Fibulin-3 and other cartilage metabolism biomarkers in relationship to calprotectin (MRP8/14) and disease activity in rheumatoid arthritis patients treated with anti-TNF therapy

BACKGROUND: Fibulin-3 (Fib-3) is a new potential biomarker of articular cartilage metabolism. OBJECTIVES: The aim of the study was to evaluate the effect of anti-TNF therapy on serum fibulin-3, cartilage oligomeric matrix protein (COMP), procollagen II C-propeptide (PIICP), and urinary C-terminal telopeptide of type II collagen (CTX-II) levels in relation to calprotectin (MRP8/14) and disease activity in rheumatoid arthritis patients. MATERIAL AND METHODS: In the study, 35 female patients with rheumatoid arthritis (RA) were investigated. The concentration of fibulin-3, COMP, PIICP, MRP8/14, and urinary CTX-II in serum was measured before and after anti-TNF therapy. Ten healthy women were investigated as the controls. RESULTS: The concentration of fibulin-3 in RA patients before treatment did not differ significantly from the concentration of fibulin-3 in the control group. A significantly higher concentration of fibulin-3 was noted prior to treatment in the group of women with a worse response to the therapy (non-responders) compared to the concentration of fibulin-3 in the healthy women. During the anti-TNF therapy, the serum fibulin-3 level decreased in patients. The fibulin-3 level correlated with CRP and ESR after anti-TNF treatment. Significant lowering of MRP8/14 was noted in the patients after anti-TNF therapy. No correlation between fibulin-3 and MRP8/14 was observed in the study group or in the control group. CONCLUSIONS: During the anti-TNF therapy, the serum fibulin-3 level decreased in RA patients. Serum MRP8/14 concentration also decreased. No correlation between fibulin-3 and MRP8/14 was observed in the study group before and after the treatment. We found a poor correlation between serum fibulin-3 and other cartilage metabolism biomarkers after anti-TNF therapy.