Rapid determination of short-chain fatty acids in colonic contents and faeces of humans and rats by acidified water-extraction and direct-injection gas chromatography

Analytical Tools for Disease Diagnosis in Animals via Fecal Volatilome

Volatilome analysis is growing in attention for the diagnosis of diseases in animals and humans. In particular, volatilome analysis in fecal samples is starting to be proposed as a fast, easy and noninvasive method for disease diagnosis. Volatilome comprises volatile organic compounds (VOCs), which are produced during both physiological and patho-physiological processes. Thus, VOCs from a pathological condition often differ from those of a healthy state and therefore the VOCs profile can be used in the detection of some diseases. Due to their strengths and advantages, feces are currently being used to obtain information related to health status in animals. However, they are complex samples, that can present problems for some analytical techniques and require special consideration in their use and preparation before analysis. This situation demands an effort to clarify which analytic options are currently being used in the research context to analyze the possibilities these offer, with the final objectives of contributing to develop a standardized methodology and to exploit feces potential as a diagnostic matrix. The current work reviews the studies focused on the diagnosis of animal diseases through fecal volatilome in order to evaluate the analytical methods used and their advantages and limitations. The alternatives found in the literature for sampling, storage, sample pretreatment, measurement and data treatment have been summarized, considering all the steps involved in the analytical process.

A simplified method for the quantitation of short-chain fatty acids in human stool

A one-vial extraction method for the quantitation of short-chain fatty acids (SCFAs) in human stool was developed. Samples were extracted with an acidified aqueous internal standard solution, sodium sulfate, and diethyl ether, followed by analysis with GC-FID. Accuracy, in terms of relative recovery, was typically between 90 and 110% for most analytes; without internal standard, the accuracy was about 5-34%; the linear dynamic range (LDR) was 0.05-50 μmol per gram; the limit of detection (LOD) was less than or equal to 0.05 μmol per gram; and the (lower) limit of quantitation (LOQ) was 1 μmol per gram. The method is suitable for quantitating acetic acid, propanoic acid, isobutyric acid, butyric acid, isovaleric acid, valeric acid, isohexanoic acid, hexanoic acid, and heptanoic acid. It is not suitable for the quantitation of formic acid. Application to human biological research was tested by the measurement of SCFA in heathy humans. This confirmed that the method performed adequately, and even better than expected, with values up to 150 μmol per gram.

Influence of sanguinarine-based phytobiotic supplementation on post necrotic enteritis challenge recovery

In the animal production industry, plant-derived antimicrobial phytobiotics are used as an alternative to antibiotics. Here we investigated the role sanguinarine-based phytobiotic in broiler recovery from Necrotic Enteritis (NE) infection. A total of 100 one-day-old broiler chicks (Ross 308) were randomly allocated to four treatments: negative control CTR (no challenge, no phytobiotic supplementation); positive control NE (NE challenged); phytobiotic SG (sanguinarine phytobiotic, 0.12 g/kg); and SG + NE, (sanguinarine phytobiotic, 0.12 g/kg and NE challenge). Sanguinarine-based phytobiotic supplementation caused significant changes between the groups in performance, livability and histological measurements, however, these changes were not significantly different between SG + NE and NE groups. Significant improvement was detected in NE lesion score of the duodenum and ileum of SG + NE birds compared to NE challenged birds at the end of the production cycle at 40 days old, indicating improved post-NE recovery with the addition of phytobiotic. Sanguinarine-based phytobiotic supplementation in NE challenged birds significantly compensated for a NE associated reduction of Firmicutes and an increase in Bacteroidetes. Functional profile of sanguinarine-based phytobiotic supplemented birds microbiota was distinct from CTR functional profile. NE challenge was associated with a significant increase in cecal propionic acid, while sanguinarine-based phytobiotic supplementation resulted in an increase in cecal acetic acid.

Phlorizin ameliorates obesity-associated endotoxemia and insulin resistance in high-fat diet-fed mice by targeting the gut microbiota and intestinal barrier integrity

Phlorizin (PHZ) is one of phytonutrients in apples that contributes to the health-promoting effect implicated by the saying, 'an apple a day keeps the doctor away'. PHZ was firstly identified as a competitive inhibitor of sodium-glucose co-transporters-2 (SGLT2); however, its low bioavailability makes it hard to fully explain its pharmacological mechanisms. This study aimed to investigate the ameliorating effect of PHZ on high-fat diet (HFD)-induced obesity via modulating the "gut microbiota-barrier axis". Firstly, C57BL/6 J mice were fed a normal chow diet (NCD) or HFD coadministered with or without PHZ for 12 weeks. Our results showed that PHZ supplementation significantly reduced HFD-induced body weight gain (P < .001), alleviated metabolic disorders (MDs) like insulin resistance (P < .001) and elevation of serum lipopolysaccharides (LPS) (P < .001), attenuated HFD-induced gut microbiota alterations, enhanced short-chain fatty acids (SCFAs) production (P < .001), and inhibited fecal LPS production (P < .001). To investigate the role of the fecal microbiota in the observed beneficial effects, a fecal microbiota transplantation (FMT) experiment was performed by transplanting the feces of the four groups of mice (as donor mice) daily collected from the fourth week to a new batch of acclimatized HFD-fed mice. Our results confirmed that feeding the gut contents of the PHZ-modulated mice could attenuate HFD-induced MDs, accompanied by enhanced glucagon-like peptide 2 (GLP-2) secretion (P < .001) and restoration of HFD-induced damage in the gut epithelial barrier. This study has provided evidence that the "gut microbiota-barrier axis" was an alternative target for the anti-obesity effect of PHZ. This work has also provided an explanation for the high efficacy of PHZ despite the low bioavailability, and PHZ holds great potential to be developed as a functional food ingredient.

The Effects of Non-Nutritive Artificial Sweeteners, Aspartame and Sucralose, on the Gut Microbiome in Healthy Adults: Secondary Outcomes of a Randomized Double-Blinded Crossover Clinical Trial

Non-nutritive artificial sweeteners (NNSs) may have the ability to change the gut microbiota, which could potentially alter glucose metabolism. This study aimed to determine the effect of sucralose and aspartame consumption on gut microbiota composition using realistic doses of NNSs. Seventeen healthy participants between the ages of 18 and 45 years who had a body mass index (BMI) of 20–25 were selected. They undertook two 14-day treatment periods separated by a four-week washout period. The sweeteners consumed by each participant consisted of a standardized dose of 14% (0.425 g) of the acceptable daily intake (ADI) for aspartame and 20% (0.136 g) of the ADI for sucralose. Faecal samples collected before and after treatments were analysed for microbiome and short-chain fatty acids (SCFAs). There were no differences in the median relative proportions of the most abundant bacterial taxa (family and genus) before and after treatments with both NNSs. The microbiota community structure also did not show any obvious differences. There were no differences in faecal SCFAs following the consumption of the NNSs. These findings suggest that daily repeated consumption of pure aspartame or sucralose in doses reflective of typical high consumption have minimal effect on gut microbiota composition or SCFA production.

Detrimental effect on the gut microbiota of 1,2-dicarbonyl compounds after in vitro gastro-intestinal and fermentative digestion

This study investigated the stability of dicarbonyl compounds (DCs), 3-deoxyglucosone (3-DG), glyoxal (GO) and methylglyoxal (MGO) during simulated gastrointestinal digestion processes and the impact these compounds have on the gut microbiota. DCs pass almost unaltered through the in-vitro gastrointestinal digestion phases (concentration loss: 11% for 3-DG, 24% for GO and MGO) and have an effect on the fermentative digestion process, reducing the total gut bacterial population up to 6 Log₁₀ units. Previous studies have shown no antimicrobial activity for 3-DG, however, for the first time it has been shown that when incubated with faecal bacteria 3-DG strongly depressed this microbial community. The influence of dicarbonyl compounds on the anaerobic fermentation processes was confirmed by the reduced production of short-chain fatty acids. Considering the modern Western diet, characterised by high consumption of ultra-processed foods rich in dicarbonyl compounds, this could lead to a reduction of bacteria important for the microbiome.

