Short-chain fatty acids: ready for prime time?

Plasticity of gastrointestinal vagal afferent satiety signals

The vagal link between the gastrointestinal tract and the central nervous system (CNS) has numerous vital functions for maintaining homeostasis. The regulation of energy balance is one which is attracting more and more attention due to the potential for exploiting peripheral hormonal targets as treatments for conditions such as obesity. While physiologically, this system is well tuned and demonstrated to be effective in the regulation of both local function and promoting/terminating food intake the neural connection represents a susceptible pathway for disruption in various disease states. Numerous studies have revealed that obesity in particularly is associated with an array of modifications in vagal afferent function from changes in expression of signaling molecules to altered activation mechanics. In general, these changes in vagal afferent function in obesity further promote food intake instead of the more desirable reduction in food intake. It is essential to gain a comprehensive understanding of the mechanisms responsible for these detrimental effects before we can establish more effective pharmacotherapies or lifestyle strategies for the treatment of obesity and the maintenance of weight loss.

Fermentation of Dietetic Fiber from Green Bean and Prickly Pear Shell by Pure and Mixture Culture of Lactobacillus acidophilus LA-5 and Bifidobacterium bifidum 450B

The aim of this study was to evaluate the fermentation of dietary fiber from green bean (Phaseolus vulgaris) and prickly pear shell (Opuntia ficus-indica) by Lactobacillus acidophilus LA-5 and Bifidobacterium bifidum 450B growing as mono-culture and co-culture, the fermentation products, and proteins expressed during this process. The analysis of the fermentation profile showed a major growth of bacteria in the culture media of each dietary fiber supplemented with glucose, and particularly B. bifidum 450B at 48 h showed the highest growth. In the case of the co-culture, the growth was lower indicating the possible negative interaction between L. acidophilus LA-5 and B. bifidum 450B and may be due to the less amount of carbohydrates and the high content of non-soluble fiber that affected the nutrients availability for the bacterial strains. The pH changes indicated the presence of short-chain fatty acids (SCFAs), being acetate (46-100%) the main SCFA. Changes in the proteome concerned proteins that are involved in carbohydrate and other carbohydrate pathways. The characterization of the bacteria according to the growth, metabolites, and proteins expressed allows understanding the response to the change of environmental conditions and could be useful to understand L. acidophilus LA-5 and B. bifidum 450B strains' adaptation to specific applications.

Intake of total saponins and polysaccharides from Polygonatum kingianum affects the gut microbiota in diabetic rats

BACKGROUND

The gut microbiota has been reported to play a critical role in metabolic diseases, including in diabetes. Polygonatum kingianum has been used in the treatment of diabetes and related diseases in China for centuries. Total saponins (TSPK) and total polysaccharides (PSPK) were reported to be major types of active constituents of P. kingianum. This research aims at investigation of their therapeutical mechanisms on diabetes based on the regulation of gut microbiota.

STUDY DESIGN

Type 2 diabetes (T2D) rats were induced by high-fat diet (HFD) and streptozotocin-injection from male Sprague-Dawley (SD) rats. The blood biochemical indicators were measured. Intestinal microbial diversities and the overall structural changes in gut microbiota and the contents of the short chain fatty acids (SCFAs) were discussed.

METHODS

T2D rats were treated with TSPK (0.025 and 0.1g/kg) and PSPK (0.1g/kg) for 56 days. Major biochemical indexes, such as fasting blood glucose (FBG), fasting insulin (FINS) and lipopolysaccharide (LPS), were measured. Intestinal microbial diversities and the overall structural changes in gut microbiota were discussed based on the sequencing results on V4 region of 16S rDNA. Moreover, the contents of the SCFAs in faeces, which were fermentation products produced from gut microbiota were determined by gas chromatography (GC).

RESULTS

Oral administration of TSPK and PSPK prevented the increase of FBG. TSPK (0.025g/kg) enhancing the content of FINS at the end of research. Furthermore, TSPK and PSPK improved the intestinal microecology by decreasing the abundances of Bacteroidetes and Proteobacteria, and increasing that of Firmicutes. However, TSPK.L, PSPK and TSPK.H displayed discrepant regulation roles on Firmicutes. TSPK.L and PSPK significantly increased the abundance of Ruminococcaceae family and Ruminococcus genus in Firmicutes phylum, however, TSPK.H increased the abundances of Veillonellaceae family and Anaerovibrio genus. 57 Key variables, altered after treated by TSPK and PSPK, correlated to the alternations of FBG, FINS, LPS and body weight were identified. In addition, TSPK.L, PSPK and TSPK.H showed different adjustment on the contents of SCFAs.

CONCLUSION

These results suggested that, compared to the normal rats, the structure of gut microbiota was significantly changed in diabetic rats. Oral administration with TSPK and PSPK could prevent T2D by its regulation role on the gut microbiota.

The gut microbiome and microbial translocation in multiple sclerosis

Individuals with multiple sclerosis (MS) have a distinct intestinal microbial community (microbiota) and increased low-grade translocation of bacteria from the intestines into the circulation. The observed change of intestinal bacteria in MS patients regulate immune functions involved in MS pathogenesis. These functions include: systemic and central nervous system (CNS) immunity (including peripheral regulatory T cell function), the blood-brain barrier (BBB) permeability and CNS-resident cell activity. This review discusses the MS intestinal microbiota implication on MS systemic- and CNS-immunopathology. We introduce the possible contributions of MS low-grade microbial translocation (LG-MT) to the development of MS, and end on a discussion on microbiota therapies for MS patients.

Bifidobacterium adolescentis Exerts Strain-Specific Effects on Constipation Induced by Loperamide in BALB/c Mice

Constipation is one of the most common gastrointestinal complaints worldwide. This study was performed to determine whether Bifidobacterium adolescentis exerts inter-strain differences in alleviating constipation induced by loperamide in BALB/c mice and to analyze the main reasons for these differences. BALB/c mice underwent gavage with B. adolescentis (CCFM 626, 667, and 669) once per day for 17 days. The primary outcome measures included related constipation indicators, and the secondary outcome measures were the basic biological characteristics of the strains, the concentration changes of short-chain fatty acids in feces, and the changes in the fecal flora. B. adolescentis CCFM 669 and 667 relieved constipation symptoms by adhering to intestinal epithelial cells, growing quickly in vitro and increasing the concentrations of propionic and butyric acids. The effect of B. adolescentis on the gut microbiota in mice with constipation was investigated via 16S rRNA metagenomic analysis. The results revealed that the relative abundance of Lactobacillus increased and the amount of Clostridium decreased in the B. adolescentis CCFM 669 and 667 treatment groups. In conclusion, B. adolescentis exhibits strain-specific effects in the alleviation of constipation, mostly due to the strains’ growth rates, adhesive capacity and effects on the gut microbiome and microenvironment.

