[Are cytokines mediators in the development of insulin-dependent diabetes mellitus?].
Explore the source record for details and available documents.
Animals↗
Biomedical subjects
S Sandler
Publications and source records attributed to S Sandler.
Interleukin-1 beta induces nitric oxide production and inhibits the activity of aconitase without decreasing glucose oxidation rates in isolated mouse pancreatic islets.
The aim of this investigation was to further characterize the process of interleukin-1 beta (IL-1 beta) induced nitric oxide production in isolated pancreatic islets. It was found that both IL-1 beta and nitroprusside increased islet nitrite production. This effect was paralleled by inhibition of islet aconitase activity and glucose oxidation rates. Neither trifluoroperazinen or aminopterin could prevent the IL-1 beta induced increase in nitrite production, aconitase inhibition and decrease in glucose oxidation rates. In a second series of experiments, isolated mouse pancreatic islets were exposed to IL-1 beta for 24 h and subsequently used for nitrite production, aconitase activity and glucose oxidation determinations. The islets responded to IL-1 beta with an increased nitrite production and a decreased activity of aconitase, whereas the islet glucose oxidation rates were not decreased. It is concluded that IL-1 beta in both rat and mouse islets induces nitric oxide formation and that this induction leads to the inhibition of the Krebs cycle enzyme aconitase. In rat islets this probably leads to an inhibited insulin secretion, whereas IL-1 beta in mouse islets suppresses insulin secretion by a non-mitochondrial mechanism.
Aconitate Hydratase↗
Role of infiltrating T cells for impaired glucose metabolism in pancreatic islets isolated from non-obese diabetic mice.
Pancreatic islets isolated from non-obese diabetic (NOD) mice, all of which have insulitis, exhibit an impaired glucose metabolism. In order to investigate the role of infiltrating lymphocytes for this altered metabolism, we injected 12- to 13-week-old female NOD mice with monoclonal antibodies directed against either the alpha beta-T cell receptor, CD4+ or CD8+ T cells. Control NOD mice were injected with normal rat IgG or with the vehicle (phosphate buffered saline) alone. Injection of the three different monoclonal antibodies markedly reduced the mononuclear cell infiltration. An intravenous glucose tolerance test showed no differences between the groups. Islet insulin release in response to glucose was similar in all groups. In contrast, islets isolated from the control NOD mice with insulitis showed a high basal (1.7 mmol/l glucose) glucose oxidation rate and a small increase in the glucose oxidation rate in response to a high glucose concentration (16.7 mmol/l glucose). The monoclonal antibodies counteracted the elevated basal glucose oxidation rate of the islets. Parallel studies of stimulated mononuclear cells suggested that the contribution of glucose oxidized by islet-infiltrating lymphocytes could only partially explain the observed alterations in NOD mouse islet metabolism. Culture of islets obtained from NOD mice in the presence of the cytokine interleukin-1 beta induced a similar pattern of glucose metabolism as seen earlier in IgG or phosphate-buffered saline treated control NOD mice. In conclusion, alterations in the glucose oxidation rates seem to be an early sign of disturbance in islets isolated from NOD mice. These early alterations in glucose metabolism can be reversed in vivo by monoclonal antibodies directed against effector lymphocytes.(ABSTRACT TRUNCATED AT 250 WORDS)
Animals↗
Induction of intercellular adhesion molecule-1 (CD54) on isolated mouse pancreatic beta cells by inflammatory cytokines.
Insulin-dependent diabetes mellitus (IDDM) results from a T cell-dependent autoimmune destruction of insulin-producing pancreatic beta cells. In the present study, expression of adhesion molecule ICAM-1 (CD54) on pancreatic beta cells was studied in normal, obese hyperglycemic (ob/ob), and nonobese diabetic (NOD) mice. Freshly isolated pancreatic beta cells from ob/ob mice did not express ICAM-1, but treatment of the cells with IL-1-beta, TNF-alpha, or INF-gamma strongly induced its expression as measured by immunofluorescence flow cytometry. The cytokines acted in a dose- and time-dependent manner. Maximal induction by either cytokine occurred at 24 hr and thereafter expression decreased, except for INF-gamma. Immunoprecipitation from IL-1-beta-treated beta cells demonstrated a cell-surface glycoprotein with an apparent molecular weight of 95 kDa. ICAM-1 expression was undetectable on pancreatic beta cells of normal and ob/ob mice as measured by immunohistochemistry. In NOD mice at different ages (1 to 6 months) ICAM-1 was also undetectable on beta cells, in contrast to the strong expression on infiltrating mononuclear cells. The present study indicates that mouse pancreatic beta cells, under certain conditions, can express ICAM-1.
