Search PubMed⌕ Search

Biomedical subjects

S Endres

Publications and source records attributed to S Endres.

At least 109 records · Page 6Linked to original sources
PubMed1989

The effect of dietary supplementation with n-3 polyunsaturated fatty acids on the synthesis of interleukin-1 and tumor necrosis factor by mononuclear cells.

We examined whether the synthesis of interleukin-1 or tumor necrosis factor, two cytokines with potent inflammatory activities, is influenced by dietary supplementation with n-3 fatty acids. Nine healthy volunteers added 18 g of fish-oil concentrate per day to their normal Western diet for six weeks. We used a radioimmunoassay to measure interleukin-1 (IL-1 beta and IL-1 alpha) and tumor necrosis factor produced in vitro by stimulated peripheral-blood mononuclear cells. With endotoxin as a stimulus, the synthesis of IL-1 beta was suppressed from 7.4 +/- 0.9 ng per milliliter at base line to 4.2 +/- 0.5 ng per milliliter after six weeks of supplementation (43 percent decrease; P = 0.048). Ten weeks after the end of n-3 supplementation, we observed a further decrease to 2.9 +/- 0.5 ng per milliliter (61 percent decrease; P = 0.005). The production of IL-1 alpha and tumor necrosis factor responded in a similar manner. Twenty weeks after the end of supplementation, the production of IL-1 beta, IL-1 alpha, and tumor necrosis factor had returned to the presupplement level. The decreased production of interleukin-1 and tumor necrosis factor was accompanied by a decreased ratio of arachidonic acid to eicosapentaenoic acid in the membrane phospholipids of mononuclear cells. We conclude that the synthesis of IL-1 beta, IL-1 alpha, and tumor necrosis factor can be suppressed by dietary supplementation with long-chain n-3 fatty acids. The reported antiinflammatory effect of these n-3 fatty acids may be mediated in part by their inhibitory effect on the production of interleukin-1 and tumor necrosis factor.

Adult↗
PubMed1989

Differences in the synthesis and kinetics of release of interleukin 1 alpha, interleukin 1 beta and tumor necrosis factor from human mononuclear cells.

Cell-associated and secreted interleukin 1 alpha (IL 1 alpha), IL 1 beta and tumor necrosis factor alpha (TNF-alpha), produced by human mononuclear cells (MNC) in vitro in response to lipopolysaccharide, were measured by radioimmunoassay. After 18 h of incubation, total production of IL 1 alpha in medium containing 1% heat-inactivated serum was two-to-three times higher than IL 1 beta. However, in the presence of 1% serum and 5% fresh plasma, IL 1 alpha and IL 1 beta were produced in similar amounts. Independent of the culture conditions, 90% of the IL 1 alpha remained cell associated whereas 80% of IL 1 beta was extracellular. The kinetics of production and release of IL 1 alpha, beta and TNF-alpha were also studied. IL 1 alpha and TNF-alpha reached maximal levels within 6 h of stimulation, whereas IL 1 beta reached maximal levels between 12 and 16 h. IL 1 alpha remained primarily cell associated (80%) for the first 24 h. After 48 h, extracellular IL 1 alpha exceeded cell-associated levels. IL 1 beta was primarily secreted (80%), appearing in the extracellular fluid within 6 h. TNF-alpha appeared in the extracellular fluid within 1 h of incubation, with less than 10% cell associated at any time during the 48 h of incubation. Although the three cytokines share many biological activities, this study provides evidence that MNC IL 1 alpha is predominantly a cell-associated cytokine acting on a cell-cell basis, whereas IL 1 beta and TNF-alpha are secreted as paracrine mediators.

Cells, Cultured↗
PubMed1989

In vitro production of IL 1 beta, IL 1 alpha, TNF and IL2 in healthy subjects: distribution, effect of cyclooxygenase inhibition and evidence of independent gene regulation.

