Project description:Bacteroidaceae are common gut microbiota members in all warm-blooded animals. However, if Bacteroidaceae are to be used as probiotics, the species selected for different hosts should reflect the natural distribution. In this study, we therefore evaluated host adaptation of bacterial species belonging to the family Bacteroidaceae. B. dorei, B. uniformis, B. xylanisolvens, B. ovatus, B. clarus, B. thetaiotaomicron and B. vulgatus represented human-adapted species while B. gallinaceum, B. caecigallinarum, B. mediterraneensis, B. caecicola, M. massiliensis, B. plebeius and B. coprocola were commonly detected in chicken but not human gut microbiota. There were 29 genes which were present in all human-adapted Bacteroides but absent from the genomes of all chicken isolates and these included genes required for the pentose cycle, and glutamate or histidine metabolism. These genes were expressed during an in vitro competitive assay, in which human-adapted Bacteroides species overgrew the chicken adapted isolates. Not a single gene specific for the chicken-adapted species was found. Instead, chicken adapted species exhibited signs of frequent horizontal gene transfer, of KUP, linA and sugE genes in particular. The differences in host adaptation should be considered when the new generation of probiotics for humans or chickens is designed.
Project description:Microbiota-induced cytokine responses participate in gut homeostasis, but the cytokine balance at steady-state and the role of individual bacterial species in setting the balance remain elusive. Using gnotobiotic mouse models, we provide a systematic analysis of the role of microbiota in the induction of cytokine responses in the normal intestine. Colonization by a whole mouse microbiota orchestrated a broad spectrum of pro-inflammatory (Th1, Th17) and regulatory T cell responses. Unexpectedly, most tested complex microbiota and individual bacteria failed to efficiently stimulate intestinal cytokine responses. A potent cytokine-inducing function was however associated with non-culturable host-specific species, the prototype of which was the Clostridia-related Segmented Filamentous Bacterium, and this bacterial species recapitulated the coordinated maturation of T cell responses induced by the whole mouse microbiota. Our study demonstrates the non-redundant role of microbiota members in the regulation of gut immune homeostasis.
Project description:Germ-free (GF) animal models represent a unique tool to study the function and impact of gut microbiota on the host under homeostatic or pathologic conditions. GF animals can be selectively colonized with specific microorganisms of interest or even microbial communities. Therefore, these models are frequently employed to decipher complex interactions between the host and its endogenous commensal microbiota, as well as to study interrelations between microbial species within the specific biotope such as intestine.
Project description:Here, we report analysis of both the bacterial and host transcriptome as affected by colonization of R. hominis in the mouse gut. Microbial genes required for colonization and adaptation in the murine gut, as well as host genes responding to colonization by this bacterial species, were uncovered.
Project description:Chronic diseases arise when pathophysiological processes achieve a steady state by self-reinforcing. Here, we explored the possibility of a self-reinforcement state in a common condition, chronic constipation, where alterations of the gut microbiota have been reported. The functional impact of the microbiota shifts on host physiology remains unclear, however we hypothesized that microbial communities adapted to slow gastrointestinal transit affect host functions in a way that reinforces altered transit, thereby maintaining the advantage for microbial self-selection. To test this, we examined the impact of pharmacologically (loperamide)-induced constipation (PIC) on the structural and functional profile of altered gut microbiota. PIC promoted changes in the gut microbiome, characterized by decreased representation of butyrate-producing Clostridiales, decreased cecal butyrate concentration and altered metabolic profiles of gut microbiota. PIC-associated gut microbiota also impacted colonic gene expression, suggesting this might be a basis for decreased gastrointestinal (GI) motor function. Introduction of PIC-associated cecal microbiota into germ-free (GF) mice significantly decreased GI transit time. Our findings therefore support the concept that chronic diseases like constipation are caused by disease-associated steady states, in this case, caused by reciprocating reinforcement of pathophysiological factors in host-microbe interactions. We used microarrays to detail the global gene expression profile in the proximal colon smooth muscle tissues of germ-free, conventionalized, or specific pathogen free mouse C57Bl/6 female and male specific pathogen free (SPF) mice were bred and housed in the animal care facility at the University of Chicago. Mice of 8–10 weeks of age were treated with 0.1% loperamide in the drinking water for 7 days. Age matched, germ-free (GF) C57Bl/6 mice were gavaged orally with cecal luminal contents harvested from control or loperamide-treated C57Bl/6 donor mice. Recipient mice were sacrificed 4 weeks post-colonization.
