The hepatic asialoglycoprotein receptor selectively binds to some endogenous tissues.

The hepatic asialoglycoprotein receptor (ASGP-R) was isolated from various rat tissues or freshly prepared single cell suspensions and tested for the binding to endogenous tissues or specific cell types by indirect immunofluorescence. Inhibition with N-acetyl-D-galactosamine demonstrated specificity of binding. ASGP-R binds to mesodermal tissues and to selected cells of the majority of glandular tissues but not to lining epithelia. ASGP-R stains heart muscle but not skeletal muscle. In addition, ASGP-R stains spleen cells (52%), bone marrow cells (55%), thymocytes (62%), and a fraction of peripheral blood lymphocytes (29%), which was identified as B-lymphocytes. Five different rat tumors also showed binding of ASGP-R. The binding pattern and staining intensity of peanut agglutinin and soybean agglutinin were strikingly different although the binding specificity of these lectins is related to the ASPG-R. It is concluded that considerable numbers of endogenous binding sites for the hepatic ASGP-R exist in normal tissue, even on cells which pass the liver on circulation.

Human asialoglycoprotein receptor as an autoantigen in chronic hepatitis.

ASGPR may play a role in the pathogenesis of autoimmune chronic liver diseases. Several lines of evidence support this hypothesis. Antibodies to rabbit ASGPR could be found in various inflammatory liver diseases. In contrast, ASGPR preparations derived from human liver (h-ASGPR) were recognized predominantly by sera from patients with ai-CAH. Moreover, anti-h-ASGPR showed a close correlation to the inflammatory activity of ai-CAH both in terms of prevalence (88% in histologically proven active diseases), immunoglobulin class (IgM antibodies restricted to active inflammation) and behavior during treatment. Anti-h-ASGPR secretion could also be found in vitro, when PBL of patients were stimulated in cell culture. Anti-h-ASGPR antibodies did not correlate with a subgroup of ai-CAH; they also occurred in nearly 15% of patients with PBC. Other inflammatory liver diseases, as well as nonhepatic autoimmune disorders, seldom exhibited anti-h-ASGPR (less than 5%). Additionally, PBL and T-cell clones obtained from liver biopsies in patients with ai-CAH and PBC responded to h-ASGPR. Liver-infiltrating T cells were predominantly of CD4 phenotype and HLA class II restricted. Thus, the human ASGPR has been shown to represent a common target for humoral and cellular autoimmune response in chronic hepatitis probably contributing to disease induction or perpetuation.

Successful sealing of benign esophageal leaks after temporary placement of a self-expanding plastic stent without fluoroscopic guidance.

INTRODUCTION: We report on our experience with the temporary use of a self-expanding plastic stent (SEPS) in the treatment of non-malignant esophageal leaks. MATERIAL AND METHODS: Between November 2001 and May 2005 ten patients with iatrogenic esophageal perforations (n = 4), post-surgical leaks (n = 5) and esophago-mediastinal fistulas after caustic injury (n = 1) were treated by temporary SEPS placement. In eight out of ten patients SEPS placement was done without fluoroscopy due to the emergency setting. Stent removal was performed with a rat-toothed forceps. RESULTS: Leaks were located in the proximal (n = 1), middle (n = 6) and distal (n = 3) parts of the esophagus. The mean leakage size was 2 cm. Stent placement without fluoroscopy was always successful. The median duration of stent therapy was 55.5 days (range 15,438). In 7/10 cases the SEPS was readily removed, showing complete healing of the former leak. Four patients died during the follow-up. However, their deaths were not related to the stent therapy. DISCUSSION: The temporary use of the SEPS represents a safe method for sealing benign esophageal leaks. In the emergency-setting SEPS placement without fluoroscopy is feasible and the stent can be easily removed. In contained perforations without severe mediastinitis of the mid esophagus the SEPS should be discussed as a gentle first-line therapy.

Crohn's disease-induced non-alcoholic fatty liver disease (NAFLD) sensitizes for severe acute hepatitis B infection and liver failure.

Non-alcoholic fatty liver disease (NAFLD) commonly is associated with chronic inflammatory bowel disease (CIBD) and usually is considered to be stable and benign. However, NAFLD -- and in particular its subset, non-alcoholic steatohepatitis (NASH) -- may lead to progressive liver disease. Moreover, NAFLD sensitizes the liver to injury and increases the risk of developing acute-on-chronic liver failure following a "third hit". We here present one patient with NASH, as probably induced by long-standing Crohn's disease in the absence of ethanol consumption or abuse. The patient acquired an acute HBV infection and died from complications. As based on the clinical and histological findings, Crohn's disease appears to be a risk factor for developing NAFLD and thus to contribute to the progression into NASH. In conclusion, we suggest that Crohn's disease-related NAFLD may increase the vulnerability of the liver, which indicates that patients with a known history of CIBD merit special attention.

