Dietary leonurine hydrochloride supplementation attenuates lipopolysaccharide challenge-induced intestinal inflammation and barrier dysfunction by inhibiting the NF-κB/MAPK signaling pathway in broilers

Effect of lipopolysaccharides from pathogenic bacteria on broiler chickens' productivity: a meta-analysis

1. This meta-analysis investigated the impact of LPS and covariates (serotype, rearing period and administration route) on the productivity parameters of broiler chickens (average daily feed intake (ADFI), average daily gain (ADG) and feed conversion ratio (FCR)).2. Thirty-two eligible studies were included. Hedges' g effect size was determined using a random-effects model at 95% confidence interval.3. Results showed that LPS significantly decreased average daily feed intake (ADFI; p < 0.0001) and average daily gain (ADG; p < 0.0001) and increased FCR (p < 0.0001). The serotypes Escherichia coli 055: B5 (EC055: B5) and Escherichia coli 0127: B8 (EC 0127: B8) significantly reduced ADFI and ADG, and the serotype EC 055: B5 significantly increased the FCR (p < 0.05).4. The intraperitoneal administration of the LPS significantly reduced the productivity of broiler chickens (p < 0.05), but other administration routes did not show such effects. The reduction in ADFI and ADG was found in all rearing periods (p < 0.05), and the increase in FCR was observed in the starter (p = 0.0302) and grower periods (p = 0.0031).5. Exposure to LPS significantly reduced the productivity of broiler chickens (p < 0.05). However, no relationship was observed between LPS dosage and productivity as indicated by the meta-regression study.6. The findings indicated that LPS has detrimental effects on broiler chickens' ADFI, ADG and FCR across various LPS serotypes and rearing periods. These detrimental impacts of LPS remain consistent regardless of the administered dosage.

Effect of supplementation with Lactobacillus rhamnosus GG powder on intestinal and liver damage in broiler chickens challenged by lipopolysaccharide

This study explores the effect of dietary along with Lactobacillus rhamnosus GG (LGG) powder on intestinal and liver damage in broiler chickens challenged by lipopolysaccharide (LPS). A total of 100 healthy 1-day-old Ross 308 broiler chickens were selected and randomly divided into two treatments: the control group and the LGG treatment group. There were five replicates for each group, with 10 chickens per replicate. The chickens in the control group were fed a basal diet, while LGG treatment was supplemented with 1,000 mg/kg LGG along with the basal diet. The experiment lasted 29 days, and the trial included two phases. During the first 27 days, the animals were weighed on the 14th and 27th days to calculate growth performance. Then, on day 29, 2 animals from each replicate were intraperitoneally injected with 1 mg/kg BW LPS, and another 2 animals were treated with an equal volume of saline. The chickens were slaughtered 3 h later for sampling and further analysis. (1) LGG addition to the diet did not affect growth performance, including average daily gain (ADG), average daily feed intake (ADFI), and feed-to-weight ratio (F/G) of broiler chickens; (2) LPS stimulation decreased villus height (VH), and caused oxidative stress and increased the amount of diamine oxidase (DAO) in plasma, and the relative expression of intestinal inflammation genes (interleukin-8 [IL-8], interleukin 1β [IL-1β], inducible nitric oxide synthase [iNOS], and tumor necrosis factor-α [TNF-α]) and the relative expression of liver injury genes (b-cell lymphoma 2 [BCL2], heat shock protein70 [HSP70], and matrix metallopeptidase 13 [MMP13]). (3) Supplementation of LGG increased VH and the relative expression of intestinal barrier genes (mucins 2 [Mucin2] and occludin [Occludin]) and decreased the amount of DAO in plasma and the relative expression of intestinal inflammatory factors (IL-8, iNOS, and IL-1β). LGG supplementation also increased the expression of liver injury-related genes (MMP13 and MMP9). In conclusion, LGG enhanced intestinal barrier function, improved intestinal morphology, and alleviated the intestines' inflammatory response in LPS-stimulated broiler chicken, and it has a slightly protective effect on liver damage.

Dietary astragalin confers protection against lipopolysaccharide-induced intestinal mucosal barrier damage through mitigating inflammation and modulating intestinal microbiota

Introduction

The intestinal mucosal barrier (IMB) damage is intricately linked with the onset of numerous intestinal diseases. Astragalin (AS), a flavonoid present in numerous edible plants, exhibits notable antioxidant and anti-inflammatory properties, demonstrating a promising impact on certain intestinal ailments. In this study, our objective was to investigate the protective effects of AS and elucidate the underlying mechanisms by which it mitigates lipopolysaccharide (LPS)-induced damage to the IMB in mice.

Methods

During the experimental period, mice were subjected to a 7-day regimen of AS treatment, followed by LPS injection to induce IMB damage. Subsequently, a comprehensive evaluation of relevant biological indicators was conducted, including intestinal pathological analysis, serum inflammatory factors, intestinal tight junction proteins, and intestinal microbiota composition.

Results

Our results suggested that AS treatment significantly bolstered IMB function. This was evidenced by the enhanced morphology of the small intestine and the elevated expression of tight junction proteins, including ZO-1 and Claudin-1, in addition to increased levels of MUC2 mucin. Moreover, the administration of AS demonstrated a mitigating effect on intestinal inflammation, as indicated by the reduced plasma concentrations of pro-inflammatory cytokines such as IL-6, IL-1β, and TNF-α. Furthermore, AS treatment exerted a positive influence on the composition of the gut microbiota, primarily by augmenting the relative abundance of beneficial bacteria (including Lachnospiracea and Lactobacillus murinus), while simultaneously reducing the prevalence of the harmful bacterium Mucispirillum schaedleri.

Conclusion

AS mitigates LPS-induced IMB damage via mitigating inflammation and modulating intestinal microbiota.

Dietary Kluyveromyces marxianus hydrolysate alters humoral immunity, jejunal morphology, cecal microbiota and metabolic pathways in broiler chickens raised under a high stocking density

This study investigated the impact of dietary supplementation with hydrolyzed yeast (Kluyveromyces marxianus) on growth performance, humoral immunity, jejunal morphology, cecal microbiota and metabolic pathways in broilers raised at 45 kg/m2. A total of 1,176 mixed sex 1-day-old Ross 308 broilers were distributed into 42 pens and randomly assigned to either the control group, the control + 250 g hydrolyzed yeast (HY)/ton, 250HY group, or the control + 500 g HY/ton, 500HY group for 42 d. HY did not affect growth performance. However, HY reduced (P < 0.05) mortality at 25 to 35 d. Dietary HY lowered the heterophil/lymphocyte ratio and enhanced the villus height/crypt depth ratio and Newcastle disease titer (P < 0.05). Compared with HY250 and the control, HY500 upregulated (P < 0.05) IL-10. HY enhanced the α diversity, inferring the richness and evenness of the ceca microbiota. HY500 had greater β diversity than the control (P < 0.05). Six bacterial phyla, namely, Firmicutes, Bacteroidetes, Proteobacteria, Actinobacteria, Verrucomicrobia, and Cyanobacteria, were found. The relative abundance of Firmicutes was greater in the HY500 treatment group than in the HY250 and control groups. HY decreased the abundance of Actinobacteria. HY supplementation altered (P < 0.05) the abundance of 8 higher-level taxa consisting of 2 classes (Bacilli and Clostridia), 1 order (Lactobacillales), 1 family (Streptococcaceae), and five genera (Streptococcus, Lachnospiraceae_uc, Akkermansiaceae, PACO01270_g, and LLKB_g). HY500 improved (P < 0.05) the abundance of Bacilli, Clostridia, Lactobacillales, Streptococcaceae, Streptococcus, PACO01270_g, and Lachnospiraceae_uc, while HY250 enhanced (P < 0.05) the abundance of Akkermansiaceae and LLKB_g. HY improved the abundance of Lactobacillus and Akkermansia spp. Minimal set of pathway analyses revealed that compared with the control, both HY250 and HY500 regulated 20 metabolic pathways. These findings suggest that dietary K. marxianus hydrolysate, especially HY500, improved humoral immunity and jejunal morphology and beneficially altered the composition and metabolic pathways of the cecal microbiota in broilers raised at 45 kg/m2.

Oxidative stress in poultry production

Oxidative stress (OS) is a major concern that impacts the overall health of chickens in modern production systems. It is characterized by an imbalance between antioxidant defence mechanisms and the production of reactive oxygen species (ROS). This literature review aims to provide a comprehensive overview of oxidative stress in poultry production, with an emphasis on its effects on growth performance, immune responses, and reproductive outcomes. This review highlights the intricate mechanisms underlying OS and discusses how various factors, including dietary components, genetic predispositions, and environmental stressors can exacerbate the production of ROS. Additionally, the impact of oxidative stress on the production performance and physiological systems of poultry is examined. The study also emphasizes the relationship between oxidative stress and poultry diseases, highlighting how impaired antioxidant defenses increase bird's susceptibility to infections. The review assesses the existing approaches to reducing oxidative stress in chickens in response to these challenges. This includes managing techniques to lower stress in the production environment, antioxidant supplements, and nutritional interventions. The effectiveness of naturally occurring antioxidants, including plant extracts, minerals, and vitamins to improve poultry resistance to oxidative damage is also examined. To improve the antioxidant defenses of poultry under stress conditions, the activation of cellular homeostatic networks termed vitagenes, such as Nuclear Factor Erythroid 2-Related Factor 2 (Nrf2) is necessary for the synthesis of protective factors that can counteract the increased production of ROS and RNS. Future studies into novel strategies for managing oxidative stress in chicken production would build on these research advances and the knowledge gaps identified in this review.

