Dietary fructooligosaccharides increase intestinal permeability in rats

Breaking the Barrier: The Role of Gut Epithelial Permeability in the Pathogenesis of Hypertension

PURPOSE OF THE REVIEW

To review what intestinal permeability is and how it is measured, and to summarise the current evidence linking altered intestinal permeability with the development of hypertension.

RECENT FINDINGS

Increased gastrointestinal permeability, directly measured in vivo, has been demonstrated in experimental and genetic animal models of hypertension. This is consistent with the passage of microbial substances to the systemic circulation and the activation of inflammatory pathways. Evidence for increased gut permeability in human hypertension has been reliant of a handful of blood biomarkers, with no studies directly measuring gut permeability in hypertensive cohorts. There is emerging literature that some of these putative biomarkers may not accurately reflect permeability of the gastrointestinal tract. Data from animal models of hypertension support they have increased gut permeability; however, there is a dearth of conclusive evidence in humans. Future studies are needed that directly measure intestinal permeability in people with hypertension.

Beyond Auto-Brewery: Why Dysbiosis and the Legalome Matter to Forensic and Legal Psychology

International studies have linked the consumption of ultra-processed foods with a variety of non-communicable diseases. Included in this growing body of research is evidence linking ultra-processed foods to mental disorders, aggression, and antisocial behavior. Although the idea that dietary patterns and various nutrients or additives can influence brain and behavior has a long history in criminology, in the absence of plausible mechanisms and convincing intervention trials, the topic was mostly excluded from mainstream discourse. The emergence of research across nutritional neuroscience and nutritional psychology/psychiatry, combined with mechanistic bench science, and human intervention trials, has provided support to epidemiological findings, and legitimacy to the concept of nutritional criminology. Among the emergent research, microbiome sciences have illuminated mechanistic pathways linking various socioeconomic and environmental factors, including the consumption of ultra-processed foods, with aggression and antisocial behavior. Here in this review, we examine this burgeoning research, including that related to ultra-processed food addiction, and explore its relevance across the criminal justice spectrum—from prevention to intervention—and in courtroom considerations of diminished capacity. We use auto-brewery syndrome as an example of intersecting diet and gut microbiome science that has been used to refute mens rea in criminal charges. The legalome—microbiome and omics science applied in forensic and legal psychology—appears set to emerge as an important consideration in matters of criminology, law, and justice.

Soluble Dietary Fibers as Antihyperlipidemic Agents: A Comprehensive Review to Maximize Their Health Benefits

The number of hypercholesterolemic people is increasing rapidly worldwide, with elevated lipid profiles representing a major risk factor of coronary heart diseases. Dietary intervention was shown to improve the lipid profile, thus enhancing the quality of life. Dietary fiber is a nondigestible form of carbohydrates, due to the lack of the digestive enzyme in humans required to digest fiber, and is classified according to its water solubility properties as either soluble (SDF) or insoluble dietary fiber (IDF). Consumption of SDF is associated with several health benefits such as reduced lipid levels, lower blood pressure, improved blood glucose control, improved immune function, and reduced inflammation. SDF has been shown to lower blood cholesterol by several action mechanisms including directly due to the gelling, mucilaginous, and viscous fiber nature, and indirectly due to its fermented products and modulation of the gut microbiome. This review aims to provide a holistic overview on how SDF impacts the lipid profile. We start by providing an overview of the chemical structure of the major SDFs including mucilage, gums (gum arabic and guar gum), pectin, and inulin.

Neonatal necrotizing enterocolitis: Clostridium butyricum and Clostridium neonatale fermentation metabolism and enteropathogenicity

Bacterial colonization in the gut plays a pivotal role in neonatal necrotizing enterocolitis (NEC) development, but the relationship between bacteria and NEC remains unclear. In this study, we aimed to elucidate whether bacterial butyrate end-fermentation metabolites participate in the development of NEC lesions and confirm the enteropathogenicity of Clostridium butyricum and Clostridium neonatale in NEC. First, we produced C.butyricum and C.neonatale strains impaired in butyrate production by genetically inactivating the hbd gene encoding β-hydroxybutyryl-CoA dehydrogenase that produces end-fermentation metabolites. Second, we evaluated the enteropathogenicty of the hbd-knockout strains in a gnotobiotic quail model of NEC. The analyses showed that animals harboring these strains had significantly fewer and less intense intestinal lesions than those harboring the respective wild-type strains. In the absence of specific biological markers of NEC, the data provide original and new mechanistic insights into the disease pathophysiology, a necessary step for developing potential novel therapies.

Direct Action of Non-Digestible Oligosaccharides against a Leaky Gut

The epithelial monolayer is the primary determinant of mucosal barrier function, and tight junction (TJ) complexes seal the paracellular space between the adjacent epithelial cells and represent the main "gate-keepers" of the paracellular route. Impaired TJ functionality results in increased permeation of the "pro-inflammatory" luminal contents to the circulation that induces local and systemic inflammatory and immune responses, ultimately triggering and/or perpetuating (chronic) systemic inflammatory disorders. Increased gut leakiness is associated with intestinal and systemic disease states such as inflammatory bowel disease and neurodegenerative diseases such as Parkinson's disease. Modulation of TJ dynamics is an appealing strategy aiming at inflammatory conditions associated with compromised intestinal epithelial function. Recently there has been a growing interest in nutraceuticals, particularly in non-digestible oligosaccharides (NDOs). NDOs confer innumerable health benefits via microbiome-shaping and gut microbiota-related immune responses, including enhancement of epithelial barrier integrity. Emerging evidence supports that NDOs also exert health-beneficial effects on microbiota independently via direct interactions with intestinal epithelial and immune cells. Among these valuable features, NDOs promote barrier function by directly regulating TJs via AMPK-, PKC-, MAPK-, and TLR-associated pathways. This review provides a comprehensive overview of the epithelial barrier-protective effects of different NDOs with a special focus on their microbiota-independent modulation of TJs.

A proof of principle study investigating the effects of supplemental concentrated brewer's yeast on markers of gut permeability, inflammation, and fecal metabolites in healthy non-challenged adult sled dogs

