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Updated: Aug 5, 2026
05:31
Noninvasive Sampling of Mucosal Lining Fluid for the Quantification of In Vivo Upper Airway Immune-mediator Levels
Published on: August 7, 2017
Gram-Positive Bacteria and the Inverse Association between Farm Exposure and Childhood Asthma
Giulia Pagani1, Georg Loss2,3, Sonali Pechlivanis1
1Institute of Asthma and Allergy Prevention, Helmholtz Munich, Neuherberg, Germany.
NEJM Evidence
|July 28, 2026
Summary
Farm exposure protects against childhood asthma, primarily due to specific gram-positive bacteria in dust. These bacteria produce metabolites that interact with human receptors, offering new avenues for asthma prevention strategies.
Area of Science:
- Environmental microbiology
- Immunology
- Epidemiology
Background:
- Farm exposure is linked to reduced asthma and atopic conditions.
- The specific microbes and mechanisms driving this protective effect are not well understood.
Purpose of the Study:
- To identify specific bacterial taxa in farm environments associated with protection against asthma.
- To elucidate the metabolic pathways and host interactions involved in the farm-environment-asthma relationship.
Main Methods:
- 16S rRNA gene sequencing of mattress dust from 1018 schoolchildren.
- Bioinformatic analysis of bacterial metabolic pathways (PICRUSt2).
- Mass spectrometry for metabolite detection and statistical analyses (network, interaction, mediation).
Main Results:
- A composite score of nine gram-positive bacterial genera explained two-thirds of the protective effect of farm exposure on asthma.
- Identified bacterial metabolites (e.g., kynurenine, α-linoleic acid) are ligands for human aryl hydrocarbon receptor and peroxisome proliferator-activated receptor-γ.
- Gene-environment interactions were observed between bacterial genera and human receptor polymorphisms for asthma risk.
Conclusions:
- Childhood asthma and farm exposure inverse association is significantly mediated by gram-positive bacteria.
- Bacterial metabolites and their interaction with human receptors present novel targets for asthma prevention.
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