Quercetin and L-Arginine Ameliorated the Deleterious Effects of Copper Oxide Nanoparticles on the Liver of Mice Through Anti-inflammatory and Anti-apoptotic Pathways

The widespread use and applications of copper oxide nanoparticles (CuO NPs) in daily life make human exposure to these particles inevitable. This study was carried out to investigate the deteriorations in hepatic and serum biochemical parameters induced by CuO NPs in adult male mice and the potential ameliorative effect of L-arginine and quercetin, either alone or in combination. Seventy adult male mice were equally allocated into seven groups: untreated group, L-arginine, quercetin, CuO NPs, arginine + CuO NPs, quercetin + CuO NPs, and quercetin + arginine + CuO NPs. Treating mice with CuO NPs resulted in bioaccumulation of copper in the liver and consequent liver injury as typified by elevation of serum ALT activity, reduction in the synthetic ability of the liver indicated by a decrease in the hepatic arginase activity, and serum total protein content. This copper accumulation increased oxidative stress, lipid peroxidation, inflammation, and apoptosis as manifested by elevation in malondialdehyde, nitric oxide, tumor necrosis factor-α, the expression level of caspase-3 and bax quantified by qPCR, and the activity of caspase-3, in addition to the reduction of superoxide dismutase activity. It also resulted in severe DNA fragmentation as assessed by Comet assay and significant pathological changes in the liver architecture. The study proved the efficiency of quercetin and L-arginine in mitigating CuO NPs-induced sub-chronic liver toxicity due to their antioxidant, anti-inflammatory, and anti-apoptotic properties; ability to inhibit DNA damage; and the potential as good metal chelators. The results of histopathological analysis confirmed the biochemical and molecular studies.

Effect of Supplementation with Black Soldier Fly Extract on Intestinal Function in Piglets Infected with Porcine Epidemic Diarrhea Virus

Porcine epidemic diarrhea virus (PEDV) has developed as a global problem for the pig business, resulting in significant financial losses. Black soldier fly extract (BFE) has been proven to improve intestinal growth in pigs after weaning. Consequently, the goal of the present investigation was to explore the effects of BFE supplementation on intestinal function in PEDV-infected piglets. Eighteen piglets were randomly allocated to three groups: control, PEDV, and BFE + PEDV. The piglets in the BFE + PEDV group received 500 mg/kg BW of BFE orally for seven days from day 4 to 10 of the study. On day 9 of the study, six pigs from each group received either clean saline or PEDV solution at a dosage of 106 TCID50 (50% tissue culture infectious dose) per pig. On day 11, samples of blood and intestine were taken for additional investigation. The results indicated a significant decrease in the average daily gain (ADG) of piglets infected with PEDV (p < 0.05). Additionally, PEDV infection led to an alteration of blood indexes and a reduction in plasma D-xylose concentration and villi height in the small intestine, while it increased plasma diamine oxidase activity and small intestinal crypt depth in piglets (p < 0.05). The PEDV infection significantly reduced antioxidant enzyme activity in plasma and the gut, including total superoxide dismutase and catalase, while increasing contents of oxidation-relevant products such as malondialdehyde and hydrogen peroxide in piglets. Moreover, PEDV infection increased the mRNA expression level of antiviral-related genes (p < 0.05). Nutritional supplementation with BFE improved intestinal histomorphological indicators and reduced oxidative stress produced by PEDV infection in piglets. Interestingly, BFE could significantly promote the mRNA expression level of antiviral-related genes in the ileum (p < 0.05). Overall, the preliminary results suggest that dietary BFE could improve intestinal function in piglets after PEDV infection. Currently, the findings put a spotlight on the role of BFE in the prevention and treatment of PED in piglets.

Effects of monolaurin on intestinal barrier, blood biochemical profile, immunity and antioxidant function in porcine epidemic diarrhoea virus-infected piglets

The effects of monolaurin (ML) on the health of piglets infected with porcine epidemic diarrhoea virus (PEDV) have not been fully understood. This study aimed to investigate its role in blood biochemical profile, intestinal barrier function, antioxidant function and the expression of antiviral genes in piglets infected with PEDV. Thirty-two piglets were randomly divided into four groups: control group, ML group, PEDV group and ML + PEDV group. Piglets were orally administrated with ML at a dose of 100 mg/kg·BW for 7 d before PEDV infection. Results showed that PEDV infection significantly decreased D-xylose content and increased intestinal fatty acid-binding protein content, indicating that PEDV infection destroyed intestinal barrier and absorption function. While it could be repaired by ML administration. Moreover, ML administration significantly decreased plasma blood urea nitrogen and total protein content upon PEDV infection. These results suggested ML may increase protein utilisation efficiency. ML administration significantly decreased the number of large unstained cells and Hb and increased the number of leucocytes and eosinophils in the blood of PEDV-infected piglets, indicating ML could improve the immune defense function of the body. In the presence of PEDV infection, ML administration significantly increased superoxide dismutase and catalase activities in blood and colon, respectively, indicating ML could improve antioxidant capacity. Besides, ML administration reversed the expression of ISG15, IFIT3 and IL-29 throughout the small intestine and Mx1 in jejunum and ileum, indicating the body was in recovery from PEDV infection. This study suggests that ML could be used as a kind of feed additive to promote swine health upon PEDV infection.

The effect of chronic, non-pathogenic maternal immune activation on offspring postnatal muscle and immune outcomes

The objective was to determine the effects of maternal inflammation on offspring muscle development and postnatal innate immune response. Sixteen first-parity gilts were randomly allotted to repeated intravenous injections with lipopolysaccharide (LPS; n = 8, treatment code INFLAM) or comparable volume of phosphate buffered saline (CON, n = 8). Injections took place every other day from gestational day (GD) 70 to GD 84 with an initial dose of 10 μg LPS/kg body weight (BW) increasing by 12% each time to prevent endotoxin tolerance. On GD 70, 76, and 84, blood was collected at 0 and 4 h postinjection via jugular or ear venipuncture to determine tumor necrosis factor (TNF)-α, interleukin (IL)-6, and IL-1β concentrations. After farrowing, litter mortality was recorded, and the pig closest to litter BW average was used for dissection and muscle fiber characterization. On weaning (postnatal day [PND] 21), pigs were weighed individually and 2 barrows closest to litter BW average were selected for another study. The third barrow closest to litter BW average was selected for the postnatal LPS challenge. On PND 52, pigs were given 5 μg LPS/kg BW via intraperitoneal injection, and blood was collected at 0, 4, and 8 h postinjection to determine TNF-α concentration. INFLAM gilt TNF-α concentration increased (P < 0.01) 4 h postinjection compared to 0 h postinjection, while CON gilt TNF-α concentration did not differ between time points. INFLAM gilt IL-6 and IL-1β concentrations increased (P = 0.03) 4 h postinjection compared to 0 h postinjection on GD 70, but did not differ between time points on GD 76 and 84. There were no differences between INFLAM and CON gilts litter mortality outcomes (P ≥ 0.13), but INFLAM pigs were smaller (P = 0.04) at birth and tended (P = 0.09) to be smaller at weaning. Muscle and organ weights did not differ (P ≥ 0.17) between treatments, with the exception of semitendinosus, which was smaller (P < 0.01) in INFLAM pigs. INFLAM pigs tended (P = 0.06) to have larger type I fibers. INFLAM pig TNF-α concentration did not differ across time, while CON pig TNF-α concentration peaked (P = 0.01) 4 h postinjection. TNF-α concentration did not differ between treatments at 0 and 8 h postinjection, but CON pigs had increased (P = 0.01) TNF-α compared to INFLAM pigs 4 h postinjection. Overall, maternal immune activation did not alter pig muscle development, but resulted in suppressed innate immune activation.

Tryptophan alleviates lipopolysaccharide-induced liver injury and inflammation by modulating necroptosis and pyroptosis signaling pathways in piglets

The liver plays crucial roles in material metabolism and immune response. Bacterial endotoxin can cause various liver diseases, thereby causing significant economic losses to pig industry. Tryptophan is an essential amino acid in piglets. However, whether tryptophan can alleviate liver injury and inflammation by regulating necroptosis and pyroptosis has not been clarified. This study aimed to investigate whether dietary tryptophan can alleviate lipopolysaccharide (LPS)-induced liver injury in weaned piglets. 18 weaned piglets were randomly distributed to three treatments, each with 6 replicates: (1) control; (2) LPS-challenged control; (3) LPS + 0.2% tryptophan. After feeding with control or 0.2% tryptophan-supplemented diets for 35 d, pigs were intraperitoneally injected with saline or LPS (100 mg/kg body weight). At 4 h post-injection, blood samples and liver were collected. Results indicated that tryptophan reduced alanine aminotransferase, aspartate aminotransferase, decreased the mRNA expression and protein expression of 70-kDa heat shock proteins. Moreover, tryptophan increased the mRNA expression and protein expression of claudin-1, occludin and zonula occludens and decreased hydrogen peroxide and malondialdehyde contents, and increased catalase, glutathione peroxidase and total superoxide dismutase activities and proinflammatory cytokine levels in the liver. Meanwhile, tryptophan inhibited pyroptosis-related and necroptosis-related protein expression in liver. Collectively, tryptophan could relieve liver damage, increased the antioxidant capacity and reduced inflammation by inhibiting pyroptosis and necroptosis signaling pathways.

Development and Recovery of Liver Injury in Piglets by Incremental Injection of LPS

This study aimed to explore the effects of the incremental injection of lipopolysaccharide (LPS) on liver histopathology, inflammation, oxidative status, and mitochondrial function in piglets. Forty healthy Duroc × Landrace × Yorkshire castrated boars (21 ± 2 days old, weight 6.84 ± 0.11 kg) were randomly assigned to five groups (n = 8) and then slaughtered on days 0 (group 0, without LPS injection), 1 (group 1), 5 (group 5), 9 (group 9), and 15 (group 15) of LPS injection, respectively. The results showed that, compared to the piglets without LPS injection, LPS injection caused liver injury in the early phase, as manifested by the increased activities of serum liver injury-related parameters (aspartate amino transferase, alanine aminotransferase, alkaline phosphatase, cholinesterase, and total bile acid) on day 1, and impaired liver morphology (disordered hepatic cell cord arrangement, dissolved and vacuolized hepatocytes, karyopycnosis, and inflammatory cell infiltration and congestion) on days 1 and 5. Meanwhile, LPS injection caused liver inflammation, oxidative stress, and mitochondrial dysfunction on days 1 and 5, as reflected by the upregulated mRNA expression of TNF-α, IL-6, IL-1β, TLR4, MyD88, and NF-κB; increased MPO and MDA content; and impaired mitochondrial morphology. However, these parameters were ameliorated in the later phase (days 9~15). Taken together, our data indicate that the incremental injection of the LPS-induced liver injury of piglets could be self-repaired.