Potential anti-genotoxic effect of sodium butyrate to modulate induction of DNA damage by tamoxifen citrate in rat bone marrow cells

Sodium butyrate (SB) is one of the histone deacetylase inhibitors (HDACi's) that is recently evidenced to have a prooxidant activity and an ability to reduce hydrogen peroxide-induced DNA damage. Since the majority of estrogen receptor positive breast cancer patients are treated with tamoxifen citrate (TC), which exerts well established oxidative and genotoxic effects, thus the basic objective of this study is to determine whether SB could ameliorate or curate tamoxifen citrate-induced oxidative DNA damage and genotoxic effect in vivo through up-regulation of some antioxidant enzymes. The individual and combined effects of SB and TC have been examined on rat bone marrow cells, using Micronucleus assays (MN), Comet assay, DNA fragmentation, expression of some antioxidant genes using Real time-PCR and finally, oxidative stress analysis. SB significantly increased the mitotic activity (P < 0.05), while TC induced marked micronuclei and oxidative DNA damage, in the SB post-treatment group, the combination of SB (300 mg/kg) and TC (40 mg/kg) was able to decrease the induction of MN and oxidative DNA damage through up-regulation of Cat, Sod and Gpx1 genes significantly at (P < 0.05) more efficiently than that in the SB pre-treatment one. Therefore, we postulate that SB can be used therapeutically in combination with TC treatment to modulate TC genotoxic effect by reducing its oxidative stress, and thus being an appropriate agonist agent to combine with TC than each compound alone.

Ileal Digesta Nondietary Substrates from Cannulated Pigs Are Major Contributors to In Vitro Human Hindgut Short-Chain Fatty Acid Production

BACKGROUND

It has been assumed that short-chain fatty acids (SCFAs) in the colon originate mainly from dietary fiber fermentation. However, SCFAs in the colon are also produced from the fermentation of nondietary material.

OBJECTIVES

We aimed to predict the relative contributions of dietary and nondietary substrates in the production of SCFAs with the use of a human fecal inoculum for diets containing kiwifruit as a model fiber.

METHODS

Terminal ileal digesta were collected from ileal-cannulated male pigs [n = 7; mean ± SD: 41.4 ± 2.98 kg body weight] adapted (44-d feeding) to diets containing either 25 g/kg dry matter (DM) of kiwifruit fiber (KFf) (25 KFf) or 50 g/kg DM of KFf (50 KFf) and then again after receiving a fiber-free diet (n = 14) for a further 7 d. Pigs were used as a model for adult humans for digestion in the upper digestive tract (mouth to the terminal ileum). The ileal digesta (either unfractionated or fractionated into crude mucin and microbial fractions) were fermented in vitro for 24 h with the use of a fresh human fecal inoculum to predict SCFA production in the human hindgut.

RESULTS

SCFAs of nondietary origin were the main source (65%) of total SCFAs predicted to be produced in the human hindgut. The contribution of SCFAs from KFf was only 26% of the total SCFAs, and that from total dietary material was 35%. The higher contribution of nondietary material to total predicted SCFA production was observed at both dietary fiber concentrations. Predicted SCFA intake from dietary fiber was 76 and 105 mmol/kg diet DM intake for the diets containing 25 KFf and 50 KFf, respectively, and from the nondietary substrates it was 178 and 280 mmol/kg diet DM intake, respectively.

CONCLUSION

A considerable proportion of the SCFAs produced in the human hindgut seems to be derived from the fermentation of nondietary substrates.

Bifidobacteria exert species-specific effects on constipation in BALB/c mice

Edible bifidobacteria exerted species-specific effects in relieving constipation.

Supplementation of piglets with nutrient-dense complex milk replacer improves intestinal development and microbial fermentation

Weaning of piglets causes stress due to environmental, behavioral, and nutritional stressors and can lead to postweaning diarrhea and impaired gut development. The diet changes experienced during weaning require extensive adaptation of the digestive system. A well-developed piglet that had creep-feed experience before weaning performs better after weaning. In the current study, the effect of providing sow-fed piglets with a supplemental nutrient-dense complex milk replacer (NDM) on gut development and growth performance was studied. Litters of sows with similar parities (3.6 ± 0.8) and similar numbers of live born piglets (13.5 ± 0.3) were assigned to 1 of 2 groups: 1 group of piglets had ad libitum access to NDM from Day 2 through 21 after birth, whereas the other group was used as controls. Nutrient-dense complex milk replacer-fed piglets were shown to be significantly heavier after 21 d of supplementation compared with the control piglets. At Day 21, 3 piglets from each litter were euthanized for morphological and functional analyses of the intestinal tract. The small intestines of NDM-fed piglets had significantly higher weights (g) as well as significantly higher relative weight:length ratios (g//cm) compared with the small intestines of control piglets ( < 0.05). Morphometric analysis demonstrated that villi length and numbers of goblet cells did not differ between groups. However, NDM-fed piglets had deeper crypts ( < 0.001) and an increased expression of the cell-proliferation marker proliferating cell nuclear antigen in crypts ( < 0.05), suggesting higher cell-proliferation rates. The gene encoding IGF-1 showed a tendency to higher gene expression in the jejunum from NDM-fed piglets ( = 0.07) compared with the jejunum from control piglets, suggesting that IGF-1 might be involved in the regulation of cell proliferation and intestinal growth. Finally, as a result of dietary fiber in NDM, piglets showed significantly increased concentrations of metabolic fermentation products. This suggests differences in metabolic activity in the colon between treatment groups. In conclusion, providing sow-fed piglets with NDM before weaning stimulates intestinal proliferation, leading to increased circular growth. Nutrient-dense complex milk replacer supplementation might, therefore, help piglets through the transition period at weaning by increased BW and increased capacity for uptake of nutrients.

