Primary biliary cirrhosis: paradigm or paradox for autoimmunity

Extrahepatic Manifestations of Primary Biliary Cholangitis

Primary biliary cholangitis (PBC) is an autoimmune liver disease characterized by progressive destruction of the intrahepatic bile ducts, leading to cholestasis. PBC is known to have both hepatic and extrahepatic manifestations. Extrahepatic manifestations are seen in up to 73% of patients with PBC, with the most common being Sjogren’s syndrome, thyroid dysfunction and systemic sclerosis. It is thought that patients with PBC are at increased risk of developing these extrahepatic manifestations, almost all of which are autoimmune, because patients with autoimmune disease are at higher risk of developing another autoimmune condition. Due to the high prevalence of extrahepatic diseases in patients with PBC, it is important to complete a thorough medical history at the time of diagnosis. Prompt recognition of extrahepatic disease can lead to improved patient outcomes and quality of life. The following review summarizes the most common extrahepatic conditions associated with PBC.

A case of severe osteomalacia caused by Tubulointerstitial nephritis with Fanconi syndrome in asymptomotic primary biliary cirrhosis

Background

Primary biliary cirrhosis (PBC) is an immune-mediated chronic cholestatic liver disease, characterized by increased concentrations of serum IgM and the presence of circulating anti-mitochondrial antibodies. Although bone diseases such as osteoporosis or osteodystrophy are commonly associated with PBC, osteomalacia which is caused by abnormal vitamin D metabolism, mineralization defects, and phosphate deficiency has not been recognized as a complication of PBC.

Case presentation

We report the case of a 49-year-old Japanese woman who complained of multiple fractures. Hypophosphatemic osteomalacia was diagnosed from a low serum phosphorus level, 1,25-dihydroxyvitamin D₃ level_, high levels of bone specific alkaline phosphatase and the findings of bone scintigraphy, although a bone biopsy was not performed. Twenty four hour urine demonstrated a low renal fractional tubular reabsorption of phosphate, increased fractional excretion of uric acid and generalized aminoaciduria. An intravenous bicarbonate loading test suggested the presence of proximal renal tubular acidosis (RTA). These biochemical data indicated Fanconi syndrome with proximal RTA. A kidney biopsy demonstrated the features of tubulointerstitial nephritis (TIN).

The patient was also suspected as having primary biliary cirrhosis (PBC) because of high levels of alkaline phosphatase, IgM and the presence of anti-mitochondrial M2 antibody, though biochemical liver function was normal. Sequential liver biopsy was compatible with PBC and the diagnosis of PBC was definite. After administration of 1,25 dihydroxyvitamin D_3, neutral potassium phosphate, sodium bicarbonate for osteomalacia and subsequent predonizolone for TIN, symptoms of fractures were relieved and renal function including Fanconi syndrome was ameliorated.

Conclusion

In this case, asymptomatic PBC was shown to induce TIN with Fanconi syndrome with dysregulation of electrolytes and vitamin D metabolism, which in turn led to osteomalacia with multiple fractures. Osteomalacia has not been recognized as a result of the renal involvement of PBC. PBC and its rare complication of TIN with Fanconi syndrome should be considered in adult patients with unexplained osteomalacia even in the absence of liver dysfunction.

Tracing environmental markers of autoimmunity: introducing the infectome

We recently introduced the concept of the infectome as a means of studying all infectious factors which contribute to the development of autoimmune disease. It forms the infectious part of the exposome, which collates all environmental factors contributing to the development of disease and studies the sum total of burden which leads to the loss of adaptive mechanisms in the body. These studies complement genome-wide association studies, which establish the genetic predisposition to disease. The infectome is a component which spans the whole life and may begin at the earliest stages right up to the time when the first symptoms manifest, and may thus contribute to the understanding of the pathogenesis of autoimmunity at the prodromal/asymptomatic stages. We provide practical examples and research tools as to how we can investigate disease-specific infectomes, using laboratory approaches employed from projects studying the “immunome” and “microbiome”. It is envisioned that an understanding of the infectome and the environmental factors that affect it will allow for earlier patient-specific intervention by clinicians, through the possible treatment of infectious agents as well as other compounding factors, and hence slowing or preventing disease development.

E. coli Induced Experimental Model of Primary Biliary Cirrhosis: At Last

Recurrent urinary tract infections (UTI) have been considered potential triggers of primary biliary cirrhosis (PBC), an autoimmune cholestatic liver disease characterised by progressive destruction of intrahepatic bile ducts. Additional support for the link made between PBC and UTI was based on early observations of recurrent episodes of bacteriuria in female patients with PBC. A series of large epidemiological studies demonstrated a strong correlation between recurrent UTI and PBC, initiating a series of studies investigating the role of Escherichia coli (E. coli, the most prevalent organism isolated in women with UTI) as a trigger of PBC. Immunological evidence of B- and T-cell cross-reactive responses implicating PBC-specific autoantigens and E. coli mimics have been clearly demonstrated, adding support to the notion that E. coli is a potential infectious inducer of PBC in susceptible individuals. One of the major limitations in proving the E. coli/PBC association was the lack of reliable E. coli-infected animal models of PBC. This review provides an overview of the evidence linking this infectious agent with PBC and discusses the pros and cons of a recently developed E. coli-infected animal model of PBC.

Infectome: a platform to trace infectious triggers of autoimmunity

The "exposome" is a term recently used to describe all environmental factors, both exogenous and endogenous, which we are exposed to in a lifetime. It represents an important tool in the study of autoimmunity, complementing classical immunological research tools and cutting-edge genome wide association studies (GWAS). Recently, environmental wide association studies (EWAS) investigated the effect of environment in the development of diseases. Environmental triggers are largely subdivided into infectious and non-infectious agents. In this review, we introduce the concept of the "infectome", which is the part of the exposome referring to the collection of an individual's exposures to infectious agents. The infectome directly relates to geoepidemiological, serological and molecular evidence of the co-occurrence of several infectious agents associated with autoimmune diseases that may provide hints for the triggering factors responsible for the pathogenesis of autoimmunity. We discuss the implications that the investigation of the infectome may have for the understanding of microbial/host interactions in autoimmune diseases with long, pre-clinical phases. It may also contribute to the concept of the human body as a superorganism where the microbiome is part of the whole organism, as can be seen with mitochondria which existed as microbes prior to becoming organelles in eukaryotic cells of multicellular organisms over time. A similar argument can now be made in regard to normal intestinal flora, living in symbiosis within the host. We also provide practical examples as to how we can characterise and measure the totality of a disease-specific infectome, based on the experimental approaches employed from the "immunome" and "microbiome" projects.

Popular and unpopular infectious agents linked to primary biliary cirrhosis

Primary biliary cirrhosis (PBC) is a progressive cholestatic liver disease characterized by the autoimmune destruction of the biliary epithelial cells of the small and medium-size bile ducts. The disease affects middle aged women and usually affects more than one member within a family. The pathognomonic serological hallmark of the disease is the presence of circulating anti-mitochondrial antibodies, and disease-specific anti-nuclear antibodies. Susceptibility genes and environmental risk factors such as infections and smoking have been reported as important for the development of the disease. Among the environmental agents, infectious triggers are the best studied. Most of the work published so far has investigated the role of infections caused by Novosphingobium aromaticivorans and Escherichia coli. This review will discuss the popular and unpopular infectious agents causatively linked to PBC. It will also examine reports investigating the epidemiological aspects of the disease and their direct or indirect implications to bacterial-induced PBC.