Prospective analysis of eosinophilia in spontaneously diabetic BB rats: correlation with islet inflammation but not with diabetes development.

A prospective analysis of eosinophil counts in diabetes prone BB rats showed that eosinophilia (greater than 5%) occurred between 70-100 days of age. The presence of eosinophilia did not predict diabetes onset because persistently normoglycaemic animals developed eosinophilia as well. Nevertheless a correlation with the disease process in BB rats was found. Eosinophilia decreases a few weeks after diabetes onset but persists in non diabetic rats. Histological analyzes showed that eosinophilia correlates with eosinophil infiltration of islets (p less than 0.005) and the latter correlates with severe insulitis (p less than 0.005). These findings indicate that eosinophilia is associated with a late stage of islet inflammation in diabetes prone BB rats independent of whether the animals develop diabetes or not.

Anti asialoglycoprotein receptor antibodies and soluble interleukin-2 receptor levels as marker for inflammation in autoimmune hepatitis.

Circulating anti asialoglycoprotein receptor antibodies (anti-ASCPR) and soluble interleukin-2 receptor levels (sIL-2R) were blindly determined in sera of 23 patients with autoimmune hepatitis and compared to 18 healthy individuals. All patients underwent liver biopsy which was blindly staged and graded. 14 of 23 (61%) patients but none of normal controls showed anti-ASCPR positivity. Eleven of twelve (92%) patients with biopsy-proven grade 3 hepatitis were high-titered anti-ASCPR positive compared to three of eleven patients with grade I hepatitis. Mean levels of sIL-2R +/- standard deviation were 1.175 +/- 663 units/ml in the total number of patients with auto-immune hepatitis comparing to 372 +/- 69 units/ml in healthy controls (p < 0.001). Eleven of twelve patients with grade 3 hepatitis had significant higher sIL-2R levels (1,669 +/- 559) than patients with mild disease (635 +/- 113). Chi-square analysis demonstrated a significant correlation between positive anti-ASCPR titer and elevated sIL-2R values. A follow-up analysis of six patients showed a significant decrease of both anti-ASCPR titer and sIL-2R levels after three to nine months of immunosuppressive therapy. These findings suggest that elevated sIL-2R levels and anti-ASCPR titer are associated in patients with autoimmune hepatitis and- as a function of either T or B cell activation, respectively- could serve as reliable humoral marker for disease-specific activity.

[Reversible myelofibrosis in angioimmunoblastic lymphadenopathy]. / Reversible myelofibrose bei angioimmunoblastischer Lymphadenopathie.

Ankle oedema and abdominal swelling suddenly developed in a 55-year-old woman who also had lymphadenopathy in the neck, axillae and groin. Ultrasonography demonstrated hepatosplenomegaly, ascites and pleural effusions. Histological examination of some lymph-nodes from the axilla and groin revealed angioimmunoblastic lymphadenopathy (low-malignant peripheral T cell lymphoma). Bone-marrow biopsy was undertaken because of a normocytic anaemia (haemoglobin 4.9 g/dl) requiring blood transfusion, thrombocytopenia (5000/microliters) and monoclonal IgG gammopathy. This showed lymphoma-associated secondary myelofibrosis. Treatment with prednisone (2 mg/kg daily for 8 weeks) and vincristine (1 mg/m2 once weekly for 4 weeks) brought about partial remission of the angioimmunoblastic lymphadenopathy with normalization of the clinical and laboratory findings, the splenohepatomegaly regressed, and there was only a small amount of ascites. Four months after onset of the illness bone-marrow biopsy also showed regression of the myelofibrosis.

Liver-infiltrating T helper cells in autoimmune chronic active hepatitis stimulate the production of autoantibodies against the human asialoglycoprotein receptor in vitro.

