Evaluation of newly developed ELISA using "MESACUP-2 test mitochondrial M2" kit for the diagnosis of 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.

Fluctuations of antimitochondrial antibodies and anti-gp210 antibody in a patient with primary biliary cholangitis and Sjögren syndrome with subsequent autoimmune hemolytic anemia: A case report

RATIONALE

Primary biliary cholangitis (PBC) is a rare autoimmune cholestatic liver disease. It is often associated with extrahepatic autoimmune disorders. However, the concurrence of PBC and Sjögren syndrome (SS) with the subsequent onset of autoimmune hemolytic anemia (AIHA) is extremely rare.

PATIENT CONCERNS

This study investigated a 60-year-old woman admitted to our hospital with complaints of xerostomia for 5 years, pruritus for 3 years, and abnormal liver function for 3 months.

DIAGNOSES

The patient was suffering from typical clinical PBC and SS, and developed decompensated liver cirrhosis after 32 months of ursodeoxycholic acid (UDCA) therapy. In May 2018, she was readmitted to the hospital with a high fever of 39 °C, coughing, and sever fatigue without remission after 3 days of cephalosporin antibiotic therapy. During the clinical course of PBC, her antimitochondrial antibodies (AMA) titers fluctuated from 1:1000 to negative and then to weakly positive, determined by indirect immunofluorescence (IIF), immunoblotting, and enzyme-linked immunosorbent assay (ELISA) based on recombinant mitochondrial antigens; furthermore, her titers of anti-gp210, an antinuclear antibody (ANA), increased sharply. Laboratory tests and imaging were performed to diagnose PBC and SS in September 2015. However, she was subsequently diagnosed with AIHA after 32 months of UDCA therapy based on the identification of pancytopenia, increased reticulocyte (RET) count, and a positive result from the direct Coombs test.

INTERVENTIONS

UDCA, hepatic protectant, albumin infusion, chest drainage, rational antibiotic use, diuretics, and methylprednisolone were used to treat the patient.

OUTCOMES

Liver cirrhosis was complicated by the development of AIHA, which became severe at 42 months of follow-up.

LESSONS

This is the first case report showing a patient with comorbid PBC and SS, as well as the sequential development of AIHA with decreased AMA and increased anti-gp210 titers; this may have been due to immunodeficiency. These findings stress the importance of the serological screening of ANA profile, as well as repeated measurement of ANA and AMA to track PBC progression and prognosis.

Making Sense of Autoantibodies in Cholestatic Liver Diseases

Primary biliary cirrhosis (PBC) and primary sclerosing cholangitis (PSC) are the most common chronic cholestatic liver diseases (CLD) in adults and are associated with immune mechanisms. PBC is considered a model autoimmune disease, and more than 90% of patients present very specific autoantibodies against mitochondrial antigens. Whether PSC should be considered an autoimmune or merely immune-mediated disease is still under debate. This review addresses the clinical relevance of autoantibodies in CLD and their pathogenic mechanisms and illustrates the technology available for appropriate autoantibody detection.

Autoantibodies by line immunoassay in patients with primary biliary cirrhosis

OBJECTIVES

We attempted to measure multiple autoantibodies simultaneously using line immunoassay (LIA) in patients with primary biliary cirrhosis (PBC) with or without anti-mitochondrial antibody (AMA) and patients with PBC-autoimmune hepatitis (AIH) overlap, and we examined the clinical significance of measuring these autoantibodies.

METHODS

The study population consisted of 80 patients with PBC (including 12 AMA-negative patients), 16 patients with PBC-AIH overlap and 40 patients with AIH as controls. Nine antibodies (AMA-M2, M2-3E, Sp100, PML, gp210, Ro-52, LKM-1, LC-1 and SLA/LP) were detected by LIA, and AMA-M2 and anti-centromere antibody (ACA) were detected by ELISA. We examined the relationship between these autoantibodies and clinical findings.

RESULTS

The positive prevalence of each autoantibody and ACA in the PBC group, as determined by LIA, was as follows: 13.8% for anti-Sp100, 8.7% for anti-PML, 40% for anti-gp210 and 27.5% for anti-Ro-52 antibodies and 32.5% for ACA. In the PBC-AIH overlap group, the prevalence of anti-gp210 antibody (68.7%) and that of anti-Ro-52 antibody (81.2%) were significantly higher than those in the PBC and AIH groups. Only a few patients were positive for 2 or more autoantibodies. Nine patients were determined to be negative for all autoantibodies by LIA, of whom 7 were positive for ACA. Patients positive for anti-gp210 antibody included more patients classified as stage 4 on histology than did the negative group. Those positive for ACA included more patents with varices than did the negative group.

