Pathogens and autoimmune hepatitis

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

Diagnostic criteria of autoimmune hepatitis

Autoimmune hepatitis (AIH) is a chronic immune-mediated liver disorder characterised by female preponderance, elevated transaminase and immunoglobulin G levels, seropositivity for autoantibodies and interface hepatitis. Presentation is highly variable, therefore AIH should be considered during the diagnostic workup of any increase in liver enzyme levels. A set of inclusion and exclusion criteria for the diagnosis of AIH have been established by the International Autoimmune Hepatitis Group (IAIHG). There are two main types of AIH: type 1, positive for anti-nuclear (ANA) and/or anti-smooth muscle antibodies (SMAs) and type 2, defined by the presence of anti-liver kidney microsomal antibody type 1 (LKM-1) and/or anti-liver cytosol type 1 (LC-1) autoantibodies. The central role of autoantibodies in the diagnosis of AIH has led the IAIHG to produce a consensus statement detailing appropriate and effective methods for their detection. Autoantibodies should be tested by indirect immunofluorescence at an initial dilution of 1/40 in adults and 1/10 in children on a freshly prepared rodent substrate that includes kidney, liver and stomach sections to allow for the simultaneous detection of all reactivities relevant to AIH. Anti-LKM-1 is often confused with anti-mitochondrial antibody (AMA) if rodent kidney is used as the sole immunofluorescence substrate. The identification of the molecular targets of anti-LKM-1 and AMA has led to the establishment of immuno-assays based on the use of the recombinant or purified autoantigens. Perinuclear anti-nuclear neutrophil antibody (p-ANNA) is an additional marker of AIH-1; anti soluble liver antigen (SLA) antibodies are specific for autoimmune liver disease, can be present in AIH-1 and AIH-2 and are associated with a more severe clinical course. Anti-SLA are detectable by ELISA or radio-immuno-assays, but not by immunofluorescence. AIH is exquisitely responsive to immunosuppressive treatment, which should be instituted promptly to prevent rapid deterioration and promote remission and long-term survival.     

Diagnostic approach to autoimmune hepatitis

Introduction: Autoimmune hepatitis (AIH) is a chronic inflammatory liver disease which, if left without treatment, can evolve into cirrhosis and possibly liver failure. The diagnosis of AIH is hampered by the lack of specific and reliable markers of the disease and a number of clinical, biochemical, immunological, histological and genetic factors should be considered to reach a confident diagnosis

Areas covered: Clinical expression of AIH, histological features, serological and genetic profiles, differential diagnosis, overlap with other autoimmune liver diseases, assessed on the basis of personal experience and review of published literature in the last 10 years through a systematic Medline search (keywords: autoimmune hepatitis, diagnosis)

Expert commentary: Notwithstanding numerous efforts to identify simple and reliable markers of the disease, the diagnosis of AIH is still based on the combination of histological, immunological and biochemical features and often can represent a real challenge for the hepatologist.     

Animal models for autoimmune hepatitis

The liver is the target of adverse immune reactions in three putative autoimmune diseases: autoimmune hepatitis (AIH), primary biliary cirrhosis (PBC) and primary sclerosing cholangitis (PSC). These three diseases can be distinguished by clinical, histological, and immunological features. However, especially on the level of specific antibody formation an overlap can occur, which sometimes complicates diagnosis. In this review, we will concentrate on autoimmune hepatitis and the current state of animal models for this severe disease. AIH is characterized by the presence of interface hepatitis and portal plasma cell infiltration, hypergammaglobulinemia, and autoantibodies. The hallmark of type 2 AIH is the generation of autoantibodies of the LKM-1 type. The major target of these antibodies is the cytochrome P450 isoform 2D6 (CYP2D6). In the past several attempts have been made to develop a reliable animal model that reflects the persistent hepatic destruction that occurs in human AIH. However, most models were only successful in causing a transient form of hepatic damage and often used rather complex ways of disease induction.     

The spectrum of chronic autoimmune hepatitis

Autoimmune hepatitis (AIH) is characterised by the presence of periportal hepatitis coupled with the presence of autoantibodies in the serum. We report our experience with 10 cases (females--8, males--2) who presented to the rheumatology clinic with either articular or extra-articular manifestations. Three patients (1 SLE, 1 Sjogren's and 1 RA), satisfied the criteria for an underlying rheumatic disease (secondary AIH) while, others had primary AIH. Median duration of hepatic involvement was 6 months and the varied presentations were noted. Articular disease ranged from arthralgias, palindromic arthritis to persistent non-erosive/non-deforming arthritis (Jaccoud's arthritis). Autoimmune thrombocytopenia was seen in 2 and autoimmune hypo and hyperthyroidism were seen in 3 patients each. Anti-nuclear antibody was positive in 9/10 (6 with speckled pattern and 3 with homogenous pattern) and anti-mitochondrial antibodies were positive in three. Hepatitis C virus (HCV) markers were positive in 1, who probably had viral hepatitis with dominant autoimmune features. All have been started on steroids (5 patients--1 mg/kg dose, 1 patient--0.5 mg/kg dose and 3 patients--0.25 mg/kg dose). The HCV positive patient was on a low dose steroid (0.25 mg/kg) and interferron treatment was contemplated before she was lost to follow up. Four patients are also on azathioprine in the dose of 2 mg/kg/day. Of the 6 patients who are under regular follow up, the liver parameters have normalised in 5 and one showed hypoalbuminaemia with normal enzyme levels at the last follow up.     

