Role of liver biopsy in autoimmune liver disease

This article will review histological aspects of three chronic liver diseases – autoimmune hepatitis (AIH), primary biliary cirrhosis (PBC) and primary sclerosing cholangitis (PSC) – in which autoimmune mechanisms are thought to be involved. The changing role of liver biopsy in the diagnosis and management of patients with autoimmune liver disease will also be discussed. In the case of autoimmune hepatitis, histological assessments remain important in establishing a diagnosis, identifying prognostic features and monitoring therapeutic responses. By contrast, for many patients with PBC and PSC a diagnosis can now be made on the basis of biochemical, serological and/or radiological findings alone and histological confirmation may not be required. Liver biopsy can still be used to assess disease severity in such cases and remains important in establishing a diagnosis in patients with atypical features (e.g. AMA-negative PBC or the small-duct variant of PSC). Liver biopsy is also increasingly used in the assessment of patients suspected to have “overlap syndromes” involving AIH and PBC or PSC.     

Antilactoferrin antibodies in autoimmune liver disease

Antilactoferrin antibodies have been reported in patients with several autoimmune disorders, including primary biliary cirrhosis, autoimmune hepatitis and autoimmune cholangitis. We investigated the prevalence and the clinical significance of such autoreactivity in patients with autoimmune and viral chronic liver disease. Sera from 39 patients with autoimmune hepatitis, 51 with primary biliary cirrhosis, 17 with autoimmune cholangitis, 24 with primary sclerosing cholangitis and 28 with HCV-related chronic hepatitis were studied. Positivity for antilactoferrin antibodies was evaluated by Western immunoblotting with purified human lactoferrin. Antilactoferrin antibodies were detected more often in autoimmune liver disorders (25% autoimmune hepatitis, 25% primary biliary cirrhosis, 35% autoimmune cholangitis, 29% primary sclerosing cholangitis) than in HCV-related chronic hepatitis (3.5%, P < 0.02 versus all). Positivity for antilactoferrin antibodies was not associated with a particular clinical or biochemical profile of the underlying liver disease. No correlation was observed between antilactoferrin reactivity and perinuclear antineutrophil cytoplasmic antibodies. Antilactoferrin antibodies are present significantly more often in autoimmune than in viral liver disorders, but they cannot be considered the serological marker of a specific autoimmune liver disease.     

自身免疫性肝病的病理诊断

自身免疫性肝病是指一组以肝脏病理损害和肝脏功能异常为主要表现的自身免疫性疾病,主要包括自身免疫性肝炎（autoimmune hepatitis）、原发性胆汁性肝硬化（primary biliary cirrhosis）、原发性硬化性胆管炎（primary sclerosing cholangitis）三大类。这三种疾病尽管在组织病理学方面均有各自的特点,但由于这些疾病病理表现常与其他肝脏疾病重叠,患者病变也常常表现不典型,因此往往要密切联系临床表现、血液生化及自身抗体检测结果等才能作出正确诊断。[第一段]     

Immunoglobulin classes in biopsies of autoimmune liver disease

The immunological isotypes of plasma cell infiltrates in a series of consecutive liver biopsies from patients with chronic active hepatitis (CAH) and primary biliary cirrhosis (PBC) were determined immunohistochemically. The plasma cell infiltrate was more pronounced in PBC than in CAH. IgA and IgG isotypes predominated in CAH, and IgM and IgG in PBC. The expected predominance of kappa light chains was observed in every biopsy in PBC. However, in 8/14 CAH biopsies the plasma cells were predominantly lambda isotype. Lambda predominance was significantly associated with the presence of serum autoantibodies. These findings would suggest that different mechanisms operate in the pathogenesis of these two autoimmune liver diseases.     

Role of NKT cells in autoimmune liver disease

The three main broad categories of autoimmune liver disease are autoimmune hepatitis (AIH), primary biliary cirrhosis (PBC), and primary sclerosing cholangitis (PSC). The etiologies of these diseases are still incompletely understood, but seem to involve a combination of immune, genetic and environmental factors. Although each of these diseases has relatively distinct clinical, serologic and histological profiles, all of them share common pathways of immune-mediated liver injury. The development of autoimmune liver diseases is thought to be due to an imbalance of proinflammatory and anti-inflammatory immune responses within the liver, with proinflammatory immune responses being upregulated and anti-inflammatory ones downregulated. The available evidence, suggest that during autoimmune responses within the liver, “self” antigens are presented by antigen presenting cells (APCs) which then activate, directly and/or indirectly, NKT cells and other innate immune cells within the liver. Importantly, the hepatic innate immune system plays an increasingly recognized role in the development and propagation of autoimmune liver injury. NKT cells predominantly reside in the liver sinusoids, and through their ability to rapidly produce a wide variety of cytokines (e.g. Th1, TH2, Th17 cytokine patterns), are a critical checkpoint that bridges innate and adaptive immune responses. Specifically, activated NKT cells are capable of transactivating other innate and adaptive immune cells within the liver to amplify and regulate subsequent immune responses within the liver. It has been hypothesized that NKT cells in the setting of autoimmune liver disease can play diverse roles, including driving both anti-inflammatory and proinflammatory responses, as well as regulating the hepatic recruitment of other types of immunoregulatory cells, including regulatory T cells.     

