Helicobacter pylori infection does not correlate with plasma ammonia concentration and hepatic encephalopathy in patients with cirrhosis

BACKGROUND/AIMS

In patients with cirrhosis, infection of the stomach with Helicobacter pylori may increase ammonia production and, consequently, the incidence of hepatic encephalopathy. To test this hypothesis a retrospective analysis was performed in patients with a transjugular intrahepatic portosystemic shunt. These patients are regarded to be ideal candidates for such a study since they have a high bioavailability of gut-derived ammonia and many of them develop spontaneous hepatic encephalopathy.

METHODOLOGY

In 132 patients (Child-Pugh class A: 24%, B: 49%, C: 27%) with stable transjugular intrahepatic portosystemic shunt function for more than 3 months (mean follow-up: 15.5 +/- 10.8 months) the diagnosis of H. pylori infection was established by a specific and sensitive immunoblot assay for IgG- and IgA-antibodies. During follow-up, hepatic encephalopathy was assessed by clinical examination and a structured questionnaire. Venous plasma ammonia concentration was measured at the time of antibody determination (end of study period).

RESULTS

Eighty-four patients (64%) had negative and 48 patients (36%) had positive immunoblots for H. pylori. The groups were comparable with respect to age, gender, etiology of cirrhosis, Child-Pugh class, follow-up after transjugular intrahepatic portosystemic shunt, and shunt function. The ammonia concentrations of the patients without (group 1) and with antibodies against H. pylori (group 2) were 73 +/- 27 and 69 +/- 28 mumol/L (mean +/- SD), respectively. Hepatic encephalopathy occurred in 23 of 84 patients (27%) of group 1 and in 11 of 48 patients (23%) of group 2.

CONCLUSIONS

A positive immunoblot for H. pylori antibodies neither correlates with plasma ammonia concentration nor with the incidence of hepatic encephalopathy in patients with cirrhosis of the liver and portosystemic shunt.

Hepatocellular carcinoma: susceptibility markers

Genetic polymorphisms of the carcinogen-metabolizing enzymes cytochrome P450 (CYP), glutathione S-transferase (GST) M1 and N-acetyltransferase (NAT2) as well as p53 polymorphisms have been studied experimentally as susceptibility markers for hepatocellular carcinoma development in hepatocellular carcinoma cell lines and in mouse hepatocellular carcinomas. In addition, these susceptibility markers have been studied in hepatocellular carcinoma patients, in the context of coexisting alcohol consumption, smoking and/or HBV infection. To date, there is no clear evidence that susceptibility markers have an overall impact on hepatocarcinogenesis, but in subgroups of individuals, such as smokers, susceptibility markers are emerging indicators for hepatocellular carcinoma risk definition.

Trypsinogen gene mutations in patients with chronic or recurrent acute pancreatitis

Three-point mutations (R117H, N211, A16V) within the cationic trypsinogen gene have been identified in patients with hereditary pancreatitis (HP). A genetic background has also been discussed for idiopathic juvenile chronic pancreatitis (IJCP), which closely mimicks the clinical pattern of HP, and alcoholic chronic pancreatitis because only a small number of heavy drinkers develop pancreatitis. This prompted us to screen 104 patients in our well-defined pancreatitis cohort for the currently known cationic trypsinogen gene mutations. The R117H mutation was detected in seven patients (six patients of two clinically classified HP families, one patient with clinically classified IJCP) and the A16V mutation in one IJCP patient. No cationic trypsinogen gene mutations were found in the remaining 96 patients with chronic and recurrent acute pancreatitis of various etiologies. Our results demonstrate the need for genetic testing to exclude HP, particularly in the presence of an atypical or unknown family history. In addition, cationic trypsinogen gene mutations are no predisposing factor in patients with chronic and recurrent acute pancreatitis of different etiologies.

