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Biomedical subjects

H Tilg

Publications and source records attributed to H Tilg.

At least 73 records · Page 4Linked to original sources
PubMed1994

Biologic activity of low dosage IL-2 treatment in vivo. Molecular assessment of cytokine network interaction.

The sequence of activation of the components of the cytokine network subsequent to in vivo application of different dosages of IL-2 is still poorly understood. Although side effects of IL-2 therapy are dose dependent, the dose-response relationship for induction of potentially beneficial or harmful cytokine genes still remains to be studied. We examined the patterns of cytokine gene expression after treatment of chronic hepatitis B patients with various doses of IL-2 in a phase 1 trial. Total RNAs were isolated from PBMC harvested at various time points after s.c. injection of natural IL-2 ranging from 30,000 to 1,000,000 U. Dose-dependent effects on mRNA expression of IL-2, GM-CSF, IFN-gamma, TNF-alpha, and IL-6 were assessed using Northern blotting and slot blotting techniques. A single application of 30,000 U nIL-2 induced selective and long-lasting expression of IL-2, IFN-gamma, and GM-CSF genes, which was not accompanied by accumulation of TNF-alpha and IL-6 mRNAs. Larger dosages of IL-2 induced activation of monokine genes and were associated with systemic side effects. mRNA levels of the different cytokines related to biologic activity and correlated with expression of specific proteins and cellular parameters: IL-2 mRNA with soluble IL-2R serum levels and induction of lymphopenia, GM-CSF mRNA with induction of neutrophilia, and IL-6 mRNA with c-reactive protein serum concentrations. Taken together these data indicate unexpected immunoregulatory activities of very low and nontoxic dosages of IL-2 in vivo.

Adolescent↗
PubMed1994

Induction of circulating antagonists to IL-1 and TNF by IL-2 administration and their effects on IL-2 induced cytokine production in vitro.

The objectives of this study were to determine whether intensive immunotherapy with IL-2 results in detectable levels of circulating IL-1 and TNF antagonists and whether the levels achieved in vivo are sufficient to affect the generation of secondary proinflammatory cytokines such as IL-1 beta and TNF-alpha. We also sought to determine the extent to which endogenous TNF mediates the generation of an IL-1 antagonist by IL-2-activated PBMCs. In patients undergoing high dose IL-2 immunotherapy, plasma IL-1 receptor antagonist (IL-1ra) levels rose dramatically after the first IL-2 injection, reaching a plateau of 11.03 +/- 0.92 ng/ml within 4 h. TNF-soluble receptor p55 (TNFsRp55) was also detected in the plasma shortly after initiating treatment, and the levels progressively increased throughout the treatment course. PBMCs exposed to IL-2 expressed IL-1ra mRNA and secreted the IL-1ra protein, but neither PBMCs nor neutrophils shed TNFsRp55 in response to IL-2 or supernatants from IL-2-activated PBMCs. IL-1ra at concentrations achieved in the plasma during IL-2 immunotherapy (approximately 10 ng/ml) inhibited the in vitro production of IL-1 beta and TNF-alpha by IL-2-activated PBMCs by 65% and 30%, respectively. Although the monomeric receptor TNFsRp55 at concentrations achieved in the plasma had no effect on the in vitro production of IL-1ra, TNF-alpha, or IL-1 beta, the bivalent TNFsRp75-Fc chimera suppressed the generation of TNF and IL-1. IL-1ra synthesis was unaffected. These results suggest that the amount of IL-1ra generated in response to IL-2 is most likely sufficient to down-modulate the production of proinflammatory cytokines.

Cells, Cultured↗
PubMed1994

Interleukin-6 (IL-6) as an anti-inflammatory cytokine: induction of circulating IL-1 receptor antagonist and soluble tumor necrosis factor receptor p55.