Dietary α-linolenic acid supplementation enhances resistance to Salmonella Typhimurium challenge in chickens by altering the intestinal mucosal barrier integrity and cecal microbes

Salmonella is an important foodborne pathogen. Given the ban on the use of antibiotics during the egg-laying period in China, finding safe and effective alternatives to antibiotics to reduce Salmonella enterica subsp. enterica serovar Typhimurium (S. Typhimurium) infections in chickens is essential for the prevention and control of this pathogen and the protection of human health. Numerous studies have shown that unsaturated fatty acids have a positive effect on intestinal inflammation and resistance to infection by intestinal pathogens. Here we investigated the protective effect of α-linolenic acid (ALA) against S. Typhimurium infection in chickens and further explored its mechanism of action. We added different proportions of ALA to the feed and observed the effect of ALA on S. Typhimurium colonization using metagenomic sequencing technology and physiological index measurements. The role of gut flora on S. Typhimurium colonization was subsequently verified by fecal microbiota transplantation (FMT). We found that ALA protects chickens from S. Typhimurium infection by reducing intestinal inflammation through remodeling the gut microbiota, up-regulating the expression of ileocecal barrier-related genes, and maintaining the integrity of the intestinal epithelium. Our data suggest that supplementation of feed with ALA may be an effective strategy to alleviate S. Typhimurium infection in chickens.

Biomarkers of oxidative stress in broiler chickens attacked by lipopolysaccharide: A systematic review and meta-analysis

Oxidative stress (OS) constitutes a pivotal factor in the initiation and progression of lipopolysaccharide (LPS) challenges in broiler chickens. Increasing studies have demonstrated that Alleviation of oxidative stress seems to be a reasonable strategy to alleviate LPS-mediated afflictions in broilers. Nonetheless, the relationship between OS-related indicators and exposure to LPS remains a topic of debate. The aim of this investigation was to precisely and holistically evaluate the effect of LPS exposure on OS-associated markers. We conducted a systematic search of four electronic databases-PubMed, Web of Science, Scopus, and Cochrane for relevant studies, and a total of 31 studies were included. The overall results showed that the LPS treatment significantly increased the levels of oxygen radicals and their products, such as malondialdehydes (MDA), reactive oxygen species (ROS), and 8-hydroxy-2-deoxyguanosine (8-OHdG), while significantly reduced the levels of antioxidants, such as total antioxidative capacity (T-AOC), total superoxide dismutase (T-SOD), catalase (CAT), glutathione peroxidase (GSH-Px), and glutathione (GSH), in the chickens. Intriguingly, though the observed trends in alterations were not strictly correlated with LPS concentrations, the enzyme activity levels were indeed influenced by the concentration of LPS. This observation highlights the complex relationship between LPS exposure and the body's antioxidant response. Despite some limitations, all the included studies were deemed credible. Subgroup evaluations revealed that the jejunum and duodenum has demonstrated stronger antioxidant capability compared to other tissues. Overall, our study presents compelling evidence that exposure to LPS induces significant OS in chickens. And we also found that the extent of OS was related to LPS doses, target tissues, and dietary ingredients.

SeNPs alleviates BDE-209-induced intestinal damage by affecting necroptosis, inflammation, intestinal barrier and intestinal flora in layer chickens

As environmental pollutants, polybrominated diphenyl ethers (PBDEs) can have toxic effects on living organisms and has a bioaccumulative effect. Low doses of selenium nanoparticles (SeNPs) can exert antioxidant, anti-inflammatory and anti-toxin functions on the organism. This experiment evaluated SeNPs' ability to prevent chicken's intestinal damage from decabromodiphenyl ether (BDE-209) exposure. Sixty layer chickens were separated into four groups at randomly and equally: Control group, SeNPs group (1 mg/kg SeNPs), BDE-209 group (400 mg/kg BDE-209), and BDE-209 +SeNPs group (400 mg/kg BDE-209 and 1 mg/kg SeNPs), for 42 days. The results showed that BDE-209 increased MDA content, decreased the activities of T-SOD, T-AOC, GSH and iNOS, up-regulated the expression of TNF-α, RIPK1, RIPK3 and MLKL, promoted the production of inflammatory factors, reduced the levels of tight junction proteins (Claudin-1, Occludin, ZO-1). SeNPs attenuated intestinal oxidative stress, necroptosis, inflammation and intestinal barrier damage caused by BDE-209. This protective effect is associated with the MAPK/NF-κB signaling pathway. Moreover, SeNPs restores flora alpha and beta diversity, improves intestinal flora composition and its abundance. It shifts the dysbiosis of intestinal flora caused by BDE-209 to normal. Overall, SeNPs can alleviate BDE-209-induced intestinal barrier damage and intestinal flora disorders, which are associated with intestinal oxidative stress, necroptosis and inflammation.

Dietary supplementation with Chinese herb ultrafine powder improves intestinal morphology and physical barrier function by altering jejunal microbiota in laying hens

Introduction

Chinese medicinal herbs play important roles in anti-inflammatory, antioxidant, and antibacterial activities. However, the effects of Chinese herb ultrafine powder (CHUP) on laying hens still need to be elucidated. Therefore, this study aimed to evaluate the effects of dietary CHUP supplementation on jejunal morphology, physical barrier function, and microbiota in laying hens.

Methods

A total of 576 Xinyang black-feather laying hens (300 days old) were randomly assigned into eight groups, with eight replicates per group and nine hens per replicate. The hens were fed a basal diet (control group) and a basal diet supplemented with 0.5% Leonuri herba (LH group), 0.25% Ligustri lucidi fructus (LF group), 0.25% Taraxaci herba (TH group), 0.5% LH + 0.25% LF (LH-LF group), 0.5% LH + 0.25% TH (LH-TH group), 0.25% LF + 0.25% TH (LF-TH group), and 0.5% LH + 0.25% LF + 0.25% TH (LH-LF-TH group), respectively, for 120 days.

Results

The results showed that dietary LH-LF and LH-LF-TH supplementation increased (p < 0.05) the jejunal villus height to crypt depth ratio of laying hens. Dietary LF-TH supplementation up-regulated jejunal claudin-5 expression, while LH supplementation up-regulated jejunal claudin-1 expression and increased the jejunal abundances of potentially beneficial bacteria related to short-chain fatty acids and bacteriocins production, such as Blautia, Carnobacterium, Clostridiales, and Erysipelotrichales (p < 0.05). In addition, dietary LH supplementation enriched (p < 0.05) the tetracycline biosynthesis, butirosin/neomycin biosynthesis, and D-arginine/D-ornithine metabolism, whereas steroid biosynthesis and limonene/pinene degradation were enriched (p < 0.05) in the LH-LF and LH-LF-TH groups. Moreover, Spearman's correlation analysis revealed the potential correlation between the abundance of the jejunal microbiota and jejunal morphology and the physical barrier function of laying hens.

Discussion

Collectively, these findings suggest that dietary CHUP supplementation could enhance the beneficial bacteria abundance, physical barrier function, and metabolic function associated with short-chain fatty acids and bacteriocins production. Moreover, combined supplementation of dietary CHUP showed better effects than the sole CHUP supplementation.

The positive effects of postbiotic (SWF concentration®) supplemented diet on skin mucus, liver, gut health, the structure and function of gut microbiota of common carp (Cyprinus carpio) fed with high-fat diet

Postbiotics are an emerging research interest in recent years, which shows that metabolites, lysate extracts, cell wall components and even culture supernatants of probiotics can also exhibit significant prebiotic effects. In this study postbiotic stress worry free concentration® (SWFC) were prepared from the composition of culture supernatant of Cetobacterium somerae and Lactococcus lactis. The positive effects of SWFC supplemented diets on the growth performance, skin mucus, liver and gut health, and intestinal microbiota profile of Cyprinus carpio fed with high fat diets were investigated. 180 C. carpio with an average body weight of (3.01 ± 0.01) g were selected and randomly divided into three groups. They were fed with one of the three experimental diets supplemented with SWFC of 0 (control), 0.2 and 0.3 g/kg for 98 days, afterwards indexes were detected. The results revealed that, addition of SWFC had no significant effect on growth performance of C. carpio, while it can improve the health of the fish remarkably. In addition, SWFC improved mucosal C3, T-AOC, SOD activities, and decreased lipid peroxidation product MDA level, which were notably better than those in the control group (P < 0.05). In terms of the liver health systems, C. carpio fed on the diet supplemented with 0.2 g/kg of SWFC, showed significant improvement of the liver injured by HFD and reduce the contents of serum ALT and AST, and liver TAG (P < 0.05; P < 0.01). The expression of inflammation-related and lipid synthesis genes revealed that SWFC0.2 group could noteworthy enhance antioxidant capacity, reduced the expression of pro-inflammatory factors (TNF-α, IL-1β) and lipid synthesis genes (ACC, FAS, PPAR-β, PPAR-γ), and up-regulated the expression of anti-inflammatory factors (TGF-β). Additionally, intestinal morphology arose inflammatory cell infiltration, while intestinal integrity was better in SWFC groups compared with the control. Furthermore, the contents of serum LPS and LBP were remarkably lower in the SWFC0.2 group compared with the control (P < 0.01). The mRNA expression of genes related to gut health indicated that SWFC supplementation noteworthy up-regulated the expression of antioxidant (Nrf2, CAT, GPX), immune (Hepcidin, IL-10) and tight junction protein-related (ZO-1, Occludin). Simultaneously, the results of GF-zebrafish showed that the relative expression of anti-inflammatory genes (IL-1β, TGF-β) and antioxidant related genes (Nrf2, HO-1) were significantly up-regulated in SWFC groups. Data on intestinal microbiota profile verified that, at the phylum level, the abundance of Fusobacteria was remarkably elevated in the SWFC groups (P < 0.05), whereas the abundance of Firmicutes was declined noteworthy in SWFC0.2 and SWFC0.3 compared to the control group (P < 0.05; P < 0.01) respectively. At the genus level, the abundance of Cetobacterium in the SWFC groups were notably higher than those in the control group (P < 0.05), while the Vibrio content in the SWFC groups was significantly decreased (P < 0.05). PCoA result indicated that the intestinal microflora of SWFC0.2 group was abundant and diverse. Our results elucidate that dietary supplementation of SWFC protects C. carpio from HFD induced inflammatory response and oxidative stress, ameliorate skin mucus, liver and gut health, and improve the gut microbiota balance. Therefore, SWFC could be considered as an improving-fish-health additive, when supplemented to aquatic animal feed. With regards to how SWFC regulates the immunity and inflammatory responses and which signal transductions are involved remains unclear and more scientific evidences are needed to address these issues.