Yeast-derived β-glucans impact immunity, though their effects on gut permeability and inflammation are less understood. Most research has investigated other components of the yeast cell wall, such as the prebiotic mannan- and fructo-oligosaccharides. The objective of this study was to assess the effects of feeding a concentrated yeast product on markers of inflammation (serum amyloid A [SAA] and haptoglobin [Hp]) and oxidative status (malondialdehyde [MDA]), fecal products of fermentation, and gut permeability. Nineteen privately owned domestic Siberian huskies, and one Alaskan husky (9 females: 5 intact, 4 spayed; 11 males: 3 intact, 8 neutered), with an average age of 4.8 ± 2.6 yr and body weight (BW) of 25.6 ± 4.1 kg, were used in this study. Dogs were blocked and randomly allocated to one of two diet groups. Ten dogs received a dry extruded diet. The other 10 received the same diet top dressed with yeast for a daily β-glucan dose of 7 mg/kg BW for 10 wk. Fecal collection, for evaluation of fecal metabolites, and scoring occurred weekly. Gut permeability was assessed using the chromium-labeled ethylenediamine tetra-acetic acid (Cr-EDTA) and iohexol markers prior to the initiation of dietary treatment and after 10 wk of treatment. Blood samples were collected premarker administration and 0.5, 1, 2, 3, 4, 5, and 6 h postadministration. Fasting concentrations of SAA, Hp, and MDA were measured on weeks -1, 2, 4, and 8. Incremental area under the curve (I-AUC) was calculated for serum iohexol and Cr-EDTA concentrations. All data were analyzed using PROC GLIMMIX of SAS with dog as random effect, and week as fixed effect and repeated measure. Dogs receiving treatment tended to have decreased I-AUC of Iohexol (P = 0.10) and Cr-EDTA (P = 0.06) between baseline and cessation of treatment compared to the change over time in I-AUC for control (Ctl) dogs. Treatment dogs had lower Hp concentrations (P ≤ 0.05) than Ctl. There were no differences between treatments for SAA and MDA concentrations (P > 0.05). Fecal arabinose concentrations were greater in treatment (Trt) dogs (P ≤ 0.05) compared to Ctl, though no other fecal metabolites were affected by treatment. There was no difference in the relative frequency of defecations scored at any fecal score between Trt and Ctl dogs, and mean score did not differ between groups (P > 0.10). These data suggest that concentrated brewer's yeast may have the potential to reduce gut permeability without impacting inflammatory status and markers of health in adult dogs.

Supplementing oat hulls to the diet of suckling piglets altered their intestinal tract and colonic microbiota development

Current study evaluated the effect of a fine and coarsely ground insoluble dietary fibre source on the gastrointestinal development of suckling pigs. Oat hulls (OH) were selected as a model feedstuff, rich in cellulose, lignin, and insoluble dietary fibre. Three experimental supplemental diets were formulated: a finely ground, low fibre and nutrient dense diet served as control (CON). For the 2 high fibre diets, 15% heat-treated starch in CON was exchanged with OH, either finely (OH-f) or coarsely ground (OH-c). Litters of 10 primi- and multiparous sows (mean litter size 14.6 ± 0.84) were used. Within a litter, experimental diets were allotted to triplets of 4 piglets. From approximately 12 d of age, piglets' individual feed intakes were recorded 2 times per day when separated from their dam for 70 min. Piglets could suckle with their dam for the remainder of the day. On d 24 and 25, from the total pool of 120 piglets, seven healthy well-eating piglets per treatment were selected for post-mortem evaluation, resulting in 14 replicates per treatment. Consumption of OH-c and OH-f did not impede clinical health and production performance of piglets. The full stomach weights tended to be greater for OH-c compared to OH-f whereas CON was intermediate (P = 0.083). Supplementing OH significantly increased ileal villus height and caecal dry matter concentration (P < 0.05). For the colon, OH increased its length, contents weight, short-chain fatty acid concentration and reduced total bacterial count as well as γ-proteobacteria count and proportion (P < 0.05). The OH-c treatment specifically increased full gastrointestinal tract weight and caecum contents weight compared to piglets fed CON and OH-f. Furthermore, OH-c reduced colonic crypt depth when compared to OH-f (P = 0.018). In conclusion, supplementing OH to a diet for suckling piglets exerted subtle developmental effects on gastrointestinal morphology and colonic microbial community. These effects were largely independent from the particle size of the OH.

Immunization of Broiler Chickens With a Killed Chitosan Nanoparticle Salmonella Vaccine Decreases Salmonella Enterica Serovar Enteritidis Load

There is a critical need for an oral-killed Salmonella vaccine for broilers. Chitosan nanoparticle (CNP) vaccines can be used to deliver Salmonella antigens orally. We investigated the efficacy of a killed Salmonella CNP vaccine on broilers. CNP vaccine was synthesized using Salmonella enterica serovar Enteritidis (S. Enteritidis) outer membrane and flagella proteins. CNP was stable at acidic conditions by releasing 14% of proteins at pH 5.5. At 17 h post-incubation, the cumulative protein release for CNP was 75% at pH 7.4. Two hundred microliters of PBS with chicken red blood cells incubated with 20 μg/ml CNP released 0% hemoglobin. Three hundred chicks were allocated into 1) Control, 2) Challenge, 3) Vaccine + Challenge. At d1 of age, chicks were spray-vaccinated with PBS or 40 mg CNP. At d7 of age, chicks were orally-vaccinated with PBS or 20 μg CNP/bird. At d14 of age, birds were orally-challenged with PBS or 1 × 107 CFU/bird of S. Enteritidis. The CNP-vaccinated birds had higher antigen-specific IgY/IgA and lymphocyte-proliferation against flagellin (p &lt; 0.05). At 14 days post-infection, CNP-vaccinated birds reversed the loss in gut permeability by 13% (p &lt; 0.05). At 21 days post-infection, the CNP-vaccinated birds decreased S. Enteritidis in the ceca and spleen by 2 Log10 CFU/g, and in the small intestine by 0.6 Log10 CFU/g (p &lt; 0.05). We conclude that the CNP vaccine is a viable alternative to conventional Salmonella poultry vaccines.

Bioactive polysaccharides and oligosaccharides from garlic (Allium sativum L.): Production, physicochemical and biological properties, and structure-function relationships

Garlic is a common food, and many of its biological functions are attributed to its components including functional carbohydrates. Garlic polysaccharides and oligosaccharides as main components are understudied but have future value due to the growing demand for bioactive polysaccharides/oligosaccharides from natural sources. Garlic polysaccharides have molecular weights of 1 × 10³ to 2 × 10⁶  Da, containing small amounts of pectins and fructooligosaccharides and large amounts of inulin-type fructans ((2→1)-linked β-d-Fruf backbones alone or with attached (2→6)-linked β-d-Fruf branched chains). This article provides a detailed review of research progress and identifies knowledge gaps in extraction, production, composition, molecular characteristics, structural features, physicochemical properties, bioactivities, and structure-function relationships of garlic polysaccharides/oligosaccharides. Whether the extraction processes, synthesis approaches, and modification methods established for other non-garlic polysaccharides are also effective for garlic polysaccharides/oligosaccharides (to preserve their desired molecular structures and bioactivities) requires verification. The metabolic processes of ingested garlic polysaccharides/oligosaccharides (as food ingredients/dietary supplements), their modes of action in healthy humans or populations with chronic conditions, and molecular/chain organization-bioactivity relationships remain unclear. Future research directions related to garlic polysaccharides/oligosaccharides are discussed.

Increased fermentable carbohydrate intake alters colonic mucus barrier function through glycation processes and increased mast cell counts

Irritable bowel syndrome (IBS) is a functional gastrointestinal disorder for which dietary interventions can be a useful treatment. In recent years, the low-FODMAP approach is gaining traction in this regard. The fermentation of these non-absorbed carbohydrates by the gut microbiota can generate toxic glycating metabolites, such as methylglyoxal. These metabolites can have harmful effects by their role in the generation of advanced glycation end products (AGEs), which activates Receptor for AGEs (AGER). Mast cells can be stimulated by AGEs and play a role in IBS. We have treated mice with lactose or fructo-oligosaccharides (FOS), with or without co-administration of pyridoxamine and investigated the colonic mucus barrier. We have found that an increased intake of lactose and fructo-oligosaccharides induces a dysregulation of the colonic mucus barrier, increasing mucus discharge in empty colon, while increasing variability and decreasing average thickness mucus layer covering the fecal pellet. Changes were correlated with increased mast cell counts, pointing to a role for the crosstalk between these and goblet cells. Additionally, AGE levels in colonic epithelium were increased by treatment with the selected fermentable carbohydrates. Observed effects were prevented by co-treatment with anti-glycation agent pyridoxamine, implicating glycation processes in the negative impact of fermentable carbohydrate ingestion. This study shows that excessive intake of fermentable carbohydrates can cause colonic mucus barrier dysregulation in mice, by a process that involves glycating agents and increased mucosal mast cell counts.

