Control of type 1 diabetes by CD4+Foxp3+ regulatory T cells: lessons from mouse models and implications for human disease

Inulin prebiotic ameliorates type 1 diabetes dictating regulatory T cell homing via CCR4 to pancreatic islets and butyrogenic gut microbiota in murine model

Gut dysbiosis is linked to type 1 diabetes mellitus (T1D). Inulin (INU), a prebiotic, modulates the gut microbiota, promoting beneficial bacteria that produce essential short-chain fatty acids for immune regulation. However, how INU affects T1D remains uncertain. Using a streptozotocin-induced (STZ) mouse model, we studied INU's protective effects. Remarkably, STZ + INU mice resisted T1D, with none developing the disease. They had lower blood glucose, reduced pancreatic inflammation, and normalized serum insulin compared with STZ + SD mice. STZ + INU mice also had enhanced mucus production, abundant Bifidobacterium, Clostridium cluster IV, Akkermansia muciniphila, and increased fecal butyrate. In cecal lymph nodes, we observed fewer CD4+Foxp3+ regulatory T cells expressing CCR4 and more Foxp3+CCR4+ cells in pancreatic islets, with higher CCL17 expression. This phenotype was absent in CCR4-deficient mice on INU. INU supplementation effectively protects against experimental T1D by recruiting CCR4+ regulatory T cells via CCL17 into the pancreas and altering the butyrate-producing microbiota.

Helminth protection against type-1 diabetes: an insight into immunomodulatory effect of helminth-induced infection

Helminths are the old dirty friends of humans from decades and may live undetected by the immune system for years in the tissues. They have evolved as good experts at subverting the immune system. Despite of their pathogenicity, they provide protection to their host against certain inflammatory diseases such as diabetes by modulating the immune mechanisms. These parasites are extra-cellular and induce Th2 response which triggers the adaptive immune cells as well as innate immune cells to work synergistically allowing Tregs to work in a toll-like receptor-dependent manure. T-helper cells type-2 also secrete certain anti-inflammatory cytokines including IL-4, IL-10, IL-13 and TGF-β which also provide protection against type-1 diabetes. Several helminths such as T. crassiceps, S. venezuelensis, filarial worms, Schistosoma spp. and T. spiralis have been reported to prevent diabetes in mouse models as well as in some clinical trials. Immunomodulatory talent of helminths is receiving greater attention to prevent diabetes. Herein, an attempt has been made to review and highlight the possible immuno-modulatory mechanisms by which helminths provide protection against diabetes. Moreover, this review also emphasizes on the use of helminth-derived molecules or synthetic derivatives of helminth-antigens in clinical trials to overcome rapidly growing autoimmune disorders including diabetes.

Fucoidan prevent murine autoimmune diabetes via suppression TLR4-signaling pathways, regulation DC/Treg induced immune tolerance and improving gut microecology

Background

This study was to investigate the effect and its possible mechanism of fucoidan on the development of spontaneous autoimmune diabetes in non-obese diabetic (NOD) mice.

Methods

7-week-old NOD mice were randomly divided into three groups: control group, low-dose (300 mg/kg) and high-dose (600 mg/kg) fucoidan-treatment groups. After 5 weeks of treatment, 10 mice per group were randomly selected to be sacrificed after feces collection. The remaining 12 mice per group were fed until 26 weeks of age to assess the incidence of diabetes.

Results

Treatment with fucoidan increased serum insulin level, delayed the onset and decreased the development of diabetes in NOD mice. Fucoidan reduced the levels of strong Th1 proinflammatory cytokines, but induced Th2-bias ed. cytokine response. And dentridic cells (DCs) in fucoidan treatment group were characterized as low expression of MHC class II and CD86 molecules. TLR4 expressions and the downstream molecules in pancreas were down-regulated in fucoidan-treated groups. There were significant differences in the composition of gut flora between NOD control group and fucoidan group. Lactobacillus and Akkermansia were significantly enriched in fucoidan group.

Conclusions

Fucoidan could prevent the development of autoimmune diabetes in NOD mice via regulating DC/Treg induced immune tolerance, improving gut microecology, down-regulating TLR4 signaling pathway, and maintaining pancreatic internal environment.

Role of regulatory T cells in Schistosoma-mediated protection against type 1 diabetes

The prevalence of T1D in developed societies is partly based on the hygiene hypothesis, that is, the loss of exposure to infectious agents accompanies the loss of immune stimuli shaping the immune system during development. Indeed, the components of parasites, such as Schistosoma, have been reported to ameliorate or prevent the development of T1D, which might be associated with immune cell activity especially that of regulatory T cells (Tregs). Schistosoma infection can lead to the expansion of Treg. Herein, we provide a comprehensive overview of the involvement of Tregs in the response against Schistosoma infection and the mechanism of Schistosoma-associated host protection against T1D.

Helminths protect against type 1 diabetes: effects and mechanisms

Type 1 diabetes (T1D) is an autoimmune disease in which cells of the immune system destroy pancreatic β cells, which secrete insulin. The high prevalence of T1D in developed societies may be explained by environmental changes, including lower exposure to helminths. Indeed, infection by helminths such as Schistosoma, Filaria, and Heligmosomoides polygyrus and their by-products has been reported to ameliorate or prevent the development of T1D in human and animal models. Helminths can trigger distinct immune regulatory pathways, often involving adaptive immune cells that include T helper 2 (Th2) cells and regulatory T cells (Tregs) and innate immune cells that include dendritic cells, macrophages, and invariant natural killer T cells, which may act synergistically to induce Tregs in a Toll-like receptor-dependent manner. Cytokines such as interleukin (IL)-4, IL-10, and transforming growth factor (TGF)-β also play an important role in protection from T1D. Herein, we provide a comprehensive review of the effects and mechanisms underlying protection against T1D by helminths.

CCL22 Prevents Rejection of Mouse Islet Allografts and Induces Donor-Specific Tolerance

Manipulation of regulatory T cell (Treg) migration by islet expression of the chemokine CCL22 prevents diabetes in NOD mice and delays recurrent autoimmunity in syngeneic islet transplants. We sought to determine whether attracting Tregs with CCL22 also prevents islet allograft rejection. Isolated Bl/6 mouse islets were transduced overnight with adenovirus expressing CCL22 (Ad-CCL22) downstream of the CMV promoter. Islets were transplanted under the renal capsule of Balb/c recipients made diabetic by streptozotocin. To assess immunologic tolerance, graft-bearing kidneys from recipients of CCL22-expressing islet grafts were removed, and mice received a second transplant of naive islets from the same donor strain or third-party islets into the contralateral kidney. Adenoviral expression of CCL22 conferred prolonged protection of islet allografts in MHC-mismatched, diabetic recipients, maintaining normoglycemia in 75% of recipients for at least 80 days. Increased frequency of Treg cells was observed in islet grafts transduced with Ad-CCL22 compared with untreated grafts. Normoglycemic recipients of CCL22-expressing islet grafts showed complete absence of antidonor antibodies and no lymphocyte proliferation after exposure to donor splenocytes. After removal of the primary graft at day 80, mice that received a second transplant with untreated islets from the same donor strain did not reject the grafts, suggesting the development of tolerance. Expression of CCL22 recruits Treg cells to transplanted islets, prevents activation of alloreactive T-cells and islet allograft failure and induces alloantigen-specific tolerance. Manipulation of Treg cells by CCL22 in transplanted islets may be a novel therapeutic strategy for diabetes.

