Liver-infiltrating T helper cells in autoimmune chronic active hepatitis stimulate the production of autoantibodies against the human asialoglycoprotein receptor in vitro

Unveiling the Role of GRK2: From Immune Regulation to Cancer Therapeutics

G protein-coupled receptors (GPCRs) represent humans' most prominent family of membrane proteins. In contrast, G protein-coupled receptor kinases (GRKs) play a pivotal role in the rapid desensitization of GPCRs. GRK2 is a particularly significant member of the GRK family. Recent studies have demonstrated that GRK2 primarily regulates immune cell function and homeostasis through receptor desensitization. Over the past decade, substantial progress has been made in elucidating the role of GRK2 in various human diseases. Notably, GRK2 is implicated in a range of autoimmune disorders, including rheumatoid arthritis (RA), inflammatory bowel disease (IBD), multiple sclerosis (MS), Sjögren's syndrome (SS), autoimmune myocarditis, hepatitis, and Graves' disease. Furthermore, emerging research has expanded our understanding of GRK2's involvement in cancer biology. Comprehensive investigations into the biological and pathological functions of GRK2 have facilitated the development of therapeutic strategies aimed at targeting the GRK2 signaling pathway in cancer, inflammation, and autoimmune diseases. Promising results have been observed with targeted biologics in preclinical and clinical trials. This review aims to elucidate the multifaceted role of GRK2 in immune function, autoimmune diseases, and cancer to uncover the remaining complexities associated with this kinase. A thorough understanding of GRK2 may position it as a potent therapeutic target in treating inflammation and cancer.

Autoimmune hepatitis: Towards a personalized treatment

Autoimmune hepatitis is an uncommon condition that affects both adults and children and is characterized by chronic and recurrent inflammatory activity in the liver. This inflammation is accompanied by elevated IgG and autoantibody levels. Historically, treatment consists of steroids with the addition of azathioprine, which results in remission in approximately 80% of patients. Despite significant advancements in our understanding of the immune system over the past two decades, few modifications have been made to treatment algorithms, which have remained largely unchanged since they were first proposed more than 40 years ago. This review summarized the various treatment options currently available as well as our experiences using them. Although steroids are the standard treatment for induction therapy, other medications may be considered. Cyclosporin A, a calcineurin inhibitor that decreases T cell activation, has proven effective for induction of remission, but its long-term side effects limit its appeal for maintenance. Tacrolimus, a drug belonging to the same family, has been used in patients with refractory diseases with fewer side effects. Sirolimus and everolimus have interesting effects on regulatory T cell populations and may become viable options in the future. Mycophenolate mofetil is not effective for induction but is a valid alternative for patients who are intolerant to azathioprine. B cell-depleting drugs, such as rituximab and belimumab, have been successfully used in refractory cases and are useful in both the short and long term. Other promising treatments include anti-tumor necrosis factors, Janus kinases inhibitors, and chimeric antigen receptor T cell therapy. This growing armamentarium allows us to imagine a more tailored approach to the treatment of autoimmune hepatitis in the near future.

Advances in Understanding and Managing Autoimmune Hepatitis: A Narrative Review

Autoimmune hepatitis (AIH) is a chronic liver disease characterized by immune-mediated destruction of hepatocytes, leading to inflammation and fibrosis. In recent years, significant advances have been made in understanding the pathogenesis, epidemiology, diagnosis, and treatment of AIH. This comprehensive narrative review aims to provide an up-to-date overview of these advances. The review begins by outlining the historical background of AIH, dating back to its initial recognition in the 1940s, and highlights the evolution of diagnostic criteria and classification based on autoantibody profiles. The epidemiology of AIH is explored, discussing its varying prevalence across different regions and the role of genetic predisposition, viral infections, and drug exposure as risk factors. Furthermore, the review delves into the pathogenesis of AIH, focusing on the dysregulated immune response, involvement of T cells, and potential contribution of the gut microbiome. Clinical presentation, diagnostic criteria, and liver biopsy as crucial tools for diagnosis are also discussed. Regarding management, the review provides an in-depth analysis of the standard first-line treatments involving glucocorticoids and azathioprine, as well as alternative therapies for non-responsive cases. Additionally, emerging second and third-line treatment options are examined. In conclusion, this narrative review highlights the complexity of AIH and underscores the importance of early diagnosis and individualized treatment approaches to improve patient outcomes. Further research and clinical trials are needed to optimize AIH management and ensure a better long-term prognosis for affected individuals.