Use of fermented Chinese medicine residues as a feed additive and effects on growth performance, meat quality, and intestinal health of broilers

Introduction

The purpose of this research was to investigate how dietary supplementation with fermented herbal residues (FCMR) affected birds' development capacity, quality of meat, gut barrier, and cecum microbiota.

Methods

540 cyan-shank partridge birds aged 47 days were chosen and divided into two groups of six replicates each and 45 birds for each replicate. The control group (CON) received a basal diet, while the trial group decreased a basic diet containing 5% FCMR.

Results and discussion

The findings revealed that the addition of FCMR decreased FCR and increased ADG in broilers (P < 0.05). Adding FCMR increased steaming loss in broiler chicken breasts (p < 0.05). Supplementation with FCMR significantly enhanced VH/CD and VH in the bird's intestine (jejunum, duodenum, and ileum) (p < 0.05). In addition, the addition of FCMR significantly down-regulated mRNA expression of INF-γ, IL-6, IL-1β, and TNF-α and up-regulated mRNA expression of ZO-1, Occludin, and Claudin (P < 0.05). Microbial 16S rDNA high-throughput sequencing study revealed that supplements with FCMR modified the cecum microbiota, and α-diversity analysis showed that supplementation with FCMR reduced the cecum bacterial abundance in broilers (P < 0.05). At the phylum level, the relative abundance of Spirochaetota increased considerably following FCMR supplementation (P < 0.05). The broiler cecum's close lot of Prevotellaceae_UCG-001 (P < 0.05), Desulfovibrio, Muribaculaceae, and Fusobacterium (p < 0.05) reduced when FCMR was supplemented. Supplementation with FCMR can promote growth capacity and maintain intestinal health in birds by enhancing gut barrier function and modulating the inflammatory response and microbial composition.

Artemisia ordosica polysaccharide ameliorated LPS-induced growth inhibition and intestinal injury in broilers through enhancing immune-regulation and antioxidant capacity

The study investigated the effects of dietary Artemisia ordosica polysaccharide (AOP) on growth, intestinal morphology, immune responses and antioxidant capacity of broilers challenged with lipopolysaccharide (LPS). A total of 192 1-d-old broilers were randomly allotted to four treatments with 6 replicates (n = 8): (1) CON group, non-challenged broilers fed basal diet; (2) LPS group, LPS-challenged broilers fed basal diet; (3) AOP group, non-challenged broilers fed basal diet supplemented with 750 mg/kg AOP; (4) LPS+AOP group, LPS-challenged broilers fed basal diet supplemented with 750 mg/kg AOP. The trial included starter phase (d 1 to 14), stress period Ⅰ (d 15 to 21), convalescence Ⅰ (d 22 to 28), stress period Ⅱ (d 29 to 35) and convalescence Ⅱ (d 36 to 42). During stress period Ⅰ and Ⅱ, broilers were injected intra-abdominally either with LPS solution or with equal sterile saline. The results showed that AOP alleviated LPS-induced growth inhibition by prompting protein digestibility, and decreasing serum stress hormones and pro-inflammatory cytokines content of broilers. Moreover, AOP decreased LPS-induced over-production of IL-1β and IL-6 through suppressing TLR4/NF-κB pathway, and alleviated LPS-induced decreasing of T-AOC, CAT and GPx activities by activating Nrf2/Keap1 pathway, which ultimately improved jejunum morphology. In conclusion, AOP alleviated LPS-induced growth inhibition and intestinal damage by enhancing anti-inflammatory and antioxidant capacities of broilers.

Effects of Dietary Ferulic Acid on Intestinal Health and Ileal Microbiota of Tianfu Broilers Challenged with Lipopolysaccharide

Lipopolysaccharide (LPS) has been considered the primary agent to establish animal models of inflammation, immunological stress, and organ injury. Previous studies have demonstrated that LPS impaired gastrointestinal development and disrupted intestinal microbial composition and metabolism. Ferulic acid (FA) isolated from multiple plants exhibits multiple biological activities. This study investigated whether FA ameliorated intestinal function and microflora in LPS-challenged Tianfu broilers. The results showed that LPS challenge impaired intestinal function, as evidenced by decreased antioxidant functions (p < 0.05), disrupted morphological structure (p < 0.05), and increased intestinal permeability (p < 0.05); however, these adverse effects were improved by FA supplementation. Additionally, FA supplementation preserved sIgA levels (p < 0.05), increased mRNA expression levels of CLDN and ZO-1 (p < 0.05), and enhanced epithelial proliferation (p < 0.05) in the ileal mucosa in LPS-challenged chickens. Moreover, FA supplementation rectified the ileal microflora disturbances in the LPS-challenged broilers. The results demonstrate that dietary FA supplementation decreased LPS-induced intestinal damage by enhancing antioxidant capacity and maintaining intestinal integrity. Furthermore, FA supplementation protects intestinal tight junctions (TJs), elevates secretory immunoglobulin A (sIgA) levels, and modulates ileal microflora composition in LPS-challenged broilers.

Compound probiotics can improve intestinal health by affecting the gut microbiota of broilers

Probiotics, as a widely used additive, have played a unique advantage in replacing antibiotic products. As a result, the probiotic effects on broiler development, intestinal flora, intestinal barrier, and immunity were assessed by this investigation. Four hundred and eighty 1-day-old Arbor Acres broilers were randomly allotted to 4 groups of 5 replicates with 24 broilers each. The control was fed only a basal corn-soybean meal diet. Probiotics I, probiotics II, and probiotics III were fed basal diet and 1, 5, and 10 g/kg compound probiotics (Lactobacillus casei: Lactobacillus acidophilus: Bifidobacterium = 1:1:2), respectively. We found that broilers in the compound probiotic group exhibited better growth performance and carcass characteristics compared with control, especially among probiotics III group. The intestinal barrier-related genes relative expression of Claudin, Occludin, MUC2, and ZO-1 mRNA in the probiotic group increased at 21 and 42 d compared with control, especially among probiotics III group (P < 0.05). The early gut immune-related genes (TLR2, TLR4, IL-1β, and IL-2) mRNA increased compared with control, while the trend at 42 d was completely opposite to that in the earlier stage (P < 0.05). Among them, probiotics III group showed the most significant changes compared to probiotics II group and probiotics I group. Select probiotics III group and control group for 16S rDNA amplicon sequencing analysis. The 16S rDNA amplicon sequencing results demonstrated that probiotics increased the relative abundance of beneficial microbes such as o_Bacteroidales, f_Rikenellaceae, and g_Alistipes and improved the cecum's gut microbiota of 42-day-old broilers. Additionally, adding the probiotics decreased the relative abundance of harmful microbes such as Proteobacteria. PICRUSt2 functional analysis revealed that most proteins were enriched in DNA replication, transcription, and glycolysis processes. Therefore, this study can provide theoretical reference value for probiotics to improve production performance, improve intestinal barrier, immunity, intestinal flora of broilers, and the application of probiotics.

New Baitouweng decoction combined with fecal microbiota transplantation alleviates DSS-induced colitis in rats by regulating gut microbiota metabolic homeostasis and the STAT3/NF-κB signaling pathway

AIM OF THE STUDY

We aimed to elucidate the synergistic effect and potential mechanism of New Baitouweng Decoction (NBD) combined with fecal microbiota transplantation (FMT) in rats with DSS-induced ulcerative colitis (UC).

MATERIALS AND METHODS

Colitis was induced by 5% (w/v) dextran sulfate sodium (DSS) in drinking water for 7 days. NBD or NBD combined with FMT were administered to the colitis rats. Body weight and disease activity index were measured, and the colon histological change was imaged to further examine the efficacy of NBD and FMT. The specific effects of NBD on STAT3/NF-κB signaling pathway and gut microbiota in rats with UC were also investigated.

RESULTS

The efficacy of NBD in combination with FMT was demonstrated by the lower disease activity index scores; increased tight junction proteins expression; and a lower expression of macrophage marker (F4/80) in colon tissues. NBD combined with FMT elevated the concentrations of short-chain fatty acids and inhibited activation of the JAK2/STAT3/NF-κB related proteins. Furthermore, 16SrDNA sequencing indicated that the gut microbiota in rats with UC was perturbed, in contrast to that in healthy rats. After treatment with NBD and FMT, the diversity and abundance of intestinal flora showed clear improvements. Spearman correlation analysis indicated a strong correlation between specific microbiota and fecal concentrations of acetate, propionate and butyrate.

