Metabolomics,Unknown,Transcriptomics,Genomics,Proteomics

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High-fat diet-mediated dysbiosis promotes intestinal carcinogenesis independent of obesity

ABSTRACT: Several aspects common to a Western lifestyle, including obesity and decreased physical activity, are known risks for gastrointestinal cancers. There is an increasing amount of evidence suggesting that diet profoundly affects the composition of the intestinal microbiota. Moreover, there is now unequivocal evidence linking a dysbiotic gut to cancer development. Yet, the mechanisms through which high-fat diet (HFD)-mediated changes in the microbial community impact the severity of tumorigenesis in the gut, remain to be determined. Here we demonstrate that HFD promotes tumor progression in the small intestine of genetically susceptible K-rasG12Dint mice independent of obesity. HFD consumption in conjunction with K-Ras mutation mediates a shift in the composition of gut microbiota, which is associated with a decrease in Paneth cell antimicrobial host defense that compromises dendritic cell (DC) recruitment and MHC-II presentation in the gut-associated lymphoid tissues (GALTs). DC recruitment in GALTs can be normalized, and tumor progression attenuated completely, when K-rasG12Dint mice are supplemented with the short-chain fatty acid butyrate, a bacterial fermentation endproduct. Importantly, Myd88-deficiency completely blocks tumor progression in K-rasG12Dint mice. Transfer of fecal samples from diseased donors into healthy adult K-rasG12Dint mice is sufficient to transmit disease in the absence of HFD. Furthermore, treatment with antibiotics completely blocks HFD-induced tumor progression, suggesting a pivotal role for distinct microbial shifts in aggravating disease in the small intestine. Collectively, these data underscore the importance of the reciprocal interaction between host and environmental factors in selecting intestinal microbiota that favor carcinogenesis, and suggest tumorigenesis may be transmissible among genetically predisposed individuals. 3 mice each for each treatment.

ORGANISM(S): Mus musculus

SUBMITTER: Claudia Pommerenke

PROVIDER: E-GEOD-56257 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Project description:Several aspects of a Western lifestyle such as increased obesity and decreased physical activity are associated with increased risk for gastrointestinal cancers1. Although high-fat diet (HFD) induced low-grade inflammation has been closely linked to tumorigenesis2, however, the microbial shift that occurs due to diet and consequent alterations in host immunity have merely been considered to play a critical role during carcinogenesis. Here we show that HFD promotes tumor progression in the small intestine of genetically susceptible mice, however, independently of obesity and diet-induced chronic inflammation. HFD consumption cooperates with mutant K-Ras to mediate a shift in the composition of microbiota, which is associated with a decrease in Paneth cell antimicrobial host defense that compromises dendritic cell (DC) recruitment and MHCII presentation in the gut-associated lymphoid tissues (GALTs). DC recruitment in GALTs can be normalized and tumor progression attenuated completely when K-Ras mutant mice are supplemented with the short chain fatty acid butyrate, a bacterial fermentation end product, or partially when provided with probiotics. Importantly, Myd88-deficiency completely blocks tumor progression in K-ras mutants, however, rather by substantial changes in the microbiota than host-mediated signaling mechanisms. Strikingly, transfer of fecal samples from diseased donors into healthy adult K-ras mutants is sufficient to enhance tumor progression in the absence of HFD suggesting a pivotal role for distinct microbiota shifts in aggravating disease in the small intestine. Collectively, these data underscore the reciprocal interaction between host and environmental factors for the composition of intestinal microbiota that favors carcinogenesis and suggest tumor progression could potentially be “transmitted” in genetically predisposed individuals. 13 samples; S103_396_GroupA_Arkan and S104_429_GroupA_Arkan represent the controls of the first group, S105_394_GroupB_Arkan and S106_429_GroupB_Arkan represent ViRas (mutated) mice of the first group. S982_groupA_ 1 and S983_groupA_2 represent the cotrols of the second group, S984_groupB_3, S985_groupB_4 and S986_groupB_5 represent ViRas (mutant) mice of the second group, S563_CO1979 represent the control of the third group, S564_KO1_1231, S565_KO2_1984 and S566_KO3_2013 represent the ViRas (mutant) mice of the third group. The first group are mice kept on HFD, second group kept on ND and third group kept on HFD plus treated with butyrate

