In-vivo Colon Research Articles

A CONSORTIA OF CLINICAL E. COLI STRAINS WITH DISTINCT IN-VITRO ADHERENT/INVASIVE PROPERTIES ESTABLISH THEIR OWN CO-COLONIZATION NICHE AND SHAPE THE INTESTINAL MICROBIOTA IN INFLAMMATION-SUSCEPTIBLE MICE

Abstract Mucosal colonization with adherent-invasive Escherichia coli (AIEC) are believed to perpetuate intestinal inflammation and associated inflammatory bowel disease (IBD). However, it remains unclear if the 24-year-old AIEC in-vitro definition fully predicts mucosal colonization in-vivo. To fill this gap, germ-free inflammation-susceptible interleukin-10-deficient (Il10-/-) and inflammation-resistant WT mice were colonized with a consortia of AIEC and non-AIEC strains, then given a murine fecal transplant to provide niche competition. E. coli strains isolated from human intestinal tissue were each marked with a unique molecular barcode that permits identification and quantification by barcode-targeted sequencing. Our data reveal that specific AIEC and non-AIEC strains reproducibly colonize the intestinal mucosa of WT and Il10-/- mice. These E. coli expand in Il10-/- mice during inflammation and induce compositional dysbiosis to the microbiome in an inflammation-dependent manner based on histological analysis and 16S sequencing. Because select AIEC and non-AIEC strains colonize the mucosa, this suggests the in vitro AIEC definition may not fully predict in vivo colonization potential. Further comparison of seven E. coli genomes pinpointed unique genomic features contained only in highly colonizing strains (two AIEC and two non-AIEC). Those colonization-associated features may convey metabolic advantages (e.g., iron acquisition and carbohydrate consumption) to promote efficient mucosal colonization. Our findings establish the in-vivo mucosal colonizer, not necessarily AIEC, as a principal dysbiosis driver through crosstalk with host and associated microbes. Furthermore, we highlight the utility of high-throughput screens to decode the in-vivo colonization dynamics of patient-derived bacteria in murine models.

Biopolymeric pH-responsive fluorescent gel for in-vitro and in-vivo colon specific delivery of metronidazole and ciprofloxacin

Biocompatible fluorescent active and pH sensitive gel has been developed using covalently attached riboflavin as proficient fluorophore on crosslinked glycogen. The chemically crosslinked glycogen (cl-Gly/PMAc) has been synthesised by grafting of methacrylic acid (MAc) followed by crosslinking using ethylene glycol dimethacrylate (EGDMA) through free radical polymerization. Afterward, the fluorescent active hydrogel (cl-Gly/PMAc-RB) has been synthesised by post-polymerization modification of cl-Gly/PMAc with riboflavin. The gel properties have been explored by determining rheological parameters. pH responsive swelling and reversible swelling behaviours of cl-Gly/PMAc-RB have been investigated by executing swelling/deswelling/reswelling studies. In-vitro cell cytotoxicity study predicts that the material is non-toxic and biocompatible. cl-Gly/PMAc-RB gel demonstrates excellent release profile towards the release of dual drugs (metronidazole: release ∼ 75% after 24 h and ciprofloxacin: release ∼ 55% after 24 h) in colonic region, which is evidenced from in vitro and in-vivo studies. Finally, ab-initio molecular dynamics study has been carried out to investigate the intricate details of the probable drugs-hydrogel interaction and pH responsive release profile of dual drugs from cl-Gly/PMAc-RB hydrogel in molecular level.

Inhibition of epidermal growth factor receptor improves antitumor efficacy of vemurafenib in BRAF-mutant human melanoma in preclinical model.

Oncogenic activation of the epidermal growth factor receptor (EGFR) signaling pathway occurs in a variety of tumor types, albeit in human melanoma, the contribution of EGFR is still unclear. The potential role of EGFR was analyzed in four BRAF-mutant, one NRAS-mutant and one wild-type NRAS-BRAF-carrying human melanoma cell lines. We have tested clinically available reversible tyrosine kinase inhibitors (TKIs) gefitinib and erlotinib, irreversible EGFR-TKI pelitinib and a reversible experimental compound PD153035 on in-vitro proliferation, apoptosis, migration as well as in-vivo metastatic colonization in a spleen-liver model. The presence of the intracellular domain of EGFR protein and its constitutive activity were demonstrated in all cell lines. Efficacies of EGFR-TKIs showed significant differences, and irreversible inhibition had the strongest antitumor potential. Compared with BRAF-mutant cells, wild-type BRAF was associated with relative resistance against gefitinib. In combination with gefitinib, selective mutant BRAF-inhibitor vemurafenib showed additive effect in all BRAF-mutant cell lines. Treatment of BRAF-mutant cells with gefitinib or pelitinib attenuated in-vitro cell migration and in-vivo colonization. Our preclinical data suggest that EGFR is a potential target in the therapy of BRAF-mutant malignant melanoma; however, more benefits could be expected from irreversible EGFR-TKIs and combined treatment settings.

