Gut microbiota development in preterm and non-preterm infants, with Dr. Marie-Claire Arrieta PhD

This episode features Dr. Marie-Claire Arrieta PhD from the University of Calgary (Canada), speaking about development of the early life gut microbiome, both in preterm and non-preterm infants. Across the field, it has been established that the early days and months of an infant’s life are very determinant of immune system development as well as chronic disease later in life. In this period, environmental cues are important, with some of these cues coming from the gut microbiome – both bacteria and fungi. Preterm infants show a very different gut microbiome than non-preterm infants. Ample evidence shows probiotics given to preterm infants can bring clinical benefits such as a reduced risk of necrotizing enterocolitis, but this is separate from investigations into the infants’ gut microbiomes. Dr. Arrieta’s work has shown that probiotics can guide the gut ecosystem of preterm infants toward approximating the non-preterm gut microbiome. One gap in the research is to know more about the effects of specific strains; their work found that although bifidobacteria were more effective at colonizing in the gut, lactobacilli drove some aspects of microbiota maturation. Dr. Arrieta speculates that the case for probiotic use for preterm infants will become stronger as trials increasingly focus on health outcomes not just during the neonatal intensive care unit stay, but also later in life. Overall in healthy infants, different patterns of gut microbiome and immune development can lead to the appearance of diseases later in life. The latest insight is that disease is linked not to specific microbes or metabolites, but to the pace of gut microbiome development. Misalignment of gut microbiome development (too early or too late) with stages of immune development is associated with later emergence of allergic disease. Several factors such as C-section birth and antibiotics may contribute to this misalignment, but breastfeeding seems to mitigate it. Dr. Arrieta has an ongoing longitudinal study on the early life microbiota and disease associations in preterm and non-preterm infants that is likely to reveal more details. Episode abbreviations and links: • Study from Arrieta lab showing effects of a probiotic on the gut microbiome of preterm infants: Supplementation with a probiotic mixture accelerates gut microbiome maturation and reduces intestinal inflammation in extremely preterm infants (https://www.cell.com/cell-host-microb...) • Study combining preterm infant data from several countries, showing links between gut microbiota, immune system development, and late-onset sepsis: Gut microbiota immaturity with DL-endopeptidase deficiency links antibiotic use to preterm late-onset sepsis (https://www.cell.com/cell-host-microb...) • Arrieta lab website: https://www.arrietalab.com/ • Let Them Eat Dirt website with resources for the general public: https://letthemeatdirt.com/ About Dr. Marie-Claire Arrieta PhD: Dr. Marie-Claire Arrieta is a Professor and Research Excellence Chair at the Cumming School of Medicine, University of Calgary. Her research examines interactions between the early-life gut microbiome and infant development. Her program integrates clinical and experimental approaches to uncover mechanisms of host–microbiome communication. Her work, published in leading journals, has accumulated over 12,000 citations. She has presented her research internationally through more than 120 invited talks to scientific, medical and public audiences. A dedicated mentor, she has supervised over 45 undergraduate, medical, PhD, and postdoctoral trainees. Her contributions have been recognized with the CIHR-SickKids New Investigator Award, the Killam Emerging Research Leader Award, and election to the College of New Scholars of the Royal Society of Canada. Dr. Arrieta is co-author of the best-selling public book, Let Them Eat Dirt, and is involved in several science communication initiatives.