Antibodies to nuclear lamins in autoimmune liver disease

Antibodies to nuclear lamins were detected in sera of patients with autoimmune liver disease. In indirect immunofluorescence tests, these sera revealed staining of the nuclear periphery. Using isolated nuclei, nuclear matrices, nuclear lamina-pore complexes, and chromatographically purified lamins as antigen source, the nuclear lamins A, B, and C were identified as reactive antigens in immunoblotting experiments. The lamins were also identified by 2-D gel electrophoresis. Antibodies to nuclear lamins occurred in 12 of 16 cases of active lupoid hepatitis, but not in 35 patients with the disease in remission. However, only 3 of 37 sera of patients with primary biliary cirrhosis contained anti-lamin antibodies. Autoimmune liver disease sera reacted preferentially with lamins A/C and less frequently with lamin B or lamins A/B/C.     

Feasibility of computer evaluation of the histopathologic findings in human skeletal muscle disease.

Optical Fourier methods of image processing coupled with mutual information analysis were applied to the separation of human muscle specimens into four diagnostic classes. This process allowed rapid, relatively inexpensive data acquisition, reduction, and classification. The accuracy of the method when compared to that of experienced surgical pathologists is acceptable. Difficulties arise when material outside of the previous experience of the computer is presented.     

自身免疫性肝病患者自身抗体检测及临床意义

目的 探讨自身免疫性肝病患者血清中出现的自身抗体等免疫学指标及临床意义.方法 对3 500例肝功能反复异常的患者采用间接免疫荧光法检测抗核抗体(ANA)、抗平滑肌抗体(SMA)、抗线粒体抗体(AMA).并对AMAM2型及抗可溶性肝抗原/肝胰抗原(抗SLA/LP)、抗肝肾微粒体抗体Ⅰ型(抗LKM-1)和抗肝特异性胞浆抗原Ⅰ型抗体(抗LC-1)等肝脏疾病相关的自身抗体进行检测.结果 3 500例患者中,自身免疫性肝炎患者29例,检出率为0.83%,其中符合Ⅰ型、Ⅱ型、Ⅲ型自身免疫性肝炎的比例占72.4%、10.3%和17.2%.原发性胆汁性肝硬化(PBC)患者58例,检出率为1.65%,血清中AMAM2型抗体阳性率为93.1%,其中19例AMAM2阳性患者进行肝穿病理检查时12例(63.7%)患者病理提示符合PBC诊断.结论 每种自身免疫性肝病都具有特征性自身抗体谱,注重自身抗体检测对明确诊断及鉴别诊断自身免疫性肝病具有重要的临床意义.     

The role of complement activation in autoimmune liver disease

IntroductionThe complement system, an essential part of the innate immune system, is involved in various autoimmune diseases. Activation of the complement system by autoantibodies results in immune activation and tissue damage. At the moment little is known about the role of the complement system in autoimmune liver disease, including primary biliary cholangitis (PBC), primary sclerosing cholangitis (PSC) and autoimmune hepatitis (AIH). Since inhibition of the complement system is currently being tested in several autoimmune diseases as a therapeutic option, its role in autoimmune liver disease requires further clarification.MethodsA review of the literature was performed on studies investigating complement activation in PBC, PSC and AIH. Since data on AIH were lacking immunohistochemical staining for IgG, C1q, C3d, C4d and C5b9 was performed on liver tissue of nine AIH patients, two healthy controls and one positive control (acute liver failure caused by paracetamol intoxication).ResultsImmunohistochemical analysis in AIH revealed increased production of C3 and C4 by hepatocytes. Despite a strong staining for IgG in the immune infiltrate in AIH, C3d, C4d and C5b9 deposition was only present in one AIH patient and the deposition was restricted to the interface between portal tracts and liver parenchyma. No deposition was found in all other AIH patients or healthy controls.Literature review showed raised plasma C3 and C4 levels in AIH, PBC and PSC patients compared to healthy controls. For PBC and PSC no complement depositions at the bile ducts were reported.Conclusion and discussionAlthough complement is involved in various autoimmune diseases, the role of complement in autoimmune liver disease seems limited. Therefore it is unlikely that complement inhibition will become a novel treatment option for these diseases.     

