L-Threonine upregulates the expression of β-defensins by activating the NF-κB signaling pathway and suppressing SIRT1 expression in porcine intestinal epithelial cells

Heat Stress in Growing-Finishing Pigs: Effects of Low Protein with Increased Crystalline Amino Acids on Growth, Gut Health, Antioxidant Status and Microbiome

A total of sixty crossbred ([Landrace × Yorkshire] × Duroc) pigs with an initial body weight of 46.34 ± 0.13 kg were randomly assigned to four treatments under thermoneutral (TN, 22 °C) or heat-stress (HS, 31 °C) conditions for 54 d trial (Phase 1: 0-26 d; Phase 2: 27-54 d): a control diet (16% CP in phase 1, 14% CP in phase 2) under TN (PC), a control diet under HS (NC), a low crude protein (LCP) diet (14% CP in phase 1, 12% CP in phase 2) under HS (LCP) and an LCP diet with increased crystalline AA (an increase in 5% in Lys, Met, Thr and Trp based on calculated SID AA) (LCP5) under HS. Experimental treatments consisted of five replicate pens, with three pigs per pen. The results showed that HS reduced (p < 0.05) growth performance and nutrient digestibility compared to TN. However, LCP5 improved (p < 0.05) growth performance and nutrient digestibility compared to other HS groups. Heat stress adversely affected (p < 0.05) intestinal morphology, gut integrity and serum oxidative markers, but these effects were alleviated (p < 0.05) by LCP5 supplementation. Notably, LCP5 improved (p < 0.05) the production of butyric acids among short-chain fatty acid production and decreased (p < 0.05) proteobacteria and Spirochaetota in phylum in feces. These findings highlight the potential of LCP diets supplemented with crystalline AA as an effective nutritional strategy to mitigate the negative effects of HS on pigs, enhancing their performance, gut health and overall welfare in high-temperature environments.

Piggybacking on nature: exploring the multifaceted world of porcine β-defensins

Porcine β-defensins (pBDs) are cationic peptides that are classically associated with the innate immune system. These molecules yield both antimicrobial and immunomodulatory properties, as evidenced by various in vitro and animal trials. Researchers have revealed that enhancing pBD expression can be achieved through dietary components and gene editing techniques in pigs and porcine cell models. This state-of-the-art review aims to encapsulate the pivotal findings and progress made in the field of pBD over recent decades, with a specific emphasis on the biological role of pBD in infection control and its usage in clinical trials, thereby offering a new landscape of opportunities for research aimed at identifying prophylactic and therapeutic alternatives for both swine medicine and translational purposes.

An ultrasonic degraded polysaccharide extracted from Pueraria lobata ameliorate ischemic brain injury in mice by regulating the gut microbiota and LPS-TLR4 pathway

Ischemia brain injury is closely associated with the gut microbiota. Polysaccharides, as a typical prebiotic, have been extensively employed in stroke treatment. In our previous study, Pueraria lobata polysaccharide (PLP-3) with antioxidant activity was prepared via water extraction and alcohol precipitation combined with ultrasonic degradation. In this study, the effects of PLP-3 on ischemia brain injury and its regulatory effects on the gut microbiota were further investigated. The results demonstrated that PLP-3 effectively reduced the infarct area, improves neurological function, and alleviates neuronal damage of cerebral ischemia injury. Mechanistically, PLP-3 significantly reduces serum LPS levels in MCAO mice, inhibiting TLR-4 activation in brain tissue and thereby reducing IL-1β and TNF-α levels. Meanwhile, PLP-3 significantly repaired the intestinal barrier injury by increasing the expression of tight junction proteins (ZO-1 and Occludin) and increasing the number of goblet cells. Additionally, the structure and composition of gut microbiota in MCAO mice after PLP-3 intervention, were also significantly changed, especially the enrichment of Lactobacillus and the reduction of Corynebacterium and Staphylococcus. At the same time, short chain fatty acid, metabolites of gut microbiota, were also significantly increased and significantly correlated with the abundance of Lactobacillus. Moreover, LC-MS untargeted metabolomics revealed that PLP-3 significantly improves the intestinal metabolic profile after cerebral ischemia injury, upregulating the amino acid biosynthesis pathway and enriching amino acids such as glutamine and arginine, as well as neuroprotective flavonoids such as fisetin and liquiritigenin. These results suggested that PLP-3 could protect mice from cerebral ischemia-reperfusion injury by regulating gut microbiota and repairing gut barrier, inhibiting brain LPS/TLR4/MyD88 inflammatory pathway, therefore we provide a theoretical basis for PLP-3 as a functional food to prevent ischemic brain injury.

