Binying Ding

Dietary arginine supplementation alleviates intestinal mucosal disruption induced by Escherichia coli lipopolysaccharide in weaned pigs.

This study evaluated whether arginine (Arg) supplementation could attenuate gut injury induced by Escherichia coli lipopolysaccharide (LPS) challenge through an anti-inflammatory role in weaned pigs. Pigs were allotted to four treatments including: (1) non-challenged control; (2) LPS-challenged control; (3) LPS+0.5 % Arg; (4) LPS+1.0 % Arg. On day 16, pigs were injected with LPS or sterile saline. At 6 h post-injection, pigs were killed for evaluation of small intestinal morphology and intestinal gene expression. Within 48 h of challenge, 0.5 % Arg alleviated the weight loss induced by LPS challenge (P = 0.025). In all three intestinal segments, 0.5 or 1.0 % Arg mitigated intestinal morphology impairment (e.g. lower villus height and higher crypt depth) induced by LPS challenge (P < 0.05), and alleviated the decrease of crypt cell proliferation and the increase of villus cell apoptosis after LPS challenge (P < 0.01). The 0.5 % Arg prevented the elevation of jejunal IL-6 mRNA abundance (P = 0.082), and jejunal (P = 0.030) and ileal (P = 0.039) TNF-alpha mRNA abundance induced by LPS challenge. The 1.0 % Arg alleviated the elevation of jejunal IL-6 mRNA abundance (P = 0.053) and jejunal TNF-alpha mRNA abundance (P = 0.003) induced by LPS challenge. The 0.5 % Arg increased PPARgamma mRNA abundance in all three intestinal segments (P < 0.10), and 1.0 % Arg increased duodenal PPARgamma mRNA abundance (P = 0.094). These results indicate that Arg supplementation has beneficial effects in alleviating gut mucosal injury induced by LPS challenge. Additionally, it is possible that the protective effects of Arg on the intestine are associated with decreasing the expression of intestinal pro-inflammatory cytokines through activating PPARgamma expression.

Alpha-Ketoglutarate and intestinal function.

Alpha-ketoglutarate (AKG) is an intermediate of the Krebs cycle which bridges amino acid metabolism with glucose oxidation in animals. Of particular interest is the conversion of AKG into glutamate by mitochondrial glutamate dehydrogenase in the gastrointestinal tract where glutamate has multiple physiological functions (including regulation of cell function, neurotransmission, and gastric emptying). Additionally, AKG stimulates the initiation of catabolism of branched-chain amino acids (BCAA) via BCAA transaminase in enterocytes. Oxidation of AKG also provides large amounts of ATP and modulates cellular redox state in the small intestine. Translating the basic research into practice, results of recent studies indicate that dietary supplementation with AKG alleviates oxidative stress and injury in intestinal mucosal cells, while improving intestinal mucosal integrity and absorption of nutrients in endotoxin-challenged pigs. The beneficial effects of AKG are associated with increased activation of the mTOR signaling pathway and net protein synthesis. Thus, AKG is a novel and promising supplement in diets to improve intestinal health in animals and possibly humans.

Effect of three mycotoxin adsorbents on growth performance, nutrient retention and meat quality in broilers fed on mould-contaminated feed

