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International audience; Whereas breast milk is the gold standard, most infants are at least partly formula-fed.The aim of the present study was to investigate the short- and long-term effects of the addition of dairy lipids (DL) in infant formulas as an alternative to plant lipid-based infant formula, on gut microbiota composition and activity, and on intestinal immune and barrier functions, and of a probiotic, Lactobacillus fermentum (Lf), on the same parameters.Piglets received from postnatal day (PND) 2 to 28 a balanced formula containing either: only plant lipids (PL), a half-half mixture of PL and DL (DL), or a half-half mixture of PL and DL supplemented with Lf (DL+Lf). Pigs were subsequently fed a standard diet for 1 month and then challenged with a high-fat, high-sucrose diet for 3 months until PDN140. Dietary-induced changes in gut microbiota composition were observed at both PDN28 and PDN140, mainly within Firmicutes (Lachnospiraceae, Ruminococcaceae and Lactobacillaceae families) and Bacteroidetes (Prevotellaceae, Bacteroidaceae and Bacteroidales S24-7 group families) phyla. At PND28, twenty fecal metabolites (such as valerate, butyrate, amino acids, glucose) discriminated the three groups. DL and DL+Lf reinforced tight junction protein expressions in colon, with moderate changes in epithelial barrier permeability. At PND140, DL+Lf decreased the inflammation risk through decreased ileal pro-inflammatory cytokine secretion and increased ileal expression of genes encoding tight junction proteins. A slight but persisting and coherent effect of probiotic Lf on gut microbiota composition was observed between PND28 and PND140, even after discontinuation of its intake. Correlations between gut microbiota composition and intestinal physiology confirmed the involvement of gut microbiota in such processes.In conclusion, the addition of DL in infant formula changed the microbial signature and gut physiology in infants. The addition of Lf enhanced the beneficial effects observed in the long term. The addition of DL±Lf appears to be safe.

International audience; Swiss cheeses have been produced for centuries in a traditional way and their typical opening indicates the presence of propionibacteria. These last are indeed present in raw milk, their growth is favored by the specific technology of Swiss-type cheeses, and their high population in the ripened cheese is responsible for its characteristic sensory properties, including the opening and the aroma. In addition to this long history of safe use and consumption, they constitute a source of nutraceuticals. The specific propionic fermentation leads to the production of short chain fatty acids as main final obligatory products. These exert beneficial effects including nourishment of digestive epithelial cells, as well as promotion of differentiation and of apoptotic depletion of colon cancer cells. Propionibacteria also produce vitamins of the B group, which enhances the nutritional value of the food products they ferment. Some selected strains were moreover shown to produce immunomodulins, proteins able to modify the secretion of cytokines in human immune cells. These last were identified as proteinaceous components of propionibacteria surface layer. They also produce extracellular vesicles which modulate in vitro inflammation and the NFκB pathway in human intestinal epithelial cells. Accordingly, such strains modulate the immune response and mitigate inflammation. In mice, they prevent both mucositis and colitis, via such immunomodulins limiting acute inflammatory response and protecting the gut epithelial barrier. In pigs, their consumption also modulates the inflammatory response and the lymphocyte populations. Finally, clinical studies dealing with consumption of propionibacteria whey cultures suggest a beneficial role in the context of IBD. Propionibacteria strains were recently identified in the gut microbiota of healthy newborns, yet not in that of children with necrotizing enterocolitis. Indeed, propionibacteria were detected in human fecal samples, which means that propionibacteria may be traditional cheese starters or next generation probiotics. The growing knowledge of these peculiar actinobacteria, including their great strain-diversity, opens new avenues for the development of functional foods and of food supplements, in a general context of increasing incidence of ailments that include an inflammatory component. Moreover, their ability to ferment both dairy and vegetable matrices is presently investigated and the first promising advances open new perspectives for the development of functional fermented vegetable products.

