Mechanism of iron on the intestinal epithelium development in suckling piglets.

This study aimed to investigate the mechanism of iron on intestinal epithelium development of suckling piglets. Compared with newborn piglets, 7-day-old and 21-day-old piglets showed changes in the morphology of the jejunum, increased proliferation, differentiated epithelial cells, and expanded enteroids. Intestinal epithelium maturation markers and iron metabolism genes were significantly changed. These results suggest that lactation is a critical stage in intestinal epithelial development, accompanied by changes in iron metabolism. In addition, deferoxamine (DFO) treatment inhibited the activity of intestinal organoids at passage 4 (P4) of 0-day-old piglets, but no significant difference was observed in epithelial maturation markers at passage 1 (P1) and P4, and only argininosuccinate synthetase 1 (Ass1) and ß-galactosidase (Gleb) were up-regulated at passage 7 (P7). These results in vitro show that iron deficiency may not directly affect intestinal epithelium development through intestinal stem cells (ISCs). The iron supplementation significantly down-regulated the mRNA expression of interleukin-22 receptor subunit alpha-2 (IL-22RA2) in the jejunum of piglets. Furthermore, the mRNA expression of IL-22 in 7-day-old piglets was significantly higher than that in 0-day-old piglets. Adult epithelial markers were significantly up-regulated in organoids treated with recombinant murine cytokine IL-22. Thus, IL-22 may play a key role in iron-affecting intestinal epithelium development.

Biosynthetic Gene Clusters from Swine Gut Microbiome.

The abuse of antibiotics has become a serious health challenge in the veterinary field. It creates environmental selection pressure on bacteria and facilitates the rapid spread of antibiotic resistance genes. The speed of discovery and application of cost-effective alternatives to antibiotics is slow in pig production. Natural products from biosynthetic gene clusters (BGCs) represent promising therapeutic agents for animal and human health and have attracted extraordinary passion from researchers due to their ability to participate in biofilm inhibition, stress resistance, and the killing of competitors. In this study, we detected the presence of diverse secondary metabolite genes in porcine intestines through sequence alignment in the antiSMASH database. After comparing variations in microbial BGCs' composition between the ileum and the colon, it was found that the abundance of the resorcinol gene cluster was elevated in the ileal microbiome, whereas the gene cluster of arylpolyene was enriched in the colonic microbiome. The investigation of BGCs' diversity and composition differences between the ileal and colonic microbiomes provided novel insights into further utilizing BGCs in livestock. The importance of BGCs in gut microbiota deserves more attention for promoting healthy swine production.

Effects of ß-alanine on intestinal development and immune performance of weaned piglets.

Beta-alanine is an important amino acid involved in several metabolic reactions in the body. The study aimed to investigate the effect of ß-alanine supplementation on intestinal development and the immune performance of weaned piglets. Thirty-two 21-day-old healthy weaned piglets (half female and half male; Duroc × Landrace × Yorkshire) with an initial body weight of 8.11 ± 0.21 kg were randomly divided into 4 groups with 8 replicates of 1 pig each. The control group was fed a basal diet and the three experimental treatment groups were fed diets supplemented with 300, 600 and 1,200 mg/kg ß-alanine, respectively. The trial lasted 28 days and the diets fed were divided into 2 phases: the late lactation period (day 1 to 14) and the nursery period (day 15 to 28), during which the weaned piglets had free access to food and water. The regulatory effects of ß-alanine were further investigated in vitro using organoids obtained from the jejunum of piglets. In vivo, the addition of ß-alanine to the diet had no significant effect on the growth performance of weaned piglets (P > 0.05), but significantly reduced serum levels of immunoglobulin G (IgG) (P < 0.01), immunoglobulin M (IgM) (P = 0.005), and complement 3 (C3) (P = 0.017). The serum interleukin- 6 (IL-6) levels (P < 0.01) were significantly reduced in the 1,200 mg/kg treatment group. The addition of ß-alanine increased ileal villus height, with the most significant effect at a concentration of 300 mg/kg (P = 0.041). The addition of 600 mg/kg ß-alanine significantly up-regulated the expression of superoxide dismutase (SOD) activity (P = 0.020) and the zonula occludens-1 (ZO-1) gene (P = 0.049) in the jejunum. Diets supplemented with 300 mg/kg ß-alanine significantly increased the number of Ki67 positive cells in the jejunal crypts (P < 0.01). In vitro, ß-alanine increased the organoid budding rates (P = 0.001) and the budding height of the crypt significantly (P = 0.004). In conclusion, ß-alanine can improve intestinal morphology and barrier function, reduce inflammatory responses and alleviate the adverse effects of weaning stress on piglet intestinal health.

