Primary Biliary Cirrhosis Antigen Research Articles

Identification of New Autoantigens for Primary Biliary Cirrhosis Using Human Proteome Microarrays

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

Autoantibodies to mitochondrial and centromere antigens in primary biliary cirrhosis and systemic sclerosis

High levels of IgG antibodies to the multi-enzyme complex bovine pyruvate dehydrogenase (PDHC) were detected by a sensitive ELISA in all patients with histologically proven primary biliary cirrhosis (PBC), in a minority of patients with systemic sclerosis without overt PBC or with chronic liver diseases of another cause and in no rheumatoid arthritis or normal controls. Most (15/21) but not all of these positive patients recognized a 70-kD (E2) component of PDHC on immunoblotting. Additional recognition of a centromere-associated 140-kD polypeptide was associated with the presence of scleroderma-like features (Raynaud's phenomenon and sclerodactyly) in PBC, further emphasizing the serological and clinical overlap between these two conditions.

A mitochondrial antigen-antibody system in cholestatic liver disease detected by radioimmunoassay.

A radioimmunoassay (RIA) was established for the detection of antimitochondrial autoantibodies (AMAs) in patient sera. AMAs were detected by RIA in 12 of 14 patients with primary biliary cirrhosis and in 3 of 29 patients with chronic active hepatitis. AMAs were detected by indirect immunofluorescence in all sera positive by RIA. In addition, two patients with primary biliary cirrhosis and one patient with chronic active hepatitis were AMA positive when tested by indirect immunofluorescence, but negative when tested by RIA. AMAs were not detected by RIA or indirect immunofluorescence in 121 further patients with various hepatic and nonhepatic diseases, including healthy controls. The RIA detects an AMA directed against one determinant of a mitochondrial antigen which bears the characteristics of the previously described primary biliary cirrhosis antigen (M2 antigen). The RIA described is a sensitive and specific test for the detection of one mitochondrial autoantibody associated with chronic cholestatic liver diseases displaying the morphology of primary biliary cirrhosis in chronic active hepatitis or liver biopsy specimens. Antibodies against other mitochondrial antigens do not react in this assay system.

The Immune Response to Mitochondrial Autoantigens

Similar to other autoimmune diseases, there are intense humoral and cellular responses to intracytoplasmic antigens in primary biliary cirrhosis (PBC). The autoantigens against antimitochondrial antibodies (AMAs) in PBC are located on the inner mitochondrial membrane and are identified as members of the 2-oxo-acid dehydrogenase complexes (2-OADCs), of which the E2 subunit of pyruvate dehydrogenase complex (PDC-E2) is the major autoantigen; AMAs are is present in approximately 90 to 95% of PBC sera. An orchestrated immune response against the intrahepatic biliary epithelial cell (BEC) through 2-OADC-specific CD4 (+) helper T cells and CD8 (+) CTL are thought to be the major players in the immunological destruction of BECs in PBC. We believe that a prior/primary event of specific intrahepatic BEC malfunction (possibly caused by environmental insults such as xenobiotics and microorganisms) is responsible for the breaking of self-tolerance to 2-OADC and leads to BEC destruction. The generation of 2-OADC-specific T cells further accelerates the damage of BEC. In addition, immunoglobulin A AMAs may participate in the destruction of BECs by damaging mitochondria.

Comprehensive mapping of HLA-A*0201–restricted CD8 T-cell epitopes on PDC-E2 in primary biliary cirrhosis

Growing evidence has implicated the involvement of autoreactive T lymphocytes in the pathogenesis of primary biliary cirrhosis (PBC). We have recently taken advantage of motif prediction analysis of HLA-A*0201 and identified the first major histocompatibility complex (MHC) class I restricted epitope, amino acids 159 to 167 on E2 components of pyruvate dehydrogenase complexes (PDC-E2), the major mitochondrial antigens in PBC. The mechanisms involved in the selection of epitope peptide(s) that comprise the PDC-E2–specific autoreactive cytotoxic T lymphocytes (CTLs) are unknown and likely involve other epitopes on PDC-E2 restricted by MHC class I molecules. To address this issue, a comprehensive mapping of the CTL epitope repertoire on the PDC-E2 molecule that binds HLA-A*0201 was performed to provide further clues regarding the role of CTLs. We used the T2 cell line to screen 79 overlapping 15mer peptides, spanning the entire PDC-E2 molecule. Six of the 79 peptides exhibited significantly higher binding activity to HLA-A*0201 than the other 15mer peptides. Two of these 6 peptides induced CTL lines from patients with PBC. Fine mapping with N-terminus or C-terminus truncated peptides identified 10mer peptide, PDC-E2 amino acids 165 to 174, which is a novel CD8 epitope restricted by HLA-A*0201. In conclusion, using a combination of the 15mer peptide library screening with the T2 binding assay and also the induction of CTL lines with candidate peptides, we have defined a novel HLA-A*0201–restricted epitope PDC-E2 165 to 174 in patients with PBC. These data will become important in the development of altered peptide ligands to modulate disease activity. (H EPATOLOGY 2002;36:1125-1134.)

