Antinuclear antibodies directed to a 200-kilodalton polypeptide of the nuclear envelope in primary biliary cirrhosis. A clinical and immunological study of a series of 150 patients with primary biliary cirrhosis

Role of autoantibodies in the clinical management of primary biliary cholangitis

Primary biliary cholangitis (PBC) is a chronic cholestatic liver disease characterized by immune-driven destruction of small intrahepatic bile ducts leading a proportion of patients to hepatic failure over the years. Diagnosis at early stages in concert with ursodeoxycholic acid treatment has been linked with prevention of disease progression in the majority of cases. Diagnosis of PBC in a patient with cholestasis relies on the detection of disease-specific autoantibodies, including anti-mitochondrial antibodies, and disease-specific anti-nuclear antibodies targeting sp100 and gp210. These autoantibodies assist the diagnosis of the disease, and are amongst few autoantibodies the presence of which is included in the diagnostic criteria of the disease. They have also become important tools evaluating disease prognosis. Herein, we summarize existing data on detection of PBC-related autoantibodies and their clinical significance. Moreover, we provide insight on novel autoantibodies and their possible prognostic role in PBC patients.

Novel Anti-Hexokinase 1 Antibodies Are Associated With Poor Prognosis in Patients With Primary Biliary Cholangitis

INTRODUCTION

Antibodies to hexokinase 1 (HK1) and kelch-like 12 (KLHL12) have been identified as potential biomarkers in primary biliary cholangitis (PBC), and this study assesses changes of these antibodies over time and if they are associated with clinical outcomes.

METHODS

Two hundred fifty-four PBC patients (93.3% female, 51 ± 12.3 years old) were tested for anti-HK1 and anti-KLHL12, antimitochondrial (AMA), anti-gp210, and anti-sp100 antibodies. One hundred sixty-nine patients were tested twice and 49 three times within 4.2 (0.8-10.0) years. Biochemistry and clinical features at diagnosis, response to therapy, events of decompensation, and liver-related death or transplantation were evaluated.

RESULTS

Anti-HK1 and anti-KLHL2 were detected in 46.1% and 22.8% patients, respectively. AMA were positive in 93.7%, anti-sp100 in 26.4%, and anti-gp210 in 21.3% of patients. Anti-HK1 and anti-KLHL12 positivity changed over time in 13.3% and 5.5% of patients, respectively. Anti-HK1 or anti-KLHL12 were present in 37.5% of AMA-negative patients, and in 40% of AMA, anti-gp210, and anti-sp100 negative. No significant differences were observed between those with or without HK1 and KLHL12 antibodies, but transplant-free survival and time to liver decompensation were significantly lower in patients anti-HK1 positive (P = 0.039; P = 0.04) and in those anti-sp100 positive (P = 0.01; P = 0.007). No changes in survival and events of liver decompensation were observed according to the positivity of AMA, anti-KLHL12, or anti-gp210 antibodies.

DISCUSSION

HK1 and KLHL12 antibodies are present in 40% of PBC patients who are seronegative by the conventional PBC-specific antibodies. The novel antibodies remain rather steady during the course of the disease, and HK1 antibodies are associated with unfavourable outcomes.

The British Society of Gastroenterology/UK-PBC primary biliary cholangitis treatment and management guidelines

Primary biliary cholangitis (formerly known as primary biliary cirrhosis, PBC) is an autoimmune liver disease in which a cycle of immune mediated biliary epithelial cell injury, cholestasis and progressive fibrosis can culminate over time in an end-stage biliary cirrhosis. Both genetic and environmental influences are presumed relevant to disease initiation. PBC is most prevalent in women and those over the age of 50, but a spectrum of disease is recognised in adult patients globally; male sex, younger age at onset (<45) and advanced disease at presentation are baseline predictors of poorer outcome. As the disease is increasingly diagnosed through the combination of cholestatic serum liver tests and the presence of antimitochondrial antibodies, most presenting patients are not cirrhotic and the term cholangitis is more accurate. Disease course is frequently accompanied by symptoms that can be burdensome for patients, and management of patients with PBC must address, in a life-long manner, both disease progression and symptom burden. Licensed therapies include ursodeoxycholic acid (UDCA) and obeticholic acid (OCA), alongside experimental new and re-purposed agents. Disease management focuses on initiation of UDCA for all patients and risk stratification based on baseline and on-treatment factors, including in particular the response to treatment. Those intolerant of treatment with UDCA or those with high-risk disease as evidenced by UDCA treatment failure (frequently reflected in trial and clinical practice as an alkaline phosphatase >1.67 × upper limit of normal and/or elevated bilirubin) should be considered for second-line therapy, of which OCA is the only currently licensed National Institute for Health and Care Excellence recommended agent. Follow-up of patients is life-long and must address treatment of the disease and management of associated symptoms.

Diagnostic value of anti-gp210 antibodies in primary biliary cirrhosis: a case-based review

Primary biliary cirrhosis (PBC) is an autoimmune liver disease characterised by chronic cholestasis usually associated with antimitochondrial antibodies. Moreover, several types of antinuclear antibodies have been associated with primary biliary cirrhosis. We describe an 83-year-old man, in whom the exploration of a chronic cholestasis led to the diagnosis of primary biliary cirrhosis despite negative antimitochondrial antibodies, regarding the presence of anti-gp210 antibodies. Found in 25% of patients, these antinuclear antibodies must be sought before a strong suspicion of primary biliary cirrhosis with antimitochondrial antibodies negative, as they are highly specific of the disease. They are generally associated with a more aggressive form of PBC.

Molecular diagnostics of primary biliary cirrhosis

BACKGROUND

Primary biliary cirrhosis (PBC) is an autoimmune liver disease of unknown etiology characterized by the presence of antimitochondrial antibodies (AMA) in 90 - 95% of patients. AMA are directed against members of 2-oxo-acid dehydrogenase complex, including mainly the E2 subunit of pyruvate dehydrogenase, the E2 subunit of branched chain 2-oxo-acid dehydrogenase complex and the E2 subunit of the oxoglutarate dehydrogenase complex. Apart from AMA, PBC is characterized by the presence of PBC-specific antinuclear antibodies (ANA). The molecular targets of these PBC-specific ANA have been characterized as gp210, lamin B receptor, nucleoporin 62, sp100 and promyelocytic leukemia proteins.

OBJECTIVE

To discuss the molecular diagnostics of PBC in the context of AMA and PBC-specific ANA detection by the use of conventional and 'new' novel technologies.

METHODS

Critical analysis of all published data regarding PBC serology between 1985 and 2007 was performed in order to suggest a diagnostic algorithm for the serological diagnosis of PBC.

RESULTS/CONCLUSIONS

AMA are first detected by indirect immunofluorescence (IIF) on frozen sections of rat liver, kidney and stomach substrates. However, because IIF is time-consuming, labor-intensive and observer-dependent, molecular-based assays such as immunoblot and enzyme-linked immunosorbent assays have been developed with high sensitivity and specificity. Similarly, molecular-based assays have also been developed for the detection of PBC-specific ANA. The latter investigation seems to be of outmost importance because these autoantibodies can be used as a positive tool in the diagnosis of AMA-negative PBC while at the same time identifying a subgroup of PBC patients with more advanced disease. New test systems for the detection of PBC-specific antibodies based on the xMultiple Analyte Profiling Luminex methodology seems to be the future in molecular diagnostics of PBC as it was expected first to decrease the cost and second to speed up an accurate serological profile, although they may decrease further the proportion of AMA-negative PBC cases.

