Laminin- and fibronectin-like molecules produced by periodontal ligament fibroblasts under serum-free culture are potent chemoattractants for gingival epithelial cells.

Previously, we revealed that hepatocyte growth factor (HGF) or an HGF-like factor secreted by periodontal ligament fibroblasts (PLF) and gingival fibroblasts cultured in the presence of serum was a major chemoattractant for gingival epithelial cells, and suggested that it might play a role in epithelial invasion. However, our recent study showed that serum-free culture of PLF and gingival fibroblasts produced potent chemoattractants other than HGF for gingival epithelial cells. To identify these chemoattractants, PLF-conditioned medium (PLF-CM) from serum-free cultures was obtained, concentrated, and separated by gel filtration column chromatography, and the chemotactic activity for gingival epithelial cells of each eluted fraction was monitored by a modified Boyden chamber assay. The chemoattractant activity was eluted at a molecular mass of around 600 kDa, which would include laminin and fibronectin, but not HGF, determined by ELISA. The chemotactic activity was reduced by treatment with antilaminin and/or antifibronectin polyclonal antibodies. Western blots using both antibodies revealed that the PLF-CM contained laminin- and fibronectin-like molecules. Along with HGF, these large glycoprotein molecules produced by PLF may be involved in the pathogenesis and progression of periodontitis by inducing the apical migration of epithelial cells.