CONCLUSION

LIA can measure multiple autoantibodies simultaneously and thus is considered useful in diagnosing PBC and PBC-AIH overlap. In addition, ACA is a useful marker for identifying AMA-negative 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.

Disease-specific autoantibodies in primary biliary cirrhosis

Anti-mitochondrial autoantibodies (AMA) are specific markers of primary biliary liver cirrhosis (PBC), a cholestatic autoimmune disease which is characterised by a progressive destruction of the biliary epithelial cells followed by fibrosis, cirrhosis and liver failure. The prevalence of AMA in PBC is more than 90% and they can precede long before the clinical symptoms. AMA are conventionally detected by indirect immunofluorescence (IIF) using rodent liver, kidney, and stomach sections as substrates. Additionally, different PBC-specific anti-nuclear autoantibodies (ANA) can be observed in 30% of patients presenting with multiple nuclear dot or nuclear membrane staining patterns, which preferentially are identified using HEp-2 cells as substrate. The identification of the major PBC-specific mitochondrial and nuclear targets has allowed the generation of monospecific antigenic targets which are increasingly used in solid-phase assays for routine detection of AMA and ANA in mono- or multiparametric screen test systems. In the present paper, we give an overview of the diagnostic significance of autoantibodies in PBC, discuss the competencies of different techniques used for their determination and propose an effective diagnostic strategy.

PBC screen: an IgG/IgA dual isotype ELISA detecting multiple mitochondrial and nuclear autoantibodies specific for primary biliary cirrhosis

A dual isotype (IgG, IgA) enzyme-linked immunosorbent assay (ELISA) designed to provide enhanced detection of primary biliary cirrhosis (PBC)-specific autoantibodies against both major mitochondrial and nuclear antigens has been developed and recently become commercially available. The assay (PBC Screen) simultaneously detects IgG and IgA autoantibodies to the immunodominant portions of the 3 major mitochondrial (MIT3) and nuclear (gp210, and sp100) antigens. The aim of this study was to compare the performance of the PBC Screen to the combined performance obtained with individual IgG ELISAs to MIT3, gp210, and sp100 on a large group of selected patients from multiple centers. A total of 1175 patients with PBC and 1232 subjects without PBC were evaluated. Non-PBC groups included healthy controls (624) as well as individuals with autoimmune hepatitis (281), primary sclerosing cholangitis (77), viral hepatitis (91 hepatitis B and 98 hepatitis C), other liver diseases (31), and other infectious or autoimmune diseases (30). The PBC Screen at the receiver operator characteristic optimized cutoff of 27.8 units, had an overall sensitivity of 83.8%, specificity of 94.7% and area under curve of 0.9212. This was similar to the specificity of 96.1% obtained by the combined results of individual MIT3, sp100, and gp210 IgG ELISAs (kappa index at 0.898). Of the 253 PBC patients without AMA detectable by immunofluorescence, 113 (44.7%) were interpreted as positive for PBC-specific autoantibodies. In conclusion, the PBC Screen is an appropriate first-line test for the diagnosis of PBC, including for patients negative for markers assessed using conventional methods.

Autoantibody IgG subclasses to recombinant antigens and the role of bacterial stimuli in primary biliary cirrhosis

AIM

Serum antimitochondrial antibody (AMA) of the IgG2 and IgG3 subclasses has been reported to be predominant in patients with primary biliary cirrhosis from developed countries. No data are available as to the significance of AMA subtypes in Japanese primary biliary cirrhosis (PBC) patients who have previously manifested unique serological features, nor it is known whether AMA subclasses are influenced by bacterial stimuli, as suggested by the molecular theory of PBC. We undertook a three-step study to address these questions.

METHODS

First, Japanese PBC sera were tested using the established triple recombinant antigen (pML-MIT3) to find AMA subclass distribution. Second, we used the three recombinant mitochondrial antigens in PBC sera of Japanese and USA patients to explore the ethnic difference. Third, we used CpG oligodeoxynucleotides and a B cell mitogen to challenge ex vivo peripheral leukocytes from indirect immunofluorescence (IIF)-AMA-positive patients with Japanese PBC.

