Project description:We observed that deletion of polyketide synthase (pks) from E. coli NC101 reduces its ability to induce tumors in interleukin-10 knockout (Il10-/-) mice injected with azoxymethane (AOM), without altering histologic inflammation. The goal of this experiment is to assess inflammatory cytokine levels in colonic tissue of these mice. 2 germ-free Il10-/- mice were assayed and used as controls. 3 E. coli NC101 and 3 E. coli NC101-delta-pks monoassociated mice were experimental samples.
Project description:We observed that interleukin-10 knockout (Il10-/-) mice injected with azoxymethane (AOM) and monoassociated with E. coli NC101, but not E. faecalis OG1RF, develop tumors. Histologic inflammation is not different in mice monoassociated with either bacterium. The goal of this experiment is to assess inflammatory cytokine levels in colonic tissue of these mice. 4 germ-free Il10-/- mice were assayed and used as controls. 4 E. coli and 4 E. faecalis monoassociated mice were experimental samples.
Project description:We observed that interleukin-10 knockout (Il10-/-) mice injected with azoxymethane (AOM) and monoassociated with E. coli NC101, but not E. faecalis OG1RF, develop tumors. Histologic inflammation is not different in mice monoassociated with either bacterium. The goal of this experiment is to assess inflammatory cytokine levels in colonic tissue of these mice. 4 germ-free Il10-/- mice were assayed and used as controls. 4 E. coli and 4 E. faecalis monoassociated mice were experimental samples.
Project description:We observed that interleukin-10 knockout (Il10-/-) mice injected with azoxymethane (AOM) and monoassociated with E. coli NC101, but not E. faecalis OG1RF, develop tumors. Histologic inflammation is not different in mice monoassociated with either bacterium. The goal of this experiment is to assess inflammatory cytokine levels in colonic tissue of these mice.
Project description:We observed that interleukin-10 knockout (Il10-/-) mice injected with azoxymethane (AOM) and monoassociated with E. coli NC101, but not E. faecalis OG1RF, develop tumors. Histologic inflammation is not different in mice monoassociated with either bacterium. The goal of this experiment is to assess inflammatory cytokine levels in colonic tissue of these mice.
Project description:We observed that deletion of polyketide synthase (pks) from E. coli NC101 reduces its ability to induce tumors in interleukin-10 knockout (Il10-/-) mice injected with azoxymethane (AOM), without altering histologic inflammation. The goal of this experiment is to assess inflammatory cytokine levels in colonic tissue of these mice.
Project description:The complex reservoir of metabolite-producing bacteria in the gastrointestinal tract contributes tremendously to human health and disease. Bacterial composition, and by extension gut metabolomic composition, is undoubtably influenced by the use of modern antibiotics. Herein, we demonstrate that polymyxin B, a last resort antibiotic used for chronic multidrug resistant infections infections, influences the production of the genotoxic metabolite colibactin from adherent-invasive Escherichia coli (AIEC) NC101. Colibactin can augment colorectal cancer (CRC) through DNA double stranded breaks and interstrand crosslinks. While the structure and biosynthesis of colibactin has been elucidated, chemical-induced regulation of its biosynthetic gene cluster and subsequent production of the genotoxin by pathogenic E. coli are largely unexplored. This research highlights the regulation of the colibactin-producing biosynthetic gene cluster under polymyxin stress. Using a multi-omic approach, we have identified that polymyxin stress enhances the abundance of colibactin biosynthesis proteins (Clb’s) in multiple pks+ E. coli strains, including pro-carcinogenic AIEC: NC101, the probiotic strain: E. coli Nissle 1917, and the antibiotic testing strain: E. coli ATCC 25922. Expression analysis via qPCR revealed that increased transcription of clb genes likely contributes to elevated Clb protein levels in NC101. Enhanced production of Clb’s by NC101 under polymyxin stress matched an increased production of the colibactin prodrug motif, a proxy for the mature genotoxic metabolite. Furthermore, E. coli with heightened tolerance for polymyxin antibiotics induced greater DNA damage, assessed by quantification of γH2AX staining in cultured intestinal epithelial cells. This study establishes a key link between the polymyxin B stress response and colibactin production in pks+ E. coli. Ultimately, our findings will inform future studies investigating colibactin regulation, the microbial response to antibiotics in the gut, and the ability of seemingly innocuous commensal microbes to induce host disease.
Project description:Colorectal cancer is driven by a sequential cascade of mutations known as the adenoma-carcinoma sequence. Recent studies have revealed that specific bacterial species present in the colonic microbiota can induce mutations and contribute to this malignancy. Specifically, genotoxic colibactin-producing pks+ Escherichia coli strains can induce DNA double strand breaks (DSBs) and promote tumor development in mouse models of colorectal cancer. Here, we investigated the transformation potential of colibactin by using organoids and polarized monolayers derived from primary murine colon epithelial cells and reveal striking phenotypic changes upon short-term infection. This study demonstrates the direct pro-oncogenic potential of pks+ E. coli, as such transformations in vivo could facilitate colitis-associated colorectal carcinogenesis.
