Immunological significance of cytotoxic T lymphocyte epitope variants in patients chronically infected by the hepatitis C virus.

This study was performed to test the hypothesis that cytotoxic T lymphocyte (CTL) selection of hepatitis C virus (HCV) escape variants plays a role in HCV persistence. The peripheral blood CTL responsiveness of patients with well-established chronic hepatitis C to a panel of 10 prototype HCV peptides (genotype 1a) was compared with the corresponding sequences encoded by the infecting viruses in each patient. Variant viral peptide sequences were threefold more frequent in the presence of a CTL response than in its absence, and CTL responses were detected nearly twice as often in association with variant rather than with prototype viral peptide sequences. Furthermore, over half of the patients were infected with potential CTL escape variants that contained nonimmunogenic and noncross-reactive variant peptides many of which displayed reduced HLA-binding affinity. Surprisingly, follow up analysis over a period of up to 46 mo revealed that, in contrast to the relatively high frequency of escape variants initially observed, the subsequent emergence rate of CTL escape variants was very low. Interestingly, the one escape variant that was detected proved to be a CTL antagonist. Collectively, these observations suggest that CTL selection of epitope variants may have occurred in these patients before their entrance into the study and that it may have played a role in HCV persistence. The low apparent rate of ongoing CTL selection in chronically infected patients, however, suggests that if CTL escape occurs during HCV infection it is probably an early event.

Hepatitis C virus core and E2 protein expression in transgenic mice.

Transgenic mice have been produced that express the hepatitis C virus (HCV) core protein in the liver under the transcriptional control of the mouse major urinary protein promoter. These animals express the full length core protein in cytoplasm of their hepatocytes at levels comparable to those detected in naturally infected patients, without histological or biochemical evidence of liver disease or hepatocellular carcinoma. This contrasts with recent reports that HCV core protein can transform NIH 3T3 cells and cooperates with H-ras to transform primary rat fibroblasts in vitro. Coexpression of HCV core protein in double transgenic mice that replicate the hepatitis B virus (HBV) does not inhibit hepatocellular HBV gene expression or replication, contrary to reports that it inhibits HBV replication in HuH-7 cells after transient transfection in vitro. We have also produced transgenic mice in which a C-terminally truncated (aa384-715) glycosylated HCV E2 protein is expressed in the liver under the transcriptional control of the mouse albumin promoter. Despite the high level expression of HCV E2 protein, no evidence of liver disease was detected in these animals. These results suggest that the HCV core and E2 proteins are not cytopathic for the hepatocyte in vivo, and they represent an initial step in the development of a small animal model of HCV immunopathology.

The hepatitis B virus (HBV) precore protein inhibits HBV replication in transgenic mice.

In this study, we examined the ability of the hepatitis B virus (HBV) precore, envelope, and X gene products to modulate HBV replication in the livers of transgenic mice that replicate the virus. Hepatic HBV replication was not affected by overexpression of the envelope or X gene products when these animals were crossed with transgenic mice that express the corresponding viral genes in the hepatocyte. Overexpression of the precore protein, however, eliminated nucleocapsid particles from the cytoplasm of the hepatocytes and abolished HBV replication without affecting the hepatic steady-state content of pregenomic HBV RNA. These observations suggest that the precore protein can exert a dominant negative effect on HBV replication, presumably at the level of nucleocapsid particle maturation or stability, suggesting an important role for this enigmatic viral protein in the HBV life cycle.

The hepatitis B virus persists for decades after patients' recovery from acute viral hepatitis despite active maintenance of a cytotoxic T-lymphocyte response.

It is widely believed that the hepatitis B virus (HBV) is completely cleared by antiviral antibodies and specific cytotoxic T lymphocytes (CTLs) during acute viral hepatitis. We now demonstrate that traces of HBV are often detectable in the blood for many years after clinical recovery from acute hepatitis, despite the presence of serum antibodies and HBV-specific CTLs, which can be present at acute-stage levels. The strength of the CTL response to HBV following clinical recovery correlates with persistence of HBV DNA. It is of particular interest that HBV-specific CTLs from patients studied up to 23 years after clinical and serological recovery expressed activation markers (HLA-DR, CD69) indicating recent contact with antigen. These results suggest that sterilizing immunity to HBV frequently fails to occur after recovery from acute hepatitis and that traces of virus can maintain the CTL response for decades following clinical recovery, apparently creating a negative feedback loop that keeps the virus under control, perhaps for life.

