Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0011849 (diabetes)
 277,896 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have utilized the NOD islet beta-cell line NIT-1 to monitor beta-cell specific autoantibodies and to investigate the modulation of IDDM in NOD mice by NIT-1 membrane associated antigens. The sera from diabetic but not from pre-diabetic or protected NOD mice strongly stained NIT-1 cells in FACS analysis. The cell surface antigens on NIT-1 cells were trypsin-sensitive. NIT-1 cells could not be stained by anti-mouse GAD67 antibody; however, we could demonstrate the presence of GAD65 and GAD67 mRNA by RT-PCR. Longitudinal analysis of anti-NIT-1 antibodies showed that these antibodies were present in the neonates but disappeared after weaning. Sonicated NIT-1 cell membrane preparations protected NOD mice from diabetes when injected intravenously in 5 week old mice. The protection was associated with reduced cytotoxic activity and elevated Th2-like responses as indicated by IgG1 antibodies against the NIT-1 cells. Subcutaneous injection of sonicated NIT-1 membranes or the injection of control red blood cell membranes failed to induce protection. We conclude that NIT-1 cell membranes do not express GAD but contain other antigens that are important in the development and prevention of IDDM. These antigens could be useful for the diagnosis of diabetes by monitoring autoantibody levels and for the modulation of IDDM by immunotherapy.
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PMID:Modulation and detection of IDDM by membrane associated antigens from the islet beta cell line NIT-1. 908 Feb 97

GAD65 is one of the major autoantigens associated with insulin-dependent diabetes mellitus (IDDM). The two peptides p17 and p18 of GAD65 that share sequence similarity with coxsackie virus (amino acid sequence identity: PEVKEK) appeared to be the major determinants of GAD65 recognized preferably by T cells from new-onset IDDM patients and their first degree relatives. In contrast, in our study unrelated control subjects frequently recognized the two GAD peptides (55%, 16/29), similar to first degree relatives (41%, 12/29) and IDDM patients post-onset (68%, 15/22). However, recent-onset IDDM patients, responded less frequently (25%, 4/16) compared with IDDM patients post-onset (p < 0.03) or unrelated control subjects (borderline significant) confirming previous observations in humans and NOD mice that T-cell reactivity to GADp17/p18 at diabetes onset is decreased. Moreover, this study demonstrated a positive correlation of T-cell proliferation to GAD p17 (amino acid 247-266) and p18 (amino acid 260-279) with simultaneous responses to both peptides in 13% of all subjects tested (n = 97) (p < 0.001). T-cell proliferation to GAD p17 was higher than to p18 in recent-onset diabetic patients, first degree relatives and unrelated control subjects (p < 0.02, p < 0.004, p < 0.002, respectively). However, in post-onset IDDM patients, the two peptides were recognized equally well. Our results show that T-cell reactivity to GAD65, peptides homologous with coxsackie protein is very frequently observed, but not primarily associated with IDDM. The temporary decline of T-cell proliferation is not associated with the beta-cell destruction process, but with clinical manifestation. The positive correlation of reactivity to the two peptides in the viral motif implicates that PEVKEK is an immunogenic epitope.
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PMID:T-cell reactivity to GAD65 peptide sequences shared with coxsackie virus protein in recent-onset IDDM, post-onset IDDM patients and control subjects. 908 73

Spontaneous insulitis with insulin-dependent diabetes mellitus (IDDM) in rodent models, the BB rat and NOD mouse, has clarified the pathogenesis of and guided decisions on interventional therapy for human IDDM. However, the occurrence in such models of a standard marker of human IDDM, autoantibodies to beta islet cell constituents, has been controversial. Hence we assessed diabetes-prone rodents for the frequencies of raised levels of auto-antibodies to glutamic acid decarboxylase GAD (anti-GAD), insulin and heat shock protein 65 (HSP-65) in relation to levels in non-diabetes-prone animals and levels in human diabetic sera. Assays were performed sequentially at various ages of life. The immunoassays used for anti-GAD and anti-insulin were those validated for sensitivity and specificity for detection of the corresponding autoantibodies in human IDDM sera at international workshops. Positive controls included human IDDM sera with reactivity with GAD or insulin and, for mouse anti-GAD, the highly reactive monoclonal antibody, GAD-6. The results were that levels of autoantibodies in diabetes-prone BB rats or NOD mice to the "IDDM-relevant' autoantigens in our panel did not exceed levels in control rats or mice, and were much lower than levels in humans with IDDM. We conclude that the BB rat and NOD mouse represent a model, but not a facsimile, of human IDDM and that therapeutic successes in such models should be interpreted with caution in relation to interventional therapy for human IDDM.
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PMID:Lack of autoimmune serological reactions in rodent models of insulin dependent diabetes mellitus. 911 72

