Current Papers in Liver Disease - March, 1997

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

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

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Brown, K. E., Tisdale, J., Barrett, J., Dundar, C., E., and Young, N. S. 1997. Hepatitis-associated aplastic anemia. New England Journal of Medicine. 336:1059-1064.

Aplastic anemia (bone marrow failure) is sometimes associated with acute hepatitis, particularly in adolescent boys and young men. In these cases, which can be fatal, the cause of the hepatitis is usually not known. Aplastic anemia is also fairly common after orthotopic liver transplantation for fulminant non-A, non-B hepatitis in young patients. This study reports 10 patients with hepatitis-associated aplastic anemia seen at the National Institutes of Health between 1990 and 1996. There was evidence of activated CD8 T cells in the blood of all patients. Serological evidence of hepatitis A, B and C infection was lacking and hepatitis C virus RNA was absent in all patients. Hepatitis G virus RNA was detected in 3 patients. Seven of the 10 patients responded to aggressive treatment with immunosuppressive agents. These case reports suggest that the hepatitis of hepatitis-associated aplastic anemia is not caused by any of the well-known hepatitis viruses and that the syndrome may be mediated by immunological mechanisms.

Calhoun County Dept. of Public Health et al. 1997. Hepatitis A associated with consumption of frozen strawberries - Michigan, March 1997. Morbidity and Mortality Weekly Report. 46:288-295.

A total of 153 cases of hepatitis A have been reported in Calhoun County, Michigan in March, 1997. Preliminary analysis of both a case-control and cohort study conducted in two different school districts has linked the cases to the consumption of frozen strawberries. The investigation is still in progress. The implicated strawberries were reported to be from a company in Mexico and processed and packed by a company in southern California in 30-pound containers. The packed strawberries were distributed to the U. S. Department of Agriculture-sponsored school lunch program and to other commercial customers. States other than Michigan that received the implicated lots for the school lunch program are Arizona, California, Georgia, Iowa and Tennessee. It is unclear if any of the contaminated strawberries or products made from them are still in distribution at this time. The Centers for Disease Control and Prevention recommended that the health departments in the six states that received these lots of strawberries determine if they were served. Post exposure propylaxis with immune globulin is recommended only to persons who consumed frozen strawberries from the suspected lots in the school lunch programs within 14 days of exposure. Hepatitis A cases suspected to be associated with the consumption of frozen strawberries should be reported to local or state health departments and to the Centers for Disease Control and Prevention Hepatitis Branch (404-639-2709). Most cases of hepatitis A are not life-threatening, especially in children. Patients present with fatigue, fever, nausea, vomiting and possibly jaundice. On laboratory examination, elevations in serum aminotransferase activities and possibly bilirubin concentrations are seen along with IgM antibodies against the hepatitis A virus. Between 0.1% and 1% of cases may be fatal (or require emergency orthotopic liver transplantation), especially in older adults.

Ku, N.-O., Wright, T. L., Terrault, N. A., Gish, R., and Omary, M. B. 1997. Mutation in human keratin 18 in association with cryptogenic cirrhosis. Journal of Clinical Investigation. 99:19-23.

The term "cryptogenic" is used to describe cases of cirrhosis when the cause cannot be determined. Some cases of "cryptogenic" cirrhosis may result from genetic diseases that have not yet been described. As mutations in keratins have been associated with oral and epidermal diseases, in this study the authors examined 120 patients who underwent orthotopic liver transplantation for "cryptogenic" cirrhosis for mutations in keratins 8 and 18, the major keratins expressed in hepatocytes. They found a mutation the keratin 18 gene in one patient that caused a histidine at position 127 of the protein to be replaced by a leucine. This mutant keratin protein formed abnormal intermediate filaments when co-assembled with keratin 8. These findings demonstrate that novel genetic diseases may cause or predispose some individuals to hepatitis and/or cirrhosis and that mutations in keratins can cause liver disease.

Bottcher, B., Wynne, S. A., and Crowther, R. A. 1997. Determination of the fold of the core protein of hepatitis B virus by electron cryomicroscopy. Nature. 386:88-91.

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Conway, J. F., Cheng, N., Zlotnick, A., Wingfield, P. T., Stahl, S. J., and Steven, A. C. 1997. visualization of 4-helix bundle in the hepatitis B virus capsid by cryo-electron microscopy. Nature. 386:91-94.

