Modification of forsythia detaching factor by gingival crevicular fluid in periodontitis.

Objectives: Forsythia detaching factor (FDF) is a virulence factor of Tannerella forsythia detected as a mixture of the 60-kDa form of FDF and the 28-kDa C-terminal fragment (FDFc). The objective of the present study was to clarify the proteolytic activity of gingival crevicular fluid (GCF) from patients with periodontitis and healthy subjects using recombinant FDF (rFDF) as substrate.

Design: Eleven patients with periodontitis and 6 healthy subjects were recruited. Modification of rFDF and subsequent production of rFDFc by proteolytic activity of GCF was determined by Western blotting. Proteolytic activity of GCF was evaluated using an Ac-Arg-Ala-Lys-p-nitroaniline substrate. Correlation analysis between two different sets of variables was performed. Variables used in this analysis were proteolytic activity, clinical parameters, relative band density of rFDFc and those of rFDF.

Results: Proteolytic activity in GCF was significantly higher in patients with periodontitis than in healthy subjects. Production of rFDFc was determined by treatment of rFDF with GCF from patients with periodontitis and with GCF from healthy subjects. Correlations between clinical parameters and proteolytic activity in GCF were significantly positive. On the other hand, correlations between relative band density of rFDFc or rFDF on Western blot and cleaving activity or clinical parameters were significantly negative.

Conclusion: The detected extend of GCF-activity generating rFDFc from rFDF and/or even further degrading rFDF correlates with severity of periodontitis.