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)

The effect of in vivo administration of exogenous tumor necrosis factor-alpha on the survival of rat islet xenografts in STZ-induced diabetic mice was examined. Daily subcutaneous injections of purified recombinant murine TNF-alpha (3 micrograms/day) for 7 days after transplantation of islets prolonged the survival of the xenografts (26.7 +/- 4.9 days) compared with controls (11.2 +/- 1.1 days). Extension of the treatment from 0 to 59 days after transplantation produced an even greater prolongation of graft survival (53.7 +/- 8.5 days). After cessation of treatment, an accelerated rejection of the grafts occurred. A most interesting finding was that delaying initiation of treatment until 3 days after transplantation and continuing until 60 days produced a remarkable prolongation of xenograft survival (mean survival time > 89.8 +/- 17.5 days) with 2 recipients still normoglycemic at 124 days. Removal of the grafts at this time returned the 2 mice to a diabetic state. A second islet transplant from the same donor rat strain (Wistar-Furth) had an accelerated rejection, indicating that the long-term survival of the xenografts was not because of induction of tolerance. Delaying initiation of TNF treatment until 6 days after transplantation produced only a slight prolongation of survival (17.5 +/- 1.2 days). Prolongation of islet xenograft survival also was obtained by continuous, subcutaneous delivery of TNF-alpha by a 7-day mini-osmotic pump (3 micrograms/day). Lower daily doses of TNF-alpha (0.003, 0.3, and 1.0 micrograms) had no effect on graft survival.(ABSTRACT TRUNCATED AT 250 WORDS)
Diabetes 1993 May
PMID:Tumor necrosis factor-alpha prevents rejection of islet xenografts (rat to mouse). 848 22

To study self reactivity, a transgenic mouse model has been established in which the lymphocytic choriomeningitis virus (LCMV) glycoprotein (gp) is expressed in the beta-islet cells of the pancreas (rat insulin promoter (RIP)-gp). These mice (H-2b) do not spontaneously develop diabetes; however, infection with the LCMV strain WE rapidly induces hyperglycemia. In this study, comparative analysis of H-2k RIP-gp-transgenic animals demonstrated that the haplotype influences the incidence and kinetics of diabetes and alters the requirement for the CD4+ T cell subset. This study also showed that the properties of the virus expressing the self target Ag determined whether hyperglycemia occurred in RIP-gp-transgenic mice. Various LCMV strains were able to induce diabetes in RIP-gp-transgenic animals, whereas infection with a recombinant vaccinia virus expressing LCMV-gp (vacc-gp) did not induce diabetes. However, vacc-gp could induce diabetes in double (RIP-gp/TCR)-transgenic mice, where the majority of CD8+ T cells expressed a receptor specific for LCMV-gp, suggesting that a critical number of self-reactive T cells must be activated to induce disease. Notably, histologic analysis of pancreata taken various days after LCMV or vacc-gp infections indicated that induction of diabetes coincided with an increase in MHC class I expression on the islets of Langerhans. Additional studies with vacc-gp were done to determine other factors that possibly enhance autoimmune attack. Transgenic mice expressing both LCMV-gp and TNF-alpha under the control of the RIP were infected with vacc-gp, and 50% of RIP-gp/TNF-alpha-transgenic animals became hyperglycemic. These data suggest that the increased local lymphocyte traffic as a result of TNF-alpha expression attracts activated gp-specific T cells, enhancing the possibility of hyperglycemia. Collectively, these results demonstrate that the induction of diabetes in this model is influenced by the MHC haplotype, the infectious agent, TNF-alpha expression, the level of MHC class I expression, and the induction of a threshold number of self-reactive CTL.
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PMID:Induction of diabetes is influenced by the infectious virus and local expression of MHC class I and tumor necrosis factor-alpha. 849 10

Recent studies suggest that TNF-alpha affects various biochemical and physiological processes which may be linked to the etiology of non-insulin-dependent diabetes mellitus (NIDDM). For example, TNF-alpha interferes with the signaling of the insulin receptor and the metabolism of glucose transporters. The possibility that TNF-alpha might directly reduce glucose-stimulated insulin secretion in pancreatic beta-cells was examined by using an established pancreatic beta-cell line (INS-1). TNF-alpha did not affect glucose-induced acute insulin secretion (30 min). However, over a longer time period (24 h), TNF-alpha decreased glucose-induced insulin secretion without affecting the total amount of insulin in the cell. In the presence of TNF-alpha levels of 0, 10, 100 and 1000 U/ml, the respective 20 mM glucose-induced insulin secretion was 1.736 +/- 0.166, 1.750 +/- 0.302, 1.550 +/- 0.200, and 1.400 +/- 0.112 mU/ml per 3 x 10(5) cells in 24 h.
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PMID:TNF-alpha inhibits glucose-induced insulin secretion in a pancreatic beta-cell line (INS-1). 854 58

