Delayed Diabetes Onset Research Articles

Recombinant adenoviral expression of IL-10 protects beta cell from impairment induced by pro-inflammatory cytokine

Interleukin-10 (IL-10) is a pleiotropic immunosuppressive and immunostimulatory cytokine. In autoimmune diabetes of the nonobese diabetic (NOD) mouse, IL-10 has exhibited paradoxical effects. Systemic IL-10 expression prevented or delayed diabetes onset in NOD mice while local expression of IL-10 did not. As antigen-presenting cells (APCs) play a central role in the generation of primary T cell responses, the direct role of this gene in pancreatic beta (β) cell is not clear. The effects of IL-10 on the protection of β cells in vitro were examined. In the present study, we examined the effects of adenovirus vector-mediated murine IL-10 (mIL-10) gene transfer to islet cell line RINm5F cells in vitro and to explore if IL-10 overexpression may prevent cytokine-mediated cytotoxicity. We had established the recombinant adenovirus vector containing mIL-10 genes (Ad-mIL-10) successfully. After infection of Ad-mIL-10, both mRNA and protein were expressed in RINm5F cells. Moreover, RINm5F cells secreted IL-10 protein into culture medium. Ad-mIL-10 prevented IL-1β-mediated nitric oxide production from β cells in vitro as well as the suppression of β cells function as determined by glucose-stimulated insulin production. Furthermore, Ad-mIL-10 gene transfer led to a profound reduction of Fas-expressing β cells and caspase-3 activity which were induced by IL-1β and the apoptotic rates of Ad-mIL-10 group were decreased. These findings show that IL-10 gene transfer to β cells may be beneficial in maintaining cells function, protecting islet cells from apoptosis-mediated by factors, which showed the potential therapy for type 1 diabetes mellitus.

Chronic Administration of the Glucagon-Like Peptide-1 Analog, Liraglutide, Delays the Onset of Diabetes and Lowers Triglycerides in UCD-T2DM Rats

OBJECTIVEThe efficacy of liraglutide, a human glucagon-like peptide-1 (GLP-1) analog, to prevent or delay diabetes in UCD-T2DM rats, a model of polygenic obese type 2 diabetes, was investigated.RESEARCH DESIGN AND METHODSAt 2 months of age, male rats were divided into three groups: control, food-restricted, and liraglutide. Animals received liraglutide (0.2 mg/kg s.c.) or vehicle injections twice daily. Restricted rats were food restricted to equalize body weights to liraglutide-treated rats. Half of the animals were followed until diabetes onset, whereas the other half of the animals were killed at 6.5 months of age for tissue collection.RESULTSBefore diabetes onset energy intake, body weight, adiposity, and liver triglyceride content were higher in control animals compared with restricted and liraglutide-treated rats. Energy-restricted animals had lower food intake than liraglutide-treated animals to maintain the same body weights, suggesting that liraglutide increases energy expenditure. Liraglutide treatment delayed diabetes onset by 4.1 ± 0.8 months compared with control (P < 0.0001) and by 1.3 ± 0.8 months compared with restricted animals (P < 0.05). Up to 6 months of age, energy restriction and liraglutide treatment lowered fasting plasma glucose and A1C concentrations compared with control animals. In contrast, liraglutide-treated animals exhibited lower fasting plasma insulin, glucagon, and triglycerides compared with both control and restricted animals. Furthermore, energy-restricted and liraglutide-treated animals exhibited more normal islet morphology.CONCLUSIONSLiraglutide treatment delays the development of diabetes in UCD-T2DM rats by reducing energy intake and body weight, and by improving insulin sensitivity, improving lipid profiles, and maintaining islet morphology.

