Genes, birthplace shape our gut microbes: study

Our genes and birthplace may significantly affect the makeup of our gut microbiome, which plays an important role in keeping us healthy, according to a new study.
Researchers from Pacific Northwest National Laboratory (PNNL) and Lawrence Berkeley National Laboratory (Berkeley Lab) in the US linked specific genes in an animal - in this case, a mouse - to the presence and abundance of specific microbes in its gut.
"We are starting to tease out the importance of different variables, like diet, genetics, and the environment, on microbes in the gut. It turns out that early life history and genetics both play a role," said Janet Jansson from PNNL.

Scientists studied more than 50,000 genetic variations in mice and ultimately identified over 100 snippets that affect the population of microbes in the gut.
Some of those genes in mice are very similar to human genes that are involved in the development of diseases like arthritis, colon cancer, Crohn's disease, celiac disease and diabetes.
The abundance of one microbe in particular, a probiotic strain of Lactobacillales, was affected by several host genes and was linked to higher levels of important immune cells known as T-helper cells.

These results support the key role of the microbiome in the body's immune response, and suggest the possibility that controlling the microbes in the gut could influence the immune system and disease vulnerability.

"We know the microbiome likely plays an important role in fighting infections. We found that the level of T-helper cells in the blood of mice is well explained by the level of Lactobacillales in the gut. It is the same family of bacteria found in yogurt and very often used as a probiotic," said Antoine Snijders from Berkeley Lab.
Researchers drew upon a genetically diverse set of "collaborative cross" mice that capture the genetic variation in human populations.
Scientists studied 30 strains of the mice, which were housed in two facilities with different environments for the first four weeks of their lives.

The scientists took fecal samples from the mice to characterise their gut microbiomes before transferring them to a third facility.
They found that the microbiome retained a clear microbial signature formed where the mice were first raised-effectively their "hometown".
Moreover, that microbial trait carried over to the next generation, surprising the scientists.
"The early life environment is very important for the formation of an individual's microbiome. The first dose of microbes one gets comes from the mom, and that remains a strong influence for a lifetime and even beyond," said Jian-Hua Mao from Berkeley Lab.
The study appears in the journal Nature Microbiology.