[DNA vaccination]

DNA vaccination is based on the observation that plasmid DNA could directly transfect muscle cells, dendritic cells, and other cell types in vivo. Intramuscular, intraepidermal, or oral application of expression plasmids can induce humoral and cellular immune responses against the encoded proteins. This strategy has now been used to elicit protective antibody and cellular immune responses in a wide variety of preclinical animal models for viral, bacterial, parasitic, and malignant diseases. DNA vaccination is particularly useful for the induction of cytotoxic T cells and may, therefore, have therapeutic potential as well. This was recently demonstrated in an animal model of tuberculosis. Early phase human trials are in progress. The results from these trials may be eagerly awaited.

[Molecular aspects of hepatocellular carcinoma]

Hepatocellular carcinoma (HCC) is one of the most common malignant tumors worldwide. The major risk factors for HCC development are now well defined and some of the multiple steps involved in hepatocarcinogenesis have been elucidated in recent years. However, no clear picture of how and in what sequence these factors interact at the molecular level has emerged yet. Malignant transformation of hepatocytes may occur as a consequence of various etiologies, such as chronic viral hepatitis, alcohol, and metabolic disorders, in the context of increased cellular turnover induced by chronic liver injury, regeneration and cirrhosis. Activation of cellular oncogenes, inactivation of tumor suppressor genes, overexpression of certain growth factors, and possibly telomerase activation and DNA mismatch repair defects may contribute to the development of HCC. Finally, aflatoxins have been shown to induce specific mutations of the p53 tumor suppressor gene, thus pointing to the contribution of environmental factors to tumor development at the molecular level.

Mouse alpha-fetoprotein-specific DNA-based immunotherapy of hepatocellular carcinoma leads to tumor regression in mice

BACKGROUND & AIMS

alpha-Fetoprotein (AFP) is a tumor-associated protein that is frequently expressed at high levels in hepatocellular carcinoma (HCC). The aim of the study was to characterize self-reactive cytotoxic T lymphocytes (CTLs) directed against murine AFP (mAFP) after DNA-based immunization in mice.

METHODS

To study CTL responses, mAFP-expressing recombinant vaccinia viruses were generated. An HCC tumor model was established in C57L/J mice by injection of syngeneic endogenously mAFP-expressing Hepa1-6 cells.

RESULTS

Gene gun and intramuscular coimmunizations of DNA expression vectors encoding mAFP with plasmids encoding murine interleukin (IL)-12, granulocyte-macrophage colony-stimulating factor, or IL-18 induced weak CTL activity against mAFP in different mouse strains. Some mice developed anti-mAFP antibody responses, suggesting breaking of immunologic ignorance. No hepatocyte damage was detectable despite low-level endogenous hepatic mAFP expression. Therapeutic immunizations of mice bearing mAFP-expressing murine HCCs induced partial regression of tumors. A significant survival benefit was observed in mice immunized with mAFP expression vector DNA but not in untreated mice or in mice immunized with mock/cytokine plasmid DNA.

CONCLUSIONS

The data show that AFP may be used as a potential self tumor antigen to induce CTL and CD4(+) T cell-mediated regression of AFP-expressing HCC by DNA-based immunization.

Percutaneous radio-frequency thermal ablation of nonresectable hepatocellular carcinoma after occlusion of tumor blood supply

PURPOSE

To evaluate the usefulness of percutaneous radio-frequency (RF) thermal ablation of nonresectable hepatocellular carcinoma (HCC) after occlusion of the tumor arterial supply.

MATERIALS AND METHODS

Sixty-two patients with cirrhosis and biopsy-proved HCC underwent RF ablation after interruption of the tumor arterial supply by means of occlusion of either the hepatic artery with a balloon catheter (40 patients) or the feeding arteries with gelatin sponge particles (22 patients).

RESULTS

After a single RF procedure in 56 patients and after two procedures in six patients, spiral computed tomography (CT) demonstrated a nonenhancing area corresponding in shape to the previously identified HCC, which was suggestive of complete necrosis. No major complications occurred. Two patients subsequently underwent surgical resection; the remaining 60 patients were followed up with spiral CT. During a mean follow-up of 12.1 months, 11 HCC nodules showed areas of local progression; 49 were identified as nonenhancing areas with a 40%-75% reduction in maximum diameter. The 1-year estimate of failure risk was 19% for local recurrence and 45% for overall intrahepatic recurrence. The estimated 1-year survival was 87%. Histopathologic analysis of one autopsy and two surgical specimens revealed more than 90% necrosis in one specimen and 100% necrosis in two.