Role for mycobacterial infection in pathogenesis of primary biliary cirrhosis?

Primary biliary cirrhosis (PBC) is a progressive cholestatic liver disease characterized by the immune-mediated destruction of biliary epithelial cells in small intrahepatic bile ducts. The disease is characterized by circulating antimitochondrial antibodies (AMAs) as well as disease-specific antinuclear antibodies, cholestatic liver function tests, and characteristic histological features, including granulomas. A variety of organisms are involved in granuloma formation, of which mycobacteria are the most commonly associated. This has led to the hypothesis that mycobacteria may be involved in the pathogenesis of PBC, along with other infectious agents. Additionally, AMAs are found in a subgroup of patients with mycobacterial infections, such as leprosy and pulmonary tuberculosis. Antibodies against species-specific mycobacterial proteins have been reported in patients with PBC, but it is not clear whether these antibodies are specific for the disease. In addition, data in support of the involvement of the role of molecular mimicry between mycobacterial and human mitochondrial antigens as triggers of cross-reactive immune responses leading to the loss of immunological tolerance, and the induction of pathological features have been published. Thus, antibodies against mycobacterial heat shock protein appear to cross-recognize AMA-specific autoantigens, but it is not clear whether these autoantibodies are mycobacterium-species-specific, and whether they are pathogenic or incidental. The view that mycobacteria are infectious triggers of PBC is intriguing, but the data provided so far are not conclusive.

Autoimmunity and environment: am I at risk?

The complex interplay between environmental factors and genetic susceptibility plays an essential role in disease pathogenesis. This is especially true for autoimmunity, where clinical reports, genomic and epidemiological studies, as well as animal models have identified several environmental and genetic risk factors associated with autoimmune disease. The complexity of this relationship is demonstrated by the vast array of environmental factors that have now been implicated in the induction, and possibly the maintenance of autoimmune disease. The multitude of environmental factors implicated includes both infectious and non-infectious agents. Here, we review one specific autoimmune disease, primary biliary cirrhosis (PBC), as a model for environmental risk factors acting in concert with genetic susceptibility in the disease pathogenesis. PBC is an ideal model, as both infectious and non-infectious environmental agents have been identified as risk factors, and their study provides clues for unravelling the pathogenesis of the disease.

Autoimmune hepatitis type 2 associated with an unexpected and transient presence of primary biliary cirrhosis-specific antimitochondrial antibodies: a case study and review of the literature

Background

Unlike other autoimmune liver diseases, primary biliary cirrhosis (PBC) has never been reported in early childhood, while type 2 autoimmune hepatitis (AIH) is eminently a paediatric disease.

Case presentation

We describe a case of type 2 AIH with serological positivity for PBC-specific anti-mitochondrial antibodies (AMA) in a 3-year old girl. We found this observation intriguing as AMA and indeed an overlap with PBC are virtually absent in Type 2 AIH, a pediatric form of AIH which is distinct precisely because it is characterized by pathognomonic anti-liver kidney microsomal type 1 (LKM-1) showing a remarkable antigen-specificity directed against cytochrome P4502D6. We also review the literature in relation to AMA positivity in paediatric age and adolescence. In our case, the presence of AIH-2-specific anti-LKM-1 and PBC-specific AMA was confirmed by indirect immunofluorescence (IIF), and immunoblotting and ELISA based on recombinant mitochondrial antigens. The clinical, laboratory and histological features of the child are given in detail. Interestingly the mother was AMA positive without other features of PBC. The child was successfully treated with immunosuppression and five years after the original diagnosis is on a low dose of prednisolone and azathioprine, with no signs of relapse. Anti-LKM-1 antibodies are still present in low titres. AMA were detectable for the first 4 years after the diagnosis and disappeared later.

Conclusion

This is the first case report in the literature of AIH type 2 with an unexpected PBC-specific AMA positivity in a young child. Response to immunosuppressive treatment was satisfactory and similar to that described in AIH. A review of published reports on AMA positivity in paediatric age shows that the antibody may arise in the context of immunodeficiency and is variably associated with liver damage.

Sex differences associated with primary biliary cirrhosis

Primary biliary cirrhosis (PBC) is a cholestatic liver disease of autoimmune origin, characterised by the destruction of small intrahepatic bile ducts. The disease has an unpredictable clinical course but may progress to fibrosis and cirrhosis. The diagnostic hallmark of PBC is the presence of disease-specific antimitochondrial antibodies (AMA), which are pathognomonic for the development of PBC. The disease overwhelmingly affects females, with some cases of male PBC being reported. The reasons underlying the low incidence of males with PBC are largely unknown. Epidemiological studies estimate that approximately 7–11% of PBC patients are males. There does not appear to be any histological, serological, or biochemical differences between male and female PBC, although the symptomatology may differ, with males being at higher risk of life-threatening complications such as gastrointestinal bleeding and hepatoma. Studies on X chromosome and sex hormones are of interest when studying the low preponderance of PBC in males; however, these studies are far from conclusive. This paper will critically analyze the literature surrounding PBC in males.

Epstein-barr virus as a trigger of autoimmune liver diseases

The pathogenesis of autoimmune diseases includes a combination of genetic factors and environmental exposures including infectious agents. Infectious triggers are commonly indicated as being involved in the induction of autoimmune disease, with Epstein-Barr virus (EBV) being implicated in several autoimmune disorders. EBV is appealing in the pathogenesis of autoimmune disease, due to its high prevalence worldwide, its persistency throughout life in the host's B lymphocytes, and its ability to alter the host's immune response and to inhibit apoptosis. However, the evidence in support of EBV in the pathogenesis varies among diseases. Autoimmune liver diseases (AiLDs), including autoimmune hepatitis (AIH), primary biliary cirrhosis (PBC), and primary sclerosing cholangitis (PSC), have a potential causative link with EBV. The data surrounding EBV and AiLD are scarce. The lack of evidence surrounding EBV in AiLD may also be reflective of the rarity of these conditions. EBV infection has also been linked to other autoimmune conditions, which are often found to be concomitant with AiLD. This paper will critically examine the literature surrounding the link between EBV infection and AiLD development. The current evidence is far from being conclusive of the theory of a link between EBV and AiLD.

Urinary tract infection as a risk factor for autoimmune liver disease: from bench to bedside

Autoimmune liver diseases include autoimmune hepatitis (AIH), primary biliary cirrhosis (PBC), and primary sclerosing cholangitis. A variety of environmental and genetic risk factors have been associated with these conditions. Recurrent urinary tract infections (rUTI) have been strongly associated with PBC, and to a lesser extent with AIH. These observations were initially based on the observation of significant bacteriuria in female patients with PBC. Larger epidemiological studies demonstrated that there was indeed a strong correlation between recurrent UTI and PBC. AIH has not been linked to recurrent UTI in epidemiological studies; however treatment of UTI with nitrofurantoin can induce AIH. As Escherichia coli is the most prevalent organism isolated in women with UTI, it has been suggested that molecular mimicry between microbial and human PDC-E2 (the main autoantigenic target in PBC) epitopes may explain the link between UTI and PBC. Multiple studies have demonstrated molecular mimicry and immunological cross-reactivity involving microbial and self-antigen mimics. This review will examine the literature surrounding UTI and autoimmune liver disease. This will include case reports and epidemiological studies, as well as experimental data.

