Administration of silica particles or anti-Lyt2 antibody prevents beta-cell destruction in NOD mice given cyclophosphamide

Islet-resident macrophage-derived miR-155 promotes β cell decompensation via targeting PDX1

Chronic inflammation is critical for the initiation and progression of type 2 diabetes mellitus via causing both insulin resistance and pancreatic β cell dysfunction. miR-155, highly expressed in macrophages, is a master regulator of chronic inflammation. Here we show that blocking a macrophage-derived exosomal miR-155 (MDE-miR-155) mitigates the insulin resistances and glucose intolerances in high-fat-diet (HFD) feeding and type-2 diabetic db/db mice. Lentivirus-based miR-155 sponge decreases the level of miR-155 in the pancreas and improves glucose-stimulated insulin secretion (GSIS) ability of β cells, thus leading to improvements of insulin sensitivities in the liver and adipose tissues. Mechanistically, miR-155 increases its expression in HFD and db/db islets and is released as exosomes by islet-resident macrophages under metabolic stressed conditions. MDE-miR-155 enters β cells and causes defects in GSIS function and insulin biosynthesis via the miR-155-PDX1 axis. Our findings offer a treatment strategy for inflammation-associated diabetes via targeting miR-155.

Crosstalk between Macrophages and Pancreatic β-Cells in Islet Development, Homeostasis and Disease

Macrophages are highly heterogeneous and plastic immune cells with peculiar characteristics dependent on their origin and microenvironment. Following pathogen infection or damage, circulating monocytes can be recruited in different tissues where they differentiate into macrophages. Stimuli present in the surrounding milieu induce the polarisation of macrophages towards a pro-inflammatory or anti-inflammatory profile, mediating inflammatory or homeostatic responses, respectively. However, macrophages can also derive from embryonic hematopoietic precursors and reside in specific tissues, actively participating in the development and the homeostasis in physiological conditions. Pancreatic islet resident macrophages are present from the prenatal stages onwards and show specific surface markers and functions. They localise in close proximity to β-cells, being exquisite sensors of their secretory ability and viability. Over the years, the crucial role of macrophages in β-cell differentiation and homeostasis has been highlighted. In addition, macrophages are emerging as central players in the initiation of autoimmune insulitis in type 1 diabetes and in the low-grade chronic inflammation characteristic of obesity and type 2 diabetes pathogenesis. The present work reviews the current knowledge in the field, with a particular focus on the mechanisms of communication between β-cells and macrophages that have been described so far.

Immunity to the Dual Threat of Silica Exposure and Mycobacterium tuberculosis

Exposure to silica and the consequent development of silicosis are well-known health problems in countries with mining and other dust producing industries. Apart from its direct fibrotic effect on lung tissue, chronic and immunomodulatory character of silica causes susceptibility to tuberculosis (TB) leading to a significantly higher TB incidence in silica-exposed populations. The presence of silica particles in the lung and silicosis may facilitate initiation of tuberculous infection and progression to active TB, and exacerbate the course and outcome of TB, including prognosis and survival. However, the exact mechanisms of the involvement of silica in the pathological processes during mycobacterial infection are not yet fully understood. In this review, we focus on the host's immunological response to both silica and Mycobacterium tuberculosis, on agents of innate and adaptive immunity, and particularly on silica-induced immunological modifications in co-exposure that influence disease pathogenesis. We review what is known about the impact of silica and Mycobacterium tuberculosis or their co-exposure on the host's immune system, especially an impact that goes beyond an exclusive focus on macrophages as the first line of the defense. In both silicosis and TB, acquired immunity plays a major role in the restriction and/or elimination of pathogenic agents. Further research is needed to determine the effects of silica in adaptive immunity and in the pathogenesis of TB.

IAPP and type 1 diabetes: implications for immunity, metabolism and islet transplants

Islet amyloid polypeptide (IAPP), the main component of islet amyloid in type 2 diabetes and islet transplants, is now recognized as a contributor to beta cell dysfunction. Increasingly, evidence warrants its investigation in type 1 diabetes owing to both its immunomodulatory and metabolic actions. Autoreactive T cells to IAPP-derived epitopes have been described in humans, suggesting that IAPP is an islet autoantigen in type 1 diabetes. In addition, although aggregates of IAPP have not been implicated in type 1 diabetes, they are potent pro-inflammatory stimuli to innate immune cells, and thus, could influence autoimmunity. IAPP aggregates also occur rapidly in transplanted islets and likely contribute to islet transplant failure in type 1 diabetes through sterile inflammation. In addition, since type 1 diabetes is a disease of both insulin and IAPP deficiency, clinical trials have examined the potential benefits of IAPP replacement in type 1 diabetes with the injectable IAPP analogue, pramlintide. Pramlintide limits postprandial hyperglycemia by delaying gastric emptying and suppressing hyperglucagonemia, underlining the possible role of IAPP in postprandial glucose metabolism. Here, we review IAPP in the context of type 1 diabetes: from its potential involvement in type 1 diabetes pathogenesis, through its role in glucose metabolism and use of IAPP analogues as therapeutics, to its potential role in clinical islet transplant failure and considerations in this regard for future beta cell replacement strategies.

Do post-translational beta cell protein modifications trigger type 1 diabetes?

Type 1 diabetes is considered an autoimmune disease characterised by specific T cell-mediated destruction of the insulin-producing beta cells. Yet, except for insulin, no beta cell-specific antigens have been discovered. This may imply that the autoantigens in type 1 diabetes exist in modified forms capable of specifically triggering beta cell destruction. In other immune-mediated diseases, autoantigens targeted by the immune system have undergone post-translational modification (PTM), thereby creating tissue-specific neo-epitopes. In a similar manner, PTM of beta cell proteins might create beta cell-specific neo-epitopes. We suggest that the current paradigm of type 1 diabetes as a classical autoimmune disease should be reconsidered since the immune response may not be directed against native beta cell proteins. A modified model for the pathogenetic events taking place in islets leading to the T cell attack against beta cells is presented. In this model, PTM plays a prominent role in triggering beta cell destruction. We discuss literature of relevance and perform genetic and human islet gene expression analyses. Both direct and circumstantial support for the involvement of PTM in type 1 diabetes exists in the published literature. Furthermore, we report that cytokines change the expression levels of several genes encoding proteins involved in PTM processes in human islets, and that there are type 1 diabetes-associated polymorphisms in a number of these. In conclusion, data from the literature and presented experimental data support the notion that PTM of beta cell proteins may be involved in triggering beta cell destruction in type 1 diabetes. If the beta cell antigens recognised by the immune system foremost come from modified proteins rather than native ones, the concept of type 1 diabetes as a classical autoimmune disease is open for debate.

