Mixed cryoglobulinemia

Primary biliary cirrhosis (PBC) is a chronic and slowly progressive cholestatic liver disease of autoimmune etiology characterized by injury of the intrahepatic bile ducts that may eventually lead to liver failure. Affected individuals are usually in their fifth to seventh decades of life at time of diagnosis, and 90% are women. Annual incidence is estimated between 0.7 and 49 cases per million-population and prevalence between 6.7 and 940 cases per million-population (depending on age and sex). The majority of patients are asymptomatic at diagnosis, however, some patients present with symptoms of fatigue and/or pruritus. Patients may even present with ascites, hepatic encephalopathy and/or esophageal variceal hemorrhage. PBC is associated with other autoimmune diseases such as Sjogren's syndrome, scleroderma, Raynaud's phenomenon and CREST syndrome and is regarded as an organ specific autoimmune disease. Genetic susceptibility as a predisposing factor for PBC has been suggested. Environmental factors may have potential causative role (infection, chemicals, smoking). Diagnosis is based on a combination of clinical features, abnormal liver biochemical pattern in a cholestatic picture persisting for more than six months and presence of detectable antimitochondrial antibodies (AMA) in serum. All AMA negative patients with cholestatic liver disease should be carefully evaluated with cholangiography and liver biopsy. Ursodeoxycholic acid (UDCA) is the only currently known medication that can slow the disease progression. Patients, particularly those who start UDCA treatment at early-stage disease and who respond in terms of improvement of the liver biochemistry, have a good prognosis. Liver transplantation is usually an option for patients with liver failure and the outcome is 70% survival at 7 years. Recently, animal models have been discovered that may provide a new insight into the pathogenesis of this disease and facilitate appreciation for novel treatment in PBC.     

High Levels of Soluble Ctla-4 Are Present in Anti-Mitochondrial Antibody Positive,but Not in Antibody Negative Patients with Primary Biliary Cirrhosis

Primary biliary cirrhosis (PBC) is a chronic autoimmune cholestatic liver disease frequently characterized by anti-mitochondrial autoantibodies (AMA). A minority of patients are AMA-negative. Cytotoxic-T-Lymphocyte-Antigen-4 (CTLA-4) is a surface molecule expressed on activated T-cells delivering a critical negative immunoregulatory signal. A soluble form of CTLA-4 (sCTLA-4) has been detected at high concentrations in several autoimmune diseases, and its possible functional meaning has been suggested. We aimed to evaluate sCTLA-4 concentration in sera of patients with PBC and to correlate it to immunological abnormalities associated with the disease. Blood samples were collected from 82 PBC-patients diagnosed according to international criteria (44 AMA-positive/MIT3-positive and 38 AMA-negative-MIT3-negative), and 65 controls. sCTLA-4 levels were evaluated by ELISA and Western blot. Increased sCTLA-4 concentrations were found in all AMA-positive PBC-patients, but in none of the AMA-negative ones, nor in normal controls or in controls with unrelated liver diseases. sCTLA-4 presence was associated with autoantibodies against MIT3, but not with nuclear autoantibodies (sp100, gp210). This is the first study to demonstrate that levels of sCTLA-4 are elevated in sera of PBC patients. However, they are clearly restricted to patients with AMA positivity, suggesting an immunological difference with respect to AMA-negative ones.     

Identification of new autoantigens for primary biliary cirrhosis using human proteome microarrays

Primary biliary cirrhosis (PBC) is a chronic cholestatic liver disease of unknown etiology and is considered to be an autoimmune disease. Autoantibodies are important tools for accurate diagnosis of PBC. Here, we employed serum profiling analysis using a human proteome microarray composed of about 17,000 full-length unique proteins and identified 23 proteins that correlated with PBC. To validate these results, we fabricated a PBC-focused microarray with 21 of these newly identified candidates and nine additional known PBC antigens. By screening the PBC microarrays with additional cohorts of 191 PBC patients and 321 controls (43 autoimmune hepatitis, 55 hepatitis B virus, 31 hepatitis C virus, 48 rheumatoid arthritis, 45 systematic lupus erythematosus, 49 systemic sclerosis, and 50 healthy), six proteins were confirmed as novel PBC autoantigens with high sensitivities and specificities, including hexokinase-1 (isoforms I and II), Kelch-like protein 7, Kelch-like protein 12, zinc finger and BTB domain-containing protein 2, and eukaryotic translation initiation factor 2C, subunit 1. To facilitate clinical diagnosis, we developed ELISA for Kelch-like protein 12 and zinc finger and BTB domain-containing protein 2 and tested large cohorts (297 PBC and 637 control sera) to confirm the sensitivities and specificities observed in the microarray-based assays. In conclusion, our research showed that a strategy using high content protein microarray combined with a smaller but more focused protein microarray can effectively identify and validate novel PBC-specific autoantigens and has the capacity to be translated to clinical diagnosis by means of an ELISA-based method.     

