Stimulation of the plasminogen activator activity of human synovial fibroblasts by retinoids.

Nonrheumatoid human synovial fibroblasts in culture, while having low basal plasminogen activator levels, were stimulated to produce much more of this protease activity by low concentrations of a series of retinoids. The most potent retinoid tested, all-trans retinoic acid, was active over the range 10(-11)-10(-6)M. The increased plasminogen activator activity in the presence of 10(-6)M retinoic acid was first observed within 40 minutes under appropriate experimental conditions, required RNA and protein synthesis, and was reversible after short incubation periods. This stimulation was suppressed by low concentrations of antiinflammatory glucocorticoids such as dexamethasone.