Susceptibility to autoimmune chronic active hepatitis: human leukocyte antigens DR4 and A1-B8-DR3 are independent risk factors

Type 1 autoimmune hepatitis in Turkish patients: absence of association with HLA B8

BACKGROUND

There is very little information about autoimmune hepatitis (AIH) in populations other than of white European or Japanese descent.

GOALS

To investigate the presenting features, immunogenetic background, and response to standard immunosuppressive therapy in native Turkish patients with AIH.

METHODS

Retrospective analysis of all patients referred between 1994 and 2000 to our hepatology clinic in Ankara who fulfilled international criteria for definite or probable type 1 or type 2 AIH.

RESULTS

Seventeen patients (15 female; median age, 31 years; range, 13-56 years) were identified. All had type 1 AIH. Clinical and laboratory features were broadly similar to those reported for white or Japanese patients. Five had the HLA DR3 allotype and 10 had DR4; however, in contrast to white and Japanese patients, DR4 was not associated with an older age at onset. Importantly, no patient had the B8 allotype (vs. 10.9% in 110 healthy Turkish subjects). Thus, none had the classic A1-B8-DR3 autoimmune haplotype: a major distinction from white individuals.

CONCLUSIONS

There appears to be genetic differences in type 1 AIH between Turkish and other populations. Genotyping of Turkish patients to identify alleles that may confer susceptibility or resistance to AIH may progress understanding of the genetic basis of the disease.

Genetic effects on susceptibility, clinical expression, and treatment outcome of type 1 autoimmune hepatitis

Currently, three genetic factors have been short-listed as possible modulators of susceptibility and severity in type 1 AIH. They are female sex, HLA DRB alleles encoding lysine at position DR beta 71, and the CTLA4*G allele. The fourth association (i.e., TNFRSF6) remains to be confirmed. There are many other candidates to investigate. Current hypotheses suggest that the autoimmune genotype will include multiple (some linked, others discrete) loci which make a permissive background. Not all "at risk" individuals will develop clinical disease, and selection will depend on the interaction of this "permissive gene pool" (i.e., the host) with the environment. The resulting autoimmune phenotype will depend on gene dose and gene interaction. The human genome project has presented medical science with the challenge to identify the genes that determine common human diseases, including autoimmunity [1]. Although type 1 AIH is considerably less common than diabetes or RA, it may serve as a useful model for other autoimmune diseases. Diagnosis depends on histologic findings, and liver biopsy examinations are part of the usual assessment strategy in type 1 AIH. The availability of these tissue specimens provides a clear basis for monitoring disease progression and may permit investigators to study the impact of genetic polymorphism on disease activity. The emergence of high throughput technologies will significantly enhance our ability to study the interactions between constellations of polymorphic genes and both disease expression and behavior. An abundance of polymorphism is found in the genome. In many diseases, functional studies and genome scanning have helped revise and reduce the list of candidates. Affected families are rare in type 1 AIH, and patients are at risk if corticosteroid treatment is withheld. Under these circumstances, genetic studies may be the most practical, low risk means to investigate the pathogenesis of type 1 AIH and many other autoimmune diseases.

Autoimmune cholangitis: not just AMA-negative primary biliary cirrhosis

Variant forms of chronic cholestatic liver disease in adults, such as autoimmune cholangitis, primary biliary cirrhosis-autoimmune hepatitis overlap, and primary sclerosing cholangitis-autoimmune hepatitis overlap constitute approximately 20% of cases of autoimmune liver disease. Retrospective study design may obscure subtle differences in clinical features. Careful prospective studies are needed to help clarify classification of these disorders. Autoimmune cholangitis is often considered synonymous with antimitochondrial antibody-negative primary biliary cirrhosis, but may instead be a heterogeneous group of disorders including some cases of isolated small duct primary sclerosing cholangitis. The variable response of variant syndromes to established therapies such as corticosteroids provides justification for continued efforts to define their clinicopathologic features.

Antibodies to conformational epitopes of soluble liver antigen define a severe form of autoimmune liver disease

Prevalence and clinical relevance of antibodies to soluble liver antigen (tRNP((Ser)Sec)/SLA) in autoimmune hepatitis (AIH) have been investigated using partially purified or prokaryotically expressed antigen. The aim of this study was to improve the detection of anti-tRNP((Ser)Sec)/SLA by establishing an immunoassay that was able to identify antibodies directed to conformational epitopes and to investigate the clinical implication of this autoantibody in autoimmune liver disease. By using eukaryotically expressed tRNP((Ser)Sec)/SLA as target in a radioligand assay (RLA), 81 patients with autoimmune liver disease (AILD) (33 type 1 AIH, 31 type 2 AIH, and 17 autoimmune sclerosing cholantitis [ASC]), 147 pathologic, and 56 healthy controls were investigated. RLA results were compared with those obtained using a commercial enzyme-linked immunosorbent assay (ELISA) and immunoblot. Reactivity to tRNP((Ser)Sec)/SLA was present in 58% of patients with type 1 and type 2 AIH, 41% with ASC, but in only 3 pathologic controls. RLA was similarly disease-specific but remarkably more sensitive than ELISA and immunoblot. A prospective study showed that anti-tRNP((Ser)Sec)/SLA-positive patients run a severe clinical course, having worse histology, needing longer to achieve remission, relapsing and requiring liver transplantation or dying more frequently than anti-tRNP((Ser)Sec)/SLA negative patients. Anti-tRNP((Ser)Sec)/SLA production was favored by the possession of DR3 and A1-B8-DR3 in AIH type 1 and ASC, and prevented by the possession of A2 in all 3 types of AILD, particularly in type 2 AIH. In conclusion, anticonformational tRNP((Ser)Sec)/SLA reactivity is frequent in type 1 and type 2 AIH and ASC, defining patients with a worse prognosis.

Response to steroids in de novo autoimmune hepatitis after liver transplantation

Graft dysfunction associated with autoimmune phenomena has been recently described in liver transplant recipients without previous autoimmune disease. However, the natural history, diagnostic criteria, and definitive therapeutic approach of de novo autoimmune hepatitis (de novo AIH) are poorly understood. We report 12 cases of de novo AIH 27.9 +/- 24.5 months after liver transplantation: the outcome of 7 patients treated with steroids is compared with a group of 5 nontreated patients. Nontreated patients lost the graft after 5.8 +/- 2.6 months from de novo AIH onset. All treated patients were alive after 48.4 +/- 14 (29-65) months from de novo AIH onset, and none of them lost the graft. However, 5 patients relapsed in relation to steroid tapering. All patients presented an atypical antiliver/kidney cytosolic autoantibody, associated to classical autoantibodies in 10 cases. Histological study showed several degrees of lobular necrosis and inflammatory infiltrate. HLA antigen frequencies and matching were compared with 2 control groups (16 orthotopic liver transplantation [LTX] patients without de novo AIH and 929 healthy blood donors); de novo AIH patients showed a higher prevalence of HLA-DR3 (54.5% vs. 25.9%, P =.04) than healthy controls, which was not observed in LTX patients without de novo AIH. In conclusion, this new disease should be included in the differential diagnosis of unexplained graft dysfunction. In addition, treatment with steroids results in a dramatically improved outcome. However, maintenance therapy is usually required.