The histopathologic spectrum in Mycobacterium marinum infection

Review of nine culture-positive cases of Mycobacterium marinum infection revealed a broad range in the histopathologic features of lesions produced by this organism. Four synovial lesions and five cutaneous infections were observed. A range of inflammatory changes were seen in both synovial and skin lesions, varying from mostly acute inflammation with suppuration to a more chronic process with numerous, well-formed granulomas. Organisms were observed in the biopsy sections of only one of the nine cases. Therefore, culture of the biopsy tissue at 30 degrees C is crucial in establishing the diagnosis. These cases emphasize the importance of considering mycobacterial infection and performing cultures even when granulomatous changes in the synovium or skin are subtle.     

Towards the pathogenesis of autoimmune liver disease.

There have been recent improvements in the clinical understanding and definition of the major types of autoimmune liver disease. However, still lacking is knowledge of their prevalence and pathogenesis. Three areas of study are in progress in our laboratory. First, in type 1 autoimmune hepatitis, the search continues to identify a liver/disease-specific autoantigenic reactant. Using hepatocyte membrane preparations, immunoblotting has underlined the problem of distinguishing, among multiple reactants, those that may be causally rather than consequentially related to hepatocellular damage. Second, in primary biliary cirrhosis (PBC), the need for population screening to ascertain prevalence and detect preclinical cases can be met by a rapid automated procedure for detection, by specific enzyme inhibition in microtitre wells, of antibody (anti-M2) to the pyruvate dehydrogenase complex E2 subunit (PDC-E2). Third, the structure of the conformational epitope within the inner lipoyl domain of PDC-E2 is being investigated by screening random phage-displayed peptide libraries using PBC sera. This has yielded phage clones in which the sequence of the peptide insert portrays the structure of this epitope, as judged by clustering of PBC-derived sequences to particular branches of a guide-tree that shows relatedness of peptides, and by reactivity of selected phage clones with anti-PDC-E2. Thus phage display identifies a peptide 'mimotope' of the antibody epitope in the inner lipoyl domain of PDC-E2.     

The role of natural killer cells in autoimmune liver disease: A comprehensive review

Natural Killer (NK) cells are important players of the innate arm of the immune system and provide an early defense against pathogens and tumor-transformed cells. Peripheral blood NK (PB-NK) cells were first identified because of their ability to spontaneously kill tumor-cell targets in vitro without the need for specific antigen priming, which is the reason that they were named ‘natural killer’ cells. The characterization of NK cells in human tissues and body organs represented another important step forward to better understand their physiology and physiopathology. In this regard, many reports revealed over the past decade a differential anatomic distribution of NK cell subsets in several sites such as the intestine, lung, cervix, placenta and liver as well as in secondary lymphoid organs such as spleen, lymph nodes and tonsils. Among all these tissues, the liver is certainly unique as its parenchyma contains an unusually high number of infiltrating immune cells with 30–50% of total lymphocytes being NK cells. Given the constant liver intake of non-self antigens from the gastrointestinal tract via the portal vein, hepatic NK (H-NK) cells must retain a certain degree of tolerance in the context of their immune-surveillance against dangers to the host. Indeed, the breakdown of the tolerogenic state of the liver-associated immune system has been shown to induce autoimmunity. However, the role of NK cells during the course of autoimmune liver diseases is still being debated mainly because a complete characterization of H-NK cells normally resident in healthy human liver has not yet been fully disclosed. Furthermore, the differences in phenotype and functions between human and mouse H-NK cells often preclude translation of results obtained from murine models into experimental approaches to be performed in humans. Here, we provide an extensive characterization of the phenotype of H-NK cells physiologically resident in the human liver by both mentioning data available in literature and including a set of original results recently developed in our laboratory. We then review our current knowledge in regard to the contribution of H-NK cells in regulating local immune homeostasis and tolerance as well as in inducing the development of liver autoimmunity.     

Pulmonary histoplasmosis: unusual histopathologic findings

Four patients with clinical diagnosis of interstitial lung disease (ILD) are presented. In these patients, lung biopsies revealed bronchocentric granulomatosis (BG), pulmonary alveolar proteinosis (PAP), diffuse alveolar damage (DAD), and in one biopsy, the clinical manifestations suggested tuberculous primo-infection with systemic dissemination. Three patients died without diagnosis. In all four cases, specific histological stains found Histoplasma capsulatum. Histoplasmosis may mimic other infectious or non-infectious pulmonary diseases, such as interstitial and granulomatous pulmonary disease. Therefore, the absolute need for identification of the organism by culture or special stains cannot be over-emphasized and may lead to a proper mycological diagnosis. This highlights the importance of differential diagnosis with systemic infectious diseases, especially in areas where deep-seated mycosis are endemic.     

