Current Papers in Liver Disease - September, 2000

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

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

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Terjung, B., Spengler, U., Sauerbruch, T., and Worman, H. J. 2000. "Atypical p-ANCA" in IBD and hepatobiliary disorders react with a 50-kilodalton nuclear envelope protein of neutrophils and myoloid cell lines. Gastroenterology. 119:310-322.

About 75% of subjects with primary sclerosing cholangitis and 50% to 95% of subjects with autoimmune hepatitis have antibodies against neutrophils, a type of white blood cell. These antibodies are also present in patients with inflammatory bowel disease (IBD). When these antibodies are detected using routine indirect immunofluorescence microscopy, a method used in most clinical laboratories, they look like antibodies in patients with vasculitic diseases known as perinuclear antineutrohil cytoplasmic antibodies (p-ANCA). More careful analysis, however, has shown that the anti-neutrophil antibodies in liver diseases and IBD are clearly different, hence the term "atypical p-ANCA." In this study, Terjung et al. make a major step towards identifying the protein in neutrophils recognized by so-called "atypical p-ANCA." First, the show that these antibodies recognize a protein in the nucleus, not the cytoplasm, of neutrophils, making the term "ANCA" a misnomer. Next, they show that the recognized protein has a molecular mass of 50 kilodaltons and that it is expressed not only in neutrophils but also in 32D and HL60 myeloid cell lines (tumor cells that can differentiate into neutrophil). This work paves the way for the molecular identification of a cellular protein recognized by autoantibodies in most patients with primary sclerosing cholangitis and autoimmune hepatitis.

Piperno, A., Arosio, C., Fossati, L., Vigano, M., Trombini, P., Vergani, A., and Mancia, G. 2000. Two novel nonsense mutations of HFE gene in five unrelated Italian patients with hemochromatosis. Gastroenterology. 119:441-445.

In a landmark study published in 1996, Feder et al. (Nature Genetics. 1996;13:399-408, see September, 1996 issue of Current Papers in Liver Disease) showed that mutations in a gene on chromosome 6 now known as HFE is responsible for most cases of hereditary hemochromatosis. Most patients of European decent with the disease are homozygous (contain two copies) of a gene with a mutation that causes tyrosine to be substituted for cysteine at amino acid residue 282 of the encoded protein (C282Y mutation). Some subjects have been shown to be compound heterozygotes with one copy of their HFE gene containing the C282Y mutation and the second copy containing a mutation substituting an aspartic acid for a histidine at residue 63 in the protein (H63D mutation). In this study, Piperno et al. identify five unrelated Italian patients with hereditary hemochromatosis who have the C282Y mutation in one of their HFE genes and novel mutations in their second copies. Both of the newly described mutations introduce stop codon (nonsense mutations) that result in the synthesis of truncated proteins. These results show new mutations that cause hemochromatosis in compound heterozygotes and may have implications for genetic screening which, to date, generally involves testing for only the C282Y and H63D mutations.

Lau, G. K. K., Tsiang, M., Hou, J., Yuen, S.-T., Carman, W. F., Zhang, L., Gibbs, C. S., and Lam, S.-K. 2000. Combination therapy with lamivudine and famciclovir for chronic hepatitis B-infected Chinese patients: a viral dynamics study. Hepatology. 32:394-399.

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De Man, R. A., Marcellin P., Habal, F., Desmond, P., Wright, T., Rose, T., Jurewicz, R., and Young, C. for the Famciclovir Hepatitis B Study Group. 2000 A randomized, placebo-controlled study to evaluate the efficacy of 12-month famciclovir treatment in patients with chronic hepatitis B e antigen-positive heatitis B. Hepatology. 32:413-417.