Free fatty acid G-protein coupled receptor signaling in M1 skewed white adipose tissue macrophages

Obesity is associated with the establishment and maintenance of a low grade, chronically inflamed state in the white adipose tissue (WAT) of the body. The WAT macrophage population is a major cellular participant in this inflammatory process that significantly contributes to the pathophysiology of the disease, with the adipose depots of obese individuals, relative to lean counterparts, having an elevated number of macrophages that are skewed towards a pro-inflammatory phenotype. Alterations in the WAT lipid micro-environment, and specifically the availability of free fatty acids, are believed to contribute towards the obesity-related quantitative and functional changes observed in these cells. This review specifically addresses the involvement of the five G-protein coupled free fatty acid receptors which bind exogenous FFAs and signal in macrophages. Particular focus is placed on the involvement of these receptors in macrophage migration and cytokine production, two important aspects that modulate inflammation.

Differential modulation of flagella expression in enterohaemorrhagic Escherichia coli O157: H7 by intestinal short-chain fatty acid mixes

During passage through the gastrointestinal tract, enterohaemorrhagic Escherichia coli (EHEC) encounters numerous stresses, each producing unique antimicrobial conditions. Beyond surviving these stresses, EHEC may also use them as cues about the local microenvironment to modulate its virulence. Of particular interest is how exposure to changing concentrations of short-chain fatty acids (SCFAs) associated with passage through the small and large intestines affects EHEC virulence, as well as flagella expression and motility specifically. In this study, we investigate the impact of exposure to SCFA mixes simulating concentrations and compositions within the small and large intestines on EHEC flagella expression and function. Using a combination of DNA microarray, quantitative real-time PCR, immunoblot analysis, flow cytometry and motility assays, we show that there is a marked, significant upregulation of flagellar genes, the flagellar protein, FliC, and motility when EHEC is exposed to SCFA mixes representative of the small intestine. By contrast, when EHEC is exposed to SCFA mixes representative of the large intestine, there is a significant downregulation of flagellar genes, FliC and motility. Our results demonstrate that EHEC modulates flagella expression and motility in response to SCFAs, with differential responses associated with SCFA mixes typical of the small and large intestines. This research contributes to our understanding of how EHEC senses and responds to host environmental signals and the mechanisms it uses to successfully infect the human host. Significantly, it also suggests that EHEC is using this key gastrointestinal chemical signpost to cue changes in flagella expression and motility in different locations within the host intestinal tract.

Role of bioactive fatty acids in nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) is characterized by fat deposition in hepatocytes, and a strong association with nutritional factors. Dietary fatty acids are classified according to their biochemical properties, which confer their bioactive roles. Monounsaturated fatty acids have a dual role in various human and murine models. In contrast, polyunsaturated fatty acids exhibit antiobesity, anti steatosic and anti-inflammatory effects. The combination of these forms of fatty acids—according to dietary type, daily intake and the proportion of n-6 to n-3 fats—can compromise hepatic lipid metabolism. A chemosensory rather than a nutritional role makes bioactive fatty acids possible biomarkers for NAFLD. Bioactive fatty acids provide health benefits through modification of fatty acid composition and modulating the activity of liver cells during liver fibrosis. More and better evidence is necessary to elucidate the role of bioactive fatty acids in nutritional and clinical treatment strategies for patients with NAFLD.

Soluble Corn Fiber Increases Calcium Absorption Associated with Shifts in the Gut Microbiome: A Randomized Dose-Response Trial in Free-Living Pubertal Females

BACKGROUND

Soluble corn fiber (SCF; 12 g fiber/d) is shown to increase calcium absorption efficiency, associated with shifts in the gut microbiota in adolescent males and females who participated in a controlled feeding study.

OBJECTIVE

We evaluated the dose response of 0, 10, and 20 g fiber/d delivered by PROMITOR SCF 85 (85% fiber) on calcium absorption, biochemical bone properties, and the fecal microbiome in free-living adolescents.

METHODS

Healthy adolescent females (n = 28; aged 11-14 y) randomly assigned into a 3-phase, double-blind, crossover study consumed SCF for 4 wk at each dose (0, 10, and 20 g fiber/d from SCF) alongside their habitual diet and were followed by 3-d clinical visits and 3-wk washout periods. Stable isotope ((44)Ca and (43)Ca) enrichment in pooled urine was measured by inductively coupled plasma mass spectrometry. Fecal microbial community composition was assessed by high-throughput sequencing (Illumina) of polymerase chain reaction-amplified 16S rRNA genes. Mixed model ANOVA and Friedman analysis were used to determine effects of SCF on calcium absorption and to compare mean microbial proportions, respectively.

RESULTS

Calcium absorption increased significantly with 10 (13.3% ± 5.3%; P = 0.042) and 20 g fiber/d (12.9% ± 3.6%; P = 0.026) from SCF relative to control. Significant differences in fecal microbial community diversity were found after consuming SCF (operational taxonomic unit measures of 601.4 ± 83.5, 634.5 ± 83.8, and 649.6 ± 75.5 for 0, 10, and 20 g fiber/d, respectively; P < 0.05). Proportions of the genus Parabacteroides significantly increased with SCF dose (1.1% ± 0.8%, 2.1% ± 1.6%, and 3.0% ± 2.0% for 0, 10, and 20 g fiber/d from SCF, respectively; P < 0.05). Increases in calcium absorption positively correlated with increases in Clostridium (r = 0.44, P = 0.023) and unclassified Clostridiaceae (r = 0.40, P = 0.040).

CONCLUSIONS

SCF, a nondigestible carbohydrate, increased calcium absorption in free-living adolescent females. Two groups of bacteria may be involved, one directly fermenting SCF and the second fermenting SCF metabolites further, thereby promoting increased calcium absorption. This trial was registered at clinicaltrials.gov as NCT01660503.

Potential misinterpretation of the nutritional value of dietary fiber: correcting fiber digestibility values for nondietary gut-interfering material

The aim of this review is to identify the origin and implications of a nondietary material present in digesta and feces that interferes with the determination of dietary fiber in gastrointestinal contents. Negative values for ileal and fecal digestibility of dietary fiber are commonly reported in the literature for monogastric animal species, including humans. As negative values are not possible physiologically, this suggests the existence of a nondietary material in the gastrointestinal contents and feces that interferes with the accurate determination of dietary fiber digestibility when conventional methods of fiber determination are applied. To date, little attention has been given to this nondietary interfering material, which appears to be influenced by the type and concentration of fiber in the diet. Interestingly, estimates of dietary fiber digestibility increase substantially when corrected for the nondietary interfering material, which suggests that currently reported values underestimate the digestibility of dietary fiber and may misrepresent where, in the digestive tract, fermentation of fiber occurs. A new perspective of dietary fiber digestion in the gastrointestinal tract is developing, leading to a better understanding of the contribution of dietary fiber to health.

