Project description:Interplay of host microbiota, genetic perturbations, and inflammation promotes local development of intestinal neoplasms in mice [BeadArray]
Project description:Interplay of host microbiota, genetic perturbations, and inflammation promotes local development of intestinal neoplasms in mice [RNA-Seq]
Project description:The preferential localization of some neoplasms, such as serrated polyps, in specific areas of the intestine suggests that non-genetic factors may be important for their development. To test this hypothesis, we took advantage of transgenic mice that expressed HB-EGF throughout the intestine, but develop serrated polyps only in the cecum. Here we show that a host-specific microbiome was associated with serrated polyps, and that alterations of the microbiota induced by antibiotic treatment or by embryo-transfer rederivation markedly inhibited the formation of serrated polyps in the cecum. Mechanistically, development of serrated polyps was associated with a local decrease in epithelial barrier-function, bacterial invasion, production of antimicrobials, and increased expression of several inflammatory factors such as IL-17, Cxcl2, Tnf-α, and IL-1. Increased number of neutrophils were found within the serrated polyps, and their depletion significantly reduced polyp growth. Together these results indicate that non-genetic factors contribute to the development of serrated polyps and suggest that the development of these intestinal neoplasms in the cecum is driven by the interplay between genetic changes in the host, an inflammatory response, and a host-specific microbiota. SUMMARY: Serrated polyps (SP) are a heterogeneous group of neoplasms found in particular areas of the gut. To define the factors contributing to their specific localization, we analyzed a strain of transgenic mice that carry a genetic alteration throughout the intestinal epithelium, but only develop SP in the cecum. Transcriptome and immunostaining analyses showed increased expression of antimicrobial genes, inflammatory factors, and the presence of bacteria within SP. Alteration of the cecal microbiota by antibiotic treatment or by embryo-transfer rederivation dramatically reduced SP incidence. Microbiome analysis implicated a limited set of bacteria in the development of SP. Together, these results point to a crucial role for the microbiota in the localized development of SP in a genetically susceptible host. We obtained serrated polyp (SP) and surrounding normal (NM) tissue from the ceca of three affected mice (paired design) and assessed expression differences by RNA-Seq.
Project description:The preferential localization of some neoplasms, such as serrated polyps, in specific areas of the intestine suggests that non-genetic factors may be important for their development. To test this hypothesis, we took advantage of transgenic mice that expressed HB-EGF throughout the intestine, but develop serrated polyps only in the cecum. Here we show that a host-specific microbiome was associated with serrated polyps, and that alterations of the microbiota induced by antibiotic treatment or by embryo-transfer rederivation markedly inhibited the formation of serrated polyps in the cecum. Mechanistically, development of serrated polyps was associated with a local decrease in epithelial barrier-function, bacterial invasion, production of antimicrobials, and increased expression of several inflammatory factors such as IL-17, Cxcl2, Tnf-M-NM-1, and IL-1. Increased number of neutrophils were found within the serrated polyps, and their depletion significantly reduced polyp growth. Together these results indicate that non-genetic factors contribute to the development of serrated polyps and suggest that the development of these intestinal neoplasms in the cecum is driven by the interplay between genetic changes in the host, an inflammatory response, and a host-specific microbiota. Paired design; Surrounding and SP samples were obtained from the same mouse (n=3; mouse 1, 2, 3)
Project description:Inappropriate cross talk between mammals and their gut microbiota may trigger intestinal inflammation and drive extra-intestinal immune-mediated diseases. Studies with germ-free or gnotobiotic animals represent the gold standard for research on bacterial-host interaction but they are not readily accessible to the wide scientific community. We aimed at refining a protocol that in a robust manner would deplete murine intestinal microbiota and prove to have significant biologic validity. Previously published protocols for depleting mice of their intestinal microbiota by administering broad-spectrum antibiotics in drinking water were difficult to reproduce. We show that twice daily delivery of antibiotics by gavage depleted mice of their cultivable fecal microbiota and reduced the fecal bacterial DNA load by approximately 400 fold while ensuring the animals’ health. Mice subjected to the protocol for 17 days displayed enlarged ceca, reduced Peyer’s patches and small spleens. Antibiotic treatment significantly reduced the expression of antimicrobial factors and altered the expression of 517 genes in total in the colonic epithelium. Genes involved in cell cycle were significantly altered concomitant with reduced epithelial proliferative activity in situ assessed by Ki-67 expression, suggesting that commensal microbiota drives cellular proliferation in colonic epithelium. We present a robust protocol for depleting mice of their cultivatable intestinal microbiota with antibiotics by gavage and show that the biological effect of this depletion is phenotypic characteristics and epithelial gene expression profile similar to those of germ-free mice. Comparison of genome-wide gene expression of colon intestinal epithelial cells from mice subjected to microbiota depletion protocol against to control mice.