Experimental extracorporeal photopheresis therapy prevents type 1 diabetes in non-obese diabetic mice (96.3)

Abstract In our previous studies, we demonstrated that infusion of apoptotic cells significantly prevented type 1 diabetes (T1D) in non-obese diabetic (NOD) mouse. Extracorporeal photopheresis (ECP) is an apoptotic cell-based therapy in clinic for immune-mediated disorders. In this study we examined experimental ECP therapy in T1D prevention in NOD mice. We discovered that five weekly intravenous injections of ECP-treated NOD spleen cells significantly delayed diabetes onset when NOD mice started to receive treatment at 8 weeks of age. Further cell dose studies demonstrated that low dose ECP-treated spleen cells as low as 2x105/injection/mouse had similar diabetes protection compared to high dose (5x106). In contrast to ECP therapy alone, ECP therapy combined with β cell antigens appeared to improve the protective effect with markedly reduced insulitis in pancreas. ECP and ECP plus β cell antigen therapies increased Foxp3+ Tregs in spleen, and β cell antigen-specific T cell proliferation was significantly suppressed in vivo in these two groups. In addition, we found that ECP therapy did not induce global immunosuppression as well as autoimmunity against nuclear materials. In conclusion, ECP therapy is a safe and effective approach in T1D prevention and has great potential for clinical translation to treat human T1D.

Experimental extracorporeal photopheresis therapy significantly delays the development of diabetes in non-obese diabetic mice

In our previous studies, we demonstrated that infusion of apoptotic cells significantly prevented type 1 diabetes (T1D) in non-obese diabetic (NOD) mice. Extracorporeal photopheresis (ECP) is an apoptotic cell-based therapy used clinically for immune-mediated disorders. In this study, we examined the effect that intravenous delivery of apoptotic cells (ECP-treated) has in the prevention of T1D in NOD mice. We discovered that five weekly injections of ECP-treated NOD spleen cells, beginning at 8 weeks of age, significantly delayed diabetes onset. Furthermore, cell dose studies demonstrated that low dose ECP-treated spleen cells (2x10(5) cells/injection/mouse) had similar protective effects as compared to high dose (5x10(6) cells/injection). In contrast to ECP-treated cells alone, ECP-treated cells combined with beta cell antigens appeared to improve the protective effect as shown by the marked reduction in insulitis in the islets. Delivery of ECP-treated spleen cells or ECP-treated spleen cells plus beta cell antigen increased Foxp3(+) Tregs, and beta cell antigen-specific T cell proliferation was significantly suppressed in vivo in these two groups. In addition, we found that ECP-treated cells did not induce global immunosuppression or autoimmunity against nuclear antigens. In conclusion, ECP-treated cells provide a safe and effective approach in T1D prevention, suggesting that clinical ECP has great potential for managing human T1D.

Ileal Interposition Surgery Improves Glucose and Lipid Metabolism and Delays Diabetes Onset in the UCD-T2DM Rat

Bariatric surgery has been shown to reverse type 2 diabetes; however, mechanisms by which this occurs remain undefined. Ileal interposition (IT) is a surgical model that isolates the effects of increasing delivery of unabsorbed nutrients to the lower gastrointestinal tract. In this study we investigated effects of IT surgery on glucose tolerance and diabetes onset in UCD-T2DM (University of California at Davis type 2 diabetes mellitus) rats, a polygenic obese animal model of type 2 diabetes. IT or sham surgery was performed on 4-month-old male UCD-T2DM rats. All animals underwent oral glucose tolerance testing (OGTT). A subset was killed 2 months after surgery for tissue analyses. The remainder was followed until diabetes onset and underwent oral fat tolerance testing (OFTT). IT surgery delayed diabetes onset by 120 +/- 49 days compared with sham surgery (P < .05) without a difference in body weight. During OGTT, IT-operated animals exhibited lower plasma glucose excursions (P < .05), improved early insulin secretion (P < .01), and 3-fold larger plasma glucagon-like peptide-1(7-36) (GLP-1(7-36)) excursions (P < .001), and no difference in glucose-dependent insulinotropic polypeptide responses compared with sham-operated animals. Total plasma peptide YY (PYY) excursions during OFTT were 3-fold larger in IT-operated animals (P < .01). IT-operated animals exhibited lower adiposity (P < .05), smaller adipocyte size (P < .05), 25% less ectopic lipid deposition, lower circulating lipids, and greater pancreatic insulin content compared with sham-operated animals (P < .05). IT surgery delays the onset of diabetes in UCD-T2DM rats which may be related to increased nutrient-stimulated secretion of GLP-1(7-36) and PYY and improvements of insulin sensitivity, beta-cell function, and lipid metabolism.