In vitro fermentation characteristics, in vivo ileal and total tract nutrient digestibilities, and fecal microbiota responses of dogs to α-cyclodextrin

The objectives were to examine in vitro fermentation characteristics, in vivo nutrient digestibility, fecal microbiota, and serum lipid profiles as affected by α-cyclodextrin (ACD) supplementation. Short-chain fatty acid (SCFA) production was measured after in vitro fermentation for 3, 6, 9, and 12 h of ACD, β-cyclodextrin, and γ-cyclodextrin. Five mixed-breed hounds were used in a Latin square design. Each experimental period comprised 14 d, including 10 d for diet adaptation and 4 d for fecal collection. Dogs were fed, twice a day, an extruded diet made with poultry byproduct meal and brewer's rice as the main ingredients. Dogs were supplemented with 0, 1, 2, 3, or 4 g of ACD diluted in 15 mL of water twice daily for a total of 0, 2, 4, 6, and 8 g ACD/d. Maximal in vitro production of total SCFA was lowest for ACD. However, the greatest maximal production of propionate was noted for ACD treatment. Total tract nutrient digestibility and fecal DM concentration linearly decreased ( < 0.05) for treatment groups receiving ACD; no changes were observed for ileal digestibility. Serum cholesterol and triglyceride concentrations were within normal ranges for dogs and were not different among treatments. Similarly, no changes in fecal microbiota were observed. Overall, ACD supplementation appears to have no effect on nutrient absorption in the small intestine but may alter fermentation in the large bowel, which could lead to a higher proportion of propionate production as observed in the in vitro experiment.

Microbiome-Metabolome Responses in the Cecum and Colon of Pig to a High Resistant Starch Diet

Currently, knowledge about the impact of long-term intake of high resistant starch diet on pig hindgut microbiota and metabolite profile is limited. In this study, a combination of the pyrosequencing and the mass spectrometry (MS)-based metabolomics techniques were used to investigate the effects of a raw potato starch (RPS, high in resistant starch) diet on microbial composition and microbial metabolites in the hindgut of pig. The results showed that Coprococcus, Ruminococcus, and Turicibacter increased significantly, while Sarcina and Clostridium decreased in relative abundances in the hindgut of pigs fed RPS. The metabolimic analysis revealed that RPS significantly affected starch and sucrose metabolites, amino acid turnover or protein biosynthesis, lipid metabolites, glycolysis, the pentose phosphate pathway, inositol phosphate metabolism, and nucleotide metabolism. Furthermore, a Pearson's correlation analysis showed that Ruminococcus and Coprococcus were positively correlated with glucose-6-phosphate, maltose, arachidonic acid, 9, 12-octadecadienoic acid, oleic acid, phosphate, but negatively correlated with α-aminobutyric acid. However, the correlation of Clostridium and Sarcina with these compounds was in the opposite direction. The results suggest that RPS not only alters the composition of the gut microbial community but also modulates the metabolic pathway of microbial metabolism, which may further affect the hindgut health of the host.

Systemic Concentrations of Short Chain Fatty Acids Are Elevated in Salmonellosis and Exacerbation of Familial Mediterranean Fever

Gut microbiota-produced short chain fatty acids (SCFAs) play an important role in the normal human metabolism and physiology. Although the gradients of SCFAs from the large intestine, where they are largely produced, to the peripheral blood as well as the main routes of SCFA metabolism by different organs are known well for the healthy state, there is a paucity of information regarding how these are affected in disease. In particular, how the inflammation caused by infection or autoinflammatory disease affect the concentration of SCFAs in the peripheral venous blood. In this work, we revealed that diseases caused either by infectious agents (two Salmonella enterica serovars, S. Enteritidis, and S. Typhimurium) or by the exacerbation of an autoinflammatory disease, familial Mediterranean fever (FMF), both result in a significantly elevated systemic concentration of SCFAs. In the case of salmonellosis the concentration of SCFAs in peripheral blood was significantly and consistently higher, from 5- to 20-fold, compared to control. In the case of FMF, however, a significant increase of SCFAs in the peripheral venous blood was detected only in the acute phase of the disease, with a lesser impact in remission. It seems counterintuitive that the dysbiotic conditions, with a reduced number of gut microorganisms, produce such an effect. This phenomenon, however, must be appraised within the context of how the inflammatory diseases affect the normal physiology. We discuss a number of factors that may contribute to the “leak” and persistence of gut-produced SCFAs into the systemic circulation in infectious and autoinflammatory diseases.

NMR-based fecal metabolomics fingerprinting as predictors of earlier diagnosis in patients with colorectal cancer

Colorectal cancer (CRC) is a growing cause of mortality in developing countries, warranting investigation into its earlier detection for optimal disease management. A metabolomics based approach provides potential for noninvasive identification of biomarkers of colorectal carcinogenesis, as well as dissection of molecular pathways of pathophysiological conditions. Here, proton nuclear magnetic resonance spectroscopy (1HNMR) -based metabolomic approach was used to profile fecal metabolites of 68 CRC patients (stage I/II=20; stage III=25 and stage IV=23) and 32 healthy controls (HC). Pattern recognition through principal component analysis (PCA) and orthogonal partial least squares-discriminant analysis (OPLS-DA) was applied on 1H-NMR processed data for dimension reduction. OPLS-DA revealed that each stage of CRC could be clearly distinguished from HC based on their metabolomic profiles. Successive analyses identified distinct disturbances to fecal metabolites of CRC patients at various stages, compared with those in cancer free controls, including reduced levels of acetate, butyrate, propionate, glucose, glutamine, and elevated quantities of succinate, proline, alanine, dimethylglycine, valine, glutamate, leucine, isoleucine and lactate. These altered fecal metabolites potentially involved in the disruption of normal bacterial ecology, malabsorption of nutrients, increased glycolysis and glutaminolysis. Our findings revealed that the fecal metabolic profiles of healthy controls can be distinguished from CRC patients, even in the early stage (stage I/II), highlighting the potential utility of NMR-based fecal metabolomics fingerprinting as predictors of earlier diagnosis in CRC patients.