RNA-Sequencing Characterization of lncRNA and mRNA Functions in Septic Pig Liver Injury

We assessed differentially expressed (DE) mRNAs and lncRNAs in the liver of septic pigs to explore the key factors regulating lipopolysaccharide (LPS)-induced liver injury. We identified 543 DE lncRNAs and 3642 DE mRNAs responsive to LPS. Functional enrichment analysis revealed the DE mRNAs were involved in liver metabolism and other pathways related to inflammation and apoptosis. We also found significantly upregulated endoplasmic reticulum stress (ERS)-associated genes, including the receptor protein kinase receptor-like endoplasmic reticulum kinase (PERK), the eukaryotic translation initiation factor 2α (EIF2S1), the transcription factor C/EBP homologous protein (CHOP), and activating transcription factor 4 (ATF4). In addition, we predicted 247 differentially expressed target genes (DETG) of DE lncRNAs. The analysis of protein-protein interactions (PPI) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway detected key DETGs that are involved in metabolic pathways, such as N-Acetylgalactosaminyltransferase 2 (GALNT2), argininosuccinate synthetase 1 (ASS1), and fructose 1,6-bisphosphatase 1 (FBP1). LNC_003307 was the most abundant DE lncRNA in the pig liver, with a marked upregulation of >10-fold after LPS stimulation. We identified three transcripts for this gene using the rapid amplification of the cDNA ends (RACE) technique and obtained the shortest transcript sequence. This gene likely derives from the nicotinamide N-methyltransferase (NNMT) gene in pigs. According to the identified DETGs of LNC_003307, we hypothesize that this gene regulates inflammation and endoplasmic reticulum stress in LPS-induced liver damage in pigs. This study provides a transcriptomic reference for further understanding of the regulatory mechanisms underlying septic hepatic injury.

Effects of arginine replacement with L-citrulline on the arginine/nitric oxide metabolism in chickens: An animal model without urea cycle

BACKGROUND

This study examined the efficacy of L-citrulline supplementation on the arginine/nitric oxide metabolism, and intestinal functions of broilers during arginine deficiency. A total of 288 day-old Arbor Acre broilers were randomly assigned to either an arginine deficient basal diet (NC diet), NC diet + 0.50% L-arginine (PC diet), or NC diet + 0.50% L-citrulline (NCL diet). Production performance was recorded, and at 21 days old, chickens were euthanized for tissue collection.

RESULTS

The dietary treatments did not affect the growth performance of broilers (P > 0.05), although NC diet increased the plasma alanine aminotransferase, urate, and several amino acids, except arginine (P < 0.05). In contrast, NCL diet elevated the arginine and ornithine concentration higher than NC diet, and it increased the plasma citrulline greater than the PC diet (P < 0.05). The nitric oxide concentration in the kidney and liver tissues, along with the plasma and liver eNOS activities were promoted by NCL diet higher than PC diet (P < 0.05). In the liver, the activities of arginase 1, ASS, and ASL, as well as, the gene expression of iNOS and OTC were induced by PC diet greater than NC diet (P < 0.05). In the kidney, the arginase 1, ASS and ASL enzymes were also increased by PC diet significantly higher than the NC and NCL diets. Comparatively, the kidney had higher abundance of nNOS, ASS, ARG2, and OTC genes than the liver tissue (P < 0.05). In addition, NCL diet upregulated (P < 0.05) the mRNA expression of intestinal nutrient transporters (EAAT3 and PEPT1), tight junction proteins (Claudin 1 and Occludin), and intestinal mucosal defense (MUC2 and pIgR). The intestinal morphology revealed that both PC and NCL diets improved (P < 0.05) the ileal VH/CD ratio and the jejunal VH and VH/CD ratio compared to the NC fed broilers.

CONCLUSION

This study revealed that NCL diet supported arginine metabolism, nitric oxide synthesis, and promoted the intestinal function of broilers. Thus, L-citrulline may serve as a partial arginine replacement in broiler's diet without detrimental impacts on the performance, arginine metabolism and gut health of chickens.

Effects of Continuous LPS Induction on Oxidative Stress and Liver Injury in Weaned Piglets

Due to imperfections in their immune and digestive systems, weaned piglets are susceptible to invasions of the external environment and diseases, especially bacterial infections, which lead to slow growth, tissue damage, and even the death of piglets. Here, a model of weaned piglets induced by Escherichia coli lipopolysaccharide (LPS) was established to explore the effects of continuous low-dose LPS induction on the mechanism of liver injury. A total of forty-eight healthy 28-day-old weaned piglets (weight = 6.65 ± 1.19 kg) were randomly divided into two groups: the CON group and LPS group. During the experimental period of thirteen days, the LPS group was injected intraperitoneally with LPS (100 μg/kg) once per day, and the CON group was treated with the same volume of 0.9% NaCl solution. On the 1st, 5th, 9th, and 13th days, the serum and liver of the piglets were collected for the determination of serum biochemical indexes, an antioxidant capacity evaluation, and histopathological examinations. In addition, the mRNA expression levels of the TLR4 pathway and inflammatory cytokines were detected. The results showed that the activities of aspartate aminotransferase (AST), alanine aminotransferase (ALT), and alkaline phosphatase (ALP) in the serum increased after LPS induction. The activities of total antioxidant capacity (T-AOC) and glutathione peroxidase (GSH-Px) in the serum and liver homogenate of the LPS group were lower than those of the CON group, while the malondialdehyde (MDA) content in the serum and the activities of catalase (CAT) and superoxide dismutase (SOD) in the liver of the LPS group were higher than those in the CON group. At the same time, morphological impairment of the livers occurred, including hepatocyte caryolysis, hepatocyte vacuolization, karyopycnosis, and inflammatory cell infiltration, and the mRNA expression levels of TLR4, MyD88, NF-κB, TNF-α, IL-6, and IL-10 were upregulated in the livers after LPS induction. The above results were more obvious on the 1st and 5th days of LPS induction, while the trend during the later period was not significant. It was concluded that the oxidative stress and liver injury occurred at the early stage of LPS induction, while the liver damage weakened at the later stage. The weaned piglets probably gradually developed tolerance to the endotoxin after the continuous low-dose induction of LPS.

LPS-Induced Liver Injury of Magang Geese through Toll-like Receptor and MAPK Signaling Pathway

Lipopolysaccharide (LPS) is one of the main virulence factors of Gram-negative bacteria. In the process of waterfowl breeding, an inflammatory reaction due to LPS infection is easily produced, which leads to a decline in waterfowl performance. The liver plays a vital role in the immune response and the removal of toxic components. Therefore, it is necessary to study the mechanism of liver injury induced by LPS in goose. In this study, a total of 100 1-day-old goslings were randomly divided into a control group and LPS group after 3 days of pre-feeding. On days 21, 23, and 25 of the formal experiment, the control group was intraperitoneally injected with 0.5 mL normal saline, and the LPS group was intraperitoneally injected with LPS 2 mg/(kg body weight) once a day. On day 25 of the experiment, liver samples were collected 3 h after the injection of saline and LPS. The results of histopathology and biochemical indexes showed that the livers of the LPS group had liver morphological structure destruction and inflammatory cell infiltration, and the levels of ALT and AST were increased. Next, RNA sequencing analysis was used to determine the abundances and characteristics of the transcripts, as well as the associated somatic mutations and alternative splicing. We screened 727 differentially expressed genes (DEGs) with p < 0.05 and |log2(Fold Change)| ≥ 1, as the thresholds; GO and KEGG enrichment analysis showed that LPS-induced liver injury may be involved in the Toll-like receptor signaling pathway, MAPK signaling pathway, NOD-like receptor signaling pathway, FoxO, and PPAR signaling pathway. Finally, we intersected the genes enriched in the key pathway of LPS-induced liver injury with the top 50 key genes in protein−protein interaction networks to obtain 28 more critical genes. Among them, 17 genes were enriched in Toll-like signaling pathway and MAPK signaling pathway. Therefore, these results suggest that LPS-induced liver injury in geese may be the result of the joint action of Toll-like receptor, MAPK, NOD-like receptor, FoxO, and PPAR signaling pathway. Among them, the TLR7-mediated MAPK signaling pathway plays a major role.

A metagenome-wide association study of the gut microbiota in recurrent aphthous ulcer and regulation by thalidomide

Recurrent aphthous ulcer (RAU), one of the most common diseases in humans, has an unknown etiology and is difficult to treat. Thalidomide is an important immunomodulatory and antitumor drug and its effects on the gut microbiota still remain unclear. We conducted a metagenomic sequencing study of fecal samples from a cohort of individuals with RAU, performed biochemical assays of cytokines, immunoglobulins and antimicrobial peptides in serum and saliva, and investigated the regulation effects of thalidomide administration and withdrawal. Meanwhile we constructed the corresponding prediction models. Our metagenome-wide association results indicated that gut dysbacteriosis, microbial dysfunction and immune imbalance occurred in RAU patients. Thalidomide regulated gut dysbacteriosis in a species-specific manner and had different sustainable effects on various probiotics and pathogens. A previously unknown association between gut microbiota alterations and RAU was found, and the specific roles of thalidomide in modulating the gut microbiota and immunity were determined, suggesting that RAU may be affected by targeting gut dysbacteriosis and modifying immune imbalance. In-depth insights into sophisticated networks consisting of the gut microbiota and host cells may lead to the development of emerging treatments, including prebiotics, probiotics, synbiotics, and postbiotics.

FXR/ASS1 axis attenuates the TAA-induced liver injury through arginine metabolism

Previous studies demonstrated that arginine biosynthesis was frequently impaired in acute liver injury. However, the underlying mechanisms remain elusive. In this study, we found that Argininosuccinate synthetase 1 (ASS1), a rate-limiting enzyme in arginine metabolism, was downregulated in the TAA-induced liver injury model. Single-cell RNA-seq data found that ASS1 was highly enriched in the hepatocytes. The reduction of ASS1 was attributed to the decreased expression of Farnesoid X receptor (FXR), which is a bile acid-activated nuclear hormone receptor with high expression in the liver. Subsequent studies demonstrated that activation of FXR by its agonist obeticholic acid (OCA) directly promoted ASS1 transcription and enhanced arginine synthesis, leading to the alleviation of TAA-mediated liver injury. Further experiments found that OCA, ASS1, and arginine supplement can rescue TAA-mediated hepatocytes apoptosis by decreasing the protein levels of Cyto C, PARP, and Caspase 3. Taken together, our study illustrated a protective role of the FXR/ASS1 axis in TAA-induced liver injury by targeting arginine metabolism, which might shed light on the development of novel therapeutic approaches for acute liver injury.

