The innate immune system plays a large role in the development of and protection from asthma, as demonstrated by literature examining the low rate of asthma in children who are consistently exposed to several different environmental microbes on family farms, according to results from a literature review published in Clinical & Experimental Allergy.

Several studies have demonstrated a “farm effect” — showing that children with exposure to livestock and animal feed early and throughout life, consumption of raw milk, and contact with environmental microbes — has an associated lower prevalence of allergic diseases and asthma. In Amish traditional farming communities, this “farm effect” correlation is apparent in children.

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Gram-negative Acinetobacter lwoffii F78 and the gram-positive Lactococcus lactis G121, found in cowshed microflora, is potentially associated with reductions of allergic inflammation in mice. The literature reports a lower asthma rate in children of mothers who were exposed to these microbes. Environmental microbes in animal sheds, such as Bacillus licheniformis and farm-derived gram-positive Staphylococcus sciuri W620, have also been implicated in protection from asthma.

According to the investigators, a research group has previously demonstrated that the induction of negative regulator A20 in epithelial cells via exposure to farm dust or low-dose endotoxin was associated with protection from house dust mite-induced asthma. They also noted that prenatal exposure to microbial diversity may “prime” an immune response in children while protecting against atopic sensitization “by upregulating innate immune receptors such as CD14, TLR4, and TLR2.”


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The investigators concluded that host microbiome trajectories and the timing of environmental exposures, “also [play] a major role in shaping innate immune responses, thus offering multiple opportunities for both research and clinical interventions.”

Reference

Pivniouk V, Gimenes Junior JA, Honeker L, Vercelli D. The role of innate immunity in asthma development and protection: lessons from the environment [published online October 3, 2019]. Clin Exp Allergy. doi:10.1111/cea.13508