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Soil exposure modulates the immune response to an influenza challenge in a mouse model
Alexander W McCumber1, Yeon Ji Kim2, Joshua Granek3
1Department of Environmental Sciences and Engineering, University of North Carolina, Chapel Hill, Chapel Hill, NC, USA.
Abstract:
There is increasing evidence that early life microbial exposure aids in immune system maturation, more recently known as the "old friends" hypothesis. To test this hypothesis, 4-week-old mice were exposed to soils of increasing microbial diversity for four weeks followed by an intranasal challenge with either live or heat inactivated influenza A virus and monitored for 7 additional days. Perturbations of the gut and lung microbiomes were explored through 16S rRNA amplicon sequencing. RNA-sequencing was used to examine the host response in the lung tissue through differential gene expression. We determined that compared to the gut microbiome, the lung microbiome is more susceptible to changes in beta diversity following soil exposure with Lachnospiraceae ASVs accounting for most of the differences between groups. While several immune system genes were found to be significantly differentially expressed in lung tissue due to soil exposures, there were no differences in viral load or weight loss. This study shows that exposure to diverse microbial communities through soil exposure alters the gut and lung microbiomes resulting in differential expression of specific immune system related genes within the lung following an influenza challenge.
Insights
Early life exposure to diverse microbes in soil alters gut and lung microbiomes in mice. This exposure modifies immune gene expression in the lungs following an influenza challenge, supporting the "old friends" hypothesis.
Area of Science:
- Microbiology
- Immunology
- Environmental Health
Background:
- The "old friends" hypothesis suggests early microbial exposure is crucial for immune system development.
- Understanding how environmental microbial diversity impacts host immunity is essential for public health.
Purpose of the Study:
- To investigate the effects of soil microbial exposure on the gut and lung microbiomes in mice.
- To determine the host immune response in the lung following influenza A virus challenge after soil exposure.
Main Methods:
- Mice were exposed to soils of varying microbial diversity for four weeks.
- Intranasal challenge with influenza A virus (live or inactivated) was performed.
- Gut and lung microbiomes were analyzed using 16S rRNA amplicon sequencing.
- Host gene expression in lung tissue was examined via RNA-sequencing.
Main Results:
- Soil exposure significantly altered lung microbiome beta diversity, with Lachnospiraceae ASVs being key contributors.
- While several immune-related genes showed differential expression in lung tissue, viral load and weight loss were unaffected.
- The lung microbiome proved more susceptible to microbial diversity changes than the gut microbiome.
Conclusions:
- Exposure to diverse microbial communities via soil impacts both gut and lung microbiomes.
- This exposure leads to altered immune gene expression in the lung post-influenza challenge.
- Findings support the role of environmental microbial exposures in immune system modulation.
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