Type 1 diabetes development requires both CD4+ and CD8+ T cells and can be reversed by non-depleting antibodies targeting both T cell populations

Type 1 diabetes development in NOD mice appears to require both CD4(+) and CD8(+) T cells. However, there are some situations where it has been suggested that either CD4(+) or CD8(+) T cells are able to mediate diabetes in the absence of the other population. In the case of transgenic mice, this may reflect the numbers of antigen-specific T cells able to access the pancreas and recruit other cell types such as macrophages leading to a release of high concentrations of damaging cytokines. Previous studies examining the requirement for CD8(+) T cells have used antibodies specific for CD8alpha. It is known that CD8alpha is expressed not only on alphabeta T cells, but also on other cell types, including a DC population that may be critical for presenting islet antigen in the pancreatic draining lymph nodes. Therefore, we have re-examined the need for both CD4(+) and CD8(+) T cell populations in diabetes development in NOD mice using an antibody to CD8beta. Our studies indicate that by using highly purified populations of T cells and antibodies specific for CD8(+) T cells, there is indeed a need for both cell types. In accordance with some other reports, we found that CD4(+) T cells appeared to be able to access the pancreas more readily than CD8(+) T cells. Despite the ability of CD4(+) T cells to recruit CD11b class II positive cells, diabetes did not develop in the absence of CD8(+) T cells. These studies support the observation that CD8(+) T cells may be final effector cells. As both T cell populations are clearly implicated in diabetes development, we have used a combination of non-depleting antibodies to target both CD4-positive and CD8-positive cells and found that this antibody combination was able to reverse diabetes onset in NOD mice as effectively as anti-CD3 antibodies.

TSG-6 protein expression in the pancreatic islets of NOD mice

The histologic hallmark of the development of type 1 diabetes (T1D) is insulitis, characterized by leukocytic infiltration of the pancreatic islets. The molecules controlling the early influx of leukocytes into the islets are poorly understood. Tumor necrosis factor alpha (TNFalpha)-stimulated gene 6 (TSG-6) is involved in inflammation, extracellular matrix formation, cell migration, and development. In the present study, we examined the expression and cellular localization of TSG-6 protein in islets of female non-obese diabetic (NOD) mice using frozen section immunofluorescence staining. Pancreata from nondiabetic (8 and 25 weeks old), prediabetic (230-280 mg/dl blood glucose) and diabetic (>300 mg/dl blood glucose) NOD mice were stained for TSG-6, insulin, CD3, CD11c, Mac3 and CD31. TSG-6 protein was detected in 67% of islets of prediabetic mice, 27% of islets of 25-week old nondiabetic mice, and less than 7% of islets of diabetic mice and 8-week old nondiabetic mice. Lastly, islet-derived TSG-6 protein was localized to the infiltrating CD3 and CD11c positive leukocytes.

Newly weaned nonobese diabetic mice show heightened early diabetes sensitivity to multiple low doses of streptozotocin than nondiabetes-prone CD-1 mice: initial beta-cell damage a key trigger for type 1 diabetes?

OBJECTIVES

We determined if newly weaned female nonobese diabetic (NOD) mice show greater diabetes sensitivity to dose-adjusted regimens of multiple low doses of streptozotocin (Stz) than nondiabetes-prone CD-1 mice.

METHODS

Female NOD mice received 5 daily doses of Stz from day 21 (0, 5, 10, 15, 20, 30, and 40 mg/kg body weight) and CD-1 mice 20, 30, and 40 mg.

RESULTS

: Streptozotocin, at the 15-, 20-, 30-, and 40-mg dose, induced rapid diabetes in NOD mice. By day 100, 90% to 95% of NOD mice became diabetic after the 40- and 30-mg dose and 33% to 40% with the 15- and 20-mg dose. In comparison, only about 50% and 33% of CD-1 mice developed diabetes with the 40- and 30-mg dose, respectively, and 5.5% with the 20-mg dose. In NOD mice, the 20-mg dose also partially suppressed spontaneous diabetes. All diabetic mice displayed insulitis, variable immunostaining for insulin, and redistribution of glucagon and somatostatin cells. Glucose transporter-2 was markedly attenuated in selective beta cells.

CONCLUSIONS

Newly weaned female NOD mice show heightened early sensitivity to low doses of Stz than CD-1 mice. At diabetes, several beta cells remain and show variable immunostaining for insulin and an attenuated expression for glucose transporter-2. Specific low doses of Stz may also suppress spontaneous diabetes.

In CD4+ T-cell-induced diabetes, macrophages are the final effector cells that mediate islet beta-cell killing: studies from an acute model

To understand better how diabetogenic CD4+ T cells induce islet beta-cell death and cause diabetes, a transfer model of acute diabetes using the diabetogenic CD4+ BDC2.5 T-cell clone was established. Transfer of activated BDC T cells into NOD.scid mice resulted in diabetes within a week, characterized by strong inflammatory reaction. Electron micrographs of pancreas depicted macrophages in close contact with beta cells that exhibited signs of apoptosis. Transfer into irradiated recipients inhibited inflammation and the development of diabetes, demonstrating an obligatory role for leukocytes. Selective depletion of neutrophils or natural killer cells had no effect on diabetes induced by BDC2.5 T cells. In contrast, in vivo depletion of phagocytic cells by injection of liposomes containing clodronate abolished diabetes, although inflammation remained present and was characterized mainly by neutrophil infiltration. Treatment with clodronate-liposomes did not affect the antigen-presenting cells within the pancreas. Last, activated macrophages isolated from infiltrated pancreas exhibited cytolytic activity toward primary islet beta cells. Taken together, these results demonstrate that activated macrophages are the key cells mediating islet beta-cell death induced by activated CD4+ T cells.

Molecular Genetic Analysis of the Idd4 Locus Implicates the IFN Response in Type 1 Diabetes Susceptibility in Nonobese Diabetic Mice

High-resolution mapping and identification of the genes responsible for type 1 diabetes (T1D) has proved difficult because of the multigenic etiology and low penetrance of the disease phenotype in linkage studies. Mouse congenic strains have been useful in refining Idd susceptibility loci in the NOD mouse model and providing a framework for identification of genes underlying complex autoimmune syndromes. Previously, we used NOD and a nonobese diabetes-resistant strain to map the susceptibility to T1D to the Idd4 locus on chromosome 11. Here, we report high-resolution mapping of this locus to 1.4 megabases. The NOD Idd4 locus was fully sequenced, permitting a detailed comparison with C57BL/6 and DBA/2J strains, the progenitors of T1D resistance alleles found in the nonobese diabetes-resistant strain. Gene expression arrays and quantitative real-time PCR were used to prioritize Idd4 candidate genes by comparing macrophages/dendritic cells from congenic strains where allelic variation was confined to the Idd4 interval. The differentially expressed genes either were mapped to Idd4 or were components of the IFN response pathway regulated in trans by Idd4. Reflecting central roles of Idd4 genes in Ag presentation, arachidonic acid metabolism and inflammation, phagocytosis, and lymphocyte trafficking, our combined analyses identified Alox15, Alox12e, Psmb6, Pld2, and Cxcl16 as excellent candidate genes for the effects of the Idd4 locus.

