Association between LTA, TNF and AGER Polymorphisms and Late Diabetic Complications

BACKGROUND: Several candidate genes on the short arm of chromosome 6 including the HLA locus, TNF, LTA and AGER could be associated with late diabetic complications. The aim of our study was therefore to explore whether polymorphisms (TNF -308 G-->A, LTA T60N C-->A and AGER -374 T-->A) in these genes alone or together (as haplotypes) increased the risk for diabetic complications. METHODOLOGY/PRINCIPAL FINDINGS: The studied polymorphisms were genotyped in 742 type 1 and 2957 type 2 diabetic patients as well as in 206 non-diabetic control subjects. The Haploview program was used to analyze putative linkage disequilibrium between studied polymorphisms. The TNF, LTA and AGER polymorphisms were associated with the HLA-DQB1 risk genotypes. The AGER -374 A allele was more common in type 1 diabetic patients with than without diabetic nephropathy (31.2 vs. 28.4%, p = 0.007). In a logistic regression analysis, the LTA but not the AGER polymorphism was associated with diabetic nephropathy (OR 2.55[1.11-5.86], p = 0.03). The AGER -374 A allele was associated with increased risk of sight threatening retinopathy in type 2 diabetic patients (1.65[1.11-2.45], p = 0.01) and also with increased risk for macrovascular disease in type 1 diabetic patients (OR 2.05[1.19-3.54], p = 0.01), but with decreased risk for macrovascular disease in type 2 diabetic patients (OR 0.66[0.49-0.90], p = 0.009). The TNF A allele was associated with increased risk for macrovascular complications in type 2 (OR 1.53 [1.04-2.25], p = 0.03, but not in type 1 diabetic patients. CONCLUSIONS/SIGNIFICANCE: The association between diabetic complications and LTA, TNF and AGER polymorphisms is complex, with partly different alleles conferring susceptibility in type 1 and type 2 diabetic patients. We can not exclude the possibility that the genes are part of a large haplotype block that also includes HLA-DQB1 risk genotypes

Differential Glucose-Regulation of MicroRNAs in Pancreatic Islets of Non-Obese Type 2 Diabetes Model Goto-Kakizaki Rat

The Goto-Kakizaki (GK) rat is a well-studied non-obese spontaneous type 2 diabetes (T2D) animal model characterized by impaired glucose-stimulated insulin secretion (GSIS) in the pancreatic beta cells. MicroRNAs (miRNAs) are short regulatory RNAs involved in many fundamental biological processes. We aim to identify miRNAs that are differentially-expressed in the pancreatic islets of the GK rats and investigate both their short- and long term glucose-dependence during glucose-stimulatory conditions

Maternal Autoimmune Thyroid Disease and the Fetal Immune System.

OBJECTIVE: Several studies indicate that in utero exposure to maternal autoimmune diseases and transplacental passage of autoantibodies affect the risk of autoimmunity in the offspring, e. g., maternally derived GAD65 autoantibody correlates with decreased risk of type 1 diabetes, whereas thyroid peroxidase autoantibody (TPOAb) positivity at birth is associated with increased incidence of autoimmune thyroid disease later in life. The aim of this study was to identify immunological changes in children born to mothers with thyroid autoimmunity that may be related to in utero exposure to autoantibodies. DESIGN AND METHOD: Open label prospective analysis of cord blood lymphocytes and serum cytokines by Flow Cytometry in children born to mothers with autoimmune thyroiditis (AIT) (n=31) and to healthy mothers (n=76) and titers of thyroid autoantibodies were determined in cord blood and in maternal peripheral blood at delivery. RESULTS: We found an increase (almost 30%) in the frequency of cord blood natural killer (NK) cells (p=0.0016) and a minor increase in the subset of T cells expressing NK markers (p=0.028), in children born to AIT mothers. There were no detectable differences in the phenotype or frequency of cord blood memory/activated T cells, including CD4 (+)CD25 (+) T cells, between the 2 groups. The levels of pro-inflammatory cytokines TNF-α, IL-10, IL-12p70, IFN-γ and IL-1β were significantly decreased in offspring of AIT mothers as compared to healthy controls. CONCLUSIONS: Maternal thyroid autoimmunity and transplacental passage of autoantibodies against thyroid antigens may affect the generation or expansion of cells with NK activity and the secretion of inflammatory cytokines

GAD65 autoantibody epitopes in adult patients with latent autoimmune diabetes following GAD65 vaccination

