Abstract

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Gut microbiota development is impacted by mode of delivery, diet, lifestyle and environmental parameters such as closeness to animals. These parameters impact gut microbiota composition and have been linked to allergy protective effects (‘Microbiota hypothesis’). Microbiota composition and diet are further related to short chain fatty acid (SCFA) formation. Acetate, propionate and butyrate are major SCFA formed by gut microbes. They were shown to have anti-inflammatory properties and can induce IgA production by mucosal B cells. We hypothesise, that colonization by butyrate producers is a determining factor in the development of allergic diseases, and that spores are source of transmission to the infant gut.

To test our hypothesis, we will use fecal samples from the birth cohort study from St. Gallen (CARE -Childhood AlleRgy, nutrition and Environment - study) and monitor the natural course of atopic diseases by collecting from birth, in a prospective way, clinical and biological data from children (n=100). Fecal samples of healthy children and children diagnosed with atopic dermatitis (estimated n=20) in the 2 first years of life, collected 3, 6, 12 and 24 months after birth, will be analysed. Data obtained will be linked to fecal SCFA profiles of the infants, diet and environmental parameters.

This study, which is planned for a length of 1 year, will contribute to the understanding of gut microbiota development, and its link with allergic diseases in childhood. Results obtained here might lead to a therapeutical approach involving butyrate-producing gut microbiobes.

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Project Updates

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Sample collection

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Collection of fecal samples from 30 healthy infants and from 18 infants that have been diagnosed with atopic dermatitis. Samples were collected at 3 time points at 3, 6, and 12 months.

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Methodology testing

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Ongoing evaluation of methodology testing different microbial cultivation media with the outcome to use modified YCFA as we obtained maximum MPN using this medium in preliminary experiments. The analysis is ongoing, MPN of about 50% of the samples has been determined. DNA isolation and determination of SCFA formed in MPN samples is ongoing. Considering task 2 (‘Determine fecal SCFA concentrations’), fecal SCFA concentrations of 145 samples have been determined, we are currently analysing the data.

We are additionally analysing SCFA formed during MPN analysis to relative microbial fermentation activity with microbiota composition of the samples (see Task 1). In regard to task 3 (‘Determine 16S rRNA gene composition of fecal and spore microbiota’), 16S rRNA gene libraries of 80 fecal samples have been generated and sequenced, data analysis is currently ongoing.

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