Clinical significance of autoantibodies to soluble liver antigen in autoimmune hepatitis

EASL Clinical Practice Guidelines on the management of autoimmune hepatitis

Autoimmune hepatitis (AIH) is a chronic liver disease of unknown aetiology which may affect any patient irrespective of age, sex, and ethnicity. At baseline, the clinical spectrum of the disease varies largely from asymptomatic cases to acute liver failure with massive hepatocyte necrosis. The aim of these EASL guidelines is to provide updated guidance on the diagnosis and management of AIH both in adults and children. Updated guidance on the management of patients with variants and specific forms of AIH is also provided, as is detailed guidance on the management of AIH-associated cirrhosis, including surveillance for portal hypertension and hepatocellular carcinoma, as well as liver transplantation in decompensated cirrhosis.

Quo vadis autoimmune hepatitis? - Summary of the 5th international autoimmune hepatitis group research workshop 2024

Autoimmune hepatitis (AIH) is a rare chronic liver disease with an increasing incidence in many countries. Chronic autoimmune responses against the liver can cause hepatic and extrahepatic symptoms, decreased quality of life and reduced liver transplant-free survival if inadequately treated. Although standard treatment with corticosteroids and thiopurines improves the life expectancy of patients with AIH, remission rates and tolerability are generally overestimated and the development of alternative first-line and salvage therapies has been disappointingly slow compared to in rheumatological diseases or inflammatory bowel disease. Other gaps include the lack of disease-specific diagnostic markers for AIH. Similarly, the new entity of drug-induced autoimmune-like hepatitis underscores the need to re-evaluate previous diagnostic criteria. The International AIH Group (IAIHG) has initiated a series of research workshops over the last decade to promote the identification of research gaps and subsequently improve the pace of scientific progress by stimulating collaboration between expert centres. This review reports on the results of the 5th Research Workshop, held in Hannover, Germany in June 2024, and summarises the progress made since the 4th Workshop in 2022. Patient representatives from the European Reference Network (ERN) Rare Liver Youth Panel participated in the workshop. The specific objectives of this year's 5th Workshop were: (1) To further improve diagnostics. (2) Initiate clinical trials including knowledge transfer on drugs from extrahepatic immune-mediated diseases, including B cell-depleting CAR T cells. (3) Utilisation of multi-omics approaches to improve the understanding of disease pathogenesis. (4) Application of machine learning-based approaches established in oncology or transplantation medicine to improve diagnosis and outcome prediction in AIH.

Novel autoantibody targets identified in patients with autoimmune hepatitis (AIH) by PhIP-Seq reveals pathogenic insights

Background and Aims

Autoimmune hepatitis (AIH) is a severe disease characterized by elevated immunoglobin levels. However, the role of autoantibodies in the pathophysiology of AIH remains uncertain.

Methods

Phage Immunoprecipitation-Sequencing (PhIP-seq) was employed to identify autoantibodies in the serum of patients with AIH (n = 115), compared to patients with other liver diseases (metabolic associated steatotic liver disease (MASH) n = 178, primary biliary cholangitis (PBC), n = 26, or healthy controls, n = 94).

Results

Logistic regression using PhIP-seq enriched peptides as inputs yielded a classification AUC of 0.81, indicating the presence of a predictive humoral immune signature for AIH. Embedded within this signature were disease relevant targets, including SLA/LP, the target of a well-recognized autoantibody in AIH, disco interacting protein 2 homolog A (DIP2A), and the relaxin family peptide receptor 1 (RXFP1). The autoreactive fragment of DIP2A was a 9-amino acid stretch nearly identical to the U27 protein of human herpes virus 6 (HHV-6). Fine mapping of this epitope suggests the HHV-6 U27 sequence is preferentially enriched relative to the corresponding DIP2A sequence. Antibodies against RXFP1, a receptor involved in anti-fibrotic signaling, were also highly specific to AIH. The enriched peptides are within a motif adjacent to the receptor binding domain, required for signaling and serum from AIH patients positive for anti-RFXP1 antibody was able to significantly inhibit relaxin-2 singling. Depletion of IgG from anti-RXFP1 positive serum abrogated this effect.

Conclusions

These data provide evidence for a novel serological profile in AIH, including a possible functional role for anti-RXFP1, and antibodies that cross react with HHV6 U27 protein.

The frequency and clinical significance of antibodies to soluble liver antigen/liver pancreas in autoimmune hepatitis: a prospective single-center study

BACKGROUND AND AIMS

Soluble liver antigen/liver pancreas antibodies (anti-SLA/LP) are specific markers for autoimmune hepatitis (AIH) that have been associated with a distinct clinical phenotype and a more aggressive form of AIH. We prospectively evaluated the frequency and clinical significance of anti-SLA/LP in Turkish patients with AIH.

MATERIAL AND METHODS

We prospectively included patients diagnosed with AIH between January 2018 and May 2023. Autoantibodies were detected using by immunofluorescence and immunoblot.

RESULTS

We included 61 (80%, female) AIH patients with a median age of 31 years (15-78) at the time of diagnosis. Anti-SLA/LP was detected in 20% ( n  = 12) of the patients. Baseline characteristics, treatment responses and outcomes were similar among anti-SLA/LP-positive and anti-SLA/LP-negative AIH patients. Anti-SLA/LP-positive patients had significantly higher biochemical response rates after 4 weeks (100 vs. 67%, P  = 0.027), 3 months (100 vs. 39%, P  < 0.001), 6 months (100 vs. 69%, P  = 0.041) of therapy but not after 12 months (100 vs. 76%, P  = 0.103) and at the end of follow-up (100 vs. 91%, P  = 0.328). Relapse rates following treatment response were similar in patients with and without anti-SLA/LP (22 vs. 23%, P  = 0.956). Second-line therapies (tacrolimus and mycophenolate mofetil) were given to seven (11%) patients, all were anti-SLA/LP-negative. Two of these progressed into end-stage liver disease and both underwent liver transplantation.

CONCLUSION

Our study results suggest that anti-SLA/LP positivity does not entail clinically distinct or severe features in AIH. In our cohort, anti-SLA/LP-positive patients showed a quicker response to immunosuppressive therapy.

Autoimmune Hepatitis: Epidemiology, Subtypes, and Presentation

Autoimmune hepatitis (AIH) is a chronic immunologic disorder in which the immune system targets the liver. The disease has a genetic basis and this accounts for the epidemiologic variation observed in serologic testing and clinical presentation across different populations. The incidence of AIH increases with age into the 70s and seems to be increasing in prevalence. Most patients test positive for antinuclear antibody, ASMA, or anti-LKM but about 20% of patients do not have these serologic markers. At clinical presentation, patients may be asymptomatic, symptomatic, have acute liver failure, or decompensated cirrhosis.