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Mechanisms of liver injury relevant to pediatric hepatology

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

Autoimmune liver disease

Autoimmune liver disorders are inflammatory liver diseases characterised histologically by a dense mononuclear cell infiltrate in the portal tract and serologically by the presence of non-organ and liver specific autoantibodies and increased levels of immunoglobulin G (IgG), in the absence of a known etiology. They usually respond to immunosuppressive treatment, which should be instituted as soon as diagnosis is made. The onset is variable and often mimics acute hepatitis. The previously accepted requirement of six month duration of symptoms before a diagnosis of autoimmune disease could be made has been abandoned.

Current and novel immunosuppressive therapy for autoimmune hepatitis

Corticosteroids alone or in conjunction with azathioprine is the treatment of choice in patients with autoimmune hepatitis (AIH) and results in remission induction in over 80% of patients. Sustained response to therapy may result in substantial regression of fibrosis even in advanced cases. The outcome of rapid withdrawal of immunosuppression is disease relapse in many patients. Consequently, the use of 2 mg/kg/d of azathioprine as a sole agent to maintain remission has been widely accepted in clinical practice. Persistent severe laboratory abnormalities or histologic abnormalities such as bridging necrosis or multilobular necrosis are absolute indications for treatment based on controlled clinical trials, but debate exists as to whether all patients with AIH need treatment. Examination of liver tissue remains the best method of evaluating both treatment response and need for treatment in patients who have little biochemical activity. Alternative strategies in patients who have failed to achieve remission on "standard therapy" of corticosteroids with or without azathioprine or patients with drug toxicity include the use of cyclosporine, tacrolimus, or mycophenolate mofetil. Liver transplantation is the treatment of choice in managing decompensated disease. In this review we examine current management strategies of AIH, and evaluate available data pertaining to the use of novel immunosuppressive agents in this condition.

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

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

CTLA-4/CD 28 region polymorphisms in children from families with autoimmune hepatitis

Susceptibility to autoimmune hepatitis is associated with particular human leucocyte antigen class II alleles. However, non-HLA genetic factors are likely to be required for development of the disease. Among the candidate genes, the cytotoxic T-lymphocyte antigen 4 (CTLA-4) and CD28 genes, located on chromosome 2q33 in humans, encode a cell surface molecule playing a dominant role in the regulation of T-cell activation. The CTLA-4 and CD28 polymorphisms were investigated in children from 32 families with autoimmune hepatitis (AIH). The transmission/disequilibrium test revealed increased transmission of the (AT)8 (dinucleotide repeat) and A (exon 1) alleles of CTLA-4 gene from heterozygous parents to affected offspring (87.5% and 83.5%) with type 1 AIH, compared with unaffected offspring (50.0% for both, p = 0.009 and 0.02, respectively). In contrast, no deviation in transmission for CTLA-4 polymorphisms was found between type 2 AIH patients and unaffected offspring. No evidence for association was found between CD28 gene polymorphism or D2S72 genetic marker and both types of AIH. This study identified the CTLA-4 gene polymorphism as a non-HLA determinant that predisposes to AIH type 1 in children. The genetic heterogeneity seen in the present study provides a new argument in favor of pathogenic differences between type 1 and type 2 AIH.

Recurrent autoimmune hepatitis after orthotopic liver transplantation

To determine the frequency, risk factors, and consequences of recurrent autoimmune hepatitis after liver transplantation, 41 patients with type 1 disease were monitored after surgery in accordance with a surveillance protocol. Tacrolimus or cyclosporine plus prednisone were administered to each patient, and liver biopsy examinations were performed at least annually according to protocol. Corticosteroid therapy was ultimately discontinued in only 2 patients. Recurrent disease was defined as the presence of lymphoplasmacytic infiltrates in liver tissue in the absence of other causes of allograft dysfunction. Autoimmune hepatitis recurred in 7 patients (17%), and the mean time to recurrence was 4.6 +/- 1 years. Recurrence was asymptomatic in 4 of 7 patients and detected only by surveillance liver biopsy assessment in 2 patients. Histological changes were mild, and there was no progression to cirrhosis during 4.9 +/- 0.9 years of observation. Five-year patient (86% v. 82%; P =.9) and graft (86% v. 67%; P =.5) survival rates were not statistically different between patients with and without recurrent disease. HLA-DR3 or HLA-DR4 occurred more commonly in patients with than without recurrence (100% v. 40%; P =.008) and healthy subjects (100% v. 49%; P =.01). Recurrent disease was unrelated to donor HLA status. In conclusion, recurrence after transplantation for type 1 autoimmune hepatitis is common. Its mild manifestations and favorable prognosis may reflect early detection by a surveillance protocol and/or continuous corticosteroid treatment. HLA-DR3- or HLA-DR4-positive recipients are at risk for recurrence regardless of donor HLA status.

Understanding the pathogenesis of autoimmune hepatitis

OBJECTIVES

The aim of this study was to review the pathogenic mechanisms of autoimmune hepatitis, identify gaps in knowledge, and focus future investigative efforts.

METHODS

The study was based on a review of all relevant articles on the mechanisms of autoimmunity in autoimmune liver disease from 1980 to 2000, extraction of pertinent concepts from the medical literature; and integration of evolving paradigms of pathogenesis with personal experiences and investigations.

RESULTS

Autoimmune hepatitis is a consequence of autoantigen exposure, genetic predisposition, and defective immunoregulatory mechanisms. Autoantigen is optimally presented by class II molecules of the major histocompatibility complex that have lysine residues at position DRbeta71 of the antigen-binding groove. Cytokines and non-disease-specific autoimmune promoters modulate immune reactivity. Cell-mediated and antibody-dependent mechanisms contribute to hepatocyte injury.

