Tania Archbold

l-Tryptophan exhibits therapeutic function in a porcine model of dextran sodium sulfate (DSS)-induced colitis☆

Conventional therapies for the treatment of inflammatory bowel disease (IBD) have demonstrated limited efficacy and potential toxicity; therefore, there is a need for novel therapies that can safely and effectively treat IBD. Recent evidence has indicated that amino acids may play a role in maintaining gut health. L-tryptophan has been shown to reduce oxidative stress and improve neurological states. The objective of this study was to assess the therapeutic effects of L-tryptophan in a porcine model of dextran sodium sulfate (DSS)-induced colitis. DSS was administered to piglets via intragastric catheter for 5 days followed by tryptophan administration at 80% of the daily recommended intake. The severity of colitis was assessed macroscopically and histopathologically, and intestinal permeability was monitored in vivo by D-mannitol analysis. The effect of tryptophan on the local expression of key mediators of inflammation and IBD pathogenesis was examined at the protein and gene expression levels. Supplementation with tryptophan ameliorated clinical symptoms and improved weight gain to feed intake conversion ratios. Histological scores and measurements were also improved, and gut permeability was notably reduced in tryptophan-supplemented animals. Moreover, tryptophan reduced the expression of the pro-inflammatory cytokines tumor necrosis factor-alpha, interleukin (IL)-6, interferon (IFN)-gamma, IL-12p40, IL-1beta and IL-17, as well as IL-8 and intracellular adhesion molecule-1, and resulted in increased expression of apoptosis initiators caspase-8 and Bax. These results demonstrate that L-tryptophan supplementation can reduce inflammation and enhance the rate of recovery in DSS-induced colitis and may be an effective immunomodulating agent for the treatment of IBD.

L-cysteine supplementation attenuates local inflammation and restores gut homeostasis in a porcine model of colitis

BACKGROUND Inflammatory bowel disease (IBD), a chronic inflammation of the gastrointestinal tract, is characterized by a deregulation of the mucosal immune system and resistance of activated T cells to apoptosis. Current therapeutics show limited efficacy and potential toxicity; therefore there is a need for novel approaches for the treatment of IBD. L-cysteine was examined for its ability to reduce colitis symptoms and modulate local gene expression in a DSS-induced porcine model of colitis. METHODS Colitis was induced via intra-gastric infusion of dextran sodium sulfate (DSS), followed by the administration of L-cysteine or saline. Clinical signs, morphological measurements, histology and gut permeability were assessed for the prognosis of colitis. Local tissue production of cytokines and gene expression in the colon were analyzed by ELISA and real-time RT-PCR. RESULTS L-cysteine supplementation attenuated DSS-induced weight loss and intestinal permeability, reduced local chemokine expression and neutrophil influx, and markedly improved colon histology. Furthermore, cysteine significantly reduced the expression of pro-inflammatory cytokines, including TNF-alpha, IL-6, IL-12p40, IL-1beta, and resulted in increased expression of the apoptosis initiator caspase-8 and decreased expression of the pro-survival genes cFLIP and Bcl-xL. CONCLUSIONS AND GENERAL SIGNIFICANCE These results suggest that L-cysteine administration aids in restoring gut immune homeostasis by attenuating inflammatory responses and restoring susceptibility of activated immune cells to apoptosis, and that cysteine supplementation may be a novel therapeutic strategy for the treatment of IBD.

Hen egg lysozyme attenuates inflammation and modulates local gene expression in a porcine model of dextran sodium sulfate (DSS)-induced colitis.

Inflammatory bowel disease (IBD) is a chronic and recurring inflammation of the gastrointestinal tract, associated with a dysregulation of the mucosal immune system. There is an increasing prevalence of IBD; however, current pharmaceutical treatments are only moderately effective and have been associated with potential long-term toxicity. Lysozyme, a well-known antimicrobial protein found in large quantities in hen egg white, is a promising alternative for the treatment of IBD. A porcine model of dextran sodium sulfate (DSS)-induced colitis was used to examine the effect of hen egg lysozyme (HEL) supplementation on intestinal inflammation. Treatment with DSS resulted in weight loss, severe mucosal and submucosal inflammation, colonic crypt distortion, muscle wall thickening, down-regulation of mucin gene expression, and increased gastric permeability, but these symptoms were attenuated following supplementation with HEL and restored to basal levels observed in untreated control animals. Treatment with HEL also significantly reduced the local expression of pro-inflammatory cytokines TNF-alpha, IL-6, IFN-gamma, IL-8, and IL-17 while increasing the expression of the anti-inflammatory mediators IL-4 and TGF-beta, indicating that HEL may function as a potent anti-inflammatory and immunomodulator. Furthermore, the concomitant increases in TGF-beta and Foxp3 levels suggest that HEL may aid in restoring gut homeostasis by activating regulatory T cells, which are important in the regulation of the mucosal immune system. These results suggest that HEL is a promising novel therapeutic for the treatment of IBD.

