Glycine Relieves Intestinal Injury by Maintaining mTOR Signaling and Suppressing AMPK, TLR4, and NOD Signaling in Weaned Piglets after Lipopolysaccharide Challenge

Total flavone of Abelmoschus manihot regulates autophagy through the AMPK/mTOR signaling pathway to treat intestinal fibrosis in Crohn's disease

BACKGROUND AND AIM

Drug therapy is the treatment of choice for Crohn's disease because it effectively controls or prevents intestinal inflammation. The purpose was to research the molecular mechanism of the total flavones of Abelmoschus manihot (TFA) on intestinal fibrosis in Crohn's disease.

METHODS

A 2,4,6-Trinitrobenzenesulfonic acid (TNBS)-induced colitis model and IGF-1-treated intestinal fibroblasts were established. Then, TFA, 3-MA, and compound C were used treatments. Hematoxylin and eosin, Masson, and Picrosirius red staining were performed to observe the colon tissue. Immunohistochemical staining was used to detect α-SMA expression. Flow cytometry, CCK8, wound healing, and Transwell assays were conducted to determine apoptosis, proliferation, invasion, and migration. Col1a1 and Col3a1 levels were detected using quantitative polymerase chain reaction. Proteins related to autophagy and apoptosis were detected using western blotting.

RESULTS

TFA treated intestinal fibrosis in chronic Crohn's disease. Colon length was the shortest in the ethanol + TNBS group, and TFA treatment significantly improved the situation. Intestinal fibrosis and the percentage of collagen area decreased after TFA treatment. TFA reduced fibrosis by enhancing autophagy stimulation, whereas an autophagy inhibitor reversed the TFA effect. TFA also inhibited migration, proliferation, and collagen synthesis in intestinal fibroblasts. Moreover, it enhanced autophagy and apoptosis of intestinal fibroblasts. TFA upregulated p-AMPK expression and decreases p-mTOR levels. Compound C partially rescued the effect of TFA, indicating that TFA affected intestinal fibroblasts via the AMPK/mTOR pathway in vitro and in vivo. TFA also downregulated Col1a1 and Col3a1 expression.

CONCLUSION

TFA regulates autophagy through AMPK/mTOR signaling pathway to treat intestinal fibrosis, which may provide a new therapy for Crohn's disease treatment.

Amino acids in piglet diarrhea: Effects, mechanisms and insights

Piglet diarrhea is among one of the most serious health problems faced by the pig industry, resulting in significant economic losses. Diarrheal disease in piglets has a multifactorial etiology that is affected by physiology, environment, and management strategy. Diarrhea is the most apparent symptom of intestinal dysfunction. As a key class of essential nutrients in the piglet diet, amino acids confer a variety of beneficial effects on piglets in addition to being used as a substrate for protein synthesis, including maintaining appropriate intestinal integrity, permeability and epithelial renewal, and alleviating morphological damage and inflammatory and oxidative stress. Thus, provision of appropriate levels of amino acids could alleviate piglet diarrhea. Most amino acid effects are mediated by metabolites, gut microbes, and related signaling pathways. In this review, we summarize the current understanding of dietary amino acid effects on gut health and diarrhea incidence in piglets, and reveal the mechanisms involved. We also provide ideas for using amino acid blends and emphasize the importance of amino acid balance in the diet to prevent diarrhea in piglets.

Intestinal metabolomics in premature infants with late-onset sepsis

We aimed to investigate the characteristics of intestinal metabolomics and non-invasive biomarkers for early diagnosis of late-onset sepsis (LOS) by analyzing gut metabolites in preterm infants with LOS. We collected stool samples from septic and healthy preterm infants for analysis by liquid chromatography-mass spectrometry. 123 different metabolites were identified and 13 pathways were mainly involved. Glycine, serine, and threonine metabolism; glyoxylate and dicarboxylic acid metabolism; glutathione metabolism; primary bile acid biosynthesis; steroid synthesis; pentose and glucuronic acid interconversion may be involved in the pathogenesis of LOS in preterm infants. The significant changes of N-Methyldopamine, cellulose, glycine, gamma-Glutamyltryptophan, N-Ribosylnicotinamide and 1alpha, 25-dihydroxycholecalciferol showed specific diagnostic values and as non-invasive biomarkers for LOS.

Effects of Glycine Supplementation in Drinking Water on the Growth Performance, Intestinal Development, and Genes Expression in the Jejunum of Chicks

Glycine, the most basic amino acid found in nature, is considered an essential amino acid for chicks. However, the precise understanding of high concentrations of glycine's significance in promoting the growth performance of chicks, as well as its impact on intestinal development, re-mains limited. Consequently, the objective of this study was to investigate the effects of glycine supplementation in drinking water on growth performance, intestine morphology, and development in newly hatched chicks. In this study, 200 newly born chicks were selected and pro-vided with a supplementation of 0.5%, 1%, and 2% glycine in their drinking water during their first week of life. The results revealed that glycine supplementation in drinking water could significantly increase the average daily gain of chicks from days 7 to 14. Furthermore, a significant difference was observed between the group supplemented with 1% glycine and the control group. Concurrently, this glycine supplementation increased the villus height and the ratio of the villus height to crypt depth in jejunum on both day 7 and day 14. Glycine supplementation in drinking water significantly affected the mRNA expression level of the ZO-1, GCLM, and rBAT genes in jejunum, which may have certain effects on the mucosal immune defense, cellular antioxidant stress capacity, and amino acid absorption. Overall, the findings of this study indicate that glycine supplementation in drinking water can enhance the growth performance of chicks and promote their intestine development.

