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International audience; Administration of low-dose interleukin-2 (IL-2) alone or combined with rapamycin (RAPA) prevents hyperglycemia in NOD mice. Also, low-dose IL-2 cures recent-onset type 1 diabetes (T1D) in NOD mice, partially by boosting pancreatic regulatory T cells (Treg cells). These approaches are currently being evaluated in humans. Our objective was to study the effect of higher IL-2 doses (250,000-500,000 IU daily) as well as low-dose IL-2 (25,000 IU daily) and RAPA (1 mg/kg daily) (RAPA/IL-2) combination. We show that, despite further boosting of Treg cells, high doses of IL-2 rapidly precipitated T1D in prediabetic female and male mice and increased myeloid cells in the pancreas. Also, we observed that RAPA counteracted IL-2 effects on Treg cells, failed to control IL-2-boosted NK cells, and broke IL-2-induced tolerance in a reversible way. Notably, the RAPA/IL-2 combination failure to cure T1D was associated with an unexpected deleterious effect on glucose homeostasis at multiple levels, including β-cell division, glucose tolerance, and liver glucose metabolism. Our data help to understand the therapeutic limitations of IL-2 alone or RAPA/IL-2 combination and could lead to the design of improved therapies for T1D.

Interleukin-2 (IL-2) is a critical cytokine for the homeostasis and function of forkhead box p3–expressing regulatory T cells (Foxp3+Tregs). Dysregulation of the IL-2–IL-2 receptor axis is associated with aberrant Foxp3+Tregs and T cell–mediated autoimmune diseases such as type 1 diabetes. Treatment with recombinant IL-2 has been reported to enhance Foxp3+Tregs and suppress different models of autoimmunity. However, efficacy of IL-2 therapy is dependent on achieving sufficient levels of IL-2 to boost tissue-resident Foxp3+Tregs while avoiding the potential toxic effects of systemic IL-2. With this in mind, adeno-associated virus (AAV) vector gene delivery was used to localize IL-2 expression to the islets of NOD mice. Injection of a double-stranded AAV vector encoding IL-2 driven by a mouse insulin promoter (dsAAVmIP-IL2) increased Foxp3+Tregs in the islets but not the draining pancreatic lymph nodes. Islet Foxp3+Tregs in dsAAVmIP-IL2–treated NOD mice exhibited enhanced fitness marked by increased expression of Bcl-2, proliferation, and suppressor function. In contrast, ectopic IL-2 had no significant effect on conventional islet-infiltrating effector T cells. Notably, β-cell–specific IL-2 expression suppressed late preclinical type 1 diabetes in NOD mice. Collectively, these findings demonstrate that β-cell–specific IL-2 expands an islet-resident Foxp3+Tregs pool that effectively suppresses ongoing type 1 diabetes long term.

Peritransplant infusion of apoptotic donor splenocytes cross-linked with ethylene carbodiimide (ECDI-SPs) has been demonstrated to effectively induce allogeneic donor-specific tolerance. The objective of the current study is to determine the effectiveness and additional requirements for tolerance induction for xenogeneic islet transplantation using donor ECDI-SPs. In a rat-to-mouse xenogeneic islet transplant model, we show that rat ECDI-SPs alone significantly prolonged islet xenograft survival but failed to induce tolerance. In contrast to allogeneic donor ECDI-SPs, xenogeneic donor ECDI-SPs induced production of xenodonor-specific antibodies partially responsible for the eventual islet xenograft rejection. Consequently, depletion of B cells prior to infusions of rat ECDI-SPs effectively prevented such antibody production and led to the indefinite survival of rat islet xenografts. In addition to controlling antibody responses, transient B-cell depletion combined with ECDI-SPs synergistically suppressed xenodonor-specific T-cell priming as well as memory T-cell generation. Reciprocally, after initial depletion, the recovered B cells in long-term tolerized mice exhibited xenodonor-specific hyporesponsiveness. We conclude that transient B-cell depletion combined with donor ECDI-SPs is a robust strategy for induction of xenodonor-specific T- and B-cell tolerance. This combinatorial therapy may be a promising strategy for tolerance induction for clinical xenogeneic islet transplantation.

The dysregulation of receptor tyrosine kinases (RTKs) in multiple cell types during chronic inflammation is indicative of their pathogenic role in autoimmune diseases. Among the many RTKs, vascular endothelial growth factor receptor (VEGFR) stands out for its multiple effects on immunity, vascularization, and cell migration. Herein, we examined whether VEGFR participated in the pathogenesis of type 1 diabetes (T1D) in nonobese diabetic (NOD) mice. We found that RTK inhibitors (RTKIs) and VEGF or VEGFR-2 antibodies reversed diabetes when administered at the onset of hyperglycemia. Increased VEGF expression promoted islet vascular remodeling in NOD mice, and inhibition of VEGFR activity with RTKIs abrogated the increase in islet vascularity, impairing T-cell migration into the islet and improving glucose control. Metabolic studies confirmed that RTKIs worked by preserving islet function, as treated mice had improved glucose tolerance without affecting insulin sensitivity. Finally, examination of human pancreata from patients with T1D revealed that VEGFR-2 was confined to the islet vascularity, which was increased in inflamed islets. Collectively, this work reveals a previously unappreciated role for VEGFR-2 signaling in the pathogenesis of T1D by controlling T-cell accessibility to the pancreatic islets and highlights a novel application of VEGFR-2 antagonists for the therapeutic treatment of T1D. © 2013 by the American Diabetes Association. Readers may use this article as long as the work is properly cited, the use is educational and not for profit, and the work is not altered.

Type 1 diabetes is characterized by autoimmune destruction of pancreatic β-cells in genetically susceptible individuals. Triggers of islet autoimmunity, time course, and the precise mechanisms responsible for the progressive β-cell failure are not completely understood. The recent escalation of obesity in affluent countries has been suggested to contribute to the increased incidence of type 1 diabetes. Understanding the link between metabolism and immune tolerance could lead to the identification of new markers for the monitoring of disease onset and progression. We studied several immune cell subsets and factors with high metabolic impact as markers associated with disease progression in high-risk subjects and type 1 diabetic patients at onset and at 12 and 24 months after diagnosis. A multiple correlation matrix among different parameters was evaluated statistically and assessed visually on two-dimensional graphs. Markers to predict residual β-cell function up to 1 year after diagnosis were identified in multivariate logistic regression models. The meta-immunological profile changed significantly over time in patients, and a specific signature that was associated with worsening disease was identified. A multivariate logistic regression model measuring age, BMI, fasting C-peptide, number of circulating CD3+CD16+CD56+ cells, and the percentage of CD1c+CD19−CD14−CD303− type 1 myeloid dendritic cells at disease onset had a significant predictive value. The identification of a specific meta-immunological profile associated with disease status may contribute to our understanding of the basis of diabetes progression.

Human type 1 diabetes (T1D) is an autoimmune disease associated with major histocompatibility complex polymorphisms, β-cell autoantibodies, and autoreactive T cells. However, there is increasing evidence that innate cells may also play critical roles in T1D. We aimed to monitor peripheral immune cells in early stages of T1D (i.e., in healthy autoantibody-positive subjects) and in more advanced phases of the disease (i.e., at disease onset and years after diagnosis). We found a mild but significant and reproducible peripheral neutropenia that both precedes and accompanies the onset of T1D. This reduction was not due to peripheral neutrophil cell death, impaired differentiation, or the presence of anti-neutrophil antibodies. Neutrophils were observed by electron microscopy and immunohistochemical analysis in the exocrine pancreas of multiorgan donors with T1D (both at onset and at later stages of the disease) and not in that of multiorgan donors with type 2 diabetes or nondiabetic donors. These pancreas-infiltrating neutrophils mainly localized at the level of very small blood vessels. Our findings suggest the existence of a hitherto unrecognized clinical phenotype that might reflect unexplored pathogenic pathways underlying T1D.

In type 1 diabetes, the insulin-producing β-cells are destroyed by the immune system. One way of restoring glucose control is to transplant β-cells from a donor. Although this procedure may restore endogenous insulin production, immunosuppressive treatment is needed to prevent the recipient from rejecting the donor-derived islets. We investigated the possibilities of transient expression of the immunosuppressive cytokine transforming growth factor (TGF)-β within islets to achieve long-term graft tolerance. We found that brief expression of TGF-β prevented rejection of syngeneic islets, that there was reduction of dendritic cell (DC) activation in the graft, and that there was reduced reactivation of T cells in the graft-draining lymph nodes. In vitro exposure of bone marrow–derived DCs to TGF-β reduced expression of costimulatory molecules CD80 and CD86, as well as production of proinflammatory cytokines such as interleukin-12 p70 in DCs, but did not alter levels of major histocompatibility complex classes I and II. Furthermore, the capacity of TGF-β–treated bone marrow–derived DCs to activate both CD4+ and CD8+ T cells was reduced. Adding TGF-β–conditioned tolerogenic DCs to the grafted islets led to long-term survival of the graft, demonstrating that TGF-β–induced tolerogenic DCs can provide an effective means to restore immune tolerance in an already established autoimmune disease.