Tannic acid attenuates intestinal oxidative damage by improving antioxidant capacity and intestinal barrier in weaned piglets and IPEC-J2 cells.

Tannic acid (TA) has received widespread attention for its beneficial biological function with antioxidant capacity. This study investigated the protective role of TA on the intestinal antioxidant capacity and intestinal barrier in weaned piglets and porcine intestinal epithelial cells (IPEC-J2). A total of 18 weaned piglets were randomly allocated into two groups (n = 9) and fed with a basal diet (control, CON) and a basal diet containing 1,000 mg/kg TA for two weeks. The in vivo results showed that treatment with TA increased both glutathione peroxidase (GSH-PX) activity and the protein expression of ZO-1 in the jejunum of weaned piglets, and reduced the level of malondialdehyde (MDA) in the serum and the mRNA and protein expression of Keap1 in the jejunum of weaned piglets. Furthermore, in vitro results indicated that TA treatment effectively alleviated tert-butyl hydroperoxide (TBH)-induced oxidative stress in IPEC-J2 cells, improved the antioxidant capacity by elevating the cell redox state and activating the Nrf2 pathway, and improved the intestinal barrier by upregulating the mRNA and protein expression of intestinal tight junction proteins and increasing the transepithelial electrical resistance (TEER) value. In conclusion, these results confirmed that TA relieves oxidative injury and improves intestinal barrier function and intestinal antioxidant capacity by activating the Nrf2 signaling pathway. These findings suggest that TA has the potential application in alleviating oxidative stress in the intestine of weaned piglets.

Effect of Different Levels of Niacin on Serum Biochemical Parameters, Antioxidant Status, Cytokine Levels, Inflammatory Gene Expression and Colonic Microbial Composition in Weaned Piglets.

Niacin plays an important role in regulating the gut health of weaned piglets. In this study, 48 25-day-old weaned piglets (7.9 ± 0.20 kg) produced by 14 sows (3 to 4 piglets per sow) were randomly divided into 4 groups with 6 replicates in each group and 2 piglets in each replicate. Each group was fed diets supplemented with 22.5 (N1), 30 (N2), 45 (N3), and 75 (N4) mg/kg of niacin, respectively. Samples were taken at 7 and 14 d, respectively. The study shows that changes in niacin levels significantly affected the content of IgG and IgM in the serum (p < 0.05). Niacin had a significant effect on antioxidant parameters such as MDA, T-SOD, and CuZn-SOD in the jejunal mucosa of weaned piglets (p < 0.05). Moreover, significant differences were observed in the expression of cytokines such as TGF-ß, TNF-α, and COX2 in the jejunal mucosa (p < 0.05). The 16S rRNA sequencing analysis showed that there were significant differences in the colonic species composition, which were also accompanied by changes in the isovaleric acid content (p < 0.05). In conclusion, an appropriate increase in niacin dose based on NRC (2012) has an important role in improving the antioxidant status of weaned piglets, alleviating intestinal inflammation in piglets, improving immunity, and regulating the structure of the microbiota.

Dietary High Dose of Iron Aggravates the Intestinal Injury but Promotes Intestinal Regeneration by Regulating Intestinal Stem Cells Activity in Adult Mice With Dextran Sodium Sulfate-Induced Colitis.