In Vitro Digestion and Fermentation by Human Fecal Microbiota of Polysaccharides from Flaxseed

The digestion of flaxseed polysaccharides (FSP) in simulated saliva, gastric and small intestine conditions was assessed, as well as in vitro fermentation of FSP by human gut microbiota. FSP was not degraded in the simulated digestive systems (there was no change in molecular weight or content of reducing sugars), indicating that ingested FSP would reach the large intestine intact. Changes in carbohydrate content, reducing sugars and culture pH suggested that FSP could be broken down and used by gut microbiota. FSP modulated the composition and structure of the gut microbiota by altering the Firmicutes/Bacteroidetes ratio and increasing the relative abundances of Prevotella, Phascolarctobacterium, Clostridium and Megamonas, which can degrade polysaccharides. Meanwhile, FSP fermentation increased the concentration of short-chain fatty acids, especially propionic and butyric acids. Our results indicate that FSP might be developed as a functional food that benefits gut health.

Natural deep eutectic solvent (NADES)-based blueberry extracts protect against ethanol-induced gastric ulcer in rats

Blueberry is a polyphenol-rich fruit bearing great bioactive potential. Natural deep eutectic solvents (NADES) emerged as putatively biocompatible solvents that could substitute for toxic organic solvents in the extraction of fruit phenolic compounds for developing nutraceuticals or functional foods. Therefore, the aim of this study was to investigate the gastroprotective effects and the biocompatibility of a blueberry crude extract (CE) obtained using NADES and of the extract fractions (anthocyanin-rich fraction - ARF; non-anthocyanin phenolic fraction - NAPF) in a model of ethanol-induced gastric ulcer in rats. CE was the NADES-containing, ready-to-use extract that was obtained using choline chloride:glycerol:citric acid NADES (0.5:2:0.5 M ratio). ARF and NAPF were the NADES-free fractions obtained by solid phase purification of CE and were investigated to identify the bioactive fraction responsible for the effects of CE. Animals were treated for 14 days with water, NADES vehicle, CE, ARF, NAPF or lansoprazole (intragastric) and then received ethanol to induce gastric ulcer. CE decreased ulcer index and preserved the integrity of gastric mucosa. The pretreatment with CE or ARF reduced glutathione depletion and the inflammatory response. All treatments, including NADES vehicle reduced protein oxidation and nitric oxide overproduction in ethanol-treated rats. Additionally, ARF increased short-chain fatty acids in feces. These findings suggest that NADES can be used to obtain biocompatible extracts of blueberry that exhibit gastroprotective effects with no need of solvent removal. The gastroprotective effects were mainly associated to ARF but NAPF and even NADES vehicle also contributed to some protective effects.

The role of gut microbiota (GM) and GM-related metabolites in diabetes and obesity. A review of analytical methods used to measure GM-related metabolites in fecal samples with a focus on metabolites' derivatization step

Disruption of gut microbiota (GM) composition is increasingly related to the pathogenesis of various metabolic diseases. Additionally, GM is responsible for the production and transformation of metabolites involved in the development of metabolic disorders, such as obesity and type 2 diabetes mellitus (T2DM). The current state of knowledge regarding the composition of GM and GM-related metabolites in relation to the progress and development of obesity and T2DM is presented in this review. To understand the relationships between GM-related metabolites and the development of metabolic disorders, their accurate qualitative and quantitative measurement in biological samples is needed. Feces represent a valuable biological matrix which composition may reflect the health status of the lower gastrointestinal tract and the whole organism. Mass spectrometry (MS), mainly in combination with gas chromatography (GC) or liquid chromatography (LC), is commonly used to measure fecal metabolites. However, profiling metabolites in such a complex matrix as feces is challenging from both analytical chemistry and biochemistry standpoints. Chemical derivatization is one of the most effective methods used to overcome these problems. In this review, we provide a comprehensive summary of the derivatization methods of GM-related metabolites prior to GC-MS or LC-MS analysis, which have been published in the last five years (2015-2020). Additionally, analytical methods used for the analysis of GM-related metabolites without the derivatization step are also presented.

Marine polysaccharides from Gelidium pacificum Okamura and Cereus sinensis reveal prebiotic functions

Many marine polysaccharides as prebiotics can promote host health by modulating gut microbiota. This study investigated the beneficial effects of purified marine plant-derived Gelidium pacificum Okamura polysaccharide (GPOP-1) and marine animal-derived Cereus sinensis polysaccharide (CSP-1) on normal mice by modulating gut microbiota. The composition and diversity of gut microbiota were evaluated using 16S rRNA high-throughput sequencing. The results showed that GPOP-1 and CSP-1 altered the composition of the gut microbiota and promoted the growth of beneficial bacteria. At the genus level, GPOP-1 increased the relative abundance of Bacteroides, Phascolarctobacterium, and decreased the relative abundance of Ruminococcus, Helicobacter, Allobaculum, Dorea and AF12. While CSP-1 increased the relative abundance of Coprococcus, Adlercreutzia, Roseburia, Phascolarctobacterium, and decreased the relative abundance of Bacteroides, Ruminococcus and Oscillospira. The changes in the gut microbiota may affect the body weight, immune organ index and the production of short-chain fatty acids in normal mice. Compared to the normal control group, GPOP-1 decreased average weight gain while CSP-1 increased average weight gain. Furthermore, both GPOP-1 and CSP-1 significantly increased thymus and spleen indexes and total short chain fatty acids production in mice. In summary, GPOP-1 and CSP-1 exerted prebiotic effects on normal mice.

Astaxanthin-Shifted Gut Microbiota Is Associated with Inflammation and Metabolic Homeostasis in Mice

BACKGROUND

Astaxanthin is a red lipophilic carotenoid that is often undetectable in human plasma due to the limited supply in typical Western diets. Despite its presence at lower than detectable concentrations, previous clinical feeding studies have reported that astaxanthin exhibits potent antioxidant properties.

OBJECTIVE

We examined astaxanthin accumulation and its effects on gut microbiota, inflammation, and whole-body metabolic homeostasis in wild-type C57BL/6 J (WT) and β-carotene oxygenase 2 (BCO2) knockout (KO) mice.

METHODS

Six-wk-old male and female BCO2 KO and WT mice were provided with either nonpurified AIN93M (e.g., control diet) or the control diet supplemented with 0.04% astaxanthin (wt/wt) ad libitum for 8 wk. Whole-body energy expenditure was measured by indirect calorimetry. Feces were collected from individual mice for short-chain fatty acid assessment. Hepatic astaxanthin concentrations and liver metabolic markers, cecal gut microbiota profiling, inflammation markers in colonic lamina propria, and plasma samples were assessed. Data were analyzed by 3-way ANOVA followed by Tukey's post hoc analysis.

RESULTS

BCO2 KO but not WT mice fed astaxanthin had ∼10-fold more of this compound in liver than controls (P < 0.05). In terms of the microbiota composition, deletion of BCO2 was associated with a significantly increased abundance of Mucispirillum schaedleri in mice regardless of gender. In addition to more liver astaxanthin in male KO compared with WT mice fed astaxanthin, the abundance of gut Akkermansia muciniphila was 385% greater, plasma glucagon-like peptide 1 was 27% greater, plasma glucagon and IL-1β were 53% and 30% lower, respectively, and colon NOD-, LRR- and pyrin domain-containing protein 3 (NLRP3) inflammasome activation was 23% lower (all P < 0.05) in male KO mice than the WT mice.

CONCLUSIONS

Astaxanthin affects the gut microbiota composition in both genders, but the association with reductions in local and systemic inflammation, oxidative stress, and improvement of metabolic homeostasis only occurs in male mice.