The aim of this study was to investigate whether interleukin (IL)-6 induces the production of IL-1 and tumor necrosis factor (TNF) antagonists. Serial plasma samples were obtained from cancer patients participating in phase I and II trials of recombinant IL-6 administered as a 120-hour continuous intravenous (IV) infusion. Plasma IL-1 receptor antagonist (IL-1Ra) and soluble TNF receptor p55 (TNFsRp55) levels were measured by specific radioimmunoassays (RIAs). IL-1Ra levels increased rapidly, reaching peak values (9.6 +/- 1.7 ng/mL) within 2 to 4 hours of beginning treatment. Thereafter, levels promptly declined, reaching near baseline within 24 hours despite continuation of IL-6. TNFsRp55 plasma levels increased within 4 to 8 hours after initiating treatment and increased progressively throughout the duration of therapy. IL-1 beta and TNF-alpha plasma levels were below the detection limit in all samples tested. Peripheral blood mononuclear cells (PBMC) exposed to IL-6 produced only small amounts (1.56 +/- 0.3 ng/mL) of IL-1Ra, even in the presence of exogenous soluble IL-6 receptor (gp80). TNFsRp55 levels measured in the supernatants of IL-6-stimulated PBMC were below the detection limit of the assay. Macrophages generated by culturing monocytes in granulocyte-macrophage colony-stimulating factor (GM-CSF) were much more responsive to IL-6 than freshly isolated unfractionated or adherent PBMC and synthesized almost as much IL-1Ra when stimulated with IL-6 as with endotoxin. These results suggest that the antinflammatory properties of IL-6 may be due; in part, to the induction of IL-1Ra synthesis and the release of soluble TNF receptors. Our findings also suggest that tissue macrophages may be an important source of IL-6-induced IL-1Ra.

Anti-Inflammatory Agents↗
PubMed1994

Induction of circulating soluble tumour necrosis factor receptor and interleukin 1 receptor antagonist following interleukin 1 alpha infusion in humans.

The aim of this study was to investigate circulating levels of tumour necrosis factor soluble receptor p55 (TNFsrp55) and interleukin 1 receptor antagonist (IL-1ra) in cancer patients undergoing treatment with IL-1 alpha. Patients were treated with 0.03 micrograms/kg IL-1 alpha administered intravenously over a 30 min interval daily for five consecutive days. Plasma TNFsrp55 levels rose dramatically and peaked (24.5 +/- 3.6 ng/ml) within 1 h after the first IL-1 alpha infusion. Thereafter, the levels rapidly declined and reached baseline levels within 24 h. The increases observed on days 3 and 5 of treatment were less pronounced but the reductions in peak levels were not statistically significant. IL-1ra levels increased less abruptly after an IL-1 alpha infusion than did TNFsrp55 levels and peaked (25.3 +/- 5.1 ng/ml) within 2 h of the start of the IL-1 alpha infusion. Levels then rapidly declined reaching baseline values within 24 h. As with TNFsrp55 levels, peak IL-1ra levels observed on days 3 and 5 of treatment were less than those measured on day 1. IL-1 alpha and IL-1 beta levels were consistently below the threshold of detection of the RIAs employed in these studies. Likewise, with the exception of a single time point in one of the four patients studied, TNF-alpha was undetectable in all plasma samples assayed.(ABSTRACT TRUNCATED AT 250 WORDS)

Cyclophosphamide↗
PubMed1993

Antiinflammatory properties of hepatic acute phase proteins: preferential induction of interleukin 1 (IL-1) receptor antagonist over IL-1 beta synthesis by human peripheral blood mononuclear cells.

This study was undertaken to determine whether acute phase proteins (APP) induce the synthesis of interleukin 1 beta (IL-1 beta) and its specific antagonist, IL-1 receptor antagonist (IL-1Ra), in human peripheral blood mononuclear cells (PBMC). PBMC from healthy volunteers were incubated with C-reactive protein (CRP), alpha 1-antitrypsin (alpha 1-AT), or alpha 1-acid glycoprotein (AGP), and the levels of IL-1 beta and IL-1Ra produced were measured by specific radioimmunoassay. To evaluate the effects of alpha 1-AT further, a synthetic pentapeptide FVYLI corresponding to the minimal binding sequence for the serpine-enzyme complex receptor was also evaluated. PBMC incubated for 24 h with CRP, alpha 1-AT, or the pentapeptide FVYLI synthesized large quantities of IL-1Ra, 5-10-fold greater than the amount of IL-1 beta produced by these cells. AGP induced significantly less IL-1Ra than the other APP tested. These effects were shown to be specific, in that polyclonal antibodies against CRP, alpha 1-AT, and AGP eliminated the cytokine production induced by these respective proteins. CRP, alpha 1-AT, FVYLI, and AGP were synergistic with low concentrations of endotoxin in the induction of both IL-1Ra and IL-1 beta synthesis. We suggest that the preferential induction of IL-1Ra by APP may contribute to their antiinflammatory effects and provide an important regulatory signal for the acute phase response.