The effects of excessive dietary iron intake on the body have been an important topic. The purpose of this study was to investigate the effects of high-dose iron on intestinal damage and regeneration in dextran sodium sulfate (DSS)-induced colitis model mice. A total of 72 8-week-old adult C57BL/6 mice were randomly divided into two dietary treatment groups: the basal diet supplemented with 45 (control) and 450 mg/kg iron (high-iron) from ferrous sulfate. The mice were fed different diets for 2 weeks, and then 2.5% DSS was orally administered to all mice for 7 days. Samples of different tissues were collected on days 0, 3, and 7 post administration (DPA). High-iron treatment significantly decreased the relative weight of the large intestine at 7 DPA but not at 0 DPA or 3 DPA. High dietary iron increased the jejunal villus width at 0 DPA, decreased the villus width and the crypt depth of the jejunum at 3 DPA, and decreased the number of colonic crypts at 7 DPA. Meanwhile, high dietary iron decreased the number of goblet cells in the jejunal villi and the Paneth cells in the jejunal crypts at 0 DPA, increased the number of goblet cells per crypt of the colon at 3 DPA, and the number of Paneth cells in the jejunal crypts, the goblet cells in the colon, the Ki67-positive proliferating cells in the colon, and the Sex-determining region Y-box transcription factor 9+ (SOX9) cells in the jejunum crypts and colon at 7 DPA. The organoid formation rate was increased by high-iron treatments at 3 DPA and 7 DPA. High dietary iron treatment decreased the mRNA level of jejunal jagged canonical Notch ligand 2 (Jag-2) at 0 DPA and bone morphogenetic protein 4 (Bmp4) and neural precursor cell-expressed developmentally downregulated 8 (Nedd8) in the jejunum and colon at 7 DPA, whereas it increased the mRNA expression of the serum/glucocorticoid-regulated kinase 1 (Sgk1) in the colon at 3 DPA. The results suggested that a high dose of iron aggravated intestinal injury but promoted intestinal repair by regulating intestinal epithelial cell renewal and intestinal stem cell activity in adult mice with colitis.

Changes in progenitors and differentiated epithelial cells of neonatal piglets.

This study aimed to assess the changes of small intestinal morphology, progenitors, differentiated epithelial cells, and potential mechanisms in neonatal piglets. Hematoxylin and eosin staining of samples from 36 piglets suggested that dramatic changes were observed in the jejunum crypts depth and crypt fission index of neonatal piglets (P < 0.001). The number of intestinal stem cells (ISC) tended to increase (P < 0.10), and a decreased number of enteroendocrine cells appeared in the jejunal crypt on d 7 (P < 0.05). Furthermore, the mRNA expression of jejunal chromogranin A (ChgA) was down-regulated in d 7 piglets (P < 0.05). There was an up-regulation of the adult ISC marker gene of SPARC related modular calcium binding 2 (Smoc2), and Wnt/ß-catenin target genes on d 7 (P < 0.05). These results were further verified in vitro enteroid culture experiments. A mass of hollow spheroids was cultured from the fetal intestine of 0-d-old piglets (P < 0.001), whereas substantial organoids with budding and branching structures were cultured from the intestine of 7-d-old piglets (P < 0.001). The difference was reflected by the organoid budding efficiency, crypt domains per organoid, and the surface area of the organoid. Furthermore, spheroids on d 0 had more Ki67-positive cells and enteroendocrine cells (P < 0.05) and showed a decreasing trend in the ISC and goblet cells (P < 0.10). Moreover, the mRNA expression of spheroids differed markedly from that of organoids, with low expression of intestinal differentiation gene (Lysozyme; P < 0.05), epithelial-specific markers (Villin, E-cadherin; P < 0.05), and adult ISC markers (leucine-rich repeat-containing G protein-coupled receptor 5 [Lgr5], Smoc2; P < 0.001), and up-regulation of fetal marker (connexin 43 [Cnx43]; P < 0.05). The mRNA expression of relevant genes was up-regulated, and involved in Wnt/ß-catenin, epidermal growth factor (EGF), Notch, and bone morphogenetic protein (BMP) signaling on d 7 organoids (P < 0.05). Spheroids displayed low differentiated phenotype and high proliferation, while organoids exhibited strong differentiation potential. These results indicated that the conversion from the fetal progenitors (spheroids) to adult ISC (normal organoids) might largely be responsible for the fast development of intestinal epithelial cells in neonatal piglets.

N-Acetyl-D-glucosamine improves the intestinal development and nutrient absorption of weaned piglets via regulating the activity of intestinal stem cells.

