Light-activated therapy may treat gingivitis without disrupting the beneficial bacteria that help maintain oral health.
Treating gingivitis presents a difficult balance: harmful bacteria must be removed without eliminating beneficial microbes that help maintain oral health.
Researchers in Nagoya University In Japan, they have developed an experimental approach designed to do just that by selectively eliminating key disease-causing bacteria, while leaving a significant portion of the surrounding microbial community intact. The results were published in Journal of Translational Medicine.
A healthy mouth depends on a diverse and balanced population of microorganisms. single bacteria, Porphyromonas gingivalis (P. gingivalis), serves as the primary pathogen that can promote inflammation and disturb microbial homeostasis. Over time, the resulting damage can affect the bones supporting the teeth and contribute to tooth loss.
“Current treatments for gingivitis, including antibiotics and antimicrobial photodynamic therapy (aPDT), eliminate both pathogenic and beneficial oral bacteria,” said Kazuhide Sato, one of the authors and a lecturer at Nagoya University. “These approaches often disrupt the entire oral microbial ecosystem and can also release lipopolysaccharide (LPS), an endotoxin that may exacerbate inflammation.”
Cancer technology allows the targeted bacteria to be removed
Researchers at Nagoya University Graduate School of Medicine have adapted near-infrared photoimmunotherapy, an approach originally created to treat cancer. This technology relies on an antibody-dye complex that binds to the chosen target and becomes active when illuminated with near-infrared light.
The group included first author Hiroshi Maruyama, Professor Hideharu Hibe, and corresponding authors Sato and Kiyoshi Sakai.
To treat the gums, the researchers used IgY, an antibody collected from the egg yolk of immunized chickens P. gingivalis. IgY can be manufactured in large quantities and inexpensively, making it useful for clinical applications.
They named this therapeutic approach near-infrared antibacterial photo-targeting (NIR-PAT²). To determine if it can be removed P. gingivalis Without disturbing the oral environment extensively, they tested it in human cell cultures and mouse models and compared its effects with conventional treatments.
The treatment spares healthy cells and microbes
In cell culture experiments, the antibody-dye complex is selectively bound P. gingivalis While leaving other bacteria and healthy human gum cells unaffected. Once activated with near-infrared light, the dye focuses on the target bacteria, damaging their outer membranes and eliminating them.
Microscopic examination revealed small holes in the treated membranes P. gingivalisAlthough bacteria have largely retained their general physical structure. In comparison, aPDT caused complete destruction of bacterial cells.
Tests also showed that NIR-PAT² did not damage human gum cells. In contrast, aPDT caused cell injury and slowed healing.
The distinction persisted in mice with gingivitis. Animals that received the targeted treatment showed significantly less loss of alveolar bone, which affects the bone supporting teeth. Analysis of their saliva also indicated that the treatment eliminated pathogens P. gingivalis While maintaining the useful Streptococcus Population.
Standard antibiotics and aPDT produced a less selective effect, eliminating both beneficial and harmful bacteria and further disturbing the oral microbial community.
“The results showed that, unlike antibiotics or standard phototherapy, this approach selectively removes the primary pathogenic species while preserving the remainder of the oral bacterial community,” Sato said.
AI can identify additional bacterial targets
However, gingivitis is not caused by a single bacterial species, so it must be eliminated P. gingivalis It alone may not provide the complete solution. The researchers plan to use artificial intelligence (AI) to examine publicly available oral microbiome data, identify other important bacteria, and elucidate how different species interact with each other.
These analyzes could guide the development of more precisely targeted therapies that address additional microbial contributors to periodontal disease.
Gingivitis has also been linked to conditions including rheumatoid arthritis and diabetes. The researchers believe their AI-based approach could ultimately help identify patients who are most likely to benefit from specific targeted therapies.
Reference: “Near-infrared photosynthetic bacterial flora modulation technology achieved control of gingivitis: modulation of disease-associated dysbiosis in oral microbiota using near-infrared antibacterial targeted therapy (NIR-PAT2)” by Hiroshi Maruyama, Kazuhide Sato, Kiyoshi Sakai, Hirotoshi Yasui, Ryo Okada, Li Xinheng, Koji Umeda, Shufikur Rahman, Van Sa Nguyen and Hideharu Hebei, June 2, 2026, Journal of Translational Medicine.
doi: 10.1186/s12967-026-08336-2
Funding: JSPS KAKENHI grant 19K1919, 21K10067, 18K15923, 21K07217,25K03451, 25K22916. Program for Developing the Next Generation of Researchers (Japan Science and Technology Agency). Research grant from the Institute for Therapeutic Serum Chemical Research. Suzuki Kenzo Scholarship. Terumo Science Foundation. Hori Foundation for Science and Arts. CREST (JPMJCR19H2, JST). Forest-Sohatsu (JPMJFR2017, JST). AMED Seeds A (26ym0126807j0005, A-226, AMED). GAP-FUND Tongali (JST).
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