A new study that used a rat model has suggested that people who live together may affect one another’s gut microbiomes. Research has shown that the microbes in the gastrointestinal tract–the gut microbiome can affect us dramatically, and things we do can also affect them, like our habits and diets, as well as the genes we carry and express. It is a complex relationship. And new research has now indicated that those who are closest to us could also impact our gut microbiomes. The findings have been reported in Nature Communications.
In this study, researchers analyzed genetic and microbiome data from over four thousand genetically distinct animals that were raised in one of four standardized environments. This was meant to reveal what effects were due to genes, and which were happening because of the environment. The team identified three regions of the rat genome that had a consistent impact on gut bacteria, even when the animals were raised in totally different environmental conditions.
The gene that had the strongest link to the gut microbiome was called St6galnac1; this gene encodes for a protein that adds sugar molecules to gut mucus. This gene was associated with changes in the levels of a gut microbe called Paraprevotella, which may be consuming those sugar molecules in gut mucus.
Another genomic region that was linked to the gut microbiome was one that holds mucin genes; these help maintain the protective mucus layer in the gut. These genes were associated with bacteria in the Firmicutes group.
A genomic region that holds a gene called Pip that encodes for an antimicrobial molecule was associated with Muribaculaceae family bacteria, which are found in rodents and humans.
A rat’s gut microbiome was found to be affected by its own genes, as well as the genes of the rats they lived with. Genes are not known to be shared between individual animals, but gut microbes can share genes with each other. There are genes that prefer specific gut microbes, and they are able to move during close social contact.
"This is not magic, but rather the result of genetic influences spilling over to others through social contact. Genes shape the gut microbiome and we found that it is not just our own genes that matter," explained senior study author Dr. Amelie Baud, a researcher at the Center for Genomic Regulation in Barcelona.
Only two genes have been consistently linked to changes or impacts on gut bacteria in humans: a lactate gene that enables adults to digest milk and can affect microbes that digest milk; and the ABO blood group gene that can influence the gut microbiome through an unknown mechanism.
There may be many ways that host genes, and the genes of those around them, could be influencing gut microbes.
"We've probably only uncovered the tip of the iceberg," Baud added. "These are the bacteria where the signal is strongest, but many more microbes could be affected once we have better microbiome profiling methods."
More research will be needed to confirm these findings in humans, but it could show that our genes do not only affect our health but the health of those closest to us, and vice versa.
Sources: Center for Genomic Regulation, Nature Communications