Acute-Phase Proteins↗
PubMed1993

Induction of circulating and erythrocyte-bound IL-8 by IL-2 immunotherapy and suppression of its in vitro production by IL-1 receptor antagonist and soluble tumor necrosis factor receptor (p75) chimera.

The objective of this study was 1) to investigate the in vivo production of IL-8 in patients undergoing IL-2 immunotherapy and 2) to study the influence of IL-1Ra, soluble TNF receptor p75 (TNFsRp75), and a TNFsRp75-Fc fusion protein on IL-2-induced IL-8 production in vitro. Circulating IL-8 was assessed both in plasma and erythrocyte lysates prepared from patients undergoing IL-2 immunotherapy. IL-8 was detectable in the plasma within 2-4 h after the first IL-2 infusion, reached a peak level after 4 h, and declined rapidly to undetectable within 8 h. Erythrocyte-bound IL-8 was also detected within 4 h of the first IL-2 dose, but levels were higher than those measured in plasma and remained elevated long after the plasma levels had become undetectable. On day 4 of therapy, the increases in both plasma and the erythrocyte-lysate IL-8 levels induced by an IL-2 injection were less pronounced than on day 1. Although IL-1Ra and TNFsRp75-Fc individually had only a modest suppressive effect on IL-2-induced IL-8 production by PBMC in vitro, the combination of IL-1Ra and TNFsRp75-Fc markedly down-regulated IL-2-induced IL-8 synthesis and steady-state mRNA levels. TNFsRp75 had no effect on IL-2-induced IL-8 synthesis. Our studies suggest that the transient detection of IL-8 in plasma early in the course of IL-2 treatment is due to erythrocyte sequestration and that suppressed synthesis, due in part to high levels of circulating IL-1 and TNF antagonists, may play a role later in the course of treatment.

Calcium↗
PubMed1993

A method for the detection of erythrocyte-bound interleukin-8 in humans during interleukin-1 immunotherapy.

Interleukin-8 (IL-8) has been recently shown to bind to human erythrocytes with high affinity and is therefore potentially difficult to detect in serum or plasma. IL-8 is transiently elevated in the serum of baboons after the administration of interleukin-1 alpha (IL-1 alpha). The objective of this study was to investigate whether IL-8 can be detected in the plasma or in detergent-lysed erythrocytes from cancer patients undergoing treatment with IL-1 alpha. Using a specific radioimmunoassay (RIA), plasma IL-8 was detected within 1-2 h after the first IL-1 alpha infusion. Thereafter, the levels declined rapidly and after 4-8 h were undetectable. Erythrocyte-bound IL-8 was detectable 1-2 h after the increase in plasma levels. The erythrocyte-bound IL-8 levels were higher than those measured in plasma and remained elevated long after the plasma levels had become undetectable. Erythrocyte membranes accounted for all of the erythrocyte-associated IL-8, as IL-8 was undetectable in the cytosol after erythrocyte lysis. The assay used in these studies detects IL-8 in erythrocyte lysates when it cannot be measured in plasma and may therefore be useful in monitoring IL-8 production in vivo.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1993

Induction of circulating IL-1 receptor antagonist by IFN treatment.