Early Weaning Reduces Small Intestinal Alkaline Phosphatase Expression in Pigs

Expression of the small intestinal alkaline phosphatase (IAP) is enterocyte differentiation dependent and plays essential roles in the detoxification of pathogenic bacterial lipopolysaccharide endotoxin, maintenance of luminal pH, organic phosphate digestion, and fat absorption. This study was conducted to examine the effect of early weaning on adaptive changes in IAP digestive capacity (V(cap)) and IAP gene expression compared with suckling counterparts in pigs at ages 10-22 d. Weaning decreased (P < 0.05) IAP enzyme affinity by 26% and IAP maximal enzyme activity by 22%, primarily in the jejunal region, with the jejunum expressing 84-86% of the whole gut mucosal IAP V(cap) [mol/(kg body weight.d)]. The majority (98%) of the jejunal mucosal IAP maximal activity was associated with the apical membrane and the remaining (2%) existed as the intracellular soluble IAP. Weaning reduced the abundance of the 60-kDa IAP protein associated with the proximal jejunal apical membrane by 64% (P < 0.05). Furthermore, weaning reduced (P < 0.05) the relative abundance of the proximal jejunal IAP mRNA by 58% and this was in association with decreases (P < 0.05) in the abundances of cytoplasmic (27%) and nuclear (29%) origins of IAP caudal-associated homeobox transcription factor 1. In conclusion, early weaning decreased small intestinal IAP V(cap), IAP catalytic affinity, and IAP gene expression, and this may in part contribute to the susceptibility of early-weaned piglets to increased occurrence of enteric diseases and growth-check.

Consumption of guar gum and retrograded high-amylose corn resistant starch increases IL-10 abundance without affecting pro-inflammatory cytokines in the colon of pigs fed a high-fat diet.

Increases in dietary intake of viscous and nonviscous soluble fiber are reported to improve bowel health. However, related biological mechanisms are not very clear. This study was conducted to examine if colonic inflammation would occur in a typical Western diet model and determine if consumption of soluble fiber components would attenuate potential detrimental effects by differentially affecting colonic abundances of anti-inflammatory cytokine IL-10 and 2 pro-inflammatory cytokines tumor necrosis factor-alpha (TNF-α) and IL-6 in pigs fed a high-fat basal diet supplemented, respectively, with 15% viscous soluble fiber guar gum (GG) and 15% nonviscous soluble fiber, that is, retrograded high-amylose corn (Zea mays) resistant starch (RS). A total of 24 Yorkshire growing barrows were assigned into a standard corn and soybean (Glycine max) meal (SBM)-based grower diet as a positive control (PC), an animal protein-based high-fat basal diet as the negative control (NC), and 2 NC basal diets supplemented with 15% GG and 15% RS, respectively, according to a completely randomized block design for 4 wk. Abundance of these cytokines in homogenized and extracted colonic tissue supernatant samples was measured by ELISA. Although colonic IL-10 abundance was lower (P < 0.05) in the corn and SBM-based PC group than that in the high-fat basal NC group, there were no differences (P > 0.05) in colonic abundances of TNF-α and IL-6 between NC and PC groups and among all of the treatment groups. Compared with the NC group, consumption of GG and RS at 15% increased (P < 0.05) colonic IL-10 abundance. Moreover, there was no difference (P > 0.05) in colonic IL-10 abundance between the 15% GG and the 15% RS groups. Thus, consumption of a typical high-fat Western diet did not induce colonic inflammation. Diets supplemented with 15% GG or 15% RS may protect the colon from developing inflammation by enhancing IL-10 abundance.

The in vivo infusion of hydrogen peroxide induces oxidative stress and differentially affects the activities of small intestinal carbohydrate digestive enzymes in the neonatal pig.

