta) cell is the specific target tissue. Recently, the NOD (non-obese diabetic) mouse has become an important model for IDDM, exhibiting many of the pathological features observed in man, including a progressive pancreatic islet leukocytic inflammation referred to as insulitis. The present study was carried out to determine the efficacy of the bacterial-derived bio-product, pertussigen, to retard the progression of insulitis and thereby prevent overt diabetes. Results revealed that (1) the rapid onset of IDDM in female NOD mice is absent if the mothers are treated with pertussigen prior to mating, (2) treatment of young prediabetic NOD mice with repeated injections of pertussigen results in the retardation of onset of IDDM when compared to untreated control NOD mice, and (3) the severity of insulitis in pertussigen-treated NOD mice not developing IDDM was noticeably less severe than age and sex-matched untreated control mice. Since earlier work had shown that pertussis vaccine, which contains pertussigen, could prevent development of IDDM in mice treated with streptozotocin, the present results may indicate basic differences in the inflammatory responses in the genetically-predisposed NOD mice and IDDM-nonsusceptible mice with streptozotocin-induced diabetes.

Transgenic models of T-cell self tolerance and autoimmunity

Self-tolerance is generally induced by intrathymic clonal deletion of T cells with reactivity directed to antigens synthesized within the thymus (Kappler et al. 1987, Kisielow et al. 1988). It may also be induced in peripheral T cells when these encounter antigens unique to extra-thymic tissues. Two transgenic models have been particularly useful in the study of peripheral self tolerance: in one model, a known antigen is expressed in a particular extra-thymic site; in the other, the T-cell repertoire is predominantly reactive to this antigen. We, and others, have shown that expression of class I or II MHC molecules in defined extra-thymic sites leads to a state of T-cell tolerance. To account for this, we have proposed two hypotheses which have different implications for autoimmune disease. According to one, tolerance is imposed by deletion or functional silencing of specific high-affinity cytolytic T cells; alternatively, the target cell for tolerance induction may be a regulatory IL-2-producing T-cell, rather than the effector cell itself. To distinguish between these hypotheses it is essential to examine the fate of T cells which have the potential to react to the transgene product. Since the frequency of such T cells is low and there is no dominant clonotype for H-2Kb, which is the class I molecule we used, it was necessary to create double transgenic mice by mating class I transgenic mice with transgenic mice whose T-cell pool was compared of cells reactive to H-2Kb and could be detected by an antibody directed to the TCR. Initial studies showed that such T cells did persist despite the presence of antigen to which they may be reactive. If these double transgenic mice can be shown to be tolerant, they will offer a rich source of tolerant T cells for detailed investigation of their phenotype and fate, and they will be most useful in enabling us to probe the mechanisms responsible for the induction of peripheral self tolerance. Transgenic mouse technology has also been used successfully to unravel the genetic influences which may lead to or prevent autoimmunity. In particular, we have prevented autoimmune diabetes in the nonobese diabetic mouse by introducing a non-NOD MHC class II gene and further work is implicating the failure of intrathymic positive selection of a protective cell as one step in the pathogenesis of diabetes in NOD mice.

Detection of DNA polymorphisms between two inbred mouse strains--limitations of restriction fragment length polymorphisms (RFLPs)

Type I (insulin-dependent) diabetes in humans is characterized by a T cell mediated destruction of insulin-secreting pancreatic beta cells. This autoimmune response is very similar to that seen in the non-obese diabetic (NOD) mouse strain. Originally bred from the ICR cataract-prone strain, NOD mice spontaneously develop T cell mediated insulitis and type I diabetes by the age of 6 months. Backcross studies with the NOD mouse strain indicate segregation of at least three recessive genes. One of these, Iddm-1, has been shown to be tightly linked to the mouse MHC, H-2 on chromosome 17. Comparative studies with diabetic patients has also shown linkage to human HLA with protective and predisposing haplotypes being present within the population. In this study we have attempted to identify restriction fragment length polymorphisms (RFLPs) between the genomes of the NOD mouse strain and the diabetes-resistant strain C57BL/10. Such polymorphic loci will be used to screen DNAs from backcross animals that are diagnosed diabetic in an attempt to identify probes linked to the non-H2 disease susceptibility genes.

