Insulitis In Type Research Articles

Interferons are key cytokines acting on pancreatic islets in type 1 diabetes.

The proinflammatory cytokines IFN-α, IFN-γ, IL-1β and TNF-α may contribute to innate and adaptive immune responses during insulitis in type 1 diabetes and therefore represent attractive therapeutic targets to protect beta cells. However, the specific role of each of these cytokines individually on pancreatic beta cells remains unknown. We used deep RNA-seq analysis, followed by extensive confirmation experiments based on reverse transcription-quantitative PCR (RT-qPCR), western blot, histology and use of siRNAs, to characterise the response of human pancreatic beta cells to each cytokine individually and compared the signatures obtained with those present in islets of individuals affected by type 1 diabetes. IFN-α and IFN-γ had a greater impact on the beta cell transcriptome when compared with IL-1β and TNF-α. The IFN-induced gene signatures have a strong correlation with those observed in beta cells from individuals with type 1 diabetes, and the level of expression of specific IFN-stimulated genes is positively correlated with proteins present in islets of these individuals, regulating beta cell responses to 'danger signals' such as viral infections. Zinc finger NFX1-type containing 1 (ZNFX1), a double-stranded RNA sensor, was identified as highly induced by IFNs and shown to play a key role in the antiviral response in beta cells. These data suggest that IFN-α and IFN-γ are key cytokines at the islet level in human type 1 diabetes, contributing to the triggering and amplification of autoimmunity.

The Putative Adverse Effects of Bisphenol A on Autoimmune Diseases.

Bisphenol A (BPA) is a monomer that is widely used in the manufacturing of polycarbonate plastics (including storage plastics and baby bottles) and is considered to be one of the most widely used synthetic compounds in the manufacturing industry. Exposure to BPA mainly occurs after oral ingestion and results from leaks into food and water from plastic containers. According to epidemiological data, exposure is widespread and estimated to occur in 90% of individuals. BPA exhibits pleiotropic and estrogen-like effects; thus, it is considered an endocrine-disrupting chemical. A growing body of evidence highlights the role of BPA in modulating immune responses and signaling pathways, which results in a proinflammatory response by enhancing the differential polarization of immune cells and cytokine production profile to one that is consistent with proinflammation. Indeed, epidemiological studies have uncovered associations between several autoimmune diseases and BPA exposure. Data from animal models provided consistent evidence, which highlighted the role of BPA in the pathogenesis, exacerbation, and perpetuation of various autoimmune phenomena including neuroinflammation in the context of multiple sclerosis, colitis in inflammatory bowel disease, nephritis in systemic lupus erythematosus, and insulitis in type 1 diabetes mellitus. Owing to the widespread use of BPA and its effects on immune system dysregulation, a call for careful assessment of patients' risks and public health measures are needed to limit exposure and subsequent deleterious effects. The purpose of this study is to explore the autoimmune triggering mechanisms and present the current literature supporting the role of BPA in the pathogenesis of autoimmune diseases.

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.

Efek asam alfa lipoat terhadap insulitis pada tikus diabetes melitus tipe 2

Effect of alpha lipoic acid on insulitis in type 2 diabetic ratBackground: The damaging of β cell causes hyperglycemia. Β cell damaged as insulitis happens because of the increase of free radical and the decrease of endogen antioxidant that caused oxidative stress.Objective: The goal of this research was to find out the effect of alpha lipoic acid (ALA) on pancreas Langerhans island’s histopathology in type 2 diabetic rats.Methods: This was an experimental laboratory study with post test only design. Fifteen adult male rats of Wistar strain were segregated into three groups (n=5) labeled as control, type 2 diabetes (DM), and DM+ALA. The experiment was designed for 3 weeks. The measured parameter was insulitis level on pancreas Langerhans island of groups labeled.Results: The statistical test result showed there was the significant difference between control and type 2 diabetes group (p=0,005), but there was no significant difference between DM and DM+ ALA group (p=0,549).Conclusions: Although not statistically significant, giving ALA 60 mg/kg body weight for 3 weeks decreased the degree of insulitis in diabetic rats.

