Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0011854 (type 1 diabetes)
 20,749 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Glutamic acid decarboxylase (GAD) 65 is a major autoantigen in type 1 diabetes. Regions of homology exist between GAD65 (residues 250-273) and the Coxsackie P2-C protein (residues 28-50) and between GAD65 (residues 506-518) and proinsulin (residues 24-36), and each of these has been reported to be a diabetes-associated T cell target. The aim of this study was to determine whether the homologous regions are shared targets of T lymphocyte reactivity in individual patients with type 1 diabetes. T cell proliferation against the corresponding peptide pairs, GAD254-276 and Coxsackie P2-C32-54 and GAD506-518 and proinsulin24-36, were measured in peripheral blood mononuclear cells from 26 patients with newly diagnosed type 1 diabetes and 24 control subjects. Responses with stimulation indices higher than 3 were found against each of the antigens tested in both patients and control subjects, and no differences were observed between groups. A strong positive correlation was found between responses to the corresponding peptide pairs GAD254-276 and Coxsackie P2-C32-54 (r=0.77, P<0.0001), and between responses to the corresponding peptide pairs GAD506-518 and proinsulin24-36 (r=0.66, P<0.0001). However, a similar correlation was also observed between responses to the noncorresponding pairs Coxsackie P2-C32-54 and proinsulin24-36 (r=0.82, P<0.0001), Coxsackie P2-C32-54 and GAD506-518 (r=0.82, P<0.0001), and GAD254-276 and proinsulin24-36 (r=0.83, P<0.0001). Strikingly, increased responses to peptides were found almost exclusively in subjects with high stimulation indices against the recall antigen tetanus toxoid, further suggesting that peripheral blood T cell responses are related to a general subject hyperreactivity. These data suggest that proliferative T cell responses to peptides containing putative autoreactive epitopes of GAD65 and proinsulin are not specific for type 1 diabetes, that correlation between T cell reactivity to peptides is not restricted to those containing homologous regions, and that non-antigen-specific factors are important determinants of in vitro measurements of T cell reactivity.
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PMID:T cell responses to type 1 diabetes related peptides sharing homologous regions. 1140 13

The identification, quantification, and characterization of T-cells reactive with the islet autoantigens GAD65, proinsulin (PI), and tyrosine phosphatase-like molecules IA-2 and phogrin are major research goals in type 1 diabetes. In the Immunology of Diabetes Society First Workshop on Autoreactive T-Cells, the quality of recombinant preparations of these autoantigens was identified as a significant weakness, a finding that may account for much of the inconsistency in published studies of peripheral blood T-cell reactivity to islet autoantigens. Poor antigen quality has also hampered the development of novel technologies for the detection of islet-reactive T-cells. For these reasons, in the present study, several preparations of GAD65, PI, and IA-2 were collected and evaluated for endotoxin content, ability to stimulate a panel of relevant T-cell clones, and inhibitory effects on proliferation to unrelated third-party antigens. Through this process, we have been able to identify preparations of GAD65 and IA-2, generated in insect cells using the baculovirus expression system, that stimulate relevant clones and display low inhibitory effects on third-party antigens. In addition, we characterized a PI preparation generated in bacteria as being free of effects on proliferation to third-party antigens and low in endotoxin content. These preparations are important to promote the development of robust and sensitive assays of islet-reactive T-cells in patients with type 1 diabetes or patients at high risk for developing the disease.
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PMID:Characterization of preparations of GAD65, proinsulin, and the islet tyrosine phosphatase IA-2 for use in detection of autoreactive T-cells in type 1 diabetes: report of phase II of the Second International Immunology of Diabetes Society Workshop for Standardization of T-cell assays in type 1 diabetes. 1147 34