Autoantibodies against the human asialoglycoprotein receptor (ASGPR) occur in the sera of patients with autoimmune liver disorders. Liver-infiltrating T cell clones that specifically recognize the ASGPR have been described in patients with autoimmune chronic active hepatitis (AI-CAH) and primary biliary cirrhosis (PBC). Recently, we have shown that peripheral blood mononuclear cells (PBMC) from patients with AI-CAH or PBC but not chronic viral hepatitis secreted anti-ASGPR antibodies in vitro. In this study we characterized the influence of liver-infiltrating T cells on the secretion of ASGPR-specific autoantibodies by autologous B cells in cell culture supernatants. T cell clones from liver biopsies of three patients with chronic autoimmune liver disorders (one with AI-CAH, two with PBC) were isolated and investigated for their proliferative response to soluble ASGPR and their helper function provided to autoantibody-secreting B lymphocytes. PBMC from these patients secreted autoantibodies spontaneously in their cell culture supernatants and showed a proliferative response to ASGPR. T cell-depleted PBMC, however, lacked spontaneous antibody secretion. Four CD4+CD8- liver-infiltrating T cell clones showed a proliferative response to ASGPR and also induced spontaneous anti-ASGPR antibody production in cell culture supernatants when added to autologous T cell depleted PBMC. Activated supernatants of these T cell clones failed to induce antibody production. None of seven CD4+CD8- and two CD4-CD8+ T cell clones non-responding to ASGPR provided this help for antibody secretion. Anti-ASGPR secretion in vitro could not be inhibited by the addition of MoAbs raised against monomorphic determinants on HLA class II molecules. The addition of purified ASGPR or polyclonal-activating pokeweed mitogen showed no influence on the production of autoantibodies in these cultures. These data show that B lymphocytes require T cell help for the production of ASGPR-specific antibodies. This help can be provided by ASGPR-responsive T helper cells via cellular interactions.

Effects of cytokines on synthesis and function of the hepatic asialoglycoprotein receptor.

In this study we have investigated whether cytokines, critical mediators of the immune response, might have a direct effect on the expression and/or function of the human hepatic asialoglycoprotein receptor (ASGPR). Binding and uptake of asialoglycoproteins by the human hepatoma cell line, HepG2, and by freshly isolated rat hepatocytes were inhibited by 50% after 3-6 hours and completely abolished following a 24 hour exposure to tumor necrosis factor (TNF) alpha, interferon (INF) alpha or gamma, or interleukin-2 (IL-2). The loss of ASGPR binding activity mediated by IL-2 was reversible up to 4 hours of exposure and accompanied by the selective phosphorylation of the cell-surface receptor. Steady-state levels of total cellular ASGPR protein remained unchanged over the first 6 hours of IL-2 incubation but declined in a dose dependent manner thereafter. This down regulation of ASGPR expression was due to reduced synthesis as a result of reduced receptor transcript levels. No loss was detected, however, of cell surface-associated receptor protein even after 24 hours of IL-2 incubation, suggesting that cytokine induced phosphorylation constitutes a mechanism to regulate receptor activity.

Recombinant interleukin 2 enhances spontaneous insulin-dependent diabetes in BB rats.

Treatment of BB rats with recombinant interleukin 2 (IL2) enhanced the development of spontaneous diabetes in these animals. A dose of 20 micrograms IL 2/kg body weight was administered twice daily for 80 days starting at 42 days of age. The rate of diabetes was doubled after IL 2 administration (53% vs. 23%) and the onset of diabetes was found to be accelerated by a mean of 18 days. Histological analysis showed enhanced inflammation of islets and in addition interstitial pancreatis. It is concluded that IL 2 has a regulatory effect on spontaneous organ-specific autoimmunity.

Receptor-mediated entry of hepatitis B virus particles into liver cells.

In previous reports several receptors for either natural hepatitis B virus (HBV) particles or genetically engineered virus have been described, whereby endocytosis represents a putative uptake mechanism for HBV particles. We have found that HBV-particles from viremic carriers could bind to the human asialoglycoprotein receptor (ASGPR), which mediates glycoprotein uptake into liver cells. The HBV-ASGPR interaction was studied in a cell culture system using hepatoma HepG2 and HuH7 cells compared to COS cells as controls. About 50% of HBsAg-secretion into the cell culture supernatant after HBV-inoculation as a function of HBV-uptake could be inhibited by the specific ASGPR-ligand asialofetuin. COS-cells did not show HBsAg-secretion. If the cells were grown as clones, 15% of HepG2-cells demonstrated HBsAg-secretion but only 5% in the presence of asialofetuin. HBV-particle uptake was further confirmed by HBV-DNA analysis using PCR. HBV-ASGPR interaction was studied with purified, biotin-conjugated human ASGPR. Quantitative inhibition with asialofetuin indicated a high-affinity binding of HBV-particles to purified ASGPR. After denaturing polyacrylamid gel electrophoresis and transblotting of isolated HBV-particles a receptor-blotting system was established which identified distinct binding sites for biotinylated receptors. These results suggest that the ASGPR is capable of specifically binding HBV-particles and, moreover, to mediate their hepatic endocytosis which ultimately could be responsible for the HBV-infection of liver cells.