No acute pancreatitis but reduced exocrine pancreatic function at diagnosis of type 1 diabetes in children

Insulitis in type 1 diabetes (T1D) seems to be both mild and rather rare, and immune cells are found also in the exocrine pancreas, which often is small. We wanted to see whether clinical pancreatitis at diagnosis of T1D in children is a commonly missed diagnosis. Clinical symptoms suggesting pancreatitis were investigated in a retrospective case-control study in 191 newly diagnosed T1D patients (105 boys, 86 girls) with age at onset 0.2 to 18 (mean = 10.05, SD = 4.71, median = 10.36) years, 23/191 (12%) with ketoacidosis at diagnosis. Blood samples were taken on day 4 and stored at -20°C until analyses for P-amylase and C-reactive protein (CRP), and compared with 100 age-matched healthy control children with plasma stored at -80°C, and 46 with plasma stored at -20°C. At diagnosis, 23/191 (12%) patients had mild transient abdominal pain, 2/23 with obstipation, and 5/23 also transient mild diarrhea. Five of 23 patients with abdominal pain had pH < 7.30. None had clinical acute pancreatitis. One diabetic patient had P-amylase 1.3 μkat/L (normal range = 0.15-1.1 μkat/L), while 62/191 (32.4%) diabetic children had P-amylase below the normal range. None (0/100) of the -80-controls and only 1/46 (0.14 μkat/L) of the -20-controls had the P-amylase level in the normal range. Five diabetic children, but no controls, had increased CRP, but not related to P-amylase or to gastrointestinal symptoms. Acute pancreatitis seems to be very rare at diagnosis of T1D, but decreased exocrine function quite common, which supports that T1D sometimes is part of a more generalized pancreatic disorder.

Pancreatic Beta Cell Death: Novel Potential Mechanisms in Diabetes Therapy.

Purpose of ReviewDescribing the diverse molecular mechanisms (particularly immunological) involved in the death of the pancreatic beta cell in type 1 and type 2 diabetes mellitus. Recent FindingsBeta cell death is the final event in a series of mechanisms that, up to date, have not been entirely clarified; it represents the pathophysiological mechanism in the natural history of diabetes mellitus. These mechanisms are not limited to an apoptotic process only, which is characteristic of the immune-mediated insulitis in type 1 diabetes mellitus. They also include the action of proinflammatory cytokines, the production of reactive oxygen species, DNA fragmentation (typical of necroptosis in type 1 diabetic patients), excessive production of islet amyloid polypeptide with the consequent endoplasmic reticulum stress, disruption in autophagy mechanisms, and protein complex formation, such as the inflammasome, capable of increasing oxidative stress produced by mitochondrial damage. SummaryNecroptosis, autophagy, and pyroptosis are molecular mechanisms that modulate the survival of the pancreatic beta cell, demonstrating the importance of the immune system in glucolipotoxicity processes and the potential role for immunometabolism as another component of what once known as the “ominous octet.”

Hyaluronan content governs tissue stiffness in pancreatic islet inflammation

We have identified a novel role for hyaluronan (HA), an extracellular matrix polymer, in governing the mechanical properties of inflamed tissues. We recently reported that insulitis in type 1 diabetes of mice and humans is preceded by intraislet accumulation of HA, a highly hygroscopic polymer. Using the double transgenic DO11.10 × RIPmOVA (DORmO) mouse model of type 1 diabetes, we asked whether autoimmune insulitis was associated with changes in the stiffness of islets. To measure islet stiffness, we used atomic force microscopy (AFM) and developed a novel "bed of nails"-like approach that uses quartz glass nanopillars to anchor islets, solving a long-standing problem of keeping tissue-scale objects immobilized while performing AFM. We measured stiffness via AFM nanoindentation with a spherical indenter and found that insulitis made islets mechanically soft compared with controls. Conversely, treatment with 4-methylumbelliferone, a small-molecule inhibitor of HA synthesis, reduced HA accumulation, diminished swelling, and restored basal tissue stiffness. These results indicate that HA content governs the mechanical properties of islets. In hydrogels with variable HA content, we confirmed that increased HA leads to mechanically softer hydrogels, consistent with our model. In light of recent reports that the insulin production of islets is mechanosensitive, these findings open up an exciting new avenue of research into the fundamental mechanisms by which inflammation impacts local cellular responses.

Neutralization Versus Reinforcement of Proinflammatory Cytokines to Arrest Autoimmunity in Type 1 Diabetes.