CONCLUSIONS

Multiple disturbances in the homeostatic mechanisms that preserve self-tolerance are likely in autoimmune hepatitis. Future investigations must focus on individual determinants of autoantigen presentation, immunocyte activation, and liver cell destruction. Findings can then be integrated into a comprehensive knowledge base that may be applicable to other autoimmune diseases.

Primary biliary cirrhosis with features of autoimmune hepatitis

The diagnosis of primary biliary cirrhosis (PBC) is made via a composite of clinical, laboratory, serologic, and histologic assessments, but within each parameter there exists a wide spectrum, so that the features of PBC are not always uniform. PBC is just one of several liver diseases thought to have an autoimmune basis. Therefore, it is not surprising, given the complexity of the immune response, that some patients thought to have PBC may have features of autoimmune hepatitis (AIH). Whether such patients have PBC with features of AIH, or antimitochondrial antibody-negative PBC, or another disease altogether, remains unclear.

T cell receptor Vbeta chain restriction and preferred CDR3 motifs of liver-kidney microsomal antigen (LKM-1)-reactive T cells from autoimmune hepatitis patients

AIMS/BACKGROUND

The liver-kidney-microsomal antigen (LKM-1) has been recognized as a major CD4+ T cell antigen in autoimmune hepatitis (AIH). The aim of this study was to characterize the antigen recognition sites of the variable T cell receptor beta-chain (TCRBV) of T cells specific to LKM-1.

METHODS

By repeated stimulation of T cells with a recombinant LKM-1 antigen or an LKM-derived peptide followed by limited dilution, we generated T cell clones. Usage of TCRBV was analyzed by RT-PCR and CDR3 antigen recognition sites were sequenced.

RESULTS

The 18 LKM-1 specific T cell clones isolated from six AIH patients preferentially expressed the TCR elements BV9, BV5S2+S3, BV6, and BV13S1. Four BV9+ T cell clones rearranged the joining element JB1S3 within their CDR3 regions. JB2S3 was detected in another four clones together with BV5S2+S3 or BV13S1. A conserved sequence motif, Q(N)G(X)N, was seen in the diversity regions of five clones (36%). In order to identify T cells expressing the preferred TCRBV molecules in situ, immunohistologic examination of liver biopsies was performed. In AIH patients an accumulation of T cells expressing TCRBV 13S1, BV8 and BV5S3 was observed.

CONCLUSIONS

Our data define TCRBV restriction and preferred CDR3 features of LKM-1 specific T cells. The in situ localization of T cells expressing these restricted TCR molecules may suggest a pathogenic relevance of LKM-1 specific cellular immune responses.

LKM-positive autoimmune hepatitis in the western United States: a case series

OBJECTIVE

LKM-positive, or type 2, autoimmune hepatitis is characterized by the presence of antibodies directed against liver-kidney microsomes (LKM1). Although described frequently in southern Europe and the Mediterranean, this subtype of autoimmune liver disease seems to be extremely rare in northern Europe and in the United States. We report here five cases of LKM-positive autoimmune hepatitis that were seen at our center in the period 1989-1999.

METHODS

We reviewed the medical records of all patients with the diagnosis of AIH in our institution during the period 1989-1999, and found that five patients had type 2 AIH. All patients were female; four of five were young, and four of five presented with overt cirrhosis.

RESULTS

One patient died, one underwent liver transplantation and two are currently awaiting liver transplantation. Response to conventional immunosuppressive therapy was poor and two patients required treatment with cyclosporine and tacrolimus respectively. Four of five patients had at least one associated autoimmune disorder, including IgE-induced IgA deficiency, idiopathic thrombocytopenic purpura (ITP), and arthritis. HLA class II DR4 was present in two patients.

CONCLUSIONS

LKM-positive autoimmune hepatitis seems to be a subset of autoimmune hepatitis with distinct clinical features; although rare, it is occasionally encountered in the western United States. Prompt diagnosis and appropriate immunosuppressive treatment are recommended, as well as early referral to transplantation centers. Clinicians should be aware of this condition in the setting of young female patients with unexplained severe liver disease.

Liver transplantation for autoimmune hepatitis

Publications about liver transplantation (LTX) for autoimmune hepatitis (AIH) have started to emerge, but many issues remain unresolved. We reviewed data on 32 patients transplanted for AIH to determine how pretransplantation and posttransplantation characteristics correlate with recipient outcome, including disease recurrence. Recipients were 37+/- 14 years old; 30 of 32 were women. Most had chronic disease (8 +/- 6 years); 25% had fulminant failure. The majority had ascites (91%), jaundice (88%), elevated prothrombin time (18 +/- 3 seconds), and hypoalbuminemia (2.7 +/- 0.6 g/dL). All had hypergammaglobulinemia (3.0 +/- 1.0 g/dL) and autoantibodies (72% antinuclear, 74% smooth muscle). Only one was HLA A1-B8-DR3 positive. Other autoimmune disorders affected 25% of patients; half improved after transplantation. Actuarial survival was 81% at 1 and 2 years posttransplantation. There was a high frequency of rejection (75% of recipients had 1.7 +/- 0.8 episodes), and 39% of rejections required OKT3. Among 24 recipients with long-term follow-up (27 +/- 14 months), histologically proven recurrent AIH occurred in 25%, 15 +/- 2 months posttransplantation; half (3 patients) required retransplantation 11 +/- 3 months after diagnosis. After retransplantation 2 of 3 patients had re-recurrence within 3 months; 1 received a third LTx. Recurrence occurred in 6 of 18 patients transplanted for chronic disease vs. 0 of 6 transplanted as fulminants (P = not significant [NS]). Patients with and without recurrence had similar rejection profiles. In summary, results of LTx for AIH are excellent. However, AIH patients have a high frequency of rejection and often require OKT3. Furthermore, severe recurrent AIH sometimes develops, particularly in chronic versus fulminant AIH patients and in those already retransplanted for recurrence. Multicenter studies could elucidate the best posttransplantation immunosuppressive regimens for AIH patients.

