Necroinflammatory Disease Research Articles

Mechanisms of viral hepatitis induced liver injury.

Among seven human hepatitis viruses (A to E, G and TT virus), hepatitis B (HBV) and C (HCV) viruses are able to persist in the host for years and principally contribute to the establishment of chronic hepatitis. During the course of persistent infection, continuous intrahepatic inflammation maintains a cycle of liver cell destruction and regeneration that often terminates in hepatocellular carcinoma (HCC). While the expression and retention of viral proteins in hepatocytes may influence the severity and progression of liver disease, the mechanisms of liver injury in viral hepatistis are defined to be due not to the direct cytopathic effects of viruses, but to the host immune response to viral proteins expressed by infected hepatocytes. In the process of liver injury, hepatocellular death (apoptosis) induced by the proapoptotic molecules of T cells activated following antigen recognition triggers a cascade of antigen nonspecific effector systems and causes necroinflammatory disease. Accordingly, the regulation of the immune response, e.g., via the cell death pathways, in chronically infected patients should prevent the development of HCC.

Animal models of autoimmune liver disease.

Autoimmune liver diseases in humans are characterized by chronic active hepatitis with serum autoantibodies, hypergammaglobulinemia and liver pathology showing necroinflammatory disease and fibrosis. There are an increasing number of autoantigens believed to be associated with various autoimmune liver diseases. This review will briefly outline human autoimmune hepatitis and the immunology of the liver. Various murine models of liver inflammation will be discussed, including transgenic and non-transgenic models, with emphasis on how these models aid in our knowledge of the mechanisms of disease development and chronicity. There are limitations with all of the models, including a preponderance of T-cell-focused responses. Murine models do not easily develop fibrosis, a hallmark of autoimmune hepatitis in humans. Different experimental models may not reach the same conclusions with differences between immune responses. However, this multiplicity of responses does not necessarily imply that these models are inappropriate for the study of liver immunology and autoimmune liver diseases, as different autoantigens may induce different liver responses. Knowledge of how the liver differs from other immune organs is essential to further our understanding of liver-specific autoimmunity. The plethora of antigens implicated in autoimmune hepatitis in humans predicts that multiple mechanisms may play a role in precipitating disease in the susceptible individual.

Hepatitis B virus and hepatocellular carcinoma

Chronic hepatitis B virus (HBV) infection is a major global cause of hepatocellular carcinoma (HCC). Individuals who are chronic carriers have a greater than 100‐fold increased relative risk of developing the tumour. Several mechanisms of HBV‐induced HCC have been proposed. Integration of HBV DNA into the genome of hepatocytes occurs commonly, although integration at cellular sites that are important for regulation of hepatocyte proliferation appears to be a rare event. Functions of the HBx protein are also potentially oncogenic. These include transcriptional activation of cellular growth regulatory genes, modulation of apoptosis and inhibition of nucleotide excision repair of damaged cellular DNA. The effects of HBx are mediated by interaction with cellular proteins and activation of cell signalling pathways. Variations in HBV genome sequences may be important in hepatocarcinogenesis, although their significance has not yet been completely elucidated. Necroinflammatory hepatic disease, which often accompanies chronic HBV infection, may contribute indirectly to hepatocyte transformation in a number of ways, including by facilitating HBV DNA integration, predisposing to the acquisition of cellular mutations and generating mutagenic oxygen reactive species. Although HCC is a malignancy with a poor prognosis, the availability of an effective vaccine against HBV infection, and its inclusion in the Expanded Programme of Immunization of many countries, augurs well for the eventual elimination of HBV‐associated HCC.

Autoimmune hepatitis.

Autoimmune hepatitis (AIH) is a necro-inflammatory disease that, untreated, carries a 3-year mortality rate of approximately 50%. In this last of a series of three articles, current knowledge regarding AIH is reviewed. The mode of presentation of AIH is variable: insidious onset with few if any symptoms, presenting with symptoms indistinguishable from that of any acute viral hepatitis, or onset with fulminate hepatitis. In AIH, hepatocytes become injured by various agents (such as a viral infection) and become antigenic, leading to a self-perpetuating antigen-antibody response with subsequent chronic liver disease. AIH is the only type of hepatitis that is responsive to corticosteroids. Occasionally, AIH develops after liver transplantation.

