Relationship of GCF-gingipains and chronic periodontitis active breakdown

Background: Gingipains, including Arg-gingipain (Rgp) and Lys-gingipain (Kgp), are toxic proteases produced by Porphyromonas gingivalis, a putative periodontal pathogen. They are capable of degrading many host proteins, such as collagen fragment, IL-6, IL-8, etc. It is unknown if the levels of Rgp and Kgp in gingival crevicular fluid (GCF) are related to active progression of chronic periodontitis. Objectives: To observe the relationship between levels of Rgp and Kgp in GCF and the active progressing of chronic periodontitis. Methods: Untreated chronic periodontitis patients were selected from employees in an institute in Beijing urban area, aged from 22 to 64 years old. Fifty-three patients were examined at baseline, 6 months and 1year later. The attachment loss (AL) was measured at 6 sites per tooth in all teeth except third molars. GCF samples were collected from 53 active sites which displayed increase of AL 3 mm or more (ΔAL≥3mm) between two times of examination, and from 36 inactive sites from the same patients. Proteolytic activities of GCF-Rgp and GCF-Kgp were determined with Z-Phe-Arg-MCA and Z-His-Glu-Lys-MCA as the respective substrates. Results: The volume of GCF in active sites were not significantly different from that in inactive sites (97.11+/-46.41 units vs. 80.36+/-40.60 units, P>0.05). The levels of GCF-Rgp, GCF-Kgp activities and total activity of GCF-gingipain in active sites were significantly higher than that in inactive sites (Rgp: 334.3+/-350.8 units vs. 264.3+/-452.3 units, P<0.05; Kgp: 61.42+/-73.38 units vs. 40.19+/-83.27 units, P=0.01; Gingipain: 395.7+/-417.5 units vs. 306.3+/-526.1 units, P<0.05). GCF-Rgp activity levels were higher than that of GCF-Kgp in the same GCF sample. Conclusions: It is suggested that the Rgp, Kgp and gingipain in GCF are related to active progression of chronic periodontitis and might be a useful marker for periodontal disease progression.