Animals↗
Adaptive response in beta-cell function in pancreatic islets isolated from partially pancreatectomized rats.
Before clinical onset of insulin-dependent diabetes mellitus a decreasing pancreatic beta-cell mass maintains glucose homeostasis. We currently aimed to study the function of pancreatic islets isolated 2 weeks after a 60% partial pancreatectomy (P) or after a sham operation (S) on adult rats. Experiments on the islets were subsequently performed acutely (day 0) and after 1 week (day 7) of tissue culture in medium RPMI 1640 (11.1 mM glucose) + 10% calf serum. There was no difference in the body weight 2 weeks after surgery. The pancreatic remnant weight of the P rats was 35% less than the pancreatic weight in the S rats. The islet DNA content was 25% higher in the islets of the P rats on day 0, indicating a stimulated islet growth. However, this difference did not remain after culture for 7 days. Islet proinsulin mRNA content and (pro)insulin biosynthesis rates were slightly increased in the islets of P rats on day 0, which could be due to the increased islet mass. The islet insulin content was not different on day 0, but was higher after culture in the islets of the P rats. The islet rates of glucose oxidation and insulin release were markedly higher in the P rats on day 0, suggesting a selective effect on these processes. A higher glucose oxidation rate was, however, not evident on day 7. The relative fraction of insulin-positive cells was slightly lowered in the islets of the P rats on day 0.(ABSTRACT TRUNCATED AT 250 WORDS)
Adaptation, Physiological↗
Dissociation between the blood flow response of transplanted pancreatic islets and that of the implantation organ.
The aim of this study was to investigate if the blood flow of transplanted islets is affected by the implantation organ or regulated by the grafted islets themselves. For this purpose adult rats were partially depancreatized and islets were isolated from the excised pancreatic tissue, maintained in tissue culture for 7 days, and subsequently 500 islets were implanted into the same animal beneath the renal capsule. Four weeks after transplantation, the rats were given an i.v. injection of either saline or furosemide (7.5 mg/kg body weight). Fifteen minutes later the blood perfusion of the whole left kidney and its islet grafts were measured separately with a microsphere technique. Also, the blood flow values of the pancreatic remnant were determined. Rats that were partially pancreatectomized and transplanted showed a decreased whole pancreatic blood flow in the pancreatic remnant after furosemide injection, whereas the blood flow to the islets was not significantly affected. Furosemide also increased the blood flow to the kidney but had no effect on the blood perfusion of the pancreatic islets grafted into the same kidney. These results suggest that the blood flow of an islet graft does not necessarily change in concert with the blood flow of the implantation organ. This may reflect differences in the blood flow regulation between the grafted islets and the implantation organ. In addition, it could be that the vascular system developing in the transplanted islets originates from either the islets or the kidney capsule, rather than from the kidney parenchyma. This may account for a different blood flow regulation.
Animals↗
The blood perfusion of transplanted pancreatic islets--evidence of a maturation of the blood-flow response to D-glucose with time after implantation.
Explore the source record for details and available documents.
Adrenal Glands↗
Alloxan, but not streptozotocin, increases blood perfusion of pancreatic islets in rats.
It has recently been shown that selective B-cell toxins alloxan and streptozotocin (STZ) possess marked effects also on the vascular system. To evaluate to what extent changes in blood perfusion of islets induced by alloxan or STZ could be of importance for diabetogenic action of these compounds, we first investigated acute effects of alloxan (75 mg/kg body wt iv) and STZ (40 mg/kg body wt iv) on both whole pancreatic blood flow (PBF) and islet blood flow (IBF) in adult rats. Alloxan caused a marked increase in IBF, which was most pronounced 3 min after administration and remained for 30 min. PBF, however, was decreased 3 min after alloxan administration but was similar to that of control animals from 10 min and onward. These two opposite effects on IBF and PBF caused the fraction of whole PBF diverted through islets to increase from approximately 10 to 50%. Pretreatment with glucose (2 g/kg body wt iv), indomethacin (3.5 mg/kg body wt iv), dimethyl sulfoxide (10 ml/kg body wt ip of a 33% solution), superoxide dismutase (SOD, 1,000 kU/kg body wt iv), NG-methyl-L-arginine (30 mg/kg body wt iv), theophylline (7 mg/kg body wt iv), or terbutaline (1 mg/kg body wt iv) failed to affect stimulation of IBF by alloxan observed at 3 min. SOD was found to exert a marked stimulation of IBF both when given alone and together with alloxan. Alloxan increased IBF and decreased PBF also in a syngeneic pancreaticoduodenal graft in rats but did not affect flow distribution in a perfused pancreas-duodenum preparation.(ABSTRACT TRUNCATED AT 250 WORDS)
Alloxan↗
Interleukin-1 beta increases the activity of superoxide dismutase in rat pancreatic islets.