Autoimmune cholangitis within the spectrum of autoimmune liver disease

Autoimmune cholangitis is an idiopathic disorder with mixed hepatocellular and cholestatic findings. Our goal was to characterize the disease prospectively by application of uniform diagnostic criteria. Twenty patients were identified and compared with 242 patients with conventional forms of autoimmune liver disease. Patients with autoimmune cholangitis were distinguished from type 1 autoimmune hepatitis (AIH) by lower serum levels of aspartate transaminase (AST), gamma-globulin, and immunoglobulin G; higher serum levels of alkaline phosphatase; and lower frequencies of autoantibodies. They were distinguished from primary biliary cirrhosis (PBC) by higher serum levels of AST and bilirubin, lower serum concentrations of immunoglobulin M, and greater occurrence of autoantibodies. Their female predominance, lower serum alkaline phosphatase levels, higher frequency of autoantibodies, and absence of inflammatory bowel disease differentiated them from primary sclerosing cholangitis (PSC). Laboratory findings ranged widely and did not characterize individual patients. HLA risk factors were similar to those of type 1 AIH and PBC, and different from those of PSC. Treatment responses to corticosteroids or ursodeoxycholic acid were poor. Composite histological patterns resembled mainly PBC or PSC. We conclude that autoimmune cholangitis diagnosed by prospective analysis cannot be assimilated into a single, conventional, diagnostic category. It may represent variant forms of diverse conditions, a transition stage, or a separate entity with varying manifestations.

Mechanisms of autoimmune liver disease

Several lines of evidence suggest that autoimmune hepatitis and primary biliary cirrhosis are autoimmune diseases. This article discusses both the immunologic mechanisms of liver injury and the mechanisms of cell injury mediated by lymphocytes. This article also reviews the proposed immunopathogenesis of autoimmune hepatitis and primary biliary cirrhosis.

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.

Cytotoxic T lymphocyte antigen-4 (CTLA-4) gene polymorphisms and susceptibility to type 1 autoimmune hepatitis

Genetic susceptibility to type 1 autoimmune hepatitis is indicated by a preponderance of female subjects and strong associations with human leukocyte antigens (HLA) DRB1*0301 and DRB1*0401. The gene encoding cytotoxic T-lymphocyte antigen-4 (CTLA-4) on chromosome 2q33 may also influence autoimmunity. To determine the frequency and significance of the exon 1 adenine (A)-guanine (G) base-exchange polymorphism for CTLA-4 in patients with type 1 autoimmune hepatitis, 155 northern European Caucasoid patients and 102 ethnically-matched control subjects were tested by polymerase chain reaction. The genotype distribution was significantly different in patients compared to controls (AA = 50/155 patients vs. 51/102 controls; AG = 84/155 patients vs. 38/102 controls; GG = 21/155 patients vs. 13/102 controls, chi(2) = 8.94, P =.011). This difference was caused by a significant over-representation of the G allele in patients compared to controls (105/155 patients vs. 51/102 controls, chi(2) = 8.34, P =.004, odds ratio = 2.12). The GG genotype was associated with a significantly higher mean serum aspartate transaminase level (P =. 03), greater frequency of antibodies to thyroid microsomal antigens (P =.004) and was found more commonly in patients with HLA DRB1*0301 (P =.02). Treatment outcomes, however, were not affected by the genotype. The CTLA-4 G allele is more common in patients with type 1 autoimmune hepatitis and may represent a second susceptibility allele. Furthermore, there may be synergy between the HLA-DRB1*0301 and the GG genotype in terms of disease risk.

Pediatric and adult forms of type I autoimmune hepatitis in Argentina: evidence for differential genetic predisposition

The aim of this study was to compare major histocompatibility complex (MHC) class II susceptibility to type 1 autoimmune hepatitis (AH) between children and adults of the same ethnic group. HLA-DRB1, HLA-DRB3, HLA-DQA1, and HLA-DQB1 gene subtypes were examined by high resolution oligonucleotide typing in 122 pediatric (PAH) and 84 adult (AAH) patients and in 208 controls. In children, HLA-DRB1*1301 was the primary susceptibility allele (66.4% patients vs. 10.6% controls, relative risk [RR] = 16.3, Pc < 10(-24)) whereas HLA-DRB1*1302, which differs from HLA-DRB1*1301 by only 1 amino acid, appeared to be protective. The exclusion of individuals with HLA-DRB1*1301 from control and pediatric patients allowed us to find a secondary association of PAH with HLA-DRB1*0301. Possession of HLA-DRB1*1301, however, was associated with a lower therapeutic response rate. Analysis of peptide binding pocket residues indicated that Tyr 10, Ser 11, Ser 13, and Val 86 in the class II beta chain were present in 85% of patients compared with 37% of controls, suggesting that a high proportion of AH susceptibility is attributable to these residues (etiologic fraction [EF] = 76%). In contrast to the class II associations in children, AAH was associated with HLA-DRB1*0405 (RR = 10.4, Pc <.005) but not with HLA-DRB1*1301 or HLA-DRB1*0301. In addition, HLA-DR4 with the class I gene, HLA-A11, appeared synergistic in predisposing AAH patients to develop extra-hepatic autoimmune (AI) manifestations (odds ratio [OR] = 104.9, Pc < 10(-4)). Concomitant differences in autoantibody profiles were also observed in PAH versus AAH: smooth muscle antibodies (SMA) were most prevalent in PAH but antinuclear antibodies were most prevalent in AAH (P =.003). This study therefore reveals that different HLA-DRB1 allotypes confer susceptibility to AH in children and adults and raises the possibility that PAH and AAH may be triggered by different factors.

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.

Frequency and nature of cytokine gene polymorphisms in type 1 autoimmune hepatitis

Genetic involvement in type 1 autoimmune hepatitis (AIH) is indicated by a marked female preponderance and strong, well-established, human leukocyte antigen (HLA) associations. These associations, however, are not universal and a number of genes outside the major histocompatibility complex may also play a role in susceptibility to type 1 AIH. Prime candidates at present are those polymorphic genes encoding the proinflammatory and immunoregulatory cytokines. The aim of this study was to investigate, for the first time, 2 members of the interleukin-1 (IL-1) family (IL-1B and IL-1RN), 3 polymorphic sites in the interleukin-10 (IL-10) gene promoter (positions -1082, -819, and -592), and 2 polymorphisms in the tumor necrosis factor-alpha (TNF-alpha) promoter (positions -308 and -238) in type 1 AIH. The study was performed on 2 independently collected DNA banks, each with appropriate controls, and throughout the analysis associations described in the first set were confirmed in the second set. Standard polymerase chain reaction (PCR)-based genotyping techniques were used. Overall there were no significant differences in the distributions of the IL-1B and IL-10 alleles, genotypes, or haplotypes in either study set. In contrast we report a significant association between type 1 AIH and TNF*2 (first set: 34% of controls vs. 49% of patients, Pc =.014 and second set: 26% vs. 56%, P =.00008). However, TNF*2 is found in strong linkage disequilibrium with the HLA A1-B8-DR3 haplotype and stratification analysis indicates that the association with TNF*2 is interdependent with HLA DRB1*0301. This is an indication that there is more than one susceptibility allele for type 1 AIH on chromosome 6p21.3.