A peptide of the human 60-kDa heat-shock protein (hsp60), designated p277, was found to be useful as a therapeutic agent to arrest the autoimmune process responsible for diabetes in nonobese diabetic (NOD) mice. The effectiveness of peptide treatment was associated with the induction of peptide-specific antibodies of the IgG1 but not of the IgG2a isotype, suggesting the possibility that a Th2-type response may have been induced. We now report that the effectiveness of p277 treatment is associated with the transient activation of anti-p277 splenic T-cells that produce the Th2 cytokines interleukin-4 (IL-4) and IL-10. The Th2 response to p277 was associated with reduced Th1-type autoimmunity to hsp60 and to two other target antigens associated with diabetes: GAD and insulin. The Th2 shift appeared to be relatively specific; spontaneous T-cell reactivity to a bacterial antigen peptide remained in the Th1 mode in the p277-treated mice. Moreover, treatment with the bacterial peptide did not induce a change in cytokine profile, and it did not affect progression of the disease. Thus, effective peptide treatment of the diabetogenic process associated with the induction of antibodies may be explained by selective and transient activation of Th2 autoimmune reactivity.
Diabetes 1997 May
PMID:Hsp60 peptide therapy of NOD mouse diabetes induces a Th2 cytokine burst and downregulates autoimmunity to various beta-cell antigens. 913 41

The purpose of this study was to test for the presence (alone or in combination) of 4 autoantibodies directed against beta cells in the sera of children at diagnosis of the overt clinical phase of insulin-dependent diabetes mellitus. Children recorded in 1989 in the population-based French Registry of Incidence of Insulin-Dependent Diabetes Mellitus were included in the present study. One hundred and thirty-eight sera were tested for islet cell antibodies (ICA), insulin autoantibodies (IAA) and antibodies against glutamic acid decarboxylase (GAD-Ab) and tyrosine phosphatase (IA2-Ab). IAA showed significantly lower sensitivity (36%) than the other antibodies (ICA: 84%; GAD-Ab: 74%; IA2-Ab: 81%). In the age-range of the registry, the prevalence rates for the 4 antibodies were not significantly affected by age. IAA and GAD-Ab were significantly associated with ICA, whereas GAD-Ab and/or IA2-Ab was(were) associated with 93% sensitivity at diagnosis. Sensitivity was 100% with the 4 antibodies combined. No significant association was found between the antibodies and HLA DR phenotypes. This study shows that a combination of the 4 major autoantibodies allows all children with insulin-dependent diabetes to be identified.
Diabetes Metab 1997 Apr
PMID:Sensitivity at diagnosis of combined beta-cell autoantibodies in insulin-dependent diabetic children. French Registry of IDDM in Children Study Group. 913 5

The autoantigen glutamic acid decarboxylase 65 (GAD 65) is believed to be an important target antigen in insulin-dependent diabetes mellitus (IDDM), since an age-related spontaneous breakdown in tolerance is observed, and cell-mediated and autoantibody immune responses have been reported in humans and NOD mice. We sought to identify immunogenic epitopes of GAD 65 which are presented to T cells by the type I diabetes susceptibility allele (Ag7), using overlapping 15-mer synthetic peptides spanning the entire sequence of this protein. Four epitopes (p206 - 220, p221 - 235, p286 - 300, p571 - 585) were identified by screening a panel of T-cell hybridomas generated from GAD 65-immunized NOD mice. These immunogenic epitopes are unrelated to the previously described T-cell epitopes of GAD 65 reported in NOD mice. Of the GAD 65 amino acid sequence, 206 - 220 and 221 - 235 are the two most dominant T-cell epitopes identified in this study. Sixty-three percent and 25% of GAD 65-responding T cell hybridomas react to p206 - 220 and p221 - 235, respectively. The remaining two peptides (p286 - 300, p571 - 585) are less dominant T-cell responses. The identification of the whole spectrum of GAD 65 Ag7 epitopes should further the investigation of the role of this autoantigen in the pathogenesis of IDDM.
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PMID:Identification of immunogenic epitopes of GAD 65 presented by Ag7 in non-obese diabetic mice. 914 85

Recently, 65-kDa glutamic acid decarboxylase (GAD 65) antibodies (GADA) have been introduced as autoimmune markers in blood to confirm the diagnosis of insulin-dependent diabetes mellitus (IDDM). In this study, to evaluate two new assays that use 125I-labeled GAD 65, we assayed samples from 100 children with recent onset of diabetes and 100 control children, the results were compared with those of a [35S]GADA assay and with results for islet cell antibodies (ICA), the conventional autoimmune marker. Receiver operating characteristic (ROC) curve analysis showed one of the new assays (from RSR) to be more sensitive (P = 0.01) than the comparison ([35S]GADA) assay, whereas the second new assay (from Elias) was less sensitive (P < 0.001). The GADA frequency at 97.5% specificity was greatest in the comparison assay: 63 of 100 vs 41 of 100 (P < 0.01) and 53 of 100 (P = 0.16) in the RSR and Elias assays, respectively. Almost all GADA-positive patients had ICA, but one-third of the ICA-positive patients was GADA-negative. Accordingly, adding GADA analysis results to ICA testing increased the frequency of detection of autoimmune markers only slightly (from 81% to 85%). In conclusion, at 97.5% specificity the [35S]GADA assay seemed to be more efficient than the 125I assays, although the difference was significant only for the Elias 125I assay. Antigen-specific antibodies other than GADA may explain the difference in GADA and ICA frequencies.
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PMID:Measurement of antibodies against glutamic acid decarboxylase 65 (GADA): two new 125I assays compared with [35S]GAD 65-ligand binding assay. 916 19