Project description:The preferential localization of some neoplasms, such as serrated polyps, in specific areas of the intestine suggests that non-genetic factors may be important for their development. To test this hypothesis, we took advantage of transgenic mice that expressed HB-EGF throughout the intestine, but develop serrated polyps only in the cecum. Here we show that a host-specific microbiome was associated with serrated polyps, and that alterations of the microbiota induced by antibiotic treatment or by embryo-transfer rederivation markedly inhibited the formation of serrated polyps in the cecum. Mechanistically, development of serrated polyps was associated with a local decrease in epithelial barrier-function, bacterial invasion, production of antimicrobials, and increased expression of several inflammatory factors such as IL-17, Cxcl2, Tnf-α, and IL-1. Increased number of neutrophils were found within the serrated polyps, and their depletion significantly reduced polyp growth. Together these results indicate that non-genetic factors contribute to the development of serrated polyps and suggest that the development of these intestinal neoplasms in the cecum is driven by the interplay between genetic changes in the host, an inflammatory response, and a host-specific microbiota.
Project description:The preferential localization of some neoplasms, such as serrated polyps, in specific areas of the intestine suggests that non-genetic factors may be important for their development. To test this hypothesis, we took advantage of transgenic mice that expressed HB-EGF throughout the intestine, but develop serrated polyps only in the cecum. Here we show that a host-specific microbiome was associated with serrated polyps, and that alterations of the microbiota induced by antibiotic treatment or by embryo-transfer rederivation markedly inhibited the formation of serrated polyps in the cecum. Mechanistically, development of serrated polyps was associated with a local decrease in epithelial barrier-function, bacterial invasion, production of antimicrobials, and increased expression of several inflammatory factors such as IL-17, Cxcl2, Tnf-α, and IL-1. Increased number of neutrophils were found within the serrated polyps, and their depletion significantly reduced polyp growth. Together these results indicate that non-genetic factors contribute to the development of serrated polyps and suggest that the development of these intestinal neoplasms in the cecum is driven by the interplay between genetic changes in the host, an inflammatory response, and a host-specific microbiota.
Project description:Intestinal microbial dysbiosis is associated with Crohn’s disease (CD). However, the mechanisms leading to the chronic mucosal inflammation that characterizes this disease remain unclear. To evaluate causality and mechanisms of disease, we conducted a systems level study of the interactions between the gut microbiota and host in new-onset pediatric patients. We report an altered host proteome in CD patients indicative of impaired mitochondrial functions. A downregulation of mitochondrial proteins implicated in H2S detoxification was observed, while the relative abundance of H2S microbial producers was increased. Network correlation analysis identified Atopobium parvulum as the central hub of H2S producers. Gnotobiotic and conventionalized colitis-susceptible interleukin-10-deficient (Il10-/-) mice demonstrated that A. parvulum induced colitis, a phenotype requiring the presence of the intestinal microbiota. Administration of bismuth, a H2S scavenger, prevented A. parvulum-induced colitis in Il10-/- mice. This study identified host-microbiota interactions that are disturbed in CD patients providing mechanistic insights on CD pathogenesis.
Project description:Studying host-microbiota interactions is fundamental to understand mechanisms involved in intestinal inflammation and inflammatory bowel diseases. In this work, we studied these interactions in mice mono-associated with 4 bacteria and 2 yeasts, all representative of intestinal microbiota and/or associated with IBD pathogenesis: Bacteroides thetaiotaomicron, adhesive-invasive Escherichia coli (AIEC), Ruminococcus gnavus, Roseburia intestinalis, Saccharomyces boulardii and Candida albicans. Transcriptomics analyses showed that B. thetaiotaomicron had the highest immunological effect, being able to almost recapitulate the effects of a whole microbiota, and particularly induced Treg pathways. Furthermore, this analysis also pointed out the effects of E. coli AIEC LF82 on IDO activation and of S. boulardii on angiogenesis, as well as major effects of R. gnavus on metabolism. This work therefore reveals information on the role of each micro-organism and proposes several tracks to follow to better understand IBD pathogenesis and identify therapeutic targets 6 mono-associations + 2 controls (germ-free and conventionalized mice), with 5 to 7 mice per group.