Seong-Kyu Kim

Objective. Activation of toll-like receptor 9 (TLR9) has been proposed to play an inhibitory role in RANKL-induced osteoclastogenesis. A20 deubiquitinase has been found to be related to bone loss. This study investigated the role of CpG oligodeoxynucleotides (CpG-ODNs) through regulation of A20 deubiquitinase in RANKL-induced osteoclast formation. Methods. RAW 264.7 cells, a murine monocyte-macrophage cell line, were incubated with or without CpG-ODN in the presence of RANKL. Osteoclast-specific genes and their related signaling molecules were measured by real-time quantitative polymerase chain reaction and Western blot assay. Morphological assessment for osteoclast formation was performed using tartrate-resistant acid phosphatase (TRAP) staining and F-actin ring formation staining. Results. RANKL-induced osteoclast-related genes and proteins, c-Fos, NFATc1, TRAP, cathepsin K, and carbonic anhydrase II were significantly inhibited in RAW 264.7 cells stimulated with CpG-ODN. CpG-ODN attenuated TNF receptor-associated factor 6 (TRAF6), p-IκBα, and p-NF-κB expression in RAW 264 cells mediated by RANKL. CpG-ODN increased A20 gene and proteins in time-dependent manner. A20 expression under costimulation with CpG-ODN and RANKL was more decreased than under stimulation with RANKL alone. Cells transfected with A20 siRNA augmented expression of osteoclast-related genes and proteins. Number of TRAP-positive cells transfected with A20 siRNA was higher than those transfected with NC siRNA. A20 expression in cells transfected with IL-1β siRNA in the presence of both RANKL and CpG-ODN was more decreased than those with NC siRNA. Conclusion. This study showed that CpG-ODN suppressed RANKL-induced osteoclast formation through regulation of the A20-TRAF6 axis in RAW 264.7 cells.

Rheumatoid arthritis (RA) is associated with premature atherosclerosis and increased risk of cardiovascular disease (CVD). The purpose of this study was to assess the relationship between disease activity and arterial stiffness indexes for CVD in RA patients. Two hundred twenty-two female RA patients were retrospectively recruited. Non-invasive arterial stiffness was assessed by brachial-ankle PWV (baPWV) and ankle-brachial index (ABI) using pulse wave analyses and the augmentation index (AIx). The AIx was classified into two groups of normal (grade 0) and abnormal (grade 1, 2, and 3). The baPWV was associated with only age and rheumatoid factor titer, but not disease activity index, DAS28-ESR. Univariate analysis indicated that AIx was related to body mass index, disease duration, and DAS28-ESR. In addition, the baPWV was associated with DAS28-ESR and disease duration after adjusting for confounding factors (β = 0.147, p = 0.032 and β = 0.183, p = 0.034, respectively). Multivariate logistic regression analysis showed that the tendency for abnormal AIx increased as DAS28-ESR increased, and the result was significant ( p for trend = 0.026). The results of this study indicated that the relationship between AIx and DAS28-ESR suggests that disease activity could affect arterial stiffness in RA.