Serum IFN-gamma and IL-10 levels are associated with disease progression in non-obese diabetic mice

CXCL16-dependent scavenging of oxidized lipids by islet macrophages promotes differentiation of pathogenic CD8+ T cells in diabetic autoimmunity

The pancreatic islet microenvironment is highly oxidative, rendering β cells vulnerable to autoinflammatory insults. Here, we examined the role of islet resident macrophages in the autoimmune attack that initiates type 1 diabetes. Islet macrophages highly expressed CXCL16, a chemokine and scavenger receptor for oxidized low-density lipoproteins (OxLDLs), regardless of autoimmune predisposition. Deletion of Cxcl16 in nonobese diabetic (NOD) mice suppressed the development of autoimmune diabetes. Mechanistically, Cxcl16 deficiency impaired clearance of OxLDL by islet macrophages, leading to OxLDL accumulation in pancreatic islets and a substantial reduction in intra-islet transitory (Texint) CD8+ T cells displaying proliferative and effector signatures. Texint cells were vulnerable to oxidative stress and diminished by ferroptosis; PD-1 blockade rescued this population and reversed diabetes resistance in NOD.Cxcl16-/- mice. Thus, OxLDL scavenging in pancreatic islets inadvertently promotes differentiation of pathogenic CD8+ T cells, presenting a paradigm wherein tissue homeostasis processes can facilitate autoimmune pathogenesis in predisposed individuals.

Engineering of hybrid spheroids of mesenchymal stem cells and drug depots for immunomodulating effect in islet xenotransplantation

Immunomodulation is an essential consideration for cell replacement procedures. Unfortunately, lifelong exposure to nonspecific systemic immunosuppression results in immunodeficiency and has toxic effects on nonimmune cells. Here, we engineered hybrid spheroids of mesenchymal stem cells (MSCs) with rapamycin-releasing poly(lactic-co-glycolic acid) microparticles (RAP-MPs) to prevent immune rejection of islet xenografts in diabetic C57BL/6 mice. Hybrid spheroids were rapidly formed by incubating cell-particle mixture in methylcellulose solution while maintaining high cell viability. RAP-MPs were uniformly distributed in hybrid spheroids and sustainably released RAP for ~3 weeks. Locoregional transplantation of hybrid spheroids containing low doses of RAP-MPs (200- to 4000-ng RAP per recipient) significantly prolonged islet survival times and promoted the generation of regional regulatory T cells. Enhanced programmed death-ligand 1 expression by MSCs was found to be responsible for the immunomodulatory performance of hybrid spheroids. Our results suggest that these hybrid spheroids offer a promising platform for the efficient use of MSCs in the transplantation field.

Sustained high glucose intake accelerates type 1 diabetes in NOD mice

INTRODUCTION

Epidemiological studies have suggested that dietary factors, especially high consumption of high glycaemic index carbohydrates and sugars, may trigger or exacerbate the progression of type 1 diabetes. We aimed to provide experimental evidence to confirm this relevance and to explore the underlying mechanisms.

METHODS

NOD mice were given sustained high-glucose drinking or glucose-free water and observed for the incidence of type 1 diabetes and islet inflammation. RNAseq was performed to detect the transcriptome changes of the NOD islet beta cell line NIT-1 after high glucose treatment, and mass spectrometry was performed to detect the proteome changes of NIT-1-cells-derived sEVs.

RESULTS

Sustained high glucose drinking significantly aggravates islet inflammation and accelerates the onset of type 1 diabetes in NOD mice. Mechanistically, high glucose treatment induces aberrant ER stress and up-regulates the expression of autoantigens in islet beta cell. Moreover, high glucose treatment alters the proteome of beta-cells-derived sEVs, and significantly enhances the ability of sEVs to promote DC maturation and stimulate immune inflammatory response.

DISCUSSION

This study provides evidence for negative effect of high glucose intake as a dietary factor on the pathogenesis of type 1 diabetes in genetically predisposed individuals. Therefore, avoiding high sugar intake may be an effective disease prevention strategy for children or adults susceptible to type 1 diabetes.

Interleukin-35 Prevents Development of Autoimmune Diabetes Possibly by Maintaining the Phenotype of Regulatory B Cells

The anti-inflammatory role of regulatory B cells (Breg cells) has been associated with IL-35 based on studies of experimental autoimmune uveitis and encephalitis. The role of Breg cells and IL-35⁺ Breg cells for type 1 diabetes (T1D) remains to be investigated. We studied PBMCs from T1D subjects and healthy controls (HC) and found lowered proportions of Breg cells and IL-35⁺ Breg cells in T1D. To elucidate the role of Breg cells, the lymphoid organs of two mouse models of T1D were examined. Lower proportions of Breg cells and IL-35⁺ Breg cells were found in the animal models of T1D compared with control mice. In addition, the systemic administration of recombinant mouse IL-35 prevented hyperglycemia after multiple low dose streptozotocin (MLDSTZ) injections and increased the proportions of Breg cells and IL-35⁺ Breg cells. A higher proportion of IFN-γ⁺ cells among Breg cells were found in the PBMCs of the T1D subjects. In the MLDSTZ mice, IL-35 administration decreased the proportions of IFN-γ⁺ cells among the Breg cells. Our data illustrate that Breg cells may play an important role in the development of T1D and that IL-35 treatment prevents the development of hyperglycemia by maintaining the phenotype of the Breg cells under an experimental T1D condition.

Protein kinase C-θ knockout decreases serum IL-10 levels and inhibits insulin secretion from islet β cells

Various subtypes of protein kinase C (PKC) are expressed in islet β cells and regulate β cell proliferation and survival. PKC-θ is distributed in the immune system and promotes the secretion of IL-10, which manifests a critical role in the onset of diabetes, by the immune cells. However, the role of PKC-θ in islets has not been concerned. In the present study, we investigated the role of PKC-θ in the protection of islet β cells and insulin secretion. Fasting glucose and insulin measurement, glucose tolerant test, immunofluorescence, and ELISA were conducted to study the influence of PKC-θ knockout on islet β cell survival and function, and explore the mechanism underlying this regulation. PKC-θ knockout mice at 2 weeks manifested normal serum insulin levels, glucose tolerance, and β cell mass. Knockout mice at 8 weeks show decreased β cell mass, but manifested normal insulin levels and glucose tolerance. Knockout mice at 16 weeks manifested impaired glucose tolerance, β cell mass, and decreased glucose stimulated insulin secretion. Furthermore, knockout mice manifested decreased serum IL-10 level compared with normal mice since 2 weeks. IL-10 injection into knockout mice improved glucose tolerance, serum insulin level, and reduced β cell mass, and IL-10 administration into cultured pancreatic tissue increased glucose stimulated insulin secretion. PKC-θ knockout decreases the secretion of IL-10, reduces β cell mass and insulin secretion in pancreatic islets. The present study illuminates the critical role of PKC-θ in protecting the survival and function of islet β cells.