Autoimmmune hepatitis

Autoimmune hepatitis (AIH) is a T-cell mediated, inflammatory liver disease affecting all ages and characterized by female preponderance, elevated serum transaminase and immunoglobulin G levels, positive circulating autoantibodies, and presence of interface hepatitis at liver histology. AIH type 1, affecting both adults and children, is defined by positive anti-nuclear and/or anti-smooth muscle antibodies, while type 2 AIH, affecting mostly children, is defined by positive anti-liver-kidney microsomal type 1 and/or anti-liver cytosol type 1 antibody. While the autoantigens of type 2 AIH are well defined, being the cytochrome P4502D6 (CYP2D6) and the formiminotransferase cyclodeaminase (FTCD), in type 1 AIH they remain to be identified. AIH-1 predisposition is conferred by possession of the MHC class II HLA DRB1*03 at all ages, while DRB1*04 predisposes to late onset disease; AIH-2 is associated with possession of DRB1*07 and DRB1*03. The majority of patients responds well to standard immunosuppressive treatment, based on steroid and azathioprine; second- and third-line drugs should be considered in case of intolerance or insufficient response. This review offers a comprehensive overview of pathophysiological and clinical aspects of AIH.

The Prevalence of Autoimmune Diseases in Patients with Primary Open-Angle Glaucoma Undergoing Ophthalmic Surgeries

PURPOSE

To assess the prevalence of autoimmune disease (AiD) in patients with primary open-angle glaucoma (POAG) undergoing ophthalmic surgery.

DESIGN

Retrospective, cross-sectional study.

PARTICIPANTS

Patients with POAG undergoing any ophthalmic surgery and control subjects undergoing cataract surgery at the Massachusetts Eye and Ear from March 2019 to April 2020.

METHODS

All available medical records with patient demographics, ocular, and medical conditions were reviewed. Differences in AiD prevalence were assessed and adjusted for covariates using multiple logistic regression. Additionally, a subgroup analysis comparing the POAG patients with and without AiD was performed.

MAIN OUTCOME MEASURES

To assess the prevalence of AiD based on the American Autoimmune Related Diseases Association list.

RESULTS

A total of 172 patients with POAG and 179 controls were included. The overall prevalence of AiD was 17.4% in the POAG group and 10.1% in the controls (P = 0.044); 6.4% of POAG patients and 3.4% of controls had more than 1 AiD (P = 0.18). The most prevalent AiDs in POAG group were rheumatoid arthritis (4.6%) and psoriasis (4.1%), which were also the most common in controls (2.8% each). In a fully adjusted multiple logistic regression analysis accounting for steroid use, having an AiD was associated with 2.62-fold increased odds of POAG relative to controls (95% confidence interval, 1.27-5.36, P = 0.009); other risk factors for POAG derived from the analysis included age (odds ratio [OR], 1.04, P = 0.006), diabetes mellitus (OR, 2.31, P = 0.008), and non-White ethnicity (OR, 4.75, P < 0.001). In a case-only analysis involving the eye with worse glaucoma, there was no statistical difference in visual field mean deviation or retinal nerve fiber layer (RNFL) thickness in POAG patients with AiD (n = 30) and without AiD (n = 142, P > 0.13, for both).

CONCLUSIONS

A higher prevalence of AiD was found in POAG patients compared with control patients undergoing ophthalmic surgery. The presence of AiD was associated with increased risk for POAG after adjusting for covariates. Additional factors may have prevented a difference in RNFL thickness in POAG patients with and without AiD. Autoimmunity should be explored further in the pathogenesis of POAG.

Understanding autoimmunity: The ion channel perspective

Ion channels are integral membrane proteins that orchestrate the passage of ions across the cell membrane and thus regulate various key physiological processes of the living system. The stringently regulated expression and function of these channels hold a pivotal role in the development and execution of various cellular functions. Malfunction of these channels results in debilitating diseases collectively termed channelopathies. In this review, we highlight the role of these proteins in the immune system with special emphasis on the development of autoimmunity. The role of ion channels in various autoimmune diseases is also listed out. This comprehensive review summarizes the ion channels that could be used as molecular targets in the development of new therapeutics against autoimmune disorders.

Autoantibodies to asialoglycoprotein receptor (ASGPR) in patients with autoimmune liver diseases

BACKGROUND

The liver asialoglycoprotein receptor (ASGPR) is the only organ-specific autoantigenic target in autoimmune hepatitis (AIH) patients and corresponding autoantibodies (Abs) have been suggested aiding in the serology of autoimmune liver diseases (ALD).

METHODS

A novel enzyme-linked immunosorbent assay (ELISA) employing purified rabbit ASGPR was used to detect ASGPR Abs in patients with ALD and controls. ASGPR Ab was determined in sera from 172 patients with AIH type 1, AIH type 2 (n=42), primary biliary cirrhosis (PBC) (n=113), cryptogenic liver disease (n=30), toxic liver disease (n=11), primary sclerosing cholangitis (PSC) (n=27), HCV infection (n=25), non-alcoholic steatohepatitis (n=43) and 100 blood donors. ASGPR Ab positivity was compared with AIH-related Abs (ANA, ASMA, Abs to LKM-1, LC-1, and SLA/LP) in patients with AIH.

RESULTS

Patients with AIH-1 and AIH-2 demonstrated an ASGPR Ab prevalence of 29.1% and 16.7%, respectively. ASGPR Ab positivity in patients with AIH-1 and AIH-2 was not significantly different to those in patients with PSC and HCV (p>0.05, respectively). ASGPR Ab levels in all study cohorts were significantly different with the highest medians in patients with AIH, PSC, and HCV infection (p<0.0001). ASGPR Ab can be found as only AIH-specific Ab determined by LIA and ELISA in 24.4% of AIH patients (48/197).

