Persistence of gp210 and multiple nuclear dots antibodies does not correlate with recurrence of primary biliary cirrhosis 6 years after liver transplantation

Primary biliary cirrhosis and the nuclear pore complex

Experimental models of autoimmune diseases have led to the conclusion that an immune response to nuclear antigens is a sentinel marker for loss of tolerance and potential tissue damage. Various proteins are targets of antinuclear antibodies in a variety of autoimmune diseases, ranging from systemic rheumatologic disorders to diseases affecting specific organs such as the liver. Autoantibodies against specific nuclear constituents have also been used as probes to understand the structure and the function of the targeted components and their relevance to disease pathogenesis. Approximately a quarter of patients with primary biliary cirrhosis (PBC) have antibodies targeting proteins of the nuclear pore complex (NPC), a multi-protein structure that mediates molecular transport across the nuclear envelope. Autoantibodies against the integral membrane glycoprotein gp210 and nucleoporin p62 appear to be highly specific for PBC, an autoimmune disease characterized by progressive destruction of intrahepatic biliary epithelial cells. This review discusses the diagnostic and clinical relevance of anti-NPC antibodies in PBC and the possibility that this autoimmune response may arise as a result of molecular mimicry.

Antinuclear antibodies as ancillary markers in primary biliary cirrhosis

Antimitochondrial antibodies are the serological hallmark of primary biliary cirrhosis (PBC). Besides antimitochondrial antibodies, the autoantibody profile of PBC includes antinuclear antibodies (ANA) which are detectable by indirect immunofluorescence in up to 50% of PBC patients. Two immunofluorescence patterns are considered 'PBC-specific': the multiple nuclear dots and rim-like/membranous patterns. The target antigens of the multiple nuclear dots pattern have been identified as Sp100 and promyelocytic leukemia protein, whereas the rim-like/membranous pattern is given by autoantibodies recognizing multiple proteins such as gp210, nucleoporin p62 and the lamin B receptor. Other ANA, especially those already known in the rheumatological setting, such as anticentromere, anti-SSA/Ro and anti-dsDNA antibodies, can be frequently found in PBC, often coexisting in the same patient. In this article, we will report on recent progress in the antigenic characterization of ANA in PBC, their detection with both traditional assays and Western blot/ELISA with molecularly defined nuclear antigens, and we will discuss their clinical significance.

Antimitochondrial antibodies and other antibodies in primary biliary cirrhosis: diagnostic and prognostic value

Antimitochondrial antibodies (AMA) are the serologic cornerstone in the diagnosis of primary biliary cirrhosis (PBC), even if they are not detectable in a proportion of patients, notwithstanding the most sensitive and sophisticated technologies used. To fill in the serologic gap in AMA-negative PBC, there is sound evidence to consider antinuclear antibody (ANA) patterns, such as anti-multiple nuclear dots and anti-membranous/rim-like, as PBC-specific surrogate hallmarks of the disease, and their detection can be considered virtually diagnostic. Furthermore, particular ANA specificities, such as anti-gp210, anti-p62, anticentromere antibodies, and anti-dsDNA, may provide additional diagnostic and prognostic information.

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.

Long-term outcome of liver transplantation for autoimmune hepatitis

BACKGROUND

Liver transplantation is the final therapeutic option for about 10% of patients with autoimmune hepatitis (AIH) who do not respond to medical therapy. The aim of this study was to evaluate the long-term outcome in serologically defined subgroups of AIH after transplantation.

METHODS

Pre- and post-transplantation data of 28 patients with AIH transplanted between 1987 and 1999 were retrospectively analyzed and compared with 24 patients, who underwent liver transplantation because of Wilson's disease and glycogen storage disease type 1.