CONCLUSION

HCC nodules 3.5-8.5 cm in diameter can be ablated in one or two RF sessions after occlusion of the tumor arterial supply.

[Pancreatic and biliary tract tumors--diagnosis: ultrasonic diagnosis--endosonography]

Pancreaticobiliary tumors are mostly adenocarcinomas with a poor 5-year survival of less than 2%. Early diagnosis of resectable tumors improves outcome. Conventional ultrasound (US) is non-invasive and is the first modality employed on suspicion of these tumors. With adequate skills and equipment, pancreatic tumors from 1.5 cm in diameter can be detected. By contrast, US is less sensitive in the detection of lymph node involvement and infiltration of blood vessels. Depending on the location tumors of the biliary tract appear as a mass lesion intrahepatically or within the gallbladder. Perihilar and extrahepatic bile duct carcinomas cause proximal duct dilatation which is readily detected by US. Again, sensitivity in the detection of lymph node metastases or portal vein invasion is limited. Endoscopic ultrasound (EUS) has emerged as the method of choice in detecting small pancreatic tumors (e.g. < 2 cm in diameter). An accuracy of over 90% in T-staging and blood vessel infiltration can be achieved whereas lymph node metastases are correctly diagnosed in only 67% of cases. EUS-guided biopsy is readily performed using a curved array scanner. This technique enables neurolysis of the coeliac plexus in patients with heavy pain. EUS adds valuable information in cases of distal extrahepatic bile duct cancer. The role of EUS is limited in perihilar and intrahepatic cholangiocarcinoma. Staging and palliative therapy of perihilar carcinoma is still a domain of endoscopic retrograde cholangiography. Intraductal EUS is restricted to specialized centers and plays no role for routine purposes.

Antibodies against hepatitis C virus-like particles and viral clearance in acute and chronic hepatitis C

We recently described the efficient assembly of hepatitis C virus (HCV) structural proteins into HCV-like particles (HCV-LPs) in insect cells. These noninfectious HCV-LPs have similar morphologic and biophysical properties as putative virions isolated from HCV-infected humans and can induce a broadly directed immune response in animal models. The HCV envelope proteins of HCV-LPs are presumably presented in a native, virion-like conformation and may therefore interact with antienvelope antibodies directed against conformational epitopes. In this study, HCV-LPs were used as capture antigens in an enzyme-linked immunosorbent assay (ELISA) to detect and quantify antibodies against HCV structural proteins in patients with acute and chronic hepatitis C. High titers of anti-HCV-LP antibodies were detected in patients chronically infected with HCV genotypes 1 to 6. In contrast to individuals with chronic hepatitis C, patients with acute self-limited hepatitis C displayed only a transient and weak seroreactivity against HCV-LPs. Patients with chronic HCV infection successfully treated with interferon demonstrated a gradual decline of anti-HCV-LP titers during or subsequent to viral clearance. Sustained interferon responders were characterized by significantly higher pretreatment levels of anti-HCV-LP antibodies as compared with nonresponders (P =.0001). In conclusion, HCV infection is associated with limited humoral immunity against the envelope proteins present on the HCV-LPs. An HCV-LP-based ELISA may be a useful diagnostic tool to distinguish acute hepatitis C from chronic HCV infection with exacerbation, and to predict viral clearance in response to interferon.

Diagnosis of small intestinal bacterial overgrowth in patients with cirrhosis of the liver: poor performance of the glucose breath hydrogen test

BACKGROUND/AIMS

Small intestinal bacterial overgrowth is known to occur in association with cirrhosis of the liver and studies are needed to assess its pathophysiological role. The glucose breath hydrogen test as an indirect test for small intestinal bacterial overgrowth has been applied to patients with cirrhosis but has not yet been validated against quantitative culture of jejunal secretion in this particular patient population.