Autoimmune liver disease and multiple sclerosis: state of the art and future perspectives

Clinical observations suggest that the prevalence of autoimmune diseases is changing over time. Both autoimmune liver diseases and multiple sclerosis have shown a significant increase in the last decades. Although the coexistence of autoimmune diseases within individuals and families is a common phenomenon, the extent to which liver disease and multiple sclerosis co-occur is not clear. Case reports and few studies have reported the possible coexistence of multiple sclerosis with thyroid diseases, inflammatory bowel disease, psoriasis, and rheumatoid arthritis. It is unknown whether there is a definite association between multiple sclerosis and autoimmune liver diseases. We reviewed the literature to summarize the available studies on the association between different autoimmune liver diseases (autoimmune hepatitis, primary biliary cholangitis, and primary sclerosing cholangitis) and treated or untreated multiple sclerosis.

Evaluation of immunoserological detection of anti-liver kidney microsomal, anti-soluble liver antigen and anti-mitochondrial antibodies

Autoantibodies are the diagnostic hallmark of autoimmune liver diseases. Indirect immunofluorescence (IFT) is the reference method for the detection of anti-mitochondrial antibodies (AMA) and anti-liver kidney microsomal type-1 (anti-LKM1) antibodies, and inhibition ELISA (iELISA) for anti-soluble liver antigen (anti-SLA) antibodies. Given the complexity of these techniques, commercial ELISAs have emerged as a practical alternative, but without head-to-head validations. This study evaluated the agreement between three commercial ELISAs and the reference techniques and the impact of polyreactive immunoglobulin G (pIgG), a recently described phenomenon in autoimmune hepatitis, on commercial ELISAs. Inter-rater reliability was assessed using Cohen-Kappa coefficient (κ). Forty-eight, 46, and 66 samples were analyzed for AMA, anti-LKM1, and anti-SLA, respectively. For AMA, one commercial assay showed high agreement (κ = 0.91 (0.78-1.00)) with the reference method, while the other two showed weak or moderate agreement. For anti-LKM1, only one commercial assay showed high agreement (κ = 0.86 (0.71-1.0)). For anti-SLA antibodies only moderate agreement was achieved (κ up to 0.71 (0.52-0.89)). There was a trend towards higher pIgG levels in false-positives in the commercial ELISAs. Patients with high suspicion of autoimmune liver diseases should be referred to reference laboratories with the capacity of performing gold standard methods if the initial ELISA-based screening was performed.

Diagnosis and management of autoimmune hepatitis

Autoimmune hepatitis is an inflammatory disease of the liver of unknown cause that may progress to liver cirrhosis and end stage liver failure if diagnosis is overlooked and treatment delayed. The clinical presentation is often that of acute hepatitis, sometimes very severe; less frequently, it can be insidious or completely asymptomatic. The disease can affect people of any age and is more common in women; its incidence and prevalence seem to be on the rise worldwide. An abnormal immune response targeting liver autoantigens and inducing persistent and self-perpetuating liver inflammation is the pathogenic mechanism of the disease. A specific set of autoantibodies, increased IgG concentrations, and histological demonstration of interface hepatitis and periportal necrosis are the diagnostic hallmarks of autoimmune hepatitis. Prompt response to treatment with corticosteroids and other immunomodulatory drugs is almost universal and supports the diagnosis. The aims of treatment are to induce and maintain long term remission of liver inflammation. Treatment can often even reverse liver fibrosis, thus preventing progression to advanced cirrhosis and its complications. Most patients need lifelong maintenance therapy, and repeated follow-up in experienced hands improves the quality of care and quality of life for affected patients.

HLA and Non-HLA gene polymorphisms in autoimmune hepatitis patients of North Indian adults

Autoimmune hepatitis (AIH) is a chronic and progressive disease of the liver. This is a multifactorial autoimmune disease with both environmental factors and genetic factors playing a role in its pathogenesis. Certain environmental agents like viruses, drugs, etc., can trigger the disease in a genetically susceptible individual. The present study was aimed to explore the distribution of human leukocyte antigen (HLA)-DRB1, Protein tyrosine phosphatase non-receptor type 22 (PTPN22) and Cytotoxic T-Lymphocyte-associated protein 4 (CTLA-4) polymorphisms in North Indian adult AIH patients and their associations with clinical and pathological characteristics associated with the disease. A total of 147 subjects with 47 cases and 100 healthy controls were enrolled. Diagnosis of AIH was made by Revised International Autoimmune Hepatitis Group scoring system. HLA-DRB1 Typing was done by Luminex-based reverse Sequence-Specific Oligonucleotide Probing (SSOP). Single nucleotide variant (SNV) genotyping for CTLA-4 and PTPN22 was done by simple probe-based SNP arrays. Results indicated SLA positive AIH patients are poor responders to therapy. A significant predispositional association of HLA-DRB1*03 was observed in AIH patients from the North Indian population (p= 0.0001, OR=4.83 (2.30-10.15). The frequency of the GG genotype of CTLA-4 CT 60 was significantly increased in AIH patients compared to controls. Multinomial analysis showed that CTLA-4 CT 60 is an independent predictor for cases.

The Role of Autoantibody Testing in Modern Personalized Medicine

Personalized medicine (PM) aims individualized approach to prevention, diagnosis, and treatment. Precision Medicine applies the paradigm of PM by defining groups of individuals with akin characteristics. Often the two terms have been used interchangeably. The quest for PM has been advancing for centuries as traditional nosology classification defines groups of clinical conditions with relatively similar prognoses and treatment options. However, any individual is characterized by a unique set of multiple characteristics and therefore the achievement of PM implies the determination of myriad demographic, epidemiological, clinical, laboratory, and imaging parameters. The accelerated identification of numerous biological variables associated with diverse health conditions contributes to the fulfillment of one of the pre-requisites for PM. The advent of multiplex analytical platforms contributes to the determination of thousands of biological parameters using minute amounts of serum or other biological matrixes. Finally, big data analysis and machine learning contribute to the processing and integration of the multiplexed data at the individual level, allowing for the personalized definition of susceptibility, diagnosis, prognosis, prevention, and treatment. Autoantibodies are traditional biomarkers for autoimmune diseases and can contribute to PM in many aspects, including identification of individuals at risk, early diagnosis, disease sub-phenotyping, definition of prognosis, and treatment, as well as monitoring disease activity. Herein we address how autoantibodies can promote PM in autoimmune diseases using the examples of systemic lupus erythematosus, antiphospholipid syndrome, rheumatoid arthritis, Sjögren syndrome, systemic sclerosis, idiopathic inflammatory myopathies, autoimmune hepatitis, primary biliary cholangitis, and autoimmune neurologic diseases.

B cells in autoimmune hepatitis: bystanders or central players?

B cells are central for the adaptive immune system to mount successful immune responses not only as antibody producers but also as regulators of cellular immunity. These multifaceted features are also reflected in autoimmunity where autoreactive B cells can fuel disease by production of cytotoxic autoantibodies, presentation of autoantigens to autoreactive T cells, and secretion of cytokines and chemokines that either promote detrimental immune activation or impair regulatory T and B cells. The role of B cells and autoantibodies in autoimmune hepatitis (AIH) have been controversially discussed, with typical autoantibodies and hypergammaglobulinemia indicating a key role, while strong HLA class II association suggests T cells as key players. In this review, we summarize current knowledge on B cells in AIH and how different B cell subpopulations may drive AIH progression beyond autoantibodies. We also discuss recent findings of B cell-directed therapies in AIH.