Effect of diet on pathogen performance in the microbiome

Intricate interactions among commensal bacteria, dietary substrates and immune responses are central to defining microbiome community composition, which plays a key role in preventing enteric pathogen infection, a dynamic phenomenon referred to as colonisation resistance. However, the impact of diet on sculpting microbiota membership, and ultimately colonisation resistance has been overlooked. Furthermore, pathogens have evolved strategies to evade colonisation resistance and outcompete commensal microbiota by using unique nutrient utilisation pathways, by exploiting microbial metabolites as nutrient sources or by environmental cues to induce virulence gene expression. In this review, we will discuss the interplay between diet, microbiota and their associated metabolites, and how these can contribute to or preclude pathogen survival.

Fructooligosaccharides on inflammation, immunomodulation, oxidative stress, and gut immune response: a systematic review

CONTEXT

Evidence shows that fructooligosaccharides (FOSs) can modulate inflammatory, oxidative, and immune activity in the gut, possibly leading to a systemic response, improving human health.

OBJECTIVE

To assess the present knowledge of the effects of FOSs on inflammation, immunomodulation, oxidative stress, and gut immune response.

DATA SOURCES

Studies published between December 2000 and January 2020 were systematically searched in four databases: MEDLINE, LILACS, Web of Science, and Scopus. After the screening of 1316 articles, 8 human studies and 20 animal models were included.

DATA EXTRACTION

Data were extracted separately by 2 reviewers. For each study, the design, population, exposures, main results, and conclusion were extracted. The research questions and the risk-of-bias information were also extracted. Additionally, the risk-of-bias were analyzed to guarantee the reliability of this review.

DATA ANALYSIS

A qualitative analysis revealed that FOSs can increase bifidobacteria counts and short-chain fatty acids in the gut, stimulate IgA secretion in the colon, and decrease proinflammatory cytokines, thus influencing metabolic diseases.

CONCLUSION

Studies suggest that FOS supplementation is positively associated with an anti-inflammatory and antioxidant effect, thus enhancing the gut immune system, which may be beneficial for the host's health.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO registration nos 42020209865 and 42020220369.

Soluble Dietary Fiber, One of the Most Important Nutrients for the Gut Microbiota

Dietary fiber is a widely recognized nutrient for human health. Previous studies proved that dietary fiber has significant implications for gastrointestinal health by regulating the gut microbiota. Moreover, mechanistic research showed that the physiological functions of different dietary fibers depend to a great extent on their physicochemical characteristics, one of which is solubility. Compared with insoluble dietary fiber, soluble dietary fiber can be easily accessed and metabolized by fiber-degrading microorganisms in the intestine and produce a series of beneficial and functional metabolites. In this review, we outlined the structures, characteristics, and physiological functions of soluble dietary fibers as important nutrients. We particularly focused on the effects of soluble dietary fiber on human health via regulating the gut microbiota and reviewed their effects on dietary and clinical interventions.

Current experimental models, assessment and dietary modulations of intestinal permeability in broiler chickens

Maintaining and optimising the intestinal barrier (IB) function in poultry has important implications for the health and performance of the birds. As a key aspect of the IB, intestinal permeability (IP) is mainly controlled by complex junctional proteins called tight junction proteins (TJ) that link enterocytes together. The disruption of TJ is associated with increased gut leakage with possible subsequent implications for bacterial translocation, intestinal inflammation, compromised health and performance of the birds. Despite considerable data being available for other species, research on IP in broiler chickens and in general avian species is still an understudied topic. This paper reviews the available literature with a specific focus on IP in broiler chickens with consideration given to practical factors affecting the IP, current assessment methods, markers and nutritional modulation of IP. Several experimental models to induce gut leakage are discussed including pathogens, rye-based diets, feed deprivation and stress-inducing agents such as exogenous glucocorticoids and heat stress. Although various markers including fluorescein isothiocyanate dextran, expression of TJ and bacterial translocation have been widely utilized to study IP, recent studies have identified a number of excreta biomarkers to evaluate intestinal integrity, in particular non-invasive IP. Although the research on various nutrients and feed additives to potentially modulate IP is still at an early stage, the most promising outcomes are anticipated for probiotics, prebiotics, amino acids and those feed ingredients, nutrients and additives with anti-inflammatory properties. Considerable research gaps are identified for the mechanistic mode of action of various nutrients to influence IP under different experimental models. The modulation of IP through various strategies (i.e. nutritional manipulation of diet) may be regarded as a new frontier for disease prevention and improving the health and performance of poultry particularly in an antibiotic-free production system.

The lipidome in nonalcoholic fatty liver disease: actionable targets

Nonalcoholic fatty liver disease (NAFLD) has become the most prevalent chronic liver disease. Recent technological advances, combined with OMICs experiments and explorations involving different biological samples, have uncovered vital aspects of NAFLD biology. In this review, we summarize recent work by our group and others that expands what is known about the role of lipidome in NAFLD pathogenesis. We discuss how pathway and enrichment analyses were performed by integrating a list of query metabolites derived from text-mining existing NAFLD-lipidomics studies, resulting in the identification of nine Kyoto Encyclopedia of Genes and Genomes dysregulated pathways, including biosynthesis of unsaturated fatty acids, butanoate metabolism, synthesis and degradation of ketone bodies, sphingolipid, arachidonic acid and pyruvate metabolism, and numerous nonsteroidal antiinflammatory drug pathways predicted from The Small Molecule Pathway Database. We also summarize an integrated pathway-level analysis of genes and lipid-related metabolites associated with NAFLD, which shows overrepresentation of signal transduction, selenium micronutrient network, Class A/1Rhodopsin-like receptors and G protein-coupled receptor ligand binding, and G protein-coupled receptor downstream signaling. Generated gene-metabolite-disease interaction networks indicate that NAFLD and arterial hypertension are interlinked by molecular signatures. Finally, we discuss how mining pathways and associations among metabolites, lipids, genes, and proteins can be exploited to infer networks and potential pharmacological targets and how lipidomic studies may provide insight into the interrelationships among metabolite clusters that modify NAFLD biology, genetic susceptibility, diet, and the gut microbiome.