As physiological pathways of intercellular communication produced by all cells, cytokines are involved in the pathogenesis of inflammatory insulitis as well as pivotal mediators of immune homeostasis. Proinflammatory cytokines including interleukins, interferons, transforming growth factor-β, tumor necrosis factor-α, and nitric oxide promote destructive insulitis in type 1 diabetes through amplification of the autoimmune reaction, direct toxicity to β-cells, and sensitization of islets to apoptosis. The concept that neutralization of cytokines may be of therapeutic benefit has been tested in few clinical studies, which fell short of inducing sustained remission or achieving disease arrest. Therapeutic failure is explained by the redundant activities of individual cytokines and their combinations, which are rather dispensable in the process of destructive insulitis because other cytolytic pathways efficiently compensate their deficiency. Proinflammatory cytokines are less redundant in regulation of the inflammatory reaction, displaying protective effects through restriction of effector cell activity, reinforcement of suppressor cell function, and participation in islet recovery from injury. Our analysis suggests that the role of cytokines in immune homeostasis overrides their contribution to β-cell death and may be used as potent immunomodulatory agents for therapeutic purposes rather than neutralized.

Rodent versus human insulitis: why the huge disconnect?

The purpose of this article is to summarize recent developments in the histopathology of recent-onset type 1 diabetes. Insulitis is considered to be the defining lesion in young type 1 diabetic patients, and insight into its pathogenic mechanism is crucial for the development of effective new therapies. The present overview highlights some recent developments including an international consensus guideline for the diagnosis of insulitis in type 1 diabetic patients, immunophenotyping of the insulitic lesions, evidence for a heterogeneity of the disease process and a discussion on the differences and similarities between insulitis in patients and in rodent models of the disease. We have reviewed recent data, published over the last year, on the nature and mechanism of insulitis in both patients and the nonobese diabetic mouse model.

Hematopoietic Transplants for Disease Suppression and Cure in Type 1 Diabetes

Recent clinical studies have demonstrated the capacity of immunosuppressive therapy to delay progression of inflammatory insulitis in type 1 diabetes (T1D). The procedure includes depletion of pathogenic cells by immunosuppressive therapy and support of recovery by reinfusion of autologous hematopoietic progenitors. The short-term outcome of these clinical transplants is similar to the predictions drawn from NOD mice: debulking of diabetogenic cells is ineffectively achieved by immunosuppressive therapy, and resetting of immune homeostasis does not restrain autoimmunity. Murine models indicate that allogeneic transplants are potentially curative, through restored mechanisms of negative regulation that are effective in continuous and indefinite suppression of autoimmunity.

Insulinoma may mask the existence of Type 1 diabetes

Insulinoma is a tumour of insulin-producing cells of the pancreas and is known to be one of the causes of hypoglycaemia. Usually, appropriate removal of the insulinoma results in normalization of blood glucose levels. However, we found novel cases of insulinoma, in which hyperglycaemia developed soon after resection of the insulinoma. We encountered two patients with repeated hypoglycaemia caused by insulinoma. Following removal of the insulinoma, unanticipated hyperglycaemia was observed in both patients. Thereafter, their blood tests revealed low levels of serum C-peptide and high titres of anti-glutamic acid decarboxylase antibody, indicating concomitant Type 1 diabetes. Indeed, histological examination of the resected specimen revealed that one patient showed insulitis in non-tumorous pancreatic tissue in which β-cells had already disappeared. Moreover, inflammatory cells infiltrated the insulinoma, as if it were insulitis of Type 1 diabetes, suggesting the existence of anti-islet autoimmunity. These are first cases of insulinoma associated with underlying Type 1 diabetes. Physicians should be aware of the possibility that insulinoma may mask Type 1 diabetes, and measurement of anti-islet autoantibodies may be helpful to find underlying Type 1 diabetes, such as in these cases. It is pathologically interesting that the immune cell infiltration into insulinoma may be suggestive of anti-islet autoimmunity.

Effector and Naturally Occurring Regulatory T Cells Display No Abnormalities in Activation Induced Cell Death in NOD Mice

BackgroundDisturbed peripheral negative regulation might contribute to evolution of autoimmune insulitis in type 1 diabetes. This study evaluates the sensitivity of naïve/effector (Teff) and regulatory T cells (Treg) to activation-induced cell death mediated by Fas cross-linking in NOD and wild-type mice.Principal FindingsBoth effector (CD25−, FoxP3−) and suppressor (CD25+, FoxP3+) CD4+ T cells are negatively regulated by Fas cross-linking in mixed splenocyte populations of NOD, wild type mice and FoxP3-GFP tranegenes. Proliferation rates and sensitivity to Fas cross-linking are dissociated in Treg cells: fast cycling induced by IL-2 and CD3/CD28 stimulation improve Treg resistance to Fas-ligand (FasL) in both strains. The effector and suppressor CD4+ subsets display balanced sensitivity to negative regulation under baseline conditions, IL-2 and CD3/CD28 stimulation, indicating that stimulation does not perturb immune homeostasis in NOD mice. Effective autocrine apoptosis of diabetogenic cells was evident from delayed onset and reduced incidence of adoptive disease transfer into NOD.SCID by CD4+CD25− T cells decorated with FasL protein. Treg resistant to Fas-mediated apoptosis retain suppressive activity in vitro. The only detectable differential response was reduced Teff proliferation and upregulation of CD25 following CD3-activation in NOD mice.ConclusionThese data document negative regulation of effector and suppressor cells by Fas cross-linking and dissociation between sensitivity to apoptosis and proliferation in stimulated Treg. There is no evidence that perturbed AICD in NOD mice initiates or promotes autoimmune insulitis.

