Current Papers in Liver Disease - December, 1999

By Howard J. Worman, M. D.
Columbia University

This is a past issue of Current Papers in Liver Disease.

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Lesburg, C. A., Cable, M. B., Ferrari, E., Hong, Z., Mannarino, A. F., and Weber, P. C. 1999. Crystal structure of the RNA-dependent RNA polymerase from hepatitis C virus reveals a fully encircled active site. Nature Structural Biology. 6:937-943.

The hepatitis C virus (HCV) has an RNA genome. Therefore, the virus needs its own RNA polymerase to replicate this genome in infected cells. As this RNA polymerase is essential for viral replication, inhibitors of it would be potentially powerful antiviral drugs. In this paper, investigators at Schering-Plough Research Institute used X-ray crystallography to determine the three-dimensional structure of the HCV RNA polymerase. Knowledge of the structure of this enzyme is a critical first-step in using rational drug design to develop inhibitors which may be useful in the treatment of hepatitis C.

Dienstag, J. L., Schiff, E. R., Wright, T. L., Perrillo, R. P., Hann, H.-W. L., Goodman, Z., Crowther, L., Condreay, L. D., Woessner, M., Rubin, M., and Brown, N. A. for the U.S. Lamivudine Investigator Group. 1999. New England Journal of Medicine. 341:1256-1263.

A previous randomized, placebo-controlled trial from Hong Kong showed that lamivudine is effective for the treatment of chronic hepatitis B (see Lai et al, 1998, reviewed in July, 1998 Current Papers in Liver Disease). This trial examined the efficacy of lamivudine treatment for chronic hepatitis B in the United States. Patients were at least 18 years of age, had hepatitis B virus infection for at least six months duration and also had detectable hepatitis B e antigen (HBeAg; a sign of viral replication) in their blood. Of 143 subjects randomly assigned to receive either lamivudine or placebo (dummy pill), 137 were eligible for further evaluation (66 who received lamivudine and 71 who received placebo). Subjects received treatment once a day for 52 weeks and were then followed for an additional 16 weeks after stopping treatment. Lamivudine recipients were more likely to have improvement in liver biopsy after treatment as evaluated by an activity score (52% vs. 23%, P<0.001). Thirty-two percent of treated subjects lost HBeAg after treatment (a sign of decreased viral replication) as opposed to 11% in the placebo group (P=0.003). Lamivudine treated subjects were also more likely to lose HBeAg and develop antibodies against it and lose detectable viral DNA from serum (17% vs. 6%, P=0.04). Thirty-two percent of individuals treated with lamivudine developed resistance to the drug (mutations in the YMDD motif of the viral DNA polymerase). None of the subjects who developed resistance lost HBeAg and developed antibodies against HBeAg, but some did have histological improvement and lower serum viral DNA concentration. The results of this study extend those of the previous one from Asia and show that a year of lamivudine treatment is well tolerated and has favorable effects on liver biopsy histology and hepatitis B virus replication.

Vogt, M., Lang, T., Frosner, G., Klingler, C., Sendl, A. F., Zeller, A., Wiebecke, B., Langer, B., Meisner, H., and Hess, J. 1999. Prevalence and clinical outcome of hepatitis C infection in children who underwent cardiac surgery before the implementation of blood-donor screening. New England Journal of Medicine. 341:866-870.

In adults, hepatitis C virus (HCV) infection appears to become chronic in about 85% of cases. It has also been estimated that about 20% of adults chronically infected with HCV go on to develop cirrhosis. In contrast, very little data are available on the prevalence and clinical outcome of HCV infection in children. This study examined 458 children in Munich, Germany who had cardiac surgery (mean age of surgery 2.8 years) before 1991 when the blood supply was screened for HCV. Sixty-seven (14.6%) of those who had cardiac surgery had anti-HCV antibodies as compared to 0.7% of matched controls. At a mean time of 19.8 years after the first surgery, 37 (55%) of the 67 who had anti-HCV antibodies had detectable HCV RNA in their blood, indicating active viral infection. This suggests that 30 had "cleared" their infections. Of 17 who had liver biopsies, only 3 had evidence of progressive liver disease, all of whom had other concurrent risk factors for liver damage (congestive heart failure, hepatitis B virus infection). The results of this study suggest that, in contrast to adults, many children infected with HCV at a young age spontaneously clear the infection. The clinical course of those who remain infected also appears to be more benign that in adults.

