Lachnospiraceae bacteria in gut seen as potential MS risk factor
Study looks at gut bacteria of twins transplanted into mice
Elevated levels of two bacterial strains from the Lachnospiraceae family in the gut may be a key risk factor for multiple sclerosis (MS), according to a study.
The study, “Multiple sclerosis and gut microbiota: Lachnospiraceae from the ileum of MS twins trigger MS-like disease in germfree transgenic mice—An unbiased functional study,” was published in PNAS.
Billions of bacteria and other microscopic organisms make their home in the human digestive tract. Collectively known as the gut microbiome, these microbes play important roles in human health and disease that are only beginning to be understood.
Several studies have suggested that the gut microbiome is altered in MS. But scientists have struggled to pinpoint specific bacteria that are associated with MS. Individual studies often find different or contradictory results. Part of the issue is that the makeup of the gut microbiome is influenced by many factors, including genetics and lifestyle, which makes it hard to zero in on changes that are related to MS.
In this study, researchers analyzed the makeup of the gut microbiome in 81 pairs of monozygotic (identical) twins where one twin had MS and the other did not. Since identical twins share the same genetic code and siblings generally have similar lifestyle exposures, this approach aimed to cut down on variability due to factors other than MS.
Examining bacteria
Results revealed 51 different types of bacteria whose abundance was significantly altered in the twins with MS, relative to twins without MS.
The researchers set out to explore the functional relevance of bacteria in the guts of twins with or without MS. To do this, they used a germ-free mouse model, meaning mice that are engineered so that they completely lack their own gut microbiome. In the model that the researchers used, the mice are prone to developing MS-like neurological disease when bacteria are added to their guts.
The researchers took gut bacteria from the twins and transplanted them into the digestive tracts of these mice. For these experiments, the researchers used bacteria from two sets of twins, one female and one male. The female MS patient had fairly severe disease, whereas the male patient had relatively mild disease.
Despite these differences between the two pairs, mice transplanted with bacteria from the twins with MS were significantly more likely to develop MS-like disease than mice given bacteria from the twins who didn’t have MS.
Female mice were also more susceptible to developing MS than male mice.
The researchers noted that mice that developed MS tended to have high levels of bacteria belonging to the Lachnospiraceae family. This was consistent across both pairs of twins.
“Taken together, our results show an association of members of the Lachnospiraceae family derived from [gut] material with [MS-like disease] development across two independent and highly [varied] MS twin pairs,” the researchers wrote. The data indicate “that these bacteria might play a crucial role as environmental triggering factors of human MS,” the scientists added, though they stressed that additional research will be needed to test this idea in greater detail.
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