Host Intestinal Health Research Articles

In vitro digestion and fecal fermentation of Tremella fuciformis exopolysaccharides from basidiospore-derived submerged fermentation

Tremella fuciformis polysaccharides (TFPS) belong to natural bioactive macromolecule with both edible and medicinal value, possessing much bioactivities such as anti-tumor, antioxidant, antidiabetics, and immunomodulatory. Currently, the production of TFPS through submerged fermentation (TFPS-1) is gradually replacing the polysaccharides extracted from the fruiting body due to improved fermentation efficiency and reduced separation costs. However, it is still unclear about the effect of TFPS-1 on gastrointestinal digestion and gut microbial fermentation, which is directly related to the function of its biological activity. This study aimed to illustrate the effect of TFPS-1 on digestive process through in vitro digestion and fecal fermentation. TFPS-1 was indigestible during the simulated gastrointestinal tract. But TFPS-1 can be digested by intestinal flora leading to alterations in the total polysaccharides content, molecular weight, and apparent viscosity. Moreover, TFPS-1 regulated the composition of gut microbial, lowering the proportion of Firmicutes to Bacteroidetes and enhancing the abundances of Parabacteroides and Bacteroides. The change of intestinal flora produced more short chain fatty acids and lowered the pH. The KEGG metabolic pathway analysis indicated that TFPS-1 enriched lipid metabolism, glycan biosynthesis and metabolism, and biosynthesis of other secondary metabolites. This study demonstrated that T. fuciformis fermented polysaccharide can be a potential prebiotic to optimize intestinal flora homeostasis and maintain host intestinal health.

Bacteria colonization and gene expression related to immune function in colon mucosa is associated with growth in neonatal calves regardless of live yeast supplementation

BackgroundAs Holstein calves are susceptible to gastrointestinal disorders during the first week of life, understanding how intestinal immune function develops in neonatal calves is important to promote better intestinal health. Feeding probiotics in early life may contribute to host intestinal health by facilitating beneficial bacteria colonization and developing intestinal immune function. The objective of this study was to characterize the impact of early life yeast supplementation and growth on colon mucosa-attached bacteria and host immune function.ResultsTwenty Holstein bull calves received no supplementation (CON) or Saccharomyces cerevisiae boulardii (SCB) from birth to 5 d of life. Colon tissue biopsies were taken within 2 h of life (D0) before the first colostrum feeding and 3 h after the morning feeding at d 5 of age (D5) to analyze mucosa-attached bacteria and colon transcriptome. Metagenome sequencing showed that there was no difference in α and β diversity of mucosa-attached bacteria between day and treatment, but bacteria related to diarrhea were more abundant in the colon mucosa on D0 compared to D5. In addition, qPCR indicated that the absolute abundance of Escherichia coli (E. coli) decreased in the colon mucosa on D5 compared to D0; however, that of Bifidobacterium, Lactobacillus, and Faecalibacterium prausnitzii, which could competitively exclude E. coli, increased in the colon mucosa on D5 compared to D0. RNA-sequencing showed that there were no differentially expressed genes between CON and SCB, but suggested that pathways related to viral infection such as “Interferon Signaling” were activated in the colon mucosa of D5 compared to D0.ConclusionsGrowth affected mucosa-attached bacteria and host immune function in the colon mucosa during the first 5 d of life in dairy calves independently of SCB supplementation. During early life, opportunistic pathogens may decrease due to intestinal environmental changes by beneficial bacteria and/or host immune function. Predicted activation of immune function-related pathways may be the result of host immune function development or suggest other antigens in the intestine during early life. Further studies focusing on the other antigens and host immune function in the colon mucosa are required to better understand intestinal immune function development.

Novel primers to identify a wider diversity of butyrate-producing bacteria.