A Regulatory T-Cell Gene Signature Is a Specific and Sensitive Biomarker to Identify Children With New-Onset Type 1 Diabetes

Type 1 diabetes (T1D) is caused by immune-mediated destruction of insulin-producing β-cells. Insufficient control of autoreactive T cells by regulatory T cells (Tregs) is believed to contribute to disease pathogenesis, but changes in Treg function are difficult to quantify because of the lack of Treg-exclusive markers in humans and the complexity of functional experiments. We established a new way to track Tregs by using a gene signature that discriminates between Tregs and conventional T cells regardless of their activation states. The resulting 31-gene panel was validated with the NanoString nCounter platform and then measured in sorted CD4(+)CD25(hi)CD127(lo) Tregs from children with T1D and age-matched control subjects. By using biomarker discovery analysis, we found that expression of a combination of six genes, including TNFRSF1B (CD120b) and FOXP3, was significantly different between Tregs from subjects with new-onset T1D and control subjects, resulting in a sensitive (mean ± SD 0.86 ± 0.14) and specific (0.78 ± 0.18) biomarker algorithm. Thus, although the proportion of Tregs in peripheral blood is similar between children with T1D and control subjects, significant changes in gene expression can be detected early in disease process. These findings provide new insight into the mechanisms underlying the failure to control autoimmunity in T1D and might lead to a biomarker test to monitor Tregs throughout disease progression.

Thioreductase-Containing Epitopes Inhibit the Development of Type 1 Diabetes in the NOD Mouse Model

Autoreactive CD4⁺ T cells recognizing islet-derived antigens play a primary role in type 1 diabetes. Specific suppression of such cells therefore represents a strategic target for the cure of the disease. We have developed a methodology by which CD4⁺ T cells acquire apoptosis-inducing properties on antigen-presenting cells after cognate recognition of natural sequence epitopes. We describe here that inclusion of a thiol-disulfide oxidoreductase (thioreductase) motif within the flanking residues of a single MHC class II-restricted GAD65 epitope induces GAD65-specific cytolytic CD4⁺ T cells (cCD4⁺ T). The latter, obtained either in vitro or by active immunization, acquire an effector memory phenotype and lyse APCs by a Fas–FasL interaction. Furthermore, cCD4⁺ T cells eliminate by apoptosis activated bystander CD4⁺ T cells recognizing alternative epitopes processed by the same APC. Active immunization with a GAD65 class II-restricted thioreductase-containing T cell epitope protects mice from diabetes and abrogates insulitis. Passive transfer of in vitro-elicited cCD4⁺ T cells establishes that such cells are efficient in suppressing autoimmunity. These findings provide strong evidence for a new vaccination strategy to prevent type 1 diabetes.

Transcriptome profiling of human FoxP3+ regulatory T cells

The major goal of this study was to perform an in depth characterization of the "gene signature" of human FoxP3(+) T regulatory cells (Tregs). Highly purified Tregs and T conventional cells (Tconvs) from multiple healthy donors (HD), either freshly explanted or activated in vitro, were analyzed via RNA sequencing (RNA-seq) and gene expression changes validated using the nCounter system. Additionally, we analyzed microRNA (miRNA) expression using TaqMan low-density arrays. Our results confirm previous studies demonstrating selective gene expression of FoxP3, IKZF2, and CTLA4 in Tregs. Notably, a number of yet uncharacterized genes (RTKN2, LAYN, UTS2, CSF2RB, TRIB1, F5, CECAM4, CD70, ENC1 and NKG7) were identified and validated as being differentially expressed in human Tregs. We further characterize the functional roles of RTKN2 and LAYN by analyzing their roles in vitro human Treg suppression assays by knocking them down in Tregs and overexpressing them in Tconvs. In order to facilitate a better understanding of the human Treg gene expression signature, we have generated from our results a hypothetical interactome of genes and miRNAs in Tregs and Tconvs.

Extracorporeal photopheresis as a therapy for autoimmune diseases

Systemic autoimmune diseases (AID) have multiorgan, heterogeneous clinical presentations and are characterized by dysregulation of the immune system, immunodeficiency, irreversible organ damage and increased morbidity and mortality. Preventing or decreasing flares of AID correlate with durable disease control, significant reduction of inflammation and prevention of disability or therapy-related toxicity. There is an urgent need for better treatment of severe, therapy-refractory AID. Extracorporeal photopheresis (ECP) is a cell-based immunomodulatory treatment which has been extensively used in variety of autoimmune disorders for the last two decades. ECP treatment is FDA approved for the treatment of cutaneous T-cell lymphoma (CTCL) with particularly promising results seen in graft-versus-host disease (GVHD) after allogeneic hematopoietic stem cell transplantation (HCT). Prolonged therapy is safe, well tolerated and allows reduction of systemic immunosuppression in therapy-refractory patients. Both clinical and experimental evidence suggest that ECP mechanism of action is characterized by apoptosis and phagocytosis of activated cells by antigen-presenting cells (APC), secretion of anti-inflammatory cytokines and stimulation of regulatory T cells (Tregs). The focus of this paper is to review the current evidence of ECP use in the treatment of AID. Here, we summarize the experience of nine major AID from 65 published reports. The key findings demonstrate substantial evidence of ECP feasibility, safety and in some AID also promising efficacy. However, the role of ECP in AID therapy is not established as most published studies are retrospective with limited number of patients and the trials are small or poorly standardized. The available data support future investigations of ECP as a therapeutic modality for the treatment of AID in well-designed prospective clinical studies. J

Evaluation of immunosuppressive function of regulatory T cells using a novel in vitro cytotoxicity assay

