Fish oil enhances intestinal integrity and inhibits TLR4 and NOD2 signaling pathways in weaned pigs after LPS challenge

Morchella importuna Flavones Improve Intestinal Integrity in Dextran Sulfate Sodium-Challenged Mice

Morchella importuna, as an edible fungus, has various health benefits. However, the effects of M. importuna on intestinal health are rarely investigated. Hence, this study aims to ascertain the influences of flavones from the fruiting bodies of M. importuna (hereinafter abbreviated as MIF) on dextran sulfate sodium (DSS)-induced damage to intestinal epithelial barrier in C57BL/6J mice. In this (14-day) study, 144 C57BL/6J mice were divided into four groups: (1) Control; (2) DSS treatment; (3) DSS treatment + 100 mg/kg MIF (LMIF); (4) DSS treatment + 200 mg/kg MIF (HMIF). On days 8-14, mice in the challenged groups were challenged with 3.5% DSS, while the control group received an equal volume of normal saline. Then, serum and intestinal samples were obtained from all mice. The results showed that MIF ingestion enhanced intestinal integrity in DSS-challenged mice, as evinced by the elevated (p < 0.05) abundances of occludin, claudin-1, and zonula occludens-1 proteins. Meanwhile, MIF ingestion reduced (p < 0.05) the colonic interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α), and interferon-γ (IFN-γ) concentrations and increased the superoxide dismutase and catalase activities and Shannon and Simpson indices in DSS-challenged mice. Moreover, MIF ingestion reduced (p < 0.05) the abundance of phospho-nuclear factor (NF)-κB and increased the abundance of phospho-Nrf2 in DSS-challenged mice. Taken together, MIF protects against intestinal barrier injury in C57BL/6J mice via a mechanism that involves inhibiting NF-κB activation and promoting Nrf2 activation, as well as regulating intestinal microbiota.

Orally Administered DHA-Enriched Phospholipids and DHA-Enriched Triglyceride Relieve Oxidative Stress, Improve Intestinal Barrier, Modulate Inflammatory Cytokine and Gut Microbiota, and Meliorate Inflammatory Responses in the Brain in Dextran Sodium Sulfate Induced Colitis in Mice

SCOPE

Studies based on DHA/EPA supplementation in animal models of inflammatory bowel disease (IBD) reveal controversial results. It is speculated that different forms of DHA may explain the controversial results. Therefore, the effects of DHA-enriched phospholipids (DHA-PL) and DHA-enriched triglyceride (DHA-TG) on IBD are compared.

METHODS AND RESULTS

Male C57BL6/J mice are given DHA-PL and DHA-TG for 14 consecutive days, and receive ad libitum a 3.0% dextran sodium sulfate solution on the eighth day to establish IBD model. The results show that both DHA-PL and DHA-TG can reverse the colitis pathological process by decreasing the disease activity indexes (DAI), raising the colon length, suppressing the intestinal permeability, suppressing the oxidative stress, down-regulating pro-inflammatory factors, up-regulating anti-inflammatory factor in colon tissues. DHA-PL and DHA-TG also regulate the composition of gut microbiota via decreasing of the abundance Bacteroidetes and Firmicutes, and DHA-TG increases the abundance of Odoribacter. Importantly, DHA-PL and DHA-TG obviously attenuate the activation of microglia.

CONCLUSIONS

DHA-PL shows outstanding advantages in regulating oxidative stress, inflammatory responses, and intestinal barrier permeability. The current research indicates that the existence of DHA affects the improvement, DHA in phospholipid form could be a more effective choice for nutritional intervention to prevent and treat colitis.

Resveratrol protects intestinal integrity, alleviates intestinal inflammation and oxidative stress by modulating AhR/Nrf2 pathways in weaned piglets challenged with diquat

This study investigated the effects of resveratrol (RES) on intestinal morphology, antioxidant capacity, intestinal inflammation, and barrier function in weaned piglets challenged with diquat (DIQ). Thirty weaned piglets were randomly assigned to 5 treatments: non-challenged group (CON), DIQ-challenged group (DIQ), and DIQ-challenged group with 10, 30, or 90 mg/kg of RES, respectively. The trail lasted 21 days, and piglets were intraperitoneally injected with DIQ or the same amount of saline on day 15. The results showed that supplementation with 90 mg/kg RES increased (P < 0.05) jejunal villus height and villus height: crypt depth ratio, and decreased (P < 0.05) crypt depth, plasma D-lactate and diamine oxidase (DAO) compared with the DIQ group. Piglets fed with 30 or 90 mg/kg RES prevented the diquat-induced decrease (P < 0.05) of mRNA expression of occludin, claudin-1, ZO-1, and IL-10, and increase (P < 0.05) of TNF-α mRNA expression. Moreover, addition of 90 mg/kg RES increased (P < 0.05) the activities of SOD, GSH-Px, and CAT and decreased (P < 0.05) the MDA levels in jejunal mucosa compared with the DIQ group. Finally, addition of 90 mg/kg RES enhanced (P < 0.05) the mRNA expression of SOD1, SOD2, CAT, GPx1, and HO-1, and increased (P < 0.05) mRNA and protein expression of Nrf2, NQO1, aryl hydrocarbon receptor (AhR), and cytochrome P450 family 1 member A1 (CYP1A1). These data indicated that supplementation with 90 mg/kg RES was effective in protecting the intestinal integrity, alleviating intestinal inflammation and oxidative stress by activating AhR/Nrf2 pathways in diquat-challenged piglets.

Clostridium butyricum Helps to Alleviate Inflammation in Weaned Piglets Challenged With Enterotoxigenic Escherichia coli K88

Background: Whether the probiotic Clostridium butyricum (CB) alleviates enterotoxigenic Escherichia coli (ETEC) K88-induced inflammation by regulating the activation of the toll-like receptor (TLR) signaling pathway is not clear, thus, we carried out this study. A total of 72 piglets (average body weight 7.09 ± 0.2 kg) were randomly divided into three groups of 24 piglets per group. Pigs were either fed a daily diet (NC, negative control), a diet tested every day by 1 × 10⁹ CFU/mL ETEC K88 (PC, positive control), or a basal diet supplemented with 5 × 10⁵ CFU/g CB and challenged with ETEC K88 (PC + CB group).

Results: Our results showed that CB pretreatment attenuated the effect of ETEC K88 by decreasing C-reactive protein (CRP), which resulted in tumor necrosis factor alpha (TNF-α) and interleukin-6 (IL-6) production. Histological examination revealed that CB pretreatment alleviated intestinal villi injury caused by ETEC K88 challenge. Furthermore, CB pretreatment promoted mRNA expression of the negative regulators of TLR signaling, including myeloid differentiation factor (MyD88), toll-interacting protein (Tollip), and B cell CLL/lymphoma 3 (Bcl-3), in the intestines of ETEC K88-challenged piglets. ETEC K88-induced activation of nuclear factor kappa B (NF-κB) and nuclear factor of kappa light polypeptide gene enhancer in B cells inhibitor alpha (IκBα) was attenuated by CB pretreatment.

Conclusion: These findings indicate that CB helps to maintain and strengthen the shape of intestinal villi and limits detrimental inflammatory responses, partly by inhibiting toll-like receptor 2 (TLR-2), toll-like receptor 4 (TLR-4), and toll-like receptor 5 (TLR-5) expression and inhibiting NF-κB p65, and promoting IκBα activation and synergism among its negative regulators.

Dietary Ursolic Acid Prevents Alcohol-Induced Liver Injury via Gut-Liver Axis Homeostasis Modulation: The Key Role of Microbiome Manipulation

Ursolic acid (UA), a natural triterpenoid widely distributed within fruits and edible plants, has been proven to relieve alcoholic liver disease (ALD). However, the mechanisms involved largely remain unclear. This study investigated whether the beneficial effects of UA on ALD could be related to gut-liver axis (GLA) modulation. Special attention was paid to the contribution of gut microbiome manipulation. UA ameliorated intestinal oxidative stress and barrier dysfunction induced by alcohol. As a consequence of gut leakiness amelioration, the related endotoxemia-mediated liver toll-like receptor 4 pathway induction and the subsequent reactive oxygen species overproduction were reverted. UA also counteracted alcohol-induced gut dysbiosis. A fecal microbiota transplantation study indicated that liver injury as well as ileum oxidative stress and gut barrier dysfunction of recipient mice were partly ameliorated as a result of microbiome remodeling. These results suggest that dietary UA alleviates ALD through GLA homeostasis modulation. Gut microbiome manipulation contributes to the hepatoprotective activity and GLA modulating effect of UA.