METHODS

Forty patients with cirrhosis underwent glucose breath hydrogen test and jejunoscopy. Jejunal secretions were cultivated quantitatively for aerobe and anaerobe microorganisms.

RESULTS

Small intestinal bacterial overgrowth was detected by culture of jejunal aspirates in 73% of patients, being associated with age and the administration of acid-suppressive therapy. The glucose breath hydrogen test correlated poorly with culture results, sensitivity and specificity ranging from 27%-52% and 36%-80%, respectively.

CONCLUSIONS

In patients with cirrhosis, the glucose breath hydrogen test correlates poorly with the diagnostic gold standard for small intestinal bacterial overgrowth. Until other non-invasive tests have been validated, studies addressing the role of small intestinal bacterial overgrowth in patients with cirrhosis should resort to microbiological culture of jejunal secretions.

A sphincterotome-based technique for selective transpapillary common bile duct cannulation

BACKGROUND

Endoscopic retrograde cholangiopancreatography (ERCP) requires selective cannulation of the common bile duct and pancreatic duct. Selective common bile and pancreatic duct cannulation with standard techniques can be achieved in most but not all cases even in experienced centers. To facilitate selective cannulation, sphincterotomes can be used.

METHODS

A prospective randomized study aimed at selective deep cannulation of the common bile and pancreatic ducts comparing different ERCP procedures was performed. One hundred patients were randomly assigned to undergo cannulation with a standard catheter or with a guidewire sphincterotome (GS) without guidewire.

RESULTS

The primary success rate of selective common bile duct cannulation was significantly higher in the GS group (84%) as compared with the standard catheter group (62%) (p = 0.023). In patients with primary standard catheter failure, selective common bile duct cannulation was possible in 16 patients using a GS which increased the total success rate in the standard catheter group to 94% (p < 0.001). In GS failures selective common bile duct cannulation was possible in two patients using a standard catheter and increased the total success rate from 84% to 88%. The frequency of postinterventional pancreatitis did not differ significantly between the two groups.

CONCLUSIONS

ERCP using a GS without guidewire has a significantly higher primary success rate for selective common bile duct cannulation then ERCP using a standard catheter. The use of a GS should be considered to optimize selective cannulation of the common bile duct before resorting to precut techniques.

[Hepatocellular carcinoma: percutaneous ethanol injection/transarterial chemoembolization/radiofrequency thermoablation]

In the majority of patients hepatocellular carcinoma (HCC) is associated with liver cirrhosis. Advanced or decompensated liver cirrhosis, comorbidity and multicentricity make 70-80% of HCCs inoperable at the time of diagnosis. Therefore, percutaneous ethanol injection (PEI) and radiofrequency thermal ablation (RFTA) are non-surgical therapeutic options for patients with small HCCs. In patients with advanced tumor stage transarterial chemoembolization (TACE) and its variants showed no survival benefit on the basis of randomized trials. In several studies, however, combined treatment strategies like TACE and PEI or RFTA after occlusion of tumor blood supply in the treatment of advanced HCC seems to result in a survival benefit. All HCC patients should be included in randomized treatment studies.

Ligand-mediated retargeting of recombinant adenovirus for gene transfer in vivo

The development of efficient and safe methods for in vivo gene transfer is central to the success of gene therapy. Recombinant adenoviral vectors, although highly efficient, are limited by the host immune response, potential safety hazards due to obligatory cotransfer of viral proteins, and their broad tissue tropism. Here, we demonstrate in an animal model that host range and tissue tropism of a recombinant adenovirus from a distant species can be modified by complexing adenovirus with a cell-specific ligand. Thus, a replication-deficient lacZ recombinant human adenovirus, which naturally does not infect avian cells, allowed highly efficient and specific gene transfer to the liver of ducks in vivo when complexed with N-acetylglucosamine, a ligand for the chicken hepatic lectin. This combination of ligand-mediated receptor targeting with adenoviral uptake and intracellular processing of a given gene represents a novel approach to gene therapy of inherited and acquired liver diseases.

