RHEUMATOID SYNOVIAL FIBROBLAST ADHESION TO HUMAN ARTICULAR-CARTILAGE - ENHANCEMENT BY NEUTROPHIL PROTEASES

Objective. To determine if preexposure of human articular cartilage to activated neutrophils alters rheumatoid synovial fibroblast adhesion to human articular cartilage. Methods. Human articular cartilage was e xposed to either activated neutrophils, interleukin-1, or supernatants obtained from activated neutrophils that had been treated with differ ent protease inhibitors. Radiolabeled rheumatoid synovial fibroblasts were then incubated with the cartilage and the number of counts associ ated with the cartilage was determined. Results. Pretreatment of human articular cartilage with either activated neutrophils or supernatants obtained from activated neutrophils enhanced subsequent rheumatoid sy novial fibroblast adhesion. In contrast, interleukin-1 treatment of ca rtilage did not alter the adhesion of synovial fibroblasts. The enhanc ed adhesion could be attenuated by pretreatment of the neutrophil supe rnatants with either diisopropylfluorophosphonate or EGTA and almost c ompletely abolished by using both inhibitors. Conclusion. This study d emonstrates that adhesion of rheumatoid synovial fibroblasts to human articular cartilage can be enhanced by exposing the cartilage to prote ases released by neutrophils. These results suggest that neutrophil pr oducts may play a role in enhancing adhesion of rheumatoid synovium to cartilage in vivo.