Metabonomics Study on the hepatoprotective effect mechanism of polysaccharides from different processed products of Angelica Sinensis on the layer chickens based on UPLC-Q/TOF-MS/MS, multivariate statistical analysis and conjoint analysis

Chicken colibacillosis is one of the most severe diseases in the poultry industry. Ceftiofur sodium (CS) is often used to treat it in clinical practice and lipopolysaccharide (LPS) accumulates in the chicken's body. Previous experimental studies found that CS combined with LPS could induce liver injury in layer chickens, and polysaccharides from charred Angelica sinensis(CASP) had a better hepatoprotective effect than polysaccharides from unprocessed Angelica sinensis(UASP). However, the intervention mechanism was unclear. Thus, UPLC–Q/TOF–MS/MS‐based metabonomics and transcriptomics were used in this study to clarify the hepatoprotective effect mechanism of CASP and UASP in layer chickens. Transcriptomics and enzyme‐linked immunosorbent assay were used for biological verification of some critical mutual metabolic pathways screened with metabonomics. The comprehensive analysis results showed that in a layer chicken liver injury model built with LPS and CS, 12 critical metabolic pathways were disturbed, involving 10 important differential metabolites. The hepatoprotective effect mechanism of CASP is related to the arachidonic acid metabolism and mTOR signaling pathways, involving nine important differential metabolites. In contrast, the hepatoprotective effect mechanism of UASP is related to the arachidonic acid metabolism pathway, involving six important differential metabolites.

Increased Ingestion of Hydroxy-Methionine by Both Sows and Piglets Improves the Ability of the Progeny to Counteract LPS-Induced Hepatic and Splenic Injury with Potential Regulation of TLR4 and NOD Signaling

Methionine, as an essential amino acid, play roles in antioxidant defense and the regulation of immune responses. This study was designed to determine the effects and mechanisms of increased consumption of methionine by sows and piglets on the capacity of the progeny to counteract lipopolysaccharide (LPS) challenge-induced injury in the liver and spleen of piglets. Primiparous sows (n = 10/diet) and their progeny were fed a diet that was adequate in sulfur amino acids (CON) or CON + 25% total sulfur amino acids as methionine from gestation day 85 to postnatal day 35. A total of ten male piglets were selected from each treatment and divided into 2 groups (n = 5/treatment) for a 2 × 2 factorial design [diets (CON, Methionine) and challenge (saline or LPS)] at 35 d old. After 24 h challenge, the piglets were euthanized to collect the liver and spleen for the histopathology, redox status, and gene expression analysis. The histopathological results showed that LPS challenge induced liver and spleen injury, while dietary methionine supplementation alleviated these damages that were induced by the LPS challenge. Furthermore, the LPS challenge also decreased the activities of GPX, SOD, and CAT and upregulated the mRNA and(or) protein expression of TLR4, MyD88, TRAF6, NOD1, NOD2, NF-kB, TNF-α, IL-8, p53, BCL2, and COX2 in the liver and (or) spleen. The alterations of GPX and SOD activities and the former nine genes were prevented or alleviated by the methionine supplementation. In conclusion, the maternal and neonatal dietary supplementation of methionine improved the ability of piglets to resist LPS challenge-induced liver and spleen injury, potentially through the increased antioxidant capacity and inhibition of TLR4 and NOD signaling pathway.

Dietary Supplementation with Enterococcus faecium R1 Attenuates Intestinal and Liver Injury in Piglets Challenged by Lipopolysaccharide

Simple Summary

The biological characteristics of E. faecium R1 and the effect of dietary supplementation with E. faecium R1 on the growth performance of weaned piglets were studied. The results showed that E. faecium R1 had the characteristics of effective bacteriostatic activity, acid resistance, bile salt resistance, and high-temperature resistance. Dietary supplementation with E. faecium R1 (6.5 × 10⁶ CFU/g) improved intestinal function of weaning piglets by decreasing diarrhea incidence. Further research found that dietary supplementation with E. faecium R1 (6.5 × 10⁶ CFU/g) attenuated intestinal and liver injury in piglets challenged by lipopolysaccharide.

Abstract

In this study, a strain of E. faecium R1 with effective bacteriostatic activity, acid resistance, bile salt resistance, high-temperature resistance was screened. To study the effect of E. faecium R1 on lipopolysaccharide (LPS)-induced intestinal and liver injury in piglets, twenty-four weaned female piglets were randomly assigned into one of three groups (8 piglets per group). Piglets in the control group and LPS group were fed a basal diet, piglets in the E. faecium group were fed the basal diet supplemented with E. faecium R1 (6.5 × 10⁶ CFU/g). On day 21 of the trial, piglets in the LPS group and E. faecium group were intraperitoneally administered LPS (100 μg/kg), piglets in the control group were administered the same volume of saline. Subsequently, blood samples were collected at 3 h, and intestinal, liver, and pancreas samples were collected at 6 h. Results showed that E. faecium R1 supplementation significantly decreased the diarrhea rate and feed to gain ratio, and dramatically reduced LPS-induced intestinal and liver injury in piglets. Compared with the LPS group, E. faecium R1 supplementation significantly increased the content of glucagon in plasma and IL-1β in the liver, and the mRNA levels of villin in jejunum and ileum and Bcl-xL and pBD-L in the ileum, and significantly decreased the contents of prostaglandin 2 and malondialdehyde in the liver and the activities of myeloperoxidase and aspartate aminotransferase in plasma in piglets. Moreover, E. faecium R1 improved the pancreatic antioxidant capacity in piglets, which was indicated by a significant increase in catalase activity and a decrease in total nitric oxide synthase activity. In summary, dietary supplementation with E. faecium R1 alleviates intestinal and liver injury in LPS-challenged piglets.

Dietary Beta-Hydroxy Beta-Methyl Butyrate Supplementation Alleviates Liver Injury in Lipopolysaccharide-Challenged Piglets

The current study was performed to investigate whether dietary β-hydroxy-β-methylbutyrate (HMB) could regulate liver injury in a lipopolysaccharide- (LPS-) challenged piglet model and to determine the mechanisms involved. Thirty piglets (21 ± 2 days old, 5.86 ± 0.18 kg body weight) were randomly divided into the control (a basal diet, saline injection), LPS (a basal diet), or LPS+HMB (a basal diet + 0.60% HMB-Ca) group. After 15 d of treatment with LPS and/or HMB, blood and liver samples were obtained. The results showed that in LPS-injected piglets, HMB supplementation ameliorated liver histomorphological abnormalities induced by LPS challenge. Compared to the control group, the activities of serum aspartate aminotransferase and alkaline phosphatase were increased in the LPS-injected piglets (P < 0.05). The LPS challenge also downregulated the mRNA expression of L-PFK, ACO, L-CPT-1, ICDH β, and AMPKα1/2 and upregulated the mRNA expression of PCNA, caspase 3, TNF-α, TLR4, MyD88, NOD1, and NF-κB p65 (P < 0.05). However, these adverse effects of the LPS challenge were reversed by HMB supplementation (P < 0.05). These results indicate that HMB may exert protective effects against LPS-induced liver injury, and the underlying mechanisms might involve the improvement of hepatic energy metabolism via regulating AMPK signaling pathway and the reduction of liver inflammation via modulating TLR4 and NOD signaling pathways.

Necroptosis is active and contributes to intestinal injury in a piglet model with lipopolysaccharide challenge

Necroptosis, a newly discovered form of programmed cell death that combines the features of apoptosis and necrosis, is important in various physiological and pathological disorders. However, the role of necroptosis on intestinal injury during sepsis has been rarely evaluated. This study aimed to investigate the presence of necroptosis in intestinal injury, and its contribution to intestinal injury in a piglet model challenged with Escherichia coli lipopolysaccharide (LPS). Firstly, a typical cell necrotic phenomenon was observed in jejunum of LPS-challenged pigs by transmission electron microscope. Protein expression of necroptosis signals including receptor-interacting protein kinase (RIP) 1, RIP3, and phosphorylated mixed-lineage kinase domain-like protein (MLKL), mitochondrial proteins including phosphoglycerate mutase family member 5 (PGAM5) and dynamin-related protein 1 (DRP1), and cytoplasmic high-mobility group box 1 (HMGB1) were time-independently increased in jejunum of LPS-challenged piglets, which was accompanied by the impairment of jejunal morphology, and digestive and barrier function indicated by lower activities of jejunal disaccharidases and protein expression of jejunal tight junction proteins claudin-1 and occludin. Pro-inflammatory cytokines including tumor necrosis factor-α (TNF-α), interleukin (IL)-1β, and IL-6 were also dynamically induced in serum and jejunum of piglets after LPS challenge. Moreover, pretreatment with necrostatin-1 (Nec-1), an specific inhibitor of necroptosis, inhibited necroptosis indicated by decreased necrotic ultrastructural changes and decreased protein expression of RIP1, RIP3, and phosphorylated MLKL as well as PGAM5, DRP1, and cytoplasmic HMGB1. Nec-1 pretreatment reduced jejunal morphological injury, and improved digestive and barrier function. Nec-1 pretreatment also decreased the levels of serum and jejunal pro-inflammatory cytokines and the numbers of jejunal macrophages and monocytes. These findings indicate for the first time that necroptosis is present and contributes to LPS-induced intestinal injury. Nec-1 may have a preventive effect on intestinal injury during sepsis.

Chemical composition and anti-oxidant potential on essential oils of Thymus quinquecostatus Celak. from Loess Plateau in China, regulating Nrf2/Keap1 signaling pathway in zebrafish

Chemical profile and antioxidant potency of essential oils (EOs) of Thymus quinquecostatus Celak. (thyme oils) obtained from Loess Plateau in China had been studied. 130 constituents of thyme oils were determined using gas chromatography-mass spectrometry (GC–MS) and carvacrol ethyl ether was firstly reported as a new natural product, which has been used as a synthetic flavoring substance with no safety concern. The thyme oils showed the anti-oxidant activity using 2,2 diphenyl-1-picrylhydrazyl (DPPH), 2,2′-azino-bis-(3-ethylbenzothiazoline-6-sulfonate) (ABTS), ferric reducing antioxidant power (FRAP) and thiobarbituric acid reactive substances (TBARS) and conferred protection against oxidative stress in zebrafish. In addition, a class of carvacrol analogues was found to develop as potential natural antioxidant products of thyme oils from Loess Plateau by the correlation analysis. YL-thyme oil performed the best antioxidant activity in this research, which could be recommended as preferred sources of thyme oils. Furthermore, YL-thyme oil exhibited a potent antioxidant capacity by reactive oxygen species (ROS) scavenging, enhancing the endogenous antioxidant system, inhibiting lipid peroxidation and activation of Keap1/Nrf2 pathway in zebrafish.