Dietary fructose accelerates the development of diabetes in UCD-T2DM rats: amelioration by the antioxidant, alpha-lipoic acid.

Sustained fructose consumption has been shown to induce insulin resistance and glucose intolerance, in part, by promoting oxidative stress. Alpha-lipoic acid (LA) is an antioxidant with insulin-sensitizing activity. The effect of sustained fructose consumption (20% of energy) on the development of T2DM and the effects of daily LA supplementation in fructose-fed University of California, Davis-Type 2 diabetes mellitus (UCD-T2DM) rats, a model of polygenic obese T2DM, was investigated. At 2 mo of age, animals were divided into three groups: control, fructose, and fructose + LA (80 mg LA.kg body wt(-1).day(-1)). One subset was followed until diabetes onset, while another subset was euthanized at 4 mo of age for tissue collection. Monthly fasted blood samples were collected, and an intravenous glucose tolerance test (IVGTT) was performed. Fructose feeding accelerated diabetes onset by 2.6 +/- 0.5 mo compared with control (P < 0.01), without affecting body weight. LA supplementation delayed diabetes onset in fructose-fed animals by 1.0 +/- 0.7 mo (P < 0.05). Fructose consumption lowered the GSH/GSSG ratio, while LA attenuated the fructose-induced decrease of oxidative capacity. Insulin sensitivity, as assessed by IVGTT, decreased in both fructose-fed and fructose + LA-supplemented rats. However, glucose excursions in fructose-fed LA-supplemented animals were normalized to those of control via increased glucose-stimulated insulin secretion. Fasting plasma triglycerides were twofold higher in fructose-fed compared with control animals at 4 mo, and triglyceride exposure during IVGTT was increased in both the fructose and fructose + LA groups compared with control. In conclusion, dietary fructose accelerates the onset of T2DM in UCD-T2DM rats, and LA ameliorates the effects of fructose by improving glucose homeostasis, possibly by preserving beta-cell function.

Pre-existing autoimmunity determines type 1 diabetes outcome after Flt3-ligand treatment

Redirection of immune responses by manipulation of antigen-presenting cells is an emerging strategy for immunosuppressive treatment of autoimmune diseases. In vivo expansion of dendritic cells (DC) by Fms-like tyrosine kinase-3 (Flt3)-Ligand (FL) treatment was shown to delay diabetes onset in the NOD model of autoimmune diabetes. However, we show here that Flt3 stimulation actually accelerates autoimmunity when autoreactive CD8 T cells are detectable in blood prior to treatment. With autoreactive CD8 cells present, the capacity of FL to expand DCs and induce Treg remained intact, but both numbers and the functional response of islet-specific CD8s were boosted. Also, the inhibitory receptor PD-1 on (autoreactive) CD8 T cells and its ligand PD-L1 on Treg were no longer upregulated. These data highlight the need to pre-screen for T cell autoreactivity prior to generalized DC expansion and illustrate how accelerated disease can occur when the intended initiation of regulatory mechanisms is impaired later in diabetogenesis.

Change you can B(cell)eive in: recent progress confirms a critical role for B cells in type 1 diabetes

Here we review extant recent findings regarding the multiple roles of B cells in type 1 diabetes (T1D) and discuss how autoreactive B cells may become activated by a breach in B cell tolerance, and thereby initiate disease. Finally, we discuss the use of B cell-targeted therapies for treatment of autoimmunity. Anti-CD20-specific depletion of B cells prevents and reverses diabetes in human CD20/non-obese diabetic (NOD) mice. Correspondingly, in nontransgenic NOD mice, B cells are effectively depleted with high dose antimouse CD20 mAbs of varying isotypes, and this also prevents diabetes in more than 60% of the mice when administered early, and significantly delays disease in 15-week-old animals. A separate study revealed that targeting B cells with anti-CD22/cal monoclonal antibody therapy delays diabetes onset in prediabetic NOD mice and restores normoglycemia in new-onset hyperglycemic NOD mice. In humans, a clinical trial of rituximab in new onset type 1 diabetics has yielded promising preliminary findings. B cells are major players in T1D in humans, and clearly essential for disease development in the NOD mouse model of T1D. In this review, we discuss the silencing of autoreactive B cells and how failure of this process may contribute to autoimmunity. Further, we describe the most recent advances in studies of therapeutic effects of B cell depletion in T1D, and provide recent data indicating the diverse functions by which B cells may mediate disease.

