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

Antibodies to glutamic acid decarboxylase (GAD), a pancreatic islet beta-cell antigen, are present in > 80% of newly diagnosed insulin-dependent diabetes mellitus (IDDM), and are found in nonobese diabetic (NOD) mice, a murine model of spontaneous IDDM. To determine whether GAD is a target antigen in the kidney damage of NOD mice, we studied GAD mRNAs (GAD65 and GAD67) by RT-PCR in mesangial cells, isolated glomeruli, and kidney cortex and medulla in NOD and SJL/C57BL mice. GAD mRNAs were detected in the cortex of both diabetic and nondiabetic NOD and SJL/C57BL mice and GAD antigen was present in proximal and distal tubules by immunofluorescence microscopy. Neither GAD antigen nor mRNA were present in mesangial cells or glomeruli of diabetic or nondiabetic mice. Thus, the expression of GAD in renal tubules raises the possibility that GAD antigens may play a role in diabetic tubulointerstitial disease, whereas the absence of these antigens in glomeruli suggests that GAD-triggered autoimmunity is not directly involved in the glomerular lesions.
 ...
PMID:Localization of glutamic acid decarboxylase in the kidneys of nonobese diabetic mice. 873 Apr 38

IDDM (type I diabetes) is generally believed to result from T-cell-mediated autoimmune destruction of the insulin-producing beta-cells in the pancreatic islets of Langerhans. In the last few years, considerable progress has been made with regard to the identification and characterization of candidate autoantigens recognized by autoantibodies; several of these candidate autoantigens are recognized by T-cells, including insulin, GAD65 and GAD67, heat-shock protein 65 (hsp65), and islet-cell antigen 69 (ICA69). In addition to these, a number of unidentified beta-cell antigens, including insulin-secretory granule membrane proteins and a 38-kDa protein, have been shown to stimulate T-cells of IDDM patients. However, T-cell autoreactivity to islet antigens is not specific for IDDM, and the T-cell target antigens are not specific for beta-cells. Moreover, the autoantigens involved in the initiation of the insulitis must be defined, and the mechanism of the T-cell-dependent beta-cell destruction remains to be unraveled. This review focuses on T-cell autoreactivity in IDDM in humans and the implications of the present knowledge for immunointervention and monitoring of immunotherapeutic trials.
Diabetes 1996 Sep
PMID:T-cell responses to autoantigens in IDDM. The search for the Holy Grail. 877 14

Autoantibodies to glutamic acid decarboxylase (GAD) are useful diagnostic and predictive markers for Type 1 (insulin-dependent) diabetes mellitus. In the present study we describe a development of simple, reproducible, and quantitative radioimmunoassays for detecting GAD65 and GAD67 antibodies, and compare sensitivity and specificity of these assays with native GADAb radioimmunoassay. We used in vitro transcribed and translated recombinant human islet GAD65 and GAD67 as antigens, and anti-human IgG was used to separate free from antibody-bound ligand. By using these assays, GAD65Ab and GAD67Ab were detected in 65% and 25% of recent-onset Japanese patients with Type 1 diabetes, respectively, but none of 71 healthy control subjects tested were postive for GAD65Ab and GAD67Ab. Moreover, none of 48 patients with other autoimmune disease had GAD65Ab or GAD67Ab. There was a 100% correlation between the sensitivity and specificity of GAD65Ab assay and native GADAb assay. GAD65Ab and GAD67Ab were concordant in 28% of Type 1 diabetic sera and the levels of GAD65Ab in doubly positive patients were significantly higher than those in only GAD65Ab positive patients (P < 0.01). GAD65Ab are specific markers for Type 1 diabetes, and the radioimmunoassay using in vitro translated GAD and anti-human IgG, which is sensitive, convenient and low cost for detecting GAD antibodies, will facilitate large population screening of Type 1 diabetes.
Diabetes Res Clin Pract 1996 Apr
PMID:Detection of recombinant GAD65 and GAD67 antibodies using a simple radioimmunoassay. 880 83

Glutamic acid decarboxylase (GAD) has been shown to exist as two isoforms with molecular weights of 65 kD (GAD65) and 67 kD (GAD67) in the central nervous system as well as in several non-neuronal tissues, including the pancreatic islets. Recently, this enzyme has been proposed as a key beta-cell autoantigen in insulin-dependent diabetes mellitus (IDDM). In the present study, we used double label light and confocal microscopy to examine the expression of the two GAD isoforms in islet cells of fetal, neonatal and adult porcine pancreas. We also aimed to identify the islet cell-type(s) which co-express GAD. In the adult pig, GAD65 was localized exclusively in most of the beta cells, whereas GAD67, in addition to being present in a majority of the beta cells, was also seen in a proportion of glucagon and somatostatin labelled cells. In the 90-day fetus and the 7-day neonate, while GAD65 was also observed in a majority of beta cells, a proportion of glucagon cells also co-expressed this isoform. The cellular expression of GAD67 in the fetal and neonatal stages was similar to that in the adult. Detailed confocal analysis of GAD65 immunoreactive cells showed a granular cytoplasmic staining, with labelled granules often concentrated in specific perinuclear regions, possibly the Golgi apparatus. In contrast, GAD67 positive cells showed more diffuse cytoplasmic staining. The predominant expression of both the isoforms in porcine beta cells suggests that islet cells from this species may act as a suitable cellular model for study of GAD autoreactivity during the early stages of IDDM.
 ...
PMID:Glutamic acid decarboxylase 65 and 67 isoforms in fetal, neonatal and adult porcine islets: predominant beta cell co-localization by light and confocal microscopy. 884 50

