Glucosylceramide production maintains colon integrity in response to Bacteroides fragilis toxin-induced colon epithelial cell signaling.
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ABSTRACT:
SUBMITTER: Patterson L
PROVIDER: S-EPMC8140605 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:The Bacteroides fragilis (B. fragilis) produce biofilm for colonisation in the intestinal tract can cause a series of inflammatory reactions due to B. fragilis toxin (BFT) which can lead to chronic intestinal inflammation and tissue injury and play a crucial role leading to colorectal cancer (CRC). The enterotoxigenic B. fragilis (ETBF) forms biofilm and produce toxin and play a role in CRC, whereas the non-toxigenic B. fragilis (NTBF) does not produce toxin. The ETBF triggers the expression of cyclooxygenase (COX)-2 that releases PGE2 for inducing inflammation and control cell proliferation. From chronic intestinal inflammation to cancer development, it involves signal transducers and activators of transcription (STAT)3 activation. STAT3 activates by the interaction between epithelial cells and BFT. Thus, regulatory T-cell (Tregs) will activates and reduce interleukin (IL)-2 amount. As the level of IL-2 drops, T-helper (Th17) cells are generated leading to increase in IL-17 levels. IL-17 is implicated in early intestinal inflammation and promotes cancer cell survival and proliferation and consequently triggers IL-6 production that activate STAT3 pathway. Additionally, BFT degrades E-cadherin, hence alteration of signalling pathways can upregulate spermine oxidase leading to cell morphology and promote carcinogenesis and irreversible DNA damage. Patient with familial adenomatous polyposis (FAP) disease displays a high level of tumour load in the colon. This disease is caused by germline mutation of the adenomatous polyposis coli (APC) gene that increases bacterial adherence to the mucosa layer. Mutated-APC gene genotype with ETBF increases the chances of CRC development. Therefore, the colonisation of the ETBF in the intestinal tract depicts tumour aetiology can result in risk of hostility and effect on human health.
| S-EPMC7444842 | biostudies-literature
Project description:Enterotoxigenic Bacteroides fragilis (ETBF) is a Gram-negative, obligate anaerobe member of the gut microbial community in up to 40% of healthy individuals. This bacterium is found more frequently in people with colorectal cancer (CRC) and causes tumor formation in the distal colon of multiple intestinal neoplasia (Apcmin/+ ) mice; tumor formation is dependent on ETBF-secreted Bacteroides fragilis toxin (BFT). Because of the extensive data connecting alterations in the epigenome with tumor formation, initial experiments attempting to connect BFT-induced tumor formation with methylation in colon epithelial cells (CECs) have been performed, but the effect of BFT on other epigenetic processes, such as chromatin structure, remains unexplored. Here, the changes in gene expression (transcriptome sequencing [RNA-seq]) and chromatin accessibility (assay for transposase-accessible chromatin using sequencing) induced by treatment of HT29/C1 cells with BFT for 24 and 48 h were examined. Our data show that several genes are differentially expressed after BFT treatment and that these changes relate to the interaction between bacteria and CECs. Further, sites of increased chromatin accessibility are associated with the location of enhancers in CECs and the binding sites of transcription factors in the AP-1/ATF family; they are also enriched for common differentially methylated regions (DMRs) in CRC. These data provide insight into the mechanisms by which BFT induces tumor formation and lay the groundwork for future in vivo studies to explore the impact of BFT on nuclear structure and function.
| S-EPMC6529667 | biostudies-literature
Project description:BackgroundEnterotoxigenic Bacteroides fragilis (ETBF) produces the Bacteroides fragilis toxin, which has been associated with acute diarrheal disease, inflammatory bowel disease, and colorectal cancer (CRC). ETBF induces colon carcinogenesis in experimental models. Previous human studies have demonstrated frequent asymptomatic fecal colonization with ETBF, but no study has investigated mucosal colonization that is expected to impact colon carcinogenesis.MethodsWe compared the presence of the bft gene in mucosal samples from colorectal neoplasia patients (cases, n = 49) to a control group undergoing outpatient colonoscopy for CRC screening or diagnostic workup (controls, n = 49). Single bacterial colonies isolated anaerobically from mucosal colon tissue were tested for the bft gene with touch-down polymerase chain reaction.ResultsThe mucosa of cases was significantly more often bft-positive on left (85.7%) and right (91.7%) tumor and/or paired normal tissues compared with left and right control biopsies (53.1%; P = .033 and 55.5%; P = .04, respectively). Detection of bft was concordant in most paired mucosal samples from individual cases or controls (75% cases; 67% controls). There was a trend toward increased bft positivity in mucosa from late- vs early-stage CRC patients (100% vs 72.7%, respectively; P = .093). In contrast to ETBF diarrheal disease where bft-1 detection dominates, bft-2 was the most frequent toxin isotype identified in both cases and controls, whereas multiple bft isotypes were detected more frequently in cases (P ? .02).ConclusionsThe bft gene is associated with colorectal neoplasia, especially in late-stage CRC. Our results suggest that mucosal bft exposure is common and may be a risk factor for developing CRC.
