Primary and secondary liver/kidney microsomal autoantibody response following infection with hepatitis C virus

Hepatitis C Virus and Molecular Mimicry

This review delves into the interactions between hepatitis C virus (HCV) and the host immune system, shedding light on how by using the mechanism of molecular mimicry, the virus strategically evades the immune system, resulting in a cascade of diverse complications. HCV, notorious for its ability to persistently infect hepatocytes, employs molecular mimicry to resemble host proteins, thereby avoiding immune detection and mounting an effective defense. This mimicry also triggers systemic autoimmune responses that lead to various sequelae. The objective of this review is to comprehensively explore the role of HCV-induced molecular mimicry, which not only facilitates viral survival but is also instrumental in developing autoimmune and inflammatory disorders. By mimicking host proteins, HCV triggers an immune response that inadvertently attacks the host, fostering the development of autoimmune and other inflammatory disorders. Understanding the nuanced mechanisms of HCV-mediated molecular mimicry provides crucial insights into the multifaceted sequelae of viral infections on host immune responses. Unravelling these complexities is paramount for advancing therapeutic strategies that not only target the virus directly but also mitigate the secondary autoimmune and inflammatory complications induced by HCV.

Lactobacillus reuteri joins the liver autoimmune arena

Type 1 CD8 T cells (Tc1s) have been implicated in liver injury in autoimmune hepatitis (AIH) through mechanisms that have so far been unclear. In this issue of Cell Host & Microbe, Pandey et al. show that the aryl hydrocarbon receptor ligand-producing pathobiont Lactobacillus reuteri induces Tc1-mediated AIH-like pathology in mice with Tet-methylcytosine-dioxygenase-2 deficiency.

New agents for immunosuppression

The human abdomen harbors organs that the host's immune system can attack easily. This immunological storm front leads to diseases like Crohn's Disease, Ulcerative Colitis or Autoimmune Hepatitis. Serious symptoms like pain, diarrhea, fatigue, or malnutrition accompany these diseases. Moreover, many patients have an increased risk for developing special kind of malignancies and some autoimmune disease can show a high mortality. The key to treat them consists of a deep understanding of their pathophysiology. In vitro and especially in vivo basic research laid the foundation for our increasing knowledge about it during the past years. This enabled the development of new therapeutic approaches that interact directly with cytokines or immune cells instead of building the treatment on a total immunosuppression. Different kind of antibodies, kinase inhibitors, and regulatory T cells build the base for these approaches. This review shows new therapeutical approaches in gastrointestinal autoimmune diseases in context to their pathophysiological basis.

Impact of genetic and environmental factors on autoimmune hepatitis

Autoimmune hepatitis (AIH) is a chronic non-resolving liver disease characterized by diffuse hypergammaglobulinemia, the presence of autoantibodies and characteristic histological findings. The disease can have catastrophic outcome with the development of end-stage liver disease if misdiagnosed/undiagnosed and left untreated. AIH pathogenesis remains obscure and the main hypothesis supports its development in genetically predisposed individuals after being exposed to certain environmental triggers. Genetic predisposition is linked to the presence of certain HLA alleles, mainly HLA-DR3 and HLA-DR4. However, a wide number of non-HLA epitopes have also been associated with the disease although data vary significantly among different ethnic groups. Therefore, it is likely that epigenetic alterations may also play a crucial role in disease's pathogenesis, although not yet extensively studied. The aim of this review was to summarize the genetic and environmental factors that have been associated with AIH, but also to open new insights towards the role of epigenetic modifications in the etiology of the disease.

Genetic aspects of adult and pediatric autoimmune hepatitis: A concise review

Autoimmune Hepatitis (AIH) is a heterogenous, mostly chronic liver disease that affects people of all age groups, women more often than men. The aim of therapy is to prevent cirrhosis, as it mainly accounts for liver-related mortality in patients with AIH. Rates of remission are high in patients with AIH, but life-long immunosuppressive therapy is required. AIH is hypothesized to originate from immunologic reactivity targeted against mostly unknown self-antigens, potentially triggered by viral infections among other factors. While AIH does not follow a Mendelian inheritance pattern, part of the risk of developing AIH or worse disease course, is attributed to specific genetic risk factors. Major associations for the risk of development of AIH were found for HLA-DRB1*03:01 and HLA-DRB1*04:01 in adult AIH in the only genome-wide association study on AIH. However, other potential risk loci in SH2B3, CARD10 and KIR genes were described. This review covers the current knowledge on genetic risk factors in adult and pediatric AIH.

Pathogens and autoimmune hepatitis

Autoimmune hepatitis (AIH) is a severe form of hepatitis resulting in the autoimmune-mediated destruction of the liver parenchyma. Whereas many of the immunopathogenic events have been elucidated and some of the drivers of the disease have been identified, little is known about the aetiology of the disease. There are certain risk factors, such as particular human leucocyte antigen (HLA) haplotypes, that enhance the susceptibility for AIH or influence the severity of the disease. However, as for many other autoimmune diseases, the mere presence of such risk factors does not warrant the occurrence of the disease. Not all individuals carrying risk factors develop AIH, and not all patients with AIH are carriers of high-risk alleles. Thus, additional environmental factors need to be considered as triggers for AIH. Environmental factors include diet, sunlight exposure, stress, medication and hygiene, as well as pathogen infections and vaccinations. This review discusses if pathogens should be considered as triggers for the initiation and/or propagation of AIH.

Autoimmune hepatitis

Autoimmune hepatitis (AIH) is a severe liver disease that affects children and adults worldwide. The diagnosis of AIH relies on increased serum transaminase and immunoglobulin G levels, presence of autoantibodies and interface hepatitis on liver histology. AIH arises in genetically predisposed individuals when a trigger, such as exposure to a virus, leads to a T cell-mediated autoimmune response directed against liver autoantigens; this immune response is permitted by inadequate regulatory immune control leading to a loss of tolerance. AIH responds favourably to immunosuppressive treatment, which should be started as soon as the diagnosis is made. Standard regimens include fairly high initial doses of corticosteroids (prednisone or prednisolone), which are tapered gradually as azathioprine is introduced. For those patients who do not respond to standard treatment, second-line drugs should be considered, including mycophenolate mofetil, calcineurin inhibitors, mechanistic target of rapamycin (mTOR) inhibitors and biologic agents, which should be administered only in specialized hepatology centres. Liver transplantation is a life-saving option for those who progress to end-stage liver disease, although AIH can recur or develop de novo after transplantation. In-depth investigation of immune pathways and analysis of changes to the intestinal microbiota should advance our knowledge of the pathogenesis of AIH and lead to novel, tailored and better tolerated therapies.