To study the immune response to glutamic acid decarboxylase (GAD) in insulin-dependent diabetes mellitus, monoclonal GAD antibodies after fusion of splenocytes from a nondiabetes-susceptible BALB/c mouse immunized with human recombinant GAD65 were generated. Of the 44 monoclonals, 35 are specific for the GAD65 isoform, whereas 9 also react with GAD67. Some 37 monoclonals, including all GAD65/67 reactive antibodies, react with GAD by Western blot analysis. The remaining 7 GAD65 monoclonals bind GAD only in an immunoprecipitation assay, which implies that they target epitopes dependent on the conformation of the GAD molecule. The 125I-GAD binding of the GAD65 monoclonals reactive on Western blotting was significantly diminished by all 3 sera from Stiff-man syndrome patients but only by 3/30 (10%) sera from type 1 diabetic patients. In contrast, the 7 monoclonal antibodies reactive with a conformation-dependent GAD epitope were competitive with 83% of GAD-autoantibody-positive sera from these diabetic patients. Using chimeric GAD65/67 proteins, the epitope region targeted by these monoclonals was mapped to the middle of GAD65 (amino acids 221-442). This central conformation-dependent GAD region was also targeted by sera from patients with type 1 diabetes. In conclusion, our data show that even after common immunization of a nondiabetes-susceptible mouse strain, monoclonal were obtained which preferentially react with the GAD65 linear amino-terminus (amino acids 4-17) and a conformation-dependent region located in the middle of GAD targeted by autoantibodies, indicating that this GAD region is not restricted to the autoimmune response associated with the Stiff-man syndrome and the beta-cell destruction in type 1 diabetes mellitus.
 ...
PMID:Murine monoclonal glutamic acid decarboxylase (GAD)65 antibodies recognize autoimmune-associated GAD epitope regions targeted in patients with type 1 diabetes mellitus and stiff-man syndrome. 890 30

Reliable genetic and immunological markers are important in the prediction of insulin-dependent diabetes mellitus (IDDM). Since glutamic acid decarboxylase (GAD) is a candidate primary autoantigen, we examined the possible linkage between IDDM and the genes encoding GAD65 (GAD2, 10p11-12) and GAD67 (GAD1, 2q31) in 58 Danish IDDM affected sib pairs. The allelic inheritance of 10 polymorphic dinucleotide repeat sequences spanning the chromosomal regions of the two GAD genes, were examined by affected sib pair analysis (ASP). In addition a restriction fragment length polymorphism (RFLP) was identified in the gene encoding GAD65 using the restriction enzyme PvuII. The GAD gene markers were analyzed in relation to the presence of specific HLA types and GAD autoantibodies. No evidence of linkage was found between IDDM and either of the genes encoding GAD. This was also the case when subgroups carrying specific HLA susceptibility alleles were analyzed. Nor did we observe any association between these GAD genetic markers and the presence of GAD autoantibodies. Considering the high prevalence of GAD autoantibodies in IDDM, a putative genetic association between GAD and IDDM would be expected to affect most diabetic individuals. Therefore, our data indicate that the association between GAD and IDDM is not genetically determined, and that microsatellites used in this study do not contribute to the prediction of IDDM.
 ...
PMID:Genetic markers for glutamic acid decarboxylase do not predict insulin-dependent diabetes mellitus in pairs of affected siblings. The Danish Study Group of Diabetes in Childhood. 904 16

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.
 ...
PMID:Modulation and detection of IDDM by membrane associated antigens from the islet beta cell line NIT-1. 908 Feb 97