CONCLUSIONS

The protective mechanism of NBD combined with FMT may be linked to regulation NF-κB/STAT3 and restoration of the intestinal flora.

Lactobacillus rhamnosus GG ameliorates DON-induced intestinal damage depending on the enrichment of beneficial bacteria in weaned piglets

BACKGROUND

Deoxynivalenol (DON) is one of the most common environmental pollutants that induces intestinal inflammation and microbiota dysbiosis. Lactobacillus rhamnosus GG (LGG) is a probiotic that not only has anti-inflammatory effects, but also shows protective effect on the intestinal barrier. However, it is still unknown whether LGG exerts beneficial effects against DON-induced intestinal damage in piglets. In this work, a total of 36 weaned piglets were randomized to one of four treatment groups for 21 d. The treatment groups were CON (basal diet); LGG (basal diet supplemented with 1.77 × 10¹¹ CFU/kg LGG); DON (DON-contaminated diet) and LGG + DON (DON-contaminated diet supplemented with 1.77 × 10¹¹ CFU/kg LGG).

RESULT

Supplementation of LGG can enhance growth performance of piglets exposed to DON by improving intestinal barrier function. LGG has a mitigating effect on intestinal inflammation induced by DON exposure, largely through repression of the TLR4/NF-κB signaling pathway. Furthermore, supplementation of LGG increased the relative abundances of beneficial bacteria (e.g., Collinsella, Lactobacillus, Ruminococcus_torques_group and Anaerofustis), and decreased the relative abundances of harmful bacteria (e.g., Parabacteroides and Ruminiclostridium_6), and also promoted the production of SCFAs.

CONCLUSIONS

LGG ameliorates DON-induced intestinal damage, which may provide theoretical support for the application of LGG to alleviate the adverse effects induced by DON exposure.

Chicken jejunal microbiota improves growth performance by mitigating intestinal inflammation

Background

Intestinal inflammation is prevalent in chicken, which results in decreased growth performance and considerable economic losses. Accumulated findings established the close relationship between gut microbiota and chicken growth performance. However, whether gut microbiota impacts chicken growth performance by lessening intestinal inflammation remains elusive.

Results

Seven-weeks-old male and female chickens with the highest or lowest body weights were significantly different in breast and leg muscle indices and average cross-sectional area of muscle cells. 16S rRNA gene sequencing indicated Gram-positive bacteria, such as Lactobacilli, were the predominant species in high body weight chickens. Conversely, Gram-negative bacteria, such as Comamonas, Acinetobacter, Brucella, Escherichia-Shigella, Thermus, Undibacterium, and Allorhizobium-Neorhizobium-Pararhizobium-Rhizobium were significantly abundant in low body weight chickens. Serum lipopolysaccharide (LPS) level was significantly higher in low body weight chickens (101.58 ± 5.78 ng/mL) compared with high body weight chickens (85.12 ± 4.79 ng/mL). The expression of TLR4, NF-κB, MyD88, and related inflammatory cytokines in the jejunum was significantly upregulated in low body weight chickens, which led to the damage of gut barrier integrity. Furthermore, transferring fecal microbiota from adult chickens with high body weight into 1-day-old chicks reshaped the jejunal microbiota, mitigated inflammatory response, and improved chicken growth performance.

Conclusions

Our findings suggested that jejunal microbiota could affect chicken growth performance by mitigating intestinal inflammation.

Quercetin Reduces Inflammation and Protects Gut Microbiota in Broilers

The aim of this study was to investigate the effects of quercetin on inflammatory response and intestinal microflora in broiler chicken jejuna. A total of 120 broiler chickens were allocated into 3 groups: saline-challenged broilers fed a basal diet (CTR group), lipopolysaccharide (LPS)-challenged broilers fed a basal diet (L group) and LPS-challenged broilers fed a basal diet supplemented with 200 mg/kg quercetin (LQ group). Our results showed that LPS significantly increased expression of tumor necrosis factor (TNF)-α, interleukin (IL)-1β, IL-6, IL-8, interferon (IFN)-γ, toll-like receptor (TLR)-4, Bax, Caspase-3 and diamine oxidase activity (DAO), and decreased expression of zona occludens-1 (ZO-1), Occludin and Bcl-2 in the jejunum, while dietary quercetin prevented the adverse effects of LPS injection. LPS injection significantly decreased the number of Actinobacteria, Armatimonadetes and Fibrobacteriae at the phylum level when compared to the CTR group. Additionally, at genus level, compared with the CTR group, the abundance of Halomonas, Micromonospora, Nitriliruptor, Peptococcus, Rubellimicrobium, Rubrobacter and Slaclda in L group was significantly decreased, while dietary quercetin restored the numbers of these bacteria. In conclusion, our results demonstrated that dietary quercetin could alleviate inflammatory responses of broiler chickens accompanied by modulating jejunum microflora.

Polysaccharides derived from Astragalus membranaceus and Glycyrrhiza uralensis improve growth performance of broilers by enhancing intestinal health and modulating gut microbiota

This study was conducted to investigate the effects of dietary supplementation of polysaccharides derived from Astragalus membranaceus and Glycyrrhiza uralensis on growth performance, intestinal health, and gut microbiota composition in broilers. A total of 480 one-day-old male Arbor Acres broilers were randomly divided into 4 treatments with 6 replicates comprising 20 broilers each. Treatments included: basal diet without antibiotics (CON); basal diet supplemented with 500 mg/kg terramycin calcium (ANT); basal diet supplemented with 300 mg/kg Astragalus membranaceus polysaccharides (APS); and basal diet supplemented with 150 mg/kg Glycyrrhiza uralensis polysaccharides (GPS). The results showed that ANT, AP,S and GPS supplementation significantly increased average daily gain (ADG) and decreased feed conversion ratio (FCR) of broilers from 1 to 42 d of age. At 42 d, serum immunoglobulin A (IgA), immunoglobulin M (IgM) and immunoglobulin G (IgG) levels of the APS and GPS group were notably higher than those of the CON group, while serum levels of tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), and interleukin-6 (IL-6) as well as diamine oxidase (DAO) activity in the APS and GPS group were obviously decreased. Moreover, diets supplemented with APS and GPS could significantly increase villus height (VH) and the ratio of villus height to crypt depth (VH/CD) and remarkably upregulated occludin, claudin-1 and mucin-2 (MUC2) mRNA expression in duodenum, jejunum, and ileum of broilers. In addition, 16S rRNA gene sequencing revealed that APS and GPS supplementation altered cecal microbial diversity and composition in broilers. Higher Shannon index was observed in the APS and GPS group compared with the CON group, while GPS supplementation could also increase Chao1 index and Observed species. The result of Principal coordinate analysis (PCoA) showed that microbial community in the CON, ANT, APS, and GPS group clustered separately. Notably, both APS and GPS supplementation significantly decreased the abundance of Bacteroidetes, Bacteroides, Faecalibacterium, Desulfovibrio, and Butyricicoccus, while increased the abundance of Firmicutes, Prevotella, Parabacteroides, Ruminococcus, and Alistipes. The correlation analysis showed that the changes in cecal microbial composition induced by dietary APS and GPS supplementation were closely associated with the alteration of the phenotype of broilers including ADG, FCR, TNF-α, IL-1β, IL-6, IgA, IgG, DAO, Occludin, Claudin-1, ZO-1, and MUC2. In conclusion, polysaccharides derived from Astragalus membranaceus and Glycyrrhiza uralensis could improve growth performance of broilers by enhancing intestinal health and modulating gut microbiota.

Influences of dietary Eucommia ulmoides leaf extract on the hepatic lipid metabolism, inflammation response, intestinal antioxidant capacity, intestinal microbiota, and disease resistance of the channel catfish (Ictalurus punctatus)

The purpose of the study was to investigate the effects of Eucommia ulmoides leaf extract (ELE) on the common occurrence of liver steatosis, chronic inflammation, oxidative stress, disturbance of gut microbiota, and disease susceptibility in high-fat diet-fed channel catfish. Channel catfish fed three diets, including a high-fat diet (11% crude fat) and ELE-supplemented diets containing 1‰ or 2‰ ELE for 4 weeks. The results showed the contents of liver triacylglycerol of 1‰ and 2‰ ELE groups were reduced, and ELE treatments decreased the expression of lipogenesis related genes (srebp-1c, pparγ, and acc-1), and increased the expression of lipolysis related genes (pparα). In addition, the supplementation of ELE improved the inflammatory response of the liver and intestine. ELE could improve the destruction of intestinal morphology structure and increase the expression level of hif-1a and tight junction proteins (Occludin, Claudin2, Claudin15). 2‰ ELE significantly enhanced the antioxidant capacity of intestine by increasing the activity of SOD enzyme. Moreover, the supplement of ELE significantly increased the abundance of Cetobacterium and Romboutsia (p < 0.05). Compared with the control group, the expression of immune factor nf-κb had a significant decrease, and il-1β showed a tendency to decrease in the ELE supplement groups after pathogenic bacteria challenge. In conclusion, the ELE alleviated fatty liver disease and inflammation response, improved the oxidative capacity and physiological structure of intestine, and improved the structure of intestinal microbiota and disease resistance in HFD-fed channel catfish.