| S-EPMC4351371 | biostudies-literature
Project description:Enterotoxigenic Bacteroides fragilis - organisms that live in the colon - secrete a metalloprotease toxin, B. fragilis toxin. This toxin binds to a specific intestinal epithelial cell receptor and stimulates cell proliferation, which is dependent, in part, on E-cadherin degradation and beta-catenin-T-cell-factor nuclear signaling. Gamma-secretase (or presenilin-1) is an intramembrane cleaving protease and is a positive regulator of E-cadherin cleavage and a negative regulator of beta-catenin signaling. Here we examine the mechanistic details of toxin-initiated E-cadherin cleavage. B. fragilis toxin stimulated shedding of cell membrane proteins, including the 80 kDa E-cadherin ectodomain. Shedding of this domain required biologically active toxin and was not mediated by MMP-7, ADAM10 or ADAM17. Inhibition of gamma-secretase blocked toxin-induced proteolysis of the 33 kDa intracellular E-cadherin domain causing cell membrane retention of a distinct beta-catenin pool without diminishing toxin-induced cell proliferation. Unexpectedly, gamma-secretase positively regulated basal cell proliferation dependent on the beta-catenin-T-cell-factor complex. We conclude that toxin induces step-wise cleavage of E-cadherin, which is dependent on toxin metalloprotease and gamma-secretase. Our results suggest that differentially regulated beta-catenin pools associate with the E-cadherin-gamma-secretase adherens junction complex; one pool regulated by gamma-secretase is important to intestinal epithelial cell homeostasis.
| S-EPMC3056613 | biostudies-literature
Project description:Pro-carcinogenic bacteria have the potential to initiate and/or promote colon cancer, in part via immune mechanisms that are incompletely understood. Using ApcMin mice colonized with the human pathobiont enterotoxigenic Bacteroides fragilis (ETBF) as a model of microbe-induced colon tumorigenesis, we show that the Bacteroides fragilis toxin (BFT) triggers a pro-carcinogenic, multi-step inflammatory cascade requiring IL-17R, NF-κB, and Stat3 signaling in colonic epithelial cells (CECs). Although necessary, Stat3 activation in CECs is not sufficient to trigger ETBF colon tumorigenesis. Notably, IL-17-dependent NF-κB activation in CECs induces a proximal to distal mucosal gradient of C-X-C chemokines, including CXCL1, that mediates the recruitment of CXCR2-expressing polymorphonuclear immature myeloid cells with parallel onset of ETBF-mediated distal colon tumorigenesis. Thus, BFT induces a pro-carcinogenic signaling relay from the CEC to a mucosal Th17 response that results in selective NF-κB activation in distal colon CECs, which collectively triggers myeloid-cell-dependent distal colon tumorigenesis.
| S-EPMC5954996 | biostudies-literature
Project description:This SuperSeries is composed of the SubSeries listed below.
2018-04-18 | GSE113220 | GEO
Project description:Disruption of epithelial barriers is a common disease manifestation in chronic degenerative diseases of the airways, lung, and intestine. Extensive human genetic studies have identified risk loci in such diseases, including in chronic obstructive pulmonary disease (COPD) and inflammatory bowel diseases. The genes associated with these loci have not fully been determined, and functional characterization of such genes requires extensive studies in model organisms. Here, we report the results of a screen in Drosophila melanogaster that allowed for rapid identification, validation, and prioritization of COPD risk genes that were selected based on risk loci identified in human genome-wide association studies (GWAS). Using intestinal barrier dysfunction in flies as a readout, our results validate the impact of candidate gene perturbations on epithelial barrier function in 56% of the cases, resulting in a prioritized target gene list. We further report the functional characterization in flies of one family of these genes, encoding for nicotinic acetylcholine receptor (nAchR) subunits. We find that nAchR signaling in enterocytes of the fly gut promotes epithelial barrier function and epithelial homeostasis by regulating the production of the peritrophic matrix. Our findings identify COPD-associated genes critical for epithelial barrier maintenance, and provide insight into the role of epithelial nAchR signaling for homeostasis.
| S-EPMC10764009 | biostudies-literature
Project description:It is estimated that the etiology of 20-30% of epithelial cancers is directly associated with inflammation, although the direct molecular events linking inflammation and carcinogenesis are poorly defined. In the context of gastrointestinal disease, the bacterium enterotoxigenic Bacteroides fragilis (ETBF) is a significant source of chronic inflammation and has been implicated as a risk factor for colorectal cancer. Spermine oxidase (SMO) is a polyamine catabolic enzyme that is highly inducible by inflammatory stimuli resulting in increased reactive oxygen species (ROS) and DNA damage. We now demonstrate that purified B. fragilis toxin (BFT) up-regulates SMO in HT29/c1 and T84 colonic epithelial cells, resulting in SMO-dependent generation of ROS and induction of ?-H2A.x, a marker of DNA damage. Further, ETBF-induced colitis in C57BL/6 mice is associated with increased SMO expression and treatment of mice with an inhibitor of polyamine catabolism, N(1),N(4)-bis(2,3-butandienyl)-1,4-butanediamine (MDL 72527), significantly reduces ETBF-induced chronic inflammation and proliferation. Most importantly, in the multiple intestinal neoplasia (Min) mouse model, treatment with MDL 72527 reduces ETBF-induced colon tumorigenesis by 69% (P < 0.001). The results of these studies indicate that SMO is a source of bacteria-induced ROS directly associated with tumorigenesis and could serve as a unique target for chemoprevention.