Type 1 diabetes (T1D) results from immune-mediated destruction of insulin-producing β-cells. The killing of β-cells is not currently measurable; β-cell functional studies routinely used are affected by environmental factors such as glucose and cannot distinguish death from dysfunction. Moreover, it is not known whether immune therapies affect killing. We developed an assay to identify β-cell death by measuring relative levels of unmethylated INS DNA in serum and used it to measure β-cell death in a clinical trial of teplizumab. We studied 43 patients with recent-onset T1D, 13 nondiabetic subjects, and 37 patients with T1D treated with FcR nonbinding anti-CD3 monoclonal antibody (teplizumab) or placebo. Patients with recent-onset T1D had higher rates of β-cell death versus nondiabetic control subjects, but patients with long-standing T1D had lower levels. When patients with recent-onset T1D were treated with teplizumab, β-cell function was preserved (P < 0.05) and the rates of β-cell were reduced significantly (P < 0.05). We conclude that there are higher rates of β-cell death in patients with recent-onset T1D compared with nondiabetic subjects. Improvement in C-peptide responses with immune intervention is associated with decreased β-cell death. © 2013 by the American Diabetes Association.

Transplantation of adult pancreatic islets has been proposed to cure type 1 diabetes (T1D). However, it is rarely considered in the clinic because of its transient effect on disease, the paucity of donors, and the requirement for strong immunosuppressive treatment to prevent allogeneic graft rejection. Transplantation of fetal pancreases (FPs) may constitute an attractive alternative because of potential abundant donor sources, possible long-term effects due to the presence of stem cells maintaining tissue integrity, and their supposed low immunogenicity. In this work, we studied the capacity of early FPs from mouse embryos to develop into functional pancreatic islets producing insulin after transplantation in syngeneic and allogeneic recipients. We found that as few as two FPs were sufficient to control T1D in syngeneic mice. Surprisingly, their development into insulin-producing cells was significantly delayed in male compared with female recipients, which may be explained by lower levels of prolactin in males. Finally, allogeneic FPs were rapidly rejected, even in the context of minor histocompatibility disparities, with massive graft infiltration with T and myeloid cells. This work suggests that FP transplantation as a therapeutic option of T1D needs to be further assessed and would require immunosuppressive treatment.

Soluble interleukin-7 (IL-7) receptor α (sCD127) is implicated in the pathogenesis of autoimmune diseases. We show that serum sCD127 concentrations are increased at the onset of type 1 diabetes (T1D; n = 390) as compared with concentrations in age-matched islet autoantibody–negative first-degree relatives of patients (n = 392; P = 0.00001). sCD127 concentration in patients was influenced by islet autoantibody status (P = 0.003) and genotype of the rs6897932 single nucleotide polymorphism within the IL-7RA gene (P = 0.006). Release of sCD127 in vitro was strongly upregulated by activation of T lymphocytes and affected by exposure to cytokines. sCD127 bound IL-7 and was antagonistic to IL-7 signaling and IL-7–mediated T-cell proliferation, suggesting a regulatory feedback mechanism on T-cell expansion. Remarkably, high glucose led to a glycated form of sCD127 that was ineffective as an IL-7 antagonist. The finding of glycated sCD127 in the circulation of patients at onset of T1D suggested that physiological regulation of IL-7–mediated T-cell survival and expansion by sCD127 may be compromised in T1D. The findings indicate that genetic, immunologic, and metabolic factors contribute to a dysregulation of the IL-7/IL-7 receptor pathway in T1D and identify a novel hyperglycemia-mediated interference of immune regulatory networks.

The role of the intestinal microbiota as a regulator of autoimmune diabetes in animal models is well-established, but data on human type 1 diabetes are tentative and based on studies including only a few study subjects. To exclude secondary effects of diabetes and HLA risk genotype on gut microbiota, we compared the intestinal microbiota composition in children with at least two diabetes-associated autoantibodies (n = 18) with autoantibody-negative children matched for age, sex, early feeding history, and HLA risk genotype using pyrosequencing. Principal component analysis indicated that a low abundance of lactate-producing and butyrate-producing species was associated with β-cell autoimmunity. In addition, a dearth of the two most dominant Bifidobacterium species, Bifidobacterium adolescentis and Bifidobacterium pseudocatenulatum, and an increased abundance of the Bacteroides genus were observed in the children with β-cell autoimmunity. We did not find increased fecal calprotectin or IgA as marker of inflammation in children with β-cell autoimmunity. Functional studies related to the observed alterations in the gut microbiome are warranted because the low abundance of bifidobacteria and butyrate-producing species could adversely affect the intestinal epithelial barrier function and inflammation, whereas the apparent importance of the Bacteroides genus in development of type 1 diabetes is insufficiently understood.

Islet autoimmunity precedes type 1 diabetes onset. We previously found that islet autoimmunity rarely starts before age six months but reaches its highest incidence already at around 1 year of age. We now examine whether homeostatic expansion and immune competence changes seen in a maturating immune system may account for this marked variation in islet autoimmunity risk in the first year of life. We found naïve proinsulin- and GAD65-responsive T cells in cord blood of healthy newborns, with highest responses observed in children with type 1 diabetes susceptible HLA-DRB1/DQB1 genotypes. Homeostatic expansion characteristics with increased IL-7 concentrations and enhanced T cell responsiveness to IL-7 were observed throughout the first year of life. However, the ability of antigen-presenting cells to activate naïve T cells was compromised at birth, and cord blood monocytes had low surface expression of CD40 and HLA class II. In contrast, antigen presentation and expression of these molecules had reached competent adult levels by the high incidence age of 8 months. We propose that temporal changes in islet autoimmunity seroconversion in infants are a consequence of the changing balance between homeostatic drive and antigen presentation competence. These findings are relevant for early prevention of type 1 diabetes.

Altres ajuts: This work was supported by grants from Ministerio de Ciencia e Innovación (SAF2005-01262 and SAF2008-00962) and from the European Community (FP6 CLINIGENE, LSHB-CT-2006-018933). X.M.A., J.A., and A.R. were recipients of a predoctoral fellowship from Ministerio de Educación, Cultura y Deporte, and D.C. received a predoctoral fellowship from Instituto de Salud Carlos III, Spain. C.J.M. In type 1 diabetes, loss of tolerance to β-cell antigens results in T-cell-dependent autoimmune destruction of β cells. The abrogation of autoreactive T-cell responses is a prerequisite to achieve long-lasting correction of the disease. The liver has unique immunomodulatory properties and hepatic gene transfer results in tolerance induction and suppression of autoimmune diseases, in part by regulatory T-cell (Treg) activation. Hence, the liver could be manipulated to treat or prevent diabetes onset through expression of key genes. IGF-I may be an immunomodulatory candidate because it prevents autoimmune diabetes when expressed in β cells or subcutaneously injected. Here, we demonstrate that transient, plasmid-derived IGF-I expression in mouse liver suppressed autoimmune diabetes progression. Suppression was associated with decreased islet inflammation and β-cell apoptosis, increased β-cell replication, and normalized β-cell mass. Permanent protection depended on exogenous IGF-I expression in liver nonparenchymal cells and was associated with increased percentage of intrapancreatic Tregs. Importantly, Treg depletion completely abolished IGF-I-mediated protection confirming the therapeutic potential of these cells in autoimmune diabetes. This study demonstrates that a nonviral gene therapy combining the immunological properties of the liver and IGF-I could be beneficial in the treatment of the disease.

Type 1 diabetes results from T cell–mediated β-cell destruction. The HLA-A*24 class I gene confers significant risk of disease and early onset. We tested the hypothesis that HLA-A24 molecules on islet cells present preproinsulin (PPI) peptide epitopes to CD8 cytotoxic T cells (CTLs). Surrogate β-cell lines secreting proinsulin and expressing HLA-A24 were generated and their peptide ligandome examined by mass spectrometry to discover naturally processed and HLA-A24–presented PPI epitopes. A novel PPI epitope was identified and used to generate HLA-A24 tetramers and examine the frequency of PPI-specific T cells in new-onset HLA-A*24+ patients and control subjects. We identified a novel naturally processed and HLA-A24–presented PPI signal peptide epitope (PPI3–11; LWMRLLPLL). HLA-A24 tetramer analysis reveals a significant expansion of PPI3–11-specific CD8 T cells in the blood of HLA-A*24+ recent-onset patients compared with HLA-matched control subjects. Moreover, a patient-derived PPI3–11-specific CD8 T-cell clone shows a proinflammatory phenotype and kills surrogate β-cells and human HLA-A*24+ islet cells in vitro. These results indicate that the type 1 diabetes susceptibility molecule HLA-A24 presents a naturally processed PPI signal peptide epitope. PPI-specific, HLA-A24–restricted CD8 T cells are expanded in patients with recent-onset disease. Human islet cells process and present PPI3–11, rendering themselves targets for CTL-mediated killing.