Chronic fatigue syndrome (CFS) is characterized by persistent and relapsing fatigue that involves oxidative stress in its pathogenesis. We tested the hypothesis that a decrease in key carbohydrate-digesting enzyme activity in the gut is one of the major biological mechanisms of developing CFS in liquid formula-fed neonatal pigs with in vivo infusion of H(2)O(2). Piglets at 7 to 10 d of age were fitted with an intraperitoneal catheter, allowed a 3-d post surgical recovery, and infused with either H(2)O(2) at 5 mmol/kg BW (PER; n = 8) or the same volume of saline (CON; n = 8) in six 20-ml doses daily for a period of 10 d. During this period, animal behavior was monitored, blood samples collected, and jejunal enzyme activity kinetic experiments for lactase, sucrase, maltase, and maltase-glucoamylase were conducted. Plasma concentration of reduced glutathione remained similar (P > 0.05) to the pre-infusion level over the study duration in the CON group whereas this was 65% lower (P < 0.05) than the pre-infusion level in the PER group. Piglets experiencing oxidative stress had an overall lower (P < 0.05) physical mobility and the maximal jejunal specific activities [μmol/(mg protein · min)] for lactase (PER, 6.54 ± 0.68 vs. CON, 12.65 ± 0.69) and maltase (PER, 57.39 ± 1.02 vs. CON, 75.60 ± 1.04), respectively. However, differences were not observed (P > 0.05) in the maximal specific activities [μmol/(mg protein · min)] of sucrase (PER, 10.50 ± 1.37 vs. CON, 12.40 ± 1.55) and maltase-glucoamylase (PER, 0.71 ± 0.08 vs. CON, 0.70 ± 0.07) between the 2 groups. In conclusion, infusion of a suitable dose of H(2)O(2) induced CFS in the neonatal pigs. Oxidative stress in vivo differentially affected the maximal activities of important small intestinal carbohydrate-digesting enzymes in neonatal pigs fed a dairy milk-based liquid formula.

The small intestinal apical hydrolase activities are decreased in the piglet with bowel inflammation induced by dextran sodium sulfate1

Inflammatory bowel disease (IBD) is characterized by cramping, abdominal pain, bloating, constipation, and diarrhea. We tested the hypothesis that compromised activities of the major small intestinal apical hydrolases contribute to the symptoms of IBD. Changes in hydrolytic kinetics, target protein abundances, and mRNA expression of intestinal alkaline phosphatase (IAP), lactase, maltase, sucrase-isomaltase (SI), maltase-glucoamylase (MGA), and aminopeptidase N (APN) in piglets with colonic inflammation chemically induced by dextran sodium sulfate (DSS) were investigated. Yorkshire piglets at 5 d of age, with an average initial BW of about 3 kg, were fitted with intragastric catheters and were divided into control (CON; n = 6) and treatment groups (DSS; n = 5). Both groups were infused with an equal volume of either saline or 1.25 g of DSS · kg BW(-1) · d(-1) in saline, respectively, for 10 d. Enzyme kinetic experiments for IAP, lactase, maltase, SI, MGA, and APN were measured at 37°C with isolated proximal jejunal apical membrane. Target hydrolase protein abundances in the apical membrane were analyzed by Western blotting and their mRNA abundances in the jejunum were measured by quantitative real-time reverse transcription (RT-) PCR with β-actin as the housekeeping gene. Expressed as percentage of the CON, DSS treatment decreased (P < 0.05) the maximal specific activities of IAP (53%), lactase (78%), maltase (56%), SI (72%), MGA (29%), and APN (22%) as well as the target hydrolase protein abundances of IAP (39%), lactase (35%), SI (36%), and APN (54%), respectively. Decreases (P < 0.05) in the mRNA abundances (% of the CON) for lactase (25%), SI (52%), MGA (75%), and APN (39%) were observed in the DSS group. However, DSS treatment increased (P < 0.05) the jejunal IAP mRNA abundance by 3.5 fold. We conclude that decreases in the small intestinal apical activities of these examined hydrolases likely contribute to overgrowth of pathogenic bacterial populations in the distal small intestine and the colon, leading to the pathogenesis of IBD.

Effects of dietary true digestible calcium to phosphorus ratio on growth performance and efficiency of calcium and phosphorus use in growing pigs fed corn and soybean meal-based diets

