RESEARCH - Citrullination in extra-articular manifestations of rheumatoid arthritis

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Rheumatology (Oxford). 2006 Jun 16; [Epub ahead of print]

Citrullination in extra-articular manifestations of rheumatoid arthritis.

Bongartz T, Cantaert T, Atkins SR, Harle P, Myers JL, Turesson C, Ryu JH,

Baeten D, Matteson EL.

Mayo Clinic College of Medicine, Rochester, MN, USA.

Background. Anti-citrullinated protein antibodies have been detected with

high specificity in serum of patients with rheumatoid arthritis (RA), and

citrullination of proteins may play a key role in the pathogenesis of RA. We

therefore investigated the presence of citrullination in two extra-articular

manifestations of RA, interstitial pneumonia (IP) and rheumatoid nodules.

Methods. Open-lung biopsy specimens from patients with RA-associated IP (n =

18), idiopathic IP (n = 20) and controls (n = 10), as well as specimens of

rheumatoid nodules from 26 patients, were examined. All sections were

incubated with an anti-modified citrulline antibody. Masked scoring of

stained sections and analysis of results by stratification according to

demographic and clinical characteristics was performed.

Results. Presence of citrulline could be detected in eight lung specimens of

patients with RA-associated IP (44%) and nine patients with idiopathic IP

(46%). Conversely, lung tissue from control patients showed weak

extracellular citrullination in only two cases (20%).

Citrullination did not show any significant associations with demographic or

clinical characteristics such as age, gender, smoking habits, disease

severity, histological subtype, degree of inflammation or steroid use.

Rheumatoid nodules were citrulline positive in a majority of cases (70%).

Conclusion. Citrullination is present in extra-articular manifestations of

RA such as IP and nodules. In contrast to the high specificity of

anti-citrulline antibodies in RA, citrullination is not only restricted to

RA but can also be observed in idiopathic IP. Whether citrullination

significantly contributes to the initiation or perpetuation of autoimmunity

or merely reflects ongoing inflammation remains to be clarified.

PMID: 16782731

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=pubmed & cmd=Retrieve & dopt=Abstra\

ct & list_uids=16782731

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Mayo Clinic in Rochester

http://www.mayoclinic.org/rochester

s Hopkins Medicine

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