Gingival epithelial cells secrete a substance which increases the collagenolytic enzyme activity of periodontal ligament cells.

To examine whether the gingival epithelium provokes a loss of connective tissue attachment during periodontitis, periodontal ligament (PDL) cells and gingival fibroblasts (GF) were cultured with conditioned medium of gingival epithelial cells, and the collagenolytic activity of PDL cells and GF were examined, respectively. The epithelial cells were cultured in the presence or absence of lipopolysaccharide (LPS), and the respective conditioned media were added to the cultures of PDL cells and GF. The collagenolytic response of PDL cells to both of the conditioned media was 3- to 10-fold higher than that of each control, whereas the response of GF was only 1.4-fold higher. The LPS-stimulated epithelial conditioned medium showed a stimulation rate for collagenolytic activity similar to that of the LPS-free conditioned medium. These results suggest that human gingival epithelial cells, without LPS stimulation, secrete a substance which accelerates the collagenolytic enzyme activity of PDL cells for degradation of PDL fibers, in the absence of GF enzyme activity.