Cytokine polymorphisms associated with clinical features and treatment outcome in type 1 autoimmune hepatitis

BACKGROUND & AIMS

Polymorphisms that control cytokine production can affect immunoregulation. The frequency and consequences of these polymorphisms in type 1 autoimmune hepatitis were determined.

METHODS

DNA samples from 155 patients and 102 ethnically similar normal individuals were assessed by polymerase chain reaction for polymorphisms of 4 different cytokine-producing genes.

RESULTS

Only genotypes associated with the guanine to adenine substitution at position -308 of the tumor necrosis factor gene occurred more commonly in patients than in normal subjects (56% vs. 26%; P < 0.001). Patients with this polymorphism had the HLA DRB1*0301 allele (81% vs. 10%; P < 0.000001) and A1-B8-DRB1*0301 (66% vs. 0%; P < 0.000001) phenotype more frequently and HLA DRB1*04 alleles less often (24% vs. 67%; P < 0.000001). They also entered remission less commonly (56% vs. 78%; P = 0.01), had treatment failure more often (20% vs. 7%; P = 0.03), and developed cirrhosis more frequently (40% vs. 19%; P = 0.05). These latter differences, however, were not statistically significant by adjusted P value.

CONCLUSIONS

A polymorphism of the tumor necrosis factor gene occurs more commonly in patients with type 1 autoimmune hepatitis than in normal subjects; it is associated with a poorer response to corticosteroids. The polymorphism may be inherited as part of the extended A1-B8-DRB1*0301 haplotype and may affect both disease expression and behavior.

Development of autoimmune hepatitis following liver transplantation for primary biliary cirrhosis

Two patients undergoing liver transplantation for classical end-stage primary biliary cirrhosis (PBC) are described, who went on to develop de novo autoimmune hepatitis (AIH) in the transplanted liver. The presentation, in both instances, was with malaise and lethargy. Markedly elevated serum transaminases were found, together with a raised serum IgG and/or globulin fraction and histological features on liver biopsy typical of AIH. Both cases had had changes in their immunosuppressive therapy before the onset of AIH episodes, and both rapidly responded to reinstitution of steroid therapy. The finding, in each case, of a coincidental multiple HLA class I allele match between the recipient and their liver donor suggests that HLA class I-restricted mechanisms may play an important role in the pathogenesis of AIH.

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.

Increased bcl-2 expression in lymphocytes and its association with hepatocellular damage in patients with autoimmune hepatitis

The proto-oncogene product bcl-2 is known to inhibit apoptotic cell death, and its dysregulation might play a critical role in the development of autoimmune disease. To elucidate the role of bcl-2 in autoimmune hepatitis (AIH), its expression in peripheral blood mononuclear cells (PBMC) and in liver-infiltrating lymphocytes (LIL) was investigated. Increased bcl-2 expression in PBMC was found in AIH patients compared with that in chronic hepatitis C (CHC) patients and in healthy controls. The level of bcl-2 expression significantly correlated with serum ALT level. Further analysis showed that CD4+ T cells are enriched in bcl-2-expressing PBMC. To characterize the Th1/Th2 profile of bcl-2-expressing CD4+ T cells, intracellular interferon-gamma (IFN-gamma) and IL-4 were analysed. The results revealed that most of the bcl-2-expressing cells were found to be IFN-gamma-secreting Th1 cells. In three patients for whom their clinical courses could be followed, bcl-2 expression was decreased after the initiation of immunosuppressive therapy with corticosteroids. However, the level of IFN-gamma + cells was not altered. Immunohistochemical analysis also showed that large amounts of bcl-2+ cells were observed in periportal area in the liver. In conclusion, bcl-2-expressing cells were shown to be increased in peripheral blood and liver in AIH and the bcl-2 product was expressed mainly in CD4+ Th1-type cells, suggesting that these cells might promote the cellular immune response and contribute to the development of hepatitis and hepatocellular damage in AIH.

Autoimmune polyglandular syndromes

Autoimmune polyglandular syndrome type 1 (APS1) is characterized by a variable combination of disease components: (1) mucocutaneous candidiasis; (2) autoimmune tissue destruction; (3) ectodermal dystrophy. The disease is caused by mutations in a single gene called APECED (autoimmune polyendocrinopathy-candidiasis-ectodermal-dystrophy) or AIRE (autoimmune regulator) coding for a putative transcription factor featuring two zinc-finger (PHD-finger) motifs. APS1 shows a penetrance of 100%, lack of female preponderance and lack of association with HLA-DR. Typically, onset of APS1 occurs in childhood and multiple autoimmune manifestations evolve throughout lifetime. Organ-specific autoantibodies associated with hypoparathyroidism, adrenal and gonadal failures, IDDM, hepatitis and vitiligo are discussed, and autoantibody patterns in APS1 patients are compared with autoantibodies in APS type 2 (APS2). APS2 is characterized by adult onset adrenal failure associated with IDDM and/or hyperthyroidism. APS2 is believed to be polygenic, characterized by dominant inheritance and association with HLA DR3.

MHC class II sequences of susceptibility and protection in Mexicans with autoimmune hepatitis

BACKGROUND/AIMS

Autoimmune hepatitis has a genetic background associated with different HLA DRB1 alleles depending on the ethnic group. The aim of this study was to analyse the immunogenetics of type I autoimmune hepatitis in Mexicans.

METHODS

Thirty Mexican Mestizo patients and 175 healthy controls were HLA typed as follows: class I antigens were determined by microlymphocytotoxicity and class II typing was done on DNA samples using PCR-SSO and PCR-SSP for DRB1, DQA1 and DQB1 loci.

RESULTS

A significant association of autoimmune hepatitis with DRB1*0404 was found, (chi2Y=19.95, pc=0.002, RR=7.71), suggesting the presence of a susceptibility gene located at the DRB1 locus. Resistance was at least partially due to a DQB1 gene, since a significant decrease in DQB1*0301 was also detected (chi2Y=8.21, pc=0.04). Analysis of subgroups according to age at onset showed an association with DRB1*0404 (chi2Y=4.31, p=0.04) in patients with late onset (after 30 years), while DQA1*0501 (chi2Y=5.12, p=0.02) was increased in the early onset group.

CONCLUSIONS

The possible mechanism of HLA association is due to "shared epitopes", since DRB1*0404, and those found in other populations namely, DRB1*0401, *0405 and *0301 share almost the same sequence at position 67-72 (LLEQRR, R or K at 71). Valine-86 is also relevant to the age at onset because DRB1*0404 is increased in the patients with an average age at onset of 32. These findings are relevant in determining which peptides in the liver are targets for T cells.