MHC-Mismatched Islet Allografts Are Vulnerable to Autoimmune Recognition In Vivo

When transplanted into type 1a diabetic recipients, islet allografts are subject both to conventional allograft immunity and, presumably, to recurrent autoimmune (islet-specific) pathogenesis. Importantly, CD4 T cells play a central role both in islet allograft rejection and in autoimmune disease recurrence leading to the destruction of syngeneic islet transplants in diabetic NOD mice. However, it is unclear how NOD host MHC class II (I-A(g7))-restricted, autoreactive CD4 T cells may also contribute to the recognition of allogeneic islet grafts that express disparate MHC class II molecules. We hypothesized that islet-specific CD4 T cells can target MHC-mismatched islet allografts for destruction via the "indirect" (host APC-dependent) pathway of Ag recognition. To test this hypothesis, we determined whether NOD-derived, islet-specific CD4 T cells (BDC-2.5 TCR transgenic cells) could damage MHC-mismatched islets in vivo independent of conventional allograft immunity. Results demonstrate that BDC-2.5 CD4 T cells can vigorously destroy MHC class II-disparate islet allografts established in NOD.scid recipients. Tissue injury is tissue-specific in that BDC-2.5 T cells destroy donor-type islet, but not thyroid allografts established in the same NOD.scid recipient. Furthermore, BDC-2.5 CD4 T cells acutely destroy MHC class II-deficient islet allografts in vivo, indicating that autoimmune pathogenesis can be completely independent of donor MHC class II expression. Taken together, these findings indicate that MHC-mismatched islet allografts can be vulnerable to autoimmune pathogenesis triggered by autoreactive CD4 T cells, presumably through indirect autoantigen recognition in vivo.

Autoimmune diabetes: ongoing development of immunological intervention strategies targeted directly against autoreactive T cells

It is well known that autoimmunity associated with the onset of insulin-dependent diabetes mellitus (IDDM) involves the generation of autoreactive T and B cells. The findings that diabetics mount humoral and cellular immune responses against islet cell antigens (ICAs) have led to the testing of ICAs and their analogs as candidates for therapeutic agents for better treatment of IDDM at its prediabetic and diabetic stages. Apart from this type of approach, various immunological intervention strategies aimed at direct targeting of the autoreactive T cells have also been investigated. The present review covers the ongoing aspects of these developments focusing on the preclinical findings made in NOD (nonobese diabetic) mice which have been commonly used as a disease model for human autoimmune diabetes. Other types of approaches involving the mobilization of regulatory T cells to indirectly control or modulate the pathological activity of autoreactive T cells will not be discussed within this scope.

Dietary supplementation with the tribomechanically activated zeolite clinoptilolite in immunodeficiency: effects on the immune system

Natural zeolites are crystalline aluminosilicates with unique adsorption, cation-exchange, and catalytic properties that have multiple uses in industry and agriculture. TMAZ, a natural zeolite clinoptilolite with enhanced physicochemical properties, is the basis of the dietary supplements Megamin and Lycopenomin, which have demonstrated antioxidant activity in humans. The aim of this prospective, open, and controlled parallel-group study was to investigate the effects of supplementation with TMAZ on the cellular immune system in patients undergoing treatment for immunodeficiency disorder. A total of 61 patients were administered daily TMAZ doses of 1.2 g (Lycopenomin) and 3.6 g (Megamin) for 6 to 8 weeks, during which the patients' primary medical therapy was continued unchanged. Blood and lymphocyte counts were performed at baseline and at the end of the study. Blood count parameters were not relevantly affected in either of the two treatment groups. Megamin administration resulted in significantly increased CD4+, CD19+, and HLA-DR+ lymphocyte counts and a significantly decreased CD56+ cell count. Lycopenomin was associated with an increased CD3+ cell count and a decreased CD56+ lymphocyte count. No adverse reactions to the treatments were observed.

Beta cell MHC class I is a late requirement for diabetes

Type 1 diabetes occurs as a result of an autoimmune attack on the insulin-producing beta cells. Although CD8 T cells have been implicated both early and late in this process, the requirement for direct interaction between these cells and MHC class I on the beta cells has not been demonstrated. By using nonobese diabetic mice lacking beta cell class I expression, we show that both initiation and progression of insulitis proceeds unperturbed. However, without beta cell class I expression, the vast majority of these mice do not develop hyperglycemia. These findings demonstrate that a direct interaction between CD8 T cells and beta cells is not required for initiation or early disease progression. The requirement for class I on beta cells is a relatively late checkpoint in the development of diabetes.

Prospects for the prevention and reversal of type 1 diabetes mellitus

Type 1 (insulin-dependent) diabetes mellitus results from selective immune-mediated destruction of pancreatic islet beta cells. Strategies to prevent or reverse the development of diabetes can be divided into three groups, depending on whether they focus on beta-cell protection, regeneration or replacement. Prevention of immune beta-cell destruction involves either halting the immune attack directed against beta cells or making beta cells better able to withstand immune attack, for example, by making them resistant to free radical damage. The recent identification of beta-cell growth factors and development of stem cell technologies provides an alternative route to the reversal of diabetes, namely beta-cell regeneration. Interestingly, stem cell-derived islets appear to be less sensitive to recurrent immune destruction that is normally seen in response to islet transplantation. The last alternative is beta-cell replacement or substitution. This covers a wide range of interventions including human whole pancreas transplantation, xenotransplantation, genetically modified beta cells, mechanical insulin sensing and delivery devices, and the artificial pancreas. This review describes recent advances in each of these research areas and aims to provide clinicians with an idea of where and when an effective strategy to prevent or reverse diabetes development will become available.

A new look at viruses in type 1 diabetes

Type 1 diabetes (T1D) results from the destruction of pancreatic beta cells. Genetic factors are believed to be a major component for the development of T1D, but the concordance rate for the development of diabetes in identical twins is only about 40%, suggesting that nongenetic factors play an important role in the expression of the disease. Viruses are one environmental factor that is implicated in the pathogenesis of T1D. To date, 14 different viruses have been reported to be associated with the development of T1D in humans and animal models. Viruses may be involved in the pathogenesis of T1D in at least two distinct ways: by inducing beta cell-specific autoimmunity, with or without infection of the beta cells, [e.g. Kilham rat virus (KRV)] and by cytolytic infection and destruction of the beta cells (e.g. encephalomyocarditis virus in mice). With respect to virus-mediated autoimmunity, retrovirus, reovirus, KRV, bovine viral diarrhoea-mucosal disease virus, mumps virus, rubella virus, cytomegalovirus and Epstein-Barr virus (EBV) are discussed. With respect to the destruction of beta cells by cytolytic infection, encephalomyocarditis virus, mengovirus and Coxsackie B viruses are discussed. In addition, a review of transgenic animal models for virus-induced autoimmune diabetes is included, particularly with regard to lymphocytic choriomeningitis virus, influenza viral proteins and the Epstein-Barr viral receptor. Finally, the prevention of autoimmune diabetes by infection of viruses such as lymphocytic choriomeningitis virus is discussed.

Immunotherapy of type 1 diabetes: lessons for other autoimmune diseases

The nonobese diabetic (NOD) mouse is a well-recognised animal model of spontaneous autoimmune insulin-dependent diabetes mellitus. The disease is T-cell mediated, involving both CD4 and CD8 cells. Its progress is controlled by a variety of regulatory T cells. An unprecedented number of immunological treatments have been assessed in this mouse strain. This chapter systematically reviews most of these therapeutic manoeuvres, discussing them in the context of their significance with regard to the underlying mechanisms and the potential clinical applications. The contrast between the surprisingly high rate of success found for a multitude of treatments (more than 160) administered early in the natural history of the disease and the few treatments active at a late stage is discussed in depth. Most of the concepts and strategies derived from this model apply to other autoimmune diseases, for which no such diversified data are available.

