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

This study provides a basis for understanding the wide variations reported in the literature in IFN-gamma inducibility of class II MHC antigens on murine beta cells. Inducibility is not an intrinsic property of all mouse beta cells, but instead depends upon strain- (and tissue-) specific response modifying factors. This was demonstrated by comparison of constitutive and IFN-gamma-induced class I and class II MHC gene products on cultured islet cell monolayers. Islet cultures were established from autoimmune diabetes-prone NOD/Lt mice, diabetes-resistant NON/Lt and CBA/J mice, as well as F1 hybrids between these latter two strains and NOD/Lt. Cultures of peritoneal macrophages (M phi) from each strain were established as controls. After 3 wk of culture (with incubation in the presence or absence of IFN-gamma during the last 6 d), constitutive expression as well as IFN-gamma induction of class I MHC antigen expression was demonstrated on NOD/Lt and NON/Lt islet cells by antibody plus complement-mediated cytotoxicity. Although CBA/J islets and M phi did not maintain constitutive class I or class II antigen expression in culture in the absence of IFN-gamma, class I H-2Kk antigen was IFN-gamma inducible. Whereas IFN-gamma-induced class II I-Ak antigen on CBA/J M phi, it failed to induce this antigen on CBA/J islets. In contrast, I-A antigens were IFN-gamma inducible on NOD/Lt and NON/Lt islets and M phi. In (CBA x NOD)F1 hybrids, loss of IFN-gamma inducibility of the I-ANOD product established that suppression was mediated by a trans-acting factor from the CBA/J genome. In the course of these studies, IFN-gamma inducibility of a crossreactive occult class I-like antigen on both NOD/Lt islet cell and M phi cultures was unexpectedly detected when mAb 28-13-3 (public specificity 39, reactive with H-2Kb,f) was used as a negative control. Although not detectable by cytofluorographic analysis of freshly isolated NOD/Lt splenic leukocytes, occult antigen could be induced on NOD/Lt peritoneal macrophages (M phi) cultured for 3 d in IFN-gamma. Time course of induction showed the occult antigen to be distinct from NOD/Lt class I and II gene products. In both islet cell and M phi cultures established from (CBA x NOD)F1 hybrids, trans-suppressive factor(s) from the CBA/J genome not only suppressed IFN-gamma-induced expression of I-ANOD, but additionally suppressed occult antigen induction. Backcross of F1 to both parental strains indicated that the occult locus was on Chr 17, tightly linked to MHC.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:MHC antigen induction by interferon gamma on cultured mouse pancreatic beta cells and macrophages. Genetic analysis of strain differences and discovery of an "occult" class I-like antigen in NOD/Lt mice. 250 27

Multiple low dose streptozotocin (STZ) is believed to induce immunologically mediated islet cell necrosis. We sought to establish whether this agent also increased MHC expression, as has been reported for other diabetes models. STZ (40 mg/kg/day for 5 days) produced increased levels of both class I and II MHC products in kidney, liver, heart, and pancreas. Class I expression was induced in renal tubular cells, Kupffer cells, hepatocytes, occasional cardiac myocytes, and cells within the pancreatic islet. In contrast, class II products were increased in dendritic cells, renal tubules, and cells within the pancreatic islet. Steady state mRNA levels for class I, class II, and beta 2-microglobulin correlate closely with the level of MHC products measured by radiolabeled antibody binding, suggesting that changes in MHC expression reflect changes in gene transcription. The effect is T cell dependent and inhibitable by cyclosporine. IFN-gamma is an essential mediator of the MHC induction; administration of a neutralizing antibody blocks the increase in expression. Furthermore, this antibody attenuates the hyperglycemic response to STZ, demonstrating a pathogenic role for IFN-gamma in mediating beta cell damage. We conclude that the MHC induction observed after low dose STZ is due to immunologic mechanisms, in particular the release of lymphokines such as IFN-gamma from T cells. The release of IFN-gamma and changes in MHC expression may be relevant to the injury seen with this agent.
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PMID:Multiple low dose streptozotocin induces systemic MHC expression in mice by triggering T cells to release IFN-gamma. 252 59

