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Biomedical subjects

G Gerken

Publications and source records attributed to G Gerken.

At least 91 records · Page 5Linked to original sources
PubMed1999

HBV-specific immune defect in chronic hepatitis B (CHB) is correlated with a dysregulation of pro- and anti-inflammatory cytokines.

The aim of this study was to examine the immunomodulating effects of rhIL-12 on the immune response induced by hepatitis B virus (HBV) antigens in clinical subgroups of patients with HBV infection. Peripheral blood mononuclear cells (PBMC) of 80 patients were stimulated with HBsAg, HBcAg, pre-S1Ag and tetanus toxoid in the absence or presence of IL-12 (0.01, 0.1 and 1 ng/ml). Stimulation by anti-CD3+ anti-CD28 and lipopolysaccharide (LPS) were used as controls. Proliferation and cytokine production were determined by 3H-thymidine uptake and ELISA after 72 h. After stimulation with HBV antigens only, production of tumour necrosis factor-alpha (TNF-alpha) or IL-10 was observed in all patients, while interferon-gamma (IFN-gamma) was detectable in only 27 patients. After costimulation with IL-12 and HBV antigens, however, large amounts of IFN-gamma were found in all patients, while HBV-induced IL-10 production remained mostly unchanged. When clinical subgroups including patients with compensated liver cirrhosis were compared, PBMC from patients with HBeAg+ hepatitis showed the lowest capacity to produce IFN-gamma after HBV antigen-positive IL-12. These data suggest that the ability of IL-12 to enhance IFN-gamma production against HBV antigens is correlated with the presence of HBeAg and is not impaired in patients with advanced liver disease. In addition, IL-12 and IL-10 production by antigen-presenting cells may be a critical factor that determines the efficacy of the immune response against the hepatitis B virus.

Antigen-Presenting Cells↗
PubMed1998

[The "nutcracker syndrome" of the renal vein (superior mesenteric artery syndrome) as the cause of gastrointestinal complaints].

HISTORY AND CLINICAL FINDINGS: Since the age of 19 a now 22-year-old man had complained of intermittent abdominal pain, irregular stools and paroxysmal tachycardia. The only preceding illness had been a single episode of iron-deficiency anemia. A laparoscopy, done 8 months after the onset of symptoms, had revealed an inflamed Meckel's diverticulum which was surgically removed. After transient improvement the symptoms recurred 5 months postoperatively. On admission to clarify the cause of the symptoms he had discrete abdominal pain on pressure, but physical examination was otherwise unremarkable. INVESTIGATIONS: Routine biochemical tests and endoscopy were normal. Abdominal computed tomography was suspicious of severe narrowing of the left renal artery by a crossing superior mesenteric artery. As a result the left testicular vein and the peripelvic venous network were markedly dilated by retrograde congestion, strongly suggesting the "nutcracker syndrome" of obstruction of the left renal vein. This diagnosis was confirmed by selective renal phlebography and pressure measurement. TREATMENT AND COURSE: The vascular anomaly was corrected surgically by reimplanting the left renal vein into the inferior vena cava 3-4 cm further caudally. The patients has been completely symptom-free since then. CONCLUSIONS: The nutcracker-syndrome is a rare cause of hematuria. The coexistence of this anomaly with gastrointestinal symptoms has not been previously described, but it is likely that congestion of the splanchnic veins by obstruction of the left renal vein was at least partly responsible for them, in view of the postoperative relief.

Abdominal Pain↗
PubMed1998

Tumor necrosis factor alpha promoter polymorphism at position -238 is associated with chronic active hepatitis C infection.