Protective Effect of Zinc Oxide and Its Association with Neutrophil Degranulation in Piglets Infected with Porcine Epidemic Diarrhea Virus

Porcine epidemic diarrhea virus (PEDV) has reemerged throughout the world in the past ten years and caused huge economic losses to the swine industry. No drugs are available to prevent or treat PEDV infection in piglets. Zinc oxide (ZnO) has been shown to reduce diarrhea. However, little is known about its role in PEDV infection. In this study, twenty-four 7-day-old piglets were randomly divided into three treatment groups: control, PEDV, and ZnO+PEDV. Piglets in the ZnO+PEDV group were orally administered with 100 mg/kg·BW ZnO and then inoculated PEDV at a dose of 10^4.5 TCID₅₀ (50% tissue culture infectious dose) per pig. Growth performance, histologic lesions, viral load, indicators of intestinal damage, inflammation, and oxidative stress were recorded or detected to determine the effect of ZnO on PEDV infection. And the underlying mechanisms were revealed by microarray and proteomic analyses. Results showed that ZnO administration mitigated diarrhea and the reduction of average daily weight gain induced by PEDV infection. ZnO could inhibit PEDV replication in the small intestine and colon. Both villus height and crypt depth were affected by PEDV infection in the duodenum and jejunum, which could be rescued by ZnO administration. Moreover, the activity of catalase was decreased both in plasma and intestine after PEDV infection, while increased in the intestine by ZnO administration. PEDV infection also significantly increased the concentration of H₂O₂ in jejunal and ileum and decreased the activity of total superoxide dismutase and glutathione peroxidase in plasma, whereas ZnO administration obviously increased the activity of total superoxide dismutase and decreased the concentration of H₂O₂ in the ileum. The concentrations of IL-1β, IL-6, and IL-8 in the plasma were all decreased upon ZnO administration. A large number of differentially expressed genes and proteins were identified in the ileum among the three groups by microarray and proteomic analyses. Gene Ontology and Reactome pathway analyses indicated that neutrophil degranulation and nutrient metabolism were the main biological process and pathways in both PEDV infection and ZnO administration. Overall, ZnO administration could improve growth performance, intestinal redox status, morphology, and function and reduce diarrhea in PEDV-infected piglets; ZnO could exert antiviral and anti-inflammatory effects on PEDV-infected piglets probably through regulating neutrophil degranulation. Our findings have important implications in piglet and infant nutrition.

Mechanisms of Epidermal Growth Factor Effect on Animal Intestinal Phosphate Absorption: A Review

Phosphorus is one of the essential mineral elements of animals that plays an important role in animal growth and development, bone formation, energy metabolism, nucleic acid synthesis, cell signal transduction, and blood acid–base balance. It has been established that the Type IIb sodium-dependent phosphate cotransporters (NaPi-IIb) protein is the major sodium-dependent phosphate (Pi) transporter, which plays an important role in Pi uptake across the apical membrane of epithelial cells in the small intestine. Previous studies have demonstrated that epidermal growth factor (EGF) is involved in regulating intestinal Pi absorption. Here we summarize the effects of EGF on active Pi transport of NaPi-IIb under different conditions. Under normal conditions, EGF inhibits the active transport of Pi by inhibiting the expression of NaPi-IIb, while, under intestinal injury condition, EGF promotes the active absorption of Pi through upregulating the expression of NaPi-IIb. This review provides a reference for information about EGF-regulatory functions in Pi absorption in the animal intestine.

Dietary turmeric (Curcuma longa L.) supplementation improves growth performance, short-chain fatty acid production, and modulates bacterial composition of weaned piglets

In livestock nutrition, natural feed additives are gaining increased attention as alternatives to antibiotic growth promoters to improve animal performance. This study investigated the effects of dietary turmeric supplementation on the growth performance and gut health of weaned piglets. A total of 48 weaned piglets (Duroc × [Landrace × Yorkshire]) were used in a 6-week feeding trial. All piglets were allotted to two dietary treatments: corn-soybean meal basal diet without turmeric (control) and with 1% weight per weight (w/w) turmeric powder (turmeric). The results showed that dietary inclusion of turmeric with the basal diet improved final body weight and total average daily gain (p < 0.05). The concentrations of short-chain fatty acids in the fecal samples, including acetic, butyric, and propionic acids, were higher in the turmeric group (p < 0.05). The villus height-to-crypt depth ratio was higher in the ileum of turmeric-fed piglets (p = 0.04). The 16S rRNA gene sequencing of fecal microbiota indicated that, at the phylum level, Firmicutes and Bacteroidetes were the most predominant taxa in all fecal samples. Bacteroidetes were significantly decreased in the turmeric group compared to the control group (p = 0.021). At the genus level, turmeric showed a decreased abundance of Prevotella (p = 0.021) and an increasing trend of Lactobacillus (p = 0.083). Among the total detected species, nine bacterial species showed significant differences between the two groups. The results of this study indicated that turmeric altered the gut microbiota and short-chain fatty acid production. This suggests that turmeric could be used as a potential alternative growth promoter for piglets.

The influence on oxidative stress markers, inflammatory factors and intestinal injury-related molecules in Wahui pigeon induced by lipopolysaccharide

Introduction

The intestinal structure is the foundation for various activities and functions in poultry. An important question concerns the changes in the intestinal status under endotoxin stimulation. This study aimed to investigate the mechanism of intestinal injury induced by lipopolysaccharide (LPS) in Wahui pigeons.

Methods

Thirty-six 28-day-old healthy Wahui pigeons were randomly divided into two groups. The experimental group was injected with LPS (100 μg/kg) once per day for five days, and the control group was treated with the same amount of sterile saline. Blood and the ileum were collected from pigeons on the first, third, and fifth days of the experiment and used for oxidative stress assessment, inflammatory factor detection, histopathological examination, and positive cell localization. In addition, intestinal injury indices and mRNA expression levels (tight junction proteins, inflammatory cytokines, and factors related to autophagy and apoptosis) were evaluated.

Results

Villi in the ileum were shorter in the LPS group than in the control group, and D-lactic acid levels in the serum were significantly increased. Glutathione and catalase levels significantly decreased, but the malondialdehyde content in the serum increased. TNF-α and IL-10 were detected at higher levels in the serum, with stronger positive signals and higher mRNA expression levels, in the LPS group than in the control group. In addition, the levels of TLR4, MyD88, NF-κB, and HMGB1 in the inflammatory signaling pathway were also upregulated. Finally, the mRNA expression of Claudin3, Occludin, and ZO-1 was significantly decreased; however, that of Beclin1 and Atg5 was increased in the LPS group.

Conclusion

Ileal pathological changes and oxidative stress were caused by LPS challenge; it is proposed that this triggering regulates the inflammatory response, causing excessive autophagy and apoptosis, promoting intestinal permeability, and leading to intestinal injury in Wahui pigeons.

Maternal Probiotic or Synbiotic Supplementation Modulates Jejunal and Colonic Antioxidant Capacity, Mitochondrial Function, and Microbial Abundance in Bama Mini-piglets

The present study was conducted to investigate the effects of maternal probiotic or synbiotic supplementation during gestation and lactation on antioxidant capacity, mitochondrial function, and intestinal microbiota abundance in offspring weaned piglets. A total of 64 pregnant Bama mini-sows were randomly allocated into the control group (basal diet), antibiotic group (basal diet + 50 g/t virginiamycin), probiotic group (basal diet + 200 mL/d probiotics per pig), or synbiotic group (basal diet + 200 mL/d probiotics per pig + 500 g/t xylo-oligosaccharides). On day 30 of post-weaning, eight piglets per group with average body weight were selected for sample collection. The results showed that maternal probiotic supplementation increased the catalase (CAT) activity in plasma and glutathione peroxidase (GSH-Px) and superoxide dismutase (SOD) activities in plasma, jejunum, and colon of piglets while decreased the malondialdehyde (MDA) and H₂O₂ concentrations in plasma compared with the control group (P < 0.05). Moreover, maternal synbiotic supplementation increased the plasma CAT activity, jejunal glutathione and GSH-Px activities, jejunal and colonic total antioxidant capacity activity, and plasma and colonic SOD activity while decreased the colonic MDA concentration of offspring piglets compared with the control group (P < 0.05). The mRNA levels of antioxidant enzyme-related genes (copper- and zinc-containing superoxide dismutase, nuclear factor erythroid 2-related factor 1, and nuclear factor erythroid 2-related factor 2) and mitochondrial-related genes (adenosine triphosphate synthase alpha subunit, adenosine triphosphate synthase β, and mitochondrial transcription factor A) in the jejunal mucosa were significantly upregulated, while the level of colonic peroxisome proliferator-activated receptor γ coactivator-1α was downregulated by maternal synbiotic supplementation (P < 0.05). Maternal probiotic supplementation increased (P < 0.05) the Bacteroidetes abundance in the jejunum and Bifidobacterium abundance in the jejunum and colon, and synbiotic supplementation increased (P < 0.05) the abundances of Firmicutes, Bacteroidetes, Bifidobacterium, and Lactobacillus in the jejunum of piglets. Furthermore, correlation analysis revealed that intestinal microbiota abundances were significantly correlated with antioxidant enzyme activities and mitochondrial-related indexes. These findings indicated that maternal probiotic or synbiotic supplementation might be a promising strategy to improve the antioxidant capacity and mitochondrial function of offspring weaned piglets by altering the intestinal microbiota.

The effects of flaxseed supplementation on gene expression and inflammation in ulcerative colitis patients: An open-labelled randomised controlled trial

AIMS

Inflammatory bowel disease, a chronic inflammatory disorder of the intestinal mucosa, is a clinical presentation of Crohn's disease and ulcerative colitis (UC). This study investigated the effect of grounded flaxseed (GF) and flaxseed oil (FO) on clinical biomarkers, quality of life and diseases activity in patients with UC. This research was conducted among 90 patients with UC for 12 weeks using an open-labelled randomised controlled trial design.