TREATMENT OF CHILDREN WITH AUTOIMMUNE HEPATITIS USING MYCOPHENOLATE MOFETIL

45 Autoimmune hepatitis (AIH) is a chronic necro-inflammatory disease of the liver which can progress to cirrhosis if left untreated. The overall response rate to steroids is 80%, but >40% become steroid dependent and require treatment with azathioprine (AZA). Mycophenolate mofetil (MMF), an inhibitor of the lymphocyte-specific inosine monophosphate dehydrogenase, has been successfully utilized in children with liver transplants. There have been no reports of MMF use in children with AIH. Aim: We report our experience with MMF in treating children with AIH as an alternative to AZA. Results: 5 patients, ages 1-15 (mean 8.8) years, 2 M & 3 F with serologic & histologic evidence of AIH type 1 were studied. 2 presented with cirrhosis & were treated with MMF for AZA intolerance (1) & steroid sparing (1). Another 3 required liver transplant (LTX) for fulminant hepatitis (2) & cirrhosis (1). MMF was used post transplant. The dose of MMF was 20 mg/kg/d administered bid. Omeprazole prophylaxis (10 mg/d <10 kg or 20 mg/d >10 kg) was given to prevent gastrointestinal ulceration from MMF. Patients' data are summarized in the table. 2 patients with AIH & cirrhosis were successfully tapered to a lower steroid dose only after receiving MMF. Of 3 patients with AIH who required LTX, 2 were successfully tapered off steroids using MMF but the 3rd patient was non-compliant & had progressive disease. Conclusion: MMF appears to be a safe and effective alternative to AZA for steroid sparing & recurrent post transplant disease in children with AIH.TABLE

Hepatitis C-related Hepatocellular Carcinoma: Prevalence Around the World, Factors Interacting, and Role of Genotypes

Hepatocellular carcinoma is the most frequently occurring cancer world-wide and is responsible for approximately one million deaths each year (1). It is frequently found in patients with chronic liver disease resulting from infection with hepatitis C virus, and as many as 170 million or more people may be infected with this virus (2). Epidemiologic studies have identified the risk of hepatocellular carcinoma in patients infected with the hepatitis C virus and the routes of transmission of the disease (3-5), but it is unclear what factors interact with the virus to increase an individual's risk for carcinoma. The most plausible explanation presented thus far is that the virus causes chronic necroinflammatory hepatic disease with vigorous regeneration, fibrosis, and eventual cirrhosis (3). The World Health Organization has estimated that approximately 80 percent of patients with acute hepatitis C viral infection will go on to develop chronic hepatitis; of these, 20 percent will develop cirrhosis and 1-5 percent will progress to hepatocellular carcinoma (2). The purpose of this review is to determine which risk factors interact with hepatitis C infection among persons who develop hepatocellular carcinoma. Studies have shown that the roles of hepatitis B and C viruses in hepatocarcinogenesis vary considerably among populations. However, the independent role of hepatitis C virus in the genesis of hepatocellular carcinoma is poorly understood. Some conditions implicated as being predisposing, or etiologic factors for the risk of hepatocellular carcinoma, include older age, male sex, excessive alcohol consumption, blood transfusion, chronic liver diseases, cirrhosis, and dietary exposure to aflatoxin (6-10). An important next step

An Update on Chronic Hepatitis

Chronic hepatitis has been broadly defined as liver inflammation without improvement for at least 6 months. A more accurate definition is “it is a chronic necroinflammatory disease of variable severity that is noL associated with features of chronic cholestasis or with steatasis or Malory body forma(ion.” Histological classificati. of chronic hepatitis included chronic persisLent hepatitis, chronic active hepatitis, and chronic lobular hepatitis. The histopathological aspects of chronic heputitis are discussed.

