Targeted bacteria-killer shows promise in tooth-decay fight

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Targeted bacteria-killer shows promise in tooth-decay fight

Finding proves that human microbiome can be re-engineered to prevent disease, researcher says

A new treatment that can kill the bacteria responsible for tooth decay without harming the mouth’s beneficial bacteria has moved one step closer to reality.

Researchers at the University of Washington and the University of California-Los Angeles showed how a specifically targeted antimicrobial peptide, or STAMP, eradicates harmful acid-producing Streptococcus mutans bacteria without killing benign bacteria. 

The study is published in the June issue of the Proceedings of the National Academy of Sciences

UCLA School of Dentistry | Wenyuan Shi
(Click to enlarge.) A Streptococcus mutans bacterium is shown before (above) and after treatment with the C16G2 specifically targeted antimicrobial peptide.
two pictures of a Streptococcus mutans bacterium, before and after treatment

The finding is a critical advance because the vast majority of bacterial cells in the human mouth are not harmful. However, most common broad-spectrum antibiotics and conventional mouthwashes indiscriminately kill both beneficial and harmful bacteria, and their effects last only about 12 hours.

As a result, no effective treatment exists for bacteria-induced tooth decay. While fluoride has been an effective weapon against tooth decay, it works by strengthening tooth enamel rather than attacking Streptococcus mutans, which converts sucrose to lactic acid that attacks the teeth. 

Jeffrey McLean is an acting associate professor of periodontics in the UW School of Dentistry.
picture of Jeffrey McLean

The STAMP approach, on the other hand, restructures the mouth’s microbiome, or microorganism population, to produce an environment that supports better oral health. Moreover, the approach could be used against other microbiome-related diseases, meaning it could have an impact far beyond dentistry, said Wenyuan Shi, the study’s lead author and chair of oral biology at the UCLA School of Dentistry.

A growing number of studies have linked changes in the composition of the human microbiome to numerous disease states. When bacteria cause diseases, it is typically because they grow beyond their normal population size or niche (which can occur when the body’s immune system is compromised) or because microbes enter parts of the body that are normally sterile, such as the blood, lower respiratory tract or abdominal cavity.

Study co-author Jeffrey McLean of the UW School of Dentistry said, “Targeted killing of individual species that can trigger or significantly advance disease within our delicately poised microbiome is crucial to keep the entire system in balance. This study also represents a major step toward understanding how that balance may be shifted toward a healthy state after removing a single disruptive member of the human microbiome community.” 

C16G2, the specific peptide involved in this study, is now delivered via a gel tray, which the researchers chose as a more promising vehicle than mouthwash.

It is being developed for use in preventing tooth decay and cavities under an investigational drug application with the U.S. Food and Drug Administration by Los Angeles-based C3 Jian, a company Shi founded around patent rights he developed at UCLA. It is currently in Phase 2 clinical trials.