Dec 31, 2025
3 min read
High levels of the periodontal bacterium Fusobacterium nucleatum may be associated with severe disability in people with multiple sclerosis.
Summary: High levels of the periodontal bacterium Fusobacterium nucleatum may be associated with significant disability in patients with multiple sclerosis.The researchers analyzed samples of the tongue coating and found that MS patients with the highest levels of this bacteria scored worse on standard disability scales.
The effect was seen only in MS and was not seen in the other two destructive diseases. This suggests a possible mechanism of MS-specific oral and brain damage.The findings raise the possibility that poor oral health and chronic gum inflammation may contribute to the progression of neuropathy.
- MS disability link: MS patients with higher levels of F. nucleatum showed higher levels of disability.
- Oral-brain axis: no association was found with NMOSD or MOGAD suggesting an MS-specific significance.
- Inflammatory bridge: Viruses can act as a "bridge" between the inflammation of the oral cavity and neurological complications.
Source: Hiroshima University
Increasing evidence suggests that severe gum disease, periodontitis, may contribute to centrocardial disease.sclerlation. Ober, its role in multiple sclerosis. Ober, its role in multiple sclerosis. Ober, its role in multiple eclososis, chronic AutoSemune disease of the central nervous system, is unclear.
A research team has conducted a study with findings showing a possible association between relatives of Fusobacterium nucleatum (F. nucleatum), oral bacteria and disease severity in multiple sclerosis (MS) patients.
Their study is published in the Scientif Story Books in November 3, 2025.
Multiple sclerosis is a major inflammatory demyelinating disease that targets the myelin sheath, the protective layer around nerve cells.The exact cause of multiple sclerosis is still unknown, but possible factors include viral infections, smoking, vitamin deficiencies, and genetic predisposition.
The prevalence of multiple sclerosis has continued to increase in Japan since the 1980s.This rapid increase may be influenced by environmental changes.Scientists have studied changes in the gut microbiome associated with this.
Attention has recently expanded to include the potential role of the gut microbiota as well as the oral microbiota in central nervous system diseases.
Periodontal disease is a chronic bacterial infection that causes persistent inflammation in the periodontal tissue.It eventually causes loss of connective tissue and lung bone, and tooth loss.
Periodontal disease is common, with a global prevalence of 40% to 60%. Researchers know that it increases the risk of diseases such as atherosclerosis, diabetes and rheumatoid arthritis.
Exploring the possibility of a 'mouth-brain axis' in MS
In their study, the research team measured the number of periodontal bacteria in tongue swabs collected from patients with serious inflammatory diseases such as multiple sclerosis, neuromyelitis optic spectrum disorder (NMOSD), or myelin oligodendrocyte glycoprotein antibody disease (MOGAD).
High relative abundance is determined by whether the proportion of a given bacterial species in their oral samples was in the top 25% of all patients in the 75% to be examined (high).
They investigated the relationship between periodontal bacterial load and clinical conditions and the differences between different types of bacteria.
The team wanted to determine whether a specific period of focus in the oral cavity was associated with clinical severity in multiple sclerosis.
“While the gut microbiome has been investigated in multiple sclerosis, the potential involvement of the oral microbiome remains largely unexplored.
"Because the oral cavity is a major source of chronic inflammation and a potentially modifiable factor, it is important to clarify its relationship with the severity of multiple sclerosis in order to understand the disease process and develop new preventive strategies," said Masahiro Nakamori, associate professor and assistant professor at Hiroshima University Hospital.
Their findings show that multiple sclerosis patients with a higher relative abundance of the periodontal pathogen Fusobacterium nucleatum in tongue coating samples showed significantly greater disability, as measured by the 10-point Expanded Disability Status Scale (EDSS).
"This association is not seen in neuromyelitis optica spectrum disorders or myelin oligodendrocyte glycoprotein antibody-related diseases, and may suggest an 'oral-brain axis' specific to multiple sclerosis, where oral inflammation may influence the severity of neuroinflammatory diseases," said Hiroyuki Naito, assistant professor at Hiroshima University Hospital.