Naturally occurring regulatory T cells (Tregs) play a pivotal role in the maintenance of self-tolerance due to their intrinsic immunosuppressive activity. Currently, a number of human clinical trials are being conducted to investigate the roles of Tregs in treating various immune-mediated disorders. Traditionally, the suppressive activity of Tregs is measured using either a thymidine incorporation assay, which is a radioactive assay; or CFSE based flow cytometry assay, which requires a relatively large number of cells. Consequently, there is an increasing need to develop novel alternative bioassays that can characterize various aspects of the immunosuppressive function of Tregs in vitro. In this study, using murine clonal CD8(+) T cells specific for an islet antigen as responder T cells, we first established a novel, sensitive and quantitative in vitro luminescence based cell viability assay to measure cytotoxicity. Then we used this assay to measure if Tregs could inhibit the cytotoxicity of CD8 effector T cells. This assay does not involve the use of radioisotopes and only needs relatively low number of Tregs. Since normally Tregs only constitute 5-10% of peripheral CD4(+) T cells, this advantage is noteworthy compared with other methods. With the assay we developed, we demonstrated that regulatory T cells (Tregs) could inhibit the antigen-specific killing of an adherent target cell monolayer by the CD8(+) cytotoxic T cells. We observed more inhibition when Tregs and CD8 killer T cells were incubated during the in vitro activation (stimulation) stage of the cytotoxic T lymphocytes (CTL) than when they were added later at the start of the effector phase. Interestingly, Tregs from B6 mice demonstrated higher suppression of CD8(+) T cell killing than Tregs from NOD mice. Moreover, IL-2/anti-IL-2 mAb complexes induced expansion of Tregs in vivo, as well as enhancing the Treg's suppressive activity per cell. Therefore, this novel non-radioactive, luminescence based cytotoxicity assay mediated by clonal islet antigen-specific CD8 T cells can be used to measure, characterize, and quantitate the immunosuppressive activity of natural Tregs, representing a useful approach to characterize the functions of Tregs in the setting of autoimmune diseases and to elucidate the mechanisms for Treg cell-mediated immunoregulation.

Undifferentiated Wharton's Jelly Mesenchymal Stem Cell Transplantation Induces Insulin-Producing Cell Differentiation and Suppression of T-Cell-Mediated Autoimmunity in Nonobese Diabetic Mice

Type 1 diabetes mellitus is caused by T-cell-mediated autoimmune destruction of pancreatic β-cells. Systemic administration of mesenchymal stem cells (MSCs) brings about their incorporation into a variety of tissues with immunosuppressive effects, resulting in regeneration of pancreatic islets. We previously showed that human MSCs isolated from Wharton's jelly (WJ-MSCs) represent a potential cell source to treat diabetes. However, the underlying mechanisms are unclear. The purpose of this study was to discern whether undifferentiated WJ-MSCs can differentiate into pancreatic insulin-producing cells (IPCs) and modify immunological responses in nonobese diabetic (NOD) mice. Undifferentiated WJ-MSCs underwent lentiviral transduction to express green fluorescent protein (GFP) and then were injected into the retro-orbital venous sinus of NOD mice. Seven days after transplantation, fluorescent islet-like cell clusters in the pancreas were apparent. WJ-MSC-GFP-treated NOD mice had significantly lower blood glucose and higher survival rates than saline-treated mice. Systemic and local levels of autoaggressive T-cells, including T helper 1 cells and IL-17-producing T-cells, were reduced, and regulatory T-cell levels were increased. Furthermore, anti-inflammatory cytokine levels were increased, and dendritic cells were decreased. At 23 days, higher human C-peptide and serum insulin levels and improved glucose tolerance were found. Additionally, WJ-MSCs-GFP differentiated into IPCs as shown by colocalization of human C-peptide and GFP in the pancreas. Significantly more intact islets and less severe insulitis were observed. In conclusion, undifferentiated WJ-MSCs can differentiate into IPCs in vivo with immunomodulatory effects and repair the destroyed islets in NOD mice.

Restoration of the unfolded protein response in pancreatic β cells protects mice against type 1 diabetes

Perturbations in endoplasmic reticulum (ER) homeostasis can evoke stress responses leading to aberrant glucose and lipid metabolism. ER dysfunction is linked to inflammatory disorders, but its role in the pathogenesis of autoimmune type 1 diabetes (T1D) remains unknown. We identified defects in the expression of unfolded protein response (UPR) mediators ATF6 (activating transcription factor 6) and XBP1 (X-box binding protein 1) in β cells from two different T1D mouse models and then demonstrated similar defects in pancreatic β cells from T1D patients. Administration of a chemical ER stress mitigator, tauroursodeoxycholic acid (TUDCA), at the prediabetic stage resulted in a marked reduction of diabetes incidence in the T1D mouse models. This reduction was accompanied by (i) a significant decrease in aggressive lymphocytic infiltration in the pancreas, (ii) improved survival and morphology of β cells, (iii) reduced β cell apoptosis, (iv) preserved insulin secretion, and (v) restored expression of UPR mediators. TUDCA's actions were dependent on ATF6 and were lost in mice with β cell-specific deletion of ATF6. These data indicate that proper maintenance of the UPR is essential for the preservation of β cells and that defects in this process can be chemically restored for preventive or therapeutic interventions in T1D.

Mode of delivery shapes gut colonization pattern and modulates regulatory immunity in mice

Delivery mode has been associated with long-term changes in gut microbiota composition and more recently also with changes in the immune system. This has further been suggested to link Cesarean section (C-section) with an increased risk for development of immune-mediated diseases such as type 1 diabetes. In this study, we demonstrate that both C-section and cross-fostering with a genetically distinct strain influence the gut microbiota composition and immune key markers in mice. Gut microbiota profiling by denaturing gradient gel electrophoresis and 454/FLX-based 16S rRNA gene amplicon sequencing revealed that mice born by C-section had a distinct bacterial profile at weaning characterized by higher abundance of Bacteroides and Lachnospiraceae, and less Rikenellaceae and Ruminococcus. No clustering according to delivery method as determined by principal component analysis of denaturing gradient gel electrophoresis profiles was evident in adult mice. However, the adult C-section-born mice had lower proportions of Foxp3(+) regulatory T cells, tolerogenic CD103(+) dendritic cells, and less Il10 gene expression in mesenteric lymph nodes and spleens. This demonstrates long-term systemic effect on the regulatory immune system that was also evident in NOD mice, a model of type 1 diabetes, born by C-section. However, no effect of delivery mode was seen on diabetes incidence or insulitis development. In conclusion, the first exposure to microorganisms seems to be crucial for the early life gut microbiota and priming of regulatory immune system in mice, and mode of delivery strongly influences this.

