MMP-2/gelatinase A is a gene product of human adult articular chondrocytes and is increased in osteoarthritic cartilage.
OBJECTIVE
Collagen fibril degeneration involves initially the cleavage within the triple helix by the collagenases (1 and 3), but then mainly involves also the gelatinases, of which gelatinase A (MMP-2) appears to play a central role in many tissues. The objective of this study was to determine the quantitative expression levels as well as the distribution in normal and osteoarthritic cartilage of gelatinase A and in cultured articular chondrocytes with and without stimulation by Il-1beta.


METHODS
Conventional and online PCR technology and immunohistochemistry were used to determine MMP-2 expression levels on the mRNA and protein level.


RESULTS
Conventional PCR analysis could demonstrate the presence of MMP-2 mRNA in normal and osteoarthritic chondrocytes. Online quantitative PCR confirmed the presence of MMP-2 mRNA expression in normal articular chondrocytes in vivo (and in vitro). An increase of 5x (p < 0.001) was observed in osteoarthritic cartilage in vivo. Of note, no significant up-regulation of gelatinase A was observed by Il-1beta in vitro. Immunostaining for gelatinase A confirmed the presence of MMP-2 with mono- and polyclonal antibodies in normal and osteoarthritic chondrocytes with somewhat higher levels observed in the latter.


CONCLUSIONS
The presented results confirm the increased expression of gelatinase A by osteoarthritic articular chondrocytes as previously described. Of note, also normal adult articular chondrocytes expressed significant amounts of gelatinase A in vivo and in vitro suggesting gelatinase A as being also involved in physiological collagen turnover in human adult articular cartilage.
Duerr
S
S
Osteoarticular and Arthritis Research, Department of Pathology, University of Erlangen-Nürnberg, Germany.
Stremme
S
S
Soeder
S
S
Bau
B
B
Aigner
T
T
D000368:Aged; D000369:Aged, 80 and over; D002358:Cartilage, Articular / Q000276:immunology; D018929:Cell Culture Techniques; D019902:Chondrocytes / Q000276:immunology*; D003094:Collagen / Q000276:immunology; D005260:Female; D006801:Humans; D007375:Interleukin-1 / Q000276:immunology*; D008297:Male; D020778:Matrix Metalloproteinase 2 / Q000096:biosynthesis* / Q000235:genetics; D008875:Middle Aged; D010003:Osteoarthritis / Q000276:immunology*; D016133:Polymerase Chain Reaction
D007375:Interleukin-1; D003094:Collagen; D020778:Matrix Metalloproteinase 2