Cell surface glycoconjugates of gingival fibroblasts exposed to dental plaque extract.

Abstract

The cell surface glycoconjugates of human gingival fibroblasts exposed in a culture to dental plaque extract were studied by surface labeling techniques and indirect immunoflurescennce. After 24 h of exposure, the fibroblast morphology changed from well‐spread to spindle‐like. This alteration was associated with a disappearance of the intercellular fibronectin (FN) network and most of the high molecular weight cell surface glycoproteins. These effects of the extract were prevented by heating. After prolonged treatment with the native extract, a 80 kd glycoprotein disappeared and a 140 kd glycoprotein was replaced by a 110 kd polypeptide, but the trypsin sensitive 55 kd glycoprotein remained on the surface of the treated cells. The protcolytic activity of the plaque extract degraded the FN to various fragments with a different molecular weight than previously obtained with several purified mammalian enzymes. After a 24 h incubation of the treated cells in a normal, serum supplemented medium, the normal surface characteristics and FN network were recovered. In the treated cells, the phosphorylation of the cell surface glycoproteins was increased as well as the activity of the hyaluronic acid synthetase. The results suggest that plaque extract has a dual role in affecting the behavior of gingival fibroblasts. First, the enzymatic degradation of the FN network and surface glycoproteins destroys the association between the extracellular matrix and the cytoskeleton. Second, heat‐stable components alter the cell surface phosphorylation. These changes are associated with an activation of the cells to produce hyaluronic acid, the most striking anabolic change obtained in treated cells.