RESULTS

Serological analyses identified patients with AIH type 1 (n = 13), type 2 (n = 5), and type 3 (n = 10). The 5-yr patient survival rate after liver transplantation was 78.2%, which was not significantly different from the control group. Six AIH patients and four control patients required re-transplantation because of initial non-function, chronic rejection or AIH recurrence. Patients transplanted for AIH (88%) had more episodes of acute rejection when compared with patients transplanted for genetic liver diseases (50%). Clinical and histological features of chronic rejection were present in four patients, which did not differ significantly from the controls. Recurrence of AIH was diagnosed in nine patients (32%) based upon the presence of autoantibodies, increased gamma-globulins, steroid dependency, and histological evidence of chronic hepatitis. These combined features were not found in any of the controls.

CONCLUSIONS

Our data do not suggest that AIH subtypes influence prognosis after liver transplantation. Despite a high frequency of acute cellular rejection episodes and disease recurrence, transplantation for AIH has a 5-yr survival rate, which does not differ from that observed in patients transplanted for genetic liver diseases.

Recurrent primary biliary cirrhosis

Liver transplantation remains the only effective treatment for end-stage primary biliary cirrhosis (PBC). It appears now well accepted that the disease recurs in the allograft. The diagnosis of recurrent PBC is made on the basis of a consistent history and demonstrating the histologic features of PBC on liver biopsy and exclusion of other causes of bile duct damage.

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.

Recurrent primary biliary cirrhosis, primary sclerosing cholangitis, and autoimmune hepatitis after transplantation

1. Recurrent primary biliary cirrhosis (PBC) after transplantation is controversial, but most studies support disease recurrence within the graft. 2. Granulomatous destructive cholangitis should be present, and exclusion of acute and chronic rejection, graft-versus-host disease, biliary obstruction, viral hepatitis, and drug effects is mandatory before making a diagnosis of recurrent PBC. 3. Recurrent primary sclerosing cholangitis (PSC) after transplantation is difficult to diagnose because of the lack of a diagnostic gold standard. 4. Well-defined cholangiographic and histological criteria should be present, and exclusion of preservation injury, blood group type incompatibility between donor and recipient, chronic rejection, hepatic arterial occlusion, and viral infection is mandatory before making a diagnosis of recurrent PSC. 5. Most studies support recurrent autoimmune hepatitis (AIH) after transplantation based on clinical, biochemical, serological, and histological criteria. Exclusion of rejection, viral infection, drug effects, and biliary obstruction is mandatory before making a diagnosis of recurrent AIH. 6. Intermediate-term patient and graft survival are excellent for patients with recurrent autoimmune liver diseases within the transplanted liver, but additional studies are required to address the impact of disease recurrence on long-term patient and graft survival.

Autoantibodies against nuclear pore complexes are associated with more active and severe liver disease in primary biliary cirrhosis

BACKGROUND/AIMS

Antibodies against nuclear pore complexes (NPCs) have been detected in primary biliary cirrhosis (PBC), but their clinical relevance is still unsettled.

METHODS

We tested sera from 171 consecutive PBC patients and 230 control subjects (149 with autoimmune or viral liver diseases, 28 with systemic lupus erythematosus, and 53 healthy) by immunoblotting for antibodies against purified human NPCs.

RESULTS

Antibodies to NPCs were detected in 27% of the patients with PBC, were highly specific (97%), and were not associated with antimitochondrial antibodies. Their prevalence was higher in symptomatic patients (36 vs. 16%, P < 0.01) and was associated (P < 0.001) with more severe disease, as assessed by the presence of cirrhosis or its complications (13% prevalence in patients without cirrhosis, 31% in uncomplicated, and 54% in complicated cirrhosis), or by the application of the Mayo prognostic model (12% in the lowest, 21% in the median, 47% in the highest score tertile). Positive patients had higher levels of serum bilirubin (2.2 +/- 3.7 vs. 1.0 +/- 1.1 mg/dl, P < 0.01) and more marked inflammatory infiltrates on liver biopsy (P < 0.05).

CONCLUSIONS

Autoantibodies to NPCs are more prevalent in PBC patients than in controls and are strongly associated with more active and severe disease.