Cutting edge issues in autoimmune hepatitis

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

Tryptophan-kynurenine profile in pediatric autoimmune hepatitis

Immunologic Research - The impairment of regulatory T cells (Tregs) is a characteristic feature of autoimmune hepatitis (AIH), and the degradation of tryptophan (Trp) to kynurenine (Kyn), by gamma...     

氯喹可加重Con A诱导的自身免疫性肝损伤

氯喹(chloroquine,CQ)可抑制免疫反应,偶用于类风湿性关节炎、系统性红斑狼疮等自身免疫性疾病的治疗,但氯喹对自身免疫性肝炎的影响目前尚不明确。本研究拟探讨CQ对小鼠自身免疫性肝损伤的影响及可能机制。小鼠尾静脉注射Con A建立小鼠肝损伤模型,1h后,腹腔注射CQ或等体积PBS。观察小鼠生存状况,在不同时间点收集血清和肝组织,采用赖氏法检测血清谷丙转氨酶(GPT)水平;ELISA方法检测血清细胞因子IFN-γ及TNF-α含量;HE染色观察肝脏病理损伤情况;免疫印迹检测小鼠肝脏自噬水平指标LC3-Ⅱ和P62。结果显示,Con A+CQ组小鼠血清中GPT水平显著高于Con A组,且病理切片染色显示Con A+CQ组肝脏损伤较Con A组更严重;Con A+CQ注射组小鼠的存活率明显低于仅注射Con A组(P0.0001);Con A+CQ组小鼠血清中炎性细胞因子IFN-γ和TNF-α的分泌高于Con A组;CQ可抑制Con A刺激诱导的小鼠肝脏自噬水平升高。氯喹可加重Con A诱导的自身免疫性肝损伤,其机制可能是通过抑制肝脏自噬水平从而加剧小鼠肝脏损伤。     

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.     

Current status of autoimmune hepatitis in Japan

Autoimmune hepatitis (AIH) is a chronic and progressive disease characterized by histological interface hepatitis, hypergammaglobulinemia, and circulating autoantibodies. Multiple factors, including molecular mimicry, a genetic background including major histocompatibility complex class II, and defective function of regulatory T-cells, are involved in the pathogenesis. The diagnosis is made based on the scoring system of the International Autoimmune Hepatitis Group, the sensitivity and specificity of which are > 90%, respectively. AIH is classified into 3 sub-types based on the profiles of circulating autoantibodies: anti-nuclear antibody and/or smooth muscle antibody-positive (type 1), anti-liver-kidney microsomal antibody-positive (type 2), and anti-soluble liver antigen/liver-pancreas antigen antibody- positive (type 3). Recently, however, the number of atypical cases lacking the usual features has increased--for example, patients with acute-onset or fulminant-type AIH, autoantibody-negative patients, male patients, and patients with bile duct injury--and thus the clinical features of AIH have been diversified. AIH is responsive to immunosuppressive treatment in most cases; however, relapse occurs in more than 80% of patients within 1 year after immunosuppressive treatment withdrawal. The 10-year survival rate and the 10-year hepatocellular carcinoma-free rate are > 90%, respectively, indicating that some patients reach liver failure or develop hepatocellular carcinoma. To improve the prognosis of these patients, persistent normalization of transaminase is required.     

Clinical significance of autoantibodies in autoimmune hepatitis

The accurate diagnosis and classification of autoimmune hepatitis (AIH) rely upon the detection of characteristic autoantibodies. Positivity for anti-nuclear (ANA) and/or anti-smooth muscle (SMA) autoantibodies defines AIH type 1 (AIH-1), whereas anti-liver kidney microsomal type 1 (anti-LKM1) and/or anti-liver cytosol type 1 (anti-LC1) define AIH type 2 (AIH-2). ANA and SMA, and less commonly anti-LKM1, have also been detected in de-novo autoimmune hepatitis developing after liver transplantation, a condition that may affect patients transplanted for non-autoimmune liver disease. The diagnostic autoantibodies associated with AIH-1 are also detected in the paediatric AIH/sclerosing cholangitis overlap syndrome, referred to as autoimmune sclerosing cholangitis (ASC). ASC, like adult primary sclerosing cholangitis, is often associated with atypical perinuclear anti-neutrophil cytoplasmic autoantibodies (p-ANCA), although p-ANCA are also detected in other autoimmune liver diseases. These associations highlight the necessity for simple and prompt diagnostic autoantibody testing, and the requirement for the accurate interpretation of the results of the tests in the clinical context. Fine-mapping of antigenic autoantibody targets has facilitated the development of rapid molecular assays that have the potential to revolutionise the field if properly standardised and when used in combination with classical immunofluorescence. Despite their diagnostic significance, the pathogenic role of the various autoantibodies and the mechanisms by which they can potentially inflict damage onto the liver cell remain a topic for further research.     

