Search PubMed⌕ Search

Biomedical subjects

C Trautwein

Publications and source records attributed to C Trautwein.

At least 73 records · Page 4Linked to original sources
PubMed1999

The designer cytokine hyper-interleukin-6 is a potent activator of STAT3-dependent gene transcription in vivo and in vitro.

Interleukin-6 (IL-6) triggers pivotal pathways in vivo. The designer protein hyper-IL-6 (H-IL-6) fuses the soluble IL-6 receptor (sIL-6R) through an intermediate linker with IL-6. The intracellular pathways that are triggered by H-IL-6 are not defined yet. Therefore, we studied the molecular mechanisms leading to H-IL-6-dependent gene activation. H-IL-6 stimulates haptoglobin mRNA expression in HepG2 cells, which is transcriptionally mediated as assessed by run-off experiments. The increase in haptoglobin gene transcription correlates with higher nuclear translocation of tyrosine-phosphorylated STAT3 and its DNA binding. As H-IL-6 stimulates STAT3-dependent gene transcription, we compared the molecular mechanism between IL-6 and H-IL-6. Transfection experiments were performed with a STAT3-dependent luciferase construct. The same amount of H-IL-6 stimulated luciferase activity faster, stronger, and for a longer period of time. Dose response experiments showed that a 10-fold lower dose of H-IL-6 stimulated STAT3-dependent gene transcription comparable with the higher amount of IL-6. Cotransfection with the gp80 and/or gp130 receptor revealed that the effect of H-IL-6 on STAT3-dependent gene transcription is restricted to the gp80/gp130 receptor ratio. High amounts of gp130 increased and high amounts of gp80 decreased the effect on H-IL-6-dependent gene transcription. To investigate the in vivo effect of H-IL-6 on gene transcription in the liver, H-IL-6 and IL-6 were injected into C3H mice. H-IL-6 was at least 10-fold more effective in stimulating the DNA binding and nuclear translocation of STAT3, which enhances haptoglobin mRNA and protein expression. Thus H-IL-6 stimulates STAT3-dependent gene transcription in liver cells in vitro and in vivo at least 10-fold more effectively than IL-6. Our results provide evidence that H-IL-6 is a promising designer protein for therapeutic intervention during different pathophysiological conditions also in humans.

Animals↗
PubMed1999

Two control elements in the hepatitis B virus S-promoter are important for full promoter activity mediated by CCAAT-binding factor.

Natural occurring mutations in the preS-region are frequently found during chronic hepatitis B virus (HBV) infection. Here we used the mutated preS-region from a patient to study the transcriptional regulation of the S-promoter. The mutations were a CCAAT-box (MUT1) point mutation, a 6-base pair (bp) deletion (MUT2) 3' of the CCAAT-box, and a 153 bp deletion (MUT3) in the preS2 genome. Transfection experiments revealed for MUT1 and 2 30% to 40% and MUT3 75% of the wildtype (wt) S-promoter activity. In electro-mobility shift assays experiments, binding of a nuclear protein was impaired with MUT1. Ultraviolet cross-linking, South-Western, and gel shift experiments revealed a 30- to 40-kd protein interacting with the wt CCAAT-motif. Computer-assisted analysis and supershift experiments showed that CCAAT-binding factor (CBF) is the CCAAT-box binding protein. Cotransfection experiments with expression vectors for dominant-negative CBF or wt CBF showed that the wt S-promoter but not MUT1 could be regulated through CBF. Additionally, the CBF constructs did not modulate the basal activity of MUT2 but changes the activity of MUT3 like wt HBV. Artificial mutations were introduced in the MUT2 reporter constructs. Transfection experiments revealed that wt promoter activity could not be reconstituted. Therefore these experiments indicated the sterical position of CBF being essential for full S-promoter activity. Our study shows that the CCAAT-box and a second region is essential to mediate full S-promoter activity dependent on CBF. As these mutations also lead to retention of S-protein in the endoplasmic reticulum our results indicate that mutational changes in the preS-region might be linked to the progression of HBV-related liver disease.

