The effect of interleukin 1 beta on proteoglycans synthesized by human gingival fibroblasts in vitro

The effect of recombinant interleukin-1 beta (IL-1 beta) on proteoglycan synthesis by human gingival fibroblasts was investigated. IL-1 beta stimulated the gingival fibroblasts to proliferate. When compared to human foreskin fibroblasts, the gingival fibroblasts demonstrated a greater proliferative response at higher concentrations of IL-1 beta. The midpoint of the proliferation response for both cell types was in the 10(-11) M IL-1 beta range. The rate of [35S]-sulfate incorporation into proteoglycans by human gingival fibroblasts was enhanced by 40% at 10(-9) M IL-1 beta. This stimulatory effect appeared to be independent of cell proliferation and prostaglandin synthesis since blocking of these functions with hydroxyurea and indomethacin respectively, resulted in similar dose responses to IL-1 beta. Pulse chase experiments indicated the kinetics of degradation in the presence or absence of IL-1 beta were essentially identical. Therefore, the turnover rate of proteoglycans was not altered by IL-1 beta, no significant differences between molecular species, size or glycosaminoglycan composition of the proteoglycans synthesized in the presence or absence of IL-1 beta was noted. Thus, IL-1 beta can modulate extracellular matrix synthesis by human gingival fibroblasts and may therefore be partially responsible for the early events of healing following inflammatory episodes.