Cytokines have been shown to play an important role in regulating tolerance to islet Ags and provoking destructive islet lesions. However, data from a number of experimental systems have been conflicting, and the role of cytokines produced by T lymphocytes at various stages of diabetes has not been clearly defined. We have studied the production of cytokines in the pancreas during the development of autoimmune diabetes induced in mice by administration of (5) low doses of streptozotocin (STZ) (MDSDM). Diabetes in this model is T lymphocyte dependent. We used techniques of semiquantitative PCR to identify and quantitate cytokines that are produced. We have found that IL-2, IL-4, TNF-alpha, and IFN-gamma are expressed by the time the fourth dose of STZ is given. In the same pancreas, all of these cytokines (including IL-4) may be found. However, expression of IFN-gamma, but not IL-4, was limited to intrapancreatic lymphocytes and was not detectable at extrapancreatic lymphoid sites. Moreover, mAbs against IFN-gamma, but not against IL-4 or IL-2, prevent hyperglycemia and insulitis in MDSDM, suggesting that IFN-gamma regulates development of disease. Cells in the pancreases of nondiabetic mice treated with anti-IFN-gamma mAb and STZ show enhanced expression of IL-4, but the prevention of disease is due to blockade of the IFN-gamma itself, and not due to secretion of IL-4, because systemic administration of IL-4 does not prevent MDSDM. Thus, our findings indicate that cytokines produced by Th1 (or T cytolytic 1) and Th2 (or T cytolytic 2) cells are found in the pancreases of mice developing autoimmune diabetes. IFN-gamma is responsible for progression to diabetes, and its production is limited to lymphocytes only at that site.
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PMID:Regulation of cytokine production during development of autoimmune diabetes induced with multiple low doses of streptozotocin. 861 81

Inhibition of tumor necrosis factor (TNF)-alpha action has recently been shown to reverse insulin resistance dramatically and to improve glycemic control in obese rodents. This double-blind study was designed to assess the effects of a recombinant-engineered human TNF-alpha-neutralizing antibody (CDP571) on glucose homeostasis in obese NIDDM patients. Glycemic control and insulin sensitivity were monitored in 21 NIDDM subjects for a 2-week run-in and then for 6 weeks after treatment in a randomized fashion with a single intravenous dose of either CDP571 (5 mg/kg) or an equivalent volume of normal saline. The prolonged half-life of the antibody ensured adequate plasma levels as measured throughout the study. Concentrations of fasting glucose (CDP571: 10.0 +/- 0.8, 10.1 +/- 0.8, 10.0 +/- 1.0; placebo: 8.5 +/- 0.6, 8.1 +/- 0.5, 8.7 +/- 0.8 mmol/l at baseline, day 1, and week 4, respectively), fasting serum insulin (CDP571: 21.2 +/- 2.8, 21.0 +/- 2.8, 24.8 +/- 3.3; placebo: 19.0 +/- 2.8, 20.8 +/- 2.9, 17.5 +/- 2.2 pmol/l, respectively), and C-peptide remained unaffected by the type of treatment throughout the study. The percentage rate of glucose clearance per minute (KITT) during intravenous insulin sensitivity tests was identical in the CDP571 and placebo groups at baseline and also at 1 and 4 weeks after treatment (mean +/- SE; CDP571: 1.33 +/- 0.21, 1.44 +/- 0.25, 1.26 +/- 0.18; placebo: 1.38 +/- 0.15, 1.47 +/- 0.20, 1.52 +/- 0.20; P = 0.85, 0.93, and 0.36, respectively). TNF-alpha neutralization over a period of 4 weeks had no effect on insulin sensitivity in obese NIDDM subjects.
Diabetes 1996 Jul
PMID:Effects of an engineered human anti-TNF-alpha antibody (CDP571) on insulin sensitivity and glycemic control in patients with NIDDM. 866 37