CCAAT-Enhancer-Binding Proteins↗
PubMed1999

Mutational pattern of hepatitis B virus on sequential therapy with famciclovir and lamivudine in patients with hepatitis B virus reinfection occurring under HBIg immunoglobulin after liver transplantation.

Famciclovir (FCV) and lamivudine (LAM) reduce viral replication in patients with recurrent hepatitis B virus (HBV) infection after orthotopic liver transplantation (OLT). Eighteen of 20 patients with insufficient response to FCV were treated with 100 mg LAM daily after OLT. These patients had shown nonresponse (n = 5), partial response (n = 7), or breakthrough (n = 6) during FCV therapy. Despite passive immunoprophylaxis with hepatitis B immunoglobulin after liver transplantation, HBV reinfection had occurred in 14 of 15 transplanted patients. HBV-DNA levels and the regions A to E of the HBV-DNA polymerase gene were analyzed before and after treatment failure to either therapy. Within 4 weeks on LAM, all but 1 patient showed a 95% average reduction of the HBV-DNA level. As with FCV, we did not observe any severe side-effects attributable to LAM. However, 7 patients developed a breakthrough within 12, 29 (n = 2), 32, 37, 54, and 145 weeks under treatment with LAM associated with the methionine-to-valine signature mutation (M552V) in the YMDD motif in all. With FCV, no unique, but a dominant, resistance pattern with the L528M mutation was identified for patients with breakthrough under FCV. In contrast, nonresponders or patients with partial response to FCV did not exhibit such mutations. Our results indicate that the L528M mutation is a risk factor for LAM breakthrough, because breakthrough during LAM occurred earlier in patients with this mutation (50 +/- 10 weeks vs. 120 +/- 21 weeks). Because breakthrough on either treatment is frequent for this specific group of patients, the use of combination therapy should be explored.

2-Aminopurine↗
PubMed1999

The pre-S region determines the intracellular localization and appearance of hepatitis B virus.

The functional role of the hepatitis B virus (HBV) pre-S region for assembly and appearance of the virus is not completely understood. In this study, 3 natural-occurring mutants were investigated. Three mutants of the pre-S region-a point mutation in the CCAAT box (MUT1), a 6-bp deletion (MUT2) 3' of the CCAAT box, and a 153-bp deletion (MUT3) in the preS2 domain-were cloned alone or in combinations in replication-competent HBV plasmids and transfected in hepatoma cells. The impact on HBV assembly and appearance was studied by Northern Blot, primer extension analysis, immunofluorescence studies, enzyme-linked immunosorbent assay, and electron microscopy. An inversed ratio of pre-S/S mRNA transcripts compared with wild-type (wt) HBV was found when either MUT1 or -2 were included into the plasmid. Intracellular localization with both mutants showed retention of large S-protein in the endoplasmic reticulum and nuclear accumulation of core protein. The extracellular amount of S-protein was reduced with MUT1 and -2 or combinations in which 1 of the mutants was included. However, the extracellular appearance of viral products was comparable with wtHBV. In contrast, MUT3 showed major changes. Virion-like particles had a fried-egg, and filaments a screw-like appearance. The S-promoter mutations MUT1 and MUT2 correlated with viral retention. MUT3 leads to malformed viral particles. Therefore, different regions in the pre-S domain are essential to determine the intracellular localization and extracellular appearance of HBV, and might contribute to the prognosis of chronic HBV infection.

Hepatitis B virus↗
PubMed1999

Differential regulation of extracellular matrix synthesis during liver regeneration after partial hepatectomy in rats.