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.

Epitope-specific anti-nuclear antibodies are expressed in a mouse model of primary biliary cirrhosis and are cytokine-dependent

Although the hallmark of primary biliary cirrhosis (PBC) is the presence of anti-mitochondrial antibodies (AMA), a significant number of patients have anti-nuclear antibodies (ANA) directed primarily against two nuclear proteins, gp210 and sp100. In PBC, there are considerable data on the specificity of these anti-nuclear antibodies as well as suggestive evidence that antibodies to gp210 predict a poor outcome. However, a further understanding of the significance of these autoantibodies has been hampered by limitations in accessing human subjects in a preclinical or early asymptomatic stage. To overcome this limitation, we have taken advantage of transgenic mice with abrogated transforming growth factor-β signalling in T cells (dnTGF-βRII) that develop histological features of PBC as well as the same AMA specificity. We studied these mice for serum ANA, including specific autoantibodies against gp210 and sp100. We further examined sera from dnTGF-βRII mice with concurrent deletions of the genes encoding interleukin (IL)-12p35, IL-12p40, IL-23p19, IL-17, IL-6, interferon (IFN)-γ or tumour necrosis factor (TNF)-α. Sera from all the dnTGF-βRII mouse lines contained antibodies against gp210 and sp100. Of significance, mice with germline deletions of the genes encoding IL-12p40, IL-23p19, IL-17, IL-6 and TNF-α had significantly lower titres of anti-gp210 antibodies. These results provide a platform to dissect the mechanisms of gp210 and sp100 autoantibody production in dnTGF-βRII mice as well as to study the possible role of ANA in the pathophysiology of PBC.

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.

High prevalence of primary biliary cirrhosis and disease-associated autoantibodies in Japanese patients with systemic sclerosis

OBJECTIVE

To investigate the prevalence of primary biliary cirrhosis (PBC) and PBC-associated autoantibodies in Japanese systemic sclerosis (SSc) patients.

METHODS

Clinical data from 225 Japanese SSc patients were retrospectively obtained. Serum samples from these patients were examined for PBC-associated autoantibodies, anti-mitochondrial M2 antibodies (AMA), anti-sp100 antibodies (anti-sp100), and anti-gp210 antibodies (anti-gp210) by enzyme-linked immunosorbent assay.

RESULTS

Of 225 patients, 37 (16.4%) had AMA, 13 (5.8%) had anti-sp100, and 3 (1.3%) had anti-gp210. Three patients were positive for both AMA and anti-sp100, and 2 were positive for both AMA and anti-gp210. PBC was found in 22 (9.8%) patients positive for AMA with or without anti-sp100 or anti-gp210, but not in those with anti-sp100 or anti-gp210 without AMA. Furthermore, 13 patients lacking these three antibodies were diagnosed with or suspected of PBC by liver biopsy and/or their clinical manifestation. Multivariable analysis revealed that AMA and anti-centromere antibodies were independently associated with PBC in SSc patients, while anti-sp100 and anti-gp210 were not.

CONCLUSIONS

This study has demonstrated even higher prevalence of both PBC-associated autoantibodies and PBC in the Japanese SSc population than in the Caucasian SSc population. AMA and anti-centromere antibodies are likely to indicate increasing risk of PBC in SSc patients.

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.

Peri-nuclear antibodies correlate with survival in Greek primary biliary cirrhosis patients

AIM: To investigate possible associations of anti-nuclear envelope antibody (ANEA) with disease severity and survival in Greek primary biliary cirrhosis (PBC) patients.

METHODS: Serum samples were collected at diagnosis from 147 PBC patients (85% female), who were followed-up for a median 89.5 mo (range 1-240). ANEA were detected with indirect immunofluorescence on 1% formaldehyde fixed Hep2 cells, and anti-gp210 antibodies were detected using an enzyme linked immunosorbent assay. Findings were correlated with clinical data, histology, and survival.

RESULTS: ANEA were detected in 69/147 (46.9%) patients and 31/147 (21%) were also anti-gp210 positive. The ANEA positive patients were at a more advanced histological stage (I-II/III-IV 56.5%/43.5% vs 74.4%/25.6%, P = 0.005) compared to the ANEA negative ones. They had a higher antimitochondrial antibodies (AMA) titer (≤ 1:160/> 1:160 50.7%/49.3% vs 71.8%/28.2%, P = 0.001) and a lower survival time (91.7 ± 50.7 mo vs 101.8 ± 55 mo, P = 0.043). Moreover, they had more advanced fibrosis, portal inflammation, interface hepatitis, and proliferation of bile ductules (P = 0.008, P = 0.008, P = 0.019, and P = 0.027, respectively). They also died more frequently of hepatic failure and/or hepatocellular carcinoma (P = 0.016). ANEA positive, anti-gp210 positive patients had a difference in stage (I-II/III-IV 54.8%/45.2% vs 74.4%/25.6%, P = 0.006), AMA titer (≤ 1:160/> 1:160 51.6%/48.4% vs 71.8%/28.2%, P = 0.009), survival (91.1 ± 52.9 mo vs 101.8 ± 55 mo, P = 0.009), and Mayo risk score (5.5 ± 1.9 vs 5.04 ± 1.3, P = 0.04) compared to the ANEA negative patients. ANEA positive, anti-gp210 negative patients had a difference in AMA titer (≤ 1:160/> 1:160 50%/50% vs 71.8%/28.2%, P = 0.002), stage (I-II/III-IV 57.9%/42.1% vs 74.4%/25.6%, P = 0.033), fibrosis (P = 0.009), portal inflammation (P = 0.018), interface hepatitis (P = 0.032), and proliferation of bile ductules (P = 0.031). Anti-gp210 positive patients had a worse Mayo risk score (5.5 ± 1.9 vs 4.9 ± 1.7, P = 0.038) than the anti-gp210 negative ones.

CONCLUSION: The presence of ANEA and anti-gp210 identifies a subgroup of PBC patients with advanced disease severity and poor prognosis.

Primary biliary cirrhosis: What do autoantibodies tell us?

Primary biliary cirrhosis (PBC) is a chronic, progressive, cholestatic, organ-specific autoimmune disease of unknown etiology. It predominantly affects middle-aged women, and is characterized by autoimmune-mediated destruction of small- and medium-size intrahepatic bile ducts, portal inflammation and progressive scarring, which without proper treatment can ultimately lead to fibrosis and hepatic failure. Serum autoantibodies are crucial tools for differential diagnosis of PBC. While it is currently accepted that antimitochondrial antibodies are the most important serological markers of PBC, during the last five decades more than sixty autoantibodies have been explored in these patients, some of which had previously been thought to be specific for other autoimmune diseases.