Dietary supplemental xylooligosaccharide modulates nutrient digestibility, intestinal morphology, and gut microbiota in laying hens

This study was conducted to evaluate the prebiotic effects of dietary xylooligosaccharide (XOS) supplementation on performance, nutrient digestibility, intestinal morphology, and gut microbiota in laying hens. In a 12-wk experiment, a total of 288 Hy-Line Brown layers at 50 wk of age were randomly assigned into 3 dietary treatments supplemented with XOS at 0, 200 or 400 mg/kg. Each treatment had 8 replicates with 12 birds each. Hens fed XOS diets showed a lower feed-to-egg ratio during wk 7 to 12 and a higher egg yolk color value in wk 12 compared with those fed the control diet (P < 0.05). Dietary XOS supplementation improved the apparent total tract digestibility of gross energy and nitrogen at the end of the 12th wk (P < 0.05). In addition, a higher villus height-to-crypt depth ratio of the ileum was observed in XOS-added groups (P < 0.05). The high throughput sequencing analysis of bacterial 16S rRNA revealed that dietary XOS supplementation at 200 mg/kg altered cecal microbiota. Alpha diversity analysis illustrated a higher cecal bacterial richness in birds fed with XOS at 200 mg/kg. The composition of cecal microbiota modulated by the XOS addition was characterized by an increased abundance of Firmicutes along with a reduced abundance of Bacteroidetes. At the genus level, dietary XOS supplementation triggered decreases in Bacteroides and Campylobacter concurrent with increases in Lactobacillus and several short chain fatty acid producers including Desulfovibrio, Faecalitalea, Faecalicoccus, and 5 genera of family Lachnospiraceae. Collectively, dietary XOS addition improved the feed conversion ratio by modulating nutrient digestibility and ileal morphology in laying hens, which could be attributed to the enhancement of bacterial diversity and alteration of microbial composition.

Dose-response and functional role of whey permeate as a source of lactose and milk oligosaccharides on intestinal health and growth of nursery pigs

Two experiments were conducted to evaluate dose-response and supplemental effects of whey permeate on growth performance and intestinal health of nursery pigs. In experiment (exp.) 1, 1,080 pigs weaned at 6.24 kg body weight (BW) were allotted to five treatments (eight pens/treatment) with increasing levels of whey permeate in three phases (from 10% to 30%, 3% to 23%, and 0% to 9% for phase 1, 2, and 3, respectively) fed until 11 kg BW and then fed a common phase 4 diet (0% whey permeate) until 25 kg BW in a 48-d feeding trial. Feed intake and BW were measured at the end of each phase. In exp. 2, 1,200 nursery pigs at 7.50 kg BW were allotted to six treatments (10 pens/treatment) with increasing levels of whey permeate from 0% to 18.75% fed until 11 kg BW. Feed intake and BW were measured during 11 d. Six pigs per treatment (1 per pens) were euthanized to collect the jejunum to evaluate tumor necrosis factor-alpha, interleukin-8 (IL-8), transforming growth factor-beta 1, mucin 2, histomorphology, digestive enzyme activity, crypt cell proliferation rate, and jejunal mucosa-associated microbiota. Data were analyzed using contrasts in the MIXED procedure and a broken-line analysis using the NLIN procedure of SAS. In exp. 1, increasing whey permeate had a quadratic effect (P < 0.05) on feed efficiency (G:F; maximum: 1.35 at 18.3%) in phase 1. Increasing whey permeate linearly increased (P < 0.05) average daily gain (ADG; 292 to 327 g/d) and G:F (0.96 to 1.04) of pigs in phase 2. In exp. 2, increasing whey permeate linearly increased (P < 0.05) ADG (349 to 414 g/d) and G:F (0.78 to 0.85) and linearly increased (P < 0.05) crypt cell proliferation rate (27.8% to 37.0%). The breakpoint from a broken-line analysis was obtained at 13.6% whey permeate for maximal G:F. Increasing whey permeate tended to change IL-8 (quadratic, P = 0.052; maximum: 223 pg/mg at 10.9%), to decrease Firmicutes:Bacteroidetes (P = 0.073, 1.59 to 1.13), to increase (P = 0.089) Bifidobacteriaceae (0.73% to 1.11%), and to decrease Enterobacteriaceae (P = 0.091, 1.04% to 0.52%) and Streptococcaceae (P = 0.094, 1.50% to 0.71%) in the jejunal mucosa. In conclusion, dietary inclusion of whey permeate increased the growth of nursery pigs from 7 to 11 kg BW. Pigs grew most efficiently with 13.6% whey permeate. Improvement in growth performance is partly attributed to stimulating intestinal immune response and enterocyte proliferation with positive changes in jejunal mucosa-associated microbiota in nursery pigs.

Impact of prebiotics on immune response: from the bench to the clinic

Several preclinical and clinical studies have shown the immunomodulatory role exerted by prebiotics in regulating the immune response. In this review, we describe the mechanistic and clinical studies that decipher the cell signaling pathways implicated in the process. Prebiotic fibers are conventionally known to serve as substrate for probiotic commensal bacteria that release of short-chain fatty acids in the intestinal tract along with several other metabolites. Subsequently, they then act on the local as well as the systemic immune cells and the gut-associated epithelial cells, primarily through G-protein-coupled receptor-mediated pathways. However, other pathways including histone deacetylase inhibition and inflammasome pathway have also been implicated in regulating the immunomodulatory effect. The prebiotics can also induce a microbiota-independent effect by directly acting on the gut-associated epithelial and innate immune cells through the Toll-like receptors. The cumulative effect results in the maintenance of the epithelial barrier integrity and modulation of innate immunity through secretion of pro- and anti-inflammatory cytokines, switches in macrophage polarization and function, neutrophil recruitment and migration, dendritic cell and regulatory T-cell differentiation. Extending these in vitro and ex vivo observations, some prebiotics have been well investigated, with successful human and animal trials demonstrating the association between gut microbes and immunity biomarkers leading to improvement in health endpoints across populations. This review discusses scientific insights into the association between prebiotics, innate immunity and gut microbiome from in vitro to human oral intervention.

Phytochemicals affect T helper 17 and T regulatory cells and gut integrity: implications on the gut-bone axis

The pathology of osteoporosis is multifactorial, but a growing body of evidence supports an important role of the gut-bone axis, especially in bone loss associated with menopause, rheumatoid arthritis, and periodontal disease. Aberrant T cell responses favoring an increase in the ratio of T helper 17 cells to T regulatory cells play a critical role in the underlying etiology of this bone loss. Many of the dietary phytochemicals known to have osteoprotective activity such as flavonoids, organosulfur compounds, phenolic acids, as well as the oligosaccharides also improve gut barrier function and affect T cell differentiation and activation within gut-associated lymphoid tissues and at distal sites. Here, we examine the potential of these phytochemicals to act as prebiotics and immunomodulating agents, in part targeting the gut to mediate their effects on bone.

Effect of a Milk-Based Fruit Beverage Enriched with Plant Sterols and/or Galactooligosaccharides in a Murine Chronic Colitis Model

The potential anti-inflammatory effect of plant sterols (PS) enriched milk-based fruit beverages (PS, 1 g/100 mL) (MfB) with/without galactooligosaccharides (GOS, 2 g/100 mL) (MfB-G) in an experimental mice model of chronic ulcerative colitis was evaluated. Beverages were orally administered to mice every day by gavage to achieve PS and GOS doses of 35 and 90 mg/kg, respectively, and experimental colitis was induced by giving mice drinking water ad libitum containing 2% (w/v) dextran sulphate sodium (DSS) for 7 days, alternating with periods without DSS up to the end of the study (56 days). MfB beverage showed significant reduction of symptoms associated to ulcerative colitis and improved the colon shortening and mucosal colonic damage, but it was not able to reduce the increase of myeloperoxidase levels produced by DSS. MfB-G showed higher incidence of bloody feces and loss of stool consistency than MfB, as well as high levels of immune cells infiltration in colon tissue and myeloperoxidase. Therefore, PS-enriched milk-based fruit beverage could be an interesting healthy food to extend the remission periods of the diseases and the need to evaluate, in a pre-clinical model, the anti-inflammatory effect of the combination of bioactive compounds in the context of a whole food matrix.