Role of the first external domain of I-A beta chain in immune responses and diabetes in non-obese diabetic (NOD) mice

Diabetes in the non-obese diabetic (NOD) mouse is a multigenic autoimmune disease and is possibly controlled by three recessive loci, including one that is linked to the major histocompatibility complex (MHC). The first external domain of the Class II MHC I-A beta chain in these mice is unique and has been suggested as being responsible for autoimmunity. The I-A alpha chain in these mice is I-A alpha d, and they lack the expression of I-E molecules. We have investigated immune responses to various Ir gene control antigens in NOD mice to determine the influence of the NOD Ia and particularly the I-A beta chain. We find that sheep insulin is highly immunogenic while other insulins are weakly immunogenic in these mice. Hen egg lysozyme, pigeon cytochrome C and the synthetic polypeptide Poly 18, Poly EYK(EYA)5 antigen produce good antibody responses. Apart from H-2d, NOD are the only mice where Poly 18 antigen is immunogenic. In these mice Poly 18 induced good T-cell proliferative response, which was inhibited by anti-Ia antibody, and the mice were able to respond to tyrosine-containing polypeptide Poly EYA but not to the phenylalanine-containing antigen Poly EFA. We also found that synthetic peptide 48-60 of the NOD I-A beta chain is highly immunogenic in syngeneic NOD mice both for T cells and B cells. Using an I-A beta chain-specific monoclonal antibody, we are able to prevent induction of diabetes when the antibody was administrated in prediabetic, young mice. Our results suggest that the immune response to various antigens and autoimmune diabetes in NOD mice is directly influenced by the I-A beta chain.

Prevention of insulin-dependent diabetes mellitus in non-obese diabetic mice by transgenes encoding modified I-A beta-chain or normal I-E alpha-chain

Insulin-dependent diabetes mellitus (IDDM) is a disease with an autoimmune aetiology. The inbred non-obese diabetic (NOD) mouse strain provides a good animal model of the human disease and genetic analysis suggests that, as in man, at least one of the several genes controlling the development of IDDM is linked to the major histocompatibility complex. The NOD mouse does not express I-E owing to a deletion in the promoter region of the I-E alpha-chain gene, and the sequence of NOD I-A beta-chain in the first external domain is unique with His 56 and Ser 57 replacing Pro and Asp, respectively, at these positions. There has been considerable interest in the role amino acid 57 might have in conferring susceptibility to autoimmune diseases, including IDDM. The presence of a charged residue (such as Asp) at this position might affect the conformation of the peptide binding groove. But it could be assumed that Pro 56 gives rise to a different conformation of I-A beta-chain than does His 56. We therefore constructed transgenic NOD mice in which the transgene encoded a modified A beta nod with Pro 56, and studied its effect on the development of IDDM in this mouse strain. Previous studies have suggested that NOD mice expressing I-E as a result of the introduction of an I-E alpha-chain (E alpha) transgene are protected from the development of insulitis and hence IDDM. To explore further the protective effect of this molecule we constructed a second class of transgenic NOD mouse carrying an E alpha d transgene. Both transgenes protected the mice from IDDM, but this was not associated with a complete deletion of any T cells expressing commonly used T-cell receptor V beta genes.

Prevention of diabetes in non-obese diabetic I-Ak transgenic mice

The non-obese diabetic (NOD) mouse develops insulin-dependent diabetes mellitus (IDDM) with mononuclear cell infiltration of the islets of Langerhans and selective destruction of the insulin-producing beta-cells, as in humans. Most infiltrating cells are T lymphocytes, and most of these carry the CD4 antigen. Adoptive transfer of T cells from diabetic NOD mice into irradiated NOD or athymic nude NOD mice induces diabetes. Susceptibility to IDDM in NOD mice is polygenic, with one gene linked to the major histocompatibility complex class II locus, which in NOD mice expresses a unique I-A molecule but no I-E. Speculation exists as to the role of the I-A molecule in the diabetes susceptibility of NOD mice, especially regarding the significance of specific unique residues. To examine the role of the NOD I-A molecule in IDDM pathogenesis, we made NOD/Lt mice transgenic for I-Ak by microinjecting I-Ak alpha- and beta-genes into fertilized NOD/Lt eggs. Insulitis was markedly reduced and diabetes prevented in NOD/Lt mice expressing I-Ak.

