Investigation of synoviocytes in rheumatoid arthritis to differentiated into osteoclasts in vitro / 中华风湿病学杂志

ABSTRACT

Objectives To investigate the origination of osteoclast precursors in synovial tissue from rheumatoid arthritis (RA), and the role of receptor activitor of NF-?资B ligand (RANKL) in synoviocyte differentating into osteoclast in vitro. Methods Synovium were obtained from 6 patients with RA and 6 synovial normal samples at the time of operation. Synoviocytes were obtained by digesting synovial tissue with collagenase. CD68-positive and CD68-negative synoviocytes were obtained by Dynabeads (magnetic cell sorting). To identify the origin of osteoclast precursors from synovium, all types of selected synoviocytes were incubated containing bone slices respectively and induced differentiation in the presence of RANKL (16 ?g/L), macrophage colony stimulating factor (M-CSF) (25 ?g/L) and Dexamethasone (10-8 mol/L) and at every medium change. Osteoclast formation was evaluated in tartrate resistant acid phosphatase (TRAP), calcitonin receptors (CTR) and bone-resorption activities. Furthermore, RANKL was added to the cocultures at gradient concentrations of range 0 ?g/L to 8 ?g/L in the presence of M-CSF and Dexamethasone at the beginning of each experiment for inducing CD68+ synoviocyte in RA differentiation on bone slices. After 14 days, bone slices stained with toluidine blue. Bone resorption was evaluated by scanning the area of resorption pits with a digital analyzer. Results After 14 days incubation in the presence of RANKL, TRAP-positive?VNR-positive and resorption lacunaeas cells were only observed on the groups of CD68+ synoviocytes from RA. The activity of osteoclasts derived from CD68+ synoviocytes in RA had influenced by difference concentrations of RANKL. Conclusion CD68+ synoviocytes are identified as the osteoclast precursors in synovium with RA, and can be sufficiently induced to be the functional and mature osteoclasts by RANKL in vitro. RANKL, as a cytokine, is an essential factor for osteoclast development and stimulate osteoclasts which were derived from CD68+ synoviocytes in RA development and activation.