Detection of high levels of 2 specific isoforms of 14-3-3 proteins in synovial fluid from patients with joint inflammation.
OBJECTIVE
To investigate whether 14-3-3 proteins were detectable in synovial fluid (SF) of patients with inflamed joints, and if so, what isoform(s); and to examine whether there was a correlation between the levels of these proteins and those of MMP-1 and MMP-3 in the same samples.


METHODS
In general, 2 sets of synovial and serum samples were analyzed. The first set of 17 SF -samples from patients with inflamed joints were analyzed for 14-3-3 eta isoform by Western blot. The second set of 12 matching serum and SF samples were analyzed for 14-3-3 eta, gamma, MMP-1, and MMP-3 by the same procedure. The MMP-1 stimulatory effect of various concentrations of 14-3-3 eta in cultured fibroblasts was then evaluated.


RESULTS
We found that of the seven 14-3-3 isoforms tested (beta, gamma, epsilon, eta, sigma, Theta, and zeta), the levels of only 2 isoforms, eta and gamma, were easily detectable in SF samples from patients with inflammatory joint diseases. The levels of these proteins were significantly higher in inflammatory SF and serum samples relative to controls. The values of these proteins correlated strongly with the levels of MMP-1 and MMP-3, 2 biomarkers for rheumatoid arthritis, detected in sera. Further, the level of 14-3-3 eta was significantly higher in a pool of 12 serum samples from patients with inflammatory joint disease than those from healthy individuals.


CONCLUSIONS
Detection of only 2 (14-3-3 eta and gamma) out of 7 different isoforms in SF suggests they are specific to the site of inflammation, and that distinguishes them from barely detectable levels of these isoforms found in normal serum. The MMP-1 stimulatory effect of the eta isoform explains its correlation with MMP-1 levels seen in these samples.
Kilani
Ruhangiz T
RT
Department of Surgery, University of British Columbia, Vancouver, British Columbia, Canada.
Maksymowych
Walter P
WP
Aitken
Alastair
A
Boire
Gilles
G
St-Pierre
Yves
Y
Li
Yunyuan
Y
Ghahary
Aziz
A
D048948:14-3-3 Proteins / Q000378:metabolism* / Q000494:pharmacology; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001168:Arthritis / Q000378:metabolism*; D015415:Biomarkers / Q000378:metabolism; D016022:Case-Control Studies; D002478:Cells, Cultured; D005260:Female; D006801:Humans; D008297:Male; D020781:Matrix Metalloproteinase 1 / Q000378:metabolism; D019278:Matrix Metalloproteinase 3 / Q000378:metabolism; D008875:Middle Aged; D020033:Protein Isoforms / Q000378:metabolism; D013582:Synovial Fluid / Q000378:metabolism*
D048948:14-3-3 Proteins; D015415:Biomarkers; D020033:Protein Isoforms; D019278:Matrix Metalloproteinase 3; D020781:Matrix Metalloproteinase 1