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J Nerup

Publications and source records attributed to J Nerup.

At least 163 records · Page 9Linked to original sources
PubMed1990

Intra-peritoneal administration of interleukin-1 beta induces impaired insulin release from the perfused rat pancreas.

Previous studies have demonstrated a stimulatory effect of interleukin-1 beta (IL-1 beta) on insulin and glucagon release from the perfused rat pancreas, accompanied by selective lysis of 20% of beta-cells as assessed by electronmicroscopy. However, we have not observed an inhibitory action of IL-1 beta on insulin release from the perfused pancreas as shown for isolated islets. To test whether periodical exposure of the endocrine pancreas to circulating IL-1 beta in vivo affects insulin release from the intact perfused pancreas, rats were treated with daily intraperitoneal injections of 4 micrograms IL-1 beta/kg or saline for 5 days. On day 5 the pancreata were isolated 2 h after the last injection and perfused from 0 to 72 min with 11 mmol/l D-glucose and from 72 to 84 min with 20 mmol/l D-glucose. Saline or IL-1 beta was added from 12 to 72 min. In pancreata from animals pre-treated with IL-1 beta glucose-stimulated as well as IL-1 beta potentiated glucose-stimulated insulin release was almost completely abolished. Furthermore, a decline in insulin release was observed at 11 mmol/l D-glucose, in contrast to an increase in insulin release in controls. The total extractable insulin content in pancreata from IL-1 beta pre-treated rats was higher than in pancreata from saline-treated controls. In contrast to the inhibitory effect of in vivo administration of IL-1 beta on beta-cell function glucagon secretion was stimulated. These observations suggest that circulating IL-1 beta is an important modulator of alpha- and beta-cell secretory function in vivo and that IL-1 beta should be considered a contributory pathogenetic factor in the development of insulin-dependent (type 1) diabetes mellitus.

Animals↗
PubMed1989

Diabetic ketoacidosis in Denmark: epidemiology, incidence rates, precipitating factors and mortality rates.

The epidemiology of uncontrolled diabetes mellitus was studied in an 11.2% sample of the Danish population (574,696 inhabitants) during a 24-month period. Some 175 admissions in ketoacidosis (heavy ketonuria and plasma bicarbonate below 21 mmol/l) were recorded. Based on prevalence rates from a socio-economically and ethnically comparable Danish county, the annual incidence rate was calculated to be 0.045 per diabetic. The incidence rate of moderate and severe episodes (bicarbonate less than 16 mmol/l) was 0.032 and of severe episodes only (bicarbonate less than 10 mmol/l) 0.017 per diabetic. The major risk group was female teenagers. The total annual frequency of recurrence was 8.7%: 48% of the male episodes were ketoacidosis (DKA) associated with onset of diabetes, against 30% of the female episodes (P = 0.02). All Danish diabetics were at the time of the survey (1978-79) treated with conventional insulin treatment. Annual incidence rate in these established diabetics was 0.028, i.e. three to five times less than reported during treatment with continuous subcutaneous insulin infusion. Mortality of DKA was low, 3.4%, and dependent upon age and precipitating factor but not upon the degree of acidosis. The overall annual mortality rate was 1.5 per 100 diabetics.

Adolescent↗
PubMed1989

Characterization of PPD-specific T-cell lines generated in type I (insulin-dependent) diabetic and healthy individuals.

The particular susceptibility to insulin-dependent diabetes mellitus (IDDM) conferred by HLA-DR3,4 heterozygosity has been suggested to be an effect of transcomplementation of HLA class II molecules. To test this hypothesis of special IDDM-specific hybrid determinants and to evaluate the T-cell repertoire towards a specific antigen in IDDM patients we generated a total of 352 PPD-specific T-cell lines by the soft-agar cloning technique and studied their restriction by HLA class II molecules. Of these lines, 227 were from nine IDDM patients, of whom six were DR3,4 heterozygotes, and 125 from 10 healthy controls. Forty-six T-cell lines elicited specific responses in at least two experiments and in addition to T-cell lines demonstrating class-II-restricted PPD specificity, lines with an alloreactivity occurred. HLA-DQ-restricted PPD-specific T-cell lines were not identified and a possible DP restriction (DPw2) was only observed with one line. These data indicate that PPD is preferentially presented to T cells in the context of HLA-DR/Dw. Presentation of PPD by hybrid molecules in IDDM patients or by IDDM-specific class II epitopes recognized by the T-cell lines was not demonstrated. By restriction fragment length polymorphism analysis using a probe for the joining region of the T-cell receptor gamma gene, T-cell lines generated by the soft-agar cloning technique were found to be oligoclonal. It is concluded that soft-agar cloning should be followed by subsequent limiting dilution in order to assure monoclonality. Different preparations of antigen-presenting cells (APC) were tested. In several cases the T-cell lines were not able to respond to PPD presented by Epstein-Barr-virus-transformed lymphoblastoid cell lines (LCL). It was demonstrated that lipopolysaccharides (LPS) of E. coli potently reduce the proliferative response of antigen-specific and alloreactive T cells when T-cell-depleted peripheral blood mononuclear cells (E- cells) were used as APC, whereas only limited inhibition was observed when LCL were used as APC in the presence of LPS. This effect of LPS is suggested to be mediated by increased prostaglandin secretion by monocytes among the E- cells since indomethacin abolished the effect of LPS. This observation may have implications for T-cell cloning procedures since we have found that most commercially available culture media are heavily contaminated with endotoxin.