Consumption of acidic water alters the gut microbiome and decreases the risk of diabetes in NOD mice

Infant formula and breastfeeding are environmental factors that influence the incidence of Type 1 Diabetes (T1D) as well as the acidity of newborn diets. To determine if altering the intestinal microbiome is one mechanism through which an acidic liquid plays a role in T1D, we placed non-obese diabetic (NOD)/ShiLtJt mice on neutral (N) or acidified H2O and monitored the impact on microbial composition and diabetes incidence. NOD-N mice showed an increased development of diabetes, while exhibiting a decrease in Firmicutes and an increase in Bacteroidetes, Actinobacteria, and Proteobacteria from as early as 2 weeks of age. NOD-N mice had a decrease in the levels of Foxp3 expression in CD4(+)Foxp3(+) cells, as well as decreased CD4(+)IL17(+) cells, and a lower ratio of IL17/IFNγ CD4+ T-cells. Our data clearly indicates that a change in the acidity of liquids consumed dramatically alters the intestinal microbiome, the presence of protective Th17 and Treg cells, and the incidence of diabetes. This data suggests that early dietary manipulation of intestinal microbiota may be a novel mechanism to delay T1D onset in genetically pre-disposed individuals.

Maternal obesity exacerbates insulitis and type 1 diabetes in non-obese diabetic mice

Accompanying the dramatic increase in maternal obesity, the incidence of type 1 diabetes (T1D) in children is also rapidly increasing. The objective of this study was to explore the effects of maternal obesity on the incidence of T1D in offspring using non-obese diabetic (NOD) mice, a common model for TID. Four-week-old female NOD mice were fed either a control diet (10% energy from fat, CON) or a high-fat diet (60% energy from fat) for 8 weeks before mating. Mice were maintained in their respective diets during pregnancy and lactation. All offspring mice were fed the CON to 16 weeks. Female offspring (16-week-old) born to obese dams showed more severe islet lymphocyte infiltration (major manifestation of insulitis) (P<0.01), concomitant with elevated nuclear factor kappa-light-chain-enhancer of activated B cells p65 signaling (P<0.01) and tumor necrosis factor alpha protein level (P<0.05) in the pancreas. In addition, maternal obesity resulted in impaired (P<0.05) glucose tolerance and lower (P<0.05) serum insulin levels in offspring. In conclusion, maternal obesity resulted in exacerbated insulitis and inflammation in the pancreas of NOD offspring mice, providing a possible explanation for the increased incidence of T1D in children.

Premature CD4+ T cell aging and its contribution to lymphopenia-induced proliferation of memory cells in autoimmune-prone non-obese diabetic mice

Lymphopenia-induced proliferation (LIP), a mechanism to maintain a constant number of T cells in circulation, occurs in both normal aging and autoimmune disease. The incidence of most autoimmune diseases increases with age, and premature CD4(+) T cell aging has been reported in several autoimmune diseases. In this study, we tested the hypothesis that premature CD4(+) T cell aging can cause autoimmune disease by examining whether premature CD4(+) T cell aging exists and causes LIP in our mouse model. Non-obese diabetic (NOD) mice were used because, in addition to Treg defects, the LIP of T cells has been shown to plays a causative role in the development of insulin-dependent diabetes mellitus (IDDM) in these mice. We found that with advancing age, NOD mice exhibited an accelerated decrease in the number of CD4(+) T cells due to the loss of naïve cells. This was accompanied by an increase in the percentage of memory cells, leading to a reduced naïve/memory ratio. In addition, both the percentage of CD28(+) cells in CD4(+) T cells and IL-2 production decreased, while the percentage of FAS(+)CD44(+) increased, suggesting that NOD mice exhibit premature CD4(+) T cell aging. This process preferentially contributed to LIP of memory cells. Therefore, our results suggest that premature CD4(+) T cell aging underlies the development of IDDM in NOD mice. Given that CD28 and IL-2 play important roles in Treg function, the relationships between premature CD4(+) T cell aging and lymphopenia as well as Treg defects in autoimmune-prone NOD mice are proposed.

Epigenetic changes in inflammatory and autoimmune diseases

In higher eukaryotic organisms epigenetic modifications are crucial for proper chromatin folding and thereby proper regulation of gene expression. In the last years the involvement of aberrant epigenetic modifications in inflammatory and autoimmune diseases has been recognized and attracted significant interest. However, the epigenetic mechanisms underlying the different disease phenotypes are still poorly understood. As autoimmune and inflammatory diseases are at least partly T cell mediated, we will provide in this chapter an introduction to the epigenetics of T cell differentiation followed by a summary of the current knowledge on aberrant epigenetic modifications that dysfunctional T cells display in various diseases such as type 1 diabetes, rheumatoid arthritis, systemic lupus erythematosus, multiple sclerosis, inflammatory bowel disease, and asthma.

Surge in regulatory T cells does not prevent onset of hyperglycemia in NOD mice: immune profiles do not correlate with disease severity

Immune profiling of non-obese diabetic (NOD) is a widely employed tool to assess the mechanisms of inflammatory insulitis. Our analysis of the female NOD colony revealed similar distribution of lymphoid lineages to wild type mice, and at various ages of prediabetic and diabetic mice. The profiles of mesenteric and pancreatic lymph nodes differ and often change reciprocally due to directed migration of T cells towards the site of inflammation. Significant events in our colony include early decline in CD4(+)CD25(+)CD62L(+) Treg, accompanied by gradual increase in CD4(+)CD25(+)FoxP3(+) Treg in peripheral lymphoid organs and pancreatic infiltrates. Impressively, aged euglycemic mice display significant transient rise in CD4(+)CD25(-)FoxP3(+) Treg in the thymus, pancreas and draining lymph nodes. A significant difference was superior viability of effector and suppressor cells from new onset diabetics in the presence of high interleukin-2 (IL-2) concentrations in vitro as compared to cells of prediabetic mice. Overall, we found no correlation between FoxP3(+) Treg in the pancreatic lymph nodes and the inflammatory scores of individual NOD mice. CD25(-)FoxP3(+) Treg are markedly increased in the pancreatic infiltrates in late stages of inflammation, possibly an effort to counteract destructive insulitis. Considering extensive evidence that Treg in aged NOD mice are functionally sufficient, quantitative profiling evolves as an unreliable tool to assess mechanism and causes of inflammation under baseline conditions. Immune profiles are modulated by thymic output, cell migration, shedding of markers, proliferation, survival and in-situ evolution of regulatory cells.