Tumor necrosis factor alpha (TNF-alpha) is involved in the pathogenesis of chronic hepatitis C virus infection. The gene for TNF-alpha is encoded in the major histocompatibility locus (MHC). Two polymorphisms at positions -308 and -238 in the TNF-alpha promoter region might influence TNF-alpha expression. These promoter polymorphisms have been linked previously to a number of infectious diseases. TNF-alpha promoter polymorphisms at positions -238 and -308 were studied by DNA sequencing and sequence-specific oligonucleotide hybridization in 82 individuals with chronic hepatitis C and 99 control subjects. Subjects had been HLA class I and class II typed in a previous study. The frequency of the TNF238.2 promoter allele was significantly higher in the hepatitis C group (18.7%) compared to the controls (3.5%; P < 0.0001; pcorr < 0.009). No significant differences in the frequency of the TNF308.2 allele were observed between patients and controls. The increased frequency of the TNF238.2 allele could not be explained by linkage disequilibrium to HLA-B or -DR genes. These findings show an association between the TNF238.2 promoter variant and chronic active hepatitis C. They suggest that this polymorphism or a linked gene may be a host factor contributing to the development of chronic active hepatitis C.

Alleles↗
PubMed1998

Interleukin 12 enhances deficient HCV-antigen-induced Th1-type immune response of peripheral blood mononuclear cells.

The aim of this study was to examine the possible immunomodulating effects of rhIL-12 on the immune response induced by different hepatitis C virus (HCV) antigens. Freshly isolated peripheral blood mononuclear cells (PBMC) of 33 patients with chronic HCV infection were stimulated with optimal concentrations of antigens from the NS3, NS4, NS5, and core region of HCV in the absence or presence of interleukin-12 (IL-12). Stimulation by alpha-CD3 + alpha-CD28, lipopolysaccharide (LPS), and pokeweed mitogen (PWM) were used as controls. Proliferation and cytokine production were determined by 3H-thymidine uptake and enzyme-linked immunosorbent assay (ELISA) after 72 hr. After stimulation with antigen or antigen + IL-12, increased proliferation and production of interferon-gamma (IFN gamma) and tumor necrosis factor-alpha (TNF alpha) were observed in 23 of the 33 patients. Thus, a separation of the patients into HCV-antigen/IL-12 responders (group 1, n = 23) and HCV-antigen/IL-12 nonresponders (group 2, n = 10) was possible. Lower baseline IL-12- and LPS-induced IFN gamma, TNF alpha, and IL-12 production was observed in group 2 due to a possible dysfunction of accessory cells. Significant antigen-induced Th2-type cytokine (IL-4, IL-10, IL-13) production was not found. According to clinical and serological parameters, group 2 comprised mostly patients with advanced liver disease. These data suggest an HCV-related cellular immune defect in patients with hepatitis C that can be restored in most patients by IL-12.

Cytokines↗
PubMed1998

Interleukin-10 expression is autoregulated at the transcriptional level in human and murine Kupffer cells.

Interleukin 10 (IL-10) is known to downregulate immune responses. The regulation of IL-10 gene expression therefore determines the outcome of local immune reactions. We investigated time course and downregulation of IL-10 production in primary Kupffer's cells (KC), which are known to secrete IL-10 in response to endotoxin challenge. Human and murine KC were isolated by centrifugal elutriation and investigated for IL-10 gene expression by a two-step amplification procedure (reverse transcriptase-polymerase chain reaction [PCR] followed by T7-polymerase chain reaction). We show that IL-10 messenger ribonucleic acid (mRNA) showed a >450 fold increase in KC 2 hours after endotoxin challenge. IL-10 protein release from KC strictly depended on de novo protein synthesis. Endotoxin mediated increase in IL-10 gene expression was downregulated by exogenous (>350-fold reduction of IL-10 mRNA level), as well as endogenous IL-10 protein, showing a negative autoregulatory feedback loop. IL-10 receptor expression was found to be constitutive and functional in KC. Early expression of IL-10 in KC may be of functional relevance to the outcome of immune and inflammatory reactions in the liver sinusoid. The negative autoregulation of IL-10 expression may represent a mechanism to regain a state of functional responsiveness in the microenvironment towards new proinflammatory stimuli. In conclusion, autoregulatory downregulation of IL-10 expression in KC may account for important regulatory steps of local immune response in the liver sinusoid.

Animals↗
PubMed1998

Hepatitis B virus with antigenically altered hepatitis B surface antigen is selected by high-dose hepatitis B immune globulin after liver transplantation.