Anti-inflammatory action of exendin-4 in human islets is enhanced by phosphodiesterase inhibitors: potential therapeutic benefits in diabetic patients

Exendin-4, a glucagon-like peptide-1 (GLP-1) analogue, is reported to have modest anti-inflammatory effects in addition to that of improving beta cell survival. We therefore sought to determine whether exendin-4 decreases expression of the gene encoding chemokine (C-X-C motif) ligand (CXCL)10, which plays a role in initiating insulitis in type 1 diabetes. The expression of CXCL10 in human islets was determined at the mRNA level by real-time RT-PCR analysis and at the protein level by western blotting. The level of CXCL10 in culture medium was measured by ELISA. Pathway-specific gene expression profiling was carried out to determine the expression of a panel of genes encoding chemokines and cytokines in human islets exposed to cytokines. IFN-γ induced expression of CXCL10 through activation of signal transducer and activator of transcription-1 (STAT-1). A combination of cytokines (IL-1β, TNF-α and IFN-γ) showed strong synergy in the induction of numerous chemokines and cytokines through nuclear factor kappa B and STAT-1. Exendin-4 suppressed basal expression of several inflammatory mediators. In combination with phosphodiesterase inhibitors, exendin-4 also decreased IFN-γ-induced CXCL10 expression in human islets and in MIN6 cells (a mouse beta cell line), and its secretion into the culture medium. Exendin-4 action was mimicked by forskolin, an activator of adenylyl cyclase, and by dibutyryl cyclic AMP. Protein kinase A was not involved in mediating exendin-4 action on CXCL10. The mechanism of exendin-4's anti-inflammatory action involved decreases in STAT-1 levels. These findings suggest that the GLP-1-cyclic AMP pathway decreases islet inflammation in addition to its known effects on beta cell survival.

Cytokine-mediated induction of anti-apoptotic genes that are linked to nuclear factor kappa-B (NF-κB) signalling in human islets and in a mouse beta cell line

The destruction of pancreatic beta cells leading to type 1 diabetes in humans is thought to occur mainly through apoptosis and necrosis induced by activated macrophages and T cells, and in which secreted cytokines play a significant role. The transcription factor nuclear factor kappa-B (NF-kappaB) plays an important role in mediating the apoptotic action of cytokines in beta cells. We therefore sought to determine the changes in expression of genes modulated by NF-kappaB in human islets exposed to a combination of IL1beta, TNF-alpha and IFN-gamma. Microarray and gene set enrichment analysis were performed to investigate the global response of gene expression and pathways modulated in cultured human islets exposed to cytokines. Validation of a panel of NF-kappaB-regulated genes was performed by quantitative RT-PCR. The mechanism of induction of BIRC3 by cytokines was examined by transient transfection of BIRC3 promoter constructs linked to a luciferase gene in MIN6 cells, a mouse beta cell line. Enrichment of several metabolic and signalling pathways was observed in cytokine-treated human islets. In addition to the upregulation of known pro-apoptotic genes, a number of anti-apoptotic genes including BIRC3, BCL2A1, TNFAIP3, CFLAR and TRAF1 were induced by cytokines through NF-kappaB. Significant synergy between the cytokines was observed in NF-kappaB-mediated induction of the promoter of BIRC3 in MIN6 cells. These findings suggest that, via NF-kappaB activation, cytokines induce a concurrent anti-apoptotic pathway that may be critical for preserving islet integrity and viability during the progression of insulitis in type 1 diabetes.