Hair dyes as a risk for autoimmunity: from systemic lupus erythematosus to primary biliary cirrhosis

Environmental and genetic factors appear to be involved in the pathogenesis of primary biliary cirrhosis (PBC), a chronic cholestatic liver disease characterized by immune-mediated destruction of the small and medium sized intrahepatic bile ducts. Environmental factors include exposure to various infectious, xenobiotic and chemical compounds. These exposures may occur occupationally, through water or air contamination, pharmacological administration or by elective exposure, to name a few. Hair dyes are compounds that have been implicated in the development of several autoimmune diseases, including systemic lupus erythematosus (SLE) and PBC. So far, only epidemiological studies have addressed the role of hair dyes in PBC, with limited results. Hair dyes in SLE have been examined, and have recently demonstrated an association, both epidemiologically and immunologically. This follows a series of negative studies, which may not have taken into account several features of hair dye use. This review will examine the literature surrounding hair dye use and SLE, and compare this to data surrounding PBC. Treating physicians should be prepared for questions surrounding the need to take precautions against repeated hair dye use and this topic is discussed further.

Primary biliary cirrhosis associated with systemic sclerosis: diagnostic and clinical challenges

Patients with primary biliary cirrhosis (PBC) often have concurrent limited systemic sclerosis (SSc). Conversely, up to one-fourth of SSc patients are positive for PBC-specific antimitochondrial antibodies (AMA). The mechanisms responsible for the co-occurrence of these diseases are largely unknown. Genetic, epigenetic, environmental, and infectious factors appear to be important for the pathogenesis of the disease, but the hierarchy of events are not well defined. Patients with SSc and PBC have an increased morbidity and mortality compared with the general population, but whether the presence of both diseases in an affected individual worsens the prognosis and/or outcome of either disease is not clear. Some case reports suggested that the presence of SSc in PBC patents is associated with a more favorable prognosis of the liver disease, whereas others report an increased mortality in patients with PBC and SSc compared to patients with PBC alone. This paper discusses the features of patients with PBC-associated SSc. Our aims are to clarify some of the pathogenetic, diagnostic, and clinical challenges that are currently faced in the routine management of these patients. We also intend to provide some practical hints for practitioners that will assist in the early identification of patients with PBC-associated SSc.

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.

Towards systemic sclerosis and away from primary biliary cirrhosis: the case of PTPN22

Primary biliary cirrhosis (PBC) is a chronic cholestatic liver disease characterized by immune-mediated destruction of the small and medium size intrahepatic bile ducts. PBC patients often have concomitant autoimmune diseases, which are most often autoimmune thyroid disease, as well as Sicca syndrome. Occasionally, some PBC patients will also have systemic sclerosis of the limited cutaneous type (lcSSc). Conversely, up to one-fourth of SSc patients are positive for antimitochondrial antibody, the serologic hallmark of PBC. It is also common for SSc patients to have concomitant autoimmune disease, which may include PBC in rare cases. This has led to speculation of shared environmental and/or genetic factors, which lead to the development of PBC in SSc patients and vice versa. Recent genetic studies have revealed associations with several genes in both SSc and PBC. PTPN22 is one gene that has been associated with SSc, but not with PBC. It may be argued that some SSc patients with a particular genotype, which shares genes found in both conditions may develop PBC. Likewise, particular genes such as PTPN22 may infer susceptibility to SSc alone. The presence of PTPN22 may also contribute to the development of SSc in PBC patients. The lack of a large number of overlapping genes may, in part, explain the relative rarity of PBC with SSc and vice versa. This review will examine the literature surrounding the genetic associations of PBC and SSc, and the role of PTPN22 in particular.

Primary biliary cirrhosis: family stories

Primary biliary cirrhosis (PBC) is a chronic immune-mediated cholestatic liver disease of unknown aetiology which affects mostly women in middle age. Familial PBC is when PBC affects more than one member of the same family, and data suggest that first-degree relatives of PBC patients have an increased risk of developing the disease. Most often, these familial clusters involve mother-daughter pairs, which is consistent with the female preponderance of the disease. These clusters provide evidence towards a genetic basis underlying PBC. However, clusters of nonrelated individuals have also been reported, giving strength to an environmental component. Twin studies have demonstrated a high concordance for PBC in monozygotic twins and a low concordance among dizygotic twins. In conclusion, studies of PBC in families clearly demonstrate that genetic, epigenetic, and environmental factors play a role in the development of the disease.

Bacteria and primary biliary cirrhosis

Infectious agents have been postulated to play a pathogenic role in the loss of immunological tolerance and the induction of primary biliary cirrhosis, an immune-mediated cholestatic liver disease characterized by progressive destruction of the small intrahepatic bile ducts and subsequent cirrhosis and liver failure. This review discusses emerging issues implicating infectious agents such as Escherichia coli, mycobacteria, chlamydia, helicobacter species, lactobacilli, Novosphingobium aromaticivorans, and betaretroviruses in the pathogenesis of primary biliary cirrhosis. We also review the immunopathological mechanisms responsible for the induction of the disease with special emphasis on the role of molecular mimicry and microbial/self immunological cross-reactivity.

Clinical features and management of primary biliary cirrhosis

Primary biliary cirrhosis (PBC), which is characterized by progressive destruction of intrahepatic bile ducts, is not a rare disease since both prevalence and incidence are increasing during the last years mainly due to the improvement of case finding strategies. The prognosis of the disease has improved due to both the recognition of earlier and indolent cases, and to the wide use of ursodeoxycholic acid (UDCA). New indicators of prognosis are available that will be useful especially for the growing number of patients with less severe disease. Most patients are asymptomatic at presentation. Pruritus may represent the most distressing symptom and, when UDCA is ineffective, cholestyramine represents the mainstay of treatment. Complications of long-standing cholestasis may be clinically relevant only in very advanced stages. Available data on the effects of UDCA on clinically relevant end points clearly indicate that the drug is able to slow but not to halt the progression of the disease while, in advanced stages, the only therapeutic option remains liver transplantation.

A tribute to an outstanding immunologist - Ian Reay Mackay

The 11th Australasian Autoimmunity Workshop was held in Melbourne, Australia from July 6-8, 2007 organized by the Monash University Autoimmunity Network. The workshops, founded by the late Kevin Lafferty, are a chance for Australasians interested in research into autoimmune disease to present and discuss their work. This workshop also was a chance to acknowledge Ian Mackay, a pioneer clinician-scientist who has made major contributions to our understanding of autoimmune diseases. Friends, colleagues and former students attended the Workshop and acknowledged Ian's expertise and mentorship. This edition of the Journal of Autoimmunity pays tribute to Ian Mackay. It features articles from attendees at the workshop, and contributions from some of Ian's past students and past and current collaborators.

The value of antinuclear antibodies in primary biliary cirrhosis

OBJECTIVE

Although autoantibodies have been used for the diagnosis of primary biliary cirrhosis (PBC), their role has not been clarified. In this study, we try to explore the value of gp210 antibody and anti-centromere antibodies (ACA) in PBC.

