Comparing the intestinal transcriptome of Meishan and Large White piglets during late fetal development reveals genes involved in glucose and lipid metabolism and immunity as valuable clues of intestinal maturity

Background: Maturity of intestinal functions is critical for neonatal health and survival, but comprehensive description of mechanisms underlying intestinal maturation that occur during late gestation still remain poorly characterized. The aim of this study was to investigate biological processes specifically involved in intestinal maturation by comparing fetal jejunal transcriptomes of two representative porcine breeds (Large White, LW; Meishan, MS) with contrasting neonatal vitality and maturity, at two key time points during late gestation (gestational days 90 and 110). MS and LW sows inseminated with mixed semen (from breed LW and MS) gave birth to both purebred and crossbred fetuses. We hypothesized that part of the differences in neonatal maturity between the two breeds results from distinct developmental profiles of the fetal intestine during late gestation. Reciprocal crossed fetuses were used to analyze the effect of parental genome. Transcriptomic data and 23 phenotypic variables known to be associated with maturity trait were integrated using multivariate analysis with expectation of identifying relevant genes-phenotypic variable relationships involved in intestinal maturation. Results: A moderate maternal genotype effect, but no paternal genotype effect, was observed on offspring intestinal maturation. Four hundred and four differentially expressed probes, corresponding to 274 differentially expressed genes (DEGs), more specifically involved in the maturation process were further studied. In day 110-MS fetuses, Ingenuity® functional enrichment analysis revealed that 46% of DEGs were involved in glucose and lipid metabolism, cell proliferation, vasculogenesis and hormone synthesis compared to day 90-MS fetuses. Expression of genes involved in immune pathways including phagocytosis, inflammation and defense processes was changed in day 110-LW compared to day 90-LW fetuses (corresponding to 13% of DEGs). The transcriptional regulator PPARGC1A was predicted to be an important regulator of differentially expressed genes in MS. Fetal blood fructose level, intestinal lactase activity and villous height were the best predicted phenotypic variables with probes mostly involved in lipid metabolism, carbohydrate metabolism and cellular movement biological pathways. [b]Conclusions[/b]: Collectively, our findings indicate that the neonatal maturity of pig intestine may rely on functional development of glucose and lipid metabolisms, immune phagocyte differentiation and inflammatory pathways. This process may partially be governed by PPARGC1A

Saturated fatty acids differently affect mitochondrial function and the intestinal epithelial barrier depending on their chain length in the in vitro model of IPEC-J2 enterocytes

Introduction: Maintenance of the intestinal barrier mainly relies on the mitochondrial function of intestinal epithelial cells that provide ATP through oxidative phosphorylation (OXPHOS). Dietary fatty acid overload might induce mitochondrial dysfunction of enterocytes and may increase intestinal permeability as indicated by previous in vitro studies with palmitic acid (C16:0). Yet the impact of other dietary saturated fatty acids remains poorly described.Methods: To address this question, the in vitro model of porcine enterocytes IPEC-J2 was treated for 3 days with 250 µM of lauric (C12:0), myristic (C14:0), palmitic (C16:0) or stearic (C18:0) acids.Results and discussion: Measurement of the transepithelial electrical resistance, reflecting tight junction integrity, revealed that only C16:0 and C18:0 increased epithelial permeability, without modifying the expression of genes encoding tight junction proteins. Bioenergetic measurements indicated that C16:0 and C18:0 were barely β-oxidized by IPEC-J2. However, they rather induced significant OXPHOS uncoupling and reduced ATP production compared to C12:0 and C14:0. These bioenergetic alterations were associated with elevated mitochondrial reactive oxygen species production and mitochondrial fission. Although C12:0 and C14:0 treatment induced significant lipid storage and enhanced fusion of the mitochondrial network, it only mildly decreased ATP production without altering epithelial barrier. These results point out that the longer chain fatty acids C16:0 and C18:0 increased intestinal permeability, contrary to C12:0 and C14:0. In addition, C16:0 and C18:0 induced an important energy deprivation, notably via increased proton leaks, mitochondrial remodeling, and elevated ROS production in enterocytes compared to C12:0 and C14:0

The Level of Protein in Milk Formula Modifies Ileal Sensitivity to LPS Later in Life in a Piglet Model

Background: Milk formulas have higher protein contents than human milk. This high protein level could modify the development of intestinal microbiota, epithelial barrier and immune functions and have long-term consequences. Methodology/Principal findings: We investigated the effect of a high protein formula on ileal microbiota and physiology during the neonatal period and later in life. Piglets were fed from 2 to 28 days of age either a normoprotein (NP, equivalent to sow milk) or a high protein formula (HP, +40% protein). Then, they received the same solid diet until 160 days. During the formula feeding period ileal microbiota implantation was accelerated in HP piglets with greater concentrations of ileal bacteria at d7 in HP than NP piglets. Epithelial barrier function was altered with a higher permeability to small and large probes in Ussing chambers in HP compared to NP piglets without difference in bacterial translocation. Infiltration of T cells was increased in HP piglets at d28. IL-1b and NF-kappa B sub-units mRNA levels were reduced in HP piglets at d7 and d28 respectively; plasma haptoglobin also tended to be reduced at d7. Later in life, pro-inflammatory cytokines secretion in response to high doses of LPS in explants culture was reduced in HP compared to NP piglets. Levels of mRNA coding the NF-kappa B pathway sub-units were increased by the challenge with LPS in NP piglets, but not HP ones. Conclusions/Significance: A high protein level in formula affects the postnatal development of ileal microbiota, epithelial barrier and immune function in piglets and alters ileal response to inflammatory mediators later in life

Flexibility of the gut during the neonatal period: does it have consequences later in life?

