Interleukin 1 receptor on fibroblasts from systemic sclerosis patients induces excessive functional responses to interleukin 1 beta.

To determine if SSc fibroblasts are more sensitive to exogenous IL-1 than are normal fibroblasts, we studied the inductions of IL-6, prostaglandin E2 (PGE2), IL-1 beta mRNA production by IL-1-stimulated SSc and normal fibroblasts. The minimal IL-1 beta concentrations for stimulation of IL-6 and PGE2 production by SSc fibroblasts were 10-fold and 100-fold lower, respectively, than those for normal fibroblasts. The minimal IL-1 beta concentration for stimulation of IL-1 beta mRNA expression by SSc fibroblasts was also 10-fold lower than that for normal fibroblasts. These results suggest that the IL-1 signal transduction through IL-1R could be induced excessively in SSc fibroblasts. It is suggested that the IL-1 signal transduction plays an important role in the abnormal cytokine networks observed in the fibrosis of SSc.