1. A study was conducted to investigate the effects of an esterified glucomannan (EGM), a hydrated sodium calcium aluminosilicate (HSCAS) and a compound mycotoxin adsorbent (CMA) on performance, nutrient retention and meat quality in broilers fed on mould-contaminated feed. Mould-contaminated diets were prepared by replacing half of the non-contaminated maize in the basal diets with mould-contaminated maize, which contained 450·6 µg/kg of aflatoxin B1, 68·4 µg/kg of ochratoxin A and 320·5 µg/kg of T-2 toxin. 2. The mould-contaminated diet significantly decreased body weight gain (BWG) between 10 and 21 d, feed intake (FI) between 35 and 42 d, the apparent retention of crude lipid and phosphorus, and the lightness (L*) value of breast and thigh muscle. It also significantly increased the redness (a*) and yellowness (b*) value in breast muscle and the b* value in thigh muscle. 3. The addition of 0·2% HSCAS significantly increased FI between 35 and 42 d and the apparent retention of phosphorus. Supplementation with 0·1% CMA in the contaminated diet significantly improved BWG from 10 to 21 d, and increased FI from 35 to 42 d and from 10 to 42 d. CMA also significantly increased the apparent retention of crude lipid, crude protein, ash and phosphorus. All three mycotoxin-adsorbent treatments significantly improved the L* values of breast and thigh muscle when compared with the mould-contaminated group. Supplementation with 0·1% CMA in the contaminated diet significantly decreased b* value and improved tenderness in thigh muscle. 0·05% EGM significantly decreased b* value of thigh muscle compared to mould-contaminated group. 4. The results indicated that mycotoxins in contaminated feed retard growth, nutrient retention and meat quality, whereas the addition of 0·05% EGM, 0·2% HSCAS or 0·1% CMA prevents the adverse effects of mycotoxins to varying extents, with 0·1% CMA being the most effective adsorbent treatment.

Activation of peroxisome proliferator-activated receptor-γ potentiates pro-inflammatory cytokine production, and adrenal and somatotropic changes of weaned pigs after Escherichia coli lipopolysaccharide challenge

Our previous study demonstrated mRNA and protein expression of peroxisome proliferator-activated receptor-g (PPAR-g) in the immune system of weaned pigs. In this report, to test the hypothesis that activation of PPAR-g in immune system modulates inflammatory response, and adrenal and somatotropic responses associated with immune challenge, we administered intraperitoneally PPAR-g agonist and/or antagonist in weaned pigs subjected to Escherichia coli lipopolysaccharide (LPS) challenge. Unexpectedly, we found that a single injection of the PPAR-g agonist rosiglitazone (given at 3 mg/kg body weight 30 min before LPS injection) failed to block pro-inflammatory cytokine production induced by LPS injection. Rather, plasma levels of tumor necrosis factor-a (TNF-a) and interleukin-6 (IL-6), mRNA abundance of TNF-a in thymus, spleen, mesenteric lymph node and peripheral white blood cells, mRNA abundance of IL-6 in thymus, protein levels of TNF-a in spleen and mesenteric lymph node, and protein levels of IL-6 in spleen and mesenteric lymph node, were elevated beyond the levels in control pigs injected with LPS. Furthermore, rosiglitazone potentiated the increase of plasma cortisol and prostaglandin E2 concentrations, and the decrease of plasma insulin-like growth factor-1 concentration induced by LPS injection. Co-administration of the PPAR-g antagonist bisphenol A diglycidyl ether (given 30 mg/kg body weight) 30 min prior to treatment with rosiglitazone antagonized the effect of the PPAR-g agonist, indicating a PPAR-g-dependent effect. Our data indicate that ligand-induced activation of PPAR-g does not ameliorate but enhances pro-inflammatory cytokine production, and further potentiates the adrenal and somatotropic changes in weaned pigs subjected to E. coli LPS challenge, which suggests that PPAR-g activation may not be useful, but potentially harmful, in the treatment of immune challenge in livestock. Our results raise doubts about the prevalently accepted anti-inflammatory role for PPAR-g activation.Our previous study demonstrated mRNA and protein expression of peroxisome proliferator-activated receptor-g (PPAR-g) in the immune system of weaned pigs. In this report, to test the hypothesis that activation of PPAR-g in immune system modulates inflammatory response, and adrenal and somatotropic responses associated with immune challenge, we administered intraperitoneally PPAR-g agonist and/or antagonist in weaned pigs subjected to Escherichia coli lipopolysaccharide (LPS) challenge. Unexpectedly, we found that a single injection of the PPAR-g agonist rosiglitazone (given at 3 mg/kg body weight 30 min before LPS injection) failed to block pro-inflammatory cytokine production induced by LPS injection. Rather, plasma levels of tumor necrosis factor-a (TNF-a) and interleukin-6 (IL-6), mRNA abundance of TNF-a in thymus, spleen, mesenteric lymph node and peripheral white blood cells, mRNA abundance of IL-6 in thymus, protein levels of TNF-a in spleen and mesenteric lymph node, and protein levels of IL-6 in spleen and mesenteric lymph node, were elevated beyond the levels in control pigs injected with LPS. Furthermore, rosiglitazone potentiated the increase of plasma cortisol and prostaglandin E(2) concentrations, and the decrease of plasma insulin-like growth factor-1 concentration induced by LPS injection. Co-administration of the PPAR-g antagonist bisphenol A diglycidyl ether (given 30 mg/kg body weight) 30 min prior to treatment with rosiglitazone antagonized the effect of the PPAR-g agonist, indicating a PPAR-g-dependent effect. Our data indicate that ligand-induced activation of PPAR-g does not ameliorate but enhances pro-inflammatory cytokine production, and further potentiates the adrenal and somatotropic changes in weaned pigs subjected to E. coli LPS challenge, which suggests that PPAR-g activation may not be useful, but potentially harmful, in the treatment of immune challenge in livestock. Our results raise doubts about the prevalently accepted anti-inflammatory role for PPAR-g activation.

