Revisiting regulatory T cells in type 1 diabetes

Current understanding of CTLA-4: from mechanism to autoimmune diseases

Autoimmune diseases (ADs) are characterized by the production of autoreactive lymphocytes, immune responses to self-antigens, and inflammation in related tissues and organs. Cytotoxic T-lymphocyte antigen 4 (CTLA-4) is majorly expressed in activated T cells and works as a critical regulator in the inflammatory response. In this review, we first describe the structure, expression, and how the signaling pathways of CTLA-4 participate in reducing effector T-cell activity and enhancing the immunomodulatory ability of regulatory T (Treg) cells to reduce immune response, maintain immune homeostasis, and maintain autoimmune silence. We then focused on the correlation between CTLA-4 and different ADs and how this molecule regulates the immune activity of the diseases and inhibits the onset, progression, and pathology of various ADs. Finally, we summarized the current progress of CTLA-4 as a therapeutic target for various ADs.

Lichen Sclerosus: A Current Landscape of Autoimmune and Genetic Interplay

Lichen sclerosus (LS) is an acquired chronic inflammatory dermatosis predominantly affecting the anogenital area with recalcitrant itching and soreness. Progressive or persistent LS may cause urinary and sexual disturbances and an increased risk of local skin malignancy with a prevalence of up to 11%. Investigations on lipoid proteinosis, an autosomal recessive genodermatosis caused by loss-of-function mutations in the extracellular matrix protein 1 (ECM1) gene, led to the discovery of a humoral autoimmune response to the identical molecule in LS, providing evidence for an autoimmune and genetic counterpart targeting ECM1. This paper provides an overview of the fundamental importance and current issue of better understanding the immunopathology attributed to ECM1 in LS. Furthermore, we highlight the pleiotropic action of ECM1 in homeostatic and structural maintenance of skin biology as well as in a variety of human disorders possibly associated with impaired or gained ECM1 function, including the inflammatory bowel disease ulcerative colitis, Th2 cell-dependent airway allergies, T-cell and B-cell activation, and the demyelinating central nervous system disease multiple sclerosis, to facilitate sharing the concept as a plausible therapeutic target of this attractive molecule.

High-fat diet prevents the development of autoimmune diabetes in NOD mice

AIMS

Type 1 diabetes (T1D) has a strong genetic predisposition and requires an environmental trigger to initiate the beta-cell autoimmune destruction. The rate of childhood obesity has risen in parallel to the proportion of T1D, suggesting high-fat diet (HFD)/obesity as potential environmental triggers for autoimmune diabetes. To explore this, non-obese diabetic (NOD) mice were subjected to HFD and monitored for the development of diabetes, insulitis and beta-cell stress.

MATERIALS AND METHODS

Four-week-old female NOD mice were placed on HFD (HFD-NOD) or standard chow-diet. Blood glucose was monitored weekly up to 40 weeks of age, and glucose- and insulin-tolerance tests performed at 4, 10 and 15 weeks. Pancreata and islets were analysed for insulin secretion, beta-cell mass, inflammation, insulitis and endoplasmic reticulum stress markers. Immune cell levels were measured in islets and spleens. Stool microbiome was analysed at age 4, 8 and 25 weeks.

RESULTS

At early ages, HFD-NOD mice showed a significant increase in body weight, glucose intolerance and insulin resistance; but paradoxically, they were protected from developing diabetes. This was accompanied by increased insulin secretion and beta-cell mass, decreased insulitis, increased splenic T-regulatory cells and altered stool microbiome.

CONCLUSIONS

This study shows that HFD protects NOD mice from autoimmune diabetes and preserves beta-cell mass and function through alterations in gut microbiome, increased T-regulatory cells and decreased insulitis. Further studies into the exact mechanism of HFD-mediated prevention of diabetes in NOD mice could potentially lead to interventions to prevent or delay T1D development in humans.