Bonis, P. A. L., and Kaplan, M. 1999. Methotrexate improves biochemical tests in patients with primary biliary cirrhosis who respond incompletely to ursodiol. Gastroenterology. 117:395-399.

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Hendrickse, M. T., Rigney, E., Giaffer, M. H., Soomro, I., Triger, D. R., Underwood, J. C. E., and Gleeson, D. 1999. Low-dose methotrexate is ineffective I primary biliary cirrhosis: long-term results of a placebo-controlled trial. Gastroenterology. 117:400-497.

Methotrexate is being investigated in several on-going studies for its efficacy in the treatment of primary biliary cirrhosis (PBC). These two studies on methotrexate for PBC, published in the same issue of Gastroenterology, come to opposite conclusions about it efficacy. Bonis and Kaplan studied only 10 patients. They added methotrexate to the treatment regimen in patients who still had elevated serum alkaline phosphatase activities while receiving ursodiol and methotrexate. These patients had decreases in their serum alkaline phosphatase activities. The weakness of this study are obvious and include the small number of patients, the lack of a placebo group and the use of a single biochemical test as an end-point for clinical improvement. In contrast, Hendrickse et al. conducted a placebo-controlled trial of 60 patients and examined changes in liver biopsies, serum bilirubin concentrations (the best biochemical marker of severity in PBC) and rates of death or need for liver transplantation for up to 6 years. Thirty patients received methotrexate and 30 received placebo. Although the subjects receiving methotrexate had lower serum alkaline phosphatase activities, there were no significant differences between the methotrexate and placebo groups in these more important end-points. Hence, the best data available so-far indicate that low-dose methotrexate is not clinically indicated in the routine treatment of patients with PBC. The results of a large clinical trial now underway in the United States may help further define the role of methotrexate, if any, in the treatment of PBC.

Paradis, K., Langford, G., Long, Z., Heneine, W., Sandstrom, P., Switzer, W. M., Chapman, L. E., Lockey, C., Onions, D., The XEN 111 Study Group, and Otto, E. 1999. Search for cross-species transmission of porcine endogenous retrovirus in patients treated with living pig tissue. Science. 285:1236-1241.

Currently, there is a shortage of donor livers for individuals who require liver transplantation in the United States. Xenotransplantation (the transplantation of organs between species) may help alleviate this shortage by using animal organs. A potential danger of transplanting animal organs into humans, however, is that viruses that infect the donor animals may infect the recipients. As the organ transplant recipients would be taking drugs to surpress the immune system and prevent organ rejection, they may be unable to fight off the infecting animal virus. In an even more frightening scenario, the animal virus may mutate in the infected host into a form that can infect human contacts with normal immune systems. As a result, a new pathogenic human virus may arise (many experts believe that HIV was originally a chimpanzee retrovirus that was transmitted to humans who were involved in butchering them for food use). A favorite animal species for human organ transplantation is the pig. Although many pig pathogens can be eliminated from the animals for xenotransplantation, one that remains is the porcine endogenous retrovirus (PERV) that is permanently integrated into pig DNA. In this study, Paradis et al. examined the transmission of PERV to 160 humans who were treated with various living pig tissues. Some received treatment for liver failure with a liver assist device which utilized pig cells. Others received skin and pancreatic islet transplants from pigs. Three subjects were treated by extracorporeal perfusion through pig liver or kidneys. One hundred of the subjects were treated in Russia by pig splenic perfusion as "immunotherapy" for various indications. Using antibody testing as well as extremely sensitive methods of molecular biology (various types of polyermase chain reaction), no circulating virus was detected in any patient exposed to pig tissues. Some individuals had pig cells in their bodies (chimerism) as long as 8.5 years after being exposed to pig tissue. This study shows that in 160 patients treated with pig tissues, PERV infection was not detected in humans. However, the results do not absolutely exclude that such transmission may occur in rare instances. It should be pointed out that some of the authors of this study were employed by concerns with a commercial interest in xenotransplantation. Others were from academic institutions and the United States Centers for Disease Control and Prevention.

