Butyrate transcriptionally enhances peptide transporter PepT1 expression and activity

Amyotrophic Lateral Sclerosis Pathoetiology and Pathophysiology: Roles of Astrocytes, Gut Microbiome, and Muscle Interactions via the Mitochondrial Melatonergic Pathway, with Disruption by Glyphosate-Based Herbicides

The pathoetiology and pathophysiology of motor neuron loss in amyotrophic lateral sclerosis (ALS) are still to be determined, with only a small percentage of ALS patients having a known genetic risk factor. The article looks to integrate wider bodies of data on the biological underpinnings of ALS, highlighting the integrative role of alterations in the mitochondrial melatonergic pathways and systemic factors regulating this pathway across a number of crucial hubs in ALS pathophysiology, namely glia, gut, and the muscle/neuromuscular junction. It is proposed that suppression of the mitochondrial melatonergic pathway underpins changes in muscle brain-derived neurotrophic factor, and its melatonergic pathway mimic, N-acetylserotonin, leading to a lack of metabolic trophic support at the neuromuscular junction. The attenuation of the melatonergic pathway in astrocytes prevents activation of toll-like receptor agonists-induced pro-inflammatory transcription factors, NF-kB, and yin yang 1, from having a built-in limitation on inflammatory induction that arises from their synchronized induction of melatonin release. Such maintained astrocyte activation, coupled with heightened microglia reactivity, is an important driver of motor neuron susceptibility in ALS. Two important systemic factors, gut dysbiosis/permeability and pineal melatonin mediate many of their beneficial effects via their capacity to upregulate the mitochondrial melatonergic pathway in central and systemic cells. The mitochondrial melatonergic pathway may be seen as a core aspect of cellular function, with its suppression increasing reactive oxygen species (ROS), leading to ROS-induced microRNAs, thereby altering the patterning of genes induced. It is proposed that the increased occupational risk of ALS in farmers, gardeners, and sportsmen and women is intimately linked to exposure, whilst being physically active, to the widely used glyphosate-based herbicides. This has numerous research and treatment implications.

Gut microbial response to host metabolic phenotypes

A large number of studies have proved that biological metabolic phenotypes exist objectively and are gradually recognized by humans. Gut microbes affect the host's metabolic phenotype. They directly or indirectly participate in host metabolism, physiology and immunity through changes in population structure, metabolite differences, signal transduction and gene expression. Obtaining comprehensive information and specific identification factors associated with gut microbiota and host metabolic phenotypes has become the focus of research in the field of gut microbes, and it has become possible to find new and effective ways to prevent or treat host metabolic diseases. In the future, precise treatment of gut microbes will become one of the new therapeutic strategies. This article reviews the content of gut microbes and carbohydrate, amino acid, lipid and nucleic acid metabolic phenotypes, including metabolic intermediates, mechanisms of action, latest research findings and treatment strategies, which will help to understand the relationship between gut microbes and host metabolic phenotypes and the current research status.

Molecular regulation after mucosal injury and regeneration in ulcerative colitis

Ulcerative colitis (UC) is a chronic nonspecific inflammatory disease with a complex etiology. Intestinal mucosal injury is an important pathological change in individuals with UC. Leucine-rich repeat-containing G protein-coupled receptor 5 (LGR5+) intestinal stem cells (ISCs) exhibit self-renewal and high differentiation potential and play important roles in the repair of intestinal mucosal injury. Moreover, LGR5+ ISCs are intricately regulated by both the Wnt/β-catenin and Notch signaling pathways, which jointly maintain the function of LGR5+ ISCs. Combination therapy targeting multiple signaling pathways and transplantation of LGR5+ ISCs may lead to the development of new clinical therapies for UC.

Effect of Tributyrin on Growth Performance and Pathway by which Tributyrin Regulates Oligopeptide Transporter 1 in Juvenile Grass Carp (Ctenopharyngodon idellus)

Simple Summary

Oligopeptide transporter 1 (PepT1) plays a role in the transportation and absorption of oligopeptides, which is an important part of protein nutrition and affects the growth of animals. Tributyrin (TB), the precursor of butyrate, exhibits similar functions to those of the butyrate in intestinal nutrients absorption. The analysis of TB on the growth of grass carp and its regulation pathway on PepT1 may help us to better understand the functions of TB and oligopeptide transportation via PepT1, which can be modulated by diet. In this study, we demonstrated that an appropriate level of tributyrin supplementation in the diet promoted the growth of juvenile grass carp and elevated the expressions of caudal type homeobox 2 (CDX2), specificity protein 1 (SP1), and PepT1 in the grass carp intestine and primary intestine cell. In addition, CDX2 and SP1 regulating the expression of PepT1 was investigated. Finally, CDX2/SP1-mediating tributyrin regulation on PepT1 was elucidated. This study verified the effect of tributyrin on the growth of juvenile grass carp and clarified the tributyrin regulation pathway on CDX2/SP1-PepT1.

Abstract

The nutritional functions of tributyrin (TB) have been extensively studied, but questions remain regarding its influence on the growth of juvenile grass carp (Ctenopharyngodon idellus) and the regulation pathway to PepT1 in the intestine of grass carp. To answer the remaining questions, feeding trials, cell trials, and peritoneal injection trials were conducted in this study. The results showed that an appropriate level of TB (0.5 g/kg and 1.0 g/kg) supplementation in feed significantly promoted the growth performance of juvenile grass carp. The expressions of intestine genes (CDX2, SP1 and PepT1) related to oligopeptide transportation increased in the 0.5 g/kg TB group of feeding trials and both the 5 mM and 10 mM TB groups of the intestine cell trials, respectively. Subsequently, the injection trials of inhibitors CDX2 and SP1 demonstrated that the inhibition of CDX2 or SP1 decreased the mRNA expression of PepT1. Finally, the results of independent or combined treatments of TB and the inhibitors suggested that CDX2/SP1 mediated TB regulation on PepT1. These findings may help us to better understand the functions of TB on growth and PepT1 oligopeptide transportation, which could be modulated by dietary TB through the CDX2/SP1-PepT1 pathway in juvenile grass carp.

Modulation of 1,2-Dicarbonyl Compounds in Postprandial Responses Mediated by Food Bioactive Components and Mediterranean Diet

Glycoxidative stress with the consequent generation of advanced glycation end products has been implied in the etiology of numerous non-communicable chronic diseases. During the postprandial state, the levels of 1,2-dicarbonyl compounds can increase, depending on numerous factors, including characteristics of the subjects mainly related to glucose metabolism disorders and nutritional status, as well as properties related to the chemical composition of meals, including macronutrient composition and the presence of dietary bioactive molecules and macromolecules. In this review, we examine the chemical, biochemical, and physiological pathways that contribute to postprandial generation of 1,2-dicarbonyl compounds. The modulation of postprandial 1,2-dicarbonyl compounds is discussed in terms of biochemical pathways regulating the levels of these compounds, as well as the effect of phenolic compounds, dietary fiber, and dietary patterns, such as Mediterranean and Western diets.

Probiotics as Alternatives to Antibiotics for the Prevention and Control of Necrotic Enteritis in Chickens

Necrotic enteritis (NE) in poultry is an economically important disease caused by Clostridium perfringens type A bacteria. A global trend on restricting the use of antibiotics as feed supplements in food animal production has caused a spike in the NE incidences in chickens, particularly in broiler populations. Amongst several non-antibiotic strategies for NE control tried so far, probiotics seem to offer promising avenues. The current review focuses on studies that have evaluated probiotic effects on C. perfringens growth and NE development. Several probiotic species, including Lactobacillus, Enterococcus, Bacillus, and Bacteroides bacteria as well as some yeast species have been tested in chickens against C. perfringens and NE development. These findings have shown to improve bird performance, reduce C. perfringens colonization and NE-associated pathology. The underlying probiotic mechanisms of NE control suggest that probiotics can help maintain a healthy gut microbial balance by modifying its composition, improve mucosal integrity by upregulating expression of tight-junction proteins, and modulate immune responses by downregulating expression of inflammatory cytokines. Collectively, these studies indicate that probiotics can offer a promising platform for NE control and that more investigations are needed to study whether these experimental probiotics can effectively prevent NE in commercial poultry operational settings.

