HAL ENVT (Ecole Nationale Vétérinaire de Toulouse)
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Ex vivo exposure to the food-grade silicon dioxide hinders intestinal T cell proliferation and reduces IL-10 and TGF-β production by T regulatory anddendritic cells, two keys players of oral tolerance induction to food antigens
No full textInternational audienceBackground and Purpose: The gut immune system is daily exposed to inorganic particles used in the food industry as food additives or processing aids, such assilicon dioxide (SiO2), a common anticaking agent in manufacturing powdered foods (milk, infant formulae, instant soups), ingredients (spices, salt, flours) andsupplements. In the gut, a state of immune unresponsiveness to innocuous dietary antigens such as food proteins (known as oral tolerance, OT) is established bythe interaction of diverse immune cells to prevent food sensitivities, including allergy. In physiological conditions, the key event for inducing OT is the antigenuptake by intestinal dendritic cells (DCs) and their migration to mesenteric lymph nodes (MLN). In the MLN, DCs produce TGF-β and present antigen to naïve Tcells, mediating their conversion into Treg and Tr1 cells that secrete the anti-inflammatory cytokines IL-10 and TGF-β with suppressor function on immuneresponses. In a previous study using a mouse model of OT induction to the food antigen model ovalbumin, we showed that chronic oral exposure to food-grade(fg) SiO2 led to OT breakdown with a decreased production of IL-10 and TGF-β by MLN cells, and intestinal inflammation. Here we investigated ex vivo whetherthese fg-SiO2-mediated immunological defects could result from a direct interaction of SiO2 particles with immune cells in the MLN.Methods: MLN cells of untreated mice (C57BL/6) were exposed to fg-SiO2 (0, 6.25, 12.5, 25 and 50 µg/mL) for 24, 48 or 72h. Cell viability was assessed bylabelling cells with propidium iodide. The production of IL-10, IFN-γ and TGF-β by fg-SiO2 exposed-MLN cells was evaluated by ELISA following unspecificsimulation with phorbol 12-myristate 13-acetate (PMA) and ionomycin (PMA/iono) of all MLN cells, or anti-CD3/anti-CD28 stimulation specific of T cell subsets.The populations of MLN cells producing these cytokines were identified by flow cytometry. To assess the effects of fg-SiO2 on T cell proliferation, MLN cells wereexposed for 3 days to concanavalin-A (a T-cell mitogen) in the presence of fg-SiO2, and the frequency of dead and proliferative T cells was determined by flowcytometry. All animal experiments were approved by the Local Animal Care and Use Committee.Results: Cell viability was not impacted after exposure to fg-SiO2 regardless of the dose tested. A decreased production of TGF-β was observed in anti-CD3/CD28stimulated T cells after exposure to the highest dose of fg-SiO2 while TGF-β secretion was not altered after PMA/iono stimulation. In the presence of fg-SiO2, theproduction of the anti-inflammatory cytokine IL-10 was decreased whatever MLN cell stimulation, but the decrease was only significant in PMA/iono stimulatedcells exposed at the highest doses of the food additive. The production of IFN-γ by MLN cells was not modulated in presence of fg-SiO2 regardless thestimulation used. Flow cytometry analysis showed that the immunological effects of fg-SiO2 were due to a decreased production of IL-10 and TGF-β by Treg cells(CD3+ CD4+ CD25+ FOXP3+ IL-10+) and DCs (CD45+ CD103+ CD11b+ TGF-β+), respectively. In proliferative condition, fg-SiO2 treatment of MLN cells evoked adose-dependent decrease of T cell proliferation without reduction in T cell viability. This suggested that the fg-SiO2-induced failure in IL-10 and TGF-β secretioncould be also partly due to an anti-proliferative effect of the food additive.Conclusions: Taken together with our previous study, these data show that the ability of the food additive SiO2 to block the establishment of OT is partly due to adirect interaction with MLN cells, reducing T cell proliferation and decreasing the secretion of the suppressive factors IL-10 and TGF-β by Treg cells and DCs. Thisraises the hypothesis that chronic exposure to SiO2 through the diet could act as an environmental trigger for loss of OT, possibly contributing to thedevelopment of food sensitivities. Our results should encourage epidemiological research on potential adverse effects related to the chronic intake of foodadditive SiO2, in particular, its association with food allergies and intolerances
Combining systems and synthetic biology for in vivo enzymology
