title: Cranberry Flavonoids Modulate Cariogenic Properties of Mixed-Species Biofilm through Exopolysaccharides-Matrix Disruption.
abstract: The exopolysaccharides (EPS) produced by Streptococcus mutans-derived glucosyltransferases (Gtfs) are essential virulence factors associated with the initiation of cariogenic biofilms. EPS forms the core of the biofilm matrix-scaffold, providing mechanical stability while facilitating the creation of localized acidic microenvironments. Cranberry flavonoids, such as A-type proanthocyanidins (PACs) and myricetin, have been shown to inhibit the activity of Gtfs and EPS-mediated bacterial adhesion without killing the organisms. Here, we investigated whether a combination of cranberry flavonoids disrupts EPS accumulation and S. mutans survival using a mixed-species biofilm model under cariogenic conditions. We also assessed the impact of cranberry flavonoids on mechanical stability and the in situ pH at the biofilm-apatite interface. Topical application of an optimized combination of PACs oligomers (100-300 μM) with myricetin (2 mM) twice daily was used to simulate treatment regimen experienced clinically. Treatments with cranberry flavonoids effectively reduced the insoluble EPS content (>80% reduction vs. vehicle-control; p<0.001), while hindering S. mutans outgrowth within mixed-species biofilms. As a result, the 3D architecture of cranberry-treated biofilms was severely compromised, showing a defective EPS-matrix and failure to develop microcolonies on the saliva-coated hydroxyapatite (sHA) surface. Furthermore, topical applications of cranberry flavonoids significantly weaken the mechanical stability of the biofilms; nearly 90% of the biofilm was removed from sHA surface after exposure to a shear stress of 0.449 N/m2 (vs. 36% removal in vehicle-treated biofilms). Importantly, in situ pH measurements in cranberry-treated biofilms showed significantly higher pH values (5.2 ± 0.1) at the biofilm-apatite interface vs. vehicle-treated biofilms (4.6 ± 0.1). Altogether, the data provide important insights on how cranberry flavonoids treatments modulate virulence properties by disrupting the biochemical and ecological changes associated with cariogenic biofilm development, which could lead to new alternative or adjunctive antibiofilm/anticaries chemotherapeutic formulations.
authors.affiliation: Biofilm Research Labs, Department of Orthodontics and Divisions of Pediatric Dentistry & Community Oral Health, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America.
authors.forename: Dongyeop
authors.initials: D
authors.lastname: Kim
authors.affiliation: Biofilm Research Labs, Department of Orthodontics and Divisions of Pediatric Dentistry & Community Oral Health, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America.
authors.forename: Geelsu
authors.initials: G
authors.lastname: Hwang
authors.affiliation: Biofilm Research Labs, Department of Orthodontics and Divisions of Pediatric Dentistry & Community Oral Health, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America.
authors.forename: Yuan
authors.initials: Y
authors.lastname: Liu
authors.affiliation: Department of Plant Biology and Plant Pathology, Rutgers University, New Brunswick, New Jersey, United States of America.
authors.forename: Yifei
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Department of Plant Biology and Plant Pathology, Rutgers University, New Brunswick, New Jersey, United States of America.
authors.forename: Ajay P
authors.initials: AP
authors.lastname: Singh
authors.affiliation: Department of Plant Biology and Plant Pathology, Rutgers University, New Brunswick, New Jersey, United States of America.|Philip E. Marucci Center for Blueberry and Cranberry Research and Extension, Rutgers University, Chatsworth, New Jersey, United States of America.
authors.forename: Nicholi
authors.initials: N
authors.lastname: Vorsa
authors.affiliation: Biofilm Research Labs, Department of Orthodontics and Divisions of Pediatric Dentistry & Community Oral Health, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America.
authors.forename: Hyun
authors.initials: H
authors.lastname: Koo
mesh_terms: D001031:Apatites / Q000378:metabolism; D018441:Biofilms / Q000187:drug effects* / Q000254:growth & development*; D001696:Biomechanical Phenomena / Q000187:drug effects; D005419:Flavonoids / Q000494:pharmacology*; D011135:Polysaccharides, Bacterial / Q000378:metabolism*; D013295:Streptococcus mutans / Q000187:drug effects / Q000378:metabolism / Q000502:physiology; D029799:Vaccinium macrocarpon / Q000737:chemistry*
chemical_list: D001031:Apatites; D005419:Flavonoids; D011135:Polysaccharides, Bacterial