The Effects of Different Forms of Butyric Acid on the Performance of Turkeys, Carcass Quality, Incidence of Footpad Dermatitis and Economic Efficiency

Simple Summary

Butyric acid is a short-chain organic acid with established antimicrobial properties. It decreases the pH of intestinal digesta and reduces the abundance of pathogenic bacteria, thus indirectly improving the growth performance of birds. In the present study, turkey diets were supplemented with different forms of butyric acid. The efficiency of bird production and carcass dressing percentage were improved when butyric acid glycerides or coated sodium butyrate were added to the diet. An improvement in footpad condition and an increase in the dry matter content of faeces were noted in birds fed experimental diets. The addition of butyric acid in various forms to turkey diets improved the economic efficiency of production. The results of this study suggest that different forms of butyric acid improve production efficiency, carcass traits, and footpad condition in turkeys. Therefore, sodium butyrate, coated sodium butyrate, and butyric acid glycerides can be valuable feed additives in turkey nutrition.

Abstract

The aim of this study was to compare the efficacy of butyric acid glycerides (BAG), sodium butyrate (SB) and coated sodium butyrate (CSB) in turkey nutrition based on the growth performance of birds, carcass yield, meat quality, the dry matter (DM) content of faeces, the incidence of footpad dermatitis (FPD), and economic efficiency. A 105-day experiment was conducted on 400 BIG 6 female turkeys (4 treatments, 5 replications, 20 birds per replication). The addition of CSB and BAG to turkey diets improved the feed conversion ratio (FCR, p ≤ 0.05) and increased the values of the European Efficiency Index (EEI, p ≤ 0.01). The analysed forms of BA in turkey diets increased the concentration of DM in faeces (p ≤ 0.01) and decreased FPD incidence (p ≤ 0.01), which may suggest that all forms of butyrate improved litter quality and inhibit the risk for diarrhoea. The results of this study indicate that all forms of butyric acid can be valuable feed additives in turkey nutrition.

Effects of Sophorolipid on Growth Performance, Organ Characteristics, Lipid Digestion Markers, and Gut Functionality and Integrity in Broiler Chickens

Simple Summary

Availability of dietary fat and oil is important to broiler chicken due to their rapid growth rate. Therefore, we conducted an experiment with dietary sophorolipid, a glycolipid-type emulsifier, to investigate growth, lipid digestion markers and gut health during the growing period. Growth was accelerated by dietary sophorolipid supplementation through upregulation of lipid digestion and absorption markers. Additionally, dietary sophorolipid also increased the surface area of the gut and modulated microbial population and short-chain fatty acid concentration. Collectively, this study proposed that sophorolipid addition in feed could enhance chicken’s growth by increased intestinal absorption of dietary lipid and improved gut microenvironments.

Abstract

Dietary fat and oil could aid in reaching the high-energy requirements of fast-growing birds; however, these inclusions could lead to nutrient waste. This is because young birds have limited lipid digestion due to the low secretion of lipase and bile salt. Sophorolipid (SPL), a glycolipid emulsifier with lower toxicity and higher biodegradability, can upregulate fat utilization by increasing digestibility. Accordingly, a five-week-long experiment was conducted with 720 one-day-old chicks (Ross 308) to investigate the effects of dietary SPL on growth, organ characteristics, and gut health. The allotment was partitioned into four treatment groups according to their body weight with six replications (30 chick/pen). The three treatment diets comprised a basal diet with a formulation that met the Ross 308 standard and 5, 10, and 15 ppm SPL in the basal diet. During the experiment, the birds had free access to feed, and body weight and feed intake were measured at the end of each phase. Chickens were put down at the end of the growing and finishing phases, and jejunum and cecal samples were obtained to investigate organ characteristics and gut environments. The data were analyzed using the generalized linear model procedures of SAS 9.4, and all data were assessed for linear, quadratic, and cubic effects of dietary SPL-supplemented dosages. Body weight was significantly increased with 10 ppm of SPL supplementation in the grower phase without affecting feed efficiency. The relative weights of the intestine and the bursa of Fabricius were quadratically decreased by SPL supplementation with a lower population of Streptococcus and higher propionate and butyrate concentrations. Additionally, the dietary SPL supplementation groups showed a significantly increased villus/crypt ratio with higher intestinal expression levels of fatty acid translocase, diacylglycerol acyltransferase 2, and fatty acid transporter 4. Collectively, proper SPL supplementation in the chicken diet could improve growth performance by down-regulating immune modulation and up-regulating lipid digestion and absorption via modulation of gut microenvironments.

Pilot Study on Poultry Meat from Antibiotic Free and Conventional Farms: Can Metagenomics Detect Any Difference?

Antibiotic free farms are increasing in the poultry sector in order to address new EU regulations and consumer concerns. In this pilot study, we investigated whether the efforts of raising chickens without the use antibiotics make any difference in the microbiome of poultry meat eaten by consumers. To this aim we compared the microbiomes characterizing caeca and the corresponding carcasses of two groups of chickens reared, one reared on a conventional farm and one on an antibiotic-free intensive farm. The results showed a clear separation between the taxonomic, functional and antibiotic resistant genes in the caeca of the birds reared on the conventional and antibiotic free farm. However, that separation was completely lost on carcasses belonging to the two groups. The antibiotic-free production resulted in statistically significant lower antimicrobial resistance load in the caeca in comparison to the conventional production. Moreover, the antimicrobial resistance load on carcasses was much higher than in the caeca, without any significant difference between carcasses coming from the two types of farms. All in all, the results of this research highlighted the need to reduce sources of microbial contamination and antimicrobial resistance not only at the farm level but also at the post-harvest one.

Effects of Clostridium butyricum, Sodium Butyrate, and Butyric Acid Glycerides on the Reproductive Performance, Egg Quality, Intestinal Health, and Offspring Performance of Yellow-Feathered Breeder Hens

Butyrate has been reported to promote the performance and growth of chickens. The specific roles and efficacy of different sources of butyrate remained unclear. Thus, the present study aimed to investigate and compare the effects of Clostridium butyricum (CB), sodium butyrate (SB), and butyric acid glycerides (tributyrin, BAG) on the reproductive performance, egg quality, intestinal health, and offspring performance of yellow-feathered breeder hens. A total of 300 Lingnan yellow-feathered breeder hens were assigned to five treatment groups: control (CL), 1×10⁸CFU/kg CB (CBL), 1×10⁹CFU/kg CB (CBH), 500mg/kg SB, and 300mg/kg BAG. Results showed that the laying performance and egg quality were increased by CBL, CBH, and BAG. Both CB treatments increased the hatchability of fertilized eggs. Maternal supplementation with both levels of CB significantly elevated the growth performance of offspring. Treatment with CBL, CBH, SB, and BAG all improved the oviduct-related variables and reduced the plasmal antioxidant variables. The CBH, CBL, and BAG treatments also improved the intestinal morphology to different degrees. Jejunal contents of IL-6 were decreased by CBH and BAG, while those of IL-4, IL-6, IL-1β, and IgY were decreased by SB. Transcripts of nutrient transporters in jejunal mucosa were also upregulated by CBH, CBL, and SB treatments and expression of Bcl-2-associated X protein was decreased by CBL, CBH, and BAG. In cecal contents, CBL increased the abundance of Firmicutes and Bacillus, while CBH decreased the abundance of Proteobacteria. Also, the co-occurrence networks of intestinal microbes were regulated by CBH and BAG. In conclusion, dietary inclusion of CB and BAG improved the reproductive parameters, egg quality, and intestinal morphology of breeders. CB also influenced the hatching performance of breeders and growth performance of the offspring, while SB improved the oviduct-related variables. These beneficial effects may result from the regulation of cytokines, nutrient transporters, apoptosis, and gut microbiota; high-level CB had more obvious impact. Further study is needed to explore and understand the correlation between the altered gut microbiota induced by butyrate and the performance, egg quality, intestinal health, and also offspring performance.

