Characterization of a Lipoyl Domain-independent B-cell Autoepitope on the Human Branched-chain Acyltransferase in Primary Biliary Cirrhosis and Overlap Syndrome with Autoimmune Hepatitis

Antal Csepregi, Petra Obermayer-Straub, Susanne Kneip, Anne Kayser, Stephanie Loges, Eleonore Schmidt, Elemér Nemesánszky, F. Szalay, Michael P. Manns, Christian P. Strassburg

Research output: Article

4 Citations (Scopus)

Abstract

Background and aims: Antimitochondrial antibodies (AMA) which recognize pyruvate acetyltransferase (PDC-E2) represent a highly diagnostic feature of primary biliary cirrhosis (PBC). The analysis of immunofluorescence (IF)-AMA-positive sera in PBC patients indicates a conformational epitope located within the lipoyl binding domain of bovine branched-chain acyltransferase (BCKADC-E2) alone or in combination with AMA directed against PDC-E2 the significance of which is presently unclear. In the present study, immunoreactivities and disease associations of AMA against BCKADC-E2 were analyzed. B-cell autoepitopes on BCKADC-E2 were mapped by immunoprecipitation assay. Methods: Sera of 96 IF-AMA-positive patients with serological evidence of anti-BCKADC-E2 alone (n = 26), anti-PDC-E2 alone (n = 15), and both anti-BCKADC-E2 and anti-PDC-E2 (n = 55) were analyzed by Western blot and ELISA in addition to an analysis of B cell autoepitopes on BCKADC-E2 by immunoprecipitation using in vitro translated, unmodified human proteins. Ninety-four patients without IF-AMA [blood donors (n = 30), rheumatoid arthritis (n = 40), autoimmune hepatitis (AIH) (n = 10) and primary sclerosing cholangitis (PSC) (n = 14] served as controls. Results: Eighty of 81 (99%) sera positive for BCKADC-E2 recognized the full length, mature protein, while only 2/10 AIH sera and none of the other controls showed reactivity. Of the 68 PBC sera 58 (85%) recognized the N-terminus consisting of aa 1-144 representing the lipoyl domain. Surprisingly, C-terminal sequences (aa 143-421) were recognized by 46 out of 68 sera (68%). Three PBC sera reacted with the C-terminus only. Only 1/7 serum from patients with an "overlap syndrome of PBC and AIH" was reactive with C-terminal sequences. Conclusions: Our analysis of BCKADC-E2-positive PBC sera identified a novel B cell epitope on the C-terminal part of the human protein. Our data indicate that a distinct subset of AMA recognize sequence(s) on BCKADC-E2 which located outside of the lipoyl binding domain. The absence of immunoreactivity against C-terminal sequences may serve as a marker differentiating patients with PBC and overlap syndrome of PBC with AIH.

Original languageEnglish
Pages (from-to)173-181
Number of pages9
JournalClinical and Developmental Immunology
Volume10
Issue number2-4
DOIs
Publication statusPublished - jún. 2003

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Autoimmune Hepatitis
Biliary Liver Cirrhosis
B-Lymphocytes
Serum
Antibodies
Fluorescent Antibody Technique
Immunoprecipitation
B-Lymphocyte Epitopes
dihydrolipoamide acyltransferase
Sclerosing Cholangitis
Proteins
Acetyltransferases
Blood Donors
Pyruvic Acid
Epitopes
Rheumatoid Arthritis
Western Blotting
Enzyme-Linked Immunosorbent Assay

ASJC Scopus subject areas

  • Immunology
  • Cell Biology
  • Developmental Biology

Cite this

Characterization of a Lipoyl Domain-independent B-cell Autoepitope on the Human Branched-chain Acyltransferase in Primary Biliary Cirrhosis and Overlap Syndrome with Autoimmune Hepatitis. / Csepregi, Antal; Obermayer-Straub, Petra; Kneip, Susanne; Kayser, Anne; Loges, Stephanie; Schmidt, Eleonore; Nemesánszky, Elemér; Szalay, F.; Manns, Michael P.; Strassburg, Christian P.

In: Clinical and Developmental Immunology, Vol. 10, No. 2-4, 06.2003, p. 173-181.