Liver immunology: How to reconcile tolerance with autoimmunity

There are several examples of liver tolerance: the relative ease by which liver allografts are accepted and the exploitation of the hepatic microenvironment by the malarial parasite and hepatotrophic viruses are notable examples. The vasculature of the liver supports a unique population of antigen presenting cells specialised to maintain immunological tolerance despite continuous exposure to gut-derived antigens. Liver sinusoidal endothelial cells and Kupffer cells appear to be key to the maintenance of immune tolerance, by promoting T cell anergy or deletion and the generation of regulatory cell subsets. Despite this, there are three liver diseases with likely autoimmune involvement: primary biliary cirrhosis, primary sclerosing cholangitis and autoimmune hepatitis. How can we reconcile this with the inherent tolerogenicity of the liver? Genetic studies have uncovered several associations with genes involved in the activation of the innate and adaptive immune systems. There is also evidence pointing to pathogenic and xenobiotic triggers of autoimmune liver disease. Coupled to this, impaired immunoregulatory mechanisms potentially play a permissive role, allowing the autoimmune response to proceed.

Cutting edge issues in autoimmune hepatitis

Autoimmune hepatitis (AIH) is a severe liver disease affecting all age groups worldwide. Novel basic and clinical aspects of AIH, addressed at a Monothematic Conference in London in September 2015, are highlighted in this review. The diagnosis of AIH relies upon detection of characteristic autoantibodies, hypergammaglobulinemia, and interface hepatitis on liver histology. The International Autoimmune Hepatitis Group (IAIHG) has devised diagnostic scoring systems to help in comparative studies and clinical practice. AIH arises in a genetically predisposed host, when yet unknown triggers - such an encounter with a pathogen - lead to a T cell-mediated immune response targeting liver autoantigens. This immune response is inadequately controlled because regulatory mechanisms are impaired. The mainstay of treatment for AIH is immunosuppression, which should be instituted as soon as the diagnosis is made. Standard treatment regimens include relatively high doses of predniso(lo)ne, which are tapered gradually as azathioprine is introduced. Recent guidelines have described newer treatment regimens and have tightened the goal of therapy to complete normalization of biochemical, serological and histological parameters. Mycophenolate mofetil, calcineurin inhibitors, mTOR inhibitors and biological agents are potential salvage therapies, but should be reserved for selected non-responsive patients and administered only in experienced centers. Liver transplantation is a life-saving option for those patients who progress to end-stage liver disease. Further dissection of cellular and molecular pathways involved in AIH pathogenesis is likely to lead to the discovery of novel, tailored and better tolerated therapies.

Autoimmune hepatitis: From mechanisms to therapy

Autoimmune hepatitis (AIH) is a progressive inflammatory hepatopathy and an important cause of end-stage liver disease. Its aetiology remains unknown, though both genetic and environmental factors are involved in its development. The major mechanism of autoimmune liver damage involves immune reactions against host liver antigens. Numerical and functional defects of regulatory T-cells play a permissive role enabling autoimmune liver injury to occur and persist. The most typical features of AIH are female preponderance, hypergammaglobulinaemia, seropositivity for circulating autoantibodies and a picture of interface hepatitis on histology. Two types of AIH are distinguished according to serological profile: AIH type 1 patients are positive for anti-nuclear and/or anti-smooth muscle antibodies, whereas AIH type 2 patients are defined by the positivity for anti-liver kidney microsomal type 1 antibody and/or for anti-liver cytosol type 1 antibody. Clinical manifestations are variable, and AIH onset is often ill-defined, frequently mimicking acute hepatitis; its course may be fluctuating. AIH responds to immunosuppressive treatment in the majority of cases. Steroids with or without azathioprine should be instituted promptly upon diagnosis. Remission is achieved in some 80% of patients. For the remaining 20% of patients, alternative immunosuppressive agents such as mycophenolate mofetil and calcineurin inhibitors are an option. Liver transplantation should be considered for those patients who progress to cirrhosis and develop complications of end-stage liver disease, as well as for those presenting with acute liver failure; outcomes are excellent, although the disease may recur in the allograft.

Liver immunology

The liver is the largest organ in the body and is generally regarded by nonimmunologists as having little or no lymphoid function. However, such is far from accurate. This review highlights the importance of the liver as a lymphoid organ. Firstly, we discuss experimental data surrounding the role of liver as a lymphoid organ. The liver facilitates tolerance rather than immunoreactivity, which protects the host from antigenic overload of dietary components and drugs derived from the gut and it is instrumental to fetal immune tolerance. Loss of liver tolerance leads to autoaggressive phenomena, which if not controlled by regulatory lymphoid populations, may lead to the induction of autoimmune liver diseases. Liver-related lymphoid subpopulations also act as critical antigen-presenting cells. The study of the immunological properties of liver and delineation of the microenvironment of the intrahepatic milieu in normal and diseased livers provides a platform to understand the hierarchy of a series of detrimental events that lead to immune-mediated destruction of the liver and the rejection of liver allografts. The majority of emphasis within this review will be on the normal mononuclear cell composition of the liver. However, within this context, we will discuss selected, but not all, immune-mediated liver disease and attempt to place these data in the context of human autoimmunity.

Cutting edge issues in autoimmune hepatitis

Autoimmune hepatitis is an inflammatory liver disease affecting mainly females and characterised histologically by interface hepatitis, biochemically by elevated transaminase levels and serologically by circulating autoantibodies and increased levels of immunoglobulin G. Autoimmune hepatitis responds to immunosuppressive treatment, which should be instituted as soon as diagnosis is made. Seropositivity for smooth muscle and/or antinuclear antibody defines type 1 autoimmune hepatitis, while positivity for liver kidney microsomal type 1 antibody defines type 2 autoimmune hepatitis. The aetiology of autoimmune hepatitis is unknown, though both genetic and environmental factors are involved in its expression. The major mechanism of liver damage involves immune reactions against host liver antigens that are not adequately controlled by defective regulatory T cells. Current research aiming at potentiating regulatory T cell function in vitro to reconstitute tolerance in vivo has given promising results.

Autoimmune manifestations in viral hepatitis

Infections by the viruses responsible for hepatitis B, C and D are accompanied by a number of immunopathological manifestations. A link between infection and autoimmunity is particularly well documented for the hepatitis C virus. Immunopathological manifestations range from production of autoantibodies to overt autoimmune disease, including thyroiditis and autoimmune hepatitis, and to immune-complex-mediated disorders, including cryoglobulinaemia, glomerulonephritis and vasculitis. Several of these manifestations improve with successful antiviral treatment, directly incriminating the virus in their pathogenesis. Mechanisms considered responsible for hepatitis virus-related immunopathology, including molecular mimicry, impairment of regulatory T cells and activation of B lymphocytes, will be examined in this review.