Rice bran oil supplementation protects swine weanlings against diarrhea and lipopolysaccharide challenge

Early weaned piglets suffer from oxidative stress and enteral infection, which usually results in gut microbial dysbiosis, serve diarrhea, and even death. Rice bran oil (RBO), a polyphenol-enriched by-product of rice processing, has been shown to have antioxidant and anti-inflammatory properties both in vivo and in vitro. Here, we ascertained the proper RBO supplementation level, and subsequently determined its effects on lipopolysaccharide (LPS)-induced intestinal dysfunction in weaned piglets. A total of 168 piglets were randomly allocated into four groups of seven replicates (42 piglets each group, (21±1) d of age, body weight (7.60±0.04) kg, and half males and half females) and were given basal diet (Ctrl) or basal diet supplemented with 0.01% (mass fraction) RBO (RBO1), 0.02% RBO (RBO2), or 0.03% RBO (RBO3) for 21 d. Then, seven piglets from the Ctrl and the RBO were treated with LPS (100 μg/kg body weight (BW)) as LPS group and RBO+LPS group, respectively. Meanwhile, seven piglets from the Ctrl were treated with the saline vehicle (Ctrl group). Four hours later, all treated piglets were sacrificed for taking samples of plasma, jejunum tissues, and feces. The results showed that 0.02% was the optimal dose of dietary RBO supplementation based on diarrhea, average daily gain, and average daily feed intake indices in early weaning piglets. Furthermore, RBO protected piglets against LPS-induced jejunal epithelium damage, which was indicated by the increases in villus height, villus height/crypt depth ratio, and Claudin-1 levels, as well as a decreased level of jejunal epithelium apoptosis. RBO also improved the antioxidant ability of LPS-challenged piglets, which was indicated by the elevated concentrations of catalase and superoxide dismutase, and increased total antioxidant capacity, as well as the decreased concentrations of diamine oxidase and malondialdehyde in plasma. Meanwhile, RBO improved the immune function of LPS-challenged weaned piglets, which was indicated by elevated immunoglobulin A (IgA), IgM, β‍‍-defensin-1, and lysozyme levels in the plasma. In addition, RBO supplementation improved the LPS challenge-induced dysbiosis of gut microbiota. Particularly, the indices of antioxidant capacity, intestinal damage, and immunity were significantly associated with the RBO-regulated gut microbiota. These findings suggested that 0.02% RBO is a suitable dose to protect against LPS-induced intestinal damage, oxidative stress, and jejunal microbiota dysbiosis in early weaned piglets.

Dietary glycine supplementation prevents heat stress-induced impairment of antioxidant status and intestinal barrier function in broilers

This study tested the hypothesis that glycine improves intestinal barrier function through regulating oxidative stress in broilers exposed to heat stress. A total of 300 twenty-one-day-old female Arbor Acres broilers (600 ± 2.5g) was randomly allocated to 5 treatments (6 replicate of 10 birds each). The 5 treatments were as follows: the control group (CON) was kept under thermoneutral condition (24 ± 1°C) and was fed a basal diet. Broilers fed a basal diet and reared under high ambient temperature (HT) were considered as the HT group (34 ± 1°C for 8 h/d). Broilers fed a basal diet supplemented with 0.5%, 1.0%, and 2.0% glycine and exposed to HT were regarded as the HT + glycine treatments. The results exhibited that heat stress reduced growth performance, serum total antioxidant capacity (T-AOC), and glutathione (GSH) concentration (P < 0.05); increased activity of serum catalase (CAT) and the contents of hydrogen peroxide (H₂O₂) and malondialdehyde (MDA) (P < 0.05). HT exposure led to downregulating the mRNA expression of NAD(P)H quinone dehydrogenase 1 (NQO1), Occludin, and zonula occludens-1 (ZO-1) (P < 0.05); enhanced the mRNA levels of Kelch-like ECH-associated protein 1 (Keap1), CAT, glutathione synthetase (GSS), and glutamate-cysteine ligase modifier subunit (GCLM) (P < 0.05); impaired the intestinal morphology (P < 0.05); and altered the diversity and community of gut microbiota (P < 0.05). The final body weight (FBW), ADFI, ADG, and gain-to-feed ratio (G: F) increased linearly or quadratically, and the antioxidant capacity was improved (P < 0.05) with glycine supplementation. Glycine treatment increased the villus height (VH), and villus height to crypt depth ratio (V/C) of the duodenum linearly or quadratically, and linearly increased the VH of jejunum and ileum. The mRNA expression of Occludin, and ZO-1 were increased linearly in the ileum mucosa of broilers subjected to HT. Collectively, these results demonstrated that glycine supplementation alleviates heat stress-induced dysfunction of antioxidant status and intestinal barrier in broilers.