We examined whether zinc transporter 8 autoantibodies (ZnT8A; arginine ZnT8-RA, tryptophan ZnT8-WA, and glutamine ZnT8-QA variants) differed between immigrant and Swedish patients due to different polymorphisms of SLC30A8, HLA-DQ, or both. Newly diagnosed autoimmune (andgt;= 1 islet autoantibody) type 1 diabetic patients (n = 2,964, andlt;18 years, 55% male) were ascertained in the Better Diabetes Diagnosis study. Two subgroups were identified: Swedes (n = 2,160, 73%) and immigrants (non-Swedes; n = 212, 7%). Non-Swedes had less frequent ZnT8-WA (38%) than Swedes (50%), consistent with a lower frequency in the non-Swedes (37%) of SLC30A8 CT+TT (RW+WW) genotypes than in the Swedes (54%). ZnT8-RA (57 and 58%, respectively) did not differ despite a higher frequency of CC (RR) genotypes in non-Swedes (63%) than Swedes (46%). We tested whether this inconsistency was due to HLA-DQ as 2/X (2/2; 2/y; y is anything but 2 or 8), which was a major genotype in non-Swedes (40%) compared with Swedes (14%). In the non-Swedes only, 2/X (2/2; 2/y) was negatively associated with ZnT8-WA and ZnT8-QA but not ZnT8-RA. Molecular simulation showed nonbinding of the relevant ZnT8-R peptide to DQ2, explaining in part a possible lack of tolerance to ZnT8-R. At diagnosis in non-Swedes, the presence of ZnT8-RA rather than ZnT8-WA was likely due to effects of HLA-DQ2 and the SLC30A8 CC (RR) genotypes. Funding Agencies|Swedish Child Diabetes Foundation (Barndiabetesfonden)||National Institutes of Health|DK-63861DK-26190|Swedish Research Council||KA Wallenberg Foundation||European Union|202013|Swedish Diabetes Association||Skane County Council Foundation for Research and Development||Swedish Association of Local Authorities and Regions||EU funds||Hellenic State funds

Cytokines are upregulated in prediabetes, but their relationship with Enterovirus (EV) infection and development of islet autoimmunity is unknown. Cytokines (n = 65) were measured using Luminex xMAP technology in a nested case-control study of 67 children with a first-degree relative with type 1 diabetes: 27 with islet autoantibodies (Ab+) and 40 age-matched persistently autoantibody negative (Ab−) control subjects. Of 74 samples, 37 (50%) were EV-PCR+ in plasma and/or stool (EV+) and the remainder were negative for EV and other viruses (EV−). Fifteen cytokines, chemokines, and growth factors were elevated (P ≤ 0.01) in Ab+ versus Ab− children (interleukin [IL]-1β, IL-5, IL-7, IL-12(p70), IL-16, IL-17, IL-20, IL-21, IL-28A, tumor necrosis factor-α, chemokine C-C motif ligand [CCL]13, CCL26, chemokine C-X-C motif ligand 5, granulocyte-macrophage colony-stimulating factor, and thrombopoietin); most have proinflammatory effects. In EV+ versus EV− children, IL-10 was higher (P = 0.005), while IL-21 was lower (P = 0.008). Cytokine levels did not differ between Ab+EV+ and Ab+EV− children. Heat maps demonstrated clustering of some proinflammatory cytokines in Ab+ children, suggesting they are coordinately regulated. In conclusion, children with islet autoimmunity demonstrate higher levels of multiple cytokines, consistent with an active inflammatory process in the prediabetic state, which is unrelated to coincident EV infection. Apart from differences in IL-10 and IL-21, EV infection was not associated with a specific cytokine profile.

In diabetic patients and susceptible mice, insulin is a targeted autoantigen. Insulin B chain 9-23 (B:9-23) autoreactive CD4 T cells are key for initiating autoimmune diabetes in NOD mice; however, little is known regarding their origin and function. To this end, B:9-23-specific, BDC12-4.1 T-cell receptor (TCR) transgenic (Tg) mice were studied, of which, despite expressing a single TCR on the recombination activating gene-deficient background, only a fraction develops diabetes in an asynchronous manner. BDC12-4.1 CD4 T cells convert into effector (Teff) and Foxp3(+)-expressing adaptive regulatory T cells (aTregs) soon after leaving the thymus as a result of antigen recognition and homeostatic proliferation. The generation of aTreg causes the heterogeneous diabetes onset, since crossing onto the scurfy (Foxp3) mutation, BDC12-4.1 TCR Tg mice develop accelerated and fully penetrant diabetes. Similarly, adoptive transfer and bone marrow transplantation experiments showed differential diabetes kinetics based on Foxp3(+) aTreg's presence in the BDC12-4.1 donors. A single-specificity, insulin-reactive TCR escapes thymic deletion and simultaneously converts into aTreg and Teff, establishing an equilibrium that determines diabetes penetrance. These results are of particular importance for understanding disease pathogenesis. They suggest that once central tolerance is bypassed, autoreactive cells arriving in the periphery do not by default follow solely a pathogenic fate upon activation.

T cell-mediated rejection remains a barrier to the clinical application of islet xenotransplantation. Regulatory T cells (Treg) regulate immune responses by suppressing effector T cells. This study aimed to determine the ability of human Treg to prevent islet xenograft rejection and the mechanism(s) involved. Neonatal porcine islet transplanted NOD-SCID IL2rγ−/− mice received human peripheral blood mononuclear cells (PBMC) with in vitro expanded autologous Treg in the absence or presence of anti-human interleukin-10 (IL-10) monoclonal antibody. In addition, human PBMC-reconstituted recipient mice received recombinant human IL-10 (rhIL-10). Adoptive transfer with expanded autologous Treg prevented islet xenograft rejection in human PBMC-reconstituted mice by inhibiting graft infiltration of effector cells and their function. Neutralization of human IL-10 shortened xenograft survival in mice receiving human PBMC and Treg. In addition, rhIL-10 treatment led to prolonged xenograft survival in human PBMC-reconstituted mice. This study demonstrates the ability of human Treg to prevent T-cell effector function and the importance of IL-10 in this response. In vitro Treg expansion was a simple and effective strategy for generating autologous Treg and highlighted a potential adoptive Treg cell therapy to suppress antigraft T-cell responses and reduce the requirement for immunosuppression in islet xenotransplantation.

Experimental studies indicate low revascularization of intraportally transplanted islets. This study aimed to quantify, for the first time, the blood perfusion of intrahepatically transplanted islets and elucidate necessary factors for proper islet graft revascularization at this site. Yellow chameleon protein 3.0 islets expressing fluorescent protein in all cells were transplanted. Graft blood perfusion was determined by microspheres. The vascular density and relative contribution of donor blood vessels in revascularization was evaluated using islets expressing green fluorescent protein under the Tie-2 promoter. Blood perfusion of intrahepatic islets was as a mean only 5% of that of native islets at 1-month posttransplantation. However, there was a marked heterogeneity where blood perfusion was less decreased in islets transplanted without prior culture and in many cases restored in islets with disrupted integrity. Analysis of vascular density showed that distorted islets were well revascularized, whereas islets still intact at 1-month posttransplantation were almost avascular. Few donor endothelial cells were observed in the new islet vasculature. The very low blood perfusion of intraportally transplanted islets is likely to predispose for ischemia and hamper islet function. Since donor endothelial cells do not expand posttransplantation, disruption of islet integrity is necessary for revascularization to occur by recipient blood vessels.

Current therapies for type 1 diabetes (T1D) involve insulin replacement or transplantation of insulin-secreting tissue, both of which suffer from numerous limitations and complications. Here, we show that subcutaneous transplants of embryonic brown adipose tissue (BAT) can correct T1D in streptozotocin-treated mice (both immune competent and immune deficient) with severely impaired glucose tolerance and significant loss of adipose tissue. BAT transplants result in euglycemia, normalized glucose tolerance, reduced tissue inflammation, and reversal of clinical diabetes markers such as polyuria, polydipsia, and polyphagia. These effects are independent of insulin but correlate with recovery of the animals’ white adipose tissue. BAT transplants lead to significant increases in adiponectin and leptin, but with levels that are static and not responsive to glucose. Pharmacological blockade of the insulin receptor in BAT transplant mice leads to impaired glucose tolerance, similar to what is seen in nondiabetic animals, indicating that insulin receptor activity plays a role in the reversal of diabetes. One possible candidate for activating the insulin receptor is IGF-1, whose levels are also significantly elevated in BAT transplant mice. Thus, we propose that the combined action of multiple adipokines establishes a new equilibrium in the animal that allows for chronic glycemic control without insulin.

More than one-half of the ~50 human chemokines have been associated with or implicated in the pathogenesis of type 1 diabetes, yet their actual expression patterns in the islet environment of type 1 diabetic patients remain, at present, poorly defined. Here, we have integrated a human islet culture system, murine models of virus-induced and spontaneous type 1 diabetes, and the histopathological examination of pancreata from diabetic organ donors with the goal of providing a foundation for the informed selection of potential therapeutic targets within the chemokine/receptor family. Chemokine (C-C motif) ligand (CCL) 5 (CCL5), CCL8, CCL22, chemokine (C-X-C motif) ligand (CXCL) 9 (CXCL9), CXCL10, and chemokine (C-X3-C motif) ligand (CX3CL) 1 (CX3CL1) were the major chemokines transcribed (in an inducible nitric oxide synthase–dependent but not nuclear factor-κB–dependent fashion) and translated by human islet cells in response to in vitro inflammatory stimuli. CXCL10 was identified as the dominant chemokine expressed in vivo in the islet environment of prediabetic animals and type 1 diabetic patients, whereas CCL5, CCL8, CXCL9, and CX3CL1 proteins were present at lower levels in the islets of both species. Of importance, additional expression of the same chemokines in human acinar tissues emphasizes an underappreciated involvement of the exocrine pancreas in the natural course of type 1 diabetes that will require consideration for additional type 1 diabetes pathogenesis and immune intervention studies.

