Evaluation of some non traditional biochemical markers of joint damage in patients with early rheumatoid arthritis : an updating clinical guideline

الملخص EN

Background Identifying rheumatoid arthritis (RA) patients at high risk for progression of joint damage at early stage is of particular importance for the management of the disease.

Despite advances in laboratory and radiological technologies, it is still difficult to evaluate joint damage due to lack of reliable and specific markers indicating the presence and extent of joint destruction.

Aim of this study was to assess serum levels of YKL-40; cartilage oligomer matrix protein (COMP) and melanoma inhibitory activity (MIA) in patients with early rheumatoid arthritis, to correlate their levels with the degree of joint destruction and laboratory parameters of disease activity, and to find out which of these proteins can be used as a reliable marker for joint destruction. Subject and Methods: The study included 30 patients with early rheumatoid arthritis (disease duration less than 2 years) and 15 healthy subjects as control.

Radiological changes reflecting joint destruction were evaluated by Larsen score and the patients were assigned into non-erosive (Larsen score<2; n=15) and erosive arthritis (Larsen score ≥ 2; n=15) patients.

Serum levels of YKL-40, COMP and MIA were measured by ELISA. Results : there was a significant elevation of serum levels of YKL-40, COMP and MIA in RA patients vs.

control (p< 0.001).

Also, a significant elevation of serum levels of YKL-40 and MIA was found in erosive vs.

non-erosive RA patients (p < 0.001 and p< 0.05; respectively) however, no significant difference was found in serum COMP levels between erosive and non-erosive RA patients.

Significant positive correlations were observed between serum levels of YKL-40, COMP and MIA.

Moreover, YKL-40 serum levels were positively correlated with ESR and serum CRP (P < 0.001).

In our study, serum levels of YKL-40, COMP and MIA showed significant correlations with the degree of joint destruction (p<0.01, p< 0.05 and p < 0.001; respectively). However, no relationship was observed between ESR or serum CRP and the degree of joint destruction. Conclusion: YKL-40 is a potentially useful marker to predict the risk of joint damage in patients with early RA while COMP may be used as a prognostic marker of cartilage degradation in RA patients. Elevated levels of serum MIA very likely reflects chondrocyte activation in conjugation with joint destruction in RA and not the inflammation associated with disease.

Thus, it is recommended as a new reliable marker for early identification of patients with aggressive disease.

It can also be used for prognostic purposes, to detect disease progression and to monitor the effects of therapy.