Interactions between interleukin‐1 and basic fibroblast growth factor on articular chondrocytes. Effects on cell growth, prostanoid production, and receptor modulation

Abstract

The interactions of interleukin-1β (IL-1β) and basic fibroblast growth factor (bFGF) with monolayer cultures of rabbit articular chondrocytes were examined. Both agonists resulted in a synergistic increase in prostanoid production, to levels higher than the maximal level for either protein alone. The synergy was time-and dose-dependent, was augmented in serum-free medium, and was blocked by indomethacin or a polyclonal antibody to IL-1β. The proteins had opposite effects on cell growth, and IL-1β completely blocked the mitogenic effect of bFGF. Pretreatment of cells with IL-1β induced a down-regulation in the number of the bFGF high-affinity receptors. Pretreatment of cells with bFGF increased the number of IL-1 receptors, which was dependent on messenger RNA synthesis.