P-111 Expression of apoptosis-related antigens in primary biliary cirrhosis

P-111 Expression of apoptosis-related antigens in primary biliary cirrhosis

Establishment and structural analysis of human mAb to the E2 component of the 2-oxoglutarate dehydrogenase complex generated from a patient with primary biliary cirrhosis.

We established one Epstein-Barr virus-transformed B cell hybrid clone producing human mAb of the IgG class to the 2-oxoglutarate dehydrogenase complex (OGDC) for the first time from the peripheral B lymphocytes of a patient with primary biliary cirrhosis (PBC). This mAb, designated mAbM37GO37, specifically bound to OGDC and its dissociation constant with OGDC was calculated to be 3.70 x 10(-10) mol/l. mAbM37GO37 stained murine stomach/kidney cryostat sections in a typical immunofluorescence pattern of antimitochondrial antibody (AMA). Western blotting analysis revealed that mAbM37GO37 reacted with an E2 component of OGDC but not with other components of OGDC nor pyruvate dehydrogenase complex (PDC). Furthermore, mAbM37GO37 completely inhibited the enzymatic activity of OGDC. In order to determine the structure and genetic origin of anti-OGDC autoantibody, we cloned and sequenced the Ig heavy and light chain variable regions of mAbM37GO37. This mAb used the VHIII family member, V3-7, and the V kappa IV family member. The amino acid difference between the expressed V genes of this mAb and respective putative germline genes was concentrated within the complementarity determining regions (CDR) rather than the framework regions (FR). The R:S mutation ratio was high in the CDR and low in the FR. These features suggested that the immune response to OGDC is similar to that to exogenous antigen, and that the heavy and light chain variable regions of the anti-OGDC antibody undergo somatic hypermutation through antigen-driven clonal selection. This human mAb to OGDC, which was established for the first time from a patient with PBC and characterized at the molecular level, would be a valuable tool to study the B cell autoepitopes of OGDC, to clone as yet undetermined full length cDNA encoding OGDC and to dissect the autoimmune response to mitochondrial antigens in PBC.

Frequency of IgG and IgM autoantibodies to four specific M2 mitochondrial autoantigens in primary biliary cirrhosis.

We have previously identified four of the M2 antigens in primary biliary cirrhosis as the E2 components (dihydrolipoamide acyltransferases) of pyruvate dehydrogenase complex, branched-chain 2-oxo acid dehydrogenase complex and 2-oxoglutarate dehydrogenase complex and the protein X component of pyruvate dehydrogenase complex (approximate molecular masses: 74, 50, 50 and 52 kD, respectively). In the present study, we have examined by immunoblotting the frequency of IgG and IgM autoantibodies to these four proteins in 129 patients with primary biliary cirrhosis (36 histological Stage I, 42 Stage II/III, 51 Stage IV) and 77 controls (49 non-primary biliary cirrhosis chronic liver disease, 16 primary Sjögren's syndrome, 12 healthy normal women). One hundred twenty-seven of 129 (98%) primary biliary cirrhosis patients had antibodies against at least one of the four M2 polypeptides, compared to 2/77 controls (both had autoimmune chronic active hepatitis and were antimitochondrial antibody positive by indirect immunofluorescence). One hundred twenty-one of 129 (94%) primary biliary cirrhosis sera reacted with the E2 component and protein X of pyruvate dehydrogenase complex, 69/129 (53%) primary biliary cirrhosis sera reacted with E2 of branched-chain 2-oxo acid dehydrogenase complex and 113/129 (88%) reacted with E2 of 2-oxoglutarate dehydrogenase complex. Primary biliary cirrhosis patients with histological Stage I disease had a lower incidence of autoantibodies to each M2 protein, compared to more advanced disease (IgG, p less than 0.05) but only 2/36 Stage I patients had no anti-M2 antibodies. There was no correlation between the presence of IgG or IgM antibodies to the M2 polypeptides and established prognostic markers in primary biliary cirrhosis (serum bilirubin and albumin levels).(ABSTRACT TRUNCATED AT 250 WORDS)

