Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

---

Query: UMLS:C0011849 (diabetes)
277,896 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Autoimmune gastritis, induced by day-3 thymectomy of BALB/c mice, is a destructive CD4+ T cell-mediated disease characterized by leukocyte infiltrates in the gastric mucosa, loss of parietal and chief cells and anti-gastric H/K ATPase autoantibodies. Our previous studies have indicated that a T cell response to the H/K ATPase beta subunit is required for the onset of autoimmune gastritis (Alderuccio, F., Toh, B. H., Tan, S. S., Gleeson, P. A. and van Driel, I. R., J. Exp. Med. 1993. 178: 419). To determine whether a response to the beta subunit autoantigen is alone sufficient to induce autoimmunity, or whether other tissue-specific factors are required, we have generated transgenic mice expressing the gastric H/K ATPase beta subunit in beta islet cells of the pancreas (RIP-H/K beta). RIP-H/K beta mice developed autoimmune gastritis and insulitis after day-3 thymectomy. Significantly, insulitis, observed as a peri-islet infiltrate, was only detected in thymectomized mice with autoimmune gastritis. There was no apparent immune destruction of the pancreas as insulitis did not progress to invasion of the islets or diabetes. Double transgenic mice, expressing the gastric H/K ATPase beta subunit in the thymus and in the pancreas, were protected from both gastritis and insulitis after day-3 thymectomy. Therefore, insulitis in the RIP-H/K beta mice appears to be dependent on a T cell response to the H/K ATPase beta subunit. This is the first example where an organ-specific initiating autoantigen has been expressed in another peripheral tissue. Autoimmune destruction in the stomach, but not the pancreas, indicates that tissue-specific factors play a fundamental role in the development of organ-specific autoimmunity.
...
PMID:Expression of a gastric autoantigen in pancreatic islets results in non-destructive insulitis after neonatal thymectomy. 758 46

As part of a general program of screening islet expression libraries we have identified a clone from a lambda gt11 human islet expression library that reacts with human diabetic sera and, upon sequencing, was determined to be the neuroendocrine islet autoantigen ICA512 (islet cell antigen 512). In the current communication, we describe the development of a radioassay for autoantibodies to ICA512 (ICA512AA) using in vitro transcribed and translated protein for production of labeled antigen. Our initial results indicate that this radioassay is significantly more sensitive than the enzyme-linked immunosorbant assay, which uses a COOH-terminal fragment of ICA512. The ICA512AA radioassay uses a 96-well format with membrane separation of antibody bound from free antigen and should be readily adaptable to automated large-scale screening. Only 7 microliters of serum is required for triplicate determinations. In order to determine the specificity and sensitivity of this assay and estimate its positive predictive value, we have studied 42 new-onset diabetic patients, 33 first-degree relatives of diabetic patients followed to diabetes, 694 islet cell antibody-negative (ICA-) relatives, and 205 normal control subjects. Thirty-eight percent of new-onset patients and 48% of relatives followed to diabetes express autoantibodies to ICA512 exceeding the 99th percentile of the normal control subjects. In contrast, only 1.4% of ICA- first-degree relatives were positive for ICA512 autoantibodies.(ABSTRACT TRUNCATED AT 250 WORDS)
Diabetes 1995 Nov
PMID:ICA512 autoantibody radioassay. 758 34

The nonobese diabetic (NOD) mouse spontaneously develops insulin-dependent diabetes (IDDM or type I diabetes), resulting from T-lymphocyte-mediated destruction of pancreatic beta cells. This autoimmune phenomenon includes mononuclear cell infiltration of the islets of Langerhans (insulitis) and the presence of circulating autoantibodies. The specificity of the autoantibodies and of the autoreactive T cells was investigated and several autoantigens were proposed, in particular glutamic acid decarboxylase (GAD). This enzyme exists in two forms (GAD 65 and GAD 67) encoded by two independent genes. To explain the role of GAD in type I diabetes, we prepared recombinant rat GAD 65 as fusion protein, produced in an Escherichia coli expression system, and we treated NOD female mice from 4 to 7 weeks of age by repeated intraperitoneal injections of 5 micrograms fusion protein (3 injections per week); control groups received the fusion partner, maltose binding protein (MBP) or dissolving agent (NaCl 0.9%). We investigated two parameters, the degree of insulitis 5 weeks after the last injection and the overall incidence of the disease. Histological examination of the pancreata from GAD-treated mice revealed a significant reduction in the severity of insulitis compared with the two control groups. Furthermore, we observed that the time of onset and the frequency of diabetes in NOD females injected with GAD fusion protein differed significantly from the control groups receiving MBP or NaCl (P < 0.0001). These results show that a 3-week treatment of NOD female mice starting at 4 weeks of age protects them from diabetes, again emphasizing the crucial role of GAD as autoantigen in type I diabetes.
...
PMID:Prevention of autoimmune diabetes in nonobese diabetic female mice by treatment with recombinant glutamic acid decarboxylase (GAD 65). 760 72