De-novo autoimmune hepatitis after liver transplantation

BACKGROUND

Late graft dysfunction that does not result from recognised causes, such as rejection, infection, or vascular or biliary complications, can occur after liver transplantation. We investigated a particular type of unexplained graft dysfunction that is associated with autoimmune features in children who underwent transplantation at our unit between 1991 and 1996.

METHODS

Seven (4%) of 180 liver-transplant recipients developed an unexplained but characteristic form of graft dysfunction (five boys, two girls; median age at presentation 10.3 years, range 2.0-19.4). The median period after surgery was 24 months (6-45). The indications for transplantation had been extrahepatic biliary atresia (four patients), Alagille's syndrome (one), drug-induced acute liver failure (one), and alpha1-antitrypsin deficiency (one). Four patients were on triple immunosuppression with cyclosporin, azathioprine, and prednisolone; and three were on tacrolimus. Immunoglobulin measurements, autoantibody studies, serological studies, and HLA typing were undertaken. Liver-biopsy samples were taken.

FINDINGS

Infectious and surgical complications were excluded. Liver-biopsy samples showed the histological changes of chronic hepatitis, including portal and periportal hepatitis with lymphocytes and plasma cells, bridging collapse, and perivenular-cell necrosis without changes typical of acute or chronic rejection. All patients had high concentrations of IgG (median 22 g/L [range 17.2-34.4]) and high titres of autoantibodies. All but one patient responded to prednisolone 2 mg/kg daily and an increase in or addition of azathioprine (1.5 mg/kg daily) within a median of 32 days (7-316). One responder relapsed owing to poor compliance but went into remission after treatment was restored. All six respondents remain in remission on a reduced dose of prednisolone (5-10 mg/day) and 1.5 mg/kg daily azathioprine at a median of 283 days (range 108-730) follow-up.

INTERPRETATION

Our data show that symptoms of autoimmune hepatitis, which are responsive to the classical treatment for this condition, can appear in liver-transplant patients while they are on anti-rejection immunosuppression. Whether the liver damage in these patients is a form of rejection or the consequence of autoimmune attack has yet to be established.

Influence of HLA haplotypes on the clinical courses of individuals infected with hepatitis C virus

The human leukocyte antigen is a crucial genetic factor that initiates or regulates immune response by presenting foreign or self antigens to T lymphocytes. The aim of this study was to investigate whether HLA polymorphism is associated with the onset or progression of liver injury in chronic hepatitis C virus (HCV) infection. We determined HLA class I antigens and class II alleles in 130 hepatitis C virus (HCV)-infected patients (33 carriers with persistently normal alanine transaminase [ALT] values and 97 patients with chronic liver disease [CLD]). HLA class I (A, B) was typed serologically, and class II (DRB1, DQB1) was typed by means of polymerase chain reaction-restriction fragment length polymorphism methods. The frequencies of DRB1*0405 and DQB1*0401 were higher in HCV-infected patients than in uninfected subjects. Among HCV-infected patients, the frequencies of B54, DRB1*0405, and DQB1*0401 were significantly higher in patients with CLD than in those carriers with persistently normal ALT values, whereas DRB1*1302, DRB1*1101, and DQB1*0604 were more frequently found in carriers with persistently normal ALT values than in patients with CLD. From extended haplotype analyses, in carriers with B54-DRB1*0405-DQB1*0401 haplotype, the risk of having liver injury was 13.2 times greater than in carriers with DRB1*0405-DQB1*0401 but without B54 [P = 0.0015, Haldane odds ratio = 13.2 (95% confidence interval, 1.7-103.8)]. In contrast, carriers with B44-DRB1*1302-DQB1*0604 had a 12.7-fold lower relative risk of developing liver injury compared to those with the haplotype containing B44 but not DRB1*1302-DQB1*0604 [P = 0.0076, Haldane odds ratio = 0.079 (0.009-0.695)]. Our findings show that extended haplotypes including class I B54 are closely associated with the progression of liver injury, whereas extended haplotypes including class II DRB1*1302-DQB1*0604 are associated with low hepatitis activity in chronic HCV infection.

Is severe cryptogenic chronic hepatitis similar to autoimmune hepatitis?

BACKGROUND/AIMS

It has been reported that severe cryptogenic chronic hepatitis may be a subgroup of autoimmune hepatitis. The aims of this study were to investigate the clinical features, liver function tests, human leukocyte antigens and response to immunosuppressive therapy in severe cryptogenic chronic hepatitis, and to compare the findings in such patients with those in patients with autoimmune hepatitis.

METHODS

History of alcohol and hepatotoxic drug intake, markers of metabolic liver disease, autoantibodies (antinuclear antibody, smooth muscle antibody, antibody to liver/kidney microsome type 1), and viral markers (HBsAg, HBV DNA, anti-HCV, HCV RNA) were negative in all severe cryptogenic chronic hepatitis patients (histological activity index > 9 and alanine aminotransferase level > 2 x normal). Fifteen cryptogenic patients (13 women; mean age, 33 +/- 16 years) and seven autoimmune patients (seven women; mean age, 28 +/- 3.9 years; five type 1; two type 2a) received prednisolone and azathioprine for at least 2 years.

RESULTS

Cryptogenic chronic hepatitis patients were similar to patients with autoimmune hepatitis with respect to age, sex, clinical presentation, liver function tests and Knodell scores at admission. HLA phenotype frequencies were comparable between cryptogenic and autoimmune groups: BW6 (77% vs. 100%), DR4 (62% vs. 57%), and HLA B8 (15% vs. 43%). The rates of complete and partial remissions achieved during therapy were 87% vs. 57% and 13% vs. 29%, respectively (p > 0.05).

CONCLUSIONS

The clinical, biochemical and HLA phenotypic features, and the responsiveness to immunosuppressive therapy in severe cryptogenic chronic hepatitis support the idea that it may be an autoimmune liver disease similar to autoimmune hepatitis.

Nonalcoholic steatohepatitis masquerading as autoimmune hepatitis

Nonalcoholic steatohepatitis is an increasingly recognized clinicopathologic condition. We report two cases of nonalcoholic steatohepatitis in middle-aged Japanese women whose clinical and laboratory data mimicked autoimmune hepatitis. Histologic findings of both cases were definite steatohepatitis with portal and pericellular fibrosis. Both patients' HLA-DR haplotypes were DR4 and DR2, which are frequently observed in Japanese patients with autoimmune hepatitis. Our cases suggest a diversity in the pathogenesis of nonalcoholic steatohepatitis.