Antinuclear antibodies (ANA) as a criterion for classification and diagnosis of systemic autoimmune diseases

The classification and diagnosis of systemic autoimmune diseases are frequently based on a collection of criteria composed of clinical, laboratory, imaging, and pathology elements that are strongly associated with the respective disease. Autoantibodies are a distinctive hallmark and have a prominent position in the classification criteria of many autoimmune diseases. The indirect immunofluorescence assay on HEp-2 cells (HEp-2 IFA), historically known as the antinuclear antibody test, is a method capable of detecting a wide spectrum of autoantibodies. A positive HEp-2 IFA test is part of the classification criteria for systemic lupus erythematosus (SLE) and juvenile idiopathic arthritis (JIA), as well as the diagnostic criteria for autoimmune hepatitis (AIH) and primary biliary cholangitis (PBC). A positive HEp-2 IFA test can appear as different morphological patterns that are indicative of the most probable autoantibody specificities in the sample. Only some of the HEp-2 IFA patterns are associated with the specific autoantibodies relevant to SLE, JIA, AIH, and PBC, whereas some other patterns occur mainly in non-related conditions and even in apparently healthy individuals. This paper provides a critical review on the subject and proposes that the classification and diagnostic criteria for SLE, JIA, AIH, and PBC could be improved by a modification on the HEp-2 IFA (ANA) criterion in that the staining patterns accepted for each of these diseases should be restricted according to the respective relevant autoantibody specificities.

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Autoantibodies play a prominent role in the classification or diagnostic criteria of many autoimmune diseases.

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ANA test is part of the classification criteria for SLE and JIA, as well as the diagnostic criteria for AIH.

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Different HEp-2 IFA patterns indicate different autoantibodies and only some are associated with a specific disease.

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ANA classification/diagnostic criteria should reflect the HEp-2 IFA patterns associated to the relevant autoantibodies.

Evaluation of Validity and Efficiency of Diagnostic Criteria in Autoimmune Hepatitis in Children

BACKGROUND

Autoimmune hepatitis (AIH) is a progressive inflammatory liver disease with various clinical symptoms, but treatment and prevention of hepatic failure and cirrhosis is possible with early diagnosis. However, no specific test has been approved for the diagnosis of AIH. In 2008, the International Autoimmune Hepatitis Group (IAIHG) developed a simplified diagnostic scoring system that has been widely used in practice. Nevertheless, it cannot distinguish AIH from Primary Sclerosing Cholangitis (PSC) and consensus is lacking with respect to its validity, sensitivity, and applicability for children patients. The newer 2018 version also requires validation. The present study intends to evaluate the validity and efficiency of the IAIHG simplified scoring system and new scoring system in children with AIH.

METHODS

The present study is a non-interventional case-control study covering 152 patients with hepatic diseases (83 patients with AIH and 69 patients with Wilson disease (WD)). Titers of autoantibodies, IgG levels, hepatic histology, and absence of viral hepatitis were scored and calculated according to IAIHG diagnostic criteria. Statistics software package (SPSS) and draft receiver operating characteristic (ROC) curves was used to analyze data and determine value of diagnostic criteria.

RESULT

In our study, both scoring systems' accuracy was good in AIH diagnosis, although new score displays higher sensitivity and specificity, suggestive of greater accuracy and predictive strength.

CONCLUSION

Our study is the first validation study of the new scoring system in diagnosing AIH, and further studies require verifying this scoring system.

Clinical characteristics and HLA genotypes in Chinese patients with anti-SLA/LP-positive autoimmune hepatitis

Background

Anti-soluble liver antigen/liver pancreas (anti-SLA/LP) is a highly specific serological marker for the diagnosis of autoimmune hepatitis (AIH). The aim of the present study was to define the clinical characteristics and human leucocyte antigen (HLA) genotypes of Chinese patients with anti-SLA/LP positive AIH.

Methods

Ninety-one AIH patients who were anti-SLA/LP positive were enrolled in this case control study. Clinical information was obtained through reviewing patients’ clinical notes. High-resolution genotyping of HLA-A, B, C, DRB1, and DQB1 alleles was performed by sequence-based typing polymerase chain reaction on 62 of the 91 patients. Data from 500 healthy patients were used as baseline controls.

Results

Anti-SLA/LP-positive AIH patients were characterized as follows: adults (age 20–80 years), female (88%), and frequent anti-nuclear antibody positivity (91%). Genetically, compared with the controls, HLA-B*35:01 and C*08:01 were significantly more frequent in patients. The frequencies of HLA-B*08:01, B*40:02, DRB1*04:01, DRB1*04:05, DRB1*14:01, and DRB1*16:02 increased, and the frequency in DRB1*15:01 decreased in patients, but did not reach significance after Bonferroni’s correction. Patients with other autoimmune diseases had a higher DRB1*04:05 and DQB1*04:01 allele carrier frequency than those without. DRB1*04:05 and DQB1*04:01 alleles were found at increased frequency in patients with decompensated liver disease than those with compensated liver disease.

Conclusions

Chinese anti-SLA/LP-positive AIH patients have some distinct clinical characteristics than other populations reported in the literature. The presence of certain specific HLA alleles could potentially increase the risk of developing anti-SLA/LP-positive AIH or other autoimmune disease and decompensated liver disease in the Chinese population.

Antigen presentation, autoantibody production, and therapeutic targets in autoimmune liver disease

The liver is an important immunological organ that controls systemic tolerance. The liver harbors professional and unconventional antigen-presenting cells that are crucial for tolerance induction and maintenance. Orchestrating the immune response in homeostasis depends on a healthy and well-toned immunological liver microenvironment, which is maintained by the crosstalk of liver-resident antigen-presenting cells and intrahepatic and liver-infiltrating leukocytes. In response to pathogens or autoantigens, tolerance is disrupted by unknown mechanisms. Intrahepatic parenchymal and nonparenchymal cells exhibit unique antigen-presenting properties. The presentation of microbial and endogenous lipid-, metabolite- and peptide-derived antigens from the gut via conventional and nonconventional mechanisms can educate intrahepatic immune cells and elicit effector responses or tolerance. Perturbation of this balance results in autoimmune liver diseases, such as autoimmune hepatitis, primary biliary cholangitis, and primary sclerosing cholangitis. Although the exact etiologies of these autoimmune liver diseases are unknown, it is thought that the disruption of tolerance towards self-antigens and microbial metabolites and lipids, as well as alterations in bile acid composition, may result in changes in effector cell activation and polarization and may reduce or impair protective anti-inflammatory regulatory T and B cell responses. Additionally, the canonical and noncanonical transmission of antigens and antigen:MHC complexes via trogocytosis or extracellular vesicles between different (non) immune cells in the liver may play a role in the induction of hepatic inflammation and tolerance. Here, we summarize emerging aspects of antigen presentation, autoantibody production, and the application of novel therapeutic approaches in the characterization and treatment of autoimmune liver diseases.

