Dietary Tryptophan Supplementation Improves Antioxidant Status and Alleviates Inflammation, Endoplasmic Reticulum Stress, Apoptosis, and Pyroptosis in the Intestine of Piglets after Lipopolysaccharide Challenge

Dietary α-Ketoglutarate Alleviates Escherichia coli LPS-Induced Intestinal Barrier Injury by Modulating the Endoplasmic Reticulum-Mitochondrial System Pathway in Piglets

BACKGROUND

α-Ketoglutarate (AKG) plays a pivotal role in mitigating inflammation and enhancing intestinal health.

OBJECTIVES

This study aimed to investigate whether AKG could protect against lipopolysaccharide (LPS)-induced intestinal injury by alleviating disorders in mitochondria-associated endoplasmic reticulum (MAM) membranes, dysfunctional mitochondrial dynamics, and endoplasmic reticulum (ER) stress in a piglet model.

METHODS

Twenty-four piglets were subjected to a 2 × 2 factorial design with dietary factors (basal diet or 1% AKG diet) and LPS treatment (LPS or saline). After 21 d of consuming either the basal diet or AKG diet, piglets received injections of LPS or saline. The experiment was divided into 4 treatment groups [control (CON) group: basal diet + saline; LPS group: basal diet +LPS; AKG group: AKG diet + saline; and AKG_LPS group: AKG + LPS], each consisting of 6 piglets.

RESULTS

The results demonstrated that compared with the CON group, AKG enhanced jejunal morphology, antioxidant capacity, and the messenger RNA and protein expression of tight junction proteins. Moreover, it has shown a reduction in serum diamine oxidase activity and D-lactic acid content in piglets. In addition, fewer disorders in the ER-mitochondrial system were reflected by AKG, as evidenced by AKG regulating the expression of key molecules of mitochondrial dynamics (mitochondrial calcium uniporter, optic atrophy 1, fission 1, and dynamin-related protein 1), ER stress [activating transcription factor (ATF) 4, ATF 6, CCAAT/enhancer binding protein homologous protein, eukaryotic initiation factor 2α, glucose-regulated protein (GRP) 78, and protein kinase R-like ER kinase], and MAM membranes [mitofusin (Mfn)-1, Mfn-2, GRP 75, and voltage-dependent anion channel-1].

CONCLUSIONS

Dietary AKG can prevent mitochondrial dynamic dysfunction, ER stress, and MAM membrane disorder, ultimately alleviating LPS-induced intestinal damage in piglets.

Uncovering the mechanism of Clostridium butyricum CBX 2021 to improve pig health based on in vivo and in vitro studies

Introduction

As a symbiotic probiotic for the host, Clostridium butyricum (CB) has the potential to strengthen the body's immune system and improve intestinal health. However, the probiotic mechanism of CB is not completely understood. The Clostridium butyricum CBX 2021 strain isolated by our team from a health pig independently exhibits strong butyric acid production ability and stress resistance. Therefore, this study comprehensively investigated the efficacy of CBX 2021 in pigs and its mechanism of improving pig health.

Methods

In this study, we systematically revealed the probiotic effect and potential mechanism of the strain by using various methods such as microbiome, metabolites and transcriptome through animal experiments in vivo and cell experiments in vitro.

Results

Our in vivo study showed that CBX 2021 improved growth indicators such as daily weight gain in weaned piglets and also reduced diarrhea rates. Meanwhile, CBX 2021 significantly increased immunoglobulin levels in piglets, reduced contents of inflammatory factors and improved the intestinal barrier. Subsequently, 16S rRNA sequencing showed that CBX 2021 treatment implanted more butyric acid-producing bacteria (such as Faecalibacterium) in piglets and reduced the number of potentially pathogenic bacteria (like Rikenellaceae RC9_gut_group). With significant changes in the microbial community, CBX 2021 improved tryptophan metabolism and several alkaloids synthesis in piglets. Further in vitro experiments showed that CBX 2021 adhesion directly promoted the proliferation of a porcine intestinal epithelial cell line (IPEC-J2). Moreover, transcriptome analysis revealed that bacterial adhesion increased the expression of intracellular G protein-coupled receptors, inhibited the Notch signaling pathway, and led to a decrease in intracellular pro-inflammatory molecules.

Discussion

These results suggest that CBX 2021 may accelerate piglet growth by optimizing the intestinal microbiota, improving metabolic function and enhancing intestinal health.