Differential detection of nuclear envelope autoantibodies in primary biliary cirrhosis using routine and alternative methods

Background

Detection of autoantibodies giving nuclear rim pattern by immunofluorescence (anti-nuclear envelope antibodies - ANEA) in sera from patients with primary biliary cirrhosis (PBC) is a useful tool for the diagnosis and prognosis of the disease. Differences in the prevalence of ANEA in PBC sera so far reported have been attributed to the methodology used for the detection as well as to ethnic/geographical variations. Therefore, we evaluated the prevalence of ANEA in sera of Greek patients with PBC by using methods widely used by clinical laboratories and a combination of techniques and materials.

Methods

We screened 103 sera by immunoblotting on nuclear envelopes and indirect immunofluorescence (IIF) using cells and purified nuclei. Reactivities against specific autoantigens were assessed using purified proteins, ELISA, immunoprecipitation and mass spectrometry.

Results

We found higher prevalence of ANEA when sera were assayed by IIF on purified nuclei or cultured cells (50%) compared to Hep2 commercially available slides (15%). Anti-gp210 antibodies were identified in 22.3% and 33% of sera using ELISA for the C-terminal of gp210 or both ELISA and immunoprecipitation, respectively. Immunoblotting on nuclear envelopes revealed that immunoreactivity for the 210 kDa zone is related to anti-gp210 antibodies (p < 0.0001). Moreover, we found that sera had antibodies for lamins A (6.8%), B (1%) and C (1%) and LBR (8.7%), whereas none at all had detectable anti-p62 antibodies.

Conclusions

The prevalence of ANEA or anti-gp210 antibodies is under-estimated in PBC sera which are analyzed by conventional commercially available IIF or ELISA, respectively. Therefore, new substrates for IIF and ELISA should be included by clinical laboratories in the analysis of ANEA in autoimmune sera.

Primary biliary cirrhosis (PBC), PBC autoantibodies, and hepatic parameter abnormalities in a large population of systemic sclerosis patients

OBJECTIVE

To investigate the diagnostic accuracy of antimitochondrial antibodies (AMA), sp100, and gp210 antibodies for primary biliary cirrhosis (PBC) in a large population of patients with systemic sclerosis (SSc); to examine concordance of these antibodies with subsets of SSc. Further, to assess the association of SSc-related antibodies with hepatic parameter abnormalities.

METHODS

We obtained medical records to verify the diagnoses of SSc and PBC. Sera from all participants were examined for the presence of SSc- and PBC-related antibodies, as well as for abnormalities in hepatic parameters.

RESULTS

We examined 817 patients with SSc, of whom 16 (2%) had confirmed PBC. The sensitivity and specificity of AMA by a MIT3 ELISA for PBC were 81.3% and 94.6%, respectively. Sp100 had a sensitivity and specificity of 31.3% and 97.4%, respectively, while gp210 had an even lower sensitivity. We were able to detect all PBC cases using AMA(MIT3) and sp100 as a combined marker, resulting in a significantly improved sensitivity of 100% (p = 0.042) with an incremental decrease in specificity to 92.6%. Independent of AMA or sp100 status, there was an association of anticentromere B (CENP-B) and anti-topoisomerase antibodies (ATA) with higher alkaline phosphatase levels (p = 0.051 and p = 0.003, respectively) while anti-RNA polymerase III (anti-RNAP) was associated with lower alkaline phosphatase levels (p = 0.019) among the patients with SSc.

CONCLUSION

Utilization of AMA(MIT3) and sp100 antibodies as a combined diagnostic marker leads to an improved detection of PBC in patients with SSc. CENP-B and ATA are associated with alkaline phosphatase elevation.

Multiple nuclear dots and rim-like/membranous IgG isotypes in primary biliary cirrhosis

Anti nuclear (ANA) immunomorphological patterns such as multiple nuclear dots (MND) and rim-like/membranous (RL/M) are considered highly specific but little sensitive for primary biliary cirrhosis (PBC) diagnosis. To evaluate frequency and clinical significance of MND and RL/M in PBC patients when investigated at the level of immunoglobulin G isotypes. MND and RL/M pattern have been tested in 141 PBC sera and 230 pathological controls using HEp-2 cells as substrate and anti- total IgG and individual IgG subclasses (IgG1, IgG2, IgG3, IgG4) as specific antisera. One hundred and fourteen of 141 (80%) PBC patients had RL/M or MND pattern when IgG subclasses were used as revealing reagents (vs. 34% when anti total IgG were used, p < 0.0001). The prevalent isotype was IgG1 for RL/M, and IgG2 for MND pattern. None of controls was positive. No clinical differences in terms of severity and outcome of disease have been observed in PBC patients positive for MND and RL/M when investigated with IgG isotypes. The research for RL/M and MND pattern at level of IgG isotype determines a wide gain in terms of sensitivity without a loss of specificity. In Italian PBC patients MND and RL/M pattern did not seem to characterize any subgroup of patients with a poorer prognosis.

Characterization of the antibodies to p62 nucleoporin in primary biliary cirrhosis using human recombinant antigen

Reactivity of sera from patients with primary biliary cirrhosis (PBC) with a 60 kDa component of nuclear pore complexes (NPCs), purified by affinity chromatography on wheat-germ agglutinin (WGA)-Sepharose, was previously detected. Recently, clinical significance of the anti-NPC antibodies in PBC became evident. In the light of recent reports, indicating the correlation of the anti-NPC antibodies with severity and progression of the disease, the characterization of the reactive antigens is becoming essential in the clinical management of patients with PBC. Since accurate autoantibody detection represents one of the fundamental requirements for a reliable testing, we have generated a human recombinant p62 protein and validated an immunoprecipitation assay for the detection of anti-p62. We also demonstrated that the generated human recombinant p62 nucleoporin was modified by N-acetylglucosamine residues. More than 50% of tested PBC sera precipitated (35)S-radioactively labeled p62 recombinant nucleoporin and 40% recognized this recombinant antigen by immunoblotting. We compared the reactivity of PBC sera with rat and human nucleoporin. The incidence of anti-p62 nucleoporin positive PBC sera increased by 15% when human recombinant antigen was used. The titer of autoantibodies in p62-positive PBC samples strongly varied. Preadsorption of the PBC sera with p62 recombinant protein completely abolished their reactivity with the antigen. In conclusion, this study unequivocally proves that autoantibodies reacting with the 60 kDa component of NPCs target p62 nucleoporin and, more importantly, provide a better antigen source for future evaluations of the clinical role of anti-p62 in PBC.

Nuclear envelope protein autoantigens in primary biliary cirrhosis

Antinuclear antibodies are detectable in approximately 50% of subjects with primary biliary cirrhosis (PBC). Most clinical laboratories use indirect immunofluorescence microscopy to detect antinuclear antibodies and two labeling patterns that predominate in PBC are nuclear rim and multiple nuclear dots. Antibodies giving these patterns most often recognize nuclear envelope protein gp210 and nuclear body protein sp100, respectively. Fewer subjects with PBC have autoantibodies giving nuclear rim labeling that recognize nucleoporin p62 and LBR. Gp210 is an integral protein localized to the nuclear pore membranes. Approximately 25% of subjects with PBC have detectable serum anti-gp210 antibodies. The vast majority of anti-gp210 antibodies from patients with PBC recognize a stretch of only 15 amino acids in the carboxyl-terminal tail that faces the nuclear pore complex. Enzyme-linked immunosorbent assays using either recombinant protein expressed in bacteria or chemically synthesized polypeptides have been established to reliably detect these autoantibodies. Although initial studies did not find a correlation between the presence of anti-gp210 antibodies and prognosis in PBC, recent data suggest that the presence of antinuclear envelope protein antibodies correlate with an unfavorable disease course and more rapid progression.