Short-Chain Fatty Acid Production by Gut Microbiota from Children with Obesity Differs According to Prebiotic Choice and Bacterial Community Composition

Pediatric obesity remains a public health burden and continues to increase in prevalence. The gut microbiota plays a causal role in obesity and is a promising therapeutic target. Specifically, the microbial production of short-chain fatty acids (SCFA) from the fermentation of otherwise indigestible dietary carbohydrates may protect against pediatric obesity and metabolic syndrome. Still, it has not been demonstrated that therapies involving microbiota-targeting carbohydrates, known as prebiotics, will enhance gut bacterial SCFA production in children and adolescents with obesity (age, 10 to 18 years old). Here, we used an in vitro system to examine the SCFA production by fecal microbiota from 17 children with obesity when exposed to five different commercially available over-the-counter (OTC) prebiotic supplements. We found microbiota from all 17 patients actively metabolized most prebiotics. Still, supplements varied in their acidogenic potential. Significant interdonor variation also existed in SCFA production, which 16S rRNA sequencing supported as being associated with differences in the host microbiota composition. Last, we found that neither fecal SCFA concentration, microbiota SCFA production capacity, nor markers of obesity positively correlated with one another. Together, these in vitro findings suggest the hypothesis that OTC prebiotic supplements may be unequal in their ability to stimulate SCFA production in children and adolescents with obesity and that the most acidogenic prebiotic may differ across individuals.IMPORTANCE Pediatric obesity remains a major public health problem in the United States, where 17% of children and adolescents are obese, and rates of pediatric "severe obesity" are increasing. Children and adolescents with obesity face higher health risks, and noninvasive therapies for pediatric obesity often have limited success. The human gut microbiome has been implicated in adult obesity, and microbiota-directed therapies can aid weight loss in adults with obesity. However, less is known about the microbiome in pediatric obesity, and microbiota-directed therapies are understudied in children and adolescents. Our research has two important findings: (i) dietary prebiotics (fiber) result in the microbiota from adolescents with obesity producing more SCFA, and (ii) the effectiveness of each prebiotic is donor dependent. Together, these findings suggest that prebiotic supplements could help children and adolescents with obesity, but that these therapies may not be "one size fits all."

Antibiotic Treatment Reduces the Health Benefits of Soy Protein

SCOPE

Soy protein is a high-quality protein and its consumption has been associated with a reduction of serum cholesterol and triglycerides and an improvement in insulin resistance. However, it is not known whether the effects of soy protein are mediated by the gut microbiota. Thus, the aim of this study is to assess whether using antibiotics to partially eradicate the gut microbiota can prevent the beneficial effects of soy protein in rats.

METHODS AND RESULTS

Thus, rats are fed one of the following diets for 16 weeks: casein control, soy protein control, high-fat casein, and high-fat soy protein. The rats are then treated for 4 weeks with antibiotics. Body weight and composition, energy expenditure, glucose tolerance test, metabolic endotoxemia, and gut microbiota are measured before and after treatment with antibiotic. The results show that soy protein consumption decreases weight gain, body fat, metabolic endotoxemia, and increases energy expenditure and glucose tolerance. Antibiotic treatment suppresses all these metabolic effects. These changes are accompanied by modifying the diversity and taxonomy of the gut microbiota.

CONCLUSION

In conclusion, the evidence suggests that the health benefits of soy protein are partly dependent of the gut microbiota.

Milk whey from different animal species stimulates the in vitro release of CCK and GLP-1 through a whole simulated intestinal digestion

Milk whey is effective in enhancing satiety mainly due to its protein composition. Peptides and amino acids derived from digestion of whey protein can act as suppressants of appetite by stimulation of receptors of satiety gut hormones. But, the protein fraction of whey can vary depending on species of animal, season, lactation period, etc. The aim of this study is to evaluate the satiety effect of milk whey from different species of ruminants (cow, sheep, goat and a mixture of them) through a simulated in vitro digestion, which performed the whole gastrointestinal process, from oral digestion to colonic fermentation. The satiety effect of each sample was measured by the production of satiating hormones (CCK and GLP-1) secreted by enteroendocrine cell line (STC-1) after 2 hours of incubation with non-digested, digested and fermented whey. Digested samples have shown to be potent CCK and GLP-1 secretagogues followed by fermented and non-digested samples, showing that the last one showed a weak hormone stimulation. Digested goat whey was the most efficient stimulator of GLP-1 (86.33 ± 4.55 pg mL^-1) and fermented mixture whey produced the major release of CCK (80.78±1.81 pg mL^-1). This study demonstrates that milk whey is a suitable ingredient to stimulate satiety through the effect of peptides, amino acids produced from digestion, and metabolites released by fermentation.

Intake of Ganoderma lucidum polysaccharides reverses the disturbed gut microbiota and metabolism in type 2 diabetic rats

Ganoderma lucidum polysaccharides (GLP), a kind of medicinal mushrooms, were widely used in southeastern countries with putative anti-diabetic effects. In order to unravel the underlying mechanism of its anti-diabetic effect, this study examines the effects of GLP on gut microbiota composition and functions in type 2 diabetes mellitus (T2DM) status. In this study, the effects of GLP on the gut microbiota and fecal metabolites in high-fat diet and streptozotocin-induced T2DM rats were examined by 16S rDNA sequencing and 1H NMR profiling. As a result, administration of GLP led to significant decreases in the levels of fasting blood glucose and insulin. Moreover, GLP treatment reduced the abundance of harmful bacteria, such as Aerococcus, Ruminococcus, Corynebactrium and Proteus, and increased the level of Blautia, Dehalobacterium, Parabacteroides and Bacteroides. The PICRUSt analysis indicated that GLP could restore the disturbed amino acids metabolism, carbohydrates metabolism, inflammatory substances metabolism and nucleic acid metabolism of gut bacterial community in T2DM rats and most metabolic changes observed by metabolomics analysis were consistent with these consequences. Taken collectively, GLP can restore the disordered gut microbiota of T2DM rats to a normal level and modify metabolites of the host to realize its antidiabetic effects.

Vaginimicrobium propionicum gen. nov., sp. nov., a novel propionic acid bacterium derived from human vaginal discharge

A Gram-stain-positive anaerobic rod-shaped bacterium, designated strain Marseille-P3275^T, was isolated using culturomics from the vaginal discharge of healthy French woman. Marseille-P3275^T was non-motile and did not form spores. Cells had neither catalase nor oxidase activity. The major fatty acids were C_16 : 0 (29 %), C_18:1ω9 (18 %), and iso-C_15 : 0 (17 %). The genomic DNA G+C content was 50.64 mol%. The phylogenetic analysis based on 16S rRNA gene sequence indicated that Marseille-P3275^T was related to members of the family Propionibacteriaceae (between 90.32-92.92 % sequence similarity) with formation of a clade with the monospecific genus Propionimicrobium (type species Propionimicrobium lymphophilum). On the basis of these phylogenetic and phenotypic differences, Marseille-P3275^T was classified in a novel genus, Vaginimicrobium, as Vaginimicrobium propionicum gen. nov., sp. nov. The type strain is Marseille-P3275^T (=CSUR P3275^T=CECT 9677^T).

Gas Chromatography Detection Protocol of Short-chain Fatty Acids in Mice Feces

Short-chain fatty acids (SCFAs), which are formed mainly by bacteria fermenting undigested carbohydrates in the colon, they are based on the number of carbon atoms in the carbon chain. Organic fatty acids with less than 6 carbon atoms are called short-chain fatty acids. SCFAs are closely related to various aspects of the human body, so more and more researchers concentrate on SCFAs. This protocol describes, a direct injection gas chromatography detection method with a pretreatment method for extracting SCFA from mice feces by combining acidification. The corresponding sample limit of quantization (LOQ) and limit of detection (LOD) are 0.8-1.0 mg/L and 0.5-0.8 mg/L, respectively. The correlation coefficient of calibration curve is greater than 0.999. The recovery rate of the spiked standard is 80%-102%. This method can be used to analyze and determine SCFAs in mice feces. Therefore, this is an economical, effective and reproducible method for SCFAs measurement in mice samples.