Low-dose interleukin-2-loaded nanoparticle effect on NK and T-reg cell expression in experimentally induced type 1 diabetes mellitus

Introduction

Type 1 diabetes mellitus is an autoimmune disorder characterized by inflammatory damage to pancreatic β cells resulting in loss of insulin secretion. In autoimmune type 1 diabetes mellitus (T1D) natural killer cells (NK) initiate pancreatic islets cell lyses in autoimmune T1D. Loss of T regulatory cells (Treg) at disease onset facilitates the activation and accumulation of NKs in the pancreatic microenvironment. A proper low-dose interleukin 2 (IL-2) could enhance Tregs and enforce control and regulation of pro-inflammatory NKs.

Aim

This relation needs to be studied to improve therapeutic strategies aimed at resetting the balance between Tregs and proinflammatory cells.

Material and methods

We used novel formulations of low-dose IL-2 loaded on chitosan nanoparticles. The study included 116 T1D BALB/c mice experimentally induced by streptozotocin, divided into groups. Their splenocytes were maintained in a short-term culture for assessment of expression of CD4+FOXP3+ Treg and NKp46+NK by both flow cytometry and enzyme-linked immunoassay (ELISA). Morphological, immunohistochemical, and morphometrical analyses were done.In vitro suppressor assay was used to assess the suppressor effect of Treg cells after exogenous IL-2 treatment.

Results

NK cell expression, NKp46 level, and NK cell functions were modulated more in mice injected with IL-2-loaded chitosan nanoparticles than in other groups. A statistical inverse correlation was found between Treg and NK cell expression in IL-2-loaded chitosan with 0.3 µIU (p = 0.047), and this correlation was related to FOXP3 expression on Treg cells. The modified expression of NK and NKp46 was noticed in mice injected with 0.3 µIU for longer duration (3 weeks) (p < 0.001), but the NK functions did not show any significant changes with prolonged treatment.

Conclusions

Prolonged administration of low-dose IL-2 results in the vigorous expression of NKp46, indicating a significant role of Tregs in NK stimulation and motivation. Low-dose IL-2 selectively modulates NKp46 NK and FOXP3+ Tregs and increases their expression.

Effect of low dose IL-2 loaded chitosan nanoparticles on natural killer and regulatory T cell expression in experimentally induced autoimmune type 1 diabetes mellitus

Introduction

Natural killer cells (NK) initiate pancreatic islets cell lyses in autoimmune type 1 diabetes mellitus (T1D). Loss of T regulatory cells (Treg) at disease onset facilitates activation and accumulation of NKs in the pancreatic microenvironment. A proper low dose interleukin 2 (IL-2) could enhance Tregs and enforce control and regulation of pro-inflammatory NKs. This relation needs to be studied to improve therapeutic strategies aimed at resetting the balance between Tregs and proinflammatory cells.

Material and methods

We used novel formulations of low dose IL-2 loaded on chitosan nanoparticles. The study included 116 T1D BALB/c mice experimentally induced by streptozotocin, divided into groups. Their splenocytes were maintained in a short-term culture for assessment of expression of CD4⁺Foxp3⁺ Treg and NKp46⁺NK by both flow cytometry and enzyme linked immunoassay (ELISA). In vitro suppressor-assay was used in order to assess the suppressor effect of Treg cells after exogenous IL-2 treatment.

Results

NK cell expression, NKp46 level and NK cell functions were modulated in mice injected with IL-2 loaded chitosan nanoparticles than other groups. A statistical inverse correlation was found between Treg and NK cell expression in IL-2 loaded chitosan with (0.3 µIU) (p = 0.047) and this correlation was related to Foxp3 expression on Treg cells. The modified expression of NK and NKp46 was noticed in mice injected with (0.3 µIU) for longer duration (three weeks) (p < 0.001) but the NK functions did not show any significant changes with prolonged treatment.

Conclusions

Low dose (0.3) µIU IL-2 nanoparticles effectively modulated NK and NKp46 expression. It selectively modulates the suppressive activity of Tregs indicating a significant role of Tregs in NK activation and function by controlling the availability of IL-2 in the microenvironment.