Antigen-Presenting Cells↗
PubMed1989

Genetically determined differences in newborn rat islet sensitivity to interleukin-1 in vitro: no association with the diabetes prone phenotype in the BB-rat.

This study was designed to investigate whether the genetic predisposition to insulin-dependent diabetes mellitus (IDDM) might be caused by an inherited increased sensitivity of the pancreatic B-cells to immune effector molecules e.g. the monokine interleukin 1 (IL-1), which is selectively cytotoxic to B-cells in vitro. Islets of Langerhans isolated from newborn diabetes prone and diabetes resistant Bio-Breeding rats, as well as from the inbred non-diabetic rat strains Wistar Furth, Brown-Norway and Lewis-Scripps were exposed to 0-1000 ng/l [corrected] of recombinant human IL-1 beta for 7 days. Strain-related differences in the sensitivity to IL-1 were studied by comparing the dose-responses of insulin release at 11 mmol/l glucose and islet light microscopic morphology to varying concentrations of IL-1. Statistical analyses showed a significant impact of strain on B-cell sensitivity to IL-1, Brown-Norway islets being relatively resistant to the action of IL-1. However, the the diabetes prone islets were not more sensitive to the cytotoxic effect of IL-1 than the non-diabetic control strain islets. We conclude that genetic differences in the response to IL-1 exist in vitro, but that this phenomenon is unrelated to the propensity to develop IDDM.

Animals↗
PubMed1989

Interleukin 1 induces new protein formation in isolated rat islets of Langerhans.

It is hypothesized that interleukin 1 induces toxic free radical formation in pancreatic beta-cells leading to beta-cell degeneration and destruction. Therefore, isolated rat pancreatic islets were examined for interleukin 1 and heat shock induced proteins. Afer exposure to human interleukin 1 beta (0.015 to 10 micrograms/1) or heat (40 degrees C) for up to 24 h, islets were labelled with 35S-methionine and solubilized. Islets proteins were analysed by SDS-polyacrylamide gel electrophoresis. By autoradiography it was shown that both interleukin 1 and heat exposure induced the formation of a 70 kD protein. Further, interleukin 1 induced the formation of two proteins of 32 and 80 kD, respectively, which was not seen after heat exposure. Possibly, the 70 kD protein is a member of the heat shock protein 76 family, participating in unspecific cellular defence and maybe free radical scavenging. Other candidates are the superoxide radical scavenging enzyme manganous superoxidedismutase, MHC class II molecules, and heme oxygenase.

Animals↗
PubMed1989

Modulation of calcium flux influences interleukin 1 beta effects on insulin release from isolated islets of Langerhans.

The controlled flux of calcium across the cell membrane is intimately linked to the release of insulin from pancreatic beta-cells, but the uncontrolled influx of calcium is a common final denominator of cell death. Because interleukin 1 has been shown to be cytotoxic to beta-cells in isolated rat islets of Langerhans and since interleukin 1 has a calcium ionophore effect on other cell types, this study was designed to test whether alterations of the calcium flux across the beta-cell membrane would influence the effects of interleukin 1 on isolated rat and mouse islets. Further, the cytosolic free Ca2+ concentration was measured by the fura-2 method in rat islets during acute interleukin 1 exposure. Treatment with 10 mumol/l of verapamil (a potent blocker of the voltage-dependent calcium channel) tended to suppress the inhibitory effect of interleukin 1 on insulin release from rat islets, suggesting protection against cytotoxicity. Conversely, a stimulatory effect of interleukin 1 on mouse islets during 6 days of exposure to interleukin 1 was turned into inhibition by high extracellular calcium concentration. Interleukin 1 did not have any acute effect on cytosolic free Ca2+ concentration. In conclusion, interleukin 1 has no specific calcium ionophore effect on beta-cells, but alterations of the calcium flux across the beta-cell membrane influence the functional effects of interleukin 1, suggesting interference with cell function and toxicity, which would likely be accompanied by an uncontrolled influx of calcium.