Fermentation of Chicory Fructo-Oligosaccharides and Native Inulin by Infant Fecal Microbiota Attenuates Pro-Inflammatory Responses in Immature Dendritic Cells in an Infant-Age-Dependent and Fructan-Specific Way

SCOPE

Inulin-type fructans are commonly applied in infant formula to support development of gut microbiota and immunity. These inulin-type fructans are considered to be fermented by gut microbiota, but it is unknown how fermentation impacts immune modulating capacity and whether the process of fermentation is dependent on the infant's age.

METHODS AND RESULTS

The in vitro fermentation of chicory fructo-oligosaccharides (FOS) and native inulin are investigated using pooled fecal inocula of two- and eight-week-old infants. Both inocula primarily utilize the trisaccharides in FOS, while they almost completely utilize native inulin with degree of polymerization (DP) 3-8. Fecal microbiota of eight-week-old infants degrades longer chains of native inulin up to DP 16. This correlates with a higher abundance of Bifidobacterium and higher production of acetate and lactate after 26 h of fermentation. Fermented FOS and native inulin attenuate pro-inflammatory cytokines produced by immature dendritic cells (DCs), but profiles and magnitude of attenuation are stronger with native inulin than with FOS.

CONCLUSION

The findings demonstrate that fermentation of FOS and native inulin is dependent on the infant's age and fructan structure. Fermentation enhances attenuating effects of pro-inflammatory responses in DCs, which depend mainly on microbial metabolites formed during fermentation.

Bacillus subtilis PB6 based probiotic supplementation plays a role in the recovery after the necrotic enteritis challenge

In poultry production, birds are raised under intensive conditions, which can enable rapid spread of infections, with Clostridium perfringens-caused necrotic enteritis (NE) being one of the most devastating for the industry. The current investigation was conducted to evaluate the effectiveness of Bacillus subtilis PB6 probiotic supplementation on bird’s post NE recovery, based on chicken performance, cecal microbiota composition, ileum histomorphometric measurements, and short-chain fatty acid production in the cecum of the birds that were challenged with NE mid-production. Birds were split into four groups, including a negative control, positive control challenged with C. perfringens, group supplemented with B. subtilis probiotic, and NE challenged birds supplemented with B. subtilis probiotic. Following NE challenge birds were allowed to reach the end of production time at 40 days, and samples were collected to estimate if probiotic supplementation resulted in better post-NE recovery. Intestinal lesion score across the duodenum, jejunum, and ileum indicated that at the end of production timeline NE challenged birds supplemented with B. subtilis probiotic had lower intestinal lesion scores compared to NE challenged birds without probiotic supplementation implying improved recovery. Probiotic supplementation improved performance of NE challenged birds only in the post-NE recovery stage. NE challenged birds had a significant increase in cecal propionic acid, which was not observed in NE challenged birds supplemented with B.subtilus. Both B. subtilis supplemented groups (challenged and unchanged) were characterized by a significant rise in cecal acetic and butyric acid. Our results demonstrate that B. subtilis supplementation can assist the birds in dealing with NE outbreak and long term recovery.

Changes in the Microbiome of Cryptosporidium-Infected Mice Correlate to Differences in Susceptibility and Infection Levels

Cryptosporidium spp. are opportunistic protozoan parasites that infect epithelial cells of the small intestine, causing diarrheal illness in humans. Differences in severity may be due to the immunological status of the host, malnutrition or prior exposure but may also be due to differences in the host gut flora. We examined changes in bacterial flora following antibiotic treatment to determine how cryptosporidial infections and gut integrity were affected by alterations in the microbiome. DNA was extracted from fecal and intestinal samples during peak infection. V4 region amplicons were generated and sequenced using 16sRNA on an Illumina MiSeq. Species evenness and richness were estimated using the Shannon diversity index. There was a significant decrease in anaerobes and overgrowth of Enterobacteriaceae in mice treated with cloxacillin. We also examined levels of short-chain fatty acids in fecal samples. There was a significant decrease in acetate, propionate, and butyrate in these same mice. Concurrent with the shift in bacterial infection was a significant increase in severity of cryptosporidial infection and increase in gut permeability. Treatment with other antibiotics significantly altered the microbiome but did not change the infection, suggesting that specific alterations in the host microbiome allow for more favorable growth of the parasite.

Alterations in the Gut Microbiome and Suppression of Histone Deacetylases by Resveratrol Are Associated with Attenuation of Colonic Inflammation and Protection Against Colorectal Cancer

Inflammatory bowel disease (IBD) is known to significantly increase the risk for development of colorectal cancer (CRC), suggesting inflammation and cancer development are closely intertwined. Thus, agents that suppress inflammation may prevent the onset of cancer. In the current study, we used resveratrol, an anti-inflammatory stilbenoid, to study the role of microbiota in preventing inflammation-driven CRC. Resveratrol treatment in the azoxymethane (AOM) and dextran sodium sulphate (DSS) CRC murine model caused an increase in anti-inflammatory CD4 + FOXP3 + (Tregs) and CD4 + IL10 + cells, a decrease in proinflammatory Th1 and Th17 cells, and attenuated CRC development. Gut microbial profile studies demonstrated that resveratrol altered the gut microbiome and short chain fatty acid (SCFA), with modest increases in n-butyric acid and a potential butyrate precursor isobutyric acid. Fecal transfer from resveratrol-treated CRC mice and butyrate supplementation resulted in attenuation of disease and suppression of the inflammatory T cell response. Data also revealed both resveratrol and sodium butyrate (BUT) were capable of inhibiting histone deacetylases (HDACs), correlating with Treg induction. Analysis of The Cancer Genome Atlas (TCGA) datasets revealed increased expression of Treg-specific transcription factor FoxP3 or anti-inflammatory IL-10 resulted in an increase in 5-year survival of patients with CRC. These data suggest that alterations in the gut microbiome lead to an anti-inflammatory T cell response, leading to attenuation of inflammation-driven CRC.

Polysaccharide from wild morels alters the spatial structure of gut microbiota and the production of short-chain fatty acids in mice

Polysaccharides from morels possess many characteristics beneficial to health, such as anti-tumor and immunomodulatory activities. The gut microbiota plays a critical role in the modulation of immune function. However, the impact of morel polysaccharides on the gut microbiota has not yet been explored. In this study, a high-throughput pyrosequencing technique was used to investigate the effects of MP, a new heteropolysaccharide extracted from wild morels, on the diversity and composition of microbiota along the intestine in mice, as well as the production of short-chain fatty acids (SCFAs). The results showed that MP treatment increased the number of operational taxonomic unit (OTUs) and diversity along the intestine, especially in the small intestine. MP treatment induced a significant decrease in the number of Firmicutes and a significant increase in the number of Bacteroidetes in the small intestine microbiota. It was also observed that the relative abundance of SCFA-producing bacteria, especially Lachnospiraceae, was increased in both the cecum and colon of MP-treated mice. Moreover, MP promoted the production of SCFAs in mice. These results provide a foundation for further understanding the health benefits conferred by morel polysaccharides.

Organic acid blend supplementation increases butyrate and acetate production in Salmonella enterica serovar Typhimurium challenged broilers

The burden of enteric pathogens in poultry is growing after the ban of antibiotic use in animal production. Organic acids gained attention as a possible alternative to antibiotics due to their antimicrobial activities, improved nutrient metabolism and performance. The current study was conducted to evaluate the effectiveness of organic acid blend on broilers cecal microbiota, histomorphometric measurements, and short-chain fatty acid production in Salmonella enterica serovar Typhimurium challenge model. Birds were divided into four treatments, including a negative control, positive control challenged with S. Typhimurium, group supplemented with an organic acid blend, and birds supplemented with organic acid blend and Salmonella challenged. Results illustrate significant differences in feed conversion ratios and production efficiency factor between treatment groups, however, the influence of organic acid supplement was marginal. Organic acid blend significantly increased cecal acetic and butyric acids concentrations when compared to unsupplemented groups and resulted in minor alterations of intestinal bacterial communities.