Autoantigens in primary biliary cirrhosis

The automimmune liver disease primary biliary cirrhosis (PBC) is characterised by serum autoantibodies directed at mitochondrial and nuclear antigens (seen in most patients and a subset of patients, respectively). The antimitochondrial antibodies (AMA) characteristic of PBC are directed at members of the 2-oxoacid dehydrogenase components of multienzyme complexes; in particular, the E2 and E3 binding protein (E3BP) components of the pyruvate dehydrogenase complex (PDC). The presence of autoantibodies reactive with PDC-E2 and/or E3BP is strongly predictive of the presence of PBC. Therefore, the detection of these antibodies plays a very important role in the diagnosis of PBC. Originally demonstrated using immunofluorescence approaches, AMA can now be detected by the use of commercially available enzyme linked immunosorbent assays (ELISAs). Although the ELISA based approaches have advantages in terms of laboratory practicality, they are slightly less sensitive for the diagnosis of PBC than immunofluorescence (occasional patients with PBC show reactivity with PDC related antigens not present in the antigen preparations available for use with ELISA). Therefore, immunofluorescence should continue to be available as a complementary diagnostic test for use in occasional patients. In a subset of patients with PBC, autoantibodies are directed at increasingly well characterised nuclear antigens. Antinuclear antibody (ANA) positive patients are typically AMA negative. There are no significant differences in disease phenotype between AMA positive and AMA negative groups. At present, the clinical detection of ANA is mostly by Hep2 immunofluorescence, although ELISA kits for individual nuclear antigens are increasingly becoming available.

Recurrent primary biliary cirrhosis

Transplantation has become the accepted form of therapy for patients with end-stage liver disease. The diagnosis of recurrent disease in the allograft has been a matter of controversy, partly because of the difficulties in making the diagnosis in the allograft situation. The conventional criteria for diagnosing PBC may be inappropriate and there are many causes of bile duct damage in the graft. That the PBC-specific autoantibodies [such as antimitochondrial antibody (AMA) and gp-210] persist after transplantation is universally found, and some have reported the aberrant distribution of E2 in the allograft that is typical of PBC in the native liver, whether or not there is histological evidence of PBC recurrence. Most studies now accept that histological features of PBC, such as granulomatous bile duct damage, ductopenia and biliary-type fibrosis, may be found in the allograft; the histological features of PBC are variable and do not mirror the liver tests. The rate of recurrence increases with time, so that by 10 years, recurrence may be found in 30-50% of biopsies. There are no clear factors which identify those at risk of recurrence, but the pattern and degree of immunosuppression may be implicated. Cirrhosis has only rarely been reported. In the medium term, recurrence of PBC has little clinical impact. Ursodeoxycholic acid is used in some centres but there is no clear evidence for benefit.

Autoimmune tests in primary biliary cirrhosis

Primary biliary cirrhosis (PBC) is characterized by an immune mediated, irreversible destruction of the small intrahepatic bile ducts leading to progressive liver cirrhosis and frequently to liver failure. The course of the disease is variable and an early diagnosis is desirable to identify individuals with rapidly progressing disease, to initiate adequate therapeutic measures and to evaluate the necessity of liver transplantation. Serological tests represent the single most important diagnostic feature of PBC because liver histology, biochemistry, or clinical syndrome alone are not reliable in this respect. The molecular definition of the autoantigen targets of antimitochondrial antibodies (AMA) has resulted in the development of reproducible and effective serological testing strategies. AMA directed against the ketoacid dehydrogenase complex are highly disease-specific but not directed against liver-specific target structures. Despite a high disease specificity, their usefulness for predicting the course of disease, the timing of liver transplantation, or disease recurrence after transplantation is limited. The realization that about 5% of patients with PBC do not display AMA has led to the identification of PBC-specific antinuclear autoantibodies directed against the nuclear pore complex and other targets. The overlap of PBC with autoimmune hepatitis and primary sclerosing cholangitis represents a diagnostic challenge in which autoantibody determinations play a central role and contribute to the administration of suitable treatment options.