| S-EPMC3174648 | biostudies-literature
Project description:Purpose: The goal of this study is to determine how BFT2 alters chromatin accessibility at relatively early time points in colon epithelial cells, and to correlate the changes in chromatin accessibility with changes in gene expression, transcription factor binding sites, and the location of common single nucleotide variants (SNVs) and differentially methylated regions (DMRs) in colorectal cancer. Methods: HT29/C1 cells were plated at low density and allowed to grow for 4 days at 37C and 10% CO2. Afterwards, cells were either left untreated or treated with 100ng/mL BFT2 for 24 or 48 hours. After the specified time point, cells were counted and DNA was collected in order to prepare ATAC-seq libraries. ATAC-seq library was prepared as outlined by Buenrostro et al. (2013). The 4nM pooled ATAC-seq library was sequenced using the Illumina HiSeq. For each sample, three biological replicates were sequenced. After sequencing, the data was analyzed using the pipeline developed by the Kundaje lab, as outlined on ENCODE (Lee et al., 2016). Briefly, reads were trimmed, aligned and filtered using Bowtie2, and peaks were called using MACS2. The three replicate peak files were combined in order to create one consensus file for each treatment condition using an irreproducible discovery rate (IDR) threshold of 0.1. For all analyses, the “optimal set” consensus file was used. Results: Our data show that several genes are differentially expressed after BFT treatment and these changes correlate with changes in chromatin accessibility. This correlation is mediated by an increase in chromatin accessibility at particular transcription factor binding sites. Also, sites of increased chromatin accessibility are associated with a lower frequency of common single nucleotide variants (SNVs) in CRC and with a higher frequency of common differentially methylated regions (DMRs) in CRC. Conclusions: This study adds critical knowledge to our understanding of host-microbe interactions in the gut. While scientists have begun to analyze the effect of specific bacteria on the epigenome of colon epithelial cells, to date, no other studies have surveyed the effect of a specific bacterial toxin on chromatin accessibility in colon epithelial cells. We conclude that BFT2 alters chromatin accessibility in colon epithelial cells, and that these changes correlate with subsequent changes in gene expression. Also, sites of BFT2-induced increased chromatin accessibility are associated with a lower frequency of common single nucleotide variants (SNVs) in CRC and with a higher frequency of common differentially methylated regions (DMRs) in CRC.
2018-04-18 | GSE113219 | GEO
Project description:Purpose: The goal of this study is to determine how BFT2 alters chromatin accessibility at relatively early time points in colon epithelial cells, and to correlate the changes in chromatin accessibility with changes in gene expression, transcription factor binding sites, and the location of common single nucleotide variants (SNVs) and differentially methylated regions (DMRs) in colorectal cancer. Methods: HT29/C1 cells were plated at low density and allowed to grow for 4 days at 37C and 10% CO2. Afterwards, cells were either left untreated or treated with 100ng/mL BFT2 for 24 or 48 hours. After the specified time point, cells were counted and RNA was collected in order to prepare RNA-seq libraries. RNA was collected using the Qiagen RNeasy mini kit. mRNA was enriched using the NEBNext Poly(A) mRNA Magnetic Isolation Module. Afterwards, a non-directional RNA-seq library was constructed using the NEBnext Ultra RNA Library Prep kit from Illumina. The 2nM pooled RNA-seq library was sequenced using the Illumina HiSeq. Results: After sequencing, Kallisto was used to perform pseudoalignment of the raw RNA-seq data. Then, Sleuth was used to quantify gene expression and perform differential expression analyses. After treatment with BFT2 for 24 hours, 70 genes were differentially expressed (P-value < 0.01). Of these genes, 41 showed a decrease in gene expression, while 29 showed an increase in gene expression. After BFT2 treatment for 48 hours, we found only 16 differentially expressed genes (P-value < 0.01); 3 showed a decrease in gene expression and 13 showed an increase in gene expression. Conclusions: This study adds critical knowledge to our understanding of host-microbe interactions in the gut. While scientists have begun to analyze the effect of specific bacteria on the epigenome of colon epithelial cells, to date, no other studies have surveyed the effect of a specific bacterial toxin on chromatin accessibility in colon epithelial cells. We conclude that BFT2 alters chromatin accessibility in colon epithelial cells, and that these changes correlate with subsequent changes in gene expression. Also, sites of BFT2-induced increased chromatin accessibility are associated with a lower frequency of common single nucleotide variants (SNVs) in CRC and with a higher frequency of common differentially methylated regions (DMRs) in CRC.
2018-04-18 | GSE113218 | GEO