Targeting B-cells Mitigates Autoimmune Diabetes in NOD Mice: What Is Plan B?

In this issue of Diabetes , Grey and colleagues (1) demonstrate that therapeutic B-cell depletion delays diabetes onset and reduces diabetes incidence in NOD mice. B-cell depletion in pre-diabetic NOD mice was accomplished using an extended regime of recombinant B-cell maturation antigen (BCMA)-Fc chimerized protein that targets B-lymphocyte stimulator (BLyS)/B-cell–activating factor of the tumor necrosis factor family (BAFF)—a cytokine critical for maintenance of the peripheral B-cell pool. This follows recent studies demonstrating significant effects of B-cell depletion on diabetes onset and severity (2–5); however, no other studies have reported profound and complete protection from hyperglycemia as observed here. Following B-cell depletion therapy during 9–15 weeks of age, NOD mice remained diabetes free for ≥50 weeks of age, even after B-cell reconstitution. An increase in CD25+Foxp3+CD4+ regulatory T-cells (Tregs) following B-cell depletion may mediate prolonged tolerance given that the CD25 monoclonal antibody (mAb) treatment neutralized the long-term therapeutic benefits of B-cell depletion (Fig. 1). This mechanism may explain why B-cell–deficient NOD.μMT mice do not develop hyperglycemia given that autoimmune diabetes was also precipitated in these mice by Treg depletion. FIG. 1. Model for autoantigen presentation in B-cell–depleted NOD mice. Autoantigen presentation is normally balanced between B-cells and dendritic cells (DCs) in mice (16). A : NOD autoantigen presentation. However, B-cell cognate presentation of pancreatic autoantigens may dominate in NOD mice because B-cell selection (17) and innate cell APC function are impaired (18). As a …

Immunoregulatory mechanisms triggered by viral infections protect from type 1 diabetes in mice

Type 1 diabetes (T1D) is an autoimmune disease that is caused by the destruction of insulin-producing beta cells. Viral infections induce immune responses that can damage beta cells and promote T1D or on the other hand prevent the development of the disease. However, the opposing roles of viral infections in T1D are not understood mechanistically. We report here that viruses that do not inflict damage on beta cells provided protection from T1D by triggering immunoregulatory mechanisms. Infection of prediabetic NOD mice with Coxsackie virus B3 or lymphocytic choriomeningitis virus (LCMV) delayed diabetes onset and reduced disease incidence. Delayed T1D onset was due to transient upregulation of programmed cell death-1 ligand 1 (PD-L1) on lymphoid cells, which prevented the expansion of diabetogenic CD8+ T cells expressing programmed cell death-1 (PD-1). Reduced T1D incidence was caused by increased numbers of invigorated CD4+CD25+ Tregs, which produced TGF-beta and maintained long-term tolerance. Full protection from T1D resulted from synergy between PD-L1 and CD4+CD25+ Tregs. Our results provide what we believe to be novel mechanistic insight into the role of viruses in T1D and should be valuable for prospective studies in humans.