Targeting transcriptional coregulator OCA-B/Pou2af1 blocks activated autoreactive T cells in the pancreas and type 1 diabetes

The transcriptional coregulator OCA-B promotes expression of T cell target genes in cases of repeated antigen exposure, a necessary feature of autoimmunity. We hypothesized that T cell-specific OCA-B deletion and pharmacologic OCA-B inhibition would protect mice from autoimmune diabetes. We developed an Ocab conditional allele and backcrossed it onto a diabetes-prone NOD/ShiLtJ strain background. T cell-specific OCA-B loss protected mice from spontaneous disease. Protection was associated with large reductions in islet CD8+ T cell receptor specificities associated with diabetes pathogenesis. CD4+ clones associated with diabetes were present but associated with anergic phenotypes. The protective effect of OCA-B loss was recapitulated using autoantigen-specific NY8.3 mice but diminished in monoclonal models specific to artificial or neoantigens. Rationally designed membrane-penetrating OCA-B peptide inhibitors normalized glucose levels and reduced T cell infiltration and proinflammatory cytokine expression in newly diabetic NOD mice. Together, the results indicate that OCA-B is a potent autoimmune regulator and a promising target for pharmacologic inhibition.

B regulatory cells associated with changes in biochemical and inflammatory parameters in normal-glycemic individuals, pre-diabetes and T2DM patients

AIM

To determine the percentages of (CD19 + CD24 + CD38+, CD19 + CD24 + CD27+, CD19 + IL-10+)-Breg cells, IL-17 single and IL-17+/IFN-γ double producers T cells and IFN-γ+ T cells, in normal-glycemic individuals, prediabetes and T2DM patients, and to analyze the association of Breg cells with metabolic parameters of T2DM.

METHODS

percentages of Breg cells, IL-17+ and IL-17 + IFN-γ+ T cells, IFN-γ+ T cells and IL-10 were determined by flow cytometry. IL-6 levels were evaluated by ELISA assay.

RESULTS

increased IL-6 levels, IL-17+ and IL-17 + IFN-γ+ T cells and a diminution of IL-10 levels and CD19 + IL-10+ cells in T2DM patients were observed. We found that CD19 + CD24 + CD27+ cells and CD19 + CD24 + CD38+ cells were increased in T2DM patients. The percentages of CD19 + CD24 + CD38+ cells were associated with HOMA-B, TyG index, HDL and cholesterol values. In normal-glycemic individuals, CD19 + CD24 + CD27+ cells were inversely associated to triglycerides and TyG index. In prediabetes patients, CD19 + CD24 + CD38+ cells were inversely related with cholesterol and LDL. Finally, CD19 + CD24 + CD38+ cells were inversely related with HDL values in T2DM patients.

CONCLUSION

Our results suggest that increased percentages of IL-17 single and IL-17/IFN-γ double producers T cells in T2DM patients may be a consequence of the initial CD19 + IL-10+ cells reduction. Furthermore, dyslipidemia could play an important role in percentages and activity of B regulatory cells.

Immunopathology of Type 1 Diabetes and Immunomodulatory Effects of Stem Cells: A Narrative Review of the Literature

Type 1 Diabetes (T1D) is a complex autoimmune disorder which occurs as a result of an intricate series of pathologic interactions between pancreatic β-cells and a wide range of components of both the innate and the adaptive immune systems. Stem-cell therapy, a recently-emerged potentially therapeutic option for curative treatment of diabetes, is demonstrated to cause significant alternations to both different immune cells such as macrophages, natural killer (NK) cells, dendritic cells, T cells, and B cells and non-cellular elements including serum cytokines and different components of the complement system. Although there exists overwhelming evidence indicating that the documented therapeutic effects of stem cells on patients with T1D is primarily due to their potential for immune regulation rather than pancreatic tissue regeneration, to date, the precise underlying mechanisms remain obscure. On the other hand, immune-mediated rejection of stem cells remains one of the main obstacles to regenerative medicine. Moreover, the consequences of efferocytosis of stem-cells by the recipients' lung-resident macrophages have recently emerged as a responsible mechanism for some immune-mediated therapeutic effects of stem-cells. This review focuses on the nature of the interactions amongst different compartments of the immune systems which are involved in the pathogenesis of T1D and provides explanation as to how stem cell-based interventions can influence immune system and maintain the physiologic equilibrium.

Using gold nanoparticles for enhanced intradermal delivery of poorly soluble auto-antigenic peptides

Ultra-small 1-2 nm gold nanoparticles (NP) were conjugated with a poorly-soluble peptide auto-antigen, associated with type 1 diabetes, to modify the peptide pharmacokinetics, following its intradermal delivery. Peptide distribution was characterized, in vivo, after delivery using either conventional intradermal injection or a hollow microneedle device. The poorly-soluble peptide was effectively presented in distant lymph nodes (LN), spleen and draining LN when conjugated to the nanoparticles, whereas peptide alone was only presented in the draining LN. By contrast, nanoparticle conjugation to a highly-soluble peptide did not enhance in vivo distribution. Transfer of both free peptide and peptide-NPs from the skin to LN was reduced in mice lacking lymphoid homing receptor CCR7, suggesting that both are actively transported by migrating dendritic cells to LN. Collectively, these data demonstrate that intradermally administered ultra-small gold nanoparticles can widen the distribution of poorly-soluble auto-antigenic peptides to multiple lymphoid organs, thus enhancing their use as potential therapeutics.

Peptidylarginine Deiminase Inhibition Prevents Diabetes Development in NOD Mice

Protein citrullination plays a role in several autoimmune diseases. Its involvement in murine and human type 1 diabetes has recently been recognized through the discovery of antibodies and T-cell reactivity against citrullinated peptides. In the current study, we demonstrate that systemic inhibition of peptidylarginine deiminases (PADs), the enzymes mediating citrullination, through BB-Cl-amidine treatment, prevents diabetes development in NOD mice. This prevention was associated with reduced levels of citrullination in the pancreas, decreased circulating autoantibody titers against citrullinated glucose-regulated protein 78, and reduced spontaneous neutrophil extracellular trap formation of bone marrow-derived neutrophils. Moreover, BB-Cl-amidine treatment induced a shift from Th1 to Th2 cytokines in the serum and an increase in the frequency of regulatory T cells in the blood and spleen. In the pancreas, BB-Cl-amidine treatment preserved insulin production and was associated with a less destructive immune infiltrate characterized by reduced frequencies of effector memory CD4⁺ T cells and a modest reduction in the frequency of interferon-γ-producing CD4⁺ and CD8⁺ T cells. Our results point to a role of citrullination in the pathogenesis of autoimmune diabetes, with PAD inhibition leading to disease prevention through modulation of immune pathways. These findings provide insight in the potential of PAD inhibition for treating autoimmune diseases like type 1 diabetes.

