Flossing between your teeth could one day help vaccinate you. This is according to a new scientific study that shows by targeting a uniquely permeable gum tissue called the junctional epithelium, this new method stimulates immunity at the point where many infections enter: the mouth, nose, and lungs.
The study, from North Carolina State University, involved using dental floss on mice to apply a flu vaccine triggered a robust immune response—better than existing oral approaches and comparable to nasal vaccines, but without the risks. The process even worked with mRNA and protein-based vaccines.
According to lead researcher Harvinder Singh Gill: “Mucosal surfaces are important, because they are a source of entry for pathogens, such as influenza and COVID. However, if a vaccine is given by injection, antibodies are primarily produced in the bloodstream throughout the body, and relatively few antibodies are produced on mucosal surfaces.
“But we know that when a vaccine is given via the mucosal surface, antibodies are stimulated not only in the bloodstream, but also on mucosal surfaces. This improves the body’s ability to prevent infection, because there is an additional line of antibody defence before a pathogen enters the body.”
This point is where the junctional epithelium matters, the tissue that lines the surface of our body parts, such as the lining of the lungs, stomach and intestines. Most epithelial tissues include robust barriers that are designed to keep pathogens from entering the blood stream. Yet the junctional epithelium is different.
The junctional epithelium is a thin layer of tissue located in the deepest part of the pocket between the tooth and the gum, and it lacks the barrier features found in other epithelial tissues. The lack of a barrier allows the junctional epithelium to release immune cells to fight bacteria – you find these immune cells in your saliva, as well as between your teeth and gums.
To determine the viability of delivering vaccines via the junctional epithelium, the researchers applied vaccine to unwaxed dental floss and then flossed the teeth of lab mice.
Specifically, the researchers compared antibody production in mice that received a peptide flu vaccine via flossing the junctional epithelium; via the nasal epithelium; or via placing vaccine on the mucosal tissue under the tongue. Applying vaccine via the junctional epithelium produces far superior antibody response on mucosal surfaces.
The researchers tested whether the junctional epithelium delivery method worked for three other prominent classes of vaccines: proteins, inactivated viruses and mRNA. In all three cases, the epithelial junction delivery technique produced robust antibody responses in the bloodstream and across mucosal surfaces.
The researchers also found that, at least in the animal model, it didn’t matter whether food and water were consumed immediately after flossing with the vaccine – the immune response was the same.
There are still many questions that need to be answered before the floss technique can be considered for clinical use. Nonetheless, the researchers think there could be significant advantages for medicine administration.
The study appears in the journal Nature Biomedical Engineering, titled “Floss-based vaccination targets the gingival sulcus for mucosal and systemic immunization.”