Proteins of extracellular matrix undergo over time multiple reactions with glucose to form advanced glycosylation endproducts (AGEs) which are highly active in protein crosslinking, and have been implicated in tissue damage associated with aging and diabetes. A macrophage/monocyte receptor for AGE moieties mediates the uptake of AGE-modified proteins by a process that also induces cachectin/tumor necrosis factor (TNF) and IL-1 secretion. Reasoning that cytokines might regulate this AGE-receptor system, we have evaluated the effect of cachectin/TNF, IL-1, and IFN-gamma on AGE-protein processing. We report that cachectin/TNF induced a severalfold enhancement of binding, endocytosis, and degradation of AGE-BSA by both murine peritoneal macrophages and human blood monocytes in vitro, and that cachectin/TNF enhanced the rate of disappearance of AGE-modified red blood cells in vivo. IL-1 and IFN-gamma alone did not increase AGE processing, but IFN-gamma consistently enhanced cachectin/TNF-induced changes in AGE-receptor kinetics. Similar effects were induced by AGE-BSA and FFI-BSA, a chemically synthesized AGE, when used as macrophage stimulants, possibly via cachectin/TNF induction. All upregulatory responses were blocked by anticachectin/TNF monoclonal antibody. These data suggest that AGE-induced cachectin/TNF, in addition to influencing tissue regeneration and remodelling, may also normally regulate the disposal of tissue damaging AGE-proteins through an autocrine upregulation.
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PMID:Macrophage/monocyte receptor for nonenzymatically glycosylated protein is upregulated by cachectin/tumor necrosis factor. 255 47

To explore the role of the lymphokine, IFN-gamma, in the development of autoimmune-mediated insulin-dependent diabetes, we examined the effects of systemically administered IFN-gamma on the clinical features and pancreatic immunohistology of CBA mice made diabetic with multiple low doses of the pancreatic islet beta-cell toxin, streptozotocin. Mice given streptozotocin and IFN-gamma were significantly more hyperglycemic than those given streptozotocin alone and had significantly decreased body weight. Mice given IFN-gamma alone did not differ in glycemia or weight from vehicle-injected mice. On day 11, Ia proteins were detected on islet cells from mice given streptozotocin and their expression was potentiated by IFN-gamma; they could not be detected on islet cells from mice given IFN-gamma alone or vehicle. H-2K protein expression was increased on islet cells from mice given streptozotocin and was potentiated by IFN-gamma. IFN-gamma alone also increased H-2K protein expression on islet cells compared with vehicle-treated mice. These findings show that IFN-gamma enhances the severity of diabetes in mice given multiple-low doses of streptozotocin, in association with enhanced expression of Ia and H-2K proteins on islet cells. They indicate an important role for IFN-gamma in amplifying the autoimmune process leading to beta-cell destruction in diabetes. The ability of IFN-gamma to worsen autoimmune disease has implications for its use in man.
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PMID:IFN-gamma induces islet cell MHC antigens and enhances autoimmune, streptozotocin-induced diabetes in the mouse. 296 59

An assay was developed to detect the cytotoxic effects of cytokines on rat pancreatic islet cells in monolayer culture. Cell lysis was detected by a 51Cr-release assay after 4 days of incubation with various cytokines. When tested alone, murine (rat and mouse) interferon-gamma (mIFN-gamma) produced a small dose-dependent lysis of islet cells; human IFN-gamma, mouse IFN-alpha/beta, interleukins 1 and 2 (IL-1 and IL-2), tumor necrosis factor (TNF), and lymphotoxin (LT) were inactive. When added together, the following combinations of cytokines showed synergistic cytotoxic effects: TNF (or LT) plus IL-1, TNF (or LT) plus mIFN-gamma, and IL-1 plus mIFN-gamma. These results indicate that the cytokine products of mononuclear cells of the immune system, IFN-gamma, TNF, LT, and IL-1 have strong synergistic cytotoxic effects on islet cells and therefore may act as direct chemical mediators of islet beta-cell destruction in type I (insulin-dependent) diabetes.
Diabetes 1988 Jan
PMID:Destruction of rat islet cell monolayers by cytokines. Synergistic interactions of interferon-gamma, tumor necrosis factor, lymphotoxin, and interleukin 1. 312 15