Dietary glutamine, glutamate, and aspartate supplementation improves hepatic lipid metabolism in post-weaning piglets

A previous study has demonstrated that early weaning significantly suppressed hepatic glucose metabolism in piglets. Glutamate (Glu), aspartate (Asp) and glutamine (Gln) are major metabolic fuels for the small intestine and can alleviate weaning stress, and therefore might improve hepatic energy metabolism. The objective of this study was to investigate the effects of administration of Glu, Asp and Gln on the expression of hepatic genes and proteins involved in lipid metabolism in post-weaning piglets. Thirty-six weaned piglets were assigned to the following treatments: control diet (Control; basal diet + 15.90 g/kg alanine); Asp, Gln and Glu-supplemented diet (Control + AA; basal diet + 1.00 g/kg Asp + 5.00 g/kg Glu + 10.00 g/kg Gln); and the energy-restricted diet supplemented with Asp, Gln and Glu (Energy⁻ + AA; energy deficient diet + 1.00 g/kg Asp + 5.00 g/kg Glu + 10.00 g/kg Gln). Liver samples were obtained on d 5 and 21 post-weaning. Piglets fed Energy⁻ + AA diet had higher liver mRNA abundances of acyl-CoA oxidase 1 (ACOX1), succinate dehydrogenase (SDH), mitochondrial transcription factor A (TFAM) and sirtuin 1 (SIRT1), as well as higher protein expression of serine/threonine protein kinase 11 (LKB1), phosphor-acetyl-CoA carboxylase (P-ACC) and SIRT1 compared with piglets fed control diet (P < 0.05) on d 5 post-weaning. Control + AA diet increased liver malic enzyme 1 (ME1) and SIRT1 mRNA levels, as well as protein expression of LKB1 and P-ACC on d 5 post-weaning (P < 0.05). On d 21 post-weaning, compared to control group, Glu, Gln and Asp supplementation up-regulated the mRNA levels of ACOX1, ME1 and SIRT1 (P < 0.05). These findings indicated that dietary Glu, Gln and Asp supplementation could improve hepatic lipid metabolism to some extent, which may provide nutritional intervention for the insufficient energy intake after weaning in piglets.

Increased Consumption of Sulfur Amino Acids by Both Sows and Piglets Enhances the Ability of the Progeny to Adverse Effects Induced by Lipopolysaccharide

Simple Summary

Our results suggest that maternal consumption of total sulfur amino acids exceeding the NRC 2012 recommendations by 25% during late gestation and lactation benefits sow productivity and piglet neonatal performance. Moreover, increased consumption of sulfur amino acids by both sows and post-weaned piglets improved their ability to counteract the adverse effects by lipopolysaccharide (LPS) exposure. In addition, OH-Met showed a better response than DL-Met in both neonatal and weaned piglets. Taken together, our findings indicate that it might be necessary to update the recommendations for sulfur amino acids for gestating and lactating sows. Attention should also be given to sulfur amino acids supply during an inflammatory challenge as often encountered by piglets early in life.

Abstract

This study determined the effects of increased consumption of sulfur amino acids (SAA), as either DL-Met or Hydroxy-Met (OH-Met), by sows and piglets on their performance and the ability of the progeny to resist a lipopolysaccharide (LPS) challenge. Thirty primiparous sows were fed a diet adequate in SAA (CON) or CON + 25% SAA, either as DL-Met or OH-Met from gestation day 85 to postnatal day 21. At 35 d old, 20 male piglets from each treatment were selected and divided into 2 groups (n = 10/treatment) for a 3 × 2 factorial design [diets (CON, DL-Met or OH-Met) and challenge (saline or LPS)]. OH-Met and/or DL-Met supplementation increased (p ≤ 0.05) piglets’ body weight gain during day 0–7 and day 7–14. Sow’s milk quality was improved in the supplemented treatments compared to the CON. The LPS challenge decreased (p ≤ 0.05) piglets’ performance from 35 to 63 d and increased (p ≤ 0.05) the levels of aspartate aminotransferase, total bilirubin, IL-1β, IL-6, TNF-a, and malondialdehyde. Plasma albumin, total protein, total antioxidant capacity and glutathione peroxidase decreased post-challenge. The results were better with OH-Met than DL-Met. The increase of Met consumption, particularly as OH-Met increased piglets’ growth performance during the lactation phase and the challenging period.

Effects of intravenous arginine infusion on inflammation and metabolic indices of dairy cows in early lactation

Enhancing the supply of arginine (Arg), a semi-essential amino acid, has positive effects on immune function in dairy cattle experiencing metabolic stress during early lactation. Our objective was to determine the effects of Arg supplementation on biomarkers of liver damage and inflammation in cows during early lactation. Six Chinese Holstein lactating cows with similar BW (508 ± 14 kg), body condition score (3.0), parity (4.0 ± 0), milk yield (30.6 ± 1.8 kg) and days in milk (20 ± days) were randomly assigned to three treatments in a replicated 3 × 3 Latin square design balanced for carryover effects. Each period was 21 days with 7 days for infusion and 14 days for washout. Treatments were (1) Control: saline; (2) Arg group: saline + 0.216 mol/day l-Arg; and (3) Alanine (Ala) group: saline + 0.868 mol/day l-Ala (iso-nitrogenous to the Arg group). Blood and milk samples from the experimental cows were collected on the last day of each infusion period and analyzed for indices of liver damage and inflammation, and the count and composition of somatic cells in milk. Compared with the Control, the infusion of Arg led to greater concentrations of total protein, immunoglobulin M and high density lipoprotein cholesterol coupled with lower concentrations of haptoglobin and tumor necrosis factor-α, and activity of aspartate aminotransferase in serum. Infusion of Ala had no effect on those biomarkers compared with the Control. Although milk somatic cell count was not affected, the concentration of granulocytes was lower in response to Arg infusion compared with the Control or Ala group. Overall, the biomarker analyses indicated that the supplementation of Arg via the jugular vein during early lactation alleviated inflammation and metabolic stress.

Impact of zinc and arginine on antioxidant status of weanling piglets raised under commercial conditions

The effects of dietary zinc and L-arginine supplements on the weight gain, feed efficiency, antioxidant capacity and oxidative status of weanling piglets raised under commercial conditions were examined. A total of 288 piglets aged 21 d were fed for 15 d a diet supplemented or not with 2,500 mg/kg of zinc (provided as zinc oxide) and 1% L-arginine·HCl. The 4 treatments were distributed in a randomized complete block design with 6 initial body weight categories (12 animals per pen). Access to feed and water was ad libitum. Data were analyzed as a 2 × 2 factorial experiment using the SAS MIXED procedure, with zinc and arginine as the main independent variables. Blood collection day (d 8 and 15, samples were collected from the same 2 piglets in each pen before the morning feeding) was included as a third factor. The zinc supplement increased the average daily gain (ADG) from d 0 to 7, d 8 to 15 and d 0 to 15 (0.289 vs. 0.217 kg/d), average daily feed intake (ADFI) from d 8 to 15 and d 0 to 15 (0.338 vs. 0.279 kg/d) and the gain to feed (G:F) ratio from d 0 to 7 and d 0 to 15 (0.86 vs. 0.77) (P < 0.001). Both supplements significantly decreased the malondialdehyde concentration (zinc: 4.37 vs. 3.91 μmol/L, P = 0.005; arginine: 4.38 vs. 3.89 μmol/L, P = 0.002). Total antioxidant capacity and reduced glutathione (GSH) increased from d 8 to 15 (0.953 vs. 1.391 μmol/L, 2.22 vs. 3.37 μmol/L, P < 0.05) regardless of dietary treatment. Total and oxidized GSH concentrations on d 8 were higher in response to the combined supplements (zinc × arginine interaction, P < 0.05). Piglets fed either Zn-supplemented diet had a lower haptoglobin serum concentration (509 vs. 1,417 mg/L; P < 0.001). In conclusion, the zinc supplement improved piglet growth performance (ADG and ADFI) and oxidative status (based on malondialdehyde concentration). The arginine supplement had a limited effect on growth performance and oxidative status under these conditions.

Dietary Lysozyme Alters Sow's Gut Microbiota, Serum Immunity and Milk Metabolite Profile

The aim of current study was to determine variations in sow's gut microbiota, serum immunity, and milk metabolite profile mediated by lysozyme supplementation. Twenty-four pregnant sows were assigned to a control group without supplementation and two treatments with 0.5 kg/t and 1.0 kg/t lysozyme provided in formula feed for 21 days (n = 8 per treatment). Microbiota analysis and metagenomic predictions were based on 16s RNA high-throughput sequencing. Milk metabolome was assessed by untargeted liquid chromatography tandem mass spectrometry. Serum biochemical indicators and immunoglobulins were also determined. Gut microbial diversity of sows receiving 1.0 kg/t lysozyme treatment was significantly reduced after the trial. Spirochaetes, Euryarchaeota, and Actinobacteria significantly increased while Firmicutes showed a remarkable reduction in 1.0 kg/t group compared with control. Lysozyme addition rebuilt sow's gut microbiota to beneficial composition identified by reduced richness of Escherichia coli and increased abundance of Lactobacillus amylovorus. Accordingly, microbial metabolic functions including pyrimidine metabolism, purine metabolism, and amino acid related enzymes were significantly up-regulated in 1.0 kg/t group. Microbial metabolic phenotypes like the richness of Gram-positive bacteria and oxidative stress tolerance were also significantly reduced by lysozyme treatment. Serum alanine transaminase (ALT) activity and IgA levels were significantly down-regulated in the 1.0 kg/t group compared with control, but IgM levels showed a significantly increase in 1.0 kg/t group. Milk metabolites such as L-glutamine, creatine, and L-arginine showed significantly dose-dependent changes after treatment. Overall, lysozyme supplementation could effectively improve the composition, metabolic functions, and phenotypes of sow's gut microbiota and it also benefit sows with better serum immunity and milk composition. This research could provide theoretical support for further application of lysozyme in promoting animal gut health and prevent pathogenic infections in livestock production.

Effect of N-carbamoylglutamate supplementation on the growth performance, antioxidant status and immune response of mirror carp (Cyprinus carpio) fed an arginine-deficient diet

The present study was conducted to determine the effect of dietary N-carbamoylglutamate (NCG) supplementation on the growth performance, antioxidant capability and immune responses of mirror carp (Cyprinus carpio) fed an arginine (Arg)-deficient diet. A total of 630 mirror carp (41.65 ± 0.14 g) were fed diets (Arg 1.24% of the diet) that were supplemented with 0.50% Arg (control diet) or graded levels of NCG at 0 (Arg deficiency diet), 0.04%, 0.08%, 0.12%, 0.16% and 0.20% for 8 weeks. The results showed that, compared with the control diet, the Arg-deficient diet supplementation with 0 NCG (1) decreased the final body weight (FWB), the weight gain rate (WGR) or the protein efficiency ratio (PER) and increased the feed conversion ratio (FCR); (2) decreased the concentration of Arg and nitric oxide (NO) and the activity of total nitric oxide synthetase (T-NOS) in the plasma; (3) decreased the activities of superoxide dismutase (SOD) in the proximal intestine (PI), catalase (CAT) in the PI and distal intestine (DI), and glutathione peroxidase (GPx) in PI and mid-intestine (MI) and increased the concentration of malondialdehyde (MDA) in the PI, MI and DI; and (4) decreased the activity of lysozyme in the plasma, increased the relative mRNA expression of tumor necrosis factor-α (TNF-α), interleukin1β (IL-1β) and interleukin 8 (IL-8) in the PI, MI and DI, and decreased the relative mRNA expression of interleukin 10 (IL-10) in the PI and MI, and transforming growth factor β2 (TGF-β2) in the PI, MI and DI. Compared with the Arg deficient-diet supplementation with 0 NCG, (1) 0.12% or 0.16% NCG increased the FBW, WGR and PER, and 0.16% NCG increased the FCR; (2) 0.08%-0.20% NCG increased the concentration of Arg, NO and the activity of T-NOS; (3) 0.08% NCG increased the activities of SOD in the PI and MI, and 0.12% NCG increased activities of CAT and GPx in the PI, MI and DI; and (4) 0.04%-0.20% NCG increased the activity of lysozyme, 0.04%-0.20% NCG decreased the relative mRNA expression of TNF-α, IL-1β and IL-8 in the PI and MI, and 0.04%-0.20% NCG increased the relative mRNA expression of IL-10 and TGF-β2 in the PI and MI. The present results indicated that dietary 0.12% or 0.16% NCG improved the growth performance, feed utilization, intestinal antioxidant capacity and immune response of mirror carp fed an Arg-deficient diet.