Transgenic rescue implicates beta2-microglobulin as a diabetes susceptibility gene in nonobese diabetic (NOD) mice

Type 1 diabetes in both humans and nonobese diabetic (NOD) mice results from T-cell-mediated autoimmune destruction of insulin-producing pancreatic beta cells. Linkage studies have shown that type 1 diabetes in NOD mice is a polygenic disease involving more than 15 chromosomal susceptibility regions. Despite extensive investigation, the identification of individual susceptibility genes either within or outside the major histocompatibility complex region has proven problematic because of the limitations of linkage analysis. In this paper, we provide evidence implicating a single diabetes susceptibility gene, which lies outside the major histocompatibility complex region. Using allelic reconstitution by transgenic rescue, we show that NOD mice expressing the beta(2) microglobulin (beta(2)M)(a) allele develop diabetes, whereas NOD mice expressing a murine beta(2)M(b) or human allele are protected. The murine beta(2)M(a) allele differs from the beta(2)M(b) allele only at a single amino acid. Mechanistic studies indicate that the absence of the NOD beta(2)M(a) isoform on nonhematopoietic cells inhibits the development or activation of diabetogenic T cells.

TNF-alpha receptor 1 (p55) on islets is necessary for the expression of LIGHT on diabetogenic T cells

Insulin-dependent diabetes mellitus results from T-cell-mediated destruction of pancreatic islet beta cells. Both CD4 and CD8 T cells have been shown to be independently capable of beta cell destruction. However, the mechanism of beta cell destruction has remained elusive. It has previously been shown that the absence of TNF-alpha receptor 1 (p55) on the islets protected islets from CD4 T-cell-mediated destruction as long as the T cells did not have access to wild-type islets in vivo. Wild-type and TNF-alpha receptor 1 (p55) deficient islets induce similar levels of proliferation of BDC2.5 T cells. In this study, we demonstrate that islet TNF-alpha receptor 1 (p55) influences the expression of LIGHT (TNFSF-14), a TNF family member with both cytolytic and costimulatory properties, on BDC2.5 T cells and the expression of its receptor HVEM (TNFRSF-14) by islets, indicating a role for LIGHT-HVEM interactions in autoimmune diabetes.

Dual-label immunohistochemical study of interleukin-4-and interferon-gamma-expressing cells within the pancreas of the NOD mouse during disease acceleration with cyclophosphamide

Beta cell destruction has been shown to occur when rodent or human islets are exposed in vitro to inflammatory cytokines, such as interleukin-1beta (IL-1beta), tumour necrosis factor-alpha (TNF-alpha) and interferon-gamma (IFN-gamma). Other cytokines such as interleukin-4 (IL-4) or interleukin-10 (IL-10), when given to NOD mice, prevent insulin-dependent diabetes mellitus (IDDM). In this study, we have employed immunofluorescence histochemistry to study the expression of IFN-gamma and IL-4 in the pancreas of female NOD mice at various time-points (days 0, 4, 7, 11 and at onset of diabetes) following disease acceleration with cyclophosphamide (Cy). Dual-label confocal and light microscopy were employed to determine the precise cellular sources of the two cytokines. IL-4 immunolabelling was observed in a few immune cells at days 0, 4, and 7 within the pancreatic islets but in larger numbers at day 11 and at onset of diabetes. The cytokine was co-localized predominantly in CD4 cells, while only a small minority of CD8 cells and macrophages also expressed IL-4. At days 0, 4, 7 and 11, weak to moderate immunolabelling for IL-4 was also observed in beta cells. In contrast, immunolabelling for IFN-gamma within the islets was not observed until day 11 and this labelling persisted at onset of diabetes. It was immunolocalized in macrophages and to a lesser extent in CD4 cells. Only a few CD8 cells were immunopositive for IFN-gamma. At day 11, a proportion of beta cells showed weak immunolabelling for IFN-gamma. During the study period, immunolabelling for IFN-gamma was also observed in a proportion of endothelial cells located in the intra-islet and exocrine regions of Cy and diluent-treated mice. From day 11 onwards, both the cytokines were observed in some of the peri-vascular regions. Our results demonstrate that during Cy-induced diabetes, there is increasing expression of both IL-4 and IFN-gamma in specific immune cells within the inflamed islets in the late prediabetic stage and at onset of diabetes. Further studies are required to correlate our protein immunohistochemical findings with in situ cytokine gene expression and to determine whether there is a clear Th1 cytokine protein bias at clinical onset of diabetes and immediately preceding it.

Two genetic loci regulate T cell-dependent islet inflammation and drive autoimmune diabetes pathogenesis

Insulin-dependent diabetes mellitus (IDDM) is a polygenic disease caused by progressive autoimmune infiltration (insulitis) of the pancreatic islets of Langerhan, culminating in the destruction of insulin-producing beta cells. Genome scans of families with diabetes suggest that multiple loci make incremental contributions to disease susceptibility. However, only the IDDM1 locus is well characterized, at a molecular and functional level, as alleleic variants of the major histocompatibility complex (MHC) class II HLA-DQB1, DRB1, and DPB1 genes that mediate antigen presentation to T cells. In the nonobese diabetic (NOD) mouse model, the Idd1 locus was shown to be the orthologous MHC gene I-Ab. Inheritance of susceptibility alleles at IDDM1/Idd1 is insufficient for disease development in humans and NOD mice. However, the identities and functions of the remaining diabetes loci (Idd2-Idd19 in NOD mice) are largely undefined. A crucial limitation in previous genetic linkage studies of this disease has been reliance on a single complex phenotype-diabetes that displays low penetrance and is of limited utility for high-resolution genetic mapping. Using the NOD model, we have identified an early step in diabetes pathogenesis that behaves as a highly penetrant trait. We report that NOD-derived alleles at both the Idd5 and Idd13 loci regulate a T lymphocyte-dependent progression from a benign to a destructive stage of insulitis. Human chromosomal regions orthologous to the Idd5 and -13 intervals are also linked to diabetes risk, suggesting that conserved genes encoded at these loci are central regulators of disease pathogenesis. These data are the first to reveal a role for individual non-MHC Idd loci in a specific, critical step in diabetes pathogenesis-T cell recruitment to islet lesions driving destructive inflammation. Importantly, identification of intermediate phenotypes in complex disease pathogenesis provides the tools required to progress toward gene identification at these loci.

Oxidative stress as a mechanism of diabetes in diabetic BB prone rats: effect of secoisolariciresinol diglucoside (SDG)

Secoisolariciresinol diglucoside (SDG) isolated from flaxseed has antioxidant activity and has been shown to prevent hypercholesterolemic atherosclerosis. An investigation was made of the effects of SDG on the development of diabetes in diabetic prone BioBreeding rats (BBdp rats), a model of human type I diabetes [insulin dependent diabetes mellitus (IDDM)] to determine if this type of diabetes is due to oxidative stress and if SDG can prevent the incidence of diabetes. The rats were divided into three groups: Group I, BioBreeding normal rats (BBn rats) (n = 10); group II, BBdp untreated (n = 11); and group III, BBdp treated with SDG 22 mg/kg body wt, orally) (n = 14). Oxidative stress was determined by measuring lipid peroxidation product malondialdehyde (MDA) an index of level of reactive oxygen species in blood and pancreas; and pancreatic chemiluminescence (Pancreatic-CL), a measure of antioxidant reserve. Incidence of diabetes was 72.7% in untreated and 21.4% in SDG-treated group as determined by glycosuria and hyperglycemia. SDG prevented the development of diabetes by approximately 71%. Development of diabetes was associated with an increase in serum and pancreatic MDA and a decrease in antioxidant reserve. Prevention in development of diabetes by SDG was associated with a decrease in serum and pancreatic-MDA and an increase in antioxidant reserve. These results suggest that IDDM is mediated through oxidative stress and that SDG prevents the development of diabetes.

