INCREASED CHITOTRIOSIDASE ACTIVITIES IN PATIENTS WITH RHEUMATOID ARTHRITIS: A POSSIBLE NOVEL MARKER?

Background: Chitotriosidase and YKL-40 are well-known in humans as Glyco_18 domain-containing proteins that are the common feature of mammalian chitinases and chitinase-like proteins. Previously, increased levels of YKL-40 were found correlated with the disease activity of rheumatoid arthritis. However, serum chitotriosidase activity in rheumatoid arthritis is not known yet. The aim of this study was to determine YKL-40 and chitotriosidase in patients with rheumatoid arthritis and to compare these markers with traditional ones such as C-reactive protein and erythrocyte sedimentation rate. Methods: Chitotriosidase, YKL-40 and C-reactive protein were measured in serum samples from 27 patients with rheumatoid arthritis and 27 healthy people. Chitotriosidase, YKL-40, C-reactive protein, and erythrocyte sedimentation rate were determined by a fluorometer, ELISA, nephelometer, and Western Green method, respectively. Results: Serum chitotriosidase activities and YKL-40 levels were higher in rheumatoid arthritis group than in control. A significant positive correlation was found between chitotriosidase and YKL-40. In ROC analysis, the areas under curves for chitotriosidase, C-reactive protein, erythrocyte sedimentation rate, and YKL-40 were 0.96, 0.84, 0.76, and 0.65, respectively. Area under the curve for chitotriosidase was significantly higher than the area for erythrocyte sedimentation rate (p=0.005) and for YKL-40 (p=0.0001), but not for Creactive protein (p=0.055). Conclusions: Serum chitotriosidase was significantly in creased in patients with rheumatoid arthritis. Among all the parameters evaluated, chitotriosidase was the most sensitive and specific one. Comprehensive studies covering larger populations are needed to elucidate the relationship between chitinases, in particular chitotriosidase and rheumatoid arthritis.