Project description:Previously, we showed that dietary heme injured the colonic surface epithelium and induced hyperproliferation by changing the surface to crypt signaling. In this study we investigated whether bacteria play a role in this changed signaling. Dietary heme increased the Bacteroidetes and decreased the Firmicutes in colonic content. This shift was caused by a selective susceptibility of Gram-positive bacteria to the heme cytotoxic fecal waters, which is not observed for Gram-negative bacteria allowing expansion of the Gram-negative community. The increased amount of Gram-negative bacteria increased LPS exposure to colonocytes, however, there is no appreciable immune response detected in the heme-fed mice. There were no signs of sensing of the bacteria by the mucosa, as changes in TLR signaling were not present. This lack of microbe-host cross talk indicated that the changes in microbiota do not play a causal role in the heme-induced hyperproliferation. Mice received control or heme diet for 14 days, whereafter pooled colon samples were analysed on microarrays.
Project description:The colon contains a dense metabolically potent microbiota. The colonic O-glycan-rich mucus has been recognized as a key barrier to prevent microbial intrusion, but how this system forms and functions remains unclear. Here, we discovered that the colon mucus is mainly forged by microbiota-dependent secretion of O-glycosylated Muc2 by goblet cells in the ascending colon, where it seamlessly encapsulates the fecal materials including the microbiota. Deletion of O-glycans in the ascending colon impaired the segregating function of the mucous coating, leading to altered structure and metabolic output of the microbiota, and transcriptional homeostasis of the entire host mucosa. These findings represent a paradigm change of the prevailing model of the colon mucus system and provides new insights into host and microbiota symbiosis.
Project description:The colon contains a dense metabolically potent microbiota. The colonic O-glycan-rich mucus has been recognized as a key barrier to prevent microbial intrusion, but how this system forms and functions remains unclear. Here, we discovered that the colon mucus is mainly forged by microbiota-dependent secretion of O-glycosylated Muc2 by goblet cells in the ascending colon, where it seamlessly encapsulates the fecal materials including the microbiota. Deletion of O-glycans in the ascending colon impaired the segregating function of the mucous coating, leading to altered structure and metabolic output of the microbiota, and transcriptional homeostasis of the entire host mucosa. These findings represent a paradigm change of the prevailing model of the colon mucus system and provides new insights into host and microbiota symbiosis.
Project description:Colon cancer is a major cause of cancer deaths in Western countries and is associated with diets high in red meat. Heme, the iron-porphyrin pigment of red meat, induces cytotoxicity of gut contents which injures surface cells leading to compensatory hyperproliferation of crypt cells. This hyperproliferation results in epithelial hyperplasia which increases the risk of colon cancer. In humans, a high red-meat diet increases Bacteroides spp in feces. Therefore, we simultaneously investigated the effects of dietary heme on colonic microbiota and on the host mucosa of mice. Whole genome microarrays showed that heme injured the colonic surface epithelium and induced hyperproliferation by changing the surface to crypt signaling. Using 16S rRNA phylogenetic microarrays, we investigated whether bacteria play a role in this changed signaling. Heme increased Bacteroidetes and decreased Firmicutes in colonic contents. This shift was most likely caused by a selective susceptibility of Gram-positive bacteria to heme cytotoxic fecal water, which is not observed for Gram-negative bacteria, allowing expansion of the Gram-negative community. The increased amount of Gram-negative bacteria most probably increased LPS exposure to colonocytes, however, there is no appreciable immune response detected in the heme-fed mice. There was no functional change in the sensing of the bacteria by the mucosa, as changes in inflammation pathways and Toll- like receptor signaling were not detected. This unaltered host-microbe cross-talk indicates that the changes in microbiota did not play a causal role in the observed hyperproliferation and hyperplasia. Keywords: Expression profiling by array Mice were fed a Westernized high fat control diet, or the same diet supplemented with 0.5 M-BM-5mol heme/g diet. After 14 days of intervention, mice were killed and gene expression was profiled in colon.
Project description:Overall diet quality and statin therapy are important modulators of inflammation and CAD progression, yet their effects on colon is not well understood. Our objective was to examine the effects and interaction of dietary patterns and statin therapy on colonic mucosa gene expression in the Ossabaw pig.
Project description:Colon cancer is a major cause of cancer deaths in Western countries and is associated with diets high in red meat. Heme, the iron-porphyrin pigment of red meat, induces cytotoxicity of gut contents which injures surface cells leading to compensatory hyperproliferation of crypt cells. This hyperproliferation results in epithelial hyperplasia which increases the risk of colon cancer. In humans, a high red-meat diet increases Bacteroides spp in feces. Therefore, we simultaneously investigated the effects of dietary heme on colonic microbiota and on the host mucosa of mice. Whole genome microarrays showed that heme injured the colonic surface epithelium and induced hyperproliferation by changing the surface to crypt signaling. Using 16S rRNA phylogenetic microarrays, we investigated whether bacteria play a role in this changed signaling. Heme increased Bacteroidetes and decreased Firmicutes in colonic contents. This shift was most likely caused by a selective susceptibility of Gram-positive bacteria to heme cytotoxic fecal water, which is not observed for Gram-negative bacteria, allowing expansion of the Gram-negative community. The increased amount of Gram-negative bacteria most probably increased LPS exposure to colonocytes, however, there is no appreciable immune response detected in the heme-fed mice. There was no functional change in the sensing of the bacteria by the mucosa, as changes in inflammation pathways and Toll- like receptor signaling were not detected. This unaltered host-microbe cross-talk indicates that the changes in microbiota did not play a causal role in the observed hyperproliferation and hyperplasia. Keywords: Expression profiling by array