Bacille Calmette-Guérin/DNAhsp65 prime-boost is protective against diabetes in non-obese diabetic mice but not in the streptozotocin model of type 1 diabetes

Type I diabetes is a disease caused by autoimmune destruction of the beta cells in the pancreas that leads to a deficiency in insulin production. The aim of this study was to evaluate the prophylactic potential of a prime-boost strategy involving bacille Calmette-Guérin (BCG) and the pVAXhsp65 vaccine (BCG/DNAhsp65) in diabetes induced by streptozotocin (STZ) in C57BL/6 mice and also in spontaneous type 1 diabetes in non-obese diabetic (NOD) mice. BCG/DNAhsp65 vaccination in NOD mice determined weight gain, protection against hyperglycaemia, decreased islet inflammation, higher levels of cytokine production by the spleen and a reduced number of regulatory T cells in the spleen compared with non-immunized NOD mice. In the STZ model, however, there was no significant difference in the clinical parameters. Although this vaccination strategy did not protect mice in the STZ model, it was very effective in NOD mice. This is the first report demonstrating that a prime-boost strategy could be explored as an immunomodulatory procedure in autoimmune diseases.

FOXP3⁺ T regulatory cell modifications in inflammatory bowel disease patients treated with anti-TNFα agents

Treg modulation has been hypothesized as one of the mechanisms by which antitumor necrosis factor α (TNFα) agents exert their action in rheumatoid arthritis (RA) and inflammatory bowel disease (IBD). However, data in IBD are still conflicting. We evaluated CD4⁺CD25⁺FOXP3⁺ (Tregs) by flow cytometry in peripheral blood from 32 adult IBD patient before (T0) and after the induction of anti-TNFα therapy (T1). Eight healthy controls (HCs) were included. We also evaluated the number of FOXP3⁺ cells in the lamina propria (LP) in biopsies taken in a subset of patients and controls. Treg frequencies were significantly increased in peripheral blood from our patients after anti-TNFα therapy compared to T0. T1 but not T0 levels were higher than HC. The increase was detectable only in clinical responders to the treatment. A negative correlation was found among delta Treg levels and the age of patients or disease duration and with the activity score of Crohn's disease (CD). No significant differences were found in LP FOXP3⁺ cells. Our data suggest the possibility that in IBD patients the treatment with anti-TNFα may affect Treg percentages and that Treg modifications may correlate with clinical response, but differently in early versus late disease.

Total coumarins from Urtica dentata Hand prevent murine autoimmune diabetes via suppression of the TLR4-signaling pathways

ETHNOPHARMACOLOGICAL RELEVANCE

Urtica dentata Hand (UDH), the root of Laportea bulbifera (Sieb. et. Zucc.) Wedd, has been traditionally used in traditional Chinese medicine as an anti-inflammatory and immuno-regulatory agent for rheumatoid arthritis and some other autoimmune diseases treatment. And the coumarins are the major components of UDH.

AIM OF THE STUDY

To investigate the effect of total coumarins (TC) isolated from UDH on the development of autoimmune diabetes.

MATERIALS AND METHODS

Eight-week-old non-obese diabetic (NOD) mice were randomly divided into four groups: control group, low-dose (37.5 mg/kg), middle-dose (75 mg/kg), and high-dose (150 mg/kg) TC-treatment groups. NOD mice were then given with a suspension of TC or saline by intragastric (i.g.) administration every other day. After 4 weeks of treatment, 8 mice at 12-weeks of age per group were randomly selected to be sacrificed to perform intraperitoneal glucose tolerance test, examine histopathological insulitis, spleen T lymphocyte proliferation, the percentage of CD4+CD25+Foxp3+ T regulatory cell (Treg), dendritic cell (DC) surface molecules, toll-like receptor (TLR)4 expression and signal pathways involved. The remaining 10 mice per group were kept until 26 weeks of age to assess the incidence of diabetes. We also studied the direct effect of TC on DC and CD4+CD25+ Tregs in vitro.

RESULTS

Treatment with TC for 4 weeks significantly inhibited insulitis, increased pancreatic islet number, delayed the onset and decreased the development of diabetes by 26 weeks of age in NOD mice, compared with the untreated control mice. TC suppressed spleen T lymphocyte proliferation, induced Th2-biased cytokine response, the generation of CD4+CD25+Foxp3+ Tregs and Foxp3 mRNA expression. And TC-treated DCs were characterized as low expression of MHC class II and CD86 molecules. TLR4 gene and protein expressions in the spleen, thymus and pancreas were down-regulated in TC-treated groups. The key molecules in the downstream signaling cascades of TLR4, including myeloid differentiation factor (MyD)88, nuclear factor (NF)-κB, IL-1β, Toll-IL-1 receptor domain-containing adaptor inducing interferon-β(TRIF), TRIF-related adaptor molecule (TRAM), interferon regulatory factor (IRF)-3 and IFN-β, all decreased significantly in TC groups, suggesting that TC inhibits both MyD88-dependent and -independent pathways of TLR4. At the cellular level, however, TLR4 protein expression in DCs, but not in Tregs, was downregulated by TC. And TC strengthened the role of DC, not Treg, in negative immune regulation in vitro. In contrast, anti-TLR4 antibody could block the effect of TC on DCs immune function.

CONCLUSION

These results suggest that TC extracted from UDH prevent the development of autoimmune diabetes in NOD mice via suppression of the TLR4-signaling pathways. TC maintain the DCs in an immature tolerogenic state, at least in part, mediated by down-regulating TLR4-signaling pathways in DCs, then enhance Treg differentiation, shift toward Th2 and suppress T lymphocyte proliferation.

Targeting regulatory T cells in the treatment of type 1 diabetes mellitus

Type 1 diabetes mellitus (T1DM) is a T cell-mediated autoimmune disease resulting in islet β cell destruction, hypoinsulinemia, and severely altered glucose homeostasis. T1DM has classically been attributed to the pathogenic actions of auto-reactive effector T cells(Teffs) on the β cell. Recent literature now suggests that a failure of a second T cell subtype, known as regulatory T cells (Tregs), plays a critical role in the development of T1DM. During immune homeostasis, Tregs counterbalance the actions of autoreactive Teff cells, thereby participating in peripheral tolerance. An imbalance in the activity between Teff and Tregs may be crucial in the breakdown of peripheral tolerance, leading to the development of T1DM. In this review, we summarize our current understanding of Treg function in health and in T1DM, and examine the effect of experimental therapies for T1DM on Treg cell number and function in both mice and humans.

The influence of the microbiota on type-1 diabetes: on the threshold of a leap forward in our understanding

The last several years have seen breakthroughs in techniques to track the symbiont communities that normally colonize mammals (the microbiota) and in cataloguing the universe of the genes they carry (the microbiome). Applying these methods to human patients and corresponding murine models should allow us to decipher just how the microbiota impacts type-1 diabetes, i.e. which particular microbes are responsible and the cellular and molecular processes that are involved. Here, at its threshold, we set the stage for what promises to be an exciting rejuvenated area of investigation.

