Longitudinal study of islet cell antibodies and insulin autoantibodies and development of diabetes in non-obese diabetic (NOD) mice

Receptor for advanced glycation end-products (RAGE) provides a link between genetic susceptibility and environmental factors in type 1 diabetes

AIMS/HYPOTHESIS

This group of studies examines human genetic susceptibility conferred by the receptor for advanced glycation end-products (RAGE) in type 1 diabetes and investigates how this may interact with a western environment.

METHODS

We analysed the AGER gene, using 13 tag SNPs, in 3,624 Finnish individuals from the FinnDiane study, followed by AGER associations with a high risk HLA genotype (DR3)-DQA1*05-DQB1*02/DRB1*0401-DQB1*0302 (n = 546; HLA-DR3/DR4), matched in healthy newborn infants from the Finnish Type 1 Diabetes Prediction and Prevention (DIPP) Study (n = 373) using allelic analysis. We also studied islets and circulating RAGE in NODLt mice.

RESULTS

The rs2070600 and rs17493811 polymorphisms predicted increased risk of type 1 diabetes, whereas the rs9469089 SNP was related to decreased risk, on a high risk HLA background. Children from the DIPP study also showed a decline in circulating soluble RAGE levels, at seroconversion to positivity for type 1 diabetes-associated autoantibodies. Islet RAGE and circulating soluble RAGE levels in prediabetic NODLt mice decreased over time and were prevented by the AGE lowering therapy alagebrium chloride. Alagebrium chloride also decreased the incidence of autoimmune diabetes and restored islet RAGE levels.

CONCLUSIONS/INTERPRETATION

These studies suggest that inherited AGER gene polymorphisms may confer susceptibility to environmental insults. Declining circulating levels of soluble RAGE, before the development of overt diabetes, may also be predictive of clinical disease in children with high to medium risk HLA II backgrounds and this possibility warrants further investigation in a larger cohort.

Emerging roles for B lymphocytes in Type 1 diabetes

Self-reactive B lymphocytes play two main pathological roles in autoimmune diseases: as secretors of autoantibodies and as specialized antigen-presenting cells that present self-components to autoreactive T lymphocytes. In recognition of these roles, recent clinical trials have utilized B-lymphocyte-depleting monoclonal antibodies to treat various autoimmune diseases, with encouraging results in those where humoral autoimmunity is clearly important. Surprisingly, recent results in animal models suggest that B-lymphocyte depletion may also be effective in the treatment of T-lymphocyte-mediated autoimmune diseases, such as Type 1 diabetes (T1D). This article reviews the experimental evidence that has uncovered pathogenic as well as regulatory roles for B lymphocytes in the prodrome of T1D and how this information is being used to develop novel therapeutic strategies to treat the disease.

Increased transcriptional preproinsulin II beta-cell activity in neonatal nonobese diabetic mice: in situ hybridization analysis

In the prediabetic nonobese diabetic (NOD) mouse, a spontaneous model of type 1 diabetes, we previously reported transient postweaning hyperinsulinemia followed by progressive islet hyperplasia. A modified in situ hybridization technique was used to determine whether these effects were accompanied by changes in insulin transcriptional activity as a function of age. We found that NOD neonates express higher levels of preproinsulin II primary transcripts than age-matched C57BL/6 mice, but this difference disappeared within the first wk of age. To manipulate insulin transcriptional activity in NOD neonates, NOD mothers were treated with insulin during the last two wk of gestation. A down-regulation of beta-cell hyperactivity was observed in female NOD neonates but not in male neonates. By contrast, the same insulin treatment applied to NODscid (severe combined immunodeficiency) mothers, devoid of functional lymphocytes but showing like NOD mice postweaning hyperinsulinemia, increased transcriptional beta-cell activity in both sexes of neonates. In conclusion, NOD mice exhibit successive and transient signs of beta-cell hyperactivity, reflected as early as birth by high transcriptional preproinsulin II activity and later, from weaning to around 10 wk of age, by hyperinsulinemia. Of note, when thinking in terms of in utero disease programming, the NOD neonatal transcriptional beta-cell hyperactivity could be modulated by environmental (maternal and/or fetal) factors.

Temporal discontinuities in progression of NOD autoimmune diabetes

Consideration of the pathophysiology of insulin-dependent diabetes mellitus in the nonobese diabetic (NOD) mouse can be viewed from a temporal perspective. We argue that there are discontinuous phases and each phase may reflect a phenotype educed by a particular set of genetic and epigenetic events. Therefore, temporal dissection may be a useful platform for causal dissection and we have set out this article as follows: 1. Introduction. 2. "Pre-time." a. Genetics. b. Parental effects. 3. Development of insulitis. a. Development of autoimmunity vs waning of or failure to establish tolerance. b. Importance of beta cell mass. c. Homing. 4. Onset of beta cell destruction. 5. Further Discussion.