Butyrate-producing bacteria are a functionally important part of the intestinal tract flora, and the resulting butyric acid is essential for maintaining host intestinal health, regulating the immune system, and influencing energy metabolism. However, butyrate-producing bacteria have not been defined as a coherent phylogenetic group. They are primarily identified using primers for key genes in the butyrate-producing pathway, and their use has been limited to the Bacillota and Bacteroidetes phyla. To overcome this limitation, we developed functional gene primers able to identify butyrate-producing bacteria through the butyrate kinase gene, which encodes the enzyme involved in the final step of the butyrate-producing pathway. Genomes extracted from human and rat feces were used to amplify the target genes through PCR. The obtained sequences were analyzed using BLASTX to construct a developmental tree using the MEGA software. The newly designed butyrate kinase gene primers allowed to recognize a wider diversity of butyrate-producing bacteria than that recognized using currently available primers. Specifically, butyrate-producing bacteria from the Synergistota and Spirochaetota phyla were identified for the first time using these primers. Thus, the developed primers provide a more accurate method for researchers and doctors to identify potential butyrate-producing bacteria and deepen our understanding of butyrate-producing bacterial species.

Multiomics analysis reveals the biological effects of live Roseburia intestinalis as a high-butyrate-producing bacterium in human intestinal epithelial cells.

Butyrate-producing bacteria play a key role in human health, and recent studies have triggered interest in their development as next-generation probiotics. However, there remains limited knowledge not only on the identification of high-butyrate-producing bacteria in the human gut but also in the metabolic capacities for prebiotic carbohydrates and their interaction with the host. Herein, we discovered that Roseburia intestinalis produces higher levels of butyrate and digests a wider variety of prebiotic polysaccharide structures compared with other human major butyrate-producing bacteria (Eubacterium rectale, Faecalibacterium prausnitzii, and Roseburia hominis). Moreover, R. intestinalis extracts upregulated the mRNA expression of tight junction proteins (TJP1, OCLN, and CLDN3) in human intestinal epithelial cells more than other butyrate-producing bacteria. We cultured R. intestinalis with human intestinal epithelial cells in the mimetic intestinal host-microbe interaction coculture system to explore the health-promoting effects using multiomics approaches. Consequently, we discovered that live R. intestinalis only enhances purine metabolism and the oxidative pathway, increasing adenosine triphosphate levels in human intestinal epithelial cells, but that heat-killed bacteria had no effect. Therefore, this study proposes that R. intestinalis has potentially high value as a next-generation probiotic to promote host intestinal health. This article is protected by copyright. All rights reserved.

The effects of live and pasteurized Akkermansia muciniphila on DSS-induced ulcerative colitis, gut microbiota, and metabolomics in mice.

Akkermansia muciniphila (A. muciniphila) plays an important role in intestinal regulation, while it is presently unclear whether live or pasteurized A. muciniphila has different effects on the intestinal health. In the present study, live or pasteurized A. muciniphila was administered to dextran sulfate sodium (DSS)-induced ulcerative colitis mice to investigate its influences on the host intestinal health, gut microbiota, and metabolomic phenotype. The results showed that pasteurized A. muciniphila alleviated the symptoms of colitis in mice more efficiently by encouraging the proliferation of beneficial intestinal bacteria, increasing the production of short-chain fatty acids, and inhibiting intestinal inflammation. Moreover, pasteurized A. muciniphila increased the abundance of Parasutterella and Akkermansia and thus affected the metabolism of lipid and lipid-like molecules associated with lysophosphatidylcholines (LysoPCs). Notably, prophylactic supplementation of pasteurized A. muciniphila increased the relative abundance of the anti-inflammatory microbe Dubosiella, thereby activating intestinal sphingolipid metabolism to alleviate intestinal damage. In conclusion, pasteurized A. muciniphila showed a more effective amelioration of DSS-induced colitis by repairing the dysbiosis of gut microbiota and intestinal metabolism compared to live A. muciniphila, providing a potential strategy to explore the protective effect of A. muciniphila on host intestinal health.

Empire Apple (Malus domestica) Juice, Pomace, and Pulp Modulate Intestinal Functionality, Morphology, and Bacterial Populations In Vivo (Gallus gallus).