Lamivudine was the first hepatitis B virus (HVB) polymerase inhibitor to be approved in the United States for the treatment of patients with chronic hepatitis B. It is indicated for the treatment of subjects infected with HBV who have replicative infection based on the presence of HBeAg in serum. Lamivudine has been shown to improve liver histology and lead to loss of serum HBeAg (which is associated with a better prognosis) in about 20% to 30% of treated subjects (see Liaw et al. Gastroenterology. 2000;119:172-180, reviewed above). About 20% of treated subjects also develop HBV strains resistant to lamivuding during treatment. Better treatments are clearly needed. These two studies investigate famciclovir, another HBV polymerase inhibitor alone and in combination with lamivudine. Lau et al. studied HBV dynamics in 21 subjects infected with HBV by measuring viral DNA and using a complex mathematical model. They showed that combination therapy was better than lamivudine alone in inhibiting viral replication. In the study by De Man et al., 417 subjects received either one year of famciclovir (500 mg TID or 1.5 g daily) or placebo. Serum DNA decreased in both famciclovir groups and liver biopsies improved. Only 9%, however, lost HBeAg from serum 6 months after treatment (3% in placebo group). These studies show that famciclovir may have modest effects on inhibiting HBV replication and that it can potentially be added to lamivudine in the treatment of chronic hepatitis B. Its efficacy and safety in combination with lamivudine still must be tested in a well-designed, controlled clinical trial.

Kruger, M., Berger, C., Li, Q.-X., Welch, P. J., Tritz, R., Leavitt, M., Barber, J. R., and Wong-Staal, F. 2000. Identification of eIF2B-gamma and eIF2-gamma as cofactors of hepatitis C virus internal ribosome entry site-mediated translation using a functional genomics approach. Proceedings of the National Academy of Sciences of the United States of America. 97:8566-8571.

The hepatitis C virus (HCV) uses a conserved RNA sequence known as an internal ribosome entry site (IRES) to gain access to the host cell protein synthesis machinery. Inhibition of IRES function would lead to decreased viral protein synthesis, perhaps leading to decreased viral replication. The IRES is therefore a potential target for novel anti-viral drugs. In this study, the group of Flossie Wong-Staal identified two human proteins essential for IRES function known as eIF2B-gamma and eIF2-gamma. They established a system to measure IRES-mediated protein synthesis in tissue culture cells and then screened a library of ribozymes, which destroyed specific RNA molecules. Using their screening method, they identified a ribozyme that destroyed RNA encoding eIF2B-gamma. When expressed in cells, this ribozyme inhibited IRES-mediated protein synthesis. They further showed that a ribozyme against eIF2-gamma, which works together with showed that a ribozyme against eIF2-gamma, which works together with eIF2B-gamma in cells, also inhibited IRES-mediated protein synthesis. In cell cultures, these two ribozymes did not apparently inhibit cellular protein synthesis or cell growth. These findings suggest that the proteins eIF2B-gamma and eIF2-gamma are used by the HCV IRES to direct the synthesis of viral proteins. These proteins may therefore me potential targets for the development of drugs to fight HCV replication in cells. One concern is that the effects of inhibiting eIF2-gamma and eIF2B-gamma in normal human tissues are not known.

Theise, N. D., Nimmakayalu, M., Gardner, R., Illei, P. B., Morgan, G., Teperman, L., Henegariu, O., and Krause, D. S. 2000. Liver from bone marrow in humans. Hepatology. 32:11-16.

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Alison, M. R., Poulsom, R., Jeffery, R., Dhillon, A. P., Quaglia, A., Jacob, J., Movelli, M., Prentice, G., Williamson, J., and Wright, N. A. 2000. Hepatocytes from non-hepatic adult stem cells. Nature. 406:257.

Previous studies support the existence of liver "stem cells" which are undifferentiated cells that can divide and differentiate into hepatocytes (the primary liver cell type) and cholangiocytes (bile duct cells). Recent studies in rodents by Petersen et al. (Science. 1999;284:1168-1170, see July, 1999 issue of Current Papers in Liver Disease) and Theise et al. (Hepatology.2000;31:235-240, see February 2000 issue of Current Papers in Liver Disease) strongly support the hypothesis that hepatic stems cells originate in the bone marrow. Theise et al. now extend these finding to humans. They obtained liver biopsy materials from 2 female recipients of bone marrow transplantation from male donors and 4 male recipients of bone marrow transplantation from male donors and 4 male recipients of orthotopic liver transplants from female donors. In the livers of all these cases and normal male controls, the authors were able to detect hepatocytes and cholangiocytes that contained Y chromosomes. Y chromosomes are present in male cells but not female cells, suggesting that hepatocytes and cholangiocytes came from the bone marrow in the male recipients of female livers and female recipients of male bone marrow. Alison et al. studied nine livers of female patients who had received a bone-marrow transplant from a male donor fo cells of donor origin by using a DNA probe specific for a piece of the Y-chromosome. They found Y-chromosome-containing hepatocytes in these female livers transplanted into the male patients. Together with the previous studies on rodents, these two studies demonstrate that stem cells likely exist in the bone marrow that can differentiate into liver cells.

