Regulatory T-cells in type 1 diabetes

Collective effects of common single nucleotide polymorphisms and genetic risk prediction in type 1 diabetes

Type 1 diabetes (T1D) is a common autoimmune disease and may be related to multiple genetic and environmental risk factors. Previous genetic studies have focused on looking for individual polymorphic risk variants. Here, we studied the overall levels of genetic diversity in T1D patients by making use of a previously published study including 1865 cases and 2828 reference samples with genotyping data for 500 K common single nucleotide polymorphisms (SNPs). We determined the minor allele (MA) status of each SNP in the reference samples and calculated the total number of MAs or minor allele contents (MAC) of each individual. We found the average MAC of cases to be greater than that of the reference samples. By focusing on MAs with strong linkage to cases, we further identified a set of 112 SNPs that could predict 19.19% of cases. These results suggest that overall genetic variation over a threshold level may be a risk factor in T1D and provide a new genetic method for predicting the disorder.

Immune regulatory properties of allogeneic adipose-derived mesenchymal stem cells in the treatment of experimental autoimmune diabetes

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

Poor in vitro induction of FOXP3 and ICOS in type 1 cytokine environment activated T-cells from children with type 1 diabetes

BACKGROUND

Type 1 diabetes (T1D) is characterised by loss of tolerance to beta-cell antigens, and the insulin-producing beta-cells in the pancreatic islets are destroyed by the host's own immune system. Immunological risk factors associated with T1D are related to the defects in the polarization of T-cells and in the function of regulatory T (Treg)-cells. We set out to study whether an impaired induction of regulatory mechanisms during the generation of T-cell responses upon stimulation is associated with T1D.

METHODS

Naive T-cells were isolated from 18 children with recent T1D (0-14days from diagnosis; mean age 9.3 years), 11 children who had had T1D for at least 1 year (mean age 10.6) and 14 non-diabetic children (mean age 8.1). CD45RA+ T-cells were stimulated with PHA for 72 h in type 1 cytokine [interleukin (IL)-12 and anti-IL-4] or type 2 cytokine (IL-4 and anti-IL-12) environment. T-cell polarization and regulation related markers were analysed by quantitative reverse transcription polymerase chain reaction (QRT-PCR) (Th1 promoting T-bet, Th2 promoting GATA-3 and regulation related FOXP3, ICOS and NFATc2).

RESULTS

Children with recently diagnosed T1D showed decreased induction of FOXP3, ICOS and NFATc2 in T-cells activated in type 1 cytokine milieu (p = 0.007, p = 0.001, and p = 0.02), whereas no differences between the diabetic and healthy children were seen in the up-regulation of activation markers, T-bet and GATA-3.

CONCLUSIONS

The poor induction of factors that mediate down-modulation of T-cell responses upon stimulation in type 1 cytokine environment may contribute to the development of autoreactive type 1 responses in T1D.

Heparanase prevents the development of type 1 diabetes in non-obese diabetic mice by regulating T-cell activation and cytokines production

BACKGROUND

Heparanase is an endo-beta-D-glucuronidase that cleaves heparan sulfate saccharide chains. The enzyme promotes cell adhesion, migration and invasion, and was shown to play a significant role in cancer metastasis and angiogenesis.

METHODS

The present study focuses on the involvement of heparanase in autoimmunity, applying the murine non-obese diabetic (NOD) model, a T-cell-dependent disease often used to investigate the pathophysiology of type 1 diabetes.

RESULTS

It was found that intra-peritoneal administration of heparanase ameliorated the clinical signs of the disease. In vitro studies revealed that heparanase has an inhibitory effect on the activation of T-cells through modulation of their repertoire of cytokines indicated by a marked increase in the levels of IL-4 and IL-10, and a parallel decrease in IL-12, tumour necrosis factor-alpha (TNF-alpha) and interferon-gamma (IFN-gamma).

CONCLUSIONS

We suggest that heparanase induces a shift from a Th1- to Th2-phenotype, resulting in inhibition of diabetes in NOD mice and possibly other autoimmune disorders.