Animals↗
PubMed1989

Interaction of beta-cell activity and IL-1 concentration and exposure time in isolated rat islets of Langerhans.

This study was designed to test the hypothesis that target-cell activity influences the degree and time course of interleukin 1 beta (IL-1 beta)-mediated beta-cell impairment in vitro. Functional and morphological studies were performed in cultured newborn rat islets of Langerhans exposed from 6 h to 6 days to 50-2000 ng/L recombinant human IL-1 beta. Beta-Cell activity was modulated by glucose and nonglucose agents (15 mM L-leucine and 10 microM of long-acting somatostatin analogue SMS 201-995). In 11 mM glucose, 2000 ng/L of IL-1 beta caused inhibition of insulin release after approximately 6 h of exposure to IL-1 beta; in 3.3 mM glucose culture, onset of inhibition was delayed by this IL-1 beta concentration until after 48 h of exposure. Similarly, stimulation and suppression of beta-cell function with L-leucine and SMS 201-995, respectively, resulted in acceleration and delay of IL-1 beta-mediated inhibition. The dose-response curve of the IL-1 beta effect was shifted left- and rightward during high and low beta-cell activity, respectively. In analogy, increasing IL-1 beta concentration, exposure time, and beta-cell activity resulted in increasing islet disintegration. Thus, the resting beta-cell is more resistant to IL-1 beta-mediated impairment than the working beta-cell.

Animals↗
PubMed1988

The susceptibility to insulin-dependent diabetes mellitus is associated with C4 allotypes independently of the association with HLA-DQ alleles in HLA-DR3,4 heterozygotes.

In the genetically homogeneous Danish population, 27 HLA-DR3,4 heterozygous patients with insulin-dependent diabetes mellitus (IDDM) and 19 DR3,4 heterozygous controls without family history of IDDM were investigated for HLA-region markers and Gm and Km immunoglobulin allotypes. The aim was to define susceptibility factors for IDDM development other than HLA-DR using a number of techniques: lymphocytotoxicity (HLA-DR and DQ antigens), cellular methods (Dw and DP typing), restriction fragment length polymorphism (DQ alleles), electrophoresis and immunofixation (BF and C4 allotypes), and passive hemagglutination inhibition (Gm and Km immunoglobulin allotypes). The complement allotype C4A3 and the HLA-DQw8 (DQw3.2) antigen were found in all of the patients, whereas this was the case for only 8 of the 19 controls (P = 6 x 10(-6)): five lacked C4A3, five others lacked DQw8, and one of the controls lacked both of these factors. Fourteen of the patients had the complement allotype C4B3 versus three of the controls (P = 0.01). Previously reported family studies suggest that these alleles are part of the following haplotype: B15, BFS, C4A3, C4B3, DR4, Dw4, DQw8, and these factors were found together in ten of the patients versus one of the controls (P = 0.01). The markers usually associated with DR3 did not show significant differences between IDDM patients and controls, and the non-HLA markers studied showed no significant deviation from what was expected. In addition to the susceptibility factor DQw8, the study suggests the existence of susceptibility genes for IDDM near the complement C4 genes on DR4-carrying haplotypes.(ABSTRACT TRUNCATED AT 250 WORDS)

Complement C4↗
PubMed1988

Endotoxin-stimulated human monocyte secretion of interleukin 1, tumour necrosis factor alpha, and prostaglandin E2 shows stable interindividual differences.

The secretions of interleukin 1 (IL-1), tumour necrosis factor alpha (TNF), and prostaglandin E2 (PGE2) of low-dose E. coli lipopolysaccharide (LPS)-stimulated human monocytes (M phi) were investigated in an endotoxin (ET)-free milieu (less than 1.6 pg LPS/ml). Human M phi cultures from nine healthy men were stimulated with 0, 12.5-500, and 250,000 pg LPS/ml as measured by a very sensitive Limulus test. The IL-1 activity was tested by the mouse costimulatory thymocyte (LAF) assay, which was thoroughly standardized and characterized (interassay variation 22-24%, intra-assay variation 3-7%). Spontaneous M phi secretions of IL-1, TNF, and PGE2 were negligible, but 12.5 pg LPS/ml significantly stimulated the secretions of these M phi products and the monokine responses to 500 and 250,000 pg LPS/ml were almost in the same range. It was demonstrated that the secretions of IL-1-TNF and TNF-PGE2 were strongly correlated. Pronounced interindividual differences in LPS responsiveness were demonstrated, and two low-responders, one of whom was HLA-DR1,2-positive, were identified. Three first-degree relatives of the DR1,2-positive low-responder had similar low responses. Furthermore, M phi cultures were prepared weekly for 4 weeks from four HLA-DR different men and the only DR2,2 homozygous individual had low monokine responses. In conclusion, stable interindividual differences in in vitro monokine and PGE2 secretions of LPS-stimulated M phi were demonstrated. It is suggested that HLA-DR2-positive individuals may be low responders.