CONCLUSIONS

The novel ASGPR Ab ELISA is a specific diagnostic tool for ASGPR Ab detection in AIH. In addition to AIH, patients with PSC can demonstrate elevated ASGPR Ab amongst those with ALD suggesting a tolerance break to ASGPR in PSC.

Review article: chemokines as orchestrators of autoimmune hepatitis and potential therapeutic targets

BACKGROUND

Chemokines contribute to the pathogenesis of autoimmune hepatitis by directing the migration and positioning of inflammatory and immune cells within the liver.

AIM

Describe the liver-infiltrating effector cell populations in autoimmune hepatitis, indicate the chemokines that influence their migration, describe the role of chemokines in hepatic fibrosis and identify chemokine-directed treatment opportunities.

METHODS

Studies cited in Pub Med from 1972 to 2014 for autoimmune hepatitis, chemokines in liver disease, pathogenesis of autoimmune hepatitis and chemokine therapy were selected.

RESULTS

T helper type 17 lymphocytes expressing CXCR3 and CCR6 are attracted to the liver by the secretion of CXCL9, CXCL10 and CXCL11. These cells recruit pro-inflammatory T helper type 1 lymphocytes expressing CXCR3 and CCR5 by secreting CXCL10. Resident natural killer T cells expressing CXCR6 migrate in response to the local secretion of CXCL16, and they modulate the inflammatory response. T helper type 2 lymphocytes expressing CCR4 are attracted by CCL17 and CCL22, and they dampen the expansion of pro-inflammatory cells. Regulatory T cells expressing CXCR3 are attracted by the secretion of CXCL9, and they help dampen the pro-inflammatory responses. CCL2, CCL3, CCL5, CXCL4, CXCL10 and CXCL16 promote fibrosis by activating or attracting hepatic stellate cells, and CX3CL1 may prevent fibrosis by affecting the apoptosis of monocytes.

CONCLUSIONS

Chemokines are requisites for mobilising, directing and positioning the effector cells in immune-mediated liver disease. They are feasible therapeutic targets in autoimmune hepatitis, and the evaluation of monoclonal antibodies that neutralise the pro-inflammatory ligands or designer peptides that block receptor activity are investigational opportunities.

Juvenile autoimmune hepatitis: Spectrum of the disease

Juvenile autoimmune hepatitis (JAIH) is a progressive inflammatory liver disease, affecting mainly young girls, from infancy to late adolescence, characterized by active liver damage, as shown by high serum activity of aminotransferases, by elevated immunoglobulin G levels, high titers of serum non organ-specific and organ-specific autoantibodies, and by interface hepatitis on liver biopsy. It is a multifactorial disease of unknown etiology in which environmental factors act as a trigger in genetically predisposed individuals. Two types of JAIH are identified according to the autoantibody panel detected at diagnosis: AIH-1, characterized by the presence of anti-smooth muscle antibody and/or antinuclear antibody and AIH-2, by anti-liver-kidney microsomal antibody type 1 and/or by the presence of anti-liver cytosol type 1 antibody. Epidemiological distribution, genetic markers, clinical presentation and pattern of serum cytokines differentiate the two types of AIH suggesting possible pathogenetic mechanisms. The most effective therapy for AIH is pharmacological suppression of the immune response. Treatment should be started as soon as the diagnosis is made to avoid severe liver damage and progression of fibrosis. The aim of this review is to outline the most significant and peculiar features of JAIH, based largely on our own personal database and on a review of current literature.

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.

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.

Cutting edge issues in autoimmune hepatitis

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

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.

Autoimmune hepatitis

Autoimmune hepatitis (AIH) is an inflammatory liver disease that mainly affects females. It is characterized histologically by interface hepatitis, biochemically by increased aspartate and alanine aminotransferase levels, and serologically by the presence of autoantibodies and increased levels of immunoglobulin G. AIH affects both adults and children, and is particularly aggressive in the latter group. It is a relatively rare but devastating disease, which progresses rapidly unless immunosuppressive treatment is started promptly. With appropriate treatment 80% of patients achieve remission and long-term survival. Those patients who progress to end-stage liver disease because they are unresponsive or nonadherent to treatment, and those with fulminant liver failure (encephalopathy grade II-IV) at diagnosis, require liver transplantation. Seropositivity for smooth muscle and/or antinuclear antibodies defines type 1 AIH, while positivity for liver kidney microsomal type 1 antibodies defines type 2 AIH. The primary cause of AIH is unknown; however, considerable knowledge about the mechanisms of liver damage involved has been gathered over the past 30 years, which is likely to provide the basis for specific modes of treatment and a possible cure.