Approximately $20 billion of apple sales are generated annually in the United States. With an estimated 5 million tons produced yearly in the U.S. within the last decade, apple consumption is considered ubiquitous. Apples are comprised of bioactive constituents such as phytochemicals and prebiotics that may potentiate intestinal health and the gut microbiome. This study aimed to evaluate the effects of Empire apple juice, pomace, and pulp soluble extracts on intestinal functionality, morphology, and the microbiome in vivo (Gallus gallus). There were five treatment groups: non-injected (NI); 18 MΩ H2O (H2O); 6% apple juice (AJ); 6% apple pomace (APo); 6% apple pulp (APu). The eggs were treated by intra-amniotic administration of the samples on day 17 of incubation. After hatching, the blood, tissue, and cecum samples were collected for further analyses—including duodenal histomorphology, hepatic and duodenal mRNA expression, and cecal bacterial populations. Crypt depth was significantly (p < 0.5) shortest in AJ when compared to APo and APu. APo and APu soluble extracts significantly improved villi surface area compared to NI and H2O control groups. The highest count of Paneth cells per crypt was observed in APo as compared to all groups. In addition, the expression of brush border membrane micronutrient metabolism and functional proteins varied between treatments. Lastly, Lactobacillus cecal microbial populations increased significantly in the AJ group, while AJ, APu, and APu increased the abundance of Clostridium (p < 0.5). Ultimately, these results indicate the potential of Empire apple pomace to improve host intestinal health and the gut microbiome.

Marginal Zinc Deficiency Aggravated Intestinal Barrier Dysfunction and Inflammation through ETEC Virulence Factors in a Mouse Model of Diarrhea.

Simple SummaryEnterotoxigenic Escherichia coli (ETEC) is one of the most common bacterial causes of diarrhea in children and farm animals. Zinc has received widespread attention for its roles in the prevention and treatment of diarrhea. However, zinc is also essential for the pathogenesis of ETEC. This study aimed to explore the accurate effect and mechanisms of marginal zinc deficiency on ETEC k88 infection and host intestinal health. Using the newly developed marginal zinc deficiency and ETEC k88 infection mouse model, we found that marginal zinc deficiency aggravated growth impairment, diarrhea, intestinal morphology, intestinal permeability, and inflammation induced by ETEC k88 infection. Consistently, intestinal ETEC k88 shedding was also higher in mice with marginal zinc deficiency. However, marginal zinc deficiency failed to affect host zinc levels and correspondingly the zinc-receptor GPR39 expression in the jejunum. In addition, marginal zinc deficiency upregulated the relative expression of virulence genes involved in heat-labile and heat-stable enterotoxins, motility, cellular adhesion, and biofilm formation in the cecum content of mice with ETEC infection. These findings provide a new explanation for zinc treatment of ETEC infection.Zinc is both essential and inhibitory for the pathogenesis of enterotoxigenic Escherichia coli (ETEC). However, the accurate effects and underlying mechanism of marginal zinc deficiency on ETEC infection are not fully understood. Here, a marginal zinc-deficient mouse model was established by feeding mice with a marginal zinc-deficient diet, and ETEC k88 was further administrated to mice after antibiotic disruption of the normal microbiota. Marginal zinc deficiency aggravated growth impairment, diarrhea, intestinal morphology, intestinal permeability, and inflammation induced by ETEC k88 infection. In line with the above observations, marginal zinc deficiency also increased the intestinal ETEC shedding, though the concentration of ETEC in the intestinal content was not different or even decreased in the stool. Moreover, marginal zinc deficiency failed to change the host’s zinc levels, as evidenced by the fact that the serum zinc levels and zinc-receptor GPR39 expression in jejunum were not significantly different in mice with ETEC challenge. Finally, marginal zinc deficiency upregulated the relative expression of virulence genes involved in heat-labile and heat-stable enterotoxins, motility, cellular adhesion, and biofilm formation in the cecum content of mice with ETEC infection. These findings demonstrated that marginal zinc deficiency likely regulates ETEC infection through the virulence factors, whereas it is not correlated with host zinc levels.

AI-2/LuxS Quorum Sensing System Promotes Biofilm Formation of Lactobacillus rhamnosus GG and Enhances the Resistance to Enterotoxigenic Escherichia coli in Germ-Free Zebrafish.