Development of Intestinal Injury and Restoration of Weaned Piglets under Chronic Immune Stress

This study aimed to investigate the effects of lipopolysaccharide (LPS)-induced chronic immune stress on intestinal morphology and function, immune system, oxidative status, and mitochondrial function in piglets. Fifty healthy Duroc × Landrace × Yorkshire piglets (21 ± 2 days old, barrow, 6.98 ± 0.14 kg body weight) were selected and randomly allotted to five groups, which were slaughtered at 0 (0 group), 1, 5, 9, and 15 d of LPS injection. The results showed that compared with the piglets without LPS injection, LPS injection significantly impaired the intestinal morphology and permeability at 1, 5, and 9 d, as manifested by the increased serum lactic acid and decreased ratio of villus height to crypt depth (p < 0.05). Moreover, intestinal inflammation and oxidative and mitochondrial injury were caused at 1 d, as manifested by upregulated IL-6 mRNA expression, increased malondialdehyde content, and impaired mitochondrial morphology (p < 0.05). However, these parameters were restored to levels identical to 0 group at 9~15 d, accompanied by significantly increased antioxidant capacity, enhanced protein expression of CD3+ and CD68+, and upregulated mRNA abundance of genes related to mitochondrial biogenesis and functions (p < 0.05). Collectively, these results suggest that the intestinal injury of piglets caused by chronic immune stress could be self-repaired.

Glycine Alleviated Intestinal Injury by Inhibiting Ferroptosis in Piglets Challenged with Diquat

The purpose of this research was to examine the impact of glycine on intestinal injury caused by oxidative stress in piglets. A 2 × 2 factorial experiment with diets (basic diet vs. 1% glycine diet) and oxidative stress (saline vs. diquat) was conducted on 32 weanling piglets. On day 21, all piglets received an injection of either saline or diquat. After 7 days, all pigs were slaughtered and intestinal samples were collected. Dietary glycine supplementation improved intestinal mucosal morphology, increased the activities of disaccharidases and enhanced intestinal mucosal antioxidant capacity, while regulating the expression of ferroptosis mediators in the piglets under oxidative stress. These findings suggested that dietary glycine supplementation improved the morphology and function of the intestinal mucosa, which was involved in regulating antioxidant capacity and ferroptosis.

Pyrroloquinoline quinone regulates glycolipid metabolism in the jejunum via inhibiting AMPK phosphorylation of weaned pigs

Maintenance of intestinal metabolic function is important for optimal growth performance in post-weaning pigs. This study aimed to evaluate the effect of pyrroloquinoline quinone (PQQ) on maintaining intestinal glycolipid metabolism in weaned pigs. Seventy-two Duroc × Landrace × Yorkshire crossbred pigs were divided into two groups: pigs fed a basal diet (CTRL group) and pigs fed a basal diet supplemented with 3.0 mg kg^-1 PQQ (PQQ group). On d 14, serum was harvested from six pigs per group and the pigs were slaughtered to sample jejunal tissue. Compared with the CTRL group, pigs in the PQQ group had increased average daily gain (P < 0.05), decreased feed : gain (P < 0.05) and tended to have a reduced diarrhea ratio (P = 0.057). Jejunal villus height and villus height/crypt depth ratio were increased, and the crypt depth was decreased in the PQQ group (P < 0.01). The proteomics results showed that PQQ supplementation acted on three metabolic pathways, type I diabetes mellitus, the pancreatic secretion pathway and immune-related signalling. Compared with the CTRL group, PQQ supplementation increased (P < 0.05) serum insulin and jejunal mucosal pyruvate, triglyceride, total cholesterol and low-density lipoprotein cholesterol in the pigs. Jejunal mucosal lactic dehydrogenase and high-density lipoprotein cholesterol levels in the pigs were decreased by PQQ supplementation (P < 0.05). In addition, PQQ supplementation reduced glucose transporter 5 and phosphorylated-AMP-activated protein kinase expression in the jejunal mucosa of the pigs (P < 0.05). In conclusion, dietary supplementation with PQQ improved the growth performance and jejunal morphology and regulated glycolipid metabolism via inhibiting AMPK phosphorylation in weaned pigs.

Slc6a13 Deficiency Attenuates Pasteurella multocida Infection-Induced Inflammation via Glycine-Inflammasome Signaling

We have previously demonstrated that Slc6a13-deficient (Slc6a13-/-; KO) mice are resistant to P. multocida infection, which might be in connection with macrophage-mediated inflammation; however, the specific metabolic mechanism is still enigmatic. Here we reproduce the less sensitive to P. multocida infection in overall survival assays as well as reduced bacterial loads, tissue lesions, and inflammation of lungs in KO mice. The transcriptome sequencing analysis of wild-type (WT) and KO mice shows a large number of differentially expressed genes that are enriched in amino acid metabolism by functional analysis. Of note, glycine levels are substantially increased in the lungs of KO mice with or without P. multocida infection in comparison to the WT controls. Interestingly, exogenous glycine supplementation alleviates P. multocida infection-induced inflammation. Mechanistically, glycine reduces the production of inflammatory cytokines in macrophages by blocking the activation of inflammasome (NALP1, NLRP3, NLRC4, AIM2, and Caspase-1). Together, Slc6a13 deficiency attenuates P. multocida infection through lessening the excessive inflammatory responses of macrophages involving glycine-inflammasome signaling.