METHODS

Anti-gp210 and ACA were tested in 140 PBC patients by ELISA and indirect immunofluorescence respectively. Their association with clinical, pathological data and prognosis was analysed.

RESULTS

30.5% of PBC patients had positive anti-gp210 antibody and 29.2% had ACA. The anti-gp210 antibody positive group had higher Mayo risk scores and lower serum albumin levels compared to the negative one. Patients with positive anti-gp210 antibody were more likely to develop hepatic failure (p<0.05, OR=9.8460, 95% CI: 1.067-90.901) than patients with negative anti-gp210 antibody. More patients with positive ACA developed portal hypertension than patients with negative ACA (p<0.05, OR=9.259; 95% CI: 1.027-88.410). Furthermore, concurrent Sjögren's syndrome (SjS) and PBC was significantly more likely in the ACA positive group than in the negative ones (68.4% in ACA positive group, 20.7% in ACA negative group p<0.001).

CONCLUSIONS

Both anti-gp210 antibody and ACA are related to severe disease course and poor prognosis. For PBC patients with positive ACA, further examinations should be made to detect underlying SjS.

Autoimmune cholangitis in NOD.c3c4 mice is associated with cholangiocyte-specific Fas antigen deficiency

A major handicap in understanding the pathogenesis of autoimmune cholangitis has been the absence of an informative mouse model. Recently, autoimmune cholangitis, with several features similar to PBC, has been described in NOD.c3c4 mice, including anti-mitochondrial antibodies, lymphocytic portal tract infiltrates, biliary destruction and the adoptive transfer of disease to naïve recipients using liver-derived lymphocytes. A unique feature, and a characteristic quite distinct from human PBC, is the presence of bile cyst formation. We have addressed the issue of cysts in NOD.c3c4 mice by performing comprehensive microarray analysis using cholangiocytes from NOD.c3c4 mice compared to NOD controls. Several key differences in gene expression were noted in NOD.c3c4 cholangiocytes. First, there was consistent impairment in the expression of Fas antigen (CD95). Second, cholangiocytes were PCNA positive but TUNEL negative, suggesting an absence of apoptosis despite abnormal proliferation. In conclusion, we propose that autoimmune cholangitis develops in NOD.c3c4 mice secondary to impaired biliary cell apoptosis with exposure of mitochondrial antigens, loss of tolerance and subsequent development of multi-lineage anti-mitochondrial responses.

Primary biliary cirrhosis: what we know and what we want to know about human PBC and spontaneous PBC mouse models

Human autoimmune cholangiopathy comprises several intractable liver diseases that ultimately lead to hepatic failure. Primary biliary cirrhosis (PBC), allograft rejection, graft versus host diseases, and, possibly, primary sclerosing cholangitis are representative of immune-mediated cholangiopathies. Among them, PBC is the best-investigated human autoimmune cholangiopathy. The immunological approach to PBC has provided much critical information regarding its pathogenesis. The breakdown of self-tolerance in both B cells and T cells toward E2 components of the pyruvate dehydrogenase complex is evident. However, a number of questions regarding its etiology are unclear, in particular, the mechanisms involved in the selectivity of cholangiocyte destruction. In this brief review, we discuss what we know and we do not know regarding the pathogenesis of PBC.

Antinuclear antibodies giving the 'multiple nuclear dots' or the 'rim-like/membranous' patterns: diagnostic accuracy for primary biliary cirrhosis

BACKGROUND

Serum antinuclear antibodies giving the 'multiple nuclear dots' or the 'rim-like/membranous' patterns are frequently detected by indirect immunofluorescence on HEp-2 cells in patients with primary biliary cirrhosis.

AIM

To assess the accuracy of multiple nuclear dot and rim-like/membranous antinuclear antibodies for the diagnosis of primary biliary cirrhosis.

METHODS

Sera from 4371 consecutive patients referred to our laboratory were analysed under code for antinuclear antibodies testing by indirect immunofluorescence on HEp-2 cells.

RESULTS

Review of the clinical records of the 4371 patients allowed identification of 101 patients with antimitochondrial antibody-positive primary biliary cirrhosis and 22 with antimitochondrial antibody-negative variant. Multiple nuclear dot and/or rim-like/membranous patterns were found in 59 (1.3%) of the 4371 patients: 31 antimitochondrial antibody-positive primary biliary cirrhosis, 17 antimitochondrial antibody-negative primary biliary cirrhosis and 11 non-primary biliary cirrhosis. The specificity for primary biliary cirrhosis of both the antinuclear antibodies pattern was 99%. Positive predictive value and likelihood ratio for a positive test were 86% (95% CI: 72.7-94) and 221 (95% CI: 91.7-544) for multiple nuclear dot, 79% (95% CI: 62.2-90.1) and 132 (95% CI: 56.8-312.7) for rim-like/membranous, respectively.

CONCLUSIONS

Multiple nuclear dot and rim-like/membranous antinuclear antibodies are rare findings. Their positivity strongly suggests the diagnosis of primary biliary cirrhosis, irrespective of antimitochondrial antibody status. The high specificity for primary biliary cirrhosis makes them a useful diagnostic tool especially in antimitochondrial antibody-negative patients.

[Seropositivity for Chlamydia pneumoniae in patients with primary biliary cirrhosis]

INTRODUCTION

Primary biliary cirrhosis (PBC) is a chronic cholestatic liver disease characterized by inflammatory injury and bile duct destruction. Recent studies suggest that Chlamydia pneumoniae could be associated with the development of PBC. The aim of this study was to determine the seroprevalence of C. pneumoniae in a cohort of patients with PBC.

PATIENTS AND METHODS

The presence of IgG antibodies against C. pneumoniae was investigated in 46 patients with PBC and in 105 subjects without cirrhosis.

RESULTS

Twenty-one patients (46%) with PBC had antibodies against C. pneumoniae compared with 74 subjects (71%) in the control group (OR = 0.6; 95% CI, 0.3-1.2; p = NS). Subanalysis of the PBC group showed that patients with C. pneumoniae antibodies had a higher frequency of advanced Child-Pugh stages (24% A, 52% B and 24% C vs 64% A, 32% B and 4% C; p = 0.01), a higher score on the Mayo Clinic Prognostic Index (7.8 +/- 2.1 vs 5.6 +/- 1.2; p = 0.004), a higher frequency of ascites (29% vs 4%; OR = 9.6; 95% CI, 1-87; p = 0.02), higher total bilirubin levels (4.5 +/- 2.5 mg/dl vs 2.4 +/- 4.3 mg/dl, p = 0.001) and lower serum albumin levels (2.6 +/- 0.9 g/dl vs 3.3 +/- 0.6 g/dl, p = 0.02).

CONCLUSION

No association was found between C. pneumoniae infection and PBC in this study. An association was found between the severity of PBC and C. pneumoniae, which may suggest a deleterious effect of C. pneumoniae infection or a predisposition in advanced stages of PBC to acquire infection with this microorganism.