BTLA targeting modulates lymphocyte phenotype, function, and numbers and attenuates disease in nonobese diabetic mice

The novel coinhibitory receptor BTLA may have a regulatory role in maintaining peripheral tolerance; however, its role in autoimmune diabetes is unknown. In this study, we show that anti-BTLA mAb 6F7 selectively depleted pathogenic B and CD4+ T(H) cells; enhanced the proportion of cells with the forkhead box p3+ PD-1+CD4+ regulatory T phenotype; and increased the production of potentially protective (IL-10) and detrimental (IL-2, IFN-gamma) cytokines in NOD mice. As interactions between BTLA and PD-1 coinhibitory pathways have been described in the cardiac allograft model, we also investigated if these pathways may have significant interaction in autoimmune diabetes. Anti-BTLA inhibited anti-PD-1-potentiated total IL-12 (p40+p70) production, suggesting the possibility that anti-BTLA may have a greater effect in the setting of anti-PD-1-triggered diabetes. To test this, NOD mice at 4 and 10 weeks of age were treated with anti-BTLA mAb, anti-PD-1 mAb, both mAb, or isotype control and were monitored for diabetes development. Although anti-BTLA mAb delayed diabetes onset significantly in 10- but not 4-week-old NOD mice, anti-BTLA mAb attenuated anti-PD-1-induced diabetes in both age groups. Hence, strategies targeting BTLA+ lymphocytes or therapies enhancing the BTLA-negative cosignal may prove valuable in treating autoimmune diabetes.

AEB-071 has minimal impact on onset of autoimmune diabetes in NOD mice

Protein kinase C (PKC) is an important signaling enzyme in the activation and regulation of T lymphocytes. T-cell-mediated destruction of β-cells is a characteristic feature of autoimmune (Type 1) diabetes. Here we explore the ability of PKC inhibition, using the PKC inhibitor AEB-071 (AEB), to reduce disease in two animal models of spontaneous autoimmune diabetes (non-obese diabetic (NOD) mouse and biobreeding rat (BB)). NOD mice were treated with AEB for 4 weeks, starting at either 4 weeks of age (prior to the development of insulitis) or at 8 weeks of age, once insulitis is present. Animals treated with AEB during the effector phase of the disease (treatment onset at 8 weeks of age), showed a 2-week delay in diabetes onset (p < 0.05). In these animals, the extent of insulitis was lower than in vehicle-treated controls; however, neither serum autoimmune anti-GAD65 antibody levels nor pancreatic insulin content were different between experimental groups. Overall, inhibition of PKC can mildly reduce lymphocytic infiltrate of pancreatic islets and modestly delay onset of autoimmune diabetes in NOD mice. AEB, a T-cell-targeted immunosuppressive strategy, is only sufficient as a monothereapy to modestly delay onset of autoimmune disease in the NOD mouse.

Efficacy of the dipeptidyl peptidase IV inhibitor isoleucine thiazolidide (P32/98) in fatty Zucker rats with incipient and manifest impaired glucose tolerance

Incretin enhancers are a new class of antidiabetic drugs with promising therapeutic potential for type 2 diabetes. Therapeutic intervention in prediabetes is an attractive strategy for preventing or delaying diabetes onset. The aim of the present study was to investigate the therapeutic effects of incretin enhancement on incipient impaired glucose tolerance (iIGT) and manifest IGT (mIGT) using the dipeptidyl peptidase IV (DPP-4) inhibitor P32/98- and fatty Zucker rat (ZR, fa/fa) as a model. ZRs were classified into groups with iIGT and mIGT (n = 10 per group). P32/98 (21.61 mg/kg body weight) was administered orally to ZR with iIGT and mIGT once daily for 6 and 3 weeks respectively. Assessments included body weight, morning blood glucose and insulin, oral glucose tolerance test (oGTT; 2 g glucose/kg), plasma parameters and blood glucose day-night profile (DNP). In addition, glucose responsiveness of isolated islets and islet morphology were analysed. P32/98 decreased non-fasting morning blood glucose more effectively in ZR with iIGT than in ZR with mIGT. Compared with study entry, P32/98 improved DNP of blood glucose in ZR with mIGT and nearly normalized DNP in ZR with iIGT. An acute bolus of inhibitor reduced glucose load during oGTT in rats chronically treated with placebo or P32/98. In contrast to placebo-treated rats, rats receiving long-term treatment with P32/98 required less insulin during oGTT. This effect was larger in rats with iIGT vs. rats with mIGT. In isolated pancreatic islets of ZR with mIGT, treatment with P32/98 decreased pancreatic insulin content and increased glucose responsiveness, while the beta-cell volume density was unaffected. P32/98 significantly reduced triglycerides and non-esterified fatty acids. Intestinal growth was comparable between inhibitor- and placebo-treated fatty rats. Enhancement of incretin with the DPP-4 inhibitor P32/98 has therapeutic effects in hyperinsulinaemia, hyperglycaemia and IGT in ZR with iIGT and mIGT. Apparently, administration of P32/98 in ZR with iIGT results in more efficient beta-cell function, which is associated with less need for insulin to cope with deterioration of glucose tolerance. Importantly, P32/98 has a strong effect on dyslipidaemia in mIGT. P32/98 has no side effect on intestinal growth. Daily intake of P32/98 is a promising strategy for treatment of glucose intolerance and has the potential to prevent type 2 diabetes.