Medium-Chain Triglycerides Attenuate Liver Injury in Lipopolysaccharide-Challenged Pigs by Inhibiting Necroptotic and Inflammatory Signaling Pathways

This study was conducted to investigate whether medium-chain triglycerides (MCTs) attenuated lipopolysaccharide (LPS)-induced liver injury by down-regulating necroptotic and inflammatory signaling pathways. A total of 24 pigs were randomly allotted to four treatments in a 2 × 2 factorial design including diet (0 and 4% MCTs) and immunological challenge (saline and LPS). After three weeks of feeding with or without 4% MCTs, pigs were challenged with saline or LPS. MCTs led to a significant increase in eicosapentaenoic acid, docosahexaenoic acid and total (n-3) polyunsaturated fatty acid concentrations. MCTs attenuated LPS-induced liver injury as indicated by an improvement in liver histomorphology and ultrastructural morphology of hepatocytes, a reduction in serum alanine aminotransferase and alkaline phosphatase activities as well as an increase in claudin-1 protein expression. In addition, MCTs also reduced serum tumor necrosis factor-α (TNF-α), interleukin (IL)-1β and IL-6 concentrations, liver TNF-α and IL-1β mRNA expression and protein concentrations and enhanced liver heat shock protein 70 protein expression in LPS-challenged pigs. Moreover, MCTs decreased mRNA expression of receptor-interacting serine/threonine-protein kinase (RIP) 3, mixed-lineage kinase domain-like protein (MLKL) and phosphoglycerate mutase 5 and inhibited MLKL phosphorylation in the liver. Finally, MCTs decreased liver mRNA expression of toll-like receptor (TLR) 4, nucleotide-binding oligomerization domain protein (NOD) 1 and multiple downstream signaling molecules. MCTs also suppressed LPS-induced p38 mitogen-activated protein kinase (MAPK) phosphorylation and increased extracellular signal-related kinase 1/2 phosphorylation in the liver. These results indicated that MCTs are capable of attenuating LPS-induced liver damage by suppressing hepatic necroptotic (RIP1/RIP3/MLKL) and inflammatory (TLR4/NOD1/p38 MAPK) signaling pathways.

Effects of dietary arginine on antioxidant status and immunity involved in AMPK-NO signaling pathway in juvenile blunt snout bream

The present study assessed the effects of dietary arginine on antioxidant status and immunity involved in AMPK-NO signaling pathway in juvenile blunt snout bream. Fish were fed six practical diets with graded arginine levels ranging from 0.87% to 2.70% for 8 weeks. The results showed that compared with the control group (0.87% dietary arginine level), significantly higher mRNA levels of adenosine monophosphate activated protein kinase (AMPK) and nitric oxide synthetase (NOS), activities of total nitric oxide synthetase (T-NOS) and nitric oxide synthetase (iNOS), and plasma nitric oxide (NO) contents were observed in fish fed with 1.62%-2.70% dietary arginine levels. Significantly higher levels of NOS and iNOS were observed in fish fed with 1.62%-2.70% dietary arginine levels in enzyme-linked immune sorbent assay. At dietary arginine levels of 1.22%-2.70%, the mRNA levels of iNOS were significantly improved. Dietary arginine also significantly influenced plasma interleukin 8 (IL-8) and tumour necrosis factor-α (TNF-α) contents. Furthermore, dietary arginine significantly affected the activity and mRNA level of glutathione peroxidase (GPx), the mRNA levels of pro-inflammatory factor including IL-8 and TNF-α and plasma malondialdehyde (MDA) content. However, total superoxide dismutase (T-SOD) activity, plasma complement component 3 (C3) content, plasma immunoglobulin M (IgM) content, plasma interleukin 1β (IL-1β) content and the mRNA levels of copperzinc superoxide dismutase (Cu/Zn-SOD), manganese superoxide dismutase (Mn-SOD) and IL-1β were not significantly affected by dietary arginine. After Aeromonas hydrophila challenge, the death rate was significantly lowered in fish fed with 1.62%-1.96% dietary arginine levels. Furthermore, the mRNA levels of AMPK, NOS and iNOS, plasma NO content and the activities of T-NOS and iNOS showed an upward trend with increasing dietary arginine levels. Significantly higher levels of NOS and iNOS were observed in fish fed with 1.62%-2.70% dietary arginine levels in enzyme-linked immune sorbent assay. At dietary arginine levels of 1.96%-2.31%, T-SOD activities were significantly improved. Significantly higher GPx activities were observed in fish fed with 1.22%-2.70% dietary arginine levels. At dietary arginine levels of 1.22%-2.31%, the plasma TNF-α and IL-8 contents were significantly decreased. Significantly lower plasma IL-1β contents were observed in fish fed 1.62%-1.96% dietary arginine levels. Dietary arginine significantly influenced the mRNA levels of antioxidant and pro-inflammatory genes including Cu/Zn-SOD, Mn-SOD, GPx, IL-8, TNF-α and IL-1β. Significantly higher plasma C3 contents and significantly lower plasma MDA contents were observed in fish fed with 1.62%-1.96% arginine levels. Furthermore, plasma IgM contents were significantly improved at dietary arginine levels of 1.62%-2.31%. However, high dietary arginine group (2.70%) significantly improved the mRNA levels of pro-inflammatory genes including IL-8, TNF-α and IL-1β and plasma MDA, IL-8, TNF-α and IL-1β contents as compared with optimal dietary arginine levels (1.62% and 1.96%). The present results indicate that optimal arginine level (1.62% and 1.96%) could improve antioxidant capacity, immune response and weaken tissues inflammatory involved in arginine-AMPK-NO signaling pathway, while high arginine level resulted in excessive NO production, leading to increase oxidative stress damage and inflammatory response in juvenile blunt snout bream.

Chitosan-Zn Chelate Downregulates TLR4-NF-κB Signal Pathway of Inflammatory Response and Cell Death-Associated Proteins Compared to Inorganic Zinc

The study was conducted to investigate the effect of chitosan-zinc chelate (CS-Zn) on TLR4-NF-κB signaling pathway and cell death-associated proteins in a weanling pig model. A total of 90 weaned piglets were allotted to three dietary treatments (the dietary treatments were as follows: (1) experimental diet with supplemental ZnSO₄ (150 mg Zn/kg diet), (2) experimental diet with supplemental CS-Zn (150 mg Zn/kg diet), and (3) experimental diet with a supplemental mixture of chitosan and ZnSO₄ (150 mg/kg Zn; the content of chitosan was equal to CS-Zn, which is according to molar basis)). The feeding trial lasted 30 days. The results showed that compared with ZnSO₄ or CS+ZnSO₄, CS-Zn decreased the expressions of the cell death-associated proteins Beclin-1, and Cleaved-Caspase3 and the ratio of LC3II/LC3I. The intestinal expressions of TLR4 and its downstream signals NF-κB, IKKβ, and IκBα were down-regulated simultaneously. Moreover, the contents of pro-inflammatory cytokines IL-2, TNF-α, and IFN-γ were decreased. The results indicated that as organic zinc source, CS-Zn was more effective than ZnSO₄ and the mixture of chitosan and ZnSO₄ for inhibiting inflammatory response and decreasing the expressions of proteins associated with cell death. The great anti-inflammatory effect of CS-Zn was modulated by inhibiting the TLR4-NF-κB signaling pathway, and the effect of CS-Zn on down-regulating the expression of cell death-associated proteins might also closely be associated with the TLR4-NF-κB signaling pathway.

Dietary Supplementation with Lactobacillus casei Alleviates Lipopolysaccharide-Induced Liver Injury in a Porcine Model

This study aims to determine whether Lactobacillus casei (L. casei) could relieve liver injury in piglets challenged with lipopolysaccharide (LPS). Piglets were randomly allocated into one of the three groups: control, LPS, and L. casei. The control and LPS groups were fed a corn- and soybean meal-based diet, whereas the L. casei group was fed the basal diet supplemented with 6 × 10⁶ cfu/g L. casei. On Day 31 of the trial, piglets in the LPS and L. casei groups received intraperitoneal administration of LPS (100 µg/kg body weight), while the control group received the same volume of saline. Blood and liver samples were collected for analysis. Results showed that L. casei supplementation decreased the feed/gain ratio (p = 0.027) and diarrhea incidence (p < 0.001), and attenuated LPS-induced liver histomorphological abnormalities. Compared with the control group, LPS challenge dramatically increased glutamyl transpeptidase activity (p = 0.001) in plasma as well as the concentrations of Interleukin 6 (IL-6) (p = 0.048), Tumor necrosis factor-alpha (TNF-α) (p = 0.041), and Malondialdehyde (MDA) (p = 0.001) in the liver, while decreasing the hepatic SOD activity. LPS also increased (p < 0.05) the mRNA levels for IL-6, IL-8, TNF-α, Toll-like receptors 4 (TLR4), Nuclear factor κB (NF-κB) and Heat shock protein 70 (HSP70) in the liver. The adverse effects of LPS challenge were ameliorated by L. casei supplementation. In conclusion, dietary L. casei alleviates LPS-induced liver injury via reducing pro-inflammatory cytokines and increasing anti-oxidative capacity.