The JAK1 Selective Inhibitor ABT 317 Blocks Signaling Through Interferon-γ and Common γ Chain Cytokine Receptors to Reverse Autoimmune Diabetes in NOD Mice

Cytokines that signal through the JAK-STAT pathway, such as interferon-γ (IFN-γ) and common γ chain cytokines, contribute to the destruction of insulin-secreting β cells by CD8⁺ T cells in type 1 diabetes (T1D). We previously showed that JAK1/JAK2 inhibitors reversed autoimmune insulitis in non-obese diabetic (NOD) mice and also blocked IFN-γ mediated MHC class I upregulation on β cells. Blocking interferons on their own does not prevent diabetes in knockout NOD mice, so we tested whether JAK inhibitor action on signaling downstream of common γ chain cytokines, including IL-2, IL-7 IL-15, and IL-21, may also affect the progression of diabetes in NOD mice. Common γ chain cytokines activate JAK1 and JAK3 to regulate T cell proliferation. We used a JAK1-selective inhibitor, ABT 317, to better understand the specific role of JAK1 signaling in autoimmune diabetes. ABT 317 reduced IL-21, IL-2, IL-15 and IL-7 signaling in T cells and IFN-γ signaling in β cells, but ABT 317 did not affect GM-CSF signaling in granulocytes. When given in vivo to NOD mice, ABT 317 reduced CD8⁺ T cell proliferation as well as the number of KLRG⁺ effector and CD44^hiCD62L^lo effector memory CD8⁺ T cells in spleen. ABT 317 also prevented MHC class I upregulation on β cells. Newly diagnosed diabetes was reversed in 94% NOD mice treated twice daily with ABT 317 while still on treatment at 40 days and 44% remained normoglycemic after a further 60 days from discontinuing the drug. Our results indicate that ABT 317 blocks common γ chain cytokines in lymphocytes and interferons in lymphocytes and β cells and are thus more effective against diabetes pathogenesis than IFN-γ receptor deficiency alone. Our studies suggest use of this class of drug for the treatment of type 1 diabetes.

Inflammatory, cardio-metabolic and diabetic profiling of chronic schizophrenia

Background

There is a growing interest in low-grade inflammatory and metabolic alterations in patients with chronic schizophrenia (SCH).

Methods

Inflammatory (tumor-necrosis factor-α [TNF-α], interferon-γ [IFN-γ], interleukins [IL-1α, IL-1β, IL-2, IL-4, IL-6, IL-8, IL-10], monocyte chemo-attractant protein-1 [MCP-1]) and growth factors (vascular endothelial growth factor [VEGF], epidermal growth factor [EGF]) were measured in blood serum samples of 105 SCH patients and 148 control subjects (CS). Simultaneously the clinical biomarkers (C-reactive protein [CRP], triglycerides [TG], low-density lipoprotein [LDL-c] and high-density lipoprotein [HDL-c] cholesterol, glycated hemoglobin [HbA1c]) were measured, and body mass index (BMI) was calculated for patients.

Results

Several cyto-/chemokines (IFN-γ, MCP-1, IL-2, IL-6, IL-8 and IL-10) were significantly (P < 0.0000001) elevated in SCH patients compared to CS. Odds ratios, obtained from logistic regression analyses, were significantly elevated for IL-2, IL-6, IL-10, INF-γ, and decreased for TNF-α in SCH group. Among the patients, higher IL-2, IL-6, INF-γ and lower MCP-1 levels as well as male gender were together significant (P < 0.000001) predictors of higher HbA1c levels, and TG/HDL-c parameter was associated with ratios of INF-γ/IL-10 (P = 0.004), and INF-γ/IL-4 (P = 0.049), HbA1c (P = 0.005), INF-γ (P = 0.009), as well as LDL-c (P = 0.02) levels.

Conclusions

IL-2, IL-6, IL-10 and IFN-γ were the most significant SCH-related markers among the measured cytokines in our patient group. Furthermore, significant associations between pro-/anti-inflammatory imbalance and HbA1c as well as cardio-metabolic risk marker (TG/HDL-c) were observed, indicating higher risks of diabetes and cardiovascular diseases among SCH patients.

Safety Assessment of Bacteroides Uniformis CECT 7771, a Symbiont of the Gut Microbiota in Infants

The formulation of next-generation probiotics requires competent preclinical studies to show their efficacy and safety status. This study aims to confirm the safety of the prolonged oral use of Bacteroides uniformis CECT 7771, a strain that protected against metabolic disorders and obesity in preclinical trials, in a sub-chronic 90 day trial in animals. The safety assessment was conducted in male and female Wistar rats (n = 50) administered increasing doses (108 CFU/day, 109 CFU/day, or 1010 CFU/day) of B. uniformis CECT 7771, 1010 CFU/day of B. longum ATCC 15707T, which complies with the qualifying presumption of safety (QPS) status of the EU, or vehicle (placebo), as the control. Pancreatic, liver, and kidney functions and cytokine concentrations were analyzed. Bacterial translocation to peripheral tissues was evaluated, and colon integrity was investigated histologically. No adverse metabolic or tissue integrity alterations were associated with treatments; however, alanine aminotransferase levels and the ratio of anti-inflammatory to pro-inflammatory cytokines in serum indicated a potentially beneficial role of B. uniformis CECT 7771 at specific doses. Additionally, the microbial community structure was modified by the interventions, and potentially beneficial gut bacteria were increased. The results indicated that the oral consumption of B. uniformis CECT 7771 during a sub-chronic 90 day study in rats did not raise safety concerns.

Loss of interleukin-10 exacerbates early Type-1 diabetes-induced bone loss

Type-1 diabetes (T1D) increases systemic inflammation, bone loss, and risk for bone fractures. Levels of the anti-inflammatory cytokine interleukin-10 (IL-10) are decreased in T1D, however their role in T1D-induced osteoporosis is unknown. To address this, diabetes was induced in male IL-10 knockout (KO) and wild-type (WT) mice. Analyses of femur and vertebral trabecular bone volume fraction identified bone loss in T1D-WT mice at 4 and 12 weeks, which in T1D-IL-10-KO mice was further reduced at 4 weeks but not 12 weeks. IL-10 deficiency also increased the negative effects of T1D on cortical bone. Osteoblast marker osterix was decreased, while osteoclast markers were unchanged, suggesting that IL-10 promotes anabolic processes. MC3T3-E1 osteoblasts cultured under high glucose conditions displayed a decrease in osterix which was prevented by addition of IL-10. Taken together, our results suggest that IL-10 is important for promoting osteoblast maturation and reducing bone loss during early stages of T1D.

Nrf2 represses the onset of type 1 diabetes in non-obese diabetic mice

The transcription factor Nrf2 (NF-E2-related factor 2) plays a critical role in oxidative stress responses. While activation of Nrf2 signaling is known to exert anti-inflammatory effects, Nrf2 function in inflammation-mediated autoimmune disorders, such as type 1 diabetes, is not well established. To address the roles of Nrf2 in protection against autoreactive T-cell-induced type 1 diabetes, we used non-obese diabetic (NOD) mice, a polygenic model of human type 1 diabetes, to generate a genetic model that allowed us to assess the contribution of Nrf2 activation to preventing and/or treating type 1 diabetes. As Keap1 negatively regulates Nrf2, we used Keap1 gene knockdown driven by either hypomorphic or knockout alleles of Keap1,which enhances Nrf2 signaling to moderate and excess levels, respectively. We found that Nrf2 activation in NOD::Keap1FA/- mice inhibited T-cell infiltration within or near the islets, ameliorated impairment of insulin secretion, and prevented development of diabetes mellitus in the NOD mice. Notably, Nrf2 activation decreased both plasma interferon-γ (IFN-γ) levels and IFN-γ-positive cell numbers in the pancreatic islets. These findings were also observed in mice with two hypomorphic Keap1 alleles (Keap1FA/FA). Both NOD::Keap1FA/- and NOD::Keap1FA/FA mice had decreased incidence of diabetes mellitus, demonstrating that the activation of Nrf2 signaling prevents the onset of type 1 diabetes mellitus in NOD mice. Thus, Nrf2 appears to be a potential target for preventing and treating type 1 diabetes.