Insulin-dependent (type 1) diabetes mellitus is an organ-specific autoimmune disease frequently associated with an islet-specific humoral autoimmune response. The role of islet cell autoantibodies in the disease process is unclear; in particular, it is not known whether they are a non-specific side effect of islet cell destruction or play a role in the autoimmune network leading to type 1 diabetes. Here we report the immunoglobulin gene usage and somatic mutation rates of a panel of seven human monoclonal islet cell autoantibodies (MICA 1-7) directed towards the major islet cell autoantigen glutamate decarboxylase (GAD). These autoantibodies were produced from cells from two patients with newly diagnosed type 1 diabetes. VH1, VH4 and V lambda 2 gene segments were frequently used in the MICA, but no correlation between V gene usage and epitope recognition was found. The nonrandom ratio of replacement versus silent mutations in the variable gene region, an accumulation of replacement mutations in the complementarity determining regions, which confer antigen binding, and the high relative avidity for GAD observed for MICA 1, 3, 4, and 6, suggested that the immune response to GAD is driven by the antigen. In contrast, MICA 2, 5, and 7, revealing a lower affinity for antigen, have accumulated a large number of silent mutations. These latter antibodies may, therefore, be characteristic for later stages of the chronic autoimmune disease. Our results argue in favor of an antigen-driven autoantibody response to islets in human type 1 diabetes. They suggest that GAD is an important target of autoimmunity associated with type 1 diabetes.
...
PMID:Immunoglobulin variable gene analysis of human autoantibodies reveals antigen-driven immune response to glutamate decarboxylase in type 1 diabetes mellitus. 761 98

An enzyme-linked immunosorbent assay for GAD65, the smaller form of glutamic acid decarboxylase and an important autoantigen related to Type 1 diabetes, is described. The competitive binding assay is based on a monoclonal antibody specifically reactive with GAD65. The assay is suitable for quantification of this enzyme between 40 and 300 pg/microliter. The intraassay coefficients of variation (cv) are between 5.6% and 8.9% and the interassay cvs lie between 9.4% and 17.3%. The covalent binding of the antigen to magnetic beads as the solid phase makes the assay also applicable for quantification of GAD65 in tissue homogenates with a high concentration of detergent. The GAD65 content of islets isolated from newborn Lewis rat was detected to be 310 pg/islet. However, GAD65 was not detectable in mouse islets.
Diabetes Res 1994
PMID:A monoclonal antibody based enzyme-linked immunosorbent assay for the determination of GAD65, the smaller isoform of glutamic acid decarboxylase. 762 17

Sera from patients with insulin-dependent diabetes immunoprecipitate 64,000-M(r) proteins, distinct from glutamate decarboxylase, that are cleaved to 37,000- and 40,000-M(r) fragments by trypsin. We investigated possible relationships between 37,000- or 40,000-M(r) fragments of antigen and the tyrosine phosphatase-like protein, IA-2 (ICA512). Antibodies from nondiabetic relatives bound differentially to 37,000- and 40,000-M(r) fragments indicating presence of distinct epitopes. Precursors of these fragments could be separated on immobilized lectins, suggesting different carbohydrate content. Levels of antibodies to 40,000-M(r) fragments were strongly associated with those to the intracellular domain of IA-2. Recombinant intracellular domain of IA-2 blocked binding of antibodies to 40,000-M(r) fragments expressed by insulinoma cells and partially blocked binding to 37,000-M(r) fragments. Furthermore, trypsinization of recombinant intracellular domain of IA-2 generated proteolytic fragments of identical M(r) to the 40,000-M(r) fragments of insulinoma antigen; 37,000-M(r) fragments were not generated. Thus, 40,000-M(r) fragments of islet autoantigen are derived from a protein similar or identical to the tyrosine phosphatase-like molecule, IA-2. The 37,000-M(r) fragments are derived from a different, although related, protein.
...
PMID:Relationship of the 37,000- and 40,000-M(r) tryptic fragments of islet antigens in insulin-dependent diabetes to the protein tyrosine phosphatase-like molecule IA-2 (ICA512). 765 22