"Escape" variants of hepatitis B virus (HBV) can cause infection despite previous immunization. These viruses show alterations of the immunogenic major hydrophilic loop of the HBV small surface protein (s-protein). We studied whether HBV "escape" variants were selected in patients with graft infection after liver transplantation for HBV-related diseases who received passive immunoprophylaxis with high-dose polyclonal hepatitis B hyperimmune globulin (HBIG). For that, pre- and posttransplantation sera of 34 patients were analyzed for the occurence of HBV S-gene variants. In addition, binding of in vitro-translated variant s-proteins to HBIG was studied. Variants with exchanges of amino acid (aa) 144 (s144) in HBV genotype A and 145 in genotype D (s145) were found to emerge, persist, and predominate during HBIG, and thus fulfilled criteria of "escape" variants selected. In addition to already-known variants sG145R/K/E, we could demonstrate that newly described variants sX144G and sG145A were antigenically altered and showed impaired recognition by polyclonal HBIG in vitro. Diminished recognition of variant s-proteins correlated with the failure of HBIG to prevent infection of the liver graft with antigenically altered variant HBV Patients infected with "escape" variants s144 or s145 showed a worse clinical outcome compared with the other patients on high-dose, long-term HBIG prophylaxis (44% vs. 23% graft failure caused by HBV infection). Our results suggest that antigenically altered HBV variants s144 and s145 can be selected by HBIG and can influence clinical outcome after liver transplantation.

Adult↗
PubMed1998

[Surgery in hepatitis].

Viral hepatitis belongs to the most important infectious diseases worldwide. More than 300 million chronic HBsAg carriers and chronic HCV carriers exist, respectively. High endemic areas of viral hepatitis are Asia, Africa, Latin America and the Near, Middle and Far East. Viral hepatitis is also very important in health care workers. Today viral hepatitis can be differentiated from type A to type E (G) based on immunological and molecular assays. While enterally transmitted hepatitis type A and type E only induce acute and rare fulminant disease, hepatitis type B, C and D often induce chronic progressive disease including liver cirrhosis with typical complications due to the portal hypertension and with a high rate of association with the development of primary liver cancer (HCC). This review focusses on viral hepatitis-related surgical problems, including liver transplantation.

Hepatic Encephalopathy↗
PubMed1998

Clinical evaluation and applications of the Amplicor HBV Monitor test, a quantitative HBV DNA PCR assay.

Viral load has emerged recently as a reliable marker of disease progression and therapeutic efficacy in chronic infections, including AIDS and hepatitis C. The clinical management of type B hepatitis could also be improved by monitoring viremia levels in patients with chronic liver disease undergoing anti-viral treatment. To address this question we evaluated the performance of a newly developed, quantitative PCR assay (Amplicor HBV Monitor test, Roche Diagnostic Systems) in the assessment of viremia changes over time in a group of 45 patients with chronic active hepatitis (CAH) who received interferon treatment. Of the 45 patients, 14 were HBsAg and anti-HBeAg positive and 31 HBsAg, HBeAg positive. Follow-up extended up to 24 months. An average of ten samples per patient were analyzed for levels of ALT, IgM anti-HBc (Abbott Laboratories), HBV DNA by in-house dot-blot hybridization and hybridization-capture assays (HBV-DNA hybrid capture kit, Murex Diagnostics) and by Amplicor HBV Monitor. A sustained biochemical response was observed at the end of treatment in 12 HBeAg-positive and in seven anti-HBeAg positive patients. This was accompanied by the disappearance of HBeAg and of HBV DNA (hybridization assays) in all cases and by the clearance of IgM anti-HBc in 70% of the cases. Viremia (quantitative PCR assay) became undetectable only in 25-30% of cases and was associated with the loss of HBsAg. A good correlation was observed between the time course of IgM anti-HBc, quantitative PCR and dot-blot hybridization although the latter missed 33% of viremic samples. Together, these results indicate that the Amplicor HBV Monitor test is a robust and standardized assay for quantifying HBV viremia levels in the range from 10(2) to 10(7) copies/ml. Compared to other current markers, viral load may provide additional clinical information by predicting long term virologic response and HBsAg clearance in patients with normal ALT at the end of interferon therapy.

