Association between radiographic hand osteoarthritis and RANKL, OPG and inflammatory markers

Objective: The aim of the study was to evaluate the association between prevalence and severity of radiographic hand osteoarthritis (OA) and serum levels of systemic inflammatory markers in a community-based population sample. Design: A cross-sectional observational study was conducted on a population comprised 1452 Chuvashians (763 males, aged 49.23±17.43; and 689 females, aged 50.37±17.47 years). OA was evaluated in 14 joints of each hand using Kellgren and Lawrence (K-L), joint space narrowing (JSN) and osteophyte (OS) scores. Serum levels of systemic inflammatory and osteoclastogenic cytokines were measured by an enzyme-linked immunosorbent assay (ELISA). Statistical analyses included descriptive statistics, correlation analysis and multiple linear regressions. Results: Monocyte chemotactic protein-1 (MCP-1) and osteoprotegerin (OPG) levels were associated with OA traits, but the statistically significant correlations were weak and/or moderate. In particular, the MCP-1 inflammation marker showed a statistically significant association with JSN (β= 0.077, P= 0.022) and OS (β= 0.067, P= 0.024) scores, but not with the number of affected joints (K-L≥2). OPG was significantly correlated with the scores as to the number of affected joints (β= 0.063, P= 0.035) and OS (β= 0.077, P= 0.028). No significant associations were found between levels of other inflammatory [interleukin (IL)-6, tumor necrosis factor (TNF)-α, IL-17] and osteoclastogenic [receptor activator for nuclear factor κ B ligand (RANKL), macrophage colony-stimulating factor (M-CSF)] cytokines and OA characteristics. Conclusions: This study strengthens the premise that OPG might be a valid biomarker of hand OA. Confirmation of these results in larger cohorts of patients will reinforce our theory that the RANKL/OPG pathway is a suitable target for developing novel agents against OA.