Permanent immunosuppression in SLA/LP-positive autoimmune hepatitis is required although overall response and survival are similar

BACKGROUND AND AIMS

Antibodies against soluble liver antigen/liver pancreas (anti-SLA/LP) are highly specific for autoimmune hepatitis (AIH) and have been linked with a more severe clinical course of the disease, frequent relapses after treatment withdrawal and worse outcome. To address definitely the clinical significance of anti-SLA/LP, we investigated a large number of anti-SLA/LP-positive and -negative patients followed in three referral centres.

METHODS

Prospectively collected data from 89 anti-SLA/LP-positive AIH patients (29 from Hamburg-Germany, 20 from Bologna-Italy and 40 from Larissa-Greece) were analysed retrospectively. Age- and sex-matched anti-SLA/LP-negative patients served as disease controls (n = 230; 1:2.5 ratio).

RESULTS

In respect to baseline characteristics, anti-SLA/LP-positive patients were more frequently asymptomatic compared to anti-SLA/LP-negative (P < .05). However, anti-SLA/LP-positive patients did not differ from anti-SLA/LP-negative in terms of the overall response to treatment, disease progression and survival even though, they were less likely to achieve corticosteroid withdrawal (P < .05), needed longer treatment duration to achieve first complete response (P < .001) and relapsed more frequently after treatment withdrawal compared to anti-SLA/LP-negative patients (P = <.001).

CONCLUSIONS

We showed that anti-SLA/LP antibodies do not characterize a group of AIH patients with distinct features and cannot identify patients with a more severe form of the disease or worse survival. Most importantly, however, anti-SLA/LP-positive patients appear to require lifelong immunosuppression as they are less likely to achieve the cessation of corticosteroids and present higher relapse rates after treatment withdrawal. Therefore, close long-term monitoring should be advised in all anti-SLA/LP-positive patients after withdrawal of immunosuppressive treatment.

Stopping immunosuppressive treatment in autoimmune hepatitis (AIH): Is it justified (and in whom and when)?

BACKGROUND

Initial treatment of autoimmune hepatitis (AIH) with prednisolone ± azathioprine is based on randomised controlled trials. Many patients receive long-term immunosuppressive treatment to prevent disease relapse; this strategy has a weaker evidence base.

AIM

To consider whether immunosuppressive treatment (IST) withdrawal in AIH is justified and to develop a rationale for patient selection.

METHODS

We reviewed published papers between 1972 and 2018, which addressed the outcomes of IST withdrawal and/or complications of IST in AIH.

RESULTS

(1) AIH relapse rates after withdrawal of IST vary between 25% and 100%. There is heterogeneity in these studies regarding relapse definition, IST duration prior to withdrawal and criteria for biochemical and histological remission prior to withdrawal. (2) Factors associated with relapse following IST withdrawal include: (a) absence of an identifiable initial disease trigger, (b) presence of other autoimmune diseases, (c) longer time to biochemical remission and (d) elevated serum transaminases on treatment withdrawal. Reports of associations between relapse and age, IST duration and failure of histological remission have been inconsistent. (3) Continued IST reduces risk of AIH relapse over at least 5 years. However, there is no evidence that routine (as opposed to selective) long-term IST improves disease outcome. (4) Patients with AIH have an increased risk of extrahepatic cancer, notably non-melanoma skin cancer, to which long-term IST may contribute. Long-term corticosteroid therapy is associated with weight gain, low-trauma fractures, diabetes and possibly vascular disease.

CONCLUSIONS

While further studies are needed, evidence supports a strategy of IST withdrawal in some patients with AIH who have achieved remission.

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.

Animal models of autoimmune hepatitis

Many animal models for autoimmune hepatitis (AIH) have been described in the past. Most models had to deal with the relative immunosuppressive environment of the liver. Therefore, some models used a combination of several triggering factors often on a susceptible background to generate an aggressive immune response that targets the liver. In addition, in order to be able to track the immune response the models used specific model autoantigens as targets that are either not present or have not been identified as a natural autoantigen in AIH patients. Thereby the feasibility of such models is somewhat questionable. Although many historic approaches included challenges of experimental animals with liver homogenates it was only in the last decade that natural occurring liver autoantigens have been used in animal models. This article reflects on the requirements for breaking liver tolerance and on how an ideal experimental model for AIH would look like. In addition, it discusses historic as well as recent animal models in the context of feasibility of induction, similarity of the clinical outcome to human AIH, and gain of knowledge for possible future therapies.

Autoantibodies in Autoimmune Liver Disease-Clinical and Diagnostic Relevance

Testing for liver-related autoantibodies should be included in the workup of patients with hepatitis or cholestasis of unknown origin. Although most of these autoantibodies are not disease specific, their determination is a prerequisite to diagnose autoimmune hepatitis (AIH) and primary biliary cholangitis (PBC), and they are components of the diagnostic scoring system in these diseases. In primary sclerosing cholangitis (PSC), on the other hand, autoantibodies are frequently present but play a minor role in establishing the diagnosis. In PSC, however, data on antibodies suggest a link between disease pathogenesis and the intestinal microbiota. This review will focus on practical aspects of antibody testing in the three major autoimmune liver diseases AIH, PBC, and PSC.

Current and future perspectives in autoimmune hepatitis

Autoimmune hepatitis occurs in genetically susceptible individuals as a result of loss of immunological tolerance to hepatic autoantigens that can be precipitated by environmental triggers. The clinical manifestation is usually insidious but can be also acute with liver failure. The diagnosis is made on the basis of antibody positivity, elevated immunoglobulin G levels and interface hepatitis on liver histology. Induction of remission is achieved with high-dose steroids in the majority of cases, and maintenance of remission with azathioprine. Treatment withdrawal is achievable only in a small proportion of patients. Patients with acute liver failure unresponsive to steroids or those with end-stage liver failure or hepatocellular carcinoma may require liver transplantation. Variant forms of overlapping autoimmune hepatitis with either primary biliary cholangitis or sclerosing cholangitis are associated with worse outcomes. New insights into the pathophysiology of the disease may provide novel therapeutic targets and a more individualized approach to treatment of autoimmune hepatitis.

Autoantibodies in Autoimmune Hepatitis: Can Epitopes Tell Us about the Etiology of the Disease?