原发性胆汁性肝硬化患者临床指标变化与肝脏病理分期的回顾性分析

目的通过肝活检检测原发性胆汁性肝硬化（PBC）患者的病理分期,并对比血生化、自身抗体等指标进一步明确各期的生化特点,便于指导临床。方法所有患者采静脉血检查肝功,自身抗体,免疫球蛋白,所有患者进行肝脏活检,分析其肝脏病理分期。结果 43例患者血清抗线粒体抗体（AMA）及AMA-M2阳性为31例（72.1%）。27例（62.8%）ANA阳性,37例（86.1%）患者血清IgM水平升高。均有肝功能指标的明显异常,以GGT及ALP升高最明显。结论对胆酶增高而原因未明的肝病患者,早期自身免疫抗体及肝脏病理检查对原发性胆汁性肝硬化的诊断及治疗具有临床指导意义。     

Autoimmune liver disease 2007

Autoimmune liver disease (ALD) includes a spectrum of diseases which comprises both cholestatic and hepatitic forms: autoimmune hepatitis (AIH), primary biliary cirrhosis (PBC), primary sclerosing cholangitis (PSC) and the so called "overlap" syndromes where hepatitic and cholestatic damage coexists. All these diseases are characterized by an extremely high heterogeneity of presentation, varying from asymptomatic, acute (as in a subset of AIH) or chronic (with aspecific symptoms such as fatigue and myalgia in AIH or fatigue and pruritus in PBC and PSC). The detection and characterization of non organ specific autoantibodies plays a major role in the diagnostic approach of autoimmune liver disease; anti nuclear reactivities (ANA) and anti smooth muscle antibodies (SMA) mark type 1 AIH, liver kidney microsomal antibody type 1 (LKM1) and liver cytosol type 1 (LC1) are the serological markers of type 2 AIH; antimitochondrial antibodies (AMA) are associated with PBC, while no specific marker is found in PSC, since anticytoplasmic neutrophil antibodies with perinuclear pattern (atypical p-ANCA or p-ANNA) are also detected in a substantial proportion of type 1 AIH cases. Treatment options rely on immunosoppressive therapy (steroids and azathioprine) in AIH and on ursodeoxycholic acid in cholestatic conditions; in all these diseases liver transplantation remains the only therapeutical approach for the end stage of liver disease.     

Antibodies to hepatocyte membrane antigens in chronic liver disease: detection by immunofluorescence after Bouin's fixation

Using a modified indirect immunofluorescent (IF) technique in which cryostat tissue sections were fixed in Bouin's solution for ten minutes prior to reaction with sera under test, we have looked for antibodies to the hepatocyte membrane (HMA) in the sera of patients with chronic active hepatitis (CAH) and primary biliary cirrhosis (PBC). Samples were tested initially in parallel on unfixed and Bouin's-fixed rat composite blocks (kidney, stomach, liver) at a titer of 1:100 and those found to be positive were diluted further and reexamined. Conventional unfixed sections of rat composite block showed no liver membrane immunofluorescence although antinuclear (ANA), mitochondrial (AMA), and smooth muscle antibodies (SMA) were detected as anticipated. By contrast, prior Bouin's fixation abolished most of the fluorescence due to ANA, AMA and SMA but resulted in brilliant fluorescence of rat hepatocyte membranes in eleven of twelve patients with CAH (93%) and all ten patients with PBC. Only one of 22 normals (5%), one of 20 with collagen-vascular diseases (5%), and one of seven with nonimmunologic liver disease (14%) were positive for this hepatocyte membrane antibody. Bouin's fixation prior to IF is a simple technique which appears to alter the hepatocyte membrane so that HMA become detectable. The strong association of HMA with CAH and PBC suggests that this test might be of value and may contribute towards a further understanding of the pathogenesis of these conditions.     