Partial remission in Brazilian children and adolescents with type 1 diabetes. Association with a haplotype of class II human leukocyte antigen and synthesis of autoantibodies

OBJECTIVE

Characterization of partial remission using the insulin dose-adjusted HbA1c (IDAA1c) ≤ 9 definition in a multiethnic Brazilian population of children and adolescents with type 1 diabetes (T1D), in addition with the determination of both Class II HLA genotype and autoantibodies.

METHODS

We analyzed the prevalence of partial remission in 51 new-onset T1D patients with a median time follow-up of 13 months from diagnosis. For this study, anti-GAD65, anti-IA2 and HLA class II genotyping were considered.

RESULTS

Partial remission occurred in 41.2% of T1D patients until 3 months after diagnosis, mainly in those aged 5-15 years. We have demonstrated a significant increase in the haplotypes of class II HLA DRB1*0301-DQB1*0201 in children and adolescents with a partial remission phase of the disease (42.9% vs 21.7% in non-remitters, P = .0291). This haplotype was also associated with the reduction of anti-IA2 antibodies production. Homozygote DRB1*03-DQB1*0201/DRB1*03-DQB1*0201 children had the lowest prevalence of IA-2A antibodies (P = .0402). However, this association does not correlate with the time of the remission phase.

CONCLUSION

Although the number of patients studied was reduced, our data suggested that the association between genetics and decrease in antibody production to certain islet auto-antigen may contribute, at least in part, to the remission phase of T1D.

Increased β-cell proliferation before immune cell invasion prevents progression of type 1 diabetes

Type 1 diabetes (T1D) is characterized by pancreatic islet infiltration by autoreactive immune cells and a near-total loss of β-cells¹. Restoration of insulin-producing β-cells coupled with immunomodulation to suppress the autoimmune attack has emerged as a potential approach to counter T1D^2-4. Here we report that enhancing β-cell mass early in life, in two models of female NOD mice, results in immunomodulation of T-cells, reduced islet infiltration and lower β-cell apoptosis, that together protect them from developing T1D. The animals displayed altered β-cell antigens, and islet transplantation studies showed prolonged graft survival in the NOD-LIRKO model. Adoptive transfer of splenocytes from the NOD-LIRKOs prevented development of diabetes in pre-diabetic NOD mice. A significant increase in the splenic CD4⁺CD25⁺FoxP3⁺ regulatory T-cell (Treg) population was observed to underlie the protected phenotype since Treg depletion rendered NOD-LIRKO mice diabetic. The increase in Tregs coupled with activation of TGF-β/SMAD3 signaling pathway in pathogenic T-cells favored reduced ability to kill β-cells. These data support a previously unidentified observation that initiating β-cell proliferation, alone, prior to islet infiltration by immune cells alters the identity of β-cells, decreases pathologic self-reactivity of effector cells and increases Tregs to prevent progression of T1D.

Cell Based Therapy for Type 1 Diabetes: Should We Take Hyperglycemia Into Account?

Diabetes mellitus is characterized by long standing hyperglycemia leading to numerous life-threatening complications. For type 1 diabetes mellitus, resulting from selective destruction of insulin producing cells by exaggerated immune reaction, the only effective therapy remains exogenous insulin administration. Despite accurate compliance to treatment of certain patients, transient episodes of hyperglycemia cannot be completely eliminated by this symptomatic treatment. Novel immunotherapeutic approaches based on tolerogenic dendritic cells, T regulatory cells and mesenchymal stem cells (MSCs) have been tested in clinical trials, endeavoring to directly modulate the autoimmune destruction process in pancreas. However, hyperglycemia itself affects the immune system and the final efficacy of cell-based immunotherapies could be affected by the different glycemic control of enrolled patients. The present review explores the impact of hyperglycemia on immune cells while providing greater insight into the molecular mechanisms of high glucose action and subsequent metabolic reprogramming of different immune cells. Furthermore, over-production of mitochondrial reactive oxygen species, formation of advanced glycation end products as a consequence of hyperglycemia and their downstream signalization in immune cells are also discussed. Since hyperglycemia in patients with type 1 diabetes mellitus might have an impact on immune-interventional treatment, the maintenance of a tight glucose control seems to be beneficial in patients considered for cell-based therapy.