Identity of the M2 autoantigens in primary biliary cirrhosis

Primary biliary cirrhosis (PBC)-specific antigens were purified from beef heart mitochondria by immunoaffinity chromatography. Three major polypeptides (75, 60, and 40 kDa) were detected in the purified antigen fraction both by Coomassie blue staining and by western blot analysis. The 75 kDa antigen was identified as a subunit of Complex I (NADH-ubiquinone reductase) by the following criteria: (1) antibodies against the purified 75 kDa subunit of beef heart Complex I react with the immunoaffinity-purified 75 kDa antigen, (2) the 75 kDa subunit present in isolated Complex I, like that in the immunoaffinity-purified antigen, reacts with PBC sera only after reduction with mercaptoethanol, and (3) the 75 kDa antigen is enriched in isolated Complex I. A relationship between the 75 kDa and the 60 and 40 kDa antigens is suggested, since optimal binding of anti-mitochondrial autoantibodies (AMA) to the latter antigens also requires prior reduction with mercaptoethanol. A fourth major antigen (70 kDa) was also detected by western blot analysis, but only in samples that had not been boiled prior to electrophoresis. This antigen, which is also present in isolated Complex I, resembles the 75, 60, and 40 kDa antigens in its response to mercaptoethanol and its reaction with antibodies against the 75 kDa subunit of Complex I. A scheme is presented which relates all of the PBC antigens to the parent 75 kDa subunit of Complex I, probably as proteolytic products of the latter.

Mitochondrial Autoantigens in Primary Biliary

Anti-mitochondrial autoantibodies (AMA) from patients with primary biliary cirrhosis (PBC) were analysed for fine specificity by immunoblotting and enzyme-linked immunosorbent assay (ELISA). Inhibition ELISA showed that complex I (NADH-ubiquinone reductase) from beef heart mitochondria completely inhibited the binding of AMA to mitochondrial inner membranes (SMP), indicating that the major mitochondrial antigens are located in complex I. Immunoblot analysis of beef heart SMP, complex I and the iron sulphur (IP) subfraction of complex I revealed several antigens, one of which (75 kDa) reacted with all PBC sera but not with the additional autoimmune sera tested. Resolution of SMP or complex I by two-dimensional electrophoresis yielded in both preparations a polypeptide of 75 kDa with an isoelectric point of 6.4, which reacted with PBC serum and with rabbit antisera raised against the 75,000 subunit of complex I. In immunoblot experiments, the antigenicity of the 75,000 polypeptide in SMP, complex I, and the IP subfraction is increased by prior reduction of the sample with mercaptoethanol. This suggests a similarity to the PBC-specific 'M-2' antigen, which is also sensitive to sulphur reagents. The data indicate that the 75 kDa polypeptide of complex I is a major mitochondrial antigen binding AMA in PBC sera, and allows us to identify the location and probable function of the PBC antigen.

Evidence that the Major Primary Biliary Cirrhosis‐Specific Mitochondrial Autoantigen is a Subunit of Complex I of the Respiratory Chain

Primary biliary cirrhosis (PBC)-specific antigens were purified from beef heart mitochondria by immunoaffinity chromatography. Three major polypeptides (75, 60, and 40 kDa) were detected in the purified antigen fraction both by Coomassie blue staining and by western blot analysis. The 75 kDa antigen was identified as a subunit of Complex I (NADH-ubiquinone reductase) by the following criteria: (1) antibodies against the purified 75 kDa subunit of beef heart Complex I react with the immunoaffinity-purified 75 kDa antigen. (2) the 75 kDa subunit present in isolated Complex I, like that in the immunoaffinity-purified antigen, reacts with PBC sera only after reduction with mercaptoethanol, and (3) the 75 kDa antigen is enriched in isolated Complex I. A relationship between the 75 kDa and the 60 and 40 kDa antigens is suggested, since optimal binding of anti-mitochondrial autoantibodies (AMA) to the latter antigens also requires prior reduction with mercaptoethanol. A fourth major antigen (70 kDa) was also detected by western blot analysis, but only in samples that had not been boiled prior to electrophoresis. This antigen, which is also present in isolated Complex I, resembles the 75, 60, and 40 kDa antigens in its response to mercaptoethanol and its reaction with antibodies against the 75 kDa subunit of Complex I. A scheme is presented which relates all of the PBC antigens to the parent 75 kDa subunit of Complex I, probably as proteolytic products of the latter.

