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:On going efforts are directed at understanding the mutualism between the gut microbiota and the host in breast-fed versus formula-fed infants. Due to the lack of tissue biopsies, no investigators have performed a global transcriptional (gene expression) analysis of the developing human intestine in healthy infants. As a result, the crosstalk between the microbiome and the host transcriptome in the developing mucosal-commensal environment has not been determined. In this study, we examined the host intestinal mRNA gene expression and microbial DNA profiles in full term 3 month-old infants exclusively formula fed (FF) (n=6) or breast fed (BF) (n=6) from birth to 3 months. Host mRNA microarray measurements were performed using isolated intact sloughed epithelial cells in stool samples collected at 3 months. Microbial composition from the same stool samples was assessed by metagenomic pyrosequencing. Both the host mRNA expression and bacterial microbiome phylogenetic profiles provided strong feature sets that clearly classified the two groups of babies (FF and BF). To determine the relationship between host epithelial cell gene expression and the bacterial colony profiles, the host transcriptome and functionally profiled microbiome data were analyzed in a multivariate manner. From a functional perspective, analysis of the gut microbiota's metagenome revealed that characteristics associated with virulence differed between the FF and BF babies. Using canonical correlation analysis, evidence of multivariate structure relating eleven host immunity / mucosal defense-related genes and microbiome virulence characteristics was observed. These results, for the first time, provide insight into the integrated responses of the host and microbiome to dietary substrates in the early neonatal period. Our data suggest that systems biology and computational modeling approaches that integrate “-omic” information from the host and the microbiome can identify important mechanistic pathways of intestinal development affecting the gut microbiome in the first few months of life. KEYWORDS: infant, breast-feeding, infant formula, exfoliated cells, transcriptome, metagenome, multivariate analysis, canonical correlation analysis 12 samples, 2 groups
Project description:Exclusively breast-fed infants can exhibit clear signs of IgE or non IgE-mediated cow’s milk allergy. The definite characterization of dietary cow’s milk proteins (CMP) that survive the maternal digestive tract to be absorbed into the bloodstream and secreted into breast milk remains missing. The aim of this study was to assess the occurrence of CMP-derived peptides in breast milk, using antibody-independent methods. Using high performance liquid chromatography-high resolution mass spectrometry in blinded assays, we identified 11 cow’s milk-derived peptides, including two β-lactoglobulin (2 out 6 samples) and one αs1-casein (1 out 6 samples) fragments, in breast milk from mothers receiving a cup of bovine milk daily. The β-lactoglobulin (β-Lg) fragments, namely f42-54 and f42-57, were absent in milk from mothers who observed a strict dairy-free diet (6 samples). In contrast, neither intact nor hydrolyzed β-Lg was detected by Western blot or competitive ELISA tests. CMP-derived peptides rather than intact CMP may sensitize or elicit allergic responses in the neonate through mother’s milk. Immunologically active peptides from the maternal diet could be involved in priming the newborn’s immune system to drive tolerogenic response in neonates and infants.
Project description:Exclusively breast-fed infants can exhibit clear signs of IgE or non IgE-mediated cow’s milk allergy. The definite characterization of dietary cow’s milk proteins (CMP) that survive the maternal digestive tract to be absorbed into the bloodstream and secreted into breast milk remains missing. The aim of this study was to assess the occurrence of CMP-derived peptides in breast milk, using antibody-independent methods. Using high performance liquid chromatography-high resolution mass spectrometry in blinded assays, we identified 11 cow’s milk-derived peptides, including two ?-lactoglobulin (2 out 6 samples) and one ?s1-casein (1 out 6 samples) fragments, in breast milk from mothers receiving a cup of bovine milk daily. The ?-lactoglobulin (?-Lg) fragments, namely f42-54 and f42-57, were absent in milk from mothers who observed a strict dairy-free diet (6 samples). In contrast, neither intact nor hydrolyzed ?-Lg was detected by Western blot or competitive ELISA tests. CMP-derived peptides rather than intact CMP may sensitize or elicit allergic responses in the neonate through mother’s milk. Immunologically active peptides from the maternal diet could be involved in priming the newborn’s immune system to drive tolerogenic response in neonates and infants.
Project description:Development of the gut microbiota is greatly impacted in preterm infants. Despite increasing knowledge about microbiota composition in preterm infants, knowledge about the functional signatures of the intestinal microbiota remains limited. The aim was to study transitions in microbiota activity during the first six postnatal weeks in ten preterm infants. A total of 64 stool samples were measured by LC-MS/MS.
Project description:Development of the gut microbiota is greatly impacted in preterm infants. Despite increasing knowledge about microbiota composition in preterm infants, knowledge about the functional signatures of the intestinal microbiota remains limited. The aim was to study transitions in microbiota activity during the first six postnatal weeks in ten preterm infants. A total of 64 stool samples were measured by LC-MS/MS.
Project description:We developed a non-invasive ex vivo HT29 cell-based minimal model to fingerprint the mucosa-associated microbiota fraction in humans. HT29 cell-associated fractions were characterized by the universal phylogenetic array platform HTF-Microbi.Array, both in presence or in absence of a TNF-M-NM-1-mediated pro-inflammatory stimulus. A high taxonomical level fingerprint profiling of the mucosa-associated microbiota was performed on a group of 12 breast-fed infants and 6 adults (used as controls). Relative abundance of the bacterial species was assessed by using a so-called HTF-Microbi.Array, based on a ligation detection reaction (LDR) - Univerasal array (UA) assay, capable of correctly identify up to 31 intestinal bacterial groups, covering up to 95% of the human gut microbiota
Project description:In this study, we quantitated the disappearance of intact HMOs and characterized the glycan digestion products in the gut that are produced by the action of microbial enzymes on HMOs and glycoconjugates from breast milk. Oligosaccharides from fecal samples of exclusively breast-fed infants were extracted and profiled using nanoLC-MS. Intact HMOs were found in the fecal samples, additionally, other oligosaccharides were found corresponding to degraded HMOs and non-HMO based compounds. The latter compounds were fragments of N-glycans released through the cleavage of the linkage to the asparagine residue and through cleavage of the chitobiose core of the N-glycan.
Project description:Breast milk is associated with multiple benefits for the infant, including reduced incidence of chronic diseases such as Inflammatory Bowel Disease. We investigated the role of milk-derived maternal IgA (matIgA) on the developing small intestinal immune system. Using a model, where genotypically identical pups were fed by dams differed only in IgA production we revealed that matIgA regulates the assembly of the infant small intestinal microbiota and epithelium, supporting Lactobacillaceae and suppressing Enterobacteriaceae and the development of secretory lineage cells. Via the microbiota, MatIgA also regulated infant immune cells and suppressed early activation of Th17 cells. We demonstrated that Enterobacteriaceae-specific CD4+ T cells, activated in the absence of matIgA, persisted long term where they may contribute to subsequent inflammatory episodes. This work suggests that maternal IgA shapes the mucosal immune response by regulating the early-life microbiota thus preventing the development of inflammatory microbiota-specific T cells with memory potential.