Proliferation of small vessels including capillaries in joint tissues is one of the significant histopathological features of rapidly destructive coxarthropathy (RDC). To examine the relationship between the angiogenesis and bone destruction, expression of urokinase-type plasminogen activator (uPA) and uPA receptor (uPAR), which are necessary for angiogenesis was histochemically investigated.
Synovia and cartilage-bone tissues of femoral head were obtained from RDC patients at total hip replacement (THR). These joint tissues were fixed with 4% paraformaldehyde, and cartilage-bone tissues were decalcified, additionally. Immunohistochemical staining was performed on paraffin sections, using monoclonal antibodies against human uPA and uPAR.
There was a difference between expression of uPA and that of uPAR. Expression of uPA was observed in many types of cells such as osteoclasts, giant cells, fibroblast-like cells and macrophages, of which osteoclasts and giant cells were most prominent. On the other hand, expression of uPAR was detected mainly in fibroblast-like cells and macrophages and rarely seen in osteoclasts and giant cells.
These results indicate that uPA-plasmin system contributes to bone destruction in RDC, and furthermore, that fibroblast-like cells and macrophages play an important role in activation of uPA-plasmin system.