Thymic B Cell-Mediated Attack of Thymic Stroma Precedes Type 1 Diabetes Development

Type 1 diabetes (T1D) results from a coordinated autoimmune attack of insulin producing beta cells in the pancreas by the innate and adaptive immune systems, beta cell death being predominantly T cell-mediated. In addition to T cells, peripheral B cells are important in T1D progression. The thymus of mice and man also contains B cells, and lately they have been linked to central tolerance of T cells. The role of thymic B cells in T1D is undefined. Here, we show there are abnormalities in the thymic B cell compartment before beta cell destruction and T1D manifestation. Using non-obese diabetic (NOD) mice, we document that preceding T1D development, there is significant accumulation of thymic B cells-partly through in situ development- and the putative formation of ectopic germinal centers. In addition, in NOD mice we quantify thymic plasma cells and observe in situ binding of immunoglobulins to undefined antigens on a proportion of medullary thymic epithelial cells (mTECs). By contrast, no ectopic germinal centers or pronounced intrathymic autoantibodies are detectable in animals not genetically predisposed to developing T1D. Binding of autoantibodies to thymic stroma correlates with apoptosis of mTECs, including insulin-expressing cells. By contrast, apoptosis of mTECs was decreased by 50% in B cell-deficient NOD mice suggesting intrathymic autoantibodies may selectively target certain mTECs for destruction. Furthermore, we observe that these thymic B cell-associated events correlated with an increased prevalence of premature thymic emigration of T cells. Together, our data suggest that the thymus may be a principal autoimmune target in T1D and contributes to disease progression.

The potential pathogenic role of IL-17/Th17 cells in both type 1 and type 2 diabetes mellitus

Diabetes mellitus (DM) is a serious medical problem affecting millions of peoples worldwide, and has a great socio-economic impacts. Cytokines possess a pivotal role in modulation of immune reactions and disease pathogenesis. T-helper type 17 (Th17) cells, an important proinflammatory CD4⁺ T cell subset secreting interleukin 17 (IL-17), has been embroiled in development of DM. There are recent evidences supporting a definitive role of Th17 cells in the etiology of type 1 diabetes (T1D). In addition, IL-17 has been shown to play a crucial role in inflammation, insulin resistance, and type 2 diabetes (T2D). Recently, small molecules which have been specified to block Th17 cells differentiation are considered as potential therapeutics for the disease. Anti-IL-17 neutralizing antibodies and/or antibodies targeting Th17 cells have been investigated to protect individuals at risk from disease development. In this review we aimed to shed light on the potential role of IL-17 and Th17 cells in both T1D and T2D pathogenesis and future therapeutic strategies.

Memory T Cells in Type 1 Diabetes: the Devil is in the Detail

PURPOSE OF REVIEW

Therapies that target beta-cell antigen-specific T cells subsets have not been as successful in patients with type 1 diabetes as in mice. This might be explained by complexities in the repertoire of beta-cell antigen-specific T cells and the variety of T cell subsets involved in type 1 diabetes development in human.

RECENT FINDINGS

T cells that infiltrate islets of people with type 1 diabetes (i) react towards known islet cell antigens but also unknown antigens, (ii) differ from one patient to another, and (iii) are also present in the circulation, but not in the islets, of healthy people. Moreover, several circulating memory T cell subsets not recognized as relevant in mouse are significantly associated with clinical outcome. A more detailed understanding of the specificity, phenotype, and function of T cells that are associated with defined clinical outcomes might identify new pathways for therapeutic intervention.

