Frequency and significance of antibodies to asialoglycoprotein receptor in type 1 autoimmune hepatitis

Diagnosis and Management of Autoimmune Hepatitis: Current Status and Future Directions

Autoimmune hepatitis is characterized by autoantibodies, hypergammaglobulinemia, and interface hepatitis on histological examination. The features lack diagnostic specificity, and other diseases that may resemble autoimmune hepatitis must be excluded. The clinical presentation may be acute, acute severe (fulminant), or asymptomatic; conventional autoantibodies may be absent; centrilobular necrosis and bile duct changes may be present; and the disease may occur after liver transplantation or with features that suggest overlapping disorders. The diagnostic criteria have been codified, and diagnostic scoring systems can support clinical judgment. Nonstandard autoantibodies, including antibodies to actin, α-actinin, soluble liver antigen, perinuclear antineutrophil antigen, asialoglycoprotein receptor, and liver cytosol type 1, are tools that can support the diagnosis, especially in patients with atypical features. Prednisone or prednisolone in combination with azathioprine is the preferred treatment, and strategies using these medications in various doses can ameliorate treatment failure, incomplete response, drug intolerance, and relapse after drug withdrawal. Budesonide, mycophenolate mofetil, and calcineurin inhibitors can be considered in selected patients as frontline or salvage therapies. Molecular (recombinant proteins and monoclonal antibodies), cellular (adoptive transfer and antigenic manipulation), and pharmacological (antioxidants, antifibrotics, and antiapoptotic agents) interventions constitute future directions in management. The evolving knowledge of the pathogenic pathways and the advances in technology promise new management algorithms.

Transitioning from Idiopathic to Explainable Autoimmune Hepatitis

Autoimmune hepatitis lacks an identifiable cause, and its diagnosis requires the exclusion of etiologically defined diseases that resemble it. Insights into its pathogenesis are moving autoimmune hepatitis from an idiopathic to explainable disease, and the goal of this review is to describe the insights that are hastening this transition. Two types of autoimmune hepatitis are justified by serological markers, but they also have distinctive genetic associations (DRB1 and DQB1 genes) and autoantigens. DRB1 alleles are the principal susceptibility factors in white adults, and a six amino acid sequence encoded in the antigen-binding groove of class II molecules of the major histocompatibility complex can influence the selection of autoantigens. Polymorphisms, including variants of SH2B3 and CARD10 genes, may affect immune reactivity and disease severity. The cytochrome mono-oxygenase, CYP2D6, is the autoantigen associated with type 2 autoimmune hepatitis, and it shares homologies with multiple viruses that might promote self-intolerance by molecular mimicry. Chemokines, especially CXCL9 and CXCL10, orchestrate the migration of effector cells to sites of injury and are associated with disease severity. Cells of the innate and adaptive immune responses promote tissue damage, and possible deficiencies in the number and function of regulatory T cells may facilitate the injurious process. Receptor-mediated apoptosis is the principal mechanism of hepatocyte loss, and cell-mediated and antibody-dependent mechanisms of cytotoxicity also contribute. Insights that explain autoimmune hepatitis will allow triggering exogenous antigens to be characterized, risk management to be improved, prognostic indices to be refined, and site-specific therapeutic interventions to emerge.

Association Between TT Virus Infection and Cirrhosis in Liver Transplant Patients

BACKGROUND

Cirrhosis is one of the most severe liver complications, with multiple etiologies. The torque teno virus (TTV), also known as transfusion transmitted virus, which has a high incidence in the world population, is one of the possible increasing risk factors in patients with idiopathic fulminant hepatitis and cryptogenic cirrhosis.

OBJECTIVES

The aim of this study was to evaluate solitary and co-infection with TTV, in patients with cryptogenic and determined cause of cirrhosis.

PATIENTS AND METHODS

In this cross-sectional study, 200 liver transplant patients were consecutively recruited between years 2007 and 2011. Patients were classified, based on recognition of the etiology of cirrhosis to determined (n = 81) and cryptogenic (n = 119) patient groups. The existence of TTV infection was analyzed, using a semi-nested polymerase chain reaction method. The presence of hepatitis B virus (HBV) infective markers, including HBV DNA, hepatitis B surface antigen (HBsAg), hepatitis B e antigen (HBeAg), hepatitis B core antibody (HBcAb), and hepatitis B e antibody (HBeAb), was evaluated using qualitative polymerase chain reaction and enzyme linked immunosorbent assay protocols, respectively.

RESULTS

The TTV infection was found in 37 of 200 (18.5%) and 53 of 200 (26.5%) plasma and tissue samples of studied liver transplanted patients, respectively. The TTV genomic DNA was found in 32 (26.9%) and 28 (23.5%) of 119 liver tissue and plasma samples of transplanted patients with cryptogenic cirrhosis, respectively. The genomic DNA of TTV was also diagnosed in 21 (25.9%) and nine (11.1%) of the 81 liver tissue and plasma samples of patients with determined cirrhosis, respectively. Significant associations were found between TTV infection with HBV molecular and immunologic infective markers, in liver transplanted patients, with determined and cryptogenic cirrhosis.

CONCLUSIONS

The diagnosis of the high frequency of solitary TTV and co-infection with HBV, in both liver transplanted patients with cryptogenic and determined cirrhosis, emphasized on the importance of TTV infection in the development of cirrhosis, especially in the cases of cryptogenic ones, prompting for further studies the confirm this agent in the etiology of determined cirrhosis.

Autoimmune hepatitis, one disease with many faces: Etiopathogenetic, clinico-laboratory and histological characteristics

Autoimmune hepatitis (AIH) is an unresolving progressive liver disease of unknown etiology characterized by hypergammaglobulinemia, autoantibodies detection and interface hepatitis. Due to the absence of specific diagnostic markers and the large heterogeneity of its clinical, laboratory and histological features, AIH diagnosis may be potentially difficult. Therefore, in this in-depth review we summarize the substantial progress on etiopathogenesis, clinical, serological and histological phenotypes of AIH. AIH has a global distribution affecting any age, both sexes and all ethnic groups. Clinical manifestations vary from asymptomatic to severe or rarely fulminant hepatitis. Hypergammaglobulinemia with selective elevation of IgG is found in most cases. Autoimmune attack is perpetuated, possibly via molecular mimicry, and favored by the impaired control of T-regulatory cells. Histology (interface hepatitis, emperipolesis and hepatic rosette formation) and autoantibodies detection although not pathognomonic, are still the hallmark for a timely diagnosis. AIH remains a major diagnostic challenge. AIH should be considered in every case in the absence of viral, metabolic, genetic and toxic etiology of chronic or acute hepatitis. Laboratory personnel, hepato-pathologists and clinicians need to become more familiar with disease expressions and the interpretation of liver histology and autoimmune serology to derive maximum benefit for the patient.