[Complete neurologic recovery after prolonged cardiac arrest caused by refractory ventricular fibrillation. Clinical case]. / Completo recupero neurologico dopo arresto cardiaco prolungato da fibrillazione ventricolare refrattaria. Caso clinico.

The clinical case of a 45-year-old patient referred to us for chest pain and with clinical examination and ECG negative for ischaemic damage, is reported. The patient, hospitalised in a bed without an ECG monitor, presented heart failure due to ventricular fibrillation. He was re-examined first with ventilation and EMC and then with defibrillation. Reanimation continued for about 70 minutes. Administration of high doses of adrenalin (0.2 mg/kg) and 9 defibrillations failed to resolve the refractory VF; nor did i.v. lidocaine administration resolve the situation. Echocardiogram did not reveal cardiac tamponade. Administration of 4 g of magnesium sulphate followed by adrenalin and defibrillation, led to asystole with subsequent restoration of sinus rhythm. The patient was then transferred to Intensive Care where he was sedated and curarized for 48 hours. The clinical course was characterised from the start by positive aspects that excluded the need to carry out instrumental investigations such as evoked somatosensory potentials, in the formulation of a prognosis. The patient was transferred to the Hospital Cardiology Unit 72 hours after admission. Two weeks later the patient was discharged with a complete recovery of neurological functions and with no metabolic or thoracopulmonary changes. It can be concluded from this experience that prognosis during CPR may not be reliable. So the factors that should lead us to carry out prolonged reanimation are the age of the patient, his pre-existing clinical conditions, the speed of our actions and correct performance of reanimation.

Hepatitis B virus (HBV) sequence variation of cytotoxic T lymphocyte epitopes is not common in patients with chronic HBV infection.

It has been suggested that immune selection pressure exerted by the cytotoxic T lymphocyte (CTL) response could be responsible for viral persistence during chronic hepatitis B virus infection. To address this question, in the current study we compared the DNA and amino acid sequences of, and the CTL responses to, multiple HLA-A2-restricted CTL epitopes in the hepatitis B virus in several HLA-A2-positive patients with acute and chronic hepatitis. Our results indicate that the CTL response to these epitopes is barely detectable in the majority of patients with chronic hepatitis. Further, we show that the weak CTL response is not secondary in infection by mutant viruses lacking these epitopes, and we show that the CTL response did not select for escape mutants in any of these patients. We conclude that an ineffective hepatitis B virus specific CTL response is the primary determinant of viral persistence in chronic hepatitis and that immune selection of viral variants is not a common event in the majority of patients.

Cytotoxic T lymphocyte response to hepatitis C virus-derived peptides containing the HLA A2.1 binding motif.

The HLA class I-restricted cytotoxic T lymphocyte (CTL) response is a major defense mechanism in viral infections. It has been suggested that the CTL response may contribute to viral clearance and liver cell injury during hepatitis C virus (HCV) infection. To test this hypothesis requires an understanding of the characteristics of HCV-specific cytotoxic effector cells and identification of the target antigens to which they respond. To begin this process we stimulated peripheral blood mononuclear cells (PBMC) from a group of HLA-A2 positive patients with chronic hepatitis C with a panel of 130 HCV-derived peptides containing the HLA-A2 binding motif. Effector cells were tested for their capacity to lyse HLA-A2-matched target cells that were either sensitized with peptide or infected with a vaccinia virus construct containing HCV sequences. Using this approach we have identified nine immunogenic peptides in HCV, three of which are derived from the putative core protein, three from the nonstructural (NS) 3 domain, two from NS4 and one from NS5. Selected responses were shown to be HLA-A2 restricted, mediated by CD8+ T cells and to recognize endogenously synthesized viral antigen. Unexpectedly, peptide-specific CTL responses could also be induced in sero-negative individuals, suggesting in vitro activation of naive CTL precursors. The precursor frequency of peptide-specific CTL was 10 to 100-fold higher in infected patients compared to uninfected controls, and the responses were greatly diminished by removal of CD45 RO+ (memory) T cells. Further quantitative studies are clearly required to establish whether a correlation exists between the HCV-specific CTL response and the clinical course of this disease. Definition of the molecular targets of the human CTL response to HCV creates this opportunity, and may also contribute to the development of a T cell-based HCV vaccine.