Sort, P., Navasa, M., Arroyo, V., Aldeguer, X., Planas, R., Ruiz-del-Arbol, L., Castells, L., Vargas, V., Soriano, G., Guevara, M., Gines, P., and Rodes, J. 1999. Effect of intravenous albumin or renal impairment and mortality in patients with cirrhosis and spontaneous bacterial peritonitis. New England Journal of Medicine. 341:403-409.

Spontaneous bacterial peritonitis (SBP) is a bacterial infection of ascites (fluid in the abdomen) that occurs in individuals with cirrhosis. During an episode of SBP, kidney function may become impaired. In this study from Spain, 126 patients with cirrhosis and SBP were randomized to treatment with either cefotaxime (an antibiotic) alone or cefotaxime plus albumin (the blood protein whose concentration in blood may be decreased in cirrhosis). The infection resolved in 94% of patients in the cefotaxime group and 98% in the cefotaxime-plus-albumin group. However, more subjects in the cefotaxime alone group developed kidney dysfunction compared to those who receive albumin (33% versus 10%). In the cefotaxime alone group, 29% of the patients died while in the hospital compared to 10% in the group that received cefotaxime and albumin. Survival was even better in the cefotaxime-plus-albumin group 3 months after leaving the hospital. These results demonstrate that intravenous albumin added to antibiotic therapy reduces the incidence of kidney impairment and death in patients with cirrhosis and SBP. Further studies may identify particular subsets of patients who will benefit most from this therapy.

Olynyk, J. K., Cullen, D. J., Aquilia, S., Rossi, E., Summerville, L, and Powell, L. W. 1999. A population-based study of the clinical expression of the hemochromatosis gene. New England Journal of Medicine.341:718-724.

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Pietrangelo, A., Montosi, G., Totaro, A., Garuti, C., Conte, D., Cassanelli, S., Fraquelli, M., Sardini, C., Vasta, F., and Gasparini, P. 1999. Hereditary hemochromatosis in adults without pathogenic mutations in the hemochromatosis gene. New England Journal of Medicine.341:725-732.

Hereditary hemochromatosis is a condition characterized by iron overload in the body. As a result of excess iron deposition, damage occurs to many organs. Characteristics of the disease include cirrhosis of the liver, diabetes mellitus, hypermelanotic pigmentation of the skin and heart failure. If detected early, hemochromatosis is a relatively easily treated disorder. About 90% of individuals with hemochromatosis are homozygous (inherit 2 copies of) for a particular mutation in the HFE gene (for more information on the genetics of hemochromatosis, see OMIM entry 235000). This mutation changes a cysteine to a tyrosine at position 282 (C282Y) in the encoded protein. It is not entirely clear how many individuals homozygous for the C282Y mutation clinically suffer from hemochromatosis or if mutations in genes other than HFE cause a clinically identical condition. In the first of these studies published in the New England Journal of Medicine, Olynyk et al. examined the prevalence and expression of the C282Y mutation. They found that in a population of white adults of northern European ancestry that 0.5% were homozygous for this mutation. All of the subjects with the C282Y mutation had an elevated serum transferrin saturation (a blood test suggestive of iron overload), indicating that this is a good screening test for hemochromatosis. However, only half of those homozygous for this mutation had clinical features of hemochromatosis and 25% had normal serum ferritin levels (another blood test suggestive of iron overload). In the second study, Pietrangelo et al. described a family from Italy in which several members had a clinical diagnosis of hereditary hemochromatosis. However, the C282Y mutation or novel mutations in HFE were not detected. The study of this family suggests that a clinical condition apparently identical to hereditary hemochromatosis can arise from mutations in a gene(s) other than HFE.

Alter, M. J., Kruszon-Moran, D., Nainan, O. V., McQuillan, G. M., Gao, F., Moyer, L. A., Kaslow, R. A., and Margolis, H. S. 1999. The prevalence of hepatitis C virus infection in the United States, 1988 through 1994. New England Journal of Medicine. 341:556-562.