Diagnostic and predictive significance of autoantibody profiles in autoimmune liver disease

Autoimmune liver disease (AILD) is a chronic inflammatory disease presumably induced by a disorder of immune homeostasis within the liver, which can lead to damage to or loss of the hepatic parenchyma or bile duct epithelia. Indirect immunofluorescence and antibody specificity assays are important tools for the diagnosis of AILD. Over the last decade, there have been an increasing number of newly characterized target antigens for autoantibodies in AILD. Autoantibodies, as biomarkers, are used not only for disease diagnosis, but also for monitoring disease activity and progression and predicting prognosis and treatment responses.

Autoantibodies in liver disease: important clues for the diagnosis, disease activity and prognosis

It has been well established that numerous kinds of autoantibodies have been detected in liver disease. Some kinds of autoantibodies may be helpful in the diagnosis of autoimmune liver diseases including autoimmune hepatitis, primary biliary cirrhosis or primary sclerosing cholangitis. However, these autoantibodies are present even in sera of patients with viral hepatitis, drug-induced hepatitis, alcoholic liver disease, non-alcoholic fatty liver disease and hepatocelluar carcinoma as well as in sera of patients with autoimmune liver diseases. Other kinds of autoantibodies are recognized as predictive hallmarks for disease activity or prognosis in liver diseases. On the other hand, treatment with interferon initiates the production of several types of autoantibodies in patients with chronic hepatitis C virus infection. Some of autoantibodies induced by interferon may postulate the treatment outcome in those patients. Recent studies also revealed the close correlation between oxidative stress and the production of autoantibodies in liver diseases. This article primarily reviews the recent advances of autoantibodies in the liver diseases and discusses the clinical significance of these autoantibodies.

Autoimmune hepatitis as a unique form of an autoimmune liver disease: immunological aspects and clinical overview

Autoimmune hepatitis (AIH) is a unique form of immune-mediated disease that attacks the liver through a variety of immune mechanisms. The outcomes of AIH are either acute liver disease, which can be fatal, or, more commonly, chronic progressive liver disease, which can lead to decompensated liver cirrhosis if left untreated. AIH has characteristic immunological, and pathological, features that are important for the establishment of the diagnosis. More importantly, most patients with AIH have a favorable response to treatment with prednisolone and azathioprine, although some patients with refractory AIH or more aggressive disease require more potent immune-suppressant agents, such as cyclosporine or Mycophenolate Mofetil. In this paper, we discuss the immunological, pathological and clinical features of AIH, as well as the standard and alternative treatments for AIH.

Asialoglycoprotein receptor (ASGPR): a peculiar target of liver-specific autoimmunity

Asialoglycoprotein receptor (ASGPR) autoantibodies have been considered specific markers of autoimmune hepatitis (AIH). The exact mechanisms responsible for the development of these autoantibodies and leading to autoimmunity to this peculiar liver receptor remain elusive. Furthermore, loss of T cell tolerance to ASGPR has been demonstrated in patients with AIH, but it is poorly understood whether such liver-specific T cell responses bear a pathogenic potential and/or participate in the precipitation of AIH. Newly developed enzyme-linked immunosorbent assays have led to the investigation of the sensitivity and specificity of anti-ASGPR antibodies for AIH. The present review provides an overview of the diagnostic and clinical relevance of anti-ASGPR antibodies. A thorough investigation of the autoreactivity against ASGPR may assist efforts to understand liver autoimmunity in susceptible individuals.

Systematic review: managing suboptimal treatment responses in autoimmune hepatitis with conventional and nonstandard drugs

BACKGROUND

Corticosteroid treatment for autoimmune hepatitis has been shown by randomised controlled clinical trials to ameliorate symptoms, normalise liver tests, improve histological findings and extend survival. Nevertheless, suboptimal responses to corticosteroid treatment still occur.

AIM

To describe the current definitions, frequencies, clinical relevance and treatment options for suboptimal responses, and to discuss alternative medications that have been used off-label for these occurrences.

METHODS

Literature search was made for full-text papers published in English using the keyword 'autoimmune hepatitis'. Authors' personal experience and investigational studies also helped to identify important contributions to the literature.

RESULTS

Suboptimal responses to standard therapy include treatment failure (7%), incomplete response (14%), drug toxicity (13%) and relapse after drug withdrawal (50-86%). The probability of a suboptimal response prior to treatment is higher in young patients and in patients with a severe presentation, jaundice, high MELD score at diagnosis, multilobular necrosis or cirrhosis, antibodies to soluble liver antigen, or inability to improve by clinical indices within two weeks or by MELD score within 7 days of conventional corticosteroid treatment. Management strategies have been developed for the adverse responses and nonstandard drugs, including mycophenolate mofetil, budesonide, ciclosporin, tacrolimus, sirolimus and rituximab, are emerging as rescue therapies or alternative frontline agents.

CONCLUSIONS

Once diagnosed, the suboptimal response should be treated by a highly individualised and well-monitored regimen, preferentially using first-line therapy. Nonstandard drugs warrant consideration as salvage or second-line therapies.

Asialoglycoprotein receptor (ASGPR) as target autoantigen in liver autoimmunity: lost and found

Asialoglycoprotein receptor (ASGPR) has attracted the attention of liver immunologists for many years. This liver-specific lectin was found to be a major B and T cell autoantigenic target in patients with autoimmune liver diseases, and in particular in autoimmune hepatitis (AIH). This review discusses the biological significance of ASGPR and its relevance to the pathogenesis of autoimmune and virus-triggered liver diseases. We also discuss emerging data on the diagnostic and clinical relevance of anti-ASGPR antibodies in light of recent reports based on commercially available anti-ASGPR enzyme-linked immunosorbent assays. Finally, we critically revisit the data reporting on disease-specific cellular immune responses against ASGPR and their relevance in relation to the pathogenesis of AIH.

Autoantibody-negative autoimmune hepatitis

Autoimmune hepatitis has a variable clinical phenotype, and the absence of conventional autoantibodies does not preclude its diagnosis or need for treatment. The goals of this review are to describe the frequency and nature of autoantibody-negative autoimmune hepatitis, indicate its outcome after corticosteroid treatment, and increase awareness of the diagnosis in patients with unexplained acute and chronic hepatitis. The frequency of presumed autoantibody-negative autoimmune hepatitis in patients with acute and acute severe presentations is ≤7%, and its frequency in patients with chronic presentations is 1-34%. Patients with acute presentations can have normal serum γ-globulin levels, centrilobular zone 3 necrosis, and low pre-treatment international diagnostic scores. Liver tissue examination is essential for the diagnosis, and hepatic steatosis can be a co-morbid feature. The comprehensive international scoring system can support but never override the clinical diagnosis pre-treatment, and non-standard serological markers should be sought if the clinical diagnosis is uncertain or the diagnostic score is low. A 3-month treatment trial with corticosteroids should be considered in all patients, regardless of the serological findings, and improvements have occurred in 67-87% of cases. Autoantibody-negative autoimmune hepatitis may be associated with an autoantibody outside the conventional battery; it may have a signature autoantibody that is still undiscovered, or its characteristic autoantibodies may have been suppressed or have a delayed expression. The pathogenic mechanisms are presumed to be identical to those of classical disease. Autoantibody-negative autoimmune hepatitis is an infrequent but treatable disease that must be considered in unexplained acute and chronic hepatitis.