Project description:The mammalian gut harbors a diverse microbial community (gut microbiota) that mainly consists of bacteria. Their combined genomes (the microbiome) provide biochemical and metabolic functions that complement host physiology. Maintaining symbiosis seems to be a key requirement for health as dysbiosis is associated with the development of common diseases. Previous studies indicated that the microbiota and the hostM-bM-^@M-^Ys epithelium signal bidirectional inducing transcriptional responses to fine-tune and maintain symbiosis. However, little is known about the hostM-bM-^@M-^Ys responses to the microbiota along the length of the gut as earlier studies of gut microbial ecology mostly used either colonic or fecal samples. This is of importance as not only function and architecture of the gut varies along its length but also microbial distribution and diversity. Few recent studies have begun to investigate microbiota-induced host responses along the length of the gut. However, these reports used whole tissue samples and therefore do not allow drawing conclusions about specificity of the observed responses. Which cells in the intestinal tissue are responsible for the microbially induced response: epithelial, mesenchymal or immune cells? Where are the responding cells located? We used using extensive microarray analysis of laser capture microdissection (LCM) harvested ileal and colonic tip and crypt fractions from germ-free and conventionally-raised mice to investigate the microbiota-induced transcriptional responses in specific and well-defined cell populations of the hostM-bM-^@M-^Ys epithelium. Ileum and colon segments were dissected from germ-free and conventionally-raised 10-12 weeks old female C57Bl/6 mice, washed and frozen as OCT blocks. Cryosections were prepared from these OCT blocks and tip/crypt fractions isolated using laser capture microdissection. To investigate the microbiota-induced transcriptional responses specific for specific subpopulations of intestinal epithelial cells, tip and crypt fractions of ileal and colonic epithelium of germ-free and conventionally-raised 10-12 weeks old female C57Bl/6 mice were harvested using laser capture microdissection and probed in an extensive microarray analysis.

Project description:The mammalian gut harbors a diverse microbial community (gut microbiota) that mainly consists of bacteria. Their combined genomes (the microbiome) provide biochemical and metabolic functions that complement host physiology. Maintaining symbiosis seems to be a key requirement for health as dysbiosis is associated with the development of common diseases. Previous studies indicated that the microbiota and the hostM-bM-^@M-^Ys epithelium signal bidirectional inducing transcriptional responses to fine-tune and maintain symbiosis. However, little is known about the hostM-bM-^@M-^Ys responses to the microbiota along the length of the gut as earlier studies of gut microbial ecology mostly used either colonic or fecal samples. This is of importance as not only function and architecture of the gut varies along its length but also microbial distribution and diversity. Few recent studies have begun to investigate microbiota-induced host responses along the length of the gut. However, these reports used whole tissue samples and therefore do not allow drawing conclusions about specificity of the observed responses. Which cells in the intestinal tissue are responsible for the microbially induced response: epithelial, mesenchymal or immune cells? Where are the responding cells located? Furthermore, the gut microbiota has been implicated in epigenetic regulation of the hostM-bM-^@M-^Ys transcriptional profile. We used using extensive microarray analysis of laser capture microdissection (LCM) harvested ileal and colonic tip and crypt fractions from germ-free mice before and during the time course of colonization with a normal microbiota (on days 1, 3, 5 and 7) to investigate the microbiota-induced transcriptional responses and their kinetics in specific and well-defined cell populations of the hostM-bM-^@M-^Ys epithelium. Ileum and colon segments were dissected from germ-free 10-12 weeks old female C57Bl/6 mice and on day 1, 3, 5 and 7 after colonization, washed and frozen as OCT blocks. Cryosections were prepared from these OCT blocks and tip/crypt fractions isolated using laser capture microdissection. To investigate the microbiota-induced transcriptional responses specific for specific subpopulations of intestinal epithelial cells and their kinetics, tip and crypt fractions of ileal and colonic epithelium of germ-free 10-12 weeks old female C57Bl/6 mice before and during the time course of colonization with a normal microbiota (on days 1, 3, 5 and 7) were harvested using laser capture microdissection and probed in an extensive microarray analysis.

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High-fat diet-mediated dysbiosis promotes intestinal carcinogenesis independent of obesity

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