Ingestion of difructose anhydride III partially suppresses the deconjugation and 7α-dehydroxylation of bile acids in rats fed with a cholic acid-supplemented diet

Difructose anhydride III (DFAIII) is a prebiotic involved in the reduction of secondary bile acids (BAs). We investigated whether DFAIII modulates BA metabolism, including enterohepatic circulation, in the rats fed with a diet supplemented with cholic acid (CA), one of the 12α-hydroxylated BAs. After acclimation, the rats were fed with a control diet or a diet supplemented with DFAIII. After 2 weeks, each group was further divided into two groups and was fed diet with or without CA supplementation at 0.5 g/kg diet. BA levels were analyzed in aortic and portal plasma, liver, intestinal content, and feces. As a result, DFAIII ingestion reduced the fecal deoxycholic acid level via the partial suppression of deconjugation and 7α-dehydroxylation of BAs following CA supplementation. These results suggest that DFAIII suppresses production of deoxycholic acid in conditions of high concentrations of 12α-hydroxylated BAs in enterohepatic circulation, such as obesity or excess energy intake. Abbreviation: BA: bile acid; BSH: bile salt hydrolase; CA: cholic acid; DCA: deoxycholic acid; DFAIII: difructose anhydride III; MCA: muricholic acid; MS: mass spectrometry; NCDs: non-communicable diseases; LC: liquid chromatography; SCFA: short-chain fatty acid; TCA: taurocholic acid; TCDCA: taurochenodeoxycholic acid; TDCA: taurodeoxycholic acid; TUDCA: tauroursodeoxychlic acid; TαMCA: tauro-α-muricholic acid; TβMCA: tauro-β-muricholic acid; TωMCA: tauro-ω-muricholic acid.

Assessing intestinal permeability in Crohn's disease patients using orally administered 52Cr-EDTA

Background

Intestinal permeability can be assessed by monitoring renal excretion of orally administered radioactively ⁵¹Cr-labeled ethylenediaminetetraacetic acid (⁵¹Cr-EDTA). Although considered safe, patient participation in using radio-labeled tracers is low. Here, we used orally administered ⁵²Cr-EDTA as non-radioactive alternative to assess intestinal permeability in CD and analyzed the association with disease activity, disease location and gut microbial dysbiosis.

Materials and methods

60 CD patients with low (n = 25) and increased (n = 35) fecal calprotectin levels (cut-off: 100 μg/g feces) ingested 20 mL ⁵²Cr-EDTA (20 mmol/L) solution whereafter 24-h urine was collected. Urinary ⁵²Cr-EDTA concentrations were quantified using Inductively Coupled Plasma Mass Spectrometry (ICP-MS). Fecal Enterobacteriaceae and Faecalibacterium prausnitzii were quantified using FISH. Correlations between urinary ⁵²Cr-EDTA excretion and other parameters were established using nonparametric Spearman’s correlation coefficients (ρ).

Results

CD patients with increased fecal calprotectin levels (> 100 μg/g) demonstrated an elevated urinary ⁵²Cr-EDTA/creatinine ratio (772 vs. 636 μmol/mol, P = 0.132). Patients with primarily colonic disease showed the highest ⁵²Cr-EDTA excretion. Importantly, a positive correlation was observed for the urinary ⁵²Cr-EDTA/creatinine ratio and fecal calprotectin levels (ρ = 0.325, P < 0.05). Finally, urinary ⁵²Cr-EDTA/creatinine ratio negatively correlated with the relative abundance of Faecalibacterium prausnitzii (ρ = -0.221, P = 0.092), while positively correlating with Enterobacteriaceae (ρ = 0.202, P = 0.126).

Conclusions

Orally administered and renal excreted ⁵²Cr-EDTA may be used to assess intestinal permeability in CD and correlates with fecal calprotectin levels and bacterial species relevant to CD. This test may improve non-invasive detection of disease exacerbations and help monitor disease activity.

Review: Roles of Prebiotics in Intestinal Ecosystem of Broilers

In recent years, prebiotics have been considered as potential alternatives to antibiotics. Mechanisms by which prebiotics modulate the ecosystem of the gut include alternation of the intestinal microbiota, improvement of the epithelium, and stimulation of the immune system. It is suggested that the administration of prebiotics not only influences these aspects but also regulates the interaction between the host and the intestinal microbiota comprehensively. In this review, we will discuss how each prebiotic ameliorates the ecosystem by direct or indirect mechanisms. Emphasis will be placed on the effects of prebiotics, including mannan oligosaccharides, β-glucans, and fructans, on the interaction between the intestinal microbiota, gut integrity, and the immunity of broilers. We will highlight how the prebiotics modulate microbial community and regulate production of cytokines and antibodies, improving gut development and the overall broiler health. Understanding the cross talk between prebiotics and the intestinal ecosystem may provide us with novel insights and strategies for preventing pathogen invasion and improving health and productivity of broilers. However, further studies need to be conducted to identify the appropriate dosages and better resources of prebiotics for refinement of administration, as well as to elucidate the unknown mechanisms of action.

A Review of Prebiotics Against Salmonella in Poultry: Current and Future Potential for Microbiome Research Applications

Prebiotics are typically fermentable feed additives that can directly or indirectly support a healthy intestinal microbiota. Prebiotics have gained increasing attention in the poultry industry as wariness toward antibiotic use has grown in the face of foodborne pathogen drug resistance. Their potential as feed additives to improve growth, promote beneficial gastrointestinal microbiota, and reduce human-associated pathogens, has been well documented. However, their mechanisms remain relatively unknown. Prebiotics increasing short chain fatty acid (SCFA) production in the cecum have long since been considered a potential source for pathogen reduction. It has been previously concluded that prebiotics can improve the safety of poultry products by promoting the overall health and well-being of the bird as well as provide for an intestinal environment that is unfavorable for foodborne pathogens such as Salmonella. To better understand the precise benefit conferred by several prebiotics, "omic" technologies have been suggested and utilized. The data acquired from emerging technologies of microbiomics and metabolomics may be able to generate a more comprehensive detailed understanding of the microbiota and metabolome in the poultry gastrointestinal tract. This understanding, in turn, may allow for improved administration and optimization of prebiotics to prevent foodborne illness as well as elucidate unknown mechanisms of prebiotic actions. This review explores the use of prebiotics in poultry, their impact on gut Salmonella populations, and how utilization of next-generation technologies can elucidate the underlying mechanisms of prebiotics as feed additives.