Regulatory T cells contribute to diabetes protection in lipopolysaccharide-treated non-obese diabetic mice

It is well established that viral, parasitic or bacterial infections can prevent type 1 diabetes (T1D) occurrence in non-obese diabetic (NOD) mice. On the other hand, defects in CD4(+) Regulatory T cell (Treg) numbers and/or function contribute to T1D aetiology in NOD mice and in humans. In this work, we formally tested whether the protective role of the bacterial product lipopolysaccharide (LPS) on diabetes incidence results from enhanced Treg activity. We first report that weekly administration of LPS to young prediabetic NOD mice, presenting or not insulitis at the time of treatment, afforded full protection from diabetes. Taking advantage from the high but incomplete penetrance of diabetes in NOD mice raised in specific pathogen free (SPF) conditions we compared untreated disease-free old animals with gender- and age-matched LPS-treated mice. Histological and flow cytometry analysis indicated that LPS treatment did not prevent islet infiltration or priming of diabetogenic T cells but increased Foxp3(+) and CD103(+) Treg frequency and numbers. By performing adoptive transfer experiments into alymphoid NOD/SCID recipients, we further demonstrated that CD25(+) cells from LPS-treated NOD mice, but not from naturally protected animals, maintained diabetogenic cells at check. Our study suggests that T cell regulation represents a cellular mechanism to explain the 'hygiene hypothesis' and reinforces the notion that immune activity consolidates dominant tolerance.

Japanese herbal medicine TJ-48 prevents autoimmune diabetes in NOD mice

Type 1 diabetes mellitus (T1DM) is mainly caused by CD8(+) cytotoxic T cell infiltration into islets. Recently, the role of regulatory T cells (Tregs) in the prevention of the onset of T1DM was reported. We reported that TJ-48, a common Japanese herbal medicine, decreased Treg population in cancer patients, thus we investigated whether TJ-48 had an influence on T1DM onset using NOD mice. In the TJ-48 group, TJ-48 (2.0g/kg/day) was administered in the drinking water for NOD mice from three weeks of age to 20 weeks of age. Their body weight and fast blood glucose (FBG) were measured every week. Histology (Hematoxylin-Eosin staining) was investigated every month. Lymphocyte profiles were investigated every month with FACS. The results were compared to the age-matched NOD mice control group. FBG of the control group mice showed diabetic status of 66.7% at 18 weeks of age. On the other hand, the TJ-48 group mice showed diabetic status of 16.7% at 18 weeks of age (p = 1.905E-06). There were no significant differences in general conditions or body weight between the two groups. Lymphocyte infiltrations into islets were dramatically suppressed in the TJ-48 group. The effect of TJ-48 on decreasing Tregs was less apparent in the NOD mice model. TJ-48 inhibited lymphocyte infiltrations into islets, which led to preventing the onset of T1DM in NOD mice.

Fatal pancreatitis in simian immunodeficiency virus SIV(mac251)-infected macaques treated with 2',3'-dideoxyinosine and stavudine following cytotoxic-T-lymphocyte-associated antigen 4 and indoleamine 2,3-dioxygenase blockade

Human immunodeficiency virus (HIV) infection is associated with immune activation, CD4⁺-T-cell loss, and a progressive decline of immune functions. Antiretroviral therapy (ART) only partially reverses HIV-associated immune dysfunction, suggesting that approaches that target immune activation and improve virus-specific immune responses may be needed. We performed a preclinical study in rhesus macaques infected with the pathogenic simian immunodeficiency virus SIV(mac251) and treated with ART. We tested whether vaccination administered together with cytotoxic-T-lymphocyte-associated antigen 4 (CTLA-4) blockade and treatment with the indoleamine 2,3-dioxygenase (IDO) inhibitor 1-methyl-D-tryptophan (D-1mT), decreased immune activation and improved vaccine efficacy. The treatment did not augment vaccine immunogenicity; rather, it dramatically increased ART-related toxicity, causing all treated animals to succumb to acute pancreatitis and hyperglycemic coma. The onset of fulminant diabetes was associated with severe lymphocyte infiltration of the pancreas and complete loss of the islets of Langerhans. Thus, caution should be used when considering approaches aimed at targeting immune activation during ART.

Prevention of murine autoimmune diabetes by CCL22-mediated Treg recruitment to the pancreatic islets

Type 1 diabetes is characterized by destruction of insulin-producing β cells in the pancreatic islets by effector T cells. Tregs, defined by the markers CD4 and FoxP3, regulate immune responses by suppressing effector T cells and are recruited to sites of action by the chemokine CCL22. Here, we demonstrate that production of CCL22 in islets after intrapancreatic duct injection of double-stranded adeno-associated virus encoding CCL22 recruits endogenous Tregs to the islets and confers long-term protection from autoimmune diabetes in NOD mice. In addition, adenoviral expression of CCL22 in syngeneic islet transplants in diabetic NOD recipients prevented β cell destruction by autoreactive T cells and thereby delayed recurrence of diabetes. CCL22 expression increased the frequency of Tregs, produced higher levels of TGF-β in the CD4+ T cell population near islets, and decreased the frequency of circulating autoreactive CD8+ T cells and CD8+ IFN-γ–producing T cells. The protective effect of CCL22 was abrogated by depletion of Tregs with a CD25-specific antibody. Our results indicate that islet expression of CCL22 recruits Tregs and attenuates autoimmune destruction of β cells. CCL22-mediated recruitment of Tregs to islets may be a novel therapeutic strategy for type 1 diabetes.

IL-2 as a therapeutic target for the restoration of Foxp3+ regulatory T cell function in organ-specific autoimmunity: implications in pathophysiology and translation to human disease

Peripheral immune tolerance requires a finely controlled balance between tolerance to self-antigens and protective immunity against enteric and invading pathogens. Self-reactive T cells sometimes escape thymic clonal deletion, and can subsequently provoke autoimmune diseases such as type 1 diabetes (T1D) unless they are controlled by a network of tolerance mechanisms in the periphery, including CD4+ regulatory T cells (Treg) cells. CD4+ Treg cells are characterized by the constitutive expression of the IL-2Rα chain (CD25) and preferentially express the forkhead winged helix transcriptional regulator Foxp3. These cells have been shown to possess immunosuppressive properties towards various immune cell subsets and their defects are thought to contribute to many autoimmune disorders. Strong evidence shows that IL-2 is one of the important stimulatory signals for the development, function and fitness of Treg cells. The non-obese diabetic (NOD) mouse model, a prototypic model of spontaneous autoimmunity, mimics many features of human T1 D. Using this model, the contribution of the IL-2-IL-2R pathway to the development of T1 D and other autoimmune disorders has been extensively studied. In the past years, strong genetic and molecular evidence has indicated an essential role for the IL-2/IL-2R pathway in autoimmune disorders. Thus, the major role of IL-2 is to maintain immune tolerance by promoting Treg cell development, functional fitness and stability. Here we first summarize the genetic and experimental evidence demonstrating a role for IL-2 in autoimmunity, mainly through the study of the NOD mouse model, and analyze the cellular and molecular mechanisms of its action on Treg cells. We then move on to describe how this data can be translated to applications for human autoimmune diseases by using IL-2 as a therapeutic agent to restore Treg cell fitness, numbers and functions.