Leonurine inhibits the TXNIP/NLRP3 and NF-κB pathways via Nrf2 activation to alleviate carrageenan-induced pleurisy in mice

Oxidative stress and inflammation play important roles in pleurisy. Leonurine (Leo) has been confirmed to exert antioxidative and antiinflammatory effects in many preclinical experiments, but these effects have not been studied in pleurisy. The aim of this study was to explore the therapeutic effect and mechanism of Leo in a carrageenan (CAR)-induced pleurisy model. In this study, we found that the increase of reactive oxygen species (ROS), myeloperoxidase (MPO), and malondialdehyde (MDA) and decrease of glutathione (GSH) induced by CAR could be reversed by the treatment of Leo. Leo effectively reduced the levels of proinflammatory cytokines interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α), and the percentages of mature macrophages and increased the levels of antiinflammatory cytokines (IL-10). Furthermore, Western blotting revealed that Leo significantly activated the Nrf2 pathway to restrain the thioredoxin-interacting protein/NOD-like receptor protein 3 (TXNIP/NLRP3) and nuclear factor kappa-B (NF-κB) pathways. However, the protective effect of Leo was significantly weakened in Nrf2-deficient mice. These results indicate that Leo confers potent protection against CAR-induced pleurisy by inhibiting the TXNIP/NLRP3 and NF-κB pathways dependent on Nrf2, which may serve as a promising agent for attenuating pleurisy.

Effects of novel microecologics combined with traditional Chinese medicine and probiotics on growth performance and health of broilers

In this study, we prepared a kind of novel microecologics, namely Chinese medicine-probiotic compound microecological preparation (CPCMP), which is composed of 5 traditional Chinese medicine herbs (Galla Chinensis, Andrographis paniculata, Arctii Fructus, Glycyrrhizae Radix, and Schizonepeta tenuifolia) fermented by Aspergillus niger and a kind of compound probiotics (Lactobacillus plantarum A37 and L. plantarum MIII). The effects of the CPCMP in broilers on growth performance, serum parameters, immune function, and intestinal health were investigated. A total of 450 one-day-old male Arbor Acres broilers were randomly divided into 6 treatment groups with 5 replicates, 15 birds per replicate. Treatments consisted of: blank control, CPCMP, positive control, commercial CPCMP, traditional Chinese medicine, and probiotics groups, which were birds fed with basal diet supplemented with no extra additives, 0.2% CPCMP, 0.0035% chlortetracycline, 0.2% commercially available CPCMP, 0.2% fermented traditional Chinese medicines, and 0.2% compound probiotics, respectively. CPCMP obviously increased the average body weight and average daily gain (P < 0.05, compared with any other group) and decreased the feed:gain ratio of broilers (P < 0.05, compared with the blank control, commercial CPCMP, traditional Chinese medicine, or probiotics group). Moreover, it significantly increased glutathione peroxidase and secretory immunoglobulin A levels and spleen/bursa indices (P < 0.05 for all, compared with the blank control, commercial CPCMP, traditional Chinese medicine, or probiotics group). Villus heights in duodenum, jejunum, and ileum were also elevated by CPCMP treatment (P < 0.05, compared with any other group). Furthermore, CPCMP substantially increased jejunal mRNA levels of occludin and zonula occludens-1 (P < 0.05, compared with the blank control, positive control, or probiotics group) and facilitated the growth and colonization of beneficial cecal bacteria, such as Olsenella, Barnesiella, and Lactobacillus. Overall results show that the CPCMP prepared in our work contributes to improving growth performance, serum parameters, immune function, and intestinal health of broilers and exerts synergistic effects of traditional Chinese medicines and probiotics to some extent. Our findings suggest that CPCMP is a promising antibiotic substitute in the livestock and poultry industry in the future.

Leonurine Preconditioning Attenuates Ischemic Acute Kidney Injury in Rats by Promoting Nrf2 Nuclear Translocation and Suppressing TLR4/NF-κB Pathway

Despite the precise mechanisms for renal ischemia/reperfusion (I/R)-induced acute kidney injury (AKI) are poorly understood, nuclear factor erythroid 2 related factor 2 (Nrf2) and Toll-like receptor 4 (TLR4) pathways were considered as the important targets. Leonurine (LEO) is a special alkaloid extracted from Chinese motherwort (Leonurus japonicus Houtt), which has an anti-inflammatory effect and reduces oxidative stress. We conducted the study to explore the efficacy of LEO against I/R-induced AKI in rats and further investigated the underlying mechanisms. Ischemic renal injury was induced by temporary vascular clamping for 45 min. We have measured the levels of inflammation-related biomarkers and antioxidative stress markers. Next, Western blot analysis and Real-time PCR were performed to analyze whether the Nrf2 and TLR4/nuclear factor-kappaB (NF-κB) pathways were involved in this process. We found that LEO pretreatment remarkably decreased serum creatinine and blood urea nitrogen (BUN) in I/R rats and attenuated acute tubular damage. In addition, LEO markedly increased the expression of antioxidant proteins and decreased the levels of inflammatory factors. Further study revealed that LEO promoted Nrf2 into the nucleus, promoted the expression of heme oxygenase-1 (HO-1) and quinone oxidoreductase 1 (NQO-1), and suppressed the TLR4/NF-κB signal pathway in kidney tissues of ischemic AKI rats. The study reveals that LEO has a protective effect to prevent ischemic AKI through activation of Nrf2 nuclear translocation resisting oxidative stress injury and inhibition of the TLR4/NF-κB pathway mediated inflammatory gene expression.

Effects of yeast hydrolysate supplementation on intestinal morphology, barrier, and anti-inflammatory functions of broilers

Objective

This study was conducted to evaluate the effects of dietary yeast hydrolysate (YH) supplementation on intestinal morphology, barrier, and anti-inflammatory functions of broilers.

Methods

A total of 320 one day old male broilers were randomly allocated into four groups with eight replicates of ten broilers each. The broilers were supplemented with a basal diet (the control group) or basal diets adding 50, 100, 150 mg/kg YH, respectively. This trial lasted for 42 days. The orthogonal polynomial contrasts were used to determine the linear and quadratic effects of increasing levels of YH.

Results

In our previous research, supplementing YH improved growth performance by enhancing body weight gain but decreased feed-to-gain ratio. In this study, compared with the control group, dietary YH addition linearly and quadratically decreased serum diamine oxidase activity (p<0.05). Additionally, supplementing YH linearly and/or quadratically decreased jejunal crypt depth (CD), tumor necrosis factor-alpha (TNF-α) concentration as well as mucin 2, interleukin-6 (IL-6), IL-1β, TNF-α, nuclear factor kappa B, and myeloid differentiation factor 88 gene expression levels (p<0.05). Whereas the jejunal villus height (VH), VH/CD, IL-10 concentration as well as zonula occludens-1 and IL-10 gene expression levels were linearly and/or quadratically increased by YH supplementation (p<0.05).

Conclusion

Dietary YH supplementation improved intestinal morphology, barrier and anti-inflammatory functions while decreased intestinal permeability of broilers, which might be related with altering pertinent genes expression. This study provides evidence of YH as a promising feed additive for broilers.

Selenomethionine alleviated fluoride-induced toxicity in zebrafish (Danio rerio) embryos by restoring oxidative balance and rebuilding inflammation homeostasis

Fish are target organisms that are extremely susceptible to fluoride pollution, and an increase in fluoride load will damage multiple systems of fish. Selenomethionine (Se-Met) at low levels has been reported to alleviate oxidative damage and inflammation caused by toxic substances, but whether it can alleviate fluoride-induced toxicity in zebrafish embryos has not been elucidated. In this study, the intervention effects of Se-Met on developmental toxicity, oxidative stress and inflammation in zebrafish embryos exposed to fluoride were determined. Our results showed that fluoride accumulated in larvae and induced developmental toxicity in zebrafish embryos, caused oxidative damage and apoptosis, increased significantly the MPO and LZM activities and the levels of the inflammation-related genes IL-1β, IL-6, TNF-α, IL-10 and TGF-β. Moreover, fluoride significantly increased the levels of ERK2, JNK, p38 and p65 in MAPKs and NF-κB pathways. Se-Met-treatment alleviated the adverse effects induced by fluoride, and all of the above indicators induced by fluoride returned to near control levels with increasing concentrations and time. However, treatment with Se-Met-alone also markedly increased the levels of IL-6, TNF-α, IL-10, TGF-β, ERK2 and JNK. In short, these data demonstrated that Se-Met-could alleviate fluoride-induced toxicity in zebrafish embryos by restoring oxidative balance and rebuilding inflammation homeostasis, although low levels of Se-Met-alone had certain toxic effects on zebrafish embryos. Taken together, Se-Met-plays an important role in preventing toxic damage induced by fluoride in zebrafish embryos, although it has certain toxic effects.

Progress on Gut Health Maintenance and Antibiotic Alternatives in Broiler Chicken Production

The perturbation of gut health is a common yet unresolved problem in broiler chicken production. Antibiotics used as growth promoters have remarkably improved the broiler production industry with high feed conversion efficiency and reduced intestinal problems. However, the misuse of antibiotics has also led to the increase in the development of antibiotic resistance and antibiotic residues in the meat. Many countries have enacted laws prohibiting the use of antibiotics in livestock production because of the increasing concerns from the consumers and the public. Consequently, one of the most significant discussions in the poultry industry is currently antibiotic-free livestock production. However, the biggest challenge in animal husbandry globally is the complete removal of antibiotics. The necessity to venture into antibiotic-free production has led researchers to look for alternatives to antibiotics in broiler chicken production. Many strategies can be used to replace the use of antibiotics in broiler farming. In recent years, many studies have been conducted to identify functional feed additives with similar beneficial effects as antibiotic growth promoters. Attention has been focused on prebiotics, probiotics, organic acids, emulsifiers, enzymes, essential oils, tributyrin, and medium-chain fatty acids. In this review, we focused on recent discoveries on gut health maintenance through the use of these functional feed additives as alternatives to antibiotics in the past 10 years to provide novel insights into the design of antibiotic-free feeds.