The ability of dendritic cells to prevent diabetes development in NOD mice depends on their production of high levels of IL‐10 versus low levels of IL‐12

NOD mice, similar to diabetic patients, exhibit various defects in different types of immune cells, including dendritic cells (DC) that produce pro‐inflammatory cytokines, and regulatory T cells. Recognition of TLR2 can lead to immune evasion of various microorganisms via induction of tolerogenic APC and regulatory cells. The goal of this study was to induce tolerogenic NOD DC able to prevent diabetes. DC were stimulated for 24 hrs with two TLR2 agonists, lipoteichoic acid (LTA) from S. aureus and Lactobacillus. DC stimulated with LTA produced 50 times more IL‐12 than IL‐10, and mediated acceleration of diabetes development when transferred into NOD mice. In contrast, high doses of Lactobacilli (LC) favored the production of IL‐10 versus IL‐12. Transfer of DC treated with high‐dose LC, not low‐dose LC, into NOD mice delayed diabetes onset and decreased diabetes incidence. Interestingly, DC treated with high‐dose LC produced 5 times more IL‐10 than those treated with low‐dose LC. Finally, significant increases in IL‐10 levels were detected in most of the samples from LC DC‐injected NOD mice. These data indicate that the levels of IL‐10 versus IL‐12 produced by DC cultured with various stimuli correlates with the ability of those cells to prevent diabetes in NOD mice. IL‐10 may play a significant role in diabetes prevention either directly, by suppressing pro‐inflammatory responses, and/or by inducing regulatory cells.

B Lymphocyte Depletion by CD20 Monoclonal Antibody Prevents Diabetes in Nonobese Diabetic Mice despite Isotype-Specific Differences in FcγR Effector Functions

NOD mice deficient for B lymphocytes from birth fail to develop autoimmune or type 1 diabetes. To assess whether B cell depletion influences type 1 diabetes in mice with an intact immune system, NOD female mice representing early and late preclinical stages of disease were treated with mouse anti-mouse CD20 mAbs. Short-term CD20 mAb treatment in 5-wk-old NOD female mice reduced B cell numbers by approximately 95%, decreased subsequent insulitis, and prevented diabetes in >60% of littermates. In addition, CD20 mAb treatment of 15-wk-old NOD female mice significantly delayed, but did not prevent, diabetes onset. Protection from diabetes did not result from altered T cell numbers or subset distributions, or regulatory/suppressor T cell generation. Rather, impaired CD4+ and CD8+ T cell activation in the lymph nodes of B cell-depleted NOD mice may delay diabetes onset. B cell depletion was achieved despite reduced sensitivity of NOD mice to CD20 mAbs compared with C57BL/6 mice. Decreased B cell depletion resulted from deficient FcgammaRI binding of IgG2a/c CD20 mAbs and 60% reduced spleen monocyte numbers, which in combination reduced Ab-dependent cellular cytotoxicity. With high-dose CD20 mAb treatment (250 microg) in NOD mice, FcgammaRIII and FcgammaRIV compensated for inadequate FcgammaRI function and mediated B cell depletion. Thereby, NOD mice provide a model for human FcgammaR polymorphisms that reduce therapeutic mAb efficacy in vivo. Moreover, this study defines a new, clinically relevant approach whereby B cell depletion early in the course of disease development may prevent diabetes or delay progression of disease.

