Germaphobes: Take Notice

Generally speaking, farm kids just seem healthier than their city cousins. Time outdoors, physical chores, fresh foods and clean air probably contribute, but scientists in recent years have identified and studied another critical difference – the gut microbiome and its associations with immunity.

Several studies have shown that farm kids, with regular exposure to livestock, develop a more diverse population of microbes in their gastro-intestinal (GI) tract compared to city kids who live in more sterile environments. Recently, researchers from the Ohio State University conducted a trial comparing babies from Amish farms with babies from urban households, and found evidence that the more diverse microbiome in the farm kids might help protect them from respiratory conditions such as asthma and allergies later in life. They also demonstrated that germ-free piglets can work as models for testing relationships between microbial populations and immune-system development.

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

The research team collected fecal samples from 10 Ohio babies, ranging from about six months to one year of age. Five of the babies lived on Amish farms with livestock, while the other five lived in the Ohio town of Wooster, and had no known contact with livestock.

They found that the Amish infants had greater species richness compared with the non-Amish infants' microbiota, with higher populations of some microbe genera with known benefits to the immune system.

In a second stage of the study, the researchers transplanted the fecal microbiotas of the Amish and the non-Amish infants into germ-free (Gf) piglets. They found the diversity and structure of the microbiota in the transplanted piglets remained similar at phylum level but not at the genus level. “Some of the colonized bacterial genera were correlated with the frequency of important lymphoid and myeloid immune cells in the ileal submucosa and mesenteric lymph nodes (MLN), both important for mucosal immune maturation,” the authors note. 

Overall, the researchers say the study demonstrated that transplantation of diverse IFM into germ-free piglets largely recapitulates the differences in gut microbiota structure between rural (Amish) and urban (non-Amish) infants. Thus, fecal microbiota transplantation to germ-free piglets could be a useful large animal model system for elucidating the impact of gut microbiota on the mucosal immune system development.

At a more basic level, the study provides further evidence that early exposure to a diversity of microbes associated with livestock could benefit the long-term health of farm kids.

"Good hygiene is important, but from the perspective of our immune systems, a sanitized environment robs our immune systems of the opportunity to be educated by microbe, says co-author Zhongtang Yu, a professor of microbiology in Ohio State's Department of Animal Sciences and a member of the university's Food Innovation Center.

Read the full report from Frontiers in Immunology.

For more on the microbiome and its relationship with immunity, see these articles from BovineVetOnline:

Dissecting the Microbiome

Nursing Could Benefit Microbiome, Vaccine Response

Encourage the “Good Bugs”