We have previously reported that the cytokines IFN-gamma and TNF-alpha each upregulate the expression of class I MHC proteins and, in combination, induce the expression of class II MHC proteins on pancreatic islet cells. IFN-gamma and TNF-alpha are therefore implicated in the immunologic destruction of beta-cells in insulin-dependent diabetes mellitus. The objective of the present study was to define the effects of IFN-gamma and TNF-alpha on the function and viability of murine pancreatic islet beta-cells in vitro. Exposure of islets for 3 days to 200 U/ml of either IFN-gamma or TNF-alpha did not affect glucose-stimulated insulin release, but at higher concentrations (2000 U/ml) of either cytokine there was significant inhibition of glucose-stimulated insulin release. In combination, IFN-gamma and TNF-alpha each at 200 U/ml caused significant inhibition of glucose-stimulated insulin release; at 2000 U/ml glucose-stimulated insulin release was abolished. In time-course experiments, glucose-stimulated insulin release from islets exposed to IFN-gamma and TNF-alpha each at 1000 U/ml was significantly increased at 4-h (twofold increase compared with control islets), decreased back to control levels at 18 h, significantly inhibited by 24 h (threefold decrease compared with control islets), and completely abolished by 48 h. The progressive impairment of beta-cell function mediated by IFN-gamma plus TNF-alpha was associated with morphologic derangement of the islets that were almost totally disintegrated by day 6 of exposure to the cytokines. At day 6, insulin content of the islets was significantly reduced by exposure to TNF-alpha but not IFN-gamma. The combination of IFN-gamma and TNF-alpha resulted in a further dose-dependent depletion in insulin content compared with TNF-alpha alone. The synergistic functional and cytotoxic effects of IFN-gamma and TNF-alpha are consistent with a direct role for these cytokines in the destruction of beta-cells in insulin-dependent diabetes.
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PMID:IFN-gamma and tumor necrosis factor-alpha. Cytotoxicity to murine islets of Langerhans. 313 56

The occurrence of HLA Class II expression by thyroid (and other endocrine) epithelia in autoimmune diseases suggests that these cells may facilitate their own destruction by immunogenically presenting autoantigens. This is supported by the findings that Class II+ thyrocytes can specifically stimulate virus-specific and autoreactive T cell clones, and that Class II expression by thyrocytes correlates with the occurrence of thyroid autoantibodies. A variety of factors may contribute to the regulation of Class II expression by thyrocytes: this is induced by interferon (IFN-gamma), and is enhanced by thyroid stimulating hormone (TSH) and by tumour necrosis factor (TNF). Conversely, epidermal growth factor (EGF) suppresses the induction of Class II in thyrocytes. This complex regulation is reflected in differences in HLA-D subregion expression between patients (DR greater than DP greater than DQ). The immune-based mechanisms of thyrocyte Class II regulation are clearly applicable to the on-going disease in an infiltrated thyroid, but the possibility of nonimmune Class II induction deserves attention, particularly in identifying factors which might contribute to the initial autoimmune attack. The possible involvement of such mechanisms in autoimmunity is supported by findings in Type I diabetes in which Class II+ islet beta cells can be found in the absence of infiltration. Further evidence is provided by the observation that a proportion of thyrocytes transformed with SV40 DNA constitutively express Class II molecules. Finally, the 'activated' state of capillary endothelial cells in organs subject to autoimmune attack suggests that they may play an important role in facilitating the autoreactive infiltration of the tissues.
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PMID:Thyrocyte HLA class II expression and regulation in relation to thyroid autoimmunity. 349 11

