Project description:Diet-microbe interactions play a crucial role in infant development and modulation of the early-life microbiota. The genus Bifidobacterium dominates the breast-fed infant gut, with strains of B. longum subsp. longum (B. longum) and B. longum subsp. infantis (B. infantis) particularly prevalent within the early-life microbiota. Although, transition from milk to a more diversified diet later in infancy initiates a shift to a more complex microbiome, with concurrent reductions in Bifidobacterium abundance, specific strains of B. longum may persist in individual hosts for prolonged periods of time. Here, we sought to investigate the adaptation of B. longum to the changing infant diet during the early-life developmental window. Genomic characterisation of 75 strains isolated from nine either exclusively breast- or formula-fed infants in the first 18 months of their lives revealed subspecies- and strain-specific intra-individual genomic diversity with respect to glycosyl hydrolase families and enzymes, which corresponded to different dietary stages. Complementary phenotypic growth studies indicated strain-specific differences in human milk oligosaccharide and plant carbohydrate utilisation profiles between and within individual infants, while proteomic profiling identified proteins involved in metabolism of selected carbohydrates. Our results indicate a strong link between infant diet and B. longum subspecies/strain genomic and carbohydrate utilisation diversity, which aligns with a changing nutritional environment i.e. moving from breast milk to a solid food diet. These data provide additional insights into possible mechanisms responsible for the competitive advantage of this bifidobacterial species and their long-term persistence in a single host and may contribute to rational development of new dietary therapies for this important development window.
Project description:Microbiota assembly in the infant gut is influenced by time and duration of dietary exposure to breast-milk, infant formula and solid foods. In this randomized controlled intervention study, longitudinal sampling of infant stools (n=998) showed similar development of fecal bacterial communities between formula- and breast-fed infants during the first year of life (N=210). Infant formula supplemented with galacto-oligosaccharides (GOS) was most efficient to sustain high levels of bifidobacteria compared to formula containing B. longum and B. breve or placebo. Metabolite (untargeted) and bacterial profiling (16S rRNA/shallow metagenomics sequencing) revealed 24-hour oscillations and integrated data analysis identified circadian networks. Rhythmicity in bacterial diversity, specific taxa and functional pathways increased with age and was most pronounced following breast-feeding and GOS-supplementation. Circadian rhythms in dominant taxa were discovered ex-vivo in a chemostat model. Hence microbiota rhythmicity develops early in life, likely due to bacterial intrinsic clock mechanism and is affected by diet.
Project description:Maternal diet shapes infant microbiota and defensive capacity against infections in early life via differential breast milk composition
Project description:Infants and young children are more susceptible to common respiratory pathogens compared to adults, but can fare better against novel pathogens like SARS-CoV-2. The mechanisms by which infants and young children mount effective responses to respiratory pathogens are unknown. Here, we demonstrate through study of lungs and lung-associated lymph nodes (LLN) from infant and pediatric organ donors, aged 0-13 years, that bronchus-associated lymphoid tissue (BALT), develops in lungs during the first year of life. BALT structures, consisting of B cell follicles and T cell zones, increase in numbers in the early years, and subsequently decrease over childhood coincident with accumulation of memory T cells in the lung. Early life BALT contains germinal centers and supports B cell differentiation, clonal expansion, somatic hypermutation, and immunoglobulin class switching. High dimensional flow cytometry reveals seeding of lungs by newly formed B cells (transitional cells) during infancy coincident with the timing of maximal BALT formation. We further demonstrate increased lung-localized B cell responses during respiratory virus infection in infants. Together, our findings provide novel evidence for BALT as an early life adaptation for mobilizing in situ immune protection to the diverse respiratory challenges during this formative life stage.
Project description:Research shows that children who are reared in households with low socioeconomic status are more vulnerable to heart disease, respiratory infection, and some cancers when they reach adulthood. This study conducted transcriptional profiling of PBMC in healthy adults who were low vs. high in early-life SES to explore the long-lasting genomic effects of early experience. Keywords: life stress, gene expression, inflammation, socioeconomic status Samples from 30 adults with low early-life SES and 30 adults with high early-life SES