Complement mediated hepatocytes injury in a model of autoantibody induced hepatitis

Despite multiple reports on autoantibody-initiated complement activation in autoimmune hepatitis (AIH), how does the humoral immunity contribute to the pathogenesis of AIH remained unclear. In this report, by adoptively transferring a polyclonal rabbit anti-OVA antibody into Hep-OVA Tg mice in which OVA is selectively expressed on the surface of hepatocytes, we found that excessive complement activation initiated by the autoantibody overwhelmed the protection of intrinsic cell surface complement regulators, and induced hepatocytes injury both in vitro and in vivo. The anti-OVA antibody induced hepatic injury in Hep-OVA Tg but not WT C57BL/6 mice as assessed by serum ALT levels and liver histopathology. Immunohistochemical analyses showed that after the antibody administration, there was massive complement activation on anti-OVA IgG coated hepatocytes in Hep-OVA Tg mice, but not in WT mice. Consistent with these results, depleting complement by cobra venom factor (CVF) prior to antibody injections protected Hep-OVA Tg mice from anti-OVA IgG induced hepatic injury. In addition, treating Hep-OVA Tg mice with recombinant mouse decay accelerating factor, a native complement inhibitor, protected them from autoantibody induced hepatitis. These results suggest that complement could play a pivotal role in liver specific autoantibody mediated hepatocyte injury in AIH, and that complement inhibitors could be, in principle, developed as novel therapeutics against AIH.

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.

Aetiopathogenesis of autoimmune hepatitis

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

Autoimmune hepatitis

Autoimmune hepatitis (AIH) is an inflammatory liver disease affecting mainly females and characterised histologically by interface hepatitis, biochemically by elevated transaminase levels and serologically by the presence of autoantibodies and increased levels of immunoglobulin G. AIH responds to immunosuppressive treatment, which should be instituted as soon as diagnosis is made. Seropositivity for smooth muscle and/or anti-nuclear antibody defines type 1 AIH, while positivity for liver kidney microsomal type 1 antibody defines type 2 AIH. The aetiology of AIH is unknown, though both genetic and environmental factors are involved in its expression. Immune reactions against host liver antigens are believed to be the major mechanism of liver damage.

Aetiopathogenesis of autoimmune hepatitis

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

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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.

T cell immunity in autoimmune hepatitis

T cells play a central role in the immunopathogenesis of AIH. Until recently CD4+ T cells were thought to be critical for disease development, increasing evidence has shown that CD8+ T and gammadelta T cells also play a significant role. The predisposition of certain HLA genotypes to AIH as well as the clonal expansion of a limited number of T cell receptors suggests that the presentation of a self-antigen or a molecular mimic may be responsible for the initiation of the immune response. Given the association of AIH with viral hepatitis, it is thought that the loss of tolerance begins with an infection of hepatocytes and subsequent cytolysis by CD8+ T cells. The presentation of self-antigens or molecular mimics leads to activation and clonal expansion of T cells; this process may be increased by impaired regulatory T cells and a defect in apoptosis. Ultimately T cells initiate B cell production of autoantibodies, proinflammatory cytokines and finally hepatocyte cytotoxicity.

Mechanisms of autoimmune hepatitis

Autoimmune hepatitis (AIH) is a progressive inflammatory liver disease with a female preponderance, responsive to immunosuppressive treatment. Two types of AIH are described: type 1 AIH is characterized by positivity for smooth muscle and/or antinuclear antibody, while type 2 AIH is positive for liver kidney microsomal type 1 antibody. The putative mechanisms leading to the development of this condition include genetic predisposition to autoimmunity through possession of specific human leukocyte antigen alleles, immune reactions to liver cell antigens, possibly triggered by a mechanism of molecular mimicry, where immune responses to external pathogens, e.g. viruses, become directed toward structurally similar self-components, and an impairment in immune regulation. AIH has been described to arise de novo after liver transplantation. The mechanisms leading to post-transplant autoimmunity remain to be defined.

Autoimmune hepatitis

Autoimmune hepatitis is the archetype of liver autoimmune disease. It is divided into two types, according to the autoantibody profile. It should be suspected and diagnosed early since treatment is highly effective in preventing liver failure and transplant. The possible pathogenic scenario is described in the present review.

Pathogenesis of autoimmune hepatitis

Autoimmune hepatitis is initiated by CD4 T cells that recognize self-antigen. The effector cells differentiate into functional phenotypes according to cytokines in the microenvironment and the nature of the triggering antigen. Hepatocytes can express class II molecules and present antigenic peptides through a bystander mechanism. NKT cells reside in the normal liver but may be involved in liver cell damage possibly through the expression of Fas ligand. Autoantibodies may also participate in the process by complexing with antigen on the hepatocyte membrane surface and by interacting with mononuclear cells with Fc receptors. Molecular mimicry generates cross-reactivities that predispose the immune system to cross-react with self-antigens. Multiple exposures to pathogens with antigenic similarities may prime a cross-reactive subset of T cells in the genetically predisposed host. Autoimmunity against one self-antigen may then spread through molecular mimicry to other homologous self-antigens and may lead to overt autoimmune disease. Anatomically distant tissues may also become involved as autoreactive T cells that had been activated in one organ expand and infiltrate other organs that express similar epitopes.