Role of auto-antibodies for the diagnosis of chronic cholestatic liver diseases

Auto-antibodies are an integral part of the diagnostic armentarium in chronic cholestatic liver disorders, such as primary sclerosing cholangitis (PSC), primary biliary cirrhosis (PBC),auto-immune cholangitis, or overlap syndromes among these disorders. However, care should be taken not to overestimate the diagnostic specificity. Auto-antibodies to mitochondrial antigens(AMAs) with reactivity to the E2 subunit of the pyruvate dehydrogenase complex represent the hallmark antibody for the diagnosis of PBC, whereas antinuclear antibodies (ANAs)with low disease specificity are found in up to 50% of these sera. Antibodies that recognize nuclear envelope proteins exert a similarly high diagnostic specificity as AMA in PBC but occur at a rather low prevalence. The role of auto-antibodies is less well-studied for patients with PSC, but there is growing evidence that only antineutrophil cytoplasmic antibodies(ANCAs) are of relevant diagnostic significance. In contrast, auto-antibodies-particularlyAMAs-do not contribute to the diagnosis of auto-immune cholangitis, whereas ANCAs,ANAs, smooth muscle antibodies, and AMAs are of varying significance in PBC-auto-immune hepatitis (AIH) or PSC-AIH overlap syndromes. It has been widely accepted that the course of the auto-antibody serum end point titers are not suited for the clinical management of patients with chronic cholestatic liver disorders. Additionally, auto-antibodies in these disorders usually do not contribute to the immunopathogenesis of the disease.

Gastric electrical stimulation in gastroparesis: where do we stand?

Gastroparesis is a chronic disabling condition of impaired gastric motility that results in decreased quality of life. Currently available medical therapy consists of prokinetic and/or antiemetic therapy, dietary modifications, and nutritional supplementation. For patients with medication-resistant gastroparesis a non-pharmacological therapy, gastric electric stimulation, has evolved over the last decade. Based on the frequency of the electrical stimulus, gastric electric stimulation can be classified into low- and high-frequency gastric electric stimulation. The first method aims to normalize gastric dysrhythmia and entrain gastric slow waves and accelerates gastric emptying, whereas high-frequency gastric electric stimulation is unable to restore normal gastric emptying, but nevertheless stunningly reduces symptoms, such as nausea and vomiting, re-establishes quality of life, nutritional state in all patients, and metabolic control in patients with diabetic gastroparesis. Gastric electric stimulation presents a new possibility in the treatment of gastroparesis.

Rapid-onset primary biliary cirrhosis resembling drug-induced liver injury

A 54-year-old woman was admitted to our hospital because of acute liver injury. Since she had a history of having used a diet product, drug-induced liver injury (DILI) was initially considered. However, the patient was subsequently diagnosed as suffering from primary biliary cirrhosis (PBC) based on the findings of liver histology and serum anti-mitochondrial antibody positivity. Overlap syndrome between PBC and autoimmune hepatitis (AIH) was also suspected, however, serum levels of aspartate aminotransferase, alanine aminotransferase and alkaline phosphatase became normal three months later, after treatment with combination therapy comprising ursodeoxycholic acid plus bezafibrate. We therefore concluded that the liver disease in this patient was actually PBC, but that it resembled overlap syndrome or DILI. In cases of PBC, a rapid onset, as frequently seen in the case of DILI, viral hepatitis or AIH, is not common. We herein report a rare case of PBC which resembled DILI.

Primary biliary cirrhosis is characterized by IgG3 antibodies cross-reactive with the major mitochondrial autoepitope and its Lactobacillus mimic

The serological hallmark of primary biliary cirrhosis (PBC) is the presence of pyruvate dehydrogenase complex E2 subunit (PDC-E2) antimitochondrial antibodies (AMAs). Anti-PDC-E2 antibodies cross-react specifically with mycobacterial hsp65, and we have demonstrated that the motif SxGDL[ILV]AE shared by PDC-E2(212-226) and hsp's is a cross-reactive target. Having found that this same motif is present only in beta-galactosidase of Lactobacillus delbrueckii (BGAL LACDE), we hypothesized that this homology would also lead to cross-reactivity. The mimics were tested via ELISA for reactivity and competitive cross-reactivity using sera from 100 AMA-positive and 23 AMA-negative PBC patients and 190 controls. An Escherichia coli (ECOLI) PDC-E2 mimic that has been pathogenetically linked to PBC but lacks this motif has been also tested. Anti-BGAL(266-280) LACDE antibodies were restricted to AMA-positive patients (54 of 95, 57%) and belonged to immunoglobulin (Ig) G3. Of the 190 controls, 22 (12%; P < .001) had anti-BGAL(266-280) antibodies, mainly of the IgG4 subclass. ECOLI PDC-E2 reactivity was virtually absent. BGAL(266-280)/PDC-E2(212-226) reactivity of the IgG3 isotype was found in 52 (52%) AMA-positive PBC patients but in only 1 of the controls (P < .001). LACDE BGAL(266-280)/PDC-E2(212-226) reactivity was due to cross-reactivity as confirmed via competition ELISA. Antibody affinity for BGAL(266-280) was greater than for PDC-E2 mimics. Preincubation of a multireactive serum with BGAL(266-280) reduced the inhibition of enzymatic activity by 40%, while marginal effect (12%) or no effect (2%) was observed in human or ECOLI PDC-E2 mimics. In conclusion, IgG3 antibodies to BGAL LACDE cross-react with the major mitochondrial autoepitope and are characteristic of PBC.

[Primary biliary liver cirrhosis and overlap syndrome. Diagnosis and therapy]

Primary biliary cirrhosis represents a chronic cholestatic liver disease of unknown etiology. It primarily affects females, is associated with extrahepatic immune-mediated syndromes, shows an immunogenetic association with HLA DR8, and displays serum autoantibodies, which makes an autoimmune etiology likely. The diagnosis is reached in patients with elevated alkaline phosphatase, gamma glutamyl transferase and bilirubin levels who exhibit normal bile ducts upon ultrasound examination, and in whom specific antimitochondrial autoantibodies are detectable. Half of all PBC patients additionally show specific antinuclear autoantibodies. Immunosuppressive therapy is ineffective; steroids, transplant immunosuppressants, colchicine, d-penicillamine and methotrexate are of limited clinical benefit. Ursodeoxycholic acid has few side effects and leads to a biochemical response and a delay of disease progression in most cases. When ursodeoxycholic acid therapy is ineffective an overlap syndrome with autoimmune hepatitis can be present, which can respond to steroid treatment. The only curative option is liver transplantation which should be considered when bilirubin levels exceed 100 microM/l.

Primary biliary cirrhosis: an infectious disease caused by Chlamydia pneumoniae?

BACKGROUND/AIMS

The etiology and pathogenesis of primary biliary cirrhosis (PBC) remain elusive. Both an infectious etiology and molecular mimicry have been implicated. The aim is to study the prevalence of Chlamydial antigens and RNA in the liver tissue of patients with PBC.

METHODS

We compared the prevalence of Chlamydial antigen and RNA in 25 explants with PBC who underwent orthotopic liver transplantation with 105 explanted livers from other chronic liver disease. We also studied 14 liver biopsies from patients with early stages of PBC. Donor livers were also studied.

RESULTS

In all 39 patients with PBC, Chlamydia pneumoniae antigens were present but not Chlamydia trachomatis, and only 9/105 (8.5%) of patients in the other categories were positive (P<0.01) for C. pneumoniae. Eight explanted PBC livers were tested for C. pneumoniae 16S RNA by in situ hybridization and were positive.