Hepatitis viruses and hepatocellular carcinoma

Of the hepatitis viruses that have been identified and their pathological consequences characterised, three - hepatitis B virus (HBV), hepatitis C virus (HCV) and hepatitis D virus (HDV) - have been implicated as risk factors for hepatocellular carcinoma (HCC) in humans. Sufficient evidence is now available to justify the conclusions that chronic infection with HBV and HCV, but not HDV, are causes of HCC. Hepatocellular carcinogenesis is a complex step-wise process that evolves over many years, and the precise way(s) in which these two viruses induce malignant transformation remain uncertain. The observation that HBV DNA is integrated into cellular DNA in the great majority of, and perhaps all, HBV-related HCCs, whereas replicative intermediates of HCV do not insert into host DNA in HCVrelated HCC, makes it very likely that different pathogenic mechanisms operate in HBV- and HCV-induced HCC. Indeed, evidence is mounting that both direct and indirect mechanisms, and often the two together, are involved in the genesis of HBV-related HCC, but that HCV appears only to induce HCC indirectly by causing chronic necroinflammatory hepatic disease which in turn is responsible for tumour formation. There is some evidence that the two viruses may interact in the development of HCC, but this remains to be proven. Animal models - other members of the hepadnavirus family (to which HBV belongs) that also cause HCC in their respective animal hosts, and transgenic mice into which sequences of HBV DNA have been inserted - are proving useful in elucidating putative mechanisms of HBV-related hepatocellular carcinogenesis, but no models for studying HCV-induced HCC are yet available. Whatever the pathogenesis of HBV-induced and HCV-induced HCC, the viruses do not act alone but in conjunction with other environmental carcinogens and a number of host factors.

Hepatitis B viruses and cancerogenesis

Hepatitis B virus (HBV) is a small, enveloped DNA virus which primarily infects liver cells and causes acute and persistent liver disease. Chronic HBV infection, frequently associated with cirrhosis and eventually hepatocellular carcinoma (HCC), represents a major health problem in the world. HBV is the prototype member of the hepadnavirus family, which includes several related mammalian viruses also implicated in liver carcinogenesis in the host. Although epidemiological evidence has clearly linked HBV infection with HCC development, the precise role of the virus and the molecular mechanisms of liver cell transformation remain elusive. Here we discuss potential oncogenic strategies of HBV, ranging from indirect mechanisms related to chronic necroinflammatory disease and to the effects of viral gene products on cell proliferation and apoptosis, to direct insertional activation of cellular (onco)genes. Presently, vaccination of high risk populations represents a major way to prevent the development of HBV-related liver cancer.

Autoimmune Hepatitis: Pathogenesis, Diagnosis and Treatment

Background: Autoimmune hepatitis (AIH) is a chronic necro-inflammatory disease of the liver. Early recognition is important in order to prevent the development of cirrosis. This review discusses recent developments in the fields of diagnosis, pathophysiology and management of AIH. Methods : Relevant manuscripts were identified using an electronic database, and by hand search of a personal library. Results and conclusions : Description of new auto-antibodies, and formulation of diagnostic criteria and a scoring system by an international panel constitute important advances that may help diagnosis of the disease at an early stage. While a satisfying animal model of the disease is lacking, clinical observations have led to the formulation of a pathophysiological model. Current treatment has a failure rate of about 13%, and is unable to induce a permanent remission in most patients. New immunosuppressive agents (cyclosporine, tacrolimus and mycophenolate mofetil) appear promising, and should be evaluated in controlled trials.

Mild abnormalities in liver histology associated with chronic hepatitis: distinction from normal liver histology.

BACKGROUND: Chronic hepatitis C virus infection associated with contaminated anti-D immunoglobulin has become an issue of recent concern. The clinical course of chronic hepatitis C infection is unpredictable and histological...

Hepatitis C virus liver disease in women infected with contaminated anti-D immunoglobulin.

