MECONIUM, the first stool passed after birth, is a rich source of ingested and excreted metabolites and serves as the initial metabolic niche for microbes entering the gut. Microbiota maturation and immune development are implicated in allergic diseases and recent studies have revealed the importance of prenatal influences on these. Therefore, academics at the University of British Columbia, Vancouver, Canada, investigated the link between prenatal development and the early-life microbiota composition to identify factors associated with allergic sensitisation.
The researchers performed a global metabolomics analysis of meconium samples in a subset of 100 infants, who were enrolled in the Canadian Healthy Infant Longitudinal Development (CHILD) cohort. A significant reduction in bacterial α-diversity was detected at early time points in infants who developed immunoglobulin E-mediated allergic sensitisation by 1 year of age compared with non-atopic controls. Specifically, 13 of 15 taxa were decreased in relative abundance in the atopic individuals relative to the controls.
Senior co-author Brett Finlay, Professor in the Michael Smith Laboratories at the University of British Columbia, provided a succinct summary of the findings: “Our analysis revealed that newborns who developed allergic sensitization by one year of age had significantly less ‘rich’ meconium at birth, compared to those who didn’t develop allergic sensitization.”
Reductions in diversity were limited to particular metabolic pathways, such as amino acids, nucleotides, steroids, and vitamins. The researchers proposed a number of mechanistic links between these metabolic shifts, immune development, and allergic sensitisation. For instance, oestriol, a steroid that is reduced within atopic meconium, has been shown to generate tolerogenic immune cells that protect against autoimmunity.
The researchers also employed a machine-learning algorithm to analyse combined meconium, microbe, and clinical data. This predicted, with a high degree (76%) of accuracy and more reliably than ever before, whether an infant would develop allergies by 1 year of age.
Stuart Turvey, Department of Pediatrics, University of British Columbia, outlined the wider relevance of the study: “We know that children with allergies are at the highest risk of also developing asthma. Now we have an opportunity to identify at-risk infants who could benefit from early interventions before they even begin to show signs and symptoms of allergies or asthma later in life.”