Measurement of gp210 autoantibodies in sera of patients with primary biliary cirrhosis

Primary biliary cirrhosis (PBC) is an autoimmune liver disease with unknown etiology. Patients with PBC have antimitochondrial autoantibodies (AMA) and additionally 50% of them have antinuclear antibodies (ANA). A 15-amino acid fragment (DRKASPPSGLWSPAY) from the C-terminal part of the nuclear envelope glycoprotein gp210 has been proposed as one of the antigenic targets for ANA. The aim of this work was to develop an immunoenzymatic assay for determination of gp210 autoantibodies using for its binding a synthetic pentadecapeptide derived from the gp210 amino acid sequence and to determine level of these autoantibodies in sera of patients with PBC and other autoimmune liver diseases from Poland. Polystyrene microtitration plates coated with the synthetic peptide were consecutively incubated with diluted sera, anti-human immunoglobulin G (IgG) antibodies conjugated with horseradish peroxidase, and with tetramethylobenzidine. Optical density (OD) was read at 450 nm. The mean values of the intra- and interassay of variation coefficients of the test were 4.1 and 10.2%, respectively. Anti-gp210 was detected in 44% of PBC patients and in 6% of patients with PSC. The results were negative for healthy blood donors and other controls. The specificity of the test was 99%, so the anti-gp-210 autoantibodies estimated on DRKASPPSGLWSPAY can be a reliable marker 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.

Optimized detection of circulating anti-nuclear envelope autoantibodies by immunofluorescence

Background

Antinuclear antibodies are useful diagnostic tools in several autoimmune diseases. However, the routine detection of nuclear envelope autoantibodies using immunofluorescence (IF) is not always easy to perform in patients' sera because of the presence of autoantibodies to other nuclear and cytoplasmic components which could mask the characteristic rim-like pattern of nuclear envelope autoantibodies. This is particularly common in sera from patients with primary biliary cirrhosis (PBC), which generaly have high titres of anti-mitochondrial antibodies. Therefore, we have assayed a number of commercial slides and alternative fixation conditions to optimize the detection of anti-nuclear envelope antibodies (ANEA) in PBC sera.

Methods

We have explored the presence of ANEA in 33 sera from patients with established PBC using three different Hep2 commercial slides and home-made slides with HeLa and Hep2 cells fixed with methanol, ethanol, 1% or 4% formaldehyde.

Results

We observed that the IF pattern was related to the cell type used (Hep2 or HeLa), the manufacturer and the cell fixation scheme. When both cell lines were fixed with 1% formaldehyde, the intensity of the cytoplasmic staining was considerably decreased regardless to the serum sample, whereas the prevalence of cytoplasmic autoantibodies was significantly lowered, as compared to any of the Hep2 commercial slide and fixation used. In addition, the prevalence of ANEA was importantly increased in formaldehyde-fixed cells.

Conclusion

Immunofluorescence using appropriately fixed cells represent an easy, no time-consuming and low cost technique for the routine screening of sera for ANEA. Detection of ANEA is shown to be more efficient using formaldehyde-fixed cells instead of commercially available Hep2 cells.

Correlation of initial autoantibody profile and clinical outcome in primary biliary cirrhosis

Although there have been significant advances in understanding the clinical and biochemical features of primary biliary cirrhosis (PBC), there is still a paucity of data on the usefulness of biomarkers as prognostic indicators. This is particularly important at the time of initial diagnosis. Indeed, the widespread use of antimitochondrial antibody testing has led to an earlier diagnosis of asymptomatic PBC and it is difficult to predict which patients will experience a benign versus a rapidly progressive course. To address this issue, we examined a unique population of 127 newly diagnosed patients with PBC during a 15-year period of observation that began in January 1990. Sera from these patients were analyzed for antimitochondrial, antinuclear, and anti-smooth muscle antibodies, and immunoblotting was performed for nuclear pore complex (NPC). The patients were then followed up longitudinally using biochemical liver function tests. No patient was under any medical therapy for PBC at the time of the initial sera collection. Data were analyzed based not only on the clinical features, but also the Mayo score and specific outcome measures, including time to death, need for liver transplantation, and complication free survival. Among patients with early disease, bilirubin increased to >2 mg/dL in the anti-NPC(+) patients (26% vs. 5%, P = .019). Anti-NPC antibodies remained stable or slightly increased over the period of observation. In condusion, anti-NPC identifies patients likely to experience an unfavorable clinical course and more rapid disease progression.

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.

Autoantibodies in autoimmune liver disease

Autoantibodies indicate an immune reactive state, but in liver disease they lack pathogenicity and disease specificity. Antinuclear antibodies, smooth muscle antibodies, antibodies to liver/kidney microsome type 1, antimitochondrial antibodies, and perinuclear antineutrophil cytoplasmic antibodies constitute the standard serological repertoire that should be assessed in all liver diseases of undetermined cause. Antibodies to soluble liver antigen/liver pancreas, asialoglycoprotein receptor, actin, liver cytosol type 1, nuclear antigens specific to primary biliary cirrhosis, and pore complex antigens constitute an investigational repertoire that promises to have prognostic and diagnostic value. These autoantibodies may emerge as predictors of treatment response and outcome. Antibodies to histones, doubled-stranded DNA, chromatin, and lactoferrin constitute a supplemental repertoire, and they support the immune nature of the liver disease. Final diagnoses and treatment strategies do not depend solely on serological markers. Autoantibodies are floating variables, and their behavior does not correlate closely with disease activity. There are no minimum levels of significant seropositivity, especially in children. Over-interpretation is the major pitfall in the clinical application of the serological results. New autoantibodies will emerge as the search for target antigens and key pathogenic pathways continues.

Antibody titer to gp210-C terminal peptide as a clinical parameter for monitoring primary biliary cirrhosis

BACKGROUND/AIMS

The presence of antibodies to the 210-kDa glycoprotein of the nuclear pore complex (gp210) is highly indicative of primary biliary cirrhosis (PBC). However, the significance of anti-gp210 antibody titers for monitoring PBC remains unresolved.

METHODS

We used an ELISA with a gp210 C-terminal peptide as an antigen to assess serum antibody titers in 71 patients with PBC.

RESULTS

Patients were classified into three groups: Group A in whom anti-gp210 titers were sustained at a high level, Group B in whom anti-gp210 status changed from positive to negative under ursodeoxycholic acid (UDCA) therapy, Group C in whom anti-gp210 antibodies were negative at the time of diagnosis. The rate of progression to end-stage hepatic failure was significantly higher in group A (60%) as compared to groups B (0%) and C (4.2%). The sustained antibody response to gp210 was closely associated with the severity of interface hepatitis. The significance of anti-gp210 antibody was confirmed by National Hospital Organization Study Group for Liver Disease in Japan.