Enhancing chronic wound healing with Thai indigenous rice variety, Kaab Dum: Exploring ER stress and senescence inhibition in HaCaT keratinocyte cell line

Kaab Dum, a prominent indigenous rice variety cultivated in the Pak Phanang Basin of Nakhon Si Thammarat, Thailand, is the focus of our study. We investigate the therapeutic potential of indigenous Kaab Dum rice extract in the context of chronic wounds. Our research encompasses an examination of the nutritional compositions and chemical profiles of Kaab Dum rice extract. Additionally, we assess how the extract affects chronic wounds in TGF-β-induced HaCaT cells. Our evaluation methods include the detection of cellular oxidative stress, the examination of endoplasmic reticulum (ER) stress, wound healing assays, analysis of cell cycle arrest and the study of cellular senescence through senescence-associated β-galactosidase (SA-β-gal) staining. Our research findings demonstrate that TGF-β induces oxidative stress in HaCaT cells, which subsequently triggers ER stress, confirmed by the expression of the PERK protein. This ER stress results in cell cycle arrest in HaCaT cells, characterized by an increase in p21 protein, a cyclin-dependent kinase inhibitor (CDKI). Ultimately, this leads to cellular senescence, as confirmed by SA-β-gal staining. Importantly, our study reveals the effectiveness of Kaab Dum rice extract in promoting wound healing in the chronic wound model. The extract reduces ER stress and senescent cells. These beneficial effects are potentially linked to the antioxidant and anti-inflammatory properties of the rice extract. The findings of our study have the potential to make significant contributions to the development of enhanced products for both the prevention and treatment of chronic wounds.

Bacillus amyloliquefaciens attenuates the intestinal permeability, oxidative stress and endoplasmic reticulum stress: transcriptome and microbiome analyses in weaned piglets

Endoplasmic reticulum (ER) stress is related to oxidative stress (OS) and leads to intestinal injury. Bacillus amyloliquefaciens SC06 (SC06) can regulate OS, but its roles in intestinal ER stress remains unclear. Using a 2 × 2 factorial design, 32 weaned piglets were treated by two SC06 levels (0 or 1 × 108 CFU/g), either with or without diquat (DQ) injection. We found that SC06 increased growth performance, decreased ileal permeability, OS and ER stress in DQ-treated piglets. Transcriptome showed that differentially expressed genes (DEGs) induced by DQ were enriched in NF-κB signaling pathway. DEGs between DQ- and SC06 + DQ-treated piglets were enriched in glutathione metabolism pathway. Ileal microbiome revealed that the SC06 + DQ treatment decreased Clostridium and increased Actinobacillus. Correlations were found between microbiota and ER stress genes. In conclusion, dietary SC06 supplementation increased the performance, decreased the permeability, OS and ER stress in weaned piglets by regulating ileal genes and microbiota.

Effects of dietary N-carbamylglutamate supplementation on the modulation of microbiota and Th17/Treg balance-related immune signaling after lipopolysaccharide challenge

BACKGROUND

This study aimed to evaluate the effects of N-carbamylglutamate (NCG) on piglets' growth performance and immune response, and to unravel the mechanisms of such effects. In a 2 × 2 factorial design including diet (with or without NCG) and immunological challenge (saline or lipopolysaccharide (LPS)), 24 piglets were randomly distributed into four groups. After being fed a basic diet or a NCG-supplemented diet for 21 days, piglets were administered LPS or saline intraperitoneally.

RESULTS

The results showed that NCG increased the average daily gain and average daily feed intake, and the feed conversion ratio of piglets, and alleviated the adverse effects of LPS stimulation on intestinal morphology. At the phylum level, NCG reversed the increase in the abundance of Firmicutes and the reduction in that of Actinomycete caused by LPS stimulation. At the genus level, NCG increased the abundance of Lactobacillus, Blautia, norank_Butyricicoccaceae, Subdoligranulum, and Ruminococcus_gauvreauii_group, and LPS decreased the abundance of Escherichia-Shigella and Ruminococcus_gauvreauii_group. The short-chain fatty acid content was increased by NCG, but LPS reduced its content. N-Carbamylglutamate also inhibited significantly the LPS-induced increase in the relative expression of signal transducer and activator of transcription (STAT) 3, related orphan receptor (RAR) c, and pro-inflammatory cytokines, and the decrease in the relative expression of STAT5, forkhead box P3, IL-10 and transforming growth factor beta 1 mRNA. A significant correlation was found between intestinal microbiota and inflammatory cytokines and short-chain fatty acids.

CONCLUSION

N-Carbamylglutamate can improve piglets' growth performance. It can also attenuate LPS-induced intestinal inflammation by modulating microbiota and Th17/Treg balance-related immune signaling pathways. © 2023 Society of Chemical Industry.