MHC class II genes influence the susceptibility to chronic active hepatitis C

BACKGROUND/AIMS

Chronic hepatitis C develops in more than 70% of hepatitis C virus infected subjects. Viral factors influence the disease course, but little is known about the importance of host factors.

METHODS

Frequencies of major histocompatibility complex (MHC) class I and class II antigens were analyzed in two groups of patients with chronic hepatitis C virus infection and in control subjects. MHC class I typing was done by standard microlymphocytotoxicity assays. DRB1 and DQA1 genotyping was done by PCR based typing methods.

RESULTS

DRB1*0301 was found in 26 of 75 patients with chronic hepatitis C virus infection (34.7%) and in 12 of 101 control subjects (11.9%) (relative risk 3.9; p < 0.001). Homozygosity for this allele appeared to confer a stronger risk. In contrast, DRB1*1301 was detected in three subjects with persistent infection (4.0%) compared to 21 control subjects (20.8%) (relative risk 0.2; p < 0.008). This allele was linked with DQA1*0103, which was found in 10 patients (13.3%) compared to 34 control subjects (33.7%) (relative risk 0.31; p < 0.003). An even stronger protective effect was provided by the presence of DRB1*1301 and DQA1*0103 (relative risk 0.08; p < 0.005). These findings were confirmed in a second group of chronic hepatitis C virus infected patients.

CONCLUSIONS

The MHC class II allele DRB1*0301 appears to predispose to progression to chronic active hepatitis C, whereas the class II alleles DRB1*1301 and DQA1*0103 appear to provide protection against chronic active infection with hepatitis C virus.

Autoimmune hepatitis type 2 and hepatitis C virus infection: study of HLA antigens

BACKGROUND/AIMS

Markers for hepatitis C virus are often detectable in patients suffering chronic hepatitis with liver-kidney microsomal type 1 antibodies. Several authors have suggested that two subsets of those patients can be defined: a) hepatitis C virus negative and b) hepatitis C virus positive. The aim of this work was to further analyze the possible genetic association, HLA class I and II, in these two groups of patients.

METHODS

HLA was analyzed in 49 patients. Class I was studied using a standard lymphocytotoxicity test and in class II a reverse hybridization-based test for DRB1 typing and PCR-SSO for DQB1 typing were used. Sixty healthy Spanish subjects and 39 chronic hepatitis C subjects without anti-LKM1 antibodies were used as control groups for the "a" and "b" subsets, respectively.

RESULTS

No significant association was found with class I specificities in either group. DQB1 typing showed a very significant increase of DQ2 in the "a" group (93.3% vs. 48%; RR = 15; Pc = 0.0025), and DRB1 typing from the "b" group revealed a high association with DR7 (82.3% vs. 43.6%; RR = 6; Pc = 0.0086).

CONCLUSIONS

Our studies revealed a strong association with DQ2 for the "a" group and for the first time an extremely high association with DR7 antigen for the "b" subset. Hence it is possible to establish a different genetic profile in these two patient groups.

Absence of LKM-1 antibody reactivity in autoimmune and hepatitis-C-related chronic liver disease in Sweden. Swedish Internal Medicine Liver club

BACKGROUND

Type-2 autoimmune hepatitis is a subgroup of chronic hepatitis characterized by the presence of liver/kidney microsomal autoantibodies type 1 (LKM-1). A frequent association with chronic hepatitis C suggests that hepatitis virus might trigger autoimmune reactivity. LKM-1-positive chronic hepatitis is not uncommon in southern Europe but is rarely seen in the USA and the UK. The prevalence in Scandinavia is hitherto unknown.

METHODS

We used an automated prototype LKM-1 immunometry-based assay (IMx) to detect LKM-1 antibodies in sera from 350 Swedish patients with chronic liver diseases (100 with primary biliary cirrhosis, 80 with primary sclerosing cholangitis, 100 with hepatitis C, and 70 patients with various forms of chronic hepatitis, including 36 autoimmune cases), and from 17 children with autoimmune hepatitis. Sera reactive in the IMx assay were subjected to immunofluorescence testing.

RESULTS

No clearly LKM-reactive sera were detected. Serum samples from 29 patients were borderline reactive in the IMx assay but tested negative in the confirmatory immunofluorescence test. Positive tests in the former assay were likely caused by reactivity against microsomal antigens other than LKM-1/cytochrome P450IID6.

CONCLUSIONS

LKM-1-positive type-2 autoimmune hepatitis is very rare in Sweden. Furthermore, chronic hepatitis C did not trigger this type of autoimmune reactivity in our patients, probably owing to genetic insusceptibility.

Clinical hepatitis after transplantation of hepatitis C virus-positive kidneys: HLA-DR3 as a risk factor for the development of posttransplant hepatitis

BACKGROUND

Exposure to hepatitis C virus (HCV) and subsequent infection after renal transplantation lead to significant clinical hepatitis in approximately 50% of graft recipients.

METHODS

One hundred thirty-two consecutive renal allotransplant patients, who underwent transplantation of kidneys from HCV-positive cadaveric donors, were studied to investigate the relationship between donor and recipient HLA type and the risk of developing clinical hepatitis. Specific attention was directed toward the DR3 and DR4 alleles, as these had previously been associated with worse prognoses in autoimmune and viral hepatitis.

RESULTS

Overall, 42% of patients receiving kidneys from donors seropositive for HCV developed clinical hepatitis. This was unrelated to preoperative recipient HCV serum reactivity (P=0.65). Patients receiving kidneys from seropositive donors with HCV RNA as detected by PCR were more likely to develop hepatitis than those receiving kidneys from PCR-negative donors (56% vs. 11%; P=0.005). The presence of the DR3 allele was associated with a significant risk of clinical hepatitis (P=0.025); 80% of DR3-positive recipients (n=34) progressed to hepatitis compared with 42% of DR3-negative patients. No other recipient HLA type was significantly related to prognosis. All patients receiving a donated kidney that expressed the B41 allele developed hepatitis, compared with 55% of recipients of non-B41 grafts (P=0.039). No association between the development of clinical hepatitis and HLA compatibility was found.

CONCLUSIONS

These results suggest that both HLA type and viral presence as assayed by polymerase chain reaction, influence the risk of disease progression after transplantation of HCV-positive kidneys. Application of these associations may decrease the relative risk of a recipient contracting HCV hepatitis after cadaveric renal transplantation.