Review article: short chain fatty acids as potential therapeutic agents in human gastrointestinal and inflammatory disorders

BACKGROUND

Butyrate, propionate and acetate are short chain fatty acids (SCFA), important for maintaining a healthy colon and are considered as protective in colorectal carcinogenesis. However, they may also regulate immune responses and the composition of the intestinal microbiota. Consequently, their importance in a variety of chronic inflammatory diseases is emerging.

AIMS

To review the physiology and metabolism of SCFA in humans, cellular and molecular mechanisms by which SCFA may act in health and disease, and approaches for therapeutic delivery of SCFA.

METHODS

A PubMed literature search was conducted for clinical and pre-clinical studies using search terms: 'dietary fibre', short-chain fatty acids', 'acetate', 'propionate', 'butyrate', 'inflammation', 'immune', 'gastrointestinal', 'metabolism'.

RESULTS

A wide range of pre-clinical evidence supports roles for SCFA as modulators of not only colonic function, but also multiple inflammatory and metabolic processes. SCFA are implicated in many autoimmune, allergic and metabolic diseases. However, translating effects of SCFA from animal studies to human disease is limited by physiological and dietary differences and by the challenge of delivering sufficient amounts of SCFA to the target sites that include the colon and the systemic circulation. Development of novel targeted approaches for colonic delivery, combined with postbiotic supplementation, may represent desirable strategies to achieve adequate targeted SCFA delivery.

CONCLUSIONS

There is a large array of potential disease-modulating effects of SCFA. Adequate targeted delivery to the sites of action is the main limitation of such application. The ongoing development and evaluation of novel delivery techniques offer potential for translating promise to therapeutic benefit.

Prebiotic Supplementation Following Ileocecal Resection in a Murine Model is Associated With a Loss of Microbial Diversity and Increased Inflammation

BACKGROUND

Individuals with Crohn's disease frequently require ileocecal resection (ICR), and inflammation often recurs in the neoterminal ileum following surgery. Fructooligosaccharide (FOS) is a fermentable prebiotic that stimulates the growth of bifidobacteria and may promote anti-inflammatory activity. The aim of this study was to determine if supplementation of a postICR diet with FOS in a mouse model would be effective in stimulating the growth of bifidobacteria and reducing systemic and local inflammation.

METHODS

ICR was performed in IL10-/- mice (129S1/SvlmJ) with colitis. Following surgery, nonICR control and ICR mice were fed a chow diet ± 10% FOS for 28 days. Serum, colon, and terminal ileum (TI) were analyzed for cytokine expression by MesoScale discovery platform. DNA extracted from stool was analyzed using 16s rRNA sequencing and qPCR. Expression of occludin and ZO1 was assessed using qPCR. Short-chain fatty acid (SCFA) concentrations were assessed using gas chromatography.

RESULTS

ICR led to increased systemic inflammation (P < 0.05) and a significant decline in fecal microbial diversity (P < 0.05). Mice on the FOS diet had a greater reduction in microbial diversity and also had worsened inflammation as evidenced by increased serum IL-6 (P < 0.05) and colonic IFNγ and TNFα (P < 0.05). Expression of occludin and ZO1 were significantly reduced in FOS-supplemented mice. There was a correlation between loss of diversity and the bifidogenic effectiveness of FOS (r = -0.61, P < 0.05).

CONCLUSIONS

FOS-supplementation of a postICR diet resulted in a decrease in fecal bacterial diversity, reduction in barrier function, and increased gut inflammation.

Galactooligosaccharide supplementation provides protection against Citrobacter rodentium-induced colitis without limiting pathogen burden

Many enteric pathogens, including Salmonella and enteropathogenic and enterohemorrhagic Escherichia coli, express adhesins that recognize and bind to carbohydrate moieties expressed on epithelial cells. An attractive strategy for inhibiting bacterial adherence employs molecules that mimic these epithelial binding sites. Prebiotic oligosaccharides are non-digestible, fermentable fibres capable of modulating the gut microbiota. Moreover, they may act as molecular decoys that competitively inhibit adherence of pathogens to host cells. In particular, galactooligosaccharides (GOS) and other prebiotic fibres have been shown to inhibit pathogen adherence to epithelial cells in vitro. In the present study, we determined the ability of prophylactic GOS administration to reduce enteric pathogen adherence both in vitro and in vivo as well as protect against intestinal inflammation. GOS supplementation significantly reduced the adherence of the epithelial-adherent murine bacterial pathogen Citrobacter rodentium in a dose-dependent manner to the surface of epithelial cells in vitro. A 1- to 2-log reduction in bacterial adherence was observed at the lowest and highest doses tested, respectively. However, mouse studies revealed that treatment with GOS neither reduced the adherence of C. rodentium to the distal colon nor decreased its dissemination to systemic organs. Despite the absence of adherence inhibition, colonic disease scores for GOS-treated, C. rodentium-infected mice were significantly lower than those of untreated C. rodentium-infected animals (P=0.028). Together, these data suggest that GOS has a direct protective effect in ameliorating disease severity following C. rodentium infection through an anti-adherence-independent mechanism.

Impact of β2-1 fructan on faecal community change: results from a placebo-controlled, randomised, double-blinded, cross-over study in healthy adults

Healthy adults (n 30) participated in a placebo-controlled, randomised, double-blinded, cross-over study consisting of two 28 d treatments (β2-1 fructan or maltodextrin; 3×5 g/d) separated by a 14-d washout. Subjects provided 1 d faecal collections at days 0 and 28 of each treatment. The ability of faecal bacteria to metabolise β2-1 fructan was common; eighty-seven species (thirty genera, and four phyla) were isolated using anaerobic medium containing β2-1 fructan as the sole carbohydrate source. β2-1 fructan altered the faecal community as determined through analysis of terminal restriction fragment length polymorphisms and 16S rRNA genes. Supplementation with β2-1 fructan reduced faecal community richness, and two patterns of community change were observed. In most subjects, β2-1 fructan reduced the content of phylotypes aligning within the Bacteroides, whereas increasing those aligning within bifidobacteria, Faecalibacterium and the family Lachnospiraceae. In the remaining subjects, supplementation increased the abundance of Bacteroidetes and to a lesser extent bifidobacteria, accompanied by decreases within the Faecalibacterium and family Lachnospiraceae. β2-1 Fructan had no impact on the metagenome or glycoside hydrolase profiles in faeces from four subjects. Few relationships were found between the faecal bacterial community and various host parameters; Bacteroidetes content correlated with faecal propionate, subjects whose faecal community contained higher Bacteroidetes produced more caproic acid independent of treatment, and subjects having lower faecal Bacteroidetes exhibited increased concentrations of serum lipopolysaccharide and lipopolysaccharide binding protein independent of treatment. We found no evidence to support a defined health benefit for the use of β2-1 fructans in healthy subjects.