GAD65 contains an amino acid sequence which is highly homologous with a sequence in the 2C protein of coxsackievirus B4 (CBV4-2C). In the present study the possibility that this region could contain an epitope capable of inducing immunological cross-reactivity between CBV4-2C and GAD65 was evaluated. Six out of seven rabbit sera, which were raised against seven different synthetic peptides carrying various modifications of the homology sequence, showed cross-reactivity between 2C. GAD65 and GADD67 derived peptides in ELISA. There was substantial cross-reactivity between 2C and GAD65 peptides, but not between 2C and GAD67 peptides. The most cross-reactive peptides were those corresponding to the 2C sequences FIEWLKVKILPEVKEK and KILPEVKEKHEFLSRL. When the binding of the four 2C peptide-specific sera to the GAD65 protein was analysed in immunoprecipitation, two sera were found to be cross-reactive (anti-FIEWLKVKILPEVKEK and anti-WLKVKILPEVKEKHEF). One of these (anti-WLKVKILPEVKEKHEF) reacted also with coxsackie B virus (CBV)-infected cells. Antibodies against this epitope were induced during enterovirus (including CBV) infections in initially healthy children who later progressed to clinical insulin-dependent diabetes mellitus (IDDM). Antibody responses were frequent also in constantly GAD65 antibody-negative non-diabetic children, and antibody levels did not differ between newly diagnosed IDDM patients and matched control subjects. Blocking experiments confirmed that the observed reactivity of both rabbit and human antibodies was immunologically specific. The results suggest that the epitope is antigenically highly similar in 2C and GAD65, and that peptide immunization induces antibodies which cross-react with these molecules. However, the significance of this phenomenon in the pathogenesis of IDDM remains to be confirmed, as the peptide antibody levels were similar in patients with recent-onset IDDM and in control subjects.
 ...
PMID:Antibody cross-reactivity induced by the homologous regions in glutamic acid decarboxylase (GAD65) and 2C protein of coxsackievirus B4. Childhood Diabetes in Finland Study Group. 909 22

Pancreatic islet beta-cell destruction leading to insulin-dependent diabetes mellitus (IDDM) is an autoimmune T cell-mediated process. Peripheral blood T cells, which proliferate to islet antigens such as glutamic acid decarboxylase (GAD), (pro)insulin or tyrosine phosphatase IA-2, can be detected in at-risk, first degree relatives of people with IDDM. However, cross-sectional studies cannot define the relationship between T cell responses and progression to IDDM. Longitudinal studies were therefore undertaken on 50 at-risk, first degree relatives tested at least yearly for up to 4 years, during which time five developed IDDM. Peripheral blood T cell responses to a GAD67(aa208-404)-glutathione-S-transferase (GST) fusion protein, GST, insulin and tetanus toxoid were measured, together with antibodies to islet cells, GAD, insulin and IA-2. High levels of antibodies to GAD or insulin were generally associated with low T cell responses to these antigens. Relatives who developed IDDM were characterized by high levels of antibodies to insulin and/or islet cells, and high T cell responses to GAD67-GST and tetanus, but not insulin, in the 24 months before clinical diagnosis. Cross-sectionally, T cell responses to GAD67(aa208-404)-GST and to full-length GAD65-GST were highly correlated (r=0.75, P<0.002). In conclusion, increased cellular immunity to the mid region of GAD67 was a marker of late pre-clinical IDDM, but appears to reflect a more general, transient state of cellular immune hyperresponsiveness.
 ...
PMID:High T cell responses to the glutamic acid decarboxylase (GAD) isoform 67 reflect a hyperimmune state that precedes the onset of insulin-dependent diabetes. 918 78

We have previously shown that immunotherapy with complete Freund's adjuvant (CFA) or BCG is highly effective in the prevention of spontaneous insulin-dependent diabetes mellitus (IDDM) and in circumventing the rejection of syngeneic islet grafts in diabetic NOD mice. This protection is reversed by treatment with cyclophosphamide (Cy). The present study was undertaken to determine the effect of BCG vaccination on the progression of Cy-accelerated diabetes in NOD mice and to understand the mechanism of BCG immunotherapy. The time course of Cy and BCG administration showed that the progression of Cy-induced diabetes can only be blocked when BCG vaccination is given within 3 days of Cy administration. Mice given BCG 3 days before (-3 days) or 7 days after Cy treatment were not protected. BCG immunization 1 day after Cy treatment almost completely prevented insulitis in the islets of Cy-treated mice. Cy treatment reduced the endogenous production of anti-GAD67 antibody, whereas BCG vaccination 1 day after Cy treatment restored the production of anti-GAD67 antibody of IgG1 isotype. The comprehensive effect of BCG vaccination on cytokine production in Cy-treated mice was to increase IL-4 production and change the IL-4/IFN-gamma ratio in both serum and supernatant of spleen cell cultures. We found that BCG-induced protection was associated with increased splenic CD4+CD45 RB(high) T cells. Taken together, our results indicate that BCG treatment counteracts the effect of Cy on autoimmune process in IDDM. However, BCG immunotherapy has a narrow window of up to 3 days after Cy treatment to block the progression of Cy-induced diabetes and to allow for the induction of regulatory cells which may effectively downregulate the diabetogenic cells. In summary, our results suggest that BCG vaccination prevents IDDM if given in the prediabetic state. After the induction of diabetes, disease progression can only be prevented within a narrow window of opportunity by this treatment.
 ...
PMID:BCG vaccination prevents insulin-dependent diabetes mellitus (IDDM) in NOD mice after disease acceleration with cyclophosphamide. 921 54


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>