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Published on: August 7, 2017
Gut bacteria at 6 months of age are associated with immune cell status in 1-year-old children
Morten Nilsen1, Unni Cecilie Nygaard2, Petter Brodin3,4
1Faculty of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, Ås, Norway.
Insights
Infant gut bacteria at six months influence immune cell composition by twelve months. Specific abundant species like Bifidobacterium adolescentis and Bacteroides fragilis are linked to immune cell clusters, suggesting a role for early microbiota development.
Area of Science:
- Microbiology
- Immunology
- Developmental Biology
Background:
- Infant gut microbiota development is well-studied, but its prospective association with immune cell composition remains unclear.
- Understanding this link is crucial for identifying early life factors influencing immune system maturation.
Purpose of the Study:
- To investigate the temporal relationship between gut bacterial development and immune cell composition in infants.
- To identify specific gut bacteria associated with distinct immune cell profiles.
Main Methods:
- Analysis of fecal bacteria and short-chain fatty acids from 67 infants across four timepoints (birth to 12 months) using reduced metagenome sequencing and gas chromatography.
- Assessment of immune cell frequencies in whole blood at 12 months using mass cytometry.
- Clustering of infants based on immune cell composition (naïve cells, monocytes, neutrophils).
Main Results:
- Significant associations between gut microbiota and immune cell clusters were observed across all ages, primarily with low-abundance species.
- Crucially, at 6 months, abundant (>8%) bacterial species showed significant associations with immune cell clusters at 12 months.
- Bifidobacterium adolescentis and Porphyromonadaceae linked to cluster 1 (naïve cells); Bacteroides fragilis and Bifidobacterium longum linked to clusters 3 and 4 (monocytes/neutrophils).
- No significant correlations were found between short-chain fatty acids and immune cell composition.
Conclusions:
- Abundant gut bacteria at 6 months of age may prospectively influence immune cell frequencies at 12 months.
- Specific gut commensals, such as Bifidobacterium and Bacteroides species, may play a role in shaping infant immune cell composition.
- These findings highlight the critical window of early life for microbiota-immune system interactions.
Abstract:
Age-related gut bacterial changes during infancy have been widely studied, but it remains still unknown how these changes are associated with immune cell composition. This study's aim was to explore if the temporal development of gut bacteria during infancy prospectively affects immune cell composition. Faecal bacteria and short-chain fatty acids were analysed from 67 PreventADALL study participants at four timepoints (birth to 12 months) using reduced metagenome sequencing and gas chromatography. Immune cell frequencies were assessed using mass cytometry in whole blood samples at 12 months. The infants clustered into four groups based on immune cell composition: clusters 1 and 2 showed a high relative abundance of naïve cells, cluster 3 exhibited increased abundance of classical- and non-classical monocytes and clusters 3 and 4 had elevated neutrophil levels. At all age groups, we did observe significant associations between the gut microbiota and immune cell clusters; however, these were generally from low abundant species. Only at 6 months of age we observed significant associations between abundant (>8%) species and immune cell clusters. Bifidobacterium adolescentis and Porphyromonadaceae are associated with cluster 1, while Bacteroides fragilis and Bifidobacterium longum are associated with clusters 3 and 4 respectively. These species have been linked to T-cell polarization and maturation. No significant correlations were found between short-chain fatty acids and immune cell composition. Our findings suggest that abundant gut bacteria at 6 months may influence immune cell frequencies at 12 months, highlighting the potential role of gut microbiota in shaping later immune cell composition.
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