To elucidate whether autoantibodies can be used to predict the intensity of autoimmune beta-cell destruction, we determined both C-peptide and autoantibodies (islet cell antibodies (ICA), insulin autoantibodies (IAA), islet cell surface antibodies (ICSA) and antibodies to glutamic acid decarboxylase (GADA)). In 89 diabetic children and adolescents at diagnosis at the age of 1.2-16.6 years (mean +/- S.D., 9.0 +/- 4.5). Only 12/89 (14%) had no autoantibodies at diagnosis, while 2 patients (2%) had all 4 autoantibodies. There was a positive correlation between GADA and ICA (P < 0.01). At diagnosis 70% of the patients had GADA, most common in patients above the age of 8 years at diagnosis (P < 0.001), and with higher GAD-index in girls (P < 0.05). ICA was detected in 63%, most common in the older age groups (P = 0.04). ICSA seen in 22% of the patients as well as IAA (detected in 32%) were most common < 8 years of age (P = 0.06, P = 0.08, respectively). Children with autoantibodies had similar C-peptide levels through the follow up period as children of the same sex and age without antibodies, except for patients with ICSA alone or in combination with other autoantibodies who tended to have higher C-peptide levels. We conclude that not even combinations of autoantibodies can be used to predict beta-cell destruction in IDDM patients.
Diabetes Res Clin Pract 1997 Mar
PMID:Autoantibodies in relation to residual insulin secretion in children with IDDM. 917 62

Autoantibodies to 65 kD glutamic acid decarboxylase (GADAA) and ICA512 (ICA512AA) were measured by radioimmunoassays using as antigens in vitro transcribed and translated [35S]-methionine-labeled human GAD65 and ICA512 (IA-2). The prevalence of GADAA and ICA512AA in sera from 87 patients with IDDM was 39 and 23%, respectively. The frequency and titer of ICA512AA declined sharply within 5 years after the onset of IDDM. Among patients tested within 4 years after diagnosis, the prevalence of ICA512AA was significantly higher in acute onset IDDM than in slowly progressive IDDM (37 versus 6%, P < 0.025) irrespective of age, while there was no difference in GADAA frequency between acute onset and slowly progressive subtypes (51 versus 63%). A total of two patients out of 121 patients with NIDDM were positive for GADAA, and two other NIDDM patients, who were suffering from sarcoidosis, were positive for ICA512AA. Neither of the antibodies were positive in sera from four atypical NIDDM patients, aged < 20 years, who showed ketosis at onset and required insulin followed by excellent metabolic control with diet restriction alone. These observations suggest that ICA512AA are associated with rapid progression of beta cell damage in IDDM. ICA512 radioassay, in combination with GAD assay may provide a useful diagnostic marker for IDDM especially in youth.
Diabetes Res Clin Pract 1997 Mar
PMID:Combined measurements of GAD65 and ICA512 antibodies in acute onset and slowly progressive IDDM. 917 63

Autoantibodies to the islet-cell 65-kDa variant of glutamate decarboxylase (GAD65) are found in most insulin-dependent diabetes mellitus (IDDM) patients many years before the appearance of clinical symptoms of the disease. As IDDM-preventive therapies may be available in the future, an international effort is taking place to develop widely applicable anti-GAD immunochemical tests. These tests would help to detect individuals at risk before the full installation of the disease and to enroll them in prevention programs. Autoantibodies to GAD65 are mostly directed to conformational epitopes, and the enzyme is a complex molecule with a prosthetic group and 15 cysteine residues. Thus, the conformational integrity of GAD65 is essential for an appropriate anti-GAD assay. Isolation of large amounts of GAD65 from pancreas or other tissues is impractical, and no successful production of properly folded GAD65 has been reported in bacteria. Native recombinant GAD65 for immunochemical tests is usually obtained from eukaryotic expression systems. Since the large-scale production of a recombinant protein in an eukaryotic system is expensive and technically difficult, we investigated the expression of GAD65 in Escherichia coli as an alternative. A number of DNA constructs intended to export the enzyme to the periplasmic space or to improve its cytoplasmic solubility were designed and tested. Our results provide a solution to the two main problems associated with the expression of GAD65 in E. coli: misfolding, leading to the formation of inclusion bodies; and the presence of alternative initiation sites for translation that causes the preferential production of truncated variants of GAD65. We describe here the production of properly folded, fully active, and immunochemically competent GAD65 as an N-terminal fusion protein with thioredoxin. An account of the reactivity of the produced protein with sera of six IDDM patients is also presented.
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PMID:Expression of properly folded human glutamate decarboxylase 65 as a fusion protein in Escherichia coli. 920 24


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