Little is known about the modulation of the extracellular matrix (ECM) during liver regeneration. We studied the temporospatial expression of procollagens and of matrix metalloproteinases (MMPs) and their physiological antagonists, the tissue inhibitors of metalloproteinases (TIMPs) after two-thirds partial hepatectomy (PH) by Northern blot analysis and in situ hybridization. The entry of hepatocytes into the S-phase at 24 hours after PH was accompanied by a peak (sixfold induction) of hepatic TIMP-1 RNA levels that steadily declined thereafter to reach normal levels 144 hours after PH. Moderate MMP-2 and TIMP-2 RNA levels remained constant up to 144 hours after PH, and MMP-1 and -13 RNA were always undetectable. In situ hybridization showed a dramatic upregulation of TIMP-1 RNA transcripts in mesenchymal cells of portal, perisinusoidal and, to a lesser extent, pericentral areas. In contrast, scattered hepatocytes represented only a minor fraction (below 10%) of TIMP-1 RNA positive cells. When hepatocytes stopped DNA synthesis at 72 hours after PH, an upregulation of procollagen alpha1(I) and alpha2(III) transcripts was observed paralleled by threefold increased PIIINP levels in the sera. Our data reveal a tightly regulated program of de novo matrix synthesis after PH. Whereas interstitial procollagens appear to participate in the induction and maintenance of the quiescent hepatocyte phenotype, the early and localized expression of TIMP-1 indicates a role unrelated to its function as a general MMP-antagonist, e.g., as a growth promoting agent for hepatocytes.

Animals↗
PubMed1999

Enhanced expression of CD80 (B7-1), CD86 (B7-2), and CD40 and their ligands CD28 and CD154 in fulminant hepatic failure.

To define a possible role for changes in the regulation of antigen presentation in fulminant hepatic failure (FHF), we studied the expression of co-stimulatory molecules CD80 (B7-1), CD86 (B7-2), and CD40 along with their ligands CD28 and CD154. We analyzed the liver tissue from patients with FHF (n = 18), chronic liver disease (n = 30), and acute hepatitis (n = 3) and from normal controls (n = 9) by immunohistochemistry and examined the temporal relationship between CD80/CD86 and CD40 expression and disease in the mouse models of galactosamine-lipopolysaccharide and galactosamine-tumor-necrosis-factor-induced FHF. In human controls, faint CD80/CD86 immunoreactivity was restricted to Kupffer cells, and CD40 expression was expressed on bile ducts, macrophages, and sinusoidal endothelial cells (SECs). In FHF, immunoreactivity for CD80 and CD86 was observed on significantly higher numbers of cells, including SECs. Increased CD80/CD86 expression corresponded to increased numbers of CD28-positive lymphocytes. The expression of CD40 was also clearly elevated on virtually all cell types in FHF. In both murine models, CD40 and CD80/CD86 expression was up-regulated before tissue damage could be detected. Our data suggest that up-regulated expression of co-stimulatory molecules might lead to an excessive antigen presentation in FHF as an early step in the pathogenesis before the onset of tissue damage.

Animals↗
PubMed1999

Endogenous serum levels of thrombopoietic cytokines in healthy whole-blood and platelet donors: implications for plateletpheresis.

Serum concentrations of the thrombopoiesis-enhancing cytokines thrombopoietin (TPO), erythropoietin (EPO), interleukin (IL)-6 and IL-11 were determined in 119 healthy whole-blood (WBD) and 101 platelet donors (PD) prior to donation. The 90% TPO reference interval in WBD of 64-867 pg/ml (median 163, 100% range 45-7572) was significantly higher than in PD of 56-524 (median 122, range 44-801, P = 0.004), whereas their platelet counts were lower (P < 0.001). EPO levels were not different (WBD 7.7 +/- 3.8, PD 8.0 +/- 4.9 IU/l), IL-6 and IL-11 were below the detection limit in >/=90% of cases (IL-6 < 3.2 pg/ml, IL-11 < 31.2 pg/ml). None of the cytokines correlated with platelet counts, other blood parameters, or in the PD group with the frequency of platelet donations within the last 6 months. We conclude that plateletpheresis does not lead to a lasting increase of thrombopoietic cytokines and provide reference data for potential platelet mobilization strategies with recombinant growth factors.

Adult↗
PubMed1999

Tumour necrosis factor alpha--mediator of apoptosis and cell proliferation of hepatocytes.

In recent years, the intracellular pathways activated by the tumour necrosis factor have been described in great detail. Adaptor molecules which bind to the intracellular domain of the tumour necrosis factor receptor 1 are able to either induce apoptosis or to activate signals which trigger cell proliferation, anti-apoptotic mechanisms or the inflammatory response of hepatocytes. In different animal model the tumour necrosis factor-dependent mechanisms have been defined. Therefore, the present review deals with the molecular mechanisms of tumour necrosis factor-dependent signalling. Additionally, the role of tumour necrosis factor during liver regeneration after partial hepatectomy and models of tumour necrosis factor-dependent liver cell damage will be discussed.