Cryptogenic chronic hepatitis and its changing guise in adults

Cryptogenic chronic hepatitis is a disease that is unexplained by conventional clinical, laboratory and histological findings, and it can progress to cirrhosis, develop hepatocellular carcinoma, and require liver transplantation. The goals of this review are to describe the changing phenotype of cryptogenic chronic hepatitis in adults, develop a diagnostic algorithm appropriate to current practice, and suggest treatment options. The frequency of cryptogenic hepatitis is estimated at 5.4%. Cryptogenic cirrhosis is diagnosed in 5-30% of patients with cirrhosis, and it is present in 3-14% of adults awaiting liver transplantation. Nonalcoholic fatty liver disease has been implicated in 21-63% of patients, and autoimmune hepatitis is a likely diagnosis in 10-54% of individuals. Viral infections, hereditary liver diseases, celiac disease, and unsuspected alcohol or drug-induced liver injury are recognized infrequently in the current cryptogenic population. Manifestations of the metabolic syndrome heighten the suspicion of nonalcoholic fatty liver disease, and the absence of hepatic steatosis does not discount this possibility. The diagnostic scoring system of the International Autoimmune Hepatitis Group can support the diagnosis of autoimmune hepatitis in some patients. Certain genetic mutations may have disease-specificity, and they suggest that some patients may have an independent and uncharacterized disease. Corticosteroid therapy is effective in patients with autoimmune features, and life-style changes and specific therapies for manifestations of the metabolic syndrome are appropriate for all obese patients. The 1- and 5-year survivals after liver transplantation have ranged from 72-85% to 58-73%, respectively.

Biological significance of autoantibodies to asialoglycoprotein receptor in patients with type Ⅰ autoimmune hepatitis

AIM: To investigate the differences in clinical, biochemical, immunoserologic, genetic, histological features and response to treatment between patients with type 1 autoimmune hepatitis (AIH-Ⅰ) who were positive for autoantibodies to asialoglycoprotein receptor (ASGPR) and those negative for anti-ASGPR.

METHODS: A total of 79 patients with AIH-Ⅰ were screened for the presence of anti-ASGPR by ELISA and were divided into anti-ASGPR-positive group and anti-ASGPR-negative group.

RESULTS: There were 59 patients in the anti-ASGPR-positive group and 20 patients in the anti-ASGPR-positive group. No significant differences were found between anti-ASGPR-positive and-negative patients in age, gender, alanine transaminase (ALT) activity, aspartate aminotransferase (AST) activity, alkaline phosphatase (ALP) activity, gamma glutanmic transpeptidase (γ-GT) activity, antinuclear autoantibodies (ANA), smooth muscle autoantibodies (SMA), DR3, and DR4. The levels of immunoglobulin G, C3, histological inflammatory activity and fibrosis, and response to treatment differed significantly between the two groups.

CONCLUSION: The presence of anti-ASGPR is correlated, to a certain extent, with inflammatory activity, pathological changes, and response to treatment in patients with AIH-Ⅰ.

Autoantibodies as prognostic markers in autoimmune liver disease

Certain autoantibodies in autoimmune liver disease have prognostic implications that are under-utilized and under-developed. The goals of this review are to indicate progress in characterizing the autoantibodies with prognostic connotations and to indicate the feasibility and importance of discovering other markers. Prime source and review articles in English were selected by a Medline search through 2010. Antibodies to soluble liver antigen, actin, liver cytosol type 1, asialoglycoprotein receptor, chromatin, cyclic citrullinated peptide, and uridine glucuronosyltransferases have been associated with the occurrence, severity, and progression of autoimmune hepatitis, and antibodies to Sp100, gp210, and centromere have had similar implications in primary biliary cirrhosis. Antibodies to soluble liver antigen have shown the most promise in autoimmune hepatitis as they have been associated with severe histological changes, long durations of treatment, relapse after drug withdrawal, and high frequency of liver failure. Antibodies to the nuclear rim pore protein, gp210, have shown the most promise in primary biliary cirrhosis as they have been associated with severe interface hepatitis, lobular inflammation, and progression to liver failure. The major limitations of the autoantibodies have been their lack of standardized assays, low negative predictabilities, and fluctuating levels. Performance parameters will improve as critical pathogenic pathways, comprehensive testing batteries, and standardized assays through international exchange workshops are developed. Progress has been made in identifying the serological markers of prognosis in autoimmune liver disease, and they promise to reflect critical disease mechanisms and enhance patient management.

The role of autoantibodies as diagnostic markers of autoimmune hepatitis

Autoantibody testing is the first step towards the diagnosis of autoimmune hepatitis, and it is essential in the evaluation of acute and chronic hepatitis of undetermined cause and allograft dysfunction following liver transplantation. A standard diagnostic repertoire has been promulgated, and other autoantibodies are emerging that may have prognostic value. Supplemental autoantibodies may prove useful in assessing patients who lack the standard markers or who are distinctive among those with conventional markers. Serologic testing will improve as assays are standardized by serum exchange workshops, core diagnostic batteries are codified and promulgated, and markers emerge that are tightly associated with pathogenic mechanisms, and closely reflect disease activity and outcome.

Autoimmune liver serology: Current diagnostic and clinical challenges

Liver-related autoantibodies are crucial for the correct diagnosis and classification of autoimmune liver diseases (AiLD), namely autoimmune hepatitis types 1 and 2 (AIH-1 and 2), primary biliary cirrhosis (PBC), and the sclerosing cholangitis variants in adults and children. AIH-1 is specified by anti-nuclear antibody (ANA) and smooth muscle antibody (SMA). AIH-2 is specified by antibody to liver kidney microsomal antigen type-1 (anti-LKM1) and anti-liver cytosol type 1 (anti-LC1). SMA, ANA and anti-LKM antibodies can be present in de-novo AIH following liver transplantation. PBC is specified by antimitochondrial antibodies (AMA) reacting with enzymes of the 2-oxo-acid dehydrogenase complexes (chiefly pyruvate dehydrogenase complex E2 subunit) and disease-specific ANA mainly reacting with nuclear pore gp210 and nuclear body sp100. Sclerosing cholangitis presents as at least two variants, first the classical primary sclerosing cholangitis (PSC) mostly affecting adult men wherein the only (and non-specific) reactivity is an atypical perinuclear antineutrophil cytoplasmic antibody (p-ANCA), also termed perinuclear anti-neutrophil nuclear antibodies (p-ANNA) and second the childhood disease called autoimmune sclerosing cholangitis (ASC) with serological features resembling those of type 1 AIH. Liver diagnostic serology is a fast-expanding area of investigation as new purified and recombinant autoantigens, and automated technologies such as ELISAs and bead assays, become available to complement (or even compete with) traditional immunofluorescence procedures. We survey for the first time global trends in quality assurance impacting as it does on (1) manufacturers/purveyors of kits and reagents, (2) diagnostic service laboratories that fulfill clinicians’ requirements, and (3) the end-user, the physician providing patient care, who must properly interpret test results in the overall clinical context.

