Ming Z. Fan

Pigs expressing salivary phytase produce low-phosphorus manure

To address the problem of manure-based environmental pollution in the pork industry, we have developed the phytase transgenic pig. The saliva of these pigs contains the enzyme phytase, which allows the pigs to digest the phosphorus in phytate, the most abundant source of phosphorus in the pig diet. Without this enzyme, phytate phosphorus passes undigested into manure to become the single most important manure pollutant of pork production. We show here that salivary phytase provides essentially complete digestion of dietary phytate phosphorus, relieves the requirement for inorganic phosphate supplements, and reduces fecal phosphorus output by up to 75%. These pigs offer a unique biological approach to the management of phosphorus nutrition and environmental pollution in the pork industry.

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.

Guar gum and similar soluble fibers in the regulation of cholesterol metabolism: current understandings and future research priorities.

The hypocholesterolemic effects associated with soluble fiber consumption are clear from animal model and human clinical investigations. Moreover, the modulation of whole-body cholesterol metabolism in response to dietary fiber consumption, including intestinal cholesterol absorption and fecal sterol and bile acid loss, has been the subject of many published reports. However, our understanding of how dietary fibers regulate molecular events at the gene/protein level and alter cellular cholesterol metabolism is limited. The modern emphasis on molecular nutrition and rapid progress in ‘high-dimensional’ biological techniques will permit further explorations of the role of genetic polymorphisms in determining the variable interindividual responses to soluble fibers. Furthermore, with traditional molecular biology tools and the application of ‘omic’ technology, specific insight into how fibers modulate the expression of genes and proteins that regulate intestinal cholesterol absorption and alter hepatic sterol balance will be gained. Detailed knowledge of the molecular mechanisms by which soluble fibers reduce plasma cholesterol concentrations is paramount to developing novel fiber-based “cocktails” that target specific metabolic pathways to gain maximal cholesterol reductions.

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.

Molecular cloning, tissue distribution and ontogenetic expression of the amino acid transporter b0,+ cDNA in the small intestine of Tibetan suckling piglets

The small intestine is the main absorption place of peptides and free amino acids in mammals. The amino acid transporter system b(0,+) mediates apical uptake of basic amino acids, especially lysine, arginine and cysteine. The aim of the current study was to clone Tibetan porcine amino acid transporter b(0,+)AT (SLC7A9) for comparing the sequences of Tibetan and common (Sus scrofa) pigs, and investigating the tissue distribution and ontogenetic expression in the small intestine of Tibetan suckling piglets. The Tibetan porcine SLC7A9 gene was first cloned from the porcine small intestine and found to encode the amino acid transporter b(0,+)AT. The entire open reading frame (ORF) of the SLC7A9 is 1464 bp and codes for 487 amino acid residues, with a higher degree of sequence similarity with common pig (99.59%) and horse counterparts (91.2%) than with monkey (89.5%) or human (88.7%). The deduced protein has 12 putative transmembrane domains. In this study, SLC7A9 mRNA was detected in brain, kidney, duodenum, jejunum, ileum, heart, liver, lung and muscle from Tibetan pigs at 7 and 21 days by PCR. We also investigated the age-dependent expression of b(0,+)AT in Tibetan suckling piglets in duodenum, anterior jejunum, posterior jejunum, ileum and kidney from day 1 to 35. The abundance of SLC7A9 mRNA in duodenum and jejunum was highest and lowest, respectively. Expression patterns were similar in duodenum and anterior jejunum, where the mRNA level was decreased before the suckling period and increased until day 35. Posterior jejunum expression was increasing steadily with age, except on day 7. The ileum has the highest expression at day 14 and became steady after day 28. The mRNA abundance in the kidney is opposite to duodenum, increasing until day 14 and reducing thereafter. Our results showed the pattern of b(0,+)AT expressed in small intestine of Tibetan pig and lay the foundation for in depth investigations of the regulation of b(0,+)AT in vivo.

