Immunochemical detection of the proteoglycans decorin and biglycan in human gingival crevicular fluid from sites of advanced periodontitis.

This study characterized proteoglycan metabolites present in gingival crevicular fluid (GCF) collected from sites with clinical evidence of advanced periodontal disease. The metabolites were purified by anion-exchange chromatography from which a chondroitin sulphate rich fraction was identified by cellulose acetate electrophoresis. Sodium dodecylsulphate-polyacrylamide gel electrophoresis of this fraction revealed a broad silver-staining band with mol. wt 55-65 k and Western blotting suggested that this band was immunoreactive with CS-56, a monoclonal antibody for chondroitin sulphate. Digestion of the metabolite with chondroitinase ABC (protease-free) led to the loss of the silver-staining band. Dot-blot analysis identified components in this fraction that were immunoreactive for the monoclonal/polyclonal antibodies against the C-termino of decorin and biglycan. Amino acid analysis revealed the composition of the proteoglycan metabolite to be rich in glycine, serine and glutamic acid. Immunochemical and biochemical analyses were compared with those of proteoglycan purified from human alveolar bone. Changes in the amino acid composition were noted, suggesting the proteoglycan metabolite has undergone extensive modification and fragmentation to the protein core. The results suggest that the proteoglycan metabolite from GCF represented a degradation product originating from the active destruction of the alveolar bone. They provide further support for the proposal that the appearance of proteoglycan metabolites in GCF is a biomarker for active destruction of alveolar bone, the biochemical analysis of which provides important information on mechanisms involved in the pathology of periodontal diseases.