Autoimmune hepatitis. Part B: diagnosis

Diagnostic criteria have been codified by the International Autoimmune Hepatitis Group, and a scoring system can quantify the strength of the diagnosis and over-ride the impact of absent or inconsistent features. The absence of a definable etiologic agent and precise diagnostic test, implies that the diagnosis may be missed or misapplied. Centrilobular (zone 3) necrosis may be an early form of autoimmune hepatitis and this pattern can transform to the classical pattern of interface hepatitis. An acute severe or fulminant presentation is possible, and different ethnic groups may have different manifestations and outcomes. Asymptomatic patients at presentation commonly become symptomatic, and treatment decisions must be based on objective features of disease severity and not the presence or absence of symptoms. Concurrent autoimmune diseases are frequent, and they may constitute an autoimmune polyglandular syndrome associated with a single gene mutation. Emerging autoantibodies of possible prognostic value are antibodies to soluble liver antigen/liver pancreas, asialoglycoprotein receptor, actin, and liver cytosol type 1. HLA DRB1*03, *04, *03-*04, *07, *13 and DQB1*02 are associated with the occurrence, clinical phenotype and outcome of autoimmune hepatitis. Variant syndromes should be suspected if cholestatic features are prominent and conventional treatment is ineffective.

Autoimmune hepatitis, from mechanisms to therapy

In 1950, Waldenström was the first to describe a chronic form of hepatitis in young women. Subsequently, the disease was found to be associated with other autoimmune syndromes and was later termed "lupoid hepatitis" because of the presence of antinuclear antibodies. In 1965, it became designated by Mackay et al. as "autoimmune hepatitis" at an international meeting, at which the general concept of autoimmunity was endorsed by the scientific community. In the early 1960s and 1970s, the value of immunosuppressive therapy with glucocorticoids and/or azathioprine was well documented in several studies. The original association of autoimmune hepatitis (AIH) and HLA alleles, which has remarkably stood the test of time, was published in 1972. In the 1970s and 1980s, several autoantibodies were identified in patients with autoimmune hepatitis directed against proteins of the endoplasmatic reticulum expressed in liver and kidney and against soluble liver antigens. Subsequently, the molecular targets of these antibodies were identified and more precisely characterized. In the last two decades many additional pieces of the AIH puzzle have been collected leading to the identification of additional antibodies and genes associated with AIH and to the emergence of new therapeutic agents. Meanwhile, the immunoserological and genetic heterogeneity of AIH is well established and it has become obvious that clinical manifestations, disease behavior, and treatment outcome may vary by racial groups, geographical regions and genetic predisposition. Currently, the International Autoimmune hepatitis group is endorsing multi-center collaborative studies to more precisely define the features at disease presentation and to define prognostic indices and appropriate treatment algorithms. Given the importance of serological testing, the IAHG is also working on guidelines and procedures for more reliable and standardized testing of autoantibodies.

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.

Chloroquine for the maintenance of remission of autoimmune hepatitis: results of a pilot study

BACKGROUND: Due to the risks related to long-term treatment with prednisone and azathioprine, most clinicians try to withdraw these drugs when patients with autoimmune hepatitis are in remission. However, there is a high probability of relapse, and most patients end up receiving maintenance treatment. AIM: To evaluate the safety and efficacy of maintenance treatment with chloroquine in the prevention of autoimmune hepatitis relapses. METHODS: Classical treatment was stopped after achievement of biochemical and histological remission of autoimmune hepatitis. Chloroquine diphosphate, 250 mg daily, was given for at least 12 months or until the occurrence of relapses defined by levels of aminotransferases at least twice the upper normal values. RESULTS: Fourteen patients were consecutively treated and compared with 18 historical controls. There was a 6.49 (1.38-30.30) greater chance of relapse in the historical controls when compared with patients treated with chloroquine (72.2% x 23.5%; 0.031). CONCLUSIONS: The group treated with chloroquine had a lower frequency of relapses. Chloroquine was safe in patients with autoimmune hepatitis and hepatic cirrhosis without decompensation, on 250 mg daily up to 2 years. These preliminary results provide a basis for upcoming controlled studies comparing chloroquine with placebo or for maintenance treatment with prednisone and/or azathioprine for the prevention of autoimmune hepatitis relapses.

Autoantibodies against CYP2D6 and other drug-metabolizing enzymes in autoimmune hepatitis type 2

Autoimmune hepatitis (AIH) is a disease of unknown etiology, characterized by liver-related autoantibodies. Autoimmune hepatitis is subdivided into two major types: AIH type 1 is characterized by the detection of ANA, SMA, ANCA, anti-ASGP-R, and anti-SLA/LP. Autoimmune hepatitis type 2 is characterized to be mainly related with drug-metabolizing enzymes as autoantigens, such as anti-LKM (liver-kidney microsomal antigen)-1 against CYP2D6, anti-LKM-2 against CYP2C9-tienilic acid, anti-LKM-3 against UGT1A, and anti-LC1 (liver cytosol antigen)-1 and anti-APS (autoimmune polyglandular syndrome type-1) against CYP1A2, CYP2A6, and others. Anti-LKM-1 sera inhibited CYP2D6 activity in vitro but did not inhibit cellular drug metabolism in vivo. CYP2D6 is the major target autoantigen of LKM-1 and expressed on plasma membrane (PM) of hepatocytes, suggesting a pathogenic role for anti-LKM-1 in liver injury as a trigger. Anti-CYP1A2 was observed in dihydralazine-induced hepatitis, and radiolabeled CYP1A2 disappeared from the PM with a half-life of less than 30 min, whereas microsomal CYP1A2 was stably radiolabeled for several hours. Main antigenic epitopes on CYP2D6 are aa 193-212, aa 257-269, and aa 321-351; and D263 is essential. The third epitope is located on the surface of the protein CYP2D6 and displays a hydrophobic patch that is situated between an aromatic residue (W316) and histidine (H326). Some drugs such as anticonvulsants (phenobarbital, phenytoin, and carbamazepine) and halothane are suggested to induce hepatitis with anti-CYP3A and anti-CYP2E1, respectively. Autoantibodies against CYP11A1, CYP17, and/or CYP21 involved in the synthesis of steroid hormones are also detected in patients with adrenal failure, gonadal failure, and/or Addison disease.