The hepatitis B virus consists of an inner capsid or core surrounded by a lipoprotein envelope. The capsid core forms from the self-assembly of core protein. Knowledge of the core protein structure would be useful for the design of antiviral drugs, however, it has not been crystallized and its structure has not been determined by X-ray crystallography. In these two papers, cryo-electronmicroscopy was used to determine the structure of the hepatitis B core protein. Unlike other viral capsid proteins, the hepatitis B core protein is largely alpha-helical. The stem, which protrudes as a spike on the capsid outer surface, is a 4-helix bundle formed by the pairing of alpha-helical regions from two subunits. These papers contain the highest resolution data on the structure of the hepatitis B core protein obtained to date. They also demonstrate the power of cryo-electron microscopy to determine the structures of proteins that cannot be readily crystallized.

Ridzon, R., Gallagher, K., Ciesielski, C., Mast, E. E., Ginsberg, M. B., Robertson, B. J., Lou, C.-C., and DeMaria, A., Jr. 1997. Simultaneous transmission of human immunodeficiency virus and hepatitis C virus from a needle-stick injury. New England Journal of Medicine. 336:919-922.

The risk of acquiring human immunodeficiency virus (HIV) infection after percutaneous exposure to blood from an infected individual is estimated to be about 0.3 percent. The risk of transmission of hepatitis C virus (HCV) after percutaneous exposure to infected blood has not been well defined. In this paper, the authors document infection with both HIV and HCV that a health care worker apparently acquired simultaneously from a single source. The health care worker was a 48-year old woman who sustained a deep injury with a blood-contaminated needle and spilled blood from the collection vial under her gloves onto hands that were chapped with open cuts. Seroconversion to HIV occurred between 8 and 9.5 months and seroconversion to HCV between 9.5 and 13.5 months after exposure. Progession to hepatic failure and death occurred about a year after seroconversion. Sequencing of the HIV and HCV isolates from the source patient and the infected worker were virtually identical. This study suggests that HIV and HCV can be simultaneously transmitted from infected patients to health care workers. The long time to seroconversion and rapid progression to hepatic failure are very atypical in this case.

Moreno, A., Carreno, V., Cano, A., and Gonzalez, C. 1997. Idiopathic biliary ductopenia in adults without symptoms of liver disease. New England Journal of Medicine. 336:835-838.

Paucity of intrahepatic bile ducts or "ductopenia" has been described in many different liver diseases of adults and children. In adults, a paucity of intrahepatic bile ducts in the absence of other known causes has been described as idiopathic adulthood ductopenia. This condition has been generally reported to be associated with severe liver disease that progresses to cirrhosis and absence of bile ducts in at least 50% of portal tracts (portions of the liver where bile ducts, portal veins and hepatic veins are visible on liver biopsies). In this study, the authors describe 24 patients (17 women and 7 mean, mean age 41 years) who were asymptomatic but had elevated serum gamma-glutamyltranspeptidase activities. About three-quarters also had elevations in serum alanine aminotransferase activity. Liver biopsies showed that these patients had a paucity of intrahepatic bile ducts with ducts absent from about 40% of portal tracts. These findings suggest that paucity of intrahepatic bile ducts, or ductopenia, can occur in adults with mild, asymptomatic, non-progressive liver disease.

Purdy, A., et al. 1997. Nosocomial hepatitis B virus infection associated with reusable fingerstick blood sampling devices - Ohio and New York, 1996. Morbidity and Mortality Weekly Report. 46:217-220.

In 1996, outbreaks of hepatitis B virus (HBV) infection occurred among patients with diabetes mellitus in a nursing home in Ohio and hospital in New York City. Acute hepatitis B was diagnosed in 4 residents of an Ohio nursing home. Eleven residents were subsequently identified to be acutely or chronically infected with HBV and all had diabetes mellitus. Among infected individuals, the attack rate was 53% in those who underwent fingerstick capillary testing and 0% among persons who did not require finger sticks. When the first case was identified, the facility routinely shared three fingerstick devices among patients. Lancets were routinely changed but end caps were not. After switching to individual fingerstick devices for each resident, no new HBV infections were detected. Acute hepatitis B was also diagnosed in 3 inpatients in a New York City hospital all of whom had diabetes mellitus and were hospitalized during the same time period. All 3 of these patients had fingerstick blood monitoring compared to 20 susceptible patients hospitalized at the same time who did not have fingersticks. Based on review of serological records, 11 additional patients with possible nosocomially acquired acute HBV infection were identified and 10 had received fingersticks while hospitalized during the previous 6 months. After the hospital switched from shared fingerstick devices to completely disposable, nonreusable devices, no new cases of nosocomially acquired HBV infections have been identified. Although similar outbreaks have been reported previously, these investigations confirm that HBV can be transmitted by fingerstick capillary-blood sampling devices. These results emphasize the need to restrict such devices, even if lancets are not reused, to individual patients.