Objectives of this study were to determine effects of dietary true fecal digestible Ca to true digestible P ratio on growth performance and efficiency of Ca and P use in growing pigs fed corn (Triticum aestivum)-soybean (Glycine max) meal (SBM)-based diets. Experiment 1 was carried out to measure true fecal digestibility of Ca and P as well as the fecal endogenous outputs of these nutrients associated with a corn and SBM-based diet in 12 Yorkshire growing pigs with an average initial BW of 23.2 ± 0.6 kg by the substitution method. True fecal digestibility values (%; n = 6) of Ca (53.6 ± 12.7) and P (43.8 ± 16.7) as well as the fecal endogenous outputs (g/kg DMI; n = 12) of Ca (0.91 ± 0.20) and P (1.31 ± 0.15) associated with the diets were determined. Experiment 2 was conducted with 36 Yorkshire barrows of an average initial BW of 24.2 ± 0.6 kg and the pigs were fed 6 diets according to a completely randomized block design. The 6 diets were corn and SBM based with diet 1 containing 0.2% true digestible Ca and 0.3% true digestible P and were formulated to contain 6 total Ca to total P ratios based on analyzed dietary Ca and P contents (diet 1, 0.6:1; diet 2, 0.7:1; diet 3, 0.8:1; diet 4, 1.3:1; diet 5, 1.0:1; and diet 6, 1.3:1) by supplementing gradient levels of limestone with a constant dietary P content for meeting the recommended requirement. Changes in the dietary Ca to P ratio had no effects (P > 0.05) on ADG. No differences (P > 0.05) in ADFI were observed between the other diets except the lower ADFI (P < 0.05) in diet 3 compared with diet 2. However, G:F was higher (P < 0.05) in diet 2 compared with diets 5 and 6. Changes in the dietary Ca to P ratio had consistent effects on true fecal P digestibility and retention with much lower values (P < 0.05) observed in diet 5 in comparison with the other diets. In summary, true fecal digestible Ca to P ratios of 0.9:1 to 1.0:1 were associated with optimal responses in both G:F as well as true fecal P digestibility and retention in growing pigs fed corn and SBM-based diets.

Responses of dietary ileal amino acid digestibility to consumption of different cultivars of potatoes and conventional fibers in grower pigs fed a high-fat basal diet1

Whereas dietary fibers are well recognized for nutritional management of human health issues, fiber is also known to be one of the dietary factors potentially affecting digestive use of dietary proteins. As a staple food, potato (Solanum tuberosum) may be a significant dietary fiber source. The objective of this study was to examine effects of dietary supplementation of six potato cultivar-genotype samples that differ in soluble fiber content and two conventional fiber components (i.e., cellulose and guar gum) on the apparent ileal AA digestibility in pigs fed a high-fat basal diet. The basal diet was formulated as a zero-fiber negative control (NC) to contain 41.5% poultry meal, 4% casein, 15% animal fat-oil blend, 2.8% sucrose, 31% corn (Zea mays) starch, 0.50% salt, and 0.40% trace mineral-vitamin supplement with fat contributing to 47% of the dietary GE. The two fiber diets were formulated by respectively diluting the basal diet with 10% guar gum and 10% cellulose at the expense of corn starch. Six other test diets were formulated by including 8.5% guar gum and further diluting the basal diet with 25.1% one of the six cultivar-genotype samples of dehydrated potato tuber powder to contain about 10% total dietary fiber at the expense of corn starch. Eighty-one 25-kg barrows were fitted with a simple T-cannula at the distal ileum and fed the diets according to a completely randomized block design with each block lasting 28 d. Compared with the NC, the ileal digestibility of Ala, Gly, and Pro were decreased (P < 0.05) by 10% guar gum whereas the digestibility of Gly was reduced (P < 0.05) by 10% cellulose. The ileal digestibility of several AA was decreased (P < 0.05) by the test potatoes plus 8.5% guar gum compared with the NC. Our results suggest that dietary inclusion of fiber at 10% from guar gum and cellulose and contributed by potatoes may adversely affect digestive use of dietary protein.

Effect of milk protein composition of a model infant formula on the physicochemical properties of in vivo gastric digestates

We investigated the effect of protein composition and, in particular, the presence of whey proteins or β-casein on the digestion behavior of a model infant formula using an in vivo piglet model. Three isocaloric diets optimized for piglets were prepared with the same concentrations of protein. For protein source, 1 diet contained only whey proteins and 2 contained a casein:whey protein ratio of 40:60 but differed in the amount of β-casein. To obtain the desired protein compositions, skim milk was microfiltered at 7 or 22°C, and retentates and permeates were combined with whey protein isolate. The diets were optimized to the nutritional needs of the piglets and fed to 24 newborn piglets for 18 d. Eight piglets were also fed ad libitum with sow milk and considered only as reference (not included in the statistical analysis). The study was carried out in 2 blocks, killing the animals 60 and 120 min after the last meal. All gastric contents, regardless of diet, showed a wide range of pH. Postprandial time did not affect the pH or physical properties of the gastric digesta. The digesta from whey protein-casein formulas showed significantly higher viscosity, a higher storage modulus, and a denser microstructure than digesta obtained from piglets fed whey protein formula. The β-casein:total casein ratio at the level used in this study did not significantly affect the physical and chemical properties of the stomach digestate. Although caseins showed extensive gastric hydrolysis, whey proteins remained largely intact at both postprandial times. The results indicate that the presence of different concentrations of milk proteins can be critical to the digestion properties of the food matrix and may affect the nutritional properties of the components.