Type 1 diabetes in BioBreeding rats is critically linked to an imbalance between Th17 and regulatory T cells and an altered TCR repertoire

Diabetes-prone BioBreeding (DP-BB) rats spontaneously develop type 1 diabetes mellitus (T1DM) on grounds of their MHC haplotype RT1(u) and a point mutation in the Gimap5 gene. In this study, we report that DP-BB rats exhibit an increasingly severe imbalance, in particular between Th17 and regulatory T (T(reg)) cells, within the first months of age. This can be assigned to an excess in effector T cells because neither the percentage nor the function of the T(reg) cells is compromised. Flow cytometric analysis of Vbeta segment usage and CDR3 spectratyping further suggest that the disturbed repertoire of peripheral T cells may also contribute to the development of T1DM in DP-BB rats. Importantly, expansion of T(reg) cells in vivo by means of a CD28 superagonistic Ab as well as adoptive transfer of T(reg) cells efficiently interferes with the development of T1DM in DP-BB rats, whereas treatment with conventional Th cells does not afford protection. Using a newly generated strain of enhanced GFP transgenic rats, we could further demonstrate that the transferred T(reg) cells persist in the recipient rats for several months and partially correct the imbalance between Th17 and T(reg) cells. Thus, our data support the hypothesis that unchecked effector T cell action and a disturbed T cell repertoire contribute to the development of T1DM in DP-BB rats, which may also have implications for a better understanding of the human disease.

Processing and presentation of (pro)-insulin in the MHC class II pathway: the generation of antigen-based immunomodulators in the context of type 1 diabetes mellitus

Both CD4(+) and CD8(+) T lymphocytes play a crucial role in the autoimmune process leading to T1D. Dendritic cells take up foreign antigens and autoantigens; within their endocytic compartments, proteases degrade exogenous antigens for subsequent presentation to CD4(+) T cells via MHC class II molecules. A detailed understanding of autoantigen processing and the identification of autoantigenic T cell epitopes are crucial for the development of antigen-based specific immunomodulators. APL are peptide analogues of auto-immunodominant T cell epitopes that bind to MHC class II molecules and can mediate T cell activation. However, APL can be rapidly degraded by proteases occurring in the extracellular space and inside cells, substantially weakening their efficiency. By contrast, protease-resistant APL function as specific immunomodulators and can be used at low doses to examine the functional plasticity of T cells and to potentially interfere with autoimmune responses. Here, we review the latest achievements in (pro)-insulin processing in the MHC class II pathway and the generation of APL to mitigate autoreactive T cells and to activate Treg cells.

The role of the physician-scientist in bridging basic and clinical research in type 1 diabetes

PURPOSE OF REVIEW

In a relatively short time, advances in both basic science and clinical medicine have revolutionized the way we understand disease processes and suggested novel approaches that may be able to be used to treat or cure some of the most relevant human afflictions. In type 1 diabetes, one unintended consequence of this has been the polarization of the investigational groups (i.e., immunologists and endocrinologists) interested in developing novel therapies for this condition. This review will examine how and why such polarization exists, and why past and current approaches to develop critically needed translational investigators may be falling short.

RECENT FINDINGS

Despite significant efforts to increase the number of individuals trained in both basic science and clinical medicine, the number of academic physician-scientists is on the decline. Increased demands from academic institutions coupled with severe difficulty in securing extramural funding are probably playing important roles in this concerning trend.

SUMMARY

Type 1 diabetes will continue to be a significant strain on individuals, their families and society until a cure is found. More than ever, there is a critical need to support appropriately trained translational investigators who can best facilitate bringing the promise of basic research to clinical reality.

Glucagon-like peptide-1 receptor signalling selectively regulates murine lymphocyte proliferation and maintenance of peripheral regulatory T cells

AIMS/HYPOTHESIS

Glucagon-like peptide-1 receptor (GLP-1R) agonists improve glucose control in animals and humans with type 1 diabetes. However, there is little information on the role of the GLP-1R in the immune system. We studied the role of the GLP-1R in immune function in wild-type (WT) and nonobese diabetic (NOD) and Glp1r-/- mice.

METHODS

Glp1r mRNA expression was examined in sorted immune subpopulations by RT-PCR. The effects of GLP-1R activation were assessed on cAMP production and proliferation, migration and survival of primary immune cells from WT and NOD mice. The ability of primary cells from Glp1r-/- mice to proliferate, migrate or survive apoptosis was determined. Immunophenotyping studies were performed to assess the frequency of immune subpopulations in Glp1r-/- mice.

RESULTS

Ex vivo activation of the GLP-1R resulted in a modest but significant elevation of cAMP in primary thymocytes and splenocytes from both WT and NOD mice. GLP-1R activation did not increase proliferation of primary thymocytes, splenocytes or peripheral lymph node cells. In contrast, Glp1r-/- thymocytes exhibited a hypoproliferative response, whilst peripheral Glp1r-/- lymphocytes were hyperproliferative in response to mitogenic stimulation. Activation or loss of GLP-1R signalling did not modify apoptosis or chemotaxis in primary lymphocytes. Male Glp1r-/- mice exhibited a significantly lower percentage of peripheral regulatory T cells, although no differences were observed in the numbers of CD4+ and CD8+ T cells and B cells in the spleen and lymph nodes of Glp1r-/- mice.

CONCLUSIONS/INTERPRETATION

These studies establish that GLP-1R signalling may regulate lymphocyte proliferation and maintenance of peripheral regulatory T cells.

Expression of a ricin toxin B subunit: insulin fusion protein in edible plant tissues

Onset of juvenile Type 1 diabetes (T1D) occurs when autoreactive lymphocytes progressively destroy the insulin-producing beta-cells in the pancreatic Islets of Langerhans. The increasing lack of insulin and subsequent onset of hyperglycemia results in increased damage to nerves, blood vessels, and tissues leading to the development of a host of severe disease symptoms resulting in premature morbidity and mortality. To enhance restoration of normoglycemia and immunological homeostasis generated by lymphocytes that mediate the suppression of autoimmunity, the non-toxic B chain of the plant AB enterotoxin ricin (RTB), a castor bean lectin binding a variety of epidermal cell receptors, was genetically linked to the coding region of the proinsulin gene (INS) and expressed as a fusion protein (INS-RTB) in transformed potato plants. This study is the first documented example of a plant enterotoxin B subunit linked to an autoantigen and expressed in transgenic plants for enhanced immunological suppression of T1D autoimmunity.