Probiotic Bifidobacterium lactis, anti-oxidant vitamin E/C and anti-inflammatory dha attenuate lung inflammation due to pm2.5 exposure in mice

The incidence of asthma and allergic diseases of the airways is constantly increasing, both in the industrialised and developing countries, due to harmful and excessive quantities of air pollution. Although some studies have shown an effect of dietary supplementation of specific nutrients (especially with anti-oxidant and anti-inflammatory properties) in reducing airways inflammatory response, the results are not yet conclusive and the science is still at its infancy. Our hypothesis is that combining such nutrients could provide more benefits than using them alone. The aim of the research project proposed here is to investigate whether specific combinations of nutrients (docosahexanoic acid, vitamin C and E, and Bifidobacterium lactis strain BB-12®, included in an engineered diet) can act synergistically to reduce inflammation given by high level of air pollution. Beside the role of docosahexanoic acid, vitamins C and E on airways inflammatory disease, no study examined the effect of the supplementation of this probiotic strain in pathological conditions caused by air pollution so far. Herein we used a well-established in vivo model for the study of pollution effects, which consists in female BALB/c mice receiving by pharyngeal aspiration either a sham or a particulate matter with diameter <2.5 μm (PM 2.5) containing aerosol. Before treatment, mice were fed either a chow or a supplemented diet. By performing histological analyses and gene expression profiles on lung sections and serum measurement of the cytokine interleukin 10, we found that a specific combination of all the aforementioned nutrients rather than nutrients alone had a synergistic protective effect against PM2.5-induced inflammation. In conclusion, our study support that a supplemental nutritional intervention based on a combination of the probiotic B. lactis BB-12, the anti-oxidant vitamin C and E, and the anti-inflammatory docosahexanoic acid represents a rational option for alleviating air pollution-related lung inflammation.

Immune Response to Extracellular Vesicles From Human Islets of Langerhans in Patients With Type 1 Diabetes

The autoimmune response that characterizes type 1 diabetes (T1D) has no clear cause. Extracellular vesicles (EVs) play an important role in triggering the immune response in other contexts. Here, we propose a model by which EVs isolated from human islets stimulate proinflammatory immune responses and lead to peripheral blood mononuclear cell (PBMC) activation. We show that human islet EVs are internalized by monocytes and B cells and lead to an increase in T-helper 1, 2, and 17 cytokine expression, as well as T and B cell proliferation. Importantly, we demonstrate memory T and B cell activation by EVs selectively in PBMCs of patients with T1D. Additionally, human islet EVs induce an increase in antibodies against glutamic acid decarboxylase 65 (GAD65) in T1D PBMCs. Furthermore, pretreatment of T1D PBMCs with ibrutinib, an inhibitor of Bruton tyrosine kinase, dampens EV-induced memory B cell activation and GAD65 antibody production. Collectively, our findings indicate a role for human islet EVs in mediating activation of B and T cells and GAD65 autoantibody production.

Anti-Insulin B Cells Are Poised for Antigen Presentation in Type 1 Diabetes

Early breaches in B cell tolerance are central to type 1 diabetes progression in mouse and man. Conventional BCR transgenic mouse models (VH125.Tg NOD) reveal the power of B cell specificity to drive disease as APCs. However, in conventional fixed IgM models, comprehensive assessment of B cell development is limited. To provide more accurate insight into the developmental and functional fates of anti-insulin B cells, we generated a new NOD model (V_H125^SDNOD) in which anti-insulin VDJH125 is targeted to the IgH chain locus to generate a small (1-2%) population of class switch-competent insulin-binding B cells. Tracking of this rare population in a polyclonal repertoire reveals that anti-insulin B cells are preferentially skewed into marginal zone and late transitional subsets known to have increased sensitivity to proinflammatory signals. Additionally, IL-10 production, characteristic of regulatory B cell subsets, is increased. In contrast to conventional models, class switch-competent anti-insulin B cells proliferate normally in response to mitogenic stimuli but remain functionally silent for insulin autoantibody production. Diabetes development is accelerated, which demonstrates the power of anti-insulin B cells to exacerbate disease without differentiation into Ab-forming or plasma cells. Autoreactive T cell responses in V_H125^SDNOD mice are not restricted to insulin autoantigens, as evidenced by increased IFN-γ production to a broad array of diabetes-associated epitopes. Together, these results independently validate the pathogenic role of anti-insulin B cells in type 1 diabetes, underscore their diverse developmental fates, and demonstrate the pathologic potential of coupling a critical β cell specificity to predominantly proinflammatory Ag-presenting B cell subsets.

Cellular senescence links aging and diabetes in cardiovascular disease

Aging is a powerful independent risk factor for cardiovascular diseases such as atherosclerosis and heart failure. Concomitant diabetes mellitus strongly reinforces this effect of aging on cardiovascular disease. Cellular senescence is a fundamental mechanism of aging and appears to play a crucial role in the onset and prognosis of cardiovascular disease in the context of both aging and diabetes. Senescent cells are in a state of cell cycle arrest but remain metabolically active by secreting inflammatory factors. This senescence-associated secretory phenotype is a trigger of chronic inflammation, oxidative stress, and decreased nitric oxide bioavailability. A complex interplay between these three mechanisms results in age- and diabetes-associated cardiovascular damage. In this review, we summarize current knowledge on cellular senescence and its secretory phenotype, which might be the missing link between aging and diabetes contributing to cardiovascular disease.

Interferon-γ Limits Diabetogenic CD8+ T-Cell Effector Responses in Type 1 Diabetes

Type 1 diabetes development in the NOD mouse model is widely reported to be dependent on high-level production by autoreactive CD4⁺ and CD8⁺ T cells of interferon-γ (IFN-γ), generally considered a proinflammatory cytokine. However, IFN-γ can also participate in tolerance-induction pathways, indicating it is not solely proinflammatory. This study addresses how IFN-γ can suppress activation of diabetogenic CD8⁺ T cells. CD8⁺ T cells transgenically expressing the diabetogenic AI4 T-cell receptor adoptively transferred disease to otherwise unmanipulated NOD.IFN-γ^null , but not standard NOD, mice. AI4 T cells only underwent vigorous intrasplenic proliferation in NOD.IFN-γ^null recipients. Disease-protective IFN-γ could be derived from any lymphocyte source and suppressed diabetogenic CD8⁺ T-cell responses both directly and through an intermediary nonlymphoid cell population. Suppression was not dependent on regulatory T cells, but was associated with increased inhibitory STAT1 to STAT4 expression levels in pathogenic AI4 T cells. Importantly, IFN-γ exposure during activation reduced the cytotoxicity of human-origin type 1 diabetes-relevant autoreactive CD8⁺ T cells. Collectively, these results indicate that rather than marking the most proinflammatory lymphocytes in diabetes development, IFN-γ production could represent an attempted limitation of pathogenic CD8⁺ T-cell activation. Thus, great care should be taken when designing possible diabetic intervention approaches modulating IFN-γ production.