Most past studies on the prevalence of hepatitis C virus (HCV) infection in the general population have been performed using samples from blood donors, a selected group that is screened for risk factors associated with infectious diseases. This study assessed the prevalence of HCV infection in the United States using serum samples from participants in the third National Health and Nutrition Examination Study (NHANES III) which was conducted from 1988 through 1994. NHANES III was conducted by the United States Centers for Disease Control and Prevention to obtain national statistics on the health and nutritional status of the population. Participants were from 89 randomly selected locations in the United States. Tests for antibodies against HCV were performed on 21,241 serum samples from persons six years old or older who participated in this study. The overall prevalence of anti-HCV antibodies was 1.8%, which would correspond to an estimated 3.9 million persons nationwide. Sixty-five percent of these were between the ages of 30 and 49 years old. Of those with anti-HCV antibodies, 74% had detectable viral RNA (73.7% were genotype 1) in their serum, corresponding to 2.7 million persons in the United States with active HCV infection. Among subjects 17 to 59 years old, illegal drug use and high risk sexual behavior were the factors most strongly associated with HCV infection. These results show that approximately 2.7 million American are chronically infected with HCV. They also suggest that the burden on the health care system caused by HCV may be increase as most infected individual are in their middle ages and may develop worsening liver damage over time.

Yoshida, H., Shiratori, Y., Moriyama, M., Arakawa, Y., Ide, T., Sata, M., Inoue, O., Yano, M., Tanaka, M., Fujiyama, S., Nishiguchi, S., Kuroki, T., Imazeki, F., Yokosuka, O., Kinoyama, S., Yamada, G., and Omata, M. for the IHIT Study Group. 1999. Interferon therapy reduces the risk for hepatocellular carcinoma: national surveillance program of cirrhotic and noncirrhotic patients with chronic hepatitis C in Japan. Annals of Internal Medicine. 131:174-181.

Chronic infection with the hepatitis C virus (HCV) can lead to cirrhosis and hepatocellular carcinoma (primary liver cancer). Those with cirrhosis caused by HCV infection are at a higher risk of developing cancer than those without cirrhosis and HCV infection. Several past studies have suggested that treatment of HCV infection with interferon-alpha may reduce the risk of developing cancer. In this retrospective (backward looking) study from 70 university hospitals in Japan, 2,890 patients with chronic hepatitis C who had liver biopsies were studied. Of these, 2,400 were treated with interferon and 490 were not treated. Response to interferon was determined virologically and biochemically. Screening for the development of hepatocellular carcinoma was performed approximately every 6 months by ultrasonography for an average period of 4.3 years. Hepatocellular carcinoma developed in 89 patients who were treated with interferon and 59 who were not. The annual incidence of hepatocellular carcinoma in the untreated patients increased with the degree of liver fibrosis on biopsy. Interferon treatment was associated with a decreased risk of carcinoma, especially among patients who had a sustained virological response (no detectable virus after treatment) and persistently normal or low serum alanine aminotransferase activities after treatment. These results suggest that interferon treatment decreases the risk of hepatocellular carcinoma in patients with chronic hepatitis C.

Coffin, C. S. and Michalak, T. I. 1999. Persistence of infectious hepadnavirus in the offspring of woodchuck mothers recovered from viral hepatitis. Journal of Clinical Investigation.104:203-212.

The hepatitis B virus (HBV) is transmitted from mother to offspring. In parts of the world such as China where HBV infection is endemic, this is an important mode of transmission. The majority of infants born to mothers with serologically evident HBV infection become infected. Some studies have suggested that, even after complete clinical and serological (HBsAg negative, anti-HBsAg positive) recovery from HBV infection, some individuals carry low levels of this virus, detectable by sensitive molecular methods, in their bodies. Such individuals who become pregnant can potentially transmit HBV to their offspring. In this study, the authors used infection of the American woodchuck with woodchuck hepatitis virus (WHV), a very similar virus to HBV, to test this hypothesis. Four female woodchuck who had acute hepatitis after infection with WHV fully recovered from acute hepatitis (WHBsAg negative, anti-WHsAg positive) but had detectable WHV by sensitive molecular methods. All 11 babies born to these 4 mothers after recovery also had low levels of detectable WHV in their liver and/or lymphoid tissue. WHV was shown to replicate in lymphatic tissues of the babies but was only variably present in their livers. These results suggest that HBV may be transmitted to infants by mothers who have low levels of residual virus after complete clinical and serological recovery.

Copyright, 1999, Howard J. Worman, M. D. All rights reserved. Printing or other reproduction is prohibited without the written authorization of Howard J. Worman.