Glycine represses endoplasmic reticulum stress-related apoptosis and improves intestinal barrier by activating mammalian target of rapamycin complex 1 signaling

Endoplasmic reticulum (ER) stress has been associated with the dysfunction of intestinal barrier in humans and animals. We have previously shown that oral administration of glycine to suckling-piglets improves ER stress-related intestinal mucosal barrier impairment and jejunal epithelial apoptosis. However, the underlying mechanism remains unknown. In this study, the protective effect and the mechanism of glycine on apoptosis and dysfunction in intestinal barrier induced by brefeldin A (BFA), an ER stress inducer, was explored in porcine intestinal epithelial cells (IPEC-1). The results showed that BFA treatment led to enhanced apoptosis and upregulation of proteins involved in ER stress signaling, including inositol-requiring enzyme 1α (IRE1α), activating transcription factor 6α (ATF6α), c-Jun N-terminal kinase (JNK), and C/EBP-homologous protein (CHOP). In addition, BFA induced a dysfunction in intestinal epithelial barrier, as evidenced by the increased paracellular permeability, decreased transepithelial electrical resistance (TEER), and reduced abundance of tight junction proteins (occludin, claudin-1, zonula occludens [ZO]-1, and ZO-2). These alterations triggered by BFA were significantly abolished by glycine treatment (P < 0.05), indicating a protective effect of glycine on barrier function impaired by ER stress. Importantly, we found that the regulatory effect of glycine on intestinal permeability, proteins implicated in ER stress and apoptosis, as well as the morphological alterations of the ER were reversed by rapamycin. In summary, our results indicated that glycine alleviates ER stress-induced apoptosis and intestinal barrier dysfunction in IPEC-1 cells in a mammalian target of rapamycin complex 1 (mTORC1)-dependent manner. The data provides in vitro evidence and a mechanism for the protective effect of glycine against the disruption of intestinal barrier integrity induced by ER stress.

Protective effects of glycine against lipopolysaccharide-induced intestinal apoptosis and inflammation

Intestinal dysfunction is commonly observed in humans and animals. Glycine (Gly) is a functional amino acid with anti-inflammatory and anti-apoptotic properties. The objective of this study was to test the protective effects of Gly against lipopolysaccharide (LPS)-induced intestinal injury. 28 C57BL/6 mice with a body weight (BW) of 18 ± 2 g were randomly assigned into four groups: CON (control), GLY (orally administered Gly, 5 g/kg BW/day for 6 days), LPS (5 mg/kg BW on day 7, i. p.), and GLY + LPS (Gly pretreatment and LPS administration). Histological alterations, inflammatory responses, epithelial cell apoptosis, and changes of the intestinal microbiota were analyzed. Results showed that, compared with the CON group, mice in the LPS treatment group showed decreased villus height, increased crypt depth, and decreased ratio of villus height to crypt depth, which were significantly attenuated by Gly. Neither LPS nor Gly treatment altered morphology of the distal colon tissues. LPS increased the apoptosis of jejunum and colon epithelial cells and protein abundance of cleaved caspase3 in the jejunum, which were markedly abrogated by Gly. LPS also elevated the mRNA levels of Toll-like receptor 4 (TLR4), myeloid differentiation factor 88 (MYD88), pro-inflammatory cytokines, and chemokines in the jejunum and colon. These alterations were significantly suppressed by Gly. In addition, Gly supplementation attenuated infiltration of CD4+, CD8+ T-lymphocytes, CD11b+ and F4/80+ macrophages in the colon. Furthermore, Gly increased the relative abundance of Mucispirillum, Lachnospiraceae-NK4A136-group, Anaerotruncus, Faecalibaculum, Ruminococcaceae-UCG-014, and decreased the abundance of Bacteroides at genus level. Supplementation with Gly might be a nutritional strategy to ameliorate LPS-induced intestinal injury in mice.

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 pectin caused great changes in bile acid profiles of Pelteobagrus fulvidraco

To reveal the impact of dietary fiber (DF) on the bile acid (BA) profiles of fish, yellow catfish (Pelteobagrus fulvidraco) were fed a diet containing 300 g kg^-1 dextrin (CON diet, control) or pectin (a type of soluble DF, PEC diet) for 7 days, and then the BA profiles were analyzed by UHPLC-MS/MS. A total of 26 individuals of BAs were detected in the fish body, with 8, 10, 14, and 22 individuals of BAs detected in the liver, serum, bile, and hindgut digesta, respectively. The conjugated BAs (CBAs) of fish were dominated by taurine CBAs (TCBAs). The concentrations of free BAs (FBAs) and the value of FBAs/CBAs in the bile of fish fed the PEC diet were nearly 5 and 7 times higher, respectively than those in fish fed the CON diet. The value of glycine CBAs/TCBAs in the liver, serum and bile of fish fed the PEC diet was significantly lower, and in the hindgut digesta was higher than that of fish fed the CON diet (P < 0.05). These results suggested that dietary pectin greatly changed the BA profiles of Pelteobagrus fulvidraco, attributed to inhibition of reabsorption of BAs. Therefore, attention should be paid to the impact on BA homeostasis when replacing fishmeal with DF-rich plant ingredients in the fish diet.

Dietary hydrolyzed wheat gluten supplementation ameliorated intestinal barrier dysfunctions of broilers challenged with Escherichia coli O78

This study aimed to investigate a protective effect of hydrolyzed wheat gluten (HWG) on Escherichia coli (E. coli)-induced intestinal barrier dysfunctions in broilers. Broilers fed a basal diet unsupplemented or supplemented with HWG (0.5% or 1%) were intraperitoneally injected with either E. coli O78 suspension (10⁸ CFU/mL) or equal volume of vehicle on d 18 of age. Blood and tissue samples were collected 3rd d post infection. The results showed that E. coli-infection increased immune-organ indexes of spleen and thymus, enhanced serum diamine oxidase (DAO) level, impaired ileal villus structure and reduced tight junction mRNA levels (Occludin, Claudin-1, ZO-1, P < 0.05), while increased mRNA levels of inflammatory cytokines (TNF-α, IFN-γ, IL-1β, IL-6, IL-8) and TLR4 in the ileum of broilers (P < 0.05). The effects of E. coli O78 challenge on organ indexes of spleen and thymus, serum DAO level, mRNA levels of tight junctions were alleviated by 1% HWG supplementation, the upregulations of IL-1β and TLR4 were prevented by 0.5% HWG supplementation (P < 0.05). In addition, increased IFN-γ of E. coli-infected broilers was abrogated by 0.5% or 1% HWG supplementation (P < 0.05). In summary, dietary HWG supplementation ameliorated intestinal barrier dysfunctions triggered by E. coli-infection in the ileum of broilers. HWG supplementation might be a nutritional strategy to improve the intestinal mucosal barrier function of broilers.

