Jeroen Degroote

Arabinoxylan in Wheat Is More Responsible Than Cellulose for Promoting Intestinal Barrier Function in Weaned Male Piglets

BACKGROUND The effect of dietary fiber on intestinal function primarily has been ascribed to its interaction with intestinal bacteria in the hindgut, whereas changes in intestinal bacteria in the host have been considered to depend on fiber composition. OBJECTIVES The objectives of this study were to determine the contribution of the major fiber components to the health-promoting effects of wheat bran on intestinal mucosal barrier function and to elucidate the involvement of microbiota changes in weaned piglets. METHODS Thirty freshly weaned male piglets were assigned to 5 dietary treatment groups (n = 6) according to litter and weight. The piglets consumed synthetic diets ad libitum for 30 d, including a basal control diet (CON) without fiber components, a wheat bran diet (WB) as reference diet (10% wheat bran), and 3 other diets containing amounts of fiber components equivalent to those in the WB, i.e., an arabinoxylan diet (AX), a cellulose diet (CEL), and a combined arabinoxylan and cellulose diet (CB). RESULTS The groups consuming diets containing arabinoxylans (i.e., the WB, AX, and CB groups) had increased intestinal secretory immunoglobulin A concentrations, goblet cell number and cecal short-chain fatty acid concentrations, and reduced branched-chain fatty acid concentrations and pH values compared with the CON group. In the WB group, the stimulated secretion of Cl(-) was suppressed (60.8% and 47.5% change in short-circuit current caused by theophylline and carbachol, respectively) in the distal small intestine compared with the CON group. The AX and CB groups also had increased intestinal alkaline phosphatase activities and reduced intestinal transcellular permeability (by 77.3% and 67.2%, respectively) compared with the CON group. Meanwhile, in the WB group, cecal Bacteroidetes and Enterobacteriaceae populations were lower, and the growth of Lactobacillus was higher in the AX and CB groups than in the CON group, whereas no positive effect on intestinal barrier function was observed in the CEL group. CONCLUSION Arabinoxylan in wheat bran, and not cellulose, is mainly responsible for improving various functional components of the intestinal barrier function and the involvement of microbiota changes.

Intrauterine growth restriction in neonatal piglets affects small intestinal mucosal permeability and mRNA expression of redox-sensitive genes

Neonates with intrauterine growth restriction (IUGR) show lower efficiency of nutrient utilization compared to normal birth weight (NBW) newborns. This study was conducted using neonatal piglets as a model to test the hypothesis that IUGR affects the intestinal barrier function, intestinal structure, and antioxidant system development during the suckling period. The small intestinal mucosae were obtained from IUGR and NBW littermates in the suckling period (d 0, 3, 8, and 19 postnatal). The epithelial barrier function was assessed by FITC‐dextran 4 (FD4) and horseradish peroxidase (HRP) fluxes across the epithelium, histomorphologic measurements, and expression of tight‐junction proteins. Redox status represented by the glutathione disulfide/glutathione ratio and malondialdehyde concentrations was determined, whereas mRNA expressions of some redox‐sensitive proteins were quantified. Results showed that IUGR piglets exhibited a 2‐fold higher intestinal permeability in the proximal small intestine on d 0 (P < 0.05), and this difference between IUGR and NBW piglets was widened to 3 and 4 times for FD4 and HRP, respectively (P< 0.05), on d 3. In accordance, expression of occludin was downregulated at the transcriptional level in IUGR piglets at d 0 and 19 (P < 0.01). Furthermore, the transcription of heme oxygenase 1, catalase, and thioredoxin reductase genes was downregulated in IUGR piglets, mainly on postnatal d 0 and 19 (P < 0.01). It appears that IUGR subjects have a lower capacity to mount an antioxidant response in the early postnatal period. Collectively, these results add to our understanding of the mechanisms responsible for intestinal dysfunction in IUGR neonates.—Wang, W., Degroote, J., Van Ginneken, C., Van Poucke, M., Vergauwen, H., Dam, T. M. T., Vanrompay, D., Peelman, L. J., De Smet, S., Michiels, J. Intrauterine growth restriction in neonatal piglets affects small intestinal mucosal permeability and mRNA expression of redox‐sensitive genes. FASEB J. 30, 863–873 (2016). www.fasebj.org