ABSTRACTThe LuxS enzyme plays a key role in both quorum sensing (QS) and the regulation of bacterial growth. It catalyzes the production of autoinducer-2 (AI-2) signaling molecule, which is a component of the methyl cycle and methionine metabolism. This study aimed at investigating the differences between the Lactobacillus rhamnosus GG (LGG) wild-type strain (WT) and its luxS mutant (ΔluxS) during biofilm formation and when resisting to inflammation caused by Enterotoxigenic Escherichia coli (ETEC) in germ-free zebrafish. Our results suggest that in the absence of luxS when LGG was knocked out, biofilm formation, extracellular polysaccharide secretion and adhesion were all compromised. Addition of synthetic AI-2 indeed rescued, at least partially, the deficiencies observed in the mutant strain. The colonizing and immunomodulatory function in WT versus ΔluxS mutants were further studied in a germ-free zebrafish model. The concentration of AI-2 signaling molecules decreased sharply in zebrafish infected with the ΔluxS. At the same time, compared with the ΔluxS, the wild-type strain could colonize the germ-free zebrafish more effectively. Our transcriptome results suggest that genes involved in immunity, signal transduction, and cell adhesion were downregulated in zebrafish infected with ΔluxS and WT. In the WT, the immune system of germ-free zebrafish was activated more effectively through the MAPK and NF-κB pathway, and its ability to fight the infection against ETEC was increased. Together, our results demonstrate that the AI-2/LuxS system plays an important role in biofilm formation to improve LGG and alleviate inflammation caused by ETEC in germ-free zebrafish.IMPORTANCE Lactobacillus rhamnosus GG is a widely used probiotic to improve host intestinal health, promote growth, reduce diarrhea, and modulate immunity. In recent years, the bacterial quorum sensing system has attracted much attention; however, there has not been much research on the effect of the LuxS/AI-2 quorum sensing system of Lactobacillus on bacteriostasis, microbial ecology balance, and immune regulation in intestine. In this study, we used germ-free zebrafish as an animal model to compare the differences between wild-type and luxS mutant strains. We showed how AI-2/LuxS QS affects the release of AI-2 and how QS regulates the colonization, EPS synthesis and biofilm formation of LGG. This study provides an idea for the targeted regulation of animal intestinal health with probiotics by controlling bacteria quorum sensing system.

Effects of Apple Pomace Soluble Extract on Intestinal Morphology, Functionality, and the Microbiome In Vivo (Gallus gallus)

ObjectivesTo assess the effects of apple pomace soluble extract on intestinal morphology, functionality, and the microbiome in vivo (Gallus gallus) following intra-amniotic administration. MethodsWe used Gallus gallus as our model with three treatment groups: (1) non-injected; (2) 18 Ω H2O; (3) 6% apple pomace soluble extract (APSE). On day 17 of embryonic incubation, the eggs were treated through intra-amniotic administration. Upon hatch (day 21), blood, tissue, and cecum samples were collected for further analysis. Histomorphology, duodenal mRNA expression, blood glucose, pectoral glycogen, and cecum bacterial population analyses were conducted. ResultsAPSE improved villi surface area and goblet cell number. Expression of brush border membrane metabolism and functional proteins varied between treatment groups. Further, significant changes in cecum microbial populations were observed between groups. ConclusionsUltimately, these results suggest the potential of apple pomace to improve host intestinal health and the gut microbiome. Funding SourcesN/A.

An Integrative Multiomics Approach to Characterize Prebiotic Inulin Effects on Faecalibacterium prausnitzii.

