Stimulation of human periodontal ligament fibroblast collagenase production by a gingival epithelial cell-derived factor

Summary To examine whether cell‐to‐cell interactions between human gingival epithelial cells (HGE) and periodontal ligament fibroblasts (PLF) or gingival fibroblasts (GF) take place in the periodontium, the effects on collagenase production by PLF and GF were analyzed after adding several concentrations of HGE‐con‐ditioned medium (HGE‐CM) to PLF or GF culture. Collagenase production by both cell populations was stimulated by adding HGE‐CM, which stimulated collagenase production by PLF to a greater extent than that by GF. The HGE‐derived stimulatory factor had a molecular mass of approximately 20 kDa, and its stimulant effect was inhibited markedly in the presence of an anti‐human interleukin‐lα (IL‐lα) neutralizing antibody, indicating that the factor was identical to, or antigenically cross‐reactive with, IL‐lα. These results suggest that epithelial apical migration in the periodontium may occur after interstitial resident cells have released tissue‐degrading enzymes, such as collagenase, and damaged the extracellular matrix, once a sufficient amount of IL‐lα‐like factor for stimulating the production of proteolytic enzyme has been released by HGE in periodontal lesions.