Reversal of beta-cell suppression in vitro in pancreatic islets isolated from nonobese diabetic mice during the phase preceding insulin-dependent diabetes mellitus

Insulin-dependent diabetes mellitus (IDDM) is characterized by a progressive autoimmune destruction of the pancreatic beta-cells. One of the best-suited animal models for IDDM is the nonobese diabetic (NOD) mouse. In this investigation pancreatic islets were isolated from female NOD mice aged 5-7, 8-11, and 12-13 wk and examined immediately (day 0) or after 7 d of culture (day 7). The mice showed a progressive disturbance in glucose tolerance with age, and a correspondingly increased frequency of pancreatic insulitis. Islets isolated from the oldest mice often contained inflammatory cells on day 0, which resulted in an elevated islet DNA content. During culture these islets became depleted of infiltrating cells and the DNA content of the islets decreased on day 7. Islets of the eldest mice failed to respond with insulin secretion to high glucose, whereas a response was observed in the other groups. After culture all groups of islets showed a markedly improved insulin secretion. Islets from the 12-13-wk-old mice displayed a lower glucose oxidation rate at 16.7 mM glucose on day 0 compared with day 7. Islet (pro)insulin and total protein biosynthesis was essentially unaffected. In conclusion, islets obtained from 12-13-wk-old NOD mice exhibit an impaired glucose metabolism, which may explain the suppressed insulin secretion observed immediately after isolation. This inhibition of beta-cell function can be reversed in vitro. Thus, there may be a stage during development of IDDM when beta-cell destruction can be counteracted and beta-cell function restored, provided the immune aggression is arrested.

Restriction fragment length polymorphisms in the major histocompatibility complex of the non-obese diabetic mouse

The inbred non-obese diabetic (NOD) mouse is a spontaneous model for insulin-dependent diabetes mellitus (IDDM). As in man and BB rats, IDDM in the NOD mouse has an autoimmune aetiology. The disease is controlled by several genes, one of which, Idd-1, has been mapped to the major histocompatibility complex (MHC) on chromosome 17. However, Idd-1 has not yet been identified. To facilitate the identification of Idd-1 we have further analysed the MHC region for restriction fragment length polymorphisms and we find that the NOD mouse has a distinct haplotype: H-2K1nod Kd A beta nod A alpha d E beta nod TNF-alpha beta. In addition, the NOD mouse shows some similarities with the H-2b haplotype in the Q region, in that either the Q7 or the Q9 gene seems to be like that in the b-haplotype and that the Qa2 antigen is expressed, while other parts of this region are distinct from the b- as well as the d- haplotype. In contrast, the sister strain, the non-obese normal (NON) mouse, derived from the same cataract-prone line of mice as the NOD mouse, has an MHC Class I region indistinguishable from the b-haplotype, but the MHC Class II region is distinct from the NOD mouse as well as the b-, d- and k-haplotype.

Paradoxical lessening of autoimmune processes in non-obese diabetic mice after infection with the diabetogenic variant of encephalomyocarditis virus

In order to gain insight into the interaction between autoimmunity and viral infection in the onset of insulin-dependent diabetes, non-obese diabetic (NOD) mice which spontaneously develop autoimmune diabetes were inoculated with the diabetogenic variant of the encephalomyocarditis virus (EMCV-D) before the onset of the disease. The pre-diabetic period was divided into two phases: the early phase (days 88 to 116) during which development of spontaneous diabetes is rare and the late phase (day 123 to 200) during which the incidence of spontaneous diabetes is high. As controls ICR mice of common ancestry were also inoculated. During the early phase diabetes was observed in 4/10 inoculated, 0/13 control NOD and 7/13 inoculated ICR males vs. 6/12 inoculated, 1/11 control NOD and 0/15 inoculated ICR females. However, in NOD female, virus-induced diabetes prevalence was variable from one experiment to another. In parallel the flow cytometric analysis showed a high percentage of L3T4+ T lymphocytes in the pancreas of inoculated female NOD mice 10 days after the infection. At this time a large proportion of both L3T4+ and Ly-2+ cells expressed the interleukin 2 receptor. During the late phase no new case of diabetes occurred in inoculated NOD mice but one case was observed in control NOD males and five in control NOD females. This prevention of autoimmune diabetes was constantly found in other experiments. Insulitis was milder in inoculated NOD mice of both sexes than in control NOD. Adoptive transfer of diabetes into irradiated 8-week-old males by splenocytes from 28-week-old females was successful in five out seven attempts with control splenocytes and in zero out of six attempts with splenocytes from inoculated mice. This immunosuppression was specific as the ability of lymphocytes to respond to soluble or allogeneic antigens was preserved. In the early phase EMCV-D precipitated the onset of diabetes in females NOD mice by amplifying L3T4+ T lymphocyte-mediated immune mechanisms. During the late phase viral infection had lessened immune processes in animals which had resisted or recovered from virus-induced diabetes.