Expression of the primary biliary cirrhosis antigens in yeast: Aspects of mitochondrial control

The mitochondria of 21 yeast strains were tested for the expression of primary biliary cirrhosis (PBC) specific antigens. The amounts of the antigens in the mitochondrial preparations varied with the strains. Genetic analysis of the strain differences in antigen expression indicated nuclear control which was complex. Those strains expressing the least amounts of antigens exhibited coagulating mitochondria in organellar preparations. Additional evidence relating expression of antigens to the physiological/structural state of mitochondria was that cells grown in the presence of the mitochondrial uncoupling agent, 2,4-dinitrophenol (DNP), failed to produce any antigens, and that glucose repression of mitochondria suppressed antigen expression. Blockage of mitochondrial protein synthesis either through petite mutation or by culture in the presence of erythromycin decreased the content of antigens in the mitochondria but did not completely block antigen production. The presence of the PBC antigen in the mitochondria of these cells with nonfunctional mitochondrial synthesizing machinery further indicates that these antigens are cytoplasmically synthesized. Analysis of the pre- and postmitochondrial fractions of all homogenates confirmed that the antigens are not only cytoplasmically synthesized but also have an extramitochondrial location in cells, probably in the plasma membrane.

Serum basement membrane and type III procollagen-related antigens in primary biliary cirrhosis

A characteristic histological lesion in early primary biliary cirrhosis (PBC) is disruption of the basement membrane around small bile ducts, which at later stages of the disease is followed by fibrosis. To assess the significance of serum basement membrane- and type III procollagen-related antigens in reflecting such processes, we have measured radioimmunologically the concentrations of serum laminin, type IV collagen and the aminoterminal propeptide of type III procollagen in 22 patients with PBC, classified into four stages according to liver histology. The mean laminin concentration in PBC patients was twice that of the healthy control subjects. Increased concentrations were observed in all patients with stage III or IV of the disease and also in 60% (6/10) of the patients, with early stages (I or II). Elevated serum type IV collagen concentrations were found only in four patients, all in the late, fibrotic stages of the disease. The basement membrane protein changes in serum were in accordance with immunohistochemical findings obtained with the antibodies against these proteins. Neither of these serum parameters emerged, however, as a significant predictive factor for survival. The changes in serum aminoterminal propeptide of type III procollagen resembled those in laminin P1. Moreover, the propeptide was also significant as a predictive factor for survival.

HLA-class III antigens in primary biliary cirrhosis (PBC)

HLA-class III antigens in primary biliary cirrhosis (PBC)

The occurrence and localization in trypanosomes and other endo-parasites of an antigen cross-reacting with mitochondrial antibodies of primary biliary cirrhosis

1. 1. A mitochondrion-associated antigen to primary biliary cirrhosis (PBC) in man has been shown by solid-phase radioimmunoassay and immunoautoradiography to occur in several parasitic protozoa ( Trypanosoma, Plasmodium and Eimeria spp.) and in the helminths Ascaridia galli and Nippostrongylus brasiliensis. 2. 2. Stercorarian trypanosomes and T. brucei procyclics, with more highly-developed mitochondria, appear to contain more PBC antigen than the salivarian trypomastigote, in accordance with the known mitochondrial association of the antigen. 3. 3. Trypanosoma lewisi and A. galli gave consistently high reactivity for PBC antigen, the antigen of the former being localized predominantly to the microsomal fraction.

In situ characterization of the cell-surface antigens of the mononuclear cell infiltrate and bile duct epithelium in primary biliary cirrhosis

To analyze the tissue distribution of mononuclear cells and HLA antigens in primary biliary cirrhosis, we studied liver biopsies of 12 patients at different stages of the disease, using the avidin-biotin-peroxidase technique and monoclonal antibodies directed against T and B lymphocytes, T-cell subsets, macrophages, NK/K cells, dendritic cells, and HLA class I and II antigens. To evaluate the proportion of activated T cells we used anti-interleukin-2-receptor antibodies and a double-staining technique for T cells and class II HLA antigens. In all biopsies activated T cells predominated in the portal areas and around the damaged bile ducts. T4 cells almost always outnumbered T8 cells. While B cells, NK/K cells, and dendritic cells were always scarce, macrophages constituted about 30% of the cellular infiltrate. Biliary epithelium, which normally expresses HLA class I antigens, displayed mainly HLA class II antigens. The predominance of T4 cells around the bile ducts, which express class II antigens, suggests that class II-restricted T4 lymphocytes may mediate liver damage in primary biliary cirrhosis.