Screening for hepatitis C virus (HCV) infection is carried out by detection of antibodies to the virus (enzyme-linked immunosorbent assay (ELISA) and recombinant immunoblot assay (RIBA)) with confirmation by identification of HCV RNA genome in serum (polymerase chain reaction (PCR)). We describe the histological features on liver biopsy in 88 women with chronic HCV infection (serum positive on ELISA, RIBA and PCR) acquired from virus contaminated anti-D immunoglobulin. For the majority of these patients the time interval from virus infection to presentation was between 17 and 18 years. We separately assessed necroinflammatory disease activity and architectural features on liver biopsy and applied a scoring system which permitted semi-quantitative documentation of abnormal features. Only three women showed liver biopsies within normal limits (+/-focal steatosis). The remaining 85 cases showed a predominantly mild or moderate degree of disease activity with interface hepatitis (56.8% of cases), spotty necrosis, apoptosis and focal inflammation (88.6% of cases) and portal inflammation (90.9% of cases). Confluent necrosis was an uncommon finding (2.3% of cases). Assessment of architectural features showed normal appearance in 35.2% of biopsies. The predominant architectural abnormality noted was portal tract fibrosis. Ten per cent of cases, however, showed significant fibrous band and/or nodule formation.

Inhalation toxicity studies of thimet (phorate) in male Swiss albino mouse, Mus musculus: I. Hepatotoxicity

Biochemical and histopathological changes in serum and liver of the male Swiss Albino mouse, Mus musculus, exposed subchronically to the recommended field dose of Thimet (6728.5 mg m −3) in a whole body inhalation chamber were studied in the second, fourth, sixth, eighth, tenth and twelfth week of exposure. A significant rise in Aspartate aminotransferase (AST) and Alanine aminotransferase (ALT) activities were observed throughout the experiment. Alkaline phosphatase (ALP) activity showed a significant rise from the fourth week of exposure until the end of the experiment. The rise in the activities of these enzymes suggested hepatocellular necroinflammatory disease. Total bilirubin level was increased significantly throughout the experiment (indicative of jaundice); however the direct bilirubin level was significantly high in the tenth and twelfth week of exposure and indirect bilirubin showed a significant rise from the fourth week of exposure until the end of the experiment. Changes in bilirubin levels (direct and indirect) suggested both prehepatic and hepatocellular hyperbilirubinaemia. The biochemical changes observed and fatty change in the liver were confirmed by histopathological studies. Liver lesions were present throughout the experimental period. These consisted of mild to severe multifocal cloudy, hydropic and fatty degenerations, with necrosis. After a 30-day recovery period most of the histopathological and biochemical changes except the AST level were almost back to normal. These results suggest the inhalation of Thimet (Phorate) at the recommended field dose could affect the liver of Mus musculus.

Serum and ascitic levels of soluble intercellular adhesion molecule-1 in patients with alcoholic liver cirrhosis: relation to biochemical markers of disease activity and alcohol intake.

The overexpression of intercellular adhesion molecule-1 (ICAM-1) has been shown to be involved in the pathogenesis of various necroinflammatory diseases, including alcoholic hepatitis. Shedding of this molecule from cell surfaces results in a circulating form, soluble ICAM-1 (sICAM-1). In this work, the serum and ascitic concentrations of sICAM-1 were studied in relation to clinical and laboratory data in patients with alcoholic liver cirrhosis of different disease activities. Elevated circulating concentrations of this adhesion molecule were found in all cirrhotic patients, the highest in those with superimposed severe alcoholic hepatitis, and the levels in regularly drinking cirrhotics without severe alcoholic hepatitis were likewise significantly higher than in those who had stopped drinking. The serum sICAM-1 concentration was best related to the serum AST activity, and also exhibited significant correlations with the prothrombin activity, serum bilirubin, albumin, peripheral leukocyte count. Maddrey's discriminant function value, Child grading, and antecedent alcohol consumption. Multivariate regression analysis revealed that the serum AST and prothrombin activities were independent predictors of the circulating sICAM-1 concentration. The concentration of sICAM-1 in the uninfected ascitic fluid of cirrthotics was about seven times lower than that in the serum; the ratio of its ascitic and serum levels was lower than that of the ascitic and serum total protein concentrations. These data contradict a significant intraperitoneal production of the molecule. It is concluded that the serum sICAM-1 level may be useful as a marker for the current disease activity (the severity of underlying acute necroinflammatory reactions) in alcoholic liver cirrhosis.