Immunogenetics in liver disease

Recent advances in molecular biology, in particular X-ray crystallography of the purified antigens A2 and DR1 and development of PCR-based HLA genotyping techniques, has revolutionized our understanding of immunogenetics and cellular immunology. The application of molecular immunogenetics has refined our understanding of HLA-encoded susceptibility and resistance to both autoimmune and chronic viral liver disease. Recent studies of autoimmune hepatitis (AIH), primary sclerosing cholangitis (PSC) and primary biliary cirrhosis (PBC) have identified substitutions of specific amino acid residues in the HLA DR beta-polypeptide (AIH and PSC) and DP beta-polypeptide (PBC) which may determine susceptibility to and resistance from disease. Although these models of HLA-encoded susceptibility in PSC and PBC are currently controversial, the model for AIH, based on lysine residue at DR beta 71 has recently been confirmed in an independent series. Data on chronic viral liver disease are less abundant, but a number of interesting observations are beginning to emerge. In the Gambia, resistance to chronic hepatitis B infection has been associated with the HLA DRB1*1302 allele, and in studies of patients with chronic hepatitis C virus infection DQA1*03 and DQB1*05 have been identified as a possible protective factors. Clarifying these HLA associations is not simply an academic pursuit; in addition to providing useful clues to the pathogenesis of these diseases, HLA associations may be important indicators of prognosis. In AIH, patients with the DRB1*0301-DRB3*0101 haplotype appear to have more severe disease than those with DRB1*0401, while in PSC, DRB3*0101 is associated with early onset of disease and DRB1*0401 may be a marker of more rapid disease progression. To date, our knowledge of immunogenetic susceptibility in liver disease is incomplete and further work is needed.

Cytochromes P450 and UDP-glucuronosyl-transferases as hepatocellular autoantigens

Autoantibodies directed against cytochromes P450 or UDP-glucuronosyl-transferases (UGTs) are detected in hepatitis of different aetiology: drug-induced hepatitis autoimmune hepatitis type 2, hepatitis associated with the autoimmune polyglandular syndrome type 1 (APS1) and virus-induced autoimmunity. Autoantibodies directed against cytochrome P450 2C9 are induced by tienilic acid, and anti-P450 1A2 autoantibodies by dihydralazine. Potential mechanisms involved may be metabolic activation of the drugs by cytochromes P450, adduct formation and circumvention of T cell tolerance. In contrast, little is known about the aetiology of autoimmune hepatitis type 2. This disease is characterized by marked female predominance, hypergammaglobulinaemia, circulating autoantibodies and benefit from immunosuppression. Patients with HLA B8, DR3 or DR4 are over-represented. The major target of autoimmunity in this disease is cytochrome P450 2D6. The autoantibodies were shown to be directed against at four short linear epitopes. In addition, about 10% of the patient sera form an additional autoantibody that detects a conformational epitope on UGTs of family 1. The phenomenon of virus-associated autoimmunity is found in chronic infections with hepatitis C and D. In chronic hepatitis C the major target of the autoantibodies again is cytochrome P450 2D6. Some linear and a high proportion of conformational epitopes are recognized. The LKM3 autoantibody is found in 13% of patients with chronic hepatitis D. The target proteins are UGTs of family 1 and, in some sera also, low titres of anto-antibodies directed against UGTs of family 2 are found. The epitopes detected are conformational. In contrast to the patients suffering from autoimmune hepatitis, patients with hepatitis as part of the autoimmune polyglandular syndrome type 1 recognize cytochrome P450 1A2. Interestingly, in APS1 patients also, autoantibodies directed against cytochromes P450 c21, P450 scc and P450 c17a may be detected; these autoantibodies are associated with adrenal and ovarian failure.

Antimitochondrial antibodies in patients with chronic hepatitis C

Although autoantibodies have been found in the serum of patients with chronic hepatitis C virus (HCV) there has been no convincing evidence of the presence of antimitochondrial antibodies, until now. Sera from 460 untreated patients with chronic hepatitis C were tested for antimitochondrial antibodies, using an indirect immunofluorescence technique; and if they tested positive for the antibodies (titer more than 1:50), they also were treated by Western blot analysis. Seven (1.5%) sera were positive. None of the patients had biological or histological evidence of primary biliary cirrhosis. Antimitochondrial antibodies recognized one of the oxo-dehydrogenase multienzyme complexe's epitopes by Western blot assay in three patients only. All seven patients were then treated by interferon alpha for six months. None showed exacerbation of liver disease during treatment. HCV-RNA disappeared from the serum in one patient who became negative for anti-M2 antibodies. The four patients who did not respond to interferon-alpha therapy, and the two who relapsed after treatment withdrawal, had sustained positive antimitochondrial antibodies. These data suggest that: 1) antimitochondrial antibodies present in patients with chronic hepatitis C do not always recognize the same epitopes as in primary biliary cirrhosis; 2) these antibodies may disappear after eradication of HCV, suggesting that the production of antimitochondrial antibodies is linked to the presence of the virus and 3) the clinical and biological course of chronic hepatitis C, and the response to interferon-alpha therapy, does not seem to be different in patients who are positive for antimitochondrial antibodies.

Genetic predispositions for immunological features in chronic liver diseases other than autoimmune hepatitis

BACKGROUND/AIMS

Human leukocyte antigens DR3 and DR4 influence susceptibility for type 1 autoimmune hepatitis and affect its immunological manifestations. We aimed to determine if autoimmune features in patients with chronic liver diseases other than autoimmune hepatitis are associated with these same antigens.

METHODS

One hundred and seventy-eight patients were evaluated. Class II typing was performed by restriction fragment length polymorphism in all patients and 80 normal subjects.

RESULTS

One or more autoantibodies, including antinuclear antibodies (28%), smooth muscle antibodies (8%), thyroid antibodies (18%) and antimitochondrial antibodies (13%), were found in 92 patients (52%). Concurrent clinical diseases of an immunological nature were recognized in 53 patients (30%). Patients with antinuclear antibodies had a higher frequency of the A1-B8-DR3 haplotype than patients without these antibodies (27% versus 12%, p = 0.04) and patients with concurrent immunological diseases had a higher frequency of HLA DR4 than patients without this antigen (51% versus 26%, p = 0.003). Patients with antinuclear antibodies were more commonly DR3 positive than normals (35% versus 16%, p = 0.03) and patients with concurrent immunological diseases were more commonly HLA DR4 positive than normals (51% versus 30%, p = 0.02).

CONCLUSIONS

We conclude that the clinical expression of antinuclear antibodies is associated with the A1-B8-DR3 haplotype and the presence of concurrent immunological diseases is related to the DR4 antigen. These clinical manifestations have a genetic basis that is not disease-specific.