Nutrient utilisation and intestinal fermentation are differentially affected by the consumption of resistant starch varieties and conventional fibres in pigs

This study examined the influence of different resistant starch (RS) varieties and conventional fibres on the efficiency of nutrient utilisation and intestinal fermentation in pigs. Thirty-six pigs (30 kg) were fed poultry meal-based diets supplemented with 10 % granular resistant corn starch (GCS), granular resistant potato starch (GPS), retrograded resistant corn starch (RCS), guar gum (GG) or cellulose for 36 d according to a completely randomised block design. Distal ileal and total tract recoveries were similar (P>0.05) among the RS varieties. Distal ileal starch recovery was higher (P < 0.05) in pigs consuming the RS diets (27-42 %) as compared with the control group (0.64 %). Consumption of GCS reduced (P < 0.05) apparent total tract digestibility and whole-body retention of crude protein in comparison with the control group. Consumption of GPS reduced (P < 0.05) total tract Ca digestibility and whole-body retention of Ca and P compared with the control group. However, consumption of RCS increased (P < 0.05) total tract Ca digestibility compared with the control group. Caecal butyrate concentration was increased (P < 0.05) following consumption of RCS and GG in comparison with the control group. Consumption of all the RS varieties reduced (P < 0.05) caecal indole concentrations compared with the control. Caecal butyrate concentrations were positively correlated (P < 0.05; r 0.63-0.83) with thermal properties among the RS varieties. We conclude that nutrient utilisation and intestinal fermentation are differentially affected by the consumption of different RS varieties and types of fibres. Thermal properties associated with different RS varieties may be useful markers for developing RS varieties with specific functionality.

Egg Yolk Peptides Up-regulate Glutathione Synthesis and Antioxidant Enzyme Activities in a Porcine Model of Intestinal Oxidative Stress

Long-term oxidative stress in the gastrointestinal tract can lead to the development of chronic intestinal disorders. Many food-derived antioxidants are effective in vitro, but the variable reports of in vivo efficacy and the pro-oxidant nature of some antioxidants necessitate alternative strategies for the reduction of in vivo oxidative stress. Compounds that up-regulate the production of endogenous antioxidants such as glutathione (GSH) and antioxidant enzymes provide novel approaches for the restoration of redox homeostatis. Egg yolk peptides (EYP) prepared from Alcalase and protease N digestion of delipidated egg yolk proteins were found to exhibit antioxidative stress properties. The effect of EYP supplementation was examined in a hydrogen peroxide-induced human colon cell line and in an animal model of intestinal oxidative stress. EYP significantly reduced the pro-inflammatory cytokine, IL-8, in Caco-2 cells. In piglets given intraperitoneal infusions of hydrogen peroxide, EYP treatment increased GSH and gamma-glutamylcysteine synthetase mRNA expression and activity, significantly increased antioxidant enzyme activities, in particular catalase and glutathione S-transferase activities, and reduced protein and lipid oxidation in the duodenum, jejunum, ileum, and colon. Furthermore, EYP boosted the systemic antioxidant status in blood by increasing the GSH concentration in red blood cells. These results suggest that EYP supplementation is a novel strategy for the reduction of intestinal oxidative stress.

The effect of dietary addition of a polysaccharide from Atractylodes macrophala Koidz on growth performance, immunoglobulin concentration and IL-1β expression in weaned piglets

The present study was conducted to determine the effects of a polysaccharide of Atractylodes macrophala Koidz (PAM) as a dietary additive on growth performance, immunoglobulin concentration and IL-1β expression in weaned piglets. One hundred and twenty Landrace x Yorkshire piglets weaned at 28 days old (body weight 7·5±0·07 kg) were assigned to five treatment groups (three pens/ group, eight piglets/pen) fed maize/soybean-based diets supplemented with 0, 3, 6 or 9 g of PAM/kg diet or antibiotics (0·4 g flavomycin/kg+0·13 g olaquindox/kg). The experimental period was 28 days. With increasing PAM supplementation levels, average daily gain was greater (quadratic, P<0·05) and the ratio of amount fed to live weight (LW) gain (feed/gain) improved (quadratic, P<0·05) during days 14-28 and overall, and diarrhoea incidence decreased (linear, P<0·05) during days 14-28. Supplementation of PAM also increased (quadratic, f<0·05) serum concentrations of interleukin (IL)-2 and IL-6 on day 14, and increased (quadratic, P<0·05) IL-1β expression in jejunal mucosa and lymph nodes. Concentrations of PAM between 6 and 9 g/kg presented the strongest bioactivity compared to the control group or antibiotic-fed group. These findings indicate that PAM is effective in improving growth performance and cytokine response, which suggests that PAM can be used as a diet additive for weanling piglets.