METHODS

The participants were randomly assigned into two intervention groups supplemented with GF (30 gr/day) and FO (10 gr/day) as well as a control group. The participants' data were collected prior to and 12 weeks after the intervention. The one-way analysis of variance was run to compare variables.

RESULTS

A total of 75 patients completed the study. After the intervention, hs-CRP (P < .001) and Mayo score (P < .001) were reduced significantly, but quality of life was increased significantly (P < .001) in the GF and FO groups compared with the control. A significant increase was observed in IL-10 concentration in the FO group, but no significant change was found in serum levels of IL-10 in the control group. Moreover, the decrease in Mayo score was greater in patients at more severe stages of the disease (P < .05). No difference was observed between the intervention groups and control group in mRNA expression level of TLR4 at the 12th week.

CONCLUSION

In conclusion, grounded flaxseed and FO attenuated systemic inflammation and improved disease severity in UC patients.

Effects of Deoxynivalenol and Mycotoxin Adsorbent Agents on Mitogen-Activated Protein Kinase Signaling Pathways and Inflammation-Associated Gene Expression in Porcine Intestinal Epithelial Cells

Deoxynivalenol (DON) is the most prevalent mycotoxin in swine feedstuffs. The intestinal epithelial cells represent the first target for the DON. Here, we studied the effects of DON and mycotoxin adsorbent agents on mitogen-activated protein kinase (MAPK) signaling pathways and inflammation-associated gene expression in porcine intestinal epithelial cells (IPEC-J2). Results showed that phosphorylation of MAPK signaling pathways (p38, ERK, and JNK) was increased after treatment of DON or lipopolysaccharide (LPS) in IPEC-J2 cells. The phosphorylation of p38, ERK, and JNK was not further enhanced after co-treatment with DON and LPS. The inos and cox-2 mRNA expression were significantly induced at 6 h after treatment of DON. DON treatment significantly increased the claudin 3 and occludin mRNA expression at 12 h. DON in combination with LPS treatment did not further increase the inflammation and tight junction-associated gene expression. The DON-induced phosphorylation of MAPK signaling pathways was impaired by mycotoxin adsorbent agent (nanoscale silicate platelets and the mixture of montmorillonites and yeast cell walls) treatment, thereby decreasing inflammation and tight junction-associated gene expression. Taken together, these findings demonstrate that DON triggers the inflammation in IPEC-J2 cells by phosphorylation of MAPK signaling pathways and LPS does not further augment the DON-induced inflammatory responses. Mycotoxin adsorbent agents can attenuate DON-induced inflammatory responses in IPEC-J2 cells through modulation of the phosphorylation of p38, ERK, and JNK.

Dietary Fiber Ameliorates Lipopolysaccharide-Induced Intestinal Barrier Function Damage in Piglets by Modulation of Intestinal Microbiome

Weaning of piglets is accompanied by intestinal inflammation, impaired intestinal barrier function, and intestinal microflora disorder. Regulating intestinal microflora structure can directly or indirectly affect intestinal health and host growth and development. However, whether dietary fiber (DF) affects the inflammatory response and barrier function by affecting the intestinal microflora and its metabolites is unclear. In this study, we investigated the role of intestinal microflora in relieving immune stress and maintaining homeostasis using piglets with lipopolysaccharide (LPS)-induced intestinal injury as a model. DF improved intestinal morphology and barrier function, inhibited the expression of inflammatory signal pathways (Toll-like receptor 2 [TLR2], TLR4, and NF-κB) and proinflammatory cytokines (interleukin 1β [IL-1β], IL-6, and tumor necrosis factor alpha [TNF-α]), and upregulated the expression of barrier-related genes (encoding claudin-1, occludin, and ZO-1). The contents of proinflammatory cytokines (IL-1β, IL-6, and TNF-α) and the activity of diamine oxidase in plasma were decreased. Meanwhile, DF had a strong effect on the composition and function of intestinal microflora at different taxonomic levels, the relative abundances of cellulolytic bacteria and anti-inflammatory bacteria were increased, and the concentrations of propionate, butyrate, and total short-chain fatty acids (SCFAs) in intestinal contents were increased. In addition, the correlation analysis also revealed the potential relationship between metabolites and certain intestinal microflora, as well as the relationship between metabolites and intestinal morphology, intestinal gene expression, and plasma cytokine levels. These results indicate that DF improves intestinal barrier function, in part, by altering intestinal microbiota composition and increasing the synthesis of SCFAs, which subsequently alleviate local and systemic inflammation.IMPORTANCE Adding DF to the diet of LPS-challenged piglets alleviated intestinal and systemic inflammation, improved intestinal barrier function, and ultimately alleviated the growth retardation of piglets. In addition, the addition of DF significantly increased the relative abundance of SCFA-producing bacteria and the production of SCFAs. We believe that the improvement of growth performance of piglets with LPS-induced injury can be attributed to the beneficial effects of DF on intestinal microflora and SCFAs, which reduced the inflammatory response in piglets, improving intestinal barrier function and enhancing body health. These research results provide a theoretical basis and guidance for the use of specific fiber sources in the diet to improve intestinal health and growth performance of piglets and thus alleviate weaning stress. Our data also provide insights for studying the role of DF in regulating gastrointestinal function in human infants.

Tremella fuciformis Polysaccharides Inhibited Colonic Inflammation in Dextran Sulfate Sodium-Treated Mice via Foxp3+ T Cells, Gut Microbiota, and Bacterial Metabolites

Tremella fuciformis is an edible medicinal mushroom, and its polysaccharide components are found to confer various health benefits. This study identified the protective effects of polysaccharides of Tremella fuciformis (TPs) against dextran sulfate sodium (DSS)-induced colitis in mice. High dose of TPs (HTPs) could prevent the colon from shortening, reduce activity of colonic myeloperoxidase and serum diamine oxidase (DAO), decrease the concentration of D-lactate, and alleviate the colonic tissue damage in colitic mice. HTPs treatment stimulated Foxp3+T cells, and promoted the production of anti-inflammatory cytokines whereas it reduced the production of pro-inflammatory and the portion of immunoglobulin A (IgA)-coated bacteria, which was related to modulation of immune responses. 16S rRNA sequencing analysis showed that TPs could significantly increase gut community diversity, and restore the relative abundances of Lactobacillus, Odoribacter, Helicobacter, Ruminococcaceae, and Marinifilaceae. According to metabolomic analysis, HTPs induced specific microbial metabolites akin to that in normal mice. Tyrosine biosynthesis, tryptophan metabolism, and bile acid metabolism were influenced in the HTPs group compared with those in the DSS group. HTPs could alleviate DSS-induced colitis by immunoregulation and restored the gut microbiota and microbial metabolites. The results indicated that HTPs have potential to be developed as a food supplement to ameliorate intestinal diseases.

Dietary glycyl-glutamine supplementation ameliorates intestinal integrity, inflammatory response, and oxidative status in association with the gut microbiota in LPS-challenged piglets

During weaning transition, mammalian newborns suffer severe enteric infections and thus induced gut microbiota dysbiosis, which in turn aggravates enteric disorder. The synthetic dipeptide glycyl-glutamine (GlyGln) has been used as a diet supplement to improve the weaning transition of newborns. However, the effect of dietary GlyGln supplementation on the gut microbiota of piglets with enteric infection remains unclear. Here, weaned piglets received a basal diet or a basal diet supplemented with 0.25% GlyGln for 3 weeks. Five piglets in each group received an intraperitoneal injection of lipopolysaccharide (LPS) (100 μg per kg BW) (LPS and GlyGln + LPS groups) and meanwhile five piglets in a control group received an intraperitoneal injection of saline (Ctrl group). The results showed that dietary GlyGln supplementation improved the LPS induced inflammation response and damage to the ileum morphology by increasing interleukin 10, tight junction proteins, villus height, and the ratio villus height/crypt depth, but decreasing the crypt depth. For the oxidative status, dietary GlyGln supplementation increased the ileal superoxide dismutase and meanwhile reduced the malondialdehyde and nitric oxide synthase activity (NOS) (total NOS and inducible NOS), compared with that in the LPS group. LPS challenge reduced the diversity of gut microbiota and enriched the facultative anaerobic Escherichia coli. The GlyGln restored alpha diversity and the structure of the gut microbiota by enriching obligate anaerobes and short-chain fatty acid (SCFA)-producing bacteria, including Clostridium, Lachnospira, Phascolarctobacterium, Roseburia, Lachnospiraceae, and Synergistetes. GlyGln enriched the gut microbiota function of carbohydrate metabolism and elevated the ileal SCFA concentrations of propionic acid and butyric acid that had been decreased by the LPS challenge. The beneficial effects of dietary GlyGln supplementation are closely associated with its enriched bacteria and SCFAs. Taken together, dietary GlyGln supplementation improved the gut microbiota dysbiosis induced by LPS challenge and enriched obligate anaerobes and SCFA-producing bacteria, which contributed to the amelioration of intestinal integrity, inflammatory responses, and oxidative status.

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 10^4.5 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.

