Monitoring gene expression of rcpA from Aggregatibacter actinomycetemcomitans versus antimicrobial photodynamic therapy by relative quantitative real-time PCR

Abstract

Background: Aggregatibacter actinomycetemcomitans is an important pathogen that is frequently found in various infections, particularly aggressive periodontitis. In this study, we described the outcome of the expression level of A. actinomycetemcomitans virulence factor following treatment by antimicrobial photodynamic therapy (aPDT) with indocyanine green (ICG) as a photosensitizing agent.

Materials and methods: To determine the aPDT effect on the cell-surviving assay and expression ratio of the rcpA gene in A. actinomycetemcomitans by a colony-forming unit and relative quantitative (q) real-time PCR (qRT-PCR) assays, respectively, the proper dosing of sub-lethal aPDT was specified.

Results: The results of the current study showed that ICG-mediated aPDT, using 250-1000μg/mL, showed a significant reduction in A. actinomycetemcomitans growth when compared to the control group (P<0.05). Also, a sub-lethal dose of aPDT against A. actinomycetemcomitans was 125μg/mL ICG, with a 30s diode laser irradiation time at fluency of 15.6J/cm² that could reduce the expression of rcpA gene approximately 6-fold.

Discussion: aPDT with ICG could reduce the cell survival and the virulence agent of A. actinomycetemcomitans. Thus, use of the appropriate aPDT dosage can be used for the successful treatment of periodontitis in vivo.

Keywords: Aggregatibacter actinomycetemcomitans; Antimicrobial photodynamic therapy; Gene expression; Indocyanine green; Periodontitis; Virulence factor; qRT-PCR; rcpA.