Detection of circulating autoantibodies directed against the asialoglycoprotein receptor using recombinant receptor subunit H1

BACKGROUND/AIMS

The asialoglycoprotein-receptor (ASGPR) is a major liver-specific target autoantigen in autoimmune hepatitis. ASGPR heteromers of two subunits H1 and H2 provide clearance of circulating asialoglycoproteins by receptor-mediated endocytosis. The aim of this study was to establish whether a recombinantly expressed subunit H1 presenting conformational epitopes is capable of detecting autoantibodies against ASGPR in patients with inflammatory liver disease.

METHODS

The major subunit H1 was expressed in human-embryo-kidney 293-cells and prepared by ligand-affinity-chromatography similar to the complete receptor from normal liver. Reactivities of anti-ASGPR positive sera from 219 patients with both recombinant H1 and natural receptor were compared using enzyme-immunoassay (EIA).

RESULTS

194 of 219 sera (88.6%) showed absorbance values on 293-H1 within a range of +/-15% compared to the natural receptor. 145 of 149 sera (97.3%) positive on ASGPR were also positive on recombinant H1. Titers of 61/62 sera (98.4%) revealed no deviation of more than one dilution step. ASGPR reactivity could be inhibited in 29 sera with up to 50 ng/microl of 293-H1.

CONCLUSIONS

These results indicate that the antigenic sites of the human ASGPR are mainly located on the mammalian-expressed subunit H1. Therefore, 293-H1 is a powerful tool for the detection of autoantibodies against ASGPR.

Anti-tRNP(ser)sec/SLA/LP autoantibodies. Comparative study using in-house ELISA with a recombinant 48.8 kDa protein, immunoblot, and analysis of immunoprecipitated RNAs

BACKGROUND

Antibodies against tRNP((ser)sec) (ribonucleoproteins, RNP) have been described in our laboratory as markers of poor outcome in type 1 autoimmune hepatitis (AIH). The antigenic protein has been sequenced and cloned as a 48.8 kDa protein and identified with soluble liver antigen (SLA) and liver-pancreas (LP) antigen. The aim of this paper was to determine the best assay by which to detect these antibodies in type 1 AIH.

METHODS

A simple and reliable enzyme linked immunoassay based on prokaryotically expressed protein was compared with an immunoblot assay using prokaryotically- and eukaryotically-expressed proteins and an assay based on immunoprecipitated RNAs from HeLa cell extracts. Eighty-one sera from 58 patients with type 1 AIH, 168 sera from patients with autoimmune diseases or chronic hepatitis C, and 60 sera from healthy subjects were similarly tested.

RESULTS

The specificity of the assays was 100%, but the frequency of seropositivity was higher in the assay based on immunoprecipitated RNAs (44.4%) than in the enzyme-linked immunosorbent assay (ELISA) (16%) and the immunoblot assay with prokaryotically (12.34%) and eukaryotically (14.8%)-expressed protein. There were no clinical differences between the patients positive by ELISA, immunoblot assay, or immunoprecipitated RNAs.

CONCLUSIONS

These results suggest that the analysis of the immunoprecipitated RNAs is the most useful, sensitive and specific method to detect anti-tRNP((ser)sec)/SLA/LP autoantibodies.

Autoantibodies and autoantigens in autoimmune hepatitis: important tools in clinical practice and to study pathogenesis of the disease

Autoimmune hepatitis (AIH) is a chronic necroinflammatory disease of the liver characterized by hypergammaglobulinemia, characteristic autoantibodies, association with HLA DR3 or DR4 and a favorable response to immunosuppressive treatment. The etiology is unknown. The detection of non-organ and liver-related autoantibodies remains the hallmark for the diagnosis of the disease in the absence of viral, metabolic, genetic, and toxic etiology of chronic hepatitis or hepatic injury. The current classification of AIH and the several autoantibodies/target-autoantigens found in this disease are reported. Current aspects on the significance of these markers in the differential diagnosis and the study of pathogenesis of AIH are also stated. AIH is subdivided into two major types; AIH type 1 (AIH-1) and type 2 (AIH-2). AIH-1 is characterized by the detection of smooth muscle autoantibodies (SMA) and/or antinuclear antibodies (ANA). Determination of antineutrophil cytoplasmic autoantibodies (ANCA), antibodies against the asialoglycoprotein receptor (anti-ASGP-R) and antibodies against to soluble liver antigens or liver-pancreas (anti-SLA/LP) may be useful for the identification of patients who are seronegative for ANA/SMA. AIH-2 is characterized by the presence of specific autoantibodies against liver and kidney microsomal antigens (anti-LKM type 1 or infrequently anti-LKM type 3) and/or autoantibodies against liver cytosol 1 antigen (anti-LC1). Anti-LKM-1 and anti-LKM-3 autoantibodies are also detected in some patients with chronic hepatitis C (HCV) and chronic hepatitis D (HDV). Cytochrome P450 2D6 (CYP2D6) has been documented as the major target-autoantigen of anti-LKM-1 autoantibodies in both AIH-2 and HCV infection. Recent convincing data demonstrated the expression of CYP2D6 on the surface of hepatocytes suggesting a pathogenetic role of anti-LKM-1 autoantibodies for the liver damage. Family 1 of UDP-glycuronosyltransferases has been identified as the target-autoantigen of anti-LKM-3. For these reasons the distinction between AIH and chronic viral hepatitis (especially of HCV) is of particular importance. Recently, the molecular target of anti-SLA/LP and anti-LC1 autoantibodies were identified as a 50 kDa UGA-suppressor tRNA-associated protein and a liver specific enzyme, the formiminotransferase cyclodeaminase, respectively. Anti-ASGP-R and anti-LC1 autoantibodies appear to correlate closely with disease severity and response to treatment suggesting a pathogenetic role of these autoantibodies for the hepatocellular injury. In general however, autoantibodies should not be used to monitor treatment, predict AIH activity or outcome. Finally, the current aspects on a specific form of AIH that may develop in some patients with a rare genetic syndrome, the autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy syndrome (APECED) are also given. Autoantibodies against liver microsomes (anti-LM) are the specific autoantibodies detected in AIH as a disease component of APECED but also in cases of dihydralazine-induced hepatitis. Cytochrome P450 1A2 has been identified as the target-autoantigen of anti-LM autoantibodies in both APECED-related AIH and dihydralazine-induced hepatitis. The latter may indicate that similar autoimmune pathogenetic mechanisms can lead to liver injury in susceptible individuals irrespective of the primary defect. Characterization of the autoantigen-autoantibody repertoire continues to be an attractive and important tool to get access to the correct diagnosis and to gain insight into the as yet unresolved mystery of how hepatic tolerance is given up and AIH ensues.

