Host modulation of adherence of oral bacteria: the effect of human neutrophil myeloperoxidase on the attachment of Actinomyces viscosus and Actinomyces naeslundii to saliva-coated hydroxyapatite.

Abstract

Host neutrophils, by virtue of their ability to secrete lysosomal enzymes and reduced oxygen metabolites, may play a fundamental role in altering the composition and pathogenic potential of dental plaque by modulating bacterial adherence. The adherence of Actinomyces viscosus and Actinomyces naeslundii to salivacoated surfaces is known to be saturable and mediated by proteinaceous fimbriae. In this study, we examined the abhesive effects of the human neutrophil enzyme, myeloperoxidase (MPO), on the adherence of A. viscosus T14V and A. naeslundii ATCC 12104 to saliva‐coated hydroxyapatite (SHA) beads. Microorganisms were treated with MPO in the presence of hydrogen peroxide (H2O2) and physiologic concentrations of chloride (forming the MPO‐H2O2‐Cl‐ system) and incubated with SHA beads. Treatment of cells with the isolated MPO‐H2O2‐C1‐ system reduced the percentage of cells that bound. This abhesive effect was inhibited by sodium azide, exogenous catalase, taurine, and potassium thiocyanate. The three major chromatographic forms of MPO (I, II, and III) were effective in blocking adherence of A. viscosus. We conclude that the MPO‐H2O2‐Cl‐ system can interfere with the adherence of A. viscosus and A. naeslundii, and therefore may be important in modulating the microbiai colonization of oral surfaces.