Aetiopathogenesis of autoimmune hepatitis

Interface hepatitis, histological hallmark of autoimmune hepatitis (AIH), is a dense portal mononuclear cell infiltrate invading the parenchyma, consisting of CD4 and CD8 T-lymphocytes, monocytes/macrophages and plasma cells. What triggers AIH is unknown, but there is evidence that failure of immune homeostasis plays a permissive role allowing liver autoantigen-specific cells to attack hepatocytes. Damage is likely to be orchestrated by CD4 T-lymphocytes recognizing an autoantigenic liver peptide. For autoimmunity to arise, the peptide, embraced by an HLA class II molecule, must be presented to naïve CD4 T-helper (T(H)0) cells by professional antigen-presenting cells. Once activated, T(H)0 cells can differentiate into T(H)1 cells, which are pivotal to macrophage activation, enhance HLA class I expression, rendering liver cells vulnerable to CD8 T-cell attack, and induce HLA class II expression on hepatocytes; or into T(H)2 cells producing IL-4, IL-10 and IL-13, cytokines favouring autoantibody production by B-lymphocytes. Autoantigen recognition is tightly controlled by regulatory mechanisms, such as those exerted by CD4+CD25+ regulatory T-cells (T-regs). Numerical and functional T-reg impairment characterizes AIH, particularly during active disease. Advances in the study of autoreactive T-cells stem mostly from AIH type 2, where the main autoantigen, CYP2D6, is known enabling characterization of antigen-specific immune responses. Monocyte involvement in the autoimmune liver attack has been recently reported.

Aetiopathogenesis of autoimmune hepatitis

The histological hallmark of autoimmune hepatitis (AIH) is a dense portal mononuclear cell infiltrate that invades the surrounding parenchyma and comprises T and B lymphocytes, macrophages, and plasma cells. An unknown but powerful stimulus must be promoting the formation of this massive inflammatory cellular reaction that is likely to initiate and perpetuate liver damage. An autoimmune attack can follow different pathways to inflict damage on hepatocytes. Liver damage is likely to be orchestrated by CD4⁺ T lymphocytes recognizing an autoantigenic liver peptide. To trigger an autoimmune response, the peptide must be embraced by an HLA class II molecule and presented to naïve CD4⁺ T helper (Th0) cells by professional antigen presenting cells, with the co-stimulation of ligand-ligand fostering interaction between the two cells. Th0 cells become activated, differentiate into functional phenotypes according to the cytokines prevailing in the microenvironment and the nature of the antigen, and initiate a cascade of immune reactions determined by the cytokines produced by the activated T cells. Th1 cells, arising in the presence of the macrophage-derived interleukin (IL) -12, secrete mainly IL-2 and interferon-gamma (IFN-γ), which activate macrophages, enhance expression of HLA classI(increasing liver cell vulnerability to a CD8⁺ T cell cytotoxic attack), and induce expression of HLA class II molecules on hepatocytes. Th2 cells, which differentiate from Th0 if the microenvironment is rich in IL-4, produce mainly IL-4, IL-10, and IL-13 which favour autoantibody production by B lymphocytes. Physiologically, Th1 and Th2 antagonize each other. Th17 cells, a recently described population, arise in the presence of transforming growth factor beta (TGF-β) and IL-6 and appear to have an important effector role in inflammation and autoimmunity. The process of autoantigen recognition is strictly controlled by regulatory mechanisms, such as those exerted by CD4⁺CD25⁺ regulatory T cells, which derive from Th0 in the presence of TGF-β, but in the absence of IL-6. If regulatory mechanisms fail, the autoimmune attack is perpetuated. Over the past three decades different aspects of the above pathogenic scenario have been investigated. In particular, a defect in immunoregulation affecting CD4⁺CD25⁺ regulatory T cells (T-regs) has been demonstrated in AIH, particularly at diagnosis or during relapse. Advances in the study of autoreactive T cells have occurred mostly in AIH type 2, since the knowledge that CYP2D6 is the main autoantigen has enabled the characterization of both CD4 and CD8 T cells targeting this cytochrome. CD4 T cells from patients with type 2 AIH positive for the predisposing HLA allele DRB1*0701 recognize seven regions of CYP2D6, five of which are also recognized by CD8 T cells. High numbers of IFN-γ producing CD4 T cells and CD8 T cells are associated with biochemical evidence of liver damage, suggesting a combined cellular immune attack.

Successful treatment with cyclosporine A of HCV-driven chronic liver disease mimicking autoimmune hepatitis in a patient with common variable immunodeficiency

Common variable immunodeficiency (CVID) is the commonest primary immunodeficiency disease characterized by defective antibody production and various degrees of T cell numbers abnormality or impaired proliferation to mitogens. Clinical features include recurrent bacterial sinopulmonary and gastrointestinal infections. Autoimmunity is very common in CVID, occurring in approximately 25% of the patients particularly with autoimmune thrombocytopenia, hemolytic anemia, inflammatory bowel disease, and rheumatoid arthritis. Persistent antigen stimulation, secondary to a defective eradication of pathogens followed by a compensatory exaggerated chronic inflammatory response, is the primary cause leading to autoimmunity. Here we describe a girl with CVID in whom a chronic liver disease mimicking autoimmune hepatitis developed after hepatitis C virus infection. The immunosuppressive treatment with cyclosporine A proved effective in reversing liver disease.

Autoantibodies in autoimmune liver disease

Autoantibodies indicate an immune reactive state, but in liver disease they lack pathogenicity and disease specificity. Antinuclear antibodies, smooth muscle antibodies, antibodies to liver/kidney microsome type 1, antimitochondrial antibodies, and perinuclear antineutrophil cytoplasmic antibodies constitute the standard serological repertoire that should be assessed in all liver diseases of undetermined cause. Antibodies to soluble liver antigen/liver pancreas, asialoglycoprotein receptor, actin, liver cytosol type 1, nuclear antigens specific to primary biliary cirrhosis, and pore complex antigens constitute an investigational repertoire that promises to have prognostic and diagnostic value. These autoantibodies may emerge as predictors of treatment response and outcome. Antibodies to histones, doubled-stranded DNA, chromatin, and lactoferrin constitute a supplemental repertoire, and they support the immune nature of the liver disease. Final diagnoses and treatment strategies do not depend solely on serological markers. Autoantibodies are floating variables, and their behavior does not correlate closely with disease activity. There are no minimum levels of significant seropositivity, especially in children. Over-interpretation is the major pitfall in the clinical application of the serological results. New autoantibodies will emerge as the search for target antigens and key pathogenic pathways continues.