CONCLUSIONS

The presence of C. pneumoniae antigen and RNA in liver tissue of patients with PBC suggests that C. pneumoniae antigen may trigger an immune response based on molecular mimicry.

Antimitochondrial and other autoantibodies

Primary biliary cirrhosis (PBC) is characterized by the presence of high-titer disease specific autoantibodies directed against mitochondrial antigens (AMA) of the inner mitochondrial membrane, that are members of the 2-oxo acid complex. Among numerous other autoantibodies found in PBC the focus of ongoing studies is on the PBC-specific anti-nuclear antibodies, that are of diagnostic and clinical relevance since they can be used as a 'positive tool' in the diagnosis of AMA-negative PBC while at the same time identifying a subgroup of patients with more advanced liver disease.

Capillarization of hepatic sinusoid by liver endothelial cell-reactive autoantibodies in patients with cirrhosis and chronic hepatitis

The special features of liver sinusoidal endothelium (LSE) are crucial for normal liver physiology. Cirrhotic livers, especially in primary biliary cirrhosis (PBC), are characterized by transformation of the LSE into a continuous, vascular type. The transformation is important for disease progression and explains some of the pathological hallmarks of the cirrhotic liver. Here, we investigated the presence of liver sinusoidal endothelial cell (LSEC)-reactive autoantibodies (Abs) in the sera of patients with autoimmune liver diseases, and assessed the ability of these Abs to transform LSE into vascular endothelium. Compared to healthy individuals (9%), significantly higher numbers of patients with PBC (59%; P < 0.001) and autoimmune hepatitis (AIH) (32%; P < 0.05) had Abs against LSECs. Incubation of primary LSEC cultures with F(ab')(2) fragments of anti-LSEC Abs isolated from sera of patients with PBC and AIH, induced 1) cell surface expression of vascular endothelium-associated markers, CD31, and factor VIII-related antigen; 2) significant production of fibronectin, laminin and collagen type IV; 3) loss of fenestrae, formation of tight junctions and Weibel-Palade bodies. Deposition of immunoglobulins on LSECs were found in liver biopsies of AIH and PBC patients. Thus, anti-LSEC autoAbs transform LSE into a vascular type and may therefore play an important role in the development of hepatocellular failure and portal hypertension in PBC and AIH patients.

Antinuclear antibodies specific for primary biliary cirrhosis

The serological hallmark of primary biliary cirrhosis (PBC) is the presence of antimitochondrial antibodies. However, antinuclear antibodies (ANA) are also detectable in approximately 50% of subjects with PBC. Most clinical laboratories use indirect immunofluorescence microscopy to detect ANA and two labeling patterns that predominate in PBC are 'punctate nuclear rim' and 'multiple nuclear dots.' Work over the past several years has shown that antibodies giving these patterns most often recognize nuclear pore membrane protein gp210 and nuclear body protein sp100, respectively. These ANA are highly specific for PBC and detected in approximately 25% of patients. Less frequently, ANA apparently unique to PBC recognize other proteins of the nuclear envelope and nuclear bodies. While antibodies against gp210, sp100 and some other nuclear proteins are very specific to PBC and may therefore be useful diagnostic markers, their connection to pathogenesis remains to be elucidated.

Accumulating CD57 + CD3 + natural killer T cells are related to intrahepatic bile duct lesions in primary biliary cirrhosis

BACKGROUND

Some populations of extrathymic T cells including natural killer T (NKT) cells are involved in autoimmune diseases. In particular, a deficiency of NKT cells has been implicated in human systemic sclerosis. Primary biliary cirrhosis (PBC) is an autoimmune liver disease characterized by the selective destruction of intrahepatic small bile ducts and the formation of granulomas. It is generally believed that cellular immune mechanisms, particularly T cells, cause the bile duct damage in PBC.

METHODS

In this study, to investigate the unique population of extrathymic T cells in PBC, we examined the T cell receptor (TCR) V alpha 24-J alpha Q gene and CD57 + CD3 + cells corresponding to the major genotype and one of the phenotypes of NKT cells, respectively.

RESULTS

By reverse transcription-polymerase chain reaction (RT-PCR), amplicons of the V alpha 24-J alpha Q gene fragment in liver tissues of PBC were found to be similar to those of control diseased livers, demonstrating that there was no distinct deficiency of V alpha 24-J alpha Q + NKT cells in PBC. Immunohistochemistry for CD57 and CD3 revealed the CD57 + CD3 + cells to be distributed in portal tracts and hepatic parenchyma in all cases studied, but the numbers of these cells were increased within portal tracts in PBC, in particular around injured interlobular bile ducts, compared to other diseased and normal livers.

CONCLUSION

This indicates that an immune disturbance induced by a selective reduction of V alpha 24-J alpha Q + NKT cells is unlikely to occur in PBC. Inversely, it can be postulated that auto aggressive CD57 + CD3 + NKT cells are recruited to regulate the altered immunity of the periductal microenvironment in PBC.

Tumor necrosis factor-alpha and interferon-gamma directly impair epithelial barrier function in cultured mouse cholangiocytes

BACKGROUND/AIMS

In primary biliary cirrhosis (PBC), cytokines from CD4+ T lymphocytes were suggested to contribute to the intralobular bile duct damage together with cellular immunity by CD8+ T lymphocytes. Recently, we reported that immunolocalization of 7H6--a tight junction (TJ)-associated protein--was significantly diminished in cholangiocytes in the PBC liver. In this study, we examined the direct effects of several cytokines--tumor necrosis factor-alpha (TNF-alpha), interferon-gamma (IFN-gamma), interleukin-2 and 4 (IL-2 and 4)--on TJ in immortalized mouse cholangiocytes. Moreover, we examined the inhibitory effect of ursodeoxycholic acid (UDCA) on cytokine-induced changes in paracellular permeability.

METHODS

Barrier function of TJ was evaluated by measuring transepithelial electrical resistance (TER) and 3H-inulin flux. We also performed immunostaining and immunoblotting for TJ-associated proteins--claudin-1 and -3, occludin, zonula occluden-1 (ZO-1) and 7H6.

RESULTS

TNF-alpha and IFN-gamma, but neither IL-2 nor IL-4, significantly decreased TER (P < 0.005). 3H-inulin flux studies confirmed IFN-alpha-induced increases in paracellular permeability of cholangiocytes (P < 0.001). In immunostaining and immunoblotting studies, TJ-associated proteins were well preserved in TNF-alpha- or IFN-gamma-treated cells. Ursodeoxycholic acid has been found to have no inhibitory effect on increased paracellular permeability induced by TNF-alpha or IFN-gamma.

CONCLUSION

These findings show that TNF-alpha and IFN-gamma disrupt barrier function of TJ in cholangiocytes without major structural changes to TJ and suggest that disruption of TJ function and subsequent leakage of the bile constituents may influence the aggravation of cholestasis in PBC.

The immunology of primary biliary cirrhosis: the end of the beginning?