Pre-incubation with interleukin-4 mediates a direct protective effect against the loss of pancreatic beta-cell viability induced by proinflammatory cytokines

Loss of pancreatic beta-cells in type I diabetes is associated with an increase in T helper 1 (Th1) proinflammatory cytokines in the islet milieu, with a concomitant reduction in Th2 anti-inflammatory cytokines. In animal models, manoeuvres designed to polarize Th1 responses towards Th2, particularly involving interleukin (IL)-4, have been shown to protect against insulitis and diabetes. The aim of this study was to determine whether IL-4 can exert a direct effect on beta-cell viability. The rat pancreatic beta-cell line, BRIN-BD11, was used. IL-4R mRNA expression was assayed by reverse transcription-polymerase chain reaction and DNA sequencing and protein expression measured using anti-IL-4R antibodies and confocal microscopy. Cells were pretreated in vitro with IL-4, incubated with IL-1beta and interferon (IFN)-gamma and DNA fragmentation and nitrite production analysed by flow cytometry and Griess assay, respectively. Expression of type I (IL-4R alpha and common gamma-chain) and type II (IL-4R alpha, IL-13R alpha-1) IL-4R mRNA transcripts, together with cell surface expression of IL-4R, was demonstrated. Pre-incubation with IL-4 reduced significantly cell death induced by IL-1beta alone or by a combination of IL-1beta and IFN-gamma, although this was not accompanied by a reduced production of nitrite. The protective effect of IL-4 was not seen when all three cytokines were added simultaneously. These results demonstrate, for the first time, expression of IL-4 receptor components on rat pancreatic beta-cells and reveal a direct protective effect on the loss of viability mediated by proinflammatory cytokines when beta-cells are pre-incubated with IL-4.

Review article: immune suppression and colorectal cancer

BACKGROUND

Advances in immunology and molecular biology have shown that colorectal cancer is potentially immunogenic and that host immune responses influence survival. However, immune surveillance and activation is frequently ineffective in preventing and/or controlling tumour growth.

AIM

To discuss potential ways in which colorectal cancer induces immune suppression, its effect upon prognosis and avenues for therapeutic development.

METHOD

A literature review was undertaken for evidence of colorectal cancer-induced immune suppression using PubMed and Medline searches. Further studies were identified from the reference lists of identified papers.

RESULTS

Immune suppression occurs at a molecular and cellular level and can result in a shift from cellular to humoral immunity. Several mechanisms for immune suppression have been described affecting innate and adaptive immunity with suppression linked to poorer clinical outcome.

CONCLUSIONS

Colorectal cancer causes direct inhibition of the host's immune response with a detrimental effect upon prognosis. Immunotherapy offers a therapeutic strategy to counteract these effects with promising results seen particularly in precancerous conditions and early tumours. This review strongly suggests that immunotherapy should be incorporated into adjuvant therapeutic trials for stage 2 tumours and be considered as adjuvant treatment in conjunction with standard chemotherapy regimes for advanced disease.

Cytotoxic T lymphocytes and autoimmunity

PURPOSE OF REVIEW

The possibility of the recognition by cytotoxic T lymphocytes of tissue autoantigens has been largely ignored in explaining organ-specific autoimmune diseases. Recent advances in the understanding of human leukocyte antigen class I-binding peptides motifs have led to the detection and the characterization of those autoreactive CD8(+) cytotoxic T lymphocytes involved in organ-specific autoimmune diseases. The purpose of this review is to discuss recent studies that shed light on the implication of cytotoxic T lymphocytes in several autoimmune disorders as well as the mechanisms underlying their stimulation.

RECENT FINDINGS

Significant progress has been made in the characterization of autoantigens targeted by cytotoxic T lymphocytes in several class I-restricted autoimmune diseases, including Behçet's disease and ankylosing spondylitis, and their implication in systemic autoimmune disease such as systemic lupus erythematosus. Moreover, the signals involved in the activation of autoreactive cytotoxic T lymphocytes have been better characterized, particularly the molecular requirements of the antigen presentation at the surface of the dendritic cell system, mainly because of a better understanding of the Toll-like receptor-induced signals or the discovery of a defect in regulatory T cells.

SUMMARY

New findings in the pathophysiology of cytotoxic T lymphocytes in autoimmunity and especially a better comprehension of their activation may give a new impetus for the development of targeted immunologic therapies in various autoimmune disorders.

The autoimmune contrivance: genetics in the mouse model

Autoimmunity and inheritance of complex characters behold an explosive interest in biology over the last 15 years. Research in the genetics of autoimmunity has been impelled by the isolation of genetic markers allowing tracing of heredity. The annotation and sequencing of the human and mouse genomes provide with the potential for further advancements, through the development of new technologies. This review aims to summarize advances made in the autoimmunity field, centered in type 1 diabetes in the NOD mouse model. It also aims to demonstrate that animal models, albeit some phenotypic and genetic dissimilarities with the human diseases, still remain the best way to move towards an understanding of the molecular mechanisms involved in autoimmunity. Assessing the current state of research in this field together with the increasing potential of novel biotechnology advancements, new insights to disease pathogenesis and discovery of molecular targets for intervention strategies are anticipated in the coming years.