RESUMO
OBJECTIVES: We investigated the effects of compressive mechanical stress on osteoclastogenesis of synovial cells to clarify the mechanism of osteoclast formation by those cells in temporomandibular joint (TMJ) disorders. STUDY DESIGN: Synovial cells were isolated from rat knee joints and continuously compressed using a conventional method. The expression of receptor activator nuclear factor kappaB ligand (RANKL) mRNA and protein in synovial cells was analyzed by reverse transcriptase-polymerase chain reaction, immunoblotting, and immunofluorescence staining. Mouse bone marrow cells were cultured with synovial cells for 7 days to detect osteoclasts. RESULTS: The expressions of RANKL mRNA and protein in synovial cells were increased with compressive force. When mouse bone marrow cells were cultured with continuously compressed synovial cells, tartrate-resistant acid phosphatase-positive multinucleated cells were formed. Osteoprotegerin completely inhibited osteoclast formation induced by culturing with compressed synovial cells. CONCLUSION: Our results indicated that the expression of RANKL in compressed synovial cells enhanced osteoclast formation, whereas continuous compressive force may induce osteoclastic bone destruction in the TMJ.
Assuntos
Análise do Estresse Dentário , Osteoclastos/citologia , Ligante RANK/biossíntese , Membrana Sinovial/metabolismo , Transtornos da Articulação Temporomandibular/patologia , Animais , Western Blotting , Células da Medula Óssea/citologia , Diferenciação Celular , Células Cultivadas , Técnicas de Cocultura , Força Compressiva , Masculino , Camundongos , Camundongos Endogâmicos , Microscopia de Fluorescência , Osteoclastos/efeitos dos fármacos , Osteoprotegerina/farmacologia , Ratos , Ratos Sprague-Dawley , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Estresse Mecânico , Membrana Sinovial/citologiaRESUMO
The present study was designed to evaluate the effects of neuropeptide substance P (SP) on the formation of osteoclasts via synovial fibroblastic cells. Synovial fibroblastic cells derived from rat knee joint expressed the SP receptor, neurokinin-1 receptor (NK(1)-R). The addition of SP stimulated the proliferation of synovial fibroblastic cells and this effect was inhibited by SP or NK(1)-R antagonists. Increased expression of the receptor activator of nuclear factor kappaB ligand (RANKL) in synovial fibroblastic cells after the addition of SP was demonstrated by reverse transcriptase-polymerase chain reaction and immunofluorescence staining. Osteoprotegerin expression in synovial fibroblastic cells was decreased after incubation with SP. In co-cultures of synovial fibroblastic cells and rat peripheral blood monocytes, SP stimulated osteoclastogenesis. These results suggest that SP in the joint cavity may cause both hypertrophy of the synovium and induction of increased osteoclast formation through the increased expression of RANKL in the synovium.