ABSTRACT
The cartilage oligomeric matrix protein [COMP] is a glycoprotein, which occurs mainly in an articular cartilage. The amount of this protein increases under the influence of cytokines and growth factors. As a result of various diseases that cause damage to cartilage, fragments of matrix protein are released into synovial fluid and then into blood. The assessment of matrix protein level in serum, for example COMP, permits the establishment of the degree of cartilage damage in inflammatory joint diseases, and permits observation of the effectiveness of the treatment. To assess serum COMP level, as a marker for cartilage degradation, in SLE and OA patients and to find a correlation between serum COMP level and other markers as well as activity of disease, disease duration and the age of the patients. Blood was collected from 40 systemic lupus erythematosus [SLE] patients group I, [the patients were further subdivided into two subgroups, group [Ia] comprised 20 SLE patients received 1 g IV methylprednisolone [MP] daily for three successive days, group [Ib] comprised 20 SLE patients did not receive IV methylprednisolone [MP]], and from 20 patients with knee osteoarthritis [OA] group II who constituted the control group. Serum COMP level was determined using an inhibition enzyme-linked immunosorbent assay [ELISA]. The measured values of the serum COMP level in SLE patients ranged from 1.32 to 1.71 microg/ml with a mean of 1.51 +/- 0.13 microg/ml in group [Ia], and ranged from 2.43 to 3.56 microg/ml with a mean of 2.86 +/- 0.31 microg/ml in group [Ib]. While in OA group [II] the value of serum COMP ranged from 0.97 to 2.65 microg/ml with a mean of 1.25 +/- 0.37 microg/ml. We found significantly elevated COMP levels in the SLE group [Ib] compared to the SLE group [Ia] patients and OA group [II] [p < 0.001]. We found a statistically significant positive correlations with the number of tender joints [correlation coefficient Pearson's: r = 0.45, p < 0.01], the number of swollen joints [r = 0.55, p < 0.001], SLAM value [r = 0.56, p < 0.001]. A significant positive correlation was found between serum COMP level and the ESR value in the first hour [r = 0.35, p < 0.001]. While the serum COMP level was independent of the patients' age [r = 0.04, p = NS], disease duration [r = -0.03, p = NS] and morning stiffness duration [r = -0.05, p = NS]. Also a Negative correlation was found between the serum COMP level and haemoglobin value [r = -0.11, p = NS]. As regards the OA group, no correlation was found between the serum COMP level and patients' age [r = -0.05, p = NS] and disease duration [r = 0.24, p = NS]. There were positive correlations between serum COMP and WOMAC index score for the lower limbs [r = 0.64, p < 0.05]. The serum COMP level can be an important marker of disease activity and cartilage destruction in SLE and OA Patients, and that serum levels of COMP can be used as a parameter for monitoring the therapy response in SLE patients undergoing an intravenous bolus steroid therapy