Review article: hepatitis C virus infection and type-2 diabetes mellitus in renal diseases and transplantation

A link between hepatitis C virus infection and development of diabetes mellitus has been suggested by many investigators; however, this remains controversial. The mechanisms underlying the association between hepatitis C virus and diabetes mellitus are unclear but a great majority of clinical surveys have found a significant and independent relationship between hepatitis C virus and diabetes mellitus after renal transplantation and orthotopic liver transplantation. We have systematically reviewed the scientific literature to explore the association between hepatitis C virus and diabetes mellitus in end-stage renal disease; in addition, data on patients undergoing orthotopic liver transplantation were also analysed. The unadjusted odds ratio for developing post-transplant diabetes mellitus in hepatitis C virus-infected renal transplant recipients ranged between 1.58 and 16.5 across the published studies. The rate of anti-hepatitis C virus antibody in serum was higher among dialysis patients having diabetes mellitus (odds ratio 9.9; 95% confidence interval 2.663-32.924). Patients with type-2 diabetes-related glomerulonephritis had the highest anti-hepatitis C virus prevalence [19.5% (24/123) vs. 3.2% (73/2247); P < 0.001] in a large cohort of Japanese patients who underwent renal biopsy. The link between hepatitis C virus and diabetes mellitus may explain, in part, the detrimental role of hepatitis C virus on patient and graft survival after orthotopic liver transplantation and/or renal transplantation. Preliminary evidence suggests that anti-viral therapies prior to renal transplantation and novel immunosuppressive regimens may lower the occurrence of diabetes mellitus in hepatitis C virus-infected patients after renal transplantation. Clinical trials are under way to assess if the hepatitis C virus-linked predisposition to new onset diabetes mellitus after renal transplantation may be reduced by newer immunosuppressive medications.

Autoimmunity and hepatitis C

Hepatitis C is a widespread chronic liver disease leading to cirrhosis and to the complications of portal hypertension. Based on biochemical and clinical features, it is almost indistinguishable from autoimmune hepatitis, which is characterized by the absence of viral infection, and other causes of chronic liver diseases, and represents a classical autoimmune disease with loss of immunological tolerance of liver tissue. Although the differentiation between both diseases is not difficult due the availability of diagnostic viral markers, it is well recognized that not only are autoantibodies present in autoimmune hepatitis frequently detected in hepatitis C, but also that an array of immune-mediated symptoms and diseases occur in patients with chronic hepatitis C. This has prompted research aimed at identifying a link between hepatitis C and autoimmunity, and autoimmune hepatitis in particular. This review focuses on the general immunological mechanisms linking viral infections with autoimmunity and includes the specific features of hepatitis C- and D-associated autoimmunity. Virus infection remains at the center of molecular and cellular research aimed at identifying the forces driving human autoimmunity and autoimmune diseases.

Review article: immunopathogenetic and therapeutic aspects of autoimmune hepatitis

Autoimmune hepatitis is a chronic, progressive liver disease that responds well to immunosuppressive therapy, but has a poor prognosis if untreated. Possible triggering factors include viruses, other autoimmune disorders and drugs. The molecular mechanisms contributing to the pathogenesis include: reactions of autoantibodies against their corresponding autoantigens; aberrant expression of histocompatibility antigen class I and II molecules, cell adhesion molecules and cytokines; increased oxidative stress; and the occurrence of angiogenesis. The prevalence of the disease is highest in Caucasians, Europeans and women. The natural history of autoimmune hepatitis shows a poor prognosis, with frequent progression to cirrhosis and hepatic insufficiency in untreated patients. The occurrence of hepatocellular carcinoma is rare and is found only in long-standing cirrhosis. Corticosteroids as monotherapy or in combination with azathioprine are the treatments of choice; different therapeutic schedules and particularities of treatment for pregnant women and children have been established. To avoid treatment-associated adverse effects, alternative therapies have been proposed, including ciclosporin, budesonide, tacrolimus, mycophenolate mofetil, ursodeoxycholic acid, methotrexate, cyclophosphamide, mercaptopurine and free radical scavengers. Liver transplantation is indicated for patients refractory to or intolerant of immunosuppressive therapy.

Autoimmunity and viruses

Although viruses are commonly cited as triggers for autoimmune disease, the actual mechanisms by which they initiate autoimmunity are unknown. Molecular mimicry is the most popular hypothesis, and it proposes that viral antigens that share homologies with host antigens generate an immune response that damages host tissue. The viral antigen may not be needed for perpetuation of the disease, and cross-reacting immune responses can involve humoral, cellular, or both types of reactivity. Linear and conformational epitopes may be involved, and foreign antigens do not need to share exact amino acid sequences with self-proteins to activate autoreactive T cells. Bystander effects can enhance the autoimmune process if previously sequestered or cryptic antigens are exposed to the immune system, and superantigens that are produced by the pathogen and are not MHC restricted can result in marked polyclonal activation of CD4 and CD8 T cells. Future studies must differentiate the targets of pathologic immunity and distinguish self-antigens from infectious nonself-antigens. Transgenic animal models of AIH are needed to assess the pathogenicity of the antigenic targets.

Anti-CYP2D6 antibodies detected by quantitative radioligand assay and relation to antibodies to liver-specific arginase in patients with autoimmune hepatitis

BACKGROUND

Antibodies to cytochrome P4502D6 (CYP2D6) were measured and their prevalence compared with that of antibodies to liver-specific arginase in patients with autoimmune hepatitis (AIH).

METHODS

Anti-CYP2D6 antibodies were measured by sensitive radioligand assay and enzyme-linked immunosorbent assay (ELISA), and anti-arginase antibodies were measured by ELISA in 132 patients (definite AIH 11, probable AIH 36, hepatitis C 20, hepatitis B 23, other autoimmune diseases 42) and 50 healthy controls.

RESULTS

CYP2D6 index (radioligand assay) was significantly higher in all groups of patients than those in healthy controls. A higher index than the cut-off value (mean+3 S.D. in healthy controls) was found in 36.4%, 44.4%, 25.0%, 17.4% and 28.6% of patients with definite AIH, probable AIH, hepatitis C, hepatitis B and other autoimmune diseases, respectively. CYP2D6 index was not related to serum IgG, anti-nuclear antibody or AIH scores, and was weakly correlated with anti-arginase antibody activity. When CYP2D6 index and anti-arginase antibodies were combined, 55.3% of AIH patients were positive for either one or both antibodies.

