[The role of hypoxia on expression of cyclooxygenase-2 in synovial fibroblasts derived from human temporomandular joint].
OBJECTIVE
To investigate the effects of hypoxia on expression of COX-2 in synovial fibroblasts derived from human TMJ and to analyze the biological role of COX-2 on TMJ disorders.


METHODS
Synovial fibroblasts were induced by hypoxia, COX-2 expression was determined by reverse transcription-polymerase chain reaction (RT-PCR) and Western blotting. Moreover, cells were stimulated by hypoxia or celecoxib or both of them, prostaglandin E(2) (PGE(2)), matrix metalloproteinase 2, 9 (MMP-2, MMP-9) release was detected by enzyme-linked immunosorbent assay (ELISA) or gelatin zymography. Cells that were placed under normoxic conditons were used as controls.


RESULTS
(1) In response to hypoxia, at 4 h (1.51 +/- 0.34), 8 h (1.39 +/- 0.57), significant elevation of COX-2 mRNA expression occurred, compared with data (0.65 +/- 0.24), (0.71 +/- 0.15) under normoxic condition (both P < 0.05). (2) The elevation of COX-2 protein was detectable at 6 h (0.29 +/- 0.06), 12 h (0.51 +/- 0.09), 24 h (0.68 +/- 0.11), contrasted with normoxia (all P < 0.01). Therefore, it is suggested that COX-2 expression pattern present a time-dependent response to hypoxic conditions. (3) The concentration of PGE(2) released by synovial fibroblasts under 12 h hypoxic condition (7.6 ng/ml +/- 0.8 ng/ml) was significantly higher than those under normoxic condition (2.5 ng/ml +/- 0.4 ng/ml, P < 0.01) or in response to celecoxib combined with hypoxia (4.3 ng/ml +/- 0.4 ng/ml, P < 0.05). (4) The amount of MMP-2, MMP-9 produced by synovial fibroblasts under 12 h hypoxic condition was upregulated compared with that under normoxia or in response to celecoxib combined with hypoxia.


CONCLUSIONS
Hypoxia is, at least in part, responsible for the pathogenesis of TMJ disorders, probably by promoting COX-2 expression of synovial fibroblasts derived from TMJ.
Ke
Jin
J
Key Lab for Oral Biomedical Engineering of Ministry of Education, School & Hospital of Stomatology, Wuhan University, Wuhan 430079, China.
Long
Xing
X
Liu
Yu
Y
Li
Jian
J
Meng
Qing-gong
QG
Fang
Wei
W
Cheng
Yong
Y
D015687:Cell Hypoxia; D002478:Cells, Cultured; D051546:Cyclooxygenase 2 / Q000096:biosynthesis* / Q000235:genetics; D005347:Fibroblasts / Q000378:metabolism*; D006801:Humans; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D013583:Synovial Membrane / Q000378:metabolism*; D013705:Temporomandibular Joint Disorders / Q000201:enzymology*
D012333:RNA, Messenger; D051546:Cyclooxygenase 2