Animals↗
PubMed1998

Concanavalin A-induced liver injury triggers hepatocyte proliferation.

Concanavalin A (Con A) injection into mice leads to immune-mediated liver injury. We studied whether after Con A-induced liver injury, TNF- and IL-6-dependent signaling pathways known to be related to hepatocyte proliferation are activated. 2 h after Con A injection, maximum TNF-alpha, and after 4-8 h, maximum IL-6 serum levels were found. The rise in aminotransferases and DNA fragmentation started after 4 h; maximum levels were evident after 8 h. 5-Bromo-2'-deoxyuridine staining and nuclear cyclin A expression as markers of the S-phase were first detected in hepatocyte nuclei after 24 h, peaking after 48 h. An increase in TNF-dependent nuclear expression of CCAAT/enhancer-binding protein-beta (C/EBP-beta)/liver-enriched activating protein (LAP) was detected after 1 h, whereas an increase in RNA expression was evident only after 4 h. C/EBP-beta/LAP expression returned to normal values before progression into the S-phase. DNA binding of signal transducer and activator of transcription (STAT) 3/acute phase response factor (APRF) increased for up to 8 h. As found by supershift experiments, in addition to STAT3/APRF, STAT1 also binds to the same sequence. During the course of time gel shift experiments, DNA binding of the apoptosis-related STAT1 started earlier than DNA binding of STAT3/APRF, which regulates hepatocyte proliferation. However, the subsequent decrease in DNA binding of both factors was comparable. This study demonstrates that after Con A injection, TNF- and IL-6- dependent signals trigger nuclear events regulating hepatocyte apoptosis and proliferation during liver injury.

Animals↗
PubMed1998

Analysis of the expression pattern of the latent transforming growth factor beta binding protein isoforms in normal and diseased human liver reveals a new splice variant missing the proteinase-sensitive hinge region.

Latent transforming growth factor beta binding protein (LTBP), a component of the extracellular matrix (ECM) of various tissues, is important for the secretion of TGF-beta and, furthermore, for the storage of TGF-beta in ECM. The proteolytic cleavage of LTBP is assumed to be the prerequisite for the activation of TGF-beta. We investigated the mRNA expression pattern of the three LTBP isoforms (LTBP-1, -2, -3) and the protein distribution of the components of the large latent TGF-beta complex, namely LTBP-1 and -2, latency-associated protein (LAP), and TGF-beta, in human liver using reverse-transcription polymerase chain reaction (RT-PCR) and immunohistochemical alkaline phosphatase anti-alkaline phosphatase (APAAP) staining. Parts of explanted livers diagnosed as hepatitis B, hepatitis C, primary biliary cirrhosis (PBC), and primary sclerosing cholangitis (PSC) and normal liver tissue were examined. LTBP transcripts were detected in the same manner in all liver specimens. Interestingly, we found a new splice variant of LTBP-1 (LTBP-1D), in which the sequence coding for the proteinase-sensitive hinge region is deleted. The corresponding parts of the human LTBP-2 and LTBP-3 cDNA coding for the hinge region were sequenced and show neither similar proteinase cleavage sites nor deleted cDNA sequences. The proposed proteinase cleavage site of mouse LTBP-3 seems not to be conserved in the human LTBP-3 gene. By immunohistochemistry, LTBP-1, -2, and LAP were detectable in normal and diseased livers and showed a different staining pattern for both LTBP isoforms. By contrast, TGF-beta showed a spotted staining pattern in diseased livers only, predominantly in the area of parenchymal cells that are close to fibrotic tissue. This strongly suggests the release of active TGF-beta from preexisting latent complexes. The LTBP-1D splice variant, which is probably less sensitive against proteolytic degradation and therefore may protect TGF-beta from activation, may have importance for modulating the biological activity of TGF-beta in normal and diseased liver.

Amino Acid Sequence↗
PubMed1998

Antibodies against the GB virus C envelope 2 protein before liver transplantation protect against GB virus C de novo infection.