Xylooligosaccharide attenuates lipopolysaccharide-induced intestinal injury in piglets via suppressing inflammation and modulating cecal microbial communities

Xylooligosaccharide (XOS) has been considered to be an effective prebiotic, but its exact mechanisms remain unknown. This research was conducted to evaluate the effects of XOS on pig intestinal bacterial community and mucosal barrier using a lipopolysaccharide (LPS)-caused gut damage model. Twenty-four weaned pigs were assigned to 4 treatments in a 2 × 2 factorial design involving diet (with or without XOS) and immunological challenge (saline or LPS). After 21 d of feeding 0% or 0.02% commercial XOS product, piglets were treated with saline or LPS. After that, blood, small intestinal mucosa and cecal digesta were obtained. Dietary XOS enhanced intestinal mucosal integrity demonstrated by higher villus height, villus height-to-crypt depth ratio, disaccharidase activities and claudin-1 protein expression and lower crypt depth. XOS also caused down-regulation of the gene expression of toll-like receptor 4 and nucleotide-binding oligomerization domain protein signaling, accompanied with decreased pro-inflammatory cytokines and cyclooxygenase 2 contents or mRNA expression and increased heat shock protein 70 mRNA and protein expression. Additionally, increased Bacteroidetes and decreased Firmicutes relative abundance were observed in the piglets fed with XOS. At the genus level, XOS enriched the relative abundance of beneficial bacteria, e.g., Faecalibacterium, Lactobacillus, and Prevotella. Moreover, XOS enhanced short chain fatty acids contents and inhibited histone deacetylases. The correlation analysis of the combined datasets implied some potential connections between the intestinal microbiota and pro-inflammatory cytokines or cecal metabolites. These results suggest that XOS inhibits inflammatory response and beneficially modifies microbes and metabolites of the hindgut to protect the intestine from inflammation-related injury.

The effect of supplemental bioactive fatty acids on growth performance and immune function of milk-fed Holstein dairy calves during heat stress

The present study aimed to evaluate the effects of different supplemental fat sources (soyabean oil (SBO) as a source of n-6 fatty acid (FA) and fish oil (FO) as a source of n-3 FA) in the starter feed of milk-fed dairy calves during the hot season. Forty Holstein calves (3 d of age; 39·67 kg of body weight; ten calves per group) were randomly assigned to the experimental treatments as follows: (1) starter feed supplemented with no fat source (CON), (2) starter feed supplemented with 3 % SBO (DM basis), (3) starter feed supplemented with 3 % FO (DM basis) and (4) starter feed supplemented with an equal mixture of SBO and FO (1·5 % each, DM basis). The milk feeding schedule was constant for treatments and all calves were weaned on day 65 of age. Results show that calves had greater starter intake, average daily gain and body length when fed SBO compared with the other treatments. However, feed efficiency was increased and inflammatory indicators (TNF-α, serum amyloid A and haptoglobin) concentrations were reduced in the calves fed FO compared with the other treatments. In summary, it was revealed that SBO rich in n-6 FA improved starter intake and growth performance, while FO rich in n-3 FA could improve the immune function of calves. Due to the current experimental condition, an equal mixture of SBO and FO (1·5 % each, DM basis) can be recommended to have an optimum growth performance and immune function while the calves are reared under the heat conditions.

Lactobacillus delbrueckii Protected Intestinal Integrity, Alleviated Intestinal Oxidative Damage, and Activated Toll-Like Receptor-Bruton's Tyrosine Kinase-Nuclear Factor Erythroid 2-Related Factor 2 Pathway in Weaned Piglets Challenged with Lipopolysaccharide

Oxidative stress is increasingly being recognized as a player in the pathogenesis of intestinal pathologies, and probiotics are becoming an attractive means of addressing it. The present study investigated the effects of dietary supplementation with Lactobacillus delbrueckii (LAB) on intestinal integrity and oxidative damage in lipopolysaccharide (LPS)-challenged piglets. A total of 36 crossbred weaned piglets (Duroc × Landrace × Large Yorkshire) were randomly divided into three groups: (1) non-challenged controls (CON), (2) LPS-challenged controls (LPS), and (3) 0.2% LAB (2.01 × 10¹⁰ CFU/g) + LPS treatment (LAB + LPS). On the 29th day of the experiment, the LPS and CON groups were injected intraperitoneally with LPS and saline at 100 ug/kg body weight, respectively. The results show that the LPS-induced elevation of the serum diamine oxidase (DAO) level and small intestinal crypt depth (CD) were reversed by the dietary addition of LAB, which also markedly increased the ileal expression of tight junction proteins (occludin, ZO-1, and claudin-1) in the LPS-challenged piglets. Furthermore, LAB supplementation normalized other LPS-induced changes, such as by decreasing malondialdehyde (MDA) in both the serum and intestinal mucosa and 8-hydroxy-2-deoxyguanosine (8-OHdG) in the jejunal mucosa, increasing glutathione reductase (GR) and glutathione peroxidase (GSH-Px) in both the serum and intestinal mucosa, and increasing glutathione (GSH) and superoxide dismutase (SOD) in the jejunal mucosa. LAB also activated Toll-like receptor (TLR)–Bruton’s tyrosine kinase (Btk)–nuclear factor erythroid 2-related factor 2(Nrf2) signaling pathways in the intestine, suggesting that it plays a vital role in the ameliorative antioxidant capacity of weaned piglets. In summary, LAB increased intestinal integrity by improving the intestinal structure and tight junctions while enhancing antioxidant functions via the activation of the TLR–Btk–Nrf2 signaling pathway.

Dietary Grape Seed Meal Bioactive Compounds Alleviate Epithelial Dysfunctions and Attenuates Inflammation in Colon of DSS-Treated Piglets

Inflammatory Bowel Diseases (IBD) are chronic inflammations associated with progressive degradation of intestinal epithelium and impairment of the local innate immune response. Restoring of epithelial integrity and of the mucosal barrier function, together with modulation of inflammatory and innate immune markers, represent targets for alternative strategies in IBD. The aim of our study was to evaluate the effects of a diet including 8% grape seed meal (GSM), rich in bioactive compounds (polyphenols, polyunsaturated fatty acids (PUFAs), fiber) on the markers of colonic epithelial integrity, mucosal barrier function, pro-inflammatory, and innate immunity in DSS-treated piglets used as animal models of intestinal inflammation. Our results have demonstrated the beneficial effects of bioactive compounds from dietary GSM, exerted at three complementary levels: (a) restoration of the epithelial integrity and mucosal barrier reinforcement by modulation of claudins, Occludin (OCCL) and Zonula-1 (ZO-1) tight junction genes and proteins, myosin IXB (MYO9B) and protein tyrosine phosphatase (PTPN) tight junction regulators and mucin-2 (MUC2) gene; (b) reduction of pro-inflammatory MMP-2 (matrix metalloproteinase-2) and MMP-9 (matrix metalloproteinase-9) genes and activities; and (c) suppression of the innate immune TLR-2 (Toll-like receptor-2) and TLR-4 (Toll-like receptor-4) genes and attenuation of the expression of MyD88 (Myeloid Differentiation Primary Response 88)/MD-2 (Myeloid differentiation factor-2) signaling molecules. These beneficial effects of GSM could further attenuate the transition of chronic colitis to carcinogenesis, by modulating the in-depth signaling mediators belonging to the Wnt pathway.

Comparison of intestinal permeability, morphology, and ileal microbial communities of commercial hens housed in conventional cages and cage-free housing systems

The gastrointestinal health of poultry can be impacted by a variety of factors including their environment. As egg production moves from conventional cage housing (CC) toward cage-free housing (CF), it is important to understand this impact on intestinal health. This study was conducted to determine if housing type impacted intestinal permeability, morphology, and microbial communities in commercial hens across housing systems. Hens were randomly selected from 2 rooms of CC (n = 25) and CF (n = 25) at a commercial facility. Birds were given fluorescein isothiocyanate dextran (FITC-D) by oral gavage to measure intestinal permeability. Jejunal and ileal samples were collected to evaluate villus height, crypt depth, and their ratio. Ileal contents were collected for bacterial DNA isolation and 16S rRNA gene sequencing. Serum FITC-D was similar between housing type (P = 0.709). Hens housed in the CF had increased jejunal villus height and crypt depth compared with hens from the CC (P < 0.002). Hens from the CC tended to have a greater villus height to crypt depth ratio in both the jejunum and ileum compared with the CF (P = 0.064; P = 0.091, respectively). Microbial community diversity measurements favored hens housed in the CC as ileal contents tended to have increased species richness (P = 0.059), had greater alpha diversity (P = 0.044), and had an increased number of over represented operational taxonomic units (46/64), including Romboutsia sp. (30.80%), Lactobacillus kitasatonis (17.16%), and Lactobacillus aviarius (11.15%). Correlations between microbial communities with intestinal traits identified significant association with the greatest number of correlations with FITC-D and ileal morphology. Many of these correlations identified microbial communities associated with expected traits; thus, providing limited functional data to microbial communities with limited information. The greater number of correlations of ileal morphology with ileal microbial communities suggesting local microbial communities contribute to the intestinal environment distant. In this limited study, several parameters favored hens from CC suggesting an advantage of this system for intestinal health. However, the lower intestinal health parameters observed in CF were not at levels to indicate detrimental effects.