Dietary fibre-based SCFA mixtures promote both protection and repair of intestinal epithelial barrier function in a Caco-2 cell model

Impaired gut barrier function plays an important role in the development of many diseases such as obesity, inflammatory bowel disease, and in HIV infection. Dietary fibres have been shown to improve intestinal barrier function through their fermentation products, short chain fatty acids (SCFAs), and the effects of individual SCFAs have been studied. Here, different SCFA mixtures representing possible compositions from fibre fermentation products were studied for protective and reparative effects on intestinal barrier function. The effect of fermentation products from four dietary fibres, i.e. resistant starch, fructooligosaccharides, and sorghum and corn arabinoxylan (varying in their branched structure) on barrier function was positively correlated with their SCFA concentration. Pure SCFA mixtures of various concentrations and compositions were tested using a Caco-2 cell model. SCFAs at a moderate concentration (40-80 mM) improved barrier function without causing damage to the monolayer. In a 40 mM SCFA mixture, the butyrate proportion at 20% and 50% showed both a protective and a reparative effect on the monolayer to disrupting agents (LPS/TNF-α) applied simultaneously or prior to the SCFA mixtures. Relating this result to dietary fibre selection, slow fermenting fibres that deliver appropriate concentrations of SCFAs to the epithelium with a high proportion of butyrate may improve barrier function.

β2-1 Fructan supplementation alters host immune responses in a manner consistent with increased exposure to microbial components: results from a double-blinded, randomised, cross-over study in healthy adults

β2-1 Fructans are purported to improve health by stimulating growth of colonic bifidobacteria, increasing host resistance to pathogens and stimulating the immune system. However, in healthy adults, the benefits of supplementation remain undefined. Adults (thirteen men, seventeen women) participated in a double-blinded, placebo-controlled, randomised, cross-over study consisting of two 28-d treatments separated by a 14-d washout period. Subjects' regular diets were supplemented with β2-1 fructan or placebo (maltodextrin) at 3×5 g/d. Fasting blood and 1-d faecal collections were obtained at the beginning and at the end of each phase. Blood was analysed for clinical, biochemical and immunological variables. Determinations of well-being and general health, gastrointestinal (GI) symptoms, regularity, faecal SCFA content, residual faecal β2-1 fructans and faecal bifidobacteria content were undertaken. β2-1 Fructan supplementation had no effect on blood lipid or cholesterol concentrations or on circulating lymphocyte and macrophage numbers, but significantly increased serum lipopolysaccharide, faecal SCFA, faecal bifidobacteria and indigestion. With respect to immune function, β2-1 fructan supplementation increased serum IL-4, circulating percentages of CD282+/TLR2+ myeloid dendritic cells and ex vivo responsiveness to a toll-like receptor 2 agonist. β2-1 Fructans also decreased serum IL-10, but did not affect C-reactive protein or serum/faecal Ig concentrations. No differences in host well-being were associated with either treatment, although the self-reported incidence of GI symptoms and headaches increased during the β2-1 fructan phase. Although β2-1 fructan supplementation increased faecal bifidobacteria, this change was not directly related to any of the determined host parameters.

Sex differences in gut fermentation and immune parameters in rats fed an oligofructose-supplemented diet

BACKGROUND

Mechanistic data to support health claims is often generated using rodent models, and the influence of prebiotic supplementation has largely been evaluated using male rodents. Given that sex-based differences in immune parameters are well recognized and recent evidence suggests differences in microbiota composition between sexes, validation of the effectiveness of prebiotics merits assessment in both males and females. Here, we have compared the effect of oligofructose (OF) supplementation on the fecal bacterial community, short chain fatty acid profiles, and gut mucosal and systemic immune parameters in male and female rats.

METHODS

Male and female rats were fed rodent chow or chow supplemented with OF (5 % w/w). Fecal community change was examined by analyzing 16S rRNA gene content. To compare effects of OF between sexes at the gut microbial and mucosal immune level, fecal short chain fatty acid and tissue cytokine profiles were measured. Serum lipopolysaccharide levels were also evaluated by the limulus amebocyte lysate assay as an indirect means of determining gut permeability between sexes.

RESULTS

In the fecal community of females, OF supplementation altered community structure by increasing abundance in the Phylum Bacteroidetes. In male rats, no changes in fecal community structure were observed, although fecal butyrate levels significantly increased. Liver Immunoglobulin A (IgA) levels were higher in males relative to females fed OF, and serum LPS concentrations were higher in males independent of diet. Females had higher basal levels of the regulatory cytokine interleukin-10 (IL-10) in the colon and liver, while males had higher basal levels of the pro-inflammatory cytokines IL-6 and cytokine-induced neutrophil chemoattractant-1 (CINC-1) in the cecum and liver.

CONCLUSIONS

We have shown that male and female rat gut communities metabolize an OF-supplemented diet differently. Sex-specific responses in both the fecal community and systemic immune parameters suggest that this difference may result from an increase in the availability of gut peptidyl-nitrogen in the males. These findings demonstrate the importance of performing sex-comparative studies when investigating potential health effects of prebiotics using rodent models.

Fermentable Carbohydrates Differentially Affect Colon Tumor Formation in Azoxymethane-Induced Male Fischer 344 Rats

BACKGROUND

The role of fermentation compared with the source or type of the fermentable material in colon tumorigenesis remains an issue in refining the definition of dietary fiber (DF).

OBJECTIVE

The aim of this study was to investigate the fermentation and source-specific effects of various carbohydrates in a medium-term colon tumorigenesis model.

METHODS

Six-week-old male Fischer 344 rats were randomly allocated into 6 groups (n = 36/group) to receive either AIN-93G (control) or diets containing fructooligosaccharides, wheat bran (WB), oat bran (OB), polydextrose, or high-amylose maize starch (HAMS), each adjusted to contain a total DF concentration of 7% (wt:wt) and have a fermentability of 3% (wt:wt). After 2 wk, 24 rats/group received 2 subcutaneous doses of azoxymethane (at 15 mg/kg body weight) 1 wk apart while 12 rats/group were injected with a saline vehicle; all rats were maintained on the assigned diets for 24 wk postinjection and then killed. Colon tumor outcomes and pathology together with cecal short-chain fatty acid composition were assessed.

RESULTS

No tumors were found in saline-injected rats, and all subsequent analyses were restricted to azoxymethane-injected rats. Colon tumor incidence was significantly lower in the polydextrose (21%) and WB (13%) groups than in the control group (63%; P < 0.05) but not different from the fructooligosaccharide (58%), HAMS (46%), and OB (33%) groups. In comparison to the control group (8 proximal/31 total tumors), fermentable materials reduced the number of tumors (P < 0.05) originating in the proximal colon: HAMS (5/15), polydextrose (2/7), OB (2/9), fructooligosaccharides (1/21), and WB (1/3). The mean ± SEM number of tumors/tumor-bearing rats was significantly lower in the WB (1.00 ± 0.00), OB (1.13 ± 0.13), and HAMS (1.36 ± 0.15) groups than in the control group (2.07 ± 0.27; P < 0.02); other groups did not differ. The mean ± SEM tumor burden/diet group was lower in the WB (1.2 ± 0.7 mm2), polydextrose (6.7 ± 3.2 mm2), and OB (7.0 ± 3.0 mm2) groups than in the control (21.4 ± 5.9 mm2) and fructooligosaccharide (22.1 ± 7.1 mm2; P < 0.05) groups but not significantly different from the HAMS group (15.1 ± 6.1 mm2). Total cecal SCFA concentrations did not differ among diet groups (overall mean ± SEM: 81 ± 4 μmol/g wet weight).