Comparison of Chicken Cecal Microbiota after Metaphylactic Treatment or Following Administration of Feed Additives in a Broiler Farm with Enterococcal Spondylitis History

Minimizing the clinical signs of Enterococcus cecorum infections causing enterococcal spondylitis in broiler herds is successful when initiated as metaphylaxis in the first week of life. Mechanistically, either the Enterococcus species present at that time are reduced by antibiotic treatment or antibiotic treatment might induce changes in intestinal microbiota composition with an indirect and subsequent influence. The aim of the present study was to examine the cecal microbiota of chickens after administering lincospectin or different additives to evaluate whether these additives have lincospectin-like effects on microbiota. Therefore, 157,400 broiler chickens were reared in four chicken houses (~40,000 birds each) on a broiler farm with history of enterococcal spondylitis. Each flock was treated either with lincospectin or water soluble esterified butyrins, Bacillus (B.) licheniformis or palm oil was added via drinking water during the first days of life. Ten birds per house were dissected at days 11, 20 and 33 of life and cecal microbiota were analyzed (16S rRNA gene sequencing). Lincospectin treatment elicited significant changes in the cecal microbiota composition until slaughter age. Among the tested additives, effects of B. licheniformis on cecal microbiota composition were most similar to those seen after the treatment with lincospectin at day 11.

Effect of dipeptide on intestinal peptide transporter 1 gene expression: An evaluation using primary cultured chicken intestinal epithelial cells

Peptide transporter 1 (PepT1) is a transporter responsible for absorbing dipeptide and tripeptide in enterocytes and is upregulated by dipeptide in mammals. It has not been certain whether intestinal PepT1 expression is responsive to dipeptides in chickens because of the lack of in vitro study using the cultured enterocytes. This study established a primary culture model of chicken intestinal epithelial cells (IECs) in two‐dimensional monolayer culture using collagen gel by which the response of chicken PepT1 gene expression to dipeptide stimuli was evaluated. The cultured chicken IECs showed the epithelial‐like morphology attached in a patch‐manner and exhibited positive expression of cytokeratin and epithelial cadherin, specific marker proteins of epithelial cells. Moreover, the chicken IECs exhibited the gene expression of intestinal cell type‐specific marker, villin1, mucin 2, and chromogranin A, suggesting that the cultured IECs were composed of enterocytes as well as goblet and enteroendocrine cells. PepT1 gene expression was significantly upregulated by synthetic dipeptide, glycyl‐l‐glutamine, in the cultured IECs. From the results, we herein suggested that dipeptide is a factor upregulating PepT1 gene expression in chicken IECs.

Gut microbiome responses in the metabolism of human dietary components: Implications in health and homeostasis

The gut microbiome and its link with human health and disease have gained a lot of attention recently. The microbiome executes its functions in the host by carrying out the transformation of dietary components and/or de novo synthesis of various essential nutrients. The presence of complex microbial communities makes it difficult to understand the host-microbiome interplay in the metabolism of dietary components. This review attempts to uncover the incredible role of the gut microbiome in the metabolism of dietary components, diet-microbiome interplay, and restoration of the microbiome. The in silico analysis performed in this study elucidates the functional description of essential/hub genes involved in the amino acid degradation pathway, which are mutually present in the host and its gut microbiome. Hence, the computational model helps comprehend the inter-and intracellular molecular networks between humans and their microbial partners.

Effects of Vitamin B2 Supplementation in Broilers Microbiota and Metabolome

The study of the microbiome in broiler chickens holds great promise for the development of strategies for health maintenance and performance improvement. Nutritional strategies aimed at modulating the microbiota-host relationship can improve chickens' immunological status and metabolic fitness. Here, we present the results of a pilot trial aimed at analyzing the effects of a nutritional strategy involving vitamin B2 supplementation on the ileum, caeca and litter microbiota of Ross 308 broilers, as well as on the metabolic profile of the caecal content. Three groups of chickens were administered control diets and diets supplemented with two different dosages of vitamin B2. Ileum, caeca, and litter samples were obtained from subgroups of birds at three time points along the productive cycle. Sequencing of the 16S rRNA V3-V4 region and NMR metabolomics were used to explore microbiota composition and the concentration of metabolites of interest, including short-chain fatty acids. Vitamin B2 supplementation significantly modulated caeca microbiota, with the highest dosage being more effective in increasing the abundance of health-promoting bacterial groups, including Bifidobacterium, resulting in boosted production of butyrate, a well-known health-promoting metabolite, in the caeca environment.

Integrating Autism Spectrum Disorder Pathophysiology: Mitochondria, Vitamin A, CD38, Oxytocin, Serotonin and Melatonergic Alterations in the Placenta and Gut

BACKGROUND

A diverse array of data has been associated with autism spectrum disorder (ASD), reflecting the complexity of its pathophysiology as well as its heterogeneity. Two important hubs have emerged, the placenta/prenatal period and the postnatal gut, with alterations in mitochondria functioning crucial in both.

METHODS

Factors acting to regulate mitochondria functioning in ASD across development are reviewed in this article.

RESULTS

Decreased vitamin A, and its retinoic acid metabolites, lead to a decrease in CD38 and associated changes that underpin a wide array of data on the biological underpinnings of ASD, including decreased oxytocin, with relevance both prenatally and in the gut. Decreased sirtuins, poly-ADP ribose polymerase-driven decreases in nicotinamide adenine dinucleotide (NAD+), hyperserotonemia, decreased monoamine oxidase, alterations in 14-3-3 proteins, microRNA alterations, dysregulated aryl hydrocarbon receptor activity, suboptimal mitochondria functioning, and decreases in the melatonergic pathways are intimately linked to this. Many of the above processes may be modulating, or mediated by, alterations in mitochondria functioning. Other bodies of data associated with ASD may also be incorporated within these basic processes, including how ASD risk factors such as maternal obesity and preeclampsia, as well as more general prenatal stressors, modulate the likelihood of offspring ASD.

CONCLUSION

Such a mitochondria-focussed integrated model of the pathophysiology of ASD has important preventative and treatment implications.

Effects of Tributyrin Supplementation on Growth Performance, Insulin, Blood Metabolites and Gut Microbiota in Weaned Piglets

Simple Summary

In animal farming, alternatives to antibiotics are required due to the increase of antimicrobial resistance. In this contest, tributyrin showed the ability to promote gut health, to modulate gut microbiota and to improve protein digestibility, leading also to higher growth performance. However, although the mode of action of tributyrin on the intestinal epithelial cells has been partially explained, its effects on lipid and protein metabolism needs to be investigated. This paper provides information about the influence of tributyrin on production traits, blood parameters, faecal microbiota and faecal protein excretion in weaned piglets.