Alkaloid leonurine exerts anti-inflammatory effects via modulating MST1 expression in trophoblast cells

BACKGROUND

Pre-eclampsia (PE) is mainly attributed to the inflammation of trophoblast cells in pregnant women, which results in damage to the maternal organs and growth retardation of the fetus. Alkaloid leonurine (LNR) is a plant compound and has anti-inflammatory effects. Here we aimed to investigate the effects of LNR on human and mouse trophoblast cells and the underlying mechanisms.

METHODS

The levels of the inflammatory factors in trophoblast cells under lipopolysaccharides (LPS) stimulation were analyzed with ELISA. Western blot was employed to examine the protein expression. Trophoblast cells in Mammalian ste20-like kinase 1 (MST1-/- ) or wild type (WT) mice were isolated to examine the expression of signal molecules in the nuclear factor-κB (NF-κB) pathway. Concentration-dependent activity of NF-κB was examined. The regulation of LNR and MST1 in MST1-/- trophoblast cells was studied as well.

RESULTS

Our data showed that LNR exhibited anti-inflammatory effects and suppressed the NF-κB signaling by inhibiting LPS-induced inflammation in trophoblast cells. LNR upregulated the expression of MST1, and the anti-inflammatory role of LNR was greatly relieved in MST1-knockout trophoblast cells, although it displayed weak roles in NF-κB signaling.

CONCLUSION

LNR exhibits anti-inflammatory effects on human and mouse trophoblast cells by upregulating MST1 in the NF-κB signal pathway.

Chlorothalonil induces the intestinal epithelial barrier dysfunction in Caco-2 cell-based in vitro monolayer model by activating MAPK pathway

The widespread use of chlorothalonil (CTL) has caused environmental residues and food contamination. Although the intestinal epithelial barrier (IEB) is directly involved in the metabolism and transportation of various exogenous compounds, there are few studies on the toxic effects of these compounds on the structure and function of IEB. The disassembly of tight junction (TJ) is a major cause of intestinal barrier dysfunction under exogenous compounds intake, but the precise mechanisms are not well understood. Here, we used Caco-2 cell monolayers as an in vitro model of human IEB to evaluate the toxicity of CTL exposure on the structure and function of IEB. Results showed that CTL exposure increased the paracellular permeability of the monolayers and downregulated mRNA levels of the TJ genes (ZO-1, OCLN, and CLDN1), polarity marker gene (SI), and anti-apoptosis gene (BCL-2) but upregulated the mRNA levels of apoptosis-related genes, including BAD, BAX, CASP3, and CASP8. Western blot analysis and immunofluorescence assay results showed the decreased levels and disrupted distribution of TJ protein network, including ZO-1 and CLDN1 in CTL-exposed IEB. In addition, the accumulation of intracellular reactive oxygen species, decreased mitochondrial membrane potential, and increased active CASP3 expression were observed in treated IEB. The result of TUNEL assay further confirmed the occurrence of cell apoptosis after CTL exposure. In addition, the phosphorylation of mitogen-activated protein kinases, including ERK, JNK and p38, was increased in CTL-exposed IEB. In summary, our results demonstrated that CTL exposure induced IEB dysfunction in Caco-2 cell monolayers by activating the mitogen-activated protein kinase pathway.

Bisdemethoxycurcumin attenuates lipopolysaccharide-induced intestinal damage through improving barrier integrity, suppressing inflammation, and modulating gut microbiota in broilers

Bisdemethoxycurcumin has good antioxidant and anti-inflammatory effects and has been widely used as food and feed supplements in the form of curcuminoids. However, the beneficial effect of individual bisdemethoxycurcumin on preventing lipopolysaccharide (LPS)-induced inflamed intestinal damage is unclear. The present study aimed to investigate whether dietary bisdemethoxycurcumin supplementation could attenuate LPS-induced intestinal damage and alteration of cecal microbiota in broiler chickens. In total, 320 one-day-old male Arbor Acres broiler chickens with a similar weight were randomly divided into four treatments. The treatments were designed as a 2 × 2 factorial arrangement: basal diet (CON); 150 mg/kg bisdemethoxycurcumin diet (BUR); LPS challenge + basal diet (LPS); LPS challenge + 150 mg/kg bisdemethoxycurcumin diet (L-BUR). Results showed that dietary bisdemethoxycurcumin supplementation attenuated the LPS-induced decrease of average daily feed intake. LPS challenge compromised the intestinal morphology and disrupted the intestinal tight junction barrier. Dietary bisdemethoxycurcumin supplementation significantly increased villus length:crypt depth ratio and upregulated the mRNA expression of intestinal tight junction proteins. Moreover, a remarkably reduced mRNA expression of inflammatory mediators was observed following bisdemethoxycurcumin supplementation. The cecal microbiota analysis showed that bisdemethoxycurcumin supplementation increased the relative abundance of the genus Faecalibacterium while decreased the relative abundance of the genera Bacteroides and Subdoligranulum. In conclusion, dietary bisdemethoxycurcumin supplementation could counteract LPS-induced inflamed intestinal damage in broiler chickens by improving intestinal morphology, maintaining intestinal tight junction, downregulating pro-inflammatory mediators, and restoring cecal microbiota.

Enteromorpha prolifera polysaccharide-zinc complex modulates the immune response and alleviates LPS-induced intestinal inflammation via inhibiting the TLR4/NF-κB signaling pathway

Enteromorpha prolifera polysaccharide-zinc (EP-Zn), a kind of polysaccharide-zinc complex, has been shown to improve the immune response and reduce the inflammatory factors in weaned piglets. Yet, the molecular mechanism remains unclear. The present study was conducted to investigate the immunomodulating activity and anti-inflammatory mechanism of EP-Zn in mice. Different doses (350 mg kg^-1, 700 mg kg^-1, 1050 mg kg^-1 and 1400 mg kg^-1) of EP-Zn were administered to C57BL/6J mice for 28 days. The results showed that under physiological conditions, 350 mg kg^-1 EP-Zn stimulated cytokine (TNF-α, IL-1β, IL-6 and IL-10) secrection, regulated the intestinal microbiota, and reduced the levels of short-chain fatty acids (SCFAs) (acetic acid and propionic acid). In addition, in the LPS-induced inflammation model, EP-Zn pretreatment effectively alleviated LPS-induced shortening of colonic length and increased MPO and DAO contents, improved intestinal physical barrier function by modulating mucosal structure, and attenuated intestinal inflammation via inhibiting the TLR4/NF-κB signaling pathway. These findings suggested that EP-Zn exerted immunomodulatory and anti-inflammatory activities under physiological and inflammatory conditions, respectively.

Ageratina adenophora Disrupts the Intestinal Structure and Immune Barrier Integrity in Rats

The aim of this study was to investigate the effects of Ageratina adenophora on the intestines morphology and integrity in rat. Rats were randomly divided into two groups and were fed with 10 g/100 g body weight (BW) basal diet and 10 g/100 g BW experimental diet, which was a mixture of A. adenophora powder and basal diet in a 3:7 ratio. The feeding experiment lasted for 60 days. At days 28 and 60 of the experiment, eight rats/group/timepoint were randomly selected, weighed, and sacrificed, then blood and intestinal tissues were collected and stored for further analysis. The results showed that Ageratina adenophora caused pathological changes and injury in the intestine, elevated serum diamine oxidase (DAO), D-lactate (D-LA), and secretory immunoglobulin A (sIgA) levels, reduced occludin levels in intestinal tissues, as well as increased the count of intraepithelial leukocytes (IELs) and lamina propria leukocytes (LPLs) in the intestine (p < 0.05 or p < 0.01). In addition, the mRNA and protein (ELISA) expressions of pro-inflammation cytokines (IL-1β, IL-2, TNF-α, and IFN-ϒ) were elevated in the Ageratina adenophora treatment groups, whereas anti-inflammatory cytokines such as IL-4 and IL-10 were reduced (p < 0.01 or p < 0.05). Therefore, the results obtained in this study indicated that Ageratina adenophora impaired intestinal function in rats by damaging the intestine structure and integrity, and also triggered an inflammation immune response that led to intestinal immune barrier dysfunction.

Puerarin enhances intestinal function in piglets infected with porcine epidemic diarrhea virus

Puerarin has been reported to be an excellent antioxidant, anti-inflammatory and antimicrobial agent, but the potential effect of puerarin on porcine epidemic diarrhea virus (PEDV) is unclear. This study aimed to determine whether puerarin could alleviate intestinal injury in piglets infected with PEDV. A PEDV (Yunnan province strain) infection model was applied to 7-day-old piglets at 104.5 TCID50 (50% tissue culture infectious dose). Piglets were orally administered with puerarin at the dosage of 0.5 mg/kg body weight from day 5 to day 9. On day 9 of the trial, piglets were inoculated orally with PEDV. Three days later, jugular vein blood and intestinal samples were collected. Results showed puerarin reduced morbidity of piglets infected with PEDV. In addition, puerarin reduced the activities of aspartate aminotransferase and alkaline phosphatase, the ratio of serum aspartate aminotransferase to serum alanine aminotransferase, the number of white blood cells and neutrophils, and the plasma concentrations of interleukin-6, interleukin-8 and tumor necrosis factor-α, as well as protein abundances of heat shock protein-70 in PEDV-infected piglets. Moreover, puerarin increased D-xylose concentration but decreased intestinal fatty acid-binding protein concentration and diamine oxidase activity in the plasma of piglets infected with PEDV. Puerarin increased the activities of total superoxide dismutase, glutathione peroxidase and catalase, while decreasing the activities of myeloperoxidase and concentration of hydrogen peroxide in both the intestine and plasma of PEDV-infected piglets. Puerarin decreased mRNA levels of glutathione S-transferase omega 2 but increased the levels of nuclear factor erythroid 2-related factor 2. Furthermore, puerarin increased the abundance of total eubacteria (16S rRNA), Enterococcus genus, Lactobacillus genus and Enterobacteriaceae family in the intestine, but reduced the abundance of Clostridium coccoides in the caecum. These data indicate puerarin improved intestinal function in piglets infected by PEDV and may be a promising supplement for the prevention of PEDV infection.