Exendin-4 Modulates Diabetes Onset in Nonobese Diabetic Mice

Activation of the glucagon-like peptide-1 receptor (GLP-1R) is associated with expansion of beta-cell mass due to stimulation of cell proliferation and induction of antiapoptotic pathways coupled to beta-cell survival. Although the GLP-1R agonist Exenatide (exendin-4) is currently being evaluated in subjects with type 1 diabetes, there is little information available about the efficacy of GLP-1R activation for prevention of experimental type 1 diabetes. We examined the consequences of exendin-4 (Ex-4) administration (100 ng once daily and 2 microg twice daily) on diabetes onset in nonobese diabetic mice beginning at either 4 or 9 wk of age prior to the onset of diabetes. Ex-4 treatment for 26 wk (2 microg twice daily) initiated at 4 wk of age delayed the onset of diabetes (P = 0.007). Ex-4-treated mice also exhibited a significant reduction in insulitis scores, enhanced beta-cell mass, and improved glucose tolerance. Although GLP-1R mRNA transcripts were detected in spleen, thymus, and lymph nodes from nonobese diabetic mice, Ex-4 treatment was not associated with significant changes in the numbers of CD4+ or CD8+ T cells or B cells in the spleen. However, Ex-4 treatment resulted in an increase in the number of CD4+ and CD8+ T cells in the lymph nodes and a reduction in the numbers of CD4+CD25+Foxp3+ regulatory T cells in the thymus but not in lymph nodes. These findings demonstrate that sustained GLP-1R activation in the absence of concomitant immune intervention may be associated with modest but significant delay in diabetes onset in a murine model of type 1 diabetes.

Murine Gammaherpesvirus-68 Infection Alters Self-Antigen Presentation and Type 1 Diabetes Onset in NOD Mice

Recent research in line with the "hygiene hypothesis" has implicated virus infection in the delay or prevention of autoimmunity in murine models of type 1 diabetes such as the NOD mouse. We found that intraperitoneal or intranasal infection of NOD mice with the murine gammaherpesvirus-68 (MHV-68) significantly delayed diabetes onset in an age-dependent manner. The acute phase following intraperitoneal infection was associated with significantly reduced trafficking of autoreactive BDC2.5NOD CD4(+) T cells to the pancreas but not the pancreatic lymph node (PLN); this was not as a result of MHV-68 M3 pan-chemokine binding protein expression. Autoreactive BDC2.5NOD CD4(+) T cells within the PLN of MHV-68 infected mice were significantly more naive and proliferated to a lesser extent than those cells within the PLN of uninfected mice. These changes in autoreactive CD4(+) T cell activation were associated with reduced dendritic cell endocytosis and soluble Ag presentation but were not as a result of virally induced IL-10 or changes in Ag-specific regulatory T cell populations.

Essential Role for Signal Transducer and Activator of Transcription-1 in Pancreatic β-Cell Death and Autoimmune Type 1 Diabetes of Nonobese Diabetic Mice