RESULTS

We detected most frequently IgG2-AMA followed by IgG3-AMA, with the latter being more common in IIF-AMA-positive cases, and demonstrated that the IgG3 reactivity against the dominant antigen was significantly higher in PBC sera from the USA. We determined that the bacterial stimulus was superior to the mitogen at inducing a predominant production of IgG2-AMA and CD20+ B cell activation.

CONCLUSION

Our data cumulatively supported the hypothesis that IgG2 AMA subtypes are predominant in PBC and suggest that this might be favored by an innate immune reaction against bacterial particles, such as CpG DNA.

IgA class antibodies to 2-oxo-acid dehydrogenase complex are not predictive markers of histopathological progression in primary biliary cirrhosis

Although antimitochondrial antibody (AMA) is the characteristic serological feature of primary biliary cirrhosis (PBC), its pathogenic role remains unclear. In our previous study, we reported a positive correlation between immunoglobulin (Ig) A class anti-2-oxo-acid dehydrogenase complex (2-OADC) and histopathological stage. To determine whether the appearance of IgA class anti-2-OADC by immunoblotting represents an early marker of more aggressive disease or whether it is late finding during the disease course of PBC, we tested not only the entire IgA class but also IgA1, IgA2 and secretory IgA class anti-2-OADC in serial serum samples from 15 patients with PBC. During the median observation period of 51 months, four cases showed histopathological progression (from stage 1 to 2, stage 1 to 3, stage 1 to 4 and stage 2 to 4). There was no statistically significant correlation between the above IgA class anti-2-OADCs and histopathological progression. There was no significant correlation between histopathological stages and IgA2 class anti-2-OADC or secretory IgA class anti-2-OADC by immunoblotting. IgA class anti-2-OADC was more frequent in stages 3-4 than in stages 1-2 (p = 0.0049), but IgA1 class anti-2-OADC was more frequent in stages 1-2 than in stages 3-4 (p = 0.0232). Our present study demonstrated that serum IgA class 2-OADC was not a predictive marker of histopathological progression but was associated with the histopathological stage of PBC. Although the IgA class AMA may have a specific pathogenic role for PBC, the discrepant results between IgA and IgA1 class anti-2-OADC should be further assessed to investigate different functional activities depending on their molecular form.

Detection of M2 antimitochondrial antibodies by dot blot assay is more specific than by enzyme linked immunosorbent assay

AIMS

The objective of our study was, in one hand, to determine the sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of ELISA and dot blot assay to investigate IgG M2 antimitochondrial antibodies (M2 AMA) and, on the other hand, to compare these results with those of indirect immunofluorescence technique (IIF).

METHODS

Sera from patients suffering from primary biliary cirrhosis (PBC) (n=55), systemic lupus erythematosus (n=21), celiac disease (n=30) and blood donors (n=75) were analyzed. M2 AMA were detected by ELISA and dot blot using pyruvate dehydrogenase purified from porcine heart and by IIF on cryostat sections of rat liver-kidney-stomach.

RESULTS

IIF was more sensitive (98%) than ELISA (93%) and dot blot (91%). The specificity of AMA for PBC using IIF, ELISA and dot blot reached 100%, 92% and 100%, respectively. The PPV of IIF, ELISA and dot blot was 100%, 93% and 100%, respectively. The NPV was 98% for IIF, 92% for ELISA and 91% for dot blot.

CONCLUSION

Dot blot, using purified pyruvate dehydrogenase, had a higher specificity than ELISA and may be useful in confirming the specificity of AMA in cases of doubt with IIF.

Primary biliary cirrhosis in female subjects with sicca-associated antibodies

The aim of this study is to clarify the time course of primary biliary cirrhosis (PBC) in subjects possessing anticentromere antibodies (ACA), anti-Ro, and/or anti-La antibodies, and who used alkaline phosphatase (ALP) as a serological marker for PBC. Female subjects (n = 165), who had at least one of ACA, anti-Ro, and/or anti-La, were enrolled in this study. Groups A (ACA alone, n = 44), B (anti-Ro alone, n = 54), E (anti-Ro and anti-La, n = 52), and DFG (ACA with anti-Ro and/or anti-La, n = 14) were analyzed. Healthy females (n = 65) were used as a control. The frequencies of the PBC in groups A (13.6%) and DFG (14.3%) were higher than those in groups B (1.9%) and E (0.0%). The ALP levels increased with age in groups A and DFG and slightly increased with age in groups B and C, and the control group. After correcting for age by analysis of covariance, a comparison of ALP levels among the groups not having anti-M(2) was as follows: group A falling dots group DFG > group B falling dots group E falling dots the control group. The subjects with ACA might thus have PBC more frequently than either those with anti-Ro and/or anti-La, or the control subjects.

