A new study, led by scientists from Harvard University, is offering more compelling evidence of a link between the development of amyotrophic lateral sclerosis (ALS) and the gut microbiome. One researcher described the discovery as “remarkable”, after finding genetically identical mice displayed different health outcomes determined by their specific gut bacteria communities.
Mutations in a gene called C9orf72 account for more familial cases of ALS than any other genetic variant. ALS is generally thought to be caused by a relatively equal balance of genetic and environmental factors and, although researchers have homed in on a number of particular genetic variants that can be associated with the disease, it is still unknown what particular environmental elements play a role.
This new research stemmed from an initial unexpected observation. Mice bred with C9orf72 mutations designed to model ALS displayed significantly different health effects at two separate locations.
“Many of the inflammatory characteristics that we observed consistently and repeatedly in our Harvard facility mice weren’t present in the Broad facility mice,” explains lead author of the new study, Aaron Burberry. “Even more strikingly, the Broad facility mice survived into old age. These observations sparked our endeavor to understand what about the two different environments could be contributing to these different outcomes.”
After investigating a number of potential variables that could account for these substantially different health outcomes, the researchers focused in on differences in the animal’s microbial flora as the possible primary factor. DNA sequencing indeed confirmed a number of microbial differences between the two cohorts of mice, despite similar lab conditions.
“At this point, we reached out to the broader scientific community, because many different groups have studied the same genetic mouse model and observed different outcomes,” says Burberry. “We collected microbiome samples from different labs and sequenced them. At institutions hundreds of miles apart, very similar gut microbes correlated with the extent of disease in these mice.”