Glutamate alleviates muscle protein loss by modulating TLR4, NODs, Akt/FOXO and mTOR signaling pathways in LPS-challenged piglets

The experiment was conducted to study the effect of the glutamate (Glu) on muscle protein loss through toll-like receptor 4 (TLR4), nucleotide-binding oligomerization domain proteins (NODs), Akt/Forkhead Box O (Akt/FOXO) and mammalian target of rapamycin (mTOR) signaling pathways in LPS-challenged piglets. Twenty-four weaned piglets were assigned into four treatments: (1) Control; (2) LPS+0% Glu; (3) LPS + 1.0% Glu; (4) LPS + 2.0% Glu. The experiment was lasted for 28 days. On d 28, the piglets in the LPS challenged groups were injected with LPS on 100 μg/kg body weight (BW), and the piglets in the control group were injected with the same volume of 0.9% NaCl solution. After 4 h LPS or saline injection, the piglets were slaughtered and the muscle samples were collected. Glu supplementation increased the protein/DNA ratio in gastrocnemius muscle, and the protein content in longissimus dorsi (LD) muscle after LPS challenge (P<0.05). In addition, Glu supplementation decreased TLR4, IL-1 receptor-associated kinase (IRAK) 1, receptor-interacting serine/threonine-protein kinase (RIPK) 2, and nuclear factor-κB (NF-κB) mRNA expression in gastrocnemius muscle (P<0.05), MyD88 mRNA expression in LD muscle, and FOXO1 mRNA expression in LD muscle (P<0.05). Moreover, Glu supplementation increased p-Akt/t-Akt ratio (P<0.05) in gastrocnemius muscle, and p-4EBP1/t-4EBP1 ratio in both gastrocnemius and LD muscles (P<0.05). Glu supplementation in the piglets' diets might be an effective strategy to alleviate LPS-induced muscle protein loss, which might be due to suppressing the mRNA expression of TLR4 and NODs signaling-related genes, and modulating Akt/FOXO and mTOR signaling pathways.

Feed supplementation with arginine and zinc on antioxidant status and inflammatory response in challenged weanling piglets

Although supplementing the diet with zinc oxide and arginine is known to improve growth in weanling piglets, the mechanism of action is not well understood. We measured the antioxidant status and inflammatory response in 48 weanling castrated male piglets fed diets supplemented with or without zinc oxide (2,500 mg Zn oxide per kg) and arginine (1%) starting at the age of 20 days. The animals were injected with lipopolysaccharide (100 μg/kg) on day 5. Half of them received another injection on day 12. Blood samples were taken just before and 6, 24 and 48 h after injection and the mucosa lining the ileum was recovered following euthanizing on days 7 and 14. Zinc supplementation increased reduced and total glutathione (GSH) (reduced and total) during days 5 to 7 and arginine decreased oxidized GSH measured on days 5 and 12 and the ratio of total antioxidant capacity to total oxidative status during days 12 to 14. Zinc decreased plasma malondialdehyde measured on days 5 and 12 and serum haptoglobin measured on day 12 and increased both metallothionein-1 expression and total antioxidant capacity measured in the ileal mucosa on day 14. Tumour necrosis factor α concentration decreased from days 5 to 12 (all effects were significant at P < 0.05). This study shows that the zinc supplement reduced lipid oxidation and lipopolysaccharide-induced inflammation during the post-weaning period, while the arginine supplementation had only a limited effect.

Dietary α-ketoglutarate supplementation improves hepatic and intestinal energy status and anti-oxidative capacity of Cherry Valley ducks

α-Ketoglutarate (AKG) is an extensively used dietary supplement in human and animal nutrition. The aim of the present study was to investigate effects of dietary AKG supplementation on the energy status and anti-oxidative capacity in liver and intestinal mucosa of Cherry Valley ducks. A total of 80 1-day-old ducks were randomly assigned into four groups, in which ducks were fed basal diets supplemented with 0% (control), 0.5%, 1.0% and 1.5% AKG, respectively. Graded doses of AKG supplementation linearly decreased the ratio of adenosine monophosphate (AMP) to adenosine triphosphate (ATP) in the liver, but increased ATP content and adenylate energy charge (AEC) in a quadratic and linear manner, respectively (P < 0.05). Increasing dietary AKG supplemental levels produced linear positive responses in ATP content and AEC, and negative responses in AMP concentration, the ratio of AMP to ATP and total adenine nucleotide in the ileal mucosa (P < 0.05). All levels of dietary AKG reduced the production of jejunal hydrogen peroxide and hepatic malondialdehyde (P < 0.05). Hepatic and ileal messenger RNA expression of AMP kinase α-1 and hypoxia-inducible factor-1α were linearly up-regulated as dietary AKG supplemental levels increased (P < 0.05). In conclusion, dietary AKG supplementation linearly or quadratically enhanced hepatic and intestinal energy storage and anti-oxidative capacity of Cherry Valley ducks.

Chronic DON exposure and acute LPS challenge: effects on porcine liver morphology and function

The aim of the present study was to examine the role of chronic deoxynivalenol (DON) exposition on the liver morphology and function in combination with pre- and post-hepatic lipopolysaccharide (LPS) stress in young pigs fed for 4 weeks with a DON-contaminated diet (4.59 mg/kg feed). At the end of the experiment, LPS (7.5 μg/kg BW) was administered for 1 h pre-hepatically (Vena portae hepatis) or post-hepatically (Vena jugularis). Liver morphology was macroscopically checked and showed haemorrhage in all LPS groups, significantly higher relative liver weights, accompanied by marked oedema in the gallbladder wall. Histological changes were judged by a modified histology activity index (HAI). Liver HAI score was significantly increased in all LPS groups compared to placebo, primarily due to neutrophil infiltration and haemorrhage. DON feed alone was without effect on the liver HAI. Liver function was characterized by (i) hepatic biochemical markers, (ii) mitochondrial respiration and (iii) Ca²⁺ accumulation capacity of isolated mitochondria. Clinical chemical parameters characterizing liver function were initially (<3 h) slightly influenced by LPS. After 3 h, bilirubin and alkaline phosphatase were increased significantly, in DON-fed, jugular-infused LPS group. Respiration and Ca²⁺ accumulation capacity of isolated liver mitochondria was not impaired by chronic DON exposure, acute LPS challenge or combined treatments. DON-contaminated feed did not change macroscopy and histology of the liver, but modified the function under LPS stress. The different function was not linked to modifications of liver mitochondria.

Effects of coenzyme Q10 on the antioxidant system in SD rats exposed to lipopolysaccharide-induced toxicity

The study was performed to see the effects of coenzyme Q₁₀ (CoQ₁₀) on blood biochemical components and hepatic antioxidant system in rats exposed to lipopolysaccharide (LPS)-induced toxicity. A total of 24 rats were allocated to four groups: control (CON), 100 mg/kg BW of LPS (LPS), 100 mg of CoQ₁₀/kg BW with LPS (LCQI) and 300 mg of CoQ₁₀/kg BW with LPS (LCQII). The LPS and LCQI groups showed a significant (P<0.05) increase in the relative spleen weight compared with the CON group without affecting body and liver weights. The blood alanine aminotransferase (ALT) level in the LPS group was significantly (P<0.05) greater than that in the CON group, while supplementation with 100 or 300 mg CoQ₁₀ to rats injected with LPS normalized the ALT level in the CON group. In antioxidant systems, the LPS group showed a significantly (P<0.05) higher mRNA and activity of superoxide dismutase (SOD) than the CON group. The supplementation with CoQ₁₀ to the LPS-treated group normalized the level of SOD, which was comparable to the level of the CON group. Both the mRNA expression and activity of glutathione peroxidase in the LCQI and LCQII groups were higher (P<0.05) than that of the LPS group. However, administration of LPS or CoQ₁₀ unaffected the level of catalase and total antioxidant power. The level of lipid peroxidation in the LCQII group was lower (P<0.05) than that in the LPS group. In conclusion, CoQ₁₀ exerted its favorable effect against liver damage by modulation of antioxidant enzymes in LPS treated rats.

Dietary Supplementation with α-Ketoglutarate Activates mTOR Signaling and Enhances Energy Status in Skeletal Muscle of Lipopolysaccharide-Challenged Piglets

BACKGROUND

Skeletal muscle undergoes rapid loss in response to inflammation. α-Ketoglutarate (AKG) has been reported to enhance muscle growth in piglets, but the underlying mechanisms are largely unknown.

OBJECTIVES

This study tested the hypothesis that dietary AKG supplementation activates mechanistic target of rapamycin (mTOR) signaling and improves skeletal muscle energy metabolism in lipopolysaccharide (LPS)-challenged piglets.

METHODS

Forty-eight male piglets (Duroc × Landrace × Yorkshire) were weaned at 21 d of age to a corn- and soybean meal-based diet. After a 3-d period of adaptation, piglets with a mean weight of 7.21 kg were randomly assigned to control, LPS (intraperitoneal administration of 80 μg LPS/kg body weight on days 10, 12, 14, and 16), or LPS plus 1% dietary AKG (LPS+AKG) groups. On day 16, blood samples were collected from 8 piglets/group 3 h after LPS administration. On day 17, piglets were killed to obtain gastrocnemius muscle from 8 piglets/group for biochemical analysis.

RESULTS

Compared with the control group, LPS administration increased (P < 0.05) plasma concentrations of globulin (by 14%) and tumor necrosis factor α (by 59%) and the intramuscular ratio of AMP to ATP (by 93%) and abundance of phosphorylated acetyl-coenzyme A carboxylase (ACC) β protein (by 64%). Compared with the control group, LPS administration reduced (P < 0.05) weight gain (by 15%); plasma concentrations of glutamine (by 20%), glucose (by 23%), insulin, insulin-like growth factor I, and epidermal growth factor; intramuscular concentrations of glutamine (by 27%), ATP (by 12%), ADP (by 22%), and total adenine nucleotides; and intramuscular ratios of phosphorylated mTOR to total mTOR (by 38%) and of phosphorylated 70-kDa ribosomal protein S6 kinase (p70S6K) to total p70S6K (by 39%). These adverse effects of LPS were ameliorated (P < 0.05) by AKG supplementation.

CONCLUSIONS

Dietary AKG supplementation activated mTOR signaling, inhibited ACC-β, and improved energy status in skeletal muscle of LPS-challenged piglets. These results provide a biochemical basis for the use of AKG to enhance piglet growth under inflammatory or practical postweaning conditions.

Glycine enhances muscle protein mass associated with maintaining Akt-mTOR-FOXO1 signaling and suppressing TLR4 and NOD2 signaling in piglets challenged with LPS

Pro-inflammatory cytokines play a critical role in the pathophysiology of muscle atrophy. We hypothesized that glycine exerted an anti-inflammatory effect and alleviated lipopolysaccharide (LPS)-induced muscle atrophy in piglets. Pigs were assigned to four treatments including the following: 1) nonchallenged control, 2) LPS-challenged control, 3) LPS+1.0% glycine, and 4) LPS+2.0% glycine. After receiving the control, 1.0 or 2.0% glycine-supplemented diets, piglets were treated with either saline or LPS. At 4 h after treatment with saline or LPS, blood and muscle samples were harvested. We found that 1.0 or 2.0% glycine increased protein/DNA ratio, protein content, and RNA/DNA ratio in gastrocnemius or longissimus dorsi (LD) muscles. Glycine also resulted in decreased mRNA expression of muscle atrophy F-box (MAFbx) and muscle RING finger 1 (MuRF1) in gastrocnemius muscle. In addition, glycine restored the phosphorylation of Akt, mammalian target of rapamycin (mTOR), eukaryotic initiation factor 4E binding protein 1 (4E-BP1), and Forkhead Box O 1 (FOXO1) in gastrocnemius or LD muscles. Furthermore, glycine resulted in decreased plasma tumor necrosis factor-α (TNF-α) concentration and muscle TNF-α mRNA abundance. Moreover, glycine resulted in decreased mRNA expresson of Toll-like receptor 4 (TLR4), nucleotide-binding oligomerization domain protein 2 (NOD2), and their respective downstream molecules in gastrocnemius or LD muscles. These results indicate glycine enhances muscle protein mass under an inflammatory condition. The beneficial roles of glycine on the muscle are closely associated with maintaining Akt-mTOR-FOXO1 signaling and suppressing the activation of TLR4 and/or NOD2 signaling pathways.