Diet, Microbiota, Obesity, and NAFLD: A Dangerous Quartet

Recently, the importance of the gut-liver-adipose tissue axis has become evident. Nonalcoholic fatty liver disease (NAFLD) is the hepatic disease of a systemic metabolic disorder that radiates from energy-surplus induced adiposopathy. The gut microbiota has tremendous influences in our whole-body metabolism, and is crucial for our well-being and health. Microorganisms precede humans in more than 400 million years and our guest flora evolved with us in order to help us face aggressor microorganisms, to help us maximize the energy that can be extracted from nutrients, and to produce essential nutrients/vitamins that we are not equipped to produce. However, our gut microbiota can be disturbed, dysbiota, and become itself a source of stress and injury. Dysbiota may adversely impact metabolism and immune responses favoring obesity and obesity-related disorders such as insulin resistance/diabetes mellitus and NAFLD. In this review, we will summarize the latest evidence of the role of microbiota/dysbiota in diet-induced obesity and NAFLD, as well as the potential therapeutic role of targeting the microbiota in this set.

Procedure optimization for extracting short-chain fatty acids from human faeces

Short-chain fatty acids play an important role in the physiology and metabolism of the colon. Disturbed balance of such compounds in human gut can significantly contribute to etiological factors of various gastrointestinal disorders and it may also increase the risk of developing cancer or cardiovascular diseases. The aim of the study was to select the optimal parameters for acetic, propionic and butyric acids extraction from stool samples. The experimental conditions were optimized with respect to the solvent sample shacking time, sample ultrasounds (Ultrasound-Assisted Extraction, UAE) exposure time and the number of extractions from the particulate stool samples. The screening of experimental parameters was conducted with fractional factorial design of experiments, namely 3(3-1). The optimal conditions for UAE were found, namely ultrasound digestion time of 40 min (at 35°C), shaking time of 4 min, and the three subsequent extractions.

Potency of pre-post treatment of coenzyme Q10 and melatonin supplement in ameliorating the impaired fatty acid profile in rodent model of autism

BACKGROUND

Abnormalities in fatty acid metabolism and membrane fatty acid composition play a part in a wide range of neurodevelopmental and psychiatric disorders. Altered fatty acid homeostasis as a result of insufficient dietary supplementation, genetic defects, the function of enzymes involved in their metabolism, or mitochondrial dysfunction contributes to the development of autism.

OBJECTIVE

This study evaluates the association of altered brain lipid composition and neurotoxicity related to autism spectrum disorders in propionic acid (PA)-treated rats.

DESIGN

Forty-eight young male western albino rats were used in this study. They were grouped into six equal groups with eight rats in each. The first group received only phosphate buffered saline (control group). The second group received a neurotoxic dose of buffered PA (250 mg/kg body weight/day for 3 consecutive days). The third and fourth groups were intoxicated with PA as described above followed by treatment with either coenzyme Q (4.5 mg/kg body weight) or melatonin (10 mg/kg body weight) for 1 week (therapeutically treated groups). The fifth and sixth groups were administered both compounds for 1 week prior to PA (protected groups). Methyl esters of fatty acid were extracted with hexane, and the fatty acid composition of the extract was analyzed on a gas chromatography.

RESULTS

The obtained data proved that fatty acids are altered in brain tissue of PA-treated rats. All saturated fatty acids were increased while all unsaturated fatty acids were significantly decreased in the PA-treated group and relatively ameliorated in the pre-post melatonin and coenzyme Q groups.

CONCLUSIONS

Melatonin and coenzyme Q were effective in restoring normal level of most of the impaired fatty acids in PA-intoxicated rats which could help suggest both as supplements to ameliorate the autistic features induced in rat pups.

Biotransformation of polyphenols in a dynamic multistage gastrointestinal model

A multi-reactor gastrointestinal model was used to digest a mixture of pure polyphenol compounds, including non-flavonoid phenolic acids (chlorogenic acid, caffeic acid, ferulic acid) and a flavonoid (rutin) to identify phenolic metabolites and short chain fatty acids (SCFAs) and compare relative antioxidant capacities following a 24h digestion. Biotransformation of these polyphenols occurred in the colonic compartments generating phenylpropionic, benzoic, phenylacetic and cinnamic acids. Total SCFAs increased in all colonic vessels with a rise in the proportion of propionic to acetic acid. Antioxidant capacity increased significantly in all compartments, but first in the stomach, small intestine and ascending colon. After 24h, the colonic vessels without parent polyphenols, but containing new metabolites, had antioxidant capacities similar to the stomach and small intestine, containing parent compounds. Biotransformation of pure polyphenols resulted in different phenolic metabolite and SCFAs profiles in each colonic segment, with important health implications for these colonic compartments.

Dietary resistant starch contained foods and breast cancer risk: a case-control study in northwest of Iran

BACKGROUND

A protective effect of resistant starch (RS) containing foods on carcinogenesis has been shown from several lines of experimental evidence for gastrointestinal cancers. Therefore, we aimed to investigate the association between RS contained foods and breast cancer (BC) risk in a hospital-based, age- and origin- matched, case-control study.

MATERIALS AND METHODS

A validated, semi-quantitative, food frequency questionnaire (FFQ) was completed by 306 women newly diagnosed with BC aged 25 to 65 years, and 309 healthy women as matched controls. Odds ratios (ORs) and 95% confidence intervals (95%CI) were estimated using conditional logistic regression models.

RESULTS

Reduced BC risk was associated with the highest tertile of whole-wheat bread and boiled potato consumption with adjusted ORs at 0.34 (95%CI: 0.19-0.59) and 0.61 (95%CI: 0.37- 0.99), respectively. Among consumers of whole-wheat bread consumers were considered, the protective role of cereals remained relatively apparent at higher intakes level of fiber rich breads at adjusted models (OR=0.53, 95%CI: 0.28-1.01). Moreover, high intake of legumes was found out to be a significant protective dietary factor against risk of BC development with an OR of 0.01 (95%CI: 0.03-0.13). However, consumption of white bread and biscuits was positively related to BC risk.

CONCLUSIONS

Our results show that certain RS containing foods, in particular whole wheat bread, legumes and boiled potato may reduce BC risk, whereas higher intake of white bread and biscuits may be related to increased BC risk.