Adipose-derived mesenchymal stem cells (ADMSCs) display immunosuppressive properties, suggesting a promising therapeutic application in several autoimmune diseases, but their role in type 1 diabetes (T1D) remains largely unexplored. The aim of this study was to investigate the immune regulatory properties of allogeneic ADMSC therapy in T cell–mediated autoimmune diabetes in NOD mice. ADMSC treatment reversed the hyperglycemia of early-onset diabetes in 78% of diabetic NOD mice, and this effect was associated with higher serum insulin, amylin, and glucagon-like peptide 1 levels compared with untreated controls. This improved outcome was associated with downregulation of the CD4+ Th1-biased immune response and expansion of regulatory T cells (Tregs) in the pancreatic lymph nodes. Within the pancreas, inflammatory cell infiltration and interferon-γ levels were reduced, while insulin, pancreatic duodenal homeobox-1, and active transforming growth factor-β1 expression were increased. In vitro, ADMSCs induced the expansion/proliferation of Tregs in a cell contact–dependent manner mediated by programmed death ligand 1. In summary, ADMSC therapy efficiently ameliorates autoimmune diabetes pathogenesis in diabetic NOD mice by attenuating the Th1 immune response concomitant with the expansion/proliferation of Tregs, thereby contributing to the maintenance of functional β-cells. Thus, this study may provide a new perspective for the development of ADMSC-based cellular therapies for T1D.

Type 1 diabetes involves both T helper (Th)1 and Th17 cells. While the mechanisms underlying the control of Th1 cells are relatively well defined, those operating modulation of Th17 cells remain unknown. Moreover, given that Th17 cells are plastic and can drive disease as stable or convertible T cells, effective approaches to counter type 1 diabetes would have to alter Th17 function under both circumstances. Herein, we genetically incorporated the BDC2.5-reactive p79 mimotope into an Ig molecule, and the resulting Ig-p79 was used to investigate Th17 tolerance. Accordingly, diabetogenic BDC2.5 Th17 cells were transferred into NOD mice under convertible or stable conditions and their fate was evaluated upon induction of tolerance and disease suppression by Ig-p79. The findings show that convertible (Th17 to Th1) cells display downregulation of the chemokine (C-X-C motif) receptor 3 that was associated with diminished T-box transcription factor T-bet expression, retention in the spleen, and inhibition of trafficking to the pancreas. In contrast, stable Th17 cells downregulated orphan nuclear receptor ROR-γt but increased Fas ligand expression and died by apoptosis. Thus, the final signature transcription factor shapes the mechanism of tolerance in plastic Th17 cells. These findings suggest that effective strategies against type 1 diabetes will require regimens that could drive both mechanisms of tolerance to overcome the disease.

B cells participate in the priming of the allo- and autoimmune responses, and their depletion can thus be advantageous for islet transplantation. Herein, we provide an extensive study of the effect of B-cell depletion in murine models of islet transplantation. Islet transplantation was performed in hyperglycemic B-cell–deficient(μMT) mice, in a purely alloimmune setting (BALB/c into hyperglycemic C57BL/6), in a purely autoimmune setting (NOD.SCID into hyperglycemic NOD), and in a mixed allo-/autoimmune setting (BALB/c into hyperglycemic NOD). Inotuzumab ozogamicin murine analog (anti-CD22 monoclonal antibody conjugated with calicheamicin [anti-CD22/cal]) efficiently depleted B cells in all three models of islet transplantation examined. Islet graft survival was significantly prolonged in B-cell–depleted mice compared with control groups in transplants of islets from BALB/c into C57BL/6 (mean survival time [MST]: 16.5 vs. 12.0 days; P = 0.004), from NOD.SCID into NOD (MST: 23.5 vs. 14.0 days; P = 0.03), and from BALB/c into NOD (MST: 12.0 vs. 5.5 days; P = 0.003). In the BALB/c into B-cell–deficient mice model, islet survival was prolonged as well (MST: μMT = 32.5 vs. WT = 14 days; P = 0.002). Pathology revealed reduced CD3+ cell islet infiltration and confirmed the absence of B cells in treated mice. Mechanistically, effector T cells were reduced in number, concomitant with a peripheral Th2 profile skewing and ex vivo recipient hyporesponsiveness toward donor-derived antigen as well as islet autoantigens. Finally, an anti-CD22/cal and CTLA4-Ig–based combination therapy displayed remarkable prolongation of graft survival in the stringent model of islet transplantation (BALB/c into NOD). Anti-CD22/cal–mediated B-cell depletion promotes the reduction of the anti-islet immune response in various models of islet transplantation.

A subset of children develops persistent insulin autoantibodies (IAA; almost always as the only islet autoantibody) without evidence of progression to diabetes. The aim of the current study was the development and characterization of the performance of a nonradioactive fluid phase IAA assay in relation to standard IAA radioassay. We developed a nonradioactive IAA assay where bivalent IAA cross-link two insulin moieties in a fluid phase. The serum samples positive for anti-islet autoantibodies from 150 newly diagnosed patients with diabetes (Barbara Davis Center plus Diabetes Autoantibody Standardization Program [DASP] workshop) and 70 prediabetic subjects who were followed to diabetes were studied. In addition, sequential samples from 64 nondiabetic subjects who were persistently IAA(+) were analyzed. With 99th percentile of specificity, the new assay with the technology from Meso Scale Discovery Company (MSD-IAA) detects as positive 61% (61 of 100) of new-onset patients and 80% (56 of 70) of prediabetic patients compared with our current fluid phase micro-IAA radioassay (mIAA; 44 and 74%, respectively). In addition, MSD-IAA demonstrated better sensitivity than our mIAA from blinded DASP workshop (68 vs. 56% with the same 99% specificity). Of 64 IAA(+) nondiabetic subjects, 25% (8 of 32) who had only IAA and thus the low risk for progression to diabetes were positive with MSD-IAA assay. In contrast, 100% (32 of 32) high-risk children (IAA plus other islet autoantibodies) were positive with MSD-IAA. The IAA detectable by radioassay, but not MSD-IAA, were usually of lower affinity compared with the IAA of the high-risk children. These data suggest that a subset of IAA with current radioassay (not MSD-IAA) represents biologic false positives in terms of autoimmunity leading to diabetes. We hypothesize that factors related to the mechanism of loss of tolerance leading to diabetes determine high affinity and MSD-IAA reactivity.

Inflammatory cytokines are involved in autoimmune diabetes: among the most prominent is interleukin (IL)-1β. We postulated that blockade of IL-1β would modulate the effects of anti-CD3 monoclonal antibody (mAb) in treating diabetes in NOD mice. To test this, we treated hyperglycemic NOD mice with F(ab')(2) fragments of anti-CD3 mAb with or without IL-1 receptor antagonist (IL-1RA), or anti-IL-1β mAb. We studied the reversal of diabetes and effects of treatment on the immune system. Mice that received a combination of anti-CD3 mAb with IL-1RA showed a more rapid rate of remission of diabetes than mice treated with anti-CD3 mAb or IL-1RA alone. Combination-treated mice had increased IL-5, IL-4, and interferon (IFN)-γ levels in circulation. There were reduced pathogenic NOD-relevant V7 peptide-V7(+) T cells in the pancreatic lymph nodes. Their splenocytes secreted more IL-10, had increased arginase expression in macrophages and dendritic cells, and had delayed adoptive transfer of diabetes. After 1 month, there were increased concentrations of IgG1 isotype antibodies and reduced intrapancreatic expression of IFN-γ, IL-6, and IL-17 despite normal splenocyte cytokine secretion. These studies indicate that the combination of anti-CD3 mAb with IL-1RA is synergistic in reversal of diabetes through a combination of mechanisms. The combination causes persistent remission from islet inflammation.

OBJECTIVE Interleukin-21 (IL-21) is a proinflammatory cytokine that has been shown to affect Treg/Teff balance. However, the mechanism by which IL-21 orchestrates alloimmune response and interplays with Tregs is still unclear. RESEARCH DESIGN AND METHODS The interplay between IL-21/IL-21R signaling, FoxP3 expression, and Treg survival and function was evaluated in vitro in immunologically relevant assays and in vivo in allogenic and autoimmune models of islet transplantation. RESULTS IL-21R expression decreases on T cells and B cells in vitro and increases in the graft in vivo, while IL-21 levels increase in vitro and in vivo during anti-CD3/anti-CD28 stimulation/allostimulation in the late phase of the alloimmune response. In vitro, IL-21/IL-21R signaling (by using rmIL-21 or genetically modified CD4+ T cells [IL-21 pOrf plasmid–treated or hIL-21-Tg mice]) enhances the T-cell response during anti-CD3/anti-CD28 stimulation/allostimulation, prevents Treg generation, inhibits Treg function, induces Treg apoptosis, and reduces FoxP3 and FoxP3-dependent gene transcripts without affecting FoxP3 methylation status. In vivo targeting of IL-21/IL-21R expands intragraft and peripheral Tregs, promotes Treg neogenesis, and regulates the antidonor immune response, whereas IL-21/IL-21R signaling in Doxa-inducible ROSA-rtTA-IL-21-Tg mice expands Teffs and FoxP3− cells. Treatment with a combination of mIL-21R.Fc and CTLA4-Ig (an inhibitor of the early alloimmune response) leads to robust graft tolerance in a purely alloimmune setting and prolonged islet graft survival in NOD mice. CONCLUSIONS IL-21 interferes with different checkpoints of the FoxP3 Treg chain in the late phase of alloimmune response and, thus, acts as an antitolerogenic cytokine. Blockade of the IL-21/IL-21R pathway could be a precondition for tolerogenic protocols in transplantation.