Hepatitis B virus persistence after recovery from acute viral hepatitis.

Contrary to current opinion, the disappearance of hepatitis B surface antigen (HBsAg) from the serum, the development of anti-HBs antibodies, and normalization of liver function may not reflect complete virological recovery from acute hepatitis B virus (HBV) infection. By using the polymerase chain reaction (PCR), in the current study we demonstrate long-term persistence of HBV DNA in the serum and peripheral blood mononuclear cells (PBMC) of four patients for up to 70 mo after complete clinical, biochemical, and serological recovery from acute viral hepatitis. Serum HBV DNA reactivity co-sedimented with HBsAg in sucrose gradients, and it displayed the size and density characteristics of naked core particles and intact HBV virions, presumably contained within circulating immune complexes in these anti-HBs antibody-positive sera. HBV DNA was also present in PBMC in late convalescent samples from all four patients, and HBV RNA was detected in late convalescent phase PBMC in two of these patients. These results suggest that HBV DNA, and possibly HBV virions, can be present in the serum, and that the viral genome can persist in a transcriptionally active form in PBMC for > 5 yr after complete clinical and serological recovery from acute viral hepatitis.

Multiple oncogenes and tumor suppressor genes are structurally and functionally intact during hepatocarcinogenesis in hepatitis B virus transgenic mice.

In the current study we sought to elucidate the molecular mechanisms which might contribute to hepatocarcinogenesis in a hepatitis B virus (HBV) envelope transgenic mouse model in which chronic hepatocellular injury and inflammation lead to regenerative hyperplasia and eventually to the development of chromosomal abnormalities and hepatocellular carcinoma (HCC), thereby reiterating many of the pathophysiological events that occur prior to the development of HCC in chronic HBV infection in humans. We have previously demonstrated that HBV envelope gene expression is decreased in regenerating hepatocytes and preneoplastic nodules early in the disease process and that expression of alpha-fetoprotein and the multidrug transporter gene mdr-III is activated in the tumors that develop in this model, but not prior to tumor development. In the current study, we examined the structure and expression of a large panel of dominant acting oncogenes and tumor suppressor genes in the liver at all stages of the disease process in order to determine the extent to which they contribute to hepatocarcinogenesis in these transgenic mice. To our surprise, no changes were observed in the structure or function of any of these genes, many of which are commonly activated in other rodent models of hepatocarcinogenesis but rarely activated in human HCC. These findings suggest that the HBV transgenic mouse model is different from most other rodent models of hepatocarcinogenesis and that it may relate more closely to the events involved in HBV-induced human hepatocarcinogenesis, where generalized chromosomal abnormalities are common, while structural and functional changes in most of the commonly studied positive-acting oncogenes examined herein are not. Since p53 and RB mutations have recently been reported to be late events in human hepatocarcinogenesis, the structural integrity of the RB locus and the absence of p53 mutations in the HBV transgenic mouse model suggest that they may represent a relatively early stage of hepatocellular tumorigenesis and that further manipulation of this model is warranted in order to more fully reproduce the molecular-genetic events that characterize HBV-induced HCC in humans.

Hepatitis B virus specific transcripts in peripheral blood mononuclear cells.

We report on the analysis of HBV transcription in peripheral blood mononuclear cells of chronically infected patients by polymerase chain reaction amplification. Our results suggest that in these cells gene expression occurs either as pregenomic or subgenomic transcripts.

Significance of anti-HBx antibodies in hepatitis B virus infection.