Bacteria within the Gastrointestinal Tract Microbiota Correlated with Improved Growth and Feed Conversion: Challenges Presented for the Identification of Performance Enhancing Probiotic Bacteria

Identification of bacteria associated with desirable productivity outcomes in animals may offer a direct approach to the identification of probiotic bacteria for use in animal production. We performed three controlled chicken trials (n = 96) to investigate caecal microbiota differences between the best and poorest performing birds using four performance measures; feed conversion ratio (FCR), utilization of energy from the feed measured as apparent metabolisable energy, gain rate (GR), and amount of feed eaten (FE). The shifts in microbiota composition associated with the performance measures were very different between the three trials. Analysis of the caecal microbiota revealed that the high and low FCR birds had significant differences in the abundance of some bacteria as demonstrated by shifts in microbiota alpha and beta diversity. Trials 1 and 2 showed significant overall community shifts, however, the microbial changes driving the difference between good and poor performers were very different. Lachnospiraceae, Ruminococcaceae, and Erysipelotrichaceae families and genera Ruminococcus, Faecalibacterium and multiple lineages of genus Clostridium (from families Lachnospiraceae, Ruminococcaceae, and Erysipelotrichaceae) were highly abundant in good FCR birds in Trial 1. Different microbiota was associated with FCR in Trial 2; Catabacteriaceae and unknown Clostridiales family members were increased in good FCR and genera Clostridium (from family Clostridiaceae) and Lactobacillus were associated with poor FCR. Trial 3 had only mild microbiota differences associated with all four performance measures. Overall, the genus Lactobacillus was correlated with feed intake which resulted in poor FCR performance. The genus Faecalibacterium correlated with improved FCR, increased GR and reduced FE. There was overlap in phylotypes correlated with improved FCR and GR, while different microbial cohorts appeared to be correlated with FE. Even under controlled conditions different cohorts of birds developed distinctly different microbiotas. Within the different trial groups the abundance of certain bacterial groups correlated with productivity outcomes. However, with different underlying microbiotas there were different bacteria correlated with performance. The challenge will be to identify probiotic bacteria that can reliably deliver favorable outcomes from diverse microbiotas.

Artificially Sweetened Beverage Consumption Is Positively Associated with Newly Diagnosed Diabetes in Normal-Weight but Not in Overweight or Obese Brazilian Adults

BACKGROUND

Recent animal studies suggest that artificially sweetened beverage (ASB) consumption increases diabetes risk.

OBJECTIVE

We examined the relation of ASB intake with newly diagnosed diabetes and measures of glucose homeostasis in a large Brazilian cohort of adults.

METHODS

We used cross-sectional data from 12,884 participants from the Brazilian Longitudinal Study of Adult Health (ELSA-Brasil). ASB use was assessed by questionnaire and newly diagnosed diabetes by a 2-h 75-g oral glucose tolerance test and/or glycated hemoglobin. Logistic and linear regression analyses were performed to examine the association of ASB consumption with diabetes and continuous measures of glucose homeostasis, respectively.

RESULTS

Although ASB consumption was not associated with diabetes in logistic regression analyses after adjustment for body mass index (BMI; in kg/m(2)) overall, the association varied across BMI categories (P-interaction = 0.04). Among those with a BMI <25, we found a 15% increase in the adjusted odds of diabetes for each increase in the frequency of ASB consumption per day (P = 0.001); compared with nonusers, ASB users presented monotonic increases in the adjusted ORs (95% CIs) of diabetes with increased frequency of consumption: 1.03 (0.60, 1.77), 1.43 (0.93, 2.20), 1.62 (1.08, 2.44), and 2.51 (1.40, 4.50) for infrequent, 1-2, 3-4, and >4 times/d, respectively. In linear regression analyses, among normal-weight individuals, greater ASB consumption was also associated with increased fasting glucose concentrations (P = 0.01) and poorer β-cell function (P = 0.009). No such associations were seen for those with BMI ≥25. In fact, in overweight or obese participants, greater ASB consumption was significantly associated with improved indexes of insulin resistance and 2-h postload glucose.

CONCLUSIONS

Normal-weight, but not excess-weight, individuals with greater ASB consumption presented diabetes more frequently and had higher fasting glucose and poorer β-cell function.

GPR41 and GPR43 in Obesity and Inflammation - Protective or Causative?

GPR41 and GPR43 are a pair of mammalian G protein-coupled receptors (GPCRs) expressed in human adipocytes, colon epithelial cells, and peripheral blood mononuclear cells. These receptors are activated by short-chain fatty acids (SCFAs) such as acetate, propionate, and butyrate – which are produced during dietary fiber fermentation by resident gut bacteria. This unique ligand specificity suggests that GPR41 and GPR43 may mediate the interaction between the human host and the gut microbiome. Indeed, studies on knockout mice implicate GPR41 and GPR43 in chronic inflammatory disorders such as obesity, colitis, asthma and arthritis. However, whether GPR41 and GPR43 are protective or causative is inconsistent between studies. This discrepancy may be due to differences in the disease models used, the inbred mouse strains, or non-specific knockout effects. Here, we review the latest findings on GPR41 and GPR43, highlighting contradictory observations. With GPR41 and GPR43 being considered as drug targets, it is pertinent that their role is fully elucidated. We propose that future studies on human tissues, ex vivo, may allow us to confirm the role of GPR41 and GPR43 in humans, be it protective or causative.

Probiotics, prebiotics and colorectal cancer prevention

Colorectal cancer (CRC), the third major cause of mortality among various cancer types in United States, has been increasing in developing countries due to varying diet and dietary habits and occupational hazards. Recent evidences showed that composition of gut microbiota could be associated with the development of CRC and other gut dysbiosis. Modulation of gut microbiota by probiotics and prebiotics, either alone or in combination could positively influence the cross-talk between immune system and microbiota, would be beneficial in preventing inflammation and CRC. In this review, role of probiotics and prebiotics in the prevention of CRC has been discussed. Various epidemiological and experimental studies, specifically gut microbiome research has effectively improved the understanding about the role of probiotics and microbial treatment as anticarcinogenic agents. A few human studies support the beneficial effect of probiotics and prebiotics; hence, comprehensive understanding is urgent to realize the clinical applications of probiotics and prebiotics in CRC prevention.