OBJECTIVE Autoimmune diseases, including type 1 diabetes, are thought to have a Th17-cell bias and/or a T-regulatory cell (Treg) defect. Understanding whether this is a hallmark of patients with type 1 diabetes is a crucial question that is still unsolved, largely due to the difficulties of accessing tissues targeted by the disease. RESEARCH DESIGN AND METHODS We phenotypically and functionally characterized Th17 cells and Tregs residing in the pancreatic-draining lymph nodes (PLNs) of 19 patients with type 1 diabetes and 63 nondiabetic donors and those circulating in the peripheral blood of 14 type 1 diabetic patients and 11 healthy subjects. RESULTS We found upregulation of Th17 immunity and functional defects in CD4+CD25bright Tregs in the PLNs of type 1 diabetic subjects but not in their peripheral blood. In addition, the proinsulin-specific Treg-mediated control was altered in the PLNs of diabetic patients. The dysfunctional Tregs isolated from diabetic subjects did not contain contaminant effector T cells and were all epigenetically imprinted to be suppressive, as defined by analysis of the Treg-specific demethylated region within the forkhead box P3 (FOXP3) locus. CONCLUSIONS These data provide evidence for an unbalanced immune status in the PLNs of type 1 diabetic subjects, and treatments restoring the immune homeostasis in the target organ of these patients represent a potential therapeutic strategy.

OBJECTIVE Previous studies have noted a specific association between type 1 diabetes and insufficient levels of vitamin D, as well as polymorphisms within genes related to vitamin D pathways. Here, we examined whether serum levels or genotypes of the vitamin D–binding protein (VDBP), a molecule key to the biologic actions of vitamin D, specifically associate with the disorder. RESEARCH DESIGN AND METHODS A retrospective, cross-sectional analysis of VDBP levels used samples from 472 individuals of similar age and sex distribution, including 153 control subjects, 203 patients with type 1 diabetes, and 116 first-degree relatives of type 1 diabetic patients. Single nucleotide polymorphism (SNP) typing for VDBP polymorphisms (SNP rs4588 and rs7041) was performed on this cohort to determine potential genetic correlations. In addition, SNP analysis of a second sample set of banked DNA samples from 1,502 type 1 diabetic patients and 1,880 control subjects also was used to determine genotype frequencies. RESULTS Serum VDBP levels were highest in healthy control subjects (median 423.5 µg/mL [range 193.5–4,345.0; interquartile range 354.1–]586), intermediate in first-degree relatives (402.9 µg/mL [204.7–4,850.0; 329.6–492.4]), and lowest in type 1 diabetic patients (385.3 µg/mL [99.3–1,305.0; 328.3–473.0]; P = 0.003 vs. control subjects). VDBP levels did not associate with serum vitamin D levels, age, or disease duration. However, VDBP levels were, overall, lower in male subjects (374.7 µg/mL [188.9–1,602.0; 326.9–449.9]) than female subjects (433.4 µg/mL [99.3–4,850.0; 359.4–567.8]; P < 0.0001). It is noteworthy that no differences in genotype frequencies of the VDBP polymorphisms were associated with serum VDBP levels or between type 1 diabetic patients and control subjects. CONCLUSIONS Serum VDBP levels are decreased in those with type 1 diabetes. These studies suggest that multiple components in the metabolic pathway of vitamin D may be altered in type 1 diabetes and, collectively, have the potential to influence disease pathogenesis.

CD4 T-cells secreting interleukin (IL)-17 are implicated in several human autoimmune diseases, but their role in type 1 diabetes has not been defined. To address the relevance of such cells, we examined IL-17 secretion in response to β-cell autoantigens, IL-17A gene expression in islets, and the potential functional consequences of IL-17 release for β-cells., Journal Article, Research Support, Non-U.S. Gov't, SCOPUS: ar.j, info:eu-repo/semantics/published

OBJECTIVE The gut environment modulates the pathogenesis of type 1 diabetes (T1D), but how it affects autoimmunity toward pancreatic β-cells, a self-tissue located outside the intestine, is still unclear. In the small intestine, lamina propria dendritic cells (LPDCs) induce peripheral differentiation of FoxP3+ regulatory T (Treg) cells. We tested the hypothesis that the intestinal milieu impinges on human T1D by affecting differentiation of FoxP3+ Treg cells. RESEARCH DESIGN AND METHODS We collected duodenal biopsies of 10 T1D patients, 16 healthy subjects, and 20 celiac individuals and performed a fluorescent-activated cell sorter analysis to measure percentages of various immune cell subsets, including CD4+ and CD8+ T cells, NK cells, γδ T cells, CD103+CD11c+ LPDCs, and CD4+CD25+FoxP3+CD127− Treg cells. In parallel, we assessed the tolerogenic function (i.e., capacity to induce differentiation of FoxP3+ Treg cells) by LPDCs of T1D patients and control subjects. RESULTS Our analysis revealed a significant reduction in the percentage of intestinal CD4+CD25+FoxP3+CD127− Treg cells in T1D patients compared with healthy subjects (P = 0.03) and celiac individuals (P = 0.003). In addition, we found that LPDCs from T1D patients completely lacked their tolerogenic function; they were unable to convert CD4+CD25− T cells into CD4+CD25+FoxP3+CD127− Treg cells. CONCLUSIONS Our data indicate that T1D patients have a reduced number of intestinal FoxP3+ Treg cells as a result of their defective differentiation in the gut. These findings suggest that intestinal immune regulation is not only calibrated to tolerate commensal bacteria and food components but also is instrumental in maintaining immune tolerance toward pancreatic β-cells and preventing T1D.

OBJECTIVE Type 1 diabetes is an autoimmune disease characterized by the destruction of insulin-producing β-cells. NOD mice provide a useful tool for understanding disease pathogenesis and progression. Although much has been learned from studies with NOD mice, increased understanding of human type 1 diabetes can be gained by evaluating the pathogenic potential of human diabetogenic effector cells in vivo. Therefore, our objective in this study was to develop a small-animal model using human effector cells to study type 1 diabetes. RESEARCH DESIGN AND METHODS We adoptively transferred HLA-A2–matched peripheral blood mononuclear cells (PBMCs) from type 1 diabetic patients and nondiabetic control subjects into transgenic NOD-scid/γcnull/HLA-A*0201 (NOD-scid/γcnull/A2) mice. At various times after adoptive transfer, we determined the ability of these mice to support the survival and proliferation of the human lymphoid cells. Human lymphocytes were isolated and assessed from the blood, spleen, pancreatic lymph node and islets of NOD-scid/γcnull/A2 mice after transfer. RESULTS Human T and B cells proliferate and survive for at least 6 weeks and were recovered from the blood, spleen, draining pancreatic lymph node, and most importantly, islets of NOD-scid/γcnull/A2 mice. Lymphocytes from type 1 diabetic patients preferentially infiltrate the islets of NOD-scid/γcnull/A2 mice. In contrast, PBMCs from nondiabetic HLA-A2–matched donors showed significantly less islet infiltration. Moreover, in mice that received PBMCs from type 1 diabetic patients, we identified epitope-specific CD8+ T cells among the islet infiltrates. CONCLUSIONS We show that insulitis is transferred to NOD-scid/γcnull/A2 mice that received HLA-A2–matched PBMCs from type 1 diabetic patients. In addition, many of the infiltrating CD8+ T cells are epitope-specific and produce interferon-γ after in vitro peptide stimulation. This indicates that NOD-scid/γcnull/A2 mice transferred with HLA-A2–matched PBMCs from type 1 diabetic patients may serve as a useful tool for studying epitope-specific T-cell–mediated responses in patients with type 1 diabetes.

OBJECTIVE β-Cell and islet endothelial cell destruction occurs during the progression of type 1 diabetes, but, paradoxically, β-cell proliferation is increased during this period. Altered glucose tolerance may affect β-cell mass and its association with endothelial cells. Our objective was to study the effects of glucose and inflammation on islet vascularity and on β function, mass, and insulin in immunologically tolerant anti-CD3 monoclonal antibody (mAb)-treated and prediabetic NOD mice. RESEARCH DESIGN AND METHODS The effects of phloridzin or glucose injections on β-cells and endothelial cells were tested in prediabetic and previously diabetic NOD mice treated with anti-CD3 mAbs. Glucose tolerance, immunofluorescence staining, and examination of islet cultures ex vivo were evaluated. RESULTS Islet endothelial cell density decreased in NOD mice and failed to recover after anti-CD3 mAb treatment despite baseline euglycemia. Glucose treatment of anti-CD3 mAb–treated mice showed increased islet vascular density and increased insulin content, which was associated with improved glucose tolerance. The increase in the vascular area was dependent on islet inflammation. Increased islet endothelial cell density was associated with increased production of vascular endothelial growth factor (VEGF) by islets from NOD mice. This response was recapitulated ex vivo by the transfer of supernatants from NOD islets cultured in high-glucose levels. CONCLUSIONS Our results demonstrate a novel role for glucose and inflammation in the control of islet vasculature and insulin content of β-cells in prediabetic and anti-CD3–treated NOD mice. VEGF production by the islets is affected by glucose levels and is imparted by soluble factors released by inflamed islets.