Early weaning in piglets can cause a series of negative effects. This causes serious losses to the livestock industry. N-Acetyl-D-glucosamine (D-GlcNAc) plays an important role in regulating the homeostasis of the intestine. This study aimed to investigate the effects of D-GlcNAc on the growth performance and intestinal function of weaned piglets. Twenty-four weaned piglets ([Yorkshire × Landrace] × Duroc, 6.58 ± 0.15 kg, n = 8) at 21 d old were fed 3 diets supplemented with 0 (control), 1 and 3 g/kg D-GlcNAc. The intestinal organoid model was used to verify the regulatory mechanism of D-GlcNAc on intestinal epithelial cells. On the whole, supplementation of D-GlcNAc in the piglet diet has no significant effect on the growth performance and diarrhoea of weaned piglets (P > 0.05). The apparent digestibility of nutrients and mRNA abundance of nutrient transporters in the 1 g/kg D-GlcNAc group were increased significantly (P < 0.05). D-GlcNAc did not affect villus height (VH) and crypt depth (CD) but resulted in a numerically shorter VH and shallower CD, which lead to an increase in ileal VH:CD ratio (P < 0.05). Cell shedding rates in the ileum villi increased (P < 0.05). The relative length and weight of the small intestine of weaned piglets increased (P < 0.05). In vitro studies found that the budding rates of organoids treated with 0.1 mmol/L D-GlcNAc increased on the d 3 and 5 (P < 0.05). The average budding numbers per budding organoid treated with 0.1 and 10 mmol/L D-GlcNAc increased on d 3 (P < 0.05). D-GlcNAc upregulated leucine rich repeat containing G protein-coupled receptor 5 (Lgr5 + ) and Chromogranin A mRNA abundance in organoids (P < 0.05). Mucin 2 (Muc2) expression increased when treated with 1 and 10 mmol/L D-GlcNAc (P < 0.05). In conclusion, dietary D-GlcNAc cannot improve the growth performance of weaned piglets. However, it can promote the growth and development of the intestinal tract and improve the digestion and absorption capacity of the intestine, which is achieved by affecting the activity of intestinal stem cells.

Dietary high protein-induced diarrhea and intestinal inflammation by activation of NF-κB signaling in piglets.

The present study aimed to investigate whether inflammation-associated responses in piglets are induced by high protein (HP) through activating nuclear factor kappa B (NF-κB) signaling. Sixteen piglets (35 d of age, Duroc × [Landrace × Yorkshire], weaned at d 21, initial BW = 9.70 ± 0.11 kg) were allocated to 18% and 26% CP (HP group) at random, comprising 8 replicate pens per treatment. The piglets were slaughtered to collect intestinal tissues when apparent, persistent, and stable diarrhea syndromes happened (on d 12). No significant differences were observed in their growth performance (P > 0.05), but reduction by 19.11%, 25.31%, 23.64% of ADFI, ADG, and G:F, respectively was detected in the HP group. The HP group had greater (P = 0.002) diarrhea rates. Furthermore, dietary HP had lower ileal villus height (VH; P = 0.048), ratio of villus height to crypt depth (VH/CD ratio; P = 0.016), and colonic CD (P = 0.034), as well as had the trend (P = 0.075) to reduce the ileal villus absorptive area. Moreover, HP diets significantly elevated the goblet cell numbers in the ileal villi (P = 0.016) and colonic crypts (P < 0.001) and up-regulated (P = 0.012) the mRNA expression of mucin2 (Muc2) in the ileum. In addition, HP diets increased the myeloperoxidase concentration in the ileum (P = 0.002) and colon (P = 0.007) of piglets. Dietary HP significantly down-regulated the mRNA expression of tumor necrosis factor-α (TNF-α; P < 0.001) in the ileum, induced nitric oxide synthase (iNOS; P = 0.040) and interleukin-22 (IL-22; P = 0.008) in the colon, and inclined to down-regulate interleukin-1ß (IL-1ß; P = 0.076) expression in the colon. The relative protein abundance of Galectin-3 (P = 0.046) in the colon and the ratio of phosphorylation NF-κB to NF-κB (p-NF-κB/NF-κB ratio) in the ileum of HP piglets were also greater (P = 0.038). These results suggest that dietary HP may cause diarrhea in piglets by activating NF-κB signaling induced intestinal inflammation.

Dietary Copper Improves Intestinal Morphology via Modulating Intestinal Stem Cell Activity in Pigs.