The suppressive effects of interleukin-1 beta (IL-1 beta) on the function of pancreatic islets may be related to induction of gene transcription and protein synthesis. Presently, the effects of human recombinant IL-1 beta (rIL-1 beta) on the activities of superoxide dismutase (SOD) and the expression of corresponding genes were studied in rat pancreatic islets. Islets that were exposed to rIL-1 beta for 48 h showed a 2.6-fold greater activity of mitochondrial manganese containing SOD (MnSOD) than control islets. The cytosolic copper- and zinc-containing SOD (CuZnSOD) was, however, less affected by rIL-1 beta. Also, brief exposure of the islets to rIL-beta induced an increase in SOD activities. Hence, 12 h after a 1-h exposure of the islets to rIL-1 beta, there was a 1.4-fold increase in the activity of both MnSOD and CuZnSOD. The early induction of SOD by rIL-1 beta was inhibited by an interleukin-1 receptor antagonist protein and actinomycin-D, which is a blocker of gene transcription. This suggests that the effects of rIL-1 beta on the islet SOD activities are dependent on binding to membrane receptors and activation of gene transcription. Northern blot analysis showed a 4-fold increase in islet MnSOD mRNA content after a 90-min incubation and a 10-fold increase after a 180-min incubation with rIL-1 beta. Thus, the enhanced MnSOD activity in the islets reflects increased gene expression. To evaluate a possible role for free oxygen radicals as mediators of the early action of rIL-1 beta on the pancreatic B-cells, isolated islets were exposed to rIL-1 beta only or to rIL-1 beta plus various free radical scavengers. None of the scavengers, single or in combinations, could counteract the suppressive action of rIL-1 beta on islet insulin secretion. The present data suggest that rIL-1 beta induces increased activity of SOD, in particular MnSOD, in pancreatic islets. This may be due to a direct action of rIL-1 beta that is mediated by an increase in gene transcription.
Actins↗
Protection against hyperglycemia in female nonobese diabetic mice treated with 15-deoxyspergualin.
The effects of 15-deoxyspergualin (15-DS), a newly described immunosuppressive agent, have been studied on the development of diabetes in female NOD mice. 15-DS treatment was started two weeks after weaning i.e. at five weeks of age. The mice received either one daily intraperitoneal injection of 15-DS (2.5 mg/kg body weight) or saline for two weeks. The mice were then injected every third day up to eight months of age for evaluation of the diabetes incidence. In another set of experiments the mice were treated up to three months of age, whereafter islet insulin release, islet insulin content and DNA content was measured together with an evaluation of spleen cell proliferation rates. Different spleen cell subsets were studied directly after the two weeks of daily injections. In the saline group 8 out of 9 mice developed diabetes, whereas only 4 out of 11 of the 15-DS treated mice became diabetic (p < 0.05). There was no difference between the groups in islet insulin release in response to glucose, however, the islet insulin release increased after one week in culture. The 15-DS treatment did not affect the insulin or DNA content of the isolated islets or the insulin concentration in the pancreas. No detectable changes in the relative number of CD4+ and CD8+ T-cell subsets in the spleen were seen and there were no obvious differences in splenocyte proliferation rates. The histological examinations of the pancreatic glands showed gradual increasing signs of islet inflammation with age and 15-DS could apparently not prevent this.(ABSTRACT TRUNCATED AT 250 WORDS)
Age Factors↗
Role of receptor binding and gene transcription for both the stimulatory and inhibitory effects of interleukin-1 in pancreatic beta-cells.