Autoimmune hepatitis (AIH), primary biliary cholangitis (PBC), and primary sclerosing cholangitis (PSC) are serious autoimmune liver diseases that are characterized by a progressive destruction of the liver parenchyma and/or the hepatic bile ducts and the development of chronic fibrosis. Left untreated autoimmune liver diseases are often life-threatening, and patients require a liver transplantation to survive. Thus, an early and reliable diagnosis is paramount for the initiation of a proper therapy with immunosuppressive and/or anticholelithic drugs. Besides the analysis of liver biopsies and serum markers indicating liver damage, the screening for specific autoantibodies is an indispensable tool for the diagnosis of autoimmune liver diseases. Such liver autoantigen-specific antibodies might be involved in the disease pathogenesis, and their epitope specificity may give some insight into the etiology of the disease. Here, we will mainly focus on the generation and specificity of autoantibodies in AIH patients. In addition, we will review data from animal models that aim toward a better understanding of the origins and pathogenicity of such autoantibodies.

Serology in autoimmune hepatitis: A clinical-practice approach

Serology is key to the diagnosis of autoimmune hepatitis (AIH). Clinicians need to be aware of which tests to request, how to interpret the laboratory reports, and be familiar with the laboratory methodology. If correctly tested, >95% of AIH patients show some serological reactivity. Indirect immunofluorescence on triple rodent tissue is recommended as first screening step, since it allows the detection of all liver-relevant autoantibodies, except for anti-soluble liver antigen (SLA) antibody, which needs to be detected by molecular based assays. The threshold of immunofluorescence positivity is a titer equal or exceeding 1/40, but for patients younger than 18years even lower titers are clinically significant. Anti-nuclear antibody (ANA) and/or anti-smooth muscle (SMA) antibody characterize type 1 AIH. ANA in AIH typically shows a homogeneous staining pattern on HEp2 cells, without any specific target antigen. Anti-SMA displays different staining patterns on indirect immunofluorescence: the vascular/glomerular (VG) and the vascular/glomerular/tubular (VGT) patterns are considered specific for AIH, whilst the V pattern can be found in a variety of diseases. Type 2 AIH, which is rare and affects mostly children/adolescents, is characterized by anti-liver kidney microsomal 1 and/or anti-liver cytosol 1 antibodies. The presence of anti-neutrophil cytoplasmic antibody (ANCA), particularly atypical p-ANCA (pANNA), points to the diagnosis of AIH, especially in absence of other autoantibodies. Since it is associated with sclerosing cholangitis and inflammatory bowel disease, these conditions have to be ruled out. The only antibody specific for AIH is anti-SLA, which is associated with a more severe disease course.

Diagnostic approach to autoimmune hepatitis

Autoimmune hepatitis (AIH) is a chronic inflammatory liver disease which, if left without treatment, can evolve into cirrhosis and possibly liver failure. The diagnosis of AIH is hampered by the lack of specific and reliable markers of the disease and a number of clinical, biochemical, immunological, histological and genetic factors should be considered to reach a confident diagnosis Areas covered: Clinical expression of AIH, histological features, serological and genetic profiles, differential diagnosis, overlap with other autoimmune liver diseases, assessed on the basis of personal experience and review of published literature in the last 10 years through a systematic Medline search (keywords: autoimmune hepatitis, diagnosis) Expert commentary: Notwithstanding numerous efforts to identify simple and reliable markers of the disease, the diagnosis of AIH is still based on the combination of histological, immunological and biochemical features and often can represent a real challenge for the hepatologist.

Auto immune hepatitis

To provide an update of the latest trends in epidemiology, clinical course, diagnostics, complications and treatment of auto immune hepatitis (AIH). A search of the MEDLINE database was performed using the search terms: “auto immune hepatitis”, “clinical presentation”, “symptoms”, “signs”, “diagnosis”, “auto antibodies”, “laboratory values”, “serology”, “histopathology”, “histology”, “genetics”, “HLA genes”, “non-HLA genes”, “environment”, “epidemiology”, “prevalence”, “incidence”, “demographics”, “complications”, “HCC”, “PBC”, “PSC”, “corticosteroid”, “therapy”, “treatment”, “alternative treatment”. English-language full-text articles and abstracts were considered. Articles included reviews, meta-analysis, prospective retrospective studies. No publication date restrictions were applied. AIH is an immune meditated progressive inflammatory liver disease that predominantly affects middle-aged females but may affect people of all ages. The clinical spectrum of AIH is wide, ranging from absent or mild symptoms to fulminant hepatic failure. The aetiology of AIH is still unknown, but is believed to occur as the consequence of an aberrant immune response towards an un-known trigger in a genetically susceptible host. In the absence of a gold standard, diagnosis is based on the combination of clinical, biochemical and histopathological criteria. Immunosuppressive treatment has been the cornerstone of treatment since the earliest description of the disease in 1950 by Waldenström. Such treatment is often successful at inducing remission and generally leads to normal life expectancy. Nevertheless, there remain significant areas of unmet aetiological a clinical needs including fundamental insight in disease pathogenesis, optimal therapy, duration of treatment and treatment alternatives in those patients unresponsive to standard treatment regimens.

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.

Autoimmune Hepatitis: Progress from Global Immunosuppression to Personalised Regulatory T Cell Therapy

Autoimmune hepatitis (AIH) is an immune mediated liver injury. The precise aetiology of AIH is still unknown but current evidence suggests both genetic and environmental factors are involved. Breakdown in peripheral self-tolerance, and impaired functions of FOXP3(+) regulatory T cell along with effector cell resistance to suppression at the tissue level seem to play an important role in AIH immunopathogenesis. AIH is predominantly a T lymphocytes driven disease but B lymphocytes are also involved in the immunopathology. Innate immune cells are crucial in the initial onset of disease and their response is followed by adaptive T (Th1, Th17, and cytotoxic T cells) and B cell responses evidenced by liver histology and peripheral blood serology. Standard treatment regimens involving steroid and immunosuppressive medications lead to global immune suppression requiring life-long therapy with many side effects. Biologic therapies have been attempted but duration of remission is short-lived. Future direction of diagnosis and treatment for AIH should be guided by "omics" and the immunology profile of the individual patient and clinicians should aim to deliver personalised medicine for their patients. Cell therapy such as infusion of autologous, antigen-specific, and liver-homing regulatory T cells to restore hepatic immune tolerance may soon be a potential future treatment for AIH patients.

Type 1 and type 2 autoimmune hepatitis in adults share the same clinical phenotype

BACKGROUND

Autoimmune hepatitis (AIH) is historically classified into type 1 and type 2 on the basis of the autoantibody profile, anti-nuclear and/or anti-smooth muscle antibodies being the serological markers of type 1 AIH, whereas anti-liver/kidney microsomal antibody type 1 and/or anti-liver cytosol antibody type 1 characterise type 2 AIH.

AIM

To evaluate whether such a distinction is justified on the basis of different expression of the disease in adults.

METHODS

Twenty-six adult patients with type 2 AIH and 52 age- and sex-matched patients with type 1 AIH, representative of the entire cohort of adults with type 1 AIH, were compared at onset and during follow-up.

RESULTS

At diagnosis, median age was 26 years (range 17-53), female sex 86%, acute presentation 43%, severe liver histology 54%, cirrhosis 14%, complete response to treatment 52%, progression of the disease 17%, and median disease duration 72 months (range 12-280). HLA-DRB1*0301 was present in 26%, HLA-DRB1*0401 in 23% and HLA-DRB1*0701 in 25%. Clinical presentation, biochemical parameters, severe liver histology, genetic profile, response rate and progression of the disease were identical between type 1 and type 2 AIH.