Serological responses to hepatitis B virus-X determinants have been noted in human sera, but conflicting findings concerning the correlation of anti-HBx antibodies with different stages of hepatitis B virus infection or pathological sequelae have been reported. Using an adenovirus-based eukaryotic vector, the 17 kD X protein was efficiently expressed in 293 cells. Cellular extracts containing the eukaryotic X protein have been used to screen for anti-HBx antibodies by immunoblot analysis in a large panel of sera from patients affected by hepatitis B virus chronic hepatitis, hepatocellular carcinoma and acute viral hepatitis. Sera from 32 of 171 (19%) chronic hepatitis B virus patients were positive for anti-HBx antibodies. Only one of thirty-two (3%) HBsAg-negative, anti-HBs/anti-HBc-positive chronic hepatitis serum was anti-HBx positive. Very few sera from primary hepatocellular carcinoma patients showed positivity for anti-HBx (8 of 149 or 5%). Anti-HBx were also detected in 8 of 48 (17%) acute viral hepatitis patients. In the four cases that were followed up weekly, anti-HBx antibodies appeared 3 to 4 wk after the onset of the clinical signs. To compare the X protein expressed in eukaryotic and prokaryotic cells as a substrate for anti-HBx antibody detection, 171 sera were screened with HBx fusion proteins expressed in Escherichia coli. The prokaryotic cell extract test seems to be more sensitive. During the chronic phase of hepatitis B virus infection, the presence of anti-HBx antibodies detected with the eukaryotic cell extract correlates with the presence of well-established markers of ongoing viral replication: serum hepatitis B virus-DNA (p less than 0.001) and intrahepatic HBcAg expression (p less than 0.001).

Hepatitis B virus infection of peripheral blood mononuclear cells is common in acute and chronic hepatitis.

Hepatitis B virus (HBV) infection of peripheral blood mononuclear cells (PBMCs) has been observed in all stages of liver disease. Thus far all information about the physical state of HBV in mononuclear blood cells comes from Southern blot analysis and in situ hybridization. In this study we focused our attention on the presence of HBV DNA sequences in PBMCs of 30 patients with acute type B hepatitis and 6 patients with chronic active hepatitis by utilizing both Southern blot analysis and the polymerase chain reaction (PCR). Southern blot analysis showed no HBV DNA sequences in PBMCs of the acute hepatitis patients, although the sensitivity of our method enabled us to detect as little as 1 pg of cloned HBV insert. As far as the chronic hepatitis patients are concerned Southern blot analysis revealed the presence of HBV DNA sequences in 5 out of 6 patients but intermittently at successive follow-up times. On the other hand we were able to demonstrate the presence of HBV related sequences in 14 out of 30 acute hepatitis patients (5 HBeAg positive, 9 antiHBe positive) and in all 6 chronic hepatitis patients by PCR. Our results indicate that the involvement of PBMCs with HBV during acute HBV infection occurs at a very low level, often below the detection limit of the Southern blot technique.

[Estrogen receptors in the human liver]. / I recettori per gli estrogeni del fegato umano.

Human hepatic estrogen receptors (ER) were investigated in 17 healthy subjects (13 males and 4 females) and 70 patients with chronic liver disease (45 males and 25 females). Characterization of the estrogen binders in cytosol from human male liver showed two classes of binders, the first of them corresponding to estrogen receptor (Kd = 10(-10) M), and the second representing a low affinity binder (KD = 10(-8) M). Increased ER levels were found in males with chronic liver disease, patients with primary hepatic carcinoma (PHC) having about twice the levels of normal males. Normal females had basal values about three times higher than control males; during the progression of chronic liver disease, ER levels fell to arise again slowly so that, in PHC, values were about half of those in normal females. Prolonged alcohol abuse appeared to induce a marked increase in ER levels both in male and in female patients. The increase was maximal in patients who were still actively drinking and in those with histological signs of acute alcoholic hepatitis.

Detection of hepatitis B virus transcripts in patients with chronic liver disease.

Hepatitis B virus (HBV) transcription was studied by Northern blot analysis on total cellular RNA purified from liver biopsies in 70 patients with chronic liver disease (24 HBsAg positive, 15 antiHBs and/or antiHBc positive, 31 HBV negative). No transcripts were found in the HBV negative and in the antiHBs and/or antiHBc positive patients. In the others, three major RNA species were identified: i. a 3.5 kb transcript corresponding to the RNA pregenome; ii. 2.4-2.1 kb transcript corresponding to the s and preS1 gene RNA; iii. lower molecular weight species. All three forms were present simultaneously only in patients with active viral replication, with a strict relation between the presence of the 3.5 kb RNA in the liver and serum HBV-DNA. In conclusion, Northern blot analysis can easily be performed to study viral replication and it can contribute to a better understanding of the molecular processes underlying HBV infection and leading to liver disease in man.

[HBV DNA in mononuclear cells of peripheral blood in acute hepatitis B: a comparative analysis of Southern blot and polymerase chain reaction (PCR)]. / HBV DNA nelle cellule mononucleate del sangue periferico in corso di epatite acuta B: analisi comparativa tra Southern blot e reazione polimerasica di catena (RPC).