A novel IgM class autoantibody to a hepatocyte-related 190 kDa molecule in patients with type 1 autoimmune hepatitis

It has been reported that autoantibodies to hepatocytes are frequently found in patients with autoimmune hepatitis (AIH). To elucidate the nature of these hepatocyte-specific autoantibodies, we attempted to generate a hepatocyte-specific monoclonal antibody (MoAb) from Epstein-Barr virus-transformed peripheral blood mononuclear cells obtained from a patient with AIH. We established a single clone, 2E3, that continued to produce an immunoglobulin M (IgM) antibody (lambda-type). This MoAb had the following properties: it reacted mainly with hepatocyte-derived cell lines, rather than with other cell lines, and it reacted with liver tissue but not with other tissues. By immunoblot analysis, we found that this MoAb recognized a 190 kDa molecule on hepatocytes. The MoAb was able to kill hepatocyte-derived cell lines in the presence of fresh human serum. This cytotoxic effect was completely abrogated by heat inactivation of human serum prior to its addition to cell lines. In addition, an IgM autoantibody that recognized a 190 kDa molecule was also found in patients with AIH but not in those with chronic hepatitis C; its titer correlated significantly with serum alanine aminotransferase (ALT) levels in patients with AIH. In conclusion, we generated a human MoAb that recognizes a 190 kDa molecule on hepatocytes. Because of its ability to mediate complement-dependent cytotoxicity and the presence of similar IgM autoantibody in patients with AIH, we hypothesize this autoantibody may play a role in the immunopathogenesis of AIH.

Autoantibodies in the diagnosis and management of liver disease

Autoantibodies are nonpathogenic manifestations of immune reactivity, and they may occur in acute and chronic liver diseases. Autoantibodies may be consequences rather than causes of the liver injury, and they should be regarded as diagnostic clues rather than etiologic markers. Conventional autoantibodies used in the categorization of autoimmune liver disease are antinuclear antibodies, smooth muscle antibodies, antibodies to liver/kidney microsome type 1, antimitochondrial antibodies, and atypical perinuclear anti-neutrophil cytoplasmic antibodies. Ancillary autoantibodies that enhance diagnostic specificity, have prognostic connotation, or direct treatment are antibodies to endomysium, tissue transglutaminase, histones, doubled-stranded DNA, and actin. Autoantibodies that have an emerging diagnostic and prognostic significance are antibodies to soluble liver antigen/liver pancreas, asialoglycoprotein receptor, liver cytosol type 1, and nuclear pore complex antigens. Autoantibodies of uncertain clinical value that remain under investigation are antibodies to chromatin, lactoferrin, and Saccharomyces cervisiae. Continued recognition and characterization of autoantibodies should improve diagnostic precision, provide prognostic indices, and elucidate target autoantigens. These advances may in turn clarify pathogenic mechanisms, facilitate the development of animal models, and generate novel site-specific therapies.

Histological features associated with relapse after corticosteroid withdrawal in type 1 autoimmune hepatitis

Relapse of type 1 autoimmune hepatitis after drug withdrawal may relate to incomplete histological improvement during corticosteroid therapy and/or persistence of pathogenic mechanisms.

AIM

Determine the histological features prior to drug withdrawal that are associated with relapse in patients satisfying pre-established clinical, laboratory, and histological criteria for remission and relapsing after corticosteroid withdrawal.

METHODS

One hundred liver tissue samples obtained immediately prior to corticosteroid withdrawal from 88 patients who had previously satisfied criteria for histological remission were reviewed retrospectively.

RESULTS

Histological findings in the patients who relapsed were similar to those in the patients who sustained remission in regard to histological activity index (1.7 +/- 0.1 versus 1.6 +/- 0.2, P = 0.6), fibrosis score (2.6 +/- 0.3 versus 2.3 +/- 0.4, P = 0.5), and frequencies of interface hepatitis (36% versus 20%, P = 0.2), cirrhosis (21% versus 17%, P = 0.8), and normal or near normal tissue (9% versus 7%, P > 0.9). Only the presence of portal plasma cells was associated with relapse (31% versus 7%, P = 0.01). The positive predictability of portal plasma cell infiltration for relapse was 92%, but its sensitivity was only 31%.

CONCLUSIONS

Portal plasma cell infiltration is predictive of relapse after drug withdrawal in tissue specimens already satisfying criteria for remission. Portal plasma cell infiltration may be indicative of an active antibody-dependent pathogenic mechanism. Its low sensitivity for relapse indicates the need for other complementary predictors of outcome.

Autoimmune hepatitis: diagnostic criteria, subclassifications, and clinical features

The diagnosis of AIH depends on the finding of several suggestive features together with careful exclusion of liver diseases of other etiologies. Wherever possible, the diagnosis should be confirmed histologically by an experienced hepatopathologist. Seronegativity for the conventional autoantibodies at presentation does not exclude a diagnosis of AIH. It is important to test for anti-LKM1 antibodies to avoid missing a diagnosis of type 2 AIH, with potentially serious consequences. Although the syndrome is associated with characteristic biochemical abnormalities, and biochemical parameters are commonly used for monitoring response to therapy, it should be borne in mind that neither these nor autoantibody titers are completely reliable indices of disease activity. Although the various systems that have been promulgated for classification of the disease may identify different groups of patients on pathogenetic or clinical criteria and are useful for research purposes, none is yet sufficiently exclusive in terms of defining prognosis or planning treatment strategies to be applicable to the individual patient seen in the clinic. Clinical management should therefore continue to be individually tailored.

Autoantibodies and defined target autoantigens in autoimmune hepatitis: an overview