CONCLUSIONS

Anti-CYP2D6 antibodies by radioligand assay were frequently present in patients with AIH. Combined tests for anti-CYP2D6 radioligand assay and anti-arginase antibodies resulted in detection of 55% of AIH patients.

Mechanisms of liver injury relevant to pediatric hepatology

Hepatocyte injury and necrosis from many causes may result in pediatric liver disease. Influenced by other cell types in the liver, by its unique vascular arrangements, by lobular zonation, and by contributory effects of sepsis, reactive oxygen species and disordered hepatic architecture, the hepatocyte is prone to injury from exogenous toxins, from inborn errors of metabolism, from hepatotrophic viruses, and from immune mechanisms. Experimental studies on cultured hepatocytes or animal models must be interpreted with caution. Having discussed general concepts, this review describes immune mechanisms of liver injury, as seen in autoimmune hepatitis, hepatitis B and C infection, the anticonvulsant hypersensitivity syndrome, and autoimmune polyendocrinopathy. Of the monogenic disorders causing significant liver injury in childhood, alpha-1 antitrypsin deficiency and Niemann-Pick C disease demonstrate the effect of endoplasmic or endosomal retention of macromolecules. Tyrosinemia illustrates how understanding the biochemical defect leads to understanding cell injury, extrahepatic porphyric effects, oncogenesis, pharmacological intervention, and possible stem cell therapy. Pathogenesis of cirrhosis in galactosemia remains incompletely understood. In hereditary fructose intolerance, phosphate sequestration causes ATP depletion. Recent information about mitochondrial disease, NASH, disorders of glycosylation, Wilson's disease, and the progressive familial intrahepatic cholestases is discussed.

Autoantibodies to human cytosol: a marker of sporadic porphyria cutanea tarda

The enzymes potentially involved in the pathogenesis of sporadic porphyria cutanea tarda (PCT) reside in liver cytosoles and microsomes. PCT is frequently associated with hepatitis C virus (HCV) infection, which is in turn associated with autoimmune manifestations. To investigate whether autoimmune reactions, possibly triggered by HCV, are involved in the pathogenesis of PCT, we measured by immunoblot autoantibodies to human cytosolic and microsomal liver fractions in 82 patients with PCT (77% with HCV infection), 105 with other liver disorders and 40 healthy subjects. Anti-liver cytosolic antibodies were more frequent in PCT patients (38/82, 46%) than in pathological controls (P < 0.05-P < 0.001) or in healthy subjects (3/40, 8%, P < 0.001). Among PCT patients, anticytosolic antibodies were more frequent in HCV positive (36/63, 57%) than in HCV negative (2/19, 11%, P < 0.05) cases. Reactivity to a 40-kDa cytosolic polypeptide was present in 20 PCT patients (19 HCV positive), being more frequent than in all pathological controls (P < 0.01-P < 0.0001). Histological activity index (P = 0.04) and antibodies to HCV (P = 0.027) - but not HCV RNA - were associated independently with anticytosolic antibodies as assessed by multivariate analysis. In contrast, frequency of antiliver microsomal antibodies was similar in PCT patients (24/82, 29%) and pathological controls (8-26%), being higher in the autoimmune hepatitis control group (23/23, 100%, P < 0.0001). In conclusion, anticytosolic antibodies, particularly to a 40-kDa polypeptide, are frequent in PCT and associated with HCV infection and severity of liver damage.

Low prevalence of liver-kidney microsomal autoantibodies of type 1 (LKM1) in hepatitis C seropositive subjects on Crete, Greece

BACKGROUND

Hepatitis C is a serious problem on the Greek island of Crete, where a high prevalence of antibodies against hepatitis C (anti-HCV) has recently been reported. This article reports the findings of a study carried out in Crete, which investigated the prevalence of serum autoantibodies in patients with chronic hepatitis C.

PATIENTS AND METHODS

One hundred and forty two patients (59 men and 83 women), who were found anti-HCV seropositive in two hospitals and two Primary Health Care Centres in Crete, were eligible. Sixty healthy blood donors (46 men, 14 women), which were negative to anti-HCV, were used as the control group. They were randomly selected from those attending Rethymnon Hospital. Autoantibodies were identified using the indirect immunofluorescence (IFL) technique on human epithelial cells from larynx cancer (HEp-2 cells), rat liver-kidney-stomach substrate (CT3) and Chrithidia Luciliae (CL).

RESULTS

Serum autoantibodies were detected in 104 HCV patients, yielding an overall prevalence of 73.2%. The most frequent autoantibodies were antinuclear antibodies (ANA), positive in 72 patients (50.7%). Anti-smooth muscle antibodies (ASMA) were detected in 33 patients (23.2%). Only one patient was positive for LKM1 autoantibodies. No autoantibodies were found in 38 patients (26.7%). Autoantibodies were also found in 5 out of the 60 examined healthy blood donors (8.3%).

CONCLUSIONS

Autoantibodies, mainly ANA and ASMA are very common in HCV seropositive patients from Crete. By contrast LKM1 autoantibodies are exceptionally rare in these patients.

De novo hepatitis with autoimmune antibodies and atypical histology: a rare cause of late graft dysfunction after pediatric liver transplantation

BACKGROUND

Late graft dysfunction after orthotopic liver transplantation is commonly due to chronic rejection, recurrence of primary disease, sepsis, lympho-proliferative disease, or vascular or biliary complications. Herein we describe a subset of pediatric liver transplant patients in whom late graft dysfunction was associated with autoimmune markers, bile ductular proliferation, and portal infiltrates, which progress to fibrosis. This subset of patients has not been previously described.

METHODS

Six of the 115 children followed for greater than 5 years after transplantation developed this unusual form of graft dysfunction. All children were on a low-dose single immunosuppressive therapy (mean trough cyclosporine concentration 89 microg/L) and had been tapered off steroids for a median duration of 1.5 year. Liver biopsies were performed in all children to evaluate the graft dysfunction, and the histologic findings were interpreted by an experienced hepato-pathologist. All patients were tested for antibodies to hepatitis C virus, hepatitis B surface antigen, and IgM antibodies to hepatitis A. Smooth muscle antibody, antinuclear antibody, and antibody to liver/kidney microsome type 1 were sought by indirect immunofluorescence. International Autoimmune Hepatitis Group scores were calculated. All patients underwent ultrasonography with doppler studies at the onset of graft dysfunction. Three patients with marked bile duct proliferation on histology had cholangiograms.