抗Ro-52抗体在自身免疫性肝病中的检测

目的 探讨抗Ro-52抗体对自身免疫性肝病(autoimmune liver disease,AILD)的临床意义.方法 对采用免疫印迹法检测抗Ro-52抗体的115例AILD患者的临床资料进行回顾性分析,比较抗Ro-52阳性和阴性MLD患者肝功和免疫学指标,对可能有相关性的血清学指标进行诊断试验一致性评价.结果 抗Ro-52抗体在自身免疫性肝炎(autoimmune hepatitis,AIH)(37例)、原发性胆汁性肝硬化(primary biliary cirrhosis,PBC)(57例)、MH/PBC重叠综合征组(21例)的阳性率分别为32.43%、24.56%、33.33%,差异无统计学意义(x2=0.949,P>0.05).抗可溶性肝抗原/肝胰抗原抗体(anti-soluble liver antigen/liver-pancreas,anti-SLA/LP)在抗Ro-52阳性AIH组频率(58.33%)高于阴性组(16.00%)(x2=6.955,P<0.05),抗SLA/LP抗体在抗R0-52阳性AIH/PBC重叠综合征组频率(85.71%)高于阴性组(28.57%)(x2=6.109,P<0.05).抗Ro-52抗体和抗SLA/LP抗体结果有一致性(κ=0.466,P<0.05).AIH/PBC重叠综合征组抗Ro-52阳性患者IgG水平高于阴性患者(t=2.508,P<0.05).结论 抗Ro-52抗体在AIH、PBC和MH/PBC重叠综合征中的分布没有差别;抗Ro-52抗体与抗SLA/LP抗体检测结果有一致性;抗Ro-52抗体阳性MH/PBC重叠综合征患者IgG水平高于抗体阴性者.     

Significance of extractable nuclear antigens in childhood autoimmune liver disease.

The relative virulence of different isolates of Mycobacterium avium has been linked to their capacity to trigger the secretion of TNF from the macrophages they infect. Smooth opaque (SmOp) variants of Myco. avium have been shown to trigger higher expression of TNF-alpha by macrophages in vitro than the smooth transparent (SmTr) variants. To analyse the role of TNF in resistance to infection by Myco. avium, we studied the infection by two different morphotypes of strain 2.151 of Myco. avium both in vitro and in vivo in the presence or absence of neutralizing antibodies to TNF. No effects were found in vitro regarding the growth of either isolate of Myco. avium. In vivo, only the virulent SmTr morphotype showed enhanced growth in the presence of the neutralizing antibodies. This enhancement occurred relatively late when priming for TNF secretion in vivo was evident. Among four isolates of Myco. avium, three virulent ones induced a marked priming for TNF release and one avirulent strain did not. Mycobacterium tuberculosis H37Ra, which is very active in inducing TNF release due to its lipoarabinomannan moiety, was used to compare with the previous results. The growth of H37Ra in macrophages was increased in vitro by the neutralization of TNF and neutralization of either TNF and/or interferon-gamma (IFN-gamma) enhanced the in vivo proliferation of this microbe in the spleen and liver of infected animals, whereas only the combination of both anti-TNF and anti-IFN-gamma enhanced bacterial proliferation in the lung. We conclude that resistance to the avirulent strains of Myco. avium did not involve TNF, but rather antimicrobial mechanisms expressed constitutively in the mononuclear phagocytes. In contrast, TNF plays an important role in the control of Myco. tuberculosis H37Ra infection.     

自身免疫性肝病患者血清GP73变化特征

目的 明确自身免疫性肝病患者血清GP73的水平特征及可能的临床意义.方法 本研究共观察了健康体检、慢性乙型肝炎患者,以及自身免疫性肝病患者各80例的血清GP73水平.结果 与健康对照人群的血清GP73水平（35.84±11.8） ng/ml相比,自身免疫性肝病患者（112.3±72.55） ng/ml显著升高,也显著高于慢性乙型肝炎患者（86.44±60.69） ng/ml.但自身免疫性肝炎（107.4±90.6）ng/ml,原发性胆汁淤积性肝硬化（89.0±45.38） ng/ml,以及原发性硬化性胆管炎（113.3±50.87） ng/ml患者之间并无显著性差异,但均低于重叠综合症的患者（153.3±86.89ng/ml）.以健康体检人群为参照人群,以61.35 ng/ml为cut-off值,GP73诊断自身免疫性肝病的特异性和敏感性分别为75.0％和97.53％.ROC分析曲线下面积为为0.93（95％ CI：0.89-0.97）.结论 自身免疫性肝病患者血清GP73显著高于健康对照人群,尤其是那些重叠综合征的患者.对于GP73升高的患者,除考虑病毒性肝炎,肝癌外,也应该考虑自身性免疫性肝病的可能.