Copper (Cu) is an essential micronutrient for animals. Many studies have been conducted on the effects of dietary Cu on growth performance, intestinal morphology, and function of piglets. However, the underlying mechanism remains to be explored. Intestinal stem cells (ISC) drive the development and constant renewal of intestinal epithelium. Therefore, we hypothesized that dietary Cu affects piglets' intestinal development via modulating ISC activity. A total of eighty-five 21-day-old piglets were randomly assigned to five groups, where 25, 50, 75, 100, and 125 mg CuSO4/kg on a dry matter basis were supplemented to the basal diet at phase 1 (day 0 to 21). Increasing the dietary Cu concentration decreased (p < 0.05) villus width but increased (p < 0.001) the number of Ki67-positive cells. At phase 2 (day 22 to 163), the other 45 pigs were offered the same diets. Villus height in the 125 mg/kg Cu group was greater (p < 0.001) than in the other groups. Moreover, the effects of Cu on ISC activity in vitro were tested to explore the underlying mechanism. Compared to the control group, 10 µmol/L CuSO4·5H2O increased (p < 0.001) the organoid budding efficiency, crypt depth, and crypts per organoid. Dietary Cu improved the intestinal morphology of finishing pigs via promoting cell proliferation and modulating ISC activity.

Effects of dietary supplementation with herbal extract mixture on growth performance, organ weight and intestinal morphology in weaning piglets.

BACKGROUND: Many countries are increasingly prohibiting the addition of antibiotics in livestock diets. Therefore, herb extracts have gradually drawn attention to substitute antibiotics. Our present study aimed to determine the effects of herbal extract mixture (HEM) in dietary on growth performance, organ weight, intestinal morphology and intestinal nutrient transporters in weaned pigs. METHODS: 27 piglets (Duroc × [Landrace × Yorkshire]; Body Weight (BW) = 5.99 ± 0.13 kg) were weaned at day 21 and randomly divided into three groups (n = 9 piglets/group). All piglets received a basal diet containing similar amounts of nutrients for 14 days. The three groups were the control (no additive), the antibiotics (375 mg/kg chlortetracycline, 20%, 500 mg/kg enramycin, 4%, 1,500 mg/kg oxytetracycline calcium, 50%) and the HEM group (1000 mg/kg extract mixture of golden-and-silver honeysuckle, huangqi, duzhong leaves and dangshen). After 14 d of treatment, we collected tissue samples to measure organ weight, intestinal parameters, intestinal morphology, digestive enzyme activities and intestinal mRNA expression of nutrient transporters. RESULTS: The HEM group had no effects on growth performance and organ weight of weaned pigs. But compared with the control group, both HEM and antibiotics improved intestinal morphology, and HEM elevated the expression of nutrient transporters in ileum (SLC6A9, SLC15A1, and SLC5A1). HEM significantly decreased the activities of maltase in ileum and the ratio of small intestinal weight to BW than control group. CONCLUSIONS: These results indicate benefit effects of the supplementation of HEM in diet, including modulating intestinal morphology and increasing the mRNA expression of nutrients transporters. These findings suggest that HEM provides novel insights into a variety of herbal extract mixtures to replace antibiotics in animal production.

Dietary vitamin A affects growth performance, intestinal development, and functions in weaned piglets by affecting intestinal stem cells.

Vitamin A (VA) is an important nutrient for weaning piglets. It plays a significant role in the normal formation, development, and maintenance of epithelial cells. Previous studies have shown that VA supplements could improve the host's intestinal barrier function. Therefore, we hypothesized that VA supplements can affect intestinal function in weaned piglets by regulating intestinal stem cells. Thirty-two 21-d-old weaned [(Yorkshire × Landrace) × Duroc] piglets with an average weight of 8.34 ± 0.13 kg were randomly divided into 4 treatment groups, with 1) 2 mg/kg (control), 2) 4 mg/kg, 3) 8 mg/kg, and 4) 16 mg/kg doses of VA, respectively. The experiment lasted for 14 d. Weaned piglets were given ad libitum access to food and water during the test. The ADG (linear, P = 0.020) and G:F (linear, P = 0.005) of the piglets were found to increase significantly from days 8 to 14. The Lgr5+ gene expression (P = 0.012) in the jejunum mucosa of the 16 mg/kg VA group was increased. The jejunum villus height (P = 0.027) and villi surface area (P = 0.035) were significantly increased in the 4 mg/kg VA treatment group. The crypt depth increased significantly in the 4 and 8 mg/kg VA treatment groups (quadratic, P = 0.043), and the ratios of villus height to crypt depth significantly increased in the 16 mg/kg VA group (quadratic, P = 0.015). The maltase (P = 0.032), sucrose (P = 0.041), and alkaline phosphatase activity (linear, P = 0.024) were significantly increased when further supplemented with 4 mg/kg VA. Slc2a2 mRNA abundance was significantly increased in the 2 mg/kg VA group (linear, P = 0.024). Moreover, the budding rates, buddings number per organoid, and Chromogranin A and Muc2 expression of piglet intestinal organoids were significantly reduced (P < 0.05) by VA and its metabolites (retinoic acid). Compared with the control group, the expression of Spp1 and Trop2 increased. These results indicated that VA may increase the stemness of intestinal stem cell in vitro. This study suggested that VA could affect growth performance and intestinal function by regulating intestinal stem cells in the jejunum of weaned piglets.