Antigen presenting cell-targeted proinsulin expression converts insulin-specific CD8+ T-cell priming to tolerance in autoimmune-prone NOD mice

Type 1 diabetes (T1D) results from autoimmune destruction of insulin-producing pancreatic β cells. Therapies need to incorporate strategies to overcome the genetic defects that impair induction or maintenance of peripheral T-cell tolerance and contribute to disease development. We tested whether the enforced expression of an islet autoantigen in antigen-presenting cells (APC) counteracted peripheral T-cell tolerance defects in autoimmune-prone NOD mice. We observed that insulin-specific CD8⁺ T cells transferred to mice in which proinsulin was transgenically expressed in APCs underwent several rounds of division and the majority were deleted. Residual insulin-specific CD8⁺ T cells were rendered unresponsive and this was associated with TCR downregulation, loss of tetramer binding and expression of a range of co-inhibitory molecules. Notably, accumulation and effector differentiation of insulin-specific CD8⁺ T cells in pancreatic lymph nodes was prominent in non-transgenic recipients but blocked by transgenic proinsulin expression. This shift from T-cell priming to T-cell tolerance exemplifies the tolerogenic capacity of autoantigen expression by APC and the capacity to overcome genetic tolerance defects.

The role of adipose-derived inflammatory cytokines in type 1 diabetes

Adipose tissue dysfunction correlates with the development of diabetes. Mice with an adipocyte-specific deletion of the SUMO-specific protease SENP1 develop symptoms of type-1 diabetes mellitus (T1DM). Peri-pancreatic adipocytes (PATs) exert both systemic and paracrine effects on pancreases function. Our recent studies report that PATs of SENP1-deficient mice have increased proinflammatory cytokine production compared with other adipose depots. Proinflammatory cytokines produced from PATs not only have direct cytotoxic effects on pancreatic islets, but also increase CCL5 expression in adjacent pancreatic islets, which induces persistent inflammation in pancreases by acquisition of Th1 and Th17 effector T cell subsets. Small ubiquitin-like modifier (SUMO) can post-translationally conjugate to cellular proteins (SUMOylation) and modulate their biological functions. Several components in SUMOylation associate with T1DM susceptibility. We find that SUMOylation of NF-κB essential molecule NEMO augments NF-κB activity, NF-κB-dependent cytokine production and pancreatic inflammation. NF-κB inhibitor should provide therapeutic approach to block PAT inflammation and ameliorate the T1DM phenotype. We further propose that adipocytes in PATs may play a primary role in establishing pancreatic immune regulation at onset of diabetes, providing new insights into the molecular pathogenesis of type 1 diabetes.

Treg activation defect in type 1 diabetes: correction with TNFR2 agonism

Activated T-regulatory cells (aTregs) prevent or halt various forms of autoimmunity. We show that type 1 diabetics (T1D) have a Treg activation defect through an increase in resting Tregs (rTregs, CD4⁺CD25⁺Foxp3⁺CD45RA) and decrease in aTregs (CD4⁺CD25⁺Foxp3⁺CD45RO) (n= 55 T1D, n=45 controls, P=0.01). The activation defect persists life long in T1D subjects (T1D=45, controls=45, P=0.01, P=0.04). Lower numbers of aTregs had clinical significance because they were associated with a trend for less residual C-peptide secretion from the pancreas (P=0.08), and poorer HbA1C control (P=0.03). In humans, the tumor necrosis factor receptor 2 (TNFR2) is obligatory for Treg induction, maintenance and expansion of aTregs. TNFR2 agonism is a method for stimulating Treg conversion from resting to activated. Using two separate in vitro expansion protocols, TNFR2 agonism corrected the T1D activation defect by triggering conversion of rTregs into aTregs (n=54 T1D, P<0.001). TNFR2 agonism was superior to standard protocols and TNF in proliferating Tregs. In T1D, TNFR2 agonist-expanded Tregs were homogeneous and functionally potent by virtue of suppressing autologous cytotoxic T cells in a dose-dependent manner comparable to controls. Targeting the TNFR2 receptor for Treg expansion in vitro demonstrates a means to correct the activation defect in T1D.