RESULTS

Histology in all patients showed mononuclear cell infiltrates in the portal area with interface hepatitis, portal fibrosis, and ductular proliferation without duct damage or loss. All six patients had positive antinuclear antibody or smooth muscle antibody titers. Viral studies for hepatitis A, B, and C were negative in all patients. On the International Autoimmune Hepatitis Group scoring system, five patients had probable autoimmune hepatitis (score of 10-15) and one had definite autoimmune hepatitis (score > 15) at the onset of graft dysfunction. All were treated with azathioprine and prednisone similar to treatment for autoimmune hepatitis. However, despite aggressive treatment, four patients developed bridging portal fibrosis resulting in graft loss in two patients.

CONCLUSION

This clinical constellation is associated with worse outcome then that previously described for pediatric patients with posttransplantation de novo autoimmune hepatitis. Further studies are needed to find an optimal treatment regimen for these patients.

Liver transplantation for autoimmune hepatitis: a long-term pathologic study

Autoimmune hepatitis (AIH) after liver transplantation (LT) may recur and is difficult to diagnose. Our aims were to define the histopathology of and factors related to AIH recurrence. Fourteen of 475 patients received LT for AIH; 2 died perioperatively. Liver specimens (native and post-LT biopsies) from 12 other patients were reviewed and correlated with pre- and post-LT clinical course and outcome. Recurrent AIH was seen in 5 of 12 patients, 35 to 280 days post-LT as lobular hepatitis with acidophil bodies and lymphoplasmacytic infiltrate. Portal/interface hepatitis was seen with disease progression and 2 of 5 patients developed cirrhosis. Of 7 nonrecurrent patients, 1 had acquired hepatitis C with lobular/portal hepatitis and none developed cirrhosis. Histology suggestive of overlap syndrome was seen in 3 of 12 native livers with no effect on post-LT course or pathology. High-grade necroinflammation was present in native livers at LT in 5 of 5 cases with recurrent AIH and in 1 of 7 without recurrence (P <.01). Pre-LT disease duration, donor/recipient gender distribution, HLA studies, and rejection episodes did not correlate with AIH recurrence. We conclude that (1) recurrent AIH is not uncommon and was seen in 42% of patients with lymphoplasmacytic lobular, portal, and interface hepatitis; (2) acidophil bodies with lymphoplasmacytic cells are seen in early recurrent AIH; (3) recurrent AIH appears at variable time periods post-LT, and the progression is slow; and (4) high-grade inflammation in native liver at LT is a strong predictor of recurrent AIH.

Enzyme Immunoassay for Autoantibodies to Human Liver-Type Arginase and Its Clinical Application

Background: Arginase is an enzyme of the urea cycle, and one of the two isoenzymes is the liver-type enzyme. We examined serum autoantibodies to this liver-type enzyme in patients with hepatitis.

Methods: Antibodies to recombinant human liver-type arginase were measured by ELISA in 95 patients and 55 healthy controls.

Results: The mean absorbance values in the ELISA assays of patients with definite autoimmune hepatitis (n = 11; P &lt;0.0001), probable autoimmune hepatitis (n = 31; P &lt;0.0001), and hepatitis C (HCV; n = 20; P &lt;0.01) were significantly different from those of healthy controls, but the values in patients with hepatitis B (HBV; n = 23) and other autoimmune diseases (n = 10) were not significantly different from those of healthy controls. When the cutoff was fixed at the upper 95th percentile of the absorbance value in healthy controls, positive reactions were found in 18.2%, 32.3%, 20.0%, 13.0%, and 10.0% of patients with definite autoimmune hepatitis, probable autoimmune hepatitis, HCV hepatitis, HBV hepatitis, and other autoimmune diseases, respectively. All of these positive reactions were abolished by inhibition of serum with recombinant antigen. The specificity and sensitivity of this ELISA were 96% and 29%, respectively. The intraassay and interassay coefficients of variation were 2.3–7.5% and 9.8–11%, respectively. There was no relationship between these antibodies and anti-nuclear, anti-smooth muscle, or anti-cytochrome P450IID6 antibodies.

Conclusions: The ELISA for anti-liver-type arginase autoantibody improved the detectability of autoimmune hepatitis when compared with established assays for liver-specific autoantibodies.

Sera of children with hepatitis C infection and anti-liver-kidney microsome-1 antibodies recognize different CYP2D6 epitopes than adults with LKM+/HCV+ sera

BACKGROUND

Liver-kidney microsome type 1 (LKM1) antibodies are specific markers of autoimmune hepatitis (AIH) type 2. Antibodies to LKM1 have been found in 2% to 3% of adults infected with hepatitis C virus (HCV) without AIH. Thirty percent of these antibodies are directed against linear sequences of CYP2D6 protein. LKM1 antibodies in HCV+/LKM1+ sera and in sera of AIH patients do not recognize the same CYP2D6 epitopes. The current study was conducted to determine whether LKM1 antibodies in HCV+/LKM1+ children's sera are the result of the same immune response as the antibodies described in AIH type 2 and in HCV+/LKM1+ adult patients.

METHODS

Sera from 10 HCV+/LKM1+ children were tested against human liver microsomal and cytosolic proteins by Western blot analysis and against synthetic peptides of the CYP2D6 sequence between amino acids 200 and 429 by dot blot. The same sera were tested against radiolabeled CYP2D6 by immunoprecipitation.

RESULTS

Four of 10 sera tested by Western blot analysis showed immunoglobulin (Ig) G-type antibodies against CYP2D6, and 2 had antibodies against proteins of 58, 66, and 84 kDa. One of the sera also contained IgM-type anti-66-kDa and 84-kDa proteins. The radioligand test detected anti-CYP2D6 antibodies in 9 of 10 patients. Five of the anti-CYP2D6-positive sera recognized a peptide between amino acids 200 and 429 including amino acids 254-271.

CONCLUSIONS

Most HCV+/LKM1+ sera from children recognize conformational epitopes of the CYP2D6 antigen, and half recognize linear epitopes. Some HCV+/LKM1+ sera demonstrated antibodies against the AIH type 2 main antigenic site of the CYP2D6. Screening of HCV RNA should be performed before starting treatment of presumed autoimmune hepatitis associated with LKM1.

Prevalence of GBV-C/HGV-RNA, virus genotypes, and anti-E2 antibodies in autoimmune hepatitis

OBJECTIVE

We investigated the prevalence of hepatitis G-RNA (GBV-C/HGV-RNA), a recently cloned new flavivirus, and of antibodies to the envelope 2 antigen (anti-E2), a marker of past infection, in patients with autoimmune hepatitis, and compared it with the prevalence in patients with chronic viral hepatitis and healthy control individuals.

METHODS

Sera of 63 patients with autoimmune hepatitis were studied for the presence of GBV-C/HGV-RNA by reverse-transcription polymerase chain reaction and for anti-E2 by enzyme-linked immunosorbent assay. GBV-C/HGV genotypes were determined by genome sequencing.