Numerous studies have reported altered in vitro cytokine production in various diseases. In the present study we used specific immunoassays to quantitate production of interleukin 1 beta (IL 1 beta), IL 1 alpha, tumor necrosis factor (TNF) and IL 2 from human peripheral blood mononuclear cells (PBMC). The distribution of cell-associated and secreted cytokines was studied in PBMC of 21 individuals; in response to lipopolysaccharide (LPS) the proportion of cell-associated IL 1 beta ranged from 13% to 56%, for IL 1 alpha 29% to 98%, and for TNF 2% to 17%. In a larger cohort of 32 subjects, the total amount of immunoreactive cytokines produced in response to LPS or phytohemagglutinin was normally distributed within the study group. Mean production of IL 1 alpha in response to LPS was 10.1 ng/ml and exceeded production of IL 1 beta (5.6 ng/ml) and TNF (2.2 ng/ml). The distribution pattern was characterized by high intersubject variability extending over two orders of magnitude and the presence of high and low "producers". Production of IL 1 alpha and IL 1 beta correlated (R = 0.69). In contrast, production of IL 1 beta did not correlate with production of TNF or IL 2. Indomethacin present during stimulation of PBMC increased the amount of IL 1 beta produced and showed a high correlation (R = 0.83) compared to cultures without indomethacin. Thus, low production of IL 1 beta in certain subjects appears not to be due to inhibitable levels of cyclooxygenase products. In a retrospective study, PBMC from 12 subjects who had taken oral cyclooxygenase inhibitors during the preceding 7 days produced 43% more IL 1 beta than subjects who did not take these drugs (p less than 0.05). These studies demonstrate that the amount of cytokine synthesized by PBMC (a) is regulated independently for IL 1, TNF and IL 2; (b) correlates for IL 1 beta and IL 1 alpha; (c) is intrinsic for low and high "producers", and (d) production of IL 1 beta increases with the use of oral cyclooxygenase inhibitors.

Adult↗
PubMed1989

Role for interleukin-1 in the pathogenesis of hypersensitivity diseases.

Interleukin-1 (IL-1), a polypeptide product of various cells, is one of the key mediators of the body's response to microbial invasion, inflammation, immunological reactions, and tissue injury. IL-1 is a prominent member of a group of polypeptide mediators now called "cytokines." Current evidence suggests that IL-1 is not produced in health but that any perturbation such as inflammation or even slight injury triggers the expression of IL-1 genes. The biological effects of IL-1 are manifested in nearly every tissue and organ. These include various proinflammatory effects such as increased production of arachidonate metabolites, synovial cell proteases, activation of basophils, eosinophils and neutrophils, endothelial cell adhesiveness, and stimulation of lymphocyte responses. Control of IL-1 synthesis in certain diseases is often appropriate. Although corticosteroids reduce both the transcription and translation of IL-1, we have recently investigated the effect of dietary supplementation with N-3 (omega-3) fatty acids in human volunteers. The results indicate that increasing the amount of N-fatty acids in the diet decreases the ability of blood mononuclear cells to synthesize IL-1 in vitro. It is suggested that the ameliorative effects of N-3 fatty acid dietary supplements in patients with hypersensitive diseases may be, in part, the result of decreased IL-1 production.

Hypersensitivity↗
PubMed1988

C5a stimulates secretion of tumor necrosis factor from human mononuclear cells in vitro. Comparison with secretion of interleukin 1 beta and interleukin 1 alpha.

We have demonstrated that purified C5a is a potent stimulus to human PBMC secretion of TNF-alpha, IL-1 beta, and IL-1 alpha, which proceeds in a dose-dependent fashion. At a given concentration of C5a, TNF-alpha and IL-1 beta secretion did not differ significantly; both were secreted in significantly greater quantity than IL-1 alpha. Clinical conditions such as Gram-positive and Gram-negative bacterial infections, trauma, and immune complex diseases activate complement. Through the mediation of TNF and IL-1 secreted in response to C5a, these diverse disorders can share common features of fever, coagulopathy, acute phase protein production, and disordered metabolism.

Complement C5↗
PubMed1988

Novel and enhanced IL-1 gene expression in autoimmune mice with lupus.