The expression of pro(insulin) in the thymus may lead to the negative selection of pro(insulin) autoreactive T cells and peripheral tolerance to this autoantigen in type 1 diabetes (T1D). We investigated whether proinsulin is expressed in the thymus of young nonobese diabetic (NOD) mice, whether T cells from naive NOD female mice at weaning are reactive to mouse proinsulin, and the role of proinsulin as a pathogenic autoantigen in T1D. Proinsulin II mRNA transcripts were detected in the thymus of 2-wk-old NOD mice at similar levels to other control strains. Despite this expression, proinsulin autoreactive T cells were detected in the periphery of 2- to 3-wk-old naive NOD mice. Peripheral T cells reactive to the insulin, glutamic acid decarboxylase 65 (GAD65), GAD67, and islet cell Ag p69 autoantigens were also detected in these mice, indicating that NOD mice are not tolerant to any of these islet autoantigens at this young age. T cell reactivities to proinsulin and islet cell Ag p69 exceeded those to GAD67, and T cell reactivity to proinsulin in the spleen and pancreatic lymph nodes was directed mainly against a p24-33 epitope that spans the B chain/C peptide junction. Intraperitoneal immunization with proinsulin perinatally beginning at 18 days of age delayed the onset and reduced the incidence of T1D. However, s.c. immunization with proinsulin initiated at 5 wk of age accelerated diabetes in female NOD mice. Our findings support the notion that proinsulin p24-33 may be a primary autoantigen epitope in the pathogenesis of T1D in NOD mice.
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PMID:Evidence that a peptide spanning the B-C junction of proinsulin is an early Autoantigen epitope in the pathogenesis of type 1 diabetes. 1167 98

In type 1 diabetes, a number of specific and non-specific antigens have been identified. The major autoantigens involved in the destructive process of beta-cells leading to the development of type 1 diabetes are proinsulin/insulin, glutamic acid decarboxylase (GAD) and the transmembrane protein tyrosine phosphatase (IA-2). These are the only autoantigens that partially satisfy the criteria by which an autoantigen or cross-reactive nonself antigen could be evaluated for a pathogenic role in autoimmune diseases. Antigens by definition induce antibody production and in type 1 diabetes, such (auto) antibodies are accepted as biochemical markers for the disease. Here we describe the main features and usefulness of these markers for disease prediction.
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PMID:Biochemical markers of type 1 diabetes: clinical use. 1171 91

Type 1 diabetes results from the loss of insulin-producing pancreatic beta cells following the action of beta-cell-specific autoimmune responses. One possible treatment for type 1 diabetes is the development of beta-cell substitutes by introducing an insulin-producing gene into non-beta cells, which would evade the beta-cell-specific autoimmune attack. However, this approach has been hampered by the absence of (1) an appropriate glucose-sensing system to regulate insulin gene transcription; (2) enzymes that process proinsulin to insulin; and (3) glucose-regulatable exocytosis in the target cells. Recent attempts to solve these problems have sought new methods for effective gene transfer and have addressed issues such as the expression and release of insulin in response to the physiological stimulus of glucose, the production of biologically active insulin, and the selection of an ideal target cell for the expression of the insulin gene.
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PMID:Recent advances in insulin gene therapy for type 1 diabetes. 1181 71

In human type 1 diabetes (T1D) autoantibodies to insulin precede clinical disease, while little is known about the contribution of insulin-specific T lymphocytes-in particular, T helper (Th) subsets. Here we have studied the in vivo primed cytokine response to preproinsulin in peripheral blood mononuclear cells (PBMCs) and two major Th cell subsets-CD45RO+ memory cells and CD45RA+ naive/resting cells-in 35 individuals with HLA-DRB1*04, DQB1*0302 diabetes risk marker: 12 patients with T1D, 12 autoantibody-positive (Ab+) individuals, and 11 healthy controls. Cytokine secretion (TNF-alpha, IFN-gamma, IL-2, IL-4, IL-5, and IL-10) was measured in the supernatants of the cultures stimulated with 21 overlapping preproinsulin peptides as well as proinsulin and insulin. In Ab+ individuals our results reveal higher IL-4 levels in CD45RO+ memory cells and higher IL-5 levels in CD45RA+ naive/resting cells, while higher IL-2 production was found in PBMCs. In contrast, in PBMCs of T1D patients higher IFN-gamma and IL-10 secretion was found. Our data delineate characteristic cytokine patterns in peripheral T lymphocytes from patients at different stages of the T1D development.
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PMID:Th2 dominance of T helper cell response to preproinsulin in individuals with preclinical type 1 diabetes. 1202 Nov 8

In recent years the physiological role of the proinsulin C-peptide has received increasing attention, focusing on the potential therapeutic value of C-peptide replacement in preventing and ameliorating type 1 diabetic complications. In order to consolidate these new data and to identify the immediate directions of C-peptide research and its clinical usefulness, an International Symposium was held in Detroit, Michigan, on October 20-21, 2000, under the auspices of the Wayne State University/Morris Hood Jr. Comprehensive Diabetes Center. In this communication, we review the cellular, physiological and clinical effects of C-peptide replacement in animal models and in patients with type 1 diabetes. Finally, recommendations are presented as to the most urgent studies that should be pursued to further establish the biological action of C-peptide and its therapeutic value.
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PMID:Proinsulin C-peptide--a consensus statement. 1236 19