Amino acids in piglet diarrhea: Effects, mechanisms and insights

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

Intestinal tryptophan metabolism in disease prevention and swine production

Tryptophan (Trp) is an essential amino acid that cannot be synthesized by animals. It has been characterized into two different isomers, levorotation-Trp (L-Trp) and dextrorotation-Trp (D-Trp), based on their distinct molecule orientation. Intestinal epithelial cells and gut microbiota are involved in metabolizing L-Trp in the gut via the activation of the kynurenine, serotonin, and indole pathways. However, knowledge regarding D-Trp metabolism in the gut remains unclear. In this review, we briefly update the current understanding of intestinal L/D-Trp metabolism and the function of their metabolites in modulating the gut physiology and diseases. Finally, we summarize the effects of Trp nutrition on swine production at different stages, including growth performance in weaned piglets and growing pigs, as well as the reproduction performance in sows.

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

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

Tryptophan alleviates intestinal damage through regulating necroptosis and TLR4/NOD signaling pathways in pigs after lipopolysaccharide challenge

This study aimed to test the hypothesis that necroptosis, toll-like receptor 4 (TLR4)/nucleotide-binding oligomerization domain (NOD) signaling pathway in the jejunum of lipopolysaccharide (LPS)-challenged piglets are involved in the alleviation of intestinal injury and inflammation by tryptophan supplementation. Tryptophan supplementation has improved intestinal morphology. Also, tryptophan has been found to increase the mRNA and protein expression of tight junction proteins and decrease the expression of pro-inflammatory cytokines. Dietary tryptophan decreased the mRNA expression of heat shock protein 70, TLR4, NOD1, NOD2, myeloid differentiation primary response gene 88, interleukin 1 receptor-associated kinase 1, TNF receptor-associated factor 6, receptor-interacting serine/threonine-protein kinase 2-like, nuclear factor-kappaB transcription factor P65 in the jejunum of piglets. Tryptophan alleviated LPS-induced necroptosis and decreased the mRNA expression of mixed lineage kinase domain-like, receptor-interacting serine/threonine kinase 1, receptor-interacting serine/threonine-protein kinase 3-like, Fas (TNFRSF6)-associated via death domain, PGAM family member 5. Collectively, our results suggest that tryptophan supplementation helps in the attenuation of intestinal injury and inflammation by alleviating necroptosis and TLR4/NOD in lipopolysaccharide-challenged pigs.

Galacto-Oligosaccharides Alleviate LPS-Induced Immune Imbalance in Small Intestine through Regulating Gut Microbe Composition and Bile Acid Pool

Recent evidence suggests that the protective effect of gut microbiota on intestinal inflammation can be achieved through a microbe-bile acids (BAs) mechanism. Galacto-oligosaccharides (GOS) are a kind of prebiotic that alter gut microbiota composition. To verify whether GOS has a protective effect on intestinal inflammation through a microbe-BAs mechanism, this research was performed in a lipopolysaccharide (LPS) porcine model with the presence or absence of GOS. GOS prevented LPS-induced production of pro-inflammatory cytokines, the decrease of bacterial bile salt hydrolase-containing bacteria abundance, and the decrease of chendoxycholic acid (CDCA) level in piglets. Additionally, CDCA decreased LPS-induced production of pro-inflammatory cytokines, induced the expression of the takeda G-protein receptor 5 (TGR5), and its downstream cyclic adenosine monophosphate (cAMP) production in lamina propria-derived CD11b+ cells. The cAMP inhibitor eliminated the protective effect of CDCA on lamina propria-derived CD11b+ cells. These results suggested that GOS reduced the production of pro-inflammatory cytokines and inhibited NF-κB activation via microbe-BA-dependent TGR5-cAMP signaling in LPS-challenged piglets.

The Effect of Prebiotic Supplements on the Gastrointestinal Microbiota and Associated Health Parameters in Pigs