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

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

The Protect Effects of Chitosan Oligosaccharides on Intestinal Integrity by Regulating Oxidative Status and Inflammation under Oxidative Stress

The aim of this study was to evaluate the effects of the dietary supplementation of chitosan oligosaccharides (COS) on intestinal integrity, oxidative status, and the inflammation response with hydrogen peroxide (H₂O₂) challenge. In total, 30 rats were randomly assigned to three groups with 10 replications: CON group, basal diet; AS group, basal diet + 0.1% H₂O₂ in drinking water; ASC group, basal diet + 200 mg/kg COS + 0.1% H₂O₂ in drinking water. The results indicated that COS upregulated (p < 0.05) villus height (VH) of the small intestine, duodenum, and ileum; mucosal glutathione peroxidase activity; jejunum and ileum mucosal total antioxidant capacity; duodenum and ileum mucosal interleukin (IL)-6 level; jejunum mucosal tumor necrosis factor (TNF)-α level; duodenum and ileum mucosal IL-10 level; the mRNA expression level of zonula occludens (ZO)-1 in the jejunum and ileum, claudin in the duodenum, nuclear factor-erythroid 2-like 2 in the jejunum, and heme oxygenase-1 in the duodenum and ileum; and the protein expression of ZO-1 and claudin in jejunum; however, it downregulated (p < 0.05) serum diamine oxidase activity and D-lactate level; small intestine mucosal malondialdehyde content; duodenum and ileum mucosal IL-6 level; jejunum mucosal TNF-α level; and the mRNA expression of IL-6 in the duodenum and jejunum, and TNF-α in the jejunum and ileum. These results suggested COS could maintain intestinal integrity under oxidative stress by modulating the intestinal oxidative status and release of inflammatory cytokines.

Low-Molecular-Weight Chitosan Attenuates Lipopolysaccharide-Induced Inflammation in IPEC-J2 Cells by Inhibiting the Nuclear Factor-κB Signalling Pathway

Low-molecular-weight chitosan (LMWC), a product of chitosan deacetylation, possesses anti-inflammatory effects. In the present study, a porcine small intestinal epithelial cell line, IPEC-J2, was used to assess the protective effects of LMWC on lipopolysaccharide (LPS)-induced intestinal epithelial cell injury. IPEC-J2 cells were pretreated with or without LMWC (400 μg/mL) in the presence or absence of LPS (5 μg/mL) for 6 h. LMWC pretreatment increased (p < 0.05) the occludin abundance and decreased (p < 0.05) the tumour necrosis factor-α (TNF-α) production, apoptosis rate and cleaved cysteinyl aspartate-specific protease-3 (caspase-3) and -8 contents in LPS-treated IPEC-J2 cells. Moreover, LMWC pretreatment downregulated (p < 0.05) the expression levels of TNF receptor 1 (TNFR1) and TNFR-associated death domain and decreased (p < 0.05) the nuclear and cytoplasmic abundance of nuclear factor-κB (NF-κB) p65 in LPS-stimulated IPEC-J2 cells. These results suggest that LMWC exerts a mitigation effect on LPS-induced intestinal epithelial cell damage by suppressing TNFR1-mediated apoptosis and decreasing the production of proinflammatory cytokines via the inhibition of NF-κB signalling pathway.

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

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

Fat Encapsulation Reduces Diarrhea in Piglets Partially by Repairing the Intestinal Barrier and Improving Fatty Acid Transport

(1) Background: Nutritional strategies to enhance gut function and reduce the piglet diarrhea rate are critical to increase the growth performance of piglets. The purpose of this study was to investigate whether dietary fat types and/or fat microencapsulation techniques are involved in regulating the fatty acid transport system and the mechanical and immunological barriers of the small intestine. (2) Methods: Three hundred twenty-four weaning piglets were randomly divided into three groups fed a soybean oil diet (SBO, control group, 6.0% soybean oil), palm oil diet (PO, 6.0% palm oil), or encapsulated palm oil diet (EPO, 7.5% encapsulated palm oil). (3) Results: A significantly lower mRNA expression of the claudin was observed in the duodenum and jejunum of the PO group than in the SBO group (p < 0.05). However, the mRNA expression and protein abundance of claudin and ZO-1 in the jejunum of the EPO group were higher (p < 0.05) than in the PO group. Porcine β-defensin (pBD) secretion was not significantly different between the SBO and PO groups (p > 0.05), while the pBD-2 levels were significantly different (p < 0.05). Compared with the PO group, the EPO group exhibited a significantly increased secretion of pBD-2 and pBD-129 in the small intestine (p < 0.05) and pBD-1 in the jejunum and ileum (p < 0.05). The protein abundances of apolipoprotein AIV (Apo AIV) and intestinal fatty acid binding protein (I-FABP) were significantly lower in the PO group than in the SBO group (p < 0.05). Simultaneously, the protein abundances of fatty acid transport protein 4 (FATP4), fatty acid translocase (CD36), and I-FABP were higher in the EPO group than in the PO group. Furthermore, the low digestibility of palm oil (PO group) might negatively regulate intestinal tight junctions, fatty acid transporters, lipoproteins, and β-defensin through the activation of the AMPK/mTORC1 and AMPK/Sirt1/NF-κB pathways. (4) Conclusions: In summary, microencapsulation techniques might alleviate the negative effects of palm oil and help to improve the intestinal fatty acid transport system and barrier function.

Effect of chlorogenic acid on alleviating inflammation and apoptosis of IPEC-J2 cells induced by deoxyniyalenol

Deoxynivalenol (DON) is extensively detected in many kinds of foods and feeds to harm human and animal health. This research aims to investigate the effect of chlorogenic acid (CGA) on alleviating inflammation and apoptosis of swine jejunal epithelial cells (IPEC-J2) triggered by DON. The results demonstrated that cell viability was decreased when DON concentrations increased or incubation time expanded. The pretreatment with CGA (40 μg/mL) for 1 h increased cell viability, decreased lactate dehydrogenase (LDH) release and apoptosis in cells triggered by DON at 0.5 μg/mL for 6 h, compared with the DON alone-treated cells. Moreover, the mRNA abundances of IL-8, IL-6, TNF-α, COX-2, caspase-3, Bax and ASCT2 genes, and protein expressions of COX-2, Bax and ASCT2 were significantly down-regulated; while the mRNA abundances of ZO-1, claudin-1, occludin, PePT1 and GLUT2 genes, and protein expressions of ZO-1, claudin-1 and PePT1 were significantly up-regulated in the CGA + DON group, compared with the DON alone group. This study indicated that CGA pretreatment alleviated cytotoxicity, inflammation and apoptosis in DON-triggered IPEC-J2 cells, and protected intestinal cell integrity from DON damages.

Dietary ω-3 fatty acids and their influence on inflammation via Toll-like receptor pathways

Dietary intake of long-chain, highly unsaturated ω-3 fatty acids (FAs) is considered indispensable for humans. The ω-3 FAs have been known to be anti-inflammatory and immunomodulatory dietary factors; however, the modes of action on pathogen recognition receptors (PRRs) and downstream signaling pathways have not been fully elucidated. Dietary sources contain various amounts of ω-3 long-chain fatty acids (LCFAs) of different lengths and the association between intake of these polyunsaturated fatty acids (PUFAs) with underlying mechanisms of various immune-related disorders can be of great interest. The potential anti-inflammatory role for ω-3 LCFAs can be explained by modification of lipid rafts, modulation of inflammatory mediators such as cytokines and PRRs. Toll-like receptors (TLRs) are a group of PRRs that play an important role in the recognition of bacterial infections and ω-3 FAs have been implicated in the modulation of downstream signaling of TLR-4, an important receptor for recognition of gram-negative bacteria. The ω-3 FAs docosahexaenoic acid and eicosapentaenoic acid have been investigated in vivo and in vitro for their effects on the nuclear factor-κB activation pathway. Identification of the effects of ω-3 FAs on other key molecular factors like prostaglandins and leukotrienes and their signals may help the recognition and development of medicines to suppress the main mediators and turn on the expression of anti-inflammatory cytokines and nuclear receptors.

Docosahexaenoic acid alleviates cell injury and improves barrier function by suppressing necroptosis signalling in TNF-α-challenged porcine intestinal epithelial cells

Long-chain n-3 polyunsaturated fatty acids are known to have beneficial effects on intestinal health. However, the underling mechanisms are largely unknown. The present study was conducted to investigate whether docosahexaenoic acid (DHA) attenuates TNF-α-induced intestinal cell injury and barrier dysfunction by modulating necroptosis signalling. Intestinal porcine epithelial cell line 1 was cultured with or without 12.5 µg/ml DHA, followed by exposure to 50 ng/ml TNF-α for indicated time periods. DHA restored cell viability and cell number triggered by TNF-α. DHA also improved barrier function, which was indicated by increased trans-epithelial electrical resistance, decreased FD4 flux and increased membrane localisation of zonula occludins (ZO-1) and claudin-1. Moreover, DHA suppressed cell necrosis in TNF-α-challenged cells, as shown in the IncuCyte ZOOM™ live cell imaging system and transmission electron microscopy. In addition, DHA decreased protein expression of TNF receptor, receptor interacting protein kinase 1, RIP3 and phosphorylation of mixed lineage kinase-like protein, phosphoglycerate mutase family 5, dynamin-related protein 1 and high mobility group box-1 protein. Furthermore, DHA suppressed protein expression of caspase-3 and caspase-8. Collectively, these results indicate that DHA is capable of alleviating TNF-α-induced cell injury and barrier dysfunction by suppressing the necroptosis signalling pathway.