Effects of vitamin B6 on the growth performance, intestinal morphology, and gene expression in weaned piglets that are fed a low-protein diet1.

Vitamin B6 (VB6), which is an essential functional substance for biosome, plays an irreplaceable role in animal health. However, there are few studies that focus on the correlation between VB6 and intestinal health in weaned piglets. This study was conducted to investigate the effects of VB6 on the growth performance, intestinal morphology, and inflammatory cytokines and amino acid (AA) transporters mRNA expression in weaned piglets that are fed a low crude-protein (CP, 18%) diet. Eighteen crossbred piglets with initial body weights of 7.03 ± 0.17 kg (means ± SEM), weaned at 21-d age, were randomly assigned three diets with 0, 4, and 7 mg/kg VB6 supplementation, respectively. The experimental period lasted 14 days. Our results showed that there were no significant differences in growth performance, diarrhea rate, and biochemical parameters among the three treatments. In the jejunum, dietary VB6 supplementation did not affect the morphology and positive Ki67 counts. Dietary supplementation with 4 mg/kg VB6 decreased the mRNA expression of COX-2, IL-10, and TGF-ß (P < 0.05). Dietary supplementation with 7 mg/kg VB6 increased the mRNA expression of SLC7A1, SLC7A6, SLC16A14, and SLC38A5 (P < 0.05) and 4 or 7 mg/kg VB6 decreased SLC36A1 mRNA expression (P < 0.05). In the ileum, VB6 supplementation did not affect positive Ki67 counts but significantly decreased villus area (P < 0.05) and tended to decrease villus height (P = 0.093). Dietary supplementation with 4 mg/kg VB6 had significantly increased the mRNA expression of IL-1ß, TNF-α, COX-2, IL-10, and TGF-ß (P < 0.05). Dietary supplementation with 4 or 7 mg/kg VB6 had significantly decreased SLC6A20, SLC7A1, SLC7A6, SLC16A14, and SLC38A5 mRNA expression (P < 0.05). These findings suggest that dietary supplementation of VB6 mainly down-regulated inflammatory cytokines and up-regulated AA transporters mRNA expression in jejunum, while up-regulated (4 mg/kg) inflammatory cytokines and down-regulated AA transporters mRNA expression in ileum, which may provide a reference for the intestinal development of weaned piglets that are fed a low-CP diet.

Effects of vitamin B6 on growth, diarrhea rate, intestinal morphology, function, and inflammatory factors expression in a high-protein diet fed to weaned piglets1.

Vitamin B6 (VB6) is an important coenzyme factor which participates in many metabolic reactions, especially amino acid metabolism. There are few reports on how VB6 mediates weaned piglet intestinal health. This study purposed to investigate dietary VB6 effects on growth, diarrhea rates, and intestinal morphology and function in weaned piglets fed a high-crude protein (22% CP) diet. Eighteen 21-d-old weaned [(Yorkshire × Landrace) × Duroc] piglets with body weights of 7.03 ± 0.15 (means ± SEM) kg were randomly assigned into 3 VB6-containing dietary treatments. Vitamin B6 content was: 0, 4, and 7 mg/kg, respectively. The feeding period lasted 14 d. The results showed that no significant difference existed for the growth performance. The 7 mg/kg VB6 group had a tendency to decrease diarrhea rate (P = 0.065). Blood biochemical parameters analysis demonstrated that total protein, cholesterol, and high-density lipoprotein significantly increased in the 7 mg/kg VB6 group (P < 0.05). In the jejunum, no significant differences were detected for villus height, villus width, crypt depth, villus height and crypt depth ratios, and positive Ki67 counts and the mRNA expression of inflammatory cytokines. Vitamin B6 significantly increased the mRNA expression of SLC6A19 and SLC6A20 (P < 0.05) and decreased the mRNA expression of SLC36A1 (P < 0.05). In the ileum, VB6 significantly increased villus height and villus width (P < 0.05) while decreased positive Ki67 cell counts for 7 mg/kg VB6 group (P < 0.05). Vitamin B6 had significantly increased the mRNA expression of interleukin-1ß, tumor necrosis factor-α,cyclo-oxygen-ase-2, and transforming growth factor-ß (P < 0.05). Vitamin B6 also had significantly increased mRNA expression of SLC6A19, SLC7A6, SLC7A7, and SLC36A1 (P < 0.05). These findings suggest that dietary supplementation with VB6 may affect the intestinal morphology and absorption and metabolism of protein in weaned piglets fed a high-protein diet by altering the expression of intestinal inflammatory cytokines and amino acid transporters.