To clarify the mechanisms that cause elevation of plasma fibrinogen levels in diabetes, we first examined the effect of hyperglycemia on the production of interleukin 6 (IL-6) and tumor necrosis factor (TNF) by cultured human peripheral blood monocytes. Monocyte-enriched fractions isolated from 20 healthy volunteers were incubated with 11 mmol/l glucose, 33 mmol/l glucose, or mannitol as an osmolar control for 6 or 24 h. After 6 h of incubation, IL-6 and TNF-alpha mRNA levels were analyzed by reverse transcription and polymerase chain reaction. In addition, after 24 h of incubation, IL-6 and TNF-alpha immunoreactivity in the culture medium was measured by enzyme-linked immunoassay. Both IL-6 and TNF-alpha mRNA levels and immunoreactivity were significantly increased by treatment with 33 mmol/l glucose compared with treatment with 11 mmol/l glucose or 11 mmol/l glucose with 22 mmol/l mannitol. In addition, preincubation of the cells with an anti-TNF monoclonal antibody (mAb) blocked the stimulatory effect of 33 mmol/l glucose on IL-6 synthesis and secretion. Second, we examined the ability of conditioned media from human peripheral blood monocytes to stimulate beta-fibrinogen mRNA synthesis in HepG2 cells. The conditioned medium from monocytes treated with 33 mmol/l glucose increased beta-fibrinogen mRNA levels. The results of this study demonstrate that hyperglycemia stimulated IL-6 and TNF synthesis and secretion by human peripheral monocytes in vitro and that the IL-6 response to hyperglycemia may be mediated by TNF. Furthermore, hyperglycemia may increase fibrinogen levels through stimulation of peripheral monocytes. These results suggest that hyperglycemia may cause hyperfibrinogenemia in diabetic patients through an IL-6-dependent and TNF-dependent mechanism.
Diabetes 1996 Jul
PMID:Glucose-dependent interleukin 6 and tumor necrosis factor production by human peripheral blood monocytes in vitro. 866 48

Modified lipoproteins, particularly different forms of oxidized LDL (ox-LDL), have been reported to elicit humoral immune responses both in experimental animals and humans. In diabetes, glycation and oxidation processes coexist and lead to the formation of glycoxidation products. Ox-LDL has been demonstrated in atheromatous lesions, anti-ox-LDL antibodies have been detected in circulation and in atheromatous plaques, and immune complexes (ICs) formed with LDL and anti-LDL (LDL-IC) have been isolated from the serum of patients with manifestations of atherosclerosis. In addition, in vitro formed LDL-ICs and ICs isolated from patients have been demonstrated to cause intracellular accumulation of cholesteryl esters (CEs) in human macrophages and fibroblasts. The accumulation of CEs in macrophages exposed to LDL-ICs is unique to this type of IC and is associated with paradoxical overexpression of LDL receptor and with increased synthesis and release of interleukin 1 beta and tumor necrosis factor (TNF) alpha. The overexpression of LDL receptors is higher in LDL-IC-stimulated macrophages that release markedly high amounts of TNF-alpha than in macrophages that release low amounts of TNF-alpha into the medium. The release of cytokines in the subendothelial space may have a significant role in promoting the interaction of endothelial cells with mononuclear cells, causing endothelial cell damage directly or indirectly, and also in inducing smooth muscle cell proliferation. Thus, in view of the above data, it can be concluded that humoral autoimmunity may play a significant role in the pathogenesis of atherosclerosis in diabetes.
Diabetes 1996 Jul
PMID:Cytokines, modified lipoproteins, and arteriosclerosis in diabetes. 867 88

Expression of the co-stimulatory molecule B7-1 (CD80) on pancreatic beta cells can overcome peripheral T cell tolerance in transgenic models of autoimmune disease. This study aimed to determine if aberrant B7-1 or B7-2 (CD86) expression on pancreatic beta cells is involved in the pathogenesis of autoimmune diabetes in non-obese diabetic (NOD) mice. Immunohistochemical analysis of NOD pancreas sections revealed no evidence of B7-1 or B7-2 expression on pancreatic beta cells at any stage prior to the onset of either spontaneously arising or cyclophosphamide-accelerated diabetes. Likewise, the NOD-derived NIT-1 beta cell line did not express surface B7 or B7-1 mRNA either constitutively or following exposure to IFN-gamma and TNF-alpha, two cytokines known to be present in the insulitis lesion of NOD mice, or cAMP which can induce B7-1 expression on B cells. Both B7-1 and B7-2 were, however, highly expressed on the majority of islet-infiltrating inflammatory cells in NOD mice between days 7 and 12 after the administration of cyclophosphamide which results in accelerated beta cell destruction. Likewise B7-1 and B7-2 were extensively expressed on islet-infiltrating cells present at the time of diabetes onset in NOD SCID mice with adoptively transferred diabetes. By immunohistochemistry and flow cytometry, it was determined that the phenotype of B7+ cells in the pancreas of NOD mice 9 days after cyclophosphamide included a mixture of macrophages and both CD4+ and CD8+ T cells. B7-2 was also expressed on islet-infiltrating cells in the spontaneously occurring diabetes of female NOD mice, but the levels of B7-1 expression were low in comparison with the accelerated models of diabetes. RIP-IL-2 transgenic mice, which have extensive islet infiltration but no autoimmune beta cell destruction, also had virtually no B7-1 expression and a minority of B7-2-expressing inflammatory cells. Thus, the activation of beta cell-specific T cells in NOD mice does not appear to be a result of aberrant expression of B7 on the beta cells. Expression of B7-1 and B7-2 on islet-infiltrating cells is, however, associated with autoimmune beta cell destruction, suggesting a role for the B7-CD28 interaction in this process.
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PMID:Pancreatic expression of B7 co-stimulatory molecules in the non-obese diabetic mouse. 874 58

