Abstract

BACKGROUND
Matrix metalloproteinase (MMP)-1 and 3 are the most important degradating enzymes of the chondroid matrix. Chondrocytes may undergo apoptosis under various stimuli including nitric oxide (NO). We studied the expression rate and zone of MMP-1, MMP-3, nitrotyrosine, a marker of NO release, and apoptosis in the articular cartilage of human osteoarthritis.
METHODS
To investigate the role of nitrotyrosine and apoptosis in the degradation of the chondroid matrix in human osteoarthritis, immunohistochemistry was done for MMP-1, MMP-3, and nitrotyrosine; and the terminal deoxynucleotidyl transferase mediated nick end labeling (TUNEL) method was performed for apoptosis using a total of 93 articular cartilages from 12 femoral heads and 17 knees obtained from total joint arthroplasty and 7 normal articular cartilages. RESULTS: In the normal control group, the expression rates for MMP-1, MMP-3, nitrotyrosine, and apoptosis were very low; and their expression zones were confined to the superficial layer of the articular cartilage. Their expression rates were low in the early stage of osteoarthritis and were moderate to high in the late stage (P<0.05). Their expression zones were confined to the superficial layer of the articular cartilage in the early stage of osteoarthritis and were expressed throughout the whole layer in the late stage and those of MMP-3 and nitrotyrosine were statistically significant (P<0.05). Their expression rates and zones were significantly correlated with the grade of osteoarthritis (P<0.05). Conclusion : The expression rate and zone of apoptosis and nitrotyrosine correlated well with those of MMP-1 and MMP-3. Therefore, NO and apoptosis may be related to the progression of human osteoarthritis.

• Keywords: Human;Osteoarthritis;Interstitial collagenase;Nitric oxide;Apoptosis