Abstract

The aim of this study was to investigate the effects of tributyrin supplementation on the production traits, the main metabolic parameters and gut microbiota in weaned piglets. One hundred and twenty crossbred piglets (Large White × Landrace) were randomly divided into two experimental groups (six pens each; 10 piglets per pen): the control group (CTRL), that received a basal diet, and the tributyrin group (TRIB) that received the basal diet supplemented with 0.2% tributyrin. The experimental period lasted 40 days. Production traits were measured at days 14, 28 and 40. A subset composed of 48 animals (n = 4 for each pen; n = 24 per group) was considered for the evaluation of serum metabolic parameters and hair cortisol by enzyme-linked immunosorbent assay (ELISA), and faecal microbiota by real-time polymerase chain reaction (PCR). Our results showed that the treatment significantly increased body weight (BW) at day 28 and day 40 (p = 0.0279 and p = 0.0006, respectively) and average daily gain (ADG) from day 28 to day 40 (p = 0.046). Gain to feed ratio (G:F) was significantly higher throughout the experimental period (p = 0.049). Even if the serum parameters were in the physiological range, albumin, albumin/globulin (A/G) ratio, glucose and high-density lipoproteins (HDL) fraction were significantly higher in the TRIB group. On the contrary, tributyrin significantly decreased the urea blood concentration (p = 0.0026), which was correlated with lean gain and feed efficiency. Moreover, serum insulin concentration, which has a regulatory effect on protein and lipid metabolism, was significantly higher in the TRIB group (p = 0.0187). In conclusion, this study demonstrated that tributyrin can be considered as a valid feed additive for weaned piglets.

Saccharomyces boulardii CNCM I-745 probiotic does not alter the pharmacokinetics of amoxicillin

Background Probiotics are live microbial organisms that provide benefit to the host while co-habitating in the gastrointestinal tract. Probiotics are safe, available over the counter, and have clinical benefit by reducing the number of antibiotic-associated diarrhea days. Prescriptions from providers and direct consumer demand of probiotics appear to be on the rise. Several recent animal studies have demonstrated that probiotics may have significant effect on absorption of co-administered drugs. However, to date, most probiotic-drug interaction studies in animal models have been limited to bacterial probiotics and nonantibiotic drugs. Methods We performed a traditional pharmacokinetic mouse study examining the interactions between a common commercially available yeast probiotic, Saccharomyces boulardii CNCM I-745 (Florastor®) and an orally administered amoxicillin. Results We showed that there were no significant differences in pharmacokinetic parameters (half-life, area under the curve, peak concentrations, time to reach maximum concentration, elimination rate constant) of amoxicillin between the probiotic treated and untreated control groups. Conclusions Altogether, our findings suggest that coadministration or concurrent use of S. boulardii probiotic and amoxicillin would not likely alter the efficacy of amoxicillin therapy.

Effects of dietary tributyrin on intestinal mucosa development, mitochondrial function and AMPK-mTOR pathway in weaned pigs

Background

The objective of this experiment was to investigate the influence of dietary tributyrin on intestinal mucosa development, oxidative stress, mitochondrial function and AMPK-mTOR signaling pathway.

Methods

Seventy-two pigs were divided into two treatments and received either a basal diet or the same diet supplemented with 750 mg/kg tributyrin. Each treatment has six replicates of six pigs. After 14 days, 6 pigs from each treatment were selected and the jejunal samples were collected.

Results

Results showed that supplemental tributyrin increased (P < 0.05) villus height and villus height: crypt depth of weaned pigs. Pigs fed tributyrin had greater (P < 0.05) RNA/DNA and protein/DNA ratios than pigs on the control group. The mRNA levels of sodium glucose transport protein-1 and glucose transporter-2 in the jejunum were upregulated (P < 0.05) in pigs fed the tributyrin diet. Dietary tributyrin supplementation lowered (P < 0.05) the malondialdehyde and hydrogen peroxide (H₂O₂₎ content in jejunum, enhanced (P < 0.05) the mitochondrial function, as demonstrated by decreased (P < 0.05) reactive oxygen species level and increased (P < 0.05) mitochondrial membrane potential. Furthermore, tributyrin increased (P < 0.05) mitochondrial DNA content and the mRNA abundance of genes related to mitochondrial functions, including peroxisomal proliferator-activated receptor-γ coactivator-1α, mitochondrial transcription factor A, nuclear respiratory factor-1 in the jejunum. Supplementation with tributyrin elevated (P < 0.05) the phosphorylation level of AMPK and inhibited (P < 0.05) the phosphorylation level of mTOR in jejunum compared with the control group.

Conclusions

These findings suggest that dietary supplementation with tributyrin promotes intestinal mucosa growth, extenuates oxidative stress, improves mitochondrial function and modulates the AMPK-mTOR signal pathway of weaned pigs.

Slug and Snail have differential effects in directing colonic epithelial wound healing and partially mediate the restitutive effects of butyrate

Restitution of wounds in colonic epithelium is essential in the maintenance of health. Microbial products, such as the short-chain fatty acid butyrate, can have positive effects on wound healing. We used an in vitro model of T84 colonic epithelial cells to determine if the Snail genes Slug (SNAI2) and Snail (SNAI1), implemented in keratinocyte monolayer healing, are involved in butyrate-enhanced colonic epithelial wound healing. Using shRNA-mediated Slug/Snail knockdown, we found that knockdown of Slug (Slug-KD), but not Snail (Snail-KD), impairs wound healing in scratch assays with and without butyrate. Slug and Snail had differential effects on T84 monolayer barrier integrity, measured by transepithelial resistance, as Snail-KD impaired the barrier (with or without butyrate), whereas Slug-KD enhanced the barrier, again with or without butyrate. Targeted transcriptional analysis demonstrated differential expression of several tight junction genes, as well as focal adhesion genes. This included altered regulation of Annexin A2 and ITGB1 in Slug-KD, which was reflected in confocal microscopy, showing increased accumulation of B1-integrin protein in Slug-KD cells, which was previously shown to impair wound healing. Transcriptional analysis also indicated altered expression of genes associated with epithelial terminal differentiation, such that Slug-KD cells skewed toward overexpression of secretory cell pathway-associated genes. This included trefoil factors TFF1 and TFF3, which were expressed at lower than control levels in Snail-KD cells. Since TFFs can enhance the barrier in epithelial cells, this points to a potential mechanism of differential modulation by Snail genes. Although Snail genes are crucial in epithelial wound restitution, butyrate responses are mediated by other pathways as well.NEW & NOTEWORTHY Although butyrate can promote colonic mucosal healing, not all of its downstream pathways are understood. We show that the Snail genes Snail and Slug are mediators of butyrate responses. Furthermore, these genes, and Slug in particular, are necessary for efficient restitution of wounds and barriers in T84 epithelial cells even in the absence of butyrate. These effects are achieved in part through effects on regulation of β1 integrin and cellular differentiation state.

Effect of exogenous butyrate on the gastrointestinal tract of sheep. II. Hydrolytic activity in the rumen and structure and function of the small intestine

The aim of this study was to determine the effect of exogenous butyrate on the activity of carbohydrate-digesting enzymes in the reticuloruminal digesta and structure and selected functions of the small intestine in sheep. Eighteen rams (30.8 ± 2.1 kg; 12 to 15 mo of age) were fed for 14 d a diet without (CTRL) or with sodium butyrate (BUT; 36 g/kg of offered DM). Butyrate concentration in the reticuloruminal fluid and proximal small intestinal digesta was greater for BUT compared with CTRL (P ≤ 0.05). Amylolytic activity was greater, whereas cellulolytic and xylanolytic activity in the reticuloruminal digesta was less for BUT compared with CTRL (P ≤ 0.04). Relative to BW, small intestinal tissue mass and small intestine length did not differ between treatments (P ≥ 0.15); however, absolute length of the small intestine was greater for BUT compared with CTRL (P = 0.04). In the duodenum, crypt depth tended (P = 0.10) to be greater, whereas in the ileum, crypt depth and muscularis thickness tended (P = 0.10) to be less for BUT compared with CTRL. Mitosis-to-apoptosis ratio in the proximal jejunum was greater for CTRL compared with BUT (P = 0.02). Expression of G-protein-coupled receptor 43 mRNA in the duodenal epithelium was greater for BUT compared with CTRL (P < 0.01). On the other hand, peptide transporter 1 mRNA expression in the distal sections of the small intestine, as well as activity of aminopeptidase A and dipeptidylpeptidase IV, were greater for CTRL (P ≤ 0.05). In summary, exogenous butyrate supplementation in feed affects hydrolytic activity in the rumen, and increased butyrate flow out of the reticulorumen affects both proximal and distal sections of the small intestine in sheep.