A brief exposure of pancreatic islets to the cytokine interleukin-1 beta (IL-1 beta) induces an initial stimulatory phase, which is followed by inhibition of islet function and eventually beta-cell damage. In the present study we have investigated the effects of IRAP, a blocker of type I IL-1 receptor and actinomycin D, an inhibitor of DNA transcription, on both the stimulatory and inhibitory effects of IL-1 beta on rat pancreatic islets in vitro. The two test agents counteracted the initial stimulatory actions of IL-1 beta on both islet glucose-induced insulin release and glucose oxidation rates. Furthermore, cycloheximide, an inhibitor of protein synthesis, could also prevent the early IL-1 beta-induced stimulation of insulin release. When islets were exposed for 1 hr to IL-1 beta and studied after 12 hr, there was a 75% inhibition of glucose induced insulin release, a 50% decrease in glucose oxidation rates and a 30% decrease in (pro)insulin biosynthesis. These effects were completely counteracted by coincubation with IRAP or actinomycin D, but were not affected by coincubation with pertussis toxin. Islet exposure to IL-1 alpha also induced a 60-80% inhibition of glucose-induced insulin release after 12 hr. As observed with rIL-1 beta, IRAP was also able to block the suppressive effects of IL-1 alpha on islet function. Mouse islets exposed for 2 hr to IL-1 beta and studied after 12 hr presented a 50% decrease in the glucose-induced insulin release. This effect was completely blocked by coincubation with a rat monoclonal antibody generated against the type I mouse IL-1 receptor.(ABSTRACT TRUNCATED AT 250 WORDS)
Animals↗
Engraftment of isolated islets after syngeneic transplantation into normal and diabetic mice.
Explore the source record for details and available documents.
Animals↗
The relationship between cadaver donor interleukin 6 levels and delayed graft function in kidney transplantation.
Explore the source record for details and available documents.
Adult↗
Exposure of pancreatic islets to different alkylating agents decreases mitochondrial DNA content but only streptozotocin induces long-lasting functional impairment of B-cells.
Pancreatic B-cells exposed in vivo or in vitro to streptozotocin (SZ), the N-nitrosourea derivative of glucosamide, present a long-lasting impairment in the production and release of insulin while other cell functions are better preserved. This functional impairment is associated with a defective mitochondrial function. To further study the mechanisms behind SZ actions, mouse pancreatic islets were exposed in vitro to SZ (1.5 mM) or to different concentrations of methyl methanesulfonate (MMS; 2, 4 and 6 mM). The effect of the aglucone moiety of SZ, nitroso-N-methylurea (NMU; 2, 4 and 6 mM) was also tested. Islets were either studied immediately after exposure to the drugs (day 0) or after six days in culture following toxin treatment (day 6). On day 0 the islets showed a decrease in the NAD + NADH content, decreased glucose oxidation rates and an impaired insulin release in response to glucose. Six days after exposure to SZ there was still impaired glucose oxidation and insulin release, and decreased islet insulin mRNA and insulin content, but the NAD + NADH content was again similar to the control group. On the other hand, islets which survived for 6 days in culture following exposure to either MMS or NMU were able to regain normal B-cell function. The mouse islets exposed to SZ, NMU and MMS showed on day 6 a 30-40% decrease in the content of the mitochondrial DNA encoded cytochrome b mRNA and a 60-70% decrease in total mitochondrial DNA, as evaluated by dot and Southern blot analysis. Only SZ decreased the insulin mRNA content whereas both MMS and NMU decreased the glucagon mRNA content. As a whole, the data obtained indicate that SZ, NMU and MMS induce damage to the mitochondrial genome, and this may contribute to the B-cell dysfunction observed after SZ treatment. It is conceivable that the glucose moiety of SZ may direct the methylation to other intracellular sites besides the mitochondrial DNA, thus explaining the different functional responses of islets following exposure to SZ and NMU.
Adenine↗
Partial pancreatectomy in rats causes an impairment of the glucose-induced stimulation of pancreatic islet blood flow.
Adult rats were subjected to either a sham operation (S-rats) or a 60% partial pancreatectomy (P-rats). Both P- and S-rats were normoglycemic and normoinsulinemic after surgery. Four weeks later, the animals were injected i.v. with 1 ml of either 0.9% (w/v) saline or 30% (w/v) D-glucose, and after 5 min whole pancreatic blood flow (PBF) and islet blood flow (IBF) were measured, using a microsphere technique. In the saline-injected P-rats both PBF and IBF values were higher than in S-rats (p less than 0.001 for both values). Administration of glucose had no effects on PBF in either S- or P-rats when compared to saline-injected animals. IBF was, however, markedly increased (p less than 0.01) by glucose in S-rats in comparison with saline-injected S-rats, whilst no difference in IBF was observed between glucose- and saline-injected P-rats. The fraction of PBF diverted through the islets (fIBF) was approximately 10% in S-rats and 20% in P-rats. Glucose increased fIBF in S-rats, but had no effect in P-rats. In conclusion, in S-rats a glucose-stimulated insulin release is accompanied by an increase in IBF, but this is not observed in P-rats.