Proinflammatory Cytokines Induce Endocrine Differentiation in Pancreatic Ductal Cells via STAT3-Dependent NGN3 Activation

A major goal of diabetes research is to develop strategies that replenish pancreatic insulin-producing beta cells. One emerging strategy is to harness pancreatic plasticity-the ability of pancreatic cells to undergo cellular interconversions-a phenomenon implicated in physiological stress and pancreatic injury. Here, we investigate the effects of inflammatory cytokine stress on the differentiation potential of ductal cells in a human cell line, in mouse ductal cells by pancreatic intraductal injection, and during the progression of autoimmune diabetes in the non-obese diabetic (NOD) mouse model. We find that inflammatory cytokine insults stimulate epithelial-to-mesenchymal transition (EMT) as well as the endocrine program in human pancreatic ductal cells via STAT3-dependent NGN3 activation. Furthermore, we show that inflammatory cytokines activate ductal-to-endocrine cell reprogramming in vivo independent of hyperglycemic stress. Together, our findings provide evidence that inflammatory cytokines direct ductal-to-endocrine cell differentiation, with implications for beta cell regeneration.

Expression of Natural Cytotoxicity Receptors on and Intracellular Cytokine Production by NK Cells in Women with Gestational Diabetes Mellitus

PROBLEM

To determine the role of peripheral blood NK (pNK) cells in putative etiology of gestational diabetes, the expression of surface markers on pNK cells and the percentage of cytokine-producing pNK cells in women at 12 weeks of pregnancy with gestational diabetes mellitus (GDM) were studied.

METHOD OF STUDY

Multicolor flow cytometry was used to analyze the expression of NK cell surface receptors (CD16, NKp46, and NKp30) and intracellular cytokines (IFN-γ, TNF-α, TGF-β, and VEGF) in pNK cells (CD56(dim) and CD56(bright) ) at 12 weeks of pregnancy with GDM (n = 7) and non-GDM (n = 28).

RESULTS

CD56(bright) /CD16(-) NK and CD56(bright) /NKp46(+) NK cell percentage were significantly lower in GDM women than that in non-GDM women. IFN-γ- and TNF-α-producing CD56(+) cells, respectively, were significantly high, while TGF-β- and VEGF-producing CD56(+) cells and CD56(bright) cells, respectively, were significantly low in GDM women.

CONCLUSIONS

Women with GDM possibly have abnormal NK cell function for the expression of surface receptors and cytokine production.

Inactivation of the Progesterone Receptor in Mx1+ Cells Potentiates Osteogenesis in Calvaria but Not in Long Bone

The effect of progesterone on bone remains elusive. We previously reported that global progesterone receptor (PR) knockout mice displayed high bone mass phenotype, suggesting that PR influences bone growth and modeling. Recently, Mx1+ cells were characterized to be mesenchymal stem cell-like pluripotent Cells. The aim of this study was to evaluate whether the PR in Mx1+ cells regulates osteogenesis. Using the Mx1-Cre;mT/mG reporter mouse model, we found that the calvarial cells exhibited minimal background Mx1-Cre activity prior to Cre activation by IFNα treatment as compared to the bone marrow stromal cells. IFNα treatment significantly activated Mx1-Cre in the calvarial cells. When the PR gene was deleted in the Mx1-Cre;PR-flox calvarial cells in vitro, significantly higher levels of expression of osteoblast maturation marker genes (RUNX2, Osteocalcin, and Dmp1) and osteogenic potential were detected. The PR-deficient calvariae exhibited greater bone volume, especially in the males. Although Mx1-Cre activity could be induced on the bone surface in vivo, the Mx1+ cells did not differentiate into osteocytes in long bones. Bone volumes at the distal femurs and the bone turnover marker serum Osteocalcin were similar between the Mx1-Cre;PR-flox mutant mice and the corresponding wild types in both sexes. In conclusion, our data demonstrates that blocking progesterone signaling via PRs in calvarial Mx1+ cells promoted osteoblast differentiation in the calvaria. Mx1+ was expressed by heterogeneous cells in bone marrow and did not differentiate into osteocyte during long bone development in vivo. Selectively inactivating the PR gene in Mx1+ cells affected the membrane bone formation but did not affect peripheral skeletal homeostasis.

Reduced interferon-α production by dendritic cells in type 1 diabetes does not impair immunity to influenza virus

The increased risk and persistence of infections in diabetic condition is probably associated with defects in the cellular immune responses. We have previously shown a decrease in the production of interferon (IFN)-α by dendritic cells (DCs) in diabetic subjects. The basal level of IFN-α in splenic plasmacytoid DCs (pDCs) is also lower in non-obese diabetic (NOD) mice compared to prediabetic mice. The objective of this study was to analyse the ability of diabetic mice to mobilize innate and CD8(+) T cell-mediated immune response to influenza A virus (IAV) with the live influenza A/Puerto Rico/8/1934 H1N1 (PR8) strain or with its immunodominant CD8(+) T cell epitopes. We found that following immunization with IAV, the level of IFN-α in diabetic mice was increased to the level in prediabetic mice. Immunization of NOD mice with the immunodominant IAV PR8 peptide induced clonal expansion of IFN-γ-producing CD8(+) T cells similar to the response observed in prediabetic mice. Thus, diabetic and prediabetic NOD mice have a similar capacity for IFN-α and IFN-γ production by pDCs and CD8(+) T cells, respectively. Therefore, the DC-related immune defect in diabetic NOD mice does not impair their capacity to develop an effective immune response to IAV. Our results suggest that reduced IFN-α production by diabetic human and mouse DCs is not an impediment to an effective immunity to IAV in type 1 diabetic subjects vaccinated with live attenuated influenza vaccine.

Effect of lycopene application in rats with experimental diabetes using lipoprotein, paraoxonase and cytokines

This study was conducted with the purpose of researching the effect of lycopene application on lipoprotein, paraoxonase (PON) and cytokines that are projected to be used in the diagnosis and treatment of diabetes by making experimental diabetes. At the end of a 1-month trial period, under ether anesthesia with jelly tubes, blood samples were taken from rat hearts. Blood samples were centrifuged and serum was obtained. From the serum samples, HbA_1c, paraoxonase activity, lipoprotein levels and cytokines were determined. HbA_1c levels and PON activity were found to be p < 0.001. At the triglyceride level, with regard to the control group, in all the groups a significant rise occurred (p ≤ 0.001). At the cholesterol level, with regard to the control group, a decline was observed in the other groups (p < 0.05). At the VLDL level, with regard to the control group, a significant rise was observed in the other groups (p < 0.05). At the HDL (p < 0.001) and LDL (p < 0.05) levels, with regard to the control group, a significant decline was observed in the other groups. At the TNF-α, IL-2, IL-6 and IL-10 levels no difference was found (p > 0.05). Experimental diabetes models have an important place in analyzing diabetes complications and determining treatment approaches.