Autoimmune hepatitis (AIH) is a disease of unknown aetiology characterised by hypergammaglobulinaemia, non-organ and liver-related autoantibodies, association with HLA-DR3 or DR4 and a favourable response to immunosuppression. The current classification of AIH and the several autoantibodies/target autoantigens found in this disease are reported. The importance of these markers in the differential diagnosis and the study of pathogenesis of AIH is also given. AIH is subdivided into two major types: AIH type 1 (AIH-1) and AIH type 2 (AIH-2). AIH-1 is characterised by the detection of smooth muscle autoantibodies (SMA) and/or antinuclear antibodies (ANA). Antineutrophil cytoplasmic autoantibodies (ANCA), in most cases of perinuclear pattern (p-ANCA), by the indirect immunofluorescence assay, antibodies against the asialoglycoprotein receptor (anti-ASGP-R) and antibodies to soluble liver antigens or liver-pancreas (anti-SLA/LP) may be useful for the identification of individuals who are seronegative for ANA/SMA. AIH-2 is characterised by the presence of specific autoantibodies against liver and kidney microsomal antigens (anti-LKM type 1 or infrequently anti-LKM type 3) and/or autoantibodies against liver cytosol 1 antigen (anti-LC1). Anti-LKM-1 and anti-LKM-3 autoantibodies are also detected in some patients with chronic hepatitis C (HCV) and chronic hepatitis D (HDV). For these reasons, the distinction between AIH and chronic viral hepatitis is of particular importance. Cytochrome P450 2D6 (CYP2D6) is the major target autoantigen of anti-LKM-1 autoantibodies in both conditions (AIH-2 and HCV infection). Recent data have demonstrated the expression of CYP2D6 on the surface of hepatocytes, suggesting a pathogenetic role of anti-LKM-1 autoantibodies in liver injury. Family 1 of UDP-glycuronosyltransferases has been identified as the target autoantigen of anti-LKM-3. The molecular target of anti-SLA/LP autoantibodies has been identified recently as a 50 kDa protein with unknown structure and function. A liver-specific enzyme, the formiminotransferase cyclodeaminase, was identified as the target autoantigen of anti-LC1 autoantibodies. Anti-ASGP-R and anti-LC1 autoantibodies appear to correlate better with the severity of AIH and the response to treatment. The latter may suggest a pathogenic role of these autoantibodies in the hepatocellular damage in AIH. In general, however, autoantibodies should not be used to monitor treatment or to predict AIH activity or outcome. Finally, current knowledge concerning a specific form of AIH that may develop in some patients with a rare genetic syndrome, the autoimmune polyglandular syndrome type-1 (APS-1), is also discussed. Autoantibodies against liver microsomes (anti-LM) are the specific autoantibodies found in AIH as a disease component of APS-1. However, anti-LM autoantibodies have also been described in cases of dihydralazine-induced hepatitis. Cytochrome P450 1A2 has been identified as the target autoantigen of anti-LM autoantibodies in both disease entities.

Antibodies to soluble liver antigen/liver pancreas and HLA risk factors for type 1 autoimmune hepatitis

OBJECTIVE

Antibodies to soluble liver antigen/liver-pancreas are highly specific markers of type 1 autoimmune hepatitis that have been associated with relapse. Our aim was to determine if these antibodies are reflective of a genetic predisposition for recrudescent disease.

METHODS

One hundred forty-four white North American patients were evaluated by an enzyme immunoassay and by Western blot using recombinant soluble liver antigen/liver-pancreas; 122 were assessed for class II human leukocyte antigens (HLAs).

RESULTS

Twenty-two patients (15%) had antibodies to soluble liver antigen/liver-pancreas. These patients were indistinguishable from seronegative patients by clinical, laboratory, and histological features at presentation. Patients with antibodies to soluble liver antigen/liver pancreas had HLA DR3 (79% vs 50%, p = 0.02) more commonly and HLA DR4 less often (16% vs 47%, p = 0.02) than patients with smooth muscle antibodies and/or antinuclear antibodies. Seropositivity was associated with DRB1*0301 and seronegativity was associated with DRB1*0401. Relapse after drug withdrawal occurred in all patients with antibodies to soluble liver antigen/liver-pancreas and at a higher frequency than in patients with conventional antibodies (100% vs 78%, p = 0.05).

CONCLUSIONS

Antibodies to soluble liver antigen/liver pancreas are associated with HLA DR3 and the susceptibility allele, DRB1*0301. Antibodies to soluble liver antigen/liver-pancreas may be surrogate markers of a genetic propensity for recrudescent disease or the target autoantigen. They may be complementary to antinuclear antibodies and smooth muscle antibodies in diagnosis and management.

Current concepts in the diagnosis, pathogenesis, and treatment of autoimmune hepatitis

Autoimmune hepatitis has a global distribution and affects all ages. Genetic factors strongly influence susceptibility, clinical expression, and treatment response. The diagnosis of autoimmune hepatitis has been codified by an international panel. An acute or fulminant presentation is recognized but not a cholestatic form. Subclassifications by predominant autoantibody profile have been proposed, but they lack etiologic and prognostic differences. Autoantibodies continue to be characterized to improve diagnostic specificity, predict outcome, and identify pertinent antigenic targets. Cytosolic enzymes are prime candidates as autoantigens. DRB1*0301 and DRB1*0401 are the susceptibility alleles in Caucasoid Northern Europeans and North Americans, and they also affect clinical expression and treatment outcome. Other autoimmune promoters affecting cytokine production and immunocyte activation may act in synergy with the susceptibility alleles to affect disease behavior. Cell-mediated and antibody-dependent forms of cytotoxicity are probably interactive pathogenic mechanisms, and novel site-specific therapies are feasible because these mechanisms are defined. Potent new immunosuppressive agents are emerging from the transplantation arena, but prednisone alone or in combination with azathioprine remains the mainstay of treatment. Corticosteroid therapy is effective but not ideal.

Autoimmune liver disease. Current standards, future directions

The diagnosis and management of autoimmune hepatitis continues to evolve as new diagnostic tests and new therapies are added to the armamentarium. Also encouraging are the advances in the understanding of the human immune system and its involvement in the origin and course of auto immune diseases in general and in the variants of autoimmune liver disease. Promising changes are expected in the next few years as new medications become available to the practicing hepatologist. New immune tests may allow therapies to be customized to patients, and antiviral therapies may also eventually be used in the management of this autoimmune liver diseases.

Clinical significance of autoantibody to hepatocyte membrane antigen in type 1 autoimmune hepatitis

OBJECTIVE

By using HepG2 as flow cytometry target, we have reported that autoantibody to hepatocyte membrane antigen (anti-HMA) was frequently found in autoimmune hepatitis (AIH) patients. In this study, we have examined this autoantibody in relation to clinical features in these patients.

METHODS

HepG2 cells were incubated with diluted serum and subsequently with FITC-conjugated antihuman immunoglobulin. The results were expressed as relative fluorescence intensity. The prevalence of anti-HMA was estimated by setting the upper limit of mean +/- 3 SD obtained from healthy subjects.

RESULTS

We found that the mean relative fluorescence intensity was 1.67+/-0.5 in AIH with low serum ALT level (group 1 AIH), 4.20+/-1.9 in AIH with high serum ALT level (group 2 AIH), and 1.92+/-0.9 in age-matched chronic hepatitis C virus-positive patients. Their positive rate was 37.5% (three of eight) in group 1 AIH, 95.0% (19 of 20) in group 2 AIH, and 33.3% (four of 12) in chronic hepatitis C patients. In 12 group 2 AIH patients, their mean relative fluorescence intensity was significantly decreased during immunosuppressive therapy. The association between serum ALT level and anti-HMA was confirmed by the facts that a significant direct quantitative relationship existed between these two levels and by serial studies of anti-HMA in four AIH patients. Anti-HMA was also detected in five non-B, non-C hepatitis patients having clinical features resembling those of AIH.

CONCLUSIONS

The present results have shown that the anti-HMA was tightly associated with the degree of hepatocyte inflammation and that the measurement of anti-HMA may have some advantage in clinical evaluation of some of non-B, non-C hepatitis patients.