HCV-associated hepatocellular carcinoma without cirrhosis

Background/Aims: Hepatocellular carcinoma is an aggressive malignancy and carriers a poor prognosis. Hepatitis B and C virus infection, cirrhosis and aflatoxin B 1 exposure are considered major risk factors. The role of hepatitis C virus in the causation of hepatocellular carcinoma has been debated. It is a positive, single-stranded RNA virus without a DNA intermediate in its replicative cycle, so that integration of hepatitis C virus nucleic acid sequences into the host genome seems unlikely. The most plausible explanation of hepatitis C virus-associated hepatocellular carcinoma so far is that the virus causes necroinflammatory hepatic disease with vigorous regeneration, fibrosis, and eventually cirrhosis. The aim of this study was to examine the relationship of hepatitis C, cirrhosis and hepatocellular carcinoma. Methods: Sixty-six consecutive patients with hepatocellular carcinoma undergoing resection or transplantation at the Royal Free Hospital were reviewed. A combination of serological data and polymerase chain reaction assay was used to assign hepatitis C virus and hepatitis B virus infection. Results: We found four HCV-RNA positive patietns with hepatocellular carcinoma without cirrhosis. All four cases were positive for HCV-RNA and negative for all markers of hepatitis B virus infection. Conclusions: These four cases show that hepatocellular carcinoma may develop in patients with hepatitis C virus without pre-existing cirrhosis. However, the precise role of hepatitis C virus in hepatocarcinogenesis, the carcinogenic potential of the different genotypes and whether this role is influenced by other risk factors still have to be clarified.

Hepatitis C virus and hepatocellualr carcinoma

In the short time that the hepatitis C virus has been known to be the major cause of parenterally acquired non-A, non-B hepatitis, it has become increasingly apparent that chronic infection with this virus si closely associated with the occurence of hepatocellular carcinoma. Evidence for the link is provided mainly by case/control studies and case series but also by longitudinal studies. The proportion of patients with hepatocellular carcinoma who have circulating antibody to hepatitis C virus shows a pronounced geographical variation. In Japan, Spain, and Italy antibody isn present in 47–83% of the patients, with relative risks of 52 (95% confidence interval 24–114) in Japanese and 69 (15–308) in Italian carriers of the virus. In regions where hepatitis B virus infection is endemic and is the major risk factor for hepatocellular carcinoma, antibody to hepatitis C virus is present in the serum of a smaller proportion (6–39%) of patients, with relative risks of 7 (1.6–39) in Taiwan and 6 (0.5–69) in Senegal. Comparatively low prevalences (13–35%) have also been recorded in the remaining geographical regions for which information is available, with relative risks of 10.4 (4–26) in Greece and 10.5 (3.5–31) in North America. There is some evidence for an interaction between hepatitis C adn B viruses in hepatocellular carcinogenesis, but this remains to be proved. In most populations hepatocellular carcinoma develops at an older age in patientss with hepatitis C virus-induced tumours than in those with hepatitis B virus-induced tumours. The pathogenesis of hepatitis C virus-related hepatocellular carcinoma is unknown. Because it always arises in association with cirrhosis or chronic patients and because there is no evidence that the virus is directly carcinogenic, it appears that hepatitis C virus induces malignant trasnformation indirectly by causing chronic necroinflammatory hepatic disease which in turn is responsible for tumour formation.

Hepatitis C virus and hepatocellualr carcinoma

In the short time that the hepatitis C virus has been known to be the major cause of parenterally acquired non-A, non-B hepatitis, it has become increasingly apparent that chronic infection with this virus is closely associated with the occurrence of hepatocellular carcinoma. Evidence for the link is provided mainly by case/control studies and case series but also by longitudinal studies. The proportion of patients with hepatocellular carcinoma who have circulating antibody to hepatitis C virus shows a pronounced geographical variation. In Japan, Spain, and Italy antibody is present in 47-83% of the patients, with relative risks of 52 (95% confidence interval 24-114) in Japanese and 69 (15-308) in Italian carriers of the virus. In regions where hepatitis B virus infection is endemic and is the major risk factor for hepatocellular carcinoma, antibody to hepatitis C virus is present in the serum of a smaller proportion (6-39%) of patients, with relative risks of 7 (1.6-39) in Taiwan and 6 (0.5-69) in Senegal. Comparatively low prevalences (13-35%) have also been recorded in the remaining geographical regions for which information is available, with relative risks of 10.4 (4-26) in Greece and 10.5 (3.5-31) in North America. There is some evidence for an interaction between hepatitis C and B viruses in hepatocellular carcinogenesis, but this remains to be proved. In most populations hepatocellular carcinoma develops at an older age in patients with hepatitis C virus-induced tumours than in those with hepatitis B virus-induced tumours. The pathogenesis of hepatitis C virus-related hepatocellular carcinoma is unknown. Because it always arises in association with cirrhosis or chronic hepatitis and because there is no evidence that the virus is directly carcinogenic, it appears that hepatitis C virus induces malignant transformation indirectly by causing chronic necroinflammatory hepatic disease which in turn is responsible for tumour formation.