Temporal relationship between immune cell influx and the expression of inducible nitric oxide synthase, interleukin-4 and interferon-gamma in pancreatic islets of NOD mice following adoptive transfer of diabetic spleen cells

Beta cell destruction in NOD mice can be accelerated by adoptive transfer of diabetic spleen cells into irradiated adult NOD mice. Here mice receiving diabetic spleen cells were examined at days 0, 7, 14, 21 and at onset of diabetes for the resulting insulitis and the number of intra-islet CD4 and CD8 cells and macrophages. The progression of insulitis and the number of intra-islet CD4 and CD8 cells and macrophages were correlated with the expression and co-localization of inducible nitric oxide synthase, interferon-gamma and interleukin-4 by dual-label light and confocal immunofluorescence microscopy. Diabetes developed in 7/8 mice by 27 days following cell transfer. The insulitis score increased slightly by day 7 but rose sharply at day 14 (p = 0.001) and was maintained until diabetes. The mean number of intra-islet CD4 and CD8 cells and macrophages showed a similar trend to the insulitis scores and were present in almost equal numbers within the islets. Immunolabelling for inducible nitric oxide synthase was observed at day 7 in only some cells of a few islets but increased sharply from day 14. It was restricted to islets with insulitis and was co-localized in selective macrophages. Weak intra-islet interleukin-4 labelling was observed at days 7 and 14 but became more pronounced at day 21 and at onset of diabetes, being present in selective CD4 cells. Intra-islet labelling for interferon-gamma was first observed at day 21, but became more intense at onset of diabetes and was co-localized in a proportion of macrophages. Both cytokines were expressed in islets with advanced insulitis. Interferon-gamma staining was also observed within endothelial cells located in the exocrine pancreas. We conclude that transfer of diabetic spleen cells results in a rapid influx of CD4 and CD8 cells and macrophages within the pancreas of recipient mice. During the period of heightened insulitis, selective immune cells begin to express inducible nitric oxide synthase and the opposing cytokines, interferon-gamma and interleukin-4. Expression of these molecules becomes more pronounced immediately prior to and during the onset of diabetes.

Protective effect of secoisolariciresinol diglucoside against streptozotocin-induced diabetes and its mechanism

OBJECTIVES

Reactive oxygen species (ROS) have been implicated in the development of streptozotocin (STZ)-induced diabetes mellitus. Secoisolariciresinol diglucoside (SDG) isolated from flaxseed is an antioxidant. An investigation was made of the effects of SDG on the development of STZ-induced diabetes in rat, to determine if SDG can prevent/reduce the development of diabetes and if this prevention/reduction is associated with reduction in oxidative stress.

DESIGN AND METHODS

The rats were divided into 4 groups: Group I, Control; Group II, SDG (22 mg/kg body wt, orally) for 24 days; Group III, STZ (80 mg/kg intraperitoneally); Group IV, SDG in the dose similar to Group II three days prior to STZ and 21 days thereafter. Oxidative stress was assessed by measuring serum and pancreatic lipid peroxidation product malondialdehyde (MDA), pancreatic antioxidant reserve (pancreatic-CL) and oxygen free radical producing activity of white blood cells (WBC-CL). A diagnosis of diabetes was made on the basis of glucosuria and was confirmed at the time of sacrifice (21 days after STZ treatment) by the presence of hyperglycemia. At the end of the protocol blood samples were collected for estimation of glucose, MDA and WBC-CL, and pancreas were removed for estimation of MDA and antioxidant reserve.

RESULTS

Incidence of diabetes was 100% in Group III and 25% in Group IV. SDG prevented the development of diabetes by 75%. Development of diabetes was associated with an increase in serum and pancreatic MDA, and in WBC-CL, and a decrease in pancreatic antioxidant reserve. Prevention of diabetes by SDG was associated with a decrease in serum and pancreatic MDA and WBC-CL and an increase in pancreatic antioxidant reserve.

CONCLUSIONS

These results suggest that STZ-induced diabetes is mediated through oxidative stress and that SDG is effective in reducing the STZ-induced diabetes mellitus.

Prevention of autoimmune diabetes by oral administration of syngeneic pancreatic extract to young NOD mice

Oral administration of relevant autoantigens is being considered as a realistic approach for the prevention of several autoimmune diseases. In this study we administered, orally, to young female NOD/Ak mice (diabetes incidence, 40%) and NOD/LtJ mice (diabetes incidence, 70%) whole pancreatic extract on days 19, 20, 21, 22, 23, 26, and 27 and studied its effects on the development of diabetes until day 250. The cumulative incidence of diabetes in both the colonies after pancreatic extract treatment was compared with the incidence after oral administration of syngeneic liver extract or in untreated mice. In the NOD/Ak mice, the incidence of diabetes in the pancreatic extract group was significantly lower (6%; n = 34, p = 0.004) and was delayed compared with 33% in the liver group (n = 34) and 44% in the untreated group (n = 18). Significant protection from diabetes and a delay in its onset also were observed in the NOD/LtJ mice treated with pancreatic extract (16%; n = 19, p = 0.002) compared with those liver extract treated (72%; n = 18) and in untreated mice (60%; n = 22). Pancreatic histology at day 90 from all the study groups showed that the protection from diabetes in the pancreatic-extract group was not associated with reduced insulitis. We speculate that the marked disease protection observed in this study with orally administered pancreatic extract may be associated with the presence of immunoregulatory cells with a predominant Th2 cytokine bias. Our studies may have implications for the prevention of insulin-dependent diabetes mellitus (IDDM) in humans.

Rel B is an early marker of autoimmune islet inflammation in the biobreeding (BB) rat

Because the development of insulitis and diabetes is predictable in Lyp/Lyp congenic BB rats, we have characterized early islet inflammation in these rats to determine the cell subsets involved in the onset of autoimmune insulitis. Pancreas sections from prediabetic Lyp/Lyp, Lyp/+ and +/+ rats were analyzed by immunohistochemistry. We found W3/25+ cells in the exo- and endocrine tissue from all three genotypes, but intraislet insulitis was never found in Lyp/+ or +/+ rats. The onset of massive, intraislet B- and T-cell infiltration in Lyp/Lyp rats was preceded by Rel B+ cells in and around the islets, followed by ED1+ monocytes/macrophages. Rel B+ cells were more frequent in the parafollicular cortex of pancreatic lymph nodes from Lyp/Lyp than from Lyp/+ and +/+ rats. In the Lyp/Lyp thymus, we found significantly increased expression of IL-12p40 messenger RNA (mRNA; p<0.001), located in the Rel B-protein-rich corticomedullary junction. The NF-KB/Rel B complex specifically transactivates genes involved in antigen presentation in dendritic cells. Rel B+ cells in the islets may therefore mark the onset of autoimmune insulitis and antigen-specific activation of autoreactive T cells in the lymph nodes of diabetes prone Lyp/Lyp BB rats. In the thymus, Rel B+ cells may support the Lyp-dependent development of self-reactive thymocytes by activation of cytokine expression.

