TUESDAY, Sept. 12, 2017 (HealthDay News) -- Certain types of bacteria in the gut may play a role in the progression of multiple sclerosis, according to researchers working with mice.
The research, the study authors believe, could lead to new ways to treat multiple sclerosis (MS), an autoimmune neurodegenerative disease that affects about 2.5 million people worldwide.
"The [gut] microbiome is very malleable," study senior author Sergio Baranzini said. "You could relatively easily change it in an adult who has MS or is susceptible -- something you cannot do with their genetics. This is not a magical approach, but it is hopeful."
MS occurs when the immune system attacks the insulation (myelin) around nerve cells. This can lead to vision loss, weakness, problems with coordination and balance and, in some cases, paralysis.
The study included 71 MS patients and a "control" group of 71 healthy people. Specific species of gut bacteria (microbes) were more common in people with MS. When these species of gut microbes were transplanted into mice, the microbes affected their immune systems.
"The field has been very successful in identifying genes associated with susceptibility to MS, but I've never been satisfied with the amount of risk that we'll be able to explain with just genetics," said Baranzini, a professor of neurology at the University of California, San Francisco.
"Even identical twins, who share the same genetic inheritance, only share an MS diagnosis about 35 percent of the time," he said in a university news release. "It's clear the genome is important, but environmental factors [such as diet, smoking and surroundings] must also play a major role."
Previous studies have shown that gut microbes have a direct influence on the immune system, so the UCSF researchers decided to investigate what role these microbes might play in MS.
The findings were published online Sept. 11 in the journal Proceedings of the National Academy of Sciences.
A second study in the same journal issue also found that transplanting certain types of gut bacteria from MS patients into mice affected the animals' immune systems.
"Two different groups, using two separate cohorts of patients and controls, and two distinct mouse models of the disease, saw very similar results. This is very promising evidence that we're on the right track," said Egle Cekanaviciute, a UCSF postdoctoral researcher.
"To be clear, we don't think the microbiome is the only trigger of MS. But it looks like these microbes could be making the disease progression worse or better -- pushing someone with genetic predisposition across the threshold into disease or keeping them safe," Cekanaviciute explained.
Possible treatments include diet changes or drugs based on microbial byproducts, according to the researchers.
It's important to note, however, that results of animal research often aren't replicated in humans.
The U.S. National Institute of Neurological Disorders and Stroke has more on multiple sclerosis.