Abstract 5007: Role of the interferon-gamma response pathway in immune escape of colorectal carcinoma

Abstract The presence of an interferon-dominated Th1 immune response in colorectal carcinoma (CRC) has been associated with improved clinical outcome. We have previously identified the guanylate-binding protein 1 (GBP-1), one of the major IFN-γ-induced proteins, as a marker for the Th1 immune response and an independent positive prognostic factor in CRC. We also found that GBP-1 is a necessary mediator of the anti-tumorigenic effects of IFNγ. Interestingly, the expression of GBP-1 in CRC was observed more frequently in the desmoplastic stroma than in the directly adjacent tumor cells, suggesting that CRC tumor cells might become resistant to IFN-γ in the course of tumorigenesis. Indeed, we found that several colorectal carcinoma cell lines failed to express GBP-1 or other interferon-stimulated genes after treatment with IFN-γ, and were resistant to IFN-γ-induced apoptosis or proliferation inhibition. In these cell lines, the loss of IFN-γresponsiveness correlated either with the down-regulation of the IFN-γ receptor alpha chain (IFNγRα) or with the presence of a mis-glycosylated form of IFNγRα, which displayed an aberrant intracellular localization. We further validated these findings at the clinical level by showing that the expression of IFNγRα is decreased in CRC compared to normal tissue. In addition, the down-regulation of IFNγRα expression in CRC correlated with a reduced cancer-related survival together with a higher rate of distant metastasis. In addition, in-vivo colon tumorigenesis models using conditional knock-out mice revealed that the absence of IFNγRα expression by intestinal epithelial cells fosters tumor growth. Altogether, our data suggest that the loss of IFN-γ responsiveness is a common event in CRC and protects tumor cells against the anti-tumorigenic effects of IFN-γ. Citation Format: Nathalie Britzen-Laurent, Julia Straube, Philipp Tripal, Maximilian Waldner, Christoph Becker, Susanne Merkel, Roland S. Croner, Michael Sturzl. Role of the interferon-gamma response pathway in immune escape of colorectal carcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5007. doi:10.1158/1538-7445.AM2017-5007

In vitro Multi-Species Biofilms of Methicillin-Resistant Staphylococcus aureus and Pseudomonas aeruginosa and Their Host Interaction during In vivo Colonization of an Otitis Media Rat Model.

Staphylococcus aureus (SA) and Pseudomonas aeruginosa (PA) are known to cause biofilm-related infections. MRSA and PA have been frequently isolated from chronically infected wounds, cystic fibrosis, chronic suppurative otitis media (CSOM), and from indwelling medical devices, and these bacteria co-exist; however, their interaction with each-other or with the host is not well known. In this study, we investigated MRSA and PA multi-species biofilm communities in vitro and their interaction with the host during in vivo colonization using an OM rat-model. In-vitro biofilm formation and in-vivo colonization were studied using CV-microtiter plate assay and OM rat-model respectively. The biofilms were viewed under scanning electron microscope and bacteria were enumerated using cfu counts. The differential gene expressions of rat mucosa colonized with single or multi-species of MRSA or PA were studied using RNA-sequencing of total transcriptome. In multi-species in-vitro biofilms PA partially inhibited SA growth. However, no significant inhibition of MRSA was detected during in-vivo colonization of multi-species in rat bullae. A total of 1,797 genes were significantly (p < 0.05) differentially expressed in MRSA or PA or MRSA + PA colonized rat middle ear mucosa with respect to the control. The poly-microbial colonization of MRSA and PA induced the differential expression of a significant number of genes that are involved in immune response, inflammation, signaling, development, and defense; these were not expressed with single species colonization by either MRSA or PA. Genes involved in defense, immune response, inflammatory response, and developmental process were exclusively up-regulated, and genes that are involved in nervous system signaling, development and transmission, regulation of cell growth and development, anatomical and system development, and cell differentiation were down-regulated after multi-species inoculation. These results indicate that poly-microbial colonization induces a host response that is different from that induced by single species infection.

Inhibition of autophagy and tumor growth in colon cancer by miR-502

Autophagy is a catabolic process that allows cellular macromolecules to be broken down and recycled as metabolic precursors. The influence of non-coding microRNAs (miRNAs) in autophagy has not been explored in colon cancer. In this study, we discover a novel mechanism of autophagy regulated by hsa-miR-502-5p (miR-502) by suppression of Rab1B, a critical mediator of autophagy. A number of other miR-502 suppressed mRNA targets (e.g. DHODH) are also identified by microarray analysis. Ectopic expression of miR-502 inhibited autophagy, colon cancer cell growth, and cell cycle progression of colon cancer cells in vitro. miR-502 also inhibited in vivo colon cancer growth in a mouse tumor xenografts model. In addition, the expression of miR-502 was regulated by p53 via a negative feedback regulatory mechanism. The expression of miR-502 was down-regulated in colon cancer patient specimens compared to the paired normal control samples. These results suggest that miR-502 may function as a potential tumor suppressor and therefore be a novel candidate for developing miR-502 based therapeutic strategies.

Altered bacterial aggregation and adherence associated with changes in rat parotid-gland salivary proteins induced in vivo by β-adrenergic stimulation

Reduced adherence and aggregation were associated with protein alterations in parotid saliva after chronic treatment with the β-adrenergic agonist isoproterenol. In contrast, saliva from animals treated with the β-antagonist, propranolol, did not cause such changes; the protein composition of this saliva was similar to that of controls. SDS-polyacrylamide gel electrophoresis of protein in saliva samples before and after they were mixed with 10 mg of spheroidal hydroxyapatite beads (HA), as well as protein adsorbed and recovered from the HA, showed that an acidic, proline-rich protein with a molecular weight of approx. 40,000 was the predominant protein adsorbed. This protein was significantly diminished in saliva from isoproterenol-treated rats. Proteins with molecular weights between 44,000 and 48,000 and unique to the saliva from isoproterenol-treated animals were also adsorbed to HA. Thus alterations in proline-rich proteins of parotid saliva may influence the adherence and aggregation of oral bacteria, two processes considered important for in-vivo colonization of oral surfaces.