Dietary dihydroartemisinin supplementation alleviates intestinal inflammatory injury through TLR4/NOD/NF-κB signaling pathway in weaned piglets with intrauterine growth retardation

The aim of present study was to evaluate whether diets supplemented with dihydroartemisinin (DHA) could alleviate intestinal inflammatory injury in weaned piglets with intrauterine growth retardation (IUGR). Twelve normal birth weight (NBW) piglets and 12 piglets with IUGR were fed a basal diet (NBW-CON and IUCR-CON groups), and another 12 piglets with IUGR were fed the basal diet supplemented with DHA at 80 mg/kg (IUGR-DHA group) from 21 to 49 d of age. At 49 d of age, 8 piglets with similar body weight in each group were sacrificed. The jejunal and ileal samples were collected for further analysis. The results showed that IUGR impaired intestinal morphology, increased intestinal inflammatory response, raised enterocyte apoptosis and reduced enterocyte proliferation and activated transmembrane toll-like receptor 4 (TLR4)/nucleotide-binding and oligomerization domain (NOD)/nuclear factor-κB (NF-κB) signaling pathway. Dihydroartemisinin inclusion ameliorated intestinal morphology, indicated by increased villus height, villus height-to-crypt depth ratio, villus surface area and decreased villus width of piglets with IUGR (P < 0.05). Compared with NBW piglets, IUGR piglets supplemented with DHA exhibited higher apoptosis index and caspase-3 expression, and lower proliferation index and proliferating cell nuclear antigen expression in the intestine (P < 0.05). Dihydroartemisinin supplementation attenuated the intestinal inflammation of piglets with IUGR, indicated by increased concentrations of intestinal inflammatory cytokines and lipopolysaccharides (P < 0.05). In addition, DHA supplementation down-regulated the related mRNA expressions of TLR4/NOD/NF-κB signaling pathway and upregulated mRNA expressions of negative regulators of TLR4 and NOD signaling pathway in the intestine of piglets with IUGR (P < 0.05). Piglets in the IUGR-DHA group showed lower protein expressions of TLR4, phosphorylated NF-κB (pNF-κB) inhibitor α, nuclear pNF-κB, and higher protein expression of cytoplasmic pNF-κB in the intestine than those in the IUGR-CON group (P < 0.05). In conclusion, DHA supplementation could improve intestinal morphology, regulate enterocyte proliferation and apoptosis, and alleviate intestinal inflammation through TLR4/NOD/NF-κB signaling pathway in weaned piglets with IUGR.

Genome-wide epistatic interactions of litter size at birth in Chinese indigenous pigs

Improving litter size at birth (TNB) and the number of piglets born alive (NBA) are the main breeding goals related to litter traits, which are economically important. A better understanding of genetic architecture underlying TNB and NBA traits could increase pig production efficiency. However, most previous studies on these traits focus on additive genetic effects, while epistatic interactions underlying TNB and NBA traits has not yet been well investigated, which are essential to understand how traits-related genes interact. Herein, we conducted genome scans of epistatic interactions underlying TNB and NBA traits in a total of 150 Chinese indigenous pigs (75 Jinhua and 75 Shengxian Spotted pigs) with high throughput genomic data. Based on SNPs with high interaction values and connectivity scores, we identified eight promising candidate genes (AKT2, TSC1, MTOR, PIK3R5, TIAM1, FGF14, RALB and ROR2) potentially associated with litter traits in pigs. Moreover, the underlying pathways, e.g., calcium ion transport, pointed out their roles in litter size-related traits. Our findings provide new insight into genetic architecture of litter traits in pigs and will benefit economic profits in pig production.

Dietary Supplementation of EGF Ameliorates the Negatively Effects of LPS on Early-Weaning Piglets: From Views of Growth Performance, Nutrient Digestibility, Microelement Absorption and Possible Mechanisms

Simple Summary

This study aims to investigate how epidermal growth factor (EGF) attenuates the effect of lipopolysaccharide (LPS) on the growth performance, nutrient digestibility, microelement absorption of early-weaned pigs. A total of 48 early weaned piglets were randomly distributed to four groups consisting of a 2 × 2 factorial design. The main factors were the level of LPS (H_LPS = high LPS: 100 μg/kg body weight; Z_LPS = low LPS: 0 μg/kg body weight) and EGF (H_EGF = high EGF: 2 mg/kg diet; Z_EGF = low EGF: 0 mg/kg diet). Each group had four replicates and each replicate consisted of three piglets. The results showed that H_LPS level decreased the growth performance and the apparent digestibility of crude fat, while H_EGF level increased the average daily feed intake. The concentration of most microelements in the gastrointestinal tract chyme and feces were increased by H_LPS level and decreased by H_EGF level. The expression levels of most microelement transport-relative genes in the mucosa of gastrointestinal tissues were decreased by H_LPS level and increased by H_EGF level. In conclusion, dietary EGF could attenuate the negative effect of LPS exposure on the apparent digestibility of crude fat and microelement absorption through changing the expression levels of microelement transport-relative genes. EGF can be used as an additive to increase the essential trace elements absorption in the early weaning piglets.