Endo-1,3(4)-β-Glucanase-Treatment of Oat β-Glucan Enhances Fermentability by Infant Fecal Microbiota, Stimulates Dectin-1 Activation and Attenuates Inflammatory Responses in Immature Dendritic Cells

Background: Non-digestible carbohydrates are added to infant formula to mimic the effects of human milk oligosaccharide by acting as prebiotics and stimulating the immune system. Although not yet used in infant formulas, β-glucans are known to have beneficial health effects, and are therefore of potential interest for supplementation. Methods and results: We investigated the in vitro fermentation of native and endo-1,3(4)-β-glucanase-treated oat β-glucan using pooled fecal inocula of 2- and 8-week-old infants. While native oat β-glucan was not utilized, both inocula specifically utilized oat β-glucan oligomers containing β(1→4)-linkages formed upon enzyme treatment. The fermentation rate was highest in the fecal microbiota of 2-week-old infants, and correlated with a high lactate production. Fermentation of media supplemented with native and enzyme-treated oat β-glucans increased the relative abundance of Enterococcus and attenuated pro-inflammatory cytokine production (IL-1β, IL-6, TNFα) in immature dendritic cells. This attenuating effect was more pronounced after enzyme treatment. This attenuation might result from the enhanced ability of fermented oat β-glucan to stimulate Dectin-1 receptors. Conclusion: Our findings demonstrate that endo-1,3(4)-β-glucanase treatment enhances the fermentability of oat β-glucan and attenuates pro-inflammatory responses. Hence, this study shows that especially enzyme-treated oat β-glucans have a high potential for supplementation of infant formula.

Effects of soybean hulls and lignocellulose on performance, nutrient digestibility, microbial metabolites and immune response in piglets

A feeding trial with 96 piglets was performed to investigate the effect of added soluble (SDF) and insoluble dietary fibre (IDF) sources on performance, apparent total tract digestibility (ATTD), concentration of microbial metabolites and pro-inflammatory marker genes as indicators for immune response. Piglets were allotted to four treatments (T): T1 control, T2 with soybean hulls (IDF/SDF: 8.35) and T3 and T4 with two different kinds of lignocellulose (IDF/SDF: >70). Diets were isofibrous for their value of total dietary fibre to underline the particular physicochemical properties of fibre sources. No differences were observed regarding average daily feed intake, average daily gain (ADG), feed conversion ratio and body weight, while T2 expressed higher ADG in the grower phase (day 14-54) vs. T3. Soybean hulls (T2) resulted in higher ATTD of dry matter and organic matter vs. T4; ether extract vs. T1 and neutral detergent fibre vs. T1, T2 and T3. The concentration of short chain fatty acids did not differ among treatments. Ileal digesta in T2 generated higher amounts of cadaverine vs. T3 and T4, likewise T1 vs. T4. Finally, no impact on immune response was detected. In conclusion, soybean hulls affected ATTD positively and lignocellulose prevented the formation of cadaverine, no overall direct response of SDF nor of IDF for the inclusion level  were observed.

Perturbation of the lipid metabolism and intestinal inflammation in growing pigs with low birth weight is associated with the alterations of gut microbiota

Low birth weight (LBW) is accompanied by metabolic dysfunction, chronic inflammation and gut microbiota perturbation in piglets during early life. Regulating gut microbiota structure can indirectly or directly affect gut health and the host's metabolism. However, whether gut microbiota dysbiosis impact lipid metabolism and inflammation progression in the LBW pigs later in life is unclear. In the present study, we investigated the role of gut microbiota on homeostasis in organisms using young pigs as a model. The plasma concentrations of High-density lipoproteins (HDLC) and pro-inflammatory cytokines such as Interleukin 6 (IL-6), Tumor necrosis factor alpha (TNF-α) and Interleukin 18 (IL-18) were increased in LBW pigs. The bacterial composition was modified dramatically in LBW group in association with an increase in propionate, butyrate and Short-chain fatty acids (SCFAs) in the ileal digesta. LBW impaired intestine results in damaged Fatty acid-binding protein 1 (FABP2) and Fatty acid-binding protein 4 (FABP4) expressions, and the inhibition of Free fatty acid receptor 1 (FFAR1), Free fatty acid receptor 2 (FFAR2) and G protein-coupled receptor 119 (GPR119) expressions, causing inefficient SCFAs absorption. Meanwhile, the physical barrier and chemical barrier related to functional gene expressions of Occludin, Claudin-1, Mucin 1 (MUC1) and Mucin 2 (MUC2) in both ileum and colon were decreased in the LBW pigs. The genera of Blautia, Bifidobacterium, Subdoligranulum and Coprococcus 3 in the ileum were correlated positively with lipid metabolic dysfunction and pro-inflammatory response in LBW pigs. Collectively, the gut microbiota is critical for perturbation of lipid metabolism and inflammatory progression in LBW pigs, which suggests the interventions for modulating bacterial communities may be therapeutically beneficial for metabolic diseases and chronic inflammation.

Evaluation of fruta-do-lobo (Solanum lycocarpum St. Hill) starch on the growth of probiotic strains

Fruta-do-lobo (Solanum lycocarpum St. Hill) is a native fruit commonly used in Brazilian folk medicine as a hypoglycemic agent. These properties are attributed to their starch, mainly its resistant fraction. Resistant starch has shown to increases the growth of Bifidobacterium and Lactobacillus in the gut, even though not being selective for these strains. In this scenario, this study aimed to investigate the potential prebiotic activity of fruta-do-lobo starch (FLS). FLS showed around 30% of resistant starch and their prebiotic potential was evaluated with five probiotic strains L. acidophilus (LA3 and LA5), L. casei (LC01) and B. animalis (BB12) and B. lactis (BLC1) in a concentration range of 1.0-2.0% of starch. In a preliminary screening, we evaluated, during 48 h, the viability of the starch with promoting growth agent. An increase in the growth of the probiotic strains tested was observed. We also evaluated the microorganism's metabolic activity by assessing the short-chain fatty acid (SCFA) production, using the best starch growth promotion conditions (2% of FLS and strains BLC1, LA5, and LC01). As expected, MRS and lactose were preferentially metabolized by BLC1, with the highest growth rates: 0.231 and 0.224 h^-1, respectively. However, for this strain, the FLS growth rate (0.222 h^-1) was 65% higher than FOS (0.144 h^-1). Also, for LA5 FLS promoted higher growth (0.150 h^-1) than FOS (0.135 h^-1). Additionally, FLS promoted acetate production. These data are promising and indicate that FLS may have prebiotic potential and more studies need to be done with pathogenic microorganisms.

Fast quantification of short-chain fatty acids in rat plasma by gas chromatography

Short-chain fatty acids (SCFAs) are the main metabolites of the intestinal flora and play an important role in the interaction between the intestinal flora and host metabolism. Therefore, reliable methods are needed to accurately measure SCFAs concentrations. SCFAs are commonly analyzed by gas chromatography-mass spectrometry (GC-MS), which requires lengthy sample treatments and a long run time. This study aimed to develop a fast GC method with formic acid pretreatment for SCFAs quantification in the plasma of rat. Baseline chromatographic resolution was achieved for three SCFAs (acetic, propionic, and butyric) within an analysis time of 10.5 min. The method exhibited good recovery for a wide range of concentrations with a low limit of detection for each compound. The relative standard deviations (RSDs) of all targeted compounds showed good intra- and interday precision (<10%). We used our method to measure SCFAs levels in plasma samples from rats fed with a high fructose diet (HFD) to test the accuracy of the developed method. It was shown that SCFAs are indeed affected negatively by a HFD (60% fructose). This method was successfully employed to accurately determine SCFAs in the rat plasma with minimum sample preparation. Results showed potential damage of HFD, which produced lower SCFAs. PRACTICAL APPLICATION: Increasingly, microbiota and gut health research are being conducted by many food scientists to elucidate the relationships among the factors of food components, particularly the nondigestible carbohydrates, food processing conditions, and potential health impact. This research provides a useful, rapid, and accurate method that can save time in the analysis of short-chain fatty acids, which are commonly analyzed in gut health research.