OBJECTIVE Natural killer (NK) cells from NOD mice have numeric and functional abnormalities, and restoration of NK cell function prevents autoimmune diabetes in NOD mice. However, little is known about the number and function of NK cells in humans affected by type 1 diabetes. Therefore, we evaluated the phenotype and function of NK cells in a large cohort of type 1 diabetic children. RESEARCH DESIGN AND METHODS Peripheral blood mononuclear blood cells were obtained from subjects whose duration of disease was between 6 months and 2 years. NK cells were characterized by flow cytometry, enzyme-linked immunosorbent spot assays, and cytotoxicity assays. Signaling through the activating NK cell receptor, NKG2D, was assessed by immunoblotting and reverse-phase phosphoprotein lysate microarray. RESULTS NK cells from type 1 diabetic subjects were present at reduced cell numbers compared with age-matched, nondiabetic control subjects and had diminished responses to the cytokines interleukin (IL)-2 and IL-15. Analysis before and after IL-2 stimulation revealed that unlike NK cells from nondiabetic control subjects, NK cells from type 1 diabetic subjects failed to downregulate the NKG2D ligands, major histocompatibility complex class I–related chains A and B, upon activation. Moreover, type 1 diabetic NK cells also exhibited decreased NKG2D-dependent cytotoxicity and interferon-γ secretion. Finally, type 1 diabetic NK cells showed clear defects in NKG2D-mediated activation of the phosphoinositide 3-kinase–AKT pathway. CONCLUSIONS These results are the first to demonstrate that type 1 diabetic subjects have aberrant signaling through the NKG2D receptor and suggest that NK cell dysfunction contributes to the autoimmune pathogenesis of type 1 diabetes.

OBJECTIVE Streptozotocin (STZ) is the most widely used diabetogenic agent in animal models of islet transplantation. However, the immunomodifying effects of STZ and the ensuing hyperglycemia on lymphocyte subsets, particularly on T regulatory cells (Tregs), remain poorly understood. RESEARCH DESIGN AND METHODS This study evaluated how STZ-induced diabetes affects adaptive immunity and the consequences thereof on allograft rejection in murine models of islet and skin transplantation. The respective toxicity of STZ and hyperglycemia on lymphocyte subsets was tested in vitro. The effect of hyperglycemia was assessed independently of STZ in vivo by the removal of transplanted syngeneic islets, using an insulin pump, and with rat insulin promoter diphtheria toxin receptor transgenic mice. RESULTS Early lymphopenia in both blood and spleen was demonstrated after STZ administration. Direct toxicity of STZ on lymphocytes, particularly on CD8+ cells and B cells, was shown in vitro. Hyperglycemia also correlated with blood and spleen lymphopenia in vivo but was not lymphotoxic in vitro. Independently of hyperglycemia, STZ led to a relative increase of Tregs in vivo, with the latter retaining their suppressive capacity in vitro. The higher frequency of Tregs was associated with Treg proliferation in the blood, but not in the spleen, and higher blood levels of transforming growth factor-β. Finally, STZ administration delayed islet and skin allograft rejection compared with naive mice. CONCLUSIONS These data highlight the direct and indirect immunosuppressive effects of STZ and acute hyperglycemia, respectively. Thus, these results have important implications for the future development of tolerance-based protocols and their translation from the laboratory to the clinic.

OBJECTIVEType 1 diabetes results from selective T-cell–mediated destruction of the insulin-producing β-cells in the pancreas. In this process, islet epitope–specific CD8+ T-cells play a pivotal role. Thus, monitoring of multiple islet–specific CD8+ T-cells may prove to be valuable for measuring disease activity, progression, and intervention. Yet, conventional detection techniques (ELISPOT and HLA tetramers) require many cells and are relatively insensitive.RESEARCH DESIGN AND METHODSHere, we used a combinatorial quantum dot major histocompatibility complex multimer technique to simultaneously monitor the presence of HLA-A2 restricted insulin B10–18, prepro-insulin (PPI)15–24, islet antigen (IA)-2797–805, GAD65114–123, islet-specific glucose-6-phosphatase catalytic subunit–related protein (IGRP)265–273, and prepro islet amyloid polypeptide (ppIAPP)5–13–specific CD8+ T-cells in recent-onset diabetic patients, their siblings, healthy control subjects, and islet cell transplantation recipients.RESULTSUsing this kit, islet autoreactive CD8+ T-cells recognizing insulin B10–18, IA-2797–805, and IGRP265–273 were shown to be frequently detectable in recent-onset diabetic patients but rarely in healthy control subjects; PPI15–24 proved to be the most sensitive epitope. Applying the “Diab-Q-kit” to samples of islet cell transplantation recipients allowed detection of changes of autoreactive T-cell frequencies against multiple islet cell–derived epitopes that were associated with disease activity and correlated with clinical outcome.CONCLUSIONSA kit was developed that allows simultaneous detection of CD8+ T-cells reactive to multiple HLA-A2–restricted β-cell epitopes requiring limited amounts of blood, without a need for in vitro culture, that is applicable on stored blood samples.

OBJECTIVEMultiple type 1 diabetes susceptibility genes have now been identified in both humans and mice, yet mechanistic understanding of how they impact disease pathogenesis is still minimal. We have sought to dissect the cellular basis for how the highly protective mouse Idd9 region limits the expansion of autoreactive CD8+ T-cells, a key cell type in destruction of the islets.RESEARCH DESIGN AND METHODSWe assess the endogenous CD8+ T-cell repertoire for reactivity to the islet antigen glucose-6-phosphatase–related protein (IGRP). Through the use of adoptively transferred T-cells, bone marrow chimeras, and reconstituted severe combined immunodeficient mice, we identify the protective cell types involved.RESULTSIGRP-specific CD8+ T-cells are present at low frequency in the insulitic lesions of Idd9 mice and could not be recalled in the periphery by viral expansion. We show that Idd9 genes act extrinsically to the CD8+ T-cell to prevent the massive expansion of pathogenic effectors near the time of disease onset that occurs in NOD mice. The subregions Idd9.2 and Idd9.3 mediated this effect. Interestingly, the Idd9.1 region, which provides significant protection from disease, did not prevent the expansion of autoreactive CD8+ T-cells. Expression of Idd9 genes was required by both CD4+ T-cells and a nonlymphoid cell to induce optimal tolerance.CONCLUSIONSIdd9 protective alleles are associated with reduced expansion of IGRP-specific CD8+ T-cells. Intrinsic expression of protective Idd9 alleles in CD4+ T-cells and nonlymphoid cells is required to achieve an optimal level of tolerance. Protective alleles in the Idd9.2 congenic subregion are required for the maximal reduction of islet-specific CD8+ T-cells.

OBJECTIVE To evaluate the significance of GAD antibodies (GADAs) and family history for type 1 diabetes (FHT1) or type 2 diabetes (FHT2) in nondiabetic subjects. RESEARCH DESIGN AND METHODS GADAs were analyzed in 4,976 nondiabetic relatives of type 2 diabetic patients or control subjects from Finland. Altogether, 289 (5.9%) were GADA+—a total of 253 GADA+ and 2,511 GADA− subjects participated in repeated oral glucose tolerance tests during a median time of 8.1 years. The risk of progression to diabetes was assessed using Cox regression analysis. RESULTS Subjects within the highest quartile of GADA+ (GADA+high) had more often first-degree FHT1 (29.2 vs. 7.9%, P < 0.00001) and GADA+ type 2 diabetic (21.3 vs. 13.7%, P = 0.002) or nondiabetic (26.4 vs. 13.3%, P = 0.010) relatives than GADA− subjects. During the follow-up, the GADA+ subjects developed diabetes significantly more often than the GADA− subjects (36/253 [14.2%] vs. 134/2,511 [5.3%], P < 0.00001). GADA+high conferred a 4.9-fold increased risk of diabetes (95% CI 2.8–8.5) compared with GADA−—seroconversion to positive during the follow-up was associated with 6.5-fold (2.8–15.2) and first-degree FHT1 with 2.2-fold (1.2–4.1) risk of diabetes. Only three subjects developed type 1 diabetes, and others had a non–insulin-dependent phenotype 1 year after diagnosis. GADA+ and GADA− subjects did not clinically differ at baseline, but they were leaner and less insulin resistant after the diagnosis of diabetes. CONCLUSIONS GADA positivity clusters in families with type 1 diabetes or latent autoimmune diabetes in adults. GADA positivity predicts diabetes independently of family history of diabetes, and this risk was further increased with high GADA concentrations.

