Makeup of bacteria in the mouth is altered in MS, new study finds
Research could lead to new diagnostic biomarkers, therapeutic interventions
People with multiple sclerosis (MS) have altered levels of bacteria in their mouths, with reduced levels of normal healthy bacteria and higher levels of bacteria that can cause disease, a new study reports.
“Your mouth may reveal more about your overall health than you think,” Ashutosh Mangalam, PhD, senior author of the study at the University of Iowa, said in a university news story. “Our study shows that people with MS have measurable differences in the bacteria and metabolites found in their saliva.”
The findings could pave the way for the development of new diagnostic biomarkers and therapeutic interventions for MS, researchers said in the study, “Multiple sclerosis patients exhibit oral dysbiosis with decreased early colonizers and lower hypotaurine level,” which was published in npj Biofilms and Microbes.
Changes in mouth bacteria linked with several neurodegenerative diseases
The human body is home to billions of bacteria and other microscopic organisms, collectively known as the microbiome. These bacteria and organisms play critical roles in health and disease.
The largest part of the microbiome is located in the gut, and several studies have shown that the gut microbiome is dysregulated in MS. The second most diverse microbiome is the oral microbiome, and changes in mouth bacteria have been linked with several neurodegenerative diseases — but there hasn’t been much investigation into how this is affected in MS.
“While the gut microbiome has long been linked to MS, the oral microbiome, our mouth’s rich microbial ecosystem, has received far less attention, even though it’s the second most diverse microbiome in the human body and has been linked with other neurological diseases, like Alzheimer’s disease, and inflammatory diseases, like rheumatoid arthritis,” Mangalam said.
To learn more, the researchers analyzed saliva samples from 50 people with relapsing-remitting MS, the most common form of MS, and 50 healthy people, who were used as controls.
This isn’t just about losing a few good bacteria; it suggests a there is a breakdown of the oral ecosystem in people with MS.
Results showed several notable changes in the oral microbiome among MS patients. Specifically, patients had decreased levels of certain bacteria, including Streptococcus and Actinomyces species, that are normally key parts of a healthy oral microbiome.
At the same time, they had increased levels of bacteria that can cause dental and gum disease, such as Fusobacterium nucleatum, Porphyromonas gingivalis, and several Prevotella species.
“This isn’t just about losing a few good bacteria; it suggests a there is a breakdown of the oral ecosystem in people with MS,” Mangalam said.
Several metabolites significantly different in patients compared with controls
In addition to looking at the bacteria themselves, the researchers also analyzed bacterial metabolites, or the molecules that are produced as part of the bacteria’s metabolism. Several metabolites were significantly different in patients compared with controls. One of them, called hypotaurine, a molecule that’s known to be important for the development of nerve cells and maintenance of the myelin sheath, was markedly decreased in MS patients.
The scientists also used detailed computer models to look at interactions between different bacteria and metabolites. They found there were several connections seen in healthy oral microbiomes that appear to be disrupted in MS.
“These findings provide one of the most detailed views to date of the relationship between oral microbes, bacterial function, and host metabolism in MS,” Mangalam said. “The results expand our understanding of MS beyond the gut and brain and highlight the mouth as another important site of immune-microbial interaction.”
The scientists stressed that this study was limited to a relatively small number of patients, so further research will be needed to validate these findings in larger and more diverse populations. They also didn’t have data on whether the patients had dental disease, which will be a key consideration for future studies.
While the data suggest an association between MS and a dysregulated oral microbiome, the team noted it’s not clear whether changes in the oral microbiome may contribute to MS, or if MS causes changes in oral bacteria, or both. Further research will be needed to address these questions.
“These findings, while promising, should be interpreted with caution due to the lack of periodontal data and may reflect an indirect association rather than a direct link between the oral microbiome and MS,” the scientists wrote.
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