Fasting and meal-stimulated residual beta cell function is positively associated with serum concentrations of proinflammatory cytokines and negatively associated with anti-inflammatory and regulatory cytokines in patients with longer term type 1 diabetes

AIMS/HYPOTHESIS

Cytokines may promote or inhibit disease progression in type 1 diabetes. We investigated whether systemic proinflammatory, anti-inflammatory and regulatory cytokines associated differently with fasting and meal-stimulated beta cell function in patients with longer term type 1 diabetes.

METHODS

The beta cell function of 118 patients with type 1 diabetes of duration of 0.75-4.97 years was tested using a standardised liquid mixed meal test (MMT). Serum samples obtained at -5 to 120 min were analysed by multiplex bead-based technology for proinflammatory (IL-6, TNF-α), anti-inflammatory (IL-1 receptor antagonist [IL-1RA]) and regulatory (IL-10, TGF-β1-3) cytokines, and by standard procedures for C-peptide. Differences in beta cell function between patient groups were assessed using stepwise multiple regression analysis adjusting for sex, age, duration of diabetes, BMI, HbA1c and fasting blood glucose.

RESULTS

High fasting systemic concentrations of the proinflammatory cytokines IL-6 and TNF-α were associated with increased fasting and stimulated C-peptide concentrations even after adjustment for confounders (p < 0.03). Interestingly, increased concentrations of anti-inflammatory/regulatory IL-1RA, IL-10, TGF-β1 and TGF-β2 were associated with lower fasting and stimulated C-peptide levels (p < 0.04), losing significance on adjustment for anthropometric variables. During the MMT, circulating concentrations of IL-6 and TNF-α increased (p < 0.001) while those of IL-10 and TGF-β1 decreased (p < 0.02) and IL-1RA and TGF-β2 remained unchanged.

CONCLUSIONS/INTERPRETATION

The association between better preserved beta cell function in longer term type 1 diabetes and increased systemic proinflammatory cytokines and decreased anti-inflammatory and regulatory cytokines is suggestive of ongoing inflammatory disease activity that might be perpetuated by the remaining beta cells. These findings should be considered when designing immune intervention studies aimed at patients with longer term type 1 diabetes and residual beta cell function.

Depletion of CD4(+)CD25(+) T cells exacerbates experimental autoimmune encephalomyelitis induced by mouse, but not rat, antigens

A key question in the field of autoimmunity concerns the fact that experimental disease is generally induced more easily with closely related, but not completely identical, tissue-restricted antigens. Here, the possibility that naturally occurring regulatory T cells (Tregs) for self-antigens are more potent than those for related antigens was investigated. The self-antigen specificity of naturally occurring Tregs was tested in experimental autoimmune encephalomyelitis (EAE) induced with mouse (self) or closely related (rat) myelin oligodendrocyte glycoproteins (MOGs). Surprisingly, Treg depletion increased EAE severity in mice immunized with mouse, but not rat, MOG. This increase was associated with increased T-cell activation and infiltration of the central nervous system, as well as increased interleukin (IL)-17 production and a higher ratio of interferon-gamma- to IL-10-producing cells. These data suggest that Tregs are specific for self-antigen and do not "cross-protect" against autoimmunity even when disease is induced with closely related foreign antigens.

Regulatory function of a novel population of mouse autoantigen-specific Foxp3 regulatory T cells depends on IFN-gamma, NO, and contact with target cells

BACKGROUND

Both naturally arising Foxp3(+) and antigen-induced Foxp3(-) regulatory T cells (Treg) play a critical role in regulating immune responses, as well as in preventing autoimmune diseases and graft rejection. It is known that antigen-specific Treg are more potent than polyclonal Treg in suppressing pathogenic immune responses that cause autoimmunity and inflammation. However, difficulty in identifying and isolating a sufficient number of antigen-specific Treg has limited their use in research to elucidate the mechanisms underlying their regulatory function and their potential role in therapy.

METHODOLOGY/PRINCIPAL FINDINGS

Using a novel class II MHC tetramer, we have isolated a population of CD4(+) Foxp3(-) T cells specific for the autoantigen glutamic acid decarboxylase p286-300 peptide (NR286 T cells) from diabetes-resistant non-obese resistant (NOR) mice. These Foxp3(-) NR286 T cells functioned as Treg that were able to suppress target T cell proliferation in vitro and inhibit type 1 diabetes in animals. Unexpected results from mechanistic studies in vitro showed that their regulatory function was dependent on not only IFN-gamma and nitric oxide, but also on cell contact with target cells. In addition, separating NR286 Treg from target T cells in transwell assays abolished both production of NO and suppression of target T cells, regardless of whether IFN-gamma was produced in cell cultures. Therefore, production of NO, not IFN-gamma, was cell contact dependent, suggesting that NO may function downstream of IFN-gamma in mediating regulatory function of NR286 Treg.

CONCLUSIONS/SIGNIFICANCE

These studies identified a unique population of autoantigen-specific Foxp3(-) Treg that can exert their regulatory function dependent on not only IFN-gamma and NO but also cell contact with target cells.

Association of immune mediators at diagnosis of Type 1 diabetes with later clinical remission

AIMS

We tested the hypothesis that systemic concentrations of cytokines, chemokines or soluble cytokine receptors predict or accompany clinical remission in Type 1 diabetes (T1D).

METHODS

In a prospective, multicentre study, 48 patients with newly diagnosed T1D and 55 age-matched healthy control subjects were investigated. Blood was drawn 3-7 days after the diagnosis and then 3-4 months later. Patients were grouped into partial remitters or non-remitters by the degree of clinical improvement defined by HbA(1c) (threshold 7.5%) and daily insulin dose (threshold 0.38 IU/kg/day). Systemic concentrations of 17 immune mediators were analysed in serum or plasma. In addition, autoantibodies against insulin (IAA), IA-2 (IA-2A) and GAD65 (GADA) were quantified.

RESULTS

All 17 immune mediators showed remarkable intra-individual stability in their systemic concentrations over time. As a consequence, partial remission was not accompanied by changes in mediator levels except for a moderate decrease of interleukin (IL)-1ra concentrations (P = 0.02) and IL-10 concentrations (P = 0.01) in non-remitters. Baseline levels were associated with the later clinical course in that low levels of interferon gamma (P = 0.01), IL-10 (P = 0.03) and IL-1R1 (P = 0.009) concentrations were observed in partial remitters.

CONCLUSIONS

We conclude that the systemic immunoregulatory state at diagnosis of T1D is predictive of clinical improvement during the remission phase. There was no general change in systemic immune reactivity in the months after diagnosis and initiation of insulin therapy.