Effects of polysaccharides from wild morels on immune response and gut microbiota composition in non-treated and cyclophosphamide-treated mice

Polysaccharides isolated from mushrooms have been identified as potential prebiotics that could impact gut microbiota. In this study, a water-soluble polysaccharide (MP) extracted from wild morels was evaluated for its effects on the gut microbiota of non-treated and cyclophosphamide (CP)-treated mice. The results showed that MP restored the spleen weight and increased the counts of white blood cells and lymphocytes in the peripheral blood and spleen of the CP-treated mice. Mice treated with MP exhibited increased levels of short-chain fatty acid (SCFA)-producing bacteria, especially Lachnospiraceae, compared to normal mice, and increased levels of Bacteroidetes and SCFA-producing bacteria, especially Ruminococcaceae, compared to the CP-treated mice. Moreover, MP treatment increased the production of valeric acid and decreased the production of acetic acid in the non-treated mice and increased the production of acetic acid, propionic acid, butyric acid, and valeric acid in the CP-treated mice. These results show that MP is potentially good for health.

Pretreatment with Yeast-Derived Complex Dietary Polysaccharides Suppresses Gut Inflammation, Alters the Microbiota Composition, and Increases Immune Regulatory Short-Chain Fatty Acid Production in C57BL/6 Mice

BACKGROUND

β-Glucans (BGs), a group of complex dietary polysaccharides (CDPs), are available as dietary supplements. However, the effects of orally administered highly purified BGs on gut inflammation are largely unknown.

OBJECTIVES

The aim of this study was to investigate the impact of orally administering highly purified, yeast-derived BG (YBG; β-1,3/1,6-d-glucan) on susceptibility to colitis.

METHODS

Eight-week-old C57BL/6 (B6) mice were used in a series of experiments. Experiment (Expt) 1: male and female mice were treated every day, for 40 d, with saline (control) or 250 μg YBG, followed by 2.5% (wt:vol) dextran sulfate sodium (DSS) in drinking water during days 30-35; and colitis severity and intestinal immune phenotype were determined. Expt 2: female B6 mice were treated with saline or YBG for 30 d and intestinal immune phenotype, gut microbiota composition, and fecal SCFA concentrations were determined. Expt 3: female B6 mice were treated as in Expt 2, given drinking water with or without antibiotics [Abx; ampicillin (1 g/L), vancomycin (0.5 g/L), neomycin (1 g/L), and metronidazole (1 g/L)] during days 16-30, and gut immune phenotype and fecal SCFA concentrations were determined. Expt 4: female B6 Foxp3-green fluorescent protein (-GFP) reporter mice were treated as in Expt 3, and intestinal T-regulatory cell (Treg) frequencies and immune phenotypes were determined. Expt 5: female mice were treated as in Expt 1, given drinking water with or without antibiotics during days 16-40, and colitis severity and intestinal cytokine production were determined.

RESULTS

Compared with controls, the YBG group in Expt 1 exhibited suppressive effects on features of colitis, such as loss of body weight (by 47%; P < 0.001), shortening of colon (by 24%; P = 0.016), and histopathology severity score (by 45%; P = 0.01). The YBG group of Expt 2 showed a shift in the abundance of gut microbiota towards Bacteroides (by 16%; P = 0.049) and Verrucomicrobia (mean ± SD: control = 7.8 ± 0.44 vs. YBG = 21.0 ± 9.6%) and a reduction in Firmicutes (by 66%; P < 0.001). The YBG group also showed significantly higher concentrations of fecal SCFAs such as acetic (by 37%; P = 0.016), propionic (by 47%; P = 0.026), and butyric (by 57%; P = 0.013) acids. Compared with controls, the YBG group of Expt 2 showed higher frequencies of Tregs (by 32%; P = 0.043) in the gut mucosa. Depletion of gut microbiota in the YBG group of mice caused diminished fecal SCFA concentrations (Expt 3) and intestinal Treg frequencies (Expt 4). Compared with the YBG group, the YBG-(Abx) group of Expt 5 showed aggravated colitis features including loss of body weight (by >100%; P < 0.01) and colonic inflammation score (by 42%; P = 0.04).

CONCLUSIONS

Studies using B6 mice show that dietary BGs are beneficial for promoting intestinal health when the gut microbiota is intact. However, these CDPs may produce adverse effects if gut microbiota is compromised.

Fecal Metabolites As Non-Invasive Biomarkers of Gut Diseases

Recent studies have shown the importance of the human intestinal microbiome in maintaining a healthy gastrointestinal tract, as well as in the development of pathological processes. The intestinal microbiome manifests itself primarily as fecal metabolites. In the past decade, there has been growing interest in studying its composition, which for the most part had to do with the possibility of using the metabolomic analysis in clinical diagnosis. In contrast to the comprehensive description of blood serum, urine, saliva, and cerebrospinal fluid metabolites, data on fecal metabolites is sparse. Despite the instrumental and methodological achievements in the metabolomic analysis in general, the analysis of fecal metabolome remains less well developed, mainly because of the inhomogeneity of its composition and the lack of standardized methods for collecting, processing, and analyzing fecal samples. This review summarizes data on methods for studying and describing various groups of fecal metabolites. It also assesses their potential as tools in the diagnosis of gastrointestinal diseases.

Timing of complementary feeding is associated with gut microbiota diversity and composition and short chain fatty acid concentrations over the first year of life

BACKGROUND

Early introduction of complementary foods has been associated with various immune disorders, oxidative stress, and obesity in childhood. The gut microbiota and the short chain fatty acids (SCFAs) they produce are postulated to be on the causal pathway. The objective of this study was to determine if early complementary feeding (i.e. consumption of solids or non-water/formula liquids at or before 3 months) is prospectively associated with infant gut microbiota composition, diversity and SCFAs at 3 and 12 months of age in the Nurture birth cohort.

RESULTS

Mother-infant dyads in the early complementary feeding group (n = 18) had similar baseline characteristics to those in the later feeding group (n = 49). We assessed differential abundance of microbial taxa (measured by 16S rRNA gene sequencing of the V4 region) by timing of complementary feeding using beta-binomial regression models (considering a two-sided FDR corrected p-value of < 0.05 as significant), and we fittted linear regression models to assess the association between early complementary feeding and SCFA concentrations (quantified using gas chromatography). After multivariable adjustment for breastfeeding, delivery method, birth weight, and gestational age, there were 13 differentially abundant microbial amplicon sequence variants (ASVs) by timing of introduction to complementary foods at 3 months and 20 ASVs at 12 months. Infants introduced to complementary foods early (vs. later) had higher concentrations of the SCFA butyric acid (mean difference = 0.65, 95% CI: 0.27, 1.04, p < 0.01) and total SCFAs (mean difference = 38.8, 95% CI: 7.83, 69.7) at 12 months. Bilophila wadsworthia and Lachnospiraceae Roseburia were associated with early (vs. later) complementary feeding and with higher butyric acid concentrations at 3 and 12 months, respectively.

CONCLUSIONS

Our findings are consistent with the hypothesis that early (vs. later) introduction to complementary foods is associated with altered gut microbiota composition and butyric acid concentrations measured in stool until at least 1 year of age. Further research is needed to determine if these changes mediate future development of metabolic and immune conditions.