Successful tacrolimus therapy for a severe recurrence of type 1 autoimmune hepatitis in a liver graft recipient

A 34-year-old woman underwent orthotopic liver transplantation (OLT) for decompensated type 1 autoimmune hepatitis (AIH). She was administered standard triple-drug immunosuppressive therapy (cyclosporine, steroids, and azathioprine). Ten years after OLT, she developed a recurrence of AIH, with emergence of serological markers of autoimmunity (high anti--smooth muscle antibody [ASMA] titer, high serum gamma globulin level), abnormal liver function test results, and characteristic histological features on liver biopsy. Despite intensified steroid therapy, her clinical and liver function deteriorated. The onset of cutaneous alternariosis led to a steroid dose reduction and cyclosporine replacement by tacrolimus. Clear-cut amelioration was observed, with an improvement in liver function test results and reduction in ASMA titer. One year after the recurrence of AIH, the patient has normal liver function and physical findings. Tacrolimus therefore may be effective in patients with severe recurrent autoimmune liver disease. Further studies are needed to assess tacrolimus therapy in patients who fail to respond to standard immunosuppressive therapy.

The lymphoid liver: considerations on pathways to autoimmune injury

Immunologic injury in the liver involves immigrant T and B lymphocytes and a resident lymphoid population that comprises distinct lymphocytic cells and accessory cells. The forerunner to autoimmunity is breaching of natural self-tolerance and hence the disruption of a fundamental property of the immune system. Such breaching occurs by processes that include inflammatory activation of immunocytes and macrophages, spillage of intracellular constituents, and epitope mimicry by constituents of microorganisms, with these acting on a genetically conditional phenotype; compounding factors include aberrations of apoptosis, whether insufficient or excess. The downstream end requires specifically directed inflammatory leukocyte traffic as an essential component of autoimmune expressions in the liver. The culmination is an orchestrated attack on hepatocytes or biliary epithelial cells by multiple effector pathways. Progress in type 1 autoimmune hepatitis still requires knowledge of a disease-specific autoantigen(s) involved in T-cell reactivity, although such knowledge in type 2 autoimmune hepatitis, in which the known autoantigen is cytochrome P4502D6, has not yet been integrated into a clearly defined scheme of pathogenesis. For PBC there has been a very promising amalgamation of molecular knowledge of the mitochondrial autoantigens. Future insights require deeper analysis of molecular, genetic, macroenvironmental, and microenvironmental elements in predisposition.

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.

Clinical significance of autoantibodies to soluble liver antigen in autoimmune hepatitis

BACKGROUND/AIMS

Classification of autoimmune hepatitis (AIH) into different subgroups according to autoantibody status has been proposed: type I (ANA/SMA), type II (LKM-1) and type III (anti-SLA). However, whether type III AIH forms a clinically distinct disease entity remains controversial. The aim of this study was to evaluate the subclassification of AIH into ANA/SMA and anti-SLA positive patients with regard to clinical, biochemical and histologic differences.

METHODS

Ninety-seven consecutive patients with a well-documented long-term course of AIH with ANA/SMA and/or anti-SLA autoantibodies were studied. Clinical, biochemical and histological features of patients with ANA/SMA and/or anti-SLA autoantibodies were compared in a secondary analysis of data acquired prospectively.

RESULTS

Anti-SLA autoantibodies were found in 21.6% of patients. Anti-SLA-positive patients tended to have lower transaminases (mean: 153 vs. 247 IU/l), gamma-globulins (25 vs. 31%) and bilirubin (1.8 vs. 3.3 mg/dl) in comparison to ANA/SMA positive patients, but there was a large overlap. HLA-type A1 B8 was more frequent in anti-SLA positive patients, while there was no difference in HLA DR3 and DR4 allotype. Response to immunosuppressive therapy was excellent, but relapse occurred frequently. Diagnosis of anti-SLA positive AIH was often delayed (mean: 68 months from first elevation of transaminases) since testing for anti-SLA autoantibodies is currently not generally available.

CONCLUSIONS

ANA/SMA and anti-SLA positive patients share most clinical, biochemical, histologic and prognostic features. Distinction between type I and type III AIH is therefore clinically not helpful. However, testing for anti-SLA autoantibodies helps in the diagnosis of AIH in many patients who may otherwise be misdiagnosed.

Pathogenesis of autoimmune hepatitis

Autoimmune hepatitis (AIH) is an idiopathic disorder affecting the hepatic parenchyma. There are no morphological features that are pathognomonic of the condition but the characteristic histological picture is that of an interface hepatitis without other changes that are more typical of other liver diseases. It is associated with hypergammaglobulinaemia, high titres of a wide range of circulating auto-antibodies, often a family history of other disorders that are thought to have an autoimmune basis, and a striking response to immunosuppressive therapy. The pathogenetic mechanisms are not yet fully understood but there is now considerable circumstantial evidence suggesting that: (a) there is an underlying genetic predisposition to the disease; (b) this may relate to several defects in immunological control of autoreactivity, with consequent loss of self-tolerance to liver auto-antigens; (c) it is likely that an initiating factor, such as a hepatotropic viral infection or an idiosyncratic reaction to a drug or other hepatotoxin, is required to induce the disease in susceptible individuals; and, (d) the final effector mechanism of tissue damage probably involves auto-antibodies reacting with liver-specific antigens expressed on hepatocyte surfaces, rather than direct T-cell cytotoxicity against hepatocytes.

