Rapid detection of Lys-gingipain using fluorogenic peptide substrate for diagnosis of periodontitis

Abstract

Background/purpose: Early detection of periodontitis and its associated pathogens has become imperative in oral health. Porphyromonas gingivalis (P. gingivalis), a leading oral pathogen, is known to secrete Lys-gingipain (Kgp) enzyme. The aim of this study was to validate the detection of P. gingivalis in human saliva samples by measuring the fluorescence intensity generated by a Lys-specific peptide substrate after it is cleaved in the presence of Kgp. Materials and methods: To confirm the biological activity of the fluorogenic His-Glu-Lys containing peptide substrate which is specific to the Kgp, we compared the fluorescence intensity of the fluorogenic peptide substrate with saliva samples obtained from both healthy individuals (n = 31) and periodontitis patients (n = 30). Results: The results from the fluorogenic substrate were statistically compared with polymerase chain reaction (PCR) results of P. gingivalis quantification. Whereas the PCR test had an area under curve (AUC) value of 0.729, the normalized relative fluorescence unit (RFU) obtained from fluorogenic peptide samples had an AUC value of 0.756. Conclusion: We anticipate that the fluorogenic peptide substrate will assist in detecting early stages of periodontitis and ultimately prevent further complications. This fluorogenic peptide substrate can be used as a basic material for various types of biosensors.