The effects of dietary supplementation with hyodeoxycholic acid on the differentiation and function of enteroendocrine cells and the serum biochemical indices in weaned piglets1.

Bile acid, a cholesterol metabolite, promotes gastrointestinal tract digestion and absorption of cholesterol, lipids, and fat-soluble vitamins. It is a signaling regulatory molecule that influences a variety of endocrinal and metabolic activities. This study investigated the effects of hyodeoxycholic acid (HDCA) as a dietary supplement on endocrine cell differentiation and function and weaned piglet serum biochemical indices. Sixteen piglets [Duroc × (Landrace × Yorkshire)] were individually housed and weaned at 21 d of age (BW of 6.14 ± 0.22 kg). Uniform weight animals were randomly assigned to 1 of 2 treatments (8 replicate pens per treatment and 1 piglet per pen). The treatments were 1) base diet (control) and 2) base diet supplemented with 2 g/kg of HDCA. Control and HDCA piglet numbers of chromogranin A (CgA)-positive cells per crypt did not differ. HDCA CgA-positive cells numbers decreased (P < 0.05) in the jejunal villi showed a tendency to decrease (P < 0.10) in the ileal villi and showed tendency toward an increase (P < 0.10) in the duodenal villi compared with the controls. The HDCA diet led to a decline in glucagon-like peptide 2 (P < 0.01) concentrations, but did not affect plasma glucagon-like peptide 1. HDCA supplementation increased (P < 0.05) the mRNA expression of jejunal Insm1, Sst, PG, and Gast, but decreased (P < 0.05) duodenal expression of Insm1, jejunal Pdx1, and ileal NeuroD1. HDCA elevated globulin and immunoglobulin A (P < 0.05) serum concentrations and decreased the albumin/globulin ratio (P < 0.05). Total protein and immunoglobulin G serum levels tended to increase compared with the control group. These results indicate that dietary HDCA at 2 g/kg may regulate enteroendocrine cell differentiation and play a role in increasing weaned piglet humoral immunity.

The effects of dietary supplementation with hyodeoxycholic acid on the differentiation and function of enteroendocrine cells and the serum biochemical indices in weaned piglets.

Bile acid, a cholesterol metabolite, promotes gastrointestinal tract digestion and absorption of cholesterol, lipids, and fat-soluble vitamins. It is a signaling regulatory molecule that influences a variety of endocrinal and metabolic activities. This study investigated the effects hyodeoxycholic acid (HDCA) as a dietary supplement on endocrine cell differentiation and function and weaned piglet serum biochemical indices. Sixteen piglets (Duroc × [Landrace × Yorkshire]) were individually housed and weaned at 21 days of age (body weight of 6.14 ± 0.22 kg). Uniform weight animals were randomly assigned to one of two treatments (eight replicate pens per treatment and one piglet per pen). The treatments were 1) base diet (control); and 2) base diet supplemented with 2 g/kg of HDCA. Control and HDCA piglet numbers of CgA-positive cells per crypt did not differ. HDCA CgA-positive cells numbers decreased (P < 0.05) in the jejunal villi, showed a tendency to decrease (P < 0.10) in the ileal villi, and showed tendency toward an increase (P < 0.10) in the duodenal villi compared to the controls. The HDCA diet led to a decline in GLP-2 (P < 0.01) concentrations, but did not affect plasma GLP-1. HDCA supplementation increased (P < 0.05) the mRNA expression of jejunal Insm1, Sst, PG, and Gast, but decreased (P < 0.05) duodenal expression of Insm1, jejunal Pdx1, and ileal NeuroD1. HDCA elevated GLO and IgA (P < 0.05) serum concentrations and decreased the A/G ratio (P < 0.05). TP and IgG serum levels tended to increase compared to the control group. These results indicate that dietary HDCA at 2 g/kg may regulate enteroendocrine cell differentiation and play a role in increasing weaned piglet humoral immunity.