Six months of diazoxide treatment at bedtime in newly diagnosed subjects with type 1 diabetes does not influence parameters of {beta}-cell function and autoimmunity but improves glycemic control

OBJECTIVE Continuous beta-cell rest with diazoxide preserves residual endogenous insulin production in type 1 diabetes. However, side effects have hampered therapeutic usefulness. In a double-blind study, we tested whether lower, intermittent dosing of diazoxide had beneficial effects on insulin production, metabolic control, and autoimmunity markers in the absence of side effects. RESEARCH DESIGN AND METHODS Forty-one newly diagnosed type 1 diabetic patients were randomized to 6 months of treatment with placebo or 100 mg diazoxide at bedtime. A1C, C-peptide (fasting and glucagon stimulated), and FoxP3(+) regulatory T-cells (Tregs) were measured. Patients were followed for 6 months after intervention. RESULTS Of six dropouts, three were due to perceived side effects; one subject in the diazoxide group experienced rash, another dizziness, and one in the placebo group sleep disturbance. Adverse effects in others were absent. Diazoxide treatment reduced A1C from 8.6% at baseline to 6.0% at 6 months and 6.5% at 12 months. Corresponding A1C value in the placebo arm were 8.3, 7.3, and 7.5% (P < 0.05 for stronger reduction in the diazoxide group). Fasting and stimulated C-peptide decreased during 12 months similarly in both arms (mean -0.30 and -0.18 nmol/l in the diazoxide arm and -0.08 and -0.09 nmol/l in the placebo arm). The proportion of Tregs was similar in both arms and remained stable during intervention but was significantly lower compared with nondiabetic subjects. CONCLUSIONS Six months of low-dose diazoxide was without side effects and did not measurably affect insulin production but was associated with improved metabolic control.

Immune modulation by Schistosoma mansoni antigens in NOD mice: effects on both innate and adaptive immune systems

We have shown that Schistosoma mansoni egg soluble antigen (SEA) prevents diabetes in the nonobese diabetic (NOD) mouse inducing functional changes in antigen presenting cells (APCs) and expanding T helper (Th) 2 and regulatory T cell (Treg) responses. A Th2 response to S. mansoni infection or its antigens is key to both the establishment of tolerance and successfully reproduction in the host. More recently we demonstrated that SEA treatment upregulates bioactive TGFβ on T cells with consequent expansion of Foxp3⁺ Tregs, and these cells might be important in SEA-mediated diabetes prevention together with Th2 cells. In this study we profile further the phenotypic changes that SEA induces on APCs, with particular attention to cytokine expression and markers of macrophage alternative activation. Our studies suggest that TGFβ from T cells is important not just for Treg expansion but also for the successful Th2 response to SEA, and therefore, for diabetes prevention in the NOD mouse.

Immune tolerance induction by integrating innate and adaptive immune regulators

A diversity of immune tolerance mechanisms have evolved to protect normal tissues from immune damage. Immune regulatory cells are critical contributors to peripheral tolerance. These regulatory cells, exemplified by the CD4(+)Foxp3(+) regulatory T (Treg) cells and a recently identified population named myeloid-derived suppressor cells (MDSCs), regulate immune responses and limiting immune-mediated pathology. In a chronic inflammatory setting, such as allograft-directed immunity, there may be a dynamic "cross-talk" between the innate and adaptive immunomodulatory mechanisms for an integrated control of immune damage. CTLA4-B7-based interaction between the two branches may function as a molecular "bridge" to facilitate such "cross-talk." Understanding the interplays among Treg cells, innate suppressors, and pathogenic effector T (Teff) cells will be critical in the future to assist in the development of therapeutic strategies to enhance and synergize physiological immunosuppressive elements in the innate and adaptive immune system. Successful development of localized strategies of regulatory cell therapies could circumvent the requirement for very high number of cells and decrease the risks associated with systemic immunosuppression. To realize the potential of innate and adaptive immune regulators for the still elusive goal of immune tolerance induction, adoptive cell therapies may also need to be coupled with agents enhancing endogenous tolerance mechanisms.

Antigen-specific Tregs control T cell responses against a limited repertoire of tumor antigens in patients with colorectal carcinoma

Spontaneous antitumor T cell responses in cancer patients are strongly controlled by Tregs, and increased numbers of tumor-infiltrating Tregs correlate with reduced survival. However, the tumor antigens recognized by Tregs in cancer patients and the impact of these cells on tumor-specific T cell responses have not been systematically characterized. Here we used a broad panel of long synthetic peptides of defined tumor antigens and normal tissue antigens to exploit a newly developed method to identify and compare ex vivo the antigen specificities of Tregs with those of effector/memory T cells in peripheral blood of colorectal cancer patients and healthy subjects. Tregs in tumor patients were highly specific for a distinct set of only a few tumor antigens, suggesting that Tregs exert T cell suppression in an antigen-selective manner. Tumor-specific effector T cells were detectable in the majority of colorectal cancer patients but not in healthy individuals. We detected differences in the repertoires of antigens recognized by Tregs and effector/memory T cells in the majority of colorectal cancer patients. In addition, only effector/memory T cell responses against antigens recognized by Tregs strongly increased after Treg depletion. The selection of antigens according to preexisting T cell responses may improve the efficacy of future immunotherapies for cancer and autoimmune disease.

Do immunotherapy and beta cell replacement play a synergistic role in the treatment of type 1 diabetes?

Type 1 diabetes (T1D) is the result of the autoimmune response against pancreatic insulin-producing ss-cells. Its ultimate consequence is beta-cell insufficiency-mediated dysregulation of blood glucose control. In terms of T1D treatment, immunotherapy addresses the cause of T1D, mainly through re-setting the balance between autoimmunity and regulatory mechanisms. Regulatory T cells play an important role in this immune intervention. An alternative T1D treatment is beta-cell replacement, which can reverse the consequence of the disease by replacing destroyed beta-cells in the diabetic pancreas. The applicable insulin-producing cells can be directly obtained from islet transplantation or generated from other cell sources such as autologous adult stem cells, embryonic stem cells, and induced pluripotent stem cells. In this review, we summarize the recent research progress and analyze the possible advantages and disadvantages of these two therapeutic options especially focusing on the potential synergistic effect on T1D treatment. Exploring the optimal combination of immunotherapy and beta-cell replacement will pave the way to the most effective cure for this devastating disease.