Increased expression of the peroxisome proliferator-activated receptor γ in the immune system of weaned pigs after Escherichia coli lipopolysaccharide injection

Peroxisome proliferator-activated receptor gamma (PPARgamma), a member of the nuclear hormone receptor superfamily, has been implicated in regulation of immunity and inflammation in rodents and humans. The objective of the current study was to investigate whether the expression of PPARgamma was altered in the immune system of weaned pigs after Escherichia coli lipopolysaccharide (LPS) injection. PPARgamma expression was investigated in the thymus, spleen, mesenteric lymph node and peripheral white blood cells of weaned pigs (8.54+/-0.24 kg BW) after LPS injection (100 microg/kg BW, n=6) and controls (sterile saline, n=6), by using real-time polymerase chain reaction, Western blot analysis, and immunohistochemistry. Plasma pro-inflammatory cytokines and hormones were also assessed. LPS triggered PPARgamma mRNA and protein expression in the thymus (P<0.05, 4.24-fold; P<0.10, 1.46-fold), spleen (P<0.10, 2.75-fold; P<0.05, 1.84-fold), mesenteric lymph node (P<0.05, 4.32-fold; P<0.05, 1.96-fold) and peripheral white blood cells (P<0.001, 24.44-fold; P<0.001, 1.58-fold). The LPS-injected pigs showed an increase in PPARgamma staining in splenic corpuscle and periarterial lymphatic sheath of white pulp (P<0.05) and red pulp (P<0.001) of spleen, and in medullas of thymus lobule of thymus (P<0.05), and in thymus-dependent area of mesenteric lymph node (P<0.05) compared to the control pigs. Concurrent with up-regulation of PPARgamma expression, LPS induced increases in plasma interleukin-6 (P<0.001), tumor necrosis factor-alpha (P<0.001), cortisol (P<0.001), prostaglandin E(2) (P<0.01) and 15-deoxy-Delta(12,14)-prostaglandin J(2) (15 d-PGJ(2)) (P<0.05), and decreases in plasma insulin (P<0.10) and insulin-like growth factor-1 (P<0.001). These results suggest that induction of PPARgamma expression in immune system may be associated with the release of the natural PPARgamma activating ligand 15 d-PGJ(2), and play an important role in host response to immunological stress. Additionally, it is possible that PPARgamma would be a new therapeutic target in treatment of immunological stress of livestock.

Dietary N-acetylcysteine supplementation alleviates liver injury in lipopolysaccharide-challenged piglets.