Contributions of HO-1-Dependent MAPK to Regulating Intestinal Barrier Disruption

The mitogen-activated protein kinase (MAPK) pathway controls intestinal epithelial barrier permeability by regulating tight junctions (TJs) and epithelial cells damage. Heme oxygenase-1 (HO-1) and carbon monoxide (CO) protect the intestinal epithelial barrier function, but the molecular mechanism is not yet clarified. MAPK activation and barrier permeability were studied using monolayers of Caco-2 cells treated with tissue necrosis factor α (TNF-α) transfected with FUGW-HO-1 or pLKO.1-sh-HO-1 plasmid. Intestinal mucosal barrier permeability and MAPK activation were also investigated using carbon tetrachloride (CCl₄) administration with CoPP (a HO-1 inducer), ZnPP (a HO-1 inhibitor), CO releasing molecule 2 (CORM-2), or inactived-CORM-2-treated wild-type mice and mice with HO-1 deficiency in intestinal epithelial cells. TNF-α increased epithelial TJ disruption and cleaved caspase-3 expression, induced ERK, p38, and JNK phosphorylation. In addition, HO-1 blocked TNF-α-induced increase in epithelial TJs disruption, cleaved caspase-3 expression, as well as ERK, p38, and JNK phosphorylation in an HO-1-dependent manner. CoPP and CORM-2 directly ameliorated intestinal mucosal injury, attenuated TJ disruption and cleaved caspase-3 expression, and inhibited epithelial ERK, p38, and JNK phosphorylation after chronic CCl₄ injection. Conversely, ZnPP completely reversed these effects. Furthermore, mice with intestinal epithelial HO-1 deficient exhibited a robust increase in mucosal TJs disruption, cleaved caspase-3 expression, and MAPKs activation as compared to the control group mice. These data demonstrated that HO-1-dependent MAPK signaling inhibition preserves the intestinal mucosal barrier integrity by abrogating TJ dysregulation and epithelial cell damage. The differential targeting of gut HO-1-MAPK axis leads to improved intestinal disease therapy.

Redox Homeostasis in Poultry: Regulatory Roles of NF-κB

Redox biology is a very quickly developing area of modern biological sciences, and roles of redox homeostasis in health and disease have recently received tremendous attention. There are a range of redox pairs in the cells/tissues responsible for redox homeostasis maintenance/regulation. In general, all redox elements are interconnected and regulated by various means, including antioxidant and vitagene networks. The redox status is responsible for maintenance of cell signaling and cell stress adaptation. Physiological roles of redox homeostasis maintenance in avian species, including poultry, have received limited attention and are poorly characterized. However, for the last 5 years, this topic attracted much attention, and a range of publications covered some related aspects. In fact, transcription factor Nrf2 was shown to be a master regulator of antioxidant defenses via activation of various vitagenes and other protective molecules to maintain redox homeostasis in cells/tissues. It was shown that Nrf2 is closely related to another transcription factor, namely, NF-κB, responsible for control of inflammation; however, its roles in poultry have not yet been characterized. Therefore, the aim of this review is to describe a current view on NF-κB functioning in poultry with a specific emphasis to its nutritional modulation under various stress conditions. In particular, on the one hand, it has been shown that, in many stress conditions in poultry, NF-κB activation can lead to increased synthesis of proinflammatory cytokines leading to systemic inflammation. On the other hand, there are a range of nutrients/supplements that can downregulate NF-κB and decrease the negative consequences of stress-related disturbances in redox homeostasis. In general, vitagene-NF-κB interactions in relation to redox balance homeostasis, immunity, and gut health in poultry production await further research.

Baitouweng Decoction Ameliorates Ulcerative Colitis in Mice Partially Attributed to Regulating Th17/Treg Balance and Restoring Intestinal Epithelial Barrier

Ulcerative colitis (UC) is a chronic intestinal disease with unclear pathogenesis. With an increasing global prevalence over the past two decades, UC poses a serious threat to public health. Baitouweng decoction (BTW), a traditional Chinese medicine, has been shown to have good clinical efficacy for treating intestinal inflammation. Yet, the efficacy of BTW in UC and the underlying mechanism remain unclear. The current study aimed to determine whether BTW suppressed intestinal inflammation in mice and the potential mechanism. We used a dextran sulfate sodium (DSS)-induced murine colitis model to test the anti-inflammatory efficacy of BTW. Clinical symptoms were scored by the disease activity index (DAI), and the colon length and pathological changes in colon tissue were also used to further evaluate the efficacy of BTW. Precisely how BTW affected immune function and the intestinal barrier of UC mice was also examined. BTW significantly reduced DAI score and colonic pathological damage. BTW regulated the balance between T helper (Th)17 and regulatory T (Treg) cells, decreased interleukin (IL)-1β, IL-6, and tumor necrosis factor-α, and increased IL-10 levels. BTW reduced intestinal permeability of UC mice, increased expression of tight junction proteins (occludin and zonula occludens-1), and decreased expression of phospho-nuclear factor (p-NF)-κB and phospho-extracellular signal-regulated kinase (p-ERK) in the colon. BTW inhibited the ERK/p-NF-κB signaling pathway and suppressed expression of cyclo-oxygenase-2 and inducible NO synthase in lipopolysaccharide-activated RAW 264.7 cells. BTW significantly promoted the synthesis of short-chain fatty acids in the gut, particularly acetate, propionate, isobutyric acid, and isovalerate. The results suggest that BTW can protect against DSS-induced UC. The mechanism may be partially attributed to regulating the balance of Th17/Treg cells and restoring the intestinal epithelial barrier.

Effects of dietary pyrroloquinoline quinone disodium supplementation on inflammatory responses, oxidative stress, and intestinal morphology in broiler chickens challenged with lipopolysaccharide

This study was conducted to investigate the effects of pyrroloquinoline quinone disodium (PQQ·Na2) on inflammatory responses, oxidative stress, and intestinal morphology of broiler chickens challenged with lipopolysaccharide (LPS). A 2 × 2 factorial arrangement in a complete randomized design experiment was used to study the effect of dietary PQQ·Na2 (0 or 1 mg/kg) on broiler chickens with or without a challenge with LPS. A total of two hundred eighty-eight 1-day-old Arbor Acre broiler chickens were randomly assigned to 4 treatments with 6 replicate cages of 12 birds per cage. All experimental broilers were injected intraperitoneally with 0.5 mg/kg body weight of either Escherichia coli LPS or sterile saline at 16, 18, and 20 d of age. Results showed that injecting LPS significantly increased the concentrations of interleukin-1beta (IL-1β) in serum of birds on day 20 and day 21. Meanwhile, LPS injection increased (P < 0.05) the relative mRNA expression of interleukin-6 (IL-6) in the duodenal mucosa of broilers on day 21. However, dietary supplementation with PQQ·Na2 decreased (P < 0.05) the concentration of IL-6 in serum of birds on day 20 and the levels of IL-1β, IL-6, and interleukin-10 (IL-10) in serum of broiler chickens on day 21. Besides, supplementation of PQQ·Na2 within diet decreased (P < 0.05) the mRNA expressions of IL-1β and IL-10 in the duodenal mucosa of birds on day 20. Relative to saline injection, the activity of glutathione peroxidase (GSH-Px) in serum and the activities of total superoxide dismutase (T-SOD) and catalase (CAT) in liver were found to be lower (P < 0.05) in broilers after LPS challenge on day 21. However, birds fed with PQQ·Na2 showed higher (P < 0.05) GSH-Px activity in serum and higher (P < 0.05) T-SOD activities in liver on day 21 and day 42. Pyrroloquinoline quinone disodium also significantly attenuated the LPS-induced decreases in villus height to crypt depth ratio in the duodenum of broilers. In conclusion, dietary PQQ·Na2 supplementation significantly exerted protective effects on inflammation damage and oxidant stress of broilers under LPS challenge by regulating the expression of inflammatory cytokines (IL-1β, IL-6, and IL-10) and activities of antioxidant enzymes (GSH-Px, T-SOD, and CAT). Moreover, dietary PQQ·Na2 supplementation significantly ameliorated the LPS-impaired intestinal morphology in broilers. Therefore, it has been considered that PQQ·Na2 can be used as a potential feed additive in broiler production.