GB virus C (GBV-C) is a newly discovered RNA virus related to the Flaviviridae family. Although GBV-C is not yet associated with any cause of liver disease, a humoral immune response against the GBV-C envelope 2 (E2) protein has been observed. Therefore, we studied the prevalence and clinical relevance of GBV-C RNA and anti-E2 antibodies in patients undergoing orthotopic liver transplantation (OLT). In addition, we tested whether the prevalence of anti-E2 antibodies may protect against GBV-C infection. Of the 182 liver recipients included in this study, 117 of these were evaluated for GBV-C recurrence or de novo infection. GBV-C RNA was detected in sera or plasma using single-tube, reverse-transcriptase polymerase chain reaction, and anti-E2 antibody was detected by enzyme immunoassay (EIA). Cumulative patient and graft survival was tested by using Kaplan-Meier analysis. The independence of prognostic values was assessed by using Cox regression analysis. Before OLT, GBV-C RNA and anti-E2 were detected in 4.0% to 28.6% and 10.0% to 68.8%, respectively, of patients suffering from different forms of chronic liver diseases. GBV-C reinfection after OLT was determined in 85.7%. Of the patients without evidence of exposure to GBV-C before OLT, 30 of 65 (46.2%) became GBV-C RNA positive after OLT. None of the 38 patients who were anti-E2 antibody positive before OLT became GBV-C RNA positive after OLT. Neither patient nor graft survival was significantly affected by the presence of either GBV-C RNA or anti-E2 antibody before OLT. Our data indicate that 1) GBV-C RNA positive patients have a high risk of reinfection after OLT, and 2) the presence of anti-E2 antibodies before OLT is associated with an absence of GBV-C infection after OLT, which may indicate a protective role of anti-E2 antibodies.

Adult↗
PubMed1998

Molecular mechanisms of TNF receptor-mediated signaling.

Tumor necrosis factor alpha (TNF alpha) is a proinflammatory cytokine involved in a variety of physiological and pathological conditions. During the past several years substantial progress has been made toward a better understanding of how a single cytokine is able to exert obviously opposing effects (e.g., apoptosis and growth). This review focuses on the recently discovered TNF-receptor (TNFR)-associated proteins involved in the activation of intracellular signal-transduction cascades. It explains which classes of proteins have been described so far and how these factors are able to mediate different biological functions after TNFR activation.

Animals↗
PubMed1998

Concanavalin A-induced liver cell damage: activation of intracellular pathways triggered by tumor necrosis factor in mice.

BACKGROUND & AIMS: Concanavalin A (con A) induces tumor necrosis factor (TNF)-dependent hepatocyte apoptosis resembling immune-mediated fulminant hepatic failure in humans. Intracellular pathways originating at the TNF receptor are either linked to apoptosis, nuclear factor (NF)-kappaB translocation, or Jun kinase (JNK) activation. The aim of this study was to study TNF-dependent pathways after con A injection in vivo. METHODS: Con A, con A plus anti-TNF, and control buffer were injected into BALB/c mice. Immunofluorescence, Western blot, Northern blot, gel shift, Erk, and JNK activity and DNA fragmentation experiments were performed at different time points after injection. RESULTS: DNA fragmentation in hepatocytes was increased 4-24 hours after con A injection. JNK was activated maximally (>20-fold) directly after con A injection, whereas binding and nuclear translocation of NF-kappaB was maximal after 4 hours. All pathways were blocked by anti-TNF. JNK activation was specific because related ERK 1 + 2 were not activated after con A. High nuclear expression of c-Jun was already evident 1 hour after con A injection; however, in contrast to JNK, anti-TNF treatment did not block c-Jun nuclear expression and DNA binding. CONCLUSIONS: In the con A model, activation of TNF-dependent pathways is associated with apoptosis of hepatocytes. Their modulation in vivo may have implications to develop new therapeutic strategies to prevent apoptosis.

Animals↗
PubMed1998

Influence of arginine, omega-3 fatty acids and nucleotide-supplemented enteral support on systemic inflammatory response syndrome and multiple organ failure in patients after severe trauma.