Adult↗
PubMed1998

Impact of HBV, HCV and GBV-C/HGV on hepatocellular carcinomas in Europe: results of a European concerted action.

BACKGROUND/AIMS: To investigate the impact of hepatitis B (HBV) and C (HCV) infections on hepatocellular carcinoma (HCC) in Europe. METHODS: Five hundred and three patients with HCC, from six liver centers, were included. All 503 sera and 80 liver samples were tested for HBV DNA and HCV RNA by polymerase chain reaction. GBV-C/HGV RNA was also tested in 57 sera. RESULTS: HBsAg and anti-HCV were detected in 19% and 40.1% of the patients, respectively. Serum and liver HBV DNA were detected in 82% and 91% of the HBsAg positive subjects. HBV DNA was also detected in the serum and liver of 33% and 47% of HBsAg negative patients. In this group, serum HBV DNA was more prevalent in anti-HBs and/or anti-HBc patients (47.9%), compared to those without any HBV marker (25.1%). HCV RNA was detected in 89% and 7% of anti-HCV positive and negative cases, respectively, HCV 1b being the most prevalent genotype (80%). Coinfection with HBV and HCV was shown in 20.4% of patients, while only 29% had neither HBV nor HCV GBV-C/HGV RNA was detected in only 4/57 sera. CONCLUSIONS: This study offers the first large analysis of HCC in Europe, based on both serology and molecular tests. It demonstrates the major impact of HBV and HCV, but not of GBV-C/HGV, in liver carcinogenesis in Northern as well as Southern Europe. It also stresses the need to use viral genome detection in epidemiological studies when serological tests are negative.

Aged↗
PubMed1998

The cellular immune responses induced in the follow-up of interferon-alpha treated patients with chronic hepatitis C may determine the therapy outcome.

BACKGROUND/AIMS: To study whether the host's immune response determines viral clearance in chronic hepatitis C, virological markers and antigen-specific T cell reactions were analysed in 30 chronic HCV carriers followed up during interferon-alpha therapy, 11 untreated anti-HCV positive individuals and 10 healthy controls. METHODS: Proliferative T helper cell responses to recombinant HCV core and non-structural antigens were monitored by 3H-thymidine uptake assay and compared to quantitative viraemia levels and HCV genotypes. RESULTS: Of the 30 treated patients, six had sustained complete responses (20%), another six were transient therapy responders (20%) and 18 were non-responders (60%). Viral clearance was associated with the HCV genotype 3 and low pretreatment viral load. In a substantial proportion of complete and transient therapy responders, increased NS3-, helicase- and NS4-antigen-specific T cell responses were observed during interferon-alpha therapy. In non-responders and in the later clinical courses of transient therapy responders, core and NS5-specific T cell responses dominated. In addition, 11 untreated anti-HCV antibody positive individuals were studied. Two HCV-RNA negative patients who might have recovered from HCV infection showed strong persistent lymphoproliferative responses to NS3, helicase and NS4 antigens, whereas seven of the nine viraemic patients reacted with HCV core or NS5 antigens. CONCLUSIONS: Interferon-alpha treatment enhances NS3-, helicase- and NS4-antigen-specific T helper cell responses in patients with viral clearance, whereas viral persistence was associated with increased T cell reactivities against core and NS5 antigens. Immunogenetical, immunological and virological factors that may influence differential T cell induction in chronic hepatitis C are discussed.

Adult↗
PubMed1998

A tumor necrosis factor-alpha (TNF-alpha) promoter polymorphism is associated with chronic hepatitis B infection.

Cytokines such as TNF-alpha and interferon gamma (IFN-gamma) are important for the elimination of infected hepatocytes during acute hepatitis B virus (HBV) infection. Two G versus A transitions in the TNF-alpha promoter region at positions -308 and -238 possibly influence TNF-alpha expression. We investigated these TNF-alpha polymorphisms in 71 patients with chronic HBV infection, in 32 subjects that had spontaneously recovered from acute HBV infection, and in 99 healthy controls. The -238 A promoter variant was present in 18 (25%) of 71 patients with chronic HBV infection compared with two (6%) of 32 subjects with acute infection (P<0.04), and seven (7%) of 99 controls (P<0.003). By contrast, the prevalence of the variant at position -308 was similar in all investigated groups. The observed differences could not be explained by linkage disequilibrium to HLA-B or -DRB1* alleles. These findings suggest an association between the TNF-alpha promoter polymorphism at position -238 and the development of chronic HBV infection. This promoter variant appears to be linked to defective viral clearance.