Effect of exogenous butyrate on the gastrointestinal tract of sheep. I. Structure and function of the rumen, omasum, and abomasum

The aim of this study was to determine the effect of exogenous butyrate on the structure and selected functions of the stomach in sheep. Eighteen rams (30.8 ± 2.1 kg; 12 to 15 mo of age) were allocated to the study and fed a diet for 14 d without (CTRL) or with sodium butyrate (BUT; 36 g/kg of offered DM). Neither DMI nor initial BW differed between treatments (P ≥ 0.61), but final BW was greater for BUT compared with CTRL (P = 0.03). Butyrate concentration in the reticuloruminal fluid and abomasal digesta was greater for BUT compared with CTRL (P ≤ 0.01), but total short-chain fatty acids (SCFA) concentration, as well as concentration of other SCFA, did not differ between treatments (P ≥ 0.07). Relative to BW, reticuloruminal tissue mass tended (P = 0.09) to be greater and omasal digesta was less (P = 0.02) for BUT compared with CTRL. Dietary butyrate did not affect ruminal papillae length, width, and density nor did it affect ruminal epithelium thickness (P ≥ 0.12) in the ventral sac of the rumen. However, the DM of ruminal epithelium (mg/cm2) tended (P = 0.06) to be greater for BUT compared with CTRL. Omasal and abomasal epithelium thicknesses were greater (P ≤ 0.05) for BUT compared with CTRL. Mitosis-to-apoptosis ratio in the abomasal epithelium was less for BUT compared with CTRL (P = 0.04). Finally, the mRNA expression of peptide transporter 1 in the omasal epithelium was less (P = 0.02) and mRNA expression of monocarboxylate transporter 1 in the abomasal epithelium tended (P = 0.07) to be greater for BUT compared with CTRL. It can be concluded that exogenous butyrate supplementation affected not only the rumen but also omasum and abomasum in sheep.

Sodium Butyrate Enhances Intestinal Riboflavin Uptake via Induction of Expression of Riboflavin Transporter-3 (RFVT3)

BACKGROUND

Uptake of riboflavin (RF) by intestinal epithelial cells occurs via a specific carrier-mediated process that involves the apically localized RF transporter-3 (RFVT3). Previous studies have shown that sodium butyrate (NaB) affects intestinal uptake of other substrates and expression of their membrane transporters, but its effect on intestinal uptake of RF and expression of RFVT3 has not been examined.

AIMS

To investigate the effect of NaB on intestinal RF uptake process and expression of the RFVT3.

METHODS

Two experimental models were used in this study: Human-derived intestinal epithelial Caco-2 cells and ex vivo mouse colonoids. ³H-RF uptake assay, Western blot, RT-qPCR, and chromatin immunoprecipitation assay were performed.

RESULTS

Treating Caco-2 cells with NaB led to a significant increase in carrier-mediated RF uptake. This increase was associated with a significant induction in the level of expression of the hRFVT3 protein, mRNA, and heterogenous nuclear RNA (hnRNA). Similarly, treating mouse colonoids with NaB led to a marked increase in the level of expression of the mRFVT3 protein, mRNA, and hnRNA. NaB did not affect hRFVT3 mRNA stability, rather it caused significant epigenetic changes (histone modifications) in the SLC52A3 gene where an increase in H3Ac and a reduction in H3K27me3 levels were observed in the NaB-treated Caco-2 cells compared to untreated controls.

CONCLUSION

These findings demonstrate that NaB up-regulates intestinal RF uptake and that the effect appears to be mediated, at least in part, at the level of transcription of the SLC52A3 gene and may involve epigenetic mechanism(s).

Sodium butyrate improved performance while modulating the cecal microbiota and regulating the expression of intestinal immune-related genes of broiler chickens

This study evaluated the effect of sodium butyrate (SB) on performance, expression of immune-related genes in the cecal tonsils, and cecal microbiota of broiler chickens when dietary energy and amino acids concentrations were reduced. Day-old male Ross 708 broiler chicks were fed dietary treatments in a 3 × 2 factorial design (8 pens per treatment) with 3 dietary formulations (control diet; reduction of 2.3% of amino acids and 60 kcal/kg; and reduction of 4.6% of amino acids and 120 kcal/kg) with or without the inclusion of 0.1% of SB. Feed intake (FI), body weight gain (BW gain), and feed conversion ratio (FCR) were recorded until 28 d of age. From 14 to 28 d, there was an interaction of nutrient density by SB (P = 0.003) wherein BW gain of birds fed SB was impaired less by the energy/amino acids reduction than unsupplemented birds. A similar result was obtained from 1 to 28 d (P = 0.004). No interaction (P < 0.05) between nutrient density by SB was observed for FCR. Nutritional density of the diets and SB modified the structure, composition, and predicted function of the cecal microbiota. The nutritionally reduced diet altered the imputed function performed by the microbiota and the SB supplementation reduced these variations, keeping the microbial function similar to that observed in chickens fed a control diet. The frequency of bacterial species presenting the butyryl-CoA: acetate CoA-transferase gene increased in the microbiota of chickens fed a nutritionally reduced diet without SB supplementation, and was not changed by nutrient density of the diet when supplemented with SB (interaction; P = 0.01). SB modulated the expression of immune related genes in the cecal tonsils; wherein SB upregulated the expression of A20 in broilers fed control diets (P < 0.05) and increased IL-6 expression (P < 0.05). These results show that SB had positive effects on the productive performance of broilers fed nutritionally reduced diets, partially by modulating the cecal microbiota and exerting immune-modulatory effects.

Function, Regulation, and Pathophysiological Relevance of the POT Superfamily, Specifically PepT1 in Inflammatory Bowel Disease

Mammalian members of the proton-coupled oligopeptide transporter family are integral membrane proteins that mediate the cellular uptake of di/tripeptides and peptide-like drugs and couple substrate translocation to the movement of H⁺ , with the transmembrane electrochemical proton gradient providing the driving force. Peptide transporters are responsible for the (re)absorption of dietary and/or bacterial di- and tripeptides in the intestine and kidney and maintaining homeostasis of neuropeptides in the brain. These proteins additionally contribute to absorption of a number of pharmacologically important compounds. In this overview article, we have provided updated information on the structure, function, expression, localization, and activities of PepT1 (SLC15A1), PepT2 (SLC15A2), PhT1 (SLC15A4), and PhT2 (SLC15A3). Peptide transporters, in particular, PepT1 are discussed as drug-delivery systems in addition to their implications in health and disease. Particular emphasis has been placed on the involvement of PepT1 in the physiopathology of the gastrointestinal tract, specifically, its role in inflammatory bowel diseases. © 2018 American Physiological Society. Compr Physiol 8:731-760, 2018.

Effect of dietary supplementation with Lactobacillus acidophilus D2/CSL (CECT 4529) on caecum microbioma and productive performance in broiler chickens

This study examines the effects of the dietary supplementation with Lactobacillus acidophilus D2/CSL (CECT 4529) (LA) on productive performances, incidence of foot pad dermatitis and caecum microbioma in broiler chickens. A total of 1,100 one-day old male Ross 308 chicks were divided into 2 groups of 16 replicates with 25 birds each and reared from 1–41 d. One group was fed a basal diet (CON) and the other group the same diet supplemented with LA. Caecum contents were collected from 4 selected birds at day one and 5 selected birds at the end of the rearing period. Then, they were submitted to DNA extraction and whole DNA shotgun metagenomic sequencing. Overall, the LA supplementation produced a significant beneficial effect on body weight gain between 15–28 d and improved feed conversion rate in the overall period. On the contrary, litter moisture, pH and incidence of the foot pad lesions were not affected by LA. Birds treated with LA showed a lower occurrence of pasty vent at both 14 and 28 d. At the end of the rearing period, Lachanospiraceae were significantly higher in LA birds in comparison to CON (17.07 vs 14.39%; P = 0.036). Moreover, Ruminococcus obeum, Clostridium clostridioforme, Roseburia intestinalis, Lachnospiraceae bacterium 14-2T and Coprococcus eutactus were significantly higher in LA birds in comparison to CON. The relative abundance of Lactobacillus acidophilus was comparable between LA and CON groups. However, a positive effect was observed in relation to the metabolic functions in the treated group, with particular reference to the higher abundance of β-glucosidase. In conclusion, the LA supplementation improved broiler productive performances and metabolic functions promoting animal health.