Alter, M. J., Gallagher, M., Morris, T. T., Moyer, L. A., Meeks, E. L., Krawczynski, K., Kim, J. P., and Margolis, H. S., for the Sentinel Counties Viral Hepatitis Study Team. 1997. Acute Non-A-E hepatitis in the United States and the role of hepatitis G virus infection. New England Journal of Medicine. 336:741-746.

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Alter, H. J. , Nakatsuji Y., Melpolder, J., Wages, J., Wesley, R., Shih, W.-K., and Kim, J. P. 1997. The incidence of transfusion-associated hepatitis G virus infection and its relation to liver disease. New England Journal of Medicine. 336:747-754.

About 10% to 20% of cases of community-acquired hepatitis and transfusion-associated hepatitis are not associated with the known major hepatotropic viruses (A, B, C, D, E). The fairly recent identification from patients with hepatitis of the hepatitis G/GB-C virus (herein called HGV), which is about 25% identical to the hepatitis C virus (HCV), has implicated it as a cause of non-A-E hepatitis. [Click here for more on HGV.] These two new studies show that persistent infection with HGV is common in the United States. They also suggest that HGV may cause mild acute hepatitis but that it does not cause clinically significant chronic disease. Both of these studies used reverse-transcription polymerase chain reaction to detect HGV RNA in serum. In the study by M. J. Alter et al., a portion of patients reported to the Sentinel Counties surveillance system from 1982 to 195 with acute viral hepatitis were studied. HGV RNA was detected in 4 of 45 patients with acute non-A-E hepatitis (9%), 23 of 116 with hepatitis C (20%), 25 of 100 with hepatitis A (25%) and 32 of 100 with hepatitis B (32%). The prevalence of HGV in patients with hepatitis B was significantly higher than those with hepatitis C or hepatitis non-A-E. The clinical characteristics of the acute illness were similar in patients with HGV alone and those infected with the other viruses with or without HGV. Of the 4 patients with HGV alone, 3 remained persistently positive for HGV RNA for 1 to 9 years, however, none had clinically apparent chronic hepatitis (although liver biopsies were not performed). Of the patients with both HCV and HGV infection, 87% were persistently positive for HGV RNA. The rates of chronic hepatitis C were essentially the same in patients with hepatitis C alone (60%) and those with HGV co-infection (61%). In the study by H. J. Alter et al., serum samples were collected between 1972 and 1995 from 357 transfusion recipients, 157 controls who did not receive transfusions, 500 random volunteer blood donors and 230 donors of blood received by HGV-infected individuals. Of 79 patients with transfusion-associated hepatitis, 63 (80%) were related to HCV and 3 had preexisting HCV infection and the cause of acute hepatitis could not be determined. Six of the 63 with HCV-related hepatitis had co-infection with HGV (10%). Of the remaining 13 patients, 3 had HGV alone and 10 possible infections with unidentified agents. The 3 patients with HGV alone had mild acute hepatitis and did not develop clinically apparent chronic hepatitis (although liver biopsies were not done). There were 35 HGV infections among all of the 357 transfusion recipients and only 3 had HGV as the only virus. One of the 157 controls and 7 of the 500 random blood donors also had detectable HGV (1.4%). In all instances in which a recipient had acute HGV after transfusion and samples from donors could be tested, at least one HGV-positive donor was identified. These two studies show that HGV is fairly common in the United States and that it can be transmitted by blood and blood products. HGV may cause mild acute hepatitis, but despite persistent infection, it does not appear to cause clinically significant chronic hepatitis.

Zeuzem, S., Lee, J.-H., and Roth, K. 1997. Mutations in the nonstructural 5A gene of European hepatitis C virus isolates and response to interferon alfa. Hepatology. 25:740-744.

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Chayama, K., Tsubota, A., Kobayashi, M., Okamoto, K., Hashimoto, M., Miyano, Y., Koike, H., Kobayashi, M., Koida, I., Arase, Y., Saitoh, S., Suzuki, Y., Murashima, N., Ikeda, K., and Kumada, H. 1997. Pretreatment virus load and multiple amino acid substitutions in the interferon sensitivity-determining region predict the outcome of interferon treatment in patients with chronic genotype 1b hepatitis C virus infection. Hepatology. 25:745-749.

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Kurosaki, M., Enomoto, N., Murakami, T., Sakuma, I., Asahina, Y., Yamamoto, C., Ikeda, T., Tozuka, S., Izumi, N., Marumo, F., and Sato, C. 1997. Analysis of genotypes and amino acid residues 2209 to 2248 of the NS5A region of hepatitis C virus in relation to the response to interferon-beta therapy. Hepatology. 25:750-771.