Aims Subcutaneous injection of recombinant human GAD65 (rhGAD65) in patients with latent autoimmune diabetes in adults (LADA) correlates with an increase in C-peptide levels. In this study we analysed the effect of rhGAD65 administration on the GAD65-specific autoimmune response. Methods Longitudinal serum samples obtained from LADA patients (n = 47) who received 4, 20, 100 or 500 mu g alum-formulated rhGAD65 or placebo by subcutaneous injection twice (4 weeks apart) were analysed for their epitope recognition using GAD65-specific recombinant Fab and GAD65/67 fusion proteins. Results Overall, minor changes in the epitope pattern were observed using either approach. Only in the 500-mu g dosage group was an increase in GAD65Ab level associated with a significant increase in the binding to a conformational epitope located at the middle part of GAD65. Conclusions Our data suggest that the apparent beneficial effects of 20 mu g alum-formulated recombinant human GAD65 is not explained by changes in the GAD65Ab epitope pattern

Taming killer cells may halt diabetes progression

Preclinical studies in mice suggest that the natural killer cell receptor NKp46 may be a new molecular target for delaying the progression of type 1 diabetes by interfering with unexpected natural killer cell-mediated recognition of pancreatic beta cells

Changes in GAD65Ab-Specific Antiidiotypic Antibody Levels Correlate with Changes in C-Peptide Levels and Progression to Islet Cell Autoimmunity.

Context: The previously reported absence of 65-kDa glutamate decarboxylase antibody (GAD65Ab)-specific antiidiotypic antibodies (anti-Id) in type 1 diabetes (T1D) patients at clinical onset could be due to an inability to mount an antibody response to GAD65Ab or a longitudinal decline in anti-Id levels. Objective and Design: We investigated anti-Id levels in longitudinal samples obtained from T1D patients (n = 41) (clinical diagnosis - 12 months), and latent autoimmune diabetes in adults (LADA) patients (n = 32) who received alum-formulated human recombinant GAD65 (baseline - 12 months). We also determined anti-Id levels in a small cohort of Type 2 diabetes patients during their development of autoimmune T cell responses. Results: At clinical onset T1D patients presented no or low anti-Id levels. However, 22/41 T1D patients showed >/=50% increase in GAD65Ab-specific anti-Id levels during follow-up; peaking at 3 (n = 1), 6 (n = 10), 9 (n = 10), or 12 (n = 1) months. Increasing anti-Id levels marked patients who experienced a temporary increase in C-peptide levels. Anti-Id levels correlated significantly with glycated hemoglobin and C-peptide levels at 6 and 9 months (P values ranged from <0.001 to <0.05). In LADA patients receiving placebo, anti-Id levels declined in seven of nine patients, whereas four of five patients receiving 20 mug alum-formulated human recombinant GAD65 showed increasing anti-Id levels. Changes in anti-Id and C-peptide levels closely correlated (P < 0.0001). The significant decline in anti-Id levels (P = 0.03) in T2D patients developing T cell autoimmune responses supports our hypothesis that declining anti-Id levels are associated with developing islet autoimmunity. Conclusions: The close association between GAD65Ab-specific anti-Id levels and beta-cell function may provide a novel marker for the progression of autoimmune diabetes

Beta-cell specific deletion of dicer1 leads to defective insulin secretion and diabetes mellitus

Mature microRNAs (miRNAs), derived through cleavage of pre-miRNAs by the Dicer1 enzyme, regulate protein expression in many cell-types including cells in the pancreatic islets of Langerhans. To investigate the importance of miRNAs in mouse insulin secreting beta-cells, we have generated mice with a beta-cells specific disruption of the Dicer1 gene using the Cre-lox system controlled by the rat insulin promoter (RIP). In contrast to their normoglycaemic control littermates (RIP-Cre(+/-) Dicer1(Delta/wt)), RIP-Cre(+/-) Dicer1(flox/flox) mice (RIP-Cre Dicer1(Delta/Delta)) developed progressive hyperglycaemia and full-blown diabetes mellitus in adulthood that recapitulated the natural history of the spontaneous disease in mice. Reduced insulin gene expression and concomitant reduced insulin secretion preceded the hyperglycaemic state and diabetes development. Immunohistochemical, flow cytometric and ultrastructural analyses revealed altered islet morphology, marked decreased beta-cell mass, reduced numbers of granules within the beta-cells and reduced granule docking in adult RIP-Cre Dicer1(Delta/Delta) mice. beta-cell specific Dicer1 deletion did not appear to disrupt fetal and neonatal beta-cell development as 2-week old RIP-Cre Dicer1(Delta/Delta) mice showed ultrastructurally normal beta-cells and intact insulin secretion. In conclusion, we have demonstrated that a beta-cell specific disruption of the miRNAs network, although allowing for apparently normal beta-cell development, leads to progressive impairment of insulin secretion, glucose homeostasis and diabetes development