Research output: Article

Csepregi, Antal ; Obermayer-Straub, Petra ; Kneip, Susanne ; Kayser, Anne ; Loges, Stephanie ; Schmidt, Eleonore ; Nemesánszky, Elemér ; Szalay, F. ; Manns, Michael P. ; Strassburg, Christian P. / Characterization of a Lipoyl Domain-independent B-cell Autoepitope on the Human Branched-chain Acyltransferase in Primary Biliary Cirrhosis and Overlap Syndrome with Autoimmune Hepatitis. In: Clinical and Developmental Immunology. 2003 ; Vol. 10, No. 2-4. pp. 173-181.
@article{51b081ef3f0a4a54b5835e6a1cc9331d,
title = "Characterization of a Lipoyl Domain-independent B-cell Autoepitope on the Human Branched-chain Acyltransferase in Primary Biliary Cirrhosis and Overlap Syndrome with Autoimmune Hepatitis",
abstract = "Background and aims: Antimitochondrial antibodies (AMA) which recognize pyruvate acetyltransferase (PDC-E2) represent a highly diagnostic feature of primary biliary cirrhosis (PBC). The analysis of immunofluorescence (IF)-AMA-positive sera in PBC patients indicates a conformational epitope located within the lipoyl binding domain of bovine branched-chain acyltransferase (BCKADC-E2) alone or in combination with AMA directed against PDC-E2 the significance of which is presently unclear. In the present study, immunoreactivities and disease associations of AMA against BCKADC-E2 were analyzed. B-cell autoepitopes on BCKADC-E2 were mapped by immunoprecipitation assay. Methods: Sera of 96 IF-AMA-positive patients with serological evidence of anti-BCKADC-E2 alone (n = 26), anti-PDC-E2 alone (n = 15), and both anti-BCKADC-E2 and anti-PDC-E2 (n = 55) were analyzed by Western blot and ELISA in addition to an analysis of B cell autoepitopes on BCKADC-E2 by immunoprecipitation using in vitro translated, unmodified human proteins. Ninety-four patients without IF-AMA [blood donors (n = 30), rheumatoid arthritis (n = 40), autoimmune hepatitis (AIH) (n = 10) and primary sclerosing cholangitis (PSC) (n = 14] served as controls. Results: Eighty of 81 (99{\%}) sera positive for BCKADC-E2 recognized the full length, mature protein, while only 2/10 AIH sera and none of the other controls showed reactivity. Of the 68 PBC sera 58 (85{\%}) recognized the N-terminus consisting of aa 1-144 representing the lipoyl domain. Surprisingly, C-terminal sequences (aa 143-421) were recognized by 46 out of 68 sera (68{\%}). Three PBC sera reacted with the C-terminus only. Only 1/7 serum from patients with an {"}overlap syndrome of PBC and AIH{"} was reactive with C-terminal sequences. Conclusions: Our analysis of BCKADC-E2-positive PBC sera identified a novel B cell epitope on the C-terminal part of the human protein. Our data indicate that a distinct subset of AMA recognize sequence(s) on BCKADC-E2 which located outside of the lipoyl binding domain. The absence of immunoreactivity against C-terminal sequences may serve as a marker differentiating patients with PBC and overlap syndrome of PBC with AIH.",
keywords = "Antimitochondrial antibodies, Branched-chain acyltransferase, Epitope, Lipoyl domain, Primary biliary cirrhosis",
author = "Antal Csepregi and Petra Obermayer-Straub and Susanne Kneip and Anne Kayser and Stephanie Loges and Eleonore Schmidt and Elem{\'e}r Nemes{\'a}nszky and F. Szalay and Manns, {Michael P.} and Strassburg, {Christian P.}",
year = "2003",
month = "6",
doi = "10.1080/10446670310001642159",
language = "English",
volume = "10",
pages = "173--181",
journal = "Journal of Immunology Research",
issn = "2314-8861",
publisher = "Hindawi Publishing Corporation",
number = "2-4",

}

TY - JOUR

T1 - Characterization of a Lipoyl Domain-independent B-cell Autoepitope on the Human Branched-chain Acyltransferase in Primary Biliary Cirrhosis and Overlap Syndrome with Autoimmune Hepatitis

AU - Csepregi, Antal

AU - Obermayer-Straub, Petra

AU - Kneip, Susanne

AU - Kayser, Anne

AU - Loges, Stephanie

AU - Schmidt, Eleonore

AU - Nemesánszky, Elemér

AU - Szalay, F.

AU - Manns, Michael P.

AU - Strassburg, Christian P.