The Effects of Glucagon-like Peptide-2 on the Tight Junction and Barrier Function in IPEC-J2 Cells through Phosphatidylinositol 3-kinase-Protein Kinase B-Mammalian Target of Rapamycin Signaling Pathway

Glucagon-like peptide-2 (GLP-2) is important for intestinal barrier function and regulation of tight junction (TJ) proteins, but the intracellular mechanisms of action remain undefined. The purpose of this research was to determine the protective effect of GLP-2 mediated TJ and transepithelial electrical resistance (TER) in lipopolysaccharide (LPS) stressed IPEC-J2 cells and to test the hypothesis that GLP-2 regulate TJ and TER through the phosphatidylinositol 3-kinase (PI3K)-protein kinase B (Akt)-mammalian target of rapamycin (mTOR) signaling pathway in IPEC-J2 cells. Wortmannin and LY294002 are specific inhibitors of PI3K. The results showed that 100 μg/mL LPS stress decreased TER and TJ proteins occludin, claudin-1 and zonula occludens protein 1 (ZO-1) mRNA, proteins expressions (p<0.01) respectively. GLP-2 (100 nmol/L) promote TER and TJ proteins occludin, claudin-1, and zo-1 mRNA, proteins expressions in LPS stressed and normal IPEC-J2 cells (p<0.01) respectively. In normal cells, both wortmannin and LY294002, PI3K inhibitors, prevented the mRNA and protein expressions of Akt and mTOR increase induced by GLP-2 (p<0.01) following with the significant decreasing of occludin, claudin-1, ZO-1 mRNA and proteins expressions and TER (p<0.01). In conclusion, these results indicated that GLP-2 can promote TJ’s expression and TER in LPS stressed and normal IPEC-J2 cells and GLP-2 could regulate TJ and TER through the PI3K/Akt/mTOR pathway.

Differentially expressed genes of LPS febrile symptom in rabbits and that treated with Bai-Hu-tang, a classical anti-febrile Chinese herb formula

ETHNOPHARMACOLOGICAL RELEVANCE

Bai-Hu-Tang (BHT) has been traditionally used to clear heat and engender fluids.

AIM OF THE STUDY

To reveal the alteration of differentially expressed genes (DEGs) between lipopolysaccharide (LPS) febrile syndrome in rabbits and treatment with BHT which is a classical anti-febrile formula in traditional Chinese medicine.

MATERIALS AND METHODS

Febrile model was induced by LPS injection (i.v.) in rabbits, and BHT was gavaged to another group of febrile rabbits. After sacrifice of animals, total RNA of liver tissue was isolated, processed, and hybridized to rabbit cDNA microarrays obtained from Agilent Co. The data of DEGs were obtained by lazer scanning and analyzed with Cluster program 3.0. Then bioinformatic analysis of DEGs was conducted through gene ontology (GO) annotation and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways. In addition, expression levels of four relative genes were detected by quantitative real time ployenzyme chain reaction (qRT-PCR) to validate the accuracy of microarrays.

RESULT

The results demonstrated that genes expression pattern could be clustered into three groups significantly, and there were 606 up-regulated genes and 859 down-regulated genes in the model group, and 106 up-regulated genes and 429 down-regulated genes in BHT treated group. There were 286 DEGs existed as the common in two experimental groups. Enrichment analysis of GO annotations indicated that DEGs in model and BHT treated animals mainly referred catalytic activity and oxidoreductase activity for metabolic processes located in the membrane system at intracellular part, and binding activities increased significantly in treatment with BHT. Enrichment of KEGG analysis showed that the pathways of phagosome and protein processing in endoplasmic reticulum contained the most altered genes in the LPS group, but the percentage of phagosome pathway almost doubled in BHT group. Most DEGs involved in the LPS signal recognition system was up-regulated in LPS group, but partly decreased in BHT group. RT-PCR results of eight relative genes were consistent with the results of microarrays.

CONCLUSION

DEGs of LPS febrile syndrome mainly involved oxidoreductase and catalytic activity of the metabolic processes, and pathways of processing protein for pyrotoxin recognition; BHT mostly regulated the DEGs in the phagosome pathway to clear LPS in the liver, and partly interfered with gene expression in LPS recognition system. The study provided an important pioneering result on gene expression profiling research, and will facilitate the clinical care or further studies of the formula.

Asparagine attenuates hepatic injury caused by lipopolysaccharide in weaned piglets associated with modulation of Toll-like receptor 4 and nucleotide-binding oligomerisation domain protein signalling and their negative regulators

Pro-inflammatory cytokines play a key role in many models of hepatic damage. In addition, asparagine (Asn) plays an important role in immune function. We aimed to investigate whether Asn could attenuate lipopolysaccharide (LPS)-induced liver damage. Forty-eight castrated barrows were allotted to four groups including: (1) non-challenged control; (2) LPS-challenged control; (3) LPS + 0.5% Asn; and (4) LPS + 1.0% Asn. After 19 d feeding with control, 0.5 or 1.0% Asn diets, pigs were injected with LPS or saline. Blood and liver samples were obtained at 4 h (early stage) and 24 h (late stage) post-injection. Asn alleviated liver injury, indicated by reduced serum aspartate aminotransferase and alkaline phosphatase activities linearly and quadratically; it increased claudin-1 protein expression linearly and quadratically at 24 h, and less severe liver morphological impairment at 4 or 24 h. In addition, Asn decreased mRNA expression of TNF-α and heat shock protein 70 (HSP70) linearly and quadratically at 4 h; it increased TNF-α mRNA expression, and HSP70 protein expression linearly and quadratically at 24 h. Moreover, Asn increased inducible NO synthase activity linearly and quadratically. Finally, Asn down-regulated the mRNA expression of Toll-like receptor 4 (TLR4) signalling molecules (TLR4, IL-1 receptor-associated kinase 1 (IRAK1), TNF-α receptor-associated factor 6), nucleotide-binding oligomerisation domain protein (NOD) signalling molecules (NOD1, NOD2 and their adaptor molecule receptor-interacting serine/threonine-protein kinase 2 (RIPK2)), and NF-κB p65 linearly or quadratically at 4 h. Oppositely, Asn up-regulated mRNA expressions of TLR4 and NOD signalling molecules (TLR4, myeloid differentiation factor 88, IRAK1, NOD2 and RIPK2), and their negative regulators (radioprotective 105, single Ig IL-1R-related molecule, Erbb2 interacting protein and centaurin β1) linearly or quadratically at 24 h. These results indicate that, in early and late stages of LPS challenge, Asn improves liver integrity and exerts different regulatory effects on mRNA expression of TLR4 and NOD signalling molecules.

Dietary supplementation with glutamate precursor α-ketoglutarate attenuates lipopolysaccharide-induced liver injury in young pigs

There is growing interest in glutamate as a functional amino acid in nutrition and health. This study was conducted to determine whether glutamate precursor α-ketoglutarate (AKG) could alleviate lipopolysaccharide (LPS)-induced liver injury in young pigs. Twenty-four piglets were randomly assigned to the control, LPS, or LPS + AKG group. Piglets in the control and LPS groups were fed a basal diet, whereas piglets in the NAC group were fed the basal diet supplemented with 1 % AKG. On days 10, 12, 14, and 16 of the trial, piglets in the LPS and LPS + AKG groups received intraperitoneal administration of LPS (80 μg/kg BW), whereas piglets in the control group received the same volume of saline. On day 16 of the trial, blood samples were collected 3 h after LPS or saline injection. Twenty-four hours post-administration of LPS or saline (on day 17 of the trial), piglets were killed to obtain liver for analysis. Dietary AKG supplementation alleviated LPS-induced histomorphological abnormalities and mitigated LPS-induced increases in aspartate aminotransferase (AST) activity and AST/ALT ratio (P < 0.05). Compared with the LPS group, dietary supplementation with AKG decreased plasma glutamate concentration, while increasing hepatic concentrations of glutamate, glutamine, leucine, asparagine, lysine, alanine, serine, threonine, valine, and phenylalanine (P < 0.05). LPS challenge dramatically increased concentrations of malondialdehyde and decreased glutathione peroxidase activity in the liver. Additionally, LPS challenge enhanced concentrations of AMP and total protein, as well as RNA/DNA and total protein/DNA ratios, while decreasing hepatic ADP concentrations. These adverse effects of LPS challenge were ameliorated by AKG supplementation. Collectively, dietary AKG supplementation provides a new means to ameliorate LPS-induced liver injury by increasing anti-oxidative capacity and improving energy metabolism in young pigs.

The anti-inflammatory effects of acetaminophen and N-acetylcysteine through suppression of the NLRP3 inflammasome pathway in LPS-challenged piglet mononuclear phagocytes

Acetaminophen (AAP) and N-acetylcysteine (NAC) have been found to have anti-inflammatory effects via the TLR-NF-κB pathway in LPS-challenged piglets. However, the action mechanisms employed by AAP and NAC have yet to be completely understood. This study investigated the anti-inflammatory effects and mechanisms of AAP and NAC on LPS-induced inflammatory responses via the NLRP3 inflammasome pathway in piglet mononuclear phagocytes. The results show that mRNA expression levels of IL-1β, IL-18 and NLRP3, as well as the protein level of cleaved caspase-1, are significantly increased after LPS challenge in vitro. LPS stimulation did not change ASC and caspase-1 mRNA levels, which were components of NLRP3 inflammasome complex. AAP (0.5-1.0 mM) and NAC (0.5-1.0 mM) used individually or in combination could down-regulate protein expression of cleaved caspase-1 and mRNA expression of IL-1β, IL-18 and NLRP3. NAC could significantly enhance the above inhibition actions of AAP. The combined use of AAP plus NAC had better inhibition action on the NLRP3 inflammasome pathway. These results indicate that the anti-inflammatory effects of AAP and NAC occur via the regulation on mRNA expression of NLRP3 and activation of caspase-1. The anti-inflammatory activity of AAP and NAC could be related to the suppression of NLRP3 inflammasome pathway under LPS stimulation.