Maternal Methyl Donor Supplementation during Gestation Counteracts the Bisphenol A-Induced Impairment of Intestinal Morphology, Disaccharidase Activity, and Nutrient Transporters Gene Expression in Newborn and Weaning Pigs

This study was conducted to explore whether exposure to bisphenol A (BPA) during pregnancy could change intestinal digestion and absorption function in offspring using pigs as a model, and whether methyl donor (MET) could counteract the BPA-induced impacts. Fifty Landrace × Yorkshire sows were divided into four dietary groups throughout gestation: control diet (CON); control diet supplemented with BPA (50 mg/kg); control diet supplemented with MET (3 g/kg betaine, 400 mg/kg choline, 150 μg/kg vitamin B12, and 15 mg/kg folic acid); and control diet with BPA and MET supplementation (BPA + MET). Intestine samples were collected from pigs’ offspring at birth and weaning. Maternal BPA exposure during pregnancy significantly reduced the ratio of jejunum villus height to crypt depth, decreased the jejunum sucrase activity, down-regulated the mRNA expression of jejunum peptide transporter 1 (Pept1) and DNA methyl transferase 3a (DNMT3a), and decreased the DNA methylation level of jejunum Pept1 in offspring (p < 0.05). Maternal MET supplementation significantly raised the ratio of villus height to crypt depth in jejunum and ileum, improved the jejunum lactase activity, up-regulated the mRNA expression of jejunum Pept1, lactase (LCT), DNMT1, DNMT3a, and methylenetetrahydrofolate reductase (MTHFR), and increased the DNA methylation level of jejunum Pept1 in offspring (p < 0.05). However, the ratio of jejunum villus height to crypt depth was higher in BPA + MET treatment compared with CON and BPA treatment (p < 0.05). Meanwhile, there was no difference in the jejunum sucrase activity, the mRNA expression of jejunum Pept1 and DNMT3a, and the DNA methylation level of jejunum Pept1 between CON and BPA + MET treatment. These results indicated that maternal exposure to BPA during gestation might suppress offspring’s intestinal digestion and absorption function, whereas supplementation of MET could counteract these damages, which might be associated with DNA methylation.

EMA and EFSA Joint Scientific Opinion on measures to reduce the need to use antimicrobial agents in animal husbandry in the European Union, and the resulting impacts on food safety (RONAFA)

EFSA and EMA have jointly reviewed measures taken in the EU to reduce the need for and use of antimicrobials in food-producing animals, and the resultant impacts on antimicrobial resistance (AMR). Reduction strategies have been implemented successfully in some Member States. Such strategies include national reduction targets, benchmarking of antimicrobial use, controls on prescribing and restrictions on use of specific critically important antimicrobials, together with improvements to animal husbandry and disease prevention and control measures. Due to the multiplicity of factors contributing to AMR, the impact of any single measure is difficult to quantify, although there is evidence of an association between reduction in antimicrobial use and reduced AMR. To minimise antimicrobial use, a multifaceted integrated approach should be implemented, adapted to local circumstances. Recommended options (non-prioritised) include: development of national strategies; harmonised systems for monitoring antimicrobial use and AMR development; establishing national targets for antimicrobial use reduction; use of on-farm health plans; increasing the responsibility of veterinarians for antimicrobial prescribing; training, education and raising public awareness; increasing the availability of rapid and reliable diagnostics; improving husbandry and management procedures for disease prevention and control; rethinking livestock production systems to reduce inherent disease risk. A limited number of studies provide robust evidence of alternatives to antimicrobials that positively influence health parameters. Possible alternatives include probiotics and prebiotics, competitive exclusion, bacteriophages, immunomodulators, organic acids and teat sealants. Development of a legislative framework that permits the use of specific products as alternatives should be considered. Further research to evaluate the potential of alternative farming systems on reducing AMR is also recommended. Animals suffering from bacterial infections should only be treated with antimicrobials based on veterinary diagnosis and prescription. Options should be reviewed to phase out most preventive use of antimicrobials and to reduce and refine metaphylaxis by applying recognised alternative measures.

Di- and tripeptide transport in vertebrates: the contribution of teleost fish models

Solute Carrier 15 (SLC15) family, alias H⁺-coupled oligopeptide cotransporter family, is a group of membrane transporters known for their role in the cellular uptake of di- and tripeptides (di/tripeptides) and peptide-like molecules. Of its members, SLC15A1 (PEPT1) chiefly mediates intestinal absorption of luminal di/tripeptides from dietary protein digestion, while SLC15A2 (PEPT2) mainly allows renal tubular reabsorption of di/tripeptides from ultrafiltration, SLC15A3 (PHT2) and SLC15A4 (PHT1) possibly interact with di/tripeptides and histidine in certain immune cells, and SLC15A5 has unknown function. Our understanding of this family in vertebrates has steadily increased, also due to the surge of genomic-to-functional information from 'non-conventional' animal models, livestock, poultry, and aquaculture fish species. Here, we review the literature on the SLC15 transporters in teleost fish with emphasis on SLC15A1 (PEPT1), one of the solute carriers better studied amongst teleost fish because of its relevance in animal nutrition. We report on the operativity of the transporter, the molecular diversity, and multiplicity of structural-functional solutions of the teleost fish orthologs with respect to higher vertebrates, its relevance at the intersection of the alimentary and osmoregulative functions of the gut, its response under various physiological states and dietary solicitations, and its possible involvement in examples of total body plasticity, such as growth and compensatory growth. By a comparative approach, we also review the few studies in teleost fish on SLC15A2 (PEPT2), SLC15A4 (PHT1), and SLC15A3 (PHT2). By representing the contribution of teleost fish to the knowledge of the physiology of di/tripeptide transport and transporters, we aim to fill the gap between higher and lower vertebrates.

Nod2: A Critical Regulator of Ileal Microbiota and Crohn's Disease

The human intestinal tract harbors large bacterial community consisting of commensal, symbiotic, and pathogenic strains, which are constantly interacting with the intestinal immune system. This interaction elicits a non-pathological basal level of immune responses and contributes to shaping both the intestinal immune system and bacterial community. Recent studies on human microbiota are revealing the critical role of intestinal bacterial community in the pathogenesis of both systemic and intestinal diseases, including Crohn’s disease (CD). NOD2 plays a key role in the regulation of microbiota in the small intestine. NOD2 is highly expressed in ileal Paneth cells that provide critical mechanism for the regulation of ileal microbiota through the secretion of anti-bacterial compounds. Genome mapping of CD patients revealed that loss of function mutations in NOD2 are associated with ileal CD. Genome-wide association studies further demonstrated that NOD2 is one of the most critical genetic factor linked to ileal CD. The bacterial community in the ileum is indeed dysregulated in Nod2-deficient mice. Nod2-deficient ileal epithelia exhibit impaired ability of killing bacteria. Thus, altered interactions between ileal microbiota and mucosal immunity through NOD2 mutations play significant roles in the disease susceptibility and pathogenesis in CD patients, thereby depicting NOD2 as a critical regulator of ileal microbiota and CD.