Immune Modulation by Vitamin D and Its Relevance to Food Allergy

Apart from its classical function in bone and calcium metabolism, vitamin D is also involved in immune regulation and has been linked to various cancers, immune disorders and allergic diseases. Within the innate and adaptive immune systems, the vitamin D receptor and enzymes in monocytes, dendritic cells, epithelial cells, T lymphocytes and B lymphocytes mediate the immune modulatory actions of vitamin D. Vitamin D insufficiency/deficiency early in life has been identified as one of the risk factors for food allergy. Several studies have observed an association between increasing latitude and food allergy prevalence, plausibly linked to lower ultraviolet radiation (UVR) exposure and vitamin D synthesis in the skin. Along with mounting epidemiological evidence of a link between vitamin D status and food allergy, mice and human studies have shed light on the modulatory properties of vitamin D on the innate and adaptive immune systems. This review will summarize the literature on the metabolism and immune modulatory properties of vitamin D, with particular reference to food allergy.

Immunological Basis for Rapid Progression of Diabetes in Older NOD Mouse Recipients Post BM-HSC Transplantation

Type I diabetes (T1D), mediated by autoreactive T cell destruction of insulin-producing islet beta cells, has been treated with bone marrow-derived hematopoietic stem cell (BM-HSC) transplantation. Older non-obese diabetic (NOD) mice recipients (3m, at disease-onset stage) receiving syngeneic BM-HSC progressed more rapidly to end-stage diabetes post-transplantation than younger recipients (4-6w, at disease-initiation stage). FACS analyses showed a higher percentage and absolute number of regulatory T cells (Treg) and lower proportion of proliferating T conventional cells (Tcon) in pancreatic lymph nodes from the resistant mice among the younger recipients compared to the rapid progressors among the older recipients. Treg distribution in spleen, mesenteric lymph nodes (MLN), blood and thymus between the two groups was similar. However, the percentage of thymic Tcon and the proliferation of Tcon in MLN and blood were lower in the young resistants. These results suggest recipient age and associated disease stage as a variable to consider in BM-HSC transplantation for treating T1D.

Compound A, a selective glucocorticoid receptor agonist, inhibits immunoinflammatory diabetes, induced by multiple low doses of streptozotocin in mice

BACKGROUND AND PURPOSE

Type 1 diabetes is a multifactorial inflammatory disease that develops as a result of deregulated immune responses, causing progressive autoimmune destruction of insulin-producing beta cells of pancreas. 2-((4-acetoxyphenyl)-2-chloro-N-methyl) ethylammonium chloride, compound A (CpdA), is a selective glucocorticoid receptor (GR) agonist that displays strong anti-inflammatory and immunomodulatory activities. We investigated the therapeutic effectiveness of CpdA in a pharmacological model of type 1 diabetes in mice.

EXPERIMENTAL APPROACH

The utility of CpdA in diabetes prevention was evaluated in vivo through its prophylactic administration to male C57BL/6 mice that received multiple low doses of streptozotocin for immunoinflammatory diabetes induction. The effect of CpdA on disease development was studied by measuring blood glucose and insulin level, histopathological examination, determination of the nature of infiltrating cells, pro- and anti-inflammatory cytokine production, and signalling pathways.

KEY RESULTS

Prophylactic in vivo therapy with CpdA conferred protection against development of immunoinflammatory diabetes in mice by dampening the M1/Th1/Th17 immune response and switching it towards an anti-inflammatory M2/Th2/Treg profile, thus preserving beta cell function.

CONCLUSIONS AND IMPLICATIONS

Anti-diabetic properties of CpdA are mediated through modulation of immune cell-mediated pathways, but without triggering adverse events. These findings provide basic information for the therapeutic use of selective GR agonists in the amelioration of islet-directed autoimmunity.