No full textInternational audienceEnzymatic parameters are classically determined in vitro , under conditions that are far from those encountered in cells, casting doubt on their physiological relevance. We developed a generic approach combining tools from synthetic and systems biology to measure enzymatic parameters in vivo . In the context of a synthetic carotenoid pathway in Saccharomyces cerevisiae , we focused on a phytoene synthase and three phytoene desaturases, which are difficult to study in vitro . We designed, built, and analyzed a collection of yeast strains mimicking substantial variations in substrate concentration by strategically manipulating the expression of geranyl-geranyl pyrophosphate (GGPP) synthase. We successfully determined in vivo Michaelis-Menten parameters ( K M , V max and k cat ) for GGPP-converting phytoene synthase from absolute metabolomics, fluxomics and proteomics data, highlighting differences between in vivo and in vitro parameters. Leveraging the versatility of the same set of strains, we then extracted enzymatic parameters for two of the three phytoene desaturases. Our approach demonstrates the feasibility of assessing enzymatic parameters directly in vivo , providing a novel perspective on the kinetic characteristics of enzymes in real cellular conditions
A multi-omics dataset of the response to early plant polysaccharide ingestion in rabbits
No full textInternational audienceAbstract The transition from a milk-based diet to exclusive solid feeding deeply modifies microbiota-host crosstalk. Specifically, early ingestion of plant polysaccharides would be one of the main nutritional components to drive host-microbiota-interaction. To capture the effects of polysaccharides early-life nutrition (starch vs rapidly fermentable fiber) on the holobiont development, we investigated on the one hand the gut bacteriome and metabolome and on the other hand the transcriptome of two host gut tissues. Rabbit model was used to study post-natal co-development of the gut microbiota and its host around weaning transition. The assessment of the microbial composition of the gut appendix together with the caecum was provided for the first time. Gene expression signatures were analyzed along the gut (ileum and caecum) through high-throughput qPCR. The data collected were completed by the analysis of animal growth changes and time-series assessment of blood biomarkers. Those accessible and reusable data could help highlight the gut development dynamics as well as biological adaptation processes at the onset of solid feeding
Comparison between 16S rRNA and shotgun sequencing in colorectal cancer, advanced colorectal lesions, and healthy human gut microbiota
No full textInternational audienceBackground Gut dysbiosis has been associated with colorectal cancer (CRC), the third most prevalent cancer in the world. This study compares microbiota taxonomic and abundance results obtained by 16S rRNA gene sequencing (16S) and whole shotgun metagenomic sequencing to investigate their reliability for bacteria profiling. The experimental design included 156 human stool samples from healthy controls, advanced (high-risk) colorectal lesion patients (HRL), and CRC cases, with each sample sequenced using both 16S and shotgun methods. We thoroughly compared both sequencing technologies at the species, genus, and family annotation levels, the abundance differences in these taxa, sparsity, alpha and beta diversities, ability to train prediction models, and the similarity of the microbial signature derived from these models. ResultsAs expected, the results showed that 16S detects only part of the gut microbiota community revealed by shotgun, although some genera were only profiled by 16S. The 16S abundance data was sparser and exhibited lower alpha diversity. In lower taxonomic ranks, shotgun and 16S highly differed, partially due to a disagreement in reference databases. When considering only shared taxa, the abundance was positively correlated between the two strategies. We also found a moderate correlation between the shotgun and 16S alpha-diversity measures, as well as their PCoAs. Regarding the machine learning models, only some of the shotgun models showed some degree of predictive power in an independent test set, but we could not demonstrate a clear superiority of one technology</div
Analyse comparative des profils transcriptionnels du jéjunum de poulet et d'organoïdes dérivés collectés durant les premiers jours de vie
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Quels besoins de recherches pour améliorer conjointement la santé et le bien-être des animaux dans la transition agroécologique de l'élevage ?
