Relationship between sonographic parameters and YKL-40 levels in rheumatoid arthritis

Abstract

YKL-40, also known as human cartilage glycoprotein 39, is a member of the "mammalian chitinase-like proteins" family without chitinase activity. Increased serum concentrations are associated with inflammatory processes and several types of cancer. In this study, we evaluated YKL-40 levels in serum and synovial fluid of patients with rheumatoid arthritis in comparison with the ultrasonographic findings. YKL-40 levels were measured by enzyme-linked immunosorbent assay in 25 patients with active rheumatoid arthritis and in 40 healthy subjects. B mode and power Doppler were performed to determine synovial thickening and vascularization. Serum YKL-40 level in patients was significantly higher than the concentration in healthy controls (P < 0.01). In patients with rheumatoid arthritis, the level of the glycoprotein in synovial fluid was remarkably elevated compared to the serum level (P = 0.003). The B mode and power Doppler scores correlated to YKL-40 in serum and synovial fluid (P = 0.07). Serum YKL-40 levels were related positively to serum markers of inflammation such as C-reactive protein (P = 0.004) and erythrocyte sedimentation rate (P = 0.003). This study is the first to demonstrate a relationship between YKL-40 levels and ultrasonographic examinations in Bulgarian patients with rheumatoid arthritis. The findings suggest that YKL-40 might be implicated in the pathogenesis of the disease and could indicate the level of joint inflammation.

YKL‐40: The Search for New Biomarkers in Rheumatoid Arthritis

“…Our observations focused on YKL-40 in RA patients also found signiicantly higher glycoprotein concentrations in the synovial luid in comparison with serum levels [35]. However, we determined the same patern of expression in other inlammatory joint diseases such as osteoarthritis, gout, and psoriatic arthritis [56].…”

“…A relationship between ultrasonographic indings and YKL-40 was detected. Analysis of the data conirmed that the sonographic inlammation correlated with angiogenesis of the synovial membrane [35].…”

“…We also determined a strong association between YKL-40 levels in serum and synovial luid and CRP and ESR [35]. Thus, YKL-40 could be regarded as an informative proinlammatory biomarker.…”

“…Johansen proposed serum YKL-40 concentration higher than 20% to be considered as elevated [32]. Published levels of YKL-40 in healthy individuals difer among populations [33][34][35] and are shown in Table 1. We could speculate that divergent YKL-40 levels could be explained with diferences in sample collection and assays, genetic polymorphisms, or even epigenetics.…”

Correlation between protein YKL-40 and ultrasonographic findings in active knee osteoarthritis

“…We used the ranges of YKL-40 in the serum of healthy individuals found in previous investigations [21]. The control group consisted of 40 healthy subjects (24 women and 14 men).…”