Advances in the cellular immunological pathogenesis of type 1 diabetes

Type 1 diabetes is an autoimmune disease caused by the immune-mediated destruction of insulin-producing pancreatic β cells. In recent years, the incidence of type 1 diabetes continues to increase. It is supposed that genetic, environmental and immune factors participate in the damage of pancreatic β cells. Both the immune regulation and the immune response are involved in the pathogenesis of type 1 diabetes, in which cellular immunity plays a significant role. For the infiltration of CD4(+) and CD8(+) T lymphocyte, B lymphocytes, natural killer cells, dendritic cells and other immune cells take part in the damage of pancreatic β cells, which ultimately lead to type 1 diabetes. This review outlines the cellular immunological mechanism of type 1 diabetes, with a particular emphasis to T lymphocyte and natural killer cells, and provides the effective immune therapy in T1D, which is approached at three stages. However, future studies will be directed at searching for an effective, safe and long-lasting strategy to enhance the regulation of a diabetogenic immune system with limited toxicity and without global immunosuppression.

Analysis of the expression of candidate genes for type 1 diabetes susceptibility in T cells

Type 1 diabetes is characterized by T-cell-mediated autoimmune destruction of pancreatic β-cells. Currently, approximately 50 type 1 diabetes susceptibility genes or chromosomal regions have been identified. However, the functions of type 1 diabetes susceptibility genes in T cells are elusive. In this study, we evaluated the correlation between type 1 diabetes susceptibility genes and T-cell signaling. The expression levels of 22 candidate type 1 diabetes susceptibility genes in T cells from nonobese diabetic (NOD), control C57BL/6 (B6), and NOD-control F1 hybrid mice were analyzed in response to 2 key immunoregulatory cytokines: interleukin-2 (IL-2) and transforming growth factor β (TGF-β). Exogenous gene expression studies were also performed in EL4 and Jurkat E6.1 T-cell lines. Significant differences in the expression of Clec16a, Dlk1, Il2, Ptpn22, Rnls, and Zac1 (also known as Plagl1) were observed in T cells derived from the 3 strains of mice, and TGF-β differentially influenced the expression of Ctla4, Foxp3, Il2, Ptpn22, Sh2b3, and Zac1. We found that TGF-β induced Zac1 expression in both primary T cells and EL4 cells and that exogenous expression of Zac1 and ZAC1 in T-cell lines altered the expression of Il2 and DLK1, respectively. The results of our study indicate the possibility that additional genetic pathways underlying type 1 diabetes susceptibility, including those involving Clec16a, Dlk1, Rnls, Sh2b3, and Zac1 under IL-2 and TGF-β signaling in T cells, may be shared between human and NOD mice.

Antigen-based vaccination and prevention of type 1 diabetes

Insulin-dependent or type 1 diabetes (T1D) is a paradigm for prevention of autoimmune disease: Pancreatic β-cell autoantigens are defined, at-risk individuals can be identified before the onset of symptoms, and autoimmune diabetes is preventable in rodent models. Intervention in asymptomatic individuals before or after the onset of subclinical islet autoimmunity places a premium on safety, a requirement met only by lifestyle-dietary approaches or autoantigen-based vaccination to induce protective immune tolerance. Insulin is the key driver of autoimmune β-cell destruction in the nonobese diabetic (NOD) mouse model of T1D and is an early autoimmune target in children at risk for T1D. In the NOD mouse, mucosal administration of insulin induces regulatory T cells that protect against diabetes. The promise of autoantigen-specific vaccination in humans has yet to be realized, but recent trials of oral and nasal insulin vaccination in at-risk humans provide grounds for cautious optimism.