The chronic liver disease primary biliary cirrhosis (PBC) is characterised by autoreactive B-cell and T-cell responses directed against mitochondrial antigens. In recent years these responses have been extensively characterised and the principal PBC associated autoantigen identified as pyruvate dehydrogenase complex (PDC). The identification of anti-PDC responses (present in over 95% of PDC patients) has given rise to important questions pertinent to our understanding of the pathogenesis of PBC. What specific role to anti-PDC responses play in target cell damage? How and why does immune tolerance break down to as highly conserved and ubiquitously expressed self-antigen as PDC? Why does breakdown in tolerance to an antigen present in all nucleated cells result in damage restricted to the intra-hepatic bile ducts? In attempting to answer these key questions we have, in this review, proposed a unifying hypothesis for the pathogenesis of PBC.

Pyruvate dehydrogenase specific T cells in primary biliary cirrhosis show restricted antigen recognition sites

BACKGROUND/AIMS

The aim was to characterise the antigen recognition sites of the variable T cell receptor alpha-chain (TCRAV) and beta-chain (TCRBV) of T cells specific to the pyruvate dehydrogenase (PDC) in primary biliary cirrhosis.

METHODS

In 21 PDC-specific T cell clones isolated from five patients we analysed TCRAV and TCRBV usage by RT-PCR and sequenced the CDR3 regions.

RESULTS

Preferential expression of the TCR elements BV6 (6 clones), BV12 (4 clones) and BV1 (3 clones), and frequent usage of the joining elements JB2.3 and JB2.1 were seen. Analysis of the alpha chain revealed rearrangement of AV2 in 7 clones (35%) and AV7 in 3 clones, however, distribution of the joining elements was heterogenous and no common sequence motifs were detected. Evaluation of the physicochemical properties of the beta-chain demonstrated a positive charge at position P4 in several clones of two patients and a hydrophobic residue at position P5 in two different patients. Further, a conserved glycine at position P7 and neutral residues at positions P6 and P8 were frequently detected.

CONCLUSIONS

Our data define TCR variable region restriction and preferred CDR3 features of PDC-specific T cells and support the notion that few relevant epitopes on the PDC complex are recognised by selected T cells.

The "electrical way" to cure gastroparesis

The treatment of gastroparesis recently received a heavy blow from the restrictions on the use of the prokinetic drug cisapride, but, fortunately, at the same time, a nonpharmacological approach, such as gastric electrical stimulation, came up again with new techniques. After an ultra-decennial experimentation with a large variety of electrical stimuli delivered to the gastric wall of animals and patients with gastroparesis, three principal methods are available at the moment: gastric electrical pacing, high-frequency gastric electrical stimulation, and sequential neural electrical stimulation. The first method aims to reset a regular slow-wave rhythm, but is unable to re-establish efficient contractions and a normal gastric emptying. High-frequency gastric electrical stimulation, although inadequate to restore a normal gastric emptying, nevertheless strikingly improves the dyspeptic symptoms, such as nausea and vomiting, giving the patients a better quality of life and a more satisfactory nutritional status. The last method, neural electrical gastric stimulation, consists of a microprocessor-controlled sequential activation of a series of annular electrodes which encircle the distal two thirds of the stomach and induce propagated contractions causing a forceful emptying of the gastric content. The latter method is the most promising, but it has so far only been tested in animals and would need to be tested in patients with gastroparesis before it can be used as a solution for this disease. All the aforementioned clinical studies, however, are not controlled and nearly all were published in abstract form. Therefore, further controlled trials are needed to establish which of these techniques is more useful for the treatment of gastroparesis.

Gastric stimulation: influence of electrical parameters on gastric emptying in control and diabetic rats

BACKGROUND

The aim of this study was to test the effect of different pulse frequencies and amplitudes during gastric stimulation (GS) on gastric emptying in the rat.

METHODS

GS was performed in 2 groups of laparotomized rats: healthy control animals, and rats with acute diabetes. The effects of four pulse frequencies (0.5, 1, 10, 20 Hz) and three pulse amplitudes (5, 20, 40 mA) were tested. The volumes emptied from the stomach after the oro-gastric instillation of a nutrient solution were compared to those obtained in animals without GS. Intragastric pH values were assessed under basal conditions and after GS.

RESULTS

In both groups, GS increased emptied volumes compared to conditions without stimulation (p < 0.05) for pulse frequencies above 0.5 Hz. Increases in pulse frequencies accelerated gastric emptying (p < 0.01) with a plateau at around 10 Hz. The increase in pulse amplitudes resulted in larger emptied volumes only when the pulse frequency was 1 Hz (p < 0.04) while the opposite effect was observed at 20 Hz (p < 0.04). The most effective combinations to enhance gastric emptying compared to baseline conditions were 10 Hz with 5 or 20 mA. The overall effect of GS on gastric emptying compared to baseline conditions without stimulation, was greater in diabetic than in controls rats (p < 0.05). During stimulation, intragastric pH values were not different from basal conditions during fasting or after a meal in control and diabetic rats.

CONCLUSIONS

Although both pulse frequency and amplitude should be considered during GS, frequency appears to be the most critical point. The possibility of increasing gastric emptying by electrical stimulation in diabetic rats suggests potential clinical applications for this method.

Turner syndrome associated with acquired von Willebrand disease, primary biliary cirrhosis, and inflammatory bowel disease

We report a unique case of Turner syndrome associated with acquired von Willebrand disease (AvWD), primary biliary cirrhosis (PBC), and inflammatory bowel disease (IBD). During 7 years of close follow-up, the patient presented with multiple major episodes of upper and lower gastrointestinal bleeding caused by different pathogenic mechanisms, such as IBD, AvWD, gastric varices, and thrombocytopenia. AvWD mimicking familial vWD type III on laboratory testing was most probably triggered by autoimmune mechanism associated with PBC. Therapy of PBC with ursodeoxycholic acid (UDCA) resulted in significant decrease of liver enzymes followed by normalization of vWF and FVIII levels. Portosystemic shunt placement with ligation of gastric varices improved hypersplenism and severe thrombocytopenia and led to clinical stability for more than 24 months. The clinicopathological features of these disorders and of the recurrent bleeding episodes are discussed in the text along with a review of the literature.

Autoimmune hepatitis associated with bile duct injury resembling chronic non-suppurative destructive cholangitis

Autoimmune hepatitis (AIH) and primary biliary cirrhosis (PBC) are representative autoimmune liver diseases in which hepatocytes and intrahepatic bile ducts, respectively, are selectively damaged by autoimmune mechanisms. Bile duct injury and loss is characteristic of PBC and chronic non-suppurative destructive cholangitis (CNSDC), in particular, is a histological hallmark of PBC. In this report, we present an unusual case of AIH accompanied by CNSDC-like bile duct injury in a 46-year-old woman. The patient's serum aminotransferase level was abnormally high. The serum levels of alkaline phosphatase, gamma-GTP and IgG were also elevated, but the IgM level was within normal limits. The titer of antismooth muscle antibody (SMA) was 1:80, while antinuclear autoantibody (ANA) and the M2 fraction of antimitochondrial antibody (AMA) were both negative. Liver biopsy disclosed CNSDC-like bile duct injuries and severe interface hepatitis and lobular hepatitis with perivenular zonal necrosis were observed. The aggregate score of the International Autoimmune Hepatitis Group corresponded to the category of probable AIH. Immunohistochemically, histocompatibility leukocyte antigen-DR, which is aberrantly expressed in the damaged bile ducts of PBC, was not found in the injured bile ducts of this case. Laboratory data were much improved by treatment with prednisone, but ursodeoxycholic acid was not effective. Although the possibility of an overlapping syndrome of AIH- and AMA-negative PBC could not be excluded, this case was diagnosed as AIH with CNSDC-like bile duct lesions.