National audience; La pollution plastique de tous les compartiments de l’environnement, y compris l’environnement marin, n’est désormais plus à démontrer. Concomitamment à cette pollution, la présence de particules plastiques de tailles micrométriques et nanométriques a également été rapportée. Ces particules peuvent constituer un danger physique ou agir en tant que vecteurs de différents contaminants chimiques ou biologiques. Chez les organismes vivants le devenir de ces particules n’est que partiellement connu et le passage des barrières biologiques reste controversé, bien qu’il soit probable pour les particules les plus petites comme les nanoplastiques. Afin de répondre à cette question de la possible translocation de nanoplastiques, des manipulations d’exposition ex vivo à des nanobilles de polystyrène modèle d’une taille de 50 nm (NP-PS) ont été réalisées sur des intestins de bar commun (Dicentrarchus labrax) en utilisant des chambres de Ussing.Grâce à la combinaison des résultats obtenus par plusieurs techniques de détection : fluorométrie, microscopie électronique à balayage (MEB) et pyrolyse couplée à la chromatographie en phase gazeuse et à un spectromètre de masse haute-résolution (Py-GC-HRMS), il a été possible d’enregistrer une augmentation de la fluorescence du côté séreux quelques dizaines de minutes après l’exposition des échantillons à la solution de NP-PS. Cette mesure a pu être confirmée par celles réalisées en MEB et Py-GC-HRMS. La translocation de nanobilles de PS de 50nm et sans agrégation dans le milieu expérimental, à travers la paroi de l’intestin de cette espèce de poisson a donc été attestée.

Remerciements : Institut CARNOT AgriFoodTransition; National audience; To date, host-virus interactions have been studied mainly in cell cultures and/or animal models. These approaches come up against two problems: i) methodological, usually related to using immortalized cell lines, which can differ greatly from the target cells of the virus, and ii) ethical, related to experimenting with animals, which can induce varying degrees of symptoms and cause suffering and death. The recent development of organoids has made it possible to develop ex vivo models whose experimental conditions are significantly closer to physiological conditions. Using organoids makes it possible to plan to decrease animal experimentation greatly, in line with the 3Rs principle (Reduction, Refinement, Replacement), and each animal can potentially produce thousands of organoids from different tissues. The Viral Genetics and Biosafety Unit applies the porcine organoid system developed locally as part of the PigOrg project (of INRAE, ANSES and INSERM, funded by the Carnot Agrifood Transition Institute) to models of enteric coronavirosis in piglets, which has a strong impact on the pig industry. Here, we used the porcine transmissible gastroenteritis virus (TGEv) as a model, for which several strains of varying virulence exist and which can be cultivated on immortalized cells, to establish protocols of infections of different organoids(jejunum, duodenum, and ileum). Infections seem more effective for the jejunum than for the duodenum or ileum, and for viruses isolated on cells than on organ homogenate. This organoid system, which connects in vitro and in vivo conditions, will open novel and original perspectives into understanding the physiopathology of virus infections, especially deciphering host-pathogen interactions, without always needing to rely on extensive animal experiments.

Accepted abstracts will be published in the Abstract Volume, a supplement issue of Diabetologia, the journal of the EASD. Furthermore abstracts accepted for presentation and discussion will be published on the Association’s website www.easd.org from 1 July 2022.; International audience