Association between heat stress and oxidative stress in poultry; mitochondrial dysfunction and dietary interventions with phytochemicals

Heat as a stressor of poultry has been studied extensively for many decades; it affects poultry production on a worldwide basis and has significant impact on well-being and production. More recently, the involvement of heat stress in inducing oxidative stress has received much interest. Oxidative stress is defined as the presence of reactive species in excess of the available antioxidant capacity of animal cells. Reactive species can modify several biologically cellular macromolecules and can interfere with cell signaling pathways. Furthermore, during the last decade, there has been an ever-increasing interest in the use of a wide array of natural feed-delivered phytochemicals that have potential antioxidant properties for poultry. In light of this, the current review aims to (1) summarize the mechanisms through which heat stress triggers excessive superoxide radical production in the mitochondrion and progresses into oxidative stress, (2) illustrate that this pathophysiology is dependent on the intensity and duration of heat stress, (3) present different nutritional strategies for mitigation of mitochondrial dysfunction, with particular focus on antioxidant phytochemicals.Oxidative stress that occurs with heat exposure can be manifest in all parts of the body; however, mitochondrial dysfunction underlies oxidative stress. In the initial phase of acute heat stress, mitochondrial substrate oxidation and electron transport chain activity are increased resulting in excessive superoxide production. During the later stage of acute heat stress, down-regulation of avian uncoupling protein worsens the oxidative stress situation causing mitochondrial dysfunction and tissue damage. Typically, antioxidant enzyme activities are upregulated. Chronic heat stress, however, leads to downsizing of mitochondrial metabolic oxidative capacity, up-regulation of avian uncoupling protein, a clear alteration in the pattern of antioxidant enzyme activities, and depletion of antioxidant reserves.Some phytochemicals, such as various types of flavonoids and related compounds, were shown to be beneficial in chronic heat-stressed poultry, but were less or not effective in non-heat-stressed counterparts. This supports the contention that antioxidant phytochemicals have potential under challenging conditions. Though substantial progress has been made in our understanding of the association between heat stress and oxidative stress, the means by which phytochemicals can alleviate oxidative stress have been sparsely explored.

Fermented liquid feed for pigs: an ancient technique for the future

Fermented liquid feed is feed that has been mixed with water at a ratio ranging from 1:1.5 to 1:4. By mixing with water, lactic acid bacteria and yeasts naturally occurring in the feed proliferate and produce lactic acid, acetic acid and ethanol which reduces the pH of the mixture. This reduction in pH inhibits pathogenic organisms from developing in the feed. In addition, when this low pH mixture is fed, it reduces the pH in the stomach of pigs and prevents the proliferation of pathogens such as coliforms and Salmonella in the gastrointestinal tract. For piglets, the use of fermented liquid feed offers the possibility of simultaneously providing feed and water, which may facilitate an easier transition from sow’s milk to solid feed. Secondly, offering properly produced fermented liquid feed may strengthen the role of the stomach as the first line of defense against possible pathogenic infections by lowering the pH in the gastrointestinal tract thereby helping to exclude enteropathogens. Finally, feeding fermented liquid feed to pigs has been shown to improve the performance of suckling pigs, weaner pigs and growing-finishing pigs. In this review, current knowledge about the use of fermented liquid feed in pig diets will be discussed. This will include a discussion of the desirable properties of fermented liquid feed and factors affecting fermentation. In addition, advantages and disadvantages of fermented liquid feed will be discussed including its effects on gastrointestinal health, intestinal pH and the types of bacteria found in the gastrointestinal tract as well as the effects of fermented liquid feeds on pig performance.