Biological Products↗
PubMed1988

Interleukin-1 potentiates glucose stimulated insulin release in the isolated perfused pancreas.

The acute effects of recombinant human interleukin-1 beta (rIL-1) on basal and glucose-stimulated insulin release were investigated in the isolated perfused pancreas. At a concentration of 20 micrograms/l rIL-1 had no effect on basal insulin release, but increased the total amount of insulin released during first and second phase insulin release in response to 20 mmol/l D-glucose in the rat pancreas (P less than 0.05). In addition, 26 micrograms/l of rIL-1 potentiated insulin release in response to square wave infusions of stimulatory concentrations of glucose (11 mmol/l) in the porcine pancreas. We hypothesize that IL-1 in the systemic circulation may affect B cell function in vivo.

Animals↗
PubMed1988

The bimodal effect of interleukin 1 on rat pancreatic beta-cells--stimulation followed by inhibition--depends upon dose, duration of exposure, and ambient glucose concentration.

To investigate the hypothesis that interleukin 1 initially stimulates and then suppresses beta-cell function and that this sequential effect is directly related to interleukin 1 dose, duration of exposure, and ambient glucose concentration, insulin release was measured from cultured newborn rat islets exposed for 6 h to 6 days to interleukin 1 at doses ranging from 20 to 2000 ng/l at glucose concentrations of 3.3, 5.5 and 11 mmol/l. After 6 h of exposure and at all three glucose levels, all doses of interleukin 1 stimulated insulin release, maximal stimulation (370% of control) being observed at 5.5 mmol/l glucose and 100 ng/l interleukin 1. In contrast, after 6 days, all doses of interleukin 1 were inhibitory irrespective of glucose level, maximal inhibition (90%) being observed at 11 mmol/l glucose and 2000 ng/l interleukin 1. At 24 and 48 h of exposure, the biphasic effect of interleukin 1 was observed: lower doses of interleukin 1 at lower glucose concentrations at 24 h being more stimulatory with transition to inhibition directly related to higher glucose levels, higher interleukin 1 doses, and longer exposure. After 48 h, 200 ng/l of interleukin 1 increased insulin release to 220% at 3.3 mmol/l glucose, but at 11 mmol/l glucose a 60% suppression was seen. On the basis of these data we suggest that interleukin 1's effect on beta-cells is bimodal: stimulation followed by inhibition. Increasing interleukin 1 dose and ambient glucose concentration shift this response to the left. Experimental results will, and in vivo effects may, depend upon these three variables.

Animals↗
PubMed1988

Effect of interleukin-1 on the biosynthesis of proinsulin and insulin in isolated rat pancreatic islets.

Insulin dependent diabetes mellitus (IDDM) is often preceded or associated with lymphocytic infiltration in the islets of Langerhans (insulitis). We recently demonstrated that interleukin-1 (IL-1) produced by activated macrophages exerts a bimodal effect on insulin release and biosynthesis in isolated rat islets. In the present study we have further analysed the effect of recombinant human interleukin-1 beta (rIL-1) on the biosynthesis and conversion of proinsulin 1 and 2 in rat islets. By RP-HPLC-analysis of islets labelled with [3H]leucine we found that exposure to 6 ng/ml of IL-1 for 24 h reduced the insulin biosynthesis to 6.1 +/- 2.7% (n = 4). During the 3 h labelling period the labelled proinsulin content compared to insulin was increased from 9.0 +/- 1.3% (control) to 26.6 +/- 6.4% in the IL-1 exposed islets, and the ratio between labelled insulin 1 to 2 was increased from 2.0 +/- 0.1 to 3.4 +/- 0.4, respectively. Pulse-chase experiments with [3H]leucine and [35S]methionine indicated a more marked reduction in the conversion rate of proinsulin-2 compared to that of proinsulin-1. In conclusion these experiments demonstrate that IL-1 inhibits insulin biosynthesis by preferential attenuation of the rate of conversion of proinsulin 2.

Animals↗
PubMed1987

Human tumor necrosis factor potentiates human interleukin 1-mediated rat pancreatic beta-cell cytotoxicity.