An immunohistochemical study of macrophage influx and the co-localization of inducible nitric oxide synthase in the pancreas of non-obese diabetic (NOD) mice during disease acceleration with cyclophosphamide

Cyclophosphamide has been used to accelerate and synchronize diabetes in non-obese diabetic (NOD) mice. It was injected to 70-day-old female NOD mice and its effect on the progression of insulitis studied at days 0, 4, 7, 11 and at onset of diabetes. Pancreatic sections were also examined for the influx of CD4 and CD8 T cells and macrophages following immunofluorescence staining. The kinetics of macrophage immunoreactive cells in the exocrine and intra-islet areas were also investigated. Light and confocal microscopy were-employed to examine the expression and co-localization of inducible nitric oxide synthase following dual- and triple-label immunofluorescence histochemistry. After cyclophosphamide administration, the severity of insulitis remained similar from days 0 to 4 but began to rise at day 7 and markedly by day 11 and at onset of diabetes. At these two later stages, the insulitis scores were close to 100% while in age-matched control groups the insulitis scores were considerably lower. Immunohistochemical staining showed increasing numbers of CD4 and CD8 T cell subsets and macrophages within the islets and in exocrine, sinusoidal and peri-vascular regions. At onset of diabetes, several islets contained prominent clusters of macrophage immunoreactive cells. Macrophage influx into the islets increased sharply from day 7 (mean number per islet: 119 +/- 54 SEM), peaked at day 11 (mean number per islet: 228 +/- 42), and then declined at onset of diabetes (mean number per islet: 148 +/- 49). Several cells with immunolabelling for inducible nitric oxide synthase were detectable from day 7 onwards until the onset of diabetes. Dual- and triple-label immunohistochemistry showed that a significant proportion of macrophages and only a few beta cells contained the enzyme. Macrophages positive for the enzyme were located as clusters or occasionally contiguously, in the peri-islet and intra-islet areas but rarely in the exocrine region. Islets with minimal distribution of macrophages in the peri-islet areas were not positive for inducible nitric oxide synthase. Beta cells positive for the enzyme were observed in islets with significant macrophage infiltration in locations close to macrophages. The present results show that cyclophosphamide administration to female NOD mice results in a rapid influx of CD4 and CD8 cells and macrophages. The marked up-regulation of inducible nitric oxide synthase in a selective proportion of macrophages, within the islets, immediately preceding and during the onset of diabetes suggests that nitric oxide released by islet macrophages may be an important molecular mediator of beta cell destruction in this accelerated model of insulin-dependent diabetes mellitus.

In autoimmune diabetes the transition from benign to pernicious insulitis requires an islet cell response to tumor necrosis factor alpha

The islet-infiltrating and disease-causing leukocytes that are a hallmark of insulin-dependent diabetes mellitus produce and respond to a set of cytokine molecules. Of these, interleukin 1beta, tumor necrosis factor (TNF)-alpha, and interferon (IFN)-gamma are perhaps the most important. However, as pleiotropic molecules, they can impact the path leading to beta cell apoptosis and diabetes at multiple points. To understand how these cytokines influence both the formative and effector phases of insulitis, it is critical to determine their effects on the assorted cell types comprising the lesion: the effector T cells, antigen-presenting cells, vascular endothelium, and target islet tissue. Here, we report using nonobese diabetic chimeric mice harboring islets deficient in specific cytokine receptors or cytokine-induced effector molecules to assess how these compartmentalized loss-of-function mutations alter the events leading to diabetes. We found that islets deficient in Fas, IFN-gamma receptor, or inducible nitric oxide synthase had normal diabetes development; however, the specific lack of TNF- alpha receptor 1 (p55) afforded islets a profound protection from disease by altering the ability of islet-reactive, CD4(+) T cells to establish insulitis and subsequently destroy islet beta cells. These results argue that islet cells play a TNF-alpha-dependent role in their own demise.

Cytokine production in NOD mice on prophylactic insulin therapy

We investigated whether cytokines produced primarily by monocytes/macrophages (IL-1alpha), Th1-lymphocytes (IFNgamma), or Th2-lymphocytes (IL-4) are modulated in diabetes-prone NOD mice by insulin treatment as used in prophylaxis studies. The cytokines were measured by ELISA in plasma and in supernatants of spleen cells activated ex vivo by lipopolysaccharide plus phytohemagglutinin. Insulin, 0.25-0.50 IU/day, was given subcutaneously for 8 weeks starting in 4-week-old female mice. The insulin-treated and control NOD mice showed similar weight gains and, by the end of the study, both groups exhibited cell infiltration in about 25% of their islets. IL-1alpha, IFNgamma and IL-4 were generally below detection in plasma of prediabetic animals and controls. Diabetic NOD mice, aged 28-45 weeks, had significantly elevated plasma IL-1alpha: 154+/-39 pg/ml (mean+/-SEM, p<0.0001). While ex vivo activated NOD splenocytes released similar amounts of IL-1alpha, insulin therapy increased the levels from 99+/-17 to 155+/-19 pg/10(6) cells (p<0.05). Supernatants of activated splenocytes from prediabetic NOD mice had lower levels of IL-4 (<15 pg/10(6) cells) compared with those from BALB/c mice (88+/-22 pg/10(6) cells; p<0.01), and this deficiency was partially compensated for when the NOD mice were given insulin (27+/-8; p<0.01). The levels of IFNgamma were comparable and largely unaffected by insulin treatment. Hence, insulin therapy appears to partially normalize an otherwise deficient Th2 response in NOD mice.

Cellular and molecular changes accompanying the progression from insulitis to diabetes

Insulin-dependent diabetes mellitus (IDDM) is not a disease of unbridled destruction. The autoimmune attack on pancreatic beta cells has two distinct stages - insulitis and diabetes - and progression of the former to the latter appears to be highly regulated. Identifying the factors controlling this transition has been difficult because it is a complex process that occurs non-universally and asynchronously. We have overcome these difficulties by coupling a simplified TCR transgenic (tg) model of IDDM and the immunosuppressive drug cyclophosphamide (CY). Young BDC2.5 TCR tg mice show insulitis but not diabetes; CY treatment provoked diabetes in 100% of animals with rapid, highly reproducible kinetics. This allowed a detailed temporal analysis of changes in cellular organization and cytokine gene expression within the lesion. The monokines IL-18, IL-12 and TNF-alpha were pivotal, their induction occurring almost immediately and their coordinate action being required for the onset of aggression. Other cytokines with direct toxicity for beta cells, including IL-1 -beta, IL-6 and IFN-gamma, were subsequently induced; in contrast, there was no cellular or molecular evidence of cell contact-mediated mechanisms of beta cell death.

Thymus-dependent monoclonal antibody-induced protection from transferred diabetes

It is well established that long-term protection from insulin-dependent diabetes mellitus (IDDM) can be afforded to non-obese diabetic (NOD) mice by a short course of non-depleting (nd) anti-CD4 monoclonal antibodies (mAb). Since it is increasingly apparent that the CD8+ T cell plays a prominent role in the development of IDDM, we have investigated the effect of an anti-CD8 mAb (YTS 105) of the same isotype in both spontaneous and induced IDDM in NOD mice. Treatment with YTS 105 for 3 weeks was able to prevent the transfer of IDDM for a long period, and also substantially reduced spontaneous IDDM in female NOD mice. The role of the thymus in tolerance induction by these antibodies was studied. In the adult transfer model, thymectomized NOD mice, unlike their euthymic counterparts, were not protected long-term by treatment with YTS 105, and began to become overtly diabetic shortly after treatment. This was also true when the nd anti-CD4 mAb was used. Protection from spontaneous disease was not affected in the same way by thymectomy. The reasons for the observed effect of the thymus in the transfer model, and the differences between the two models that may explain the contrasting results are discussed.

