Project description:Guanidine DNA quadruplex (G4-DNA) structures convey a distinctive layer of epigenetic information that is critical for the regulation of key biological activities and processes as genome transcription regulation, replication and repair. Despite several works that have been published recently, the information regarding their role and possible use as therapeutic drug targets in bacteria is still scarce. Here, we tested the biological activity of a small G4-DNA ligand library based on the naphthalene diimide (NDI) pharmacophore, against both Gram-positive and Gram-negative bacteria. For the best compound identified, NDI-10, the action mechanism was further characterized. Gram-negative bacteria were more resistant altogether due to the presence of the outer membrane, although the activity of the G4-Ligand was generally bactericidal, while it was bacteriostatic for Gram-positive bacteria. This asymmetric activity could be related to the different prevalence of putative G4-DNA structures in each group, the influence that they can exert on the gene expression (which was found more severe for the Gram-negative bacteria) and the role of the G4 structures in these bacteria, that seems to be more related to promote transcription in Gram-positive bacteria and repress transcription in Gram-negative.
Project description:In order to understand the appropriate use of potentially beneficial Gram positive microbes through their introduction in the gut microbiome, it is necessary to understand the influence of individual bacteria on the host response system at a cellular level. In the present study we showed that lipopolysaccharide (LPS), flagellated Gram negative bacteria, potentially beneficial Gram positive bacteria and yeast interact differently with human intestinal enterocytes (IEC) with a custom-designed expression microarray evaluating 17 specific host-response pathways. Only, LPS and flagellated Gram negative bacteria induced inflammatory response, while a subset of Gram positive microbes had anti-inflammatory potential. The main outcome from the study was the differential regulation of the central MAPK signaling pathway by these Gram positive microbes versus commensal/pathogenic Gram negative bacteria. The microarray was efficient to highlight the impact of individual bacteria on IEC response, but q-RT-PCR validation demonstrated some underestimation for down regulated genes by the microarray. This Immune Array will allow us to better understand the mechanisms underlying pathogen-induced host immune responses, aid in the selection potentially probiotic microbes and perhaps select biomarkers for future clinical studies. In this study, human immune response was assessed by stimulating HT-29 intestinal epithelial cells (IEC) with different microorganisms (or LPS) individually. For each of the 12 different treatments, between 4 and 8 biological replicates were performed, analyzed with dye-swaps and hybridized against control or untreated cells. Genes that were showing a 1.3 mRNA transcript abundance fold change and a P-value below 0.05 were considered to be differentially expressed.
Project description:In order to understand the appropriate use of potentially beneficial Gram positive microbes through their introduction in the gut microbiome, it is necessary to understand the influence of individual bacteria on the host response system at a cellular level. In the present study we showed that lipopolysaccharide (LPS), flagellated Gram negative bacteria, potentially beneficial Gram positive bacteria and yeast interact differently with human intestinal enterocytes (IEC) with a custom-designed expression microarray evaluating 17 specific host-response pathways. Only, LPS and flagellated Gram negative bacteria induced inflammatory response, while a subset of Gram positive microbes had anti-inflammatory potential. The main outcome from the study was the differential regulation of the central MAPK signaling pathway by these Gram positive microbes versus commensal/pathogenic Gram negative bacteria. The microarray was efficient to highlight the impact of individual bacteria on IEC response, but q-RT-PCR validation demonstrated some underestimation for down regulated genes by the microarray. This Immune Array will allow us to better understand the mechanisms underlying pathogen-induced host immune responses, aid in the selection potentially probiotic microbes and perhaps select biomarkers for future clinical studies.
Project description:Transcriptional profiling of D. discoideum revealed sets of genes whose expression is enriched in amoebae interacting with different species of bacteria, including sets that appear specific to amoebae interacting with Gram(+), or with Gram(-) bacteria. In a genetic screen utilizing the growth of mutant amoebae on a variety of bacteria as a phenotypic readout, we identified amoebal genes that are only required for growth on Gram(+) bacteria, including one that encodes the cell surface protein gp130, as well as several genes that are only required for growth on Gram(-) bacteria including one that encodes a putative lysozyme, AlyL. These genes are required for parts of the transcriptional response of wild-type amoebae, and this allowed their classification into potential response pathways. Transcriptional profiling of amoebal response to different bacteria.
Project description:Transcriptional profiling of D. discoideum revealed sets of genes whose expression is enriched in amoebae interacting with different species of bacteria, including sets that appear specific to amoebae interacting with Gram(+), or with Gram(-) bacteria. In a genetic screen utilizing the growth of mutant amoebae on a variety of bacteria as a phenotypic readout, we identified amoebal genes that are only required for growth on Gram(+) bacteria, including one that encodes the cell surface protein gp130, as well as several genes that are only required for growth on Gram(-) bacteria including one that encodes a putative lysozyme, AlyL. These genes are required for parts of the transcriptional response of wild-type amoebae, and this allowed their classification into potential response pathways.
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.