RESULTS

Patients with autoimmune hepatitis had a similar high prevalence of GBV-C/HGV-RNA and anti-E2 antibodies as patients with chronic viral hepatitis B or C. GBV-C/HGV-RNA was found significantly more often in patients with autoimmune hepatitis (11%, p = 0.045), hepatitis B (16%, p = 0.004), or hepatitis C (21%, p = 0.001) than in healthy controls (2%). The prevalence of anti-E2 antibodies in patients with autoimmune hepatitis was not different from healthy controls (17% vs 13%, NS). The various subtypes of autoimmune hepatitis had similar prevalence rates of GBV-C/HGV-RNA as patients with liver-kidney microsomal antibody-positive hepatitis C. All of our anti-E2+ (GBV-C/HGV-RNA-) patients were positive for anti-smooth-muscle antibody, whereas only 29% of GBV-C/HGV-RNA+ (anti-E2-) patients were positive (p = 0.025). All seven of the GBV-C/HGV-RNA+ patients with autoimmune hepatitis had genotype 2a, which is also the most prevalent genotype in our region.

CONCLUSION

The prevalence of GBV-C/HGV-RNA is significantly increased in patients with autoimmune hepatitis, compared with healthy controls, and is similar to the increased prevalence seen in chronic hepatitis B or C patients. Anti-E2 positivity was associated with antibodies against smooth-muscle antigen in all cases. All GBV-C/HGV+ autoimmune hepatitis patients were infected with genotype 2a.

Molecular mimicry of human cytochrome P450 by hepatitis C virus at the level of cytotoxic T cell recognition

Hepatitis C virus (HCV) is thought to be involved in the pathogenesis of autoimmune hepatitis (AIH) type 2, which is defined by the presence of type I antiliver kidney microsome autoantibodies directed mainly against cytochrome P450 (CYP)2D6 and by autoreactive liver infiltrating T cells. Virus-specific CD8(+) cytotoxic T lymphocytes (CTLs) that recognize infected cells and contribute to viral clearance and tissue injury during HCV infection could be involved in the induction of AIH. To explore whether the antiviral cellular immunity may turn against self-antigens, we characterized the primary CTL response against an HLA-A*0201-restricted HCV-derived epitope, i.e., HCV core 178-187, which shows sequence homology with human CYP2A6 and CYP2A7 8-17. To determine the relevance of these homologies for the pathogenesis of HCV-associated AIH, we used synthetic peptides to induce primary CTL responses in peripheral blood mononuclear cells of healthy blood donors and patients with chronic HCV infection. We found that the naive CTL repertoire of both groups contains cross-reactive CTLs inducible by the HCV peptide recognizing both CYP2A6 and CYP2A7 peptides as well as endogenously processed CYP2A6 protein. Importantly, we failed to induce CTLs with the CYP-derived peptides that showed a lower capacity to form stable complexes with the HLA-A2 molecule. These findings demonstrate the potential of HCV to induce autoreactive CD8(+) CTLs by molecular mimicry, possibly contributing to virus-associated autoimmunity.

Development of cytochrome P450 2D6-specific LKM-autoantibodies following liver transplantation for Wilson's disease -- possible association with a steroid-resistant transplant rejection episode

BACKGROUND/AIMS

Antibodies to cytochrome P450 2D6, also known as LKM1-autoantibodies, are characteristic for a subgroup of patients with autoimmune hepatitis, but can also occasionally be found in hepatitis C. We observed the occurrence of LKM1-autoantibodies 4 months after liver transplantation for Wilson's disease, in close association with a steroid-resistant rejection episode, in the absence of evidence for autoimmune hepatitis or hepatitis C.

METHODS

Sera from several time points prior to and following transplantation were tested for LKM-reactivity by immunofluorescence, ELISA and Western blotting. Antigen specificity was confirmed by Western blotting analysis on different cytochrome P450 isoenzymes. The absence of viral hepatitis C and hepatitis G virus infection was confirmed by polymerase chain reaction. The serum of the organ donor was also tested.

RESULTS

All the sera prior to transplantation and up to 4 months after transplantation were LKM-negative by all assay systems used. In the course of a steroid-resistant rejection episode at this time, the patient developed LKM antibodies at high titre (70% in inhibition ELISA) and has remained positive since (now more than 4 years). Reactivity was exclusively to the cytochrome isoenzyme 2D6. Hepatitis C infection never occurred, but hepatitis G was transiently present many years prior to transplantation. The donor serum was negative for all autoantibodies and for hepatitis C and G virus infection.

DISCUSSION

We here describe a patient developing LKM1-autoantibodies without evidence of autoimmune or viral hepatitis. The close temporal association with a transplant rejection episode suggests immunological mechanisms of rejection together with hepatocellular injury as a pathogenetic mechanism.

HCV and diabetes mellitus: evidence for a negative association

OBJECTIVE

Uncontrolled, retrospective clinical studies have recently claimed that HCV infection could trigger the onset of diabetes mellitus (DM). We sought to verify the association between DM and liver diseases of different etiology, stage, and severity in a prospective study including gender- and age-matched controls.

METHODS

Two hundred forty-seven patients with liver cirrhosis (184 men, 116 with an associated hepatocellular carcinoma, 34% in Child-Pugh's class A) were evaluated (group 1). One hundred fifty-seven (63.5) of them were HCV positive, 38 (15.5%) HBV positive, 49 (19.8%) alcohol abusers, and three (1.2%) cryptogenic. Two control groups were also included. The first control group consisted of 138 patients with chronic hepatitis due to HCV infection (73.9%), HBV infection (15.9%), or alcohol abuse (10.2%) (group 2). The second control group included 494 patients with an acute osteoarticular trauma, age- and gender-matched with patients in group 1 (group 3).

RESULTS

Diabetes mellitus was present in 32.3%, 3.6%, and 9.7% of patients in groups 1, 2, and 3, respectively. When compared with controls (group 3), DM was significantly less frequent in group 2 (p < 0.004) and significantly more frequent in group 1 (p < 0.0001). The prevalence of DM was not different among patients with HCV, HBV infection, or alcohol abuse. In group 3, the prevalence of DM appeared to increase steadily with age. On the contrary, in patients with liver cirrhosis (group 1) DM was detected in about 20-30% of cases in all decades of age. In group 2, diabetics were found only in the 7th and 8th decades of life. At multivariate analysis cirrhosis and age were the only two factors independently associated with DM; odds ratios were 12.5 (95% confidence interval [C.I.], 6.74-20.4) for cirrhosis, and 1.47 for age (95% C.I. 0.39-2.55).

