Fibronectin fragmentation induced by dental plaque and Bacteroides gingivalis

Degradation of fibronectin (FN) by subgingival and supragingival plaque and Bacteroides gingivalis (Bg) was studied in vitro. The degradation of FN by both types of plaque was relatively rapid, continuous but incomplete. Some differences were found between supra- and subgingival samples. Supragingival plaque extracts produced several FN fragments of 110-180 kd during short incubations of 15-60 min. The predominant fragment after overnight incubation was a 110 kd polypeptide. With subgingival plaque extract a more extensive degradation of FN was noted. The main degradation product was a 120 kd fragment after overnight incubation. Several peptide fragments were released from fibronectin by Bg extracts. Their molecular size was different from those produced by trypsin, elastase or dental plaque. When cell extracts of Bg were fractionated by high performance liquid chromatography, three separate peaks of fibronectin degrading activity were obtained. Two of those peaks also contained trypsin-like enzyme activity. The degradation of fibronectin and the subsequent formation of biologically active peptides may have many effects in periodontal pockets. These may include modifying effects on plaque growth and wound healing.