PY - 2003/6

Y1 - 2003/6

N2 - Background and aims: Antimitochondrial antibodies (AMA) which recognize pyruvate acetyltransferase (PDC-E2) represent a highly diagnostic feature of primary biliary cirrhosis (PBC). The analysis of immunofluorescence (IF)-AMA-positive sera in PBC patients indicates a conformational epitope located within the lipoyl binding domain of bovine branched-chain acyltransferase (BCKADC-E2) alone or in combination with AMA directed against PDC-E2 the significance of which is presently unclear. In the present study, immunoreactivities and disease associations of AMA against BCKADC-E2 were analyzed. B-cell autoepitopes on BCKADC-E2 were mapped by immunoprecipitation assay. Methods: Sera of 96 IF-AMA-positive patients with serological evidence of anti-BCKADC-E2 alone (n = 26), anti-PDC-E2 alone (n = 15), and both anti-BCKADC-E2 and anti-PDC-E2 (n = 55) were analyzed by Western blot and ELISA in addition to an analysis of B cell autoepitopes on BCKADC-E2 by immunoprecipitation using in vitro translated, unmodified human proteins. Ninety-four patients without IF-AMA [blood donors (n = 30), rheumatoid arthritis (n = 40), autoimmune hepatitis (AIH) (n = 10) and primary sclerosing cholangitis (PSC) (n = 14] served as controls. Results: Eighty of 81 (99%) sera positive for BCKADC-E2 recognized the full length, mature protein, while only 2/10 AIH sera and none of the other controls showed reactivity. Of the 68 PBC sera 58 (85%) recognized the N-terminus consisting of aa 1-144 representing the lipoyl domain. Surprisingly, C-terminal sequences (aa 143-421) were recognized by 46 out of 68 sera (68%). Three PBC sera reacted with the C-terminus only. Only 1/7 serum from patients with an "overlap syndrome of PBC and AIH" was reactive with C-terminal sequences. Conclusions: Our analysis of BCKADC-E2-positive PBC sera identified a novel B cell epitope on the C-terminal part of the human protein. Our data indicate that a distinct subset of AMA recognize sequence(s) on BCKADC-E2 which located outside of the lipoyl binding domain. The absence of immunoreactivity against C-terminal sequences may serve as a marker differentiating patients with PBC and overlap syndrome of PBC with AIH.

AB - Background and aims: Antimitochondrial antibodies (AMA) which recognize pyruvate acetyltransferase (PDC-E2) represent a highly diagnostic feature of primary biliary cirrhosis (PBC). The analysis of immunofluorescence (IF)-AMA-positive sera in PBC patients indicates a conformational epitope located within the lipoyl binding domain of bovine branched-chain acyltransferase (BCKADC-E2) alone or in combination with AMA directed against PDC-E2 the significance of which is presently unclear. In the present study, immunoreactivities and disease associations of AMA against BCKADC-E2 were analyzed. B-cell autoepitopes on BCKADC-E2 were mapped by immunoprecipitation assay. Methods: Sera of 96 IF-AMA-positive patients with serological evidence of anti-BCKADC-E2 alone (n = 26), anti-PDC-E2 alone (n = 15), and both anti-BCKADC-E2 and anti-PDC-E2 (n = 55) were analyzed by Western blot and ELISA in addition to an analysis of B cell autoepitopes on BCKADC-E2 by immunoprecipitation using in vitro translated, unmodified human proteins. Ninety-four patients without IF-AMA [blood donors (n = 30), rheumatoid arthritis (n = 40), autoimmune hepatitis (AIH) (n = 10) and primary sclerosing cholangitis (PSC) (n = 14] served as controls. Results: Eighty of 81 (99%) sera positive for BCKADC-E2 recognized the full length, mature protein, while only 2/10 AIH sera and none of the other controls showed reactivity. Of the 68 PBC sera 58 (85%) recognized the N-terminus consisting of aa 1-144 representing the lipoyl domain. Surprisingly, C-terminal sequences (aa 143-421) were recognized by 46 out of 68 sera (68%). Three PBC sera reacted with the C-terminus only. Only 1/7 serum from patients with an "overlap syndrome of PBC and AIH" was reactive with C-terminal sequences. Conclusions: Our analysis of BCKADC-E2-positive PBC sera identified a novel B cell epitope on the C-terminal part of the human protein. Our data indicate that a distinct subset of AMA recognize sequence(s) on BCKADC-E2 which located outside of the lipoyl binding domain. The absence of immunoreactivity against C-terminal sequences may serve as a marker differentiating patients with PBC and overlap syndrome of PBC with AIH.

KW - Antimitochondrial antibodies

KW - Branched-chain acyltransferase

KW - Epitope

KW - Lipoyl domain

KW - Primary biliary cirrhosis

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U2 - 10.1080/10446670310001642159

DO - 10.1080/10446670310001642159

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