Diet structure, butyric acid, and fermentable carbohydrates influence growth performance, gut morphology, and cecal fermentation characteristics in broilers

An experiment with 288 male (Ross 308) 1-d-old broilers was conducted to test the hypothesis that a coarse diet supplemented with butyric acid (BA) and fermentable carbohydrates (FC) improves performance of broilers with a poorly digestible protein source. The interaction effects of diet structure (fine or coarse), FC supplementation (with or without), and BA supplementation (with or without) in a poorly digestible diet based on rapeseed meal (RSM) were tested in a factorial arrangement of 8 (2×2×2) dietary treatments. The coarseness of the diet affected feed intake (FI) (P<0.001), BW gain (P=0.001), and the feed conversion ratio (FCR) (P=0.001) positively. Broilers fed the coarse diets had, on average, 14% heavier gizzards and 11, 7, 5, and 6% lower relative empty weights of the crop, duodenum, jejunum, and ileum, respectively, compared with those fed the fine diets. Dietary coarseness resulted in, on average, 6% greater ileal protein digestibility, 20% lower gizzard pH, 19% greater villus height, 18% lower crypt depth, and 23% reduced cecal branched chain fatty acids (BCFA) compared with chickens fed the fine diets. Broilers fed BA-supplemented diets had an improved FCR (P=0.004) and decreased crypt depth (P<0.001) compared with those fed diets without BA. Fermentable carbohydrate supplementation did not influence growth performance, gut development, or contents of total BCFA and total biogenic amines in the cecal digesta (P>0.05). Supplementation with FC, however, decreased the cecal concentration of spermine by approximately 31% compared with broilers fed diets without FC (P=0.002). In conclusion, feeding a coarse diet supplemented with BA improved performance of broilers fed a diet containing a poorly digestible protein source. The negative effects of a poorly digestible protein source can thus be partly counterbalanced by coarse grinding and BA supplementation in the diet.

Use of sodium butyrate as an alternative to dietary fiber: effects on the embryonic development and anti-oxidative capacity of rats

In this study, we evaluated the effect of replacing dietary fiber with sodium butyrate on reproductive performance and antioxidant defense in a high fat diet during pregnancy by using a rat model. Eighty virgin female Sprague Dawley rats were fed one of four diets—(1) control diet (C group), (2) high fat + high fiber diet (HF group), (3) high-fat +5% sodium butyrate diet (SB group), and (4) HF diet + α-cyano-4-hydroxy cinnamic acid (CHC group)—intraperitoneally on days 8, 10, 12, 14, and 16 of gestation. SB and dietary fiber had similar effects on improving fetal number and reducing the abortion rate; however, the anti-oxidant capacity of maternal serum, placenta, and fetus was superior in the HF group than in the SB group. In comparison, CHC injection decreased reproductive performance and antioxidant defense. Both dietary fiber (DF) and SB supplementation had a major but different effect on the expression of anti-oxidant related genes and nutrient transporters genes. In summary, our data indicate that SB and DF showed similar effect on reproductive performance, but SB cannot completely replace the DF towards with respect to redox regulation in high-fat diet; and SB might influence offspring metabolism and health differently to DF.

Characterization and dietary regulation of oligopeptide transporter (PepT1) in different ploidy fishes

The oligopeptide transporter (PepT1) is located on the brush-border membrane of the intestinal epithelium which has been regarded as a mediator of protein absorption. Here, we cloned and characterized PepT1 genes from diploid (red crucian carp), triploid and tetraploid fish. Then, the PepT1 expression pattern in different tissues and embryogenesis were assayed. Meanwhile, using real-time PCR and western blotting, we showed the expression profiles of diets with different protein levels, protein sources and additives (sodium butyrate) in triploids. The cDNAs of the three different ploidy fishes have a high sequence similarity of PepT1 among vertebrates. PepT1 mRNA expression was also developmentally regulated and showed the strongest expression around the 2-cell and 4-cell stage in all three kinds of fishes. The maternal transcripts were first detected in eggs and dropped from blastula stage to muscle contraction stage. Tissue expression studies showed higher expression of PepT1 genes in the intestines of fishes compared with other tissues. In adults, triploids showed significantly higher expression levels of PepT1 in the intestines of the three kinds of ploidy fishes during breeding season and non-breeding season. In addition, high or low protein level diets both promote PepT1 expression in the intestine. We also confirmed that fish meal showed a significant increase in PepT1 expression than soybean meal in triploid intestines. Furthermore, sodium butyrate additives induce PepT1 expression that may be mediated by CDX2 and CREB. This research provides a new insight into protein absorption and its regulation in triploid fish.

Nrf2 regulates the expression of the peptide transporter PEPT1 in the human colon carcinoma cell line Caco-2

BACKGROUND

PEPT1 is a rheogenic transport protein in the apical membrane of intestinal epithelial cells capable of transporting essentially all possible di- and tripeptides that are generated from the luminal protein breakdown. In addition, several anticancer, antimicrobial and antiviral drugs are taken up from the intestinal lumen via PEPT1 and therefore PEPT1 is a target for efficient drug delivery via prodrug approaches. Thus, understanding PEPT1 gene regulation is not only of importance for dietary adaptation but also for drug treatment.

METHODS

In silico analysis of the Pept1 promoter was performed using MatInspector. Pept1 promoter constructs were generated and cotransfected with an Nrf2 expression plasmid. Caco-2 cells were stimulated with Nrf2 inducers followed by electrophoretic mobility shift assay (EMSA) and chromatin immunoprecipitation (ChIP). Biological relevance was investigated using western blot analysis and transport activity assays.

RESULTS

Reporter gene assays showed transcriptional activation of the Pept1 promoter in response to Nrf2 overexpression. EMSA as well as ChIP analysis validated Nrf2 binding to the ARE located closest to the start codon (Pept1-ARE1). Induction of the Nrf2 pathway resulted in increased endogenous PEPT1 protein abundance as well as transport activity. Moreover, we demonstrate that also the induction of autophagy by MG132 resulted in elevated Nrf2 binding to Pept1-ARE1 and increased PEPT1 protein expression.

CONCLUSION

In summary, we identified a biologically active Nrf2 binding site within the Pept1 promoter which links Pept1 to the cellular defense program activated by Nrf2.

GENERAL SIGNIFICANCE

This study identifies Pept1 as an inducible target gene of the Nrf2 pathway.

Transcriptional and functional regulation of the intestinal peptide transporter PEPT1

Dietary proteins are cleaved within the intestinal lumen to oligopeptides which are further processed to small peptides (di- and tripeptides) and free amino acids. Although the transport of amino acids is mediated by several specific amino acid transporters, the proton-coupled uptake of the more than 8000 different di- and tripeptides is performed by the high-capacity/low-affinity peptide transporter isoform PEPT1 (SLC15A1). Its wide substrate tolerance also allows the transport of a repertoire of structurally closely related compounds and drugs, which explains their high oral bioavailability and brings PEPT1 into focus for medical and pharmaceutical approaches. Although the first evidence for the interplay of nutrient supply and PEPT1 expression and function was described over 20 years ago, many aspects of the molecular processes controlling its transcription and translation and modifying its transporter properties are still awaiting discovery. The present review summarizes the recent knowledge on the factors modulating PEPT1 expression and function in Caenorhabditis elegans, Danio rerio, Mus musculus and Homo sapiens, with focus on dietary ingredients, transcription factors and functional modulators, such as the sodium-proton exchanger NHE3 and selected scaffold proteins.