Expression of hepatitis C virus proteins interferes with the antiviral action of interferon independently of PKR-mediated control of protein synthesis

Hepatitis C virus (HCV) of genotype 1 is the most resistant to interferon (IFN) therapy. Here, we have analyzed the response to IFN of the human cell line UHCV-11 engineered to inducibly express the entire HCV genotype 1a polyprotein. IFN-treated, induced UHCV cells were found to better support the growth of encephalomyocarditis virus (EMCV) than IFN-treated, uninduced cells. This showed that expression of the HCV proteins allowed the development of a partial resistance to the antiviral action of IFN. The nonstructural 5A (NS5A) protein of HCV has been reported to inhibit PKR, an IFN-induced kinase involved in the antiviral action of IFN, at the level of control of protein synthesis through the phosphorylation of the initiation factor eIF2alpha (M. Gale, Jr., C. M. Blakely, B. Kwieciszewski, S. L. Tan, M. Dossett, N. M. Tang, M. J. Korth, S. J. Polyak, D. R. Gretch, and M. G. Katze, Mol. Cell. Biol. 18:5208-5218, 1998). Accordingly, cell lines inducibly expressing NS5A were found to rescue EMCV growth (S. J. Polyak, D. M. Paschal, S. McArdle, M. J. Gale, Jr., D. Moradpour, and D. R. Gretch, Hepatology 29:1262-1271, 1999). In the present study we analyzed whether the resistance of UHCV-11 cells to IFN could also be attributed to inhibition of PKR. Confocal laser scanning microscopy showed no colocalization of PKR, which is diffuse throughout the cytoplasm, and the induced HCV proteins, which localize around the nucleus within the endoplasmic reticulum. The effect of expression of HCV proteins on PKR activity was assayed in a reporter assay and by direct analysis of the in vivo phosphorylation of eIF2alpha after treatment of cells with poly(I)-poly(C). We found that neither PKR activity nor eIF2alpha phosphorylation was affected by coexpression of the HCV proteins. In conclusion, expression of HCV proteins in their biological context interferes with the development of the antiviral action of IFN. Although the possibility that some inhibition of PKR (by either NS5A or another viral protein) occurs at a very localized level cannot be excluded, the resistance to IFN, resulting from the expression of the HCV proteins, cannot be explained solely by inhibition of the negative control of translation by PKR.

[Value of manometry]

Manometry of the esophagus is essential in the diagnostic workup of patients with motility disorders of the esophagus. Before manometry organic diseases causing the symptoms should be excluded by a esophago-gastroscopy and/or a barium swallow meal. Indications for manometry are noncardiac chest pain, dysphagia of unknown origin, primary or secondary motility disorders of the esophagus and preoperative assessment before antireflux surgery.

Human interleukin-6 facilitates hepatitis B virus infection in vitro and in vivo

BACKGROUND AND AIM

Research on hepatitis B virus (HBV) infection in vivo has been limited due to the absence of a suitable animal model. We have developed a human-mouse radiation chimera in which normal mice, preconditioned by lethal total body irradiation and radioprotected with SCID mouse bone marrow cells, are permissive for engraftment of human hematopoietic cells and solid tissues. This resulting human-mouse model, which comprises three genetically disparate sources of tissue, is therefore termed Trimera. This study was aimed at assessing the effect of human IL-6 on HBV infection in vivo in Trimera mice.

METHODS

Trimera mice were transplanted with human liver tissue fragments or with HepG2-derived cell lines, which had been previously infected ex vivo with HBV in the presence or absence of human interleukin-6 (hIL-6) and in the presence of anti-IL-6-neutralizing antibodies.

RESULTS

HBV sequences appeared in the sera of animals in which the liver tissue was incubated with both HBV and hIL-6 prior to transplantation. A similar result was obtained when a human hepatoblastoma cell line (HepG2), expressing the hIL-6 receptor, was infected ex vivo with HBV in the presence of hIL-6 prior to their injection into spleens of Trimera mice. However, when liver fragments were infected ex vivo and simultaneously treated with neutralizing antibodies against hIL-6 or were incubated with HBV prior to transplantation without hIL-6, the rate of mice positive for HBV DNA in their sera was lower. Human mononuclear cells are also permissive for HBV infection in vitro: in the presence of hIL-6 the infection of these cells is enhanced; and this infection is suppressed by the chimeric protein named Hyper-IL-6, generated by the fusion of hIL-6 to the soluble hIL-6 receptor (sIL-6Ralpha, gp80).