The present study was carried out to determine whether N-acetylcysteine (NAC) could modulate liver injury in a lipopolysaccharide (LPS)-challenged piglet model. For this purpose, eighteen piglets were randomly assigned to the control, LPS or NAC group. Piglets in the control and LPS groups were fed a basal diet, whereas those in the NAC group were fed the basal diet supplemented with 500 mg/kg NAC. On days 10, 13 and 20 of the trial, the LPS- and NAC-treated piglets were intraperitoneally administered LPS (100 μg/kg body weight), while the control group was administered the same volume of saline. On day 20 of the trial, blood samples were obtained 3 h after LPS or saline injection. On day 21, the piglets were killed to collect liver samples. Dietary NAC supplementation attenuated LPS-induced liver histomorphological abnormalities. Compared with the control group, in the LPS-challenged piglets, the activities of alanine aminotransferase and aspartate aminotransferase and the concentrations of H2O2, TNF-α, IL-6 and PGE2 were dramatically increased in the plasma and the activity of superoxide dismutase in the plasma and that of glutathione peroxidase in the liver were significantly decreased. The LPS challenge also increased the concentration of AMP and the ratio of AMP:ATP, but decreased adenylate energy charges and the levels of ATP and ADP. These adverse effects of the LPS challenge were ameliorated by NAC supplementation. Moreover, NAC inhibited the LPS-induced increases in the abundance of liver heat shock protein 70 and NF-κB proteins. In conclusion, these results suggest that dietary NAC supplementation alleviates LPS-induced liver injury by reducing the secretion of pro-inflammatory cytokines, increasing the antioxidative capacity and improving energy metabolism.

Fish oil attenuates liver injury caused by LPS in weaned pigs associated with inhibition of TLR4 and nucleotide-binding oligomerization domain protein signaling pathways:

This study evaluated whether fish oil exerted a hepatoprotective effect in a LPS-induced liver injury model via regulation of TLR4 and nucleotide-binding oligomerization domain protein (NOD) signaling pathways. Twenty-four piglets were used in a 2 × 2 factorial design, and the main factors included diet (5% corn oil or 5% fish oil) and immunological challenge (LPS or saline). Fish oil resulted in enrichment of eicosapentaenoic acid, docosahexaenoic acid and total (n-3) polyunsaturated fatty acids in liver. Less severe liver injury was observed in pigs fed fish oil, as evidenced by improved serum biochemical parameters and less severe histological liver damage. In addition, higher expression of liver tight junction proteins, and lower hepatocyte proliferation and higher hepatocyte apoptosis were observed in pigs fed fish oil. The improved liver integrity in pigs fed fish oil was concurrent with reduced hepatic mRNA expression of TLR4, myeloid differentiation factor 88, IL-1 receptor-associated kinase 1 and TNF-α receptor-associated factor 6, and NOD1, NOD2 and receptor-interacting serine/threonine-protein kinase 2, as well as reduced hepatic protein expression of NF-κB p65, leading to reduced hepatic pro-inflammatory mediators. These results indicate that fish oil improves liver integrity partially via inhibition of TLR4 and NOD signaling pathways under an inflammatory condition.

Protective effects of N-acetylcysteine on acetic acid-induced colitis in a porcine model

BackgroundUlcerative colitis is a chronic inflammatory disease and involves multiple etiological factors. Acetic acid (AA)-induced colitis is a reproducible and simple model, sharing many characteristics with human colitis. N-acetylcysteine (NAC) has been widely used as an antioxidant in vivo and in vitro. NAC can affect several signaling pathways involving in apoptosis, angiogenesis, cell growth and arrest, redox-regulated gene expression, and inflammatory response. Therefore, NAC may not only protect against the direct injurious effects of oxidants, but also beneficially alter inflammatory events in colitis. This study was conducted to investigate whether NAC could alleviate the AA-induced colitis in a porcine model.MethodsWeaned piglets were used to investigate the effects of NAC on AA-induced colitis. Severity of colitis was evaluated by colon histomorphology measurements, histopathology scores, tissue myeloperoxidase activity, as well as concentrations of malondialdehyde and pro-inflammatory mediators in the plasma and colon. The protective role of NAC was assessed by measurements of antioxidant status, growth modulator, cell apoptosis, and tight junction proteins. Abundances of caspase-3 and claudin-1 proteins in colonic mucosae were determined by the Western blot method. Epidermal growth factor receptor, amphiregulin, tumor necrosis factor-alpha (TNF-α), and toll-like receptor 4 (TLR4) mRNA levels in colonic mucosae were quantified using the real-time fluorescent quantitative PCR.ResultsCompared with the control group, AA treatment increased (P < 0.05) the histopathology scores, intraepithelial lymphocyte (IEL) numbers and density in the colon, myeloperoxidase activity, the concentrations of malondialdehyde and pro-inflammatory mediators in the plasma and colon, while reducing (P < 0.05) goblet cell numbers and the protein/DNA ratio in the colonic mucosa. These adverse effects of AA were partially ameliorated (P < 0.05) by dietary supplementation with NAC. In addition, NAC prevented the AA-induced increase in caspase-3 protein, while stimulating claudin-1 protein expression in the colonic mucosa. Moreover, NAC enhanced mRNA levels for epidermal growth factor and amphiregulin in the colonic mucosa.ConclusionDietary supplementation with NAC can alleviate AA-induced colitis in a porcine model through regulating anti-oxidative responses, cell apoptosis, and EGF gene expression.