Liaw, Y.-F., Leung, N. W. Y., Chang, T.-T., Cuan, R., Tai, D.-I., Ng, K.-Y., Chien, R.-N., Dent, J., Roman, L., Edmundson, S., and Lai, C.-L. for the Asia Hepatitis lamivudine study group. 2000. Effects of extended lamivudine therapy in Asian patients with chronic hepatitis B. Gastroenterology. 119:172-180.

A previous study by Lai et al. (New England Journal of Medicine. 1998;339:61-68, see July, 1998 issue of Current Papers in Liver Disease) has shown that one year of treatment with the nucleoside analogue lamivudine suppresses hepatitis B virus (HBV) replication and decreases liver inflammation in Asian patients with chronic hepatitis B. This study by Liaw et al. examined extended treatment with lamivudine for an additional year (two years total) in the same subjects. A total of 334 Asian subjects with chronic hepatitis B were randomized to receive either lamivudine (25 mg or 100 mg a day) or placebo. Patients who continued to receive lamivudine for an additional year had a significantly greater chance of not having detectable HBV DNA in their blood compared to patients who took lamivudine for one year and then were switched to placebo in the second year. Of the subjects who took lamivudine for 2 years, 17% lost detectable hepatitis B e antigen (HBeAg) after 52 weeks and 27% after 104 weeks of therapy (loss of HBeAg from serum correlates with a better long-term prognosis in chronic hepatitis B). Thirty-eight percent of subjects treated with lamivudine developed resistant mutants in their blood but they continued to do fairly well without evidence of worsening hepatitis. Lamivudine at both doses was well-tolerated for 1 and 2 years. This study shows that 2 years of treatment with lamivudine for chronic hepatitis B appears to be safe and may improve the chance of losing HBeAg from blood. Nonetheless, only a minority of subjects obtain this response and about one-third developed lamivudine-resistant HBV. Despite the partial utility of lamivudine for some patients with chronic hepatitis B, superior treatments are still urgently needed.

Rossle, M., Ochs, A., Gulberg, V., Siegerstetter, V., Holl, J., Deibert, P., Olschewski, M., Reiser, M., and Gerbes, A. L. 2000. A comparison of paracentesis and transjugular intrahepatic portosystemic shunting in patients with ascites. New England Journal of Medicine. 342:1701-1707.

Patients with cirrhosis can suffer from ascites (accumulation of fluid in the abdomen). Low salt diets and diuretics help most patients, however, some develop refractory or recurrent ascites despite maximal dietary and medical therapy. Liver transplantation remains the best treatment for eligible patients with cirrhosis and refractory ascites but sometimes other measures are needed to control ascites until a transplant can be performed. This study compared large-volume paracentesis (removal of fluid from the abdomen with a needle) to transjugular intrahepatic portosystemic shunting TIPS) in 60 patients with cirrhosis and refractory ascites. Patients were randomized to repeated paracentesis or TIPS and followed for a mean duration of approximately 45 months. In the TIPS group, 15 patients died and 1 underwent liver transplantation as compared with 23 patients and 2 patients in the paracentesis group. In an analysis of multiple variables, TIPS was independently associated with survival without the need for liver transplantation. Subjects in the TIPS group were also significantly more likely to have no ascites. These results suggest that, in a center specializing in the procedure, TIPS may be effective controlling refractory ascites in patients with cirrhosis any may even improve survival. However, TIPS should not be considered a first line treatment for all subjects with ascites, but only for those clinically similar to those studied by Rossle et al. Patients with other complications of cirrhosis, for example hepatic encephalopathy, may not tolerate TIPS and those with less advance disease may not require it.

Copyright, 2000, Howard J. Worman, M. D. All rights reserved. Printing or other reproduction is prohibited without the written authorization of Howard J. Worman.