Limited T cell receptor Vbeta-chain repertoire of liver-infiltrating T cells in autoimmune hepatitis

BACKGROUND/AIMS

To characterize the cellular immune reactions in autoimmune hepatitis, the T cell receptor repertoire of liver-infiltrating and circulating T cells was studied.

METHODS

Nucleic acids of liver-tissue and peripheral blood-derived T cells from 12 patients with untreated autoimmune hepatitis, four patients with chronic hepatitis C and three patients with toxic liver injury were extracted and analysed using a semiquantitative RT-PCR with a panel of T cell receptor Vbeta family specific primers. After agarose gel electrophoresis, the distribution of T cell receptor (TCR) Vbeta molecules was assessed by densitometry. Furthermore, results were compared to the TCR Vbeta distribution of 10 healthy blood donors.

RESULTS

Four of 12 patients with untreated autoimmune hepatitis but no patients with chronic hepatitis C and toxic liver injury showed a significant overexpression of TCR Vbeta3 (17.8% +/- 2.6% vs. 9.3% +/- 4.6%; p = 0.01) and three an overexpression of Vbeta13.1 (14.6% +/- 2.3% vs. 6.6% +/- 3.5%; p = 0.02) molecules compared to the TCR Vbeta-distribution in healthy blood donors. In addition, Vbeta3+ T cells were found enriched in the liver tissue compared to autologous peripheral blood in three autoimmune hepatitis patients (15.3% +/- 7.0% vs. 5.2% +/- 3.1%; L/B ratio: 2.9), while Vbeta13.1+ T cells were enriched in the liver tissue from one of three patients with overexpression.

CONCLUSIONS

In autoimmune hepatitis a disease specific compartmentalisation of TCR Vbeta3+ T cells was observed in the liver tissues. Although their specificity was unknown, this might indicate that these infiltrating T cells could have relevance for abnormal immunoregulation.

Is melatonin associated with the development of autoimmune hepatitis?

Melatonin is a neurohormone produced by the human pineal gland that plays a role in the regulation of many physiologic processes and has been proposed as a therapy for everything from insomnia to metastatic carcinoma. Melatonin is available in the United States without prescription, and adverse effects appear to be uncommon. However, because melatonin appears to have immunomodulatory properties, the potential exists for the development of autoimmune-related side effects. We describe a patient in whom characteristic clinical and laboratory features of autoimmune hepatitis developed after beginning melatonin therapy for the treatment of insomnia. Liver biopsy demonstrated histologic features of autoimmune hepatitis. Rapid symptomatic and biochemical improvement resulted from the initiation of immunosuppressive therapy; however, hepatitis recurred after the withdrawal of steroid therapy. The temporal relation observed between melatonin use and the development of autoimmune hepatitis raises the possibility that the drug might be involved in the pathogenesis of this patient's autoimmune disease.

Autoimmune hepatitis. Definition--classification--histopathology--immunopathogenesis

Autoimmune hepatitis (AIH) is a distinct form of acute and chronic inflammatory liver disease in which immune reactions against host antigens are found to be the major pathological mechanism. If left untreated it carries an unfavourable prognosis, and the diagnosis should be made as soon as possible. The diagnostic approach has been greatly facilitated by the establishment of a panel of marker autoantibodies, which do not define distinct therapeutic groups of AIH, but do allow a subgrouping based on differences in patient populations, some clinical features and prognosis. The characterization of organ-specific components of the liver cell surface as targets of cellular and humoral autoimmune reactions give new insights into the pathogenesis of the disease, even though the primary event triggering the disease remains to be defined. The most important disease-promoting factor seems to be a genetically determined background for autoimmunity. Without this different environmental factors, including viruses, toxins, cytokines and drugs, are only able to induce transient autoimmune phenomena and not autoimmune disease. The histopathology of AIH is in keeping with the present pathogenetic concept. Although there is no pathognomonic feature distinguishing this type of hepatitis from virus-induced forms, some distinct morphological lesions are regarded as characteristic. Clinical research on AIH has benefited greatly from observations of experimental AIH in mice. Recognition of the critical role of autoreactive T-lymphocytes in the pathogenesis and the observation of spontaneous recovery from AIH in the animal model associated with antigen-specific and antigen-non-specific T-cell suppression have made basic contributions to our improved understanding of the natural course of AIH in humans.