Inappropriate expression of mitochondrial antigens in breast cancer

Conference Article| August 01 1986 Inappropriate expression of mitochondrial antigens in breast cancer HAROLD BAUM; HAROLD BAUM *Department of Biochemistry, King's College, Kensington Campus, Campden Hill, London W8 7AH, U.K. Search for other works by this author on: This Site PubMed Google Scholar DAKSHA TRIVEDI; DAKSHA TRIVEDI †Department of Surgery, King's College, London SE5 8RX, U.K. Search for other works by this author on: This Site PubMed Google Scholar MICHAEL BAUM MICHAEL BAUM †Department of Surgery, King's College, London SE5 8RX, U.K. Search for other works by this author on: This Site PubMed Google Scholar Biochem Soc Trans (1986) 14 (4): 755. https://doi.org/10.1042/bst0140755 Views Icon Views Article contents Figures & tables Video Audio Supplementary Data Peer Review Share Icon Share Facebook Twitter LinkedIn MailTo Cite Icon Cite Get Permissions Citation HAROLD BAUM, DAKSHA TRIVEDI, MICHAEL BAUM; Inappropriate expression of mitochondrial antigens in breast cancer. Biochem Soc Trans 1 August 1986; 14 (4): 755. doi: https://doi.org/10.1042/bst0140755 Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentAll JournalsBiochemical Society Transactions Search Advanced Search Keywords: PBC, primary biliary cirrhosis, PBS, phosphate-buffered saline, SDH, succinate dehydrogenase This content is only available as a PDF. © 1986 Biochemical Society1986 Article PDF first page preview Close Modal You do not currently have access to this content.

HLA-DR antigens in primary biliary cirrhosis: lack of association.

A study of HLA-DR antigen in 75 patients with primary biliary cirrhosis has been carried out in order to test the hypothesis that genetic factors related to genes controlling immune responses might be important in the pathogenesis of primary biliary cirrhosis. The frequencies of HLA-DR locus antigens was not significantly different from those in 200 normal controls, nor were those of tissue antigens on the A and B loci. No HLA-DR antigen was significantly associated with the appearance of granulomata on liver biopsy (possibly good prognosis) or with raised serum bilirubin (possibly bad prognosis); nor was there any association between any HLA-DR antigen and adverse reactions to D-penicillamine treatment in 17 patients with such adverse reactions. It is concluded that genetic traits related to HLA antigens studied are probably not important in the aetiology of the disease.

Characterization of primary biliary cirrhosis (PBC) specific mitochondrial determinants by immunoblotting

Antimitochondrial antibodies (AMA) are detected in up to 100% of patients with primary biliary cirrhosis (PBC); subtypes of AMA are disease specific. Sera from 21 patients with PBC and from 50 patients with various hepatic and non-hepatic diseases were tested for AMA by indirect immunofluorescence, radioimmunoassay for PBC-specific subtype anti M2 and characterized by western blot analysis and agarose-IEF-immunoblotting. Sera from patients with PBC reacted with up to 7 different mitochondrial polypeptides on western blots, mol. wt. 24,000-62,000 dalton. Sera from 50 patients with various hepatic and non-hepatic diseases did not react with these polypeptides. Sera with other AMA subtypes were included in this study (anti M1, anti M3, and anti M5). These mitochondrial polypeptides were associated with inner mitochondrial membranes (mitoplasts). Sonification led to a solubilization of several mitochondrial polypeptides (p 62, p 48, p 40, p 24). On agarose-IEF-immunoblotting sera from patients with PBC and 3 sera from patients with AMA positive cholestatic CAH but no other sera reacted with a protein band at pI 4.0; seven PBC sera reacted in addition with a protein band at pI 4.4. Western blot and agarose-IEF-immunoblotting are sensitive and specific tools to identify and characterize mitochondrial target antigens in PBC. Furthermore these techniques allow to study the clinical relevance of the heterogeneity of AMA in cholestatic liver disease.

Autoreactivity against biliary tract antigens in primary biliary cirrhosis

Autoreactivity against biliary tract antigens in primary biliary cirrhosis