IL-1 is a pleiotropic factor encoded for by at least two genes, alpha and beta, and capable of eliciting a broad set of immunologic and inflammatory events. MRL/MP-lpr (MRL-lpr) mice are an appealing model for studies of renal injury inasmuch as disease in this strain is spontaneous, rapid, predictable, and regulated by the lpr gene. Infiltration of macrophages and the proliferation of the glomerular mesangial cells are prominent features of renal disease. Because both mesangial cells and macrophages can synthesize IL-1, the purpose of this study was to determine whether enhanced IL-1 gene expression is associated with lupus nephritis in the MRL-lpr mouse model. Glomerular macrophages, abundant in the kidneys of MRL-lpr mice but rarely present in the kidney of congenic MRL/MP-++(MRL-++) mice, were isolated and cultured and found to express a 10-fold increase in both IL-1 alpha and IL-1 beta mRNA transcripts as compared with MRL-++ and MRL-lpr mesangial cells. IL-1 alpha was not detected in the total RNA extracted from freshly excised kidney, whereas IL-1 beta transcripts were detected in both the renal cortex of MRL-lpr as well as MRL-++ animals. A previously undetected truncated 1200 nucleotide IL-1 beta transcript together with the conventional 1600 nucleotide IL-1 beta transcript was found in kidneys from MRL-lpr and was abundantly expressed in glomeruli of MRL-lpr mice with lupus nephritis. Isolated glomeruli from MRL-lpr mice with nephritis produce IL-1, whereas in normal glomeruli from MRL-++ and C3H/FeJ mice this cytokine was not detected. Glomerular macrophages and mesangial cells cultured from MRL-lpr mice with nephritis both secrete IL-1. These studies indicate that IL-1 beta gene expression and IL-1 protein are increased in the kidneys of autoimmune mice with lupus nephritis and is generated, at least in part, by glomerular macrophages. We speculate that an alteration in IL-1 beta gene expression may be responsible for causing a cascade of events leading to acute and chronic renal injury.

Animals↗
PubMed1988

Concentrations of immunoreactive human tumor necrosis factor alpha produced by human mononuclear cells in vitro.

The concentrations of tumor necrosis factor (TNF) produced by human peripheral blood mononuclear cells (MNC) were measured using a radioimmunoassay (RIA) for human TNF. This was developed using a rabbit antiserum against human recombinant TNF (Hu rTNF), and Hu rTNF labeled with Na125I by a modification of the chloramine T method. This RIA does not detect human lymphotoxin, interleukin-1 alpha or beta, interleukin 2, interleukin 6, interferon alpha or gamma, granulocyte-macrophage-colony stimulating factor, and C5a des arg. A good correlation (r = 0.89) was found between the RIA and the cytolytic bioassay for TNF. The sensitivity of the RIA is between 3 and 78 pg/ml (median 11 pg/ml). The mean concentration of TNF in 24-h culture supernatants of human MNC exposed to different concentrations of lipopolysaccharide (LPS) was found to increase in dose-dependent fashion and then level off between 50 and 100 ng/ml. The concentrations of IL-1 beta and alpha detected by specific RIAs in these supernatants were between 0.2 and 19 ng/ml and 0.04 and 1 ng/ml, respectively. The amount of TNF produced by human MNC in vitro was determined in a cohort of 50 normal volunteers. Without exogenous stimuli, TNF concentrations were almost always below the detection limit; with 0.5 ng/ml LPS, the median concentration of TNF was 2 ng/ml, and with PHA the median was 3.8 ng/ml. In cultures performed in the presence of indomethacin significantly (p less than 0.005) more TNF was produced. Using this RIA, we could detect TNF in the circulation of mice injected with Hu rTNF. When plasma samples of patients with febrile illnesses were added directly to the RIA, TNF was not detectable, with the exception of patients with malaria. These studies demonstrate the range and sensitivity of LPS-induced and mitogen-induced production of immunoreactive TNF by human MNC in vitro without interference of similar cytokines in bioassays.

Animals↗
PubMed1988

Measurement of immunoreactive interleukin-1 beta from human mononuclear cells: optimization of recovery, intrasubject consistency, and comparison with interleukin-1 alpha and tumor necrosis factor.