Association of interferon-gamma and interleukin 10 genotypes and serum levels with partial clinical remission in type 1 diabetes

We studied whether serum interferon (IFN)-gamma or interleukin (IL)-10 levels and their corresponding functional polymorphic genotypes are associated with partial remission of type 1 diabetes (T1D). A multi-centre study was undertaken in patients with newly diagnosed T1D and matched controls. T1D patients were followed for 3 months and characterized for remission status. Partial clinical remission was defined as a daily insulin dose <or= 0.38 units/kg/24 h with an HbA1c <or= 7.5%. Thirty-three patients and 32 controls were phenotyped for serum concentrations of IFN-gamma and IL-10 and genotyped for functional polymorphisms of the IFN-gamma and IL-10 genes. Sixteen of 25 informative patients (63%) remitted. Serum IFN-gamma concentrations were significantly decreased in remitters but increased in non-remitters compared to controls, and did not change over time in any group. IFN-gamma genotypes corresponded with serum levels in controls and non-remitters, but not in remitters who displayed the lowest serum IFN-gamma levels despite more often carrying high-producing IFN-gamma genotypes. Neither the frequency of IL-10 genotypes nor serum IL-10 concentration differed between patients and controls. The combination of high-producing IFN-gamma genotype together with low serum IFN-gamma concentration at the time of diagnosis provided a strong positive predictive value for remission. Serum IFN-gamma concentrations predicted by genotype and observed serum levels were discordant in remitters, suggestive of regulation overruling genetic predisposition. Although high-producing genotypes were less frequent in remitters, they were predictive of remission in combination with low serum IFN-gamma levels. These data imply that remission is partially immune-mediated and involves regulation of IFN-gamma transcription.

Regulatory T Cells Can Mediate Their Function through the Stimulation of APCs to Produce Immunosuppressive Nitric Oxide

Regulatory T cells (Tr cells) play a critical role in inducing immune tolerance. It remains largely unclear how various types of Tr cells perform their regulatory function. We have studied the underlying regulatory mechanism of a population of autoantigen-specific CD4+ Tr cells. These T cells are specific for the glutamic acid decarboxylase p206-220 peptide and are isolated from the diabetes-resistant nonobese-resistant mice. Although these T cells express T-bet and display a Th1 phenotype, they are able to inhibit diabetes. Their regulatory function is dependent on both IFN-gamma and cell contact with target cells. These Tr cells can mediate their cell contact-dependent regulatory function by secreting IFN-gamma which stimulates APCs to produce NO. NO is necessary for the Tr cells to inhibit the proliferation of pathogenic T cells and the development of diabetes. Therefore, we have identified a novel mechanism by which these Tr cells can exert their regulatory function. These results also provide an explanation as to why IFN-gamma may play both pathogenic and immunomodulatory roles in autoimmune diseases.

Evaluation of the natural killer cytotoxicity and the levels of cytokines in rats with type I diabetes mellitus

Type I diabetes mellitus (insulin-dependent DM = IDDM) is a chronic disease characterized by specific destruction of pancreatic beta cells, resulting in an absolute lack of insulin. Immune mechanisms, genetic susceptibility, and environmental factors are all implicated in the pathogenesis of Type 1 diabetes. This study was aimed at determining the efficiency of cytokines, natural killer (NK) cells in the pathophysiology of IDDM. Therefore, we evaluated the plasma levels of cytokines by specific enzyme-linked immunosorbent assay (ELISA) and the cytotoxicity activity of NK cells by anti-candididal index in rats with type I diabetes. We found that the cytotoxicity activity of NK cells in IDDM groups significantly decreased compared to the control groups. The levels of interferon-gamma (IFN-gamma) in IDDM groups were slightly higher than in healthy controls. These results indicate that the changes of T H1 type cytokines such as IFN-gamma and NK cell activity can play a role in the etiology of IDDM. The data may provide new strategies for the treatment of IDDM.

Cytokine profile and insulin antibody IgG subclasses in patients with recent onset type 1 diabetes treated with oral insulin

AIMS/HYPOTHESIS

Tolerance to orally administered antigens may be generated through the induction of T helper cell type 2 and 3 (Th2/Th3) regulatory cells. We previously reported that treatment of recent onset type 1 diabetes with oral insulin had no effect on residual beta cell function. The aim of this study was to evaluate whether this treatment produces a deviation in the immune response, with polarisation of the cytokine pattern and the induction of a Th2-like antibody response.

METHODS

Mononuclear cells were collected from a total of 20 patients with type 1 diabetes before and after 12 months of treatment with oral insulin (n=11) or placebo (n=9). Following stimulation of the cells with insulin or phytohaemagglutinin, levels of Th2 and Th3 cytokines (including TGF-beta, IFN-gamma, IL-4 and IL-5) in the culture supernatants were assessed by ELISA. In addition, levels of total and specific insulin antibody IgG subclasses were measured by radioimmunoassay in serum samples drawn from 33 patients with type 1 diabetes before and after 3, 6 and 12 months of therapy with oral insulin (n=18) or placebo (n=15).

RESULTS

After 12 months of treatment, the release of TGF-beta was significantly higher in patients who received oral insulin compared with those who received placebo (p=0.025 and p=0.006 for lymphocytes challenged with insulin and phytohaemagglutinin respectively). The two groups had similar levels of IL-4 and IL-5 both at baseline and after 12 months of treatment. The release of IFN-gamma was markedly reduced in patients treated with oral insulin compared with those who received placebo at the 12-month follow-up. Circulating levels of IgG1 and IgG3 subclasses directed against insulin were significantly lower in the oral insulin group than in the placebo group after 12 months of treatment (p=0.05 for IgG1 and p=0.014 for IgG3).

CONCLUSIONS/INTERPRETATION

The increased TGF-beta release observed in patients treated with oral insulin suggests that a regulatory response can be induced in vivo by this treatment. The lower levels of insulin antibody IgG1 and IgG3 subclasses present in patients exposed to oral insulin are consistent with a Th2 deviation of the immune response. The failure of oral insulin treatment to provide any measurable clinical benefit may be due to the timing of treatment initiation.

Cytokine release by murine spleen cells following multiple low dose streptozotocin-induced diabetes and treatment with a TNFα transcriptional inhibitor

We recently reported that administration of 9-[(1R, 3R)-trans-cyclopentan-3-ol] adenine (MDL 201,449A), a transcriptional inhibitor of TNFalpha, decreased hyperglycemia in murine diabetes induced by multiple low doses of streptozotocin (MLDSTZ). In the present study, we first investigated if in vivo administration of MDL 201,449A in the MLDSTZ model affects cytokine release from cultured spleen cells. Secondly, we studied how MDL 201,449A affects cytokine release from normal cultured spleen cells. In all experiments, the mitogen concanavalin A (2 micro g/ml) was added to the cultured spleen cells in order to enhance cytokine release. MLDSTZ treatment in vivo caused increased IFNgamma secretion, a decreased/retarded rate of increased TNFalpha accumulation, whereas IL-10 production was not altered compared to vehicle-treated mice. MDL 201,449A treatment of MLDSTZ mice did not affect cytokine release from spleen cells subsequently cultured in the absence of MDL 201,449A. We also studied cytokine release from normal spleen cells in the presence or absence of MDL 201,449A. Production of TNFalpha, IFNgamma and IL-10 was all suppressed by the drug. In groups where exposure to MDL 201,449A was discontinued, cytokine levels increased promptly and in the case of TNFalpha secretion, it exceeded the production from control cells. Our data suggest an enhanced Th1 cytokine secretion from spleen cells derived from MLDSTZ-treated mice. MDL 210,449A may be a potent inhibitor of cytokine secretion, albeit not completely selective for TNFalpha. However, when MDL 201,449A is withdrawn, there may be a rebound phenomenon of increased TNFalpha secretion.