Antioxidant Drug Tempol Promotes Functional Metabolic Changes in the Gut Microbiota

Recent studies have identified the important role of the gut microbiota in the pathogenesis and progression of obesity and related metabolic disorders. The antioxidant tempol was shown to prevent or reduce weight gain and modulate the gut microbiota community in mice; however, the mechanism by which tempol modulates weight gain/loss with respect to the host and gut microbiota has not been clearly established. Here we show that tempol (0, 1, 10, and 50 mg/kg p.o. for 5 days) decreased cecal bacterial fermentation and increased fecal energy excretion in a dose-dependent manner. Liver (1)H NMR-based metabolomics identified a dose-dependent decrease in glycogen and glucose, enhanced glucogenic and ketogenic activity (tyrosine and phenylalanine), and increased activation of the glycolysis pathway. Serum (1)H NMR-based metabolomics indicated that tempol promotes enhanced glucose catabolism. Hepatic gene expression was significantly altered as demonstrated by an increase in Pepck and G6pase and a decrease in Hnf4a, ChREBP, Fabp1, and Cd36 mRNAs. No significant change in the liver and serum metabolomic profiles was observed in germ-free mice, thus establishing a significant role for the gut microbiota in mediating the beneficial metabolic effects of tempol. These results demonstrate that tempol modulates the gut microbial community and its function, resulting in reduced host energy availability and a significant shift in liver metabolism toward a more catabolic state.

Can We Prevent Obesity-Related Metabolic Diseases by Dietary Modulation of the Gut Microbiota?

Obesity increases the risk of type 2 diabetes, cardiovascular diseases, and certain cancers, which are among the leading causes of death worldwide. Obesity and obesity-related metabolic diseases are characterized by specific alterations in the human gut microbiota. Experimental studies with gut microbiota transplantations in mice and in humans indicate that a specific gut microbiota composition can be the cause and not just the consequence of the obese state and metabolic disease, which suggests a potential for gut microbiota modulation in prevention and treatment of obesity-related metabolic diseases. In addition, dietary intervention studies have suggested that modulation of the gut microbiota can improve metabolic risk markers in humans, but a causal role of the gut microbiota in such studies has not yet been established. Here, we review and discuss the role of the gut microbiota in obesity-related metabolic diseases and the potential of dietary modulation of the gut microbiota in metabolic disease prevention and treatment.

In vitro extraction and fermentation of polyphenols from grape seeds (Vitis vinifera) by human intestinal microbiota

The effects of several parameters on the extraction yield of total polyphenols from grape seeds by pressurized liquid extraction were investigated.

Selective Manipulation of the Gut Microbiota Improves Immune Status in Vertebrates

All animals develop in association with complex microbial communities. It is now well established that commensal microbiota is essential for the correct functionality of each organ in the host. Particularly, the commensal gastro-intestinal microbiota (CGIM) is a key factor for development, immunity and nutrient conversion, rendering them bio-available for various uses. Thus, nutritional inputs generate a positive loop in maintaining host health and are essential in shaping the composition of the CGIM communities. Probiotics, which are live exogenous microorganisms, selectively provided to the host, are a promising concept for manipulating the microbiota and thus for increasing the host health status. Nevertheless, most mechanisms induced by probiotics to fortify the immune system are still a matter of debate. Alternatively, prebiotics, which are non-digestible food ingredients, can favor the growth of specific target groups of CGIM. Several metabolites are produced by the CGIM, one of the most important are the short-chain fatty acids (SCFAs), which emerge from the fermentation of complex carbohydrates. SCFAs have been recognized as key players in triggering beneficial effects elicited by simple diffusion and by specific receptors present, thus, far only in epithelial cells of higher vertebrates at different gastro-intestinal locations. However, both strategies have shown to provide resistance against pathogens during periods of high stress. In fish, knowledge about the action of pro- and prebiotics and SCFAs is still limited. Thus, in this review, we briefly summarize the mechanisms described on this topic for higher vertebrates and discuss why many of them may operate in the fish gut representing a model for different mucosal tissues

Gut Microbiota: A Modulator of Brain Plasticity and Cognitive Function in Ageing

Gut microbiota have recently been a topic of great interest in the field of microbiology, particularly their role in normal physiology and its influence on human health in disease. A large body of research has supported the presence of a pathway of communication between the gut and the brain, modulated by gut microbiota, giving rise to the term “microbiota-gut-brain” axis. It is now thought that, through this pathway, microbiota can affect behaviour and modulate brain plasticity and cognitive function in ageing. This review summarizes the evidence supporting the existence of such a connection and possible mechanisms of action whereby microbiota can influence the function of the central nervous system. Since normalisation of gut flora has been shown to prevent changes in behaviour, we further postulate on possible therapeutic targets to intervene with cognitive decline in ageing. The research poses various limitations, for example uncertainty about how this data translates to broad human populations. Nonetheless, the microbiota-gut-brain axis is an exciting field worthy of further investigation, particularly with regards to its implications on the ageing population.

Hepatic Uptake of Rectally Administered Butyrate Prevents an Increase in Systemic Butyrate Concentrations in Humans

BACKGROUND

Short-chain fatty acids (SCFAs), fermentation products of undigested fibers, are considered beneficial for colonic health. High plasma concentrations are potentially harmful; therefore, information about systemic SCFA clearance is needed before therapeutic use of prebiotics or colonic SCFA administration.

OBJECTIVE

The aim of this study was to investigate the effect of rectal butyrate administration on SCFA interorgan exchange.

METHODS

Twelve patients (7 men; age: 66.4 ± 2.0 y; BMI 24.5 ± 1.4 kg/m(2)) undergoing upper abdominal surgery participated in this randomized placebo-controlled trial. During surgery, 1 group received a butyrate enema (100 mmol sodium butyrate/L; 60 mL; n = 7), and the other group a placebo (140 mmol 0.9% NaCl/L; 60 mL; n = 5). Before and 5, 15, and 30 min after administration, blood samples were taken from the radial artery, hepatic vein, and portal vein. Plasma SCFA concentrations were analyzed, and fluxes from portal-drained viscera, liver, and splanchnic area were calculated and used for the calculation of the incremental area under the curve (iAUC) over a 30-min period.

