The feather epithelium contributes to the dissemination and ecology of clade 2.3.4.4b H5 high pathogenicity avian influenza viruses in ducks

Immature feathers are known replication sites for high pathogenicity avian influenza viruses (HPAIVs) in poultry. However, it is unclear whether feathers play an active role in viral transmission. This study aims to investigate the contribution of the feather epithelium to the dissemination of clade 2.3.4.4b goose/Guangdong/1996 lineage H5 HPAIVs in the environment, based on natural and experimental infections of domestic mule and Muscovy ducks. During the 2016-2022 outbreaks, H5 HPAIVs exhibited persistent and marked feather epitheliotropism in naturally infected commercial ducks. Infection of the feather epithelium resulted in epithelial necrosis and disruption, as well as the production and environmental shedding of infectious virions. Viral and feather antigens colocalized in dust samples obtained from poultry barns housing naturally infected birds. In summary, the feather epithelium contributes to viral replication, and it is a likely source of environmental infectious material. This underestimated excretion route could greatly impact the ecology of HPAIVs, facilitating airborne and preening-related infections within a flock, and promoting prolonged viral infectivity and long-distance viral transmission between poultry farms

3D printing of biocompatible low molecular weight gels: Imbricated structures with sacrificial and persistent N-alkyl-d-galactonamides

International audienc

Physicochemical study of aqueous dispersions of organogel particles: Role of the ingredients and formulation process leading to colloidal hydrogels

dispersions of organogel particles were obtained by hot emulsification (T°>T gel), and cooling (T°<T gel). Two oils were tested, sweet almond oil and phytosqualane, using 12-hydroxystearic acid (HSA) as an organogelator, and polyvinyl alcohol (PVA80) as a stabilizer. A preservative agent (Saliguard® COS) and an antioxidant (Tocopherol) were also used. Under the same preparation conditions, two completely different textures were obtained depending on the oil: a stable dispersion of organogel particles for sweet almond oil and a colloidal hydrogel for phytosqualane. In this study, we were able to understand the impact of the ingredients on these differences in texture, and propose different mechanisms of formation. The important role played by the preservative agent at the water/oil interface of the droplets, during the gelation step, was demonstrated. Such adsorption, depending on the polarity of the oil, can modify the anchoring of the dispersing agent (PVA80) and lead during the gelation to a destabilization of the droplets by coalescence and to the formation of a colloidal hydrogel. These results highlight the possible formation of colloidal hydrogels from particles of organogels and open the way to new textures in the cosmetic or pharmaceutical field

Synthesis of new alkylaminooxysterols with potent cell differentiating activities: identification of leads for the treatment of cancer and neurodegenerative diseases.

International audienceWe describe here the syntheses and the biological properties of new alkylaminooxysterols. Compounds were synthesized through the trans-diaxial aminolysis of 5,6-alpha-epoxysterols with various natural amines including histamine, putrescine, spermidine, or spermine. The regioselective synthesis of these 16 new 5alpha-hydroxyl-6beta-aminoalkylsterols is presented. Compounds were first screened for dendrite outgrowth and cytotoxicity in vitro, and two leads were selected and further characterized. 5alpha-Hydroxy-6beta-[2-(1H-imidazol-4-yl)ethylamino]cholestan-3beta-ol, called dendrogenin A, induced growth control, differentiation, and the death of tumor cell lines representative of various cancers including metastatic melanoma and breast cancer. 5alpha-Hydroxy-6beta-[3-(4-aminobutylamino)propylamino]cholest-7-en-3beta-ol, called dendrogenin B, induced neurite outgrowth on various cell lines, neuronal differentiation in pluripotent cells, and survival of normal neurones at nanomolar concentrations. In summary, we report that two new alkylaminooxysterols, dendrogenin A and dendrogenin B, are the first members of a class of compounds that induce cell differentiation at nanomolar concentrations and represent promising new leads for the treatment of cancer or neurodegenerative diseases

Dark Field Transmission Electron Microscopy Imaging for Biological and Soft Matter Systems

International audienceIn this study, we present a new application of the transmission electron microscopy dark field mode for cell imaging. We have applied this imaging mode to two types of cellular systems: human HeLa cells to analyze molecular membrane systems and HC11 mouse mammary cells containing lipid molecule droplets. We have also studied a third macromolecular system, copolymer nanoparticles for the characterization of core-shell structures. We want to show the effective use of diffraction contrast, even on amorphous systems for increasing the image contrast and the signal/noise ratio. We discuss the TEM dark field advantages for the analysis of polymers and other macromolecular systems, including biological, systems compared to the bright field mode

How an organogelator can gelate water: gelation transfer from oil to water induced by a nanoemulsion