Abstract

Epidermal growth factor (EGF) plays an important role in nutrients absorption. However, whether it can be an effective additive to improve the growth performance and nutrients absorption in lipopolysaccharide (LPS) challenged early weaning piglets is still unknown. A 14-days trial was conducted to investigate how EGF attenuates the effect of LPS on the growth performance, nutrient digestibility, microelement absorption of early-weaned pigs, and study the underlying mechanism. A total of 48 early weaned piglets, aged 25 days, were randomly distributed to four groups (control, EGF, LPS and EGF + LPS groups) consisting of a 2 × 2 factorial design. The main factors were the level of LPS (H_LPS = high LPS: 100 μg/kg body weight; Z_LPS = low LPS: 0 μg/kg body weight) and EGF (H_EGF = high EGF: 2 mg/kg diet; Z_EGF = low EGF: 0 mg/kg diet). Each group had four replicates and each replicate consisted of three piglets. The results showed that piglets injected with H_LPS level significantly decreased the average daily gain (ADG), and significantly increased the feed conversion ratio (FCR) compared with the piglets injected with Z_LPS level, while piglets fed H_EGF level significantly increased the average daily feed intake (ADFI) compared with the piglets fed Z_EGF level (p < 0.05). Piglets injected with H_LPS level significantly decreased the apparent digestibility of crude fat compared with the piglets injected with Z_LPS level (p < 0.05). Piglets injected with H_LPS level significantly increased the concentration of most microelements in the gastrointestinal tract chyme and feces, and significantly decreased the expression levels of most microelement transport-relative genes in the mucosa of gastrointestinal tissues compared with the piglets injected with Z_LPS level (p < 0.05). Piglets fed H_EGF level significantly decreased the concentration of microelement in the gastrointestinal tract chyme and feces, and significantly increased the expression levels of the microelement transport-relative genes in the mucosa of gastrointestinal tissues compared with the piglets fed Z_EGF level (p < 0.05). In conclusion, dietary EGF could attenuate the negative effect of LPS exposure on the apparent digestibility of crude fat and microelement absorption of early-weaning piglets. EGF and LPS influenced the absorption of essential trace element through changing the expression levels of microelement transport-relative genes in the mucosa of gastrointestinal tissues. In the early weaning piglets, EGF can be used as an additive to increase the essential trace elements absorption.

Glycine alleviates fluoride-induced oxidative stress, apoptosis and senescence in a porcine testicular Sertoli cell line

Glycine is a well-known free radical scavenger in the cellular antioxidant system that prevents oxidative damage and apoptosis. Excessive fluoride exposure is associated with multiple types of cellular damage in humans and animals. The objective of the present study was to investigate the protective effects of glycine on sodium fluoride (NaF) exposure and the possible underlying mechanisms in a porcine testicular Sertoli cell line model. Cellular viability and proliferation were examined following NaF exposure and glycine supplementation, and glycine dramatically ameliorated the decreases in NaF-induced porcine testicular Sertoli cell viability and proliferation. Further investigations revealed that glycine decreased NaF-induced intracellular reactive oxygen species production, DNA fragment accumulation and the apoptosis incidence in the porcine testicular Sertoli cell line; in addition, glycine improved mitochondrial function and ATP production. Notably, results of the SPiDER-β-Gal analysis suggested that glycine alleviated NaF-induced cellular senescence and downregulated P53, P21, HMGA2 and P16INK4a gene expression in the porcine testicular Sertoli cell line. Collectively, the beneficial effects of glycine alleviate NaF-induced oxidative stress, apoptosis and senescence, and together with our previous findings, support the hypothesis that glycine plays an important role in protecting against NaF exposure-induced impairments in the porcine testicular Sertoli cell line.

Agar oligosaccharides ameliorate the intestinal inflammation of male Drosophila melanogaster via modulating the microbiota, and immune and cell autophagy

Agar oligosaccharide (AOS) is a marine prebiotic with apparent improving health and longevity effects. In this study, the protective effect of AOS on the intestine was evaluated in the sodium dodecyl sulfate (SDS)-induced inflammatory model of male Drosophila. The results showed that AOS used as a nutritional additive in basal food could lengthen the life of SDS-stimulated male Drosophila. Additionally, AOS could alleviate the injuries of SDS to microvilli and mitochondria in male Drosophila midgut epithelial cells. AOS could regulate the relative gene expressions in the antibacterial peptides (AMPs), mTOR pathway and autophagy process, and significantly improved the α-diversity of midgut microbiota and decreased the abundance of Klebsiella aerogenes, a kind of bacteria easily causing infections. Collectively, AOS could ameliorate the intestinal inflammation by modulating the microbiota, and the gene expression of immune and cell autophagy.