Immunization with a xenobiotic 6-bromohexanoate bovine serum albumin conjugate induces antimitochondrial antibodies

The E2 subunit of pyruvate dehydrogenase complex (PDC-E2) is the major autoantigen recognized by antimitochondrial Abs (AMA) in primary biliary cirrhosis (PBC). Recently, we replaced the lipoic acid moiety of PDC-E2 with a battery of synthetic structures designed to mimic a xenobiotically modified lipoyl hapten on a 12-aa peptide that was found within the immunodominant autoepitope of PDC-E2 and demonstrated that AMA in PBC reacted against several organic modified mimotopes as well as, or sometimes significantly better than, the native lipoyl domain. Based on this data, we immunized rabbits with one such xenobiotic organic compound, 6-bromohexanoate, coupled to BSA. One hundred percent of immunized rabbits developed AMA that have each and every characteristic of human AMAs with reactivity against PDC-E2, E2 subunit of branched chain 2-oxo-acid dehydrogenase, and E2 subunit of 2-oxoglutarate dehydrogenase complex. The rabbit AMA also inhibited enzymatic function of PDC-E2 and, importantly, binds to peptide sequences not present in the xenobiotic carrier immunogen. In contrast, BSA-immunized controls did not produce such activity. Our observation that animals immunized with a xenobiotic BSA complex produce autoantibodies that react not only with the xenobiotic, but also with mitochondrial autoantigens recognized by autoimmune PBC sera, suggests that environmental xenobiotic agents can be a risk factor for the induction of PBC.     

Recurrent primary biliary cirrhosis after liver transplantation--the disease and its management

Primary biliary cirrhosis (PBC) is a chronic cholestatic liver disease characterized by the destruction of interlobular and septal bile ducts that can lead to fibrosis and cirrhosis. Orthotopic liver transplantation (OLT) remains the definitive treatment for decompensated liver disease secondary to PBC. An estimated 10% to 40% of patients develop clinical, biochemical, and histologic changes consistent with recurrent PBC after OLT. However, the presence of recurrent PBC does not appear to affect either graft or patient survival rates. There is conflicting evidence regarding the effect of specific immunosuppressant medications (eg, tacrolimus vs cyclosporine) on the risk of recurrent PBC. Most experts favor the use of ursodeoxycholic acid (UDCA) for recurrent PBC given its beneficial effect in patients with pretransplant PBC and its improvement of biochemical markers in the posttransplant setting. However, despite its potential benefit, there is no evidence that UDCA improves graft or patient survival in recurrent PBC.     

Antimitochondrial antibodies of primary biliary cirrhosis recognize dihydrolipoamide acyltransferase and inhibit enzyme function of the branched chain alpha-ketoacid dehydrogenase complex

Antimitochondrial antibodies (AMA) recognizing the acetyltransferase (E2) of the pyruvate dehydrogenase (PDH) complex have been previously well-documented and the immunodominant epitope mapped. In this study, we demonstrate that sera from patients with primary biliary cirrhosis (PBC) react with another lipoic acid containing acyltransferase enzyme, namely the E2 of the branched chain alpha-ketoacid dehydrogenase (BCKD) complex. Indeed, 85/120 (71%) sera from patients with PBC reacted with BCKD-E2 by immunoblotting against purified BCKD complex. In contrast, sera from patients with chronic active hepatitis or progressive sclerosing cholangitis as well as sera from healthy volunteers did not react with any component enzymes of the BCKD complex. More importantly, BCKD enzyme activity was inhibited after incubation of the BCKD complex with either PBC sera against BCKD-E2 or with affinity purified antisera to BCKD-E2. Enzyme activity was unaltered by control sera or with PBC sera that reacted with PDH-E2 but not BCKD-E2. Furthermore, immunoblots of purified mitochondria probed with PBC sera absorbed with BCKD-E2 demonstrated that BCKD-E2 and PDH-E2 are each recognized by distinct AMA populations which do not cross-react. In addition, affinity purified PBC sera against BCKD-E2 did not react with PDH-E2 nor inhibit PDH enzyme activity, thus providing further evidence that BCKD-E2 and PDH-E2 are recognized by separate AMA. These data further suggest that the BCKD-E2 epitope recognized by AMA contains, or is close to, a functional domain of this enzyme. The availability of cDNA clones encoding BCKD-E2 and PDH-E2 will allow the study of how key metabolic enzymes may be involved in the immunology and pathology of PBC.     