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

Antibodies to asialoglycoprotein receptor have diagnostic specificity for autoimmune hepatitis, but it is uncertain if they are complementary or redundant markers of the disease. Our aims were to assess their frequency and significance in type 1 autoimmune hepatitis and determine their contribution to the evaluation of these patients. Sera from 54 well-characterized patients were evaluated for antibodies to asialoglycoprotein receptor by a radioimmunofiltration assay based on rabbit-derived protein. Forty-four patients (82%) were seropositive. Seropositive patients were distinguished from seronegative counterparts by having higher serum gamma globulin (3.7 +/- 0.2 g/dl vs 2.3 +/- 0.3 g/dl, P = 0.0007) and immunoglobulin G levels (3707 +/- 179 mg/dl vs 2203 +/- 263 mg/dl, P = 0.0005) at presentation and a greater frequency of relapse after drug withdrawal (88% vs 33%, P = 0.01). Seropositivity for smooth muscle and/or antinuclear antibodies did not define treatment outcomes and antinuclear antibodies occurred less frequently than the other markers. Concurrent testing for antibodies to asialoglycoprotein receptor and smooth muscle identified all patients. We conclude that antibodies to asialoglycoprotein receptor are common in type 1 autoimmune hepatitis and they identify patients with a high frequency of relapse after corticosteroid withdrawal. Concurrent testing for these antibodies and smooth muscle antibodies has the same diagnostic sensitivity as testing for antinuclear and smooth muscle antibodies but a greater prognostic implication.

Autoimmune hepatitis versus viral hepatitis C

Numerous viruses are capable of inducing the syndrome of chronic hepatitis. Among them are the hepatitis B, C and D viruses. Out of the most common agents of chronic hepatitis, the hepatitis C virus has been found to be strikingly associated with autoimmune diseases and serological markers of autoimmunity. Conversely, the syndrome of genuine autoimmune hepatitis lacks evidence of previous or ongoing virus infection and is diagnosed by additionally excluding metabolic, toxic, and genetic causes of chronic hepatitis, and by the response to immunosuppressive treatment. This review article summarizes the current knowledge of hepatotropic virus-induced autoimmunity. It focuses on the present molecular and immunological definitions, the clinical and molecular distinction between autoimmune hepatitis and chronic viral hepatitis and the implications for the safe and efficacious therapy of these disease entities.

Autoimmune hepatitis following hepatitis A virus infection

A 7-year-old patient is reported who suffered from fatigue and jaundice due to chronic hepatitis. He had acquired hepatitis A virus infection in his community and communicated the disease to his German family 4 weeks later. While the other family members recovered from acute viral hepatitis A, the patient presented 10 weeks after the onset of hyperbilirubinemia (12 mg/dl) with the histology of chronic hepatitis, absence of markers for viral persistence, presence of autoantibodies against smooth muscle (1:320) and the asialoglycoprotein receptor (1:600), and marked hypergammaglobulinemia (3700 mg/dl), leading to the diagnosis of autoimmune hepatitis. The patient received immunosuppressive therapy, symptoms of liver disease disappeared, and autoantibodies cleared from circulation. The case is discussed in the context of a putative virus-induced autoimmune hepatitis in childhood. Autoimmune hepatitis may be induced by an external trigger. Hepatitis A virus infection is one of probably several triggers that may induce autoimmune hepatitis in predisposed individuals.

Mitochondrial antigens, molecular mimicry and autoimmune disease

The immune system is normally tolerant to mitochondrial self-antigens, but responsive against bacteria. Low-titre anti-mitochondrial antibodies (AMA) might be involved in this discrimination. Tolerance is broken in diseases characterised by high titre AMA. Some of these AMA, against cardiolipin, cross-react with DNA. The best studied AMA are those characterising primary biliary cirrhosis (PBC). These are directed against E2 subunits of the oxo-acid dehydrogenase complexes, and also against subunits E1 alpha, E1 beta and X of the pyruvate dehydrogenase complex. AMA of PBC patients also react with bacterial E2s. Reactivities are primarily peptide-specific but with cross-reactivity between mitochondrial and microbial antigens and between E2s of respective complexes. Immunodominant epitopes, for anti E2 AMA, include the conserved sequence flanking the site of lipoyl attachment. It is proposed that the initial stimulus for antibody production is chronic urinary tract infection. AMA themselves are not pathogenic, but CD4+ T-cells would be primed, recognising the lipoyl domain epitope in association with class II HLA. Inappropriate expression of class II antigens on bile duct epithelia, (as found in PBC), might lead to presentation of a particular fragment of HLA-DR alpha, known to be a major MHC presented self-peptide in the mouse. That sequence strongly mimics the lipoyl domain and might be recognised by primed T-cells, initiating the autoimmune cascade. In the mouse, a peptide of ND1 of Complex I is presented in association with class I MHC. Cells exhibiting somatic mutation of such a peptide might thus be subject to attack by CD8+ T-cells. If such peptides were presented by class II HLA, autoimmune diseases might arise, related to mimicry between such peptides and microbial sequences and/or self-antigens. These considerations might apply in Leber's disease and in age-related pathology.