Of the various hepatitis C virus (HCV) genotypes, type 1b is particularly resistant to treatment with interferon. Enomoto and colleagues have shown that a region of the NS5A gene in genotype 1b isolates correlates with increased sensitivity to interferon treatment. They named this region, between amino acids 2209 and 2248, the interferon-sensitivity determining region (ISDR). In a study published in 1996 of 84 Japanese patients with chronic hepatitis C treated with interferon alpha, they showed that response to treatment with interferon alpha correlated with multiple mutations in ISDR (Enomoto et al. 1996. New England Journal of Medicine. 334:77-81. [see April, 1996 Current Papers in Liver Disease]). In the three studies described here, the relationship between mutations in ISDR and interferon responsiveness was further examined. In the paper by Zeuzem et al., 32 patients with chronic hepatitis C in Europe were studied. Only one of these patients had a sustained, long-term response to treatment with interferon alpha and only 3 of 22 patients infected with HCV genotype 1b had three or more had mutations causing amino acid substitutions in ISDR. Not surprisingly, given the low number of patients with genotype 1b infection and multiple mutations in ISDR, these investigators found no correlation between such mutations and response to treatment. On the other had, Chayama et al., who studied 110 patients in Japan, found a significant correlation between sustained response to treatment with interferon alpha and multiple mutations in ISDR. In their study, 33% of patients had long-term responses to treatment. Of 103 patients from whom they could obtain ISDR sequences, 32 had three or more amino acid substitutions in ISDR, 16 of 31 responders and only 6 of 72 non-responders. Kurosaki, Enomoto and their collaborators showed that multiple mutations in ISDR correlated with response to treatment with interferon beta in a follow-up on their previous study published in 1996 on interferon alpha. These investigators studied 40 patients, 32 of whom were infected with HCV genotype 1b. None of 10 with wild-type ISDR, none of 6 with one amino acid substitution and 4 of 6 with 5 to 10 amino acid substitutions had long-term responses to treatment. Along with the past work of Enomoto and collaborators, these studies demonstrate that mutations in ISDR of the NS5A protein of HCV genotype 1b correlate with sustained responses to treatment with interferons. The function of the HCV NS5A polypeptide remains to be determined.

Lindor, K. D., for the Mayo Primary Sclerosing Cholangitis-Ursodeoxycholic Acid Study Group. 1997. New England Journal of Medicine. 336:691-694.

There is no highly effective medical therapy for patients with primary sclerosing cholangitis (PSC). Ursodiol (also known as urodeoxycholic acid) is beneficial in the treatment of primary biliary cirrhosis and has also been shown to improve serum alkaline phosphatase and aminotransferase activities and bilirubin and albumin concentrations in individuals with PSC. In this double-blind study, 105 patients with PSC were randomized to receive either ursodiol or placebo. The primary outcome was the time to treatment failure defined as either death, liver transplantation, significant histological progression, progression to cirrhosis, the development of complications of cirrhosis, worsening fatigue and pruritus, inability to tolerate the drug and voluntary discontinuation. Subjects were followed for a median of 2.2 years. Although the patients receiving ursodiol had improvements in laboratory values, there was no significant difference between the drug and placebo groups in the time to treatment failure. In a group of patients with well-defined PSC, ursodiol was of no clinical benefit. As the diagnosis of PSC is usually made once the disease is already advanced, it is not clear if ursodiol would be beneficial if physicians were able to routinely diagnose the disease at earlier stages.

Wang, Y., DeMayo, F. J., Tsai, S. Y., and O'Malley, B. W. 1997. Ligand-inducible and liver-specific target gene expression in transgenic mice. Nature Biotechnology. 15:239-243.

Transgenic mice have been used extensively to study various disease processes, including the molecular and cellular biology of liver diseases. One limitation of transgenic mouse models is the difficulty in inducing the expression of a desired gene in a particular tissue in a regulated fashion. In this study, the authors have devised a method to specifically express a desired transgene in the liver which is inactive until the administration of an exogenous compound. They accomplish this by using a chimeric gene activator that consists of a mutated human progesterone receptor ligand binding domain fused to the yeast GAL4 DNA binding domain and the HSV VP16 transcriptional activation domain. The authors demonstrate that the expression of a target transgene can be activated by this chimeric activator by low concentrations of the progesterone antagonist mifepristone. By putting the chimeric transactivator under control of the enhancer/promoter region of the transthyretin gene, they go on to generate transgenic mice with a target gene that is expressed in a liver-specific and ligand-inducible fashion. Transgenic technologies such as the one described in this paper may facilitate the development of useful animal models of human liver diseases.