The mechanism of TNF-alpha to regulate glucose metabolism remains unclear. To further delineate the TNF-alpha signal transduction pathway mediating glucose metabolism, we utilized L6 rat myoblasts which contain the receptors for the insulin-like growth factor-I (IGF-I) and TNF-alpha, and the ability of both ligands to stimulate glucose uptake was compared. IGF-I (6.5 nM) maximally stimulated glucose uptake 7-fold after 24 h incubation, while 23 nM TNF-alpha maximally stimulated glucose uptake 3-fold only after 48 h incubation. IGF-I receptor beta-subunit, insulin receptor substrate-1 (IRS-1), and mitogen-activated protein (MAP) kinase were all phosphorylated in response to 6.5 nM IGF-I after 10 min incubation. In contrast, the treatment with 23 nM TNF-alpha failed to phosphorylate either IGF-I receptor beta-subunit or IRS-1 but did phosphorylate MAP kinase as much as IGF-I did. Despite a similar extent to which TNF-alpha induced MAP kinase phosphorylation as IGF-I did, TNF-alpha stimulated glucose uptake less compared to IGF-I. The results indicate that MAP kinase phosphorylation is not sufficient for glucose uptake in L6 myoblasts. TNF-alpha-elicited signal transduction to glucose uptake may utilize a different pathway from that seen with IGF-I.
Diabetes Res Clin Pract 1996 Apr
PMID:TNF-alpha stimulates glucose uptake in L6 myoblasts. 880 77

Celiac disease (CD) is an immune disease triggered by the cereal antigen gliadin, resulting in villous atrophy in the small intestine. Susceptibility to the development of CD is strongly influenced by genes in the major histocompatibility complex, in particular alleles of the DQ genes in the class II region. However recent evidence has suggested that the major histocompatibility complex (MHC) class III region may be linked to celiac disease independently of the class II region. Among the genes located in this area is TNF-alpha, which encodes the cytokine tumor necrosis factor-alpha which has a broad range of pro-inflammatory, immunomodulatory and catabolic activities. Therefore, aberrant expression of TNF-alpha could be important in the pathogenesis of MHC-associated immune disorders. A TNF-alpha variant with a polymorphism in its promoter region has been described and designated TNF2. TNF2 has been associated with a variety of MHC-linked diseases, including systemic lupus erythematosus, dermatitis herpetiformis and insulin-dependent diabetes mellitus (IDDM), as well as parasitic infections. TNF2 has previously been shown to be associated with the MHC haplotype HLA A1-B8-DR3-DQ2, which confers susceptibility to CD. We have analyzed the distribution of TNF2 alleles in a group of celiac patients (n = 52) compared to controls (n = 52) in an effort to evaluate its role, if any, in susceptibility to the condition. TNF2 has a frequency of 0.5000 (SE +/- 0.0490) in CD, compared to 0.1635 (+/- 0.0362) in a control sample (p < 10(-6)). Of 52 patients, 44 carried one or more TNF2 alleles. Analysis indicates that the distribution of TNF2 is best explained by assuming 100% allelic association between it and HLA-DQB1*0201 (frequency = 0.7791 +/- 0.0447). However, the number of TNF2 heterozygotes significantly exceeds expectations and measurements of linkage disequilibrium confirm that allelic associations spanning the DQ and TNF regions are strongly maintained in CD. Taken together, these results indicate that TNF2 may have a role in the pathogenesis of CD; however, since it is not an independent association, the possibility that TNF2 constitutes a passive component of the CD haplotype cannot be excluded.
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PMID:TNF2, a polymorphism of the tumour necrosis-alpha gene promoter, is a component of the celiac disease major histocompatibility complex haplotype. 881 55


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