Curcumin ameliorates duodenal toxicity of AFB1 in chicken through inducing P-glycoprotein and downregulating cytochrome P450 enzymes

It has been reported that oral intake of aflatoxin B1 (AFB1)-contaminated feed could cause acute, sub-chronic, or chronic toxicity in livestock and poultry. However, the harmful effect of AFB1 on the small intestine is still controversial. Therefore, blocking the entry of AFB1 into the body through the digestive tract is one of the important methods to prevent its toxicity. In the present study, 1-day-old Arbor Acres broilers were randomly divided into 6 groups including control group, curcumin control group (450 mg curcumin/kg feed), curcumin low-, medium-, and high-dose group (150, 300, and 450 mg curcumin/kg feed + 5 mg AFB1/kg feed), and AFB1 group (5 mg AFB1/kg feed). After 28 d, the samples of chickens' duodenums were collected for further analyses. AFB1 caused abnormal functional and morphological changes in the duodenum, including histological lesions, increased the length of the duodenum and depth of crypt, decreased the unit weight of the duodenum, height of villus, and the value of villus height/crypt depth. Meanwhile, AFB1 administration enhanced malonaldehyde activity, 8-HOdG level, and the mRNA expression of cytochrome P450 (CYP450) enzymes, and reduced superoxide dismutase, catalase, adenosine triphosphatase (ATPase) activity and the mRNA expression of Abcb1. Importantly, curcumin supplementation partially ameliorated AFB1-induced abnormal functional and morphological signs of the duodenum, alleviated AFB1-induced oxidative stress, and decreased the mRNA expression of CYP450 enzymes. Furthermore, curcumin ameliorated AFB1-induced decrease in the Abcb1 mRNA expression, P-glycoprotein (P-gp) level, and ATPase activities. It has been suggested from these results that curcumin supplementation in the feed could ameliorate AFB1-induced duodenal toxicity and damage through downregulating CYP450 enzymes, promoting ATPase activities, and inducing P-gp in chickens.

Branched-Chain Fatty Acids-An Underexplored Class of Dairy-Derived Fatty Acids

Dairy fat and its fatty acids (FAs) have been shown to possess pro-health properties that can support health maintenance and disease prevention. In particular, branched-chain FAs (BCFAs), comprising approximately 2% of dairy fat, have recently been proposed as bioactive molecules contributing to the positive health effects associated with the consumption of full-fat dairy products. This narrative review evaluates human trials assessing the relationship between BCFAs and metabolic risk factors, while potential underlying biological mechanisms of BCFAs are explored through discussion of studies in animals and cell lines. In addition, this review details the biosynthetic pathway of BCFAs as well as the content and composition of BCFAs in common retail dairy products. Research performed with in vitro models demonstrates the potent, structure-specific properties of BCFAs to protect against inflammation, cancers, and metabolic disorders. Yet, human trials assessing the effect of BCFAs on disease risk are surprisingly scarce, and to our knowledge, no research has investigated the specific role of dietary BCFAs. Thus, our review highlights the critical need for scientific inquiry regarding dairy-derived BCFAs, and the influence of this overlooked FA class on human health.

Metabolic and functional interplay between gut microbiota and fat-soluble vitamins

Gut microbiota is a complex ecosystem seen as an extension of human genome. It represents a major metabolic interface of interaction with food components and xenobiotics in the gastrointestinal (GI) environment. In this context, the advent of modern bacterial genome sequencing technology has enabled the identification of dietary nutrients as key determinants of gut microbial ecosystem able to modulate the host-microbiome symbiotic relationship and its effects on human health. This article provides a literature review on functional and molecular interactions between a specific group of lipids and essential nutrients, e.g., fat-soluble vitamins (FSVs), and the gut microbiota. A two-way relationship appears to emerge from the available literature with important effects on human metabolism, nutrition, GI physiology and immune function. First, FSV directly or indirectly modify the microbial composition involving for example immune system-mediated and/or metabolic mechanisms of bacterial growth or inhibition. Second, the gut microbiota influences at different levels the synthesis, metabolism and transport of FSV including their bioactive metabolites that are either introduced with the diet or released in the gut via entero-hepatic circulation. A better understanding of these interactions, and of their impact on intestinal and metabolic homeostasis, will be pivotal to design new and more efficient strategies of disease prevention and therapy, and personalized nutrition.

Omega-3 Polyunsaturated Fatty Acids Counteract Inflammatory and Oxidative Damage of Non-Transformed Porcine Enterocytes

Simple Summary

Farm animals frequently suffer from chronic inflammatory diseases due to certain physiological or pathophysiological conditions such as weaning, the periparturient period and infections. Traditionally, antibiotics were added to animal diets to counteract inflammation and enhance growth. However, this leads to the emergence of antibiotic-resistant bacterial species which causes potential health hazards. Over several decades, omega-3 polyunsaturated fatty acids have been known to exhibit a multitude of beneficial effects in animal health and are regarded as a functional food with therapeutic potential. We accessed the bioactivity of omega-3 polyunsaturated fatty acids as eicosapentaenoic acid and docosahexaenoic acid in pig intestinal epithelium under different stress conditions in an in vitro set-up. Our results demonstrated the proliferative and cytoprotective properties of the two fatty acids, which are fundamental to determining the cellular mechanism for efficient utilization in pig diets.

Abstract

Marine and plant-based omega-3 polyunsaturated fatty acids (ω-3 PUFAs) are widely added to animal diets to promote growth and immunity. We tested the hypothesis that eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA) and their 1:2 combination could counteract acute or long-term damage of lipopolysaccharides (LPS), dextran sodium sulphate (DSS) and hydrogen peroxide (H₂O₂) in Intestinal Porcine Epithelial Cell line-J2 (IPEC-J2). The results showed that 24 h treatment with EPA or DHA exhibited proliferative effects in IPEC-J2 cells at low to moderate concentrations (6.25–50 μM) (p < 0.05). Further, 24 h pretreatment with individual DHA (3.3 µM), EPA (6.7 µM) or as DHA:EPA (1:2; 10 µM) combination increased the mitochondrial activity or cell membrane integrity post-LPS (24 h), DSS (24 h) and H₂O₂ (1 h) challenge (p < 0.05). Additionally, DHA:EPA (1:2, 10 µM) combination decreased the apoptotic caspase-3/7 activity around twofold after 24 h LPS and DSS challenge (p < 0.05). Our study confirms the proliferative and cytoprotective properties of EPA and DHA in IPEC-J2 cells. Increased intracellular mitochondrial activity and cell membrane integrity by ω-3 PUFAs can play a role in preventing enterocyte apoptosis during acute or chronic inflammatory and oxidative stress.

The Molecular and Mechanistic Insights Based on Gut-Liver Axis: Nutritional Target for Non-Alcoholic Fatty Liver Disease (NAFLD) Improvement

Non-alcoholic fatty liver disease (NAFLD) is recognized as the most frequent classification of liver disease around the globe. Along with the sequencing technologies, gut microbiota has been regarded as a vital factor for the maintenance of human and animal health and the mediation of multiple diseases. The modulation of gut microbiota as a mechanism affecting the pathogenesis of NAFLD is becoming a growing area of concern. Recent advances in the communication between gut and hepatic tissue pave novel ways to better explain the molecular mechanisms regarding the pathological physiology of NAFLD. In this review, we recapitulate the current knowledge of the mechanisms correlated with the development and progression of NAFLD regulated by the gut microbiome and gut-liver axis, which may provide crucial therapeutic strategies for NAFLD. These mechanisms predominantly involve: (1) the alteration in gut microbiome profile; (2) the effects of components and metabolites from gut bacteria (e.g., lipopolysaccharides (LPS), trimethylamine-N-oxide (TMAO), and N,N,N-trimethyl-5-aminovaleric acid (TMAVA)); and (3) the impairment of intestinal barrier function and bile acid homeostasis. In particular, the prevention and therapy of NAFLD assisted by nutritional strategies are highlighted, including probiotics, functional oligosaccharides, dietary fibers, ω-3 polyunsaturated fatty acids, functional amino acids (L-tryptophan and L-glutamine), carotenoids, and polyphenols, based on the targets excavated from the gut-liver axis.

Effects of dietary grape pomace on the intestinal microbiota and growth performance of weaned piglets

Grape pomace (GP) is an abundant by-product from wine production and is rich in phenolic compounds, unsaturated fatty acids, dietary fibre and beneficial bacteria. In this study, weaned piglets were fed a basic diet supplemented with 5% GP for 4 weeks. Compared with those in the control (CON) group, it was found that the proportion of Lactobacillus delbrueckii, Olsenella umbonata and Selenomonas bovis in the caecum and the villus height and villus height/crypt depth ratio (VCR) of the jejunum were both significantly increased in the GP group (p < 0.05). Meanwhile, at the mRNA expression level, several proinflammatory cytokines (IL-1β, IL-8, IL-6 and TNF-α) were significantly downregulated (p < 0.05) in piglet caecal tissue, and the short-chain fatty acid receptors (GPR41 and GPR43) were not significantly upregulated. In contrast, the levels of IgG was significantly increased (p < 0.05) in the sera of weaned piglets in the GP group. However, no difference in growth performance between the two groups of piglets was detected. These results show that GP had no adverse effects on the growth performance of piglets, but GP can promote the content of some beneficial bacteria in the caecum; this effect is conducive to improving the disease resistance potential of piglets.