Minocycline as a cause of drug-induced autoimmune hepatitis. Report of four cases and comparison with autoimmune hepatitis

We describe the clinical and liver biopsy morphologic features for 4 patients with minocycline-induced autoimmune hepatitis (group 1). We compared the serum laboratory values and liver biopsy findings from group 1 with those from 10 patients with sporadic autoimmune hepatitis (group 2). All patients in group 1 had positive serum antinuclear antibody titers, but none had positive serum anti-smooth muscle antibody titers. The morphologic findings of group 1 biopsies were those of autoimmune hepatitis in all 4 patients. In addition, 1 of these biopsy specimens also had scattered single eosinophils, unlike autoimmune hepatitis. The mean histologic activity index scores for patients in groups 1 and 2, respectively, were 6.7 and 5.4. No patients in group 1 had marked bridging fibrosis or cirrhosis, compared with 4 of 10 patients in group 2. Minocycline-induced autoimmune hepatitis is usually identical to sporadic autoimmune hepatitis. The absence of eosinophils does not exclude the possibility of a minocycline cause. In the absence of clinical or morphologic differences, a recent ingestion of minocycline should be excluded before the diagnosis of sporadic autoimmune hepatitis is established. Whether the drug is unmasking latent autoimmune hepatitis is unclear.     

Evolving paradigm of treatment for autoimmune hepatitis

Introduction: Current medications for autoimmune hepatitis have broad anti-inflammatory and immunosuppressive actions, and their effects are short-lived and inconsistent. The goals of this review were to describe the actions and shortcomings of these medications, indicate the key pathogenic mechanisms that might be targeted by site-directed interventions, and present the pivotal studies supporting development of these alternative agents.

Areas covered: Abstracts cited in PubMed from April 1964 to February 2017 were identified using the search words ‘treatment of autoimmune hepatitis’. A secondary bibliography was developed from the references cited in selected articles, and additional searches were performed to expand the concepts developed in these articles. The number of abstracts reviewed exceeded 1000, and the number of full-length articles reviewed exceeded 100.

Expert commentary: Molecular, cellular, and pharmacological interventions that target key pathogenic pathways promise to change the current paradigm of treatment for autoimmune hepatitis. Interventions affecting lymphocyte activation, lymphocyte differentiation, effector cell migration, hepatocyte apoptosis, oxidative-nitrosative stress, fibrogenesis, and intestinal dysbiosis promise to emerge as supplemental or replacement therapies. The intestinal microbiome constitutes the next investigational frontier that may influence future management strategies. Unwanted and unexpected consequences of manipulating these homeostatic pathways constitute the major unmeasured risks of these evolving regimens.     

Serum soluble HLA-DR antigens in autoimmune hepatitis

To investigate the significance of HLA-class II, especially DR antigens, in autoimmune hepatitis (AIH), the serum concentrations of soluble HLA-DR antigen (sDR) were measured in 16 patients with AIH. The expression of HLA-DR antigens in the liver tissues of AIH patients was also studied by immunohistochemistry. AIH at diagnosis showed markedly higher serum sDR levels than controls, in which the liver tissues exhibited positive staining of HLA-DR antigens. Seven patients received corticosteroid therapy, in whom the serum sHLA-DR concentration was reduced dramatically from activated to remission stage. In sequentially follow-up cases, sDR correlated well with the disease activity, and also with the change of surface DR expression in the liver. A single major band with a molecular size of 60 kDa was detected, both in patient's sera and in normal control sera, by Western blotting. In conclusions, serum sHLA-DR level could be a marker reflecting immunological activity of the disease.     

实验性自身免疫性肝炎的研究

本文通过 S-100肝抗原多次免疫同种 C57BL/6小鼠后,成功地建立了实验性自身免疫性肝炎的动物模型,并在此基础上进一步探讨了过继输注致敏脾淋巴细胞给正常同种小鼠后自身免疫性肝炎的发生情况.结果表明,导致过继输注后自身免疫性肝炎主要为 T 淋巴细胞,揭示了 T 淋巴细胞在自身免疫性肝炎发病中起着重要作用.另外,本文还就免疫抑制剂环孢素 A 对实验性自身免疫性肝炎的防治作用进行了探讨.组织学检查结果表明预防和治疗用药时均能减轻肝脏病理变化和/或减少自身免疫性肝炎的发生率.为临床治疗自身免疫性肝炎提供了实验室依据.