Insulitis in type 2 diabetes

Islets of patients with type 2 diabetes have the feature of an inflammatory process reflected by the presence of cytokines, immune cells, beta-cell apoptosis, amyloid deposits and fibrosis. Indeed, beta-cells from patients with type 2 diabetes display inflammatory markers, including increased interleukin (IL)-1 beta expression. Furthermore, increased islet-associated macrophages are observed in human type 2 diabetic patients and in most animal models of diabetes. Importantly, increased numbers of macrophages are detectable very early in high fat-fed mice islets, before the onset of diabetes. These immune cells are most likely attracted by islet-derived chemokines, produced in response to metabolic stress, and under the control of IL-1 beta. It follows that modulation of intra-islet inflammatory mediators, in particular IL-1 beta, may prevent insulitis in type 2 diabetes and therefore presents itself as a possible causal therapy with disease-modifying potential.

Cytokine signalling in the β-cell: a dual role for IFNγ

IFNgamma (interferon gamma), a cytokine typically secreted by infiltrating immune cells in insulitis in Type 1 diabetes, is by itself not detrimental to beta-cells, but, together with other cytokines, such as IL-1beta (interleukin 1beta) and TNFalpha (tumour necrosis factor alpha), or dsRNA (double-stranded RNA), it induces beta-cell apoptosis. The complex gene and protein networks that are altered by the combination of cytokines clearly point towards synergisms between these agents. IFNgamma acts mostly via JAK (Janus kinase) activation, with the transcription factors STAT-1 (signal transducer and activator of transcription-1) and IRF-1 (IFNgamma regulatory factor-1) playing a central role in the downstream pathway. The study of mice with a disruption of these transcription factors has revealed a possible dual role for IFNgamma in beta-cell destruction by cytokines or dsRNA. We demonstrated that the absence of STAT-1 from beta-cells completely protects against IFNgamma+IL-1beta- and IFNgamma+dsRNA-mediated beta-cell death in vitro, whereas absence of IRF-1 does not prevent cytokine-induced beta-cell apoptosis. In vivo, a lack of the IRF-1 gene in pancreatic islets even promotes low-dose streptozotocin-induced diabetes, whereas lack of STAT-1 confers resistance against beta-cell death following low-dose streptozotocin-induced diabetes. Additionally, IRF-1(-/-) islets are more sensitive to PNF (primary islet non-function) after transplantation in spontaneously diabetic NOD (non-obese diabetic) mice, whereas STAT-1(-/-) islets are fully protected. Moreover, proteomic analysis of beta-cells exposed to IFNgamma or IFNgamma+IL-1beta confirms that very different pathways are activated by IFNgamma alone compared with the combination. We conclude that IFNgamma may play a dual role in immune-induced beta-cell destruction. Transcription factors drive this dual role, with STAT-1 driving beta-cell destruction and IRF-1 possibly playing a role in up-regulation of protective pathways induced by IFNgamma.

From Endothelial to &amp;#946; Cells: Insights into Pancreatic Islet Microendothelium

The microvasculature is a key interface between blood and tissues and participates in numerous pathophysiological processes. The heterogeneity of microvascular endothelial cells derived from different organs, suggests that these cells have specialised functions at different anatomical sites. Pancreatic islet microcirculation exhibits distinctive features, with an islet capillary network showing five times higher density than the capillary network of the exocrine counterpart and high permeability. Moreover, the islet microvascular endothelial cells show about 10 times more fenestrations than those of the exocrine tissue. In an interdependent physical and functional relationship with beta cells, islet endothelial cells are involved not only in the delivery of oxygen and nutrients to endocrine cells, but induce insulin gene expression during islet development, affect adult beta cell function, promote beta cell proliferation, and produce a number of vasoactive, angiogenic substances and growth factors. Specific markers of islet microvasculature are alpha-1 proteinase inhibitor and nephrin, a highly specific barrier protein with adhesion and signalling function. The islet microendothelium also appears to have a role in fine-tuning blood glucose sensing and regulation, and to behave as an active "gatekeeper" in the control of leukocyte recruitment into the islets, adopting an activated phenotype during autoimmune insulitis in type 1 diabetes. This dense vasculature is therefore likely to play a role in the physiology as well as in the disease of the pancreatic islets. In this review we will describe the phenotypic and functional characteristics of islet microendothelium and its possible involvement in type 1 and 2 diabetes, and islet revascularisation in transplantation settings.