Faecalibacterium prausnitzii, a major commensal bacterium in the human gut, is well known for its anti-inflammatory effects, which improve host intestinal health. Although several studies have reported that inulin, a well-known prebiotic, increases the abundance of F. prausnitzii in the intestine, the mechanism underlying this effect remains unclear. In this study, we applied liquid chromatography tandem mass spectrometry (LC-MS/MS)-based multiomics approaches to identify biological and enzymatic mechanisms of F. prausnitzii involved in the selective digestion of inulin. First, to determine the preference for dietary carbohydrates, we compared the growth of F. prausnitzii in several carbon sources and observed selective growth in inulin. In addition, an LC-MS/MS-based intracellular proteomic and metabolic profiling was performed to determine the quantitative changes in specific proteins and metabolites of F. prausnitzii when grown on inulin. Interestingly, proteomic analysis revealed that the putative proteins involved in inulin-type fructan utilization by F. prausnitzii, particularly β-fructosidase and amylosucrase were upregulated in the presence of inulin. To investigate the function of these proteins, we overexpressed bfrA and ams, genes encoding β-fructosidase and amylosucrase, respectively, in Escherichia coli, and observed their ability to degrade fructan. In addition, the enzyme activity assay demonstrated that intracellular fructan hydrolases degrade the inulin-type fructans taken up by fructan ATP-binding cassette transporters. Furthermore, we showed that the fructose uptake activity of F. prausnitzii was enhanced by the fructose phosphotransferase system transporter when inulin was used as a carbon source. Intracellular metabolomic analysis indicated that F. prausnitzii could use fructose, the product of inulin-type fructan degradation, as an energy source for inulin utilization. Taken together, this study provided molecular insights regarding the metabolism of F. prauznitzii for inulin, which stimulates the growth and activity of the beneficial bacterium in the intestine.

Molecular and metabolomic changes in the proximal colon of pigs infected with Trichuris suis

The pig whipworm Trichuris suis is important in swine production because of its negative effects on pig performance and, notably, to some humans with inflammatory bowel disease as a therapeutic agent that modulates inflammation. The proximal colon of T. suis-infected pigs exhibited general inflammation around day 21 after inoculation with infective eggs that is transcriptionally characterized by markers of type-2 immune activation, inflammation, cellular infiltration, tissue repair enzymes, pathways of oxidative stress, and altered intestinal barrier function. Prominent gene pathways involved the Th2-response, de novo cholesterol synthesis, fructose and glucose metabolism, basic amino acid metabolism, and bile acid transport. Upstream regulatory factor analysis implicated the bile acid/farnesoid X receptor in some of these processes. Metabolic analysis indicated changes in fatty acids, antioxidant capacity, biochemicals related to methylation, protein glycosylation, extracellular matrix structure, sugars, Krebs cycle intermediates, microbe-derived metabolites and altered metabolite transport. Close to 1,200 differentially expressed genes were modulated in the proximal colon of pigs with a persistent adult worm infection that was nearly 90% lower in pigs that had expelled worms. The results support a model to test diets that favorably alter the microbiome and improve host intestinal health in both pigs and humans exposed to Trichuris.

Impact of Prebiotics on Enteric Diseases and Oxidative Stress

In animals, the gastrointestinal microbiota are reported to play a major role in digestion, nutrient absorption and the release of energy through metabolism of food. Therefore, microbiota may be a factor for association between diet and enteric diseases and oxidative stress. The gut microbial composition and concentration are affected by diet throughout the life of an animal, and respond rapidly and efficiently to dietary alterations, in particular to the use of prebiotics. Prebiotics, which play an important role in mammalian nutrition, are defined as dietary ingredients that lead to specific changes in both the composition and activity of the gastrointestinal microbiota through suppressing the proliferation of pathogens and by modifying the growth of beneficial microorganisms in the host intestine. A review of the evidence suggests possible beneficial effects of prebiotics on host intestinal health, including immune stimulation, gut barrier enhancement and the alteration of the gastrointestinal microbiota, and these effects appear to be dependent on alteration of the bacterial composition and short-chain fatty acid (SCFA) production. The production of SCFAs depends on the microbes available in the gut and the type of prebiotics available. The SCFAs most abundantly generated by gastrointestinal microbiota are acetate, butyrate and propionate, which are reported to have physiological effects on the health of the host. Nowadays, prebiotics are widely used in a range of food products to improve the intestinal microbiome and stimulate significant changes to the immune system. Thus, a diet with prebiotic supplements may help prevent enteric disease and oxidative stress by promoting a microbiome associated with better growth performance. This paper provides an overview of the hypothesis that a combination of ingestible prebiotics, chitosan, fructooligosaccharides and inulin will help relieve the dysbiosis of the gut and the oxidative stress of the host.

