Researchers at the University of Pennsylvania School of Dental Medicine (Penn Dental) continue to build on existing knowledge of how the fungus Candida albicans takes advantage of the enzyme GtfB, produced by the Streptococcus mutans bacteria, to form oral biofilm that contributes to early childhood caries. In their most recent study, researchers were able to pinpoint the surface molecules on the fungus that interact with the bacteria and found that blocking this interaction impaired C. albicans’ ability to form biofilm with S. mutans on tooth surfaces.
Published in PLOS Pathogens, the paper, “Candida albicans Mannans Mediate Streptococcus mutans Exoenzyme GtfB Binding to Modulate Cross- Kingdom Biofilm Development In Vivo,” examined binding strength measurements between various mutant C. albicans strains and GtfB. The enzyme was reported to bind more weakly to mutants that lacked components of the mannan layer (molecules that make up the outer portion of the C. albicans cell wall) than wild-type C. albicans. The team next looked at the abilities of the mutant C. albicans to form biofilms with S. mutans in a laboratory assay. The mutants that had impaired binding with GtfB were mostly unable to form biofilms with S. mutans, resulting in fewer C. albicans cells and reduced production of glucans molecules.
To ensure their findings translated to in vivo, researchers examined biofilm formation in a rodent model. While a biofilm formation was abundant if the wild-type fungus was used, it was substantially reduced in subjects infected with the mutant strain. Defective biofilms completely lacked viable C. albicans cells, and S. mutans were reduced by more than fivefold, according to the authors.
“Instead of just targeting bacteria to treat early childhood caries, we may also want to target the fungi,” notes Hyun (Michel) Koo, DDS, MS, PhD, senior author and a professor in the Department of Orthodontics and Divisions of Pediatric Dentistry and Community Oral Health at Penn Dental. “Our data provide hints that you might be able to target the enzyme or cell wall of the fungi to disrupt biofilm formation.” These findings may lead to a new direction in the treatment of early childhood caries.
From Decisions in Dentistry. August 2017;3(8):10.