[Littoral-cell angioma--a rare differential diagnosis on splenic tumors]. / Uferzellangiom--eine seltene Differentialdiagnose von Milztumoren.

UNLABELLED: HISTORY AND PRE-ADMISSION FINDINGS: Routine abdominal sonography of a 51-year-old man 6 years after removal of the right testis and radiotherapy for a seminoma revealed a 3 cm mass within the spleen. INVESTIGATIONS: All biochemical tests were normal. Computed tomography (CT) and magnetic resonance imaging confirmed the tumour which had not been present on the CT before the seminoma had been treated. No other space-occupying lesions were found in the thorax and abdomen. TREATMENT AND COURSE: A splenectomy was performed because a metachronous metastasis of the seminoma was suspected. The operation and subsequent course were uneventful. At operation the tumour had been diagnosed as an haemangioma because of its gross appearance, but histological and immunohistochemical examination revealed a littoral cell angioma. CONCLUSION: The littoral cell angioma is a benign vascular lesion in the red pulp of the spleen, which may be caused by different stimuli such as chronic infection or tumours. This case illustrates, that this tumour should be considered in the differential diagnosis of an unclear neoplasm in the spleen.

Suppression of spontaneous insulin-dependent diabetes in BB rats by administration of ciamexone.

BB rats spontaneously develop an insulin dependent diabetes which resembles in many features human type I diabetes. We have tested the effect of the immunomodulatory drug Ciamexone, a 2-cyan-aziridine-derivative, on the development of diabetes in BB rats. Ciamexone was given once daily during 6 days per week beginning with the age of 42 or 50 days up to 120 days. For comparison cyclosporin A (10 mg/kg) was applied following the same protocol. At 1 mg/kg ciamexone administration led to complete prevention of diabetes in females but was not beneficial in males. At 10 mg/kg the drug caused significant suppression of diabetes development in males but more pronounced in females. Both, a reduction of the incidence of diabetes and a delay in the onset of hyperglycaemia was observed only in females. After administration of cyclosporin A none of the animals developed diabetes. Ciamexone treatment did not affect granulocyte and lymphocyte counts and subsets in the peripheral blood except for a tendency to suppress eosinophilia. The growth of animals was not retarded. It is concluded that ciamexone seems to influence the autoimmune state of the BB rat resulting in partial suppression of the disease.

The asialoglycoprotein receptor mediates hepatic binding and uptake of natural hepatitis B virus particles derived from viraemic carriers.

As a putative mechanism of hepatitis B virus (HBV) uptake into hepatocytes the interaction between HBV and the hepatic, human-derived asialoglycoprotein receptor (ASGPR) was investigated. Sera from patients with different variations of hepatitis B surface antigen-(HBsAg) positive chronic hepatitis, HBV particles isolated from HBV carriers with high-titre viraemia and commercial HBsAg served as sources of HBV. ASGPR was affinity-purified from human liver. HBV that had bound to isolated ASGPR was either detected by radioimmunoassay using solid-phase bound ASGPR or enzyme immunoassay with biotin-ASGPR bound to immobilized HBV. Furthermore, binding and uptake of purified, 125I-labelled HBV particles into human hepatoma cell lines (HepG2 and HuH7), which constitutively express functional ASGPR molecules, were compared to that of ASGPR-negative COS cells. As a result HBV was found to bind to purified human ASGPR in two different assays. Circulating virus particles from sera with high titre viraemia showed the highest attachment activity to ASGPR. HBV binding to purified ASGPR was saturable and inhibitable by an excess of D-galactose-bearing ligands, by EDTA and anti-receptor immunoglobulin. Lysis of particles by adding detergent abolished immunodetectable HBV binding to purified ASGPR. Commercial HBsAg did not adhere to solid phase-immobilized ASGPR. Monoclonal anti-preS1 antibody (MA18/7) but not anti-preS2 antibody (Q19/10) inhibited virus attachment. Purified and radiolabelled HBV particles showed binding to HepG2 and HuH7 cells but to much lesser degree to COS cells. Cellular binding of HBV was significantly inhibited by blocking of ASGPR function. Both ASGPR ligands and rabbit anti-ASGPR immunoglobulin but not non-immune rabbit serum inhibited uptake of radiolabelled HBV particles into HepG2 cells or HuH7 cells, respectively. This study suggests that HBV virions may enter human hepatocytes via ASGPR molecules by attachment of viral preS1-related envelope binding sites to this receptor.

