Intermittent hydrostatic pressure inhibits matrix metalloproteinase and pro-inflammatory mediator release from human osteoarthritic chondrocytes in vitro.
OBJECTIVE
This study tested the hypothesis that intermittent hydrostatic pressure applied to human osteoarthritic chondrocytes modulates matrix metalloproteinase and pro-inflammatory mediator release in vitro.


METHODS
Human osteoarthritic articular chondrocytes were isolated and cultured as primary high-density monolayers. For testing, chondrocyte cultures were transferred to serum-free medium and maintained without loading or with exposure to intermittent hydrostatic pressure (IHP) at 10 MPa at a frequency of 1 Hz for periods of 6, 12 and 24 h. Levels of matrix metalloproteinase-2, -9 (MMP-2, -9), tissue inhibitor of metalloproteinase-1 (TIMP-1), and the pro-inflammatory mediators, interleukin-6 (IL-6) and monocyte chemoattractant protein-1 (MCP-1), released into the culture medium were assessed by ELISA. Matrix metalloproteinase activity was confirmed by zymographic analysis.


RESULTS
In the absence of IHP, levels of MMP-2, TIMP-1, IL-6, and MCP-1 in the chondrocyte culture medium increased in a time-dependent manner. Application of IHP decreased MMP-2 levels at all time periods tested, relative to unloaded control cultures maintained for the same time periods. Although 84/82 kDa bands were faintly detectable by zymography, MMP-9 levels were not quantifiable in medium from loaded or unloaded cultures by ELISA. TIMP-1 levels were not altered in response to IHP at any time period tested. IL-6 and MCP-1 levels decreased in cultures exposed to IHP at 12 and 24 h, relative to unloaded control cultures maintained for the same time periods.


CONCLUSIONS
IHP decreased release of MMP-2, IL-6 and MCP-1 by osteoarthritic chondrocytes in vitro suggesting that pressure influences cartilage stability by modulating chondrocyte expression of these degradative and pro-inflammatory proteins in vivo.
Orthopaedic Research Laboratory, Stanford University School of Medicine, Stanford, CA 94305-5341, USA.
Michael C D
MC
Trindade
Jun-ichi
J
Shida
Takashi
T
Ikenoue
Mel S
MS
Lee
Eric Y
EY
Lin
Burt
B
Yaszay
Scott
S
Yerby
Stuart B
SB
Goodman
David J
DJ
Schurman
R Lane
RL
Smith
D002358:Cartilage, Articular / Q000201:enzymology* / Q000276:immunology; D002478:Cells, Cultured; D018932:Chemokine CCL2 / Q000032:analysis / Q000378:metabolism; D019902:Chondrocytes / Q000276:immunology / Q000378:metabolism*; D016207:Cytokines / Q000378:metabolism*; D006801:Humans; D006874:Hydrostatic Pressure; D015850:Interleukin-6 / Q000032:analysis / Q000378:metabolism; D020782:Matrix Metalloproteinases / Q000032:analysis / Q000378:metabolism*; D010003:Osteoarthritis / Q000201:enzymology* / Q000276:immunology; D018709:Statistics, Nonparametric
C111835:CCL2 protein, human; D018932:Chemokine CCL2; D016207:Cytokines; D015850:Interleukin-6; D020782:Matrix Metalloproteinases