Project description:Background and aims. The etiopathology of inflammatory bowel diseases is still poorly understood. To date, only few little data are available on the microbiota composition in ulcerative colitis (UC), representing a major subform of inflammatory bowel diseases. Currently, one of the main challenges is to unravel the interactions between genetics and environmental factors in the onset or during the progression and maintenance of the disease. The aim of the present study was to analyse twin pairs discordant for UC for both gut microbiota dysbiosis and host expression profiles at a mucosal level and to get insight into the functional genomic crosstalk between microbiota and mucosal epithelium in vivo. Methods. Biopsies were sampled from the sigmoid colon of both healthy and diseased siblings from UC discordant twin pairs but also from healthy twins. Microbiota profiles were assessed by 16S rDNA libraries while mRNA expression profiles were analysed from the same volunteers using Affymetrix microarrays. Results. UC patients showed a dysbiotic microbiota with lower diversity and more species belonging to Actinobacteria and Proteobacteria phyla. On the contrary, their healthy siblingsM-bM-^@M-^Y microbiota contained more bacteria from the Lachnospiracea and Ruminococcaceae family than did healthy individuals . Sixty-three host transcripts significantly correlated with bacterial genera in healthy individuals whereas only 43 and 32 correlated with bacteria in healthy and UC siblings from discordant pairs, respectively. Several transcripts related to oxidative and immune responses were differentially expressed between unaffected and UC siblings. Conclusion. A loss of crosstalk between gut microbiota and host was highlighted in UC patients. This defect was also striking in healthy siblings from discordant pairs, as was the lower biodiversity within the microbiota. Our results suggest disease-relevant interactions between host transcriptome and microbiota. Moreover, unusual aerobic bacteria were noticed in UC mucosal microbiota, whereas healthy siblings from discordant pairs had higher percentages of potentially beneficialusual commensal bacterial species. Paired samples (twins) were analyzed to obtain data independent of genetic variation
Project description:Gut microbiota and the circadian clock are both key regulators of the metabolic processes. Although recent evidence points to the impact of the circadian clock on microbiota, gut microbiota effect on diurnal host gene expression remains elusive. A transcriptome analysis of germ-free mice reveals subtle changes in circadian clock gene expression. However, a lack of microbiome leads to liver feminization and alters the expression of male-specific genes involved in lipid metabolism and xenobiotic detoxification associated with sustained activation of the Growth Hormone pathway. These results emphasize the mutual interaction of gut microbiota and its host even on unexpected functions.
Project description:Gut microbiota and the circadian clock are both key regulators of the metabolic processes. Although recent evidence points to the impact of the circadian clock on microbiota, gut microbiota effect on diurnal host gene expression remains elusive. A transcriptome analysis of germ-free mice reveals subtle changes in circadian clock gene expression. However, a lack of microbiome leads to liver feminization and alters the expression of male-specific genes involved in lipid metabolism and xenobiotic detoxification associated with sustained activation of the Growth Hormone pathway. These results emphasize the mutual interaction of gut microbiota and its host even on unexpected functions.
Project description:Gut microbiota and the circadian clock are both key regulators of the metabolic processes. Although recent evidence points to the impact of the circadian clock on microbiota, gut microbiota effect on diurnal host gene expression remains elusive. A transcriptome analysis of germ-free mice reveals subtle changes in circadian clock gene expression. However, a lack of microbiome leads to liver feminization and alters the expression of male-specific genes involved in lipid metabolism and xenobiotic detoxification associated with sustained activation of the Growth Hormone pathway. These results emphasize the mutual interaction of gut microbiota and its host even on unexpected functions.
Project description:Gut microbiota and the circadian clock are both key regulators of the metabolic processes. Although recent evidence points to the impact of the circadian clock on microbiota, gut microbiota effect on diurnal host gene expression remains elusive. A transcriptome analysis of germ-free mice reveals subtle changes in circadian clock gene expression. However, a lack of microbiome leads to liver feminization and alters the expression of male-specific genes involved in lipid metabolism and xenobiotic detoxification associated with sustained activation of the Growth Hormone pathway. These results emphasize the mutual interaction of gut microbiota and its host even on unexpected functions.