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Synovial fluid is a site of citrullination of autoantigens in inflammatory arthritis

Kinloch, Andrew; Lundberg, Karin; Wait, Robin; Wegner, Natalia; Lim, Ngee Han; Zendman, Albert J. W.; Saxne, Tore LU ; Malmstrom, Vivianne and Venables, Patrick J. (2008) In Arthritis and Rheumatism 58(8). p.2287-2295
Abstract
Objective. To examine synovial fluid as a site for generating citrullinated antigens, including the candidate autoantigen citrullinated alpha-enolase, in rheumatoid arthritis (RA). Methods. Synovial fluid was obtained from 20 patients with RA, 20 patients with spondylarthritides (SpA), and 20 patients with osteoarthritis (OA). Samples were resolved using sodium dodecyl sulfate-polyacrylamide gel electrophoresis, followed by staining with Coomassie blue and immunoblotting for citrullinated proteins, alpha-enolase, and the deiminating enzymes peptidylarginine deiminase type 2 (PAD-2) and PAD-4. Proteins from an RA synovial fluid sample were separated by 2-dimensional electrophoresis, and each protein was identified by immunoblotting and mass... (More)
Objective. To examine synovial fluid as a site for generating citrullinated antigens, including the candidate autoantigen citrullinated alpha-enolase, in rheumatoid arthritis (RA). Methods. Synovial fluid was obtained from 20 patients with RA, 20 patients with spondylarthritides (SpA), and 20 patients with osteoarthritis (OA). Samples were resolved using sodium dodecyl sulfate-polyacrylamide gel electrophoresis, followed by staining with Coomassie blue and immunoblotting for citrullinated proteins, alpha-enolase, and the deiminating enzymes peptidylarginine deiminase type 2 (PAD-2) and PAD-4. Proteins from an RA synovial fluid sample were separated by 2-dimensional electrophoresis, and each protein was identified by immunoblotting and mass spectrometry. Antibodies to citrullinated alpha-enolase peptide 1 (CEP-1) and cyclic citrullinated peptide 2 were measured by enzyme-linked immunosorbent assay. Results. Citrullinated polypeptides were detected in the synovial fluid from patients with RA and patients with SpA, but not in OA samples. Alpha-enolase was detected in all of the samples, with mean levels of 6.4 ng/mu l in RA samples, 4.3 ng/mu l in SpA samples, and <0.9 ng/mu l in OA samples. Two-dimensional electrophoresis provided evidence that the alpha-enolase was citrullinated in RA synovial fluid. The citrullinating enzyme PAD-4 was detected in samples from all 3 disease groups. PAD-2 was detected in 18 of the RA samples, in 1.6 of the SpA samples, and in none of the OA samples. Antibodies to CEP-1 were found in 12 of the RA samples (60%), in none of the SpA samples, and in I OA sample. Conclusion. These results highlight the importance of synovial fluid for the expression of citrullinated autoantigens in inflammatory arthritis. Whereas the expression of citrullinated proteins is a product of inflammation, the antibody response remains specific for RA. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Arthritis and Rheumatism
volume
58
issue
8
pages
2287 - 2295
publisher
John Wiley & Sons
external identifiers
  • wos:000259055400012
  • scopus:49449111807
ISSN
1529-0131
DOI
10.1002/art.23618
language
English
LU publication?
yes
id
3c1b1612-ac13-40e2-aa9b-659b935f0438 (old id 1247310)
date added to LUP
2008-11-21 11:01:26
date last changed
2017-10-22 03:55:30
@article{3c1b1612-ac13-40e2-aa9b-659b935f0438,
  abstract     = {Objective. To examine synovial fluid as a site for generating citrullinated antigens, including the candidate autoantigen citrullinated alpha-enolase, in rheumatoid arthritis (RA). Methods. Synovial fluid was obtained from 20 patients with RA, 20 patients with spondylarthritides (SpA), and 20 patients with osteoarthritis (OA). Samples were resolved using sodium dodecyl sulfate-polyacrylamide gel electrophoresis, followed by staining with Coomassie blue and immunoblotting for citrullinated proteins, alpha-enolase, and the deiminating enzymes peptidylarginine deiminase type 2 (PAD-2) and PAD-4. Proteins from an RA synovial fluid sample were separated by 2-dimensional electrophoresis, and each protein was identified by immunoblotting and mass spectrometry. Antibodies to citrullinated alpha-enolase peptide 1 (CEP-1) and cyclic citrullinated peptide 2 were measured by enzyme-linked immunosorbent assay. Results. Citrullinated polypeptides were detected in the synovial fluid from patients with RA and patients with SpA, but not in OA samples. Alpha-enolase was detected in all of the samples, with mean levels of 6.4 ng/mu l in RA samples, 4.3 ng/mu l in SpA samples, and &lt;0.9 ng/mu l in OA samples. Two-dimensional electrophoresis provided evidence that the alpha-enolase was citrullinated in RA synovial fluid. The citrullinating enzyme PAD-4 was detected in samples from all 3 disease groups. PAD-2 was detected in 18 of the RA samples, in 1.6 of the SpA samples, and in none of the OA samples. Antibodies to CEP-1 were found in 12 of the RA samples (60%), in none of the SpA samples, and in I OA sample. Conclusion. These results highlight the importance of synovial fluid for the expression of citrullinated autoantigens in inflammatory arthritis. Whereas the expression of citrullinated proteins is a product of inflammation, the antibody response remains specific for RA.},
  author       = {Kinloch, Andrew and Lundberg, Karin and Wait, Robin and Wegner, Natalia and Lim, Ngee Han and Zendman, Albert J. W. and Saxne, Tore and Malmstrom, Vivianne and Venables, Patrick J.},
  issn         = {1529-0131},
  language     = {eng},
  number       = {8},
  pages        = {2287--2295},
  publisher    = {John Wiley & Sons},
  series       = {Arthritis and Rheumatism},
  title        = {Synovial fluid is a site of citrullination of autoantigens in inflammatory arthritis},
  url          = {http://dx.doi.org/10.1002/art.23618},
  volume       = {58},
  year         = {2008},
}