Analysis of the in vitro cytokine production by liver-infiltrating T cells of patients with autoimmune hepatitis

The pathogenic mechanisms underlying the development of autoimmune hepatitis (AIH) are still unclear. Since AIH is associated with the presence of various autoantibodies and certain HLA subtypes, it is likely that T and B cells play a major role in this disease. In this study we have determined the functional capacities of in vivo preactivated liver-infiltrating T cells (LTC) from patients with AIH. As controls we used LTC from patients with non-autoimmune hepatitis (non-AIH). Our results show that preactivated LTC from patients with AIH predominantly (190/255 clones) reside in the CD4+ population, whereas LTC in non-AIH are dominated by the CD8+ phenotype (148/254 clones). In view of this finding we have investigated the cytokine secretion patterns of 102 randomly chosen CD4+ T cell clones from six patients with AIH. As controls we have used 58 CD4+ LTC from 11 patients with non-AIH. All clones were stimulated by lectin and irradiated accessory cells and subsequent cytokine production was evaluated. LTC from patients with AIH have a lower interferon-gamma (IFN-gamma)/IL-4 ratio compared with LTC from non-AIH. Although clones from some patients with AIH produced very high amounts of IL-4 in vitro, this was not a constant finding. These results show that in vivo preactivated LTC from patients with AIH are mostly CD4+ T cells that produce more IL-4 than IFN-gamma. In contrast, LTC from patients with non-AIH are dominated by CD8+ and CD4+ T cells that produce significantly less IL-4 than IFN-gamma. Thus, liver-infiltrating T cells from patients with AIH and non-AIH belong to different functional T cell subsets. This may have implications for the regulation of humoral and cellular immune responses in inflammatory liver disease.

Autoantibodies against the human asialoglycoprotein receptor: effects of therapy in autoimmune and virus-induced chronic active hepatitis

The hepatic asialoglycoprotein receptor (ASGPR) was recently identified as a target antigen for both humoral and cellular immune response in inflammatory liver diseases. Thereby anti-ASGPR autoantibodies directed against human substrate were closely associated with autoimmune chronic active hepatitis. The present study compares the occurrence, titer and immunoglobulin classification of anti-human(h-)-ASGPR antibodies in 23 patients with newly diagnosed autoimmune chronic hepatitis before and after initiation of immunosuppressive therapy to 22 patients with autoimmune hepatitis in remission. Additionally, 1-year follow-up examinations of 42 patients with HBsAg-positive chronic hepatitis and of 32 patients with chronic hepatitis C receiving recombinant interferon-alpha were included. Nineteen of 23 patients with newly diagnosed and 9/22 with autoimmune hepatitis in remission, 5/42 with untreated chronic hepatitis B and 5/32 patients with chronic hepatitis C exhibited anti-h-ASGPR at the beginning of the study. In autoimmune hepatitis anti-h-ASGPR were found in higher titers (median > 1:1000) than in viral hepatitis (maximum 1:400). After initiation of immunosuppressive therapy in autoimmune hepatitis anti-h-ASGPR decreased sharply. Eight of 19 patients eliminated anti-h-ASGPR within 18 months in contrast to 11 patients with persistent anti-h-ASGPR titer over 18 months and longer. Anti-h-ASGPR with maximum titer of 1:600 were detected in 5 patients with chronic hepatitis B (transiently in 4/5 patients) and in 2 patients with chronic hepatitis C during interferon-alpha. Anti-h-ASGPR were from immunoglobulin classes IgG and IgM in cases with untreated autoimmune hepatitis and chronic hepatitis B and C exhibiting mainly IgG2-subclass in autoimmune and IgG4 in viral hepatitis.(ABSTRACT TRUNCATED AT 250 WORDS)

Autoreactive liver-infiltrating T cells in primary biliary cirrhosis recognize inner mitochondrial epitopes and the pyruvate dehydrogenase complex

Primary biliary cirrhosis (PBC) is characterized by lymphoid infiltrates in the portal tracts of the liver and the occurrence of antimitochondrial autoantibodies in serum directed against components of the pyruvate dehydrogenase complex and the other alpha-keto acid dehydrogenase complexes. These enzymes are located on the inner mitochondrial membrane. The destruction of the biliary tract in PBC is thought to be mediated by autoreactive liver-infiltrating T cells exerting cytotoxic activity or releasing certain lymphokines. In this study the reactivity of liver infiltrating T cells was shown to a bovine pyruvate dehydrogenase complex (PDH), a purified E2 subunit (PDH-E2) and a crude preparation of human liver mitoplasts (HLM), i.e. mitochondria depleted of their outer membranes. Peripheral blood lymphocytes (PBL) from 11 of 15 patients (73.3%) with PBC showed a HLA class II-restricted proliferative response to the PDH complex whereas PBL from patients with chronic viral hepatitis, autoimmune hepatitis or extrahepatic cholestatic icterus (n = 20) and healthy controls (n = 5) did not. In addition 13 of 15 PBL from patients with PBC (86.6%) and three of nine PBL from patients with autoimmune hepatitis (33.3%) reacted with the crude HLM preparation whereas no reactivity was found with PBL from eight patients with chronic viral hepatitis, three patients with extrahepatic cholestasis or five healthy controls. Clonal analysis of 115 liver-infiltrating T cells derived from two diagnostic liver biopsies of patients with PBC revealed a predominance of activated CD4+CD8- T helper cells.(ABSTRACT TRUNCATED AT 250 WORDS)