Isolation and characterization of cDNA encoding the antigenic protein of the human tRNP(Ser)Sec complex recognized by autoantibodies from patients withtype-1 autoimmune hepatitis

We previously described autoantibodies against a UGA serine tRNA-protein complex (tRNP(Ser)Sec) in patients with type-1 autoimmune hepatitis [1] and now define the specificity and frequency of this autoantibody and the DNA sequence encoding the tRNA(Ser)Sec-associated antigenic protein. The presence of anti-tRNP(Ser)Sec antibodies was highly specific for type-1 autoimmune hepatitis, as 47.5% of patients were positive compared with none of the control subjects. To characterize the antigenic protein(s), we immunoscreened a human cDNA library with anti-tRNP(Ser)Sec-positive sera. Two clones (19 and 13) were isolated. Clone 19 encodes a protein with a predicted molecular mass of 48.8 kD. Clone 13 is a shorter cDNA, almost identical to clone 19, which encodes a 35.9-kD protein. Expression of both cDNAs was accomplished in Escherichia coli as His-tagged recombinant proteins. Antibodies eluted from both purified recombinant proteins were able to immunoprecipitate the tRNA(Ser)Sec from a HeLa S3 cell extract, demonstrating their cross-reactivity with the mammalian antigenic complex. Recent cloning data relating to the target antigen(s) of autoantibodies in autoimmune hepatitis patients that react with a soluble liver antigen (SLA) and a liver-pancreas antigen (LP) have revealed that these two autoantibodies are identical and that the cloned antigen shows 99% amino acid sequence homology with tRNP(Ser)Sec.

Autoimmune hepatitis

Autoimmune hepatitis (AIH) is a rare disease, characterized by female predominance, hypergammaglobulinemia, autoantibodies, association with HLA DR3 and HLA DR4 and a good response to immunosuppression. Different subtypes of AIH may be distinguished, based on differences in the autoantibody patterns. AIH type 1 is characterized by anti-nuclear (ANA) and/or anti-smooth muscular (SMA) autoantibodies. AIH type 2 is characterized by liver/kidney microsomal autoantibodies (LKM). AIH type 3 may be distinguished by autoantibodies to soluble liver proteins (SLA) or the liver pancreas antigen (LP). AIH-2 affects predominantly pediatric patients and is characterized by a more severe clinical course, a higher frequency of relapse under immunosuppressive treatment and a more frequent progression to cirrhosis. In contrast, AIH types 1 and 3 show a higher age of onset and a better long-term response to immunosuppressive treatment. At present, the treatment of choice is prednisone alone or a combination with prednisone and azathioprine. Both treatment protocols show high survival rates. However, a rate of 13% of treatment failures and the failure to induce permanent remission in most patients underlines the urgent need to develop additional treatment regimens. A yet unknown genetic predisposition is believed to act as the underlying etiological factor in AIH. This genetic predisposition includes a few known risk factors such as the presence of HLA DR3 or HLA DR4, deletions of C4A alleles and female gender. Furthermore, it has to be postulated that defects in immunoregulatory genes exist. A model for such defects may be the autoimmune polyglandular syndrome type 1 (APS1), which results from the defects in a single gene, the autoimmune regulator type 1 (AIRE-1). Patients with APS1 suffer from mucocutaneous candidiasis and a number of organ-specific autoimmune diseases. Characteristic is a high variability in the number and character of the disease components in APS1, indicating that other genetic and environmental factors may strongly modulate the outcome of disease. Environmental factors may comprise chemical influences, such as nutritional compounds and drugs, or virus infections. Several drugs or chemicals were shown to induce hepatitis with autoimmune involvement, e.g. tienilic acid, dihydralazine and halothane. Adduct formation of an activated metabolite is believed to act as a trigger and to induce a specific immune response. Similarly, viruses were repeatedly shown to trigger autoimmune hepatitis. In virus infections, sequence similarities between viral and self-proteins may trigger autoimmune processes and the simultaneous presence of inflammatory cytokines during virus infection may further increase the risk of developing self-perpetuating autoimmune reactions which overshoot.

Behavior and significance of autoantibodies in type 1 autoimmune hepatitis

BACKGROUND/AIM

Smooth muscle antibodies and antinuclear antibodies characterize type 1 autoimmune hepatitis. Our aim was to correlate the appearance and disappearance of these autoantibodies with clinical and histological events.

METHODS

One hundred and seven patients were evaluated successively over 128+/-9 months. Autoantibodies were determined by indirect immunofluorescence during routine follow-up and at key clinical events.

RESULTS

Eighty-one patients (76%) lost one or both of the autoantibodies, and disappearance was associated with improved laboratory and histological features. Autoantibody status, however, was not highly predictive of laboratory (69%) or histological activity (72%). Patients who relapsed were seronegative at the time of drug withdrawal as commonly as patients who sustained remission (29% versus 25%). Only 27 patients (25%) lost their autoantibodies long term. Patients who eventually entered a sustained remission lost their autoantibodies more commonly than those who required retreatment (76% versus 43%, p=0.03). Disappearance of the autoantibodies, however, preceded sustained remission in only 38%. Serum titers at presentation did not distinguish patients with more severe disease or different treatment outcomes.

CONCLUSIONS

Smooth muscle antibodies and antinuclear antibodies commonly disappear and reappear. Their loss is associated with improved laboratory tests and biopsy findings, but disappearance does not predict treatment outcome. Autoantibody titer at presentation and autoantibody behavior during therapy are not accurate indices of disease severity or prognosis.

Study of antigenic sites on the asialoglycoprotein receptor recognized by autoantibodies

The aim of this study was to identify the epitopes recognized by antibodies to the asialoglycoprotein receptor, a specific hepatocyte protein, from sera of patients with autoimmune hepatitis. An ELISA test was used to detect anti-asialoglycoprotein receptor antibodies in the sera of patients with autoimmune hepatitis. Positive sera were tested against the same antigen by slot blot, by Western blot and by immunoprecipitation of the untreated protein and following treatment with beta-mercaptoethanol (beta-ME) and endoglycosidase F. The mature, unglycosylated and partially glycosylated forms of the asialoglycoprotein receptor synthesized by HepG2 cells were tested against positive patients' sera, as well as the in vitro translated unglycosylated form of the H1 subunit of the receptor. Sera from patients with autoimmune hepatitis recognized equally the native form, as well as the beta-ME-modified form, but less well the deglycosylated form of the human mature receptor. No reactivity was found when these sera were tested against the denatured human protein. In addition, neither the unglycosylated H1 subunit nor any of the HepG2-synthesized asialoglycoprotein receptor forms bound to the antibodies. Altogether, these results show that anti-asialoglycoprotein receptor antibodies in the sera of patients with autoimmune hepatitis are directed against conformational structures of the mature hetero-oligomeric form of the human liver protein and that at least some epitopes were located on the extracellular domain of the antigen.