Immune deficiency of the CTS mouse. I. Deficiency of in vitro T cell-mediated immune response

The cataract Shionogi (CTS) mouse characterized by cataracts and microphthalmia is a sister strain of the NOD mouse. We have made the immunological characterization of the CTS mouse by means of in vitro assays. Splenocytes of the CTS mouse were very low in the responsiveness to T cell mitogens such as Con A and PHA but not to a B cell mitogen, LPS. The production of IL 2 and expression of IL 2-receptor of spleen cells after in vitro stimulation with Con A decreased in the CTS mouse, when compared with those in the NOD and the other reference strains. In mixed lymphocyte culture, CTS splenocytes did not proliferate and did not generate cytotoxic T lymphocytes when cocultured with splenocytes of the C3H/He mouse. The NK activity against YAC-1 target cells was lower in the CTS mouse than in the C3H/He mouse, an NK high responder, but higher than in the NOD mouse, a low responder. These results suggest that the CTS mouse is deficient in T cells. Subset analysis of splenic lymphocytes of the CTS mouse using flow cytometry revealed that the percentage of T cells in the CTS mouse was significantly lower than those in the reference strains, which was consistent with the reduced responsiveness to T cell mitogens in the CTS mouse. The deficiency in the Ly-2+ T cell subset was particularly striking. However, the response to PHA of the splenocytes of the CTS mouse was normalized when T cells were enriched by nylon wool-passing and cell-sorting. Therefore, it seems that decreased T cell activity is due to a decrease in T cell number and not to dysfunction of individual T cells.

Genetic control of autoimmunity in type 1 diabetes

DNA sequence analysis of major histocompatibility complex (MHC) class II genes from humans and rodents with type 1 (insulin-dependent) diabetes indicates that a portion of MHC-linked genetic susceptibility in humans is determined by the HLA-DQA1 and -DQB1 loci. In this article John Todd summarizes recent advances in these studies. The conformation of DQ molecules and their levels of expression may influence the efficiency of autoantigen presentation and the degree of pancreatic beta cells destruction during disease development. Certain DAQ1 and DQB1 alleles correlate with decreased susceptibility to disease. The penetrance of class II alleles that are correlated with positive susceptibility may be influenced by environmental factors such as bacterial and viral infections.

The genetic regulation of the induction of experimental SLE

We have recently reported the induction of systemic lupus erythematosus (SLE) in C3H.SW female mice by their immunization with a human monoclonal anti-DNA antibody that bears a common idiotype termed 16/6 Id. In the present study, the ability to induce experimental SLE in seven inbred mouse strains by immunization with the 16/6 Id was examined. Two out of the seven strains failed to develop the disease. These two strains did not produce antibodies specific to the 16/6 Id, while the other five strains produced high titres of anti-16/6 Id antibodies. The anti-16/6 Id antibody response, followed by the induction of the disease, was not found to be MHC or Ig heavy chain allotype linked. F1 hybrids between a resistant strain and two of the susceptible strains were found to be resistant to the induction of the disease, indicating that susceptibility is inherited as a recessive trait. In the autoimmune NZB/W F1 female mice, immunization with the 16/6 Id resulted in an early onset of the SLE-like disease. The results of the present study indicate the role of the anti-16/6 Id antibodies in the induction of experimental SLE, and provide direct evidence for the importance of the genetic background in determining susceptibility to SLE.

A single recessive non-MHC diabetogenic gene determines the development of insulitis in the presence of an MHC-linked diabetogenic gene in NOD mice