Molecular events in the pathogenesis of hepadnavirus-associated hepatocellular carcinoma.

Chronic hepadnavirus infection is associated with hepatocellular carcinoma (HCC) in natural hosts such as humans, woodchucks, and Beechey ground squirrels. Several possible oncogenic mechanisms have been identified, including a potential role of the hepadnavirus x (hbx) gene, which transactivates transcription regulated by certain cis-acting sequences, e.g. regulatory sequences of the hepatitis B virus (HBV) and heterologous regulatory sequences of other viruses and cellular genes. The oncogenic potential of hbx is suggested by the observation of HCCs in hbx transgenic mice, the oncogenic transformation of cells expressing hbx in culture, and the transactivation of oncogenes c-myc and c-jun by hbx. Cis-activation of cellular oncogenes N-myc and c-myc by viral promoter insertion has been a common finding in woodchuck hepatitis virus (WHV)-associated HCCs of woodchucks. No such cis-activation of any cellular gene has been shown in virus-associated HCCs of ground squirrels or humans. Amplification and overexpression of the c-myc gene has been a common finding in HCCs of ground squirrels, and is rare in woodchuck or human HCCs. Point mutations in the p53 gene and allelic deletion of p53 have been common findings in human HCCs, but have not been found in HCCs in woodchucks and have been found rarely in ground squirrels. How each of these genetic changes in the different hosts contributes to HCC remains to be determined, but apparently different changes in different HCCs of hepadnavirus-infected hosts suggest that several separate genetic events may contribute to the development of HCC. These events may differ in each host, and some may not result from a direct virus-specific mechanism. Chronic hepadnavirus infection is often associated with chronic necroinflammatory liver disease and cirrhosis, a pathologic process common to several other risk factors for HCC. This suggests that this pathologic process (necroinflammatory disease) may be hepatocarcinogenic regardless of the inciting agent. Thus hepadnavirus infection may play an important role in the development of HCC by causing chronic hepatitis and HCC with the same mechanisms by which other risk factors for HCC cause chronic necroinflammatory liver disease and HCC.

Mycobacterial contamination of fibreoptic bronchoscopes.

Contamination of bronchoalveolar lavage specimens by environmental mycobacteria in hospital water supplies may lead to diagnostic confusion, particularly in immunocompromised patients. Mycobacteria may become concentrated in the tubing of bronchoscope disinfecting machines. It is very difficult to eradicate these organisms once contamination has occurred.

Tumours of the liver.

One of the major debates in hepatocellular carcinogenesis at present is whether the hepatitis-B and -C viruses are directly carcinogenic or exert their effect indirectly by causing chronic necro-inflammatory hepatic disease, which in turn is responsible for malignant transformation of hepatocytes. This debate has been fueled by the observation that hepatitis C virus is a single-stranded RNA virus with no precedent for inducing cancer but with a marked propensity to cause chronic necro-inflammatory hepatic disease and by the findings in Chisari's transgenic mouse model, which suggest that severe and prolonged hepatocellular injury per se induces a proliferative response that progresses to tumour formation. Recent reports of a guanine to thymine mutation of the third base of codon 249 of the tumour suppressor gene, p53, in 50% of patients with hepatocellular carcinoma in regions of high aflatoxin exposure, and mutagenic experiments showing that aflatoxin B1 binds particularly to guanine residues in G-C-rich domains and that codon 249 is a preferred target have suggested a mechanism whereby aflatoxin might induce malignant transformation.