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Updated: Jun 27, 2026
Noninvasive Sampling of Mucosal Lining Fluid for the Quantification of In Vivo Upper Airway Immune-mediator Levels
Published on: August 7, 2017
Contrasting immunological effects of two disparate dusts - preliminary observations
Harri Alenius1, Jaakko Pakarinen, Ossian Saris
1Finnish Institute of Occupational Health, Helsinki, Finland. Harri.Alenius@ttl.fi
Background:
Modern lifestyle and urbanization have been associated with a raised risk for atopic diseases whereas early and long-term exposure to a farm environment confers protection against atopic sensitization. Immunomodulatory potential and microbiological characteristics of settled airborne dust from an urban house and a barn were examined.
Methods:
Pulmonary inflammation was induced in mice by repeated intranasal administration of dusts. Monocyte-derived human dendritic cells (moDCs) were exposed to dusts followed by coculture with purified naïve T cells. Cytokine/chemokine mRNA and protein levels were analyzed by real-time polymerase chain reaction, enzyme-linked immunosorbent assay and flow cytometry. The dusts were analyzed by cloning and sequencing of 16S rRNA genes (290 sequences) for DNA, lipids, endotoxin and beta-glucan, by live-dead staining, viable counting, isolation and identification of pure cultures (n = 76).
Results:
Repeated exposure to house dust elicited pulmonary eosinophilia in mice whereas exposure to barn dust elicited neutrophilic and lymphocytic airway inflammation. Stimulation of moDCs with urban house dust elicited expression of Th2-promoting OX40L and Jagged-1 costimulatory molecules. Dendritic cells (DCs) exposed to house dust directed naïve T cells towards Th2 responses. Exposure of DCs to barn dust elicited the development of Th1-dominated immune responses. Urban house dust contained bacterial debris almost exclusively of human commensal species (corynebacteria, streptococci) whereas barn dust comprised mainly intact, viable bacteria of high diversity and no commensal species.
Conclusion:
Contact to debris originating from human commensal bacteria in urban house dust elicited a Th2-type response whereas barn dust with high bacterial diversity directed the cells towards a Th1 response.
Insights
Urban house dust containing human commensal bacteria triggers Th2 immune responses, while diverse barn dust promotes protective Th1 responses. This highlights how environmental microbial exposures influence immune system development and atopic disease risk.
Area of Science:
- Immunology
- Microbiology
- Environmental Health
Background:
- Urbanization and modern lifestyles are linked to increased atopic disease risk.
- Early and prolonged exposure to farm environments offers protection against atopic sensitization.
Purpose of the Study:
- To investigate the immunomodulatory potential of urban house dust versus barn dust.
- To characterize the microbiological differences between these dust types.
Main Methods:
- Mice were exposed intranasally to dusts to induce pulmonary inflammation.
- Human monocyte-derived dendritic cells (moDCs) were exposed to dusts and co-cultured with T cells.
- Gene expression, protein levels, and microbial composition (16S rRNA sequencing, culturing) of dusts and cellular responses were analyzed.
Main Results:
- House dust exposure in mice led to eosinophilic lung inflammation, while barn dust induced neutrophilic and lymphocytic inflammation.
- Urban house dust stimulated moDCs to express Th2-promoting molecules (OX40L, Jagged-1), directing T cells towards Th2 responses.
- Barn dust exposure promoted Th1-dominated immune responses, with barn dust containing diverse, viable bacteria, unlike the commensal debris in house dust.
Conclusions:
- Debris from human commensal bacteria in urban house dust elicits a Th2-type immune response.
- Barn dust, rich in diverse and viable bacteria, directs immune cells towards a protective Th1 response.
- Environmental microbial exposures significantly shape immune responses, influencing atopic disease susceptibility.
