Abstract
Aggregatibacter actinomycetemcomitans is an etiological agent that is frequently found in both chronic and aggressive periodontitis as well as peri-implantitis. In this study we evaluated the effects of antimicrobial photodynamic therapy (aPDT) as an alternative treatment modality by nano-chitosan encapsulated indocyanine green (CNPs/ICG) as a photosensitizer on the virulence features of cell-surviving aPDT against A. actinomycetemcomitans. Cell cytotoxicity effect of CNPs/ICG was evaluated on primary human gingival fibroblast cells. A. actinomycetemcomitans ATCC 33384 photosensitized with CNPs/ICG were irradiated with diode laser at wavelength of 810 nm for 1 min, following bacterial viability measurements. The biofilm formation ability, metabolic activity and antimicrobial susceptibility profiles were assessed for cell-surviving aPDT. The effect of aPDT on the expression of virulent gene (fieF), encoding Ferrous-iron efflux pump, was evaluated by quantitative real-time PCR. CNPs/ICG-aPDT resulted in the significant reduction of cell viability (91%), the biofilm formation capacity (53%), and metabolic activity (48%) of A. actinomycetemcomitans when compared to the control group (P < 0.05); As well as, fieF gene expression was downregulated (14.8-fold) after the strains were treated with aPDT. The virulence of A. actinomycetemcomitans strain is reduced in cells surviving aPDT with CNPs/ICG, and this may have potential implications of aPDT for the treatment of A. actinomycetemcomitans infections in periodontitis and peri-implantitis in vivo.
Highlights
The periodontal pathogen Aggregatibacter actinomycetemcomitans is frequently found in various infections, aggressive periodontitis and peri-implantitis [1]
When HuGu cells were subjected to chitosan nanoparticles (CNPs)/indocyanine green (ICG), no changes were seen in the cell morphology (Figure 2b)
The present study focused on the application of the developed CNPs/ICG in photo-elimination of A. actinomycetemcomitans as a major periodontal pathogen
Summary
The periodontal pathogen Aggregatibacter actinomycetemcomitans is frequently found in various infections, aggressive periodontitis and peri-implantitis [1]. A. actinomycetemcomitans possesses a numerous virulence factors that reinforce its survival in the oral cavity and are associated with colonization, biofilm formation, and invasion of the host tissue [2]. Antimicrobial photodynamic therapy (aPDT) is currently used as a potential alternative strategy for considerably removal of microorganisms from the oral cavity [4]. Various types of photosensitizers have been recently developed, among which indocyanine green (ICG) as an anionic photosensitizer has a higher in vitro efficacy against oral microorganisms [6]. Despite ICG potential therapeutic effects, the major disadvantage of ICG in aPDT is limited due to its instability in aqueous solutions that has been overcome by encapsulation of ICG molecules in nano-sized carriers [7]
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