Influence of T lymphocytes and major histocompatibility complex class II genes on diabetes susceptibility in the NOD mouse

Central to the autoimmune pathogenesis of IDDM in NOD mice is the MHC class II region. In all models studied to date, expression of NOD MHC class II genes is essential for disease development suggesting a crucial role for I-ANOD-restricted presentation of autoantigen. Protection has been afforded by transgene incorporation of other non-NOD class II genes and many models have been proposed to account for this effect. It is now clear that protection is not achieved by deletion or permanent silencing of all autoreactive T cell clones. It also appears that expression of these genes is required both intra- and extrathymically. It still remains to be determined what role these genes may have in the various compartments and how the autoreactive cells are held in check in protected NOD transgenic mice. Currently, the most likely explanation is that intrathymic expression of non-NOD class II genes is required for the positive selection of class II-restricted immunoregulatory T cells, while peripheral expression is necessary to bring about the interaction of these cells in a tricellular complex with NOD autoantigen-specific T cells and APCs, so that the response can be deviated to a nonpathogenetic one. Whether this process is active or passive is not known.

Self and non-self antigen in diabetic autoimmunity: molecules and mechanisms

In this article, we have summarized current facts, models and views of the autoimmunity that leads to destruction of insulin-producing beta-cells and consequent Type 1 (insulin-dependent) diabetes mellitus. The presence of strong susceptibility and resistance gene loci distinguishes this condition from other autoimmune disorders, but environmental disease factors must conspire to produce disease. The mapping of most of the genetic risk (or disease resistance) to specific alleles in the major histocompatibility locus (MHC class II) has direct functional implications for our understanding of autoimmunity in diabetes and directly implies that presentation of a likely narrow set of peptides is critical to the development of diabetic autoimmunity. While many core scientific questions remain to be answered, current insight into the disease process is beginning to have direct clinical impact with concerted efforts towards disease prevention or intervention by immunological means. In this process, identification of the critical antigenic epitopes recognized by diabetes-associated T cells has achieved highest priority.

First phase insulin release in the non-obese diabetic mouse: correlation with insulitis, beta cell number and autoantibodies

The ontogenic variation of beta cell function and its relationship with the degree of islet damage and levels of autoantibodies have been studied in the non-obese diabetic (NOD) mouse model. We conducted in vivo first phase insulin release (FPIR) in response to intravenous glucose and studied its correlation with the degree of insulitis, islet cell antibody (ICA) and insulin autoantibody (IAA) levels in female NOD mice cross-sectionally at days 40 (n = 19), 90 (n = 21), 150-160 (n = 21) and day 250 (n = 20). The mean +/- SEM FPIR values showed an age-related decline from day 40 (46.2 +/- 5.3 microU/ml) to day 150-160 (17.8 +/- 2.5 microU/ml) and then doubled at day 250 (34.5 +/- 5 microU/ml), while the mean +/- SEM insulitis scores increased progressively until day 150-160 (61.7 +/- 6.1%) and then declined slightly at day 250 to 50.2 +/- 6.2%. In female NOD mice with spontaneous diabetes (n = 4) and streptozotocin-induced diabetic Swiss mice (n = 5) FPIR was either absent or greatly attenuated. A statistically significant inverse correlation between FPIR and insulitis was found among NOD mice at days 90 (P = 0.02; r = -0.52) and 150-160 (P = 0.03; r = -0.48). However, no statistically significant correlation was observed at days 40 and 250. Morphometric techniques applied to day 150-160 pancreatic sections showed a statistically significant negative correlation between insulitis and beta cell number per unit area of islet tissue (P = 0.0001; r = - 0.75). At this age some islet beta cells showed different intensities of staining by immunofluorescence.(ABSTRACT TRUNCATED AT 250 WORDS)

Studies of autoantibodies reactive with thyroid membrane antigens and insulin in non obese diabetic mice

Enzyme-linked immunosorbent assay (ELISA) was used to study the temporal relationship between the appearance of murine autoantibodies reactive to insulin and thyroid membrane antigens (TMA) and the development of diabetes and thyroiditis in the non obese diabetic (NOD) mouse. Overall, 28% of NOD mice had antibodies specific for mouse thyroid membrane antigens (MTMA), 30% had antibodies to human thyroid membrane antigens (HTMA) and 23% of NOD mice had insulin autoantibodies (IAA), in at least one of their serial monthly blood samples. Non autoimmune BALB/c mice did not develop antibodies to these antigens. Presence of IAA was associated with the development of diabetes and in 87% of cases such antibodies were detected before the diabetes was diagnosed. IAA were usually demonstrated before insulitis. No association between thyroiditis and IAA was noted. Anti-MTMA and anti-HTMA antibodies were detected more frequently in NOD mice with thyroiditis than in those without thyroid inflammation. No significant association was noted between detection of serum anti-TMA antibodies and the development of diabetes. In young mice, anti-TMA antibodies were not detected in the absence of thyroiditis. Western blot analysis of NOD sera positive for MTMA by ELISA revealed a heterogeneous pattern of reactivity. The significance of these findings with respect to the pathogenesis of diabetes and thyroiditis and their association, is discussed.