CONCLUSION

There is not enough clinical, biochemical, histological or genetic reason to subdivide adults with autoimmune hepatitis into type 1 and type 2 on the basis of the autoantibody profile, and the term 'autoimmune hepatitis' without qualification should be preferred.

Prognostic Implications of Antibodies to Soluble Liver Antigen in Autoimmune Hepatitis: A PRISMA-Compliant Meta-Analysis

Prognostic evaluation is important for the management of patients with autoimmune hepatitis (AIH). Although some autoantibodies have been associated with disease activity and outcomes, the implication of antibodies to soluble liver antigen (anti-SLA) remains controversial. To conduct a meta-analysis of observational studies which addressed differences in clinical characteristics by anti-SLA status in patients with AIH. Three databases PUBMED, EMBASE, and OVID were systemically searched up to January 2015 using the terms "soluble liver antigen" or "liver-pancreas antigen" and "autoimmune hepatitis" with restriction to English-language. Studies were included if at least 50 patients with objective diagnosis of AIH were enrolled, anti-SLA detection was performed for the patients, and prognostic outcomes and/or disease severity were reported. Two investigators independently reviewed retrieved literature and evaluated eligibility. Discrepancy was resolved by discussion and a third investigator. Quality of included studies was evaluated using Newcastle-Ottawa Quality Assessment Scale (NOS). Data were pooled using fixed-effect or random-effect models. Prognostic outcomes included death from hepatic failure or requirement for liver transplantation, and responses to immunosuppressive therapy regarding remission or relapse. Results were combined on the odds ratio (OR) or standardized mean difference (SMD) scales. Eight studies were enrolled in this study, involving a total of 1297 AIH patients among whom 195 with anti-SLA. Pooled serum AST levels tended to be lower in anti-SLA seropositive patients. The presence of anti-SLA conferred 3.1-fold increased risk of hepatic death in AIH patients. The remission rates were comparable between anti-SLA seropositive and seronegative AIH patients, while anti-SLA positivity was associated with nearly 2-fold increased risk of relapse after drug withdrawal. Human leukocyte antigen (HLA) allotype DR3 was positively associated with anti-SLA. Antibodies to SLA may be an indicator of increased risks of hepatic death and treatment relapse for AIH patients. Our findings suggest that the anti-SLA seropositive patients should be maintained indefinitely on individually adjusted medication to improve their prognosis.

Anti-SLA/LP alone or in combination with anti-Ro52 and fine specificity of anti-Ro52 antibodies in patients with autoimmune hepatitis

BACKGROUND & AIMS

Antibodies (Abs) to soluble liver antigen/liver pancreas (anti-SLA/LP) are considered markers of worse prognosis and outcome in patients with autoimmune hepatitis (AIH) although this assumption has recently been attributed to their frequent co-expression with Abs against Ro52 (anti-Ro52). To assess the clinical significance of anti-SLA/LP Abs alone or in combination with anti-Ro52 in AIH patients and determine the immunodominant Ro52 epitopes according to the anti-SLA/LP status.

METHODS

Twenty-three anti-SLA/LP-positive and 106 anti-SLA/LP-negative AIH patients were included. Anti-SLA/LP were determined by ELISA using recombinant antigen, and confirmed by immunoblot using cytosolic rat liver fraction or HuH-7 extract. Anti-Ro52 Abs were determined by ELISA using recombinant antigen. Epitope mapping was assessed by ELISA using overlapping peptides covering the whole Ro52 protein in 26 AIH patients and 12 patients with Sjögren's syndrome.

RESULTS

Anti-SLA/LP positivity was not associated with the clinical, laboratory or histological characteristics of AIH patients. Treatment response, corticosteroid withdrawal, relapse after stopping treatment and outcome, were not associated with the presence of anti-SLA/LP, anti-Ro52 or double reactivity. Moreover, Ro52 epitope mapping revealed new epitopes unique for AIH and independent from anti-SLA/LP positivity.

CONCLUSIONS

Neither anti-SLA/LP nor anti-Ro52 Abs or their combination could specify a distinct group of AIH patients in terms of clinical characteristics, treatment response and outcome. Further studies are needed to clarify whether the newly discovered immunodominant epitopes of Ro52 antigen which were associated specifically with AIH have any clinical or pathogenetic significance in AIH.

Medullary thymic epithelial cells and central tolerance in autoimmune hepatitis development: novel perspective from a new mouse model

Autoimmune hepatitis (AIH) is an immune-mediated disorder that affects the liver parenchyma. Diagnosis usually occurs at the later stages of the disease, complicating efforts towards understanding the causes of disease development. While animal models are useful for studying the etiology of autoimmune disorders, most of the existing animal models of AIH do not recapitulate the chronic course of the human condition. In addition, approaches to mimic AIH-associated liver inflammation have instead led to liver tolerance, consistent with the high tolerogenic capacity of the liver. Recently, we described a new mouse model that exhibited spontaneous and chronic liver inflammation that recapitulated the known histopathological and immunological parameters of AIH. The approach involved liver-extrinsic genetic engineering that interfered with the induction of T-cell tolerance in the thymus, the very process thought to inhibit AIH induction by liver-specific expression of exogenous antigens. The mutation led to depletion of specialized thymic epithelial cells that present self-antigens and eliminate autoreactive T-cells before they exit the thymus. Based on our findings, which are summarized below, we believe that this mouse model represents a relevant experimental tool towards elucidating the cellular and molecular aspects of AIH development and developing novel therapeutic strategies for treating this disease.

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.

Anti-phosphoenolpyruvate carboxykinase 2 antibody in patients with autoimmune hepatitis

AIM

To identify a novel autoantibody specific to autoimmune hepatitis (AIH) and to evaluate its clinical significance.

METHODS

Non-nuclear component protein extracted from normal human liver cell CyrohNHpes cultures that reacted with sera from AIH patients on a western blot was identified as an antigenic protein and subjected to N-terminal amino acid analysis to identify phosphoenolpyruvate carboxykinase 2 (PCK2). Enzyme-linked immunoassay (ELISA) for anti-PCK2 antibody was conducted on sera samples from patients with AIH (n = 42), primary biliary cirrhosis (PBC; n = 48), non-alcoholic steatohepatitis (NASH, n = 41), chronic hepatitis C (CHC, n = 20), drug-induced liver injury (DILI, n = 10), systemic lupus erythematosus (SLE, n = 16) and on sera samples from healthy volunteers (n = 30). Clinical findings were compared for AIH patients testing positive and negative for anti-PCK2 antibody.

