Detection of COX-1 and COX-2 isoforms in synovial fluid cells from inflammatory joint diseases.
OBJECTIVE
To investigate the expression of cyclooxygenase-1 (COX-1) and cyclooxygenase-2 (COX-2) in cells from synovial fluid (SF) of patients with acute or chronic arthritis.


METHODS
SF was obtained from eight patients with acute crystal-induced arthritis, nine with rheumatoid arthritis and four with psoriatic arthritis. COX-1 and COX-2 gene expression was studied by reverse transcriptase-polymerase chain reaction (RT-PCR). Protein expression was detected by Western blotting and immunocytochemistry.


RESULTS
There was expression of COX-1 mRNA in all and COX-2 mRNA in most of the SF samples from acute or chronic arthritis. By immunocytochemistry, both COX-1 and COX-2 immunoreactivity was restricted to a variable fraction of mononuclear cells. COX-1 staining was observed in 10-fold more cells than COX-2. By Western blotting, COX-1 protein was detected in 60% of the SF samples and COX-2 in none. There were no differences in the pattern of COX-1 and COX-2 expression between chronic and acute SF samples.


CONCLUSIONS
In arthritis, both COX-1 and COX-2 isoforms are expressed by SF cells. COX-1 is the most abundant isoform. Since the strong COX-1 immunostaining observed in a fraction of mononuclear SF cells is not observed in peripheral blood leucocytes, it may be the result of either the activation or recruitment of a subset of mononuclear cells with a high COX-1 expression level.
Servicio de Reumatología y Unidad de Investigación, Hospital 12 de Octubre, Madrid, Spain.
M A
MA
Iñiguez
J L
JL
Pablos
P E
PE
Carreira
F
F
Cabré
J J
JJ
Gomez-Reino
D015210:Arthritis, Gouty / Q000201:enzymology* / Q000473:pathology; D015535:Arthritis, Psoriatic / Q000201:enzymology* / Q000473:pathology; D001172:Arthritis, Rheumatoid / Q000201:enzymology* / Q000473:pathology; D015153:Blotting, Western; D051545:Cyclooxygenase 1; D051546:Cyclooxygenase 2; D017931:DNA Primers / Q000737:chemistry; D006801:Humans; D007124:Immunoenzyme Techniques; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism*; D007963:Leukocytes, Mononuclear / Q000201:enzymology / Q000473:pathology; D008565:Membrane Proteins; D011451:Prostaglandin-Endoperoxide Synthases / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D013582:Synovial Fluid / Q000166:cytology / Q000201:enzymology*
D017931:DNA Primers; D007527:Isoenzymes; D008565:Membrane Proteins; D012333:RNA, Messenger; D051545:Cyclooxygenase 1; D051546:Cyclooxygenase 2; C496511:PTGS1 protein, human; C496540:PTGS2 protein, human; D011451:Prostaglandin-Endoperoxide Synthases