Vascular endothelial growth factor (VEGF) plays a crucial role in the pathogenesis of inflammatory joint disease, including angiogenesis and synovitis. Rheumatoid arthritis is a chronic inflammatory disease characterized by progressive synovitis and subsequent bone destruction mediated by osteoclasts (OCs). In this study, we investigate the effects of VEGF on OC precursor cells (pOCs) using Raw cells and adjuvant-induced arthritis in rats. OCs and pOCs in the arthritic joints express VEGF and VEGF receptor type I (Flt-1). Raw cells also express Flt-1, and VEGF treatment stimulated chemotaxis, cell proliferation, the association of Flt-1 with focal adhesion kinase (FAK), and the tyrosine phosphorylation of FAK in Raw cells. The tyrosine phosphorylation of FAK was also observed in pOCs in the arthritic joints of adjuvant-induced arthritis. Adenovirus-mediated expression of FAK-related nonkinase in Raw cells inhibited the effects of VEGF in a dominant negative manner. Furthermore, intra-articular injection of the FAK-related nonkinase virus suppressed the recruitment of pOCs and bone destruction. Our results suggest the possible involvement of the VEGF-Flt-1-FAK pathway in inflammatory disease-induced joint destruction.
When mouse bone marrow cells were co-cultured with a stromal cell line. ST2, numerous osteoclast-like multinucleated cells (MNCs) were formed. To enrich the MNCs which were tartrate-resistant acid phosphatase (TRAP)-positive, we treated the cultures with dispase. Enriched TRAP-positive MNCs adhering to the bottom of the dish were cultured for a further 24h with medium containing 15% fetal calf serum. More than 80% of TRAP-positive MNCs were detached from the dish during the culture. However, when ST2 cells were included during the culture period, survival of TRAP-positive MNCs were significantly increased. Moreover, among various factors examined for the survival of TRAP-positive MNCs, only M-CSF and IL-1 alpha were effective in prolonging viability of TRAP-positive MNCs.
This report describes the case of a 47-year-old woman who was found to have subchondral insufficiency fractures in both femoral heads after renal transplantation. Initially, plain radiographs showed no obvious changes, but magnetic resonance imaging (MRI) revealed an irregular, discontinuous, low-intensity band on the T1-weighted image of both hips. The patient was treated nonsurgically. Ten months after onset, the pain in both hips disappeared, and plain radiographs and MRI showed no abnormalities. Subchondral insufficiency fracture should be considered in the diagnosis of patients who have hip pain after renal transplantation.
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