Trolox and Ascorbic Acid Reduce Direct and Indirect Oxidative Stress in the IPEC-J2 Cells, an In Vitro Model for the Porcine Gastrointestinal Tract

Oxidative stress in the small intestinal epithelium is a major cause of barrier malfunction and failure to regenerate. This study presents a functional in vitro model using the porcine small intestinal epithelial cell line IPEC-J2 to examine the effects of oxidative stress and to estimate the antioxidant and regenerative potential of Trolox, ascorbic acid and glutathione monoethyl ester. Hydrogen peroxide and diethyl maleate affected the tight junction (zona occludens-1) distribution, significantly increased intracellular oxidative stress (CM-H2DCFDA) and decreased the monolayer integrity (transepithelial electrical resistance and FD-4 permeability), viability (neutral red) and wound healing capacity (scratch assay). Trolox (2 mM) and 1 mM ascorbic acid pre-treatment significantly reduced intracellular oxidative stress, increased wound healing capacity and reduced FD-4 permeability in oxidatively stressed IPEC-J2 cell monolayers. All antioxidant pre-treatments increased transepithelial electrical resistance and viability only in diethyl maleate-treated cells. Glutathione monoethyl ester (10 mM) pre-treatment significantly decreased intracellular oxidative stress and monolayer permeability only in diethyl maleate-treated cells. These data demonstrate that the IPEC-J2 oxidative stress model is a valuable tool to screen antioxidants before validation in piglets.

Changes in the pig small intestinal mucosal glutathione kinetics after weaning

Glutathione (GSH) serves as a major endogenous antioxidant and its kinetics have been poorly described in the weaned pig. This study was to assess the effect of birth weight, sex, and days postweaning on the small intestine (SI) mucosal GSH kinetics. At weaning (18.8 ± 0.44 d) 34 pairs of intrauterine growth restricted (IUGR) and normal birth weight sex-matched littermates were selected and fed a starter diet ad libitum until 1 h before sampling at 0, 2, 5, 12 and 28 d postweaning. Mucosa was collected from 2 SI sites, at 5% and at 75% of total length, to determine GSH and glutathione disulfide (GSSG), glutathione peroxidase (GSH-Px) and malondialdehyde (MDA), and plasm GSH-Px and MDA. At both 5 and 75% of total length, the GSH-Px activity and GSH concentrations increased gradually with increasing days postweaning to peak at day 12 (P < 0.05). The GSH-Px activity and GSH concentrations at 5% of SI length were consistently higher as compared to 75% of SI length (e.g., at day 12, 43.2 and 28.9 units/mg protein and 21.5 and 15.4 μmol/g protein, respectively). The GSSG:GSH ratio at 5% of total length was 2-fold higher at day 5 compared to all other days (P < 0.05), possibly indicating that the mucosal redox balance was disturbed in that time window. The higher GSH-Px activity, GSH content, and GSSG:GSH ratio in the proximal SI might illustrate the higher need for antioxidant action at that site. Plasma MDA and GSH-Px activity followed a comparable pattern as in the small intestine.

In Vitro Investigation of Six Antioxidants for Pig Diets

Oxidative stress in the small intestinal epithelium can lead to barrier malfunction. In this study, the effect of rosmarinic acid (RA), quercetin (Que), gallic acid (GA), lipoic acid (LA), ethoxyquin (ETQ) and Se-methionine (SeMet) pre-treatments using 2 mM Trolox as a control on the viability and the generation of intracellular reactive oxygen species (iROS) of oxidatively (H2O2) stressed intestinal porcine epithelial cells (IPEC-J2) was investigated. A neutral red assay showed that RA (50–400 µM), Que (12.5–200 µM), GA (50–400 µM), ETQ (6.25–100 µM), and SeMet (125–1000 µM) pre-treatments but not LA significantly increased the viability of H2O2-stressed IPEC-J2 cells (p < 0.05). A 5-(and-6)-chloromethyl-2′,7′-dichlorodihydrofluorescein diacetate, acetyl ester (CM-H2DCFDA) fluorescent probe showed that RA (100–600 µM), Que (25–800 µM), ETQ (3.125–100 µM) and SeMet (500–2000 µM) pre-treatments significantly reduced iROS in IPEC-J2 monolayers (p < 0.05). Moreover, RA and Que were most effective in reducing iROS. Therefore, the effects of RA and Que on barrier functioning in vitro were examined. RA and Que pre-treatments significantly decreased fluorescein isothiocyanate (FITC)-conjugated dextran-4 (4 kDa) permeability and transepithelial electrical resistance (TEER) of an IPEC-J2 cell monolayer (p < 0.05). These in vitro results of RA and Que hold promise for their use as antioxidants in pig feed.