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:Human activity is altering the environment at a rapid pace, challenging the adaptive capacities of genetic variation within animal populations. Animals also harbor extensive gut microbiomes, which play diverse roles in host health and fitness and may help expanding host capabilities. The unprecedented scale of human usage of xenobiotics and contamination with environmental toxins describes one challenge against which bacteria with their immense biochemical diversity are particularly suited to offer solutions. To explore the paths leading to bacteria-assisted rapid adaptation, we used Caenorhabditis elegans harboring a defined microbiome, and the antibiotic neomycin as a model toxin, harmful for the worm host and neutralized to different extents by microbiome members. Worms exposed to neomycin showed delayed development and decreased survival but were protected when colonized by neomycin-resistant members of the microbiome. Through a combination of 16S gene sequencing, counting of live bacteria and behavioral assays we identified two distinct mechanisms that facilitated adaptation: gut enrichment for a neomycin-modifying strain driven by altered bacterial competition; and host avoidance behavior, which depended on the stress-activated KGB-1/JNK and enabled preference of neomycin-protective bacteria. The straightforwardness of these mechanisms suggests that bacteria-assisted host adaptation may be more common than currently appreciated, protecting animals from novel stressors. However, gut remodeling may also cause dysbiosis, and additional experiments identified fitness trade-offs including increased susceptibility to infection as well as metabolic remodeling. Extending these results to other toxins suggests yet unaccounted-for microbiome-dependent long-term consequences of toxin exposure.
Project description:During weaning, the shift from milk to solid food is accompanied by a rapid expansion and diversification of the gut microbiome. This triggers the weaning reaction, a programmed immune response important for long-lasting mucosal immunity that is poorly understood. Here, we characterize the impact of the gut microbiome on the DNA methylome and transcriptome of intestinal stem cells (ISCs) from weaning to young adulthood in mice. We identify a weaning- IFN-g-TET3 axis that reprograms epithelial MHC-II signaling via enhancer demethylation in ISCs, establishing a lasting transcriptional memory into adulthood. Disruption of this axis by IFN-g blockade or low-dose penicillin attenuates the microbiota-mediated epigenetic control of epithelial MHC-II signaling, leading to impaired mucosal immunity. By engaging immune crosstalk and metabolite production, the weaning microbiome drives epigenetic reprogramming, thereby establishing a microbiome-induced regulatory pathway that couples developmental cues to lifelong epithelial immune resilience.
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
Project description:During weaning, the transition to solid food diversifies the gut microbiome, triggering a programmed immune response critical for long-lasting mucosal immunity. Previous work showed that the gut microbiome mediates epigenetic development in intestinal stem cells (ISCs) during suckling, but what happens during weaning is unclear. Here, using genome-wide methylation profiling revealed that weaning-driven microbiome changes shape the DNA methylome and transcriptome of murine ISCs in an IFN-g dependent manner. Specifically, we observe demethylation of enhancer elements essential for MHC class II genes, which result in a transcriptional memory that persists through differentiation into adulthood. IFN-g blockade, or low-dose penicillin to target Gram-positive bacteria, in early life impaired microbiome-mediated epigenetic control and mucosal immunity, and exacerbated colitis. Murine organoids primed with IFN-g showed rapid, amplified transcriptional responses upon secondary stimulations. These findings reveal that early-life events alter the gut microbiome and these changes reprogram ISC epigenetic memory to shape mucosal immunity.
Project description:The gut microbiome is significantly altered in inflammatory bowel diseases, but the basis of these changes is not well understood. We have combined metagenomic and metatranscriptomic profiling of the gut microbiome to assess changes to both bacterial community structure and transcriptional activity in a mouse model of colitis. Gene families involved in microbial resistance to oxidative stress, including Dps/ferritin, Fe-dependent peroxidase and glutathione S-transferase, were transcriptionally up-regulated in colitis, implicating a role for increased oxygen tension in gut microbiota modulation. Transcriptional profiling of the host gut tissue and host RNA in the gut lumen revealed a marked increase in the transcription of genes with an activated macrophage and granulocyte signature, suggesting the involvement of these cell types in influencing microbial gene expression. Down-regulation of host glycosylation genes further supports a role for inflammation-driven changes to the gut niche that may impact the microbiome. We propose that members of the bacterial community react to inflammation-associated increased oxygen tension by inducing genes involved in oxidative stress resistance. Furthermore, correlated transcriptional responses between host glycosylation and bacterial glycan utilisation support a role for altered usage of host-derived carbohydrates in colitis. Complementary transcription profiling data from the mouse hosts have also been deposited at ArrayExpress under accession number E-MTAB-3590 ( http://www.ebi.ac.uk/arrayexpress/experiments/E-MTAB-3590/ ).
Project description:Preterm infants born <32 weeks gestation have abnormal microbial colonisation and dysregulated inflammation within the gut. Preterm infant-derived intestinal organoids (PIOs) represent a valuable model for investigating gut microbiome-host interactions and inflammatory responses. We optimised an inflammation model in PIO monolayers incubated within an anaerobic co-culture system that recreates the physiological oxygen gradient of the intestinal epithelium. We trialled multiple stimuli, including live and heat-killed pathobiont consortia, lipopolysaccharide (LPS) and flagellin. We found that a combination of apical LPS and basolateral flagellin, incubated for 3 hours, elicited the most robust response. This was characterised by enhanced pro-inflammatory cytokine secretion, the potential for chemokine-driven immune recruitment, TNFα and IL17C pathway signalling, shifts from NF-κB to AP-1-mediated responses, and signs of tissue remodelling. This provides a framework for appropriate study design to disentangle the impacts of microbiome-host interactions in health and disease using intestinal organoids.
Project description:Preterm infants born <32 weeks gestation have abnormal microbial colonisation and dysregulated inflammation within the gut. Preterm infant-derived intestinal organoids (PIOs) represent a valuable model for investigating gut microbiome-host interactions and inflammatory responses. We optimised an inflammation model in PIO monolayers incubated within an anaerobic co-culture system that recreates the physiological oxygen gradient of the intestinal epithelium. We trialled multiple stimuli, including live and heat-killed pathobiont consortia, lipopolysaccharide (LPS) and flagellin. We found that a combination of apical LPS and basolateral flagellin, incubated for 3 hours, elicited the most robust response. This was characterised by enhanced pro-inflammatory cytokine secretion, the potential for chemokine-driven immune recruitment, TNFα and IL17C pathway signalling, shifts from NF-κB to AP-1-mediated responses, and signs of tissue remodelling. This provides a framework for appropriate study design to disentangle the impacts of microbiome-host interactions in health and disease using intestinal organoids.