Oral administration of autoantigens suppresses development of autoimmunity in several animal models, and is being tested in clinical trials in patients with autoimmune diseases such as multiple sclerosis and rheumatoid arthritis. Non-obese diabetic (NOD) mice spontaneously develop insulin-dependent diabetes mellitus at 15 to 20 weeks of age, after mononuclear cell (MNC) infiltration of the pancreatic islets of Langerhans and destruction of insulin-producing beta cells. We have previously shown that oral administration of insulin suppresses insulitis and development of diabetes in the NOD mouse. Oral insulin has no metabolic effect on blood glucose. Oral insulin mediates its effect through a T cell-dependent mechanism as shown by adoptive transfer and T cell depletion experiments, but the mechanisms responsible have not been fully explored. We now report a serial analysis of the cells and cytokines associated with development of diabetes in NOD mice, and contrast this with the findings in animals fed equine insulin or a control protein (ovalbumin). Animals were fed 1 mg twice a week for 5 weeks, beginning at 5 weeks of age. Marked insulitis in naive or ovalbumin-fed NOD mice occurred at 10 weeks, at which time a dense peri-islet and intra-islet MNC infiltration was observed. Immunohistological studies using monoclonal antibodies showed that infiltrating MNC consisted mainly of CD4+ T cells ( > 75% of leukocytes) plus smaller numbers of macrophages and CD8+ T cells. These cells displayed evidence of immune activation with expression of receptors for interleukin-2 (IL-2R) plus Th1 cytokines; dense labeling for IFN-gamma and tumor necrosis factor-alpha, plus lesser amounts of IL-2, was observed. MNC lacked labeling for IL-4, IL-10, prostaglandin-E, or transforming growth factor-beta. By contrast, at 10 weeks, pancreatic tissues from NOD mice fed insulin showed considerably less insulitis, and the residual MNC, although still largely CD4+ T cells plus macrophages, showed dense labeling for IL-4, IL-10, prostaglandin-E, and transforming growth factor-beta and an absence of IL-2, IFN-gamma or tumor necrosis factor-alpha Taken together with our previous findings, these data indicate that oral administration of insulin affects the development of diabetes in NOD mice through the generation of cells that elaborate immunoregulatory cytokines within the target organ and shift the balance from a Th1 to a Th2 pattern of cytokine expression.
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PMID:Suppression of insulitis in non-obese diabetic (NOD) mice by oral insulin administration is associated with selective expression of interleukin-4 and -10, transforming growth factor-beta, and prostaglandin-E. 748 82

Cytokines have been proposed as inducers of beta-cell damage in human insulin-dependent diabetes mellitus via the generation of nitric oxide (NO). This concept is mostly based on data obtained in rodent pancreatic islets using heterologous cytokine preparations. The present study examined whether exposure of human pancreatic islets to different cytokines induces NO and impairs beta-cell function. Islets from 30 human pancreata were exposed for 6-144 h to the following human recombinant cytokines, alone or in combination: IFN-gamma (1,000 U/ml), TNF-alpha (1,000 U/ml), IL-6 (25 U/ml), and IL-1 beta (50 U/ml). After 48 h, none of the cytokines alone increased islet nitrite production, but IFN-gamma induced a 20% decrease in glucose-induced insulin release. Combinations of cytokines, notably IL-1 beta plus IFN-gamma plus TNF-alpha, induced increased expression of inducible NO synthase mRNA after 6 h and resulted in a fivefold increase in medium nitrite accumulation after 48 h. These cytokines did not impair glucose metabolism or insulin release in response to 16.7 mM glucose, but there was an 80% decrease in islet insulin content. An exposure of 144 h to IL-1 beta plus IFN-gamma plus TNF-alpha increased NO production and decreased both glucose-induced insulin release and insulin content. Inhibitors of NO generation, aminoguanidine or NG-nitro-L-arginine, blocked this cytokine-induced NO generation, but did not prevent the suppressive effect of IL-1 beta plus IFN-gamma plus TNF-alpha on insulin release and content. In conclusion, isolated human islets are more resistant to the suppressive effects of cytokines and NO than isolated rodent islets. Moreover, the present study suggests that NO is not the major mediator of cytokine effects on human islets.
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PMID:Cytokines suppress human islet function irrespective of their effects on nitric oxide generation. 751 90

Increased blood flow and vascular permeability of early diabetes have been associated with increased nitric oxide formation in diabetic rats, but the specific nitric oxide synthase responsible is unknown. We examined the modulation of the induction and activity of the inducible NOS isoform by high glucose concentration in a murine macrophage cell line, RAW 264.7, and murine glomerular mesangial cells. Culturing both cell types in high glucose concentration led to significant increases in nitrite production and the mRNA encoding iNOS upon stimulation with LPS plus interferon-gamma, as compared with normal glucose concentration. High glucose also modestly enhanced LPS/IFN-gamma-induced stimulation of the iNOS promoter in transient transfection experiments in mesangial cells. Protein kinase C activation led to enhanced mRNA expression of iNOS, and inhibitors of protein kinase C blocked nitrite accumulation in mesangial cells. These findings suggest that high glucose in combination with stimulation by LPS plus IFN-gamma enhances iNOS expression, and protein kinase C activation may be playing a role in this enhancement.
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PMID:Enhanced expression of inducible nitric oxide synthase in murine macrophages and glomerular mesangial cells by elevated glucose levels: possible mediation via protein kinase C. 753 75


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