RESULTS

Rectal butyrate administration led to higher portal butyrate concentrations at 5 min compared with placebo (92.2 ± 27.0 μmol/L vs. 14.3 ± 3.4 μmol/L, respectively; P < 0.01). In the butyrate-treated group, iAUCs of gut release (282.8 ± 133.8 μmol/kg BW · 0.5 h) and liver uptake (-293.7 ± 136.0 μmol/kg BW · 0.5 h) of butyrate were greater than in the placebo group [-16.6 ± 13.4 μmol/kg BW · 0.5 h (gut release) and 16.0 ± 13.8 μmol/kg BW · 0.5 h (liver uptake); P = 0.01 and P < 0.05, respectively]. As a result, splanchnic butyrate release did not differ between groups.

CONCLUSION

After colonic butyrate administration, splanchnic butyrate release was prevented in patients undergoing upper abdominal surgery. These observations imply that therapeutic colonic SCFA administration at this dose is safe. The trial was registered at clinicaltrials.gov as NCT02271802.

Kiwifruit fibre level influences the predicted production and absorption of SCFA in the hindgut of growing pigs using a combined in vivo-in vitro digestion methodology

Combined in vivo (ileal cannulated pig) and in vitro (faecal inoculum-based fermentation) digestion methodologies were used to predict the production and absorption of SCFA in the hindgut of growing pigs. Ileal and faecal samples were collected from animals (n 7) fed diets containing either 25 or 50 g/kg DM of kiwifruit fibre from added kiwifruit for 14 d. Ileal and faecal SCFA concentrations normalised for food DM intake (DMI) and nutrient digestibility were determined. Ileal digesta were collected and fermented for 38 h using a fresh pig faecal inoculum to predict SCFA production. The predicted hindgut SCFA production along with the determined ileal and faecal SCFA were then used to predict SCFA absorption in the hindgut and total tract organic matter digestibility. The determined ileal and faecal SCFA concentrations (e.g. 8·5 and 4·4 mmol/kg DMI, respectively, for acetic acid for the low-fibre diet) represented only 0·2-3·2 % of the predicted hindgut SCFA production (e.g. 270 mmol/kg DMI for acetic acid). Predicted production and absorption of acetic, butyric and propionic acids were the highest for the high-fibre diet (P0·05). In conclusion, determined ileal and faecal SCFA concentrations represent only a small fraction of total SCFA production, and may therefore be misleading in relation to the effect of diets on SCFA production and absorption. Considerable quantities of SCFA are produced and absorbed in the hindgut of the pig by the fermentation of kiwifruit.

Effect of growth factors, estradiol 17-β, and short chain fatty acids on the intestinal HT29-MTX cells : Growth factors and SCFAs effects on intestinal E12 cells

Peptides growth factors, hormones, and short chain fatty acids (SCFAs) are constantly in contact with the human bowel when secreted by gland or ingested by food, as milk and colostrum, or, as in the case of SCFAs, produced by fermentation processes. This study considers the effect of growth factors, estradiol 17-β, and SCFAs on the metabolic activity and proliferation of undifferentiated HT29-MTX-E12 (E12) cells. In particular, the aim of the present study was the characterization of the human intestinal cell line E12 for its suitability as an in vitro intestinal model for cell-nutrient interaction studies. The effect of insulin-like growth factors (IGF)-I, epidermal growth factors (EGF), transforming growth factor alpha (TGF-α), transforming growth factor beta (TGF-β), estradiol 17-β and butyrate, propionate, and acetate was assessed on metabolic activity and proliferation of E12 cells using AlamarBlue(TM) assay and PicoGreen® assay, respectively. IGF-I and estradiol 17-β significantly (P < 0.05; P < 0.001) increased both metabolic activity and proliferation in a concentration-dependent manner, whereas TGF-α, at the concentration of 1 ng/mL, significantly (P < 0.05) reduced the metabolic activity of the cells. Further, a dose-dependent inhibition of cell metabolic activity was detected in the presence of all SCFAs tested. Butyrate showed to be the most active in the inhibition of E12 metabolic activity and its effect was enhanced by the presence of propionate and acetate. E12 cells, in undifferentiated state, showed to be a suitable in vitro model for cell-nutrient interaction studies, providing an opportunity to examine the potential role of growth factors, hormones and SCFAs in the regulation of the intestinal cell viability.

Products for the treatment of inflammatory bowel disease: a patent review (2013 - 2014)

INTRODUCTION

Inflammatory bowel disease (IBD) consists of Crohn's disease, ulcerative colitis and an unspecific IBD. The unclear etiology of IBD is a limiting factor that complicates the development of new pharmacological treatments and explains the high frequency of refractory patients to current drugs, including both conventional and biological therapies. In view of this, recent progress on the development of novel patented products to treat IBD was reviewed.

AREAS COVERED

Evaluation of the patent literature during the period 2013 - 2014 focused on chemical compounds, functional foods and biological therapy useful for the treatment of IBD.

EXPERT OPINION

Majority of the patents are not conclusive because they were based on data from unspecific methods not related to intestinal inflammation and, when related to IBD models, few biochemical and molecular evaluations that could be corroborating their use in human IBD were presented. On the other hand, methods and strategies using new formulations of conventional drugs, guanylyl cyclase C peptide agonists, compounds that influence anti-adhesion molecules, mAbs anti-type I interferons and anti-integrin, oligonucleotide antisense Smad7, growth factor neuregulin 4 and functional foods, particularly fermented wheat germ with Saccharomyces cerevisiae, are promising products for use in the very near future.

The role of gut adaptation in the potent effects of multiple bariatric surgeries on obesity and diabetes

Bariatric surgical procedures such as vertical sleeve gastrectomy (VSG) and Roux-en-Y gastric bypass (RYGB) are the most potent treatments available to produce sustained reductions in body weight and improvements in glucose regulation. While traditionally these effects are attributed to mechanical aspects of these procedures, such as restriction and malabsorption, a growing body of evidence from mouse models of these procedures points to physiological changes that mediate the potent effects of these surgeries. In particular, there are similar changes in gut hormone secretion, bile acid levels, and composition after both of these procedures. Moreover, loss of function of the nuclear bile acid receptor (FXR) greatly diminishes the effects of VSG. Both VSG and RYGB are linked to profound changes in the gut microbiome that also mediate at least some of these surgical effects. We hypothesize that surgical rearrangement of the gastrointestinal tract results in enteroplasticity caused by the high rate of nutrient presentation and altered pH in the small intestine that contribute to these physiological effects. Identifying the molecular underpinnings of these procedures provides new opportunities to understand the relationship of the gastrointestinal tract to obesity and diabetes as well as new therapeutic strategies to harness the effectiveness of surgery with less-invasive approaches.