OBJECTIVE To investigate if recurrent autoimmunity explained hyperglycemia and C-peptide loss in three immunosuppressed simultaneous pancreas-kidney (SPK) transplant recipients. RESEARCH DESIGN AND METHODS We monitored autoantibodies and autoreactive T-cells (using tetramers) and performed biopsy. The function of autoreactive T-cells was studied with in vitro and in vivo assays. RESULTS Autoantibodies were present pretransplant and persisted on follow-up in one patient. They appeared years after transplantation but before the development of hyperglycemia in the remaining patients. Pancreas transplant biopsies were taken within ∼1 year from hyperglycemia recurrence and revealed β-cell loss and insulitis. We studied autoreactive T-cells from the time of biopsy and repeatedly demonstrated their presence on further follow-up, together with autoantibodies. Treatment with T-cell–directed therapies (thymoglobulin and daclizumab, all patients), alone or with the addition of B-cell–directed therapy (rituximab, two patients), nonspecifically depleted T-cells and was associated with C-peptide secretion for >1 year. Autoreactive T-cells with the same autoantigen specificity and conserved T-cell receptor later reappeared with further C-peptide loss over the next 2 years. Purified autoreactive CD4 T-cells from two patients were cotransplanted with HLA-mismatched human islets into immunodeficient mice. Grafts showed β-cell loss in mice receiving autoreactive T-cells but not control T-cells. CONCLUSIONS We demonstrate the cardinal features of recurrent autoimmunity in three such patients, including the reappearance of CD4 T-cells capable of mediating β-cell destruction. Markers of autoimmunity can help diagnose this underappreciated cause of graft loss. Immune monitoring during therapy showed that autoimmunity was not resolved by the immunosuppressive agents used.

OBJECTIVE Costimulation blockade has emerged as a selective nontoxic maintenance therapy in transplantation. However, these drugs must be combined with other immunomodulatory agents to ensure long-term graft survival. RESEARCH DESIGN AND METHODS Recent work has demonstrated that caspase inhibitor therapy (EP1013) prevents engraftment phase islet loss and markedly reduces the islet mass required to reverse diabetes. The “danger” hypothesis suggests that reduction in graft apoptosis should reduce the threshold for immunosuppression and increase the possibility for tolerance induction. Thus, the impact of combination of EP1013 treatment with costimulation blockade (CTLA4-Ig) was investigated in this study. RESULTS Islet allografts were completed in fully major histocompatibility complex (MHC)-mismatched mice (Balb/C to B6). When animals received vehicle or EP1013, there was no difference in graft survival. CTLA4-Ig resulted in prolonged graft survival in 40% of the animals, whereas EP1013+CLTA4-Ig resulted in a significant increase in graft survival (91% >180 days; P = 0.01). Ex vivo analysis revealed that animals receiving EP1013 or EP1013+CTLA4-Ig had a reduced frequency of alloreactive interferon (IFN)-γ–secreting T-cells and an increased frequency of intragraft Foxp3+ Treg cells. Alloantibody assays indicated that treatment with EP1013 or CTLA4-Ig prevented allosensitization. CONCLUSIONS This study suggests that addition of caspase inhibitor therapy to costimulation blockade will improve clinical transplantation by minimizing immune stimulation and thus reduce the requirement for long-term immunosuppressive therapy. The approach also prevents allosensitization, which may be an important component of chronic graft loss in clinical transplantation.

OBJECTIVEIn part, activation of invariant natural killer T (iNKT)-cells with the superagonist α-galactosylceramide (α-GalCer) inhibits the development of T-cell–mediated autoimmune type 1 diabetes in NOD mice by inducing the downstream differentiation of antigen-presenting dendritic cells (DCs) to an immunotolerogenic state. However, in other systems iNKT-cell activation has an adjuvant-like effect that enhances rather than suppresses various immunological responses. Thus, we tested whether in some circumstances genetic variation would enable activated iNKT-cells to support rather than inhibit type 1 diabetes development.RESEARCH DESIGN AND METHODSWe tested whether iNKT-conditioned DCs in NOD mice and a major histocompatibility complex–matched C57BL/6 (B6) background congenic stock differed in capacity to inhibit type 1 diabetes induced by the adoptive transfer of pathogenic AI4 CD8 T-cells.RESULTSUnlike those of NOD origin, iNKT-conditioned DCs in the B6 background stock matured to a state that actually supported rather than inhibited AI4 T-cell–induced type 1 diabetes. The induction of a differing activity pattern of T-cell costimulatory molecules varying in capacity to override programmed death-ligand-1 inhibitory effects contributes to the respective ability of iNKT-conditioned DCs in NOD and B6 background mice to inhibit or support type 1 diabetes development. Genetic differences inherent to both iNKT-cells and DCs contribute to their varying interactions in NOD and B6.H2g7 mice.CONCLUSIONSThis great variability in the interactions between iNKT-cells and DCs in two inbred mouse strains should raise a cautionary note about considering manipulation of this axis as a potential type 1 diabetes prevention therapy in genetically heterogeneous humans.

Type 1 diabetes is a disorder caused by the autoimmune-mediated destruction of insulin-producing β-cells in the pancreas (1). Many promising intervention trials are currently underway or in development to prevent β-cell loss in patients with recent-onset type 1 diabetes and in individuals at increased risk for type 1 diabetes due to the presence of autoantibodies or elevated genetic risk (2). Despite this hope for future interventions, islet transplantation remains the only therapeutic option currently available for individuals with established type 1 diabetes when insulin therapy fails to maintain adequate metabolic control (3). Islet allograft transplantation has demonstrated great success in terms of restoring normoglycemia (4). Unfortunately, the long-term efficacy following transplantation has been limited due to chronic graft rejection (5). Thus, an optimal approach would involve an islet transplantation protocol that would prevent graft rejection without the need for potentially dangerous long-term and nonspecific immune suppression. Mesenchymal stem cells (MSCs) have been proposed to be one possible means to enhance current islet transplantation protocols (6). MSCs represent a population of nonhematopoetic precursor cells that have generated marked interest and attention for their capacity to elicit tissue regeneration (7–9). For the treatment of type 1 diabetes, the therapeutic potential of MSCs is potentially twofold. First, these cells …

OBJECTIVEThe autoimmune destruction of β-cells in type 1 diabetes results in a loss of insulin production and glucose homeostasis. As such, an immense interest exists for the development of therapies capable of attenuating this destructive process through restoration of proper immune recognition. Therefore, we investigated the ability of the immune-depleting agent antithymocyte globulin (ATG), as well as the mobilization agent granulocyte colony–stimulating factor (GCSF), to reverse overt hyperglycemia in the nonobese diabetic (NOD) mouse model of type 1 diabetes.RESEARCH DESIGN AND METHODSEffects of each therapy were tested in pre-diabetic and diabetic female NOD mice using measurements of glycemia, regulatory T-cell (CD4+CD25+Foxp3+) frequency, insulitis, and/or β-cell area.RESULTSHere, we show that combination therapy of murine ATG and GCSF was remarkably effective at reversing new-onset diabetes in NOD mice and more efficacious than either agent alone. This combination also afforded durable reversal from disease (>180 days postonset) in animals having pronounced hyperglycemia (i.e., up to 500 mg/dl). Additionally, glucose control improved over time in mice subject to remission from type 1 diabetes. Mechanistically, this combination therapy resulted in both immunological (increases in CD4-to-CD8 ratios and splenic regulatory T-cell frequencies) and physiological (increase in the pancreatic β-cell area, attenuation of pancreatic inflammation) benefits.CONCLUSIONSIn addition to lending further credence to the notion that combination therapies can enhance efficacy in addressing autoimmune disease, these studies also support the concept for utilizing agents designed for other clinical applications as a means to expedite efforts involving therapeutic translation.

OBJECTIVE Defining an optimal costimulatory blockade–based immune suppression protocol enabling engraftment and functional development of E42 pig embryonic pancreatic tissue in mice. RESEARCH DESIGN AND METHODS Considering that anti-CD40L was found to be thrombotic in humans, we sought to test alternative costimulatory blockade agents already in clinical use, including CTLA4-Ig, anti-LFA1, and anti-CD48. These agents were tested in conjunction with T-cell debulking by anti-CD4 and anti-CD8 antibodies or with conventional immunosuppressive drugs. Engraftment and functional development of E42 pig pancreatic tissue was monitored by immunohistology and by measuring pig insulin blood levels. RESULTS Fetal pig pancreatic tissue harvested at E42, or even as early as at E28, was fiercely rejected in C57BL/6 mice and in Lewis rats. A novel immune suppression comprising anti-LFA1, anti-CD48, and FTY720 afforded optimal growth and functional development. Cessation of treatment with anti-LFA1 and anti-CD48 at 3 months posttransplant did not lead to graft rejection, and graft maintenance could be achieved for >8 months with twice-weekly low-dose FTY720 treatment. These grafts exhibited normal morphology and were functional, as revealed by the high pig insulin blood levels in the transplanted mice and by the ability of the recipients to resist alloxan induced diabetes. CONCLUSIONS This novel protocol, comprising agents that simulate those approved for clinical use, offer an attractive approach for embryonic xenogeneic transplantation. Further studies in nonhuman primates are warranted.