To study the genetic control of insulitis in non-obese diabetic (NOD) mice, we performed breeding studies in crosses of NOD with non-diabetic strains, ICR-L-line Ishibe (ILI), non-obese non-diabetic (NON) and C3H/He mice. The ILI mouse serologically shared the same MHC Class I and Class II as the NOD mouse. Insulitis was defined as islets invaded by lymphoid cells. Periductular, perivascular and peri-insular lymphoid cell infiltrations were often observed in NOD mice and appear to be the initial lesion leading to insulitis. Such lesions, however, were found in 1-year-old ICR, ILI, NON and Cataract Shionogi (CTS) mice of the NOD's sister strain. The lymphoid cells did not invade the islets in ICR, ILI, NON and CTS mice. The incidence of insulitis was 0% in F1 generations and 40% in female backcrosses (BC) [(ILI x NOD)F1 x NOD] at 9 weeks of age, 48 and 50% in BC[(NON x NOD)F1 x NOD] and BC[(C3H/He x NOD)F1 x NOD] at 1 year of age, respectively. Backcross animals were typed for the MHC to investigate correlation between the development of insulitis and MHC haplotypes. Among the backcross females with insulitis, approximately half the animals were heterozygous for MHC(non/nod) in BC[(NON x NOD)F1 x NOD] and MHC(k/nod) in BC[(C3H x NOD)F1 x NOD]. Among the backcross females with no insulitis, approximately half the animals were homozygous for MHC(nod/nod) in BC[(NON x NOD)F1 x NOD] and in BC[(C3H x NOD)F1 x NOD]. The results suggest that a single recessive non-MHC diabetogenic gene determines the development of insulitis regardless of NOD MHC homozygosity or heterozygosity.

Transplantation analysis of B cell destruction in (NOD x CBA)F1 mouse bone marrow chimeras

F1 hybrids produced by outcross of non-obese diabetic (NOD) mice with diabetes resistant strains are also diabetes resistant. This resistance is abrogated if F1 hybrids are lethally irradiated and then haematopoietically reconstituted with NOD bone marrow. This model was employed to determine whether T lymphocyte recognition and elimination of pancreatic B cells in NOD mice is restricted by the MHC haplotype of the target B cell. Diabetes resistant (NOD/Lt x CBA/J)F1 hybrids were lethally irradiated and reconstituted with NOD/Lt bone marrow. Following haematopoietic reconstitution, donor matched NOD/Lt or CBA/J pancreatic islet and anterior pituitary grafts were grafted under a renal capsule to determine whether effector cells derived from NOD/Lt marrow progenitors would reject islet grafts in a MHC restricted fashion. The H-2k haplotype expressed by CBA/J mice differs from all known loci of the unique H-2 haplotype of NOD; therefore, if NOD/Lt T lymphocytes eliminate pancreatic B cells in a MHC restricted fashion. NOD islet grafts would be eliminated in these chimeras while CBA islet grafts would be retained. Overt diabetes developed in 80% of the female and 40% of the male F1 hybrids following reconstitution with NOD/Lt marrow, while no hybrids reconstituted with CBA/J marrow became diabetic through a year of age. The retention of CBA/J skin and pituitary grafts in NOD/Lt marrow reconstituted F1 hybrids confirmed that the F1 thymic environment imparted tolerance to CBA/J alloantigens. Nonetheless, responses to a T cell dependent model antigen were restricted to the unique MHC haplotype of NOD. This was associated in the hyperglycaemic chimeras with rejection (8-21 days post-implantation) of both CBA/J and NOD/Lt islet grafts.(ABSTRACT TRUNCATED AT 250 WORDS)

Major histocompatibility complex-linked diabetogenic gene of the nonobese diabetic mouse. Analysis of genomic DNA amplified by the polymerase chain reaction

Inheritance of insulin-dependent diabetes mellitus (IDDM) is polygenic, and at least one of the genes conferring susceptibility to diabetes is tightly linked to the MHC. Recent studies have suggested that DQB1 of humans and I-A beta of mice are closely associated with susceptibility and resistance to IDDM. For further characterization and localization of the MHC-linked diabetogenic gene, we studied the genomic sequence of the A beta gene of the nonobese diabetic (NOD) mouse, an animal model of IDDM, in comparison with those of its sister strains, nonobese nondiabetic and cataract Shionogi (CTS) mice, and the original strain, outbred Imperial Cancer Research (ICR) mice. Genomic DNAs from these strains were amplified in vitro by the polymerase chain reaction with thermostable Taq polymerase. The amplified sequences were analyzed by restriction endonuclease digestion, hybridization with allele-specific oligonucleotide probes, and direct sequencing. The unique I-A beta sequence of NOD mice was observed in the sister strain, CTS mice, and in one mouse of the original strain, outbred ICR mice. These data together with the results of MAb typing of MHC molecules and restriction mapping of the I-A region suggest that the unique class II MHC of NOD mice is not the result of a recent mutation, but is derived from the original strain. Since class I MHC of CTS mice is different from the MHC of NOD mice at both the K and D loci, CTS mice are a naturally occurring recombinant strain with NOD type class II MHC and non-NOD type class I MHC. Thus, breeding studies in crosses of NOD with CTS mice should provide biological information on whether the unique class II MHC of NOD mice is diabetogenic.

