Tryptase enhances release of vascular endothelial growth factor from human osteoarthritic chondrocytes.
OBJECTIVE
A contribution of mast cells and its mediators in the pathogenesis of arthritis has been postulated. We aimed to clarify the role of mast cell-derived serine protease tryptase and proteinase activated receptor (PAR)-2-mediated signaling in chondrocytes.


METHODS
Human articular cartilage specimens were obtained from patients with osteoarthritis (OA), rheumatoid arthritis (RA) and with traumatic fracture without arthritis (PT; as controls) who underwent joint surgery. Isolated chondrocytes were cultured in vitro by monolayer, and confluent cells were incubated with recombinant human lung Beta tryptase or with a PAR-2 agonist peptide. The secreted level of vascular endothelial growth factor (VEGF) in culture supernatant was measured using commercially available ELISA kits, and expression of VEGF mRNA was analyzed using real-time PCR.


RESULTS
The tryptase-stimulated chondrocytes from OA or RA, but not from PT patients, produced significantly higher amount of VEGF in their supernatants. The response was blocked by a G-protein receptor inhibitor pertussis toxin, however, was not reproduced by incubation of cells with the PAR-2 agonist, suggesting a presence of non-PAR-2 dependent signals for the VEGF induction. In addition, actinomycin D and cycloheximide did not exert significant inhibition, indicating a regulation of VEGF release by tryptase.


CONCLUSIONS
The inflammatory mediator, mast cell-derived protease tryptase may modulate chondrocyte metabolism through induction of VEGF release.
Masuko
K
K
Department of Bioregulation and Proteomics, Institute of Medical Science, St. Marianna University School of Medicine, Kawasaki-shi, Kanagawa, Japan. kmarianna@mac.com
Murata
M
M
Xiang
Y
Y
Nakamura
H
H
Yudoh
K
K
Nishioka
K
K
Beppu
M
M
Kato
T
T
D001172:Arthritis, Rheumatoid / Q000378:metabolism; D002478:Cells, Cultured; D019902:Chondrocytes / Q000187:drug effects* / Q000378:metabolism; D003513:Cycloheximide / Q000494:pharmacology; D003609:Dactinomycin / Q000494:pharmacology; D005260:Female; D050723:Fractures, Bone / Q000378:metabolism; D006801:Humans; D008297:Male; D010003:Osteoarthritis / Q000378:metabolism*; D037342:Pertussis Toxin / Q000494:pharmacology; D016133:Polymerase Chain Reaction; D044464:Receptor, PAR-2 / Q000819:agonists; D053802:Tryptases / Q000494:pharmacology*; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism*
D044464:Receptor, PAR-2; D042461:Vascular Endothelial Growth Factor A; D003609:Dactinomycin; D003513:Cycloheximide; D037342:Pertussis Toxin; D053802:Tryptases