Genome-wide DNA methylation analysis identifies hypomethylated genes regulated by FOXP3 in human regulatory T cells

Regulatory T cells (Treg) prevent the emergence of autoimmune disease. Prototypic natural Treg (nTreg) can be reliably identified by demethylation at the Forkhead-box P3 (FOXP3) locus. To explore the methylation landscape of nTreg, we analyzed genome-wide methylation in human naive nTreg (rTreg) and conventional naive CD4(+) T cells (Naive). We detected 2315 differentially methylated cytosine-guanosine dinucleotides (CpGs) between these 2 cell types, many of which clustered into 127 regions of differential methylation (RDMs). Activation changed the methylation status of 466 CpGs and 18 RDMs in Naive but did not alter DNA methylation in rTreg. Gene-set testing of the 127 RDMs showed that promoter methylation and gene expression were reciprocally related. RDMs were enriched for putative FOXP3-binding motifs. Moreover, CpGs within known FOXP3-binding regions in the genome were hypomethylated. In support of the view that methylation limits access of FOXP3 to its DNA targets, we showed that increased expression of the immune suppressive receptor T-cell immunoglobulin and immunoreceptor tyrosine-based inhibitory motif domain (TIGIT), which delineated Treg from activated effector T cells, was associated with hypomethylation and FOXP3 binding at the TIGIT locus. Differential methylation analysis provides insight into previously undefined human Treg signature genes and their mode of regulation.

Environmental determinants of islet autoimmunity (ENDIA): a pregnancy to early life cohort study in children at-risk of type 1 diabetes

BACKGROUND

The incidence of type 1 diabetes has increased worldwide, particularly in younger children and those with lower genetic susceptibility. These observations suggest factors in the modern environment promote pancreatic islet autoimmunity and destruction of insulin-producing beta cells. The Environmental Determinants of Islet Autoimmunity (ENDIA) Study is investigating candidate environmental exposures and gene-environment interactions that may contribute to the development of islet autoimmunity and type 1 diabetes.

METHODS/DESIGN

ENDIA is the only prospective pregnancy/birth cohort study in the Southern Hemisphere investigating the determinants of type 1 diabetes in at-risk children. The study will recruit 1,400 unborn infants or infants less than six months of age with a first-degree relative (i.e. mother, father or sibling) with type 1 diabetes, across five Australian states. Pregnant mothers/infants will be followed prospectively from early pregnancy through childhood to investigate relationships between genotype, the development of islet autoimmunity (and subsequently type 1 diabetes), and prenatal and postnatal environmental factors. ENDIA will evaluate the microbiome, nutrition, bodyweight/composition, metabolome-lipidome, insulin resistance, innate and adaptive immune function and viral infections. A systems biology approach will be used to integrate these data. Investigation will be by 3-monthly assessments of the mother during pregnancy, then 3-monthly assessments of the child until 24 months of age and 6-monthly thereafter. The primary outcome measure is persistent islet autoimmunity, defined as the presence of autoantibodies to one or more islet autoantigens on consecutive tests.

DISCUSSION

Defining gene-environment interactions that initiate and/or promote destruction of the insulin-producing beta cells in early life will inform approaches to primary prevention of type 1 diabetes. The strength of ENDIA is the prospective, comprehensive and frequent systems-wide profiling from early pregnancy through to early childhood, to capture dynamic environmental exposures that may shape the development of islet autoimmunity.

TRIAL REGISTRATION

Australia New Zealand Clinical Trials Registry ACTRN12613000794707.

Adaptive immunity, inflammation, and cardiovascular complications in type 1 and type 2 diabetes mellitus

Diabetes mellitus (DM) is a pandemics that affects more than 170 million people worldwide, associated with increased mortality and morbidity due to coronary artery disease (CAD). In type 1 (T1) DM, the main pathogenic mechanism seems to be the destruction of pancreatic β -cells mediated by autoreactive T-cells resulting in chronic insulitis, while in type 2 (T2) DM primary insulin resistance, rather than defective insulin production due to β -cell destruction, seems to be the triggering alteration. In our study, we investigated the role of systemic inflammation and T-cell subsets in T1- and T2DM and the possible mechanisms underlying the increased cardiovascular risk associated with these diseases.