Consumption of a baked corn and bean snack reduced chronic colitis inflammation in CD-1 mice via downregulation of IL-1 receptor, TLR, and TNF-α associated pathways

Ulcerative colitis (UC) is a condition that has been rising in the number of cases around the world. Food products made from natural ingredients such as corn and common bean might serve as alternatives for the treatment of UC. This study aimed to assess the anti-inflammatory effect of the consumption of a baked corn and bean snack (CBS) in an in vivo model of UC using 2% dextran sodium sulfate (DSS) as inductor of colitis. CD-1 mice (45, n = 9/group) were randomly separated into 5 groups, treated for 6-weeks as follows: G1 (basal diet, BD), G2 (2% DSS), G3 (20 g CBS/body weight BW/day + BD), G4 (40 g CBS/BW/day + BD) and G5 (60 g CBS/BW/day + BD). BW, Disease Activity Index (DAI), and feces were collected throughout the treatment. After euthanasia, organs (spleen, liver, and colon) were excised and weighed. Feces were analyzed for β-glucuronidase (β-GLUC) activity and gas-chromatography. The colons were analyzed for histopathology, myeloperoxidase (MPO) activity, and gene analysis. At the end of treatments, among the DSS-induced groups, G3 exhibited the lowest BW losses (11.5%), MPO activity (10.4%) and β-GLUC (8.6%). G4 presented the lowest DAI (0.88), relative spleen weight, and histological inflammation score (p < 0.05). Compared to G2, CBS consumption significantly (p < 0.05) reduced serum TNF-α, IL-10, and MCP-1 levels. The fecal metabolome analysis ranked 9-decenoic acid, decane, and butyric acid as the main contributors of pathways associated with the β-oxidation of fatty acids. G4 showed the highest fecal/cecal contents of short-chain fatty acids among all the DSS-induced groups. For the gene expression, G4 was clustered with G1, showing a differential inhibition of the pro-inflammatory genes Il1r1, Il1a, Tlr4, Tlr2, and Tnfrsf1b. In conclusion, CBS consumption decreased the inflammatory state and reduced the expression of the IL-1 receptor, TLR, and TNF-α-associated pathways in DSS-induced UC in CD-1 mice.

Assessing the effect of starch digestion characteristics on ileal brake activation in broiler chickens

The objective of this research was to evaluate activation of the ileal brake in broiler chickens using diets containing semi-purified wheat (WS; rapidly and highly digested) and pea (PS; slowly and poorly digested) starch. Diets were formulated to contain six WS:PS ratios (100:0, 80:20, 60:40, 40:60, 20:80, 0:100) and each starch ratio was fed to 236 Ross 308 male broilers housed in 4 litter floor pens. At 28 d of age, the effect of PS concentration was assessed on starch digestion, digestive tract morphology, and digesta pH and short-chain fatty acid (SCFA) concentration. Glucagon-like peptide-1 (GLP-1) and peptide tyrosine-tyrosine (PYY) status were assessed in serum (ELISA) and via gene expression in jejunal and ileal tissue (proglucagon for GLP-1). Data were analyzed using regression analyses, and significance was accepted at P ≤ 0.05. Increasing dietary PS resulted in reduced starch digestibility in the small intestine, but had no effect in the colon. Crop content pH responded quadratically to PS level with an estimated minimum at 55% PS. Total SCFA increased linearly in the crop with PS level, but changed in a quadratic fashion in the ileum (estimated maximum at 62% PS). Ceacal SCFA concentrations were highest for the 80 and 100% PS levels. The relative empty weight (crop, small intestine, colon), length (small intestine) and content (crop jejunum, Ileum) of digestive tract sections increased linearly with increasing PS concentration. Dietary treatment did not affect serum GLP-1 or PYY or small intestine transcript abundance. In conclusion, feeding PS increased the presence of L-cell activators (starch, SCFA) and increased trophic development and content of the digestive tract, suggestive of L-cell activation. However, no direct evidence of ileal brake activation was found by measuring venous blood levels of GLP-1 or PYY or corresponding gene expression in small intestine tissue.

Indole-3-carbinol prevents colitis and associated microbial dysbiosis in an IL-22-dependent manner

Colitis, an inflammatory bowel disease, is caused by a variety of factors, but luminal microbiota are thought to play crucial roles in disease development and progression. Indole is produced by gut microbiota and is believed to protect the colon from inflammatory damage. In the current study, we investigated whether indole-3-carbinol (I3C), a naturally occurring plant product found in numerous cruciferous vegetables, can prevent colitis-associated microbial dysbiosis and attempted to identify the mechanisms. Treatment with I3C led to repressed colonic inflammation and prevention of microbial dysbiosis caused by colitis, increasing a subset of gram-positive bacteria known to produce butyrate. I3C was shown to increase production of butyrate, and when mice with colitis were treated with butyrate, there was reduced colonic inflammation accompanied by suppression of Th17 and induction of Tregs, protection of the mucus layer, and upregulation in Pparg expression. Additionally, IL-22 was increased only after I3C but not butyrate administration, and neutralization of IL-22 prevented the beneficial effects of I3C against colitis, as well as blocked I3C-mediated dysbiosis and butyrate induction. This study suggests that I3C attenuates colitis primarily through induction of IL-22, which leads to modulation of gut microbiota that promote antiinflammatory butyrate.

Development and validation of a GC-FID method for the analysis of short chain fatty acids in rat and human faeces and in fermentation fluids

Short-chain fatty acids (SCFAs) are gut microbiota metabolites recognized for their beneficial effects on the host organism. In this study, a simple and rapid sample preparation method combined to SCFAs analysis by direct injection and gas chromatography coupled with flame ionization detection (GC-FID), for the determination and quantification of eight SCFAs (acetic, propionic, i-butyric, butyric, i-valeric, valeric, i-caproic and caproic acids) in rat, mice and human faeces and in fermentation fluids samples, has been developed and validated. The method consists of extraction of the SCFAs by ethyl ether after acidification of the samples. The effect of the number of extractions has been assessed in order to optimize the procedure and to obtain a satisfactory yield for all the analyzed SCFAs. The increase of the extracted analytes quantity was significant passing from 1 to 2 and from 2 to 3 extractions (P < 0.05), while no significant differences were found performing 3, 4 or 5 extractions (P > 0.05). The SCFAs extracted are directly analyzed by GC-FID without derivatization and separated on a polyethylene glycol nitroterephthalic acid modified coated capillary column, with a chromatographic run time of 13 min. The proposed method showed good sensitivity, with limits of quantifications in the range 0.14-0.48 µM for SCFAs from propionic to caproic acids and 2.12 µM for acetic acid; recovery was between 80.8 and 108.8% and intraday and interday repeatability in the range 0.6-5.0% of precision (RSD, %) The optimized method is suitable for the quantitative analysis of SCFAs in real samples of rat, mouse and human faeces and in fermentation fluids, and it can be applied also to very small amount of faecal sample (20 mg).

Effect of a proanthocyanidin-rich polyphenol extract from avocado on the production of amino acid-derived bacterial metabolites and the microbiota composition in rats fed a high-protein diet

The consumption of high-protein diets (HPDs) increases the flux of undigested proteins moving to the colon. These proteins are hydrolyzed by bacterial proteases and peptidases, releasing amino acids, which in turn are metabolized by the intestinal microbiota (IM) for protein synthesis and production of various metabolites that can exert positive or deleterious effects, depending on their concentrations, at the colonic or systemic level. On the other hand, proanthocyanidins are polymers of flavan-3-ols which cannot be absorbed at the intestinal level, accumulating in the colon where they are fermented by the IM producing metabolites that appear beneficial for colonocytes and also at the peripheral level. This study evaluated the effect of an avocado peel polyphenol extract (AvPPE) rich in proanthocyanidins on the production of cecal bacterial metabolites and microbiota composition in rats fed a HPD. Compared with the normal-protein (NP) group, HPD did not markedly affect the body weight gain of the animals, but increased the kidney weight. Additionally, the HPD induced a higher cecal concentration of ammonia (NH4+/NH3), hydrogen sulfide (H2S) and branched-chain fatty acids (BCFAs). The supplementation with AvPPE attenuated the production of H2S and increased the production of indole. On the other hand, the HPD affected the composition of the cecal microbiota, increasing the relative abundance of the genera Bacteroides and Lactobacillus, while decreasing Prevotella. The AvPPE counteracted the increase induced by the HPD on the genus Lactobacillus, and increased the relative abundance of [Prevotella]. Our results contribute towards explaining the health-promoting effects of proanthocyanidin-rich dietary foodstuffs including fruits and vegetables.