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What is your diagnosis? Abnormal cluster on the WDF and WNR scattergrams from Sysmex XN ‐V in a dog
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Measurement of the Direct Impact of Hematophagous Flies on Feeder Cattle: An Unexpectedly High Potential Economic Impact
No full textInternational audienceIn addition to blood pathogen transmission, insects of the order Diptera affect livestock through visual and contact harassment; blood-feeders are responsible for painful bites and blood despoliation, generating behavioral modifications, anemia, and production losses. Knowledge of their economic impact is a basis for cost-effective control. Here, we measured the global impact of diptera insects by comparing two batches of six feeder cattle, one in the open air and the other protected by a mosquito net. The analytical data were insect density in the open air and, for feeder cattle, tail flick counts, hematocrit values (Ht), feed intake, feed conversion ratio (FCR), and live body weight gain (LBWG). Over a period of five months, the results showed significant losses in the LBWG of cattle exposed to insects, estimated at 8.0 ± 1.5 kg/month [2.7; 13.3], with a total loss reaching 40.0 ± 5.5 kg/head. Main diurnal insects were Stomoxys spp. and Musca crassirostris. There was a strong correlation between fly density and diurnal tail flicks. Night trapping and tail flicks showed a potentially important role of mosquitoes to be further explored. The Ht levels of exposed animals were 3–4% lower than those of controls. FCRs indicated that exposed animals needed 33% more dry matter intake/kg of LBWG. An economic assessment showed that dipterans were responsible for a 10–11% loss in LBWG during the main growing period of feeder cattle (10–15 months). A feedlot of 100 calves would register a total loss of USD 16,000 within 5 months, which appears to be an unexpectedly huge loss caused by dipterans. Investing part of this money into fly control would probably be beneficial
Validation of the Sysmex XN ‐ V hematology analyzer for feline specimens
No full textInternational audienceAbstract Background The Sysmex XN‐V is derived from the new Sysmex XN series of human hematology analyzers. The main changes from the previously validated XT‐2000iV analyzer include an optic‐fluorescent analysis for platelets and a nucleated red blood cell (NRBC) count. Objective We aimed to validate the Sysmex XN‐V for feline blood following the American College for Veterinary Clinical Pathology and International Council for Standardization in Hematology recommendations. Methods Feline EDTA blood specimens were analyzed on the Sysmex XN‐V to evaluate repeatability, linearity, comparison with the XT‐2000iV analyzer and manual methods, stability, and to verify the previously established Sysmex XT‐2000iV RIs. Results Repeatability was excellent for most variables. Visually determined linearity was excellent or good for most variables except eosinophils and platelet variables. The correlation between the XN‐V and XT‐2000iV analyzers was good (≥0.82) for all variables except reticulocyte indices. Correlations between the Sysmex XN‐V and manual differential counts were good to excellent for most variables, acceptable for neutrophils, and fair for monocytes and NRBC. The previously established Sysmex XT‐2000iV RIs can be used to interpret results from the Sysmex XN‐V analyzer for most variables except red cell distribution width and reticulocyte variables. The RI for platelet variables could not be evaluated because of platelet clumps. Changes in the Sysmex XN‐V measurements after storage at 4 and 24°C were similar to those described for the Sysmex XT‐2000iV analyzer. Conclusions The performance of the Sysmex XN‐V analyzer was good and compared favorably with the Sysmex XT‐2000iV analyzer
3D Printing and Gallium-Based Liquid Metal Technologies for Microwave and Millimeter-wave Components
No full textInternational audienceThe article presents an overview of threedimensional (3D) printed microwave and millimeter-wave components integrating Gallium-based liquid metal. The liquid metal is considered here as a 4th degree of freedom for the design of 3D printed antennas, filters and wireless sensors. The 3D printing combined with liquid metal technology can be considered as a four-dimensional (4D) printing technology and to date, in microwave and millimeter-wave applications, is mainly used to achieve the metallization and/or reconfigurability and/or mechanical flexibility of high-frequency 3D printed components