International audience; The gut microbiota plays an important role in the postnatal development of the intestinal epithelium. Proteobacteria and Fusobacteria are abundant in the gut microbiota of neonatal piglets. We hypothesized that members of these phyla could regulate epithelial homeostasis in early life. Piglets received every day from birth to day 7 an oral administration of water (negative control, n=18 piglets from 3 litters) or colistin (antibiotic targeting specific gram negative bacteria, n=18 piglets from 3 litters). At day 7, we analysed the microbiota and the metabolome in the colon and we isolated epithelial cells for gene expression profiling and organoid culture. Microbiota richness and β-diversity were analysed with the R package ‘Phyloseq’. Linear mixed models were used to compare groups by including the litter as a random effect. Differential abundance analysis showed that colistin reduced the relative abundance of Proteobacteria (Enterobacteriaceae, Pasteurellaceae) and Fusobacteria (Fusobacteriaceae) while it did not change the microbiota richness. The modification of the microbiota composition induced by colistin was associated with a modification of the colon metabolome. The treatment with colistin increased the relative concentration of succinate, malonate and serotonin while it reduced the relative concentration of histamine, propionate and numerous lipids. Piglets treated with colistin expressed lower levels of genes involved in innate immunity such as Toll-like receptor 4 (TLR4) and lysozyme (LYZ) in the colon epithelium. This gene expression pattern persisted in piglet colon organoids after two passages, indicating that the depletion of Proteobacteria and Fusobacteria in vivo imprinted the epithelial stem cells from which organoids were derived. In conclusion, an early life modification of the microbiota altered the metabolome, epithelial gene expression and imprinted intestinal stem cells in the colon of piglets. Additional studies will be required to unravel the underlying mechanisms and to evaluate the long-term consequences for gut health in piglets.

International audience; Plastic pollution in marine ecosystems constitutes an important threat to marine life. For vertebrates, macro/microplastics can obstruct and/or transit into the airways and digestive tract whereas nanoplastics (NPs; < 1000 nm) have been observed in non-digestive tissues such as the liver and brain. Whether NPs cross the intestinal epithelium to gain access to the blood and internal organs remains controversial, however. Here, we show directly NP translocation across the intestinal barrier of a fish, the European seabass, Dicentrarchus labrax, ex vivo. The luminal side of median and distal segments of intestine were exposed to fluorescent polystyrene NPs (PS-NPs) of 50 nm diameter. PS-NPs that translocated to the serosal side were then detected quantitatively by fluorimetry, and qualitatively by scanning electron microscopy (SEM) and pyrolysis coupled to gas chromatography and high-resolution mass spectrometry (Py-GC-HRMS). Fluorescence intensity on the serosal side increased 15–90 min after PS-NP addition into the luminal side, suggesting that PS-NPs crossed the intestinal barrier; this was confirmed by both SEM and Py-GC-HRMS. This study thus evidenced conclusively that NPs beads translocate across the intestinal epithelium in this marine vertebrate.

International audience; Introduction et but de l’étude: L’obésité et le surpoids sont associés à une inflammation de bas-grade en lien avec des perturbations de la barrière intestinale et du microbiote. Le maintien de l’homéostasie intestinale est soutenu par la fonction mitochondriale des cellules épithéliales intestinales (CEI), puisqu’elle fournit l’énergie nécessaire à l’absorption des nutriments, au renouvellement épithélial et au maintien de la barrière intestinale. Or, la consommation d’un régime obésogène est susceptible d’altérer la fonction mitochondriale, tel que cela a été montré au niveau hépatique. Le but de cette étude est d’évaluer si la consommation d’un régime obésogène altère la fonction mitochondriale des CEI de jéjunum chez la souris.Matériel et méthodes: Des souris mâles C57Bl/6J ont été nourries pendant 22 semaines avec un régime contrôle pauvre en lipides (CTRL, lipides=10% de l’énergie, N=9) ou un régime obésogène (WD, lipides=58% de l’énergie, et eau de boisson supplémentée en fructose et saccharose (42 g/L), N=8)). A l’issue du régime, le jéjunum a été prélevé et les CEI, sous forme de cryptes et de villosités, ont été isolées pour analyser la fonction mitochondriale par la technologie Seahorse® et expressions géniques et protéiques.Résultats et Analyse statistique: Les souris WD ont développé une obésité caractérisée par une augmentation de 50% du poids corporel (CTRL : 32,5±0,9 vs WD : 46,4±1,8 g, P