The APC1 concept of type I diabetes

Type I diabetes appears to be a T cell dependent disease. T cell reactivity is regulated by antigen presenting cells (APCs). In animal models of type I diabetes, abnormal reactivity of APCs, in particular of macrophages, probably is responsible for the progression of islet inflammation from T helper type 2 dependent benign periinsulitis to T helper type I dependent destructive intrainsulitis. The functional state of APCs during preferential stimulation of Th1 reactivities (APC1 state) is characterized by the release of TNFalpha, IL-12 and/or IL-18. The bias towards APC1 reactivity has been found due to defective inhibition via IL-10 and PGE2.

Administration of silica sensitizes lipopolysaccharide responsiveness of murine macrophages but inhibits T and B cell priming by inhibition of antigen presenting function

Macrophages play a key role in natural host defense against infection by a variety of pathogens. In addition, macrophages initiate the development of acquired immunity via antigen processing and presentation. The role of macrophages in resistance to pathogens, the development of autoimmune diseases and the induction of acquired immunity has been studied by treatment of rodents with reagents which are cytotoxic. We have studied the effects of one such reagent, silica, on the function of spleen macrophages and peritoneal exudate cells (PEC). Intraperitoneal administration of silica caused the accumulation of spleen macrophages and neutrophils, reduction in the number of B cells and had a modest effect on T cell abundance. The percentage of CD11b+ PEC was not affected by silica treatment but total PEC recovery was diminished 5-8 fold. Silica treatment did not cause release of TNF-alpha or IL-1-beta but, when stimulated with lipopolysaccharide (LPS) in vitro after silica treatment, PEC or spleen macrophages produced elevated levels of both cytokines compared to controls. In contrast, release of IL-12 from non-LPS treated PEC was stimulated 4-5 fold by silica treatment. In addition, sensitivity to LPS toxicity in vivo was significantly enhanced by silica. The ability of macrophages to present antigen to a T cell clone in vitro was found to be dramatically inhibited by silica treatment, as was the ability to prime antigen-specific T cells and B cells by antigen injection. Collectively these data demonstrate that silica treatment enhances macrophage sensitivity to LPS exposure but inhibits antigen processing and presentation.

Reduced incidence and delayed onset of diabetes in perforin-deficient nonobese diabetic mice

To investigate the role of T cell-mediated, perforin-dependent cytotoxicity in autoimmune diabetes, perforin-deficient mice were backcrossed with the nonobese diabetes mouse strain. It was found that the incidence of spontaneous diabetes over a 1 yr period was reduced from 77% in perforin +/+ control to 16% in perforin-deficient mice. Also, the disease onset was markedly delayed (median onset of 39.5 versus 19 wk) in the latter. Insulitis with infiltration of CD4(+) and CD8(+) T cells occurred similarly in both groups of animals. Lower incidence and delayed disease onset were also evident in perforin-deficient mice when diabetes was induced by cyclophosphamide injection. Thus, perforin-dependent cytotoxicity is a crucial effector mechanism for beta cell elimination by cytotoxic T cells in autoimmune diabetes. However, in the absence of perforin chronic inflammation of the islets can lead to diabetogenic beta cell loss by less efficient secondary effector mechanisms.

Prevention of onset in an insulin-dependent diabetes mellitus model, NOD mice, by oral feeding of Lactobacillus casei

The effect of Lactobacillus casei (LC) on the onset of diabetes in an insulin-dependent diabetes mellitus model, nonobese diabetic (NOD) mice, were examined. From the age of 4 weeks, female NOD mice were fed a diet of either standard laboratory chow (n = 12) or the same chow containing 0.05% weight heat-killed cells of LC (n = 12), and the onset of diabetes was thereafter recorded. The incidence of diabetes in the control group (10/12) was significantly higher than that in the LC-treated group (3/12) (p < 0.01). Pathological analysis in the LC-treated group revealed strong inhibition of the disappearance of insulin-secreting beta cells in Langerhans islets caused by autoimmune disease. The proportion of CD45R+ B-cells in the spleen was increased and that of CD8+ T-cells in spleen cells was decreased in the LC-treated group. Analysis of cytokine production revealed lower interferon-gamma production in the LC-treated group compared to the control group, while the interleukin (IL)-2 production was higher. The levels of IL-4, IL-5, IL-6 and IL-10 in the LC-treated group were somewhat higher than in the control group. Taken together, these findings clearly demonstrated that oral feeding of LC to NOD mice effectively inhibited the occurrence of diabetes and regulated the host immune response.

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.

Primary nonfunction of islet grafts in autoimmune diabetic nonobese diabetic mice is prevented by treatment with interleukin-4 and interleukin-10

In isologous islet transplantation in spontaneously diabetic nonobese (NOD) mice, destruction of the islet graft is caused by recurrence of T helper (Th)1-driven insulitis[fnc,1. We established a model of transplantation in which female NOD recipients were rendered diabetic by a single injection of cyclophosphamide (250 mg/kg). Under these conditions, 500 freshly isolated islets from young NOD mice transplanted under the kidney capsule did not lead to normoglycemia within 3 day after transplantation, but underwent immediate impairment of function. This primary nonfunction was seen in > 80% of the recipients. Treatment of the recipients with the Th2-associated cytokine interleukin (IL)-4 alone did not prevent primary nonfunction, whereas treatment of the recipients with a combination of IL-4 and IL-10 restored immediate function of the grafts. Cytokine treatment did not prevent later rejection of grafts. Histological analysis of the grafts revealed less severely infiltrated islets, with well preserved islet architecture, in only normoglycemic animals treated with IL-4 or with IL-4 and IL-10. Staining for lymphocytes, macrophages, and tumor necrosis factor (TNF)-alpha did not show differences between the groups, but IFN-gamma was markedly less expressed in IL-4- and IL-10-treated grafts. Concomitantly, analysis of animals treated for 8 days after injection of cyclophosphamide, with IL-4 and IL-10, revealed a reduction of IL-12 mRNA in the pancreas. We conclude from these data that primary nonfunction of islet grafts is prevented by treatment of the recipients with a combination of IL-4 and IL-10, via downregulation of Th1 cytokines.

A novel function of islet-derived CD8+T cells in initiating and developing autoimmune insulin-dependent diabetes mellitus in non-obese diabetic (NOD) mice

Accumulated studies revealed that CD4+T cells were initially required for diabetes in NOD mice, whereas interaction of CD4+T/CD8+T cells is not fully understood. To address this question, we established islet-derived CD4+T cells and CD8+T cells from NOD mice. One NOD neonate that received CD4+T cells developed diabetes and insulitis with CD8+T cells. Administration of cyclophosphamide to non-diabetic recipients accelerated the development of diabetes, while none of the mice with anti-CD8 antibody did so. Similarly, it was observed that neonates that received islet-derived CD8+T cells developed diabetes and obvious insulitis mainly with CD4+T cells. Administration of anti-CD4 antibody with transfer of CD8+T cells inhibited insulitis. These results imply that CD8+T cells function as an initial element to recruit CD4+T cells to islets as well as a final effector.