RESULTS

ELISA findings showed that mean anti-PCK2 antibody titer in sera from AIH patients was significantly higher than in PBC, NASH, CHC, DILI and SLE patients, as well as in healthy volunteers. Anti-PCK2 antibody was present in 50.0% (21/42) of AIH, 14.6% (7/48) of PBC, 4.9% (2/41) of NASH, and 10.0% (2/20) of CHC patients, 0% (0/10) of DILI, 12.5% (2/16) of SLE and in 3.3% (1/30) of healthy volunteers. The sensitivity, specificity and accuracy of using the detection of anti-PCK2 antibody in diagnosing AIH were 50.0%, 91.5% and 83.1%, respectively. None of the AIH patients positive for anti-PCK2 antibody showed characteristic clinical features.

CONCLUSION

Although further investigations into the clinical usefulness are necessary, anti-PCK2 may have potential as a diagnostic marker for AIH.

Autoimmune hepatitis

Autoimmune hepatitis is a disease of the hepatic parenchyma that can present in acute or chronic forms. In common with many autoimmune diseases, autoimmune hepatitis is associated with non-organ-specific antibodies in the context of hepatic autoimmunity. This dichotomy has made definition of a unifying hypothesis in the pathophysiology of the disease difficult, although data from the past 8 years have drawn attention to the role of regulatory T cells. Several triggers have been identified, and the disease arises in genetically susceptible individuals. Clinical and biochemical remission is achievable in up to 85% of cases. For the remaining patients, alternative immunosuppression strategies are an option. Liver transplantation provides an excellent outcome for patients with acute liver failure or complications of end-stage liver disease, including hepatocellular carcinoma. Variant or overlapping syndromes are worthy of consideration when unexpected disease features arise.

Review article: autoimmune hepatitis -- current management and challenges

BACKGROUND

Autoimmune hepatitis (AIH) is a disease of unknown aetiology characterised by interface hepatitis, hypergammaglobulinaemia, circulating autoantibodies and a favourable response to immunosuppression.

AIM

To review recent advancements in understanding aetiopathogenesis, clinical, serological and histological features, diagnostic criteria and treatment strategies of AIH.

METHODS

Published studies on AIH extracted mainly from PubMed during the last 15 years.

RESULTS

Autoimmune hepatitis has a global distribution affecting any age, both sexes and all ethnic groups. Clinical manifestations are variable ranging from no symptoms to severe acute hepatitis and only seldom to fulminant hepatic failure. Autoimmune attack is perpetuated, possibly via molecular mimicry mechanisms, and favoured by the impaired control of regulatory T-cells. A typical laboratory finding is hypergammaglobulinaemia with selective elevation of IgG, although in 15-25% of patients - particularly children, elderly and acute cases - IgG levels are normal. Liver histology and autoantibodies, although not pathognomonic, still remain the hallmark for diagnosis. Immunosuppressive treatment is mandatory and life-saving; however, to meet strict response criteria, the conventional therapy with prednisolone with or without azathioprine is far from ideal.

CONCLUSIONS

Autoimmune hepatitis remains a major diagnostic and therapeutic challenge. The clinician, the hepato-pathologist and the laboratory personnel need to become more familiar with different expressions of the disease, interpretation of liver histology and autoimmune serology. According to the strict definition of treatment response issued by the 2010 AASLD guidelines, many patients are nonresponders to conventional treatment. Newer immunosuppressive agents targeting pathogenetic mechanisms can improve patient management, which needs to be tailored on a case-by-case basis.

Medullary thymic epithelial cell depletion leads to autoimmune hepatitis

TRAF6, an E3 ubiquitin protein ligase, plays a critical role in T cell tolerance by regulating medullary thymic epithelial cell (mTEC) development. mTECs regulate T cell tolerance by ectopically expressing self-antigens and eliminating autoreactive T cells in the thymus. Here we show that mice with mTEC depletion due to conditional deletion of Traf6 expression in murine thymic epithelial cells (Traf6ΔTEC mice) showed a surprisingly narrow spectrum of autoimmunity affecting the liver. The liver inflammation in Traf6ΔTEC mice exhibited all the histological and immunological characteristics of human autoimmune hepatitis (AIH). The role of T cells in AIH establishment was supported by intrahepatic T cell population changes and AIH development after transfer of liver T cells into immunodeficient mice. Despite a 50% reduction in natural Treg thymic output, peripheral tolerance in Traf6ΔTEC mice was normal, whereas compensatory T regulatory mechanisms were evident in the liver of these animals. These data indicate that mTECs exert a cell-autonomous role in central T cell tolerance and organ-specific autoimmunity, but play a redundant role in peripheral tolerance. These findings also demonstrate that Traf6ΔTEC mice are a relevant model with which to study the pathophysiology of AIH, as well as autoantigen-specific T cell responses and regulatory mechanisms underlying this disease.

[Review of overlap syndromes in autoimmune liver diseases. Diagnostic and therapeutic difficulties]

Overlap syndromes are biochemical, serological, histological and radiological overlaps across the classic autoimmune liver diseases in the presence of autoimmun hepatitis and primary biliary cirrhosis or primary sclerosing cholangitis. The exact prevalence of the disease is not known, but it may vary between 5% and 20%. Because it has no generally accepted diagnostic criteria, clinical signs, biochemical, serological, radiological and histological findings are evaluated together. Treatment depends on the predominant feature of the overlap syndrome; ursodeoxycholic acid and/or immunsuppressive (corticosteroid) treatment are used, based on observations from retrospective, non-randomized studies.

Structural mimicry between SLA/LP and Rickettsia surface antigens as a driver of autoimmune hepatitis: insights from an in silico study

BACKGROUND

Autoimmune hepatitis (AIH) is a chronic, progressive liver disease, characterized by continuing hepatocellular inflammation and necrosis. A subgroup of AIH patients presents specific autoantibodies to soluble liver antigen/liver-pancreas (SLA/LP) protein, which is regarded as a highly specific diagnostic marker. Autoantigenic SLA/LP peptides are targeted by CD4+ T cells, and restricted by the allele HLA-DRB1*03:01, which confers disease susceptibility in Europeans and Americans. A positively charged residue at position 71 has been indicated as critical for AIH susceptibility in all of the HLA alleles identified to date. Though the exact molecular mechanisms underlying pathogenesis of AIH are not clear, molecular mimicry between SLA/LP and viral/bacterial antigens has been invoked.

METHODS

The immunodominant region of SLA/LP was used as query in databank searches to identify statistically significant similarities with viral/bacterial peptides. Homology modeling and docking was used to investigate the potential interaction of HLA-DRB1*03:01 with the identified peptides. By molecular mechanics means, the interactions and energy of binding at the HLA binding site was also scrutinized.

RESULTS

A statistically significant structural similarity between the immunodominant regions of SLA/LP and a region of the surface antigen PS 120 from Rickettsia spp. has been detected. The interaction of the SLA/LP autoepitope and the corresponding Rickettsia sequence with the allele HLA-DRB1*03:01 has been simulated. The obtained results predict for both peptides a similar binding mode and affinity to HLA-DRB1*03:01. A "hot spot" of interaction between HLA-DRB1*03:01 and PS 120 is located at the P4 binding pocket, and is represented by a salt bridge involving Lys at position 71 of the HLA protein, and Glu 795 of PS120 peptide.