Oat Bran Increased Fecal Butyrate and Prevented Gastrointestinal Symptoms in Patients With Quiescent Ulcerative Colitis-Randomized Controlled Trial

Background

Oat bran specifically increases colon butyrate concentrations and could therefore affect the progress of the disease in patients with ulcerative colitis (UC).

Methods

Patients with UC in remission were enrolled in a controlled multicenter study and randomized to eat oat bran or low-fiber wheat products.

Results

Ninety-four of the enrolled patients (n = 47 for both groups) completed the 24-week study. The oat bran group had significantly (P < 0.05) higher fecal butyrate concentrations and lower serum LDL levels, while deterioration of gastrointestinal symptoms was prevented, and subjective health maintained. The control diet significantly (P < 0.05) increased obstipation, reflux, and the symptom burden and had no effects on butyrate or LDL-cholesterol. The relapse rate was the same for both diets.

Conclusions

Oat bran was well tolerated when given to patients with quiescent UC.

The influence of indigestible protein on broiler digestive tract morphology and caecal protein fermentation metabolites

Indigestible dietary protein fermentation products have been suggested to negatively influence broiler performance due to their impact on health and digestive tract morphology. This study evaluated the digestive tract morphology and caecal protein fermentation metabolites of broiler fed 3 dietary protein levels (24%, 26% and 28%) with low or high indigestible protein (LIP, HIP). Two completely randomized 3 × 2 factorial trials were conducted with protein level (PL) and indigestible protein (IDP) as the main factors. In both trials, birds received six diets (24-LIP, 24-HIP, 26-LIP, 26-HIP, 28-LIP and 28 HIP) formulated with no medication. On day 5, trial 1 birds were vaccinated with Coccivac-B52, while trial 2 received no vaccine. Tissue and caecal samples were collected and caecal contents analysed for fermentation metabolites. Differences were considered significant when p ≤ .05. The LIP treatment caecal content in trial 1 at 14 days had greater histamine, agmatine and cadaverine levels, while HIP diets resulted in increased serotonin, tryptamine and spermidine. Histamine, serotonin and tryptamine at day 28 were not affected by IDP, and ammonia was not affected by treatments at day 14 or day 28. At day 14, HIP birds had lower total short-chain fatty acids, higher caecal pH and heavier pancreas, proventriculus, gizzard, jejunum and ileum weights. The same effects of IDP found in trial 1 were observed for histamine, agmatine, cadaverine, serotonin, tryptamine and spermidine at day 21 in trial 2. Trial 2 had a PL-by-IDP interaction influencing tyramine, spermidine (28-LIP > 24-LIP) and spermine with values increasing with PL for LIP diets and remaining constant for HIP diets. An interaction between PL and IDP was found for ammonia level and was similar to interactions for biogenic amines. In conclusion, dietary PL and IDP influence broiler caecal protein fermentation metabolites and those effects varied with coccidiosis vaccination and rearing environment.

Abundance of Gut Microbiota, Concentration of Short-Chain Fatty Acids, and Inflammatory Markers Associated with Elevated Body Fat, Overweight, and Obesity in Female Adolescents

BACKGROUND AND AIMS

Overweight is ever more prevalent in the pediatric population, and this cardiometabolic factor can be associated with inflammatory markers, gut microbiota composition, and short-chain fatty acid (SCFA) concentrations. The aim of this study is to evaluate to what extent the abundance of gut microbiota phyla, SCFA concentrations, and inflammatory markers are associated with elevated body fat percentage (BF%), overweight, and obesity in female adolescents.

METHODS

An experimental and comparative study was conducted with 96 girls 14 to 19 years old. They were divided into 3 groups: G1-eutrophic (EUT) and adequate BF%; G2-EUT and high BF%; and G3-overweight (OW) or obese (OB) and high BF%. Waist circumference (WC), waist to height ratio (WtHR), and neck circumference (NC) were analyzed as indicators of central visceral adiposity. The BF% was evaluated by DEXA equipment. A food frequency questionnaire was used to evaluate the main types of food consumed in a week. The abundance of the Firmicutes, Bacteroidetes, and Proteobacteria phyla was measured by real-time polymerase chain reaction (RT-qPCR), and the SFCA concentrations (acetic, butyric, and propionic) were determined by high-performance liquid chromatography (HPLC). The inflammatory markers leptin, tumor necrosis factor-alpha, interleukin-6, and high-sensitivity C-reactive protein (hs-CRP) were assessed.

RESULTS

Female adolescents in groups G2 and G3 had greater central visceral adiposity and leptin concentration than those in group G1. No association was found between gut microbiota phyla abundance and SFCA concentrations in any of the groups. WC and frequency of consumption of oily and fatty foods were associated with Firmicutes abundance and SFCA concentrations. Girls with high WC also had the greatest leptin (p < 0.001) and hs-CRP (p = 0.035) concentrations.

CONCLUSIONS

Inflammatory markers showed association with increased BMI and high BF% in female adolescents. The abundance of Firmicutes was associated with WC and NC, but not with BMI classification or BF%. Specifically, WC and the consumption of oils and fats showed correlation with SCFA concentrations. Different anthropometric indicators, such as NC and WC, should be incorporated into the clinical evaluation of the nutritional status of individuals in the adolescent population.

"Bowel on the Bench": Proof of Concept of a Three-Stage, In Vitro Fermentation Model of the Equine Large Intestine

The intestinal microbiota of the horse, an animal of huge economic and social importance worldwide, is essential to the health of the animal. Understanding the intestinal ecosystem and its dynamic interaction with diet and dietary supplements currently requires the use of experimental animals, with consequent welfare and financial constraints. Here, we describe the development and assessment, using multiple analytical platforms, of a three-vessel, continuous-flow, in vitro model of the equine hindgut. After inoculation of the model with fresh horse feces, the bacterial communities established in each vessel had a taxonomic distribution similar to that of the source animal. Short-chain fatty acid (SCFA) and branched-chain fatty acid (BCFA) production within the model at steady state was consistent with the expected bacterial function, although higher concentrations of some SCFA/BCFA relative to those in the ex vivo gut content were apparent. We demonstrate the intermodel repeatability and the ability of the model to capture some aspects of individual variation in bacterial community profiles. The findings of this proof-of-concept study, including recognition of the limitions of the model, support its future development as a tool for investigating the impact of disease, nutrition, dietary supplementation, and medication on the equine intestinal microbiota.IMPORTANCE The equine gut model that we have developed and describe has the potential to facilitate the exploration of how the equine gut microbiota is affected by diet, disease, and medication. It is a convenient, cost-effective, and welfare-friendly alternative to in vivo research models.

Phellinus linteus polysaccharide extract improves insulin resistance by regulating gut microbiota composition

The hypoglycemic effect of Phellinus linteus polysaccharide extract (PLPE) has been documented in several previous studies, but the functional interactions among PLPE, gut microbiota, and the hypoglycemic effect remain unclear. We examined the regulatory effect of PLPE on gut microbiota, and the molecular mechanism underlying improvement of insulin resistance, using a type 2 diabetic rat model. Here, 24 male Sprague-Dawley rats were randomly divided into four groups that were subjected to intervention of saline (normal and model control group), metformin (120 mg/kg.bw), and PLPE (600 mg/kg.bw) by oral administration. After 8 weeks of treatment, PLPE increased levels of short-chain fatty acids (SCFAs) by enhancing abundance of SCFA-producing bacteria. SCFAs maintained intestinal barrier function and reduced lipopolysaccharides content in blood, thereby helping to reduce systemic inflammation and reverse insulin resistance. Our findings suggest that PLPE (in which polysaccharides are the major component) has potential application as a prebiotic for regulating gut microbiota composition in diabetic patients.