Immunostimulation circumvents diabetes in NOD/Lt mice

Diabetes susceptibility in non-obese diabetic (NOD) mice may entail faulty activation of immunoregulatory cells resulting from cytokine deficiencies. Depletion of T cells prevents disease onset in these mice. Since we had previously shown that IL-2 treatment in vivo restored the ability of NOD/Lt mice to produce self-restricted suppressor T cells (Ts) in a syngeneic mixed lymphocyte reaction (SMLR), we investigated the possibility that diabetes could be circumvented by treatment with immunostimulatory agents that increase cytokine production. By 20 weeks of age, 75% of vehicle-treated NOD/Lt female controls had become glycosuric, while glycosuria developed in only 17% of NOD/Lt females injected with human recombinant interleukin-2 (rIL-2, 250 U twice weekly) beginning at 6 weeks of age. Treatment of mice with Poly [I:C] alone [50 micrograms twice weekly, an inducer of Interferon (IFN) alpha/beta] or in conjunction with rIL-2 was even more effective, completely preventing glycosuria for 20 weeks. However, therapeutic effects required continuous administration of the immunostimulants since pancreatic insulin content declined and severity of insulitis increased following cessation of treatment. IL-2 treatment increased transcription of interleukin-1 (IL-1) mRNA in peritoneal macrophages and increased lipopolysaccharide (LPS)-stimulated IL-1 secretion in comparison to controls. In the presence of stimulators from IL-2-treated mice, T lymphocytes isolated from both controls and IL-2-treated NOD/Lt mice proliferated in a SMLR and acquired Ts function. Peritoneal macrophages from Poly [I:C]-treated mice exhibited increased IFN alpha gene transcription and LPS-stimulated IL-1 secretion. T cells isolated from Poly [I:C]-treated mice were capable of suppressing NOD-Lt T cell responses to alloantigens in a mixed lymphocyte culture without prior activation in a SMLR. Thus, Poly [I:C] treatment may recruit a different population of regulatory cells than those elicited by treatment with IL-2. However, the mechanisms by which autoreactive T-cell clones may be regulated by these two treatments in NOD/Lt mice may be synergistic. These results indicate that in addition to T-cell depletion protocols, diabetes in NOD mice can be prevented by treatment with immunostimulatory agents.

Allelic T-cell receptor alpha complexes have little or no influence on susceptibility to type 1 diabetes

We performed a multiple-affected-sib study to determine if T-cell receptor alpha-chain alleles affect susceptibility to insulin-dependent diabetes mellitus. Restriction fragment length polymorphisms were used to follow the segregation of allelic T-cell receptor alpha complexes within the families. The segregation of T-cell receptor alpha alleles in 29 multiplex families revealed no significant tendency for affected sibs to share T-cell receptor alpha-chain alleles more often than would be expected by chance alone (p greater than 0.2). In contrast, the same type of analysis for HLA alleles easily detected the well-known linkage of insulin-dependent diabetes mellitus susceptibility to the HLA complex (p = 0.003). We suggest that the importance of HLA alleles in insulin-dependent diabetes mellitus susceptibility and the lack of importance of T-cell receptor alpha alleles result from the different strategies by which HLA and T-cell receptor molecules achieve antigen-binding diversity: multiple loci and allelic diversity in the case of HLA; combinatorial, junctional, and N-region diversity in the case of the T-cell receptor. In this paper we also describe three new restriction fragment length polymorphisms of the T-cell receptor alpha complex and a new method for testing the significance of linkage in multiple-affected-sib studies.

Lessons from the NOD mouse for the pathogenesis and immunotherapy of human type 1 (insulin-dependent) diabetes mellitus

Suitable animal models of human Type 1 (insulin-dependent) diabetes mellitus have long been sought, in particular a model that would permit detailed histological and immunological investigation of changes in the islet preceding the metabolic disorder. This would allow hypotheses as to pathogenesis of the condition to be examined and interventions such as immunotherapy to be tested. The most widely studied models include the low-dose streptozotocin induced diabetic mouse and the BB rat, but both differ in important respects from the human disease. In this review we describe one highly successful model, the non obese diabetic mouse. Selected aspects of pathogenesis and immunotherapy are presented and analogies with human Type 1 diabetes discussed.