Symbiotic Effects of Kefir and Yacon Flour (Smallanthus sonchifolius) on Bone Remodeling in Rats

Abstract Objectives Kefir is a natural source of probiotics that confer benefits to the host's intestinal health. Yacon (Smallanthus sonchifolius) is a tuberous root originating in the Andes region, rich in prebiotic fructooligosaccharides (FOS), which increases the absorption of minerals. The objective of this study was to evaluate the prebiotic properties of yacon, the probiotic effect of kefir and the symbiotic action of the association between them in bone health in rats. Methods Adult Wistar rats were divided into 4 groups (n = 10): Group C (Control), Y (yacon flour, 51.34% FOS) K (kefir, 10⁷ UFC/mL), and YK (yacon flour + kefir). Group C received AIN-93 M + cow's milk (1 mL/day), group Y received AIN93 diet added by yacon flour to provide 5% FOS + cow's milk, group K received fermented kefir (1 mL/day), and group YK received yacon flour + fermented kefir. Feces and urine were collected for calcium balance in the last week of the experiment. At the end of 6 weeks, the animals were euthanized and the large intestine and blood sample were collected for analysis of intraluminal pH (pH meter Kasvi®) and biomarkers of bone remodeling, respectively. Calcium from diet, feces and urine was analyzed by atomic absorption. Osteocalcin (OC -- EL-R0243), C telopeptide of type I collagen (CTX – EL-R1456) and N telopeptide of type I collagen (NTX – EL-R0276) were analyzed by ELISA, according to manufacture's instructions (Elabscience, TX, USA). The results were analyzed by ANOVA, followed by the Tukey test (p &amp;lt; 0.05), using GENES®. Results No significant differences were observed between groups concerning calcium balance and cecal pH, although pH was slightly lower in the groups fed yacon (Y and YK). Biomarkers of bone formation (OC) and bone resorption (CTX and NTX) were significantly lower in group K (OC = 7.29; CTX = 4.04; NTX = 94.31 ng/mL), compared to the control (OC = 16.33; CTX = 5.68; NTX = 105.97 ng/mL). Groups Y (OC = 13.63; CTX = 5.13; NTX = 114.34 ng/mL) and YK (OC = 15.37; CTX = 5.17; NTX = 132.51 ng/mL) did not differ from the control. Conclusions Prebiotic (Y) and Symbiotic (YK) were more effective than kefir in bone remodeling in rats, although fermentation in the large gut did not reduce pH sufficiently to improve calcium absorption and retention. Funding Sources FAPES; CNPq and CAPES/Brazil.

Campylobacter jejuni BumSR directs a response to butyrate via sensor phosphatase activity to impact transcription and colonization

Campylobacter jejuni monitors intestinal metabolites produced by the host and microbiota to initiate intestinal colonization of avian and animal hosts for commensalism and infection of humans for diarrheal disease. We previously discovered that C. jejuni has the capacity to spatially discern different intestinal regions by sensing lactate and the short-chain fatty acids acetate and butyrate and then alter transcription of colonization factors appropriately for in vivo growth. In this study, we identified the C. jejuni butyrate-modulated regulon and discovered that the BumSR two-component signal transduction system (TCS) directs a response to butyrate by identifying mutants in a genetic screen defective for butyrate-modulated transcription. The BumSR TCS, which is important for infection of humans and optimal colonization of avian hosts, senses butyrate likely by indirect means to alter transcription of genes encoding important colonization determinants. Unlike many canonical TCSs, the predicted cytoplasmic sensor kinase BumS lacked in vitro autokinase activity, which would normally lead to phosphorylation of the cognate BumR response regulator. Instead, BumS has likely evolved mutations to naturally function as a phosphatase whose activity is influenced by exogenous butyrate to control the level of endogenous phosphorylation of BumR and its ability to alter transcription of target genes. To our knowledge, the BumSR TCS is the only bacterial signal transduction system identified so far that mediates responses to the microbiota-generated intestinal metabolite butyrate, an important factor for host intestinal health and homeostasis. Our findings suggest that butyrate sensing by this system is vital for C. jejuni colonization of multiple hosts.