Tolerance induction as a therapeutic strategy for the control of autoimmune endocrine disease in mouse models

This chapter aims to describe ways in which autoimmunity can be prevented or reversed and 'self-tolerance' re-established. To this end we have largely restricted our overview to the two main autoimmune disease models with which we are involved, i.e. IDDM in NOD mice and EAT in H-2k mice although, where appropriate and to demonstrate a particular point, other models are mentioned. The chapter has been divided into sections covering protection afforded by 1) transgenes, 2) autoantigen and 3) by reagents targetting T-cell surface molecules. Where established, the mechanism by which protection or tolerance is achieved is described but where, as in most cases, it is unknown the possibilities are discussed. Investigations using T-cell lines and clones and on islet regeneration which are currently being followed as part of a comprehensive approach to the study of autoimmunity are included as separate sections and their relevance discussed.

Prevention of autoimmunity in nonobese diabetic (NOD) mice by neonatal transfer of allogeneic thymic macrophages

Nonobese diabetic (NOD) mice spontaneously develop insulin dependent diabetes mellitus. The disease results from an autoimmune process which involves mononuclear cells surrounding and eventually infiltrating the pancreatic islets of Langerhans. Macrophages are thought to be the first cells to infiltrate the islets and are actively involved in the disease process because diabetes is prevented if host macrophages are depleted or inactivated. Several lines of evidence also suggest that NOD macrophages are phenotypically and functionally abnormal. In this study, allogeneic (CBA) macrophages derived from the thymus were inoculated into newborn NOD mice and these were followed for more than 250 days. Spontaneous diabetes was significantly reduced in female NOD mice (6% diabetic versus 45% of controls). Insulitis was also significantly reduced in both male and female mice compared to their control counterparts, and in most cases there were virtually no inflammatory cells in the pancreas. Allogeneic skin grafting and mixed leukocyte cultures indicated that the recipients were not tolerant of donor antigens, and donor-derived cells were not detected in the lymphoid tissues by either flow cytometry or immunohistochemistry. The results show that macrophages from diabetes-resistant donors will prevent insulitis and diabetes in most recipients, however, the mechanism for the protection is unclear, but does not appear to be due to long-term tolerance induction.

Beta cell-specific expression of retroviral mRNAs and group-specific antigen and the development of beta cell-specific autoimmunity in non-obese diabetic mice

Non-obese diabetic (NOD) mice spontaneously develop autoimmune type 1 diabetes. Earlier studies have shown that retroviruses appear to be associated with the development of the disease in these animals. This investigation was initiated to determine whether any retroviral genes are specifically expressed in pancreatic beta cells from NOD mice, in contrast to their non-diabetic, parental strain, ICR mice. Host chromosomal DNAs from pancreatic islets, kidneys, hearts, and stomachs of NOD and ICR mice contained an equal amount of A-type retroviral genome (DNA); however, A-type retroviral gag, pol, and env mRNAs were detected in only the pancreatic islets from NOD mice. Furthermore, group-specific retroviral antigen (p73 of A-type--gag gene product) was found by immunofluorescent staining using anti-p73 antibody in only pancreatic beta cells from NOD mice. On the basis of these observations, we suggest that tissue and strain differences in transcription of the retroviral genome and beta cell-specific expression of A-type retroviral group-specific antigen p73 in NOD mice may be involved in the initiation of beta cell-specific autoimmunity leading to type 1 diabetes in these animals.

Prevention of diabetes mellitus in non-obese diabetic mice by Linomide, a novel immunomodulating drug

Oral administration of the synthetic immunomodulating drug quinoline-3-carboxamide (Linomide) in the drinking water to 5-week-old female non-obese diabetic (NOD) mice resulted in complete protection from insulitis and maintenance of normal glucose tolerance for over 40 weeks (impaired glucose tolerance: treated n = 2 of 18; control n = 17 of 18, p < 0.0001). Delayed administration of the drug at 16 weeks resulted in slowing of the progression to diabetes when assessed at 42 weeks (treated with diabetes n = 7 of 25; control with diabetes 25 of 43, p < 0.0234). No gross changes of immune system cell phenotype or function were observed in the Linomide-treated group. Adoptive transfer of spleen and lymph node cells from treated female NOD mice into sub-lethally irradiated male recipients failed to transfer diabetes, whereas a similar transfer of cells obtained from untreated age-matched controls resulted in diabetes in all secondary recipients (diabetes in control group n = 12 of 13; in Linomide group n = 0 of 11, p < 0.0001). Linomide pretreatment of the secondary recipients also inhibited the transfer of diabetes (diabetes in pretreated group n = 2 of 9, control group n = 12 of 13, p < 0.015), as did adoptive co-transfer of cell mixtures obtained from treated female NOD mice, free of diabetes, and from diabetic NOD female mice (diabetes in Linomide group n = 4 of 9; in control group 7 of 7, p < 0.0337).(ABSTRACT TRUNCATED AT 250 WORDS)

Circulating monocytes are activated in newly diagnosed type 1 diabetes mellitus patients

Investigations in the BB rat and the non-obese diabetic (NOD) mouse have provided substantial evidence for the involvement of the monocyte/macrophage system in the development of type 1 diabetes mellitus. However, it is not known whether monocytes play the same role in the pathogenesis of human type 1 diabetes. We investigated this problem in a longitudinal study of 29 recent-onset type 1 diabetes mellitus patients. Monocyte chemotaxis, phagocytosis and superoxide production as well as metabolic and haematological parameters were studied immediately after diagnosis and 6 months later. At diagnosis the patients had activated casein and C5a chemotaxis (casein 70 +/- 9 versus 150 +/- 5 (mean +/- s.e.m.), P < 0.001; C5a 137 +/- 10 versus 158 +/- 5, P < 0.05 (activation immobilizes monocytes, reducing the measured values)), and activated superoxide production (3.6 +/- 0.3 versus 3.0 +/- 0.3, P < 0.05). After 6 months casein chemotaxis (115 +/- 16 versus 150 +/- 5, P < 0.05) and Candida phagocytosis (3.3 +/- 0.1 versus 2.8 +/- 0.2, P < 0.001) were still activated. There was no correlation with other clinical or paraclinical parameters. We conclude that the circulating monocytes in newly diagnosed type 1 diabetes patients are activated. It is reasonable to expect that monocytes at the local site of inflammation in pancreas are even further activated. This could play a pathogenic role in beta cell destruction.

Intercellular adhesion molecule-1 (ICAM-1) expression in the islets of the non-obese diabetic and low-dose streptozocin-treated mouse

The expression of intercellular adhesion molecule-1 (ICAM-1) was studied in 8-week-old non-obese diabetic (NOD) mice and low-dose streptozocin-treated (LDS) mice. ICAM-1 expression in NOD mice was observed at the islet periphery, corresponding to the peri-islet venular network, within the islet and on scattered elements along septa of the exocrine portion of the pancreas. Image analysis demonstrated that LDS-treated animals had less ICAM-1 immunoreactivity within and around the islets compared to NOD mice. At the ultrastructural level the peri-islet vessels were found to be filled with mononuclear elements. Moreover, endothelial cells showed signs of activation, and margination of monocytes and polymorphonuclear leukocytes was observed.