"Bridge bacteria"?
To rule out alternative explanations, the team tested a number of clinical factors in addition to the bacteria.Even after adjusting for age, disease duration, number of attacks and multiple sclerosis subtype, high levels of Fusobacterium nucleatum were associated with approximately tenfold higher odds of severe disability in multiple sclerosis patients.
The team noted that nearly two-thirds (61.5%) of MS patients with high levels of Fusobacterium nucleatum fell into the moderate-to-severe disability range (EDSS 4 or more), compared to about a fifth (18.6%) of those with milder disease (EDSS below 4).
There is no companies found in patients with nuromeetitis Optical Optical Optimal or diseases associated with the oligindrocyte myecopidies.The public Sclerosis with Fusiobactorum Nugleatum and at least one Parriodonal diseases.
"Fusobacteria nucleatum may act as a hidden 'bridge bacteria' - not only connecting bacterial communities in dental biofilms but also potentially linking stomatitis to neurological impairment," said Nakamori.
In the future, the team hopes to conduct larger, multicenter studies to confirm the link between oral bacteria and the severity of multiple sclerosis.They plan to conduct mechanistic analyses, including cytokine profiling and metagenomic sequencing, to understand how oral pathogens influence the immunopathology of multiple sclerosis.
Also, there is a need to evaluate whether dental activities - such as periodic treatment or daily oral hygiene - can change disease activity or the development of disability in multiple sclerosis.
"Ultimately, we aim to elucidate how the inflammatory mouth-gut-brain axis contributes to the pathophysiology of MS and investigate whether oral health can serve as a new target for disease modification," Naito said.
The research team also includes Megumi Toko, Tomoko Muguruma, Hidetada Yamada, Takamichi Sugimoto, Yu Yamazaki, Kazuhide Ochi, and Hirofumi Maruyama from the Department of Health and Sensory Neurosciences at Hiroshima University and Hiromi Nishi and Hiroyuki Kawaguchi from the Department of General Dentistry at Kawaguchi University.
Key questions answered:
A: Yes.High levels of Fusobacterium nucleatum have been associated with severe disability in MS patients.
A: No. The association is not caused by neuromyelitis optica spectrum disorder or MOG antibody deficiency, which indicates a unique MS pathway.
A: Potentially.Researchers hope to learn whether periodontal treatment can reduce inflammation and influence the progression of MS.
- This article was edited by a Neuroscience News editor.
- Complete news.
- Additional context added by our staff.
For this multiple sclerosis research story
Writer: Mikas Matsuzawa
Source: Hiroshima University
CT: Mikas Matsuzawa - Hiroshima Sea Urushi ty
Image: Image credited to Neuroscience News.
Basic Research: Open Access.
"The periodontal pathogen Fusobacterium nucleatum is associated with disease severity in multiple sclerosis" by Masahiro Nakamori et al.Scientific Reports
The pathogen Fusobacterium nucleatum is associated with disease severity in multiple sclerosis.
Growing evidence suggests that periodontitis may contribute to central nervous system disorders through chronic inflammation, but its role in multiple sclerosis (MS) remains unclear.
This exploratory, cross-sectional study investigated the relationship between the relative abundance of periodontal pathogens in the oral cavity and clinical features of MS.
We included 98 patients with multiple sclerosis, neuromyelitis optica, or myelin oligodendrocyte glycoprotein antibody-related disease.
Lingual coating samples were analyzed by quantitative polymerase chain reaction targeting four periodontal types.
High relative abundance was defined as abundance exceeding the third quartile in proportion to total bacterial abundance.The association between clinical features and MIR features was evaluated.
Among 56 MS patients, only a high relative abundance of Fusobacterium nucleatum was associated with disease severity, as measured by the Expand Disability Status Scale (EDSS) (p=0.009).
No associations were observed with the other three pathogens or in the non-MS group.In multivariate analysis, the relative abundance of Fusobacterium nucleatum was independently associated with EDSS score.
These results suggest a possible association between the relative abundance of Fusobacterium nucleatum in the oral cavity and MS severity.