This study investigated the influence of an enteral diet supplemented with arginine, omega-3 fatty acids, and nucleotides (Impact, Sandoz Nutrition, Berne, Switzerland) on the incidence of systemic inflammatory response syndrome (SIRS) and multiple organ failure (MOF) in patients after severe trauma. Thirty-two patients with an injury-severity score > 20 were included in this prospective, randomized, double-blind, controlled study. Primary endpoints were the incidence of SIRS and MOF. Secondary endpoints were parameters of acute phase and immune response as well as infection rate, mortality, and hospital stay. For statistical analysis 29 patients (test group n = 16, control n = 13) were eligible. In the test group, significantly fewer SIRS days per patient were found during 28 d. The difference was highly significant between d 8-14 (P < 0.001). MOF score was significantly lower in the test group on d 3 and d 8-11 (P < 0.05). Acute phase parameters showed lower C-reactive protein serum levels (significant on D day 4) and fibrinogen plasma levels (significant on d 12 and 14; P < 0.05). HLA-DR expression on monocytes showed significantly higher fluorescence activity on d 7. No significant difference was found for T-lymphocyte CD4/CD8 ratio, interleukin-2 receptor expression, infection rate, mortality (2/16 vs. 4/13), and hospital stay. The results of the study provide further support for beneficial effects of arginine, omega-3-fatty acids and nucleotide-supplemented enteral diet in critically ill patients.

Acute-Phase Reaction↗
PubMed1998

GB virus C/hepatitis G virus infection: a favorable prognostic factor in human immunodeficiency virus-infected patients?

To investigate a possible influence of GB virus C (GBV-C) in immunocompromised patients, the prevalences of GBV-C RNA and anti-E2 antibody in 197 human immunodeficiency virus (HIV)-infected patients and in 120 control blood donors were studied. GBV-C RNA was detected in 33 of 197 HIV-infected patients (16.8%) compared with 1 in 120 blood donors (0.8%) (P < .001). Previous exposure to GBV-C (anti-E2 antibody-positive) was shown in 56.8% of HIV patients and in 9% of blood donors. GBV-C viremia was not associated with hepatitis. Despite approximately equal duration of HIV infection in all subgroups, the CD4 cell counts were significantly higher in GBV-C-viremic patients (344 cells/microL) compared with exposed (259 cells/microL) and unexposed (170 cells/microL) patients (P = .017 and P < .001). Furthermore, Kaplan-Meier analysis demonstrated significantly better cumulative survival in GBV-C RNA-positive HIV-infected patients, suggesting that GBV-C might be a favorable prognostic factor in HIV disease.

AIDS-Related Opportunistic Infections↗
PubMed1998

The mitochondrial permeability transition is required for tumor necrosis factor alpha-mediated apoptosis and cytochrome c release.

This study assesses the controversial role of the mitochondrial permeability transition (MPT) in apoptosis. In primary rat hepatocytes expressing an IkappaB superrepressor, tumor necrosis factor alpha (TNFalpha) induced apoptosis as shown by nuclear morphology, DNA ladder formation, and caspase 3 activation. Confocal microscopy showed that TNFalpha induced onset of the MPT and mitochondrial depolarization beginning 9 h after TNFalpha treatment. Initially, depolarization and the MPT occurred in only a subset of mitochondria; however, by 12 h after TNFalpha treatment, virtually all mitochondria were affected. Cyclosporin A (CsA), an inhibitor of the MPT, blocked TNFalpha-mediated apoptosis and cytochrome c release. Caspase 3 activation, cytochrome c release, and apoptotic nuclear morphological changes were induced after onset of the MPT and were prevented by CsA. Depolarization and onset of the MPT were blocked in hepatocytes expressing DeltaFADD, a dominant negative mutant of Fas-associated protein with death domain (FADD), or crmA, a natural serpin inhibitor of caspases. In contrast, Asp-Glu-Val-Asp-cho, an inhibitor of caspase 3, did not block depolarization or onset of the MPT induced by TNFalpha, although it inhibited cell death completely. In conclusion, the MPT is an essential component in the signaling pathway for TNFalpha-induced apoptosis in hepatocytes which is required for both cytochrome c release and cell death and functions downstream of FADD and crmA but upstream of caspase 3.

Adaptor Proteins, Signal Transducing↗