Procarta Biosystems (United Kingdom)

The human gut microbiota is complex, dense, and hugely influential to health. Imbalances in the microbiota have been associated with numerous disease states, in many cases due to the overgrowth of Enterobacteriaceae, such as Escherichia coli. We describe an oligonucleotide antimicrobial that selectively reduces levels of Enterobacteriaceae in vitro, in a model of the human colonic microbiota, and in vivo in a murine study, whilst leaving the core microbiota intact. The antimicrobials are Transcription Factor Decoys (TFDs) that bind to and competitively inhibit an identified transcription factor necessary for growth in the intestine. This is highly conserved amongst Enterobacteriaceae and controls anaerobic respiration and response to nitrosative stress caused by the innate immune response of the host. A nanoparticulate formulation delivers the TFDs to the cytoplasm of E. coli, as visualized by confocal microscopy, and rapidly kills the bacteria under microaerobic conditions. When applied to anin vitro model of the human intestinal microbiota the TFD produced a decrease up to log10 6 c.f.u. ml−1 in coliforms within the Enterobacteriaceae family while other families remain intact. When delivered orally to the intestines of mice similar results were seen: Enterobacteriaceae were decreased or cleared from the wild-type intestinal microbiota while the remaining bacteria were unaffected. This demonstrates that TFDs can be used to make precise changes to the microbiota and has utility in testing associations between dysbiosis and disease and developing microbiota targeted therapeutics.

Highly complex, multicomponent gels and water-containing soft materials have varied applications in biomedical, pharmaceutical, and food sciences, but the characterization of these nanostructured materials is extremely challenging. The aim of this study was to use stearoyl macrogol-32 glycerides (Gelucire 50/13) gels containing seven different species of glycerides, PEG, and PEG-esters, as model, complex, multicomponent gels, to investigate the effect of water content on the micro- and nanoarchitecture of the gel interior. Thermal analysis and NMR relaxometry were used to probe the thermal and diffusional behavior of water molecules within the gel network. For the highly concentrated gels (low water content), the water activity was significantly lowered due to entrapment in the dense gel network. For the gels with intermediate water content, multiple populations of water molecules with different thermal responses and diffusion behavior were detected, indicating the presence of water in different microenvironments. This correlated with the network architecture of the freeze-dried gels observed using SEM. For the gels with high water content, increased quantities of water with similar diffusion characteristics as free water could be detected, indicating the presence of large water pockets in these gels. The results of this study provide new insights into structure of Gelucire gels, which have not been reported before because of the complexity of the material. They also demonstrate that the combination of thermal analysis and NMR relaxometry offers insights into the structure of soft materials not available by the use of each technique alone. However, we also note that in some instances the results of these measurements are overinterpreted and we suggest limitations of the methods that must be considered when using them.