Activities of xanthine oxidoreductase and antioxidant enzymes in different tissues of diabetic rats

Oxidative stress is an important pathogenic constituent in diabetic endothelial dysfunction. The aim of this study was to investigate whether an increase in oxidative stress related to xanthine oxidoreductase occurs in diabetes. Liver, brain, heart, and kidney xanthine oxidase (XO), xanthine dehydrogenase (XDH), antioxidant enzymes (glutathione peroxidase, superoxide dismutase, catalase), and nitrite levels were measured in control and early and late diabetic rat models. Although diabetes had no impact on liver XO and XDH activity, XDH activity in heart, kidney, and brain was significantly greater in late diabetic rats than in controls. Selenium glutathione peroxidase (GPx) activity was found to be lower in the liver, brain, kidney, and heart of late diabetic rats than in controls. The measured decrease in selenium GPx activity was also observed in early diabetic heart, kidney, and brain. No significant change was observed in liver, brain, and kidney copper/zinc superoxide dismutase (Cu/Zn SOD) activity in early and late diabetic rat models compared with that in controls, whereas heart Cu/Zn SOD activity was significantly decreased in both early and late diabetic rats. Liver and brain catalase activity remained similar among the different experimental groups, whereas increased heart and kidney catalase activity was observed in both early and late diabetic rats. Liver, kidney, and brain nitrite levels were found to be increased in early diabetic rat models compared with those in controls. These data suggest that the increased XDH and decreased selenium GPx activity observed in the later stages of diabetes leads to enhanced oxidative stress in the heart, kidney, and brain, resulting in secondary organ damage associated with the disease.

An association of autoantibody status and serum cytokine levels in type 1 diabetes

At onset of type 1 diabetes, the islet autoantibody status of patients has been reported to predict progression of the disease. We therefore tested the hypothesis that the systemic immunoregulatory balance, as defined by levels of circulating cytokines and chemokines, is associated with islet autoantibody status. In 50 patients with recent-onset type 1 diabetes, antibodies to GAD and insulinoma-associated antigen 2 (IA-2) were analyzed by radioimmunoassay; cytoplasmic islet cell antibodies were determined by indirect immunofluorescence. Cytokine and chemokine concentrations were measured by rigidly evaluated double antibody enzyme-linked immunosorbent assay. Of four classically defined Th1/Th2 cytokines (gamma-interferon, interleukin [IL]-5, IL-10, IL-13), none showed an association with multiple autoantibody positivity. Of six mediators mainly produced by innate immunity cells, three were associated with multiple autoantibody status (IL-18 increased, MIF and MCP-1 decreased) and three were unaffected (IL-12, MIP-1beta, IP-10). GAD and/or IA-2 antibody titers negatively correlated with systemic concentrations of MIF, MIP-1beta, and IL-12. Combining the data of several cytokine and chemokine levels made it possible to predict islet antibody positivity in individual patients with 85% sensitivity and 94% specificity. These data suggest a close association of islet antibody status with systemic immunoregulation in type 1 diabetes.

Regulatory cytokine production stimulated by DNA vaccination against an altered form of glutamic acid decarboxylase 65 in nonobese diabetic mice

Nonobese diabetic (NOD) mice develop a T-cell dependent autoimmune form of diabetes, in which glutamic acid decarboxylase 65 (GAD65) is an important islet target antigen. Intramuscular DNA vaccination with a plasmid encoding native GAD65 (a cytosolic antigen) did not significantly alter the incidence of diabetes, but vaccination against an altered form of GAD65 with a signal peptide (spGAD), which is secreted in vitro, was protective. The preventive effect was further enhanced by repeated injections of the spGAD plasmid. Following DNA injection into muscle GAD65 was expressed for several months, and this was not accompanied by an inflammatory response. Immunization against GAD65 was not associated with substantial alterations in cytokine production by splenic lymphocytes stimulated with immunogenic GAD65 peptides. In contrast, spGAD induced increased secretion of both interleukin 10 and interferon gamma and a striking decrease in the interferon gamma/interleukin 10 ratio in culture supernatants. Similarly, spGAD-immunized mice had higher serum interleukin 10 levels and lower serum interferon gamma levels than other groups, suggesting a systemic effect. In nondiabetic mice there was increased basal production of transforming growth factor beta(1), which was enhanced by antigenic stimulation. These alterations in regulatory cytokine production were apparent both early and late after the treatment was initiated. These findings suggest that DNA vaccination against spGAD protects NOD mice by increasing regulatory cytokine production.

Acute shock induced by antigen vaccination in NOD mice

Type 1 diabetes in NOD mice can be prevented through autoantigen vaccination by shifting lymphocyte differentiation toward a T-helper 2 (Th(2)) response. However, in other models of autoimmunity, this approach may be accompanied by unexpected triggering of Th(2)-dependent anaphylactic shock. To test the safety of vaccination therapy in the NOD mouse model, we evaluated the effects of immunization with a wide battery of antigens in NOD, BALB/c, and C57BL/6 mice. Surprisingly, a nondiabetogenic antigen, hen egg white lysozyme, induced severe shock exclusively in NOD mice (shock in 11 of 11 mice, lethal in 3 mice). Shock severity was further increased by a more pronounced Th(2) setting generated by 1alpha,25(OH)(2)D(3) administration (17 of 17 mice, lethal in 14 mice, P < 0.0001). Pretreatment with dexamethasone resulted in full rescue, indicating an immune-mediated mechanism. Serum IgE levels and Th(1)/Th(2) cytokine profile analysis showed that the shock phenomenon was paralleled by a Th(2) response. mRNA expression of platelet-activating factor receptor (PAF-R) was significantly higher in NOD mice (P < 0.01) and was further increased by 1alpha,25(OH)(2)D(3). Pretreatment with WEB2086 (PAF-R antagonist) again protected all mice from lethal shock, indicating PAF as an anaphylaxis effector. In conclusion, in NOD mice, vaccination leading to a Th(2) immune shift can result in a lethal anaphylactic reaction.

Cytokine detection by ELISPOT: relevance for immunological studies in type 1 diabetes

Diabetes mellitus type 1 is a chronic disease in which the insulin-secreting ss-cells are selectively destroyed by an immune-mediated process. Autoantibodies directed against several islet antigens are useful parameters to estimate the risk to develop diabetes, but cell-mediated immunity involving T lymphocytes plays a major part in causing the specific destruction of ss-cells. T cells are characterized by their antigen-specificity, phenotype and cytokine-secreting profile. T cells that secrete cytokines of the T helper 1 (Th1) type have been shown to transfer diabetes in animal studies, in contrast to T helper 2 (Th2) cytokine-secreting T cells that are thought to be rather nondestructive. In the absence of phenotypic markers for Th1 and Th2 cells, several different approaches have been taken to examine T cell responses in detail. Methods involve T-cell proliferation assays, Enzyme-Linked-Immuno-Sorbent-Assay (ELISA) analysis of secreted cytokines and phenotype analysis applying flow cytometry. A more recent development is ELISPOT analysis, which enables the investigator to determine the qualitative and quantitative antigen-specific immune response on a single-cell level with regard to cytokine secretion. This article aims to give an introduction to the advantages and limitations inherent in the different techniques and their potential relevance for immunological studies in diabetes mellitus type 1.