Diagnostic relevance and clinical significance of the new enhanced performance M2 (MIT3) ELISA for the detection of IgA and IgG antimitochondrial antibodies in primary biliary cirrhosis

BACKGROUND/AIMS

Antimitochondrial antibodies (AMAs) are the serological hallmark of primary biliary cirrhosis (PBC). We evaluated the sensitivity and specificity of a new M2 enhanced performance enzyme-linked immunosorbent assay (ELISA) (MIT3) for the detection of IgG- and IgA-specific isotypes of AMA in PBC patients including a number of PBC patients negative for AMA by indirect immunofluorescence (IIF) as well as in patients with diverse, non-PBC disorders. We also investigated the clinical significance of IgG and IgA AMA in PBC.

METHODS

One hundred and three Greek PBC patients including 27 with AMA IIF-negative at the time of the investigation, 29 with autoimmune hepatitis-1 (AIH-1), 12 with primary sclerosing cholangitis (PSC), 26 with hepatitis C virus (HCV), 15 with hepatitis B virus (HBV), and 29 healthy were investigated for AMA (IgG and IgA) using the MIT3-based ELISAs (INOVA Diagnostics, San Diego, CA). The samples were also tested by conventional anti-M2 ELISA (INOVA Diagnostics, Inc.).

RESULTS

The IgG MIT3-based ELISA significantly increased AMA detection in the cohort of PBC patients, over 26% of whom were AMA IIF-negative, from 63.1% by the conventional anti-M2, and 73.7% by IIF to 79.6% by MIT3-based ELISA (p<0.001). IgA AMAs were detected in 47.6% patients. Overall, IgG/IgA AMAs were detected in 84/103 (81.6%). IgG MIT3-based ELISA detected 12/27 IIF AMA-negative samples (44.4%), while IgG/IgA MIT3-based ELISAs detected 13/27 IIF AMA-negative patients (48.1%). The specificities of MIT3-based ELISAs (IgG and IgA) were 82.8% and 89.7%, respectively, in AIH-1, 100% and 93.3%, respectively, in HBV, 100% in PSC, and 96% and 93.3%, respectively, in HCV. Patients positive for IgG AMA had significantly more severe disease as shown by worse histology and elevated biochemical markers; IgG and IgA AMA titers were associated positively with the Mayo risk score but none of the isotypes were able to predict disease outcome.

CONCLUSIONS

The new IgG and IgA MIT3-based ELISAs seem to have higher specificity and sensitivity for AMA detection than IIF and the conventional anti-M2. Interestingly, these assays were able to unmask AMA presence in almost half of the AMA-negative samples by IIF. These findings may suggest the use of MIT3-based ELISAs as first-line investigation for AMA detection, particularly, when the laboratories are unfamiliar with the use and interpretation of the IIF patterns of AMA. The presence of IgG AMA seems to characterize PBC patients with more severe disease, but both IgG and IgA isotypes of AMAs were not predictive markers of disease outcome.

Enzyme inhibition assay for pyruvate dehydrogenase complex: Clinical utility for the diagnosis of primary biliary cirrhosis

Primary biliary cirrhosis (PBC) is usually diagnosed by the presence of characteristic histopathological features of the liver and/or antimitochondrial antibodies (AMA) in the serum traditionally detected by immunofluorescence. Recently, new and more accurate serological assays for the detection of AMA, such as enzyme-linked immunosorbent assay (ELISA), immunoblotting, and enzyme inhibition assay, have been developed. Of these, the enzyme inhibition assay for the detection of anti- pyruvate dehydrogenase complex (PDC) antibodies offers certain advantages such as objectivity, rapidity, simplicity, and low cost. Since this assay has almost 100% specificity, it may have particular applicability in screening the at-risk segment of the population in developing countries. Moreover, this assay could be also used for monitoring the disease course in PBC. Almost all sera of PBC-suspected patients can be confirmed for PBC or non-PBC by the combination results of immunoblotting and enzyme inhibition assay without histopathological examination. For the development of a “complete” or "gold standard" diagnostic assay for PBC, similar assays of the enzyme inhibition for anti-2-oxoglutarate dehydrogenase complex (OGDC) and anti-branched chain oxo-acid dehydrogenase complex (BCOADC) antibodies will be needed in future.

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.