Early life nutrition impacts durably several physiological and metabolic functions and is a risk factor for the development of metabolic disease in adults (obesity, type 2 diabetes, hypertension, …). This theory of nutritional imprinting or Developmental Origin of Health and Disease established by Barker in the late 80’s (1) has been reinforced by experimental data on organs and tissues directly involved in the pathophysiologyof the metabolic syndrome (liver, adipose tissue, pancreas…) (2). The gut has got little attention in this context so far. Yet, evidences for a role of the gut in the pathophysiology of metabolic diseases in adults, especially with gut microbiota and barrier function maladaptation to a high fat diet, have emerged (3-4). The structure of the gut microbiota is established and the mucosal immune system programed in early life. This postnataldevelopment is not hard-wired and is influenced by environmental and nutritional factors. Man can hypothesize that this flexibility in acquisition of the microbiota and education of the gut immune system in early life would be long-lasting and induce distinct response to a high fat diet later in life. There are already several evidences that early life environmental factors including stress such as maternal deprivation or chemical contaminants such as bisphenol A dramatically impact adult response to gut inflammation or visceral painful stimuli in models of inflammatory bowel disease and irritable bowel syndrome. Recently, evidences have also emerged that nutritional factors, including energy, fat and fatty acids, protein, and micronutrients imbalances during early life have remnant effects of gut function in adults with alterations in microbiota, intestinal barrier function and/or defense systems. Examples of such long-term effects on the gut will be provided, focusing on piglet model and adaptation to a high fat diet. Those emerging data challenges neonatal nutrition which, apart from its traditional role as a supplier of building blocks for growth, may play another, yet potentially crucial role in shaping theindividual’s future life, impinging on the risk of disease decades later on

The Ussing chamber technique to evaluate alternatives to in-feed antibiotics for young pigs

The recent ban of in-feed antibiotics in animal production has brought scientists to find alternatives to in-feed antibiotics. The Ussing chamber is an in vitro technique in which intestinal tissue is collected and immediately mounted as a flat sheet between two half-chambers, establishing a luminal and a serosal side. This technique allows the measurement of actively transported ions as well as the permeability of the tissues, two parameters relevant for the evaluation of gut health. Ussing chambers have been used to describe the changes of intestinal physiology occurring at weaning. We observed that weaning induces an acute alteration of the epithelial barrier function and electrolyte transport in the first days. Long-lasting modifications (15 days after weaning) have also been observed. Alternatives to in-feed antibiotics can be evaluated by studying the intestinal physiology of animals treated with those alternatives. A benefic effect of pro- and pre-biotics on the rat intestine, human biopsies or epithelial cell monolayers has been demonstrated using Ussing chambers. In pigs, the influence of the source of dietary ingredients or the physical form of the diet seems limited. A few results obtained in pigs with pre- or probiotics appear less convincing than in laboratory animals. Another way to use Ussing chambers is to incubate the intestinal tissue with different substances added directly into the chambers. Some substances can be detrimental to the intestine, inducing electrolyte secretion or decreasing barrier function. However, some substances show a beneficial effect. Although this approach has limits and should be combined with in vivo measurements, it constitutes a rapid way to evaluate the effect of substances on intestinal physiology and can also, at least partly, elucidate the mechanisms of action of those alternatives.Utilisation de la technique des chambres d’Ussing pour l’évaluation d’alternatives aux antibiotiques dans l’alimentation des porcelets. L’interdiction récente de l’utilisation d’antibiotiques dans l’alimentation animale a conduit les scientifiques à trouver des alternatives à ces pratiques d’élevage. La technique des chambres d’Ussing est une technique in vitro dans laquelle des sections d’intestin sont collectées et immédiatement montées entre deux demi-chambres, établissant ainsi un compartiment séreux et un compartiment muqueux. Ceci permet la mesure des transports actifs d’ions ainsi que de la perméabilité du tissu, deux paramètres intéressants dans l’évaluation de la santé du tube digestif. Les chambres d’Ussing ont été utilisées pour décrire les perturbations intestinales au moment du sevrage. Nous avons ainsi pu montrer que le sevrage induit des altérations transitoires de la physiologie intestinale ainsi que des modifications à plus long terme. Les alternatives aux antibiotiques peuvent être évaluées par l’étude de la physiologie intestinale des animaux traités avec ces alternatives. Un effet bénéfique des pro- et prébiotiques sur l’intestin de rat, des biopsies intestinales humaines ou des monocouches de cellules épithéliales intestinales a été démontré en chambres d’Ussing. Chez le Porc, l’influence des sources de matières premières ou de la forme physique de l’aliment semble limitée. De plus, les rares résultats obtenus chez le porc quant à l’effet des pré- et probiotiques semblent moins convaincants que chez les animaux de laboratoire. Une autre façon d’utiliser les chambres d’Ussing est d’incuber l’intestin avec différentes substances ajoutées directement dans les chambres. Certains composés semblent avoir un effet délétère sur l’intestin, induisant des sécrétions d’électrolytes ou des modifications de la barrière épithéliale. Cependant, certaines substances ont montré un effet bénéfique. Bien que cette technique ait des limites et doive être combinée à des expérimentations in vivo, elle constitue un moyen rapide d’évaluer l’effet de certains composés sur la physiologie intestinale tout en permettant d’élucider une partie des mécanismes mis en jeu

L’augmentation progressive de la perméabilité colique transcellulaire mais pas paracellulaire est corrélée à l’endotoxémie et l’adiposité chez le rat obèse

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Impact of nutrition and microbiota on intestinal barrier function development and consequences later in life

Impact of nutrition and microbiota on intestinal barrier function development and consequences later in life. SFB Summer Schoo