PR3-ANCA: A Promising Biomarker in Primary Sclerosing Cholangitis (PSC)

Background and Aims

The only recognized biomarker for primary sclerosing cholangitis (PSC) is atypical anti-neutrophil cytoplasmic antibodies (aANCA), which, in addition to having low sensitivity and specificity, is an indirect immunofluorescence (IIF) test lacking the advantages of high throughput and objectivity. Recent reports have shown that antibodies to proteinase-3 (PR3-ANCA) might add diagnostic value in inflammatory bowel disease (IBD), specifically in ulcerative colitis (UC). As PSC is associated with IBD, the objective of this study was to evaluate the frequency and clinical significance of PR3-ANCA in a large cohort of patients.

Methods

A total of 244 PSC and 254 control [autoimmune hepatitis (AIH), primary biliary cirrhosis (PBC), hepatitis C viral infection (HCV), hepatitis B viral infection (HBV), and healthy controls] sera and their clinical correlations were retrospectively analyzed for PR3-ANCA determined by ELISA and a new chemiluminescence immunoassay (CIA). Testing was also performed for aANCA by IIF.

Results

When measured by CIA, PR3-ANCA was detected in 38.5% (94/244) of PSC patients compared to 10.6% (27/254) controls (p<0.0001). By ELISA, PR3-ANCA was detected in 23.4% (57/244) of PSC patients compared to 2.7% (6/254) controls (p<0.0001). PR3-ANCA in PSC patients was not associated with the presence or type of underlying IBD, and, in fact, it was more frequent in Crohn''s disease (CD) patients with PSC than previously reported in CD alone. PR3-ANCA in PSC measured by CIA correlated with higher liver enzymes.

Conclusion

PR3-ANCA is detected in a significant proportion of PSC patients compared to other liver diseases including PBC and AIH. PR3-ANCA is associated with higher liver enzyme levels in PSC, and is not solely related to underlying IBD.     

The autoimmunity of primary biliary cirrhosis and the clonal selection theory

Primary biliary cirrhosis (PBC) is a chronic cholestatic liver disease in which an immune-mediated injury targets the small intrahepatic bile ducts. PBC is further characterized by highly specific serum antimitochondrial autoantibodies (AMAs) and autoreactive T cells, a striking female predominance, a strong genetic susceptibility and a plethora of candidate environmental factors to trigger the disease onset. For these reasons, PBC appears ideal to represent the developments of the clonal selection theory over the past decades. First, a sufficiently potent autoimmunogenic stimulus in PBC would require the coexistence of numerous pre-existing conditions (mostly genetic, as recently illustrated by genome-wide association studies and animal models) to perpetuate the destruction of the biliary epithelium by the immune system via the persistence of forbidden clones. Second, the proposed modifications of mitochondrial autoantigens caused by infectious agents and/or xenobiotics well illustrate the possibility that peculiar changes in the antigen structure and flexibility may contribute to tolerance breakdown. Third, the unique apoptotic features shown for cholangiocytes are the ideal setting for the development of mitochondrial autoantigen presentation to the immune system through macrophages and AMA; thus, turning the non-traditional mitochondrial antigen into a traditional one. This article will review the current knowledge on PBC etiology and pathogenesis in light of the clonal selection theory developments.     

The Value of MRI in the Diagnosis of Primary Biliary Cirrhosis and Assessment of Liver Fibrosis

Objectives

To evaluate MRI findings in patients with primary biliary cirrhosis (PBC) and to determine the value of MRI in the diagnosis of PBC and assessment of liver fibrosis.

Materials and Methods

This study reviewed the prevalence of MRI abnormalities seen in 45 PBC patients in the past four years, including 33 patients who underwent liver biopsy. Correlation between the MRI findings and the pathological stage was determined.