Alleles↗
PubMed1998

IL-10 down-regulates T cell activation by antigen-presenting liver sinusoidal endothelial cells through decreased antigen uptake via the mannose receptor and lowered surface expression of accessory molecules.

Our study demonstrates that antigen-presenting liver sinusoidal endothelial cells (LSEC) induce production of interferon-gamma (IFN-gamma) from cloned Th1 CD4+ T cells. We show that LSEC used the mannose receptor for antigen uptake, which further strengthened the role of LSEC as antigen-presenting cell (APC) population in the liver. The ability of LSEC to activate cloned CD4+ T cells antigen-specifically was down-regulated by exogenous prostaglandin E2 (PGE2) and by IL-10. We identify two separate mechanisms by which IL-10 down-regulated T cell activation through LSEC. IL-10 decreased the constitutive surface expression of MHC class II as well as of the accessory molecules CD80 and CD86 on LSEC. Furthermore, IL-10 diminished mannose receptor activity in LSEC. Decreased antigen uptake via the mannose receptor and decreased expression of accessory molecules may explain the down-regulation of T cell activation through IL-10. Importantly, the expression of low numbers of antigen on MHC II in the absence of accessory signals on LSEC may lead to induction of anergy in T cells. Because PGE2 and IL-10 are released from LSEC or Kupffer cells (KC) in response to those concentrations of endotoxin found physiologically in portal venous blood, it is possible that the continuous presence of these mediators and their negative effect on the local APC may explain the inability of the liver to induce T cell activation and to clear chronic infections. Our results support the notion that antigen presentation by LSEC in the hepatic microenvironment contributes to the observed inability to mount an effective cell-mediated immune response in the liver.

Animals↗
PubMed1998

Viral and host factors in the prediction of response to interferon-alpha therapy in chronic hepatitis C after long-term follow-up.

Acute infection with hepatitis C virus (HCV) develops into a chronic hepatitis in about 50-70% of patients. Treatment of these patients with interferon-alpha (IFN-alpha) results in a sustained long-term response in only 15-20% but causes numerous unwanted side-effects in a higher percentage of patients. The aim of our study was to define host or viral parameters that would allow identification of responders and non-responders to IFN-alpha prior to the onset of treatment. We studied a group of 87 patients suffering from chronic hepatitis C who were treated with IFN-alpha. After long-term follow-up, 18 patients (21%) showed a sustained response to IFN-alpha therapy (normalization of serum transaminases and loss of viral RNA from serum) for up to 7 years after therapy had ceased. By univariate and multivariate analyses, no host factors were found to be predictive of response to therapy. Neither the degree of inflammation or fibrosis in liver biopsy samples obtained before treatment nor immunogenetic factors (major histocompatibility complex II haplotype and tumour necrosis factor-alpha promoter polymorphism) were associated with response to therapy. In contrast, viral parameters showed a strong association with response to therapy. HCV genotype 3 was found significantly more frequently in responders (P = 0.034), and mean HCV RNA concentration was lower in responders (3.1 x 10(4)) than in non-responders (2.5 x 10(5)) (P = 0.01). By multivariate analysis, both HCV genotype and HCV RNA concentration were independent predictors of response to therapy. However, exact prediction of response to treatment for an individual patient was not possible on the basis of pretreatment viral RNA concentration or viral genotype. The best association with response to therapy was found to be clearance of HCV RNA from serum 3 months after the start of treatment (32 of 34 partial and sustained responders vs 0 of 53 non-responders; P = 0.001). In conclusion, determination of pretreatment viral factors, but not host factors, was significantly correlated with treatment response but did not give an accurate prediction for patients, whereas clearance of HCV RNA from serum after 3 months of therapy was predictive of response to therapy.

