Researchers at Nagoya University in Japan have developed an experimental treatment that attacks a major driver of gum disease while preserving the beneficial bacteria that support a healthy oral microbiome. The technology, known as near-infrared photo-antibacterial targeting therapy, or NIR-PAT², combines a pathogen-specific antibody with a light-sensitive dye. In laboratory and mouse studies, the approach selectively targeted Porphyromonas gingivalis, a bacterium strongly associated with periodontitis, and destroyed it when activated by near-infrared light.
Periodontitis is a chronic inflammatory disease in which microbial communities accumulate around the gums and progressively damage the tissues and bone that anchor teeth. Although many bacteria can contribute to the condition, P. gingivalis is considered a keystone pathogen because it can disrupt the wider microbial ecosystem even when present in relatively small numbers. This disruption, known as dysbiosis, can intensify inflammation, weaken the periodontal tissues, and ultimately lead to tooth loss.
Existing treatments can reduce the bacterial burden, but they are not always selective. Antibiotics may affect both disease-associated and beneficial bacteria, while conventional antimicrobial photodynamic therapy, or aPDT, uses light-activated compounds that can damage a broad range of microorganisms and host cells. The destruction of bacterial cells can also release lipopolysaccharide, or LPS, a component of the outer membrane of Gram-negative bacteria that can stimulate inflammatory responses. The Nagoya team designed NIR-PAT² to address these limitations by directing the light-sensitive agent specifically to P. gingivalis.
The treatment adapts a form of near-infrared photoimmunotherapy originally developed for cancer. In this strategy, an antibody recognizes a molecular target on a cell, while an attached dye responds to near-infrared illumination. For the periodontal application, the researchers used immunoglobulin Y, or IgY, an antibody obtained from the egg yolks of hens immunized against P. gingivalis. IgY can be produced in large quantities and at comparatively low cost, potentially making it more practical for biological targeting than some conventional antibody platforms.
When the antibody-dye compound was added to cell cultures containing different bacterial species, it preferentially attached to P. gingivalis. The researchers then exposed the cultures to near-infrared light, which activated the dye bound to the bacterial surface. Rather than broadly irradiating the microbial community, the treatment concentrated its photochemical effect where the antibody had accumulated. The resulting damage disrupted the outer membrane of the pathogen and eliminated it while leaving unrelated bacteria largely unaffected.
Microscopic observations helped distinguish NIR-PAT² from conventional photodynamic treatment. After exposure to the targeted therapy, P. gingivalis cells developed localized holes in their outer membranes but generally retained their overall shape. This pattern is consistent with a membrane-disrupting mechanism in which the activated dye generates short-lived reactive species near the bacterial surface. By contrast, aPDT caused more extensive destruction of bacterial cells and also injured cultured human gum cells. The NIR-PAT² treatment did not show comparable toxicity toward the human cells under the experimental conditions.
The researchers next tested the therapy in mouse models of periodontitis. Animals receiving NIR-PAT² showed significantly less loss of alveolar bone, the specialized bone that surrounds and supports the teeth. Analysis of saliva indicated that the intervention reduced detectable P. gingivalis while preserving populations of beneficial Streptococcus bacteria. Mice treated with standard antibiotics or aPDT experienced broader changes in their oral microbial communities, including reductions in bacteria considered part of a healthier oral environment.
“These results demonstrated that, unlike antibiotics or standard light therapy, this approach selectively removes the primary pathogenic species while preserving the remainder of the oral bacterial community,” said Kazuhide Sato, a lecturer at Nagoya University and one of the study’s corresponding authors. The researchers emphasize that preserving microbial diversity may be important because the oral microbiome is not simply a collection of harmful organisms to be eliminated. Its members interact with one another and with the host immune system, and indiscriminate treatment can potentially create new imbalances.
The findings remain an early proof of concept rather than evidence of an available human treatment. Periodontitis is driven by complex communities containing multiple bacterial species, and eliminating P. gingivalis alone may not fully resolve disease in every patient. The team plans to use artificial intelligence to analyze publicly available oral microbiome data, identify additional organisms associated with disease, and map interactions among them. Because periodontitis is also linked with systemic conditions including diabetes and rheumatoid arthritis, the researchers hope such analyses could eventually help identify patients most likely to benefit from highly targeted therapies. Before clinical use, NIR-PAT² will require further studies addressing safety, dosing, light delivery, antibody persistence, immune reactions, and effectiveness in human periodontal tissues.
Subject of Research: Animals
Article Title: Near infrared photo-bacterialflora modulation technology realized controlling periodontitis: Modulation of disease-associated dysbiosis in oral microbiota using near infrared photo-antibacterial targeting therapy (NIR-PAT²)
Web References: https://link.springer.com/article/10.1186/s12967-026-08336-2
References: Maruyama H, Sato K, Sakai K, Yasui H, Okada R, Li X, Umeda K, Rahman S, Nguyen VS, Hibi H. “Near infrared photo-bacterialflora modulation technology realized controlling periodontitis: Modulation of disease-associated dysbiosis in oral microbiota using near infrared photo-antibacterial targeting therapy (NIR-PAT²).” Journal of Translational Medicine. 2026. DOI: 10.1186/s12967-026-08336-2
Image Credits: Kazuhide Sato et al., Journal of Translational Medicine, 2026. Licensed under CC BY-NC-ND 4.0.
Keywords: periodontitis, oral microbiome, Porphyromonas gingivalis, near-infrared photoimmunotherapy, NIR-PAT², IgY antibody, antimicrobial photodynamic therapy, periodontal bone loss, targeted antibacterial treatment, dysbiosis