CONCLUSIONS

Our findings disprove HCV infection as a trigger factor for DM, which should not be listed among the various extrahepatic manifestations of this viral infection.

Acute exacerbation of autoimmune liver disease associated with hantaviral infection

Hantavirus is known to cause haemorrhagic fever with renal syndrome (HFRS). Although liver dysfunction has been reported in HFRS, hepatic manifestations of hantaviral infection have not been well described. We describe a case of autoimmune cholangitis in which an exacerbation of hepatitis was associated with hantaviral infection. Seroconversion of both IgG- and IgM-class antibodies to hantavirus was noted coincident with acute exacerbation of hepatitis, which was resolved promptly by treatment with corticosteroid. No extrahepatic manifestations were noted. This case suggests that hantavirus may trigger acute exacerbation of autoimmune liver disease without extrahepatic manifestations and that it may cause community-acquired hepatitis.

Chronic hepatitis C associated with anti-liver/kidney microsome-1 antibody is not a subgroup of autoimmune hepatitis

To determine whether "autoimmune hepatitis type IIb" should be categorized as a subgroup of autoimmune hepatitis, we conducted a clinicopathological study of 25 adult Japanese patients who were positive for anti-liver/kidney microsome-1 (anti-LKM-1) anti-body and infected with the hepatitis C virus (HCV). Anti-LKM-1 was determined by indirect immunofluorescence and by the double immunodiffusion assays we have developed. Twenty-two patients did not present any unusual symptoms or any associated diseases during the course of their chronic HCV infection. The spectrum of HCV genotypes of these patients did not significantly differ from that of anti-LKM-1-negative Japanese patients with chronic hepatitis C. Histological examination of liver biopsy specimens showed the usual characteristics of chronic hepatitis C and lack of characteristics of autoimmune hepatitis type I. No disease-specific HLA haplotypes were noted, and HLA-DR4, which is detectable in 88.7% of Japanese patients with autoimmune hepatitis type I, was detected in only 50.0% of our group, the same rate as the background frequency. Prednisolone was effective in none of the six patients treated, but interferon was effective in six of ten treated patients (60%). From these results, we conclude that "autoimmune hepatitis type IIb" should not be categorized as autoimmune hepatitis, and that this subgroup is essentially chronic hepatitis C in which an autoantibody has been produced during the course of chronic HCV infection.

Hepatotropic viruses and autoimmunity 1997

Autoimmune hepatitis is a disease of unknown cause. Apart from genetic markers such as HLA DR3 and HLA DR4, female predominance, hypergammaglobulinaemia and characteristic autoantibodies are diagnostic hallmarks. Several viruses have been discussed to induce autoimmune hepatitis, among them all major hepatotropic viruses, Epstein-Barr virus and herpes simplex virus. It seems that herpes viruses may be responsible in at least some cases of patients with autoimmune hepatitis type 2. Furthermore, hepatotropic viruses like hepatitis C and hepatitis D virus may cause autoimmune phenomena which are similar to those in idiopathic autoimmune hepatitis. LKM-1 antibodies in hepatitis C and LKM-3 antibodies in hepatitis D may cause diagnostic problems. LKM-1 antibodies in hepatitis C are directed either against cytochrome P450 2D6 or other yet unidentified microsomal antigens. As in hepatitis C the antimicrosomal autoantibody response in hepatitis D is more heterogeneous. These LKM-3 antibodies react with several epitopes on proteins of family 1 and 2 UDP-glucuronosyltransferases (UGT). Additional autoantibodies are seen in hepatitis D virus infection. Liver diseases are models to study autoimmune disease, drug-induced and virus-induced autoimmunity in humans.

GBV-C/HGV is not the major cause of autoimmune hepatitis

Recently, GBV-C and HGV-two isolates of the same new flavivirus-were identified in serum samples of patients with indeterminate hepatitis and posttransfusion hepatitis, respectively. The pathogenic relevance of these viruses is still uncertain. As viral infections are presumed to trigger autoimmune processes, we investigated GBV-C in autoimmune hepatitis as well as in cryptogenic hepatitis, and compared the prevalences to patients with chronic viral hepatitis and those of blood donors. We found only a slightly higher prevalence of the virus in cryptogenic (12%) and autoimmune hepatitis type I-III (6.7%, 10%, and 12.5%) compared to blood donors (4.7%). In contrast, patients with viral hepatitis B, C, and D were more frequently infected with GBV-C (16%, 20%, 36%). These results suggest that GBV-C is not a major cause for inducing autoimmunity and leading to autoimmune hepatitis. We analyzed the nucleic acid sequences of a representative number of GBV-C positive patients (24/42) and found a broad range of nucleotide similarity in the NS3 helicase region (74-100%) among the isolates and the prototype sequences. However, we could not identify a specific sequence, which would point to a certain strain or subtype of the virus associated with autoimmune or cryptogenic liver disease.

Low hepatitis C viremia levels in patients with anti-liver/kidney microsomal antibody type 1 positive chronic hepatitis

BACKGROUND/AIMS

The majority of adult patients positive for anti-liver-kidney microsomal antibody are also positive for anti-hepatitis C virus and serum HCV RNA. In these patients the role played by hepatitis C virus infection in the progression of liver damage and its relationship with anti-liver-kidney microsomal antibody are, however, still a matter of debate.

METHODS

To clarify this point we have compared hepatitis C viremia in sera from 31 hepatitis C virus-related chronic hepatitis patients positive for anti-liver-kidney microsomal antibody with that of 31 patients with hepatitis C virus-related chronic hepatitis without autoantibodies using a newly developed competitive reverse transcription-polymerase chain reaction technique. Reverse transcription-polymerase chain reaction was performed using a synthetic competitor of a length similar to that of wild template (71 bp vs 86 bp).

RESULTS

The results obtained have been related to hepatitis C virus genotypes. Anti-liver-kidney microsomal antibody/anti-HCV positive patients show a median value of hepatitis C virus genome molecules (626829/ml, range 9780-25651424), significantly lower than anti-liver-kidney microsomal antibody negative/anti-HCV positive patients (10158314/ml, range 101822-67429974) (p < 0.001). No hepatitis C virus genotype was significantly associated with anti-liver-kidney microsomal antibody, although a predominance of genotype 1 (subtypes a and b) has been observed in these patients.

CONCLUSIONS

Since a low hepatitis C viremia has been observed in anti-liver-kidney microsomal antibody positive patients with disease severity comparable to that of patients without autoantibodies, it is conceivable that in them autoimmune mechanisms may cooperate with viral infection in sustaining disease activity.