Characterisation of Fecal Soap Fatty Acids, Calcium Contents, Bacterial Community and Short-Chain Fatty Acids in Sprague Dawley Rats Fed with Different sn-2 Palmitic Triacylglycerols Diets.

The structure of dietary triacylglycerols is thought to influence fatty acid and calcium absorption, as well as intestinal microbiota population of the host. In the present study, we investigated the impact of palmitic acid (PA) esterified at the sn-2 position on absorption of fatty acid and calcium and composition of intestinal microorganisms in rats fed high-fat diets containing either low sn-2 PA (12.1%), medium sn-2 PA (40.4%) or high sn-2 PA (56.3%), respectively. Fecal fatty acid profiles in the soaps were measured by gas chromatography (GC), while fecal calcium concentration was detected by ICP-MS. The fecal microbial composition was assessed using a 16S rRNA high-throughput sequencing technology and fecal short-chain fatty acids were detected by ion chromatograph. Dietary supplementation with a high sn-2 PA fat significantly reduced total fecal contents of fatty acids soap and calcium compared with the medium or low sn-2 PA fat groups. Diet supplementation with sn-2 PA fat did not change the entire profile of the gut microbiota community at phylum level and the difference at genera level also were minimal in the three treatment groups. However, high sn-2 PA fat diet could potentially improve total short-chain fatty acids content in the feces, suggesting that high dietary sn-2 PA fat might have a beneficial effect on host intestinal health.

Interaction between Microbes and Host Intestinal Health: Modulation by Dietary Nutrients and Gut-Brain-Endocrine-Immune Axis.

The mammalian gut, the site of digestion and nutrients absorption, harbors diverse microbes that play an essential role in maintaining physiological homeostasis of the gastrointestinal system. These commensal microbes are important for the normal development of the host immune system and alteration of the microbiota of gastrointestinal system has been found to play an important role in the development of obesity, metabolic syndromes such as type 2 diabetes, and cardiovascular diseases. Several recent studies with mouse models and in humans have demonstrated that intestinal microbiota has important role in host metabolism by regulating energy absorption and modulating the endocrine functions. A variety of nutrients and metabolites derived from commensal bacteria have been proved to be important regulators in improving gut barrier functions and immune homeostasis. Here we review current literature on the interactions between microbes and host in the Gastrointestinal (GI) tract and based on these interactions we proposed a hypothesis in which the microbiota interacts with the host gastrointestine through a gut-brainendocrine- immune system. By understanding this system, we should be in better position to develop treatment for metabolic diseases and inflammation in human and animals.

Changes in the Intestinal Microbiota and Host Inflammatory Gene Expression in Pigs Fed a Flavanol‐Enriched Cocoa Powder

To determine the effects of eating cocoa‐derived flavanols on the composition of the gut microbiota, associated metabolic profiles, and related features of host intestinal health, pigs were fed with 0, 2.5, 10, or 20 grams of flavanol‐enriched cocoa powder/day for 27 days. Analysis of phase II metabolites of cocoa‐derived flavanols demonstrated that O‐methyl‐(epi)catechin‐glucuronide conjugates were detected in a dose‐dependent manner in urine, serum, liver, and adipose tissue of pigs fed cocoa powder. Products of microbial metabolism such as phenylpropionic acids, phenylacetic acids, benzoic acids, cinnamic acids, and conjugated benzoic acids were detected in most of the tissue and bio‐fluids examined. Cocoa consumption also changed the composition of the intestinal microbiome. Pigs fed 20 gram of cocoa/day had significantly increased abundance of Lactobacillus species (casei group) in the feces and distal colon contents compared to pigs not fed cocoa. Moreover, consumption of cocoa powder reduced the gene expression of tumor necrosis factor‐α and toll‐like receptors‐2, ‐4, and ‐9 in most intestinal tissues examined. Overall, this study demonstrated that consumption of flavanol‐enriched cocoa can contribute to gut health by enhancing the abundance of Lactobacillus species and modulating markers of localized intestinal immunity.