Dietary genistein supplementation protects against lipopolysaccharide-induced intestinal injury through altering transcriptomic profile

Genistein is abundant in the corn-soybean meal feed. Little information is available about the effect of dietary genistein on the intestinal transcriptome of chicks, especially when suffering from intestinal injury. In this study, 180 one-day-old male ROSS 308 broiler chickens were randomly allocated to 3 groups, with 4 replicates (cages) of 15 birds each. The treatments were as follows: chicks received a basal diet (CON), a basal diet and underwent lipopolysaccharide-challenge (LPS), or a basal diet supplemented with 40 mg/kg genistein and underwent LPS-challenge (GEN). LPS injection induced intestinal injury and inflammatory reactions in the chicks. Transcriptomic analysis identified 7,131 differently expressed genes (3,281 upregulated and 3,851 downregulated) in the GEN group compared with the LPS group (P adjusted value < 0.05, |fold change| > 1.5), which revealed that dietary genistein exposure altered the gene expression profile and signaling pathways in the ileum of LPS-treated chicks. Furthermore, dietary genistein improved intestinal morphology, mucosal immune function, tight junction, antioxidant activity, apoptotic process, and growth performance, which were adversely damaged by LPS injection. Therefore, adding genistein into the diet of chicks can alter RNA expression profile and ameliorate intestinal injury in LPS-challenged chicks, thereby improving the growth performance of chicks with intestinal injury.

Flaxseed oil supplementation improves intestinal function and immunity, associated with altered intestinal microbiome and fatty acid profile in pigs with intrauterine growth retardation

Flaxseed oil (FO), enriched in n-3 polyunsaturated fatty acids (PUFAs), is an important oil source for intestinal development and health. We aimed to study the different effects of FO versus soybean oil (SO) on growth, intestinal health and immune function of neonates with intrauterine growth retardation (IUGR) using a weaned piglet model. Forty pairs of male IUGR and normal birth weight piglets, weaned at 21 ± 1 d, were fed diets containing either 4% FO or SO for 3 weeks consecutively. Growth performance, nutrient digestibility and intestinal function parameters, immunology and microbiota composition were determined. IUGR led to a poor growth rate, nutrient digestibility and abnormal immunology variables, whereas feeding FO diet improved systemic and gut immunity, as indicated by increased plasma concentration of immunoglobulin G and decreased CD3+CD8+ T lymphocytes, and down-regulated intestinal expression of genes (MyD88, NF-κB, TNF-α, IL-10). Although IUGR tended to decrease villous height, feeding FO diet tended to increase the villi-crypt ratio and up-regulated expressions of tight junction genes (Claudin-1 and ZO-1), together with increased mucosa contents of n-3 PUFAs and a lower Σn-6/Σn-3 ratio. Besides, FO diet decreased the abundance of pathogenic bacteria Spirochaetes, and increased phylum Actinobacteria, and genera Blautia and Bifidobacterium in colonic digesta. Our findings indicate that IUGR impairs growth rate, nutrient digestibility, and partly immunology variables, whereas feeding FO-supplemented diet could improve intestinal function and immunity of both IUGR and NBW pigs, associated with the altered gut microbiome and mucosal fatty acid profile.

Effects of dietary fatty acids on gut health and function of pigs pre- and post-weaning

Fatty acids (FA) play a major role in relation to mucosal immune responses, epithelial barrier functions, oxidative stress, and inflammatory reactions. The dietary FA composition and the molecular structures (chain length and number of double bonds) influence digestion, absorption and metabolism, and the bioactivity of the FA. Piglets post-weaning having an immature intestine and not fully formed immune functions are very vulnerable to invading microorganisms. Manipulation of the milk FA composition via sow nutrition, or inclusion of dietary fat sources in the feed for newly weaned pigs, may be used as a strategic tool to enhance pig performance and their gut health and function pre- and post-weaning. Medium-chain fatty acids (MCFA) are absorbed directly into the portal blood and may contribute to immediate energy for the enterocytes. In addition, the MCFA, similarly to the short-chain fatty acids (SCFA), possess antibacterial effects and may thereby prevent overgrowth of pathogenic bacteria in the gastrointestinal tract. The essential FA, linoleic (LA) and α-linolenic (ALA) FA, form the building blocks for the long-chain polyunsaturated n-3 and n-6 FA. The conversion of ALA and LA into n-3 and n-6 eicosanoids, respectively, influences the molecular structures of metabolites and inflammatory reactions and other immune responses upon bacterial challenges. Dietary manipulation of the lactating sow influences the transfer of the n-3 and n-6 polyunsaturated fatty acids (PUFA) from the sow milk to the piglet and the incorporation of the FA into piglet enteric tissues and cell membranes, which exerts bioactivity of importance for immune responses and the epithelial barrier function. Especially, the n-3 PUFA present in fish oil seem to influence the gut health and function of pigs, and this is of importance during the transition periods such as post-weaning in which piglets are prone to inflammation. The proportion of unsaturated FA in the cell membranes influences the susceptibility to oxidative stress. Oxidative stress accompanies infectious diseases, and the development of lipid peroxides and other reactive oxygen products may be harmful to the epithelial barrier function. Fatty acid peroxides from the feed may also be absorbed with other lipid-solubles and thereby harm the intestinal function. Hence, antioxidative protection is important for the enteric cells. In conclusion, manipulation of the dietary FA composition can influence the gut health and function in pigs and may support a normal immune system and modulate resistance to infectious diseases during especially stressful phases of a pig's life such as post-weaning.

Effects of dietary inulin supplementation on growth performance, intestinal barrier integrity and microbial populations in weaned pigs

Here, we explored the influences of dietary inulin (INU) supplementation on growth performance and intestinal health in a porcine model. Thirty-two male weaned pigs (with an average body weight of 7·10 (sd 0·20) kg) were randomly assigned to four treatments and fed with a basal diet (BD) or BD containing 2·5, 5·0 and 10·0 g/kg INU. After a 21-d trial, pigs were killed for collection of serum and intestinal tissues. We show that INU supplementation had no significant influence on the growth performance in weaned pigs. INU significantly elevated serum insulin-like growth factor-1 concentration but decreased diamine oxidase concentration (P < 0·05). Interestingly, 2·5 and 5·0 g/kg INU supplementation significantly elevated the villus height in jejunum and ileum (P < 0·05). Moreover, 2·5 and 5·0 g/kg INU supplementation also elevated the villus height to crypt depth (V:C) in the duodenum and ileum and improved the distribution and abundance of tight-junction protein zonula occludens-1 in duodenum and ileum epithelium. INU supplementation at 10·0 g/kg significantly elevated the sucrase activity in the ileum mucosa (P < 0·05). INU supplementation decreased the expression level of TNF-α but elevated the expression level of GLUT 2 and divalent metal transporter 1 in the intestinal mucosa (P < 0·05). Moreover, INU increased acetic and butyric acid concentrations in caecum (P < 0·05). Importantly, INU elevated the Lactobacillus population but decreased the Escherichia coli population in the caecum (P < 0·05). These results not only indicate a beneficial effect of INU on growth performance and intestinal barrier functions but also offer potential mechanisms behind the dietary fibre-regulated intestinal health.

Dietary Clostridium butyricum supplementation modifies significantly the liver transcriptomic profile in weaned piglets

The addition of probiotics in swine nutrition is known to positively influence both health and growth. The current study investigates differences in the hepatic transcriptome profiles between weaned piglets supplemented with Clostridium butyricum (C. butyricum) and control animals that received no probiotic. The liver is an important metabolic organ that plays a critical role in oxidizing triglycerides for energy production, lipid synthesis and degradation, as well as immune regulation in animals. RNA-Seq analysis was carried out on total RNA harvested from the liver of piglets fed with (n = 3) or without (n = 3) 5 × 10⁵ C. butyricum CFU/g. Compared to the control piglets, 588 of the genes examined (352 up-regulated and 236 down-regulated) were significantly differentially expressed at a fold change > 2 and p < .05 in animals fed with C. butyricum. Quantitative real-time reverse transcription PCR (qRT-PCR) analysis was further used to validate the microarray expression results for 28 genes tested. The functional annotation analyses revealed several genes, processes and pathways with putative involvement in piglet growth and performance. Feeding swine with 5 × 10⁵ C. butyricum CFU/g appears to reinforce their immune status as well as foster the cell cycle and improve the metabolism of carbohydrates, lipids and amino acids. This study provides valuable information about the expression profiles of mRNAs in piglet liver and in-depth functional investigations of these mRNAs that could provide new insights into the molecular networks of growth, immune responses and nutrient metabolism in the porcine liver.

