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.