CONCLUSION

hIL-6 facilitates HBV infection in vitro and in vivo.

Transport of heptafluorostearate across model membranes. Membrane transport of long-chain fatty acid anions I

Heptafluorostearic acid, an isogeometric derivative of stearic acid, has a pK(a) value of about 0.5. To evaluate the suitability of heptafluorostearate as model compound for anions of long-chain fatty acids in membrane transport, monolayer and liposome studies were performed with lipid mixtures containing phospholipids;-cholesterol-heptafluorostearate or stearate (100:40:20 molar ratios). Transfer of heptafluorostearate and stearate from liposomes to bovine serum albumin (BSA) was followed by measuring the intrinsic fluorescence of BSA. The percentage of heptafluorostearate, equivalent to the amount placed in their outer monolayer, transferred from liposomes (120;-130 nm diameter) to BSA was 55.7 +/- 3.7% within 10 min at 25 degrees C and 55 +/- 2% within 5 min at 37 degrees C. Slow transfer of 22.7 +/- 2.5% of heptafluorostearate at 25 degrees C followed with a half-life of 2.3 +/- 0.4 h and of 20 +/- 4% at 37 degrees C with a half-life of 0.9 +/- 0.1 h until the final equilibrium distributions between BSA and liposomes were reached, 79 +/- 6% to 21 +/- 5% at 25 degrees C and 75 +/- 5% to 25 +/- 4% at 37 degrees C. The pseudounimolecular rate constants for flip-flop of heptafluorostearate equal k(FF,25) = 0.24 +/- 0.05 h(-) and k(FF,37) = 0.6 +/- 0.1 h(-), respectively. By comparison, transfer of stearate required only 3 min to reach equilibrium distribution. The difference between heptafluorostearate and stearate may be explained by a rapid flip-flop movement of the un-ionized fatty acids which exist in different concentrations in accordance with their pK(a) values. Half-life of flip-flop of heptafluorostearate makes it suitable to study mediated membrane transport of long-chain fatty acid anions.

Ongoing murine T1 or T2 immune responses to the hepatitis B surface antigen are excluded from the liver that expresses transgene-encoded hepatitis B surface antigen

Different protein- or DNA-based vaccination techniques are available that prime potent humoral and cellular, T1 or T2 immune responses to the hepatitis B surface Ag (HBsAg) in mice. T1 and T2 are immune responses with isotype profile indicating Th1 and Th2 immunoregulation. We tested whether HBsAg-specific immune responses can be established in transgenic mice that express HBsAg in the liver (HBs-tg mice) using either these different vaccination techniques or an adoptive transfer system. HBsAg-specific responses could not be primed in HBs-tg mice with the established, potent vaccine delivery techniques. In contrast, adoptive transfers of T1- and T2-type HBsAg-immune spleen cells into congenic HBs-tg hosts (that were not conditioned by pretreatment) suppressed HBsAg antigenemia and gave rise to HBsAg-specific serum Ab titers. The establishment of continuously rising anti-HBsAg serum Ab levels with alternative isotype profiles (reflecting T1 or T2 polarization) in transplanted HBs-tg hosts required donor CD4+ T cell-dependent restimulation of adoptively transferred immune cells by transgene-derived HBsAg. Injections of HBsAg-specific Abs into HBs-tg mice did not establish stable humoral immunity. The expanding T1 or T2 immune responses to HBsAg in HBs-tg hosts did not suppress transgene-directed HBsAg expression in the liver and did not induce liver injury. In addition to priming functional antiviral effector cells, the conditioning of the liver microenvironment to enable delivery of antiviral effector functions to this organ are therefore critical for effective antiviral defense. A major challenge in the development of a therapeutic vaccine against chronic hepatitis B or C virus infection is thus the efficient targeting of specifically induced immune effector specificities to the liver.