CONCLUSIONS

The serial quantitation of serum anti-gp210-C-terminal peptide antibodies is useful for monitoring the effect of UDCA and for the early identification of patients at high risk for end-stage hepatic failure.

Nuclear pore complex oxalate binding protein p62: expression in different kidney disorders

BACKGROUND

Urolithiasis is a multifactorial process that starts with the formation of microcrystals in the urine and terminates as mature renal calculi. The oxalate binding protein plays a vital role in the transport of oxalate. The physiological significance of the presence of oxalate binding protein in the nuclear pore complex is not well understood.

METHODS

The nuclear envelope was extracted from human cadaver kidneys. 14C oxalate was labeled, nuclear pore complex proteins were extracted and loaded onto Sephadex G-200, and further purified in DEAE-Sephadex A-50 column. The radioactive protein peak was pooled, concentrated and checked for purity in SDS-PAGE. The purified protein showed cross-reactivity with the monoclonal antibody (MAb 414) and was homogeneous. Urine samples of healthy individuals with no history of kidney disease served as control. Blood and urine samples were collected from kidney and autoimmune disorder patients and checked for the expression of p62 protein by ELISA.

RESULTS

Extracted and purified nuclear pore complex oxalate binding protein had a molecular weight of 62 kDa. A threefold increase in oxalate excretion was observed in hyperoxaluric patients compared to control subjects. The protein expression was found to be higher in hyperoxaluric patients vs. controls, chronic renal failure (CRF) and acute renal failure (ARF), whereas decreased expression was observed in nephrotic syndrome (NS) patients. p62 autoantibodies was observed in hyperoxaluria (HO), systemic lupus erythematosus (SLE) and primary biliary cirrhosis (PBC), whereas it was absent in controls.

CONCLUSION

Increased expression of p62 may be due to membrane damage induced by oxalate stress, and may be used as a diagnostic marker. This study also confirms the presence of p62 autoantibodies in HO patients.

Autoimmune cytopenias associated with autoantibodies to nuclear envelope polypeptides

A subset of anti-nuclear autoantibodies (ANA) are directed against nuclear envelope (NE) polypeptides and display by indirect immunofluorescence (IIF) a ring-like fluorescent pattern. We report herein 19 patients with autoimmune cytopenias associated with antibodies (Abs) to NE polypeptides. Anti-NE specificity was determined by immunoblot, using NE preparations and purified lamina fractions. Eleven sera reacted with lamin B(1), and two reacted with both lamin B(1) and an unidentified 150-kDa protein (p150). One serum reacted with only p150. Four sera reacted with lamins A and C, and one reacted with and an unidentified 52-kDa NE polypeptide (p52). Autoimmune cytopenias included hemolytic anemia (7 cases), thrombocytopenia (13 cases), and neutropenia (6 cases). Five patients had 2 (3 cases) or 3 (2 cases) different cytopenias. Antiphospholipid antibodies (APLA) were detected in 14 patients, 2 of whom experienced thromboembolic events. A liver disorder was present in 7 patients. Systemic lupus erythematosus and lupus-like syndrome were diagnosed in 11 and 2 patients, respectively. Cytopenias responded to steroids alone (13 patients), or together with intravenous immunoglobulins (2 patients), or cyclophosphamide (2 patients). Two patients did not require treatment. Our results suggest that anti-NE Abs need to be sought for in patients with peripheral cytopenias, particularly when they are associated with APLA and/or liver disorders. Their detection strongly suggests an autoimmune process. Such cytopenias are often manifestations of a lupus or lupus-like disease and are responsive to steroids.

Diagnostic and therapeutic implications of bile duct injury in autoimmune hepatitis

BACKGROUND

Bile duct injury is not a feature of classical autoimmune hepatitis (AIH), but it has been described in variant forms of the disease.

AIMS

Our goals were to assess the similarity of AIH with bile duct injury to classical disease and to evaluate the possibility of concurrent primary biliary cirrhosis (PBC).

METHODS

Fifteen patients with bile duct injury were compared with 151 patients with classical AIH. Patterns of nuclear immunofluorescence and the frequency and nature of autoantibodies associated with AIH and PBC were determined.

RESULTS

Patients with bile duct injury had the same nuclear-staining patterns, frequency and nature of autoantibodies, and genetic risk factors as the comparison group. Features specific for PBC, including the multiple nuclear dot pattern of immunofluorescence and antibodies to the M2 antigens, Sp100 and nuclear pore complex antigen, gp210, did not distinguish them from classical disease. Remission and treatment failure occurred with similar frequencies in both groups.

CONCLUSIONS

Patients with AIH and bile duct injury lack features of PBC, and they respond as well to corticosteroid therapy as patients with classical disease. Background bile duct changes should not alter the diagnosis or treatment of AIH.

Autoantigens of the nuclear pore complex

The nuclear envelope (NE) is one of many intracellular targets of the autoimmune response in patients with autoimmune liver disease, systemic lupus erythematosus, and related conditions. In eukaryotic organisms the NE consists of five interconnected regions: an outer nuclear membrane (ONM) that is continuous with the endoplasmic reticulum, an intermembrane or perinuclear space, an inner nuclear membrane (INM) with a unique set of integral membrane proteins, the underlying nuclear lamina, and the pore domains that are regions where the ONM and INM come together. The pore domains are sites of regulated continuity between the cytoplasm and nucleus that are occupied by supramolecular structures, termed nuclear pore complexes (NPCs). Human autoantibodies identified to date bind to specific components in three of the five NE compartments. Autoantigen targets include the lamins A, B, and C of the nuclear lamina, gp210, p62 complex proteins, Nup153, and Tpr within the NPC, and LBR, MAN1, LAP1, and LAP2 that are integral proteins of the INM. Autoantibodies to these NE targets have been shown to be correlated with various autoimmune diseases such as primary biliary cirrhosis, other autoimmune liver diseases and systemic rheumatic diseases. Now that the proteome of the NE is more clearly defined, other autoantibodies to components in this cell compartment are likely to be defined.

Molecular mimicry of mitochondrial and nuclear autoantigens in primary biliary cirrhosis

BACKGROUND & AIMS

The mechanism for development of primary biliary cirrhosis (PBC) remains enigmatic, but molecular mimicry has been implicated because of well-known cross-reactivity of human mitochondrial autoantigens and equivalent bacterial antigens. Virtually all patients with PBC have antimitochondrial autoantibodies (AMA), but, interestingly, approximately 50% also manifest antinuclear antibodies (ANA).

METHODS

To determine whether generation of ANA are due to molecular mimicry of mitochondrial peptides, we established 6 T-cell clones selected by a peptide corresponding to the E2 subunit of mitochondrial pyruvate dehydrogenase complex and analyzed for reactivity to mimicry peptides derived from mitochondrial and nuclear autoantigens, including control sequences.