This study was undertaken to determine whether IFN induce IL-1 receptor antagonist (IL-1Ra), a specific inhibitor of IL-1. Plasma samples were obtained from healthy volunteers (n = 5) and patients with chronic hepatitis C (n = 5) treated with IFN-alpha, and from patients with renal cell carcinoma (n = 6) treated with IFN-gamma and assayed for IL-1Ra by a specific radioimmunoassay. Both types of IFN were administered subcutaneously. In vitro studies were carried out with PBMC from healthy volunteers. A single, low and nontoxic dose (1 x 10(6) U) of IFN-alpha induced circulating IL-1Ra, which reached peak levels within 12 h. This effect was dose-dependent and more pronounced with a higher dose (5 x 10(6) U). Peak IL-1Ra levels 12 h after 5 x 10(6) U IFN-alpha were 4.16 +/- 0.35 ng/ml in healthy volunteers and 5.7 +/- 0.73 ng/ml in patients with chronic hepatitis C (difference not significant). Thereafter levels declined but remained elevated for 24 h. IFN-gamma treatment led only to a modest increase of circulating IL-1Ra even at a dose of 400 micrograms; this dose, however, was associated with side effects similar to those seen after injection of 5 x 10(6) U IFN-alpha. PBMC stimulated with IFN-alpha or IFN-gamma produced IL-1Ra in vitro. The induction of IL-1Ra may contribute to the antiviral, anti-inflammatory, and antiproliferative effects of IFN.

Carcinoma, Renal Cell↗
PubMed1993

Divergent in vivo and in vitro antileukemic activity of recombinant interferon beta in patients with chronic-phase chronic myelogenous leukemia.

It was the aim of this study to investigate the antileukemic activities of recombinant interferon beta (rIFN beta) in chronic-phase CML in vitro and in vivo. Nine patients in the early chronic-phase of CML were treated in a phase-II trial with escalating doses of rIFN beta. In parallel, antiproliferative and immunomodulatory activities of rIFN beta and rIFN alpha 2b were studied in vitro. rIFN beta exhibited a significantly higher antiproliferative activity on hematopoietic progenitor cells of CML patients in vitro than rIFN alpha 2b. In contrast, only very limited clinical antileukemic efficacy of rIFN beta was observed. None of the patients achieved a complete or partial hematologic response (0% response rate, 0-36% 95 C.I.). Primary resistance of CML patients to rIFN beta treatment was caused neither by antibody formation against the recombinant material nor by deficient IFN receptor targeting and/or signaling; Induction of serum levels of beta-2-microglobulin (beta-2-m) and neopterin after administration of rIFN beta was comparable to that seen after administration of rIFN alpha. However, rIFN beta treatment less effectively induced biosynthesis of interleukin-1 receptor antagonist protein (IL-1-Ra) than rIFN alpha 2b. Thus, we conclude that rIFN beta at doses up to 12 MU/day s.c. is ineffective for treatment of chronic-phase CML. Further investigations into divergent biologic responses to various type-I interferons might help to elucidate mechanisms crucial for IFN action in patients with CML.

Adult↗
PubMed1993

The role of cytokines in the pathophysiology of chronic liver diseases.

Many of the biological activities of cytokines are similar to clinical manifestations and abnormalities of laboratory parameters observed in chronic liver diseases (CLD). Evidence of impaired cytokine synthesis in CLD comes from studies of serum or plasma levels, supernatants of peripheral blood mononuclear cells stimulated with various agents and from studying cytokine expression locally in the liver. Circulating levels of several cytokine-regulated molecules such as neopterin, soluble IL-2 receptor, adhesion molecules, and metabolites of the nitric oxide pathway are elevated in patients with CLD. Thus inhibition of cytokine synthesis or modulation of their activity could provide not only important information about their pathophysiologic relevance but also have a profound impact on disease progression in CLD. These studies will also show whether prolonged anti-cytokine treatment with interleukin-1- or tumor necrosis factor-inhibitors interferes with host defense mechanism.

Chronic Disease↗
PubMed1993

Pilot study of natural human interleukin-2 in patients with chronic hepatitis B. Immunomodulatory and antiviral effects.