Establishing a balanced and diverse microbiota in the GIT of pigs is crucial for optimizing health and performance throughout the production cycle. The post-weaning period is a critical phase, as it is often associated with dysbiosis, intestinal dysfunction and poor performance. Traditionally, intestinal dysfunctions associated with weaning have been alleviated using antibiotics and/or antimicrobials. However, increasing concerns regarding the prevalence of antimicrobial-resistant bacteria has prompted an industry-wide drive towards identifying natural sustainable dietary alternatives. Modulating the microbiota through dietary intervention can improve animal health by increasing the production of health-promoting metabolites associated with the improved microbiota, while limiting the establishment and proliferation of pathogenic bacteria. Prebiotics are a class of bioactive compounds that resist digestion by gastrointestinal enzymes, but which can still be utilized by beneficial microbes within the GIT. Prebiotics are a substrate for these beneficial microbes and therefore enhance their proliferation and abundance, leading to the increased production of health-promoting metabolites and suppression of pathogenic proliferation in the GIT. There are a vast range of prebiotics, including carbohydrates such as non-digestible oligosaccharides, beta-glucans, resistant starch, and inulin. Furthermore, the definition of a prebiotic has recently expanded to include novel prebiotics such as peptides and amino acids. A novel class of -biotics, referred to as "stimbiotics", was recently suggested. This bioactive group has microbiota-modulating capabilities and promotes increases in short-chain fatty acid (SCFA) production in a disproportionally greater manner than if they were merely substrates for bacterial fermentation. The aim of this review is to characterize the different prebiotics, detail the current understating of stimbiotics, and outline how supplementation to pigs at different stages of development and production can potentially modulate the GIT microbiota and subsequently improve the health and performance of animals.

Perinatal exposure to high concentration glyphosate-based herbicides induces intestinal apoptosis by activating endoplasmic reticulum stress in offspring

Glyphosate-based herbicides (GBHs), the most widely used pesticide worldwide, have been reported to impair organ function in humans and animals. However, research on the effect of maternal GBHs exposure on the intestinal health of offspring has received little attention. Based on the glyphosate limits defined by Codex Alimentarius Commission and European Food Safety Authority, this study established pregnant sow exposure models to investigate the influence of low (L-GBHs, 20 mg/kg) and high concentration GBHs (H-GBHs, 100 mg/kg) on the intestinal health of offspring and proposed the protective mechanism mediated by betaine. The results showed that the intestinal morphology and barrier function of suckling piglets were damaged in the H-GBHs group. H-GBHs increased the activity of glutathione peroxidase (GPX) and levels of methane dicarboxylic aldehyde (MDA), hydrogen peroxide (H₂O₂) and inflammatory factors (tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), interleukin-6 (IL-6), interleukin-10 (IL-10)) in suckling piglets and activated Nrf2-mediated antioxidant signaling pathway. Subsequently, we found that exposure to H-GBHs triggered endoplasmic reticulum stress (ERS) and further induced apoptosis by upregulating the expression of Bcl-2-associated X protein (Bax), Caspase3, Caspase9 and Caspase12. Moreover, H-GBHs exposure perturbed mitochondrial membrane fusion and electron transport in mitochondrial respiratory chains by increasing the mRNA expression of mitofusin-2 (MFN2) and succinate dehydrogenase subunit A (SDHA), causing mitochondrial dysfunction. Dietary supplementation with betaine provided modest protection against GBHs-induced intestinal damage in suckling piglets. These findings reveal the mechanism of GBHs-induced intestinal damage in offspring, improving our understanding of the risk of GBHs exposure in pregnant women and suggesting the potential protective effects of betaine against GBHs poisoning.

Dietary tryptophan supplementation enhances mitochondrial function and reduces pyroptosis in the spleen and thymus of piglets after lipopolysaccharide challenge

The thymus and spleen, the main reservoirs for T lymphocytes, modulate the innate immune response. Oxidative stress, excessive inflammation and abnormal pyroptosis can cause dysfunction of these organs. This study aimed to examine whether tryptophan supplementation can improve growth performance and mitochondrial function via the adenosine 5'-monophosphate-activated protein kinase (AMPK)/sirtuin1 (Sirt1)/peroxisome proliferator-activated receptor-γ coactivator-1α (PGC1α) signalling pathway and decrease pyroptosis via the nucleotidebinding oligomerisation domain-like receptor protein 3 (NLRP3)/caspase-1/gasderminD (GSDMD) signalling pathway in the spleen and thymus of piglets after lipopolysaccharide (LPS) challenge. Eighteen weaned piglets were allotted to three treatment groups: non-challenged control, LPS-challenged control and LPS + 0.2% tryptophan. On day 35, the pigs in the LPS and LPS + 0.2% tryptophan groups were injected with 100 μg/kg BW LPS, whereas those in the control group were administered with sterile saline. At 4 h postchallenge, the weaned piglets were sacrificed, and their thymuses and spleens were collected. Results showed that tryptophan enhanced growth performance and antioxidant status by increasing catalase, glutathione peroxidase and total superoxide dismutase activities and decreasing malondialdehyde and reactive oxygen species contents. Tryptophan also reduced the mRNA levels of proinflammatory cytokine genes and enhanced mitochondrial function by increasing the mRNA levels of mitochondrial transcription factor A, nuclear respiratory factor-1, mitochondria transcription factor B1, AMPKα1, AMPKα2, Sirt1 and PGC1α and the protein expression of phosphorylated AMPK, Sirt1 and PGC1α. It also reduced pyroptosis by decreasing the mRNA levels of NLRP3, apoptosis-associated speck-like protein containing CARD, caspase-1 and GSDMD and the protein expression of NLRP3, caspase-1 and GSDMD. These results indicate that tryptophan supplementation enhances growth performance and mitochondrial function via the AMPK/Sirt1/PGC1α signalling pathway and decreases pyroptosis via the NLRP3/caspase-1/GSDMD signalling pathway in the spleen and thymus of LPS-challenged piglets.