Interaction of Hypericum perforatum (St. John's wort) with cyclosporin A metabolism in a patient after liver transplantation.

Immunosuppressive therapy in patients after liver transplantation requires careful monitoring of blood levels for immunosuppressive agents such as cyclosporin A. A variety of drugs are capable of interfering with the metabolism of cyclosporin A. We observed a 63-year-old patient who received a liver allograft for cryptogenic liver cirrhosis in 1998. This patient developed severe acute rejection 14 months after transplantation which was associated with a sudden drop in cyclosporin A levels. Two weeks previously, he had started taking the herbal drug Hypericum perforatum (2 x 900 mg/day) for increasing episodes of depression. The cyclosporin A dosage later had to be doubled, which caused some side effects. Finally, an assessment of oral cyclosporin A resorption suggested an enhanced cyclosporin A metabolism. Hypericum perforatum was stopped. Both cyclosporin A dosage and blood levels immediately returned to normal. The liver function recovered completely. In conclusion, this observation is a previously undescribed drug interaction of a widely used herbal drug (Hypericum perforatum, i.e. St. John's wort) in a patient after liver transplantation.

High-yield purification and characterization of human asialoglycoprotein receptor.

The human asialoglycoprotein receptor (ASGPR) represents a major component of the hepatocellular membrane. To study its native composition, approximately 30% of receptor activity from liver specimens was recovered in highly purified ASGPR preparations. Discontinuous, denaturing SDS-gel electrophoresis based on Tris-Tricine buffer indicated the presence of a multimeric ASGPR corresponding to H1 and H2 polypeptides as confirmed by peptide-specific immunoblotting. FPLC-gel filtration of ASGPR preparations revealed a molecular mass for receptor complexes at 150 and 95 kDa, suggesting functional heterotrimers and dimers of H1/H2 subunits. Gel filtration of SDS-denatured protein indicated a single peak at 50 kDa apparently corresponding to dissociated subunits H1 and H2. beta-Mercaptoethanol treatment followed by affinity chromatography separated functionally active and inactive receptors. The H2 subunit was strikingly enriched in the inactive fraction of receptors. Both active and inactive ASGPR preparations consistently showed peaks at 150 and 95 kDa by gel filtration. Receptor activity retained in such heteromers was linked to a lower glycosylation state of ASGPR. These results suggest that native human ASGPR consists of sulfide- and non-sulfide-linked heterotrimers and -dimers from H1 and H2 subunits with a functional restriction to their glycosylation states.

Autoantibodies to human asialoglycoprotein receptor in autoimmune-type chronic hepatitis.

Autoantibodies to the human asialoglycoprotein receptor (anti-h-ASGPR) were studied with a solid-phase ELISA in the sera of 421 patients with inflammatory liver diseases, 288 patients with various other disorders and 31 controls. Anti-h-ASGPR were found predominantly in autoimmune chronic active hepatitis (44 of 88, 50%) and were closely related to inflammatory activity. In a subpopulation of these patients with untreated, biopsy-proven active disease or relapse, 15 of 17 were positive (88%). In contrast, only 11 of 204 patients (5.3%) with viral hepatitis were anti-h-ASGPR receptors-positive (chi 2 analysis; p less than 0.001). We also compared the occurrence of anti-h-ASGPR with antibodies to rabbit and rat asialoglycoprotein receptors in 352 sera. In contrast to the anti-human asialoglycoprotein receptor antibodies (3 of 107), anti-rabbit- or anti-rat-asialoglycoprotein receptor antibodies were found in 21 and 28 of 107 cases of viral hepatitis, indicating that different epitopes were recognized by these sera. In various other diseases anti-human asialoglycoprotein receptor antibodies were rarely found. Some sera from patients with connective-tissue diseases (8 of 73) and primary or secondary liver malignancies (6 of 55) exhibited anti-h-ASGPR. In autoimmune chronic active hepatitis the presence of anti-human asialoglycoprotein receptors did not correlate to other established autoantibody systems. Thus we conclude that anti-human asialoglycoprotein receptor antibodies can serve as diagnostic markers for inflammatory active cases of autoimmune chronic active hepatitis. Immune reactions to the asialoglycoprotein receptor, which is expressed on the hepatocellular membrane as a liver-specific antigen, might contribute to the pathogenesis of autoimmune chronic active hepatitis.