Numerous studies have reported altered levels of in vitro production of the cytokines interleukin-1 (IL-1) and tumor necrosis factor (TNF) from blood leukocytes in various human disease states. Most of these studies have used bioassays which are vulnerable to inhibitors produced by these cells. Furthermore in vitro cytokine production is often assessed on a single occasion. The present study was designed to standardize stimulation conditions for in vitro IL-1 beta production and to employ a competitive radioimmunoassay (RIA) to demonstrate reproducibility and long-term variation of in vitro cytokine production in a cohort of healthy human subjects. We also examined relative amounts of immunoreactive IL-1 beta, IL-1 alpha, and TNF induced by the stimuli endotoxin, phytohemagglutinin, or Staphylococcus epidermidis. We show that the RIA can reliably detect IL-1 beta produced from mononuclear cells in concentrations as low as 115 pg/ml. Lysing cells by repeated freeze-thawing yields maximal recovery of total (i.e., secreted plus cell-associated) immunoreactive IL-1 beta, when compared to extraction with the detergent CHAPS or addition of protease inhibitors. Repeated measurement of in vitro cytokine production on different days within 1 week shows good reproducibility for a given individual and a given stimulus (variation coefficient 20 to 30%). Over a long time period (6 months) in vitro cytokine production is stable in some individuals but changes considerably in others. The soluble stimulus endotoxin induces twofold more IL-1 alpha than IL-1 beta or TNF; in contrast the phagocytic stimulus heat-killed S. epidermidis induces fourfold more IL-1 beta and TNF than IL-1 alpha. This distinct pattern of cytokine response indicates differential stimulation of the mononuclear cells by different stimuli. The results form the basis for studying in vitro cytokine production in different human disease states.

Animals↗
PubMed1988

Parallel determination of mineralocorticoid and glucocorticoid receptors in T- and B-lymphocytes of human spleen.

The binding characteristics of glucocorticoid and mineralocorticoid receptors were determined in T- and B-lymphocytes from the spleen of four deceased kidney donors. The number of glucocorticoid and mineralocorticoid receptors was equivalent in T- and B-cells (respectively, 1308 +/- 364 and 1335 +/- 520 glucocorticoid receptors per cell, and 174 +/- 29 and 164 +/- 24 mineralocorticoid receptors per cell). The number of binding sites per cell was 5- to 10-fold higher for dexamethasone than for aldosterone. The apparent dissociation constant of dexamethasone for glucocorticoid receptors was 2-fold higher than that of aldosterone for mineralocorticoid receptors. In conclusion, subpopulations of human lymphocytes have an equal number of glucocorticoid and mineralocorticoid receptors.

B-Lymphocytes↗
PubMed1988

Interleukin-1 beta in human plasma: optimization of blood collection, plasma extraction, and radioimmunoassay methods.

Current immunoassays for interleukin-1 beta (IL-1 beta) are effective for analyzing fluids derived from cultured cells. However, IL-1 beta determinations in human plasma or serum samples are technically complicated by higher protein and lipid concentrations, physicochemical differences which exist between samples from healthy subjects and those experiencing acute phase responses, and by the fact that IL-1 beta can be produced and degraded in the blood collection tube after the sample is drawn. A simple chloroform extraction process has been developed which eliminates several of the interfering factors from plasma samples and increases the amount of IL-1 beta detected by radioimmunoassay and lymphocyte activation assay. In the radioimmunoassay, rabbit sera was found to influence the accuracy and variability of plasma measurements. Improvements in radioimmunoassay reagents and methods are reported which reduce this influence. Finally, different concentrations of IL-1 beta were measured depending on whether serum or plasma was tested. We propose that plasma samples collected with EDTA and aprotinin provide a better determination of free circulating IL-1 beta in vivo than serum samples, which may contain IL-1 beta secreted from blood leukocytes during the clotting process.

Acute-Phase Reaction↗
PubMed1988

A radioimmunoassay for human interleukin-1 alpha: measurement of IL-1 alpha produced in vitro by human blood mononuclear cells stimulated with endotoxin.