Construction and analysis for dys-regulated lncRNAs and mRNAs in LPS-induced porcine PBMCs

Long non-coding RNAs (lncRNAs) are emerging as key regulators in inflammation. However, their functions and profiles in LPS-induced inflammation in pigs are largely unknown. In this study, we profiled global lncRNA and mRNA expression changes in PBMCs treated with LPS using the lncRNA-seq technique. In total 43 differentially expressed (DE) lncRNAs and 1082 DE mRNAs were identified in porcine PBMCs after LPS stimulation. Functional enrichment analysis on DE mRNAs indicated these genes were involved in inflammation-related signaling pathways, including cytokine–cytokine receptor interaction, TNF-α, NF-κB, Jak-STAT and TLR signaling pathways. In addition, co-expression network and function analysis identified the potential lncRNAs related to inflammatory response and immune response. The expressions of eight lncRNAs (ENSSSCT00000045208, ENSSSCT00000051636, ENSSSCT00000049770, ENSSSCT00000050966, ENSSSCT00000047491, ENSSSCT00000049750, ENSSSCT00000054262 and ENSSSCT00000044651) were validated in the LPS-treated PBMCs by quantitative real-time PCR (qRT-PCR). In LPS-challenged piglets, we identified that expression of three lncRNAs (ENSSSCT00000051636, ENSSSCT00000049770, and ENSSSCT00000047491) was significantly up-regulated in liver, spleen and jejunum tissues after LPS challenge, which indicated that these lncRNAs might be important regulators for inflammation. This study provides the first lncRNA and mRNA transcriptomic landscape of LPS-mediated changes in porcine PBMCs, which might provide potential insights into lncRNAs involved in regulating inflammation in pigs.

Anti-Inflammatory Potential of Cow, Donkey and Goat Milk Extracellular Vesicles as Revealed by Metabolomic Profile

In recent years, extracellular vesicles (EVs), cell-derived micro and nano-sized structures enclosed in a double-layer membrane, have been in the spotlight for their high potential in diagnostic and therapeutic applications. Indeed, they act as signal mediators between cells and/or tissues through different mechanisms involving their complex cargo and exert a number of biological effects depending upon EVs subtype and cell source. Being produced by almost all cell types, they are found in every biological fluid including milk. Milk EVs (MEVs) can enter the intestinal cells by endocytosis and protect their labile cargos against harsh conditions in the intestinal tract. In this study, we performed a metabolomic analysis of MEVs, from three different species (i.e., bovine, goat and donkey) by mass spectroscopy (MS) coupled with Ultrahigh-performance liquid chromatography (UHPLC). Metabolites, both common or specific of a species, were identified and enriched metabolic pathways were investigated, with the final aim to evaluate their anti-inflammatory and immunomodulatory properties in view of prospective applications as a nutraceutical in inflammatory conditions. In particular, metabolites transported by MEVs are involved in common pathways among the three species. These metabolites, such as arginine, asparagine, glutathione and lysine, show immunomodulating effects. Moreover, MEVs in goat milk showed a greater number of enriched metabolic pathways as compared to the other kinds of milk.

The gut microbiota attenuates muscle wasting by regulating energy metabolism in chemotherapy-induced malnutrition rats

BACKGROUND

Malnutrition is a common clinical symptom in cancer patients after chemotherapy, which is characterized by muscle wasting and metabolic dysregulation. The regulation of muscle metabolism by gut microbiota has been studied recently. However, there is no direct convincing evidence proving that manipulating gut microbiota homeostasis could regulate muscle metabolic disorder caused by chemotherapy. Here, we investigate the potential role of gut microbiota in the regulation of the muscle metabolism in 5-fluorouracil (5-Fu)-induced malnutrition rat model.

METHODS

Male Sprague-Dawley rats were randomly divided into two groups (n = 8/group): control group and 5-Fu group. In the 5-Fu group, rats received 5-Fu (40 mg/kg/day) by intraperitoneal injection for 4 days, and all rats were raised for 8 days. Nutritional status, muscle function, muscle metabolites, and gut microbiota were assessed. Fecal microbiota transplantation (FMT) was applied to explore the potential regulation of gut microbiota on muscle metabolism.

RESULTS

5-Fu-treated rats exhibited loss of body weight and food intake compared to control group. 5-Fu decreased the levels of total protein and albumin in serum, and significantly increased the levels of IL-6 and TNF-α in muscle tissue. Rats that received 5-Fu displayed concurrent reduction of muscle function and fiber size. Moreover, 5-Fu group showed a distinct profile of gut microbiota compared to control group, including the relative lower abundance of Firmicutes and a higher abundance of Proteobacteria and Verrucomicrobia. Fourteen differential muscle metabolites were identified between two groups, which were mainly related to glycolysis, amino acid metabolism, and TCA cycle pathway. Furthermore, fecal transplantation from healthy rats improved nutritional status and muscle function in 5-Fu-treated rats. Notably, FMT inhibited the inflammatory response in muscle, and reversed the changes of several differential muscle metabolites and energy metabolism in 5-Fu-treated rats.

CONCLUSIONS

Our study demonstrated that gut microbiota played an important role in the regulation of muscle metabolism and promoting muscle energy production in 5-Fu-induced malnutrition rats, suggesting the potential attenuation of chemotherapy-induced muscle wasting by manipulating gut microbiota homeostasis.

Holly polyphenols alleviate intestinal inflammation and alter microbiota composition in lipopolysaccharide-challenged pigs

The effect of holly polyphenols (HP) on intestinal inflammation and microbiota composition was evaluated in a piglet model of lipopolysaccharide (LPS)-induced intestinal injury. A total of twenty-four piglets were used in a 2 × 2 factorial design including diet type and LPS challenge. After 16 d of feeding with a basal diet supplemented with or without 250 mg/kg HP, pigs were challenged with LPS (100 μg/kg body weight) or an equal volume of saline for 4 h, followed by analysis of disaccharidase activities, gene expression levels of several representative tight junction proteins and inflammatory mediators, the SCFA concentrations and microbiota composition in intestinal contents as well as proinflammatory cytokine levels in plasma. Our results indicated that HP enhanced intestinal disaccharidase activities and reduced plasma proinflammatory cytokines including TNF-α and IL-6 in LPS-challenged piglets. Moreover, HP up-regulated mRNA expression of intestinal tight junction proteins such as claudin-1 and occludin. In addition, bacterial 16S rRNA gene sequencing showed that HP altered hindgut microbiota composition by enriching Prevotella and enhancing SCFA production following LPS challenge. These results collectively suggest that HP is capable of alleviating LPS-triggered intestinal injury by improving intestinal disaccharidase activities, barrier function and SCFA production, while reducing intestinal inflammation.

