Children Raised on Farms Avert Allergies

Infants raised on farms with environmental and animal diversity have enriched levels of bacteria in their gut microbiomes, which is associated with a lower risk for allergy and asthma, new research suggests.

"Just being raised on a farm is, in fact, correlated with changes in the gut," said investigator Julia Thorsen, MD, from the University of Wisconsin–Madison. But it turns out that "the type of farm an infant is exposed to is also an important factor in the development of the gut microbiome."

These study results offer clues for the development of new therapeutics, but it is early days for microbiome-modulating agents.

"We're getting ready for early-stage clinical trials, especially in areas where there would be the most impact, like asthma and allergies," Christina Ciaccio, MD, explained at the American Academy of Allergy, Asthma and Immunology 2019 Meeting in San Francisco.

But questions remain about safety and effectiveness that will challenge regulators, Ciaccio, who is from the University of Chicago, pointed out.

"I don't know if you can patent a probiotic cocktail or fiber supplements. It may be up to our partners in the pharmaceutical industry to see where we can have an impact," she explained.

In one study, researchers demonstrated that Akkermansia and Clostridia bacteria reduce gut inflammation and are associated with a lower risk for atopy and asthma in urban populations (Nat Med. 2016;22:1187-1191).

Comparing Stool Samples

"We wanted to see if the stools of infants raised on a farm were different than those of infants not raised on a farm," Thorsen told Medscape Medical News. "We didn't know the degree of farm exposure that would affect the stool."

Thorsen presented findings from a study of stool samples from infants born after 2013 and enrolled in the Wisconsin Infant Study Cohort (WISC) — 94 with farm exposure and 110 without.

Stool samples were collected when the infants were 2 months of age, and DNA was sequenced using the MiSeq System from Illumina. The investigators amplified the V4 region of the 16S ribosomal RNA. They extracted high-quality biomarker profiles from 89 farm infants and 102 nonfarm infants.

From the samples, Thorsen and her colleagues identified six differentially enriched taxa (P < .2 adjusted for false discovery rate). In stool samples from infants with farm exposure, members of the bacterial genera Akkermansia, Blautia, and Clostridiaceae were enriched. In contrast, in stool samples from infants without farm exposure, members of the genera Bifidobacterium, Veillonella, and Clostridium were enriched.

"Interestingly, the bacteria found to be more enriched in infants from diverse farms have also been found to be enriched in urban infants protected from atopic disease," Thorsen reported.

Simple farm exposure is associated with a lower prevalence of atopy and asthma (Nat Rev Immunol. 2010;10:861-868) but, to date, no data have shown that the type of farm makes a difference.



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