Characterization and Function of Tumor Necrosis Factor and Interleukin-6-Induced Osteoclasts in Rheumatoid Arthritis.

OBJECTIVE: We have previously reported that stimulation of mouse bone marrow-derived macrophages with tumor necrosis factor (TNF) and interleukin-6 (IL-6) induces differentiation of osteoclast-like cells. We undertook this study to clarify the characterization and function of human TNF and IL-6-induced osteoclasts using peripheral blood collected from patients with rheumatoid arthritis (RA) and healthy donors. METHODS: Peripheral blood monocytes were cultured with a combination of TNF and IL-6, TNF alone, IL-6 alone, or with RANKL, and their bone resorption ability was evaluated. Expression levels of NFATc1, proinflammatory cytokines, and matrix metalloproteinase 3 were analyzed. The effects of NFAT inhibitor and JAK inhibitor were examined. Furthermore, the relationship between the number of TNF and IL-6-induced osteoclasts or RANKL-induced osteoclasts differentiated from peripheral blood mononuclear cells (PBMCs) in patients with RA and the modified total Sharp score (mTSS) or whole-body bone mineral density (BMD) was examined. RESULTS: Peripheral blood monocytes stimulated with a TNF and IL-6-induced osteoclasts were shown to demonstrate the ability to absorb bone matrix. Cell differentiation was not inhibited by the addition of osteoprotegerin. Stimulation with a combination of TNF and IL-6 promoted NFATc1 expression, whereas the NFAT and JAK inhibitors prevented TNF and IL-6-induced osteoclast formation. Expression levels of IL1ß, TNF, IL12p40, and MMP3 were significantly increased in TNF and IL-6-induced osteoclasts, but not in RANKL-induced osteoclasts. The number of TNF and IL-6-induced osteoclasts differentiated from PBMCs in patients with RA positively correlated with the mTSS, whereas RANKL-induced osteoclast numbers negatively correlated with the whole-body BMD of the same patients. CONCLUSION: Our results demonstrate that TNF and IL-6-induced osteoclasts may contribute to the pathology of inflammatory arthritis associated with joint destruction, such as RA.

Plasma pentraxin 3 is associated with progression of radiographic joint damage, but not carotid atherosclerosis, in female rheumatoid arthritis patients: 3-year prospective study.

Background: Pentraxin 3 (PTX3) has an important role in inflammation, immunity, and atherosclerosis. Rheumatoid arthritis (RA) is a chronic inflammatory disease featuring both joint damage and atherosclerosis. We investigated whether the plasma PTX3 level was associated with progression of joint destruction and subclinical atherosclerosis in RA patients.Methods: Plasma PTX3 levels were measured in 72 women with RA and 80 female control subjects. In RA patients, we also evaluated clinical characteristics, medications, and at one and three years, joint damage and atherosclerosis. Then we investigated whether PTX3 was associated with progression of joint destruction or an increase of carotid intima-media thickness (IMT).Results: Plasma PTX3 levels were significantly higher in the RA patients than in healthy controls (4.05 ± 2.91 ng/mL vs. 1.61 ± 1.05 ng/mL, p < .001). By multivariate linear regression analysis, the plasma pentraxin 3 level was independently associated with radiographic progression of joint damage for 3 years in the RA patients after adjustment for age, disease duration, body mass index, rheumatoid factor, MMP-3, Disease Activity Score 28-ESR, postmenopausal status, current use of corticosteroids and biologic use. On the other hands, pentraxin 3 was not associated with an increase of carotid intima-media thickness in RA patients.Conclusion: Female RA patients had elevated plasma PTX3 levels compared with control female subjects. PTX3 was independently associated with radiographic progression of joint damage in the RA patients, but not with carotid atherosclerosis.