Effects of L-proline on the Growth Performance, and Blood Parameters in Weaned Lipopolysaccharide (LPS)-challenged Pigs

This trail was conducted to study the effect of L-proline on the growth performance, and blood parameter in the weaned lipopolysaccharide (LPS)-challenged pigs. Thirty six pigs (9.13±0.85 kg) were assigned randomly to dietary treatments in a 2×3 factorial arrangement in a 20-d growth assay. Factors were intraperitoneal injection with saline or LPS, and three dietary L-proline supplement levels (0%, 0.5%, or 1.0%). On d 10, blood samples were collected at 3 h after LPS (100 μg LPS/kg body weight [BW]) or saline injection. On d 20 of the trial, all pigs were orally administrated D-xylose (0.1 g/kg BW) at 2 h, and blood samples were collected at 3 h after LPS or saline injection. As a result, dietary supplementation with 0.5% proline had a tendency to increase average daily gain (ADG) in piglets during d 10 to 20 (p = 0.088). Without LPS challenge, dietary supplementation with 1.0% proline had no effect on growth hormone (GH) concentrations on d 10 (p>0.05), but decreased it after LPS challenge (p<0.05). There was LPS challenge×proline interaction for GH concentrations on d 10 (p<0.05). Dietary supplementation with 1.0% proline decreased glucagon concentration on d 10 after LPS challenge (p<0.05). In addition, dietary supplementation with proline increased superoxide dismutase (SOD) activity significantly on d 10 and 20 (p<0.05), and 1.0% proline increased heat shock proteins-70 concentration on d 10 (p<0.05). Moreover, proline supplementation increased diamine oxidase (DAO) concentrations after LPS challenge (p<0.05). There was LPS challenge×proline interaction for DAO (p<0.05). Furthermore, dietary supplementation with 1.0% proline increased the D-xylose level when no LPS challenge (p<0.05). These results indicate that proline supplementation could improve growth performance, increase SOD activities, and has a positive effect on the gastrointestinal tract digestibility in early weaned pigs.

Beneficial roles of dietary oleum cinnamomi in alleviating intestinal injury.

Cinnamon is a traditional herb used for treatment of many human diseases. The most important chemical compounds of the essential oil are cinnamaldehyde and eugenol. Oleum cinnamomi (OCM, cinnamon oil) is increasingly used as a feed additive to animal diets. Beneficial effects of OCM in protecting tissues from inflammation and injury by endogenous and exogenous agents (such as hydrogen peroxide and lipopolysaccharide (LPS)) may result, in part, from its action on regulating amino acid metabolism in cells to favor the synthesis of glutathione (a major low-molecular-weight antioxidant) from cysteine, glycine and glutamate. In support of this notion, results of recent studies indicate that supplementing OCM (50 mg/kg diet) to a corn- and soybean meal-based diet for piglets weaned at 21 days of age enhances intestinal anti-oxidative capacity and reduces the incidence of diarrhea. Additionally, dietary supplementation with OCM ameliorates LPS-induced mucosal barrier dysfunction and mucosal damage in the small intestine. OCM holds great promise for protecting the gut from injury under conditions of inflammation, infections, and oxidative stress.