Tannic acid modulates intestinal barrier functions associated with intestinal morphology, antioxidative activity, and intestinal tight junction in a diquat-induced mouse model.

Oxidative stress is more likely to occur in the intestine compared to other organs because it is located at the interface between an organism and its luminal environment. Tannic acid (TA) is reported to serve as an antioxidant, antimicrobial, anticarcinogenic and antimutagenic agent in various models. In the present study, we evaluated the effects of TA on body weight, intestinal morphology, antioxidative activity, and intestinal barrier in diquat-induced oxidative stress mouse model. The results showed that TA had failed to affect antioxidative enzymes in diquat-challenged mice, while the concentration of 2.5 mg kg-1 to 10 mg kg-1 TA had no negative effect on body weight and enhanced the colon length in mice. The dose of 2.5 mg kg-1 TA ameliorated the morphological damage in the jejunum by increasing the villus height and crypt depth, activated the antioxidative pathway by decreasing jejunal protein expression of Kelch like-ECH-associated protein 1 (KEAP1) and increasing protein expression of Nuclear factor erythroid 2-related factor 2 (NRF2), and affected the intestinal barrier by inhibiting the jejunal mRNA expression of claudin and promoting mRNA expression of zonula occludens (zo-1). In conclusion, the pretreatment of TA in a mouse model of oxidative stress failed to change the antioxidative enzymes but modulated the jejunal morphology, colon length, antioxidative pathway and intestinal barrier in the diquat oxidative model.

Effects of dietary tryptophan supplementation in the acetic acid-induced colitis mouse model.

Inflammatory bowel disease (IBD) is characterized by chronic inflammation of the gastrointestinal tract and is strongly associated with intestinal immunity and the microbiome. Tryptophan (Trp) is an inflammatory inhibitor and modulator of the intestinal microflora. We explored the serum profile of amino acids and the effects of diet supplementation with Trp (1.0 g kg-1) on intestinal immunity and microbiota in the acetic acid-induced colitis mouse model. We analyzed the survival rate, colonic morphological parameters, profiles of serum amino acids, microbiota in colonic contents and the relative gene abundance of intestinal proinflammatory cytokines. Although the dietary Trp supplementation failed to improve the survival rate and ameliorate the morphological parameters of colon in mice with colitis, Trp modulated the general serum amino acid profile by reducing the amino acid profiles of threonine, methionine and proline, affected intestinal immunity by inhibiting the colonic expression of interleukin-22 and changed the microbiota by reducing the abundance of Candidatus, Clostridium and Coprococcus at the genus level. In conclusion, dietary Trp supplementation in a mouse model of colitis did not ameliorate the survival rate and morphological parameters of colon but did modulate the serum amino acid profiles, intestinal immunity and microbiota. These findings enhance our understanding of the roles of Trp in the metabolism of serum amino acids, intestinal immunity and microbiota.

Pig models on intestinal development and therapeutics.

The gastrointestinal tract plays a vital role in nutrient supply, digestion, and absorption, and has a crucial impact on the entire organism. Much attention is being paid to utilize animal models to study the pathogenesis of gastrointestinal diseases in response to intestinal development and health. The piglet has a body size similar to that of the human and is an omnivorous animal with comparable anatomy, nutritional requirements, and digestive and associated inflammatory processes, and displays similarities to the human intestinal microbial ecosystem, which make piglets more appropriate as an animal model for human than other non-primate animals. Therefore, the objective of this review is to summarize key attributes of the piglet model with which to study human intestinal development and intestinal health through probing into the etiology of several gastrointestinal diseases, thus providing a theoretical and hopefully practical, basis for further studies on mammalian nutrition, health, and disease, and therapeutics. Given the comparable nutritional requirements and strikingly similar brain developmental patterns between young piglets and humans, the piglet has been used as an important translational model for studying neurodevelopmental outcomes influenced by pediatric nutrition. Because of similarities in anatomy and physiology between pigs and mankind, more emphasises are put on how to use the piglet model for human organ transplantation research.