Solution structure and dynamics of the lipoic acid-bearing domain of human mitochondrial branched-chain alpha-keto acid dehydrogenase complex

The lipoyl-bearing domain (LBD) of the transacylase (E2) subunit of the branched-chain alpha-keto acid dehydrogenase complex plays a central role in substrate channeling in this mitochondrial multienzyme complex. We have employed multidimensional heteronuclear NMR techniques to determine the structure and dynamics of the LBD of the human branched-chain alpha-keto acid dehydrogenase complex (hbLBD). Similar to LBD from other members of the alpha-keto acid dehydrogenase family, the solution structure of hbLBD is a flattened beta-barrel formed by two four-stranded antiparallel beta-sheets. The lipoyl Lys(44) residue resides at the tip of a beta-hairpin comprising a sharp type I beta-turn and the two connecting beta-strands 4 and 5. A prominent V-shaped groove formed by a surface loop, L1, connecting beta 1- and beta 2-strands and the lipoyl lysine beta-hairpin constitutes the functional pocket. We further applied reduced spectral density functions formalism to extract dynamic information of hbLBD from (15)N-T(1), (15)N-T(2), and ((1)H-(15)N) nuclear Overhauser effect data obtained at 600 MHz. The results showed that residues surrounding the lipoyl lysine region comprising the L1 loop and the Lys(44) beta-turn are highly flexible, whereas beta-sheet S1 appears to display a slow conformational exchange process.

Antimitochondrial antibody profiles: are they valid prognostic indicators in primary biliary cirrhosis?

OBJECTIVE

Retrospective studies have reported that subtypes of antimitochondrial antibodies (AMAs) discriminate between a benign and a progressive course in patients with primary biliary cirrhosis (PBC). Four AMA profiles (A-D) were defined: profiles A and B associated with a benign course and C and D with a progressive course. We aimed to confirm whether AMA profiles predict prognosis in a large sample of North American patients with PBC.

METHODS

Stored pretreatment sera from patients with PBC from two centers were tested for AMA profiles using standard techniques. Proportions of patients in each profile group reaching the endpoints of liver transplantation or death from liver disease were compared. Kaplan-Meier curves were constructed comparing AMA profiles.

RESULTS

All 472 patients studied had AMA positive, biopsy-confirmed PBC. Mean age at diagnosis was 53 yr, 90% were female, mean follow-up was 7.6 yr (range = 0.5-23), and 51% received ursodeoxycholic acid for >6 months. Profile A was not detected; 16.7% had profile B; 51.1%, profile C; and 32.2%, profile D. Duration of follow-up was comparable among the different profile groups. The proportions of patients reaching endpoints of death from liver disease or transplantation did not differ among the AMA profiles. No difference in the Kaplan-Meier curves between the different profile groups was observed (p > 0.05).

CONCLUSION

AMA profiles do not predict prognosis in patients with PBC.

Hepatoimmunology: a perspective

Premises for the subspecialty of hepatoimmunology include the recognition that the liver is a lymphoid organ with unique immunological properties. These properties ensure efficient innate defence against intestinal microbes and toxins, confer a particular capacity for induction of tolerance, and provide for apoptotic disposal of redundant lymphocytes. Pathological responses within the liver are elicited when: (i) hepatotropic viruses (hepatitis virus B and C) escape immune elimination and reside in hepatocytes; (ii) the liver becomes the site of autoimmune responses directed against either hepatocytes (autoimmune hepatitis) or biliary ductules (primary biliary cirrhosis); or (iii) the liver in the course of disposal of drugs generates neoantigens that provoke adverse allergic responses. Recent advances in the understanding of the immunopathogenesis of these entities are reviewed.

Antibodies against homologous microbial caseinolytic proteases P characterise primary biliary cirrhosis

BACKGROUND/AIMS

Antibodies to caseinolytic protease P(177-194) (ClpP(177-194)) of the proteolytic subunit of the Clp complex of Escherichia coli (E. coli) are uniquely present in primary biliary cirrhosis (PBC). Molecular mimicry between the regulatory subunit ClpX and the principal T-cell epitope of pyruvate dehydrogenase complex (PDC-E2) in PBC, has been proposed to account for this. Since ClpP is highly conserved among bacteria we investigated whether the micro-organisms triggering these antibodies may be other than E. coli.

METHODS/RESULTS

E. coli ClpP(177-194) is homologous with ClpP peptides of Yersinia enterocolitica (YEREN) and Haemophilus influenzae (HAEIN). Enzyme linked immunosorbent assay (ELISA) reactivity to these peptides was tested in 45 patients with PBC, 44 pathological and 32 healthy controls. Reactivity to at least one of the ClpP peptides was observed in 21 (47%) PBC patients, 5.8% pathological and 3.1% healthy controls (P<0.01 for all). Among these 21 seropositive PBC patients, 15 (71%) reacted to ECOLI ClpP(177-194), alone or in association with YEREN and/or HAEIN peptides, compared to three (14.2%) reactive with YEREN, two (9.5%) with YEREN/HAEIN and one (4.7%) with HAEIN peptide. Simultaneous reactivity to homologous sequences was due to cross-reactivity as confirmed by competition ELISAs.

CONCLUSIONS

The PBC-specificity of anti-microbial ClpP reactivity is confirmed: the questions as to primary trigger(s) and relevance to PBC pathogenesis remain open.

Novel murine autoimmune-mediated liver disease model induced by graft-versus-host reaction and concanavalin A

BACKGROUND AND AIMS

We have previously reported that cluster of differentiation (CD)4+ T cells induced autoimmune liver diseases in mice with graft-versus-host reaction (GVHR) because of major histocompatibility complex (MHC) class II disparity. To analyze the progression of the autoimmune-related mechanism in the liver, concanavalin A (Con A) was injected in mice undergoing GVHR. The aim of this study is to clarify whether Con A deteriorates murine hepatic lesions induced by GVHR, and to elucidate the participation of the cytokines of liver-infiltrating CD4+ T cells.

METHODS

Mice (F1; B6.C-H-2(bm12) x B6) were intravenously injected with B6 T spleen cells. Concanavalin A (15 mg/kg) was administrated 5 days after cell transfer. We examined serum transaminase, antimitochondrial antibodies (AMA), antinuclear antibodies (ANA) and histological changes. Liver-infiltrating CD4+ T cells were sorted and their cytokine mRNA expression was examined by the use of reverse transcription-polymerase chain reaction (RT-PCR).

RESULTS

Graft-versus-host reaction + Con A mice revealed an elevated serum transaminase, elevated AMA and ANA titers, increased periportal cellular infiltration, piecemeal necrosis and bridging necrosis in the liver. In this group, interferon (IFN)-gamma mRNA expression was more elevated than it was in the GVHR mice. However, there was no difference in the expression of interleukin (IL)-10 mRNA between the two groups.

CONCLUSION

The results suggest that Con A deteriorates the GVHR-induced hepatic lesions, and IFN-gamma and IL-10 of CD4+ T cells might be implicated in the progression of autoimmune-related hepatic lesions. This model might offer an aspect for the investigation of progressive mechanisms in T-cell- mediated hepatobiliary injury.