A specific radioimmunoassay (RIA) for human interleukin-1 alpha (IL-1 alpha) which detects less than 25-50 pg/ml IL-1 alpha is described. Although human IL-1 alpha shares structural homology, receptors and multiple biological properties with IL-1 beta, this RIA does not detect human IL-1 beta or other human cytokines. We recovered nearly 100% of IL-1 alpha added to fresh human heparinized blood or freshly voided urine; in contrast, using a specific RIA for IL-1 beta, recovery of IL-1 beta added to fresh blood is approximately 50% reduced by nonspecific factors. In the present study, we employed this RIA to measure the amount of total (extracellular and cell-associated) immunoreactive IL-1 alpha produced by human blood mononuclear cells stimulated in vitro by different concentrations of endotoxin. Using ultrafiltered culture medium to reduce endotoxin content, there was no detectable (less than 50 pg/ml) IL-1 alpha produced after 24 hours. Endotoxin (0.5 ng/ml) induced a mean concentration of 900 pg/ml (range 180-1660 pg/ml). At higher concentrations of endotoxin (500 ng/ml), a mean of 6,990 pg/ml (range 415-11,900 pg/ml) was produced. These levels were comparable to the amount of IL-1 beta produced under similar culture conditions. The results indicate that IL-1 alpha can be measured independently of IL-1 beta in human body fluids and from human mononuclear cells.

Endotoxins↗
PubMed1987

C5a induction of human interleukin 1. Synergistic effect with endotoxin or interferon-gamma.

Interleukin-1 (IL-1) is a potent cytokine which possesses the ability to mediate systemic acute phase responses as well as local tissue inflammation. In these studies, we have examined the ability of C5a and C5a des Arg to induce IL-1 production in vitro. Human C5a and C5a des Arg were purified to homogeneity and were found to stimulate IL-1 release from freshly obtained human mononuclear cells into the extracellular medium. Only 2 hr of exposure to the purified complement components were necessary in order to stimulate IL-1 production. The minimal concentration of C5a required was 25 ng/ml, whereas 125 ng/ml of C5a des Arg induced comparable amounts of IL-1. This dose relationship was maintained at higher concentrations (150 ng/ml vs 750 ng/ml, respectively). That the effect was due to the anaphylatoxins themselves, and not endotoxin contamination, was shown by negative Limulus amebocyte lysate tests and employing preincubation of C5a/C5a des Arg with polymyxin B. The latter blocked a wide dose range of endotoxin-stimulated IL-1 production. However, when endotoxin was added to C5a or C5a des Arg, significant synergism in the stimulation of IL-1 production was observed, occurring at various concentrations of either agent. A similar synergism with C5a/C5a des Arg was seen with interferon-gamma. In these studies, IL-1 production was measured by bioassay employing cloned D . 10 . G4 . 1 murine T cells and by radioimmunoassay for human IL-1 beta; using C5a/C5a des Arg as stimulants, there was a high degree of correlation (r = 0.82) between the two assays. Since traumatic, infectious, and inflammatory diseases may result in the simultaneous appearance of these stimuli, the synergism described herein is likely to be clinically relevant.

Biological Assay↗
PubMed1987

Development and use of a radioimmunoassay for human interleukin-1 beta.

Interleukin-1 (IL-1) mediates immunological, physiological, and metabolic changes associated with inflammation and host defense systems. Measurement of IL-1 activity can vary with the bioassay employed and substances have been described in several bioassay systems that either inhibit or mimic IL-1 activity. We now report a sensitive, rapid (24 hour), and specific radioimmunoassay for human IL-1 beta. Using 125I-labeled IL-1 beta and polyclonal rabbit antisera raised against recombinant human IL-1 beta, a competitive inhibition assay is described which detects 250 pg/ml of recombinant human IL-1 beta and 500 pg/ml of pI 7 human monocyte IL-1. The assay does not detect human IL-1 alpha, human interleukin-2, human tumor necrosis factor-alpha or human interferon-gamma. Nearly 100% of IL-1 beta added to human serum or urine can be quantitatively recovered. Substances such as fetal calf serum, phytohemagglutinin, opsonized Staphylococcus albus or E. coli endotoxin do not affect the assay. Using this assay, IL-1 beta was measured in both the intracellular and extracellular compartments of stimulated human blood mononuclear cells. These results were unaffected by the presence of substances that interfere with bioassays for IL-1 such as indomethacin or BW 755C, a lipoxygenase inhibitor. These studies establish the usefulness of quantitating immunoreactive human IL-1 beta produced by human blood cells and that which may be present in human body fluids in the presence of other cytokines.