Threonine attenuates lipopolysaccharide-induced intestinal inflammatory responses in rabbits

PURPOSE

Threonine (Thr) can be involved in the synthesis of immunoglobulins, which play the role of immune regulation, Thr also has to improve intestinal morphology, adjust the sticky protein synthesis, maintain the intestinal barrier function, etc. The experiment aimed to investigate the effects of diets supplemented with different levels of Thr on growth performance and intestinal health of rabbits under lipopolysaccharide (LPS) stress conditions.

METHODS

A total of 180 healthy 35-day-old weaned New Zealand White rabbits were randomly assigned in a 2 × 3 factorial design to receive an intraperitoneal injection of 100 µg/kg BW LPS or saline and three diets with different levels of digestible threonine (0.43%, 0.54%, and 0.64%).

RESULTS

The LPS challenge resulted in a reduction in body weight in rabbits at day 22, as well as a decrease in the serum d-lactic acid (D-LA) content and the number of goblet cells (GCs) in the jejunum. Additionally, the duodenum JAM2 and JAM3 were down-regulated. The expression of OCLN, ZO-1, and IL-2 in the jejunum, and CLDN, nuclear factor-κB (NF-κB) and ZO-1 mRNA in the ileum were also down-regulated. Furthermore, the duodenum TLR4 and IL-1β mRNA expression, while the jejunum exhibited an elevation in CLDN, TNF-α, and ileum TNF-α mRNA expression (P < 0.05). In the context of LPS challenge condition, dietary Thr addition was found to down-regulate the duodenum ZO-1 and jejunum CLDN mRNA expression of rabbits (P < 0.05). This was accompanied by an increase in ileum sIgA content and GCs number (P < 0.05). Additionally, dietary Thr addition resulted in a downregulation of duodenum TLR4, MyD88, NF-κB, TNF-α and IL-1β, jejunum MyD88, and IL-1β mRNA expression, as well as an up-regulation of ileum IL-10 mRNA expression in rabbits (P < 0.05).

CONCLUSION

In conclusion, the LPS challenge can result in intestinal inflammation and damage the integrity of the intestinal barrier in rabbits. Nevertheless, dietary Thr supplementation can alleviate the intestinal inflammatory response in rabbits challenged with LPS.

Spirobenzofuran Mitigates Ochratoxin A-Mediated Intestinal Adverse Effects in Pigs through Regulation of Beta Defensin 1

Antimicrobial peptides (AMPs) function to extensively suppress various problematic factors and are considered a new alternative for improving livestock health and enhancing immunomodulation. In this study, we explored whether AMP regulation has positive influences on Ochratoxin A (OTA) exposure using a porcine intestinal epithelial cell line (IPEC-J2 cells). We constructed a beta-defensin 1 (DEFB1) expression vector and used it to transfection IPEC-J2 cells to construct AMP overexpression cell lines. The results showed that OTA induced cytotoxicity, decreased cell migration, and increased inflammatory markers mRNA in IPEC-J2 cells. In DEFB1 overexpressing cell lines, OTA-induced reduced cell migration and increased inflammatory markers mRNA were alleviated. Additionally, a natural product capable of inducing DEFB1 expression, which was selected through high-throughput screening, showed significant alleviation of cytotoxicity, cell migration, and inflammatory markers compared to OTA-treated IPEC-J2 cells. Our finding provides novel insights and clues for the porcine industry, which is affected by OTA exposure.

Dietary tryptophan improves growth and intestinal health by promoting the secretion of intestinal β-defensins against enterotoxigenic Escherichia coli F4 in weaned piglets

Adequate dietary L-tryptophan (Trp) governs intestinal homeostasis in piglets. However, the defensive role of Trp in the diet against enterotoxigenic Escherichia coli F4 (K88) in pigs is still poorly understood. Here, sixty (6.15 ± 1.52 kg, 24-day-old, Duroc × Landrace × Yorkshire) weaned piglets were used for an E. coli F4 attack test in a 2 × 2 factorial design. The growth (ADG, ADFI, GH), immune factors (IL-10, IgA, IgG, IgM), Trp metabolite 5-HT, intestinal morphology (jejunal and colonic VH), mRNA expression of β-defensins (jejunal BD-127, BD-119, ileal BD-1, BD-127), and abundance of beneficial microorganisms in the colon (Prevotella 9, Lactobacillus, Phascolarctobacterium, Faecalibacterium) were higher in the piglets in the HT (High Trp) and HTK (High Trp, K88) groups than in the LT (Low Trp) and LTK (Low Trp, K88) groups (P<.05), while FCR, diarrhea rate, diarrhea index, serum Trp, Kyn, IDO, D-LA, ET, and abundance of harmful microorganisms in the colon (Spirochaetes, Fusobacteria, Prevotella, Christensenellaceae R7) were lower in the HT and HTK groups than in the LT and LTK groups (P<.05). High Trp reduced the expression of virulence genes (K88 and LT) after E. coli F4 attack (P<.05). The IL-6, TNF-α was lower in the HTK group than in the LT, LTK group (P<.05). In short, a diet containing 0.35% Trp protected piglets from enterotoxigenic E. coli F4 (K88) via Trp metabolism promoting BD expression in the intestinal mucosa, which improved growth and intestinal health.

