Early exposure to farm animals can lead to robust development of the immune system

Getting up close – and a bit dirty – with farm animals might help us fight the disease, say researchers who have shown the benefits of early exposure to a wide variety of bacteria in the world. 39; environment.

Scientists from Ohio State University found that the bacteria and other microbes of rural Amish babies were much more diversified – beneficially – than those found in the intestines of city babies. And, in an unprecedented experiment, they found evidence of how a healthier intestinal microbiome could lead to a more robust immune system development of the airways.

The study was published this month in the journal Frontiers in Immunology.

Good hygiene is important, but from the point of view of our immune system, a healthy environment deprives our immune system of the possibility of being educated by microbes. Too clean is not necessarily a good thing. "

Zhongtang Yu, co-lead author of the study, professor of microbiology at the Ohio State Department of Animal Sciences and member of the University Food Innovation Center

The research team collected stool samples from 10 Ohio babies aged 6 months to about a year old. The five Amish babies lived in rural houses with farm animals. The other five babies lived in or near Wooster, a mid-Ohio town, and had no known contact with cattle.

The samples revealed significant differences – particularly a large variation in microbes and an abundance of beneficial bacteria in the intestines of Amish babies that was not found in their counterparts living in the city. Researchers were expecting it because of the exposure of infants to livestock and the fact that the Amish tend to lead a relatively less sanitized life than most other Americans.

"The early immune system priming is very different in Amish babies, compared to urban dwellers," said Renukaradhya Gourapura, co-lead author of the study and a professor at the College of Food Science. , agriculture and the environment and animal health, in the state of Ohio. Research program.

What they really wanted to know was how these differences could affect the development of the immune system, thus laying the foundation for an organism's ability to identify and attack diseases and its resistance. allergies and other immune system problems. Previous studies of the American Amish population and comparable populations around the world have clearly linked rural life to a decrease in allergies and asthma, Gourapura said.

This connection has led to a theory called "hygiene hypothesis", which is based on the idea that modern hyper-clean life – think of antibacterial soap, ubiquitous hand sanitizer and homes and places cleaned – cleaned allergic diseases.

Since we know that billions of microbes in the human gut play an important role in the health and progression of the disease, researchers from the state of Ohio have wanted to explore how different intestinal microbiomes might contribute to the development of the immune system. To do this, they used feces grafts from the babies participating in the study to colonize the bowel of newborn pigs.

"We wanted to know what was happening in the early development of the immune system when newborn pigs with gutless intestines were receiving intestinal microbes from human babies raised in different environments," Gourapura said. "From the day of their birth, these Amish babies have been exposed to various microbial species inside and outside their homes."

The researchers found a link between the various microbes in the Amish intestine and a more robust development of immune cells, particularly lymphoid and myeloid cells in the intestines.

"Indeed, there was a big difference in the generation of critical immune cells," Gourapura said.

Previous research on the link between the microbiome and immunity has been conducted on mice, and this study has shown that pigs – whose anatomy, immune systems, genetics and physiology are more similar to humans – are a viable option for further studies, Gourapura said. . This is an important step as it opens the door for a better exploration of the details of the microbial links between the gut and the immune system of the respiratory tract in infants, he said.

"Researchers know that the intestinal microbiome probably plays an important role in the development of the immune system and in the appearance of various metabolic processes and infectious diseases, but we need better models to discover the details of this process and to be able to use this information to: improve human health, "said Gourapura.

For example, some probiotics could improve bowel health and immune system development, Yu said.

Although the main difference between study babies is their exposure to an agricultural environment, the researchers also noted that two of the non-Amish babies were formula fed only, while all Amish babies of this study were badfed. Another important difference that could contribute to gut microbiome differences between groups is that Amish families have grown and have systematically eaten their own products.