The first human monoclonal islet cell antibodies of the IgG class (MICA 1-6) obtained from an individual with Type 1 (insulin-dependent) diabetes mellitus were cytoplasmic islet cell antibodies selected by the indirect immunofluorescence test on pancreas sections. Surprisingly, they all recognized the 64 kDa autoantigen glutamate decarboxylase. In this study we investigated which typical features of cytoplasmic islet cell antibodies are represented by these monoclonals. We show by double immunofluorescence testing that MICA 1-6 stain pancreatic beta cells which is in agreement with the beta-cell specific expression of glutamate decarboxylase. In contrast an islet-reactive IgM monoclonal antibody obtained from a pre-diabetic individual stained all islet cells but lacked the tissue specificity of MICA 1-6 and must therefore be considered as a polyreactive IgM-antibody. We further demonstrate that MICA 1-6 revealed typical features of epitope sensitivity to biochemical treatment of the target tissue which has been demonstrated for islet cell antibodies, and which has been used to argue for a lipid rather than a protein nature of target antigens. Our results provide direct evidence that the epitopes recognized by the MICA are destroyed by methanol/chloroform treatment but reveal a high stability to Pronase digestion compared to proinsulin epitopes. Conformational protein epitopes in glutamate decarboxylase therefore show a sensitivity to biochemical treatment of sections such as ganglioside epitopes. MICA 1-6 share typical features of islet cell and 64 kDa antibodies and reveal that glutamate decarboxylase-reactive islet cell antibodies represent a subgroup of islet cell antibodies present in islet cell antibody-positive sera.
...
PMID:Human monoclonal islet specific autoantibodies share features of islet cell and 64 kDa antibodies. 769 67

Glutamic acid decarboxylase (GAD) catalyzes the biosynthesis of the inhibitory neurotransmitter gamma-aminobutyric acid (GABA). GAD has been suggested as an autoantigen in insulin-dependent diabetes mellitus and stiff-man syndrome. Recently, three forms of membrane-associated GAD (MGAD) have been characterized in porcine brain, but the subcellular localization and function of these proteins are unknown. We present evidence that GAD activity is associated with synaptic vesicles from porcine brain. These vesicles contain a 60 kDa protein recognized by serum from patients with insulin-dependent diabetes mellitus, probably MGADII, as shown by subcellular fractionation and immunoblotting. These results raise the possibility that the association of MGADII with synaptic vesicles may be crucial for its role as an autoantigen in insulin-dependent diabetes mellitus.
...
PMID:Synaptic vesicle-associated glutamate decarboxylase: identification and relationship to insulin-dependent diabetes mellitus. 771 21

Insulin-dependent diabetes mellitus (IDDM) is an autoimmune disease that results in the destruction of the pancreatic islet beta cells. Glutamic acid decarboxylase (GAD) has been recently indicated as a key autoantigen in the induction of IDDM in nonobese diabetic mice. In human diabetes, the mechanism by which the beta cells are destroyed is still unknown. Here we report the first evidence for the presence of GAD-specific cytotoxic T cells in asymptomatic and recent diabetic patients. GAD65 peptides displaying the human histocompatibility leukocyte antigen (HLA)-A*0201 binding motif have been synthesized. One of these peptides, GAD114-123, binds to HLA-A*0201 molecules in an HLA assembly assay. Peripheral blood mononuclear cells from individuals with preclinical IDDM, recent-onset IDDM, and from healthy controls were stimulated in vitro with the selected peptide in the presence of autologous antigen-presenting cells. In three cases (one preclinical IDDM and two recent-onset IDDM), we detected specific killing of autologous antigen-presenting cells when incubated with GAD114-123 peptide or when infected with a recombinant vaccinia virus expressing GAD65. These patients were the only three carrying the HLA-A*0201 allele among the subjects studied. Our finding suggests that GAD-specific cytotoxic T lymphocytes may play a critical role in the initial events of IDDM.
...
PMID:Cytotoxic T cells specific for glutamic acid decarboxylase in autoimmune diabetes. 772 68

The enzyme L-glutamic acid decarboxylase is a major autoantigen of the beta cell. Autoantibodies against this enzyme are observed before the onset of insulin-dependent diabetes mellitus (IDDM) in man and may be of predictive value. There is evidence that this enzyme is involved in the development of autoimmune diabetes in animals. In order to facilitate the investigation of the role of L-glutamine acid decarboxylase in IDDM, we expressed the 65 kDa isoform of human islet L-glutamic acid decarboxylase in insect cells using a baculovirus-based vector. The material was expressed at high levels (up to 50 mg/l of cells). Partially purified metabolically labelled L-glutamic acid decarboxylase bound to immunoglobulins in the sera from 20 of 49 subjects with newly-diagnosed IDDM. The enzyme was isolated in high yields (up to 26 mg/l cell culture) with fully maintained enzymatic activity by either ion-exchange chromatography or immunoaffinity chromatography. Purified L-glutamic acid decarboxylase inhibited the binding of radioactive L-glutamic acid decarboxylase, prepared by in vitro translation of mRNA, to immunoglobulins in the sera of subjects with IDDM. Recombinant human islet L-glutamic acid decarboxylase, isolated from Sf9 cells, is a suitable material for the large scale investigation of the utility of this enzyme in the prediction and prevention of autoimmune diabetes.
...
PMID:Isolation by anion-exchange of immunologically and enzymatically active human islet glutamic acid decarboxylase 65 overexpressed in Sf9 insect cells. 774 24


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

---