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Heterogeneous response of antimitochondrial autoantibodies and bile duct apical staining monoclonal antibodies to pyruvate dehydrogenase complex E2: the molecule versus the mimic

Heterogeneous response of antimitochondrial autoantibodies and bile duct apical staining monoclonal antibodies to pyruvate dehydrogenase complex E2: the molecule versus the mimic
Heterogeneous response of antimitochondrial autoantibodies and bile duct apical staining monoclonal antibodies to pyruvate dehydrogenase complex E2: the molecule versus the mimic
The 2-oxo-acid dehydrogenase complexes and, in particular, the E2 component of the pyruvate dehydrogenase complex (PDC) are the target of antimitochondrial antibodies (AMA). More than 95% of primary biliary cirrhosis (PBC) patients have detectable levels of autoantibodies to PDC-E2 and in general these react with a region of the molecule that contains the prosthetic group lipoic acid (LA). LA is vital to the function of the enzyme, although there is conflicting evidence as to whether its presence is required for PDC-E2 recognition by AMA. Some, but not all, monoclonal antibodies (mAbs) to PDC-E2 produce an intense staining pattern at the apical surface of bile duct epithelial cells (BEC) in patients with PBC, and it has been argued that the molecule at the apical surface of PBC bile duct cells is a modified form of PDC-E2 or a cross-reactive molecule, acting as a molecular mimic. Herein, we characterize the epitopes recognized by 4 anti-PDC-E2 mAbs that give apical staining patterns (3 mouse and 1 human). In particular, by using a combination of recombinant antigens, competitive inhibition assays, and a unique peptide-on-bead assay, we determined that these apically staining mAbs recognize 3 or 4 distinct epitopes on PDC-E2. More importantly, this suggests that a portion spanning the entire inner lipoyl domain of PDC-E2 can be found at the BEC apical surface. In addition, competition assays with patient sera and a PDC-E2-specific mAb showed significant epitope overlap with only 1 of the 3 mouse mAbs and showed a differential response to the peptide bound to beads. These findings further highlight the heterogeneous response of patient autoantibodies to the inner lipoyl domain of PDC-E2.
0270-9139
792-801
Migliaccio, C.
8d1031a9-91da-4701-b1a2-865c8c4543a3
Van de Water, J.
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Ansari, A .A.
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Kaplan, M. M.
e96b8040-1dae-4ea9-8df1-9b78cd1f8650
Coppel, R. L.
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Lam, K. S.
6c77c271-970b-4a9b-aa26-2c4b1e9720c1
Thompson, R. K.
aac073e5-9382-427a-80da-8642490cfb83
Stevenson, F.
ba803747-c0ac-409f-a9c2-b61fde009f8c
Gershwin, M. E.
09a78a5e-6074-43da-9d71-8dd1b2db0414
Migliaccio, C.
8d1031a9-91da-4701-b1a2-865c8c4543a3
Van de Water, J.
2d2987b1-f236-4341-b950-41d6e8e0c60e
Ansari, A .A.
6b1e2c93-f632-4adc-a2ee-3e111c0bdd8e
Kaplan, M. M.
e96b8040-1dae-4ea9-8df1-9b78cd1f8650
Coppel, R. L.
0f59c826-d981-4604-a446-e706803d6261
Lam, K. S.
6c77c271-970b-4a9b-aa26-2c4b1e9720c1
Thompson, R. K.
aac073e5-9382-427a-80da-8642490cfb83
Stevenson, F.
ba803747-c0ac-409f-a9c2-b61fde009f8c
Gershwin, M. E.
09a78a5e-6074-43da-9d71-8dd1b2db0414

Migliaccio, C., Van de Water, J., Ansari, A .A., Kaplan, M. M., Coppel, R. L., Lam, K. S., Thompson, R. K., Stevenson, F. and Gershwin, M. E. (2001) Heterogeneous response of antimitochondrial autoantibodies and bile duct apical staining monoclonal antibodies to pyruvate dehydrogenase complex E2: the molecule versus the mimic. Hepatology, 33 (4), 792-801. (doi:10.1053/jhep.2001.23783).

Record type: Article

Abstract

The 2-oxo-acid dehydrogenase complexes and, in particular, the E2 component of the pyruvate dehydrogenase complex (PDC) are the target of antimitochondrial antibodies (AMA). More than 95% of primary biliary cirrhosis (PBC) patients have detectable levels of autoantibodies to PDC-E2 and in general these react with a region of the molecule that contains the prosthetic group lipoic acid (LA). LA is vital to the function of the enzyme, although there is conflicting evidence as to whether its presence is required for PDC-E2 recognition by AMA. Some, but not all, monoclonal antibodies (mAbs) to PDC-E2 produce an intense staining pattern at the apical surface of bile duct epithelial cells (BEC) in patients with PBC, and it has been argued that the molecule at the apical surface of PBC bile duct cells is a modified form of PDC-E2 or a cross-reactive molecule, acting as a molecular mimic. Herein, we characterize the epitopes recognized by 4 anti-PDC-E2 mAbs that give apical staining patterns (3 mouse and 1 human). In particular, by using a combination of recombinant antigens, competitive inhibition assays, and a unique peptide-on-bead assay, we determined that these apically staining mAbs recognize 3 or 4 distinct epitopes on PDC-E2. More importantly, this suggests that a portion spanning the entire inner lipoyl domain of PDC-E2 can be found at the BEC apical surface. In addition, competition assays with patient sera and a PDC-E2-specific mAb showed significant epitope overlap with only 1 of the 3 mouse mAbs and showed a differential response to the peptide bound to beads. These findings further highlight the heterogeneous response of patient autoantibodies to the inner lipoyl domain of PDC-E2.

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Published date: April 2001

Identifiers

Local EPrints ID: 157827
URI: http://eprints.soton.ac.uk/id/eprint/157827
ISSN: 0270-9139
PURE UUID: 928f7931-9ef2-4b58-83bb-b8683db187a6
ORCID for F. Stevenson: ORCID iD orcid.org/0000-0002-0933-5021

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Date deposited: 06 Jul 2010 13:39
Last modified: 14 Mar 2024 02:40

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Contributors

Author: C. Migliaccio
Author: J. Van de Water
Author: A .A. Ansari
Author: M. M. Kaplan
Author: R. L. Coppel
Author: K. S. Lam
Author: R. K. Thompson
Author: F. Stevenson ORCID iD
Author: M. E. Gershwin

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