Animals↗
An interleukin-1 receptor antagonist protein protects insulin-producing beta cells against suppressive effects of interleukin-1 beta.
The cytokine interleukin-1 beta may have an important role in the autoimmune mediated damage of pancreatic Beta cells in insulin-dependent diabetes mellitus. In the present study we have investigated the effects of an interleukin-1 receptor antagonist protein, a blocker of the type I interleukin-1 receptor, on the suppressive actions of recombinant interleukin-1 beta on insulin-producing cells. Brief exposure (1-2 h) of rat and mouse pancreatic islets to 10 ng/ml recombinant interleukin-1 beta induced an 70-80% inhibition of insulin response to glucose after 12 h. These effects were completely counteracted by co-incubation with 100 ng/ml interleukin-1 receptor antagonist protein. When rat islets were cultured for 48 h in the presence of recombinant interleukin-1 beta (5 ng/ml) higher concentrations of interleukin-1 receptor antagonist protein (5000 ng/ml) were required to protect Beta-cell function. Interleukin-1 receptor antagonist protein also counteracted the inhibitory effects of recombinant interleukin-1 beta on the growth of the rat insulinoma cell line RINm5F. These data suggest that interleukin-1 receptor antagonist protein can protect insulin-producing cells from the deleterious effects of recombinant interleukin-1 beta, and that these cells possess type I interleukin-1 receptors.
Animals↗
Prolonged exposure of pancreatic islets isolated from "pre-diabetic" non-obese diabetic mice to a high glucose concentration does not impair beta-cell function.
In the early stages of Type 1 (insulin-dependent) diabetes mellitus patients present a deficient insulin response to glucose. The reasons for this defective response are unknown, but it has been suggested that it reflects a deleterious effect of excessive glucose stimulation on a reduced Beta-cell mass. Female non-obese diabetic (NOD) mice from our colony, at the age of 12-13 weeks, have a normal basal glycaemia but an impaired intravenous glucose tolerance test, insulitis and a defective insulin response to glucose. In order to characterize the potential effect of glucose on the Beta cells at that "pre-diabetic" stage, pancreatic islets were isolated from 12-13 week old female NOD mice. Immediately after isolation (day 0) the NOD islets displayed a defective insulin response to an acute stimulation with 16.7 mmol/l glucose. After seven days in culture at both 11 and 28 mmol/l glucose these islets showed an increased insulin release in response to an acute glucose stimulation. This increase was more pronounced in the islets cultured at 28 mmol/l glucose. Experiments performed in parallel, using islets obtained from a non-diabetes prone strain of mice (Naval Medical Research Institute, NMRI) showed that these islets had a similar insulin release in response to glucose both on day 0 and after seven days in culture at 11 mmol/l glucose. The insulin mRNA levels of NOD islets did not change over one week in culture at 11 or 28 mmol/l glucose, but culture at the high glucose concentration induced a decrease in the islet insulin content.(ABSTRACT TRUNCATED AT 250 WORDS)
Animals↗
Decrease in insulin-containing secretory granules and mitochondrial gene expression in mouse pancreatic islets maintained in culture following streptozotocin exposure.
We have previously described a preferential reduction in the secretory response to nutrient secretagogues in pancreatic mouse islets maintained in culture after in vitro exposure to streptozotocin (SZ). This reduction was associated with an impaired substrate metabolism at the mitochondrial level. To further clarify this issue, mouse pancreatic islets were exposed in vitro to 2.2 mM SZ for 30 min. At 4 h after SZ treatment ultrastructural changes were apparent in the endoplasmic reticulum and Golgi areas of the B-cells. However, 2 and 6 days following SZ exposure the B-cells appeared well preserved, except for a marked decrease in the number of insulin-containing secretory granules. A morphometric analysis of the B-cells 6 days after SZ exposure showed a normal B-cell size and a normal volume fraction of B-cell mitochondria. However, there was a decrease in total islet size and a 13% decrease in the volume fraction of B-cells in the islets. These mouse islets exhibited a decreased content of the mitochondrial DNA-encoded cytochrome b mRNA, as evaluated by dot-blot analysis. As a whole, the data obtained indicate that SZ treatment does not induce a decrease in the number of mitochondria or long-lasting ultrastructural damage to this organelle. However, there is a clear decrease in the cytochrome b mRNA, suggesting that SZ can induce damage to the mitochondrial DNA.
Animals↗