We have reported important roles for signal transducer and activator of transcription-1 (STAT1) in pancreatic beta-cell death by cytokines in vitro. However, in vivo evidence supporting the role for STAT1 in natural type 1 diabetes has not been reported. We studied whether STAT1 plays an important role in the development of natural type 1 diabetes. We produced nonobese diabetic (NOD)/STAT1(-/-) mice by backcrossing and studied the in vivo role of STAT1 in beta-cell death and type 1 diabetes. STAT1(-/-) islet cells were resistant to death by interferon (IFN)-gamma/tumor necrosis factor (TNF)-alpha or IFN-gamma/interleukin (IL)-1 beta combination. Cytochrome c translocation by IFN-gamma/TNF-alpha was abrogated in STAT1(-/-) islet cells. The induction of X-linked inhibitor of apoptosis protein by TNF-alpha was inhibited by IFN-gamma in STAT1(+/-) islet cells but not in STAT1(-/-) islet cells. Inducible nitric oxide (NO) synthase induction and NO production by IFN-gamma/IL-1 beta were impaired in STAT1(-/-) islet cells. Strikingly, diabetes and insulitis were completely abrogated in NOD/STAT1(-/-) mice. Development of diabetes after CD4(+) diabetogenic T-cell transfer was inhibited in those mice. STAT1(-/-) neonatal pancreata were not destroyed when grafted into diabetic NOD/BDC2.5 mice that developed CD4(+) T-cell-dependent islet cell death. In NOD/STAT1(-/-) mice, autoreactive T-cell priming was not impaired, but Th1 differentiation was impaired. A janus kinase (JAK) 2 inhibitor upstream of STAT1 attenuated islet cell death by IFN-gamma/TNF-alpha or IFN-gamma/IL-1 beta and delayed diabetes onset in NOD/BDC2.5-SCID mice. These data demonstrate a critical role for STAT1 in beta-cell death, T-cell immunoregulation, and type 1 diabetes in vivo and suggest potential therapeutic values of STAT1 or JAK inhibitors in the treatment/prevention of type 1 diabetes.

Participant and Parent Experiences in the Parenteral Insulin Arm of the Diabetes Prevention Trial for Type 1 Diabetes

To assess participant and parent experiences in the parenteral insulin arm of the Diabetes Prevention Trial for Type 1 Diabetes (DPT-1). Before trial results were publicized, surveys were completed by 82 intervention participants (the intervention group) (who received annual 4-day insulin infusions and daily insulin injections), 81 closely monitored control subjects (the closely monitored group), and 135 parents of children in the trial. Survey results suggest that participant perspective (adult, child, parent, and sex), study procedures, and group assignment have important implications when planning clinical trials. Parents rated the trial more favorably but worried about hypoglycemia and diabetes onset. Children had the least favorable reaction to the study. Parents preferred assignment to the intervention group; child/adult participants preferred assignment to the closely monitored group. The intervention group rated the annual 4-day insulin infusions more negatively than all other study procedures. Intervention group participants/parents reported poorer insulin injection adherence over the course of the study. Intervention group participants, parents, and female subjects expressed an interest in additional psychosocial support during the trial. Random assignment was viewed negatively by both study groups. Close observation for diabetes onset was viewed as the most favorable aspect of the study. Behaviors outside of the study protocol to prevent or delay diabetes onset were common and should be monitored in future prevention studies. Overall, most participants were positive about the trial, and many expressed optimism about the intervention's potential for success. These results have implications for study design, recruitment, and retention procedures in future prevention trials.

Rotavirus Infection of Infant and Young Adult Nonobese Diabetic Mice Involves Extraintestinal Spread and Delays Diabetes Onset

Rotaviruses have been implicated as a possible viral trigger for exacerbations in islet autoimmunity, suggesting they might modulate type 1 diabetes development. In this study, the ability of rotavirus strain RRV to infect the pancreas and affect insulitis and diabetes was examined in nonobese diabetic (NOD) mice, an experimental model of type 1 diabetes. Mice were inoculated either orally or intraperitoneally as infants or young adults. In infant mice inoculated orally, rotavirus antigen was detected in pancreatic macrophages outside islets and infectious virus was found in blood cells, pancreas, spleen, and liver. Extraintestinal RRV spread and pancreatic presence of infectious virus also occurred in intraperitoneally inoculated infant and adult mice. The initiation of insulitis was unaltered by infection. The onset of diabetes was delayed in infant mice inoculated orally and infant and adult mice inoculated intraperitoneally. In contrast, adult mice inoculated orally showed no evidence of pancreatic RRV, the lowest rate of detectable RRV replication, and no diabetes modulation. Thus, the ability of RRV infection to modulate diabetes development in infant and young adult NOD mice was related to the overall extent of detectable virus replication and the presence of infectious virus extraintestinally, including in the pancreas. These studies show that RRV infection of infant and young adult NOD mice provides significant protection against diabetes. As these findings do not support the hypothesis that rotavirus triggers autoimmunity related to type 1 diabetes, further research is needed to resolve this issue.