Results

There were 33 patients who underwent liver biopsy. Twenty-five patients (75.8%) had non-homogeneous changes in the liver signal intensity, 25 (75.8%) had a periportal halo sign, and 29 (87.9%) had lymphadenopathy. The short axis of the enlarged lymph nodes was a mean of 1.2±0.3 cm. A strong positive correlation was observed between histological stage and the inhomogeneity of liver signal intensity (P<0.001). There were significant differences among the four histological stages based on the periportal halo sign (P=0.034), and the grading of the periportal halo sign was found to be significantly correlated with the histological stage (P<0.001). Grading of the periportal halo sign was significantly different at stage II versus III, and stage III versus IV; no significant difference was found between stages I and II. There were also no significant differences among the four histological states in the occurrence and size of enlarged lymph nodes (P=0.674 and P=0.394).

Conclusion

MRI is valuable in the diagnosis of PBC, and the periportal halo sign and liver signal intensity help to evaluate the degree of liver fibrosis.     

Identification and characterization of mitochondria autoantigens in progressive systemic sclerosis: identity with the 72,000 dalton autoantigen in primary biliary cirrhosis

Sera from eight out of 62 (14.5%) patients with progressive systemic sclerosis (PSS) reacted by immunoblotting with a 72,000 dalton antigen and one, a patient with concomitant primary biliary cirrhosis (PBC), reacted with the 72,000 dalton and a 47,000 dalton antigen. Reactivity with these antigens was not seen with any of 111 control sera. The antigens with minor variations in m.w. were present in a variety of cultured cells and tissue homogenates from different species. Subcellular fractionation studies localized the antigens to the mitochondria. Of 19 sera from patients with other diseases selected for immunofluorescence staining for anti-mitochondria autoantibody, nine reacted with the 72,000 dalton antigen, seven reacted with both the 72,000 and 47,000 dalton antigens, and three reacted with the 47,000 dalton antigen. These results show that serum reactivity with the 72,000 dalton and 47,000 dalton mitochondria autoantigens is found with some patients with PSS. Because mitochondria autoantibodies that are reactive with the 72,000 dalton and 47,000 dalton polypeptides are also found in patients with PBC, the present finding provides additional support for the association of PSS with PBC. Prior absorption of rat liver homogenate with PBC sera removed PSS serum reactivity with a 63,000 dalton antigen, the equivalent 72,000 dalton antigen in rodents, and vice versa, showing that both PBC and PSS sera recognize the same antigen.     

Immunopathogenesis of primary biliary cirrhosis: an old wives' tale

Primary biliary cirrhosis (PBC) is a cholestatic liver disease characterised by the autoimmune destruction of the small intrahepatic bile ducts. The disease has an unpredictable clinical course, but may progress to fibrosis and cirrhosis. Although medical treatment with urseodeoxycholic acid is largely successful, some patients may progress to liver failure requiring liver transplantation. PBC is characterised by the presence of disease specific anti-mitochondrial (AMA) antibodies, which are pathognomonic for PBC development. The disease demonstrates an overwhelming female preponderance and virtually all women with PBC present in middle age. The reasons for this are unknown; however several environmental and immunological factors may be involved. As the immune systems ages, it become less self tolerant, and mounts a weaker response to pathogens, possibly leading to cross reactivity or molecular mimicry. Some individuals display immunological changes which encourage the development of autoimmune disease. Risk factors implicated in PBC include recurrent urinary tract infection in females, as well as an increased prevalence of reproductive complications. These risk factors may work in concert with and possibly even accelerate, immune system ageing, contributing to PBC development. This review will examine the changes that occur in the immune system with ageing, paying particular attention to those changes which contribute to the development of autoimmune disease with increasing age. The review also discusses risk factors which may account for the increased female predominance of PBC, such as recurrent UTI and oestrogens.     