Modulatory Effects of Co-Fermented Pu-erh Tea with Aqueous Corn Silk Extract on Gut Microbes and Fecal Metabolites in Mice Fed High-Fat Diet

Pu-erh tea is recognized for its weight loss effects, but its potential association with gut microbiota and metabolites remains unclear. This research explored the alterations in gut flora and metabolite composition upon treatment with a co-fermented Pu-erh tea with an aqueous corn silk extract (CPC) in obese mice by employing integrated 16S ribosomal RNA gene sequencing and untargeted metabolomics processes. For 8 weeks, mice were fed control, high-fat, and high-fat diets which included a 46 mg/mL CPC extract. The CPC extract the alleviated high-fat diet (HFD), it stimulated systemic chronic inflammation, and it reduced the body weight, daily energy consumption, and adipose tissue weight of the mice. It also modified the gut microbiota composition and modulated the Lactobacillus, Bifidobacterium, Allobaculum, Turicibacter, and Rikenella genera. Fecal metabolomics analysis revealed that the CPC extract influenced the caffeine, cysteine, methionine, tryptophan, biotin metabolism pathways, primary bile acid, and steroid biosynthesis. This research revealed that the CPC extract could inhibit HFD-stimulated abnormal weight gain and adipose tissue accumulation in mice, and modulate mice gut microbiota composition and multiple metabolic pathways.

Biomarker identification and pathway analysis of Astragalus membranaceus and Curcuma zedoaria couplet medicines on adenine-induced chronic kidney disease in rats based on metabolomics

Background: Chronic kidney disease (CKD) is usually insidious, and most affected individuals are asymptomatic until the disease becomes advanced. The effective treatment of CKD would rely on the incorporation of multidisciplinary approaches. Astragalus membranaceus (AM) and Curcuma zedoaria (CZ) have been widely used in the treatment of CKD. However, the mechanism of AM and CZ in the treatment of CKD is still unclear.

Methods: This study was designed to evaluate the effects of AM and CZ on adenine-induced rats and to investigate the underlying mechanism by using metabolomic analysis. Addition of 0.75% adenine to the diet of rats for 3 weeks induced the animal model of CKD. The rats in the treatment group were treated with AM and CZ (2.1 g/kg/day) for 4 weeks. Blood and kidney samples were collected for biochemical and histological examination. Ultra-high-performance liquid chromatography/Q Exactive HFX mass spectrometer (UHPLC-QE-MS) was applied to analyze metabolic profiling variations in the kidney.

Results: The results showed that AM and CZ could significantly reduce serum creatinine (Scr) and blood urea nitrogen (BUN) levels in CKD rats and alleviate renal pathological injury. By comparing the endogenous components of the normal group and the model group in positive ion mode and negative ion mode, a total of 365 and 155 different metabolites were screened, respectively. A total of 117 and 73 metabolites with significantly different expressions were identified between model group and AM and CZ group in positive ion mode and negative ion mode, respectively. The pivotal pathways affected by AM and CZ included nicotinate and nicotinamide metabolism, and glycine, serine and threonine metabolism. Furthermore, significant changes in metabolites in CKD rats after AM and CZ therapies were observed, including L-Threonine, D-pantothenic acid, and nicotinamide. Moreover, we found that AM and CZ significantly reduced renal fibrosis and inflammation in CKD rats, which may be related to the regulation of SIRT1/JNK signaling pathway.

Conclusion: In conclusion, AM and CZ significantly reduced renal fibrosis and inflammation in CKD rats, which may be related to the regulation of SIRT1/JNK signaling pathway. Furthermore, L-Threonine, D-pantothenic acid, and nicotinamide may be potential biomarkers for the progression and treatment of CKD.