Adult↗
PubMed1998

Quantification of CD8+ T lymphocytes responsive to human immunodeficiency virus (HIV) peptide antigens in HIV-infected patients and seronegative persons at high risk for recent HIV exposure.

The combination of a tumor necrosis factor (TNF)-alpha enzyme-linked immunospot (ELISPOT) assay and computer-assisted video image analysis was used to detect and quantitate in peripheral blood CD8+ T cells reactive with known human immunodeficiency virus type 1 (HIV-1) peptide antigens presented by HLA-A2 or HLA-A3. T lymphocyte responsiveness to at least one HIV peptide was found in 10 (83%) of 12 HIV-1-infected patients and in 5 (45%) of 11 persons who had no serologic and virologic signs of HIV infection but who were at high risk for recent sexual exposure to HIV-1. CD8+ T cells responding to HIV-1 peptides were observed in none of 11 HIV-seronegative donors without a history of HIV exposure. ELISPOT assays are relatively fast and easy to perform and appear to reliably detect T cell reactivity due to previous exposure to HIV. These findings support the use of the ELISPOT assay for monitoring T cell responsiveness to HIV peptides.

Antigen Presentation↗
PubMed1998

Quantitative and functional analysis of core-specific T-helper cell and CTL activities in acute and chronic hepatitis B.

AIMS/BACKGROUND: CD4+ T-helper cell (Th) responses to hepatitis B virus (HBV) core antigen (HBc) are increased during exacerbations in acute and chronic hepatitis B (AHB, CHB) and might influence the induction of CD8+ cytotoxic T lymphocytes (CTL) that are important for viral clearance. METHODS: HBc-specific proliferative responses and cytokine release of blood mononuclear cells (PBMC) were studied in patients with AHB or CHB, as well as responders and non-responders to interferon-alpha treatment (IFN-R, IFN-NR), by [3H]-thymidine-uptake, enzyme-linked immunosorbent assay (ELISA) and Elispot assay and were compared to peptide HBc18 27-specific CTL precursor frequencies among CD8+ T cells derived from HLA-A2+ patients. RESULTS: HBc-specific proliferative PBMC responses and Th frequencies were significantly increased in AHB patients compared with untreated CHB patients. PBMC derived from IFN-R showed stronger cellular responses than IFN-NR. Stimulated PBMC from all patient groups secreted significantly more IFN-gamma than IL-4 indicating Th1/Th0 cell responses. Furthermore, in AHB and IFN-R patients, high peptide HBc18-27-specific CTL precursor frequencies closely correlated with strong HBc-specific Th responses, whereas in untreated CHB and IFN-NR patients lower CTL frequencies were observed without correlation to Th activities. CONCLUSIONS: HBV core-specific Th-cell responses appeared to support efficient CTL induction in patients with viral clearance, whereas in chronic HBV carriers quantitatively insufficient Th and CTL responses were observed. This observation could be important for future therapeutic strategies.

Acute Disease↗
PubMed1998

No association between mannose-binding lectin alleles and susceptibility to chronic hepatitis B virus infection in German patients.

Variants of the mannose-binding lectin (MBL) have been shown to be associated with low serum concentrations of the protein and to predispose to bacterial, fungal and viral infections. A recent small study on 33 Caucasian patients had suggested that a mutation at codon 52 of the MBL gene is associated with chronic hepatitis B virus (HBV) infection. Exon 1 of the MBL gene was amplified by PCR in 61 patients with chronic HBV infection, 28 patients with acute infection and in 60 controls. MBL variants were detected by subsequent restriction enzyme digestion and agarose gel electrophoresis. The occurrence of the codon 52 mutation in patients with chronic HBV infection did not differ significantly from that in controls or patients with acute infection (9 vs. 7%), nor were there any significant differences for the codon 54 mutation. The frequency of MBL variants at codon 52 and 54 is not increased in patients with chronic HBV infection. Thus, the previously reported association of MBL deficiency with chronic HBV infection in adults could not be confirmed.

Acute Disease↗