1Maryam A. Abdurrahman, 1Dahalia A. Hussain, 1Samia A. Abdu, 2Faten M. Aly, 2Maha M. Fathy and 2Amany S. Awad
Departments of 1Internal Medicine and 2Microbiology & Immunology, Faculty of Medicine, Ain Shams University, Cairo, Egypt.
Matrix metalloproteinases (MMPs) play an important role in
the remodeling of cartilage extracellular matrix. However, they can initiate
tissue damage and subsequent joint destruction by proteolytic degradation of
collagens and proteoglycans. A naturally occurring inhibitor named tissue
inhibitor of metalloproteinase-1 (TIMP-1) regulates the action of interstitial
collagenase (MMP-1), which is a member of MMPs family. This study utilized
ELISA to measure serum levels of MMP-1 and its inhibitor TIMP-1 in two
different groups of arthritides: rheumatoid arthritis (RA) as a chronic
inflammatory arthritis, and knee osteoarthritis (KOA) as a degenerative
arthritis. Twenty two patients with RA, 18 patients with KOA and 10 healthy
controls were studied. We assessed how these markers correlate with each other,
with disease duration, disease progression and other established clinical and
laboratory markers of disease activity in the RA group. The results indicated
that serum MMP-1 is significantly higher in RA patients than KOA and normal
controls (p<0.01 for each). Also, significant differences in serum
TIMP-1values were observed between the controls and each of RA and KOA groups (p<0.01
& <0.05 respectively). But, the difference between RA and KOA patients
was insignificant. Serum MMP-1 values decreased significantly with progression
of RA severity, whereas TIMP-1 was higher in sera of patients with advanced RA
stages. On the other hand, serum TIMP-1 showed significant increase in late KOA
stages. Traditional systemic markers of RA activity (Ritchi articular index,
C-reactive protein and erythrocytic sedimentation rate) showed significant
negative correlations with serum TIMP-1 (p<0.05), and CRP showed significant
positive correlation with serum MMP-1 (p<0.05). No significant correlation
could be established between either MMP-1 or TIMP-1 and disease duration in
both groups. it is concluded that
serum levels of MMP-1 and TIMP-1 are elevated in both RA and KOA, and reflected
activity of RA disease. An imbalance between MMP-1 and TIMP-1, and not their
absolute values, may be the important factor in degradation of cartilage
extracellular matrix in RA and KOA.