CONCLUSIONS

These findings strongly support the notion that a molecular mimicry mechanism can trigger AIH onset. CD4+ T cells recognizing peptides of SLA/LP could indeed cross-react with foreign Rickettsia spp. antigens. Finally, the same analysis suggests a molecular explanation for the importance of position 71 in conferring the susceptibility of the allele HLA-DRB1*03:01 to AIH. The lack of a positive charge at such position could prevent HLA alleles from binding the foreign peptides and triggering the molecular mimicry event.

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.

Antibodies to soluble liver antigen in patients with various liver diseases: a multicentre study

BACKGROUND

Antibodies to soluble liver antigen (anti-SLA) are specific serological markers of autoimmune hepatitis (AIH). The clinical significance and frequency of anti-SLA have never been reported among AIH patients from Italy and Turkey. To retrospectively assess the estimated prevalence, sensitivity, specificity and clinical significance of anti-SLA in AIH and various liver diseases.

METHODS

A total of 986 patients who had been tested for serum anti-SLA were included in study. The presence of anti-SLA was detected using recombinant enzyme linked immunosorbent assay and immuno-blot. The general characteristics and outcome of patients were obtained from their medical records.

RESULTS

Antibodies to SLA were found in 30 (3%) of 986 patients. Of these, 27 (90%) had AIH and its variants, whereas the remaining three (10%) had primary biliary cirrhosis. The prevalence of anti-SLA was 9% in AIH patients from Italy and 15% in patients from Turkey. The specificity of these antibodies was 99.5%, whereas sensitivity was 11%. The positive predictive and negative predictive values were 90% and 77.5% respectively (95% confidence interval). Biochemical remission was achieved in 90% of anti-SLA positive AIH patients, but relapse after immunosuppressive withdrawal or during maintenance therapy was observed in 53% of the patients.

CONCLUSIONS

Seropositivity for anti-SLA occurs at similar frequencies in AIH patients from different geographical regions and ethnic groups. The sensitivity of anti-SLA is low, but it has high specificity for AIH. Additional studies are necessary to prove clinical significance of anti-SLA in AIH.

Development of a recombinant cell-based indirect immunofluorescence assay for the determination of autoantibodies against soluble liver antigen in autoimmune hepatitis

Autoantibodies against soluble liver antigen (SLA) are specific markers for autoimmune hepatitis (AIH) type 1. In contrast to the determination of other AIH-associated autoantibodies by indirect immunofluorescence assay (IFA), detection of anti-SLA relied up to now on ELISA or immunoblot based on bacterially expressed recombinant protein. In order to develop a complementary IFA substrate, SLA isoform 1 was recombinantly produced in the human cell line HEK293 and controlled by a rabbit hyperimmune serum against SLA. The recombinant cells were used in IFA (RC-IFA) to analyze sera from 20 AIH patients with anti-SLA positivity predetermined by ELISA together with 80 controls (20 anti-SLA negative AIH, 15 primary biliary cirrhosis, 15 HCV, and 30 healthy blood donors). Using RC-IFA, anti-SLA was detected in all ELISA positive AIH sera but in none of the controls. Furthermore, a cytosolic fraction of HEK293 containing SLA was able to neutralize the autoantibodies in all positive sera in a dose-dependent manner. HEK293 cells expressing SLA are a valid substrate for the serodiagnosis of AIH relevant autoantibodies by IFA. In concert with cryosections of primate liver, rat kidney, rat liver, rat stomach, and HEp-2 cells, they enable the parallel determination of all autoantibodies associated with autoimmune liver diseases.

Review article: overlap syndromes and autoimmune liver disease

BACKGROUND

Autoimmune hepatitis (AIH), primary biliary cirrhosis (PBC) and primary sclerosing cholangitis (PSC) all nestle within the family of autoimmune liver diseases, whereby the result of immune-mediated liver injury gives rise to varied clinical presentations. Some patients demonstrate a phenotype whereby there is evidence of either PBC or PSC together with overlapping features of AIH. Due to an absence of well-validated diagnostic criteria and a lack of large therapeutic trials, treatment of overlap conditions is empiric and extrapolated from data derived from the primary autoimmune liver diseases.

AIMS

To review overlaps in the context of autoimmune liver diseases.

METHODS

General and specific review of published articles using PubMed, Medline and Ovid search engines, alongside pre-existing clinical management protocols, guidelines, and the authors' own knowledge of the published literature.

RESULTS

The challenges in diagnosis, clinical presentation, determining natural history and outcome of overlaps are presented, as well as present-day management suggestions, some based on evidence, others on consensus and opinion.

CONCLUSIONS

Overlapping autoimmune features, be they clinical, serological, histological or radiological are not infrequent, but appropriate diagnosis remains hindered by a lack of standardised diagnostic criteria. Optimum care for those with suspected overlap should thus focus on attention to detail over the fundamental aspects of timely secure diagnosis of the dominant disease entity. Clinicians should counsel patients carefully with regard to the risks and benefits of treatment, bearing in mind the paucity of randomised and controlled outcome data for medical interventions.

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.

Budesonide induces remission more effectively than prednisone in a controlled trial of patients with autoimmune hepatitis

BACKGROUND & AIMS

Autoimmune hepatitis (AIH) is a chronic liver disease associated with cirrhosis and liver failure. Corticosteroid therapy induces long-term remission but has many side effects. We compared the effects of budesonide (a steroid that is rapidly metabolized, with low systemic exposure) and prednisone, both in combination with azathioprine.

METHODS

We performed a 6-month, prospective, double-blind, randomized, active-controlled, multicenter, phase IIb trial of patients with AIH without evidence of cirrhosis who were given budesonide (3 mg, three times daily or twice daily) or prednisone (40 mg/d, tapered to 10 mg/d); patients also received azathioprine (1-2 mg/kg/d). Treatment was followed by a 6-month, open-label phase during which all patients received budesonide in addition to azathioprine. The primary end point was complete biochemical remission, defined as normal serum levels of aspartate aminotransferase and alanine aminotransferase, without predefined steroid-specific side effects, at 6 months.

RESULTS

The primary end point was achieved in 47/100 patients given budesonide (47.0%) and in 19/103 patients given prednisone (18.4%) (P < .001; 97.5% 1-side confidence interval [CI] = 16.2). At 6 months, complete biochemical remission occurred in 60% of the patients given budesonide versus 38.8% of those given prednisone (P = .001; CI: 7.7); 72.0% of those in the budesonide group did not develop steroid-specific side effects versus 46.6% in the prednisone group (P < .001; CI = 12.3). Among 87 patients who were initially given prednisone and then received budesonide after 6 months, steroid-specific side effects decreased from 44.8% to 26.4% at month 12 (P < .002).

CONCLUSIONS

Oral budesonide, in combination with azathioprine, induces and maintains remission in patients with noncirrhotic AIH, with a low rate of steroid-specific side effects.

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.