Metabolomic Profile of Posner-Schlossman Syndrome: A Gas Chromatography Time-of-Flight Mass Spectrometry-Based Approach Using Aqueous Humor

The Posner-Schlossman syndrome (PSS) is a disease with clinically recurrent unilateral anterior uveitis with markedly elevated intraocular pressure (IOP) and subsequent progression to optic neuropathy. Retrospective studies have reported increased annual incidence of PSS, especially in China. While currently, the clinical management of PSS is still challenging. Metabolomics is considered to be a sensitive approach for the development of novel targeted therapeutics because of its direct elucidation of pathophysiological mechanisms. Therefore, we adopted gas chromatography time-of-flight mass spectrometry (GC-TOF-MS) technology-based non-targeted metabolomics approach to measure comprehensive metabolic profiles of aqueous humor (AH) samples obtained from patients with PSS, with an aim to demonstrate the underlying pathophysiology, identify potential biomarkers specific to PSS, and develop effective treatment strategies. A comparative analysis was used to indicate the distinct metabolites of PSS. Pathway analysis was conducted using MetaboAnalyst 4.0 to explore the metabolic reprogramming pathways involved in PSS. Logistic regression and receiver-operating characteristic (ROC) analyses were employed to evaluate the diagnostic capability of selected metabolites. Comparative analysis revealed a clear separation between PSS and control groups. Fourteen novel differentiating metabolites from AH samples obtained from patients with PSS were highlighted. Pathway analysis identified 11 carbohydrate, amino acid metabolism and energy metabolism pathways as the major disturbed pathways associated with PSS. The abnormal lysine degradation metabolism, valine-leucine-isoleucine biosynthesis, and citrate circle were considered to weigh the most in the development of PSS. The ROC analysis implied that the combination of glycine and homogentisic acid could serve as potential biomarkers for the discrimination of control and PSS groups. In conclusion, these results revealed for the first time the identity of important metabolites and pathways contributing to the development/progression of PSS, enabled the better understanding of the mechanism of PSS, and might lead to the development of metabolic biomarkers and novel therapeutic strategies to restrict the development/progression of PSS.

Long non-coding RNA profiling in LPS-induced intestinal inflammation model: New insight into pathogenesis

LPS can induce an inflammatory immune response in the intestine, and long non-coding RNA (lncRNA) is involved in the process of inflammatory disease. However, the biological role of lncRNA in the intestinal inflammation of piglets remains unclear. In this study, the lncRNA expression profile of the ileal mucosa of piglets challenged by LPS was analysed using lncRNA sequencing. In total, 112 novel lncRNAs were predicted, of which 58 were up-regulated and 54 down-regulated following LPS challenge. Expression of 15 selected lncRNAs was validated by quantitative PCR. We further investigated the target genes of lncRNA that were enriched in the signalling pathways involved in the inflammatory immune response by utilising Gene Ontology and Kyoto Encyclopaedia of Genes and Genomes analysis, with cell adhesion molecules and mTOR signalling pathway identified. In addition, the co-expression networks between the differentially expressed lncRNAs and the target mRNAs were constructed, with seven core lncRNAs identified, which also demonstrated that the relationship between lncRNAs and the target genes was highly correlated. Our study offers important information about the lncRNAs of the mucosal immune system in piglets and provides new insights into the inflammatory mechanism of LPS challenge, which might serve as a novel target to control intestinal inflammation.

Evaluation of Supplementation of Defatted Black Soldier Fly (Hermetia illucens) Larvae Meal in Beagle Dogs

The objective of this experiment was to test the effects of supplementation of defatted black soldier fly (Hermetia illucens) larvae (BSFL) meal in beagle dogs. A total of nine healthy female beagles (initial body weight 12.1 ± 1.76 kg) were fed grain-based diets with three levels of BSFL meal (0, 1% or 2%) in a 42-day feeding trial. At the end of week 6 of the experiment, all dogs were intraperitoneally challenged with Escherichia coli lipopolysaccharide (LPS) at 100 μg/kg of body weight. Albumin concentration was linearly increased with increasing BSFL meal level (P<0.05). A linear increase (P<0.05) in calcium concentration was observed when increasing dietary BSFL meal. Although dietary treatments did not affect the digestibility of ether extract, the digestibility of dry matter and crude protein were linearly increased with increasing the level of BSFL meal. The concentration of tumor necrosis factor-α was linearly decreased but glutathione peroxidase (GPx) concentration was linearly increased when increasing the level of BSFL meal at 6 h after challenge (P<0.05). In addition, there were quadratic increases in concentrations of GPx and superoxide dismutase with increasing dietary BSFL meal level at 3 h after challenge (P<0.05). These findings from the present study demonstrate that BSFL meal can be supplemented in the diet to convert beneficial effects to beagle dogs, indicated as improved digestibility of dry matter and crude protein and anti-inflammatory and anti-oxidative capacity.