MS and gut microbiome pattern similar across US, Asia: Analysis
MS patients across populations show 'generalized and common' pattern
People with multiple sclerosis show subtle alterations in gut bacteria that seem to be consistent across populations in the U.S. and Asia, a new analysis of previously published studies found.
“Our work … establishes a generalized and common gut microbiome pattern in patients with MS across geographically and technically diverse studies,” the researchers wrote. The study, “Meta-analysis identifies common gut microbiota associated with multiple sclerosis,” was published in Genome Medicine.
The human gut is home to billions of bacteria and other microscopic organisms, collectively known as the gut microbiome. These bacteria can powerfully impact human health, but their effects are only beginning to be understood.
Over the last several years, multiple studies have investigated whether there are differences in the gut microbiome in people with MS compared with individuals who don’t have the disease. Many studies have found striking differences — but often these differences aren’t consistent from study to study.
“For a long time, people have questioned whether there are true microbiome signatures in MS,” Yanjiao Zhou, MD, PhD, associate professor of medicine at the University of Connecticut and co-author of the study, said in a university press release. “Our findings support the idea of a microbiome signature.”
Differences in environment, diet
Investigating the gut microbiome is especially complex because the makeup of gut bacteria can be influenced by factors such as environment and diet, which can differ greatly among people living in different places or with different cultural backgrounds.
Aiming to get a more comprehensive overview of MS-related microbiome changes, the researchers conducted a meta-analysis, a type of study in which scientists pool data from multiple published studies and analyze all the data collectively.
This meta-analysis included data from seven prior studies, five from the U.S., one from China, and one from Japan. A total of 257 MS patients and 267 controls were included in these studies, and a vast majority of patients (98.4%) had the relapsing-remitting disease type.
Results showed that MS patients consistently had lower than normal levels of bacteria in the group Faecalibacterium. This class of bacteria is thought to have anti-inflammatory effects, so low levels may contribute to MS-driving inflammation.
MS patients also had higher than normal levels of another type of bacteria, Actinomyces. This group of bacteria is known to be abundant in the human digestive tract, especially in the mouth.
Another common type of microbiome bacteria called Prevotella also tended to be found at lower than normal levels in MS patients compared with people without MS. In a healthy microbiome, there’s normally an inverse correlation between levels of Prevotella and levels of another group called Bacteroides: In other words, people with higher abundance of bacteria in one of these groups tend to have lower levels of the other.
But in MS patients, the normal correlation between these two groups was no longer evident.
Overall, the data show that “there are consistent microbial signatures associated with MS across studies,” the scientists wrote.
The team noted that their analysis looked at broad groups of bacteria, not individual species, so the role of specific bacteria in MS requires further research to understand. “While we are happy that the microbiome differences between MS and healthy people are finally settled, it is important to study the functional microbiome biomarkers in MS next,” Zhou said.
The scientists also highlighted that the biggest driver of microbiome variation from study to study wasn’t related to disease status, but rather to the specific methods that researchers used to analyze gut bacteria. The researchers said they did their best to account for these methodological variances in their analysis, but they stressed a need for standardized procedures in future studies looking at the gut microbiome in MS.
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