International audienceA hydrogel can be formed by an organogelator in the presence of a nanoemulsion. It is expected that this is due to a gelation transfer from oil to water. The system started with an oil-in-water nanoemulsion prepared according to a phase inversion temperature (PIT) process. Into this nanoemulsion consisting of Kolliphor® RH40 and Brij® L4 as surfactants, and Miglyol® 812 as oil and water, we introduced the organogelator 12-hydroxyoctadecanoic acid (12-HOA) in the oil phase. After cooling at room temperature, a slow reversible gelation of the water phase occurred with persistence of the nanoemulsion. This thermally reversible system was investigated using various techniques (rheology, turbidimetry, optical and electron microscopies, scattering techniques). Successive stages appeared during the cooling process after the nanoemulsion formation, corresponding to the migration and self-assembly of the organogelator from the oil nanodroplets to the water phase. According to our measurements and the known self-assembly of 12-HOA, a mechanism explaining the formation of the gelled nanoemulsion is proposed

Structure and biological activities of a hexosamine-rich cell wall polysaccharide isolated from the probiotic Lactobacillus farciminis

International audienceLactobacillus farciminis CIP 103136 is a bacterial strain with recognized probiotic properties. However, the mechanisms underlying such properties have only been partially elucidated. In this study, we isolated and purified a cell-wall associated polysaccharide (CWPS), and evaluated its biological role in vitro. The structure of CWPS and responses from stimulation of (i) human macrophage-like THP-1 cells, (ii) human embryonal kidney (HEK293) cells stably transfected with Toll-like receptors (TLR2 or TLR4) and (iii) human colonocyte-like T84 intestinal epithelial cells, upon exposure to CWPS were studied. The structure of the purified CWPS from L. farciminis CIP 103136 was analyzed by nuclear magnetic resonance (NMR), MALDI-TOF-TOF MS, and methylation analyses in its native form and following Smith degradation. It was shown to be a novel branched polysaccharide, composed of linear backbone of trisaccharide repeating units of: [6GlcpNAc14ManpNAc14GlcpNAc1] highly substituted with single residues of Glcp, Galp and GlcpNAc. Subsequently, the lack of pro- or anti-inflammatory properties of CWPS was established on macrophage-like THP-1 cells. In addition, CWPS failed to modulate cell signaling pathways dependent of TLR2 and TLR4 in transfected HEK-cells. Finally, in T84 cells, CWPS neither influenced intestinal barrier integrity under basal conditions nor prevented TNF-/IFN- cytokine-mediated epithelium impairment

Adherent-invasive Escherichia coli isolated from Crohn's disease patients induce granulomas in vitro

Auteur de correspondance : [email protected] audienceAdherent-invasive Escherichia coli (AIEC) have been shown to be highly associated with ileal Crohn's disease (CD). AIEC survive within infected macrophages, residing within the phagolysosomal compartment where they take advantage of the low pH to replicate extensively. We investigated whether, like the tuberculous bacillus which also persists within macrophages, AIEC LF82 induces the formation of granulomas, which are a common histopathological feature of CD. For this purpose, we have taken advantage of an in vitro model of human granulomas that we recently developed, based on blood-derived mononuclear cells. We demonstrated that AIEC LF82 induces aggregation of infected macrophages, fusion of some of them to form multinucleated giant cells and subsequent recruitment of lymphocytes. Light microscopy and scanning electron microscopy analysis of the cell aggregates confirmed their granuloma features. This was further confirmed by histological analysis of granuloma sections. Noteworthy, this phenomenon can be reproduced by soluble protein extracts of AIEC LF82 coated onto beads. Although the cell aggregates not completely mimic natural CD-associated granulomas, they are very similar to early stages of epithelioid granulomas

Structure and biological activities of a hexosamine-rich cell wall polysaccharide isolated from the probiotic Lactobacillus farciminis

International audienceLactobacillus farciminis CIP 103136 is a bacterial strain with recognized probiotic properties. However, the mechanisms underlying such properties have only been partially elucidated. In this study, we isolated and purified a cell-wall associated polysaccharide (CWPS), and evaluated its biological role in vitro. The structure of CWPS and responses from stimulation of (i) human macrophage-like THP-1 cells, (ii) human embryonal kidney (HEK293) cells stably transfected with Toll-like receptors (TLR2 or TLR4) and (iii) human colonocyte-like T84 intestinal epithelial cells, upon exposure to CWPS were studied. The structure of the purified CWPS from L. farciminis CIP 103136 was analyzed by nuclear magnetic resonance (NMR), MALDI-TOF-TOF MS, and methylation analyses in its native form and following Smith degradation. It was shown to be a novel branched polysaccharide, composed of linear backbone of trisaccharide repeating units of: [6GlcpNAc14ManpNAc14GlcpNAc1] highly substituted with single residues of Glcp, Galp and GlcpNAc. Subsequently, the lack of pro- or anti-inflammatory properties of CWPS was established on macrophage-like THP-1 cells. In addition, CWPS failed to modulate cell signaling pathways dependent of TLR2 and TLR4 in transfected HEK-cells. Finally, in T84 cells, CWPS neither influenced intestinal barrier integrity under basal conditions nor prevented TNF-/IFN- cytokine-mediated epithelium impairment