Animals↗
PubMedDate not supplied

Tumor necrosis factor-alpha mediates RANK ligand stimulation of osteoclast differentiation by an autocrine mechanism.

Osteoblasts or bone marrow stromal cells are required as supporting cells for the in vitro differentiation of osteoclasts from their progenitor cells. Soluble receptor activator of nuclear factor-kappaB ligand (RANKL) in the presence of macrophage colony-stimulating factor (M-CSF) is capable of replacing the supporting cells in promoting osteoclastogenesis. In the present study, using Balb/c-derived cultures, osteoclast formation in both systems-osteoblast/bone-marrow cell co-cultures and in RANKL-induced osteoclastogenesis-was inhibited by antibody to tumor necrosis factor-alpha (TNF-alpha), and was enhanced by the addition of this cytokine. TNF-alpha itself promoted osteoclastogenesis in the presence of M-CSF. However, even at high concentrations of TNF-alpha the efficiency of this activity was much lower than the osteoclastogenic activity of RANKL. RANKL increased the level of TNF-alpha mRNA and induced TNF-alpha release from osteoclast progenitors. Furthermore, antibody to p55 TNF-alpha receptors (TNF receptors-1) (but not to p75 TNF-alpha receptors (TNF receptors-2) inhibited effectively RANKL- (and TNF-alpha() induced osteoclastogenesis. Anti-TNF receptors-1 antibody failed to inhibit osteoclastogenesis in C57BL/6-derived cultures. Taken together, our data support the hypothesis that in Balb/c, but not in C57BL/6 (strains known to differ in inflammatory responses and cytokine modulation), TNF-alpha is an autocrine factor in osteoclasts, promoting their differentiation, and mediates, at least in part, RANKL's induction of osteoclastogenesis.

Acid Phosphatase↗
PubMedDate not supplied

Prostacyclin analogs suppress the synthesis of tumor necrosis factor-alpha in LPS-stimulated human peripheral blood mononuclear cells.

Recent reports have shown that prostaglandin E2 (PGE2) is able to suppress lipopolysaccharide (LPS)-stimulated production of tumor necrosis factor-alpha (TNF-alpha). In the present study we compared PGE2 with prostacyclin (PGI2) analogs in their potency to influence LPS-stimulated production of interleukin-1 beta (IL-1 beta) and TNF-alpha by human mononuclear cells (MNC). Our results show, that the stable analogs of PGI2, iloprost and cicaprost, markedly suppress TNF-alpha synthesis in LPS-stimulated MNC without effect on IL-1 beta production. Although there was no significant difference in maximal suppression of TNF-alpha, iloprost and cicaprost reached suppression to 50% of control at 20-fold lower concentrations than PGE2. The ID50 for iloprost and cicaprost were 8 nM and 5 nM, respectively, compared to 125 nM for PGE2. Moreover, the prostacyclin analogs as well as PGE2 suppressed LPS-induced production of TNF-alpha in Mono Mac 6 cells, a permanent human cell line with characteristics of mature monocytes. Suppression of TNF-alpha synthesis by cicaprost and PGE2 is probably mediated by an increased intracellular cAMP formation. We were able to show elevated cAMP levels with 1 microM and 10 microM of PGE2 and cicaprost in this system. The suppression of TNF-alpha synthesis may add to the beneficial effects of iloprost reported in animal models of acute respiratory distress syndrome (ARDS) and may offer a therapeutic approach in TNF-alpha mediated pathologic processes.

Cell Line↗