RESULTS

For mitochondrial autoantigens, 1 peptide from the E2 subunit of the pyruvate dehydrogenase complex, 1 peptide from the E2 subunit of the oxo-glutarate dehydrogenase complex, 1 peptide from the E2 subunit of the branched-chain 2-oxoacid dehydrogenase complex, and 1 peptide from the E3-binding protein cross-reacted with these T-cell clones. For the nuclear autoantigens, 5 peptides from gp210 and 1 from Sp100 cross-reacted with these clones. Furthermore, 1 of 3 T-cell clones selected by recombinant gp210 protein reacted with a mimicry peptide corresponding to amino acids 188-201 of gp210, indicating that this part of the protein is a naturally processed immunodominant T-cell epitope.

CONCLUSIONS

These results demonstrate molecular mimicry between mitochondrial and nuclear autoantigens in PBC and that a mimicry peptide may become an immunodominant T-cell epitope. These data have significance not only for PBC but also for the production of ANA in other disease processes.

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.

Characterization and clinical impact of antinuclear antibodies in primary biliary cirrhosis

OBJECTIVES

The clinical impact of antinuclear antibodies in primary biliary cirrhosis is uncertain. We analyzed in detail the antinuclear antibodies reactivity of primary biliary cirrhosis patients and correlated the fine specificities observed with clinical, biochemical, and immunologic parameters.

METHODS

A total of 96 consecutive primary biliary cirrhosis patients and 283 pathologic controls were studied. To dissect the fine antinuclear antibodies specificities we used different techniques, such as indirect immunofluorescence on cryostat tissue sections and cell culture (HEp-2 cells), counterimmunoelectrophoresis with thymus and spleen extracts, ELISA assays with recombinant Sp100 and purified gp210 and Lamin B receptor, and immunoblot with several recombinant nuclear and cytoplasmic antigens.

RESULTS

Antinuclear antibodies were detected in 53% of patients, with the following hierarchy of specificities: 27% anti-Sp100, 16% "multiple nuclear dots," 16% anti-gp210, 16% anti-centromere, 7% XR1, 6% anti-lamin B receptor, 5% anti-SS-A/Ro, 5% anti-ribonucleoprotein, 4% XR2, 2% anti-SS-B/La, 2% perinuclear antineutrophil cytoplasmic antibodies, and 1% anti-double-stranded deoxyribonucleic acid. Several patients showed multiple specificities. The "multiple nuclear dots" pattern was detected more often in antimitochondrial antibodies negative patients. In particular, primary biliary cirrhosis specific antinuclear antibodies (anti-Sp100, anti-gp210, and anti-lamin B receptor) were detected in nine of 13 antimitochondrial negative primary biliary cirrhosis cases. Anti-gp210 was more frequent in patients with more pronounced cholestasis and more impaired liver function.

CONCLUSIONS

Antinuclear antibodies reactivities are present in more than half of primary biliary cirrhosis patients and target diverse autoantigens located in distinct subnuclear structures. Anti-gp210 identifies a subgroup of primary biliary cirrhosis patients with more serious liver disease. Positivity for anti-Sp100, anti-gp210, and anti-lamin B receptor, either alone or in combination, may act as a serologic marker of antimitochondrial antibodies negative primary biliary cirrhosis.

New autoantibodies and autoantigens in autoimmune hepatitis

The molecular characterization of the autoreactivities associated with autoimmune liver disease will improve their diagnosis and enhance understanding of their pathogenic mechanisms. Surprisingly, little is known about the nature of the major autoreactivities associated with type 1 AIH, including homogeneous ANA and antibodies to microfilaments [3]. Type 1 AIH is, however, the prototype of autoimmune liver disease [103].

Anti-nuclear envelope antibodies: Clinical associations

OBJECTIVES

Characterization of the clinical associations and clinical implications of antibodies reacting with antigens of the nuclear envelope.

METHODS

Description of an illustrative case and a MEDLINE search-assisted literature review of relevant cases.

RESULTS

With indirect immunofluorescence, autoantibodies directed against various antigens of the nuclear envelope stain the nucleus in a ring-like (rim) pattern. Autoantibodies against 5 antigenic components of the nuclear envelope have been described: anti-gp210, p62, lamina, lamina-associated polypeptides, and lamin B receptor. Antibodies to antigens of the nuclear pore complex, such as gp210 and p62, are highly specific (> 95%) for primary biliary cirrhosis and may aid in the serologic diagnosis of this condition, especially in cases in which antimitochondrial antibodies are not detectable. In contrast, antilamin antibodies are not disease-specific but seem to be associated with lupus anticoagulant or anticardiolipin antibodies, antiphospholipid syndrome, thrombocytopenia, autoimmune liver diseases, and arthralgia. High-titered antilamin antibodies help to define a subset of lupus patients with antiphospholipid antibodies who are at a lower risk of developing thrombotic events. In addition, preliminary data suggest that the presence of antilamin antibodies may be helpful in the diagnosis of chronic fatigue syndrome.

CONCLUSIONS

Each of the antibodies reacting with nuclear membrane antigens has its own spectrum of disease associations.

RELEVANCE

Determination of anti-nuclear envelope antibody pattern by indirect immunofluorescence, with subsequent determination of the specific antibody, carries important diagnostic and prognostic implications in various autoimmune conditions.

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.

"Atypical p-ANCA" in IBD and hepatobiliary disorders react with a 50-kilodalton nuclear envelope protein of neutrophils and myeloid cell lines

BACKGROUND & AIMS

Atypical "antineutrophil cytoplasmic antibodies" (ANCA) are present in patients with ulcerative colitis (UC), primary sclerosing cholangitis (PSC), and autoimmune hepatitis (AIH). Recently, we showed that atypical p-ANCA react with nuclear envelope proteins of neutrophils. Based on this observation, we aimed to characterize the nuclear antigen recognized by atypical p-ANCA.

METHODS

We prepared cytoplasmic and nuclear extracts of human neutrophils, human HL-60, and murine 32D myeloid cells. Proteins were resolved by 1- and 2-dimensional gel electrophoresis. Reactive proteins were detected by immunoblotting with sera from 118 individuals (UC, 25; PSC, 28; AIH, 35; disease and normal controls, 30). Atypical p-ANCA (n = 64) were affinity-purified against the reactive protein and investigated for their immunofluorescence pattern using confocal microscopy.

RESULTS

Immunoblotting showed reactivity to a myeloid-specific 50-kilodalton nuclear protein with an isoelectric point of pH 6.0 detected in 92% (59 of 64) of the patients with inflammatory bowel or hepatobiliary diseases and atypical p-ANCA. Affinity-purified antibodies against the 50-kilodalton protein gave a nuclear rim-like fluorescence on myeloid cells examined by immunofluorescence microscopy. Affinity-purified antibodies did not recognize antigens in nonmyeloid cells.

CONCLUSIONS

Atypical p-ANCA in UC, PSC, or AIH recognize a 50-kilodalton myeloid-specific nuclear envelope protein.

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.

