Some recent studies have suggested that there is a link between severe gum disease or periodontitis, and some disorders that affect the central nervous system, because periodontitis can lead to chronic inflammation, which can cause other problems. Now, scientists have found a link between the severity of multiple sclerosis (MS) cases, and a patient’s levels of a mouth microbe known as Fusobacterium nucleatum (F. nucleatum). The findings have been published in Scientific Reports.
In MS, the protective sheath that insulates many neurons, known as myelin, is erroneously attacked by the immune system; so it begins to degrade, leading to a variety of other health problems. MS can vary in severity significantly from one patient to another. The cause or causes of MS are still unknown, and many factors like viral infections (particularly Epstein-Barr virus infections), genetics, vitamin deficiencies, and other influences may be involved in raising the risk of MS.
In this study, the researchers assessed the levels of a common microbe found in the human mouth, called F. nucleatum as well as other mouth microbes, in MS patients. They also did this assessment for patients with other demyelinating disorders such as neuromyelitis optica spectrum disorder (NMOSD), and myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD).
This showed that MS patients with moderate to severe disabilities were more likely to have higher relative levels of F. nucleatum. This association was not seen in NMOSD or MOGAD patients.
This could suggest a, “multiple sclerosis-specific oral–brain axis through which oral inflammation may influence neuroinflammatory disease severity," suggested first study author Hiroyuki Naito, an assistant professor at Hiroshima University Hospital.
Even when the scientists made statistical adjustments for age; MS subtype; and time since diagnosis; unusually high levels of F. nucleatum were linked to a roughly tenfold increase of severe MS disability. MS patients with F. nucleatum levels of lower relative abundance tended to have milder MS cases.
"Fusobacterium nucleatum may act as a hidden 'bridge bacterium,' not only bridging bacterial communities in dental biofilms, but also potentially linking oral inflammation to neurological disability," said corresponding study author Masahiro Nakamori, an associate professor and lecturer at Hiroshima University Hospital.
Now these findings will have to be validated in larger cohorts of patients. Research will also have to be conducted to understand the nature of the link between the high F. nucleatum levels, and whether the bacterium is contributing to the development of MS. If so, it could present a great opportunity to prevent or treat the disorder.
"Ultimately, we aim to clarify how the oral–gut–brain inflammatory axis contributes to multiple sclerosis pathophysiology and to explore whether oral health could serve as a novel target for disease modification," said Naito.
Sources: Hiroshima University, Scientific Reports