Dietary inhibitors of histone deacetylases in intestinal immunity and homeostasis

Intestinal epithelial cells (IECs) are integral players in homeostasis of immunity and host defense in the gut and are under influence of the intestinal microbiome. Microbial metabolites and dietary components, including short chain fatty acids (acetate, propionate, and butyrate, SCFAs), have an impact on the physiology of IECs at multiple levels, including the inhibition of deacetylases affecting chromatin remodeling and global changes in transcriptional activity. The number and diversity of butyrate-producing bacteria is subject to factors related to age, disease, and to diet. At physiological levels, SCFAs are inhibitors of histone deacetylases (HDACs) which may explain the transcriptional effects of SCFAs on epithelial cells, although many effects of SCFAs on colonic mucosa can be ascribed to mechanisms beyond HDAC inhibition. Interference with this type of post-translational modification has great potential in cancer and different inflammatory diseases, because HDAC inhibition has anti-proliferative and anti-inflammatory effects in vitro, and in in vivo models of intestinal inflammation. Hence, the influence of dietary modulators on HDAC activity in epithelia is likely to be an important determinant of its responses to inflammatory and microbial challenges.

Butyrate produced by commensal bacteria potentiates phorbol esters induced AP-1 response in human intestinal epithelial cells

The human intestine is a balanced ecosystem well suited for bacterial survival, colonization and growth, which has evolved to be beneficial both for the host and the commensal bacteria. Here, we investigated the effect of bacterial metabolites produced by commensal bacteria on AP-1 signaling pathway, which has a plethora of effects on host physiology. Using intestinal epithelial cell lines, HT-29 and Caco-2, stably transfected with AP-1-dependent luciferase reporter gene, we tested the effect of culture supernatant from 49 commensal strains. We observed that several bacteria were able to activate the AP-1 pathway and this was correlated to the amount of short chain fatty acids (SCFAs) produced. Besides being a major source of energy for epithelial cells, SCFAs have been shown to regulate several signaling pathways in these cells. We show that propionate and butyrate are potent activators of the AP-1 pathway, butyrate being the more efficient of the two. We also observed a strong synergistic activation of AP-1 pathway when using butyrate with PMA, a PKC activator. Moreover, butyrate enhanced the PMA-induced expression of c-fos and ERK1/2 phosphorylation, but not p38 and JNK. In conclusion, we showed that SCFAs especially butyrate regulate the AP-1 signaling pathway, a feature that may contribute to the physiological impact of the gut microbiota on the host. Our results provide support for the involvement of butyrate in modulating the action of PKC in colon cancer cells.

The role and pathophysiological relevance of membrane transporter PepT1 in intestinal inflammation and inflammatory bowel disease

Intestinal inflammation is characterized by epithelial disruption, leading to loss of barrier function and the recruitment of immune cells, including neutrophils. Although the mechanisms are not yet completely understood, interactions between environmental and immunological factors are thought to be critical in the initiation and progression of intestinal inflammation. In recent years, it has become apparent that the di/tripeptide transporter PepT1 may play an important role in the pathogenesis of such inflammation. In healthy individuals, PepT1 is primarily expressed in the small intestine and transports di/tripeptides for metabolic purposes. However, during chronic inflammation such as that associated with inflammatory bowel disease, PepT1 expression is upregulated in the colon, wherein the protein is normally expressed either minimally or not at all. Several recent studies have shown that PepT1 binds to and transports various bacterial di/tripeptides into colon cells, leading to activation of downstream proinflammatory responses via peptide interactions with innate immune receptors. In the present review, we examine the relationship between colonic PepT1-mediated peptide transport in the colon and activation of innate immune responses during disease. It is important to understand the mechanisms of PepT1 action during chronic intestinal inflammation to develop future therapies addressing inappropriate immune activation in the colon.

Fermentation in the human large intestine: its physiologic consequences and the potential contribution of prebiotics

The human large intestine harbors a complex microbiota containing many hundreds of different bacterial species. Although structure/function relationships between different components of the microbiota are unclear, this complex multicellular entity plays an important role in maintaining homeostasis in the body. Many of the physiologic properties of the microbiota can be attributed to fermentation and the production of short-chain fatty acids (SCFAs), particularly acetate, propionate, and butyrate. In healthy people, fermentation processes are largely controlled by the amounts and different types of substrate, particularly complex carbohydrates that are accessible to bacteria in the colonic ecosystem. However, other factors impact on bacterial metabolism in the large gut, including large bowel transit time, the availability of inorganic terminal electron acceptors, such as nitrate and sulfate, and gut pH. They all affect the types and levels of SCFA that can be formed by the microbiota. This is important because to a large extent, acetate, propionate, and butyrate have varying physiologic effects in different body tissues. Prebiotics such as galactooligosaccharides together with inulins and their fructooligosaccharide derivatives have been shown to modify the species composition of the colonic microbiota, and in various degrees, to manifest several health-promoting properties related to enhanced mineral absorption, laxation, potential anticancer properties, lipid metabolism, and anti-inflammatory and other immune effects, including atopic disease. Many of these phenomena can be linked to their digestion and SCFA production by bacteria in the large gut.

Impaired carbohydrate digestion and transport and mucosal dysbiosis in the intestines of children with autism and gastrointestinal disturbances

Gastrointestinal disturbances are commonly reported in children with autism, complicate clinical management, and may contribute to behavioral impairment. Reports of deficiencies in disaccharidase enzymatic activity and of beneficial responses to probiotic and dietary therapies led us to survey gene expression and the mucoepithelial microbiota in intestinal biopsies from children with autism and gastrointestinal disease and children with gastrointestinal disease alone. Ileal transcripts encoding disaccharidases and hexose transporters were deficient in children with autism, indicating impairment of the primary pathway for carbohydrate digestion and transport in enterocytes. Deficient expression of these enzymes and transporters was associated with expression of the intestinal transcription factor, CDX2. Metagenomic analysis of intestinal bacteria revealed compositional dysbiosis manifest as decreases in Bacteroidetes, increases in the ratio of Firmicutes to Bacteroidetes, and increases in Betaproteobacteria. Expression levels of disaccharidases and transporters were associated with the abundance of affected bacterial phylotypes. These results indicate a relationship between human intestinal gene expression and bacterial community structure and may provide insights into the pathophysiology of gastrointestinal disturbances in children with autism.

Differentiating passive from transporter-mediated uptake by PepT1: a comparison and evaluation of four methods

BACKGROUND

To quantify transmembrane transport of dipeptides by PepT1, passive uptake (non-PepT1 mediated) must be subtracted from total (measured) uptake. Three methods have been described to estimate passive uptake: perform experiments at cold temperatures, inhibit target dipeptide uptake with a greater concentration of a second dipeptide, or use modified Michaelis-Menten kinetics. We hypothesized that performing uptake experiments at pH 8.0 would estimate passive uptake accurately, because PepT1 requires a proton gradient. Our aim was to determine the most accurate method to estimate passive uptake.

METHODS

Caco-2 cells were incubated with various concentrations of glycyl-sarcosine (gly-sar) at pH 6.0 and at 37°C to measure total uptake. Passive uptake was estimated: (1) by incubating Caco-2 cells with varying concentrations of gly-sar at 4°C, (2) in the presence of 50 mM glycyl-leucine, (3) in solution at pH 8.0, or (4) using modified Michaelis-Menten kinetics. PepT1-mediated uptake was calculated by subtracting passive uptake from total uptake. K(m), V(max), and % gly-sar transported by PepT1 were calculated and compared.

RESULTS

K(m), V(max), and % gly-sar transported by PepT1 varied from 0.7 to 2.4 mM, 8.4 to 21.0 nmol/mg protein/10 min, and 69% to 87%, respectively. Uptakes calculated with cold, 50 mM gly-leu and using modified Michaelis-Menten kinetics were similar but differed significantly from uptake at pH 8.0 (P < 0.001).

CONCLUSIONS

Estimating passive uptake at pH 8.0 does not appear to be accurate. Measuring uptake at cold temperatures or in the presence of a greater concentration of a second dipeptide, and confirming results with modified Michaelis-Menten kinetics is recommended.