Novel Insight Into Nutritional Regulation in Enhancement of Immune Status and Mediation of Inflammation Dynamics Integrated Study In Vivo and In Vitro of Teleost Grass Carp (Ctenopharyngodon idella): Administration of Threonine

This study aims to investigate the effects of threonine (Thr) on immunoregulation in vivo and in vitro of teleost grass carp (Ctenopharyngodon idella). Juveniles (9.53 ± 0.02 g) were reared for 8 weeks with respective Thr diet (3.99, 7.70, 10.72, 14.10, 17.96, and 21.66 g/kg) and then challenged with Aeromonas hydrophila for in vivo study. Macrophages isolated from head kidney were treated in vitro for 48 h with L-Thr (0, 0.5, 1.0, 2.0, 4.0, and 8.0 mM) after 6 h of lipopolysaccharide induction. The results showed that, compared with Thr deficiency (3.99 g/kg), the optimal dietary Thr (14.10g/kg) affected the immunocyte activation in the head kidney (HK) and spleen (SP) by downregulating the mRNA expressions of MHC-II and upregulating CD4 (not CD8), and it mediated the innate immune by enhancing the activities of lysozyme (LZ), acid phosphatase content of complement 3 (C3) and C4, increasing the mRNA abundances of hepcidin, liver expressed antimicrobial peptide-2A (LEAP-2A), LEAP-2B, β-defensin1, downregulating tumor necrosis factor α (TNF-α), IL-6, IL-1β, IL-12p35, IL-12p40, IL-17AF1, and IL-17D partly by attenuating RORγ1 transcriptional factor and nuclear factor kappa B p65 (NF-κBp65) signaling cascades [IKKβ/IκBα/NF-κBp65] and upregulating transforming growth factor β1 (TGF-β1), IL-4/13A, -4/13B, IL-10, and IL-22 partly by GATA-3. Besides these, the optimal dietary Thr regulated the adaptive immune by upregulating the mRNAs of immunoglobulin M (IgM) and IgZ (not IgD). Moreover, 2 mM Thr downregulated in vitro the mRNA abundances of colony stimulating factor-1, inducible nitric oxide synthase, mannose receptor 1, matrix metalloproteinase2 (MMP-2), and MMP-9 significantly (P < 0.05), indicating that Thr could attenuate the M1-type macrophages’ activation. Moreover, L-Thr downregulated the mRNA transcripts of TNF-α, IL-6, and IL-1β associated with impairing the SOCS1/STAT1 signaling and upregulated IL-10 and TGF-β1 partly by accentuating the SOCS3/STAT3 pathway. The above-mentioned observations suggested that Thr improved the immune status in the immune organs of fish by enhancing the immune defense and mediating the inflammation process. Finally, based on the immune indices of LZ activity in HK and C3 content in SP, the optimal Thr for immune enhancement in juvenile grass carp (9.53–53.43 g) was determined to be 15.70 g/kg diet (4.85 g/100 g protein) and 14.49 g/kg diet (4.47 g/100 g protein), respectively.

DL-Selenomethionine Alleviates Oxidative Stress Induced by Zearalenone via Nrf2/Keap1 Signaling Pathway in IPEC-J2 Cells

Zearalenone (ZEN) is a kind of nonsteroidal mycotoxin that is considered a risk affecting the safety of human food and livestock feed that causes oxidative damages in mammalian cells. Selenomethionine (SeMet) was indicated to have antioxidant activity and received great interest in investigating the role of SeMet as a therapeutic agent in oxidation. Therefore, the aim of this study was to investigate the hormetic role of DL-SeMet in porcine intestinal epithelial J2 (IPEC-J2) cells against ZEN-induced oxidative stress injury. As a result of this experiment, 30 μg/mL of ZEN was observed with significantly statistical effects in cell viability. Following the dose-dependent manner, 20 μg/mL was chosen for the subsequent experiments. Then, further results in the current study showed that the ZENinduced oxidative stress with subsequent suppression of the expression of antioxidant stress pathway-related genes species. Moreover, SeMet reversed the oxidative damage and cell death of ZEN toxins to some extent, by a Nrf2/Keap1-ARE pathway. The finding of this experiment provided a foundation for further research on the ZEN-caused cell oxidative damage and the cure technology.

Physiological Functions of Threonine in Animals: Beyond Nutrition Metabolism

Threonine (Thr), an essential amino acid for animals and the limiting amino acid in swine and poultry diets, which plays a vital role in the modulation of nutritional metabolism, macromolecular biosynthesis, and gut homeostasis. Current evidence supports that the supplementation of Thr leads to benefits in terms of energy metabolism. Threonine is not only an important component of gastrointestinal mucin, but also acts as a nutritional modulator that influences the intestinal immune system via complex signaling networks, particularly mitogen-activated protein kinase (MAPK) and the target of the rapamycin (TOR) signal pathway. Threonine is also recognized as an indispensable nutrient for cell growth and proliferation. Hence, optimization of Thr requirement may exert a favorable impact on the factors linked to health and diseases in animals. This review focuses on the latest reports of Thr in metabolic pathways and nutritional regulation, as well as the relationship between Thr and relevant physiological functions.