Ten patients with chronic hepatitis B received increasing doses of nIL-2 (30,000 U, 100,000 U, 300,000 U, 1.0 million U) subcutaneously in a phase I trial. Each dose was applied once per week over 3 weeks. Serum samples were taken before and 2, 12, 24, 48 and 72 h after the first application of each dose level. Serum concentrations of interleukin-1 (IL-1), IL-2, IL-6, interferon-alfa (IFN-alpha), IFN-gamma, tumor necrosis factor-alpha (TNF-alpha) and GM-CSF as well as the cytokine-dependent serum components neopterin, beta-2-microglobulin (B2M), C-reactive protein (CPR), soluble IL-2-receptor (sIL-2R) and 2'-5'-oligoadenylate synthetase (2-5 OA) were assayed using ELISAs and RIAs. None of the samples tested contained measurable cytokine levels other than IL-2. A low and non-toxic dose of 300,000 U nIL-2 was already biologically active with induction of neopterin, B2M and sIL-2R. Dose-dependent changes peaked 24-48 h after application. The same patients were then enrolled in a phase II trial. Treatment in five of the patients was continued twice per week for 3 months with a biologically active dose of 300,000 U nIL-2 subcutaneously. Two of these patients as well as another five patients from the original group were treated with 1.0 million U nIL-2 subcutaneously, twice weekly for 3 months. Neither a biologically active but non-toxic dose of 300,000 U nIL-2, nor a toxic dose of 1.0 million U resulted in permanent clearance of hepatitis B early antigen (HBeAg).(ABSTRACT TRUNCATED AT 250 WORDS)

2',5'-Oligoadenylate Synthetase↗
PubMed1993

Immune response modulation by pentoxifylline in vitro.

Pentoxifylline (PTX) has recently been shown to modulate TNF-alpha production and to reduce the incidence and severity of all major complications after BMT, including mucositis, veno-occlusive disease, renal insufficiency, hypertension, and graft-versus-host disease. To analyze in detail the effect of PTX on immune complications after BMT, we investigated the immunomodulatory effect of PTX on immune responses in vitro. The continuous presence of PTX significantly reduced the proliferative response of PBMC to PHA stimulation and to alloantigens in a dose-dependent manner. Starting at concentrations of 100 micrograms/ml, PTX was able to inhibit and, at 1000 micrograms/ml, completely block mitogen-induced proliferation. Maximal inhibition of more than 90% (91 +/- 4%) was also observed at PTX concentrations of 1000 micrograms/ml in the mixed lymphocyte culture (MLR) and by addition on day 0. However, lower but still significant suppression (13 +/- 7%) was achieved at concentrations of 10 micrograms/ml PTX. The inhibitory capacity of PTX was increased by mAbs against TNF-alpha (34 +/- 5% additional suppression at 100 micrograms/ml PTX) and not reversed by the addition of rTNF-alpha. The effect of PTX on the generation of CTLs in vitro was studied in the cell-mediated lymphotoxicity assay. PTX (100 micrograms/ml) significantly inhibited (P = 0.0178) the in vitro generation of CTLs when PTX was added to the culture on day 0. PTX also showed profound modulatory properties in the NK assay, with a reduction of 23 +/- 3% in specific lysis at 10 micrograms/ml PTX and maximal reductions of 88 +/- 3% at 1000 micrograms/ml PTX. Immunomodulatory properties of PTX were not only associated with blockage of TNF-alpha, as shown by decreased mRNA expression and TNF-alpha values in the culture supernatants, but also with an impaired production of other cytokines and secondary messages such as IFN-gamma and neopterin. PTX treatment, however, did not affect IFN-alpha or IL-1 beta production, and IL-6 release was even increased. PTX, therefore, has profound immunomodulatory properties in vitro, which are associated with selective inhibition of cytokine release and can be enhanced by the addition of mAbs against TNF-alpha, but not reversed by the addition of rTNF-alpha.

Biopterins↗
PubMed1993

Circulating interleukin-1 and tumor necrosis factor antagonists in liver disease.