A first-line gene therapy for type 1 diabetes should be based on a safe procedure to engineer an accessible tissue for insulin release. We evaluated the ability of the skeletal muscle to release human insulin after electrotransfer (ET)-enhanced plasmid DNA injection in mice. A furin-cleavable proinsulin cDNA under the CMV or the MFG promoter was electrotransferred to immune-incompetent mice with STZ-induced severe diabetes. At 1 week, mature human insulin was detected in the serum of 17/20 mice. After an initial peak of 68.5 +/- 34.9 microU/ml, insulin was consistently detected at significant levels up to 6 weeks after gene transfer. Importantly, untreated diabetic animals died within 3 weeks after STZ, whereas treated mice survived up to 10 weeks. Fed blood glucose (BG) was reduced in correspondence with the insulin peak. Fasting BG was near-normalized when insulin levels were 12.9 +/- 5.3 (CMV group, 2 weeks) and 7.7 +/- 2.6 microU/ml (MFG group, 4 weeks), without frank hypoglycemia. These data indicate that ET-enhanced DNA injection in muscle leads to the release of biologically active insulin, with restoration of basal insulin levels, and lowering of fasting BG with increased survival in severe diabetes. Therefore the skeletal muscle can be considered as a platform for basal insulin secretion.
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PMID:Human insulin production and amelioration of diabetes in mice by electrotransfer-enhanced plasmid DNA gene transfer to the skeletal muscle. 1237 5

Insulin has been used to modify T-cell autoimmunity in experimental models of type 1 diabetes. In a large clinical trial, the effect of insulin to prevent type 1 diabetes is currently investigated. We here show that insulin can adversely trigger autoimmune diabetes in two mouse models of type 1 diabetes, using intramuscular DNA vaccination for antigen administration. In female nonobese diabetic (NOD) mice, diabetes development was enhanced after preproinsulin (ppIns) DNA treatment, and natural diabetes resistance in male NOD mice was diminished by ppIns DNA vaccination. In contrast, GAD65 DNA conferred partial diabetes protection, and empty DNA plasmid was without effect. In RIP-B7.1 C57BL/6 mice (expressing the T-cell costimulatory molecule B7.1 in pancreatic beta-cells), autoimmune diabetes occurred in 70% of animals after ppIns vaccination, whereas diabetes did not develop spontaneously in RIP-B7.1 mice or after GAD65 or control DNA treatment. Diabetes was characterized by diffuse CD4(+)CD8(+) T-cell infiltration of pancreatic islets and severe insulin deficiency, and ppIns, proinsulin, and insulin DNA were equally effective for disease induction. Our work provides a new model of experimental autoimmune diabetes suitable to study mechanisms and outcomes of insulin-specific T-cell reactivity. In antigen-based prevention of type 1 diabetes, diabetes acceleration should be considered as a potential adverse result.
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PMID:Induction of autoimmune diabetes through insulin (but not GAD65) DNA vaccination in nonobese diabetic and in RIP-B7.1 mice. 1240 15

Insulin is a major disease determinant in type 1 diabetes, type 2 diabetes, and related disorders. The role of variations in the expression of the insulin gene has been proposed in genetic susceptibility to the three pathological conditions in humans. In contrast to humans, rodents express two proinsulin isoforms. One isoform, proinsulin 1, is expressed exclusively in islets. The second, proinsulin 2, is expressed in islets and in other tissues, especially the thymus. We took advantage of the expression of these two isoforms to introduce a null proinsulin 2 allele in NOD mice and to evaluate the consequence of a variation of proinsulin 2 gene expression on the development of type 1 diabetes on the NOD genetic background. Heterozygote NOD mutant mice carrying a null proinsulin 2 mutation showed an increased incidence of type 1 diabetes at successive backcross generations. Plasma glucose and insulin levels were identical in prediabetic mutant and in wild-type mice at 4 weeks of age. Variation in insulin gene expression is hypothesized to interfere with diabetes development at both the islet and the thymus level.
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PMID:Proinsulin 2 knockout NOD mice: a model for genetic variation of insulin gene expression in type 1 diabetes. 1247 95


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