OBJECTIVE We have previously reported a highly diabetogenic CD8 T-cell clone, G9C8, in the nonobese diabetic (NOD) mouse, specific to low-avidity insulin peptide B15-23, and cells responsive to this antigen are among the earliest islet infiltrates. We aimed to study the selection, activation, and development of the diabetogenic capacity of these insulin-reactive T-cells. RESEARCH DESIGN AND METHODS We generated a T-cell receptor (TCR) transgenic mouse expressing the cloned TCR Vα18/Vβ6 receptor of the G9C8 insulin-reactive CD8 T-cell clone. The mice were crossed to TCRCα−/− mice so that the majority of the T-cells expressed the clonotypic TCR, and the phenotype and function of the cells was investigated. RESULTS There was good selection of CD8 T-cells with a predominance of CD8 single-positive thymocytes, in spite of thymic insulin expression. Peripheral lymph node T-cells had a naïve phenotype (CD44lo, CD62Lhi) and proliferated to insulin B15-23 peptide and to insulin. These cells produced interferon-γ and tumor necrosis factor-α in response to insulin peptide and were cytotoxic to insulin peptide–coated targets. In vivo, the TCR transgenic mice developed insulitis but not spontaneous diabetes. However, the mice developed diabetes on immunization, and the activated transgenic T-cells were able to transfer diabetes to immunodeficient NOD.scid mice. CONCLUSIONS Autoimmune CD8 T-cells responding to a low-affinity insulin B-chain peptide escape from thymic negative selection and require activation in vivo to cause diabetes.

OBJECTIVE— A restricted region of proinsulin located in the B chain and adjacent region of C-peptide has been shown to contain numerous candidate epitopes recognized by CD8+ T-cells. Our objective is to characterize HLA class I–restricted epitopes located within the preproinsulin leader sequence.RESEARCH DESIGN AND METHODS— Seven 8- to 11-mer preproinsulin peptides carrying anchoring residues for HLA-A1, -A2, -A24, and -B8 were selected from databases. HLA-A2–restricted peptides were tested for immunogenicity in transgenic mice expressing a chimeric HLA-A*0201/β2-microglobulin molecule. The peptides were studied for binding to purified HLA class I molecules, selected for carrying COOH-terminal residues generated by proteasome digestion in vitro and tested for recognition by human lymphocytes using an ex vivo interferon-γ (IFN-γ) ELISpot assay.RESULTS— Five HLA-A2–restricted peptides were immunogenic in transgenic mice. Murine T-cell clones specific for these peptides were cytotoxic against cells transfected with the preproinsulin gene. They were recognized by peripheral blood mononuclear cells (PBMCs) from 17 of 21 HLA-A2 type 1 diabetic patients. PBMCs from 25 of 38 HLA-A1, -A2, -A24, or -B8 patients produced IFN-γ in response to six preproinsulin peptides covering residues 2–25 within the preproinsulin region. In most patients, the response was against several class I–restricted peptides. T-cells recognizing preproinsulin peptide were characterized as CD8+ T-cells by staining with peptide/HLA-A2 tetramers.CONCLUSIONS— We defined class I–restricted epitopes located within the leader sequence of human preproinsulin through in vivo (transgenic mice) and ex vivo (diabetic patients) assays, illustrating the possible role of preproinsulin-specific CD8+ T-cells in human type 1 diabetes.

OBJECTIVE Anti-tissue transglutaminase (TG2) antibodies are the serological marker of celiac disease. Given the close association between celiac disease and type 1 diabetes, we investigated the production and deposition of anti-TG2 antibodies in the jejunal mucosa of type 1 diabetic children. RESEARCH DESIGN AND METHODS Intestinal biopsies were performed in 33 type 1 diabetic patients with a normal mucosal architecture: 14 had high levels (potential celiac disease patients) and 19 had normal levels of serum anti-TG2 antibodies. All biopsy specimens were investigated for intestinal deposits of IgA anti-TG2 antibodies by double immunofluorescence. In addition, an antibody analysis using the phage display technique was performed on the intestinal biopsy specimens from seven type 1 diabetic patients, of whom four had elevated and three had normal levels of serum anti-TG2 antibodies. RESULTS Immunofluorescence studies showed that 11 of 14 type 1 diabetic children with elevated levels and 11 of 19 with normal serum levels of anti-TG2 antibodies presented with mucosal deposits of such autoantibodies. The phage display analysis technique confirmed the intestinal production of the anti-TG2 antibodies; however, whereas the serum-positive type 1 diabetic patients showed a preferential use of the VH5 antibody gene family, in the serum-negative patients the anti-TG2 antibodies belonged to the VH1 and VH3 families, with a preferential use of the latter. CONCLUSIONS Our findings demonstrate that there is intestinal production and deposition of anti-TG2 antibodies in the jejunal mucosa of the majority of type 1 diabetic patients. However, only those with elevated serum levels of anti-TG2 antibodies showed the VH usage that is typical of the anti-TG2 antibodies that are produced in patients with celiac disease.

OBJECTIVE—Regulatory T-cells (Tregs) have catalyzed the field of immune regulation. However, translating Treg-based therapies from animal models of autoimmunity to human clinical trials requires robust methods for the isolation and expansion of these cells—a need forming the basis for these studies. RESEARCH DESIGN AND METHODS—Tregs from recent-onset type 1 diabetic patients and healthy control subjects were isolated by fluorescence-activated cell sorting and compared for their capacity to expand in vitro in response to anti-CD3–anti-CD28–coated microbeads and IL-2. Expanded cells were examined for suppressive function, lineage markers and FOXP3, and cytokine production. RESULTS—Both CD4+CD127lo/− and CD4+CD127lo/−CD25+ T-cells could be expanded and used as Tregs. However, expansion of CD4+CD127lo/− cells required the addition of rapamycin to maintain lineage purity. In contrast, expansion of CD4+CD127lo/−CD25+ T-cells, especially the CD45RA+ subset, resulted in high yield, functional Tregs that maintained higher FOXP3 expression in the absence of rapamycin. Tregs from type 1 diabetic patients and control subjects expanded similarly and were equally capable of suppressing T-cell proliferation. Regulatory cytokines were produced by Tregs after culture; however, a portion of FOXP3+ cells were capable of producing interferon (IFN)-γ after reactivation. IFN-γ production was observed from both CD45RO+ and CD45RA+ Treg populations. CONCLUSIONS—The results support the feasibility of isolating Tregs for in vitro expansion. Based on expansion capacity, FOXP3 stability, and functional properties, the CD4+CD127lo/−CD25+ T-cells represent a viable cell population for cellular therapy in this autoimmune disease.

OBJECTIVE—All-trans retinoic acid (ATRA), a potent derivative of vitamin A, can regulate immune responses. However, its role in inducing immune tolerance associated with the prevention of islet inflammation and inhibition of type 1 diabetes remains unclear.RESEARCH DESIGN AND METHODS—We investigated the mechanisms underlying the potential immunoregulatory effect of ATRA on type 1 diabetes using an adoptive transfer animal model of the disease.RESULTS—Our data demonstrated that ATRA treatment inhibited diabetes in NOD mice with established insulitis. In addition, it suppressed interferon (IFN)-γ–producing CD4+ and CD8+ T effector (Teff) cells and expanded T regulatory (Treg) cells in recipient mice transferred with diabetic NOD splenocytes, without affecting either interleukin (IL)-17 –or IL-4–producing cells. Consistent with these results, ATRA reduced T-bet and STAT4 expression in T-cells and decreased islet-infiltrating CD8+ T-cells, suppressing their activation and IFN-γ/granzyme B expression. Depletion of CD4+CD25+ Treg cells impaired the inhibitory effect of ATRA on islet-infiltrating T-cells and blocked its protective effect on diabetes. Therefore, ATRA treatment induced Treg cell–dependent immune tolerance by suppressing both CD4+ and CD8+ Teff cells while promoting Treg cell expansion.CONCLUSIONS—These results demonstrate that ATRA treatment promoted in vivo expansion of Treg cells and induced Treg cell–dependent immune tolerance by suppressing IFN-γ–producing T-cells, without affecting Th17 cells. Our study also provides novel insights into how ATRA induces immune tolerance in vivo via its effects on Teff and Treg cells.

OBJECTIVES—To investigate a B-cell–depleting strategy to reverse diabetes in naïve NOD mice.RESEARCH DESIGN AND METHODS—We targeted the CD22 receptor on B-cells of naïve NOD mice to deplete and reprogram B-cells to effectively reverse autoimmune diabetes.RESULTS—Anti-CD22/cal monoclonal antibody (mAb) therapy resulted in early and prolonged B-cell depletion and delayed disease in pre-diabetic mice. Importantly, when new-onset hyperglycemic mice were treated with the anti-CD22/cal mAb, 100% of B-cell–depleted mice became normoglycemic by 2 days, and 70% of them maintained a state of long-term normoglycemia. Early therapy after onset of hyperglycemia and complete B-cell depletion are essential for optimal efficacy. Treated mice showed an increase in percentage of regulatory T-cells in islets and pancreatic lymph nodes and a diminished immune response to islet peptides in vitro. Transcriptome analysis of reemerging B-cells showed significant changes of a set of proinflammatory genes. Functionally, reemerging B-cells failed to present autoantigen and prevented diabetes when cotransferred with autoreactive CD4+ T-cells into NOD.SCID hosts.CONCLUSIONS—Targeting CD22 depletes and reprograms B-cells and reverses autoimmune diabetes, thereby providing a blueprint for development of novel therapies to cure autoimmune diabetes.