The proinflammatory cytokines interleukin-1 and tumor necrosis factor-alpha are thought to play important roles in the pathophysiology of liver disease. Specific antagonists of these cytokines have been found in recent years. Interleukin-1 receptor antagonist is a specific interleukin-1 antagonist. The soluble receptor derived from the cell-surface p55 tumor necrosis factor receptor p55 is a naturally occurring substance that inhibits the biological effects of tumor necrosis factor. We used specific radioimmunoassays to detect circulating interleukin-1 receptor antagonist and tumor necrosis factor soluble receptor p55 levels in 14 patients with acute viral hepatitis and in 160 patients with various chronic liver diseases. Levels of interleukin-1 receptor antagonist and, especially, tumor necrosis factor soluble receptor were markedly increased in most patients with chronic liver disease regardless of pathogenesis and in viral hepatitis. Patients with chronic liver disease and cirrhosis showed significantly higher levels of both cytokine antagonists than did noncirrhotic patients. Correlations between interleukin-1 receptor antagonist and tumor necrosis factor soluble receptor were more significant than those of either antagonist with C-reactive protein or blood sedimentation rate. Interleukin-1 receptor antagonist and tumor necrosis factor soluble receptor levels were also positively correlated with bilirubin and AST levels. We conclude that circulating levels of interleukin-1 receptor antagonist and tumor necrosis factor soluble receptor may reflect ongoing disease activity and probably modulate some effects of endogenous interleukin-1 and tumor necrosis factor.

Adult↗
PubMed1992

Serum levels of cytokines in chronic liver diseases.

Serum levels of interleukin-1 (IL-1 beta), interleukin-6 (IL-6), tumor necrosis factor alpha (TNF-alpha), interferon gamma (IFN-gamma), and C-reactive protein (CRP) were investigated in patients with chronic liver diseases (CLD) and correlated with the type of underlying disease and various clinical and laboratory parameters. Two hundred sixty-four patients suffering from various CLD were studied; 136 cases presented with liver cirrhosis, and 128 patients were in the noncirrhotic stage of their underlying liver diseases. Serum levels of IL-1 beta, IL-6, TNF-alpha, IFN-gamma, and CRP were elevated in patients with CLD. Endogenous cytokine patterns in CLD were stage dependent and only marginally affected by the type of underlying disease. The cirrhotic group of CLD patients showed higher serum levels in IL-1 beta, IL-6, TNF-alpha, and CRP than did noncirrhotic cases, and these differences reached the level of statistical significance. IL-1 beta and TNF-alpha values were closely correlated but did not correlate with IL-6 levels. Elevated concentrations of cytokines represent a characteristic feature of CLD regardless of underlying disease. This and the apparent stage-dependency suggest that enhanced endogenous cytokine levels represent a consequence of liver dysfunction rather than of inflammatory disease.

Adolescent↗
PubMed1992

Interleukin-8 serum concentrations after liver transplantation.

The study's objective was to investigate serum levels of interleukin-8 (IL-8) after liver transplantation and to correlate these findings with tumor necrosis factor alpha serum levels and various clinical parameters. This was a prospective observation study conducted at the University Hospital of Innsbruck with 19 patients studied after orthotopic liver transplantation. Serum levels of IL-8 were analyzed by a solid-phase double ligand ELISA method. Serum TNF-alpha concentrations were measured by means of a commercially available radio immunoassay (IRE-Medgenix, Fleurus, Belgium). Three patients with an uneventful recovery after transplantation showed IL-8 levels below the detection limit. IL-8 serum levels markedly increased in patients with acute graft rejection, bacterial infection, and CMV disease. Increments of serum IL-8 preceded clinical complications in all patients. Highest levels were observed in bacterial infection, lowest in acute rejection. A statistically significant positive correlation was demonstrated between IL-8 and TNF-alpha serum levels in the context of bacterial infection and CMV disease. Elevated IL-8 serum levels represent a feature of alloimmune and infectious complications following liver transplantation. IL-8 can thus be considered a further indicator molecule in the heterogenous group of acute-phase reactants that accompany various inflammatory responses and do not permit the underlying clinical complication to be specified.

Adult↗