Previous studies have established that the cytokine interleukin 1 (IL-1) is selectively cytotoxic for isolated human and rat pancreatic beta-cells. This observation raises the possibility that insulin-dependent diabetes mellitus is in part due to immunologically mediated mechanisms involving IL-1. However, other cytokines are produced during immunologic responses. To study possible modulatory effects of other cytokines on IL-1-mediated beta-cell cytotoxicity, we added human recombinant IL-1 alpha and beta (rIL-1 alpha, rIL-1 beta), tumor necrosis factor (rTNF), lymphotoxin (rLT), and interferon-gamma (rIFN-gamma) separately or in combinations to the culture medium of isolated rat islets of Langerhans. A half-maximal inhibition of glucose-stimulated insulin release after 7 days of culture was obtained with 100 pg/ml of rIL-1 beta, whereas 1000 pg/ml of rIL-1 alpha were necessary to obtain an equivalent effect. While ineffective in causing inhibition of beta-cell function or morphologic damage to islets alone 2.5 to 25 ng/ml of rTNF, but not 40 ng/ml of rLT, or 25 ng/ml of rIFN-gamma markedly potentiated the inhibition of beta-cell secretory response and dissolution of islet integrity caused by rIL-1 alpha and beta. The potentiating effect of rTNF was more pronounced if the rTNF was added after 60 min of preincubation of the islets with rIL-1 beta, than if rIL-1 beta was added after 60 min of preincubation with rTNF. rTNF did not interfere with the activity of rIL-1 alpha or beta on lymphocytes. Combinations of rIFN-gamma and rTNF or rLT did not affect beta-cell function. In conclusion, rTNF strongly potentiates the functional inhibition of beta-cells and the morphologic disintegration of islets caused by rIL-1 in vitro. These data, seen in context with previous observations of rIL-1-mediated beta-cell cytotoxicity, suggest that macrophages present in the intra-islet mononuclear cell infiltrate in insulin-dependent diabetes mellitus may secrete monokines that could be important effector molecules in beta-cell destruction.

Animals↗
PubMed1987

Linkage analysis of the human insulin receptor gene and maturity onset diabetes of the young.

The cloning of the insulin receptor cDNA has permitted the definition of restriction fragment length polymorphisms at that locus. These polymorphisms were used to study the role of the insulin receptor in four pedigrees with maturity onset diabetes of the young through linkage analyses. When each pedigree was individually analysed, no linkage was demonstrated in the two larger pedigrees, implying that an insulin receptor defect was not responsible for the predisposition to diabetes in these pedigrees. One of these pedigrees was known to be hypoinsulinaemic, while insulin levels were unavailable in the second pedigree. In the two smaller pedigrees, however, a single haplotype cosegregated with diabetes. One of these pedigrees is known to be hyperinsulinaemic. The small size of the pedigrees which demonstrated cosegregation precluded statistical proof of linkage. Nonetheless, the presence of an uncommon insertional polymorphism which cosegregated with diabetes in both pedigrees was improbable and suggested that this insertion could be responsible for diabetes in these families. This study thus may be additional evidence for heterogeneity in maturity onset diabetes of the young. For the two larger pedigrees, the insulin gene and HLA region have already been eliminated as genetic markers. This study provides data which eliminate a third candidate gene in these two pedigrees.

Diabetes Mellitus, Type 2↗
PubMed1987

Interleukin 1 dose-dependently affects the biosynthesis of (pro)insulin in isolated rat islets of Langerhans.

Human crude and recombinant interleukin 1 (IL-1) was found to dose- and time-dependently affect the biosynthesis of (pro)insulin in isolated rat islets of Langerhans. Incubation of rat islets with either 0.5 U/ml or 5 U/ml of crude IL-1 for 1 h had no detectable effect on (pro)insulin biosynthesis. After 24 hours of exposure 0.5 U/ml of crude or 0.6 ng/ml of recombinant IL-1 (beta) increased the (pro)insulin biosynthesis by 42% and 58%, respectively, whereas a 10-fold greater concentration of IL-1 decreased the (pro)insulin biosynthesis by 74% and 89%, respectively. The increase in (pro)insulin biosynthesis was accompanied by an increase in total protein biosynthesis indicating a nonspecific stimulatory action of low IL-1 concentrations. In contrast, high IL-1 concentrations caused a more selective decrease of the (pro) insulin biosynthesis when compared to the total protein biosynthesis. In addition, low IL-1 concentrations were found to increase and high concentrations to decrease the relative levels of pre-proinsulin mRNA suggesting that IL-1 may act both at a pre- and post-translational level of insulin biosynthesis.

Animals↗