Expression of fibronectin splice variants and oncofetal glycosylated fibronectin in the synovial membranes of patients with rheumatoid arthritis and osteoarthritis.
OBJECTIVE
The aim of this study was to define and compare the expression of fibronectin (Fn) isoforms in synovial tissue of patients with rheumatoid arthritis (RA) and osteoarthritis (OA).


METHODS
Using monoclonal antibodies specific for total Fn, extra domain (ED)-A Fn, ED-B Fn, and oncofetal glycosylated Fn, we studied the expression of the Fn isoforms in synovium. Furthermore, in situ hybridization for the detection of ED-B Fn mRNA including a double labeling technique for the detection of cell type was applied.


RESULTS
Strong expression of total Fn, ED-A Fn, oncofetal glycosylated Fn and, to a lesser extent, ED-B Fn could be demonstrated in the synovial lining layer in both RA and OA. Stromal and vessel expression of Fn isoforms was more prominent in RA tissue. Pannus tissue showed strong labeling with ED-B Fn.


CONCLUSIONS
The expression of alternatively spliced isoforms of Fn is associated with tissue remodeling and, as a partial process of this phenomenon, with neovascularization rather than underlying disease, X-ray status, or parameters of acute inflammation. In the lining layer, Fn expression correlates with hyperplasia associated with cell recruitment but not with proliferative status. Most remarkably, the expression of ED-B Fn in pannus tissue seems to be associated with the invasive phenotype described in RA tissue.
Kriegsmann
J
J
Institute of Pathology, Trier, Germany.
Berndt
A
A
Hansen
T
T
Borsi
L
L
Zardi
L
L
Bräuer
R
R
Petrow
P K
PK
Otto
M
M
Kirkpatrick
C J
CJ
Gay
S
S
Kosmehl
H
H
D017398:Alternative Splicing / Q000235:genetics; D000911:Antibodies, Monoclonal; D001172:Arthritis, Rheumatoid / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D005353:Fibronectins / Q000235:genetics* / Q000378:metabolism; D006801:Humans; D007150:Immunohistochemistry; D010003:Osteoarthritis / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D013583:Synovial Membrane / Q000378:metabolism* / Q000473:pathology / Q000503:physiopathology
D000911:Antibodies, Monoclonal; D005353:Fibronectins; D020033:Protein Isoforms; D012333:RNA, Messenger; C121542:oncofetal fibronectin