Clinical relevance of autoantibodies in systemic rheumatic diseases

Autoantibodies directed to intracellular antigens are serological hallmarks of systemic rheumatic diseases. Identification of circulating autoantibodies is helpful in establishing the correct diagnosis, indicating the prognosis and providing a guide to treatment and follow-up. Some autoantibodies are included in diagnostic and classification criteria for diseases such as anti-Sm antigen and anti-double-stranded DNA antibodies in systemic lupus erythematosus, anti-U1 nuclear ribonucleoprotein antibodies in mixed connective tissue disease, and anti-SS-A/Ro and anti-SS-B/La antibodies in Sjögren's syndrome. Over the past 30 years, the identification of new autoantibody systems was advanced by the initiation or adaptation of novel techniques such as double immunodiffusion to detect antibodies to saline-soluble nuclear antigens, extraction-reconstitution and ELISA techniques to detect histone and chromatin antibodies, immunoblotting and immunoprecipitation to detect a wide range of antibodies directed against naturally occurring and recombinant proteins. These techniques have been made possible by advances in cellular and molecular biology and in turn, the sera from index patients have been important reagents to identify novel intracellular macromolecules. This paper will focus on the clinical relevance of several autoantibody systems described by Tan and his colleagues over the past 30 years.Abbreviations ANA antinuclear antibody - CENPs centromere proteins - CTD connective tissue disease - DIA drug-induced autoimmunity - DIL drug-induced lupus - HIV human immunodeficiency virus - IIF indirect immunofluorescence - JCA juvenile chronic arthritis - MCTD mixed connective tissue disease - MSA mitotic spindle apparatus - NOR nucleolar organizer - NuMA nuclear mitosis antigen - PBC primary biliary cirrhosis - PCNA proliferating cell nuclear antigen - PM polymyositis - RA rheumatoid arthritis - RNP ribonucleoprotein - SLE systemic lupus erythematosus - SS Sjögren's syndrome - SSc systemic sclerosis - UCTD undifferentiated connective tissue disease     

原发性胆汁性肝硬化的药物治疗进展

原发性胆汁性肝硬化(Primary Biliary Cirrhosis,PBC)是一种以胆汁淤积及慢性非化脓性破坏性胆管炎为特点的自身免疫介导的慢性肝脏病。熊去氧胆酸(UDCA)作为PBC患者的首选治疗药物可使患者的生化指标、存活指标以及组织学等都得以改善。尽管如此,PBC的治疗仍是临床医师的一大难题,大约40%的PBC患者对UDCA的治疗仅获得了不完全应答,而肝移植则为晚期PBC患者治疗之首选。本文简要介绍近些年治疗PBC药物的新进展,包括熊去氧胆酸、布地奈德、免疫抑制剂、贝特类、6α-乙基鹅去氧胆酸、利妥昔单抗以及抗逆转录病毒药物等,期望为PBC的治疗提供帮助。     

Autoantibodies of primary biliary cirrhosis recognize dihydrolipoamide acetyltransferase and inhibit enzyme function

Autoantibodies against mitochondria occur in the sera of patients with primary biliary cirrhosis (PBC) with characteristic reactivity to an inner membrane protein of approximately 74 kDa. To precisely define these autoantigens, we recently cloned and sequenced a rat liver cDNA (pRMIT) that encodes for all of the epitopes recognized by Ig to the 74-kDa autoantigen. In the present study we have used this recombinant probe as a tool, in addition to purified enzymes, to demonstrate by immunoblotting that the 74-kDa mitochondrial autoantigen is dihydrolipoamide acetyltransferase (EC 2.3.1.12), the core protein of the pyruvate dehydrogenase complex. Furthermore, and of particular interest, inhibition of pyruvate dehydrogenase enzyme activity was demonstrated after incubation with sera from patients with PBC but not from normal volunteers or patients with chronic active hepatitis. Such inhibition was abrogated by absorption of the PBC sera with an expressing subclone of pRMIT, designated pRMIT-603. Identification of dihydrolipoamide acetyltransferase as the target of autoimmunity in PBC provides a reagent that can be used to determine mechanisms by which this molecule is recognized. It will allow study of whether autoimmune reactivity, at the humoral or T cell level, is the basis for the pathogenesis of PBC. Additionally, such data present evidence of functional inhibition of a critical metabolic enzyme. Dihydrolipoamide acetyltransferase is well-known to mitochondrial biochemistry and, similar to identified autoantigens in other autoimmune diseases, is highly conserved in evolution.     