Review: nuclear lamins--structural proteins with fundamental functions

The nuclear lamina is located between the inner nuclear membrane and the peripheral chromatin. It is composed of both peripheral and integral membrane proteins, including lamins and lamina-associated proteins. Lamins can interact with one another, with lamina-associated proteins, with nuclear scaffold proteins, and with chromatin. Likewise, most of the lamina-associated proteins are likely to interact directly with chromatin. The nuclear lamina is required for proper cell cycle regulation, chromatin organization, DNA replication, cell differentiation, and apoptosis. Mutations in proteins of the nuclear lamina can disrupt these activities and cause genetic diseases. The structure and assembly of the nuclear lamina proteins and their roles in chromatin organization and cell cycle regulation were recently reviewed. In this review, we discuss the roles of the nuclear lamina in DNA replication and apoptosis and analyze how mutations in nuclear lamina proteins might cause genetic diseases.

Case report: a rare association of primary biliary cirrhosis and systemic lupus erythematosus and review of the literature

We report a rare occurrence of systemic lupus erythematosus in a patient known to have had well-documented primary biliary cirrhosis for 10 years. The presentation was dramatic with pericardial tamponade, but responded well to high dose corticosteroid. There are only five such definite associations reported in the literature. In the present case, other possible causes were considered, such as drug-induced cholestasis, drug-induced lupus, autoimmune chronic active hepatitis and the overlap syndrome.

Atypical antineutrophil cytoplasmic antibodies with perinuclear fluorescence in chronic inflammatory bowel diseases and hepatobiliary disorders colocalize with nuclear lamina proteins

Antineutrophil cytoplasmic antibodies (ANCA) are frequently associated with chronic inflammatory bowel diseases (IBD) and hepatobiliary disorders. However, their target antigens have not been identified yet. Recently, we observed an atypical perinuclear ANCA fluorescence (p-ANCA) together with an intranuclear staining using ANCA-positive sera from patients with IBD and hepatobiliary disorders. This observation suggests that the target antigens are localized within the nucleus of neutrophilic granulocytes. To further investigate this hypothesis, we examined sera from patients with ulcerative colitis, primary sclerosing cholangitis, autoimmune hepatitis or systemic vasculitis on ethanol or formaldehyde-fixed neutrophils using confocal laser scanning microscopy and immunoelectron microscopy. Counterstaining with propidium iodide, a DNA-specific dye, showed that ANCA-positive sera in IBD and heptobiliary disorders react with intranuclear antigens at the nuclear periphery of the neutrophils. Double immunolabeling techniques revealed that nuclear lamina proteins, lamins A, C and B1, and lamin B receptor were colocalized with the antigen(s) recognized by atypical p-ANCA. No colocalization was observed with classical p-ANCA and antibodies against histones (H1-H4). Our study showed that atypical p-ANCA are antinuclear antibodies reactive with granulocyte-specific antigens present in the nuclear lamina.

Autoantibodies against a 210 kDa glycoprotein of the nuclear pore complex as a prognostic marker in patients with primary biliary cirrhosis

It has been reported that the presence of anti-nuclear antibody against a 210 kDa glycoprotein of nuclear pore complex (anti-gp210) is highly specific for primary biliary cirrhosis (PBC). The aim of the present study was to investigate the significance of anti-gp210, especially as a prognostic marker. The presence of anti-gp210 was ascertained in 113 patients with PBC and 162 controls by indirect immunofluorescence assay using HepG2 cells and immunoblotting analysis using nuclear extracts from HeLa cells. Anti-gp210 was detected in 25 of the 113 (22.1%) patients. None of the 162 controls was positive for anti-gp210. The appearance and titre of anti-gp210 in the patients with PBC did not vary from the time of diagnosis and through their clinical course. Anti-mitochondrial antibodies (AMA), including antibodies against pyruvate dehydrogenase complex, branched chain alpha-ketoacid dehydrogenase complex and alpha-ketoglutarate dehydrogenase complex, were not detected by enzyme-linked immunosorbent assay in five of the 113 (4.4%) patients with PBC. However, anti-gp210 alone was positive in one of these five patients. The difference in prognosis was statistically significant; patients with PBC positive for anti-gp210 died from hepatic failure more frequently than those who were negative (P < 0.01), although there were no statistically significant differences in the frequency of jaundice and the histological stage at the time of diagnosis between the two groups. We suggest that the presence of anti-gp210 is one of the independent prognostic markers able to predict, at the time of diagnosis, a poor outcome in patients with PBC.

Prevalence, kinetics, and therapeutic modulation of autoantibodies against Sp100 and promyelocytic leukemia protein in a large cohort of patients with primary biliary cirrhosis

Antinuclear antibodies (ANA) staining nuclear dot structures predominantly occur in primary biliary cirrhosis (PBC) patients and recognize the Sp100 and promyelocytic leukemia protein (PML). From retrospective analysis of sera from a clinically well-defined Canadian series of 170 PBC patients included into a 24-month therapeutic trial of ursodeoxycholic acid (UDCA), we report the prevalence of these ANA and their dynamics in the course of the disease. Using an enzyme-linked immunosorbent assay (ELISA), anti-Sp100 autoantibodies were shown in 35 (21%) patients. Thirty-three patients (19%) had autoantibodies against PML as determined by indirect immunostaining of cells overexpressing PML. Altogether, anti-nuclear dot autoantibodies were present in 25% of the 170 PBC patients. Their occurrence correlated with an unfavorable disease course, because these patients progressed significantly more frequently from early stages (I/II) to late stages (III/IV) within the 24-month observation period (P < .05). During the course of the disease, the autoantibody levels against the Sp100 full-length protein remained nearly constant in all 35 positive patients. However, 9 patients showed remarkable changes in Sp100 epitope recognition as revealed by ELISA and immunoblotting. When the occurrence of these changes and the treatment of the patients were compared retrospectively, it became evident that 8 of the 9 patients had received UDCA (42% of all Sp100-positive patients treated with UDCA). These findings indicate subtle changes of the Sp100 epitope recognition pattern during the natural course of the disease and its induction or acceleration by UDCA treatment. This implies that UDCA can modulate immunoglobulin (Ig) expression not only quantitatively, but also qualitatively.

Acute hepatitis caused by alverine associated with anti-lamin A and C autoantibodies

We report the case of a 67-year-old woman in whom onset and regression of acute hepatitis were closely related to the time of administration and withdrawal of the smooth muscle relaxant alverine. Antinuclear antibodies were positive, and their titer followed the course of hepatitis. They presented a smooth rim-like nuclear immunofluorescence staining pattern. Immunoblot assay showed that they were directed against lamin A and lamin C. This suggests that alverine should be added to the list of drugs known to produce acute hepatitis, and that drug-induced liver injury is a possible cause of antinuclear antibodies specific for lamin A and lamin C.

