Expression of integrins by human periodontal ligament and gingival fibroblasts and their involvement in fibroblast adhesion to enamel matrix-derived proteins

We showed recently that human periodontal ligament (PDL) and gingival fibroblasts adhere and spread on enamel matrix protein (EMP) coatings (1). In the present study, we investigated whether this interaction can be attributed to integrin expression. Human PDL and gingival fibroblasts were cultured for periods up to 24 h on EMP coatings, in the presence of synthetic RGD-containing peptide or an antibody against the beta(1) integrin subunit. The cells were first cultured for 24 h under serum-free conditions and then cultured on EMP coatings for 48 h. Integrin expression levels were assessed by flow cytometry analysis. It was found that attachment and spreading on EMP was inhibited by the synthetic RGD-containing peptide, but not by a synthetic RGE-peptide. Both PDL and gingival fibroblasts showed expression of the integrin subunits, alpha(2), alpha(5), beta(1), and the integrin, alpha(v)beta(3). Incubation with an antibody against the beta(1) subunit significantly inhibited the attachment and spreading of PDL and gingival fibroblasts on EMP coatings. We conclude that integrins are involved in the interaction of PDL and gingival fibroblasts with EMP.