Anti-mitochondrial antibodies and primary biliary cirrhosis in TGF-beta receptor II dominant-negative mice

Primary biliary cirrhosis (PBC) is an autoimmune disease of the liver, characterized by lymphocytic infiltrates in portal tracts, selective destruction of biliary epithelial cells, and anti-mitochondrial Abs (AMAs). The elucidation of early events in the induction of tissue inflammation and autoimmunity in PBC has been hampered by the cryptic onset of the disease, the practical limitations in accessing the target tissue, and the lack of a suitable animal model. We demonstrate in this study that a mouse transgenic for directed expression of a dominant-negative form of TGF-beta receptor type II (dnTGFbetaRII), under the direction of the CD4 promoter, mimics several key phenotypic features of human PBC, including spontaneous production of AMAs directed to the same mitochondrial autoantigens, namely PDC-E2, BCOADC-E2, and OGDC-E2. The murine AMAs also inhibit PDC-E2 activity. Moreover, there is lymphocytic liver infiltration with periportal inflammation analogous to the histological profile in human PBC. Additionally, the serum cytokine profile of affected mice mimics data in human PBC. The concomitant presence of these immunopathological features in the transgenic mice suggests that the TGF-betaRII pathway is implicated in the pathogenesis of PBC. Finally, these data point away from initiation of autoimmunity by mechanisms such as molecular mimicry and more toward activation of an intrinsically self-reactive T cell repertoire in which necessary regulatory T cell influences are lacking.     

Apoptosis-associated antigens recognized by autoantibodies in patients with the autoimmune liver disease primary biliary cirrhosis

There is growing evidence that the onset of autoimmune disorders can be linked to the inefficient removal of apoptotic cells. Since defects in the elimination of apoptotic cells lead to secondary necrosis and subsequent release of intracellular components, this might explain the generation of autoantibodies against intracellular antigens. Accordingly, we wanted to investigate, whether antibodies from patients with the autoimmune liver disease primary biliary cirrhosis (PBC) recognize self-proteins generated and released during apoptosis. Using Western blot analyses we could detect intracellular antigens with serum IgG from PBC patients but not with serum IgG from healthy donors in lysates of Jurkat T-leukemia, HepG2 hepatoma, and HT-29 colon-carcinoma cells. Interestingly, PBC serum IgG also recognized caspase substrates in cells undergoing apoptosis induced by staurosporine or TRAIL (TNF-related apoptosis inducing ligand). In addition to intracellular antigens, serum IgG from PBC patients detected caspase-dependent antigens in the supernatants of apoptotic (secondary necrotic) cells and antigens on the surface of apoptotic Jurkat cells. Among the caspase substrates recognized by PBC serum IgG we could identify the components PDC-E2 and -E1β of the known autoantigen PDC (pyruvate dehydrogenase complex). Thus, caspase-mediated processing of intracellular proteins might generate de novo autoantigens that upon release contribute to the generation of autoantibodies and autoimmune diseases as PBC. Christoph Peter Berg and Gerburg Maria Stein contributed equally to this paper and share first authorship. Sebastian Wesselberg and Kirsten Lauber share equal senior authorship.     

免疫球蛋白在原发性胆汁性肝硬化与自身免疫性肝炎组织中的表达及意义

目的:原发性胆汁性肝硬化(PBC)与自身免疫性肝炎(AIH)的临床表现存在相似性,因而不易鉴别及诊断。本研究对免疫球蛋白在PBC和AIH中的表达情况进行比较并分析其意义,为两种疾病的鉴别和诊断积累临床资料。方法:选取2011年10月-2012年10月在我院接受治疗的原发性胆汁性肝硬化患者20例作为PBC组,另选取20例同期入院治疗的自身免疫性肝炎患者作为AIH组。利用免疫组化法检测两组患者病变组织中免疫球蛋白IgM和IgG的表达水平,比较两组细胞的阳性表达率,并对阳性细胞含量进行评分。结果:PBC组:17例患者显示IgM阳性(85%),3例患者显示IgG阳性(15%),IgM与IgG比值1,IgM评分为3.2±0.8,IgG评分为1.5±0.6;AIH组:18例患者显示IgG阳性(90%),2例患者显示IgM阳性(10%),IgM与IgG比值1,IgM评分为1.2±0.7,IgG评分为2.4±0.9。PBC组的IgM评分明显高于AIH组,而AIH组的IgG评分则明显高于PBC组,差异具有统计学意义(P0.05)。结论:检测IgG和IgM的表达水平对原发性胆汁性肝硬化与自身免疫性肝炎的临床诊断具有较高的敏感性和特异性,可作为鉴别两种疾病的依据之一,值得进一步推广应用。