Autoantibodies

The number of autoantibodies associated with chronic liver disease continues to burgeon and characterization of these immunoreactivities will undoubtedly enhance understanding of the autoantigens that are targeted by cytodestructive immunocytes. Assays for the majority of these immunoserological species are not generally available and in most instances, assessments are restricted to individual laboratories with vested interests in characterizing a particular species. For clinical diagnosis and management of autoimmune liver disease, assays for ANA, SMA, anti-LKM1 and AMA are essential. This conventional armamentarium, however, must be upgraded on a regular basis to ensure availability and application of the most useful assays. Unfortunately, there are no formal mechanisms for improving the diagnostic resources and standardizing testing strategies. An important first step must be taken by the basic laboratories that advocate individual assay systems. These facilities must share methodologies and exchange serum samples so that the most clinically pertinent and cost-effective immunoserological batteries can be defined and promulgated. Industry can then respond to need and facilitate the commercialization of assays for general use. Currently, the assays that warrant dissemination are those that detect antibodies to the E2 subunits of the pyruvate dehydrogenase complex and antibodies to asialoglycoprotein receptor. Both assays have high diagnostic specificity and each reflects reactivity to an important target autoantigen of probable pathogenic importance. Each autoantibody species can supplant conventional assays such as those for AMA and ANA and they each may impart useful clinical information. In the case of antibodies to the E2 subunits, titres may reflect histological progression of PBC. In the case of anti-ASGPR, disappearance of the autoantibodies in patients with autoimmune hepatitis may secure a confident treatment end-point. Great progress has been made in defining the immunoserological manifestations of chronic liver disease but little has been done to distribute the resources.

Autoantibodies from patients with primary biliary cirrhosis preferentially react with the amino-terminal domain of nuclear pore complex glycoprotein gp210

Patients with primary biliary cirrhosis frequently develop autoantibodies directed to gp210, a major glycoprotein of the nuclear pore complex. This protein contains a large glycosylated cisternal domain, a single transmembrane segment, and a short cytoplasmic tail. It has been previously shown that autoantibodies from primary biliary cirrhosis patients exclusively react with the cytoplasmic tail. We demonstrate that autoantibodies against gp210 recognize at least two different epitopes. 4 out of 12 anti-gp210 positive sera reacted with the fragment consisting of the cytoplasmic tail, and 8 sera targeted a novel epitope located within the large glycosylated lumenal domain. Moreover, our data prove that carbohydrate moieties are an essential part of this novel epitope. We propose, therefore, that future screening assays should be performed with antigens possessing both epitopes to detect all sera with anti-gp210 specificity.

High prevalence of antibodies to recombinant CENP-B in primary biliary cirrhosis: nuclear immunofluorescence patterns and ELISA reactivities

The purpose of the present study is to evaluate the centromeric pattern on human laryngeal tumour (HEp-2) cells by indirect immunofluorescent (IIF) test and to compare their reactivities with a newly developed recombinant centromere protein B enzyme linked immunosorbent assay (CENP-B ELISA) test using sera of antinuclear antibody (ANA)-reactive primary biliary cirrhosis (PBC) patients. Antimitochondrial antibody (AMA) subtypes (PDC-E2, BCOADC-E2, OGDC, protein X, and PDC-E1 alpha) by Western blot were also investigated to see whether they have any effect on the expression of CENP-B reactivities. A centromeric pattern (anticentromere antibody [ACA]) was detected in 11 of 25 (44%) PBC patients whereas CENP-B reactivity was found in 15 (60%) of them. There were some differences in IIF patterns and CENP-B reactivities. One PBC serum with indistinguishable ANA pattern reacted with CENP-B. Eight of 15 (53%) CENP-B reactive patients had other autoimmune-like disorders. Of 181 healthy sera, none was reactive for ACA either by IIF or by ELISA test. There was a correlation between ACA IIF and CENP-B ELISA titres (r = 0.824, P < 0.001). However, no correlation was observed between either CENP-B or AMA reactivities and/or between either autoantibodies or laboratory and histologic indices of PBC. These findings suggest that recombinant CENP-B ELISA appears to be more sensitive in identifying ACA than IIF, underlying its potential value as a screening test for the diagnosis of PBC complicated with other autoimmune-like disorders. The presence of multiple autoantibodies in PBC sera may reflect heterogeneous antigens recognition, and requires further study to identify target antigens at cellular and molecular levels.

Mitochondrial antigens, molecular mimicry and autoimmune disease

The immune system is normally tolerant to mitochondrial self-antigens, but responsive against bacteria. Low-titre anti-mitochondrial antibodies (AMA) might be involved in this discrimination. Tolerance is broken in diseases characterised by high titre AMA. Some of these AMA, against cardiolipin, cross-react with DNA. The best studied AMA are those characterising primary biliary cirrhosis (PBC). These are directed against E2 subunits of the oxo-acid dehydrogenase complexes, and also against subunits E1 alpha, E1 beta and X of the pyruvate dehydrogenase complex. AMA of PBC patients also react with bacterial E2s. Reactivities are primarily peptide-specific but with cross-reactivity between mitochondrial and microbial antigens and between E2s of respective complexes. Immunodominant epitopes, for anti E2 AMA, include the conserved sequence flanking the site of lipoyl attachment. It is proposed that the initial stimulus for antibody production is chronic urinary tract infection. AMA themselves are not pathogenic, but CD4+ T-cells would be primed, recognising the lipoyl domain epitope in association with class II HLA. Inappropriate expression of class II antigens on bile duct epithelia, (as found in PBC), might lead to presentation of a particular fragment of HLA-DR alpha, known to be a major MHC presented self-peptide in the mouse. That sequence strongly mimics the lipoyl domain and might be recognised by primed T-cells, initiating the autoimmune cascade. In the mouse, a peptide of ND1 of Complex I is presented in association with class I MHC. Cells exhibiting somatic mutation of such a peptide might thus be subject to attack by CD8+ T-cells. If such peptides were presented by class II HLA, autoimmune diseases might arise, related to mimicry between such peptides and microbial sequences and/or self-antigens. These considerations might apply in Leber's disease and in age-related pathology.

Patterns of nuclear immunofluorescence and reactivities to recombinant nuclear antigens in autoimmune hepatitis

BACKGROUND/AIMS

Antibodies to nuclear antigens have not been fully characterized in autoimmune hepatitis. The aims of this study were to determine the different patterns of immunofluorescence associated with antinuclear antibodies and to correlate these patterns with reactivities to recombinant nuclear antigens and clinical manifestations of autoimmune hepatitis.

METHODS

Sera from 65 patients were tested by indirect immunofluorescence and by enzyme immunoassay for antibodies to recombinant centromere, ribonucleoproteins, and ribonucleoprotein complexes.

RESULTS

Homogeneous and speckled patterns of immunofluorescence occurred with similar frequencies (34% vs. 38%) in the majority of patients (72%). Patients with speckled patterns were younger and had higher serum aspartate aminotransferase levels at presentation than counterparts with other patterns. Antibodies to centromere (42%) and 52K ribonucleoprotein complex (23%) were the most common reactivities. Of the 35 patients with antibodies, 16 (46%) had multiple specificities. Individual reactivities were not associated with specific immunofluorescent patterns, and they did not identify patients with distinctive features.

CONCLUSIONS

Antinuclear antibodies produce mainly homogeneous and speckled patterns of immunofluorescence in patients with autoimmune hepatitis. Speckled patterns are associated with a younger age and greater aminotransferase activity. Multiple autoantibodies are frequently associated with each immunofluorescent pattern. Antibodies to centromere and the 52K ribonucleoprotein complex have a previously unrecognized high frequency and uncertain significance.