Hepatitis B virus (HBV) infection of peripheral blood mononuclear cells (PBMCs) has been observed in all stages of liver disease. The data available on acute hepatitis patients are limited. We therefore focused our attention on the presence of HBV DNA sequences in PMBCs of 30 patients with acute type B hepatitis. Southern Blot analysis showed no HBV sequences in PMBCs, although the sensitivity of our method enabled us to detect as low as 1 pg of cloned HBV insert. On the other hand, Polymerase Chain Reaction (PCR) demonstrated the presence of HBV related sequences in 14 out of 30 patients (5 HBeAg positive, 9 anti HBeAg positive). Our results indicate that the involvement of PMBCs with HBV during acute infection is not correlated with viral replication and occurs at a very low level, so that its detection by traditional Southern Blotting can prove ineffective.

Molecular pathogenesis of hepatocellular carcinoma in hepatitis B virus transgenic mice.

Transgenic mice that overproduce the hepatitis B virus large envelope polypeptide and accumulate toxic quantities of hepatitis B surface antigen (HBsAg) within the hepatocyte develop severe, prolonged hepatocellular injury that initiates a programmed response within the liver, characterized by inflammation, regenerative hyperplasia, transcriptional deregulation, and aneuploidy. This response inexorably progresses to neoplasia. The incidence of hepatocellular carcinoma in this model corresponds to the frequency, severity, and age of onset of liver cell injury, which itself corresponds to the intrahepatic concentration of HBsAg and is influenced by genetic background and sex. Thus, the inappropriate expression of a single structural viral gene is sufficient to cause malignant transformation in this model. These results suggest that severe, prolonged cellular injury induces a preneoplastic proliferative response that fosters secondary genetic events that program the cell for unrestrained growth.

Ethanol-induced increase in cytosolic estrogen receptors in human male liver: a possible explanation for biochemical feminization in chronic liver disease due to alcohol.

The hepatic cytosolic estrogen receptor content was measured in liver samples from patients with normal livers and from patients with nonalcoholic cirrhosis, alcoholic cirrhosis and alcoholic hepatitis. The estrogen receptor content of normal liver was 5.2 +/- 3.5 fmoles per mg of cytosolic protein. Levels which were not significantly different from this were found in the samples from patients with nonalcoholic cirrhosis (2.1 +/- 2.0 fmoles per mg of cytosolic protein). The cytosolic estrogen receptor content in the livers of patients with alcoholic cirrhosis who were abstaining was 4.2 +/- 3.6 fmoles per mg of cytosolic protein, but it increased to 10.4 +/- 4.9 fmoles per mg of protein in the livers of patients with alcoholic cirrhosis who were drinking, to 17.3 +/- 8.7 fmoles per mg of protein in the livers of patients with alcoholic hepatitis with cirrhosis and to 22.7 +/- 15.7 fmoles per mg of protein in the livers of patients with alcoholic hepatitis without cirrhosis. Alcohol abuse appeared, therefore, to induce an increase in the estrogen receptor content of human liver, especially in patients who were drinking and had histological evidence of acute liver damage (alcoholic hepatitis). The increase in hepatic estrogen receptor which we have observed may be involved in the molecular mechanisms underlying the feminization of the liver in alcoholic males.

Risk factors for hepatocellular carcinoma in Italy. Male sex, hepatitis B virus, non-A non-B infection, and alcohol.

To investigate risk factors for hepatocellular carcinoma (HCC) in Italy--a country with medium (south: 5% to 10%) to low (north: 1% to 2%) incidence of hepatitis B virus (HBV) infection--we studied 646 consecutive patients: 58 chronic active hepatitis (CAH), 428 cirrhosis, and 160 HCC, 49% from Southern and 51% from Northern Italy. Hepatitis B surface antigen (HBsAg) was positive in 41.4% of the CAH, in 23.1% of cirrhotic patients, and in 26.2% of HCC. In the latter, HBV DNA assay increased the number of subjects with active HBV infection by about 12%. Alcohol abuse was evenly distributed in all three categories of HBV markers. Males were preferentially affected. The HCC was superimposed on cirrhosis in more than 90% of patients. Our data suggest that, in our epidemiologic setting, different factors (HBV, non-A, non-B agents, alcohol) may cooperate in the development of HCC, mainly through their potential for causing cirrhosis.