CONCLUSION

The rate and extent of fermentation of the carbohydrate material as well as the characteristics of the material in the lumen of the lower gastrointestinal tract all appear to have an important role in tumor outcomes in the azoxymethane-induced rat colon tumorigenesis assay.

Metagenomic insights into the effects of fructo-oligosaccharides (FOS) on the composition of fecal microbiota in mice

Fructo-oligosaccharides (FOS) are usually regarded as a type of prebiotic, favorably stimulating the growth of bifidobacteria and lactobacilli. However, they are not the specific substrates for these target species, and other bacteria, such as Streptococcus, Escherichia, and Clostridium, have been shown to be able to utilize FOS. Previous studies have mainly investigated only a few bacteria groups, and few reports analyzed the global effects of FOS on intestinal microbial communities. In this study the effects of FOS on gut bacteria in mice were investigated through a 16S rRNA metagenomic analysis. In the FOS-low group, the abundance of Actinobacteria significantly increased and that of Bacteroidetes decreased after FOS diet (5%) for 3 weeks. In the FOS-high group, Enterococcus was promoted and levels of Bifidobacterium and Olsenella both notably increased after FOS diet (25%) and the microbiota tended to revert to initial structure 2 weeks after FOS treatment ceased. The most striking observation was that Olsenella became a dominant genus comparable with Bifidobacterium after FOS treatment, and one strain of Olsenella, isolated from mice feces, was confirmed, for the first time, to be capable of using FOS. The results indicated that metagenomic analysis was helpful to reveal the FOS effects on the global composition of gut communities and new target for future studies.

Short-chain fructo-oligosaccharide and inulin modulate inflammatory responses and microbial communities in Caco2-bbe cells and in a mouse model of intestinal injury

BACKGROUND

Few studies have focused on the ability of prebiotics to prevent pathogen-induced cellular changes or alter the composition of the intestinal microbiota in complimentary relevant cell and animal models of inflammatory bowel disease.

OBJECTIVE

The objective of this study was to determine if pretreatment with inulin and a short-chain fructo-oligosaccharide (sc-FOS) prevents enterohemorrhagic Escherichia coli (EHEC) O157:H7 infection in Caco2-bbe epithelial cells and what effect 10% wt:v sc-FOS or inulin has on C57BL/6 mice under sham conditions or pretreatment with prebiotics before Citrobacter rodentium infection (10(8) colony-forming units).

METHODS

Actin rearrangement and tight junction protein (zona occludin-1) were examined with immunofluorescence. Barrier function was assessed by a fluorescent probe and by measuring transepithelial electrical resistance (TER). Alterations in cytokine gene expression and microbiome were assessed with quantitative reverse transcriptase-polymerase chain reaction and fluorescence in situ hybridization. Short-chain fatty acids (SCFAs) were measured by GC.

RESULTS

sc-FOS added to monolayers altered actin polymerization without affecting TER or permeability to a fluorescein isothiocyanate (FITC) probe, whereas inulin increased TER (P < 0.005) and altered actin arrangement without affecting FITC permeability. Neither prebiotic attenuated EHEC-induced decreases in barrier function. Prebiotics increased interleukin 10 (Il10) and transforming growth factor-β (Tgfβ) cytokine responses alone (P < 0.05) or with EHEC O157:H7 infection (P < 0.05) in vitro. Increases in tumor necrosis factor-α (Tnfα) (P < 0.05) and decreases in chemokine CXC motif ligand 8 (Cxcl8) (P < 0.05) expression were observed with prebiotic treatment prior to EHEC infection. No differences were noted in barrier function or cytokine responses in the absence or presence of C. rodentium in vivo. Alterations in microbiome were evident at 6 d and 10 d postinfection in treatment groups, but a change in C. rodentium load was not observed. Inulin and sc-FOS (P < 0.05) increased fecal SCFAs in the absence of infection.

CONCLUSION

This study provides new insights as to how prebiotics act in complementary in vitro and in vivo models of intestinal injury.

Dietary xylo-oligosaccharide stimulates intestinal bifidobacteria and lactobacilli but has limited effect on intestinal integrity in rats

Background

Consumption of prebiotics may modulate gut microbiota, subsequently affecting the bacterial composition, metabolite profile, and human health. Previous studies indicate that also changes in intestinal integrity may occur. In order to explore this further we have investigated the effect of the putative prebiotic xylo-oligosaccharides (XOS) on the gut microbiota and intestinal integrity in male Wistar rats. As changes in intestinal integrity may be related to the expected bifidogenic effect of XOS, we additionally addressed effects of supplementation with a commensal Bifidobacterium pseudolongum (BIF) isolated from the same breed of laboratory rats.

Results

Changes in faecal and caecal bacterial composition determined by 16S rRNA gene sequencing and quantitative PCR for selected bacterial groups revealed that the overall bacterial composition did not differ markedly between the control (CON), XOS, and BIF groups, when correcting for multiple comparisons. However as hypothesised, the relative abundance of Bifidobacterium spp. was increased in XOS-fed rats as compared to CON in faecal samples after the intervention. Also Lactobacillus spp. was increased in both the XOS and BIF groups in caecum content compared to CON. Intestinal permeability determined in vivo by FITC-dextran permeability and in vitro using extracted caecum water in trans-epithelial resistance (TER) assay showed no effect on intestinal integrity in either the XOS or the BIF groups. However, the expression of occludin, which is part of the tight junction complex, was increased in the XOS group compared to the CON group.

Conclusions

Supplementation with XOS or a commensal Bifidobacterium pseudolongum had very limited effects on intestinal integrity in rats as only significant change in expression of a single tight junction protein gene was found for the XOS group.

Fructo-oligosaccharides and iron bioavailability in anaemic rats: the effects on iron species distribution, ferroportin-1 expression, crypt bifurcation and crypt cell proliferation in the caecum

The present study investigated the effects of fructo-oligosaccharides (FOS) on the bioavailability of Fe from ferric pyrophosphate (FP), a water-insoluble compound, in Fe-deficient anaemic rats that were subjected to a Hb repletion assay. Male Wistar rats (n 64) were fed adequate or low (8 mg/kg) Fe diets for 15 d followed by 1 or 2 weeks of Fe repletion with diets providing 35 mg Fe/kg as ferrous sulphate (FS), FP or FP that was mixed with 7·5% FOS in the form of yacon flour or Raftilose P95 (RAF), a purified source of FOS. The effects of FOS were observed within the 1st week of the repletion period. Fe bioavailability was improved by FOS supplementation, as measured by Hb regeneration efficiency and hepatic Fe stores, which were more pronounced in the RAF group. Moreover, RAF supplementation resulted in a higher biological value relative to that of the FP group. FOS supplementation resulted in caecal enlargement, in addition to acidification and Fe species redistribution in the caecal contents relative to the control rats. These effects occurred concomitantly with decreased ferroportin (FPN)-1 expression in the caecal mucosa, which was similar in magnitude to that observed in the FS group. Caecum mucosal morphometry was influenced by FOS supplementation, whereas crypt fission and cell proliferation were highest in the caecum of the RAF group. These results reinforce the effects of FOS as Fe bioavailability enhancers in anaemic rats that are sustained by early changes in their caecal environment (decreased mucosal FPN-1 expression and increased Fe absorbability, crypt fission and cellularity).