Glutathione Protects against Paraquat-Induced Oxidative Stress by Regulating Intestinal Barrier, Antioxidant Capacity, and CAR Signaling Pathway in Weaned Piglets

Endogenous glutathione (GSH) effectively regulates redox homeostasis in the body. This study aimed to investigate the regulatory mechanism of different dietary levels of GSH supplementation on the intestinal barrier and antioxidant function in a paraquat-induced stress-weaned piglet model. Our results showed that dietary 0.06% GSH supplementation improved the growth performance of weaned piglets under normal and stressful conditions to some degree and decreased the diarrhea rate throughout. Exogenous GSH improved paraquat-induced changes in intestinal morphology, organelle, and permeability and reduced intestinal epithelial cell apoptosis. Moreover, GSH treatment alleviated intestinal oxidative stress damage by upregulating antioxidant (GPX4, CnZnSOD, GCLC, and GCLM) and anti-inflammatory (IL-10) gene expression and downregulating inflammatory cytokines (IFN-γ and IL-12) gene expression. Furthermore, GSH significantly reduced the expression levels of constitutive androstane receptor (CAR), RXRα, HSP90, PP2Ac, CYP2B22, and CYP3A29, and increased the expression levels of GSTA1 and GSTA2 in the jejunum and ileum of paraquat-induced piglets. We conclude that exogenous GSH protects against oxidative stress damage by regulating the intestinal barrier, antioxidant capacity, and CAR signaling pathway.

Tryptophan Supplementation Enhances Intestinal Health by Improving Gut Barrier Function, Alleviating Inflammation, and Modulating Intestinal Microbiome in Lipopolysaccharide-Challenged Piglets

Tryptophan (Trp) can modify the gut microbiota. However, there is no information about the effect of Trp on intestinal microbiota after lipopolysaccharide (LPS) challenge. This study aimed to investigate the effect of Trp on intestinal barrier function, inflammation, antioxidant status, and microbiota in LPS-challenged piglets. A total of 18 weaned castrated piglets were randomly divided into three treatments with 6 replicate per treatment, namely, (i) non-challenged control (CON); (ii) LPS-challenged control (LPS-CON); and (iii) LPS + 0.2% Trp (LPS-Trp). After feeding with control or 0.2% tryptophan-supplemented diets for 35 days, pigs were intraperitoneally injected with LPS (100 μg/kg body weight) or saline. At 4 h post-challenge, all pigs were slaughtered, and colonic samples were collected. The samples were analyzed for gut microbiota, fatty acids, antioxidant parameters, and the expression of mRNA and protein. The community bar chart showed that Trp supplementation to LPS-challenged pigs increased the relative abundance of Anaerostipes (P < 0.05) and tended to increase the relative abundance of V9D2013_group (P = 0.09), while decreased the relative abundance of Corynebacterium (P < 0.05) and unclassified_c__Bacteroidia (P < 0.01). Gas chromatography showed that Trp increased the concentrations of acetate, propionate, butyrate, and isovalerate in the colonic digesta (P < 0.05). Trp reduced the mRNA level of pro-inflammatory cytokines (P < 0.01), and increased mRNA level of aryl hydrocarbon receptor, cytochrome P450 (CYP) 1A1 and CYP1B1 (P < 0.05). Correlation analysis results showed that acetate, propionate, and butyrate concentrations were positively correlated with mRNA level of occludin and CYP1B1 (P < 0.05), and were negatively correlated with pro-inflammatory cytokines gene expression (P < 0.05). Isovalerate concentration was positively correlated with catalase activity (P < 0.05), and was negatively correlated with pro-inflammatory cytokines gene expression (P < 0.05). Furthermore, Trp enhanced the antioxidant activities (P < 0.01), and increased mRNA and protein expressions of claudin-1, occludin, and zonula occludens-1 (P < 0.01) after LPS challenge. These results suggest that Trp enhanced intestinal health by a modulated intestinal microbiota composition, improved the short chain fatty acids synthesis, reduced inflammation, increased antioxidant capacity, and improved intestinal barrier function.