Docosahexaenoate-enriched fish oil and medium chain triglycerides shape the feline plasma lipidome and synergistically decrease circulating gut microbiome-derived putrefactive postbiotics

The purpose of this study was to examine the influence of medium-chain fatty acid-containing triglycerides (MCT), long-chain polyunsaturated fatty acid-containing triglycerides, and their combination on the plasma metabolome of cats (Felis catus), including circulating microbiome-derived postbiotics. After a 14-day lead-in on the control food, cats were randomized to one of four foods (control, with 6.9% MCT, with fish oil [FO; 0.14% eicosapentaenoate, 1.0% docosahexaenoate], or with FO+MCT; n = 16 per group) for 28 days. Analysis of plasma metabolites showed that the addition of FO and MCT led to synergistic effects not seen with either alone across a number of lipid classes, including fatty acids, acylcarnitines, and acylated amines including endocannabinoids. Notably, the FO+MCT group had an increase in ketone body production relative to baseline and beyond that seen with MCT alone. N-acyl taurines, the accumulation of which has been implicated in the onset of type 2 diabetes, were significantly decreased in the FO+MCT group. Significant decreases in the gut microbiome-derived postbiotic classes of indoles/indolic sulfates and phenols/phenolic sulfates were observed only the FO+MCT group. Overall, the combination of MCT and FO led to number of changes in plasma metabolites that were not observed with either oil alone, particularly in postbiotics.

Lactobacillus delbrueckii Ameliorates Intestinal Integrity and Antioxidant Ability in Weaned Piglets after a Lipopolysaccharide Challenge

This study was conducted to evaluate the effect of dietary supplementation with Lactobacillus delbrueckii (LAB) on intestinal morphology, barrier function, immune response, and antioxidant capacity in weaned piglets challenged with lipopolysaccharide (LPS). A total of 36 two-line crossbred (Landrace × large Yorkshire) weaned piglets (28 days old) were divided into three groups: (1) nonchallenged control (CON); (2) LPS-challenged control (LPS); and (3) LAB+LPS treatment (0.2% LAB+LPS). Compared to the LPS piglets, the LAB+LPS piglets improved intestinal morphology, indicated by greater (P < 0.05) villus height in the duodenum and ileum; villus height : crypt depth ratio in the duodenum, jejunum, and ileum, as well as decreased (P < 0.05) crypt depth in the jejunum and ileum; and better intestinal barrier function, indicated by upregulated (P < 0.05) mRNA expression of tight junction proteins in the intestinal mucosa. Moreover, compared to the LPS piglets, LAB significantly decreased (P < 0.05) concentrations of TNF-α and IL-1β in the small intestine and increased (P < 0.05) IL-10 levels in the jejunum and ileum. Additionally, LAB increased (P < 0.05) T-AOC activities of the colon, GSH concentrations of the jejunum, and mRNA expression of CAT and Cu/Zn-SOD, while reduced (P < 0.05) MDA concentrations in the jejunum and ileum in LPS-changed piglets. Collectively, our results indicate that supplementation of LAB improved intestinal integrity and immune response and alleviated intestinal oxidative damage in LPS-challenged piglets.

Dietary flaxseed oil rich in omega-3 suppresses severity of type 2 diabetes mellitus via anti-inflammation and modulating gut microbiota in rats

BACKGROUND

Type 2 diabetes mellitus (T2DM) is closely associated with hyperglycemia, abnormal lipid profiles, chronic low-grade inflammation and gut dysbiosis. Dietary intervention plays a crucial role in the control of diabetes. Flaxseed oil (FO), a plant-derived omega-3 (ω-3) polyunsaturated fatty acids (PUFAs), is rich in α-linolenic acid (ALA) which has been proved to benefit for chronic metabolic disease. However, the exact effects of dietary FO on T2DM remains largely unclear.

METHODS

In the present study, SD rats were randomly allocated into four groups: pair-fed (PF) with corn oil (CO) group (PF/CO); DM with CO group (DM/CO); PF with FO group (PF/FO); DM with FO group (DM/FO). A diabetic rat model was generated by a single intraperitoneal injection of streptozotocin-nicotinamide (STZ-NA). After 5 weeks of intervention, rats were euthanized and associated indications were investigated.

RESULTS

Dietary FO significantly reduced fasting blood glucose (FBG), glycated hemoglobin (GHb), blood lipid, plasma lipopolysaccharide (LPS), interleukin (IL)-1β, tumor necrosis factor (TNF)-α, IL-6, IL-17A and malondialdehyde (MDA), compared to control group, respectively. Moreover, body mass (BM) and superoxide dismutase (SOD) in DM/FO group were dramatically increased respectively, compared with those in DM/CO group. But insulin (INS) and homeostasis model assessment of insulin resistance (HOMA-IR) remained no significant difference between DM/CO group and DM/FO group. Sequencing analysis of gut microbiota showed a reduction in the relative abundance of Firmicutes and Blautia, as well as a reduction in the ratio of Bacteroidetes-Firmicutes in DM/FO group compared to DM/CO group. An elevation in the relative abundance of Bacteroidetes and Alistipes were detected in DM/FO group. Acetic acid, propionic acid and butyric acid belonging to short chain fatty acids (SCFAs) as gut microbiota metabolites, were dramatically increased after FO intervention. Correlation analysis revealed that the relative abundance of Firmicutes and Blautia were positively correlated with IL-1β, TNF-α, IL-6, IL-17A or LPS, respectively. Additionally, Bacteroidetes and Alistipes were negatively correlated with LPS.

CONCLUSIONS

Taken together, dietary FO ameliorated T2DM via suppressing inflammation and modulating gut microbiota, which may potentially contribute to dietary control of diabetes.

Curcumin ameliorates oxidative stress-induced intestinal barrier injury and mitochondrial damage by promoting Parkin dependent mitophagy through AMPK-TFEB signal pathway

The gut epithelial is known as the most critical barrier for protection against harmful antigens and pathogens. Oxidative stress has been implicated in the dysfunction of the intestine barrier. Hence, effective and safe therapeutic approaches for maintaining intestinal redox balance are urgently needed. Curcumin has gained attention for its vast beneficial biological function via antioxidative stress. However, whether the curcumin can relief intestine damage and mitochondrial injury induced by oxidative stress is still unclear. In this study, we found that curcumin can effectively ameliorate hydrogen peroxide (H₂O₂)-induced oxidative stress, intestinal epithelial barrier injury and mitochondrial damage in porcine intestinal epithelial cells (IPEC-J2 cells) in a PTEN-induced putative kinase (PINK1)-Parkin mitophagy dependent way. Mechanistically, depletion of Parkin (a mitophagy related protein) abolished curcumin's protective action on anti-oxidative stress, improving intestinal barrier and mitochondrial function in porcine intestinal epithelial cells (IPEC-J2) induced by H₂O₂. Consistently, the protective effect of curcumin was not found in cells transfected with GFP-ParkinΔUBL, which encodes a mutant Parkin protein without the ubiquitin E3 ligase activity, indicating that the ubiquitin E3 ligase of Parkin is required for curcumin's protective effects. On the other hand, we also found that the protective function of curcumin was diminished when PRKAA1 was depleted in IPEC-J2 cells treated with H₂O₂. Immunofluorescence and luciferase assay showed that curcumin dramatically enhanced nuclear translocation and transcriptional activity of transcription factor EB (TFEB) in IPEC-J2 cells treated with H₂O₂, and it was ameliorated by co-treated with compound C, an Adenosine 5'-monophosphate (AMP)-activated protein kinase (AMPK) inhibitor, which means curcumin promotes TFEB transcript via AMPK signal pathway. Consistent with in vitro data, dietary curcumin protected intestinal barrier function, improved redox status, alleviated mitochondrial damage, triggered mitophagy and influenced AMPK-TFEB signal pathway in a well-established pig oxidative stress model by challenging with diquat. Taken together, these results unveil that curcumin ameliorates oxidative stress, enhances intestinal barrier function and mitochondrial function via the induction of Parkin dependent mitophagy through AMPK activation and subsequent TFEB nuclear translocation.

Activation of the NF-κB and MAPK Signaling Pathways Contributes to the Inflammatory Responses, but Not Cell Injury, in IPEC-1 Cells Challenged with Hydrogen Peroxide

Oxidative stress can lead to intestinal cell injury as well as the induction of inflammation. It is not clear whether inflammation is an important factor leading to cell injury caused by oxidative stress. The purpose of this study was to investigate the role of inflammation in intestinal injury caused by hydrogen peroxide (H₂O₂). Our results revealed that H₂O₂ stimulation significantly decreased the viability of intestinal porcine epithelial cells (IPEC-1), increased lactate dehydrogenase (LDH) activity, and disrupted the distribution of the tight junction protein claudin-1. H₂O₂ significantly increased the mRNA expression of interleukin-6 (IL-6), IL-8, and tumor necrosis factor-α (TNF-α). H₂O₂ stimulation also led to increased phosphorylation of p38 and jun N-terminal kinase (JNK), and p65 NF-κB protein translocation into the nucleus of IPEC-1 cells. Cells treated with the NF-κB inhibitor (BAY11-7082), the p38 inhibitor (SB202190), or the JNK inhibitor (PD98059) significantly decreased mRNA and protein expression of IL-6, IL-8, and TNF-α. However, treatment with mitogen-activated protein kinase (MAPK) or NF-κB inhibitors did not prevent the damage effect on cell viability, LDH activity, or the distribution of claudin-1 in cells challenged with H₂O₂. In summary, our data demonstrate that activation of the NF-κB and MAPK signaling pathways can contribute to the inflammatory response, but not cell injury, in IPEC-1 cells challenged with H₂O₂.