Association of interleukin-1-induced, NFκB DNA-binding activity with collagenase gene expression in human gingival fibroblasts

During earlier examination of interleukin-1 (IL-1)-induced matrix metalloproteinase gene expression in human gingival fibroblasts a highly induced immediate early gene, IκB-α, a NFκB DNA-binding inhibitor, was identified. The aim now was to investigate whether recombinant (r)IL-1β induces the stimulation of NFκB and its inhibitor proteins in human gingival fibroblasts and to understand if inhibition of its activity affects collagenase gene expression. Primary gingival fibroblasts (human) were treated with rIL-1β to determine the effect on NFκB-like DNA-binding activity. IL-1 induced the production of steady-state mRNA levels of IκB-α in the cultured fibroblasts. Nuclear run-on transcription studies demonstrated that rIL-1 induction of IκB-α may be transcriptionally regulated. Using electrophoretic mobility gel-shift assays it was shown that rIL-1 activates NFκB-like DNA-binding activity in these fibroblasts. NFκB-like DNA-binding activity was rapidly induced and turned over in gingival fibroblasts with peak activity at 30 min after rIL-1 treatment. Further, treatment with chymotrypsin protease inhibitor and antioxidant inhibitor prevented IL-1-induced, NFκB-like, DNA-binding activity and collagenase mRNA production. When coupled with the existence of NFκB consensus DNA-binding sites on the collagenase gene promoter, these findings suggest that the stimulation of NFκB in gingival fibroblasts by rIL-1 could play an important part in the regulation of their collagenase gene expression. The ability of IL-1 to stimulate this expression may define a pivotal role for this cytokine in the pathogenesis of periodontitis.