The effect of aspartate on the energy metabolism in the liver of weanling pigs challenged with lipopolysaccharide

PURPOSE

This study was conducted to investigate whether aspartate (Asp) could improve liver energy status in the lipopolysaccharide (LPS)-challenged pigs.

METHODS

Twenty-four weaned pigs were assigned to four treatments: (1) nonchallenged control (control diet and saline-treated); (2) LPS-challenged control (the same control diet and LPS-challenged); (3) LPS + 0.5% Asp treatment (0.5% Asp diet and LPS-challenged); and (4) LPS + 1.0% Asp treatment (a 1.0% Asp diet and LPS-challenged). On d 19, the pigs were injected intraperitoneally with Escherichia coli LPS at 100 μg/kg body weight, and the same volume of 0.9% NaCl solution, respectively. All pigs were slaughtered at 24 h after LPS or saline injection, and the liver was collected for further analysis.

RESULTS

Dietary supplementation with Asp improved liver energy status evidenced by the increased ATP concentration and adenylate energy charges, and the decreased AMP concentration and AMP/ATP ratio (p < 0.05). Asp supplementation increased the mRNA expression of key enzymes in hepatic glycolysis and tricarboxylic acid (TCA) cycle, including pyruvate kinase and citrate synthase (p < 0.05), and had a tendency to increase hepatic pyruvate dehydrogenase and isocitrate dehydrogenase β mRNA expression (p < 0.10). In addition, Asp increased the mRNA expressions of hepatic AMP-activated protein kinase (AMPK) α1, AMPKα2, silent information regulator (Sirt1), and proliferator-activated receptor-γ coactivator 1α (PGC1α) (p < 0.05). Moreover, Asp increased AMPKα phosphorylation (p < 0.05).

CONCLUSIONS

These results indicated that dietary supplementation of Asp could improve energy status in LPS-injured liver, which might result from motivating the metabolism pathway of TCA cycle and glycolysis and stimulating the AMPK signaling pathway.

Zinc oxide influences mitogen-activated protein kinase and TGF-β1 signaling pathways, and enhances intestinal barrier integrity in weaned pigs

Weaning is the most significant event in the life of pigs and is always related with intestinal disruption. Although it is well known that zinc oxide (ZnO) exerts beneficial effects on the intestinal barrier, the mechanisms underlying these effects have not yet been fully elucidated. We examined whether ZnO protects the intestinal barrier via mitogen-activated protein kinases and TGF-β1 signaling pathways. Twelve barrows weaned at 21 d of age were randomly assigned to two treatments (0 verus 2200 mg Zn/kg from ZnO) for 1 wk. The results showed that supplementation with ZnO increased daily gain and feed intake, and decreased postweaning scour scores. ZnO improved intestinal morphology, as indicated by increased villus height and villus height:crypt depth ratio, and intestinal barrier function, indicated by increased transepithelial electrical resistance and decreased mucosal-to-serosal permeability to 4-ku FITC dextran. ZnO decreased the ratios of the phosphorylated to total JNK and p38 (p-JNK/JNK and p-p38/p38), while it increased the ratio of ERK (p-ERK/ERK). Supplementation with ZnO increased intestinal TGF-β1 expression. The results indicate that supplementation with ZnO activates ERK ½, and inhibits JNK and p38 signaling pathways, and increases intestinal TGF-β1 expression in weaned pigs.

Antioxidant status and inflammatory response in weanling piglets fed diets supplemented with arginine and zinc

Bergeron, N., Robert, C. and Guay, F. 2014. Antioxidant status and inflammatory response in weanling piglets fed diets supplemented with arginine and zinc. Can. J. Anim. Sci. 94: 87–97. Dietary supplementation with zinc oxide (Zn oxide) and arginine (Arg) is known to improve growth in weanling piglets. The mechanism of action is not yet well understood, although antioxidant effects and inflammatory responses may be involved. This experiment was conducted to evaluate the effects of Zn and Arg supplementation on the antioxidant status and inflammatory response of piglets. Thirty-two 20-d-old weanling piglets were placed for 12 d on diets supplemented or not with Zn (2500 mg Zn oxide kg−1) and Arg (1%), designated ZN0ARG0, ZN2500ARG0, ZN0ARG1 and ZN2500ARG1. On day 12, blood samples were taken before and 3 h after intra-peritoneal injection of lipopolysaccharide (LPS; 10 µg kg−1). The piglets were euthanized just after the second blood sample, and samples of mucosae were taken from the jejunum and ileum for determination of mRNA expression and morphological observation. Zn supplementation decreased plasma malondialdehyde measured before LPS injection (P<0.05). Arg supplementation increased the ferric-reducing ability of plasma (indicator of antioxidant status) measured after LPS injection (P<0.05). Piglets fed Zn-supplemented diets had lower total plasma superoxide-dismutase (SOD) activity (P<0.05) but higher plasma tumour necrosis factor-α (P<0.05) after LPS injection. Zinc-supplemented diets increased metallothionein-1 expression and total antioxidant capacity in the ileum and jejunum (P<0.05) and decreased interleukin-10 expression (P<0.05) in the ileum. In the jejunum, the combination of Zn and Arg supplementation increased villus height (Arg×Zn, P<0.05). These results indicate that Zn may reduce systemic oxidation and improve the antioxidant status in the jejunal and ileal mucosae. However, Zn and Arg supplementation did not appear to act synergistically to enhance antioxidant status or reduce inflammation in weanling piglets.

Zinc oxide influences intestinal integrity, the expressions of genes associated with inflammation and TLR4-myeloid differentiation factor 88 signaling pathways in weanling pigs

This study explored whether zinc oxide (ZnO) supplementation could alleviate weanling-induced intestinal injury through TLR and NOD-like receptor signaling pathways. Twelve early-weanling piglets were allotted to two dietary treatments (control vs 2200 mg Zn/kg from ZnO) for 1 wk. The results showed that supplemental ZnO improved daily gain and feed intake, decreased post weaning scour scores, increased villus height and villus height:crypt depth ratio at the jejunal mucosa, and decreased diamine oxidase activity and endotoxin concentration in plasma. The intestinal mRNA levels of TLR4 and its downstream signals, including MyD88, IL-1 receptor-associated kinase 1 and TNF-α receptor-associated factor 6, were decreased, and the expressions of intestinal pro-inflammatory cytokines and chemokines were decreased simultaneously in the ZnO-supplemented piglets. Although NF-κB p65 mRNA abundance was not affected by ZnO supplementation, NF-κB p65 protein expression was down-regulated by ZnO. However, ZnO supplementation had no effect on intestinal expressions of NOD1 and NOD2, and their adaptor molecule receptor-interacting serine/threonine-protein kinase 2, as well as protein expressions of caspase-3 and heat shock protein 70. The results indicated that the protective effects of ZnO on intestinal integrity were closely related to decreasing the expressions of genes associated with inflammation through inhibiting the TLR4-MyD88 signaling pathways.

Fish oil increases muscle protein mass and modulates Akt/FOXO, TLR4, and NOD signaling in weanling piglets after lipopolysaccharide challenge

Proinflammatory cytokines play a key role in the pathophysiology of muscle atrophy. In addition, n3 polyunsaturated fatty acids (PUFAs) exert an inhibitory effect on proinflammatory cytokines affecting many inflammatory diseases. We hypothesized that dietary supplementation of fish oil could attenuate lipopolysaccharide (LPS)-induced muscle atrophy. Weanling pigs 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). After 21 d of treatment with either fish oil or corn oil, pigs received an i.p. injection of either saline or LPS. At 4 h postinjection, blood and muscle samples were obtained. Fish oil led to enrichment of eicosapentaenoic acid, docosahexaenoic acid, and total n3 PUFAs in muscles. Fish oil increased muscle protein mass, indicated by a higher protein:DNA ratio in gastrocnemius and longissimus dorsi (LD) muscles. In addition, fish oil increased Akt1 mRNA abundance and decreased Forkhead Box O (FOXO) 1 and FOXO4 mRNA abundance. Fish oil also increased phosphorylation of Akt and FOXO1 in gastrocnemius and LD muscles. Fish oil decreased the mRNA abundance of muscle atrophy F-box (MAFbx) and muscle RING finger 1 in gastrocnemius and LD muscles. Moreover, fish oil reduced the plasma tumor necrosis factor (TNF) α, muscle TNFα, and prostaglandin E2 concentrations, and muscle TNFα and cyclooxygenase 2 (COX2) mRNA abundance. Finally, fish oil downregulated the mRNA abundance of muscle toll-like receptor (TLR4) and its downstream signaling molecules [myeloid differentiation factor 88 (MyD88), TNFα receptor-associated factor 6 (TRAF6), and NF-κB p65], and nucleotide-binding oligomerization domain protein (NOD1), NOD2, and their adaptor molecule [receptor-interacting serine/threonine-protein kinase 2 (RIPK2)]. These results indicate fish oil may suppress muscle proinflammatory cytokine production via regulation of TLR and NOD signaling pathways and therefore improve muscle protein mass, possibly through maintenance of Akt/FOXO signaling.

Effects of dietary arginine and glutamine on alleviating the impairment induced by deoxynivalenol stress and immune relevant cytokines in growing pigs

Deoxynivalenol (DON) is a mycotoxin that reduces feed intake and animal performance, especially in swine. Arginine and glutamine play important roles in swine nutrition. The objective of this study was to determine the effects of dietary supplementation with arginine and glutamine on both the impairment induced by DON stress and immune relevant cytokines in growing pigs. A total of forty 60-d-old healthy growing pigs with a mean body weight of 16.28±1.54 kg were randomly divided into 5 groups, and assigned to 3 amino acid treatments fed 1.0% arginine (Arg), 1.0% glutamine (Gln) and 0.5% Arg+0.5% Gln, respectively, plus a toxin control and a non-toxin control. Pigs in the 3 amino acid treatments were fed the corresponding amino acids, and those in non-toxin control and toxin control were fed commercial diet with 1.64% Alanine as isonitrogenous control for 7 days. The toxin control and amino acid treatments were then challenged by feeding DON-contaminated diet with a final DON concentration of 6 mg/kg of diet for 21 days. No significant differences were observed between toxin control and the amino acid groups with regard to the average daily gain (ADG), although the values for average daily feed intake (ADFI) in the amino acid groups were significantly higher than that in toxin control (P<0.01). The relative liver weight in toxin control was significantly greater than those in non-toxin control, arginine and Arg+Glu groups (P<0.01), but there were no significant differences in other organs. With regard to serum biochemistry, the values of BUN, ALP, ALT and AST in the amino acid groups were lower than those in toxin control. IGF1, GH and SOD in the amino acid groups were significantly higher than those in toxin control (P<0.01). The IL-2 and TNFα values in the amino acid groups were similar to those in non-toxin control, and significantly lower than those in toxin control (P<0.01). These results showed the effects of dietary supplementation with arginine and glutamine on alleviating the impairment induced by DON stress and immune relevant cytokines in growing pigs.