MiR-196-5p involvement in selenium deficiency-induced immune damage via targeting of NFκBIA in the chicken trachea

Dietary selenium (Se) deficiency can induce multifarious immune injury in tissues, accompanied by inflammation and a decreased expression of selenoproteins. The results of previous studies indicated that these issues are associated with Se-mediated microRNAs involved in immune regulation, although the specific mechanisms associated with these interactions have not been reported in the trachea of chickens. To explore the effects of Se deficiency in the trachea of chickens and the role of miR-196-5p, we established correlational models of tracheal injury in chickens. One hundred broilers were divided into four groups, including a control group (C group), a Se deficient group (L group), a lipopolysaccharide (LPS)-induced control group (C + LPS group) and a LPS-induced Se deficient group (L + LPS group). Light microscopy observations indicated that the infiltration of inflammatory cells was the major histopathological change caused by Se deficiency. Furthermore, ultrastructural observation of the tracheal epithelium and ciliary showed typical inflammatory signs owing to Se deficiency. We determined the targeting relationship between miR-196-5p and NFκBIA by bioinformatics analysis. In the case of Se deficiency, the changes were detected as follows: 19 selenoproteins showed different degrees of decrease (p < 0.05). Significant inhibition of both antimicrobial peptides and immunoglobulin production were observed (p < 0.05). IκB-α (NFκBIA) expression degraded with the increasing miR-196-5p (p < 0.05), and the NF-κB pathway was activated. Thereafter, we can see a significant increase in the mRNA levels of inflammatory cytokines-related genes (tumor necrosis factor (TNF)-α, inducible nitric oxide synthase (iNOS), cyclooxygenase (COX)-2, prostaglandin E (PTGE), interleukin (IL)-1β, IL-6) and protein expression of NF-κB/iNOS pathway-related genes (NF-κB, iNOS, TNF-α, COX-2) (p < 0.05). The release of IL-2, interferon (IFN)-γ inhibited (p < 0.05) and the secretion of IL-4, IL-6 increased, suggesting the imbalance of Th1/Th2 (Th, helper T cell) cytokines. Compared to the control, the mRNA and protein expression levels of the anti-inflammatory system components with antioxidant activity (PPAR-γ/HO-1) were in an inhibitory state (p < 0.05). Antioxidases (SOD, CAT, GSH-Px) activities were suppressed. The activities of the peroxide markers (MDA, H₂O₂) were enhanced (p < 0.05). In addition, Se deficiency had a positive effect on the pathological changes of inflammation and the exceptional immunity in LPS-treated groups (p < 0.05). The results confirmed the relationship between miR-196-5p and NFκBIA in chickens, revealing that Se deficiency causes respiratory mucosal immune dysfunction via the miR-196-5p-NFκBIA axis, oxidative stress and inflammation. Moreover, Se deficiency exacerbates the inflammatory damage stimulated by LPS. Our work provides a theoretical basis for the prevention of tracheal injury owing to Se deficiency and can be used as a reference for comparative medicine. Furthermore, the targeted regulation of miR-196-5p and NFκBIA may contribute to the protection of the tracheal mucosa in chickens.

Bombyx mori gloverin A2 alleviates enterotoxigenic Escherichia coli-induced inflammation and intestinal mucosa disruption

Background

Enterotoxigenic Escherichia coli (ETEC) is one of the leading bacterial causes of intestinal inflammation and diarrhea. However, the ETEC is frequently resistant to common antibiotics. In this study, we explored the role of a novel antibacterial peptide Bombyx mori gloverin A2 (BMGlvA2) in alleviating ETEC-induced inflammation and intestinal epithelium disruption in mice.

Methods

An ETEC-challenged mice model was used, and the ETEC-challenged mice and non-challenged mice were treated by the BMGlvA2 at different doses.

Results

ETEC challenge not only elevated the concentrations of serum inflammatory cytokines such as the IL-6 and TNF-α (P < 0.01), but also elevated the concentrations of serum creatinine and urea (P < 0.05). However, BMGlvA2 attenuated the inflammatory responses by decreasing the serum inflammatory cytokines and improving the metabolisms in ETEC-challenged mice, and alleviated the ETEC-induced tissue damage in spleen. Moreover, BMGlvA2 treatment significantly elevated the duodenum villus height and decreased the crypt depth in the duodenum and ileum in ETEC-challenged mice (P < 0.05). Interestingly, BMGlvA2 improved the distribution and abundance of tight-junction protein ZO1 in duodenum and ileum epithelium after ETEC-challenge. Moreover, BMGlvA2 significantly down-regulated the expression levels of inflammatory cytokines (IL-1β, IL-6, and TNF-α) and the apoptosis-related genes (Caspase 8 and Caspase 9) in jejunal mucosa (P < 0.05) in the TETC-challenged mice. Importantly, BMGlvA2 significantly elevated the expression levels of critical genes related to mucosal barrier functions such as the mucins (MUC1 and MUC2) and glucose transporter (GLUT2) in the intestinal mucosa (P < 0.05).

Conclusion

Our results suggested a novel function of the conventional antibacterial peptides, and the anti-bacterial and anti-inflammatory properties of BMGlvA2 may allow it a potential substitute for conventionally used antibiotics or drugs.

Dietary Stevioside Supplementation Alleviates Lipopolysaccharide-Induced Intestinal Mucosal Damage through Anti-Inflammatory and Antioxidant Effects in Broiler Chickens

The study was conducted to investigate the effects of dietary stevioside (STE) supplementation on the lipopolysaccharide (LPS)-induced intestinal mucosal damage of broiler chickens. A total of 192 one-day-old male Ross 308 broiler chicks were randomly divided into four treatments: (1) basal diet (CON); (2) basal diet supplemented with 250 mg/kg stevioside (STE); (3) basal diet + LPS-challenge (LPS); (4) basal diet supplemented with 250 mg/kg stevioside + LPS-challenge (LPS + STE). LPS-challenged groups received an intraperitoneal injection of LPS at 17, 19 and 21 d, whereas the CON and STE groups received a saline injection. The results showed that dietary STE supplementation normalized LPS-induced changes in protein expression of p-NF-κB and p-IκBα, mRNA expression of inflammatory genes (TLR4, NF-κB, and IFN-γ), tight junction-related genes (CLDN2, OCLN, and ZO-1), and antioxidant genes (Nrf2 and HO-1). LPS-induced decreases in serum diamine oxidase (DAO) level, villus height-to-crypt depth ratio, apoptotic index, and protein expression of proliferating cell nuclear antigen (PCNA) were reversed with dietary STE supplementation. Additionally, STE supplementation ameliorated the redox damage by reducing malondialdehyde (MDA) content and increasing total antioxidant capacity (T-AOC) and antioxidant enzyme activity. In conclusion, dietary stevioside supplementation could alleviate LPS-induced intestinal mucosal damage through anti-inflammatory and antioxidant effects in broiler chickens.

Propofol attenuated TNF-α-modulated occludin expression by inhibiting Hif-1α/ VEGF/ VEGFR-2/ ERK signaling pathway in hCMEC/D3 cells

Background

The levels of tight junction proteins (TJs), especially occludin, correlate with blood-brain barrier (BBB) disruption caused by inflammation in central nervous system (CNS). It has been reported that propofol, the most commonly used anesthetic, could inhibit inflammation response in CNS. In this study, we investigated the effects of tumor necrosis factor-α (TNF-α) and propofol on occludin expression in human cerebral microvascular endothelial cell line, D3 clone (hCMEC/D3 cells), and explored the underlying mechanisms.

Methods

The hCMEC/D3 cells were treated with propofol, followed by TNF-α. The expression and phosphorylation of Hif-1α, VEGF, VEGFR-2, ERK, p38MAPK and occludin were measured by Western blot analysis. The cell viability of hCMEC/D3 cells was measured by cell counting kit-8.

Results

TNF-α (10 ng/ml, 4 h) significantly decreased the expression of occludin, which was attenuated by propofol (25 μM). TNF-α induced Hif-1α/VEGF/VEGFR-2/ERK signaling pathway, while propofol could inhibit it. TNF-α induced the phosphorylation of p38MAPK, while propofol had no effect on it. In addition, the inhibitors of Hif-1α, VEGFR-2, and ERK could reduce the effect of TNF-α on occludin expression.

Conclusion

TNF-α could decrease the expression of occludin via activating Hif-1α/ VEGF/ VEGFR-2/ ERK signaling pathway, which was attenuated by propofol.

Electronic supplementary material

The online version of this article (10.1186/s12871-019-0788-5) contains supplementary material, which is available to authorized users.

Dietary l-tryptophan alleviated LPS-induced intestinal barrier injury by regulating tight junctions in a Caco-2 cell monolayer model

The intestinal epithelial layer forms a barrier through cell-cell tight junctions and breaking or even slightly disrupting this barrier can lead to serious pathological consequences, including infection and inflammation. Various amino acids have been shown to improve the intestinal tract, but the effect of tryptophan on the intestinal barrier has been controversial. Here, an in vitro Caco-2 cell model was built to investigate the protective and reparative effects of different concentrations of dietary l-Tryptophan (l-Trp) on lipopolysaccharide (LPS)-induced intestinal tight junction injury. Lower concentrations (40 μM) of dietary l-Trp protected and repaired the integrity and permeability injury of the intestinal tight junction induced by LPS, while high concentrations (80 μM) may not have a positive effect. LPS-induced injury led to increased (P < 0.05) mRNA expression of Nuclear factor-kappa B (NFκB) and Myosin light-chain kinase (MLCK), and decreased (P < 0.05) the mRNA expression of extracellular regulated protein kinase 1/2 (ERK1/2) and Mitogen-activated protein (MAP), and the treatment of dietary l-Trp alleviated those regulations in different concentrations, which suggests that dietary l-Trp may attenuate LPS-induced injury to tight junctions via inhibiting the NFκB-MLCK signaling pathway and activating the ERK1/2-MAP signaling pathway. And the mRNA and protein expressions of claudin-1, occludin and ZO-1 in LPS-induced injury were all down-regulated to varying degrees, and dietary l-Trp weakened the down-regulation of claudin-1 (P < 0.05) with no significant regulation of the protein expression of occludin and ZO-1 (P > 0.05).