Human pancreatic islet endothelial cells express coxsackievirus and adenovirus receptor and are activated by coxsackie B virus infection

Enteroviruses, such as the coxsackievirus (CV) group, have been linked to the induction of inflammatory and autoimmune diseases. Virus tropism and tissue access are modulated by endothelial cells. To examine the susceptibility of microvascular endothelial cells (MECs) derived from pancreatic islets to infection with CV group B (CVB), purified cultured human islet MECs were infected with CVB-4 strain, and the immunological phenotype of the infected cells was analyzed. CVB-4 persistently infected the islet MECs, which expressed the CV receptors human coxsackievirus and adenovirus receptor (HCAR) and decay accelerating factor (DAF) and maintained EC characteristics, without overt cytopathic effects. CVB-4 infection transiently up-regulated expression of the adhesion molecules ICAM-1 and VCAM-1 and increased production of the proinflammatory cytokines IL-1beta and IL-6, and chemokines IL-8 and lymphotactin, as well as IFN-alpha. Mononuclear cell adhesion to CVB infected monolayers was increased, compared to uninfected monolayers. Moreover, infection up-regulated the viral receptors HCAR and DAF and coreceptor alpha(v)beta3 integrin on islet MECs, while down-regulating expression of HCAR on human aortic endothelial cells, indicating potential tissue-specific influence on the pathological outcome of infection. These results provide evidence that islet MECs are natural targets and reservoirs for persistent CVB infection resulting in acute endothelial cell activation by virus, which may contribute to selective recruitment of subsets of leukocytes during inflammatory immune responses, such as insulitis in type 1 diabetes.

Immunolocalization of Monocyte Chemoattractant Protein‐1 in Islets of NOD Mice during Cyclophosphamide Administration

The molecular processes that initiate insulitis in type 1 diabetes remain unclear. Chemokines, such as monocyte chemoattractant protein-1 (MCP-1), mediate chemotaxis and leukocyte migration to inflammatory sites. Although MCP-1 mRNA has been shown in islets isolated from NOD mice at 2 weeks of age and at later stages, the cellular sources of this chemokine, at the protein level, and its role in insulitis are unclear. The aims of the present study were to employ immunohistochemical techniques to examine the expression of MCP-1 and quantify its cellular sources in islets of NOD mice both after cyclophosphamide (Cy) administration and in spontaneous diabetes. Tissues were examined at days 1 (=day 73, first day of Cy), 4, 7, 11, and 14 and in age-matched control NOD mice. Pancreatic sections from NOD mice without Cy administration were also studied between days 21-65 and at onset of diabetes and from adult CD-1 mice. In the Cy group, a small number of peri-islet macrophages were immunopositive for MCP-1 at day 1 whereas at day 4, the number declined but increased subsequently at day 7. In the same group, it increased markedly at days 11 and 14 compared with age-matched control NOD mice. In young NOD mice, MCP-1 was present in selective macrophages in islets with early insulitis (day 45) but was absent at diabetes onset. MCP-1 was undetectable in beta cells and in most T cells. Islets from adult CD-1 mice did not show immunostaining for MCP-1. We conclude that MCP-1 is expressed in a proportion of islet and exocrine macrophages. This expression increases during the later stages of Cy-induced diabetes. Thus, MCP-1 positive macrophages that migrate to the islet periphery during the early stages of Cy-induced diabetes and preceding spontaneous diabetes may augment insulitis by further attracting macrophages and T cells.

Transient Chemokine Receptor Blockade does not Prevent, but may Accelerate Type 1 Diabetes in Prediabetic NOD Mice

The influx of autoreactive lymphocytes into the site of an autoimmune inflammation is mediated by certain chemokines. Autoimmune insulitis in type 1 diabetes is viewed as the result of destructive Th-1-cells and their corresponding antigen-presenting cells infiltrating the pancreatic islets. Blocking the chemokine receptors that mediate a Th-1-reaction has been shown to reduce autoimmunity in other experimental autoimmune disorders. We used the NOD mouse model to investigate the potency of anti-CCR2 and anti-CCR5 antibodies to inhibit the influx of Th-1-cells into the pancreatic islets, thus preventing diabetes onset. Eleven-week-old female NOD mice were treated with 500 microg of a monoclonal anti-CCR5 or anti-CCR2 or an isotype control antibody every third day over two weeks. We did not observe any preventive effect in either treatment group, but accelerated diabetes onset in the anti-CCR5 treated group. The number of autoantigen-specific Th-1-cells detected in the two treated groups was not reduced, but increased in the anti-CCR5 group. Redundancy within the chemokine system may account for this lack of prevention, or the intervention may have come too late in the disease process. Furthermore, blocking Th-1 chemokine receptors in the late autoimmune process may also inhibit regulatory T-cells, thus accelerating rather than preventing the disease.